Economics of an academic renal division: an approach

Nephrology divisions work within the systems and constraints of a department of medicine in a college of medicine, and in an increasing number of cases, also within a larger health care delivery system. Key to the division's stability are a consistently applied practice pan, how the tenure and clinical track systems function, how teaching funds are distributed, mechanisms of incentive for the division, and its faculty and the ability to establish and maintain reasonable financial reserves, especially for investment in research. Dialysis, transplantation, hypertension, research, and the teaching of medical students, residents, and fellows are the key elements the divisional organization must address. Incentives for faculty performance should be included in all of these areas. The division director must recognize his or her control of earning capacity in the distribution of responsibilities; financial returns as compared with effort involved vary considerably. Three main problems confront the future of our divisions: manpower shortages in nephrology; the effects of managed care systems on nephrology practice; and the future existence and success of departments of internal medicine and academic health centers.

Rewarding teaching faculty with a reimbursement plan

OBJECTIVE

To develop a system for measuring the teaching effort of medical school faculty and to implement a payment system that is based on it.

DESIGN

An interventional study with outcomes measured before and after the intervention.

SETTING

A department of internal medicine with a university hospital and an affiliated Veterans Administration hospital.

INTERVENTION

We assigned a value in teaching units to each teaching activity in proportion to the time expended by the faculty and the intensity of their effort. We then calculated total teaching units for each faculty member in the Division of General Internal Medicine and for combined faculty effort in each subspecialty division in the Department of Medicine. After determining the dollar value for a teaching unit, we distributed discretionary teaching dollars to each faculty member in the Division of General Internal Medicine and to each subspecialty division according to total teaching units.

MEASUREMENTS AND MAIN RESULTS

The distribution of discretionary teaching dollars was determined. In the year after the intervention, there was a substantial redistribution of discretionary teaching dollars among divisions. Compared with an increase in total discretionary dollars of 11.4%, the change in allocation for individual divisions ranged from an increase of 78.2% to a decrease of -28.5%. Further changes in the second year after the intervention were modest. The distribution of teaching units among divisions was similar to the distribution of questions across subspecialties on the American College of Physicians In-Training Examination (r =.67) and the American Board of Internal Medicine Certifying Examination (r =.88).

CONCLUSIONS

It is possible to measure the value of teaching effort by medical school faculty and to distribute discretionary teaching funds among divisions according to the value of teaching effort. When this intervention was used at our institution, there were substantial changes in the amounts received by some divisions. We believe that the new distribution more closely approximates the desired distribution because it reflects the desired emphasis on knowledge as measured by two of the most experienced professional groups in internal medicine. We also believe that our method is flexible and adaptable to the needs of most clinical teaching

Development and implementation of a teaching practice plan in a department of medicine (1995-1998): relative teaching units (RTU's)

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Renal effects of amphotericin B lipid complex

A study was conducted to compare the renal effects of amphotericin B lipid complex (ABLC), a lipid formulation of the widely used antifungal medication, with conventional amphotericin B (AmB) in the treatment of serious fungal infections, including invasive candidiasis, cryptococcal meningitis, and aspergillosis. The clinical experience of ABLC includes two types of open-label studies: randomized comparative (ABLC 5 mg/kg/d compared with AmB 0.6 to 1 mg/kg) and emergency use. In the comparative studies, changes in serum creatinine were evaluated three ways: doubling of the baseline value, an increase from < or = 1.5 mg/dL at baseline to > or = 1.5 mg/dL, and an increase from < or = 1.5 mg/dL at baseline to > or = 2.0 mg/dL. More patients in the AmB group reached these end points than in the ABLC group (P < or = 0.007), and the time needed to reach each of these end points was significantly shorter for the AmB group (P < or = 0.02). Increased serum creatinine was reported as an adverse event more frequently by patients receiving AmB than by patients receiving ABLC. In the emergency use study, a steady and statistically significant decrease in serum creatinine was observed among patients who started ABLC treatment with serum creatinine greater than 2.5 mg/dL due to prior AmB treatment. ABLC offers the physician a valuable, less-nephrotoxic alternative to AmB for the treatment of patients with severe, invasive fungal infections.

