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Highly purified platelet glucose-6-phosphate dehydrogenase (G6PD; D-glucose-6-phosphate:NADP+ 1-oxidoreductase, EC 1.1.1.49) can be modified in its isoelectric point and its molecular specific activity by extracts of some leukemic granulocytes. The "G6PD modifying factors" are relatively small molecules (molecular weight slightly under 5000), thermostable, dialyzable, and ultrafilterable. These molecules are destroyed by various endo- and exopeptidases and by serine enzymes present in crude extracts of leukocytes and commercial preparations of ribonuclease. The alterations of platelet G6PD due to the "G6PD modifying factors" are stable and not reversible by dialysis or further chromatography. The leukemic extracts which are able to modify G6PD also can modify the electrophoretic mobility and (or) the enzymatic activity of purified leukocyte pyruvate kinase, 6-phosphogluconate dehydrogenase, and glucosephosphate isomerase. The chemical nature of such modifications and their relationships with post-translational modifications which occur in leukemic or normal cells are discussed. |
Raising day-old chicks on diets lacking copper severely depressed the activity of lysyl oxidase, a copper metalloenzyme in connective tissue. Administration of CuSO4 either through the diet or through intraperitoneal injections restored the lysyl oxidase activity in aortic tissue. Two hours after the chicks received CuSO4 (1 mg/kg) the activity of lysyl oxidase rose rapidly to attain, within 4-6 hr, a new steady-state level which was five to 20 times higher than the basal (saline-injected) activity. Twenty hours after copper administration, activity was still higher, in some experiments double that achieved at 6 hr. Very low amounts of cycloheximide injected intraperitoneally 45 min before and 3 hr after copper suppressed the activation response by two-thirds. Cycloheximide given 2 or 4 hr after the copper was only one-half as effective. Actinomycin D caused only a 10-15% inhibition of the copper-induced activation. The data suggest that copper is a key regulator of lysyl oxidase activity in aorta and may in fact be a major determinant of the steady-state levels of the enzyme in that tissue. |
The cellular content of acetyl-CoA carboxylase [acetyl-CoA:carbon-dioxide ligase (ADP-forming), EC 6.4.1.2] in Saccharomyces cerevisiae is reduced by the addition of long-chain fatty acids to the culture medium. Mutant strains of S. cerevisiae defective in acyl-CoA synthetase [acid:CoA ligase (AMP-forming), EC 6.2.1.3] were isolated and used to determine whether fatty acid itself or a metabolite of fatty acid is more directly responsible for the repression of acetyl-CoA carboxylase. Cells of the mutant strains were capable of incorporating fatty acid to an extent comparable to that observed with the wild-type strain, but they accumulated markedly more of the incorporated fatty acid in the nonesterified form than did the wild-type cells. The level of acetyl-CoA carboxylase activity in the mutants, in contrast to that in the wild-type strain, was hardly affected by the addition of fatty acids to the medium. These results indicate that the activation of exogenous fatty acid is required for the repression of acetyl-CoA carboxylase, supporting the view that the repressive effect is mediated by some compound metabolically derived from fatty acid. |
Villus tip cells and crypt cells of rat jejunal mucosa were separated by the planning procedure of Imondi et al. and were studied with respect to their activities of the enzymes of the gamma-glutamyl cycle and glutathione content. The villus tip cells exhibit much higher gamma-glutamyl transpeptidase activities than do the crypt cells: thus, gamma-glutamyl trnaspeptidase appears to be a villus-specific enzyme. gamma-Glutamyl cyclotransferase and the enzymes required for glutathione synthesis are not specifically localized to either the crypt or villus tip cells but are present in both. The crypt cells have a high concentration of glutathione (4-5 mM) comparable to the levels found in liver and kidney; in contrast, the villus tip cells have much lower concentrations. On fasting, the glutathione concentration decreased markedly in both villus tip and crypt cells; feeding of protein, but not of sucrose, led to increased glutathione concentrations. The migration of cells from the undifferentiated crypt cell region to the villus tip is associated with structural and biochemical changes that equip the cell for its mature functional activities, which include transport. The present findings indicate that such cellular differentiation and migration is associated with a marked increase in gamma-glutamyl transpeptidase activity and in the utilization of glutathione. |
Addition of dimethylsulfoxide at concentrations of 1% and 2% (vol/vol) to cells of mouse neuroblastoma clone NIE-115 in the confluent phase of growth resulted in the production of morphologically differentiated cultures with extensive process formation. Cell maintained in 2% dimethylsulfoxide remained in a stable nondividing condition for periods of up to 4 weeks. A high degree of electrical excitability was found in these cells, but there was no clear correlation of this property with the level of induction of either acetylcholinesterase (acetylcholine hydrolase; EC 3.1.1.7) or tyrosine hydroxylase [L-tyrosine, tetrahydropteridine:oxygen oxidoreductase (3-hydroxylating); EC 1.14.16.2]. In addition, intracellular levels of cyclic 3':5'-AMP were not elevated in fully morphologically and electrically differentiated cells. While cell division was markedly inhibited by 2% or higher concentrations of dimethylsulfoxide, at 1% growth continued at a somewhat slowed rate and such cultures exhibited enhanced process formation and electrical activity for a relatively short period. High concentrations (3% or 4%) of dimethylsulfoxide totally suppressed process formation and did not result in increased excitability, but cells maintained high resting potentials. The results suggest that the development of the excitable membrane in neuroblastoma cells may be expressed independently of neurospecific enzyme induction, and does not require a sustained elevation of cyclic 3':5'-AMP levels. |
Stoichactis helianthus toxin, a protein derived presumably from the nematocysts, was purified to homogeneity. It has a molecular weight of about 16,000, an isoelectric pH of 9.8, and it contains approximately 3.7% carbohydrate. It is powerfully hemolytic for erythrocytes derived from a variety of animal species, those of the cat being the most sensitive and those of the guinea pig the most resistant. The toxin is lytic also for rabbit blood platelets, and it destroys cultured fibroblasts but is inactive for several kinds of bacterial protoplasts and spheroplasts. The hemolytic activity is specifically inhibited by sphingomyelin, and it is proposed that this phospholipid is the constituent of the membrane which functions as receptor for the toxin. Supporting evidence includes the findings that enzymes known to destroy sphingomyelin (a) prevent erythrocyte membranes from inhibiting hemolysis, and (b) render erythrocytes resistant to lysis by the toxin. The mechanism underlying hemolysis may involve translocation of membrane sphingomyelin by virtue of a specific affinity of the coelenterate protein for this phospholipid. |
Fast reaction techniques were used to study the kinetics of protein fluorescence intensity changes that are associated with the reactions of unadenylylated Escherichia coli glutamine synthetase [L-glutamate: ammonia ligase (ADP-forming), EC 6.3.1.2] with its substrates. It was established that the synthesis of glutamine occurs by a stepwise mechanism. During the catalytic process two fluorometrically distinct intermediates were observed. Both forward and reverse rate constants which lead to the formation and consumption of these intermediates were evaluated. The catalytic rate constant, kc, which was calculated from these rate constants agrees well with the values of kc which were determined by direct measurement of the overall biosynthetic activities by means of stopped-flow technique or the steady-state assay method. |
The kinetics of the action of local anesthetics upon firefly luciferin and luciferase systems is presented. Clinical concentrations of local anesthetics inhibited this ATP-induced luminescence in a dose-dependent manner. From the effects of temperature and pH upon the inhibitory action of the local anesthetics, it is concluded that hydrophobic ligand-enzyme interaction is the predominant cause of the inhibition, but hydrophilic interaction also contributes to the inhibition to a lesser degree. A molecular theory of anesthesia is outlined which postulates that release of electrostricted water molecules from the hydrophilic parts of the enzyme due to the protein conformational changes induced by anesthetics is the cause of the decreased luminescence. A similar mechanism is expected to occur at the cell membrane, which probably dehydrates the sodium channel and suppresses the conductance of this ion across the membrane. These events lead to a volume expansion of the total system, and the system becomes reactive to a pressure which reverses the anesthesia by shifting the equilibrium to the nonanesthetized original volume. The pressure antagonism of anesthesia can be explained by this overall volume expansion and not by a mere swelling of the cell membrane. |
Cyclic nucleotide metabolism was investigated in growing kidneys of rats during compensatory hypertrophy and during neonatal development. After unilateral nephrectomy a mild and short-lasting decrease in cyclic 3':5" adenosine monophosphate (cAMP) was observed in the hypertrophying kidney. In contrast, cyclic 3':5' guanosine monophosphate (cGMP) showed a sharp decline to 20% of control at 15 min and a rapid rise to 200-300% above base-line at 1-72 hr. The alterations in renal tissue levels of cGMP were associated with parallel changes in the soluble, 100,000 X g supernatant guanylate cyclase activity [GTP pyrophosphate-lyase (cyclizing): EC 4.6.1.2]. No change was observed in total cGMP phosphodiesterase (3':5'-cyclic-nucleotide 5'-nucleotidohydrolase; EC 3.1.4.17). In the rapidly growing kidney of newborn rats cAMP levels were 983 +/- 65 and 833 +/- 42 pmol/g of kidney at 4 and 7 days after birth, and increased to adult levels (1518 +/- 57 pmol/g) at 21 days whereas cGMP levels were 59.8 +/- 6.8 and 92.5 +/- 13.9 pmol/g at 4 and 7 days and decreased to adult levels (36 +/- 1.5) at 21 days. The results indicate that compensatory renal hypertrophy and neonatal kidney growth are associated with changes in cAMP and cGMP metabolism. |
Effects of the denaturants urea and guanidine-HCl on the sweet-tasting protein monellin have been studied. The pH at which monellin is initially treated with denaturant is an important factor in retention of sweetness, but the pH maintained during subsequent removal of denaturant by dialysis has no effect on activity. Recovery of sweetness of denaturant-treated monellin is favored when denaturation occurs at acid pH. Monellin treated with either 6 M guanidine-HCl or 8 M urea at acid pH retains all of its sweetness following removal of denaturant, but urea treatment at neutral pH leads to some irreversible loss of sweetness. Monellin precipitates from solution under some conditions during removal of denaturant by dialysis, and the precipitated protein is no longer sweet. Precipitation is least under acid conditions. Aggregated protein was demonstrated by gel filtration chromatography. The single sulfhydryl group of monellin was not demonstrable in the precipitated protein, having apparently become oxidized during denaturation and formation of the aggregated protein. The data support the hypothesis that the tertiary structure is important in the ability of monellin to elicit a sweet sensation. |
