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Biomedical subjects

C Norris

Publications and source records attributed to C Norris.

At least 73 records · Page 4Linked to original sources
PubMed1986

Effect of time and dose of indomethacin on follicular prostaglandins and ovulation in the rabbit.

This study determined specifically when ovarian prostaglandins (PGs) increase during ovulation and how effectively different doses of indomethacin inhibit PGs and ovulation. Rabbit ovarian follicles were removed at hourly intervals after stimulating the animals with hCG (50 IU/kg). The follicles were homogenized in 0.1 M acetate buffer (pH 4.5), and the PGE and PGF in the extracts were measured by RIA. Ovulation rates were determined by calculating the percentage of mature follicles that ruptured after stimulation by hCG. Before hCG, the normal levels of PGE and PGF were 111.1 +/- 14.7 and 51.0 +/- 6.6 pg/mg follicle, respectively. By 2 h after hCG treatment, PGE and PGF both increased to 162.6 +/- 17.0 and 80.6 +/- 13.3 pg/mg follicle, respectively. Approximately 5 h later, there was a second, sharper increase in both PGs which peaked at 652.6 +/- 63.5 and 345.4 +/- 32.3 pg/mg follicle, respectively, 10 h after hCG treatment, i.e. at the expected time of ovulation. We found that regardless of whether indomethacin was given early or late during the ovulation process, this agent significantly reduced follicular PG production within 5 min after its administration. For example, only 5 min after 10 mg/kg indomethacin were administered 8 h after hCG, PGE and PGF dropped from 317.7 +/- 50.0 and 125.0 +/- 10.5 pg/mg follicle to 93.3 +/- 17.4 and 49.3 +/- 10.5 pg/mg follicle, respectively. Unexpectedly, when graded doses of indomethacin were administered either 1 or 8 h after hCG, there was not a statistically significant correlation between follicular PG levels and ovulation rate. For example, when doses of 1.25, 2.5, 5.0, and 10.0 mg/kg indomethacin were given 8 h after hCG, the PGE and PGF levels at the expected time of ovulation (i.e. 2 h later) were always equal to or less than the PG levels in follicles that had not been stimulated by hCG, yet ovulation proceeded at rates of 46.7 +/- 12.3%, 30 +/- 7.7%, 14.3 +/- 9.3%, and 0%, respectively. Therefore, the results raise questions about the specific role of PGs in the ovulation process.

Animals↗
PubMed1986

Capillary permeability changes in the uteri of recipient rabbits after transfer of blastocysts from indomethacin-treated donors.

Blastocysts recovered from control or indomethacin-treated (10 mg/kg s.c. twice daily starting on Day 4.5 of pregnancy) donor rabbits were transferred to the uteri of Day-6 or 6.5 pseudopregnant recipients. The minimal time required to cause an increase in capillary permeability in the endometrium underlying control blastocysts was approximately 9 h. Blastocysts derived from the indomethacin-treated donors were depleted of PGE and PGF (determined by RIA) and were unable to produce any increase in capillary permeability during the same time period, although after 46 h in vivo the diameters of the implantation swellings related to control or indomethacin-treated blastocysts were not different. This suggests that, in the untreated recipients, blastocysts depleted of PGs can become replenished and then release these PGs in a site-directed manner. Indomethacin thus causes a delay rather than a complete inhibition of implantation. Incubation of the indomethacin-treated blastocysts in vitro led to replenishment with PGs, but such replenished blastocysts failed to induce an increase in capillary permeability within the same time-frame as control blastocysts. Evidence is presented that indomethacin is probably not the cyclooxygenase inhibitor of choice, since it interferes with PG uptake and efflux. Such an action could explain the failure of the replenished blastocysts to induce a normal increase in capillary permeability.

Animals↗
PubMed1984

Effect of calcium and phosphorus on zinc metabolism in man.

Calcium and phosphorus have been shown to inhibit the availability of zinc for absorption in animal studies, but limited information is available on this subject in man. In the present study, the effect of both calcium and phosphorus on zinc metabolism was investigated in adult men by determining metabolic balances of zinc during three intake levels of calcium of 200, 800, and 2000 mg/day, and during two intake levels of phosphorus of 800 and 2000 mg/day. The analyzed dietary zinc intake was normal and was kept constant throughout all study phases. Increasing the calcium intake from 200 mg to two higher intake levels up to 2000 mg/day did not significantly change the urinary or fecal zinc excretions or the zinc balance. Also, increasing the phosphorus intake from 800 to a high intake of 2000 mg/day did not have any effect. The simultaneous use of the high calcium and high phosphorus intake also had no effect on zinc excretions and on the zinc balance.

Adult↗
PubMed1984

Calcium requirements in humans. Report of original data and a review.

Presently submitted and previously available data indicate that the recommended calcium requirement of 800 mg/day is inadequate for a large segment of the population, particularly the elderly. With an intake of 800 mg of calcium/day, calcium balance was only slightly positive, without consideration of dermal losses or other risk factors that may play a role in calcium bioavailability and calcium retention. A calcium intake of 1000-1200 mg/day is preferable, as calcium balance increased significantly when calcium intake was increased from 800 to 1200 mg/day; there was no further improvement in calcium balance on higher calcium intakes, up to 2300 mg/day.

Adaptation, Physiological↗
PubMed1983

Further studies of the effect of a high protein diet as meat on calcium metabolism.

