bluuebunny/crossref_metadata_2025_split huggingface dataset:
Testosterone Metabolism by Gastrointestinal Microsomes
Authors: Harri M.‐P. , Hartiala K. , Nienstedt W. , Salmi H. A. 
Published: December 2008

AbstractIn incubation studies with the microsonial fraction of various tissues of the rat, the ability to metabolize testosterone, determined as the decrease in NADPH2 absorbance, was found to be rather high in various gastrointestinal tissues but lower in several non‐gastrointestinal tissues. In one case, some of the numerous metabolites were identified with hepatic, ileal mucosal and heart tissues. All of them apparently produce at least 4‐androstenedione, 5α‐androstanedione, and 17 β‐hydroxy‐5α‐androstan‐3‐one.
Thermogenesis of Brown Adipose Tissue Reflected in Mitochondrial Respiratory Control
Authors: Andersen H. T. , Christiansen E. N. , Grav H. J. , Pedersen J. I. 
Published: December 2008

AbstractThis paper presents data to demonstrate a loosening in the coupling of phosphorylation to respiration in brown adipose tissue mitochondria during cold exposure. This loosening of coupling was accompanied by a significant increase in the respiratory rate. Moreover, the mitochondrial energy conserving mechanism has been shown to recouple when cold exposed animals are returned to thermoneutral surroundings. The degree of coupling of phosphorylation to respiration has been investigated in terms of the P/O ratio and of the respiratory control index. With brown adipose tissue mitochondria, both of these relationships have to be studied independently in order to obtain data relevant to the problem of variations in the energy conserving mechanism since they are differently affected by the in vitro conditions used. Our findings indicate that the non‐shivering thermogenesis of brown adipose tissue is physiologically regulated and perhaps in a more sophisticated way than by simple on‐off control. Guinea‐pigs have been used in the experiments.
Effects of Feeding States on Lipid Radioactivity in Liver, Muscle and Adipose Tissue after Injection of Labelled Glucose in the Rat
Authors: Björntorp P. , Krotkiewski M. , Larsson B. , Somlo‐Szücs Z. 
Published: December 2008

Abstract0.5 g of glucose/kg b.w. and (U‐14C) glucose was injected i.v. to ad libitum fed, 18 hrs fasting or 48 hrs fasting‐48 hrs refed rats. After 60 min blood glucose had decreased to preinjection values. Recirculation of radioactive metabolites was found in blood in pyruvate‐lactate and to a small extent in glyceride‐glycerol. Rats were sacrificed at this time and radioactivity measured in chloroform: methanol extracts of homogenates from muscle, liver and different adipose tissue regions. Furthermore, radioactivity was measured in fatty acids. Fatty acid radioactivity in different regions was considered to be due to the local synthesis of fatty acids, because no recirculation was discovered at the time of analysis. Liver and adipose tissue fatty acid synthesis was most pronounced in the refed rats. Adipose tissue showed higher fatty acid synthesizing activity than the liver in ad libitum fed, but not in refed rats. Glyceride‐glycerol radioactivity was rather high in muscle. In adipose tissue it was more constant in different feeding states than fatty acid radioactivity was. By additions of measured radioactive metabolites glucose uptake in adipose tissue was roughly estimated to a few per cent of total glucose uptake.
The Effect of Dinitrophenol on Secretory Potentials, Secretion and Potassium Accumulation in the Perfused Cat Submandibular Gland
Authors: Petersen Ole Holger 
Published: December 2008

AbstractDinitrophenol strongly depresses salivary secretion and potassium uptake after acetylcholine‐induced potassium loss in the perfused cat submandibular gland. However, transmembrane secretory potentials recorded from the acinar cells after intraarterial injections of acetylcholine change little after introduction of dinitrophenol. This seems to indicate that the secretory potentials are not directly dependent on energy metabolism and that the mechanism of these potential changes may be an increase in ion permeability of the basal acinar cell membrane.
Exchange of Glucose between Plasma, Brain Extracellular Fluid and Cerebral Ventricles in Cats and Effects of Intraventricular Acetazolamide and Insulin
Authors: Brondsted H. E. 
Published: December 2008