A lipoprotein present in trypsin-treated microsomes can be oxidized with formation of malondialdehyde in a system which contains NADPH, ferric ion-ADP complex, NADPH-cytochrome c reductase and a factor. This factor, a mixture of peptides, can be isolated from hepatic microsomes by trypsin digestion and successive gel filtration through Sephadex G-100 and G-25 columns. Lipid peroxidation in this system catalyzes the deiodination of thyroxine, as does NADPH-dependent lipid peroxidation in fresh hepatic microsomes. Thyroxine inhibits lipid peroxidation as it is deiodinated in this system. |
The influence of environmental pH on AAV was studied in infectious virus titrations, induction of CF antigens production of infectious virus, induction of immunofluorescent stainable antigen, and aggregation of the viral particles. The pH of the medium was found to influence the titer of virus stocks in that less virus was registered at acid pH's, giving differences of up to 105 TCID50 in HEK and HEp-2 cells. Less infectious virus was produced in KB cells, and decreased amounts of CF antigen appeared at acid pH's. However, increased levels of detectable intracellular FA antigen appeared at acid pH's. Electron microscopic examination of AAV particles negatively stained at various pH's showed increasingly large aggregates of particles as the pH was lowered. Under the acid conditions studied, the adenovirus helper and cell activities were only slightly suppressed, with the greatest effect due to aggregation of the virus particles. |
Although it is well recognized that mineralocorticoids enhance renal acid excretion, the effect of glucocorticoids on renal acidification is unclear. Oral administration of dexamethasone to six healthy volunteers for 1 week at a daily dose of 4.5 mg was associated with mild respiratory alkalosis and a small but statistically significant increase in baseline urine pH. However, neither the ability to lower urine pH nor to excrete titratable acid and ammonium after NH4Cl acid-loading was altered. Administration of a single intravenous dose of dexamethasone sodium phosphate (7.5 mg) was associated with a significant rise in urine pH and potassium excretion and decreased titratable acid, ammonium , and phosphorus excretion in the absence of changes in blood acid-base status, creatinine clearance, or urine flow. |
A simple and rapid method for measuring guanylate cyclase activity in broken cell preparations of biological tissues is described. This method employs the rate of conversion of [32P]GTP to [32P]cyclic-GMP. The product of this reaction is isolated by ion-exchange chromatography and by a ZnSO4-Ba(OH)2 precipitation at pH 5.7. Using this method, about 30-50 samples can be assayed for guanylate cyclase activity during a 5-6 hr period. The characteristics of this enzyme in the mammary gland were found to be similar to those described for other tissues using different methods for measuring guanylate cyclase activity. |
Guanylate cyclase and cyclic-GMP phosphodiesterase activities were measured in homogenates of mammary glands from virgin, pregnant, and lactating mice. Guanylate cyclase activities increased 35% in mammary tissues during pregnancy, and a further 40% increase was observed during lactation. Cyclic-GMP phosphodiesterase activity also increased during pregnancy but activities were not different in glands from lactating mice vs glands from pregnant mice. These results are discussed with regard to a possible role of cyclic-GMP in regulating lactational processes. |
In anesthetized dogs given secretin intravenously in doses doubling every 60 min and ranging from 0.5 to 8 units per kg body weight per hr, cyclic-AMP levels in pancreatic tissue rose continuously, whereas DNA concentrations were slightly decreased. Bicarbonate concentrations and bicarbonate outputs, cyclic-AMP tissue concentrations and bicarbonate outputs, as well as cyclic-AMP tissue concentrations and juice outputs, were significantly correlated. In conscious pancreatic fistula dogs, there was also a significant correlation between cyclic-AMP and bicarbonate concentrations and outputs in the pancreatic juice after stimulation by exogenous secretin. Accordingly, enhanced release of endogenous secretin achieved by intraduodenal acidification led to a dose-dependent increase in bicarbonate and cyclic-AMP outputs in both conscious and anesthetized dogs. Phosphodiesterase inhibitors (aminophylline, caffeine, and papaverine) given alone to the conscious dogs did not initiate pancreatic bicarbonate secretion, but they potentiated bicarbonate responses to exogenous secretin. These data suggest that cyclic-AMP plays a part in secretin-stimulated pancreatic secretion. |
Purified streptococcal proteinase and Serratia proteinase are potent permeability factors in rat skin and initiate histopathological evidence of an acute inflammatory response. These effects appear to be largely independent of terminal components of complement, histamine, and polymorphonuclear leukocytes. |
Adrenergic agonists produced a characteristic and definite decrease in the amplitude of spontaneous contractions and tone of the isolated rabbit jejunum. Effect of phenylephrine was abolished either by phenoxybenzamine or phentolamine. Relaxation induced by epinephrine and by norepinephrine was inhibited after combined treatment with phentolamine and propranolol. Phentolamine alone diminished the response to epinephrine and to norepinephrine, but the diminution for epinephrine was greater, indicating that epinephrine has a greater affinity for alpha- than for beta-receptors in the rabbit jejunum. Stimulation of the beta-receptors by isoproterenol was inhibited by propranolol, oxprenolol, sotalol and pindolol, but the block was incomplete. The activity of these four beta-blockers in preventing the inhibitory response to isoproterenol was as follows: inidolol greater than or equal to oxprenolol greater than propranolol greater than sotalol. This demonstrates the fact that not all beta-adrenergic blocking agents possess an identical pharmacologic spectrum of activity. Also it can be suggested that the beta-receptors of jejunum differ in specificity from those of other organs. |
Tyrosine hydroxylase is present at birth and reaches adult levels in the hypothalamus usually during the second month. Recurrent stimulation of intrahypothalamic noradrenergic structures shortened this period of maturation in a statistically significant manner. |
Mice were given a drug per os and 2 h later were challenged with an intravenous LD95 of nicotine. Amitriptyline, imipramine, doxepin, meprobamate, chlordiazepoxide, diazepam, trifluoroperazine, haloperidol, thioridazine, chlorpromazine, phenobarbital, propranolol and diphenylhydantoin were all active in protecting mice from extensor convulsions and lethality. Iproniazid, tranylcypromine, atropine, benztropine and trimethadione were inactive. There appears to be a relationship between blockage of nicotine-induced extensor convulsions and lethality in mice and sedative-antianxiety effects in man. This relationship is especially good for drugs designated antidepressant, antianxiety and antipsychotic. |
Propranolol at a dose (10 mg/kg) which did not alter tail-flick latency by itself, did not alter the ED50 of morphine when given 10 min prior to the narcotic. Propranolol at doses of 10 and 25 mg/kg given 10 min prior to naloxone challenge did not significantly alter the frequency of naloxone induced jumping 72 hr after morphine pellet implantation. The ED50 of naloxone in morphine pelleted mice was not altered by treatment with propranolol at 0, 24, and 48 hr after pellet implantation. Naloxone caused hyperactivity in mice when administered 72 hr after morphine pellet implantation. An injection of 25 mg/kg propranolol 10 min prior to naloxone did not block this hyperactivity. In addition, administration of 10 mg/kg of propranolol every 8 hr to rats during withdrawal from morphine failed to alleviate the withdrawal syndrome as evidenced by changes in either body weight or water intake. These data suggest that the beta-adrenergic blocking agent, propranolol, does not alter the antinociceptive activity or lessen the withdrawal syndrome of morphine in rodents. |
After daily injections of melanocyte stimulating hormone (MSH), MSH-release inhibiting factor (MIF), or diluent albino rats ran a 12 choice Warden maze for a palatable food reward. Rats receiving the hormones had shorter latencies and made fewer errors than controls during learning but, unlike results with simple tasks, there were no differences during extinction. The results demonstrated that both MSH and MIF-I could facilitate the acquisition of an appetitive task which seemed of sufficient complexity to emphasize differences in performance. |
The jumping apparatus of the flea, which includes highly modified direct and indirect flight muscles, is described: attention is drawn to the various specializations of the exoskeleton which stiffen the thorax and also provide the 'click' mechanism triggering take-off. A finger-like invagination of tall cells within the cavity of the developing pleural arch of the pharate adult secretes the resilin pad. This is illustrated with coloured photographs. It is suggested that winglessness of a Mecopteran-like ancestor pre-adapted fleas to a parasitic life-style, and that a jumping mode of progression was a primitive feature of the whole Order. Scattered throughout the Siphonaptera today are species which have secondarily lost the pleural arch and with it the power to execute large jumps. These are usually found among fleas parasitizing mammals inhabiting caves, subterranean burrows and runs, high aerial nests and snow or ice-bound habitats. Large pleural arches are associated with fleas infesting large mobile hosts. |
The ultrastructure of the trochanteral depressor muscle of the oriental rat flea is described. It is shown to be similar to that of the tubular leg muscles of other insects except in the volume and arrangement of the sarcoplasmic reticulum. The sarcoplasmic reticulum occupies approximately 18% of the volume of the muscle fibres. It is in three configurations:a regular array of parallel tubules opposite the A-band, a collar of sacculi involved in the formation of the dyads at the edge of the A-band and a loosely woven arrangement of tubules around the I-band. This tripartite arrangement of the sarcoplasmic reticulum and its large surface area is discussed in relation to the action of the muscle as the main propulsive muscle in the jump of the flea. |
