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Biomedical subjects

J P Merrill

Publications and source records attributed to J P Merrill.

At least 55 records · Page 3Linked to original sources
PubMed1975

Recommendations for evaluation of the cardiovascular response of dialysis patients.

The minimum parameters, which I have stressed in the first section, should be measured at least once a week, as should the chest films, the films of the vessels and so on, plus the chemistries, probably when determined by the investigator. If we are going to compare program to program, these intervals should, of course, be synchronized. The more sophisticated parameters, which I have mentioned, should be measured perhaps only when specific areas are to be investigated because the number of things which we think need to be measured is, indeed, enormous for any one laboratory. Now, if such studies are to be carried out by a number of investigators, the standard form mentioned should be instituted and yearly meetings of such groups should be held to compare notes, and particularly the adequacy of the data obtained and the method of obtaining it. Initially perhaps, after the program is underway, if enough groups are actively involved, the first meeting probably should be held six months after the beginning of the evaluation. I realize what we have put forth here is ambitious. I think it is probably wise to put in as many things as possible which might be important, and then with a little rethinking time, obviously some of these things can be eliminated. To my knowledge, we have covered almost everything that needs to be covered, and what we need to do now, perhaps, is to thin this out a little bit with discussion and consultation.

Carbohydrate Metabolism↗
PubMed1975

Immunologic enhancement of rat renal allografts. III. Immunopathologic lesions and rejection in long-surviving passively enhanced grafts.

Immunologic enhancement of renal allografts from (Lewis times Brown Norway) F1 to Lewis rats was achieved by administering a single dose of antidonor serum at the time of transplantation. A series of grafts functioning for 1 to 4 months after transplantation were examined by light and immunofluorescence microscopy to evaluate the long-term protective effects of the enhancing serum and to determine if previously unobserved lesions appeared in long survivors. Despite the absence of detectable circulating cytotoxic alloantibody, long-term allografts showed necrotizing glomerular and arterial lesions which resembled those seen in acutely rejecting grafts and were compatible with humoral rejection. Thus, in this model, there is a late decline in the ability of passive enhancement to inhibit humoral rejection. Long-term grafts also developed tubular lesions with deposition of immunoglobulin and complement on the tubular basement membranes (TBM). Anti-TBM antibodies were demonstrated in recipients' sera and found to be organ specific but not major histocompatibility antigen or species specific. This tubular lesion is therefore a unique form of allograft injury in which the immune response is directed against tissue antigen(s) which are distinct from the major histocompatibility antigens that induce rejection.

Animals↗
PubMed1975

Cardiovascular disease in uremic patients on hemodialysis.

In conclusion, patients on chronic maintenance dialysis have an increased incidence of death from cardiovascular disease. Hypertension plays a major role, and these patients must be carefully monitored for complete control of blood pressure. Adequacy of ultrafiltration to maintain normal extracellular volume is an essential part of the dialytic treatment. Hypertensive patients should be screened for excessive renin secretion because of its possible role in unresponsive hypertension in patients on dialysis. Nephrectomy should be used when necessary, where dialysis and antihypertensive medication have not adequately controlled blood pressure. Patients must be monitored for the presence of pericardial disease to avoid subsequent pericardial effusion and the development of constrictive pericarditis with its adverse effect on myocardial function. When constrictive pericarditis is present, it obviously should be relieved by appropriate surgery. Efforts should be made to minimize cardiac output in hemodialysis patients. Whether or not routine transfusions to maintain a higher hematocrit are indicated is a question that cannot yet be answered. However, patients with marginal cardiovascular function who are accepted on hemodialysis and must have an arteriovenous shunt should be supported in any manner to minimize an increase in cardiac output. Early and aggressive treatment of known episodes of sepsis is important in the elimination of valvular endocarditis in this patient population. Perhaps one of the finer indicators of adequacy of hemodialysis will be K rate and peak immunoreactive insulin levels. Continued abnormality of these parameters may contribute to cardiovascular disease. Clearly, further study of the effect of abnormal carbohydrate metabolism on lipid metabolism is in order. Serum triglyceride, serum cholesterol and lipid electrophoretic pattern should be followed to evaluate the beneficial effects of drug therapy and changes in dialytic technique on the development of cardiovascular disease. Careful monitoring of calcium, phosphorus, bone films and parathyroid hormone levels is indicated to assess parathyroid status. The use of aluminum binders and parathyroidectomy to prevent vascular and myocardial calcification is important in the therapy of these patients. The use of cardiac catheterization, coronary artery arteriography, and possibly cardiac vascular repair, should be considered in the chronic hemodialysis patient with coronary artery disease if he is otherwise well. Adequacy of hemodialysis perhaps can be evaluated through its effect on all of the above parameters. Whether or not changes in artificial kidney treatments can correct the final vascular disease remains to be seen.

