bluuebunny/crossref_metadata_2025 huggingface dataset:
THE EFFECT OF DICUMAROL ON PROTHROMBIN TIME IN RATS AND ITS RELATION TO VITAMIN K CONTENT OF LIVER
Authors: Chandrasekhar N. , Hickie R. A. , Millar G. J.
Published: April 2011

On administration of varying doses of vitamin K1 (2-methyl-3-phytyl-1,4-naphthoquinone) and vitamin K3 (2-methyl-1,4-naphthoquinone) to dicumarol-treated rats, it was observed that vitamin K1 at a low dosage strongly counteracted the dicumarol effect as measured by prothrombin time. The rate of lowering of prothrombin time depended upon the dose of vitamin K1 administered. Vitamin K3 did not counteract dicumarol even at a high dosage. In experiments with radioactive vitamin K1 in rats treated with dicumarol, it was observed that a positive correlation exists between the amount of radioactivity present in the liver and the shortening of prothrombin time in the animals.Rats showed wide individual variations in their response to dicumarol. This response could be altered by changing the dosage. The animals did not develop any particular tolerance to dicumarol on 3-day courses of this drug when the courses were repeated twice at 3-week intervals.Rats that were well fed and received dicumarol daily for 10 days acquired tolerance to the drug after 2 days as judged by prothrombin time values. Partial starvation in dicumarol-fed rats prolonged the prothrombin times and increased the percentage mortality. Results obtained in other work in this laboratory suggest that partial starvation probably constitutes a stress.
SALT AND WATER DISTRIBUTION IN HEREDITARY AND IN INDUCED HYPOTHALAMIC DIABETES INSIPIDUS IN THE RAT
Authors: Friedman Sydney M. , Friedman Constance L.
Published: April 2011

Salt and water metabolism and the distribution of Na, K, and water in gastrocnemius and in aorta were measured in spontaneous hereditary hypothalamic and in surgically induced diabetes insipidus in the rat. The degree of severity in the two types of the disease was estimated in terms of salt and water handling. Water turnover in 24 hours was about equal to body weight in the hereditary disease and about 60% of body weight in the induced disease. Skeletal muscle Na increased more than 20% in the familial disease, and the gain involved both cells and environment. There was no corresponding loss of K. Similar changes of lesser degree were noted in the induced disease. The degree of Na accumulation appears to be partially dependent on the duration of the disease.
THE DEPOSITION OF AEROSOLS IN THE RESPIRATORY TRACT: II. DEPOSITION IN CIGARETTE SMOKING
Authors: Beeckmans J. M.
Published: April 2011

A computer program was developed which calculates the deposition of cigarette smoke particles in the respiratory tract of the smoker. The basic equations used to describe the particle deposition and the mixing of air in the respiratory tract have been described in a previous publication by the author on the deposition of aerosol particles during normal breathing. However, an improved model of the respiratory tract, similar to a model suggested by Weibel, was employed. Comparison of the computer results with experiments was difficult, because of the absence of complete data in the literature. However, when estimates were made regarding the true experimental conditions under which certain results on smoke retention were obtained, a partial correlation was made possible by assuming a much larger mean particle size than is known to exist in raw smoke. The increase in mean particle size was tentatively ascribed to water absorption in the respiratory tract. Even with this assumption, the correlation was extremely poor at very low smoke inhalation volumes.The computer program analysis indicated that it should be possible to substantially reduce smoke deposition, without reducing smoke inhalation, by puffing on the cigarette at some point in the breathing cycle other than at the end of expiration, as is customary. This method of smoking was found to be as pleasurable as the normal method by most of the smokers who have used it.
THE RETENTION OF I131 IN THE BLOOD PLASMA OF MOLYBDATE-FED RABBITS
Authors: Robinson G. A. , Riddell Patricia E. , McCarter Anne
Published: April 2011

The initial rate of uptake of I131 by the thyroids of 44 molybdate-fed rabbits, as determined by in vivo counting, was slightly less than for 34 control rabbits. Thirty to sixty hours after the I131 injection, thyroidal I131 levels were approximately equal in these two groups. Thoracic counting rates decreased more slowly in molybdate-fed rabbits, resulting by 72 hours in I131 levels 3 to 35 times those of the control rabbits. Differences in the I131 concentrations of protein-free plasma supernatants were of the same magnitude as for thoracic counts. The greater the effect of molybdate on the individual rabbit, the greater the I131 retention in the plasma. For example, the product moment correlation coefficient for supernatant I131 concentrations at 72 hours against haemoglobin concentrations for the 27 surviving molybdate-fed rabbits in one grouping of experiments was −0.77. Protein-free supernatant containing I131 was chromatographed on plates coated with silica gel in 1:4:5 dioxane – butan-1-ol –2 N NH3 (aqueous). A single I131 band was found and tentatively identified as iodide by comparison with plates treated with iodide-127.
CORRELATION BETWEEN BODY HABITUS AND CROSS-SECTIONAL AREA OF RIBS
Authors: Takahashi Hideaki , Frost Harold M.
Published: April 2011

A correlation study was performed of the relationship between the total cross-sectional area of the fifth, sixth, or seventh rib in its middle third, and the height, weight, and sex of its owner. The study involved 115 metabolically normal people and yielded high correlation coefficients between the calculated and observed total rib cross-sectional areas of 60 males and 55 females. It is suggested that the total cross-sectional area at a standard bone sampling site be used as a basis for normalizing measures of the severity of osteoporosis. This would allow one to make improved comparisons of the severity of osteoporosis between persons of different body habitus and sex.
ABSORPTION OF BILIARY THYROXINE FROM LOOPS OF SMALL INTESTINE
Authors: Cottle W. H. , Veress A. T.
Published: April 2011

