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Biomedical subjects

S Kaufman

Publications and source records attributed to S Kaufman.

At least 343 records · Page 19Linked to original sources
PubMed1981

Control of fluid intake in pregnant and lactating rats.

1. During 24 hr water deprivation, the pregnant and lactating rats lost more weight than the non-mated animals. The increase in haematocrit was considerably greater in the lactating animals although plasma osmolality increased to the same extent in both lactating and non-mated animals. 2. Following water deprivation, the water intake of the lactating rats was significantly less than that of the pregnant, post-lactating or non-mated animals when expressed as a percentage of the weight loss during dehydration. While the non-mated rats restored their plasma osmolality to the pre-deprivation value upon drinking, the lactating rats sustained a new decrease in osmolality despite the fact that their mean haematocrit was still elevated. 3. When the dehydrated animals were given isotonic saline to drink instead of water, both lactating and non-mated animals restored their body weight and haematocrit to pre-deprivation levels. 4. Lactating rats showed a reduced absolute and net fluid intake in response to I.V. hypertonic saline which could not be explained by more rapid renal clearance of the solute. 5. The pregnant and lactating rats drank less in response to s.c. isoprenaline than did the post-lactating and non-mated animals. 6. The spontaneous 3 hr fluid intake was significantly less during lactation. 7. It is suggested that during the hours of daylight, lactating rats are less responsive to dipsogenic stimuli arising from deficits in both their intracellular and extracellular fluid spaces.

Animals↗
PubMed1981

Daily water and electrolyte balance in chronically hyperprolactinaemic rats.

1. Chronic hyperprolactinaemia was induced in eight male rats by implantation of anterior pituitary glands from inbred female rats. The ten control rats underwent sham operations. 2. The spontaneous 24 hr water intake of hyperprolactinaemic rats was greater than that of the controls. Intake was increased only at night. 3. The increased water intake was independent of food intake and was not secondary to increased salt intake. 4. When prolactin secretion was inhibited with bromocriptine, there was a parallel fall in water intake and plasma prolactin levels in the experimental animals to the levels observed in the controls. 5. Urine volume was greater and urine osmolality lower in the hyperprolactinaemic rats than in the controls during both day and night. 6. In the evening, plasma osmolality was lower in the hyperprolactinaemic animals than in the controls. No such difference was observed in the morning. 7. Blood volume was greater in the hyperprolactinaemic rats than in the controls, but the haematocrits were the same. 8. These findings indicate prolactin may have a primary dipsogenic activity.

Animals↗
PubMed1981

Effect of stretching the superior vena cava on heart rate in rats.

The effect on the heart rate of stretching the superior vena cava 3-4 mm above its entrance to the right atrium was examined in rats anesthetized with chloralose. The superior vena cava was stretched 41 times in 16 rats. There was a mean increase of 24.1 +/- 1.9 (SE) beats/min. This response was abolished (6 rats) by sympathetic blockade (with propranolol hydrochloride and bretylium tosylate) and by bilateral vagosympathectomy (5 rats). Application of lidocaine to the cervical vagi also abolished the response in a reversible manner (4 rats). In five rats, histological examination of the superior vena cava revealed an abundance of nerves, which formed a net in the stretched region. Complex unencapsulated nerve endings similar to those demonstrated in the dog and cat were not found.

Animals↗
PubMed1981

Eosinophilia in uremia.

Peripheral and bone marrow eosinophils were determined in a group of patients on chronic hemodialysis and in predialysis uremics. Healthy subjects were taken as controls. Increased number of eosinophils in bone marrow were found in the predialysis uremic group and this finding was even more accentuated in the dialyzed patients. Marrow eosinophilia correlated linearly with serum creatinine levels in the predialysis group. The peripheral eosinophil count was normal in the uremic group and in part of the hemodialysis group. Marked and progressive peripheral eosinophilia was evident in a distinct subgroup of the dialysis patients. Marrow eosinophilia seems to be part of the uremic syndrome. The possible nature of the factor(s) involved in the derangement of eosinophil homeostasis is discussed.

