External quality assessment of serum alpha-fetoprotein assays.

Adequate control of performance in immunoassays of maternal serum alpha-fetoprotein is an essential part of screening for neural tube defects. Information derived from external quality assessment schemes may be of limited value in monitoring individual laboratory performance and stresses the need for proper internal quality control.

Biochemical and clinical responses to dichloromethylene diphosphonate (Cl2MDP) in Paget's disease of bone.

Dichloromethylene diphosphonate (Cl2MDP, or clodronate disodium) is one of the most potent of the known diphosphonates as an inhibitor of bone resorption and differs from EHDP in that it does not inhibit skeletal mineralization. It is one of the second generation diphosphonates now undergoing clinical evaluation. In the study described here Cl2MDP was given by mouth (800-1600 mg/day for 6 months) to 35 patients with symptomatic Paget's disease of bone.

Treatment of bone disease after jejunoileal bypass for obesity with oral 1 alpha-hydroxyvitamin D3.

The effects of oral 1 alpha-hydroxyvitamin D3 have been investigated in 12 patients with bone disease after jejunoileal bypass for obesity. Bone histology became normal or improved greatly after four to 12 months' treatment in eight patients but showed little change or worsened in four. There was a significant rise in plasma calcium and fall in plasma alkaline phosphatase concentration with 1 alpha-hydroxyvitamin D3 therapy in the patients with a good histological response.

Effect of dichloromethylene diphosphonate in Paget's disease of bone and in hypercalcaemia due to primary hyperparathyroidism or malignant disease.

30 patients with disorders of calcium metabolism were treated with dichloromethylene diphosphonate (C1(2)MDP, or clodronate disodium), an inhibitor of bone resorption. 13 patients with Paget's disease of bone were given C1(2)MDP by mouth (1.6 g/day).

Non-specific binding of restriction endonuclease EcoR1 to DNA.

Restriction endonuclease, EcoRl cleaves the DNA sequence (see formula in text) at the points indicated. Under certain conditions, EcoRl activity is observed when (see formula in text) is cut. Mg2+ is required for both activities.

Vitamin D prophylaxis and osteomalacia in chronic cholestatic liver disease.

Bone histology was examined in 32 patients with chronic cholestatic liver disease, of whom just over one half were receiving high-dose parenteral vitamin D therapy. Four patients had histological evidence of osteomalacia; two of these were receiving vitamin D therapy, and showed only very mild osteomalacia, while the remaining two untreated patients had more severe bone disease. Plasma 25-hydroxyvitamin D levels were normal in all vitamin D-treated patients, and serum calcium concentrations were significantly higher in the treated group.

Measurement of human proinsulin by an indirect two-site immunoradiometric assay.

An indirect two-site immunoradiometric assay is described for the measurement of human proinsulin in plasma. Polyethylene tubes coated with purified guinea-pig antibodies to insulin were used to extract proinsulin and insulin from plasma. Rabbit antibody to human C peptide was then added to react with the C-peptide moiety of the bound proinsulin.

Drug contamination of mortars and pestles.

Evidence is presented suggesting that potent water-insoluble antipentylenetetrazol agents triturated in porcelain mortars and pestles are not removed from this mixing device by the usual laboratory washing procedure. Moreover, amounts sufficient to contaminate the next substance triturated in this vessel can be demonstrated by the subcutaneous pentylenetetrazol seizure threshold test. The data show that a rigorous washing routine must be followed to achieve a "clean" mortar and pestle.

Bone disease after jejuno-ileal bypass for obesity.

Bone tissue was examined in 21 patients who had undergone jejuno-ileal bypass for obesity between 1971 and 1974. 10 patients had osteomalacia with evidence of secondary hyperparathyroidism. Clinical symptoms and biochemical and radiological investigations were often unreliable in diagnosing bone disease, although plasma-25-hydroxyvitamin-D and plasma-phosphate concentrations were significantly lower and plasma-parathyroid-hormone concentrations were significantly higher in the patients with bone disease.

The nature of hypocalcaemia in acute pancreatitis.

A retrospective and prospective study was made of 82 attacks of acute pancreatitis occurring in 80 patients. Attacks were defined as mild (55) or severe (27) according to clinical criteria. Severe attacks were associated with significantly low levels of uncorrected calcium and calculated ionized calcium, both at the time of admission and 48 h later.

Two-site assay of bovine parathyroid hormone.

A two-site assay has been developed for bovine PTH. This technique involves reaction of the antigen with two antibody molecules with the purpose of increasing specificity. In paratice the hormone was extracted form plasma samples on to plastic tubes coated with antibody specific for PTH (1-34).

Serum-25-hydroxyvitamin-D concentrations in adolescent boys.

In March, 1976, vitamin-D status was investigated in 256 thirteen-year-old school boys of Asian, West Indian, andEuropean origin in Birmingham. Serum-25-hydroxyvitamin-D3 (25-OHD3) concentrations in 78% of the 124 Asian boys resembled those found in rickets and osteomalacia. Serum-25-OHD3 concentrations were also low in a few West Indian and European children.

Assay of parathyroid hormone in human serum and its uses.

The assay of parathyroid hormone has contributed greatly to our understanding of calcium metabolism in health and disease. The most important clinical application of the assay is in the differential diagnosis of hypercalcaemia, which is an increasing clinical problem. PTH assays are of little or no value in the absence of other biochemical data, especially accurate determinations of plasma calcium and phosphate.

Phaeochromocytoma and hypercalcaemia.

An example of possible pseudohyperparathyroidism associated with a non-endocrine benign tumour is reported. Some of the pertinent factors contributing to hypercalcaemia under these circumstances are reviewed, with particular reference to ectopic hyperparathyroidism and catecholamine-induced endogenous hyperparathyroidism.

Nonspecific effect of bis(2-ethylhexyl) phthalate on hexobarbital sleep time.

The data presented suggest that the intravenous or intraperitoneal administration of bis(2-ethylhexyl) phthalate prolongs hexobarbital sleep time in mice and rats by enlarging the lipophilic pool, a phenomenon that can be replicated by pretreatment of the animals with olive oil. These results call attention to the importance of considering the physical characteristics of a substance when evaluating its effect on a pharmacologically active agent.

Calcitonin production by rat thyroid tumours.

Immunolocalization techniques have been used to study 16 rat thyroids containing C cell tumours and ten rat thyroids in which no tumours or hyperplasias were found. All rats in these groups were at least 2 years old. An indirect ('sandwich') technique was used which involved rabbit or goat anti-human calcitonin antiserum and either fluorescein or peroxidase-labelled anti-rabbit or anti-goat IgG.