The absorption of labelled thyroxine and its glucuronide conjugate from loops of small intestine has been studied in rats. Free thyroxine was found to be more readily absorbed than its conjugate, suggesting that formation of the conjugate by the liver facilitates excretion of the hormone. No difference was found between the rate of absorption of these materials from loops prepared in cold-acclimated rats and from those prepared in warm-acclimated rats. Labelled D-thyroxine added to bile was found to be absorbed as readily as added L-thyroxine.
THE EFFECT OF TOLBUTAMIDE (RASTINON) ON THE LEVELS OF GLUCOSE AND INORGANIC PHOSPHORUS OF BLOOD IN NORMOTHERMIC AND HYPOTHERMIC RATS
Authors: Crawford Anne L. , Haist R. E.
Published: April 2011

Blood sugar, inorganic phosphorus, and hematocrit values were measured in normothermic and hypothermic (25 °C) fasted rats injected intra-arterially with tolbutamide (Rastinon) and a control solution. Doses of 12.5, 25, 50, and 100 mg/kg body weight of tolbutamide led to hypoglycemia in the normothermic rats, whereas doses of 25 and 200 mg/kg tolbutamide had no effect on the blood sugar levels of hypothermic rats. Doses of 25, 50, 100, and 200 mg/kg caused the blood inorganic phosphorus levels to fall, and in the so-called "normothermic" rats the colonic temperature was reduced. A dose of 200 mg/kg injected intra-arterially led to a fall in the inorganic phosphorus levels of blood in hypothermic rats.
LEFT INTRAVENTRICULAR PRESSURE GRADIENT UPON CARDIAC STIMULATION IN THORACOTOMIZED HEMORRHAGED RATS
Authors: Dieudonné J. M.
Published: April 2011

Pressures were recorded in thoracotomized rats at the ascending aorta and at various sites of the left ventricle. After induction of an acute hemorrhage, injection of norepinephrine elicited the appearance of a large late-systolic pressure gradient between the left ventricular main chamber and ascending aorta, but not between the outflow tract and ascending aorta. Restoration of the initial blood volume abolished any significant pressure gradient in response to nor-epinephrine.The systematic appearance of an intraventricular pressure gradient in these anatomically normal hearts required the simultaneous presence of two experimental conditions: (a) a reduced blood volume as a predisposing factor; (b) a stimulation of the cardiac force of contraction in the presence of a relatively-lower aortic resistance as a triggering factor.
THE CHRONIC ORAL TOXICITY OF CAFFEINE
Authors: Boyd Eldon M. , Dolman Mortimer , Knight Lois M. , Sheppard E. Patricia
Published: April 2011

The toxicity of caffeine administered daily by intragastric cannula to female albino rats was determined over 100 days, i.e., 1/10 of the animal's life-span. The maximal LD0(0.1L) or maximal daily dose producing no deaths over 100 days was 110 ± 2.5 mg/kg; the LD50(0.1L), 150 ± 3.1 mg/kg; and the minimal LD100(0.1L), 191 ± 5.7 mg/kg. Doses of the order of the LD0(0.1L) produced a mild cerebral hyperemia, occasional psychotic-like self mutilation, gastric ulcers, and inhibition of oogenesis; hypertrophy of the salivary glands, gastrointestinal tract, liver, heart, kidneys, and lungs; a stressor reaction in the adrenal and thymus glands; minor changes in organ water levels; an occasional death apparently from bronchopneumonia; but in general a normal appearance, and no change in growth rate, eating and drinking habits, or in the volume, pH, and protein and glucose content of the urine. Doses of the order of the LD50(0.1L) also produced a polydipsia and diuresis and an occasional dermatitis; some degree of toxic nephritis, hepatitis, myositis, thyroiditis, and loss of red pulp in the spleen. Doses of the order of the minimal LD100(0.1L) and higher produced an increasingly more toxic reaction, which was similar to that seen in the syndrome at the acute oral LD50 dose and that due to fortnight partial starvation. Abrupt withdrawal of caffeine was followed for 1 week by decreased locomotor activity, a slight decrease in colonic temperature, and proteinuria and glycosuria.
ACUTE EFFECTS OF ETHANOL ON TISSUE ELECTROLYTES IN THE RAT
Authors: Kalant H. , Mons W. , Mahon M. A.
Published: April 2011

Groups of Wistar albino rats of both sexes received either gavage with low or high doses of water, ethanol in water, or no treatment. Ninety minutes later they were decapitated and exsanguinated, and samples of brain, ventricular myocardium, renal cortex, liver, skeletal muscle, whole blood, and plasma were obtained. These were analyzed for water, chloride, sodium, and potassium. Corrections were made for residual blood in the heart, kidney, and liver samples. On the basis of an assumed extracellular location of chloride, the intracellular content of water and the concentrations of sodium and potassium in the intracellular water (i.e., chloride-free space) were calculated.All treatments produced a fall in the water content of the blood and a rise in potassium, which were taken as evidence of hemoconcentration. The plasma showed a fall in sodium, which was most marked following the high dose of water and was interpreted as a dilution effect; and a fall in potassium after ethanol, which is not yet explained. Most tissues tended to show a rise in calculated intracellular water and sodium and a fall in intracellular potassium after ethanol, especially after the high dose (4 g/kg). These changes, although statistically significant only in liver and kidney, are compatible with data reported elsewhere which show that ethanol inhibits the active transport of cations across cell membranes.
EFFECT OF PROLONGED INFUSION OF ISOPROTERENOL ON PLASMA VOLUME AND BLOOD LACTATE AND PYRUVATE IN THE DOG
Authors: Scott H. M. , Peretz D. I. , Duff J. H. , MacLean L. D. , McGregor M.
Published: April 2011

