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Biomedical subjects

J P Merrill

Publications and source records attributed to J P Merrill.

At least 37 records · Page 2Linked to original sources
PubMed1978

Dialysis versus transplantation in the treatment of end-stage renal disease.

Both dialysis and kidney transplantation are effective techniques for prolonging life in ESRD. Because dialysis therapy does not effect replacement of the metabolic functions of the kidney, it is less tha perfect. Successful transplantation that replaces all of the aspects of renal function is the treatment of choice. Successful transplantation is highly dependent upon the availability of a suitable donor and the appropriate tissue match, which remains a problem. Present immunosuppressive therapy required to prevent the immunoresponse causing rejection of the renal allograft is a tool too dull for the job. Since all immunoresponse is suppressed, infections are common, as are the multiple complications of cortical steroid therapy. For the dialysis patient, development of more compact effective dialysis apparatus and particularly the availability of replacement therapy hold promise. New approaches to diminishing the immune response to the graft without impairing that to microorganisms may well effect improvement in graft survival as will increasing knowledge of factors other than HLA antigens in the immunologic reaction. Development of an effective method for arresting the progress of glomerulonephritis before it reaches end-stage renal failure would obviate the necessity for dialysis or transplant therapy in appoximately two thirds of ESRD patients.

Anemia↗
PubMed1978

A longitudinal study of bone disease after successful renal transplantation.

A retrospective study of 100 patients followed for 1-4 years after successful renal transplantation was undertaken to assess the amelioration of previously present metabolic bone disease and to determine the risk factors associated with the development of osteonecrosis. 42% of patients showed some evidence of bony abnormality. Following transplantation, there was slow but progressive resolution in the X-ray changes of hyperparathyroidism but not of osteoporosis. 14% of patients developed osteonecrosis in the posttransplant period with the femoral head the most common site involved (72% of patients). Osteonecrosis could not be related to average steroid dose, number of steroid pulses, or the preexistence of metabolic bone disease.

Adult↗
PubMed1977

Controlled ultrafiltration (UF) with hemodialysis (HD): analysis of coupling between convective and diffusive mass transfer in a new HD-UF system.

A convertible and versatile dialysis system consisting of a PMMA hollow fiber unit and UFR controller is shown to be useful for evaluating the effect of solute and fluid removal rates on adequacy of dialysis. Post-dilution mode where high UFR is applied to the patient with matching or comparable dilution rate is concluded to be most effective modification for enhancing the clearance for "middle molecules", without sacrificing the removal rates for the small solutes.

Creatinine↗
PubMed1976

Factors in the dialysis regimen which contribute to alterations in the abnormalities of uremia.

While hemodialysis therapy in its present form is capable of sustaining life, dialysis patients are not metabolically normal and we are unable to say what technical factors contribute adequate therapy. Recent efforts to resolve these problems have led to the assumption that substances in the molecular weight range of 800 to 3000 daltons may be pathogenic in uremia and these may not be effectively removed by dialysis. Accordingly, four groups of patients (ten each) underwent changes in their routine which were theoretically designed to alter independently the concentration of small (urea) and "middle" molecules in the blood. In two groups, the concentration of urea was theoretically increased or decreased while the concentration of so-called middle molecules was maintained unchanged. In the remaining two groups, middle molecule concentration was theoretically increased or decreased while small molecule concentration was unchanged. Patients were evaluated prior to and after completing altered dialysis therapy. The results suggest three related conclusions. First, the uremic syndrome may be viewed as a constellation of abnormalities which can be subgrouped by association so that azotemia may be correlated with neuropathic disease and hypertension with weight gain or body size, for example. Second, those physiologic variables which changed after altered dialysis tended to deteriorate with increasing concentration of small molecules in the blood and remained independent of theoretical changes in middle molecules. Finally, when patients are relatively under-dialyzed, they may spontaneously modulate the reduced removal of metabolites such as urea by decreasing the dietary intake of nutrients.

Adult↗
PubMed1976

Secondary hyperparathyroidism in human kidney transplant recipients.

76 kidney transplant recipients who were up to 4 years post transplant, were studied to assess the incidence of secondary hyperparathyroidism. All patients had good renal function with a mean serum creatinine of 1.4 mg/100 ml. Secondary hyperparathyroidism, as evidenced by increased serum parathyroid hormone levels, was present in 53 of the 76 patients (66%) and radiologic bone disease in 26 of the 76 patients (34%), while hypercalcemia (serum calcium greater than 11.0 mg/100 ml) occurred in only 6 patients (8.5%). The incidence of secondary hyperparathyroidism decreased slightly with time following transplantation, but the degree of secondary hyperparathyroidism as indicated by the levels of serum parathyroid hormone at various times following renal transplantation was essentially similar. The causes for the persistence of this condition are not totally known, but it was found that its incidence was related to the duration of dialysis prior to transplantation.

Follow-Up Studies↗
PubMed1975

Renal vascular tone in essential and secondary hypertension: hemodynamic and angiographic responses to vasodilators.

The renal vascular response to graded doses of acetylcholine, dopamine and phentolamine, assessed by xenon washout and selective arteriography was used to define the relative contribution of fixed and reversible vascular abnormalities to increased renal vascular resistance in patients with essential or secondary hypertension. The increase in blood flow induced by acetylcholine and dopamine was blunted strikingly in patients with advanced nephrosclerosis, chronic pyelonephritis and polycystic kidney disease and was normal in the kidney contralateral to a significant renal artery stenosis. Conversely, the response to both was potentiated in 9 of 13 (69%) patients with mild essential hypertension. Equivalent potentiation of the response to acetylcholine was induced in normal subjects by increasing renal vascular tone pharmacologically with angiotensin. Phentolamine infused into the renal artery also increased renal blood flow significantly in 6 of 9 (67%) patients with mild essential hypertension, but in none of 15 normal subjects, over a dose reange that paralleled that for alpha-adrenergic blockade. Changes in the selective renal arteriogram were in excellent accord: potentiated response to acetylcholine, phentolamine or dopamine was associated with reversal of the small vessel abnormalities visualized in the arteriogram. The reduced blood flow response in advanced nephrosclerosis or parenchymal disease was associated with a reduced angiographic change during dilator infusion. The results suggest a quantitatively important, functional renal vascular abnormality--perhaps mediated by the sympathetic nervous system--in many patients with mild essential hypertension. Conversely the renal vascular abnormality associated with advanced nephrosclerosis or renal parenchymal disease is largely fixed and is probably due to organic changes.

Acetylcholine↗
PubMed1975

Hemorrhagic pleural effusion in patients undergoing chronic hemodialysis.

Three patients maintained on chronic hemodialysis developed hemorrhagic pleural effusion. The effusions seemed to be solely related to the uremic state, other causes having been excluded. Pulmonary restriction requiring decortication occurred in one patient. We concluded that hemorrhagic pleural effusion may be a complication of uremia in the chronically dialyzed patient and that fibrous pleuritis causing pulmonary restriction may result.

Adult↗