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Biomedical subjects

J F Moorhead

Publications and source records attributed to J F Moorhead.

At least 55 records · Page 3Linked to original sources
PubMed1993

Calcium set point progressively worsens in hemodialysis patients despite conventional oral 1-alpha hydroxycholecalciferol supplementation.

Calcium set point was measured in 12 patients on chronic hemodialysis. Dialysate calcium concentration was 1.65 mmol/l. Calcium carbonate (CaCO3) was used as the phosphate binder and oral 1-alpha hydroxycholecalciferol (alfacalcidol) was administered in a dose of 0.25-1.0 micrograms/day for 12 months. Comparing base line and post study values, there were no significant changes in ionized calcium (ICa++), intact immunoreactive parathyroid hormone (iPTH), plasma total calcium (TCa++), plasma phosphate (P), alkaline phosphatase (ALP), or aluminum (Al). However, the relative calcium set point significantly worsened (shifted to the right). Three patients developed hypercalcemia (25%) with a total calcium > 2.65 mmol/l. Total bone mineral content (BMC) fell suggesting demineralization. We conclude that this dose of oral alfacalcidol, CaCO3, and a dialysate calcium concentration of 1.65 mmol/l are not sufficient to halt the progression of secondary hyperparathyroidism in chronic hemodialysis patients. Measurement of calcium set point may be the best early measure of failure to prevent worsening of hyperparathyroidism.

Administration, Oral↗
PubMed1992

Lipoprotein(a) in patients with proteinuria.

Lipoprotein(a) (Lp(a)) has recently been recognized to be a risk factor for coronary heart disease. Lp(a) median values in the absence of renal disease are around 10 mg/dl. Higher levels (greater than or equal to 30 mg/dl) correlate with the occurrence of coronary heart disease, particularly in the presence of elevated cholesterol. We have studied Lp(a) in 76 adults with proteinuria. Fifty had glomerular diseases and 26 non-glomerular diseases, with renal function varying from normal to advanced chronic renal failure. Lp(a) values were shifted to the right, with a median of 21.0 mg/dl, and 25% of patients had values of 30 mg/dl or more. Lp(a) did not correlate with cholesterol, age, lipoprotein subclasses, apoproteins A-I or B-100, albumin, creatinine, or creatinine clearance. Median Lp(a) values did not differ significantly comparing men versus women, or glomerular versus non-glomerular disease. Lp(a) may inhibit fibrinolysis, and is deposited in atherosclerotic lesions. Although the cause of these elevated Lp(a) levels is uncertain, we propose that they contribute to the increased risk of coronary heart disease in the nephrotic syndrome, and may play a role in progressive renal disease.

Adolescent↗
PubMed1992

Screening for renovascular disease with captopril-enhanced renography.

Changes in renal function caused by angiotensin-converting-enzyme (ACE) inhibitors can be detected on 99mTc-DTPA renography so that DTPA scanning before and after a single dose of captopril can be used to screen for renovascular disease. We have performed captopril-DTPA scans with renal arteriography on 104 patients, of whom 27 had renal artery stenosis, all due to atheroma. Using a 5% fall in divided function or a delay of greater than 15 min in time to peak activity on one side after captopril, or the finding of greater than 90% divided function on one side before captopril as criteria for a positive scan, a sensitivity of 93% and specificity of 70% was achieved. The negative predictive value of the test in our population was 93%. Bilateral improvement in renographic function after captopril was seen in patients with accelerated phase hypertension. The presence of bilateral renal artery disease did not reduce the sensitivity of the test, but sensitivity was reduced (75%) in patients with renal impairment. Clinical characteristics in our patients most strongly associated with renal artery stenosis were abdominal bruit, recurrent left ventricular failure, and peripheral vascular disease. In view of the well-publicized risks of ACE inhibitor therapy, care should be exercised in the use of these agents in such patients.

Adult↗
PubMed1992

Effect of 24,25-dihydroxycholecalciferol on intestinal absorption of calcium and phosphate and on parathyroid hormone secretion in chronic renal failure.

Twelve patients with chronic renal failure (CRF) requiring dialysis, 7 of whom were hypercalcaemic, were treated with 24,25-dihydroxycholecalciferol [24,25(OH)2D3; 10 micrograms daily for 3 months] or placebo and the treatment then crossed over for a further 3 months. Treatment with 24,25(OH)2D3 was associated with small but significant increments in the fractional rates of absorption of calcium (p less than 0.01) and phosphate (p less than 0.05) measured by a combined radioisotope test, but even during treatment, the absorption of both calcium and phosphate remained subnormal. A significant fall in immunoreactive parathyroid hormone (i-PTH) levels occurred during treatment (p less than 0.05) in the absence of significant changes in plasma ionised calcium and plasma phosphate levels. In 7 patients, treatment with 24,25(OH)2D3 converted parathyroid glands which were non-suppressible by calcium infusion before treatment to suppressible ones (greater than 50% suppression of i-PTH levels) at similar levels of ionised calcium. 24,25(OH)2D3 may have a role in the treatment of renal osteodystrophy, especially in patients with hypercalcaemic hyperparathyroidism.

