Monitoring the function of renal transplants

Chronobiology in hematology and immunology

The hematopoietic and the immune systems in all their components are characterized by a multifrequency time structure with prominent rhythms in cell proliferation and cell function in the circadian, infradian, and rhythms in cell proliferation and cell function in the circadian, infradian, and circannual frequency ranges. The circulating formed elements in the peripheral blood show highly reproducible circadian rhythms. The timing and the extent of these rhythms were established in a clinically healthy human population and are shown as chronograms, cosinor summaries and, for some high-amplitude rhythms, as time-qualified reference ranges (chronodesms). Not only the number but also the reactivity of circulating blood cells varies predictably as a function of time as shown for the circadian rhythm in responsiveness of human and murine lymphocytes in vitro to lectin mitogens (phytohemagglutinin and pokeweed mitogen). Some circadian rhythms of hematologic functions appear to be innate and are presumably genetically determined but are modulated and adjusted in their timing by environmental factors, so-called synchronizers. Phase alterations in the circadian rhythms of hematologic parameters of human subjects and of mice by manipulation of the activity-rest or light-dark schedule and/or of the time of food uptake are presented. Characteristically these functions do not change their timing immediately after a shift in synchronizer phase but adapt over several and in some instances over many transient cycles. The circadian rhythm of cell proliferation in the mammalian bone marrow and lymphoid system as shown in mice in vivo and in vitro may lend itself to timed treatment with cell-cycle-specific and nonspecific agents in an attempt to maximize the desired and to minimize the undesired treatment effects upon the marrow. Differences in response, and susceptibility of cells and tissues at different stages of their circadian and circaseptan (about 7-day) rhythms and presumably of cyclic variations in other frequencies are expected to lead to the development of a chronopharmacology of the hematopoietic and immune system. Infradian rhythms of several frequencies have been described for numerous hematologic and immune functions. Some of these, i.e., in the circaseptan frequency range, seem to be of importance for humoral and for cell mediated immune functions including allograft rejection. Infradian rhythms with periods of 19 to 22 days seem to occur in some hematologic functions and are very prominent in cyclic neutropenia and (with shorter periods) in its animal model, the grey collie syndrome.(ABSTRACT TRUNCATED AT 400 WORDS)

Computing, mathematics, and the nephrologist

The potential of computing and mathematics to make major contributions to nephrology by making information retrieval and presentation more accurate, more complete, and more rapid and by providing immediate access to computational and graphic facilities is emphasized in this symposium issue. The realization that disordered physiology due to disease may not prevent the course of an illness being described in mathematical terms should encourage physicians, and others interested in pathophysiology, to integrate mathematics and statistics into their thinking and their practice.

Mathematical and statistical aids to evaluate data from renal patients

The monitoring of renal patients and the making of many decisions during their management involves consideration of sequences of numerical data. Renal function results after renal transplantation were used as an example of how graphical presentations, simple mathematical transforms, statistical evaluation and adjustments to the data, to take into account other biological and technical sources of error, can all contribute to better understanding. Experience with a statistical technique, the 4-state Kalman filter not often used in the biological sciences, was summarized and its use suggested as a method to quantitate some traditionally subjective decisions about individual patients, for example, the onset of allograft rejection. The method has identified in retrospect and in prospect events after transplantation earlier than did experienced clinicians. Other statistical techniques to set the sensitivity and specificity of monitoring methods, to detect change points and to quantitate rhythmic sequences of clinical data were discussed, with examples, and with increasing access to computers, these can be used more easily by nephrologists, transplant surgeons, and others.

Predictors of renal function in diabetic and non-diabetic renal disease

Forty-two patients with renal disease due to diabetic nephropathy (14 patients), tubulointerstitial disease (14 patients) and glomerular disease (14 patients) underwent measurement of glomerular filtration rate (GFR) by the 51Cr-EDTA 'one-shot' method and simultaneous serum beta 2-microglobulin, serum creatinine and creatinine clearance estimation. Serum creatinine was a significantly better predictor of GFR than serum beta 2-microglobulin in patients with diabetic nephropathy, whereas both methods were equally useful predictors of GFR in non-diabetic renal disease. Serum creatinine measurement remains the best method for detecting early reduction of GFR on a serum sample.

Time of day of taking immunosuppressive agents after renal transplantation: a possible influence on graft survival

Large-amplitude circadian rhythms in immune responses and the known variations in the effects of glucocorticoids with the time of day of administration suggest that immunosuppressive regimens may need to take this variable into account. In two similar groups of patients with renal transplants functioning satisfactorily after three months subsequent graft failure developed in 66% of those taking all immunosuppressives in the evening, compared with only 22% of those taking immunosuppressives twice daily (p < 0.05). A survey of other transplant units showed that one unit with outstanding results--graft survival at three years 82%--had a unique policy of morning-only administration of immunosuppressives. Doctors need to consider more carefully the time of drug administration when prescribing, as it may be possible to obtain better results with less toxicity.