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Biomedical subjects

L Singer

Publications and source records attributed to L Singer.

At least 55 records · Page 3Linked to original sources
PubMed1985

Promotion of bone dissolution by excessive fluoride in acidic buffer solution.

In order to quantitatively examine fluoride uptake by bone and the effect on its chemical and physical properties, rat bone was incubated in acidic buffer solutions (pH 5) with fluoride concentrations of 0-1000 ppm F. After 1 wk incubation, there was a substantial increase in the crystallinity of the bone mineral with increasing fluoride concentration in the solution. The calcium concentration in the solutions used for incubation decreased dramatically, with increased levels of fluoride in the solution, approaching a plateau. The phosphate concentration initially decreased, with increasing levels of fluoride in proportion to the decrease of calcium concentration, and then increased when the fluoride concentration of the solution was above 200-300 ppm. These phenomena, when considered with X-ray diffraction data, reflected the formation of CaF2. The increase of the phosphate concentration in the solution suggests that the presence of excessive fluoride in the acidic buffer solution may promote the dissolution of soluble bone apatites, in spite of the dissolution-preventive activity of fluoride.

Animals↗
PubMed1985

Dietary fluoride intake of 6-month and 2-year-old children in four dietary regions of the United States.

Based upon the analysis of 44 market basket food collections, the average daily dietary fluoride intakes of 6-mo-old and 2-yr-old children residing in cities with water fluoride levels of 0.05 to 1.04 ppm were determined. In cities with greater than 0.7 ppm fluoride in the drinking water, a 6-mo-old child (infant) and a 2-yr-old child (toddler) had mean dietary fluoride intakes of 0.418 mg/day (0.052 mg/kg body weight) and 0.621 mg/day (0.050 mg/kg body weight) respectively. The data indicate that the average dietary fluoride intake of infants and toddlers did not exceed 0.08 mg/kg, and in all but three cases was within or below the optimum range of 0.05-0.07 mg/kg. The ingestion of fluoride-containing dentifrice or milk formula diluted with fluoridated water may result in intake levels exceeding that associated with the development of dental fluorosis (0.1 mg F/kg body wt).

Child, Preschool↗
PubMed1985

Dietary fluoride intake of 15-19-year-old male adults residing in the United States.

The average daily dietary fluoride intakes of 15-to-19-year-old males were estimated from the analysis of 24 FDA "market basket" food collections made from 1975 to 1982. The data indicate that 15-to-19-year-old males residing in fluoridated (greater than 0.7 ppm) cities had an average daily dietary fluoride intake of 1.85 mg/day when the diet provided an estimated caloric intake of 11.72 megajoules (2800 calories). In non-fluoridated cities, with less than 0.3 ppm in the drinking water, the average dietary fluoride intake was 0.86 mg/day. The beverages and drinking water contributed an average of 75 +/- 2% of the daily dietary fluoride intake.

Adolescent↗
PubMed1979

Lack of cytogenetic effects in mice or mutations in Salmonella receiving sodium fluoride.

We have examined the possible effect of fluoride intake on chromosome damage. There was no evidence of increased frequency of chromosomal aberration in bone marrow or testis cells of mice with either 50 ppm fluoride intake over several generations or 100 ppm intake for 6 weeks compared to animals drinking distilled water. Fluoride was not found to be mutagenic in a widely used bacterial mutagenesis assay over a range of 0.1 to as high as 2000 microgram fluoride per plate.

Animals↗
PubMed1979

Lack of effect of fluoride on urinary cAMP excretion in rats.

The urinary excretion of cyclic 3'5'-adenosine monophosphate (cAMP) was measured in rats provided a low fluoride diet (less than 0.5 ppm) and drinking water containing either 0 or 25 ppm of fluoride. The pMole cAMP/microgram creatinine ratio decreased with age but was not influenced by fluoride intake.

Animals↗
PubMed1979

[Lithium and thyroid function. Significance of the TRH test in the diagnosis of lithium-induced thyroid dysfunction].