AbstractThe ventriculo‐aqueductal perfusion technique was used for a quantitative study of the transport of glucose between the cerebral ventricles and surrounding tissues in cats. The inflow perfusion fluid contained U14C‐D‐glucose and unlabelled D‐glucose. Carrier systems appeared to operate symmetrically. Intraventricular acetazolamide or insulin did not influence the transport of glucose in the brain. At zero net flux of glucose in the system the concentration of glucose in brain extracellular fluid was estimated to be the same as in the ventricles, i.e. about 40 per cent below the concentration in arterial plasma water.
Effect of Hypotonic Mannitol and Saline Load on Diluting Capacity in Man
Authors: Aperia A. , Broberger O. , Feychting H. 
Published: December 2008

AbstractThe effect of hypotonic mannitol and saline loading on the urinary diluting capacity in man has been examined. The further interpretation of the data was built on the assumption that the free water formation is determined by distal tubular Na+ reabsorption. Thus it could be demonstrated that the distal tubular Na+ reabsorption was at first enhanced and later suppressed by progressive increases in the total distal tubular Na+ delivery. No relationship could be demonstrated between distal tubular Na+ reabsorption and urinary Na+ concentration. This was interpreted to mean that the distal tubular Na+ reabsorption was independent of the transtubular Na+ gradient.
Mechanisms Involved in the Cat's Blink Reflex
Authors: Lindquist Chr. , Mårtensson A. 
Published: December 2008

AbstractTapping on the cat's facial skin elicits two successive reflex discharges in the orbicularis oculi. The responses have similar thresholds and are most readily evoked from the skin overlying the muscle. Both discharges result also on tapping on a skin flap over the muscle, whereas tapping on the muscle belly is ineffective. Similar responses are elicited on electrical stimulation of low‐threshold trigeminal afferents; the central relay time indicates that the early response is mediated through a polysynaptic reflex arc. Stimulation of high‐threshold afferents in the facial nerve may give a long latency reflex response in the orbicularis oculi and facilitate transmission of a short‐latency reflex response in the same muscle set up by stimulation of trigeminal afferents. Recordings from peripheral filaments provide no evidence for the presence of afferent fibers from muscle spindles or other types of proprioceptors in the facial and trigeminal nerves. A twitch contraction of the orbicularis oculi elicits a high‐amplitude reflex response in the muscle through activation of trigeminal exteroceptive afferents; the possibility is considered that such afferents may serve a proprioceptive function in monitoring the degree of contraction of the facial muscles.
Renal Reabsorption and Metabolic Conversion of Galactose in the Cat
Authors: Rasmussen S. Nybo 
Published: December 2008

AbstractExtrahepatic elimination of galactose occurs mainly in the kidney. Urinary excretion as well as metabolic conversion may be of significance. At plasma concentrations of galactose between 60 and 1200 mg per liter in cats urine to plasma concentration ratios below one were never observed. At low filtered loads the reabsorption fraction was close to 1.0. At higher loads the reabsorption fraction decreased and seemed to converge towards 0.6. The rate of metabolic conversion of galactose in the kidney — calculated as the RBF times the arterio‐venous concentration difference minus the excretion rate — exceeded considerably the reabsorption rate at low filtered loads. At increasing loads the metabolic rates approached maximum values between 50 and 100 μg per minute and gram kidney weight. The capacity of the kidney for metabolic conversion of galactose appeared (per gram organ weight) to be in the same order of magnitude as that of the liver. Push‐flow experiments indicated that reabsorption of galactose takes place exclusively in the proximal tubular system. When, at low plasma concentrations, the metabolic rate exceeds the reabsorption rate the intracellular concentration of galactose in the tubular wall cells may stay low and this may promote diffusion into the cells and account for the high reabsorption fractions found (conversion reabsorption). At higher concentrations, where the reabsorption rate exceeds the metabolic rate, reabsorption is probably due increasingly to carrier‐facilitated transcellular backdiffusion.
Effects of Increased Liver Metabolism of Nicotine on Its Uptake, Elimination and Toxicity in Mice
Authors: Stålhandske Torbjörn 
Published: December 2008