An essential preliminary to therapeutic trial of isoproterenol in the treatment of shock was to ascertain whether prolonged infusion of this drug could of itself cause reduction in plasma volume or increase in blood lactic acid levels. In six dogs the levels of plasma volume and of blood lactate and pyruvate were determined at three dosages, 0.067, 0.13, and 0.33 μg/kg per minute, each maintained for 2 hours, before and after splenectomy. There was a small decrease in plasma volume (average, 4.0%) which was not related to the dosage level. The smalt increases in lactate and pyruvate levels (average, 11.4 and 0.4 mg/100 ml, respectively) were also unrelated to dosage. Excess lactate resulting from infusion (average, 6.0 mg/100 ml) did not differ significantly from zero. It was concluded that these changes were of insufficient magnitude to contraindicate the further trial of isoproterenol in the treatment of shock.
FREE FATTY ACID METABOLISM IN CHINESE HAMSTERS
Authors: Campbell James , Green G. R.
Published: April 2011

In normal Chinese hamsters (Cricetulus griseus) the mean concentration of free fatty acids (FFA) in serum varied from group to group, but was (i) consistently 4 to 9 times greater than in rats, dogs, or man; (ii) slightly higher than in Syrian hamsters; (iii) two- to four-fold higher than in fasting or alloxan-diabetic rats. The epididymal adipose tissue of the Chinese hamster (i) had initial concentrations of FFA comparable to those in the rat and Syrian hamster; (ii) released, in the same time interval, 8- to 10-fold more FFA in vitro than this tissue of the rat; (iii) had higher concentrations of FFA after incubation than the incubated tissue of the rat. The retroperitoneal (perirenal) adipose tissue of the Chinese hamster was less active in release of fatty acids in vitro than the epididymal, but was, however, more active than the epididymal adipose tissue of the rat. These characteristics of FFA metabolism in the Chinese hamster were apparently attributable to species, not to age, diet, or sex. In the Chinese hamster, the weight of the epididymal adipose tissue per gram of body was relatively high. It appears that in this species the rate of release of fatty acids from adipose tissue is great, leading to high FFA concentrations in serum.In Chinese hamster and rat adipose tissues in vitro, glucose and insulin (separately) reduced the rate of release of FFA and the amount of FFA in the tissues, but glucose and insulin together produced the greatest reductions. The net reduction in FFA release by glucose and insulin in vitro was greater in tissue from the Chinese hamster. Insulin markedly increased glucose uptake by the adipose tissues of both species. The possible relation of the results to spontaneous diabetes in the Chinese hamster is discussed.
BIOLOGICAL ACTIVITY OF BOVINE BRAIN CONSTITUENTS
Authors: Shaw R. K. , Chandler B. H. , Stewart W. C.
Published: April 2011

Bovine brain extracts have been fractionated into 89 different subfractions, and the serotonin-like and acetylcholine-like properties of each determined. Thirty-three of the subfractions exhibited biological activity: 6 possessed acetylcholine-like activity; 5 possessed serotonin-like activity; 12 possessed activity of an unknown type; and the remaining 10 possessed more than one type of activity. Eighty of the subfractions contained peptides as revealed by acid hydrolysis. However, it was not established whether the peptides accounted for the biological activities noted.
SEMIPERMEABLE AQUEOUS MICROCAPSULES: I. PREPARATION AND PROPERTIES
Authors: Chang T. M. S. , MacIntosh F. C. , Mason S. G.
Published: April 2011

Methods have been developed for depositing thin stable semipermeable polymer membranes around aqueous microdroplets (mean diameter down to 5 μ or less) by either interfacial polymerization or interfacial coacervation. The enclosed aqueous phase may contain enzymes or other proteins, cell fragments, or intact cells. Examples of methods for preparing such microcapsules are given in detail, and some of their properties are described.
OCCURRENCE AND PREVENTION OF POSTASPHYXIAL INTRAVENTRICULAR PRESSURE GRADIENTS
Authors: Dieudonné J. M.
Published: April 2011

Following the earlier demonstration of a systolic pressure gradient across the ventricular outflow tract after exogenous cardiac stimulation, a severe stressor, asphyxia, was produced in rats to determine whether inotropic stimulation of endogenous origin would induce comparable intraventricular systolic pressure gradients. Only during the oxygen rebound phase was a transient ventriculo–aortic pressure gradient demonstrable; it did not appear after treatment with dichloroisoproterenol and was inhibited by bilateral adrenalectomy. It is concluded that the pressure gradient coincided with a marked inotropic stimulation resulting from the release of catecholamines with adrenomedullary participation under adequate oxygenation.
DYED FIBRIN PLATE ASSAY OF FIBRINOLYSIS
Authors: Barta George
Published: April 2011

A fibrin plate test for assaying fibrinolytic activity has been developed by dyeing the fibrin with congo red and applying the protease solution to the entire surface of the fibrin film. Enzymatic digestion results in uptake of the dye by the supernatant solution, which is then measured by colorimetry. The applicability of the test for rapid and accurate evaluation of protease activity is demonstrated by dose–response curves of enzymatic digestion, and their standard errors. The possible advantages of the dyed-plate test over other fibrinolytic assays are discussed.
DEVELOPMENT OF A STRAIN OF RATS WITH GREATER THAN NORMAL SUSCEPTIBILITY TO OXYGEN POISONING
Authors: Wood J. D.
Published: April 2011