The flea's hind legs are the chief source of jumping power, but in species which execute large jumps, take-off is accelerated by elastic energy released from a resilin pad (homologous with the wing hinge ligaments of flying insects) situated in the pleural arch. A central click mechanism, operated by a rapid twitch of the trochanteral depressor (the starter muscle), synchronizes the separate sources of energy which power the jump. Ciné photos confirm the morphological evidence that the flea takes off from the trochanters, not the tarsi. The loss of wings, associated with lateral compression of the body and the shortening of the pleural ridge (which thus lowers the position of the pleural arch) together with modifications of the direct and indirect flight muscles, are some of the main morphological features associated with the change from a flying to a saltatorial mode of progression. The flea's take-off basically resembles that of other Panorpoid insects (Diptera, Mecoptera, etc.). The release of elastic energy from the pleural arch is a system by which the force used to move the wings of flying insects is rapidly fed back into the legs and adds power to the jump. |
The genetic apparatus of the cell is responsible for the accurate biosynthesis of the primary structure of macromolecules which then spontaneously fold up and, in certain circumstances, aggregate to yield the complex tertiary and quaternary structures of the biologically active molecules. Structures capable of self-assembly in this range from simple monomers through oligomers to complex multimeric structures that may contain more than one type of polypeptide chain and components other than protein. It is becoming clear that even with the simpler monomeric enzymes there is becoming clear that even with the simpler monomeric enzymes there is a kinetically determined pathway for the folding process and that a folded protein must now be regarded as the minimum free energy form of the kinetically accessible conformations. It is argued that the denatured subunits of oligomeric enzymes are likely to fold to something like their final structure before aggregating to give the native quaternary structure and the available evidence would suggest that this is so. The importance of nucleation events and stable intermediates in the self-assembly of more complex structures is clear. Many self-assembling structures contain only identical subunits and symmetry arguments are very successful in accounting for the structures formed. Because proteins are themselves complex molecules and not inelastic geometric objects, the rules of strict symmetry can be bent and quasi-equivalent bonding between subunits permitted. This possibility is frequently employed in biological structures. Conversely, symmetry arguments can offer a reliable means of choosing between alternative models for a given structure. It can be seen that proteins gain stability by growing larger and it is argued in evolutionary terms that aggregation of subunits is the preferred way to increase the size of proteins. The possession of quaternary structure by enzymes allows conferral of other biologically important properties, such as cooperativity between active sites, changes of specificity, substrate channelling and sequential reactions within a multi-enzyme complex. Comparison is made of the invariant subunit compositions of the simpler oligomeric enzymes with the variation evidently open to, say, the 2-oxoacid dehydrogenase complexes of E. coli. With viruses, on the other hand, the function of the quaternary structure is to package nucleic acid and, as an example, the assembly and breakdown of tobacco mosaic virus is discussed. Attention is drawn to the possible ways in which the principles of self-assembly can be extended to make structures more complicated than those that can be formed by simple aggregation of the comonent parts. |
There are two aspects of enzyme specificity: recognition of the substrate by the formation of an enzyme-substrate compound and recognition of the transition state by catalysis of the reaction. Kinetic studies with inactive substrate analogues as potential competitive inhibitors, and structural studies of their compounds with enzymes, give information about the first of these specificity elements. Comparative kinetic studies with alternative substrates give information about both. There is a great deal of information from kinetic studies of dehydrogenases about the coenzyme specificities, substrate specificities and stereospecificities and mechanisms of these enzymes, particularly alcohol dehydrogenases. Recent X-ray diffraction studies of dehydrogenases have given insight into the molecular basis of some of their specificity elements. An attempt is made to correlate the available kinetic and structural data for alcohol and lactate dehydrogenases. |
Possible structures adopted by bulk water are discussed with special reference to the possible presence of monomeric water and the detection of 'free' -OH groups. The way in which water tends to accommodate small hydrophobic molecules is considered, with particular reference to the clathrate theory and the phenomenon of 'structure making'. Cage-pairing and cage-sharing processes are described. Consideration of the way water solvates cations and anions is followed by a discussion of the way these solvated ions interact with the bulk medium. Large symmetrical alkylammonium ions probably encourage clathrate cage formation, at least at low temperatures. Particular reference is made to the use of infrared, Raman, ultraviolet, n.m.r. and e.s.r. spectroscopic techniques to the study of water and aqueous solutions. |
The intercalative trypanosomal drug, ethidium bromide, forms a crystalline complex with the dinucleoside monophosphate, 5-iodiuridylyl(3'-5')adenosine (iodoUpA). These crystals are monoclinic, space group C2, with unit cell dimensions, a = 2.845 nm, b = 1.354 nm, c = 3.413 nm, beta = 98.6 degrees. The structure has been solved to atomic resolution by Patterson and Fourier methods, and refined by full matrix least squares to a residual of 0.29 on 2017 observed reflexions. The asymmetric unit contains two ethidium molecules, two iodoUpA molecules, twenty water molecules and four methanol molecules, a total of 156 atims excluding hydrogens. The two iodoUpA molecules are held together by adenine-uracil Watson-Crick base-pairing. Adjacent base-pairs within this paired iodoUpA structure and between neighbouring iodoUpA molecules in adjoining unit cells are separated by 0.68 nm. This separation results from intercalative binding by one ethidium molecule and stacking by the other symmetry is utilized in this model drub-nucleic acid interaction, the intercalative ethidium molecule being oriented such that its phenyl and ethyl groups lie in the narrow groove of the miniature nucleic acid double helix. Solution studies have indicated a marked sequence specificity for ethidium-dinucleotide interactions and a probable structural explanation for this has been provided by this study. |
Interest in nucleic acid hybridization stems mainly from its great power as a tool in biological research. It is used in several quite distinct ways. Because of the high degree of specificity that they show, hybridization techniques can be used to measure the amount of one specific sequence within a very heterogeneous mixture of sequences. Measurements of 1/10(6)-10(7) have been recorded. In extension of this, various properties of a specific sequence can often be studied. Secondly, because the kinetics of nucleic acid hybridization are quite well understood, it can be used to characterize both a pure sequence and a very complex mixture of sequences, like the genome of a vertebrate. Thirdly, again because of its specificity, it can be used to measure homologies between different populations of nucleic acids. Lastly, in conjunction with other techniques, it can be used as a basis for the fractionation of nucleic acid populations and the purification of specific sequences. Specific examples of these applications are given, with special reference to the organization of the genome in higher eukaryotes. |
Biological membranes must be viewed as highly dynamic, undergoing continuous structural fluctuations and changes in response to external perturbations. The study of liposomes by 31 P n.m.r. and fluorescence can reveal some of the motional characteristics of the different regions in a bilayer. Asymmetric lipid distribution and how this depends on the environment is also observed by n.m.r. The nature of the interaction of amine anaesthetics and of polypeptide antibodies with membranes is discussed in relation to their perturbing effect. The role of lipid mobility in modulating hormone-receptor interaction is discussed with reference to the binding of thyroid stimulating hormone. |
Many aspects of cell behaviour are regulated by the interaction of extracellular ligands with specific receptors exposed on the cell surface. The receptors correspond to membrane proteins and expecially glycoproteins. A key event in regulation is the transmission across the surface membrane of the information resulting from receptor-ligand interaction. The activation of lymphocytes by Phaseolus vulgaris phytohaemagglutinin (PHA) provides a convenient experimental model for the study of the molecular basis of receptor-ligand interaction and the molecular consequences of interaction. The receptor mediating lymphocyte activation by PHA is probably a unique glycoprotein which is present to the extent of about 3 X 10(4) molecules/cell. The PHA-receptor complex solubilized in 1% sodium deoxycholate has a molecular size of about 3 X 10(5). The primary event in the activation process is probably an increase in the permeability of the surface membrane to Ca2+. This may be achieved by PHA cross-linking ('patching') the receptors to form a polar channel that permits an influx of Ca2+. |
At the surface of aggregating cells of the slime mould, Dictyostelium discoideum, two different sites interacting with extracellular cAMP are detectable: binding sites and cycl-nucleotide phosphodiesterase. Both sites are developmentally regulated. An adequate stimulus for the chemoreceptor system in D. discoideum is the change of cAMP concentration in time, rather than concentration per se: long-term binding of cAMP causes only short-term response. The system is, consequently, adapted to the recognition of pulses rather than to steady-state concentrations of cAMP. The ce,lls are, nevertheless, able to sense stationary spatial gradients and to respond to them by chemotactic orientation. The possibility is discussed that they do so by transforming spatial concentration changes into temporal ones, using extending pseudopods as sensors. The cAMP recognition system is part of a molecular network involved in the generation of spatio-temporal patterns of cellular activities. This system controls the periodic formation of chemotactic signals and their propagation from cell to cell. The phosphodiesterase limits the duration of the cAMP pulses and thus sharply separates the periods of signalling; the binding sites at the cell surface are supposed to be the chemoreceptors. The control of cellular activities via cAMP receptors can be studied with biochemical techniques with cell suspensions in which spatial inhomogeneities are suppressed by intense stirring, whereas the temporal aspect of the spatiotemporal pattern is preserved. Under these conditions it can be shown that the extracellular cAMP concentration changes periodically, and that the phase of the cellular oscillator can be shifted by external pulses of cAMP. It can also be shown that small cAMP pulses induce a high output of cAMP, which demonstrates signal amplification, a function necessary for a cellular relay system. |