Antigens↗
PubMed1975

The effects of varying dialysis regimens on lymphocyte stimulation.

A protocol was designed to alter mean time average serum concentrations of "middle" (B12) and "small" (urea) molecules. Serum before and after studies was tested for its effect on the blastogenic response to PHA. From this study we have concluded that: 1. Serum of patients on hemodialysis inhibits the mitogenic response of normal lymphocytes to PHA when compared to normal sera. 2. This phenomenon is not responsive to pertubations in dialysis designed to alter the concentration of ""middle'' and ""small'' molecules. 3. The inverse correlation between PHA response and serum PO4 and likewise the inverse correlation with changes in bone X-rays suggest that PTH, fragments thereof, or other factors related to bone and calcium metabolism, could conceivably be involved. This could mediated via cyclic AMP.

Adult↗
PubMed1975

The influence of serum calcium and parathyroid hormone upon glucose metabolism in uremia.

The alterations in carbohydrate metabolism which attend the uremic syndrome have been recognized for some time. Recently, an interaction between hyperparathyroidism and these alterations in intermediary metabolism has been postulated. To further define any such interaction, 6 stable dialysis patients with significant secondary hyperparathyroidism were studied prior to and after subtotal parathyroidectomy. Glucose utilization and insulin secretion were estimated by use of a standard intravenous glucose tolerance test and the resistance of peripheral tissues to exogenous insulin was evaluated by insulin tolerance testing. All of peripheral tissues to exogenous insulin was evaluated by insulin tolerance testing. All patients were studied under baseline conditions, as well as induced hyper- and hypocalcemia, prior to and at least 2 months after surgery. Parathyroidectomy, per se, had no significant effect upon glucose utilization, insulin secretion, or the resistance of peripheral tissues to the action of exogenous insulin. Both induced hyper- and hypocalcemia, on the other hand, significantly diminished glucose utilization as judged by a reduced glucose disappearance rate during intravenous glucose tolerance testing. Hypocalcemia was associated with a markedly reduced insulin secretory response and normal tissue insulin sensitivity, while hypercalcemia was associated with a normal insulin response but reduced tissue sensitivity. The data suggest that calcium ion concentration may affect both glucose utilization and insulin secretion. As such, it must be adequately controlled in furture metabolic studies.

Adult↗
PubMed1975

Testosterone therapy in hemodialysis patients.

30 patients undergoing regular, three times weekly hemodialysis were treated with large doses of intramuscular testosterone with evaluation of hematopoiesis before and after treatment. A control group of 30 patients not using the drug was evaluated in similar fashion. The presence or absence of native kidneys was the most important factor determining hematocrit level and transfusion requirements in these patients, whether treated with testosterone or not. The mean hematocrit was lower and the transfusion requirements were higher in bilaterally nephrectomized patients. A significant increase in hematocrit occurred in testosterone treated nephric patients, but untreated nephric patients also had a significant rise. Important adverse side effects occurred with testosterone. Anephric patients did not increase hematocrit levels with or without testosterone.

Adult↗