Male and female rats of the Wistar strain were exposed to oxygen at high pressure (OHP) once per week for 3 weeks. Based on the incidence and severity of the convulsions observed, animals were selected which were considered the most susceptible and the most resistant to oxygen poisoning. The animals were mated and the offspring exposed to OHP. The rats from susceptible parents were more than normally susceptible to oxygen poisoning as gauged by time until onset of convulsions, incidence and severity of convulsions, and mortality. The animals from resistant parents were no more tolerant of OHP than were the randomly selected rats of the parent generation. Similar results were observed with a third generation of rats obtained by mating second generation susceptible and resistant animals respectively.
INTERACTING EFFECTS OF THYROID ACTIVITY AND DIETARY LEVEL OF VITAMIN A ON ERYTHROCYTE FRAGILITY IN THE CHICKEN
Authors: March B. E. , Coates Viona , Biely Jacob
Published: April 2011

The level of dietary vitamin A is shown to affect the osmotic stability of chick erythrocytes in hypotonic solutions. In chicks fed an excess of vitamin A, induced hyperthyroidism shifts the osmotic fragility curves, which indicates that an increase in the proportion of more stable cells has occurred. When the level of dietary vitamin A is normal, induced hyperthyroidism does not appreciably alter the osmotic fragility curve. It is concluded that the increased fragility of erythrocytes from chicks fed an excess of vitamin A may be an indirect effect of suppression of thyroid activity with a consequent increase in the proportion of older, more fragile cells in the blood.
SIMULATION OF SINUS NODE ACTIVITY BY AN ELECTRONIC RELAXATION OSCILLATOR
Authors: Roberge F. A. , Nadeau R. A.
Published: April 2011

After the sinus node was destroyed, its rhythmic activity was simulated by an electronic relaxation oscillator coupled to the beating heart. The output of the oscillator was used to stimulate the right atrium, and the ventricular response was returned to the input of the relaxation oscillator. By manually varying the frequency of this artificial pacemaker it was possible to produce changes in the rate of the atrio–ventricular (A–V) node similar to those obtained by perfusion of the intact sinus node with chronotropic agents. Particular attention was paid to the transitions from "oscillator" rhythm to A–V nodal rhythm, and vice versa. The results provide support for the following hypotheses relative to the intact heart: (i) some form of sinus node activity persists during A–V nodal rhythm, and (ii) the principal pacemakers of the heart, the sinus and A–V nodes, behave as a system of coupled relaxation oscillators.
AUTORADIOGRAPHY AND DRUG LOCALIZATION
Authors: Berlinguet L. , Bégin N. , Nicole L. , Ho-Van-Hap A. , Singh P.
Published: April 2011

Autoradiography was used to follow the distribution of 1-aminocyclopentanecarboxylic acid (ACPC), its analogue 1-amino-2-methylcyelopentanecarboxylic acid, tryptamine, and a barbituric acid analogue of phenylalanine. Mice were injected with 14C-labelled compounds, and sagittal sections were exposed for autoradiography. ACPC was localized in the pancreas and also in Walker tumors. Similarly, the methyl analogue accumulated in the pancreas but was located also in the kidney. There was a high content in an Ehrlich ascites tumor. The barbiturate was found mainly in the intestine and gallbladder. Tryptamine was rapidly metabolized and excreted through the kidney. These findings add much to the information obtained by the classical techniques of biochemistry.
ADAPTATION TO SUCROSE LOADING IN THE RAT
Authors: Fiorica Vincent , Iampietro P. F. , Moses Russell
Published: April 2011

Four groups of unanesthetized rats were infused with standardized volumes of 1.46 M (50% w/v) sucrose solutions through chronically indwelling arterial catheters. The excretion of water and solutes was measured during the following 6 hours. Five days later, after the animals had returned to their pre-loading weights, each group was infused again with the same load given initially. After the second loading, a pattern of excretion of water and solutes was observed which was different from that elicited by the first loading. The adaptations manifested after a second loading were characterized principally by (a) a smaller total volume excretion of urine (milliliters per 100 g body weight), (b) the excretion of a smaller fraction of the infused load, (c) an earlier inhibition of the initial diuresis, and (d) the production of a more concentrated urine. It is suggested that the initial loading conditions generate a physiological adaptation which promotes the water conservation mechanisms of the animal. This may involve a greater sensitivity of the adapted animal to antidiuretic hormone. It was further observed that the characteristics of the adaptations generated by intra-arterial infusion are qualitatively different from those produced by intraperitoneal infusion. This suggests that the ability of hypertonic solutions to evoke adaptive responses is dependent on the route through which such solutions are given.
AN ATTEMPT TO REPRODUCE EXPERIMENTALLY THE PATTERN OF SALT AND WATER DISTRIBUTION OF AGE IN THE YOUNG NEUROHYPOPHYSECTOMIZED ADRENALECTOMIZED RAT
Authors: Friedman Sydney M. , Gustafson Brigid , Hamilton Dorothy , Friedman Constance L.
Published: April 2011

Previous studies of the interaction of aldosterone, vasopressin, and corticosterone in the neurohypophysectomized adrenalectomized rat suggested that the salt and water distribution pattern in the muscles of the aged rat and that observed in simple aldosterone dominance were similar. This was tested by maintaining young neurohypophysectomized adrenalectomized rats with aldosterone alone for 3 months and comparing the resulting pattern with that of old rats, 27 months of age. Changes identical with those which occur spontaneously in the aged muscle, although of lesser degree, were reproduced in the young animals. Thus, total muscle sodium increased in association with a corresponding loss of potassium and a shift of water from cells to environment. As in the old animals, an increase in total muscle water was observed.
STIMULATION OF ADRENAL ACTIVITY BY THE ADMINISTRATION OF CORTICOSTERONE TO RATS CHRONICALLY TREATED WITH AMPHENONE OR METHAPYRAPONE
Authors: Pollock John J. , LaBella Frank S. , Krass Melvin E.
Published: April 2011

