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Biomedical subjects

T M Murray

Publications and source records attributed to T M Murray.

At least 91 records · Page 5Linked to original sources
PubMed1979

Postfeeding radioimmunoassay artefact in heparinized pig plasma: studies with intestinal calcium-binding protein.

Samples of pig blood were taken in relation to feeding and assayed for intestinal CaBP by radioimmunoassay. When heparinized plasma was assayed by a double-antibody technique, significant postprandial increases of plasma immunoreactivity between twofold and 10-fold were noted. These apparent feeding responses were seen only with heparinized plasma and not with EDTA plasma, ACD plasma, or serum. Nor were such responses seen when heparinized plasma was assayed with talc or charcoal methods for phase seperation. The height of the artefactual response in immunoreactivity following feeding was related to the amount of carrier serum added during the incubation with second antibody and with the duration of this incubation. The artefact was seen in the presence of 0.01M EDTA. These results demonstrate a striking postfeeding radioimmunoassay artefact localized to the second-antibody precipitation step. The artefact can easily be avoided by several methodological changes. Such an artefact could conceivably affect other double-antibody radioimmunoassays of hormones or other substances. Caution is advised when double-antibody radioimmunoassays are used to assay samples taken in relation to feeding.

Animals↗
PubMed1978

Hypercalcemia and cancer: an update.

Hypercalcemia is a not infrequent complication of cancer that every physician should be aware of. It is a significant factor in the morbidity and mortality of cancer patients. Almost invariably hypercalcemia is associated with accelerated resorption of bone, which is thought to be mediated by humoral or metabolic factors. Three such factors, parathyroid hormone, E2 prostaglandins and osteoclast activating factor, have been strongly implicated in the pathogenesis of hypercalcemia in cancer patients. Other mechanisms for the hypercalcemia may exist. Accurate diagnosis of the disorder is important in therapy, and current research into the various mechanisms for hypercalcemia in cancer patients may well lead to new modes of therapy that are more specific and perhaps less toxic.

Bone Resorption↗
PubMed1978

Calcium metabolism in adult outpatients with epilepsy receiving long-term anticonvulsant therapy.

Long-term anticonvulsant drug therapy may lead to abnormalities of calcium metabolism resulting in osteomalacia. The prevalence and severity of altered calcium metabolism was studied in an adult outpatient population of persons with epilepsy receiving anticonvulsant therapy for a minimum of 2 years. Assessment of calcium metabolism was based on serum concentrations of calcium, phosphorus, alkaline phosphatase and 25-hydroxycholecalciferol and of plasma parathyroid hormone, intestinal absorption of isotopic calcium and skeletal bone mineral mass as determined by in vivo neutron activation or x-ray photodensitometry.Thirty-nine patients who had been receiving anticonvulsant therapy for an average of 20 years were studied; none had clinical evidence of metabolic bone disease. Decreased serum calcium concentration was noted in 10%, decreased serum phosphorus concentration in 10% and elevated serum alkaline phosphatase concentration in 44%. The mean serum 25-hydroxycholecalciferol concentration was significantly lower (P < 0.001) than in a control group (11.6 v. 19.6 mg/mL). None of 18 patients studied had an increased plasma concentration of parathyroid hormone, and only 1 of 17 patients had decreased intestinal absorption of isotopic calcium. Bone mineral mass was decreased in 44% of 32 patients studied.It was concluded that long-term treatment with anticonvulsant drugs leads to mild abnormalities of calcium metabolism and decreased bone mineral mass in a substantial percentage of adult outpatients with epilepsy. These abnormalities probably predispose the patients to the development of clinically significant metabolic bone disease.

Adult↗
PubMed1978

Effect of low phosphorus diets on intestinal calcium absorption and the concentration of calcium-binding protein in intact and parathyroidectomized pigs.

The effect of changing the dietary concentration of phosphorus on the intestinal absorption of calcium has been studied in conscious pigs each prepared with a Thiry--Vella loop of jejunum. A reduction in the percentage of phosphorus in the diet from 0.7 to 0.3% caused an increase in the efficiency of absorption of calcium from the fluid used to perfuse the jejunal loop in both intact and parathyroidectomized animals. There was a marked increase in the amount of calcium-binding protein (CaBP) in the small intestine of pigs fed the low phosphrous diet. Parathyroidectomy did not affect the amount of CaBP in the small intestine when either the normal or the low phosphorus diets were fed.