Bicarbonate transport in collecting duct segments during chloride-depletion alkalosis

Renal correction of chloride-depletion alkalosis (CDA) by chloride replacement results in bicarbonate secretion in the cortical collecting duct (CD) and urinary bicarbonate excretion. To assess the participation of the more distal segments of the CD, we determined net total CO2 transport in the outer medullary (OMCD), initial (IMCDi) and terminal (IMCDt) inner medullary CD segments obtained from Sprague-Dawley rats with normal acid-base balance (NML) or with CDA produced by peritoneal dialysis. Tubules were bathed and perfused with isotonic solutions containing Cl 110 mM and HCO, 25 mM. Net total CO2 transport was decreased in all segments: OMCD 22.1 +/- 4.2 to 9.2 +/- 2.0; IMCDi 38.1 +/- 4.6 to 9.3 +/- 1.7; IMCDt 6.7 +/- 1.2 to -0.5 +/- 0.4 pmol/min/mm tubule length. Perfusion rates, tubule lengths, and transepithelial voltages did not differ between groups in any segment. These data show that all CD segments beyond the cortical segment decrease bicarbonate reabsorption during CDA. This permits the bicarbonate secreted by the cortical CD to be excreted, and is likely an important mechanism for the correction of CDA.

Race, socioeconomic status, and the development of end-stage renal disease

The reasons for the increased annual incidence of end-stage renal disease (ESRD) in blacks compared with whites are unclear, but may include lack of access to treatment of the causative disease, which likely relates closely to socioeconomic status (SES). End-stage renal disease rates for diabetic glomerulosclerosis, hypertensive nephrosclerosis, and glomerulonephritis were determined in the 9,390 black and white New York State residents who began treatment within the Medicare program between 1982 and 1988. The relationship between the incidence of ESRD, age, and SES, as measured by the race-specific median family income in the patient's zip code, was estimated using a series of logistic-regression models for 12 populations: three causes of renal failure by two races by two sexes. For whites, incidence rates of diabetic glomerulosclerosis and hypertensive nephrosclerosis were significantly negatively associated with declining SES for the 45 to 65 year and 25 to 55 year age groups, respectively. In contrast, there was no relationship between the incidence of these diseases and SES in blacks. For glomerulonephritis, effects of SES were minor for both races. Better access to treatment of diabetes and hypertension might well decrease the annual incidence of ESRD due to diabetic glomerulosclerosis and hypertensive nephrosclerosis in whites. If the SES measures used for blacks are adequate, predisposition to progressive renal damage in response to renal injury or environmental factors other than SES are stronger risk factors for ESRD than SES.

Captopril-induced fall in glomerular filtration rate in cyclosporine-treated hypertensive patients

It was found that two known renal vasodilators had different effects on RBF and GFR in the setting of therapeutic blood levels of cyclosporine in hypertensive renal transplant patients. Captopril lowered blood pressure in these patients but also lowered blood flow and GFR. Nifedipine lowered blood pressure to the same degree but without lowering either RBF or GFR.

HCO3- transport in rat CCD: rapid adaptation by in vivo but not in vitro alkalosis

Acute chloride-depletion alkalosis (CDA) in vivo results in sustained net total carbon dioxide (tCO2) secretion in vitro in the rat cortical collecting duct (CCD) for several hours. To determine whether altering in vitro pH and electrolytes similarly result in tCO2 secretion, CCD were incubated for 1 h at 37 degrees C in an alkalotic environment similar to in vivo arterial pH, PCO2, and electrolytes (pH 7.6, 40 mM HCO3). The in vitro alkalosis incubation had no effect on tCO2 transport. Second, alteration of the magnitude of vivo alkalosis was correlated with in vitro tCO2 transport. After generation of CDA by intraperitoneal dialysis against 154 mM HCO3-, rats received an infusion for 2.5 h of either 5% dextrose to maintain alkalosis or 154 mM NaCl at differing rates to partially correct or fully correct the systemic alkalosis. After in vitro isolation and perfusion, in vitro tCO2 flux correlated with in vivo Cl- balance (r2 = 0.82), serum HCO3- (r2 = 0.84), and arterial H+ concentration (r2 = 0.78), but not with K+ balance (r2 = 0.33). These findings suggest that: 1) the regulation of tCO2 transport in vitro correlates with the degree of systemic alkalosis and Cl- balance in vivo, and 2) simulating alkalotic pH and electrolytes in vitro does not rapidly alter transport as does in vivo CDA within a similar time. Taken together, pH and electrolyte changes alone cannot account for the rapid adaptation of tCO2 transport in the CCD, but an in vivo factor(s) contributes importantly to alter tCO2 transport in magnitude and direction that would tend to restore normal acid-base balance.