Administration of amphenone or methapyrapone as 0.3% of the diet to 28-day-old female rats for 29–32 days resulted in a decrease in body weight gain, a decrease in plasma steroid concentration, and an increase in adrenal weight. Thin-layer chromatography indicated the presence of corticosterone in the plasma extracts of untreated but not of amphenone- or methapyrapone-treated rats. However, two unknown fluorescent substances detected in the plasma extracts of treated but not untreated rats may represent biologically inactive glucocorticoid precursors. Deoxycorticosterone was detected in the plasma of rats treated with methapyrapone but not of untreated rats or those treated with amphenone. Intravenous administration of corticosterone, in amounts as little as 0.001 μg, to rats in which normal adrenal steroid synthesis was inhibited by amphenone or methapyrapone resulted in an increased release of ACTH, as indicated by both a depletion in adrenal ascorbic acid and an increase in fluorescent plasma steroids. ACTH release in response to increasing doses of corticosterone followed a bell-shaped curve when plotted. The adrenal-stimulating effect of small amounts of corticoid in the drug-treated rats was unaltered by interruption of the hypothalamicohypophyseal pathways by means of median eminence lesions placed 2 days previously. These findings indicate that low levels of circulating glucocorticoids stimulate directly the cells of the anterior pituitary to secrete ACTH.
BLOOD PLATELET FLUCTUATION CONSECUTIVE TO TRAUMA AND SURGICAL INTERVENTION IN THE RAT, A POSSIBLE STRESS EFFECT
Authors: Latour J. G. , Renaud S.
Published: April 2011

The typical blood platelet fluctuation repeatedly observed in man following surgical interventions and characterized by thrombocytopenia during the first 2 days and thrombocytosis after 5 to 8 days, has been reproduced in rats subjected to certain procedures, provided these were accompanied by severe tissue damage. An E. coli endotoxin injected intravenously or intraperitoneally induced a similar fluctuation and markedly potentiated the effects of the tissue damage on the blood platelets. This variation in the platelet count could be a stress effect, since it was completely reproduced by forced immobilization in the absence of any gross tissue damage. Ether anesthesia seems to reduce the magnitude of this stress-induced platelet fluctuation.
ROLE OF THE PITUITARY–ADRENOCORTICAL SYSTEM IN THE STRESS-INDUCED BLOOD PLATELET FLUCTUATION
Authors: Renaud S. , Latour J. G.
Published: April 2011

The blood platelet fluctuation observed after surgical interventions and reproduced here in the rat is apparently induced, partly or totally, by the reactions of the pituitary–adrenocortical axis to stress. The stress-induced platelet fluctuation could be the result of a certain adrenal insufficiency, since it can be elicited by simple adrenalectomy and completely prevented in immobilized but otherwise normal rats by hydrocortisone administered solely at the time of the immobilization. The thrombocytosis which occurs from 5 to 8 days after the stress appears to be dependent on the posterior pituitary hormones, since in hypophysectomized rats it could be reproduced only when posterior lobe or whole pituitary extracts were injected or when the posterior lobe had reorganized 26 days after the hypophysectomy. The potassium and sodium concentrations in serum did not seem to exert any influence on the blood platelet level under our conditions.
EFFECT OF COLD EXPOSURE ON SERUM LIPIDS AND LIPOPROTEINS IN THE RAT
Authors: Radomski M. W.
Published: April 2011

The effect of cold exposure for 1–52 days on the concentration and composition of the serum lipids and lipoproteins in male Wistar rats was studied. Serum lipoproteins were separated by preparative ultracentrifugation into three density classes, very low density (d < 1.006), low-density (d, 1.006–1.070), and high-density (d, 1.070–1.218). On the first day of cold exposure, total serum lipids were reduced by 20–25%, this decrease occurring mainly in the triglyceride fraction. Although the low-density and high-density lipoproteins were not affected by cold exposure, the concentration of the very low density lipoproteins fell markedly to 70–75% below normal levels. These alterations in the pattern of serum lipids and lipoproteins persisted throughout the cold-exposure period. Sex or prior feeding of a high-fat, high-carbohydrate, or high-protein diet did not modify these cold-induced changes. The response of the very low density lipoproteins to cold was immediate and rapid, the rate and degree of change being greatest in the first 4 hours of exposure. Conversely, the recovery of the very low density fraction to normal after removal of the rats from the cold was slow and depended upon the period of prior exposure. Animals exposed to 4 °C for 4 days required 3 days at 22 °C for the very low density lipoproteins to return to normal, and the recovery period was twice as long for cold-acclimatized (4 weeks) animals. The role of the triglyceride-rich very low density lipoproteins as a readily available energy source in the animals is discussed in the light of these results.
STUDIES OF THE CARBON DIOXIDE AND OXYGEN TENSIONS OF URINE DURING APPLICATION OF THE STOP-FLOW TECHNIQUE
Authors: Zborowski Danuta T. , Koch B. , Bates D. V. , Dossetor J. B.
Published: April 2011

Studies by the stop–flow technique were carried out in dogs in which diuresis had been induced with water, with and without the addition of bicarbonate. Urine samples from the collecting duct had greater maximal CO2 tension than was recorded simultaneously in arterial blood, and this peak occurred during infusion of carbonic anhydrase as well as during its inhibition by acetazolamide. With the former procedure, curves of CO2 tension were almost identical with those in standard control experiments. After administration of acetazolamide the values were greater, even when CO2 tension in arterial blood was > 60 mm Hg; otherwise, the curves were of similar shape. Lowest values for O2 tension in urine were recorded from the collecting duct region, and they persisted when urine flow was increased by the administration of acetazolamide or when the dog breathed 100% oxygen. The curves were of similar shape but values were slightly greater during oxygen breathing. The results obtained reflect the operation of hemodynamic mechanisms in the renal medulla, during application of the stop–flow technique.
CHOLINOLYTICS IN THE TREATMENT OF ANTICHOLINESTERASE POISONING: IV. THE EFFECTIVENESS OF FIVE BINARY COMBINATIONS OF CHOLINOLYTICS WITH OXIMES IN THE TREATMENT OF ORGANOPHOSPHORUS POISONING
Authors: Coleman I. W. , Little P. E. , Patton G. E. , Bannard R. A. B.
Published: April 2011