AbstractMale albino mice were injected intraperitoneally or intravenously with14C‐labelled nicotine. Both untreated and phenobarbital pretreated mice were used. The concentrations of nicotine and metabolically formed cotinine were determined in the brain, liver and blood 1, 2.5, 5, 10, 20 and 60 min after injection. It was found that phenobarbital pretreated mice exhibited an enhanced liver metabolism of nicotine both in vitro and in vivo. The increased liver metabolism caused a significant decrease of nicotine concentration in the brain only when nicotine was given intraperitoneally. Phenobarbital pretreatment elevated the intraperitoneal LD50value 2–3 times and also increased tolerance to repeated sublethal doses of nicotine. No change in the intravenous LD50value was observed.
Acetylation of P‐Aminohippuric Acid in the Kidney. Renal Clearance of P‐Aminohippuric Acid in the Kidney. Renal Clearance of P‐Aminohippuric Acid and N4‐Acetylated P‐Aminohippuric Acid in Pigs
Authors: Gyrd‐Hansen N. , Rasmussen Folke 
Published: December 2008

Abstract20 pigs weighing 21–124 kg were used to determine the clearance of PAH, N4‐acetylated PAH and PAHtotal, and for determination of acetylation of PAH and de‐acetylation of N4‐acetylated PAH in the kidney. By examining blood samples taken from a. renalis and v. renalis and urine collected simultaneously, the acetylation and de‐acetylation of PAH and N4‐acetylated PAH in the kidney were determined on 9 pigs. 6 of these acetylated PAH (1.5–10 per cent), while 3 de‐acetylated N4‐acetylated PAH (2–21 per cent). The extraction percentage for PAH and N4‐acetylated PAH were 91 ± 1.4 (S.E.M.) and 84 ± 2.1 respectively. The ratio between clearance of N4‐acetylated PAH and PAH was found to be 1.08 ± 0.07 and between clearance for PAHtotal and PAH 1.01 ± 0.02.
The Relationship between Arylesterase Activity and Growth in Rats
Authors: Augustinsson Klas‐Bertil , Henricson Bengt 
Published: December 2008

AbstractThere was a highly significant negative correlation between blood plasma arylesterase activity and growth rate in male rats when the enzyme activity was determined at younger ages (11–32 days). In females the correlation was only vaguely indicated. A direct or indirect causal relationship between the two parameters is discussed.
Localization of a Microelectrode Tip in Muscle Cell
Authors: Nickels J. 
Published: December 2008

AbstractA method is described for accurate localisation of a recording glass microelectrode in muscle cell and subsequent histochemical staining of the myoneural junction of the cell with cholinesterase and, finally, for localisation of the recording site itself in an electronmicroscopic picture. Microelectrodes were filled with 1.1 M of K4Fe(CN)6 and 1.5 M of Na2HPO4. With the microelectrode at the recording point, a 1: 1 mixture of 0.1 M of Pb(NO3)2 and 5 per cent acetate‐buffered (pH 5.6) glutaraldehyde was applied to its environment and anions were driven electrophoretically from the microelectrode with a DC of about 2 μA for 5–10 sec. into the muscle cell. The white sediment that originated was turned dark with 1 per cent (NH4)2S. The size of the sediment was 5–20 μ. It was seen clearly under the light microscope. This method did not affect the histochemical stainability of the motor end‐plate. As the sediment contained heavy metals it was visualised also in the electron microscopic picture after further fixation for one hour in buffered glutaraldehyde. The sediment was visible also in the Epon resin block and this helped the trimming of the specimen. The sediment consisted in a normal electron microscopic picture of rough heavy‐metal grains.
Contraction Times of Twitches Evoked by H‐Reflexes
Authors: Buchthal Fritz , Schmalbruch Henning 
Published: December 2008

AbstractIsometric twitches of the same amplitude were initiated in the human soleus muscle by near threshold H‐reflexes and by stimuli to the efferent nerve (M‐responses) or to the end‐plate zone. The time to peak‐force was longer in reflex than in directly activated twitches: The range was 84 to 130 msec and 52 to 100 msec, respectively (36–37°C).
Circulatory Effects of Interruption and Stimulation of Cardiac Vagal Afferents
Authors: ÖBerg B. , White S. 
Published: December 2008