Recognition of metal cations by biological systems can be compared with the geochemical criteria for isomorphous replacement. Biological systems are more highly selective and much more rapid. Methods of maintaining an optimum concentration, including storage and transfer for the essential trace elements, copper and iron, used in some organisms are in part reproducible by coordination chemists while other features have not been reporduced in models. Poisoning can result from a foreign metal taking part in a reaction irreversibly so that the recognition site or molecule is not released. For major nutrients, sodium, potassium, magnesium and calcium, there are similarities to the trace metals in selective uptake but differences qualitatively and quantitatively in biological activity. Compounds selective for potassium replace all the solvation sphere with a symmetrical arrangement of oxygen atoms; those selective for sodium give an asymmetrical environment with retention of a solvent molecule. Experiments with naturally occurring antibiotics and synthetic model compounds have shown that flexibility is an important feature of selectivity and that for transfer or carrier properties there is an optimum (as opposed to a maximum) metal-ligand stability constant. Thallium is taken up instead of potassium and will activate some enzymes; it is suggested that the poisonous characteristics arise because the thallium ion may bind more strongly than potassium to part of a site and then fail to bind additional atoms as required for the biological activity. Criteria for the design of selective complexing agents are given with indications of those which might transfer more than one metal at once. |
The structure of the Fab' fragment of a human myeloma protein (IgG1 (lambda) New) has been determined by X-ray crystallographic analysis to a nominal resolution of 0.2 nm. Each of the structure subunits corresponding to the variable and to the constant homology regions of the light and heavy polypeptide chains contains two irregular beta-sheets which are roughly parallel to each other and surround a tighly packed interior of hydrophobic side chains. The regions of the hypervariable sequences in the light and heavy chains occur in close spatial proximity at one end of the molecule, defining the active site of IgG New. The role of these hypervariable regions in defining the size and shape of the active site of different immunoglobulins is discussed on the basis of the three-dimensional model of Fab' New. Several ligands that bind to the active centre of IgG New have been used to obtain crystalline ligand-Fab' New complexes which were investigated by difference Fourier maps. These studies are analysed in terms of the biological function and specificity of antibodies. |
The nature of molecular interactions is examined. Intermolecular forces are divided into long-range and short-range components; the former operate at distances where the effects of electron exchange are negligible and decrease as an inverse power of the separation. The long-range interactions may be subdividied into electrostatic, induction and dispersion contributions, where the electrostatic component is the interaction of the permanent charge distributions and the others originate in the fluctuations in the distributions. Typical magnitudes of the various contributions are given. The forces between macroscopic bodies are briefly considered, as are the effects of a medium. Some of the manifestations of molecular interactions are discussed. |
This paper reports the initial progress in a research programme to identify and obtain the relative orientations, in solution, of the amino acid residues that constitute the combining site of the myeloma protein MOPC 315. This protein has a molecular mass of 150,000, but enzymic digestion yields the Fv fragment of molecular mass 25,000 which still has the combining site intact, as judged by the affinity for dinitrophenyl haptens. Analysis of the e.s.r. spectra of a series of dinitrophenyl spin labelled haptens has allowed the dimensions, rigidity and polarity profile of the combining site to be determined. The combining site is a cleft of overall dimensions 1.1 nm x 0.9 nm x 0.6 nm which has considerable structural rigidity. One of these spin labels has also been used to perturb the n.m.r. spectrum of the Fv and using difference spectroscopy the 270 MHz proton n.m.r. spectrum of the amino acid residues in and around the combining site has been obtained. This spectrum contains only the equivalent of about 30 aromatic and 21 aliphatic protons. Comparison of this difference spectrum with that obtained using a diamagnetic analogue suggests that any conformational changes on hapten binding are mainly localized to the combining site. By the use of (n.m.r.) difference spectroscopy the protons of the three histidine residues in the Fv are observed to titrate with pH and have pKa values of about 8.1, 6.9 and 6.1. The histidine resonances with pKa values 6.9 and 6.1 alter slightly in the presence of haptens and also appear in the spin label difference spectrum, and must therefore be in or near to the combining site. These are assigned to His 102H and His 97L. The existence of lanthanide binding sites on the Fv, necessary for the mapping studies, has been demonstrated by measurements of Gd III water relaxation rates in Fv solutions and also by the changes in the Fv tryptophan fluorescence on addition of Gd III. At pH 5.5 there is one tight binding site for the lanthanides (KD approximately 80 muM) but in the presence of hapten this is weakened 10-20 fold with a reciprocal effect on the hapten binding. Measurements of the Gd III quenching of the e.s.r. spectrum of a spin labelled hapten bound to Fv indicate that the lanthanide site is ca. 1.5 nm from the nitroxide moiety. |
The specificity of binding between small molecules and macromolecular receptors may be studied by comparing theoretically calculated conformational potential energy surfaces of a series of chemically similar molecules which have a range of receptor binding energies and biological activities. In this way essential requirements for binding may be highlighted, including the necessity of the small molecule adopting, or passing through, conformations which are not at energy minima and not found either in the solid state or in aqueous solution. In particular the conformational demands of the adrenergic beta-receptor and histamine H1 receptor are considered. |
An enzyme is designed to bind most tightly to a substrate when it is in the transition state of the reaction which the enzyme catalyses. The consequent reduction of the activation energy of the reaction constitutes the catalytic mechanism. The energetic contributions of different features of the interaction can only be crudely assessed, but they are dominated by entropically driven effects. The binding site of trypsin orients the substrate so that the reacting groups are correctly placed for reaction to occur. Apart from two side chains which take part in chemical steps of the reaction, the enzyme behaves almost as a rigid body. The full binding interactions are only developed when the substrate is in an intermediate stage of the reaction. The tightly bound complexes of trypsin with protein trypsin inhibitors have proved amenable to structural analysis. Enzyme inhibitor interactions, which account for almost 80 kJ mol-1 of interaction energy, are known fairly accurately. The similarity of the two known trypsin inhibitor structures, close to the primary binding site, indicates a high specificity, even for this simple interaction. In cases where no large conformational changes occur the specificity of an enzyme should be predictable from accurate knowledge of its tertiary structure. |
Soluble rat brain proteins undergo a thermal reversible denaturation in the range of 20 degrees C -65 degrees C. The thermal transition as studied in 0.25 M sucrose solution, is associated with changes in the proteins ionization capacity by the lowering of the isoionic solution pHfrom a value of 6.95 at 20 degrees C to 6.55 at 65 degrees C. The apparent enthalpy change delta H at the transition temperature (t=50 degrees C) is about 34 Kcal, heat capacity delta Cp about 1.75 Kcal, and apparent entrophy change deltaS 100 e.u. The data suggest that the thermal transition is predominantly a two-state process. A prolonged keeping of the protein solution at the increased temperature produces a partial reversibility of thermal transitions by a lowering of 5-HT cations fixing on the protein molecule. |
Seven of nine depressed patients experienced a 4.3-fold increase in rated euphoria and activation following 30 mg d-amphetamine in a replicated dose, double blind study. d-Amphetamine was 2 to 2.3-fold more effective in producing activation, euphoria, and antidepressant effects than the same dose of l-amphetamine. Co-treatment with lithium carbonate produced a 60% (P less than 0.001) attenuation of the activation and euphoria responses to d-amphetamine. The responses to l-amphetamine were almost completely abolished by lithium. This study raises the possibility of lithium carbonate use as an adjunct in the treatment of amphetamine addiction. |
Four possible metabolic approaches to improving cardiac function in the presence of myocardial hypoxia have been considered. 1. It appears that there is increasing evidence which suggests that free fatty acids are harmful to the ischemic heart. 2. Although it has been demonstrated that Krebs cycle intermediates can result in anaerobic energy formation by the mitochondria, and under certain extreme conditions can lead to improved performance of the heart, the potential for a physiologically important effect of this approach is probably limited. 3. The protection of the ischemic or hypoxic heart by alkalosis may be a feasible approach. The major beneficial effect appears to be exerted through more efficient conversion of energy that is already available to contractile performance rather than by increasing energy supply. 4. There appears to be some real potential for improving cardiac energy delivery via the glycolytic pathway. Calculations based on isolated rat heart studies indicate that, at 50% oxygenation, glycolytic ATP generation could totally correct for the deficit in mitochondrial ATP formation. Therefore, it is in the area of overcoming the inhibition of glycolytic ATP formation and tapping this potential metabolic pathway that energy delivery may be restored toward normal in the hypoxic and perhaps the borderline zone of underperfusion in the ischemic heart. The problem of the ischemic inhibition of glycolysis may partially be overcome by creating extracellular alkalosis, but this presumption will have to be tested. |
The effects of isoproterenol, glucose, and pH on the responses of isolated rat cardiac muscle to hypoxia (95% N2, 5% CO2) were examined while the muscles were contracting isometrically 12 times a minute at 28 degrees C. In the presence of 5.5 mM glucose, 10(-5) M isoproterenol and alkaline pH (7.8) improved the performance of cardiac muscle during early hypoxia. This was followed by a premature decline in developed tension, and contracture appeared. Recovery of function following reoxygenation with 95% O2 and 5% CO2 after a 60-min period of hypoxia was poor. Acid pH (6.8) resulted in an early decline of mechanical activity during hypoxia; but contracture did not appear, and full recovery of developed tension was seen upon reoxygenation after 60 min of hypoxia. When 22 mM glucose was used as substrate, the early responses to hypoxia were not altered; but late performance was improved, contracture did not appear, and full recovery after 60 min of hypoxia was seen. If additional glucose was added to the bath after 30 min of hypoxia (concentration 22 mM), little effect on developed tension was evident; but contracture diminished and recovery after 60 min of hypoxia was improved. Addition of 22 mM glucose allowed isoproterenol to exert its inotropic effect in the absence of late deleterious changes. The data support the concept that factors tending to increase the utilization of limited stores of anaerobic substrate during hypoxia facilitate deterioration. By increasing exogenous glucose, the support of inotropic activity without late adverse effects appears possible, and recovery is improved upon reoxygenation. |
