The metabolic clearance rate of osteocalcin in sheep.

Plasma osteocalcin has been proposed as a useful and convenient biochemical marker of bone formation. However, the effect on plasma osteocalcin due to variations in the rate of its removal from the circulation has been little investigated. We have measured the metabolic clearance rate of plasma osteocalcin in adult oophorectomized sheep.

Hypokalemic periodic paralysis of thyrotoxic origin.

A 50-year-old Vietnamese man suffered recurrent episodes of hypokalemic periodic paralysis during treatment for thyrotoxicosis. Suspected precipitants of the paralysis were oral prednisolone, strenuous exertion and poor compliance with medications. Propranolol prevented the periodic paralysis.

Metabolism of osteocalcin.

After intravenous injection, labeled bovine osteocalcin was rapidly removed from rat plasma and taken up mainly by kidney, liver, and bone. The rate of disappearance was slowed by nephrectomy but not as much by ureteric ligation, suggesting renal destruction of osteocalcin rather than renal excretion. Both liver and kidney tissue rapidly degraded osteocalcin, both in vivo and in vitro.

Plasma osteocalcin in man.

A radioimmunoassay for bovine osteocalcin has been developed. Human osteocalcin reacted identically with the bovine standard, allowing the use of this assay to measure human plasma osteocalcin. Levels were determined in 212 healthy subjects (124 men, 88 women) with an age range of 20 to 66 years.

Noncollagenous proteins in normal and pathological human bone.

The concentrations of alpha 2HS-glycoprotein, albumin, and sialic acid were measured in the bone of 28 normal individuals and 6 patients with osteogenesis imperfecta, 3 patients with Paget's disease, and 4 patients with either renal osteodystrophy, osteoporosis, osteomalacia, or osteopetrosis. The concentration of alpha 2HS-glycoprotein in neonatal bone was 3 X higher than in bone from children and 7 X higher than in adult bone. The concentrations of albumin and sialic acid in neonatal bone were 1.

Analysis of collagen from normal and abnormal human bone.

Using cyanogen bromide digestion of bone collagen, we have studied the type of collagen in normal bone, and in samples from patients with Paget's disease of bone, osteomalacia, osteoporosis and renal osteodystrophy. Despite extensive extraction with ethylene diamine tetraacetic acid and guanidine hydrochloride, not all of the glycoproteins could be removed from bone collagen. Upon electrophoresis on sodium dodecyl sulphate polyacrylamide gels, the cyanogen bromide peptides of insoluble bone collagen showed the pattern of type I collagen only in all samples, both normal and abnormal.

Chemical composition of human bone.

The mineral and non-collagenous organic components of normal human femoral cortex were examined following powdering, demineralization with EDTA and digestion with bacterial collagenase. The protein, hexose, sialic acid and uronic acid contents of the matrix were determined. Neonatal bone had lower levels of mineral and calcium and higher levels of organic material and sialic acid than adult bone, suggesting increased glycoprotein content in neonatal bone.

Effect of temperature on phospholipase C induced alterations in insulin binding.

Regulation of insulin-receptor affinity is at present poorly understood. In this study membrane structure was modified by exposing placental membranes to phospholipase C and the subsequent effect on insulin binding and dissociation was examined. As previously described, when insulin-receptor binding was performed at 4 degrees C, phospholipase C treated membranes showed an increase in the apparent number of insulin receptors.

The demonstration of sialic acid in kidney stone matrix.

1. The organic matrices of 12 kidney stones containing calcium and two composed of uric acid were solubilized, with ethylenediaminetetra-acetate for the former and sodium hydroxide for the latter. 2.

The effects of trypsin and phospholipase C on insulin binding and action in the isolated adipocyte.

The effect of alterations to the insulin receptor on the insulin sensitivity of isolated adipocytes was studied. Receptor changes were induced by treatment of adipocytes with either phospholipase C or trypsin. After enzyme treatment, binding of insulin to insulin receptors and insulin-mediated glucose metabolism were examined.

Osteomalacia due to unusual causes presenting in adults.

Severe osteomalacia due to causes other than malabsorption and, where renal function was impaired, disproportionate to the degree of renal failure, is described in 15 adults. Only one was younger than 46 years, the median age being 59 years. The diagnosis was not made for months in most patients.

Metabolic properties of hormonally responsive osteogenic sarcoma cells.

There is sufficient impetus from the clinical nature of osteogenic sarcoma to stimulate basic studies of the effects of hormones on tumor growth and differentiation. This can probably best be done first by the use of in vitro studies to determine precisely the effects of certain hormones on tumor cell growth and biochemical function. Such investigations would hopefully indicate the direction of in vivo work.

Hypercalcaemia in adult hospital population: comparison of inpatients of 1966 with those of 1976.

During 1976, inpatients with hypercalcaemia at The Royal Melbourne Hospital were identified from the worksheets of the Department of Biochemistry and compared with those discovered in a similar study in 1966. In 1966, the estimation of plasma calcium level had to be ordered specifically, whereas in 1976, for technical reasons, the measurement of plasma calcium level was frequently performed when not requested. Despite a six-fold increase in plasma calcium in the rate of detection of hypercalcaemia.

The effects of digestive enzymes on characteristics of placental insulin receptor. Comparison of particulate and soluble receptor preparations.

The role of the surrounding membrane structure on the binding characteristics of the insulin receptor was studied by using several digestive enzymes. The effects observed with particulate membrane preparations are compared with those from soluble receptor preparations. beta-Galactosidase and neuraminidase had no effect on insulin binding to either particulate or soluble receptors from human placentae.

The effect of growth retardation and of osteomalacia on the uptake of albumin by bone.

125I-labeled rat albumin injected intravenously into rats was taken up by growing bone. Some of this radioactive albumin could be removed from bone by washing with saline, the proportion so removed decreasing from 82.5% at 1 day to 7.

Clinical, biochemical and histological observations on the effect of porcine calcitonin in Paget's disease of bone.

The response to porcine calcitonin has been assessed in 38 patients with Paget's disease, observed during 44 treatment periods of from three to 42 months. In 36 of the treatment courses significant relief of pain was achieved but the contribution of placebo effect could not be determined. Serum alkaline phosphatase and urinary hydroxyproline levels reached normal in a few patients, but the grouped data indicated a plateau effect above the range of normal.

Correlation between insulin receptor binding in isolated fat cells and insulin sensitivity in obese human subjects.

This study examined the relationship between receptor binding of insulin in a metabolically significant target tissue in vitro and sensitivity to insulin in vivo in obese human subjects. Specific insulin binding was measured at 24 degrees C in isolated enlarged fat cells obtained from 16 patients, by observing the effect of increasing concentrations of unlabeled insulin on the binding of [125I]insulin. Scratchard plots of the binding data were curvilinear with an upward concavity, similarity shaped, and essentially parallel.