Adolescent↗
PubMed1981

Severe ovarian hemorrhage in congenital afibrinogenemia.

This is a case report of a patient with congenital afibrinogenemia and massive intra-abdominal bleeding from a ruptured corpus luteum cyst. None of the previously reported 100 cases mentioned obstetrical or gynecological complications associated with this rare entity.

Adult↗
PubMed1981

Effect of uremic serum on E-rosette formation of normal lymphocytes modulated by levamisole.

The number of E-rosette forming cells of lymphocytes from healthy subjects was determined under various experimental conditions. Sera from 16 chronic hemodialysis patients were incubated with lymphocytes from 16 matched normal subjects. The effect of levamisole on this combination was studied. Uremic serum markedly inhibited E-rosette formation of normal lymphocytes. Pretreatment with levamisole completely prevented this effect, whereas levamisole treatment following incubation with uremic serum resulted in a partial correction of the E-rosette formation. The hypothesis best fitting these results is that a factor present in uremic serum blocks sheep red cell receptors on normal lymphocytes; levamisole, having a greater affinity for these receptors, prevents or partially corrects the effect of the blockade.

Humans↗
PubMed1980

Characterization of the dihydropterin reductase activity of pig liver methylenetetrahydrofolate reductase.

Pig liver methylenetetrahydrofolate reductase catalyzes the reduction of quinonoid dihydropterins in vitro. Either NADPH or methyltetrahydrofolate can serve as the electron donor. Methylenetetrahydrofolate reductase can also suppor phenylalanine hydroxylation in vitro by regeneration of the tetrahydropterin cofactor. These results lend support to the proposal that reduction of methylenetetrahydrofolate proceeds by tautomerization of the 5-iminium cation to form quinonoid 5-methyldihydrofolate, which is then reduced to methyltetrahydrofolate (Matthews, R. G., and Haywood, B. J. (1979) Biochemistry 18, 4845-4851). Under Vmax conditions, the turnover numbers for the NADPH-linked reductions of the quinonoid forms of 6,7-dimethyldihydropterin, dihydrobiopterin, and dihydrofolate are all about the same as that for the reduction of methylenetetrahydrofolate. The Km values for racemic mixtures of the same quinonoid acceptors are 40, 30, and 20 microM, respectively, while the Km for (6R,S)methylenetetrahydrofolate is 20 microM at pH 7.2 in phosphate buffer. The reduction of quinonoid dihydropterins is inhibited by adenosylmethionine and dihydropteroylhexaglutamate, which are known to modulate methylenetretrahydrofolate reductase activity.

Animals↗
PubMed1980

Relationship between the multiple forms of rat hepatic phenylalanine hydroxylase and degree of phosphorylation.

The two major forms of rat liver phenylalanine hydroxylase have been resolved by calcium phosphate chromatography and have been highly purified. These different forms of the enzyme contain dissimilar amounts of endogenous protein-bound phosphate. The hydroxylase activity of these forms, as assayed in the presence of tetrahydrobiopterin, can be differentially stimulated by treatment with Mg2+, ATP, cyclic AMP, and protein kinase, leading to the production of a chromatographically distinct species. In the presence of [gamma-32P]ATP, activation is accompanied by differential incorporation of 32P into the subunits (Mr = 50,000) of the two enzyme forms leading to a new form which contains 1 mol of phosphate/subunit. In addition, phosphorylation in vitro eliminates the electrophoretic heterogeneity displayed by the isolated forms. These data show that the multiple forms and electrophoretic heterogeneity of phenylalanine hydroxylase are correlated with the degree of phosphorylation and also provide further evidence for the regulation of this enzyme by phosphorylation and dephosphorylation.

Animals↗
PubMed1980

Early detection of doxorubicin cardiotoxicity by M-mode echocardiography.

