W. D. Armstrong

Tissue weights of the rat. I. Normal values determined by dissection and chemical methods.

Summary A combined dissection and chemical approach to the problem of determining tissue weights has been described. It allows the exact determination of total muscle mass and supportive tissue weight in a fraction of the time required by the complete dissection approach. It also provides estimates of the total marrow weight and the fresh weight of the connective tissue, which are difficult to obtain in any other manner.

DISTRIBUTION AND EXCRETION OF RADIOFLUORIDE IN THE HUMAN

Summary One mg fluoride labeled with radiofluoride was ingested by each of 2 adult humans. Observations of renal clearance of fluoride, chloride and creatinine were made. Fluoride clearance always exceeded chloride clearance by many fold and increased with urine flow, but fluoride clearance was always less than creatinine clearance. Renal tubules in 2 individuals, reabsorbed respectively 51 and 63% of fluoride in the glomerular filtrate which indicates a net process of glomerular filtration with a variable amount of tubular reabsorption. Plasma contained 72% of whole blood radiofluoride and radiofluoride concentration of plasma exceeded that of parotid gland saliva. Measurement of uptake and release of the radioisotope by soft tissues and by the skeleton showed characteristic differences of radiofluoride retention in these tissues. Skeletal tissues retained the isotope but soft tissues lost nearly all their activity within 4 hours after ingestion.

Determination of fluoride: Procedure based upon diffusion of hydrogen fluoride☆

Abstract The principle of fluoride determination by diffusion of hydrogen fluoride in Conway-type cells made of polypropylene has been applied to the determination of fluoride in plasma, liver, muscle, calcified tissues, urine, and saliva. Methods for preparation of the low fluoride containing biological specimens by precipitation of proteins with perchloric acid and analysis of the supernatant liquid are described. The results of fluoride analyses by diffusion compare well with those obtained by microdistillation. The diffusion method for fluoride analysis is more simple than distillation procedures.

Placental transfer of fluoride and calcium.

Abstract Maternal (uterine) artery, maternal (uterine) vein, umbilical artery, and umbilical vein blood were obtained simultaneously at the time of 16 cesarean sections. Calcium determinations of these blood plasma samples and those from women in their ninth month of pregnancy suggest either that a calcium “pump” operates in the placenta supplying a higher concentration of calcium to the fetal blood supply than is found in the maternal circulation or that the calcium homeostatic mechanisms operate at different levels in the maternal and fetal organisms. The fluoride concentrations found in the blood plasmas suggest that the placental barrier to the transport of fluoride ion does not operate so as to maintain a difference in concentration of fluoride between the maternal and fetal body fluids.

Determination of ionic (plus ionizable) fluoride in biological fluids. Procedure based on adsorption of fluoride ion on calcium phosphate.

Abstract A method is deseribed for the determination of ionic (plus ionizable) fluoride in biological fluids by a procedure not requiring ashing, diffusion, or distillation. The method is based on quantitative adsorption of ionic fluoride on calcium phosphate. The fluoride adsorbed on calcium phosphate is measured with the fluoride ion electrode. The concept of “ionic fluoride” which emerged from these studies demonstrates the need for reinvestigation of the subject of homeostasis of fluoride in the body.

Fluoride in Plaque

Large concentrations of fluoride in dental plaque were reported by Dawes et al (Brit Dent J 119: 164, 1965). Jenkins et al (Arch Oral Biol 14: 105-119, 1969) estimated that with the Orion fluoride electrode the ionic fluoride in human plaque was only 2 to 3% of the total fluoride and suggested that much of the fluoride in plaque bacteria cultured in a medium containing 50 ppm fluoride is bound within bacterial cells. Two separate pools (1 and 2) of plaque material were collected in the dental clinics at the University of Minnesota Dental School and the Hennepin County General Hospital in Minneapolis. The population in this region has access to municipal water containing 1 ppm fluoride. The determined concentration of total fluoride in pool 1 was similar when the electrode was used to determine the fluoride isolated after diffusion from unashed plaque (18.9 + 2.97 [SD] ppm) or from the ash of plaque fixed with Ca3(PO4)2 before ashing (18.8 + 0.37 [SD] ppm) (L. SINGER and W. D. ARMSTRONG: Anal Chem 40:613, 1968). When specimens of the plaque in pool 1 were dispersed in isotonic saline and buffered to pH 4.7 with acetate buffer, 7.4% of the plaque fluoride was responsive to the fluoride electrode. Similar results were obtained with plaque material of pool 2, which contained 13.7 + 0.58 (SD) ppm total fluoride in the fresh state. When the pool 2 plaque sample was placed in a small volume of isotonic saline in a cellophane dialysis bag (5 ml) and dialyzed for 24 hours against a large volume of isotonic saline (20 ml, pH 6.0), the total plaque fluoride was dialyzable

Retention and turnover of radiocalcium by the skeleton of large rats.

Summary The calcium specific activities of the femoral epiphyses, femoral diaphyses, humeri, lumbar vertebrae and the remainder of the skeleton of large rats differ soon after the administration of radiocalcium but decrease to a common value after 52 days, following which the specific activities decline at equal but much reduced rates. The fraction of the injected dose of radiocalcium retained in the animals declines to 42-45% on the 52nd day, after which only small quantities of radiocalcium are excreted. The results indicate the existence in large rats of two kinds of skeletal calcium which differ markedly in their rate of turnover and in the lenght of time over which they fix radiocalcium. The apparent reduction in skeletal calcium specific activity occurring in large rats after the 52nd day following the injection of radiocalcium is due to accretion of calcium to the skeleton. Part of the decline in skeletal specific activities which takes place in rats before radiocalcium excretion ceases is also due to skeletal growth. Data as to the changes of calcium specific activity of the urine and the teeth following the injection of labelled calcium are presented and discussed.

Determination of fluoride in ultrafiltrates of sera

Abstract A method has been described for the determination of the ionic fluoride content of ultrafiltrates of sera. The ultrafiltrates are easily obtained and can be satisfactorily analyzed with the fluoride-ion electrode to provide an accurate determination of ionic fluoride. The technique provides an indirect method for determining the ultrafiltrable nonionic fluoride when the total ultrafiltrable fluoride is known. The results can be related to the concentration of fluoride in the original sera on the basis of the water content of the sera. Evidence was presented that a large part of the fluoride in sera is ultrafiltrable and bound but not to the protein of molecular weights of 25,000 or greater nor to metallic cations.

Microdetermination of calcium in biological materials

Abstract A simple reliable colorimetric method for microquantities of calcium using glyoxal bis(2-hydroxyanil) as a color reagent has been described. The method has been applied to serum, fresh muscle, and calcified tissue. Values obtained by this technique have been checked by other methods of analysis and the results support the reliability and accuracy of the method.

Fertility Impairment in Mice on a Low Fluoride Intake

Female mice maintained on a low fluoride diet over two generations showed a progressive decline in litter production. Mice receiving the same diet supplemented with fluoride reproduced normally and at consistent intervals. Addition of fluoride to the intake of females with demonstrated impaired fertility restored their reproductive capacity.