AbstractThe influence of the rhythmic activity in cardiac vagal afferents on the circulation was analyzed in chloralose‐anesthetized cats by observing the cardiovascular responses to sudden interruption of this activity and to afferent stimulation of the cardiac nerves. The evoked responses were compared with those produced by “unloading” and stimulation of arterial baroreceptors. — Elimination of the impulse traffic in vagal afferents produced a blood pressure rise, a tachycardia and vasoconstrictions in skeletal muscle, intestine and kidney, indicating a tonic restraint of these afferents on the medullary vasomotor centre. The responses were generally moderate in the presence of normally functioning arterial baroreceptors but were pronounced after elimination of “buffering” influences from these receptors. — Comparisons of the inhibitory influences from vagal cardiac afferents and baroreceptor afferents, respectively, on the vasomotor centre indicated that the former were preferentially directed to neurons controlling the efferent discharge to the heart and the renal vessels. There was no evidence for a particularly strong engagement of the capacitance vessels in reflex patterns mediated through cardiac afferents. — Low frequency afferent stimulation of the cardiac nerves generally induced a profound brady‐cardia, which was probably due to stimulation of fibres not normally tonically active.
In Vitro Assay of the Stimulatory Effect of Hypoxic Serum on Cellular Proliferation in the Erythron
Authors: Kivilaakso E. 
Published: December 2008

AbstractThe effect of experimental hypoxia on mitotic homeostasis in the erythron was investigated by means of an in vitro technique. The proliferative responses were measured in terms of 3H‐thymidine incorporation in normal rat bone marrow cells in vitro. Test serum was collected from rats kept in hypoxic conditions. The hypoxic serum caused a significant (22%) stimulation of total incorporation of 3H‐thymidine in the target cells as compared to normal serum. Autoradiographic analysis revealed that this effect was due to an increase in the number of bone marrow cells labelled. The stimulation proved to be tissue‐specific: the number of labelled erythrocyte precursors was increased by 45%, while the effect on the granulocyte population was negligible. Gel filtration of the hypoxic and normal sera on Sephadex G‐200 revealed that the effect was exerted by a stimulatory factor present in the hypoxic serum, there being no substantial difference between the two sera in their contents of the inhibitor, chalone. Elution parameters of the stimulator on Sephadex G‐200 suggested a molecular weight in the region of 60,000–70,000. As judged from the molecular weights, this stimulator and erythro‐poietin may be identical, but the exact relation of the two factors cannot be deduced with certainty on the basis of the data available. The results are discussed.
Inhibitory Control of the Abdominal Stretch Receptors of the Crayfish
Authors: Jansen J. K. S. , Njå A. , Walløe L. 
Published: December 2008

AbstractBy stretch activation of the slowly adapting abdominal stretch receptor of the crayfish, we have found reflex activation of two efferent spikes of different amplitudes in the dorsal nerves of the same and neighbouring segments. The large as well as the small efferent spike inhibit the discharge of the receptor. It is suggested that these two units represent the thick and thin accessory fiber described by Alexandrowicz, as making synaptic contacts with the receptor cell.
The Significance of Age for the Phosphatase Activity of Seminal Fluid
Authors: Wikström Carin 
Published: December 2008

AbstractTwo age groups of rabbits have been compared with respect to the activity of seminal acid phosphatases. The ejaculates of the young (1 year old) rabbits showed about twice as high phosphatase activity as the ejaculates of the older rabbits (3–5 years old). No differences in ejaculate volumes and libido have been observed.
Studies on the Mechanism of Action of Lithium Ions
Authors: Giacobini E. , Stepita‐Klauco M. 
Published: December 2008

AbstractWhen the extracellular Na+was replaced by lithium (Li+) the frequency of the impulses elicited by stretching the stretch receptor of crayfish was changed and then inhibited. This effect was not due to the lack of extracellular Na+. Higher firing rate facilitated and low extracellular K+delayed the Li+effect. Ouabain alone (10‐4M) changed the impulse activity in a similar manner to Li+replacement. Ouabain (10‐5M) decreased the rate of recovery during wash‐out after Li+replacement. The Li+‐induced increase in the frequency of the impulse activity was probably the result of a lower intracellular K+concentration, the block of the spike activity being due to the accumulation of Li+in the cell. The Na+pump participated in the recovery of the spike activity after Li+replacement.
Calcium supplementation and thyroid hormone protect against gentamicin‐induced inhibition of proximal tubular Na+, K+‐ATPase activity and other renal functional changes
Authors: FUKUDA Y. , EKLÖF A.‐C. , MALMBORG A.‐S. , APERIA A. 
Published: December 2008

