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Biomedical subjects

H R Powell

Publications and source records attributed to H R Powell.

50 records · Page 3Linked to original sources
PubMed1987

Urinary nitrite in symptomatic and asymptomatic urinary infection.

The dipstrip test for urinary nitrite is fairly unreliable in symptomatic urinary infections and only 104 (52%) of 200 symptomatic children with urinary infection attending an emergency department had a positive result. The test yielded positive results, however, in 83 of 100 outpatients with largely asymptomatic urinary infection attending a follow up clinic because of known predisposition to urinary infection. This difference was highly significant. The finding of urinary nitrite is highly specific for urinary infection and only 1% of 300 uninfected urine specimens gave a positive result. After addition of a broth culture of Escherichia coli to sterile urine incubation at 37 degrees C for four to six hours was required before the nitrite test yielded positive results. This suggests that frequency of micturition in urinary infection reduces the reliability of the nitrite test. On the other hand, the use of overnight, first morning urine specimens may further improve the sensitivity. If nitrite testing is used for screening for urinary infection at home, however, patients should be warned not to rely on a negative result in the presence of symptoms of urinary infection.

Adolescent↗
PubMed1987

Low red cell arachidonic acid in hemolytic uremic syndrome.

A defect in prostacyclin generation has been proposed in hemolytic uremic syndrome (HUS): prostacyclin is formed from arachidonic acid derived from phospholipid and low levels of some phospholipids have been described in HUS cell membranes. Therefore fatty acid content of the red blood cell membranes of 8 children with HUS was compared with 32 children with other renal disease, with 33 patients with non-renal disease and with 8 normal adults. Children with HUS consistently had lower proportions of arachidonic acid (2.7-8.4%) than all other groups (10.1-18.8%) and the mean arachidonic acid level in HUS was very significantly reduced (p less than 0.0001). These findings suggest a reduced availability of arachidonic acid for prostaglandin synthesis in HUS and are consistent with the proposition that arachidonic acid is lost through peroxidative change.

Adolescent↗
PubMed1984

Vitamin E treatment of haemolytic uraemic syndrome.

Because low plasma vitamin E concentrations have been reported in patients with haemolytic uraemic syndrome and there is accumulating evidence of lipid peroxidation in this disease, treatment with the antioxidant vitamin E was undertaken in 16 consecutive children with the syndrome. Twelve children had features at presentation suggesting a poor prognosis for recovery but despite this all 16 patients survived and are well three months later. Fifteen children now have normal values for serum creatinine, blood pressure, and urinalysis for protein but one has slight renal impairment. Although this is not a report of a controlled trial, it seems that patients treated with vitamin E have fared considerably better than our previously treated patients with haemolytic uraemic syndrome, even in the presence of early, adverse prognostic features. We suggest that vitamin E alters the natural history of the disease, and in view of the absence of any observed side effects further experience with this treatment is being sought.

Child↗
PubMed1980

Response to frusemide in acute renal failure: dissociation of renin and diuretic responses.

Eight hypertensive children with acute post-streptococcal glomerulonephritis were given intravenous frusemide, 2 mg/kg, and the results compared with 8 similar cases not given the diuretic. Mean urine flow increased from 0.24 ml/min/m2 before frusemide to 3.63 ml/min/m2 in the 6 hours afterwards and was still 0.72 ml/min/m2 48 hours later. In contrast mean urine flow remained unchanged over 48 hours in those not given frusemide. Despite similar initial blood pressures the duration of hypertension was much shorter (mean 4.7 days) after frusemide than in the controls (mean 11.0 days) and the edema-free weight was achieved more rapidly (6.8 days compared with 13.9 days). Plasma renin activity (PRA) did not rise after frusemide in the children with acute nephritis. This was in contrast to the rapid rise seen in normal humans thus indicating a dissociation between the diuretic and renin-releasing activities of frusemide in acute nephritis. Seven children with the hemolytic-uremic syndrome or acute tubular necrosis showed no significant change in either urine flow or PRA after frusemide. Frusemide is therefore effective treatment for both hypertension and oliguria in acute nephritis. Failure of PRA to rise indicates that renin release mechanisms are abnormal in renal failure and that PRA levels need to be interpreted with caution in this condition.

