Muscle and bone in paraplegic patients, and the effect of functional electrical stimulation.

1. Four paraplegic men volunteered for an exercise programme in which their paralysed quadriceps muscles were stimulated by means of computer-regulated electrical impulses applied through external electrodes. The first exercise regimen consisted of leg raising against a graded load, and during the second regimen exercise took the form of cycling on a modified bicycle ergometer. Each subject exercised five times weekly for 10 weeks during the first regimen and 32 weeks during the second regimen. 2. Whole-body protein turnover determined by L-[1-13C]leucine during feeding remained constant during both exercise regimens, when expressed either in terms of body weight or fat-free mass derived from measurements of total body potassium. 3. Quadriceps muscle protein synthetic rate increased during the study, from 0.0712 to 0.0985%/h (P less than 0.05), as did quadriceps muscle area assessed by computed tomography. 4. Bone mineral content for lumbar vertebrae was normal in all four patients, but for the femoral mid-shaft bone mineral content averaged only 66% of normal for three of the patients. Trabecular bone density in the distal tibia ranged from normal to 2% of normal for the men with the shortest and longest periods of disability, respectively. No changes in bone mineral content or bone density occurred during the exercise period.

Dietary intake of calcium and postmenopausal bone loss.

The use of calcium supplements to prevent postmenopausal bone loss and hence osteoporosis is widespread, but the evidence for their efficacy, either alone or in combination with other treatments, is contradictory. Skeletal measurements and dietary intake of calcium were determined in 59 healthy postmenopausal women, most of whom were within five years of the menopause. No correlation was found between current intake of calcium and either total calcium in the body or the density of trabecular or cortical bone in the forearm or vertebral trabecular bone. Dietary intake of calcium did not influence the rate of postmenopausal bone loss in the 54 women who completed 12 months of active or placebo treatment. Even when extremes of calcium intake were examined no difference was found in bone measurements between the women with the highest and lowest intakes. The results of this study suggest that the bone density of women in the early menopause is not influenced by current dietary intake of calcium.

Critical analysis of the accuracy of a combined test (75Se-HCAT and 58Co-B12) of ileal function using a whole-body counter.

The accuracy of a combined test (75Se-HCAT + 58Co-B12) of ileal function by whole-body counting has been assessed with particular attention being paid to the reliability of the 100% retention measurements, the accuracy of the crossover of 58Co into the 75Se channel and the effects of variable counting geometry. A linear relationship between 58Co crossover and body weight improved the accuracy of determining the crossover value for individual patients. Non-geometrical errors such as those associated with counting statistics and crossover were found to be small, with a coefficient of variation usually less than +/- 2% except in cases of very low 75Se-HCAT retention in the presence of substantial amounts of 58Co. The main sources of error were due to problems of variable counting geometry but there was very good agreement between 75Se and 58Co retentions measured by whole body counting and by excreta analysis which suggested that the overall error of the test was unlikely to exceed +/- 10%. A protocol is presented for use of the combined test on an outpatient basis and includes retention measurements at 4, 7, and 10 d post administration.

Potassium supplements during long-term thiazide therapy for essential hypertension.

Increasing doses of a slow-release potassium supplement were given to nine hypertensive patients previously treated for at least 18 months with bendrofluazide 10 mg daily. Serum potassium and total body potassium (TBK) were measured after 2 months on each dose. No significant increase in serum potassium or TBK occurred over a 6 month period of supplementation using doses commonly prescribed in clinical practice.

Bone rarefaction and crush fractures in juvenile chronic arthritis.

Seventy children with juvenile chronic arthritis have had measurements of cortical and trabecular bone density in one or both radii. In 7 children with unilateral disease of one wrist, there was a substantial reduction in growth on the affected side. Trabecular bone density in the distal radius was reduced in the main group of 63 patients compared with controls, and this deficit was appreciably worse if the wrist was clinically affected by disease or if the child was being treated with steroids. Cortical bone density in the midshaft was less affected. Crush fractures of the spine were associated with more prolonged periods of bed rest, steroid therapy, radial trabecular bone density more than 2 standard deviations below normal, and subnormal 25-hydroxycholecalciferol concentrations in the serum. Since steroid therapy is often mandatory the main therapeutic implications are that the more severely affected child often needs vitamin D supplementation in "physiological" dosage, and that early mobilisation and reduction of steroid dosage should be constant aims.

Selenium 75-selenofolate metabolism and radiation dosimetry.

Following the oral administration of 75Se-selenofolate in two normal healthy volunteers, retention was measured by whole body counting, and distribution throughout the body was determined with a hybrid scanner. Approximately 65% of the dose was absorbed from the GI tract. The metabolic data obtained from this study was used to calculate the integrated radiation dose to the liver, and the effective dose equivalent.

Anabolic effect of low doses of a fragment of human parathyroid hormone on the skeleton in postmenopausal osteoporosis.

Parathyroid hormone, injected daily in low dosage, exerted anabolic effects on the human skeleton, just as it does in the rat. Four postmenopausal women with primary osteoporosis were treated for six months with a synthetic fragment of human parathyroid hormone (hP.T.H. 1-34), given as a daily injection of 100 mug. This treatment caused a remarkable acceleration of bone turnover, indicated both by isotopic tracer and histological methods. At this normocalcaemic dose level, the increases in bone formation outweighed increases in resorption. Three of the four patients showed more positive calcium balances, and mean increases in calcium and phosphorus balances were statistically significant for the group as a whole, the changes being principally due to increased intestinal absorption of both elements. Many modifications of the present method of hormone administration are possible which could further increase the preponderance of anabolic effects. These results suggest that low doses of hP.T.H. 1-34, alone or in combination with other agents, may prove useful in the treatment of osteoporosis.

Total body and serum potassium during prolonged thiazide therapy for essential hypertension.

Serum-potassium and total body potassium (T.B.K.) were measured serially for 1 year in a group of eighteen patients with mild essential hypertension. The patients were receiving a single daily dose of 10 mg. bendrofluazide without potassium supplements. At 12 months the mean value for serum-potassium (3-86 mmol per litre) was significantly lower than the mean pre-treatment value (4-26 mmol per litre). There was no significant decrease in T.B.K. in the same period. Diastolic blood-pressure fell significantly, and there were no apparent side-effects from the medication. In the group as a whole, a reduction of about 1 mmol per litre in serum-potassium was associated with an average reduction of 10% in T.B.K., but there was a large individual variation. The amount of potassium loss during the period of study did not seem to be clinically significant. It is suggested that routine potassium supplements are not essential in the treatment of uncomplicated essential hypertension with thiazide diuretics.