Survey of vitamin D metabolite levels during growth and development in Japanese quail.

Plasma calcium and vitamin D metabolite levels were monitored during growth and development in male and female Japanese quail. In male Japanese quail, plasma calcium levels were constant (range 9.0 to 10.

Effect of dietary mineral and vitamin D content and parathyroidectomy on the plasma disappearance rate of 1,25-dihydroxyvitamin D3 in rats.

The plasma disappearance rate of 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] was determined in rats after a single intravenous injection of the tritiated hormone. Tritiated 1,25-(OH)2D3 (120 Ci mmol-1) was administered to rats at a dose of 400 000 dpm kg-1 body weight and the animals were bled between 0 and 8 hours. The dose was estimated to produce negligible perturbations in endogenous plasma levels of 1,25-(OH)2D3.

Proteins of the kidney microvillar membrane. The 130 kDa protein in pig kidney, recognized by monoclonal antibody GK5C1, is an ectoenzyme with aminopeptidase activity.

The hybridoma GK5C1, secreting a monoclonal IgG1 antibody, was generated after immunizing a mouse with pig kidney microvillar membranes. An immunoradiometric assay showed that only kidney and intestine contained detectable amounts of the antigen recognized by the antibody, the highest concentration being observed in the ileum. Immunocytochemistry confirmed this observation and revealed that the antigen was associated with renal and intestinal brush borders.

Proteins of the kidney microvillar membrane. Purification and properties of carboxypeptidase P from pig kidneys.

Carboxypeptidase P has been purified by immunoaffinity chromatography from pig kidneys. A single-step assay with Z-Pro-Met (where Z represents benzyloxycarbonyl) as substrate was used, methionine being determined by using L-amino acid oxidase and horseradish peroxidase. The enzyme constitutes about 1.

The metabolism of neuropeptides. Endopeptidase-24.11 in human synaptic membrane preparations hydrolyses substance P.

Synaptic membrane preparations from human striatum and human diencephalon were shown to contain a phosphoramidon-sensitive metalloendopeptidase that appeared identical with endopeptidase-24.11. The activity of endopeptidase-24.

An immunoradiometric assay for endopeptidase-24.11 shows it to be a widely distributed enzyme in pig tissues.

An immunoradiometric assay for endopeptidase-24.11, which depended on the absorption by tissues of a monoclonal antibody, GK7C2, was established. The optimum conditions for the assay were defined and its correlation with an enzymic assay determined.

Activation of avian medullary bone osteoclasts by oxidized synthetic parathyroid hormone (1-34).

Synthetic bovine parathyroid hormone (1-34) [bPTH(1-34)] has been treated with hydrogen peroxide and assayed for the effect of such treatment on the ability of bPTH(1-34) to activate medullary bone osteoclasts during their quiescent period in the early phase of the ovulatory cycle in Japanese quail. In addition, the same batches of oxidized and unoxidized bPTH(1-34) were assayed for their hypercalcemic activity in Japanese quail and their capacity to stimulate renal adenylate cyclase activity in the same species. Three groups, each consisting of five 5-month-old egg-laying Japanese quail (Coturnix coturnix japonica), were used.

Role of carbonic anhydrase in bone resorption induced by 1,25 dihydroxyvitamin D3 in vitro.

The present investigation was undertaken to study the role of carbonic anhydrase in 1,25 dihydroxyvitamin D3-induced bone resorption. Calvaria were removed from 5- to 6-day-old mice and cultured for periods up to 96 h in Dulbecco's Modified Eagle Medium (high glucose, 4,500 mg/dl) supplemented with antibiotics and either heat-inactivated horse and fetal calf sera or bovine serum albumin. The experimental cultures contained 1 X 10(-8) M 1,25 dihydroxyvitamin D3 (1,25(OH)2D3).

Role of carbonic anhydrase in bone: partial inhibition of disuse atrophy of bone by parenteral acetazolamide.

Carbonic anhydrase inhibitor acetazolamide blocks the hypercalcemic response to parathyroid hormone (PTH) and to dibutyryl 3',5'-cyclic AMP in the nephrectomized-parathyroidectomized rat. In addition, we have reported that acetazolamide, when incorporated in the diet, partially prevents denervation-induced bone loss in a rat model of disuse osteoporosis. The present study compares the effectiveness of orally and subcutaneously administered acetazolamide in preventing denervation-induced bone loss in the rat model.

Role of carbonic anhydrase in bone: plasma acetazolamide concentrations associated with inhibition of bone loss.

Earlier reports from our laboratory have indicated that the carbonic anhydrase inhibitor acetazolamide blocks the hypercalcemic response to parathyroid hormone. In addition, we have reported that acetazolamide when administered by several routes partially prevents denervation-induced bone loss in a rat model of disuse osteoporosis. Continuous subcutaneous infusion required the least daily dose (8 mg/kg).