Gentamicin can cause proximal tubule necrosis. We have shown that inhibition of PT Na+, K+‐ATPase activity is rapidly induced by gentamicin. We have now investigated whether manipulations known to attenuate the negative effects of gentamicin on renal excretory capacity, i.e. high calcium intake and L‐thyroxine treatment, will also attenuate gentamicin‐induced inhibition of Na+, K+‐ATPase activity and ameliorated signs of proximal tubule damage. Rats were gentamicin‐ or vehicle‐treated for 7 days. Sub‐groups were given 4% calcium (Ca) supplements or L‐thyroxine 20μg 100 g‐1body weight daily. Gentamicin significantly reduced the glomerular filtration rate and increased the urinary excretion of the proximal tubule lysosomal enzyme,N‐acetyl‐β‐d‐glucosaminidase. Gentamicin significantly reduced proximal tubule Na+, K+‐ATPase activity, measured in single permeabilized proximal tubule segments. Sodium excretion was inversely correlated to proximal tubule Na+, K+‐ATPase activity. Both calcium and L‐thyroxine alleviated all gentamicin‐induced side‐effects on renal function as well as on proximal tubule Na+, K+‐ATPase activity. Calcium and L‐thyroxine had no significant effect on renal function. L‐thyroxine, but not calcium, increased proximal tubule Na+, K+‐ATPase activity in control rats. Renal cortical tissue gentamicin concentration was not influenced by calcium but was significantly lowered by L‐thyroxine.Two procedures which, via different mechanisms, afford protection from gentamicin‐induced changes in renal function also give protection from gentamicin‐induced inhibition of Na+, K+‐ATPase activity. This suggests that loss of integrity of the Na+, K+‐ATPase enzyme contributes to gentamicin‐induced nephrotoxicity.
In vivo and in vitro studies on the effects of mGnRH on oestradiol‐17β inter‐renal production in the female frog, Rana esculenta, during the post‐reproductive period
Authors: ZERANI M. , GOBBETTI A. 
Published: December 2008

Plasma oestradiol‐17β was measured by RIA, in female, Rana esculenta, submitted to hypophysectomy, gonadectomy, or both, and treated with mammalian gonadotropinreleasing hormone (mGnRH), homologous pituitary homogenate, or both, during the post‐reproductive period. In addition, the oestradiol‐17β release was measured in in vitro incubations of ovaries or interrenals treated with mGnRH, pituitary, or both, during the same period. In vivo and in vitro mGnRH and/or pituitary directly stimulated the production of oestradiol‐17β by the interrenal, but not by ovary, although the stimulatory effects of the pituitary are minor and delayed with respect to those of mGnRH.These results seem to indicate that mGnRH and pituitary, with probably different mechanisms, stimulate the interrenal to produce high levels of oestradiol which is involved in the post‐reproductive refractoriness.
Inefficiency of bilateral amygdaloid lesions to reduce the transient motor reactions exhibited by swine during exposure to CO2
Authors: FORSLID A. , HÄGGENDAL J. 
Published: December 2008

The aim of the study was to evaluate from the ethical point of view the importance of transient muscular jerks commonly exhibited by swine at an early stage of pre‐slaughter CO2 anaesthesia.The influence of 5 min restraint upon plasma concentrations of adrenaline (A) and noradrenaline (NA) was studied in swine (n= 6) before and after bilateral lesioning of the amygdaloid region of the brain, as were the motor reactions of the same and three other animals during 1 min exposure to 80% CO2. The A and NA responses to the restraint became almost extinguished after amygdaloid lesioning in three of the animals, were reduced by about 50% in one swine, whereas no reduction was seen in the other two animals investigated. The amygdaloid lesioning did not visibly influence the latency for, and the duration and intensity of the muscular jerks manifested by the swine during the CO2‐exposure.The results do not favour the possibility that transient motor reactions exhibited by swine during pre‐slaughter CO2‐exposure are manifestations of emotional stress. Instead, the study indirectly supports the idea that the cause of the muscular jerks may be disinhibition of subcortical motor centres being inactivated by the CO2‐anaesthesia somewhat later than neocortical cells normally exerting the inhibition.