Adult↗
PubMed1992

Determining medical necessity of outpatient physical therapy services.

A patient referred for physical therapy may attend one or several therapy visits or may continue to receive ongoing therapy services several times weekly for several months. The question of the continued medical necessity of those services arises often. Determination of medical necessity for continued therapy services requires knowledge of the natural history of diseases that may require therapy services, familiarity with the effectiveness of treatment alternatives for those diseases, and awareness of community practice patterns. Accurate and complete documentation from the therapist or referring physician is required for the physician advisor or utilization review consultant to make an accurate determination of medical necessity. A structured format for providing this documentation is suggested.

Adult↗
PubMed1991

Can urinary thyroid hormone loss cause hypothyroidism?

Four patients presented with nephrotic syndrome associated with hypothyroidism; none had thyroid antibodies. Hypothyroidism resolved on remission of nephrotic syndrome in two patients; thyroxine (T4) replacement was ineffective during periods of gross proteinuria in another, and the fourth had had normal thyroid function a year before presentation. Urinary T4 excretion was measured in ten further patients with proteinuria. It was detectable in the urine in five, who had significantly lower serum free T4 (8.5 [95% confidence interval 5.8-11.2] vs 13.9 [11.1-16.7] pmol/l; p less than 0.01) and free triiodothyronine (3.1 [2.2-4.0] vs 4.9 [3.8-6.0] pmol/l; p less than 0.01) concentrations than the five patients without detectable urinary T4.

Aged↗
PubMed1991

Effects of dietary fatty acids in an animal model of focal glomerulosclerosis.

The obese Zucker rat develops hyperlipidemia, proteinuria and focal glomerulosclerosis without prior changes in renal hemodynamics. To study the effects of oral fatty acid intake on the development of renal injury in this model, rats were fed standard chow or chow supplemented with either 14% fish oil or 14% beef tallow after unilateral nephrectomy at the age of 10 weeks. At 32 weeks post-nephrectomy animals were sacrificed and renal tissue saved to assess histology and glomerular eicosanoid production. Fish-oil treated rats had lower mean plasma cholesterol levels and developed less proteinuria than control or tallow-fed animals although there was no difference in plasma creatinine or blood pressure. Histological analysis showed significantly fewer sclerosed glomeruli in the fish oil group (4.0 +/- 0.8% vs. control 19.4 +/- 4.1%, P less than 0.0005 and vs. beef tallow 10.8 +/- 1.9%, P less than 0.005). Glomeruli derived from rats on fish oil supplements produced smaller amounts of prostaglandin (PG)E2 and of the stable metabolites of PGI2 (6-oxo-PGF1 alpha), PGF2 (PGF2 alpha) and thromboxane (TX)A2 (TXB2) than those from tallow-fed animals. This study demonstrates that oral fatty acid intake may influence the development of glomerulosclerosis. The apparent beneficial effects of fish oil have not been fully defined, but may relate to favorable changes in plasma lipid concentration and renal eicosanoid production.

Animals↗
PubMed1991

Characterisation of the binding of low-density lipoproteins to cultured rat mesangial cells.

Mesangial cell lipid accumulation is a recognised feature of glomerular disease and has been implicated as a factor in the pathogenesis of renal injury. To investigate possible mechanisms of such accumulation, binding of 125I-labelled human low-density lipoprotein (LDL) to rat mesangial cells was studied in vitro. Experiments were performed at 4 degrees C to prevent ligand internalisation. LDL remained associated with the cells after repeated washing. Binding was time-dependent, was inhibited by addition of an excess of unlabelled LDL, but to a much lesser extent by apoprotein-A-rich high-density lipoprotein particles devoid of apoprotein E (HDL-A). Specific binding reached saturation at an LDL concentration of 21 micrograms/ml, required the presence of calcium, and was inhibited by heparin and dextran sulphate. Scatchard analysis suggested a single class of binding site (Kd 22.7 micrograms protein/ml). Higher binding affinities were obtained when rat LDL was substituted for human LDL (Kd 1.3 micrograms/ml) and when human fibroblasts were exposed to human LDL under identical experimental conditions (Kd 3.0 micrograms/ml). Further experiments at 37 degrees C demonstrated degradation of LDL by cells. These results suggest that mesangial cells possess apoprotein B, E receptors. Mesangial cell lipid accumulation may therefore result from receptor-mediated endocytosis of LDL particles.

Animals↗
PubMed1991

Plasma histamine in patients with chronic renal failure and nephrotic syndrome.