The selection, for use in combatting organophosphorus poisoning, of five binary cholinolytic drug combinations from previously screened compounds is described. Their effectiveness was determined in mouse, rat, guinea pig, hamster, and rabbit against TEPP, DFP, Paraoxon, sarin, tabun, O,O-diethyl S-2-diethyl-aminoethyl phosphorothiolate (DSDP), and cyclohexyl methylphosphonofluoridate (CMPF) in treatments in which the oximes P2S and TMB4 were used both singly and together. The effectiveness of each cholinolytic combination was compared with that of atropine sulfate on the basis of nine quantitative tests and one qualitative test.The following combinations had highest and almost equal effectiveness: G3063, a Caramiphen hydrochloride (Parpanit®) analogue, with triflupromazine; and Win 5779-6, a benzilate type ester, with triflupromazine. The combinations of Win 5779-6 with Parpanit®, atropine methylbromide with Parpanit®, and G3063 with G5130, another Parpanit® analogue, were second in activity and almost equal in potency. Atropine sulfate was the least effective. The most effective oximes were TMB4, and a lower dose mixture of P2S plus TMB4, which were found almost equal in potency but superior in effectiveness to P2S alone.
THE EFFECTS OF PREPUBERTAL OVARIECTOMY ON CONNECTIVE TISSUE GENERATION
Authors: Gardner D. G.
Published: April 2011

Polyvinyl sponges were implanted subcutaneously in 84-day-old female rats and in prepubertally ovariectomized rats of the same age. Animals from both groups were killed 72 ± 1 hours later. The mean hexosamine concentrations in sponge tissue were, in the intact animals and ovariectomized rats respectively, 340 ± 28 and 258 ± 19 μg hexosamine per 100 mg dry lipid-free tissue. The confidence intervals were derived from the Student's t test (5%). Prepubertal ovariectomy decreases the hexosamine concentration of the sponge tissue during the early stages of connective tissue generation in young adult rats and may have a similar effect on serum hexosamine. The mean hydroxyproline concentrations in the sponge tissue of the remaining animals, which were killed 10 days after implantation, were 1027 ± 77 and 777 ± 130 μg hydroxyproline per 100 mg dry lipid-free tissue for the ovariectomized and intact animals respectively (5% confidence interval). Prepubertal ovariectomy increases the rate of connective tissue generation in young adult rats. The ovariectomized rats were heavier at death than the intact animals and no apparent histologic differences were noted in the sponge tissue recovered from the two groups.
ARTIFICIAL NATURE AND SITE OF THE SYSTOLIC PRESSURE DROP DURING INOTROPIC STIMULATION OF THE NORMAL VENTRICLE
Authors: Dieudonné Jean-Marie
Published: April 2011

The effect of stellate stimulation on the exposed heart of the normal dog was studied with regard to the type of pressure contour changes recorded in the left ventricular main chamber. The evidence pointed toward a correlation between the presence or absence of systolic upshoot on the pressure contour and, respectively, the presence or absence of systolic obstruction of the tip of the recording catheter. The upshoot is interpreted as the accidental equivalent of subendocardial pressure, the reliability of which is, furthermore, open to question.
HEMODIALYSIS OF THE RAT
Authors: Robinson Sumner M. , Hurwitz David A. , Louis-Ferdinand Robert , Blatt William F.
Published: April 2011

A technique is described for hemodialysis of either anesthetized or non-restrained rats. In the apparatus the dialysis plates of an autoanalyzer system are used with only minor modification. The efficiency of this method has been evaluated with regard to the clearance of saccharides, both in vitro and in vivo, as well as the extraction of nitrogenous low molecular weight moieties from circulating blood. Approximately 50% of the dialyzable material was obtained in a 1-hour dialysis. Further fractionation of the dialyzate was accomplished by gel filtration (Sephadex G-25).
ON THE ACTION OF PROSTAGLANDIN E1AND PROSTAGLANDINS FROM BRAIN ON THE ISOLATED RAT STOMACH
Authors: Coceani F. , Wolfe L. S.
Published: April 2011

Prostaglandins are a group of structurally related dihydroxyketo- and trihydroxy-C20unsaturated carboxylic acids which cause contraction of intestinal smooth muscle at concentrations down to 1 × 10−10 g/ml. Crystalline prostaglandin E1and a purified preparation of ox brain prostaglandins (mainly F2α) initiated contraction of the isolated rat stomach fundus preparation by a direct action on the muscle which was strongly antagonized by adrenalin and noradrenalin. Drugs that inhibited sympathetic fibers or receptors potentiated the action of prostaglandins, whereas drugs that stimulated sympathetic receptors were inhibitory. Prostaglandin action was greatly diminished by lowering the temperature from 37 °C to 24 °C. The presence of oxygen was absolutely necessary for initiation of prostaglandin contraction but not for acetylcholine contraction. Prostaglandins were taken up by the tissue or produced a persistent change when added under anoxic conditions, but were unable to act unless oxygen was present. Metabolic inhibitors such as cyanide, azide, and carbon monoxide reversibly inhibited prostaglandin action to a greater extent than that of acetylcholine. A tonic rebound contraction occurred after removal of these inhibitors. Ascorbic acid and reduced (but not oxidized) glutathione reversibly enhanced prostaglandin action. Increased external potassium progressively increased the sensitivity of the muscle to prostaglandins. A hypothesis is proposed in which prostaglandins in association with an oxygen-requiring metabolic reaction initiate contraction by the release of bound calcium or the facilitation of calcium influx.
THERMAL PANTING AND THE INITIATION OF RESPIRATORY ALKALOSIS
Authors: Higgins E. Arnold , Iampietro P. F.
Published: April 2011

