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Biomedical subjects

L Singer

Publications and source records attributed to L Singer.

At least 109 records · Page 6Linked to original sources
PubMed1981

[A study of thyroid function in patients with psychoaffective disease (author's transl)].

The purpose of the present study was to investigate dysfunctions in thyroid gland secretion and regulation among patients with manic-depressive psychosis. Plasma levels of thyroxine (T4), triiodothyronine (T3) and thyroid stimulating hormone (TSH) were measured by radioimmune assays, and TSH responsiveness (delta TSH) to synthetic TSH-releasing hormone (TRH) 250 microgram IV was determined in 20 untreated patients, 19 patients under neuroleptics and 19 patients under antidepressants. Untreated patients were compared with 15 age - and sex-matched controls. They were found to have significantly lower plasma T3 levels than controls (121.0 +/- 6.0 ng/dl as against 144.5 +/- 3.3 ng/dl; p less than 0.01) and blunted TSH response to TRH (delta TSH 4.1 +/- 0.6 instead of 12.6 +/- 2.1). Other thyroid function parameters were unchanged. Under neuroleptic treatment T3 levels tended to increase and delta TSH returned to normal. Manic-depressive psychosis is characterized by hypothalamic-pituitary dysfunction. Thyroid secretion is normal, and the decrease in T3 is probably due to impaired peripheral T4 to T3 conversion.

Bipolar Disorder↗
PubMed1981

Effect of lactation and calcium deficiency, and of fluoride intake, on bone turnover in rats: isotopic measurements of bone resorption and formation.

The rates of bone formation and resorption were investigated, using isotopic measurements, in calcium-deficient lactating rats and compared to those of calcium-sufficient non-lactating animals. Bone formation was measured by 3H-proline uptake and 3H-hydroxyproline formation, and resorption was measured by the loss of previously incorporated 3H-tetracycline, in whole humerus. The effect of 50 ppm fluoride in the drinking water on both parameters was also examined. The stress of lactation and calcium deficiency significantly increased the rates of bone resorption and formation, but the increase in resorption was greater than in formation which resulted in a net decrease in bone mineral and matrix. Fluoride had no effect on various parameters measured.

Animals↗
PubMed1980

Metabolic aspects of bone resorption in calcium-deficient lactating rats.

Lactating female rats were fed diets containing 1.0, 0.1, or 0.04% Ca for 21 days. Fat-free dry weight, ash weight, calcium and phosphorus content of the humerus, plasma calcium levels, and bone acid and alkaline phosphatase activities were compared to those of nonlactating rats fed the same diets. Bone, plasma, and urinary cAMP levels were also studied. Dietary calcium deficiency and/or lactation caused significant loss of bone mass from experimental animals. Urinary cAMP levels reflecting increased parathyroid activity were elevated by the stresses of lactation and calcium deficiency over those of control animals. Plasma and bone levels of cAMP were not different. Bone alkaline and acid phosphatase activities were affected only by the most extreme stress. The results demonstrated that the calcium-deficient lactating rat is an excellent model for bone resorption studies.

Acid Phosphatase↗
PubMed1980

Estimated fluoride intake of 6-month-old infants in four dietary regions of the United States.

Eleven composite food groups comprising the infant "market basket" food collections for 1977 or 1978 from each of four dietary regions of the United States were analyzed for their fluoride content. Based upon the determined fluoride content of each composite and Food and Drug Administration estimates of food consumption the daily fluoride intake of an average 6-month-old infant residing in each of the dietary regions was calculated. The daily fluoride intake varied from 0.207 mg/day in Grand Rapids, Mich. (north central dietary region) to 0.541 mg/day in Orlando, Fla. (south dietary region). Flouride intakes of 0.272 and 0.354 mg/day were calculated for Philadelphia, Pa. (northeast dietary region) and Los Angeles, Calif. (west dietary region), respectively. The fluoride content of the water supplies ranged from 0.37 ppm (Los Angeles) to 1.04 ppm (Grand Rapids). Drinking water, dairy products and substitutes (other than milk), and grain and cereal products contributed 44 to 80% of the daily fluoride intake. In three of the four dietary regions the daily fluoride intake was less than the optimum level of 0.05 mg/kg body weight.

Dairy Products↗
PubMed1980

Fluoride intakes of young male adults in the United States.

The total daily fluoride intake for young male adults living in four geographical areas of the United States has been estimated by the analysis of "market basket collections" obtained in 1975 and 1977. The fluoride intake in 1975 vaired from 0.912 mg/day in an unfluoridated city (Kansas City, Mo.) to 1.720 mg/day in a fluoridated city (Atlanta, Ga.). The 1977 collection from San Francisco, Calif. contained more fluoride (1.636 mg/day) than the 1975 collection (1.213 mg/day). The level of intake found in this study is less than that reported by San Filippo and Battistone (Clin. Chem. Acta 31: 453, 1971) who analyzed similar collections from Baltimore, Md. in 1967 to 1968 (2.09 to 2.34 mg/day). This study, as well as the earlier one, indicates that relatively low levels of fluoride are being consumed in the United States by the young adult male 16 to 19 years of age.

Adolescent↗
PubMed1980

Effects of indomethacin and methylprednisolone on renal elimination of lithium in the rat.

Wistar rats were given lithium chloride (16.7 mg/kg i.p.) after treatment with indomethacin (2.5 mg/kg/day for 5 days), with methylprednisolone (3 mg/kg/day for 5 days), or with their solvents. Lithium and creatinine clearance and urinary elimination of sodium and phosphate were determined. Indomethacin increases while methylprednisolone decreased the fractional tubular reabsorption of lithium. The quantity of lithium eliminated in the urine is correlated with the urinary elimination of sodium and phosphate. The effects of the anti-inflammatory drugs on renal elimination of lithium seemed linked to their effects on proximal sodium reabsorption.

Animals↗
PubMed1980

[Lithium elimination by the isolated perfused rat kidney (author's transl)].

The pharmacokinetics of lithium, a drug with a narrow therapeutic index, depends on the renal elimination of the metal. An open circuit, constant flow isolated rat kidney preparation perfused with gelatinized (Haemaccel) Krebs-solution, was used to study the urinary elimination of lithium relative to sodium. A series of 88 kidney preparations perfused with a solution containing 0.47 mmol/l lithium was compared to another of 52 kidney preparations perfused without lithium. Lithium reduced the tubular reabsorption of sodium but did not modify the elimination of potassium. There is a strong correlation between the tubular reabsorption of lithium and of sodium. The correlation between tubular reabsorption of lithium and filtered load demonstrates the existence of a glomerulo-tubular balance.

Animals↗