Animals↗
PubMed1977

Metabolic balance studies in patients with Paget's disease receiving salmon calcitonin over long periods.

Metabolic balance and calcium kinetic studies were performed in four patients with Paget's disease before treatment with salmon calcitonin and during the early and late stages of the treatment, which lasted 9 to 19 months, A significant decrease in bone turnover and 24-hour urine hydroxyproline and serum alkaline phosphatase values was observed in all patients. In contrast, the calcium, phosphorus and magnesium balances did not change significantly. In agreement with this, the partial body calcium, measured by in vivo neutron activation analysis, did not change. Intestinal calcium absorption increased initially, but returned to baseline levels 9 to 19 months after the study began. During the initial period there was a small, significant, but transient decrease in tubular reabsorption of phosphorus; this was accompanied by a significant decrease in serum phosphorus values--probably a direct effect of calcitonin rather than evidence of secondary hyperparathyroidism. Administration of salmon calcitonin to patients with Paget's disease decreases bone turnover without affecting calcium and phosphorus balances.

Aged↗
PubMed1976

Cellular localization of intestinal calcium-binding protein in pig duodenum.

The gamma-globulin fraction of a rabbit antiserum against porcine intestinal calcium-binding protein (CaBP) was used in an immunoperoxidase method to study CaBP localization in porcine duodenal tissue. Specific immunostaining, indicative of the presence of CaBP, was noted within the cytoplasm of the duodenal epithelial cells. No CaBP was detected in goblet cells or in the subepithelial layers. When the specific antibody was replaced by either nonimmune rabbit gamma-globulin or when the specific antibody was preadsorbed with excess CaBP, no positive immunostaining was seen. Our studies lend support to the hypothesis that CaBP may function in intracellular calcium transport.

Animals↗
PubMed1975

Treatment of hypoparathyroidism and pseudohypoparathyroidism with metabolites of vitamin D: evidence for impaired conversion of 25-hydroxyvitamin D to 1 alpha,25-dihydroxyvitamin D.

In hypoparathyroidism and pseudohypoparathyroidism, pharmacologic doses of vitamin D correct hypocalcemia, but the mechanism is unknown. In two children with hypoparathyroidism and one with pseudohypoparathyroidism we tested the hypothesis that in these conditions there is a defect in synthesis of 1 alpha,25-dihydroxyvitamin D3, the principal active metabolite of vitamin D. In both conditions, minute doses of the metabolite (0.04 to 0.08 mug per kilogram of body weight per day) quickly corrected hypocalcemia and increased intestinal calcium absorption. On the other hand, the effective dose of 25-hydroxyvitamin D3 to maintain normocalcemia was 3 to 4 mug per kilogram per day in the two conditions. Thus, the dosage ratio of 25-hydroxyvitamin D3 to 1 alpha,25-dihydroxyvitamin D3 approximated 100:1. By contrast this ratio was approximately 3:1 in two infants with vitamin D deficiency, a condition in which optimal metabolism of vitamin D would be expected. These findings suggest an impaired conversion of 25-hydroxyvitamin D to 1 alpha,25-dihydroxyvitamin D in both hypoparathyroidism and pseudohypoparathyroidism.

Administration, Oral↗
PubMed1975

A biologically active hormonal fragment isolated from bovine parathyroid glands (BPTH 1-65).

Fresh frozen bovine parathyroid glands were defatted in acetone, when extracted with phenol. Following trichloroacetic acid precipitation, the resultant peptides were chromatographed on Sephadex G-100. Parathyroid hormone (BPTH) characteristically elutes in the fourth peak. However, we also observed significant hormonal activity, both biological and immunological, in the fifth elution peak. The peak V material had potent hypercalcemic activity in the rat and chick, and stimulated adenylate cyclase activity in the rat renal cortex bioassay. This material was further purified by ion exchange chromatography on carboxymethylcellulose in 8 M urea. The biological activity of the purified peptide (3700 MRC units/mg) was equivalent to that of the native hormone on a molar basis. Amino acid analysis, carboxypeptidase digestion, and partial Edman sequence analysis identified this material as BPTH 1-65, a hormonal fragment lacking the C-terminal 19 residues of the 84 residue hormone molecule. Several immunoassays using different anti-PTH antisera had variable reactivity toward the BPTH 1-65 fragment, showing that it may be useful for further characterizing antibody recognition sites. The presence of a lysine residue at position 65 suggests a tryptic-like cleavage may be responsible for the genesis of this hormonal fragment. Further investigation will be necessary to determine if this peptide has physiological significance.