Forty-five dogs were exposed to nine different environmental conditions (five dogs per condition) consisting of three ambient temperatures (100 °F, 110 °F, and 120 °F) and relative humidities (30%, 60%, and 90%). After an initial control period of 30 minutes (ambient 21–24 °C) the animals were exposed to one of the experimental conditions for [Formula: see text] hours or until rectal temperature reached 42.0 °C. Under combined conditions of high temperature and humidity the non-biothermally involved consequences of panting became evidenced by an increase in blood pH, a decrease in blood CO2 (as a result of the thermally forced hyperventilation), and an increase in blood O2. The more severe the heat load (combined temperature and humidity) the greater was the rate of elevation of rectal temperature over control levels. It was evident that both relative humidity and ambient temperature were drives for increasing respiratory rate. It was also evident that increased humidity as well as increased temperature facilitated the rate of change of rectal temperature, blood pH, and blood CO2 and O2 concentrations. It appears possible that only under heat loads in which rectal temperature can be maintained at control levels by panting can the shift in acid–base balance be avoided.
THE ROLE OF ARTERIOVENOUS ANASTOMOSES IN COLD-INDUCED VASODILATION, REWARMING, AND REACTIVE HYPEREMIA AS DETERMINED BY24Na CLEARANCE
Authors: Edwards Merrill A.
Published: April 2011

The rate of removal of24Na from a deposit in the rabbit's foot was used to determine the degree of involvement of arteriovenous anastomoses in the blood flow of cold-induced vasodilation, in the rewarming following intense vasoconstriction, and in reactive hyperemia. The results indicate that in the first two cases the total flow is through the arteriovenous anastomoses. In reactive hyperemia an initial flow which is partly capillary and partly through the anastomoses gives way to a flow which is entirely through the anastomoses.
HOMOVANILLIC ACID AND DIHYDROXYPHENYLACETIC ACID IN THE STRIATUM OF MONKEYS WITH BRAIN LESIONS
Authors: Sharman D. F. , Poirier L. J. , Murphy G. F. , Sourkes T. L.
Published: April 2011

Lesions were placed in the left ventromedial tegmental area of the brains of nine monkeys (Macaca mulatto). After 1–4 months, the brains were removed, and the striatum was dissected and prepared for chemical analysis. In seven animals in which the lesion was strictly unilateral, the striatal dopamine was very much reduced below the level found on the intact side of the brain. In the two monkeys in which the lesion impinged on the right side of the brain, the concentration of dopamine was reduced on both sides. Homovanillic acid and 3,4-dihydroxyphenylacetic acid, metabolic derivatives of dopamine, were measured in the left and right striata of four and five monkeys respectively. Both compounds were present at subnormal concentrations on the side of the lesion. The concentration of homovanillic acid did not fall to as great an extent as did that of dopamine. These results are discussed in relation to data reported by others in regard to (a) animals treated with tranquilizing drugs, and (b) brains of patients who died with Parkinson's disease.
INHIBITORY EFFECT OF CERTAIN AMINO ACIDS ON RENAL TUBULAR ABSORPTION OF PHOSPHATE
Authors: Michael Alfred F. , Drummond Keith N.
Published: April 2011

Infusion of certain neutral L-amino acids (alanine, glycine, valine, and tryptophan) into dogs resulted in an inhibition of the renal tubular reabsorption of phosphate and increased phosphate excretion. This was seen in both the parathyroidectomized animal and under conditions of exogenous parathormone infusion, indicating that the phosphaturia induced by amino acids is independent of parathyroid hormone action. This effect was stereospecific and did not occur with D-alanine; no effect was observed after infusion of the basic amino acids L-arginine and L-lysine.
KINETICS OF URIC ACID TRANSPORT AND ITS PRODUCTION IN RAT SMALL INTESTINE
Authors: Oh Jung H. , Dossetor John B. , Beck Ivan T.
Published: April 2011

Segments of the middle third of rat small intestine were incubated at 30 °C for 1 hour in the model of Crane and Wilson. When comparison was made between the uric acid contained in unincubated segments and that in both incubated segments and their incubation media, the latter was found to exceed the former nearly fivefold. This indicates that the small intestine is a major site of uric acid production in the body. The rate of uric acid-14C transport across the intestinal wall was studied with the same model, and found to be linearly proportional to its initial concentration gradient in both directions. This rate was not altered by hypoxanthine or uricosuric agents, which have been shown to influence uric acid transport in other systems. It is concluded, therefore, that uric acid transport across the wall of the small intestine is by passive diffusion.
EFFECTS OF COMPOUND 48/80, CHLORPROMAZINE, DEXTRAN, AND RESERPINE IN RABBITS FED A 1% CHOLESTEROL DIET
Authors: Lafrance Louise , LeBlanc Jacques
Published: April 2011