Previous studies in this Unit have shown that a high protein intake, given as meat, did not induce hypercalciuria, except for the initial and temporary increase in two subjects. In the present investigation the long-term effect of a high meat diet on calcium metabolism was studied for 78 to 132 days in four adult males and the short-term effect for 18 to 30 days in three subjects. Calcium and phosphorus balances and calcium absorption studies, using 47Ca as the tracer, were carried out. During the long-term high meat intake and during the short-term high meat studies, there was no significant change of the urinary or fecal calcium nor of the calcium balance. There was also no significant change of the intestinal absorption of calcium during the high meat intake. These long- and short-term studies have confirmed our previous results that a high protein intake, given as meat, does not lead to hypercalciuria and does not induce calcium loss.

Adult↗
PubMed1982

Amino acid content of guinea pig perilymph collected under conditions of quiet or sound stimulation.

With the cochlear aqueducts blocked, guinea pig cochleas were perfused with artificial perilymph. The collected perfusates were treated with 5-(dimethylamino)-1-naphthalenesulfonyl chloride (dansyl-Cl). The derivatized constituents were analyzed by high- performance liquid chromatography using fluorometric detection. The concentration of none of the compounds measured, including the putative transmitters glutamate and aspartate, was found to increase in the perfusate in response to sound stimulation. These results do not support the suggestion that one of these compounds might be primary afferent transmitter of audition.

Acoustic Stimulation↗
PubMed1982

Effect of small doses of aluminum-containing antacids on calcium and phosphorus metabolism.

The effect of small doses of four commercially available aluminum-containing antacids on calcium and phosphorus metabolism was investigated in adult males in 20 studies. During the use of these doses of antacids, urinary and fecal calcium increased significantly during a low calcium intake averaging 252 mg/day, and the calcium balances became distinctly more negative. There was a reversal of the normal pattern of phosphorus excretions, namely, the fecal phosphorus was high and the urinary phosphorus was low. During a normal calcium intake of 800 mg/day, these doses of antacids did not result in significant changes of the calcium excretions or balance. Despite the decrease in net intestinal absorption of calcium, the average 47Ca absorption remained unchanged, irrespective of the type and dose of antacid used. In three patients who received large therapeutic doses of antacids, 240 to 450 ml/day, the changes of calcium and phosphorus metabolism were intensified.

Adult↗
PubMed1980

Zinc65 absorption in patients with carcinoma of the prostate.

The intestinal absorption of 65 Zn was determined in patients with carcinoma of the prostate prior to treatment and during estrogen therapy. Following an oral tracer dose of 65 ZnCl2, plasma levels and urinary and fecal excretions of 65 Zn were determined. The absorption of 65 Zn was low in six of eight patients, particularly in three patients who had extensive metastatic bone involvement. During estrogen therapy the absorption of 65 Zn increased markedly in these patients, and this increase correlated with the clinical remission of the neoplastic process. In one patient who did not respond to estrogen therapy, 65 Zn absorption was normal prior to treatment and did not increase during estrogen therapy. In patients free of neoplasia estrogen administration did not increase 65 Zn absorption, and even decreased it. These results indicate that the intestinal absorption of 65 Zn is decreased during the active phase of carcinoma of the prostate and improves during clinical remission induced by estrogen therapy.

Aged↗
PubMed1980

Effect of aluminum hydroxide on fluoride metabolism.

Aluminum inhibits intestinal absorption of fluoride in animals but little information is available about man. To determine whether and to what extent aluminum affects fluoride absorption in man, effects of aluminum hydroxide on fluoride metabolism were studied under controlled dietary conditions. Relatively small amounts of aluminum hydroxide were used (30 ml three times daily, containing a total of 1.8 gm aluminum, were given for several weeks). Fluoride balances were determined in control studies and during the intake of aluminum hydroxide. The fluoride intake was the fluoride content of the diet and the drinking water. Two studies were also carried out on a high-fluoride intake. The use of aluminum hydroxide was associated with an increase in fecal fluoride excretion and a decrease in net absorption of fluoride regardless of the intake fluoride, calcium, phosphorus, or magnesium. Urinary fluoride decreased during aluminum hydroxide ingestion. Our studies show that relatively small amounts of aluminum hydroxide inhibit intestinal absorption of fluoride in man.

Aged↗
PubMed1980

Effect of calcium, phosphorus, magnesium, and aluminum on fluoride metabolism in man.

The studies of the interaction of fluoride with minerals in man have shown that: 1. in contrast to observations made in animals, the high intake of calcium, phosphorus, and magnesium in amounts that can be used in humans did not inhibit the intestinal absorption of fluoride in man; 2. the lack of effect of added calcium, given in divided doses, on the intestinal absorption of fluoride has relevance for the use of a high calcium intake during fluoride therapy for osteoporosis; 3. aluminum as the hydroxide, commonly used as an antacid in clinical medicine, significantly decreases the intestinal absorption of fluoride. This inhibitory effect, in conjunction with the known effects of aluminum-containing antacids in causing calcium loss as a consequence of phosphorus depletion, may contribute to the development of skeletal demineralization.

Adult↗
PubMed1980

Fluoride metabolism in patients with chronic renal failure.

Studies of fluoride metabolism were carried out in patients with chronic renal failure by determining fluoride balances for several weeks. The fluoride intake was due to the analyzed fluoride content of the diet and of the drinking water. The effect of aluminum hydroxide on fluoride metabolism was investigated because this antacid is commonly used therapeutically for these patients. Studies have shown that urinary fluoride excretion in patients with chronic renal failure was significantly lower than that in patients with normal renal function, resulting in a signicantly higher retention of fluoride. Although the fecal fluoride excretion in patients with chronic renal failure was slightly but significantly increased, this change did not compensate for the decrease of the urinary fluoride excretion. The intake of aluminum hydroxide resulted in a significant increase of fecal fluoride excretion and in a significant decrease of net absorption and retention of fluoride in patients with chronic renal failure.

Aged↗