Contractile performance of ischemic feline myocardium was evaluated under conditions of selective changes in perfusate in pH and pCO2. A substantial increase in myocardial performance was noted when the pCO2 was lowered at constant pH, and depression of performance was noted when the pCO2 was increased at constant pH. Perfusate acidosis at constant pCO2 resulted in depression of performance and decreased performance only after 20 min of exposure. Alkalosis did not increase performance and decreased performance transiently during mild ischemia. These studies suggest that performance of myocardium during ischemia is closely related to tissue pCO2 and is minimally related to the level of extracellular pH. |
In healthy, closed-chest dogs, dose-dependent depression of ventricular function was produced by the anesthetics halothane, methoxyflurane, and fluroxene, as evidence by decreases in left venticular stroke volume, stroke work, dP/dt, and an increased enddiastolic pressure. Myocardial blood flow and oxygen consumption decreased concomitantly and were correlated with aortic blood pressure decreases. There was no change in myocardial lactate extraction with halothane and methoxyflurane, suggesting that myocardial oxygenation was adequate in spite of the decrease in blood flow. However, even with marked increases in arterial lactate concentration during fluroxene anesthesia, extraction did not chance and, in fact, tended to decrease. The hemodynamic effects of halothane and methoxyflurane are similar to those previously reported in man, but those of fluroxene are different. Consequently, clinical speculation from these results is not justified at this time. |
Acute aneurysms and other morphologically defined cardiac lesions were produced in frogs by isoproterenol (IPR) as previously described. Samples from lesions verified in vivo and from macroscopically normal ventricular areas, together with samples from nontreated control animals, were analyzed for total water content, inulin space, pHe, and pHi by using DMO-14C and inulin-3H. Total cardiac tissue water content was increased in all types of lesions after IPR injection. The highest content was found in bulging, noncontractile aneurysms. Inulin space was enlarged in all heart muscle specimens from IPR-treated animals, including those without macroscopically visible lesions. Those specimens with aneurysms showed the greatest degree of enlargement. The (pHe-pHi) did not differ between injected and noninjected animals, and the noncontractile samples from aneurysms did not differ from other lesions and macroscopically intact areas. In IPR-injected animals, there was no difference in pHi between macroscopically damaged and nondamaged segments of ventricle wall. On comparing these animals to controls, however, a slight shift to the alkaline side for both pHi and pHe was observed. The (pHe-pHi) was higher in skeletal muscle than in heart muscle in both IPR-treated and nontreated animals. Tissue water increased in skeletal muscle after IPR injection, reflecting a change of intracellular water as inulin space was maintained. |
The possible effect of high concentrations of plasma triglycerides on arterial oxygen tension was investigated in rats by infusion of lymph chylomicrons or a soybean oil emulsion (Intralipid). Mean triglyceride concentrations were raised from 130 to 1454 mg/100 ml without statistically significant change in arterial oxygen tension, oxygen saturation, carbon dioxide tension, or pH. The small reduction in arterial oxygen tension, content, or saturation observed in earlier studies may have been due to inadequate stabilization of fat emulsion then available for intravenous use. The present data suggest that high concentrations of plasma triglycerides produced by infusion of chylomicrons or Intralipid do not affect arterial blood gases in the normal rat. |
Patients with different liver diseases were studied by discriminant analysis. Groups of patients classified mainly on the basis of liver biopsy findings showed functional differences which permitted a consistent reclassification by discriminant functions using laboratory results. Optimal combinations of laboratory tests for the separation of liver diseases were defined. Different combinations were found, dependent on the subsets of liver diseases studied. |
An experimental procedure was worked out in which rats were subjected to an exchange of erythrocytes, followed by acute anemia by means of hemodilution. One group of rats received erythrocytes with a high concentration of 2,3-diphosphoglycerate (DPG), and the other group was given erythrocytes with a low DPG concentration. The survival rate was equal in the two groups. Irrespective of DPG concentration, the rats whose hemoglobin concentration reached the lowest level died. The rats that died were also more acidotic than the others. The results indicate that the hemoglobin concentration and the pH value were more important determinants for survival than the DPG concentrations. |
During two epidemics of influenza A infection in Stockholm 1969-72, 249 cases were selected for a study on the effect of bacterial superinfection. Bacterial involvement was demonstrated through cultures and serologic reactions. The occurrence of C-reactive protein in increased amount in serum was significantly more common in the group which had the strongest indication of bacterial infection. An increased duration of fever, and a higher incidence of pneumonia, leukocytosis and erythrocyte sedimentation rate over 50 mm/l h was also the rule in cases with bacterial involvement. During both epidemics the bacteria most often involved were pneumococci. |
As the effect of antibiotic treatment of maxillary sinusitis has been questioned, the elimination of bacteria from sinus secretions was studied during antibiotic treatment. Penicillin V, azidocillin, tetracycline or doxycycline was administered to 54 patients with maxillary sinusitis. Samples of sinus secretion were aspirated both before treatment and 2-3 days after the onset of treatment. When the antibiotic concentration was below the upper limit of MIC for sensitivity group 1, bacterial growth was present in practically all samples. When the antibiotic concentration equalled or was above this limit, there was no bacterial growth in about half of the samples. A prerequisite for antibiotic effect--elimination of bacteria--is that the antibiotic concentration is well above the MIC of the bacteria at the site of infection. The choice between bactericidal or bacteriostatic antibiotics appeared unimportant. Bacterial survival in the maxillary sinus despite a high antibiotic concentration in the sinus illustrates that MIC values determined in the laboratory do not always mirror the sensitivity of bacteria to antibiotics in vivo. |
Intravenous urography of 78 cryptorchid boys revealed no clinically significant upper urinary tract anomalies. Two boys had a rotated kidney and 2 others a double renal pelvis. One boy had previously been operated upon because of hydronephrosis. There thus appears to be no reason for routine intravenous urography of cryptorchid boys. Forty-two per cent of the boys had spina bifida occulta in the lumbar and sacral spine. One case of asymptomatic congenital cardiac disease was discovered at routine chest X-ray. |
The semen from 20 men with varicocele was studied before and after surgical correction of the varicocele. The effect on sperm quality was only marginal and could not explain the fairly high conception rate (20%) after operation. The recommendation that varicocele in men with long-term infertility should be eliminated by ligation of the internal spermatic veins is still justified despite the absence of positive effects on sperm quality. |
In order to investigate the possible relationship between a glucose-containing pump prime and changes in plasma potassium during extracorporeal circulation, determinations were made of blood glucose and plasma insulin, potassium, and magnesium in 18 subjects undergoing open-heart surgery. In 6 of the patients, the same parameters had been measured during a pre-operative glucose tolerance test. It was found that the elimination of glucose was considerably impaired during extracorporeal circulation, in spite of high insulin levels. During the first minutes of extracorporeal circulation, plasma potassium fell more than during the glucose tolerance test, in spite of comparable insulin levels. It is concluded that changes in plasma potassium during extracorporeal circulation do not reflect insulin activity to any noticeable extent. |
A simple membrane oxygenator for isolated organ perfusion is described. The membrane employed consisted of an ordinary silicone rubber tubing, 2 mm internal diameter, 0.3 mm wall thickness, the length of the tubing varying according to the required gas transfer. When describing the capacity of the oxygenator, it was found that the maximum gas transfer rate per unit membrane surface was an inadequate measure, since this would vary with both flow rate through the oxygenator and the gas binding capacity of the perfusate. The following formula for the function describing the relation between maximally possible change in gas concentration in the perfusate (C), flow rate (F) and actual change in gas concentration in the perfusate (U) was proposed: U=C-e(-bF), b being a constant specific for the gas and the membrane. This formula was tested by a series of in vitro experiments and proved to give a valid description of the capacity of the oxygenator. It was also found that carbon dioxide was always more easily transferred than oxygen, so that oxygen transfer capcity was the limiting factor in the use of the oxygenator. To facilitate the construction of the right size membrane, a nomogram was constructed for oxygen transfer. |
A peroperative study of blood flow and flow direction was performed in series of patients with occlusive disease of the subclavian artery. Particular attention was focused on the flow variations caused by arm ischaemia and postischaemic hyperaemia and on the effect of injection of a vasodilator into the distal subclavian artery. The effect on blood flow and flow direction was measured with the aid of an electromagnetic flowmeter. During arm ischaemia induced by an inflated cuff on the arm, the subclavian flow diminished, as did the vertebral artery flow when it was retrograde. If the vertebral artery flow was anterograde, it increased during arm ischaemia. The postischaemic hyperaemia caused an increase of the subclavian flow and of reversed vertebral flow. If the vertebral flow was anterograde, it diminished during the postischaemic hyperaemia. Similar findings were obtained with intra-arterial injection of a vasodilator. The large amount of blood flow passing through the vertebral artery, as well as the flow variations caused by reactive arm hyperaemia, emphasize the role of this artery as a collateral vessel to the upper limb in cases of the subclavian steal phenomenon. |