Response of intercalated cells to chloride depletion metabolic alkalosis

We examined the effect of Cl- depletion metabolic alkalosis (CDA) on H(+)-ATPase and band 3 protein localization in intercalated cells (IC) of the rat cortical collecting duct (CCD) and the outer medullary collecting duct (OMCD). After 30 min of peritoneal dialysis against 0.15 M NaHCO3 to produce CDA, or Ringer bicarbonate to serve as controls (CON), both groups were infused intravenously with an 80 mM Cl- solution for 90 min. For CDA vs. CON, physiological parameters were as follows: plasma total CO2, 38.0 +/- 1.1 vs. 27.8 +/- 0.6 meq/l (P less than 0.001); urinary total CO2 excretion, 141 +/- 89 vs. 20 +/- 3 neq.min-1.100 g body wt-1; and urinary Cl- excretion, 20 +/- 10 vs. 486 +/- 144 neq.min-1.100 g body wt-1 (P less than 0.001). H(+)-ATPase was localized in thin sections using a rabbit polyclonal antibody against the 70-kDa subunit of bovine brain H(+)-ATPase. Band 3 protein was localized using a polyclonal antibody against the 43-kDa subunit of the cytoplasmic domain of human erythrocyte band 3 protein. In CON rats, H(+)-ATPase localized along the apical plasma membrane and over the apical cytoplasmic vesicles of type A ICs in the CCD and ICs of the OMCD. H(+)-ATPase was observed along the basolateral plasma membrane and over cytoplasmic vesicles throughout type B ICs. In CDA rats, H(+)-ATPase was only observed over apical cytoplasmic vesicles in type A ICs and in the majority of OMCD ICs. In type B ICs, H(+)-ATPase staining was intensified along the basal plasma membrane in CDA. Band 3 protein was consistently localized in the basolateral plasma membrane of all type A cells in the CCD and ICs of the OMCD in both CON and CDA. In summary, stimulation of HCO3- secretion in rats caused withdrawal of H(+)-ATPase from the apical plasma membrane and storage in apical cytoplasmic vesicles of ICs of the OMCD and type A ICs of the CCD. H(+)-ATPase appeared to be inserted into the basal plasma membrane of type B ICs. These findings suggest that, during correction of CDA, proton secretion by type A and OMCD ICs is suppressed and proton transport across the basolateral plasma membrane of type B ICs is stimulated.

Absence of a regulatory role of angiotensin II in acute chloride-depletion alkalosis in rats

Chloride-depletion alkalosis (CDA) has been characterized by hypereninemia. To determine whether angiotensin II (ANG II) has an important role in its maintenance or correction, anesthetized alkalotic rats, chloride depleted by peritoneal dialysis, were infused with 5% dextrose and saralasin (1 microgram.kg-1.min-1) (SAR) or vehicle (SAR-C), 5% dextrose and pretreatment with enalapril (1-1.5 mg/kg) (ENP) or vehicle (ENP-C), or 80 mM Cl solution with ANG II (20 micrograms/min) (ANG) or vehicle (ANG-C). Rats infused with 5% dextrose showed no differences in the magnitude of the alkalosis, inulin clearance, or urinary total CO2 excretion; both SAR and ENP were associated with decreased blood pressure. In SAR, tCO2 delivery out of late proximal convoluted tubule did not differ from that in SAR-C. Rats infused with 80 mM Cl corrected CDA similarly (delta plasma [Cl] - ANG-C + 6 +/- 1, ANG + 5 +/- 1 mM; P = not significant). These data suggest that, although ANG II can importantly influence vascular tone and early proximal tubule bicarbonate reabsorption, it does not have an important role in the renal maintenance or correction of acute CDA.