Role of carbonic anhydrase in bone resorption induced by prostaglandin E2 in vitro.

The possible role of carbonic anhydrase in bone resorption induced by prostaglandin E2 (PGE2) was studied using an in vitro neonatal mouse calvarial culture system. PGE2 (10(-6) M) was effective in stimulating resorption, as assessed by calcium release into culture media. This enhanced resorption was accompanied by significant increases in calvarial carbonic anhydrase activity over control values at 48 and 96 h.

Proteins of the kidney microvillar membrane. Effects of monensin, vinblastine, swainsonine and glucosamine on the processing and assembly of endopeptidase-24.11 and dipeptidyl peptidase IV in pig kidney slices.

The effects of various inhibitors were studied on the biogenesis of endopeptidase-24.11 (EC 3.4.

Proteins of the kidney microvillar membrane. Biosynthesis of endopeptidase-24.11, dipeptidylpeptidase IV and aminopeptidases N and A in pig kidney slices.

An organ culture employing slices of renal-cortex tissue from piglets of the Yucatan strain was used to study the biogenesis of four microvillar peptidases: endopeptidase-24.11 (EC 3.4.

The metabolism of neuropeptides. The hydrolysis of peptides, including enkephalins, tachykinins and their analogues, by endopeptidase-24.11.

Endopeptidase-24.11 (EC 3.4.

Endopeptidase-24.11 and aminopeptidase activity in brain synaptic membranes are jointly responsible for the hydrolysis of cholecystokinin octapeptide (CCK-8).

Endopeptidase-24.11 (EC 3.4.

Cardiac actions and structural--activity relationship of parathyroid hormone on isolated frog atrium.

The hypercalcemic and hypotensive actions of parathyroid hormones (PTH), parathyroid extract, and synthetic PTH-(1-34) have been reported in many different animals. However, their cardiac action was only recognized recently. In the present study, experiments were designed to examine (1) whether PTH possesses any cardiac action on the isolated frog atrium, and (2) the importance of methionine and arginine of bPTH-(1-34) in cardiac action.

Deglycosylation by trifluoromethanesulphonic acid of endopeptidase-24.11 purified from pig kidney and intestine.

Endopeptidase-24.11, an integral microvillar membrane enzyme, exists in differently glycosylated forms when purified from pig kidney and intestine [Fulcher, Chaplin & Kenny (1983) Biochem. J.

The psychiatric expert in court.

The law about expert evidence is unsatisfactory: it gives scope for the expert to usurp the role of judge, jury and parliament; it brings the professions of the experts into disrepute; and it sets juries the impossible task of sorting pseudo sciences from genuine ones. The law should be reformed by changing statutes which force expert witnesses to testify beyond their science, by taking the provision of expert evidence out of the adversarial context, and by removing from the courts the decision whether a nascent discipline is or is not a science.

Uterine relaxing action of parathyroid hormone: effect of oxidation and methionine substitution.

The effects of bPTH-(1-34), oxidized bPTH-(1-34),[Nle8,Nle18, Tyr34] bPTH-(1-34) amide, and oxidized [Nle8,Nle18,Tyr34]bPTH-(1-34)amide were tested in an in vitro rat uterine assay. When bPTH-(1-34) was treated with hydrogen peroxide (H2O2), the ability of this peptide to reduce oxytocin-stimulated uterine contraction in vitro was no longer evident. An analogue of bPTH-(1-34), in which the methionines at positions 8 and 18 were replaced with norleucine ([Nle8,Nle18,Tyr34]bPTH-(1-34)amide), was capable of reducing oxytocin-stimulated uterine contraction.

Purification of endopeptidase-24.11 ('enkephalinase') from pig brain by immunoadsorbent chromatography.

Membrane preparations from striatum of pig brain contain endopeptidase activity towards iodoinsulin B-chain. Only 50% of the hydrolysis of insulin B-chain is inhibitable by phosphoramidon, and DEAE-cellulose chromatography can resolve the phosphoramidon-sensitive and -insensitive activities. The former activity (now designated 'endopeptidase-24.

Proteins of the kidney microvillar membrane; analysis by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and crossed immunoelectrophoresis.

A microvillar fraction was prepared from human kidney cortex. This fraction was seven to 10 times enriched in aminopeptidases N and A, gamma-glutamyltransferase, dipeptidyl peptidase IV, neutral endopeptidase and alkaline phosphatase. Dipeptidyl peptidase IV activity of human renal microvilli could be inhibited by di-isopropylphosphorofluoridate and neutral endopeptidase activity by phosphoramidon.