The influence of increasing doses of doxorubicin on the heart was examined in 30 patients with solid tumors, M-mode echocardiography being used to evaluate left ventricular contractility. The function of the left ventricle remained normal in 26 subjects, whereas four patients had evidence of cardiotoxicity after cumulative doses of 220, 380, 420, and 450 mg/m2. Transient overt heart failure was noted in one subject only. Doxorubicin cardiotoxicity can be detected by M-mode echocardiography, a simple and non-invasive technique, prior to the appearance of overt congestive heart failure. Patients demonstrating left ventricular dysfunction are probably not candidates for receiving further therapy with anthracycline antibiotics. Limitation of M-mode echocardiography include a 28% incidence of inadequate studies in this group of patients, and a relative inaccuracy of the technique in evaluating patients with prior myocardial infarction.

Adolescent↗
PubMed1980

Congenital afibrinogenemia in 10 offspring of uncle-niece marriages.

Two unrelated large sibships, including 10 cases of congenital afibrinogenemia among 27 sibs, are reported. Both sibships were the product of uncle-niece marriages. They were not selected for any particular clinical manifestation and should provide some information on genetic fitness. Six of the patients died in childhood, two affected boys are adolescent and two affected patients are young women. Two of the four survivors had spontaneous ruptures of the spleen. Fitness in this very rare disease seems to be close to zero and the inheritance is autosomal recessive.

Adolescent↗
PubMed1980

Neopterin and biopterin levels in patients with atypical forms of phenylketonuria.

The pattern of unconjugated pterins in liver tissue and in urine from patients with atypical forms of phenylketonuria with hyperphenylalaninemia (HPA) has been investigated with a high performance liquid chromatographic technique. Two patients with defects in the biosynthesis of biopterin have been shown to have higher than normal levels of neopterin and lower than normal levels of biopterin. In contrast, a patient with HPA due to a deficiency of dihydropteridine reductase has the reverse urinary pattern, i.e., high biopterin, low neopterin. These results indicate that the ratio of neopterin to biopterin in urine can be of value in discriminating between HPA due to a deficiency of phenylalanine hydroxylase (classic PKU), HPA due to dihydropteridine reductase deficiency, and HPA due to a block in the biosynthesis of biopterin.

Amino Acid Metabolism, Inborn Errors↗
PubMed1980

The mechanism of drinking induced by parenteral hyperonocotic solutions in the pigeon and in the rat.

1. In pigeons, the I.V. injection of 0.3-1.3 ml. of 50% (w/w) solutions of either polyethylene glycol (mol.wt. 20,000) or dextran (mol.wt. 40,000) induced reliable, rapid dose-dependent drinking responses. The amount of water drunk in response to I.V. polyethylene glycol was greater than that in response to I.P. polyethylene glycol and twice that in response to I.V. dextran. I.V. polyethylene glycol induced a diuresis following the onset of drinking.2. The dipsogenic effect of I.P. polyethylene glycol solutions in the pigeon was depressed by I.V. isotonic NaCl solution 1 hr before offering water but was increased by simultaneous I.V. hyperoncotic polyethylene glycol solution.3. In contrast, in rats, the subcutaneous injection of 25% (w/w) polyethylene glycol (mol.wt. 20,000; 1.25-10.0 ml./kg body wt.) induced reliable drinking responses, while the same doses of polyethylene glycol, injected I.V., did not induce drinking consistently. The volume of water drunk by rats in response to subcutaneous polyethylene glycol was smaller per unit dose than that drunk by I.P. injected pigeons.4. The results suggest that receptors for drinking induced by extracellular dehydration in the pigeon could be situated in the extravascular interstitial section of the extracellular compartment.

Animals↗
PubMed1980

A comparison of the dipsogenic responses of male and female rats to a variety of stimuli.

Female rats subjected to 48 h of water deprivation drank more than similarly deprived males. There was no sexual difference in the dipsogenic responses to intracellular dehydration produced by intravenous hypertonic NaCl but females drank considerably more than males in response to the extracellular stimuli of hyperoncotic polyethylene glycol and angiotensin II. It is concluded that intact adult female rats are dipsogenically more responsive than adult male rats to stimuli acting through the pathways of extracellularly induced thirst but not to those arising from the intracellular fluid compartment.

Angiotensin II↗