The effects of drugs such as compound 48/80, chlorpromazine, dextran, and reserpine which influence the release and metabolism of biogenic amines, have been studied in rabbits fed a 1% cholesterol diet for 5 and 9 weeks. It was found that chlorpromazine, dextran, reserpine, and reserpine + compound 48/80 decreased the serum total cholesterol and lipid levels during the first 3 weeks of the 9-week experiment. This hypolipemic effect was no longer evident in the latter part of the experiment. Chlorpromazine and dextran reduced the serum total cholesterol, total lipid, and total protein levels after the 4th week of the 5-week experiment. The aortic fatty deposits of the treated groups were less abundant after 5 weeks of experiment but not significantly so after 9 weeks. Compound 48/80 had no decreasing effect on serum lipemia or aortic deposits in either experiment. The effects obtained with dextran and reserpine were not due to variations in exogenous cholesterol intake or intestinal absorption of the ingested cholesterol. However a smaller intake of exogenous cholesterol may partly account for the effects observed with chlorpromazine, and a reduced intestinal absorption for the effects observed with reserpine + compound 48/80.
THE ENHANCEMENT OF PENETRATION OF AN ORGANOPHOSPHORUS ANTICHOLINESTERASE THROUGH GUINEA PIG SKIN BY DIMETHYL SULFOXIDE
Authors: McDermot H. L. , Finkbeiner A. J. , Wills W. J. , Heggie R. M.
Published: April 2011

The penetration of both intact and stripped guinea pig skin by soman was enchanced by dimethyl sulfoxide (DMSO), showing that DMSO does not act solely by increasing the penetration of stratum corneum. At high concentrations of DMSO the increase in penetration was masked by a decrease in the spreading of the mixtures on skin, but when this decrease was taken into consideration the penetration rate of soman increased with increasing DMSO concentrations up to at least 90%.
VITAMIN C METABOLISM IN RATS FED A LOW-PROTEIN DIET AND EXPOSED TO COLD
Authors: Beaton John R.
Published: April 2011

Male rats of the Wistar strain were fed a low-protein (5% casein) or a control (20% casein) diet at environmental temperatures of 24 and 5 °C. Measurements were made of daily food intake, body weight, and urinary excretion of vitamin C, and of ascorbic acid synthesis and destruction by liver homogenates in vitro. From the results of several experiments it was observed that (a) rats fed the low-protein diet excreted decreased amounts of vitamin C which were increased by exposure to cold; (b) ascorbic acid synthesis was decreased in rats fed the low-protein diet; (c) ascorbic acid synthesis was increased by cold exposure in rats fed the low-protein diet ad libitum but not when pair-fed; (d) destruction of ascorbic acid was not affected markedly by either dietary protein level or by cold exposure; (e) subcutaneous injection of ascorbic acid (5 mg/100 g body weight) significantly increased body weight gain in rats fed the low-protein diet at 24 and 5 °C and in rats fed the control diet at 5 °C. These observations indicate an inadequate synthesis of ascorbic acid in rats fed a low-protein diet.
CHANGES IN ATRIAL RATE DURING AND FOLLOWING VENTRICULAR ARREST FROM ACETYLCHOLINE INJECTIONS INTO THE ATRIOVENTRICULAR NODE ARTERY OF THE DOG
Authors: Nadeau R. A. , Amir-Jahed A. K. , Roberge F. A.
Published: April 2011

During ventricular arrest obtained by injections of acetylcholine into the canine atrioventricular node artery, atrial acceleration of variable magnitude was observed. Upon return of ventricular activity a marked slowing of atrial rate was usually noted, followed by a gradual return to the initial sinus rhythm. Similar phenomena were observed with a preparation in which the sinus node was destroyed and its activity simulated by an electronic relaxation oscillator coupled to the heart in a closed-loop fashion. Model experiments with two interacting relaxation oscillators suggested that atrial acceleration during ventricular arrest, and atrial slowing during the return of ventricular activity, were governed by some sort of feedback from ventricles to sinus node.
ANATOMICAL AND PHYSIOLOGICAL CHANGES IN LAMBS DURING BACTERIAL INHIBITION
Authors: Karr M. R. , Little C. O. , Mitchell Jr. G. E. , Glimp H. A. , Woolfolk P. G.
Published: April 2011

Rumen cannulas were installed in four sets of twin lambs. Increasing levels (with time) of a mixture of antibiotics and Sulfathalidine were administered via the rumen cannula twice daily to prevent the development of a bacterial population in the rumen. This procedure was successful for 12 weeks. Small concentrations of volatile fatty acids were observed after this time. Neither papillae nor the muscular part of the rumen developed normally in the treated lambs where rumen volatile fatty acids were absent. Structural development of the reticulum and omasum was also greatly reduced by the antibiotic–Sulfathalidine treatments. In vitro butyrate uptake by tissues taken from the rumen, reticulum, and omasum was similar and was low for both the control and treated lambs. Poor muscular development of the rumen wall was observed in the treated lambs; and large quantities of ingesta were present, suggesting a reduced rate of passage. This was associated with diminished feed intake and inability of the lambs to maintain body weight after weaning. The apparent digestion of dietary dry matter, crude protein, starch, and cellulose was reduced by treatment.
OUABAIN-INDUGED CHANGES IN THE CONTRACTILE AND ELECTRICAL ACTIVITY, POTASSIUM CONTENT, AND RESPONSE TO DRUGS, OF SMOOTH MUSCLE CELLS
Authors: Matthews E. K. , Sutter M. C.
Published: April 2011

Contractile activity, electrical activity, and tissue potassium content were studied in vitro in the guinea pig taenia coli and rabbit anterior mesenteric vein, before, during, and after exposure to ouabain 10−5M. Ouabain produced a contraction, followed by relaxation, in both preparations; later there was a larger, more prolonged contraction of the vein. Action potential frequency was first increased, then decreased, and finally abolished by ouabain in both preparations. Tissue potassium content was also decreased and membrane potentials were progressively reduced. Ouabain blocked the contractile effect of excitant drugs in the taenia but not in the vein. Yet in both preparations drug-induced electrical changes were completely abolished by ouabain. These results support the conclusion that stimulant drugs are able to contract the anterior mesenteric vein both via action potentials and by a mechanism relatively independent of the electrical events at the cell membrane. They also suggest that smooth muscles vary in regard to the necessity of action potentials as a link in drug-induced contraction.