Infrared spectra of time- and size-classified atmospheric particulate samples collected with a inertial impactor reveal the presence of acid sulfate in the submicrometer-sized fraction. Although the degree of acidity is highly variable with time, the acidic nature of the particles is observed at all times of the day and may persist for several days in urban areas. |
Directionally sensitive ganglion cells in rabbit retina lose their directional sensitivity when picrotoxin, an antagonist of the inhibitory neurotransmitter gamma-aminobutyric acid, is infused into the retinal blood supply. Strychnine, an antagonist of glycine, does not produce this effect. Other receptive field types are affected by strychnine but not picrotoxin. Inhibitory transmitters therefore have specific functions in information processing in the retina. |
Dopamine beta-hydroxylase activity was higher in mesenteric vessels, adrenal glands, and serum of 3-week-old spontaneously hypertensive rats but lower in the locus coeruleus than it was in the control Wistar-Kyoto rats. The results support the concept that the nervous system is an important regulator of blood pressure. |
Chromatography on controlled pore glass in combination with chaotropic buffers makes possible, in a single step, protein purifications of several hundredfold. The new emphasis is on highly selective controllable adsorption. The method is useful for the purification and concentration of proteins from large volumes of complex media and for the purification of proteins that are poorly soluble or tend to aggregate in aqueous solution D-(-)-Beta-Hydroxybutyrate dehydrogenase, a mitochondrial membrane-bound protein, several soluble proteins, and staphylococcal alpha toxin, which can be purified directly from large volumes of culture medium, are used to illustrate the method. |
A trace quantitative analysis of barbiturates has been carried out in blood, urine, organs and in gastric and intestinal concents. The amount of sample required for analysis is very small [approximately 400 mul blood]. Extraction is carried out four times with the mixture of acetone and either 1:1]. The preparation of columns, packing and standards has been described. The device used for the analyses [Chrom 3] is furnished with an adjusted feeding block preventing the decomposition of samples in the doser. The column temperature is 190 degrees C, the column packing is Chromaton N-AW-DMCS coated with 3% NPGS and 0.75% trimer acid, detector FID. |
Previous human studies have shown that drinking tea during meals significantly inhibits the absorption of both food iron and medicinal iron. This study provides evidence from experiments with rats that the tannins in the tea are responsible for the inhibition, probably by forming non-absorbable complexes with the iron within the intestinal lumen. The molar ratio of tannin: iron is dependent on the pH, being 1:1 at pH 2,0 2:1 at pH 5,5 and 3:1 at pH 8,0. Since tannins are present in many vegetable foods the formation of such complexes may be a factor in the poor availability for absorption of much food iron. |
The role of the different cytochromes P-450 in the metabolism of the anaesthetic agent fluroxene, and the mechanism of production of toxic effects seen after pre-treatment of the animals with pehnobarbital prior to anaesthesia, have been investigated. Male rats were anaesthetized with fluroxene, or with 2,2,2-trifluroethyl ethyl ether, or with ethyl vinyl ether in an attempt to ascertain the in vivo toxic effects of the three anaesthetic agents. The resultant hepatic histology is reported. A study of the binding and metabolism of fluroxene by isolated rat hepatic microsomes was also made. We conclude that it is elevated levels of cytochrome P-450 which potentiate the toxicity of fluroxene anaesthesia in phenobarbital treated animals and that cytochrome P-448 does not bind or metabolize fluroxene. The potential toxicity of the fluroxene molecule is considered to reside in the trifluoroethyl moiety, while the vinyl group of fluroxene appears to play a role in the observed liver damage. |
This is a preliminary report. Clearly, the internal mammary artery implanted into the infarcted anterolateral portion of the wall of the left ventricle has been of help in decreasing the size of the infarction and in maintaining the life of the dogs and normal function six hours after a large left ventricular wall myocardial infarction had been created. More animals need to be studied at the end of six hours, eight hours, and ten hours after implantation. More studies are needed to learn if ligation of the coronary veins at the same time as the arteries is beneficial or not. Two internal mammary arteries may act better than one when implanted side by side into a 5 by 5 centimeter infarction. In man, both internal mammary arteries and the right gastroepiploic artery could be used to revascularize acute myocardial infarctions in the posterior and anterolateral parts of the left ventricle. |
Relationships between various types of chronic anemia, wound healing, and red cell 2,3-diphosphoglycerate (2,3 DPG) were examined in rabbits. Wound tensile strength and energy absorption were not affected by chronic iron-deficiency anemia, the chronic hemolytic anemia caused by intravenous water infusion nor by chronic hemolytic anemia caused by intravenous water infusion nor by chronic phenylhydrazine-induced anemia. Red cell 2,3 DPG levels were increased in the anemia of iron deficiency and were normal in the rabbits with chronic phenylhydrazine-induced anemia at the time of wound excision but were low following phynylhydrazine injection. The results show that chronic anemia per se does not affect the tensile strength and energy adsorption of wound healing. The findings suggest that the wound healing process may differ in certain types of anemia. |
Using the method in which leukocyte suspensions were incubated with NaF or metaproterenol at 30 degrees C for 15-30 min to allow them to convert 3H-ATP (10 muCi) to 3H-cyclic AMP, followed by separation of the formed 3H-cyclic AMP by common chromatography, the leukocyte adenyl cyclase activity of monkeys and human beings was measured with high reproducibility. The oral administration of metaproterenol increased the leukocyte adenyl cyclase activity which was stimulated by NaF and decreased the count of peripheral eosinophils in some of the monkeys. In the beta-adrenergic blockade of the monkey which was made by administration of propranolol, the leukocyte adenyl cyclase activity significantly decreased. The leukocyte adenyl cyclase from patients with coronary heart disease also decreased after oral medication with propranolol. |
The levels of carbonic anhydrase B and C isozymes in human red cells were determined using a quantitative immunological technique in patients with chronic obstructive lung disease. A significant increase in the level of carbonic anhydrase B was observed in these patients, while the level of carbonic anhydrase C did not change substantially. Positive correlations were found between the level of carbonic anhydrase B and arterial CO2 tension and plasma HCO3 concentration. A negative correlation was observed between the levels of carbonic anhydrase B and blood pH. These findings suggest that the synthesis or degradation of carbonic anhydrase B isozyme is affected by arterial CO2 tension or plasma HC03 concentration. The clinical significance was also discussed in relation to these isozyme levels in red cell. |
The inhalation of trichlorofluoromethane (FC11), dichlorotetrafluoroethane (FC114) and dichlorodifluoromethane (FC12) caused a reduction in mean aortic blood pressure but only FC11 and FC114 caused a reduction in mean pulmonary arterial pressure. The primary cause of the fall is a decrease in pulmonary blood flow. When blood flow to a lobe is kept constant and the adrenergic alpha receptors are blocked by injection of phentolamine, the inhalation of FC11 caused vasodilation. In the intact circulation, the vasodilation is masked by release of catecholamines which constrict the pulmonary blood vessels. |
Delta5-3beta HSDH activity has been assayed either by spectrophotometric method or by use of radioactive substrates. The enzymatic activity is equally distributed between mitochondrial and microsomal fractions verified by electronic microscopy. The specific activity is comparable in both fractions, as well as the optimal pH and the Km for NAD and for the substrates. The delta5-3beta Hut optimal pH, specific activity and sensitivity to the inhibitory action of various steroids are different when C19 and C21 steroids are used as substrates. Estrogens and cyclic AMP have also an inhibitory action on the oxidation of C21 steroids. Treatment of microsomal or mitochondrial membranes with phospholipase A releases fatty acids (mainly arachidonic) and decreases the enzymatic activity. "Adsorbtion" of the fatty acids on bovine serum albumin partially reactivates the delta5-3beta HSDH. |
Hydrolysis of collagen was studied in the bull bone tissues by the Str. griseus crystalline protease. The amount of collagen hydrolyzed by it composed 6.6% and 16% after 4-hour and 6-hour hydrolysis, respectively. When the enzyme:substrate ratio is 1:50 hydrolysis proceeds most intensively; with a decrease in the ratio up to 1:1000 the average amount of peptides increase from 2.6 up to 4 amino acidic residua, respectively. Under conditions of denaturated collagen hydrolysis the content of hydroxyproline in solution as compared with the native one increases; in this case the links with the presence of imino-acids are easier to split, the more resistant being those formed by hydroxyproline. Within the limit of 20-45 degrees C hydrolysis of protein intensifies with a temperature rise. Within the pH range of 5.0-11.0 the maximal amount of alpha- NH2-groups and hydroxyproline is observed at pH 8.5, the minimal--at PH 5.0. Hydroxyproline in the composition of peptides appears at the beginning of hydrolysis whereas the free one of enzymes of the longer effect 24 h after the beginning of the experiment composes 12.2% of its total content in the solved products. In the insoluble part of the substrate after 3-hour hydrolysis tyrosine composes less than 25% of its initial amount in protein whereas phenyl alanine--over 70%. After 6-hour hydrolysis the solved part of the system contains about 30% of alanine and 8.9 and 6% of glycine, proline and hydroxyproline, respectively. |
The effect of different dilutions with heparin solutions or saline on blood PCO2, pH and standard bicarbonate was investigated. Blood was first equilibrated to give about 40 or 60 mmHg PCO2. The solutions were in equilibrium with room air. The effect on blood PCO2 etc. could be fully explained by the dilution with a medium having a much lower PCO2. Thus, correction of the heparin solution to pH 7.40 and PCO2 40 mmHg eliminated the effect on PCO2, pH and standard bicarbonate. With ordinary procedure for blood heparinization (about 2% dilution) the effect is practically negligible. |
