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Biomedical subjects

H Spencer

Publications and source records attributed to H Spencer.

At least 127 records · Page 7Linked to original sources
PubMed1976

Metabolic balances of strontium in man.

Stable strontium balances were determined in man under strictly controlled dietary conditions in control studies and during both oral and intravenous administration of stable strontium. The diet contained about 1 mg strontium per day and most of this (88%) was excreted in stool while 17.5 per cent was excreted in urine, so that the balance was very slightly negative. During the oral intake of 1536 mg strontium per day, given as the lactate, the urinary and the fecal strontium excretions increased markedly and the balance became strongly positive. During the 6-day periods of intravenous infusions of stable strontium as the gluconate, 30-40 per cent of the infused amount was excreted in the urine and 5-10 per cent in stool. A high percentage of the strontium retained during both oral and intravenous administration was excreted in 30 days after the discontinuation of the strontium administration and there was no evidence of long term retention. The administration of stable strontium, given either orally or intravenously, was associated with an increase of the urinary calcium excretion.

Administration, Oral↗
PubMed1976

Effect of conventional and newer forms of treatment on calcium absorption in osteoporosis.

Studies carried out in this Research Unit and by others have shown that patients with osteoporosis absorb less calcium from a high calcium intake than do patients without osteoporosis. To determine whether various treatment modalities would increase the intestinal absorption of calcium, the effects of conventional and new methods were investigated. Tracer doses of 47Ca were given orally to determine the absorption of calcium. Calcium balances were also determined. Estrogen decreased urinary calcium and testosterone increased the nitrogen balance. Vitamin D and strontium increased the urinary calcium but did not increase calcium absorption. Of the newer compounds, fluoride did not affect calcium absorption but decreased urinary calcium. Phosphate had a similar effect. Infusions containing up to 15 mg calcium/kg, given for 6 or 10 days, increased the retention of calcium but did not increase its absorption.

Adult↗
PubMed1975

Effect of calcium and phosphorus on fluoride metabolism in man.

The effect of orally administered calcium and phosphorus on the fluoride balance was studied in man during a low fluoride intake of about 4 mg/day and a high fluoride intake of 14 mg/day. Three calcium intake levels averaging 223, 1,481, and 2,312 mg and two phosphorus intakes averaging 915 and 1,430 mg/day were used. Calcium or phosphorus used singly or combined did not affect the urinary fluoride. Increasing the calcium intake from an average of 223 to 1,481 and to 2,312 mg/day during the low fluoride intake increased the fecal fluoride only slightly, from 0.13 to 0.17 and 0.20 mg/day, respectively, and during high fluoride intake from 0.31 to 0.58 and 0.56 mg/day, respectively. The addition of phosphorus to the low calcium intake did not change the fecal fluoride excretion during either low or high fluoride intake, but the fecal fluoride increased during the two higher calcium intakes by a factor of 1.5. As the fecal fluoride was very low in the control study and was still relatively low in the experimental studies, the increase in fecal fluoride did not change the fluoride balances. The studies have shown that the increased levels of calcium and phosphorus used had little effect on fluoride metabloism in man.

Adult↗
PubMed1975

Excretion of retained fluoride in man.

In fluoride studies performed in man the excess fluoride excretions in urine and stool over and above the base-line excretions were determined following the discontinuation of fluoride supplements. The fluoride supplements contained either 9.1 mg fluoride as sodium fluoride, given daily for 32 days, or 7.6 mg fluoride as fish protein concentrate (FPC), given daily for 26 days. Following discontinuation of these fluoride supplements the excess fluoride excretions were low and of short duration, in most cases for 6-12 days. Since the fluoride supplements were given for a known period of time, the fluoride retention could be calculated from the fluoride balances, and the excess fluoride excretion corresponded to 9.1% of the retained fluoride given as NaF and to 14.1% of the retained fluoride given as FPC. The excess fluoride was predominantly excreted via the kidney, i.e., 87% of the total excess fluoride excretion was passed in urine and only 13% in stool.

Adult↗
PubMed1975

Retention of fluoride with time in man.

Fluoride retention is high during fluoride supplementation and increases with increasing fluoride intake. When large amounts of fluoride were given for several months the retention of fluoride was about the same as in the initial phase of fluoride supplementation, whether the supplemental dose of fluoride was 10, 20, or 45 mg per day. The rapid return of the fluoride balance to control values after the high fluoride intake was discontinued indicates that there is not only a tendency for continued retention of fluoride during the high fluoride intake but also after large amounts of fluoride have already been retained.

Adult↗
PubMed1975

Dietary fluoride intake of infants.

The fluoride content of various commercially available food items used in the preparation of the infant diet for the age groups from birth to 6 months has been analyzed and the total daily fluoride intake has been calculated on the basis of these data. The dietary fluoride intake totaled 0.32 mg/day for infants in the age group 1 to 4 weeks, increased in the subsequent months due to increasing food intake, and totaled 1.23 mg for infants 4 to 6 months of age. These fluoride intakes expressed per kilogram of body weight ranged from 0.07 mg/kg in the newborn to 0.16 mg/kg in the 6-month-old infant.

Animals↗
PubMed1974

Typographic coding in lists and bibliographies.

A comparison was made of the effectiveness of ten systems of typographical/spatial coding suitable for use in the presentation of highly structured information such as bibliographic material. With one exception, which requires a bold typeface, the systems tested are all suitable for the preparation of copy on a standard typewriter or an upper and lowercase line printer. Sections of alphabetical author index were typed in each of the ten styles and subjects were asked to look up lists of entries in each style. The most effective system on balance was a two-unit left extension of the first line of each entry.

Journal Article↗