The treatment by lithium is known to involve certain endocrine complications. Those concerning the thyroid function, with risk of a frank hypothyroidy, are the most important. Aiming to appreciate the frequence and the intensivity of the endocrine effects of lithium, the thyroid parameters and the steady state of the hypothalamo-pituitary-thyroid axis were tested using the TRH test in 52 patients with maniaco-depressive psychosis with special attention to TSH, prolactin and growth hormone: 24 out of them were treated for 1 month to 6 years by lithium; the 28 others were considered as controls. The lithium treatment involves a decrease in the free thyroxine index (1.78 +/- 0.09 vs 2.16 +/- 0.09; p less than 0.01), an increase in the mean baseline TSH level (5.80 +/- 1.49 vs 2.70 +/- 0.24 microU/ml; p less than 0.05) and a noteworthy increase in the TSH responsiveness to TRH (22.7 +/- 2.14 vs 9.75 +/- 1.63 microU/ml; p less than 0.005). The TSH supranormal responses were neither correlated with the length of the treatment nor with the age of the patients. They appear as the consequence of a decrease in the thyroidal hormone secretion. The basal and stimulated prolactinemias remain comparable in the two groups of patients and no response of growth hormone occured after TRH. The TRH test must be considered as a useful complement for the surveillance of the patients treated with lithium because it permits to diagnose early the lithio-induced thyroid dysfunction.

Adolescent↗
PubMed1979

Concentrations of ionic, total, and bound fluoride in plasma.

We found no significant difference between the means for ionic, bound, and total fluoride concentrations in the plasma of male and female subjects of the same age, living in a community with fluoridated water. When results for the 264 fasting subjects were therefore combined according to age, they indicated that persons over 60 years of age have a significantly higher mean ionic (3.89 mumol/L) and total (6.58 mumol/L) fluoride concentration in plasma than do younger age groups. For younger age groups, means ranged from 2.74 to 3.05 mumol/L for ionic fluoride and from 4.74 to 5.58 mumol/L for total. The bound fluoride concentration was lower in individuals 21 to 30 years of age (1.89 mumol/L) than in older age groups (for whom means ranged from 2.42 to 2.68 mumol/L), but was not significantly different from that of individuals who were younger (2.21 mumol/L). A tendency for the mean ionic fluoride concentration to increase with age was noted, but the concentration was significantly higher than the preceding decade group only in those persons over 60 years of age.

Adolescent↗
PubMed1979

Total fluoride intake of infants.

The fluoride content of commercially prepared infant foods processed in fluoridated and nonfluoridated plants has been determined. The use of fluoridated water during processing has been shown to increase significantly the fluoride content of certain infant foods. The data obtained have been employed to calculate the minimum and maximum total daily fluoride intake for infants up to 6 months of age. The maximum total daily fluoride intake for infants up to 6 months of age is 0.127 mg of fluoride per kilogram of body weight. An infant consuming human milk or cow's milk and living in a community that does have fluoridated water has a substantially lower total daily fluoride intake.

Animals↗
PubMed1978

The effects of high and low fluoride diets on the frequencies of sister chromatid exchanges.

A recent report suggests that fluoride has mutagenic activity in mice. To examine the potential clastogenic effect of ingested fluoride, we examined the frequencies of baseline SCE and mitomycin C induced SCE as well as baseline chromsomal aberrations and cell-cycle kinetics in mice raised on high and low fluoride diets. The lack of significant differences in any of these parameters between the two groups of animals indicates that dietary fluoride is not clastogenic and supports the continued use of water fluoridation.

Animals↗
PubMed1978

Long-term follow-up of photocoagulated retinal breaks.

126 cases of retinal breaks treated in our department by photocoagulation during a period of 10 years (1963-1973) were selected for a close annual follow-up. Eliminated from the study were cases of macular holes, breaks which developed in an eye after retinal detachment surgery, and cases in which a close follow-up was impossible for various reasons. The study includes symptomatic retinal breaks in myopic, non-myopic, and aphakic eyes as well as asymptomatic holes which were found in the undetached fellow eye. Four eyes treated by photocoagulation (3.2%) developed a retinal detachment. The causes of failures and complications, such as retinal detachment, vitreous haemorrhage, and macular pucker, are discussed.

Adolescent↗