The cells of yeast P. guilliermondii contain specific p-nitrophenyl phosphatase (pNPPase), the level of which depends on the cells supply with inorganic phosphorus. Partially purified enzyme is activated by ions Mg2+, Co2+ and somewhat weaker -- by ions Fe2+. With the presence of Mg2+ the enzyme activity is inhibited by ions Cd2+, Zn2+, f-, Be2+, Cu2+, Mn2+, Ca2+, MoO42-, Fe3+, Fe2+, inorganic phosphate as well as by EDTA. A mixture ions Be2+ and F- causes a complete inhibition of the activity. Ions K+ and Na+ inhibit to some extent the enzymic activity, ATP removes the inhibitory effect of monovalent cations. Km of pNPPase is equal to 3.3-10(-4) M, the molecular weight determined by the method of gelfiltration is 60 000. The enzyme is the most active at 50 degrees C and pH 9,5 PNPPase does not manifest the phosphotranspherase activity in tris-HC1-buffer. |
A urinary enzyme pattern and kidney tissue pattern were investigated simultaneously in 117 urologic patients. In contrast to all other renal disorders only the sixteen malignant tumors of the kidney showed a significant drop of gamma-GT in tumor tissue and urine. So far urinary enzymology has been used only as screening test. Measurement of gamma-GT in urine, however, permits the diagnosis of kidney tumors. |
A seminoma of both intra-abdominal testes in a forty-five-year-old patient is reported. Discovery of the tumor was fortuitous during admission for upper lobe pneumonia. Of particular interest in this case is that seminoma was found in both undescended testes. Surgical extirpation of both degenerated testes along with prostatic utricle was performed. The patient refused radiotherapy. |
Cytologic, biochemical and immunoelectrophoretic studies were carried out of amniotic fluids in 100 ewes with normal pregnancy and 40 ewes that had miscarried. Each month of pregnancy a total of 20 and 8 animals of the two groups, respectively were studied. It was found that the biochemical and metabolic processes taking place in the fetus lead to changes in the amniotic fluids altering the pH value, the alkali reserve, the content of potassium, calcium, phosphorus, alkaline phosphatase as well as their bactericidal activity. More characteristic changes linked with pregnancy were observed in the cell composition of the amniotic fluids. With advancing in age the increase in cell count was accompanied (staining with Nile blue sulfate) with a rise of the "orange cell" content. The amniotic fluids of ewes with normal pregnancy were found to contain proteins which precipitated with hyper immune sera against blood serum and kidney, heart, and placenta proteins. In ewes that had miscarried the pH values of the amniotic fluids dropped in the months when abortions took place: 7.36, 7.11, 6.90, 6.80 and 6.90, as against 7.41, 7.36, 7.28, 7.17 and 7.18, respectively. Along with pH the alkali reserve also dropped to 37.9 in the first month and 14.20 in the fifth month. In ewes that had miscarried in the 2nd, 3rd, and 4th month these values were 18.90, 14.90, and 13.80 cu. cm, respectively. In cases of abortions the protein composition of the amniotic fluids showed higher levels of the alfa and beta globulins. |
Adrenal-like lipoid-rich Leydig cells, which could be found in a cryptorchid testis, were investigated by light and electronmicroscopy. There were nodular and diffuse proliferation of these adrenal-like cells in the interstitium of the testis. Electronmicroscopically these cells are fasciculated and characterized by large liposomes, many tubulovesicular mitochondria, and a large smooth endoplasmatic reticulum. But the presence of crystals of Reinke in these cells underlined their relationship to Leydig cells. The clinical history of this case is characterised by an extreme adipositas (167 kg) and high urinary estrogenexcretion. This excretion could be suppressed with dexamethasone and stimulated with HCG. After orchiectomy estrogen excretion decreased for 4 months and then increased again, after ACTH stimulation performed by reason of adrenal insufficiency. At this time there is no evidence of adrenal tumor; in the contralateral, scrotal testis, spermiogenesis and Leydig cells are without pathologic changes as revealed by biopsy. |
Three active fractions of ATP desaminase from Actinomyces N4 of type Antibioticus were obtained by gel filtration through Sephadex G-200. Some properties of each fraction were studied: effect of pH and Mg2+, substrate specificity, effect of pH on Km. The enzyme studied could be used for preparation of ITP, IDP, IMP, inosine and hypoxantine. |
Optimal activity of RNAase from brain ribosomal fraction was observed at pH 5.4 and pH 7.9. After alimentary and conditioned-alimentary stimulation content of rRNA was significantly increased in brain, but the RNAase activity was decreased more than two-fold. After conditioned-alimentary inhibition content of rRNA was slightly decreased as compared to experiments with alimentary and conditioned-alimentary stimulation, but it was distinctly higher than in control. As compared with alimentary stimulation in the conditioned-alimentary stimulation the RNAase activity was increased at pH 5.4 and decreased at pH 7.9. |
In a period of lowest day activity of tyrosine aminotransferase, within 6-8 days after bilatheral adrenalectomy, the enzyme activity was decreased by about 20% as compared with an adequate control. At the same time, within a day and seven days after hypophisectomy, in rat liver tissue the enzyme activity was increased, approximately two-fold as compared with the normal state. Within four hrs after intraperitoneal administration into intact fasting rats at a dose of 2-2.5 g per 1 kg of body weight D-cycloserine and its dimer caused an induction of tyrosine aminotransferase by 75% and 180%, respectively. Induction of the enzyme by D-cycloserine and its dimer was inhibited by actinomycin D; the phenomenon was not observed in adrenalectomized rats. Within a day after hypophisectomy D-cycloserine did not cause the induction of tyrosine aminotransferase in rat liver tissue; to the contrary, the dimer of D-cycloserine caused induction of the enzyme, comparable to the ACTH effect, in liver tissue of hypophisectomized rats. |
Microsomal complexes of electron transfer were resistant to typical inhibitors of mitochondrial pathway of electron transport. In oxidation of NADP.H2 there were at least three point of molecular O2 reduction: NADP.H2-specific flavoprotein, Fe2+ participating in reactions of peroxidation of unsaturated fatty acids and cytochrome P-450. Efficiency of cytochrome P-450 inhibitors could not be evaluated by polarography as in the pathway several sites of molecular O2 activation were observed. In oxidation of NADP.H2 estimation of the rate of electron transfer reactions was carried out by monitoring of velocity of O2 absorption in presence of EDTA (inhibitor of the reaction of peroxidation) because about 50% of the total oxygen were utilized only in the process where NADP.H2 was oxidized. NAD.H2 oxidation, inhibited with EDTA, was activated by addition of Ca2+. |
Single administration of hydrocortisone or insulin into rats (body weight 200 g) and also combined treatment of the animals with the hormones at large doses caused a distinct increase in activities of anode and cathode isoenzymes of tyrosine-alpha-ketoglutarate transaminase in soluble fraction; total activity of the enzyme was also increased in mitochondria of rat liver tissue. |
The lactate and pyruvate content in the arterial blood and CSF of 24 patients operated on the brain under fluothane anesthesia with artificial ventilation of the lungs was measured. Towards the end of the operation and anesthesia a sizably elevated lactate level and accumulation of its excess in the blood were noted, these shifts having been more marked with hypocapnic ventilation of the lungs. An increased concentration of lactate and pyruvate in the cerebrospinal fluid was not attended by accumulation of lactate excess. |
The available data suggest that at 2 degrees and 5 degrees with a 12-day long storage in unpacked and in polymeric film packed forcemeat there occurs no propagation of the enterococci. At 22-24 degrees the multiplication of Str. faecalis var. liquefaciens proceeded similarly both in packed and unpacked forcemeat. When the temperature in the central part of the cutlets prepared from the enterococci-contaminated forcemeat reaches 7-80 degrees the bulk of the Str. faecalis var liquefaciens cells perishes, but even at 80 degrees there survive individual heat-resistant cells. |
2,6-dichlorophenol-indophenol is more stable in 75% ethanol than in aqueous solution and ascorbic acid reacts considerably faster in this media than glutathione. The activity determination of glutathione: dehydroascorbic acid oxidoreductase was based on these observations by a photometric measurement of the ascorbic acid resulting from the catalysis. Extracts from various types of wheat were tested and relatively high enzyme activities were found. |
Reproduction of Aueski disease virus in suspension cultures of trysinized cells and mechanically minced tissue of chick, duck and quail embryos was compared. The optimal conditions for cultivation of vaccine and virulent strains of virus in these systems were determined. The advantages and prospects of using suspension cultures of minced avian embryo tissue for preparation of virus materials with high biological activity and in large volumes in comparison with trypsinized cell suspensions were demonstrated. |
In dogs with elaborated rhythmic and mozaic stereotypes of secretory and motor situational conditioned reflexes specific features were revealed in the action of some neurotropic drugs (amizyl, amedine, diphacil, pediphene, chlorpromazine and sodium oxybutyrate) on preparatory (latent) conditions of excitation and inhibition, appearing in the stabilized systems of reflexes. Pharmacological analysis has pointed to the predominantly cholinergic nature of preparatory and trigger mechanisms of alimentary conditioned activity. The blockade of M-cholinoreceptors (by means of amizyl and amedine) weakens or eliminates the preparatory conditions appearing in a dynamic stereotype and disturbs the trigger reactions within three to ten days. A pediphene blockade of H-cholinoreceptors intensifies the preparatory states. |
The authors report on the drug benorylate which is available in the Federal Republic under the name of Benortan (4-acetamidophenyl-2-acetoxybenzoat). Numerous examinations have shown that it is well tolerated by mouth and that it has beneficial clinical effects with few side effects. Benorylate is a neutral, fat-soluble, water-insoluble substance which upon absorption is almost completely hydrolyzed into salicylate and paracetamol. 6 patients with classical seropositive rheumatoid arthritis and with a highly active synovialitis of one or both knee joints not previously treated received 4 g of a 40% benorylate suspension orally twice daily over a period of 9-14 days. On different days at exactly determined times of drug administration blood, and on the day of synovectomy synovial fluid and synovial tissue, were taken and frozen to - 70 degrees C and subsequently examined as to the content of salicylate, paracetamol, and unchanged benorylate. The plasma levels of salicylate and paracetamol were generally distinctly higher than the concentrations of these metabolites in the synovial fluid. Benorylate which is practically not detectable in blood is found in the synovial tissue and is detectable in greatest quantities in the most inflamed synovial villi. Benorylate can probably penetrate into the synovial membrane like its metabolites salicylate and paracetamol; it remains, however, to be examined whether the metabolites are distributed differently in different synovial areas (active inflamed and unattacked synovial tissue, respectively) in the same way as benorylate per se. |