Amino Acid Sequence↗
PubMed1975

Inactivation of viruses and bacteria by ozone, with and without sonication.

Selected organisms with public health significance were placed in a reaction chamber for treatment by ozonation, by ozonation and sonication, by sonication, or by sonication during oxygenation. Vesicular stomatitis virus, encephalomyocarditis virus, GDVII virus, Staphylococcus aureus, Pseudomonas fluorescens, Salmonella typhimurium, enteropathogenic Escherichia coli, Vibrio cholerae, and Shigella flexneri were inactivated by treatment with ozone. When microorganisms were suspended in phosphate-buffered saline, they were inactivated rapidly by treatment with ozone. However, microorganisms suspended in secondary effluent from a wastewater treatment plant required longer contact times with ozone for complete inactivation. Simultaneous treatments by ozonation and sonication reduced the contact time for complete inactivation of microorganisms in secondary effluent. Treatment by sonication alone or sonication and oxygenation did not inactivate microorganisms. Therefore, the simultaneous treatment of microorganisms in secondary effluent with ozone and sonication resulted in a synergistic effect.

Animals↗
PubMed1975

Radioimmunoassay studies of intestinal calcium-binding protein in the pig. I. Identification of intestinal calcium-binding protein in blood and response to a low calcium diet.

We have developed a radioimmunoassay for porcine intestinal calcium-binding protein (CaBP) and have used it to detect CaBP in pig plasma. Plasma CaBP is identical to intestinal CaBP on the basis of immunological activity, molecular size, and molecular charge properties. The plasma CaBP concentration was greater in the portal blood than in mixed venous blood, suggesting that blood CaBP originates in the gut. Two of four 15-week-old littermate pigs were placed on a low calcium diet (0.15% calcium, 0.65% phosphorus) and two on a control diet (0.65% calcium, 0.65% phosphorus). After 2 weeks, the entire small intestine was removed and divided into nine 1.8-m segments. CaBP was assayed in both plasma and intestinal mucosa. When the two pigs on a low calcium diet were compared with two control pigs, there was a general increase in immunoreactive CaBP in both plasma and intestinal mucosa. However, there was no increment in immunoreactive CaBP in the first 1.8-m segment of small intestine. Seventy-one percent of the increment in CaBP occurred distal to the first two segments. The largest fractional low calcium diet effect occurred in the ileum. The mean CaBP concentration for the total small intestine increased by a factor of 1.9. The plasma CaBP concentration increased by a factor of 2.6. In these pigs, plasma CaBP was a more reliable indicator of change in CaBP status than was the measurement in the proximal gut segment which contained the duodenum. The assay of CaBP in blood is convenient and may obviate the sampling errors inherent in intestinal biopsy.

Animals↗
PubMed1975

Radioimmunoassay studies of intestinal calcium-binding protein in the pig. II. The distribution of intestinal CaBP in pig tissues.

Using a specific radioimmunoassay for porcine intestinal calcium-binding protein (CaBP), we have measured the concentration of CaBP in the various tissues and organs of normal pigs. Intestinal CaBP was present in highest concentration in the upper small intestine, with lower concentrations in the distal small intestine. Intestinal CaBP was also found, in lower concentrations, in kidney, liver, thyroid, pancreas, and blood. In all other tissues, including parathyroid, bone, skeletal muscle, and brain, CaBP immunoreactivity was undetectable or less than in blood. The elution profile of calcium-binding activity and immunoreactivity from gel filtration analysis of kidney and parathyroid extracts suggest that the calcium-binding protein in the parathyroid gland, and the major calcium-binding protein(s) in the kidney, are chemically and immunochemically different from intestinal CaBP.

Animals↗
PubMed1974

Parathyroid carcinoma: location of pelvic metastases by parathyroid hormone assay.

A metastasis from a functioning parathyroid carcinoma was located by PTH radioimmunoassay and selective venous catheterization. The site of the metastasis, verified at autopsy, was in the right side of the pelvis. This is the most distant reported location for metastatic parathyroid carcinoma. The patient's plasma immunoreactive PTH rose more than twofold in response to induced hypocalcemia. This suggests that relative hypocalcemia, induced therapeutically in such patients, may result in a higher chronic level of PTH secretion.

Aged↗