Plasma histamine concentrations were measured using a commercially available monoclonal antibody radioimmunoassay in 38 patients with nephrotic syndrome, end stage renal failure, those receiving haemodialysis, and those receiving continuous ambulatory peritoneal dialysis to determine whether histamine may mediate damage to glomerular capillaries and arterial endothelium. Plasma histamine concentrations were significantly increased in all four patient groups when compared with those of controls and were the highest in two patients with pruritus. Raised plasma histamine concentrations in such patients are consistent with the hypothesis that histamine may contribute to the damage to glomerular capillaries and to arterial endothelium. These effects may be relevant to the pathogenesis of glomerular disease and atherosclerosis. Histamine may also contribute to the pathogenesis of pruritus in patients with chronic renal failure.

Adolescent↗
PubMed1991

Lipids and progressive kidney disease.

The nephrotic syndrome comprises proteinuria, oedema, albuminuria, hypoalbuminaemia, and hyperlipidaemia. Some of its manifestations are present throughout the course of progressive renal disease. Hyperlipidaemia is one of the most dramatic of the clinical manifestations of the syndrome, but has not been seen as relevant to the progression of renal disease. Recently, however, increasing interest has been shown in the lipid abnormalities of patients with persistent proteinuria, largely as a result of experimental data which have emphasised the connection between progressive disease and hyperlipidaemia in animal models. This review considers some aspects of the metabolic background against which the pathological changes in animal models of nephrotic syndrome take place. Attention is drawn to analogies between glomerular disease and atherosclerosis. Lack of information on the value of long-term lipid lowering therapy in patients with proteinuria, hyperlipidaemia, and progressive renal disease emphasises the need for long-term studies of lipid-lowering therapy in these individuals. A conceptual framework for understanding the role of lipids is discussed in relation to the underlying disease processes and possible therapeutic approaches in man.

Animals↗
PubMed1990

Conversion of stable renal allografts at one year from cyclosporin A to azathioprine: a randomized controlled study.

Seventy-seven stable, nondiabetic, cadaveric renal transplants were randomized at 1 year to convert from cyclosporin A to azathioprine or to continue on cyclosporin A. Prednisolone was increased twofold during the period of conversion, and there was a 3-week overlap period during which azathioprine and cyclosporin A were given. No grafts were lost due to rejection related to conversion, but 9 of the 33 patients who were randomized to convert experienced rejection episodes and 6 were returned to cyclosporin A. Conversion to azathioprine resulted in a drop in creatinine and improvement in blood pressure control. In the group randomized to stay on cyclosporin A, 6 patients had to be subsequently converted to azathioprine because of cyclosporin A toxicity in spite of well-controlled plasma levels. The creatinine levels after successful conversion remained stable whereas those of the patients continuing on cyclosporin A showed a progressive decline. We conclude that conversion from cyclosporin A to azathioprine can be achieved safely. Progressive deterioration in graft function with continuing cyclosporin A therapy does occur and should be taken as an indication for conversion.

Adult↗
PubMed1990

Effects of low-density lipoproteins on mesangial cell growth and viability in vitro.

Recent animal studies suggest that abnormal lipid metabolism may play a role in the pathogenesis of glomerulosclerosis. In order to define mechanisms whereby lipoproteins could contribute to glomerular injury, the effect of Low-density lipoprotein (LDL) concentration on the proliferation of rat mesangial cells was studied in vitro. Human LDL was added to culture medium that had been rendered otherwise lipid free and proliferation rate was estimated by measuring incorporation of 3H-thymidine. When compared to standard medium, LDL-enriched medium stimulated cell division when present in protein concentrations of between 10 and 100 micrograms/ml. At greater concentrations (more than 200 micrograms/ml), cell proliferation was inhibited and above 500 micrograms/ml cells sustained visible morphological injury when assessed under phase contrast microscopy. Estimation of 51Cr release from prelabelled cells confirmed that LDL was cytotoxic in these greater concentrations. A similar pattern of proliferation and toxicity has been observed in vascular smooth muscle cell cultures over a corresponding range of LDL concentrations. These results strengthen the analogy between glomerulosclerosis and atherosclerosis and provide further evidence that lipoproteins may contribute directly to glomerular scarring.

Animals↗
PubMed1990

Cyclosporin-induced renal magnesium leak in renal transplant patients.

Renal transplant patients (n = 116) attending an outpatients clinic were screened for hypomagnesaemia. No azathioprine-treated patients (n = 46) but 24% (17 of 70) of the cyclosporin treated patients were hypomagnesaemic. The hypomagnesaemia in all cases was associated with a renal magnesium leak. This leak did not correlate with plasma bicarbonate, urate, calcium, cyclosporin or creatinine concentrations, nor did it correlate with the use of loop diuretics or duration of the transplant. A renal magnesium leak is common in renal transplant patients treated with cyclosporin and it is independent of other markers of nephrotoxicity.

Adult↗