It was found in studying the antimeningococcus activity of the leukocytic and thymus histones and their fractions that both histones were capable of neutralizing in vitro the activity of the causative agent of meningopneumonia (MP). The neutralization effect was chiefly associated with the F3 fraction rich in arginine and depended on the duration of the histone fraction contact with the MP causative agent, the weight concentration of the histone and the pH of the incubation medium. |
It was shown with the aid of immunosorption of an allergen-active substrate of E. coli 020: K84 (No. 2-rII) that protein substances taking part in the phenomenon of cell hypersensitivity were active in the humoral immunity reactions. The allergenic and immunochemical activity served as functions of the same molecules of bacterial proteins, this substantiating the use of immunochemical analysis for the study of an allergen-active bacterial substrate. By protein denaturing it is possible to obtain immunochemical inert allergen-active preparations capable of detecting the cell hypersensitivity to crude bacterial proteins. The problem of immunological polyfunctionality of proteins is discussed from the aspect of nonhomogeneity of their antigenic determinant groups. |
It was found that alpha-hemolysin of E. coli P 678 HIy+ was maximally active against human erythrocytes at pH 6.5. The hemolytic activity is characterized in time by a distinct lag-phase and a phase of the greatest velocity of the reaction immediately following it. The duration of the lag-phase and also the rate of hemolysis depends on alpha-hemolysin concentration, whose increase is accompanied by a decrease of the lag-phase and acceleration of hemolysis. There is a definite limit below which the duration of the lag-phase remains unchanged with further increase of hemolysin concentration. There was noted a linear relationship between the amount of erythrocytes taken for the test and the rate of hemoglobin release and also a temperature activation of the hemolytic reaction. |
An experimental analysis of the psychotropic activity of Leponex (in a chronic experiment on II cats) in conditions of a group interaction depicted that the preparation processes a definite tranquillizing and antipsychotic effect. In conditions of zoosocial interactions this drug promotes disappearance of neurotic reactions and a resocialization of animals in the zoosocial ierarchy. In tranquillizing doses the preparation has an antihypertensive effect and prevents the development of a long-term tonic hypertension due to emotional stress. |
Pyruvate kinase from ascites tumour cells can be eluted from phosphocellulose by very low concentrations of phosphoenolpyruvate, fructose 1,6-bisphosphate, adenosine 5'-diphosphate and pyrophosphate, respectively. The appropriate limiting conditions for "facilitated desorption" of the enzyme from phosphocellulose by these ligands have been elaborated for achieving maximum selectivity and recovery in the process of its purification. This method has been designated as "affinity elution chromatography" owing to the specific interactions between a ligand as a constituent of the eluting medium with the adsorbed enzyme, which causes its selective desorption from the ion-exchanger. Affinity elution with phosphoenolpyruvate has been found to be very effective for preparation of the M-types of pyruvate kinase. A specific activity of 420 for an almost homogeneous preparation of pyruvate kinase from ascites tumour cells has maximally been obtained. |
The influence of temperature on activity assays of the isoenzymes of L-aspartic aminotransferase in described. For this purpose, isolated human isoenzymes were added to inactivated serum. Half-saturation constants were determined at 17.8 degrees C, 25 degrees C, 30 degrees C, and 37 degrees C, and the substrate saturation and pH curves were recorded. The cytoplasmatic (c) and mitochondrial (m) GOT showed temperature-dependent differences in the half-saturation constants for the substrates L-aspartate and 2-oxoglutarate. For both isoenzymes pH 7.4 is considered the optimum regardless of the temperature of measurement, and Tris-HCl is the optimal buffer. In the Arrhenius plot there is a bent at 27 degrees C for both isoenzymes. Thermal denaturation as a possible reason for this deviation from the linearity in the Arrhenius plot could be ruled out. |
The effects of some drugs on the beating frequency of isolated cells of the chick amnion cultivated on cover slips were investigated. Cholinergic and adrenergic agonists and antagonists, serotonine, antispasmodics, coronary dilatants and local anesthetics influenced the beating frequency significantly. The isolated chick amnion cells equal in their pharmacological behaviour the intact chick amnion and smooth muscle cells of mammals but differ from isolated beating heart cells. |
1. Injections of carrageenin (1,25 mg/kg i.v.) from the 1st to the 3rd day and then each 2nd or 3rd day inhibited paw swelling in adjuvant arthritis of the rat during the time of treatment. Injections from the 11th to the 15th day were ineffective. The level of plasma kininogen was slightly decreased but the total complement serum level was significantly lowered. 2,5 and 3 mg carrageenin/kg respectively were toxic after repeated injections. After a single administration the levels of plasma kininogen and of total serum complement were decreased by 50% although paw swelling was not affected. 2. Pentosane polysulfoester (25 mg/kg i.v.) did not influence paw swelling despite daily administration from the 1st to the 17th day. Heparin (10 000 IE/kg i.v.) was likewise ineffective. 3. Single or repeated injections of compound 48/80 (0,125-0,5 mg/kg i.v.; 1-5 mg/kg i.p.; 3-6 mg/kg s.c.), reserpine (0,2 mg/kg i.p.), cyproheptadine (5 mg/kg i.v.), bromolysergic acid diethylamide (2 x 2 mg/kg i.v.) or metiamide (10 mg/kg i.v.) were without effect on paw swelling. Neither did compound 48/80 effect the complement serum level. 4. Daily administration of chloropromazine (4-10 mg/kg p.o.) or of promethazine (10-15 mg/kg s.c. or p.o.) inhibited paw swelling in the first phase of adjuvant arthritis but not in the second one. 5. The soybean trypsin inhibitor (15 mg/kg i.v.) inhibited paw swelling significantly up to the 4th day, the Kunitz inhibitor (25 000 E/kg i.v.) was ineffective. 6. The content of prostaglandin E of the inflamed paws was increased threefold in both phases of arthritis. The results are discussed with regard to the putative role of mediators of inflammation (histamine, serotonin, kinins, prostaglandins, lysosomal enzymes, lymphokines, complement). |
Treatment with neuraminidase decreased the activity of Na+,K+-activated Mg2+-adenosine triphosphatase in plasma membranes isolated from experimental granulation tissue but not that of 5'-nucleotidase or leucine-beta-naphthylamidase. A temporary lowering of the pH of the plasma membrane suspension to 2-3 inactivated all three enzymes, which remained inactive after the pH had been readjusted to 7.4. Addition of dextran preparations to the membrane suspension decreased the activity of adenosine triphosphatase. Ethanol (0.4%) had a similar effect. These marker enzymes of plasma membranes were not affected by additions of hyaluronate, chondroitin sulfate, protein polysaccharide or soluble collagen. Serotonin stimulated the adenosine triphosphatase activity slightly. About 10-20% of the protein in the plasma membrane preparation was extracted with EDTA. This "fuzzy coat" fraction yielded a distinct gel-electrophoretic protein pattern. Hyaluronidase was not helpful in cleaving this surface layer from the plasma membranes. |
Serum gastrin concentrations were measured during fasting and after feeding in duodenal ulcer patients and in dogs before and after parietal cell vagotomy (PCV). Postoperatively, fasting serum gastrin concentrations increased significantly in man and insignificantly higher in dog. After feeding, serum gastrin reached higher values postoperatively in both man and dog. The percentage rise in food-stimulated serum gastrin after PCV was higher in dog than in man. |
In a double-blind trial lasting 2 weeks, a new, long-acting antihistamine, Mequitazine, and a placebo, were compared. 115 allergic patients participated in this experiment (mequitazine n = 56, placebo n = 59). Therapeutic results and the effect on diurnal alertness were evaluated by means of a questionnaire filled in daily by the patients. Whether considering the day by day results or the results of the entire treatment period, statistically, Mequitazine (10 mg/24 hrs) is very significantly more active than the placebo. The daytime drowsiness induced by Mequitazine is statistically no greater than that induced by the placebo, whether analyzed on a day by day basis or over the entire treatment period (P = 0.23). The side effects, 8 for Mequitazine, 5 for placebo, are mild and did not lead to discontinuation of the treatment in the Mequitazine group. |
In a controlled, double-blind study 20 children and adults, suffering from summer hay fever, were treated intranasally with a daily dose of 200 mug, 300 mug or 400 mug beclomethasone dipropionate (Beconase, Becotide Nasal) or with placebo for 2 weeks during the hay fever season. No beneficial effect of the placebo treatment was observed. In patients treated with 200 mug and 300 mug beclomethasone dipropionate a day there was a moderate decrease in nasal symptom scores and in use of antihistamine tablets. As the results indicated 400 mug a day to have the most pronounced effect on nasal symptoms, this dosage is recommended for children as well as adults suffering from summer hay fever. |
In order to study the relationship between arterial PCO2 and cerebral blood flow (CBF) in hypothermia, the body temperature of artifically ventilated rats was decreased to 22 degreesC, and changes in CBF were evaluated from arteriovenous differences in oxygen content (AVDO2) at PaCO2 values of 15, 30, 40 and 60 mm Hg. The results were compared to those obtained at normal body temperature (37 degrees C) over the PaCO2 range 15-60 mm Hg. Separate experiments were performed to evaluate CBF and CMRO2 at 22 degrees C and a PaCO2 of 15 mm Hg, using an inert gas technique for CBF. The tissue contents of phosphocreatine, ATP, ADP, AMP and lactate were measured in hypothermic animals at PaCO2 values of 15, 30 and 60 mm Hg. The results showed that changes in CBF were of the same relative magnitude in hypothermia and normothermia when PaCO2 was increased from about 35 to about 60 mm Hg. However, with a decrease in PaCO2 the reduction in CBF was much more pronounced in hypothermia, and at PaCO2 15 Mm Hg CBF was less then 20% of the value measured in normothermic and normocapnic animals. The results of the metabolite measurements gave no evidence of tissue hypoxia in spite of the pronounced reduction in CBF. Although the results demonstrate that the brain of a hypothermic animal is protected against the harmful effects of a lowered CBF, it may not warrant recommending hyperventilation in clinical cases of hypothermia, especially not in patients with arteriosclerosis or cerebrovascular diseases. |