Acute Kidney Injury↗
PubMed1978

Renin release by parathyroid hormone in the dog.

Synthetic N-terminal 34 amino acid peptide of bovine parathyroid hormone (PTH) produced a consistent rise in plasma renin activity in saline-loaded dogs when given iv either as a single bolus dose of 400 U or infused steadily in lower dosage over a number of hours. Infusion of as little as 1 U/min produced a significant rise in plasma renin activity, but a greater effect was obtained with 2 U/min. Infusion of 4 U/min had no more effect than 2 U/min. In contrast to transient hypotension after rapid injection of a single large dose, blood pressure did not change significantly during the steady infusion of lower doses of PTH. These findings are compatible with the thesis that an increased distal tubular load of sodium stimulates renin release and suggest that the increased distal sodium absorption after the proximal effects of PTH may be regulated by the renin-angiotensin-aldosterone system.

Animals↗
PubMed1977

Nephropathy in cyanotic congenital heart disease.

Three children with cyanotic congenital heart disease who developed transient proteinuria and edema are described. One died of an intercurrent illness but the other two are now well. Renal biopsy findings in all three children demonstrated a mesangial proliferative glomerulonephritis on light microscopy. An unusual ultrastructural appearance of localized electron-dense thickening of the basement membrane of the capillary loops was seen in all three and collagen fibers were present in the mesangium of two. There was slight fusion of foot processes in two specimens and marked fusion in the third. Immunofluorescence in two patients demonstrated IgM staining in both and fibrin in one. The cause of the glomerular lesions is unknown but, among the many possible factors involved, anoxia and increased venous pressure may be important.

Child, Preschool↗
PubMed1976

Diphosphonate therapy in nephrocalcinosis.

4 patients with nephrocalcinosis were treated with disodium ethane 1-hydroxy-1, 1-diphosphonate (EHDP) for a period of 13 months. No clinical side-effects were observed and growth proceeded normally. Radiographic changes of osteitis fibrosa cystica developed in 1 child and bone biopsy in 2 children showed defective osteoid mineralisation. It is suggested that EHDP prevented further crystal deposition in 3 children but did not prevent non-calcium stone formation in the 4th child. In view of this and the development of histological and radiographic evidence of osteomalacia and/or secondary hyperparathyroidism in these patients the value of EHDP remains dubious. On the other hand its use may be justified when rapidly increasing calcification is expected, as for example in hyperoxaluria.

Bartter Syndrome↗
PubMed1976

Relationship between proteinuria and epithelial cell changes in minimal lesion glomerulopathy.

The degree of fusion of glomerular epithelial cell foot processes was quantitated by determining the mean number of inter-process slip pores along 10 mum of basement membrane of peripheral capillary walls in 45 children with steroid-responsive nephrotic syndrome and minimal lesion glomerulopathy. Fusion was present in all biopsies performed when the child had proteinuria, but after remission the number of slit pores increased progressively towards normal over the next 4 weeks. There was a close correlation between the degree of fusion and the amount of proteinuria in those biopsied before remission.

Adolescent↗
PubMed1976

Trends in freeze-drying equipment and materials.

The above discussion outlines some trends seen in the development of equipment for freeze-drying of various biological-like products. It has been pointed out that many similarities in equipment now exist. There are still areas in which a consensus on best design has not been reached and in these areas the user is offered some clear choices. Various changes have been introduced in recent years into freeze-drying equipment principally in an effort to increase reliability and improve the quality of the product produced. It is probable as more products are freeze-dried (and particularly as these products become more cost-sensitive) that manufacturers will also require that greater performance-capability be built into their equipment. This may perhaps translate into requirements for carrying high peak-vapor-rates and for automatic control in an effort to reduce drying cycles and increase throughput in a given machine.

Biological Products↗
PubMed1975

Effect of parathyroid extract on renin release in the dog.

1. A rapid increase in plasma renin activity occurred in dogs after intravenous administration of parathyroid extract. 2. This was not seen after injection of a purer parathormone preparation, or the solution used to dilute the parathyroid extract or calcitonin. 3. A vasoactive compound in parathyroid extract appears to provide the most likely explantation of this effect.

Animals↗