Adaptations to chloride-depletion alkalosis

The systemic and renal adaptations for the maintenance and correction of metabolic alkalosis generated by chloride depletion (CDA) are the focus of this review. The hypothesis that extracellular fluid (ECF) volume expansion is essential for the correction of CDA is refuted, while the concept that Cl- repletion is necessary and sufficient for correction is developed. Contraction of ECF volume probably can occur as a consequence of CDA. The principal mechanisms by which the kidney corrects CDA appear to reside primarily in the collecting duct, which is endowed with the anion exchange mechanisms and the capacity to effect the necessary changes in body anion composition. Although the remainder of the collecting duct is undoubtedly important in this response, the cortical segment appears to have the paramount role since it can either absorb or secrete HCO3-. Alterations in the delivery of Cl- or HCO3- to the collecting duct may also be important but changes in glomerular filtration rate appear to have a minor role. Major unanswered questions in the pathophysiology of CDA are the manner in which exogenous Cl- repletion is detected and the kidney is signaled to excrete HCO3- and the cellular mechanisms by which this is accomplished in the various nephron segments.

Changing patterns of end-stage renal disease due to hypertension

We analyzed the records of all residents of Jefferson County, Alabama, accepted for renal replacement therapy between 1982 and 1987 and compared them with those accepted between 1974 and 1978 to determine any changes in the distribution and frequency of end-stage renal disease (ESRD) due to hypertension (H-ESRD). H-ESRD increased from 6.4 to 9.6 per 100,000 in blacks and from 0.36 to 0.62 per 100,000 in whites. Smoothed age- and race-specific yearly H-ESRD rates decreased in blacks under age 50. Peak incidence of H-ESRD shifted from age 40 to 49 in 1974 through 1978 to age 50 to 59 in 1982 through 1987 (P less than 0.0001). Blacks were referred for care with significantly higher blood pressure levels and serum creatinine concentrations than whites, and had more severe retinal vascular disease. Factors significantly associated with a shorter time from referral to renal replacement therapy were black race, female gender, blood urea nitrogen and serum creatinine concentrations, carbohydrate intolerance, and the use of alpha-agonist and/or angiotensin-converting enzyme (ACE) inhibitor. We conclude that racial distribution and risk for H-ESRD have not changed. Peak rates of H-ESRD have been delayed nearly a decade, suggesting a possible effect of better awareness and treatment of hypertension.

Pathophysiology and treatment of posttransplant hypertension

Post-renal transplant hypertension remains a common problem. The most frequent causes now are chronic rejection and cyclosporine-induced hypertension. Before the development of cyclosporine, renin-dependent hypertension was the dominant pathophysiological mechanism but now, with the widespread use of cyclosporine, a salt-dependent mechanism is the major one. In severe "inappropriate" hypertension, potentially surgically remediable causes such as renal artery stenosis of the allograft artery or renin release from the native kidneys should be considered. Cyclosporine causes hypertension in normal subjects and in all solid organ transplants. The most likely mechanism is renal vasoconstriction with subtle retention of sodium chloride together with systemic vasoconstriction. The vasoconstriction, as yet, is not associated with any specific vasoconstricting agent nor does there appear to be a specific antagonist. Indeed, increased sensitivity to many different vasoconstrictors has been demonstrated. The major site of vasoconstriction appears to be in the afferent arteriole, and optimum antihypertensive therapy is probably provided by calcium channel blockers if the hypertension is due to cyclosporine. Because post-renal transplant hypertension is often multifactorial in origin, however, it is not surprising that the use of combined antihypertensives is often necessary.

Mechanism of cyclosporine-induced hypertension

Cyclosporine is a common immunosuppressive agent used in solid organ and bone marrow transplants and the treatment of some immunological diseases. It has been established that treatment with cyclosporine can cause a patient to develop hypertension within a few weeks of treatment. This review will examine this effect and effective ways to treat it.

Ion concentrations in the rat CCD: differences between cell types and effect of alkalosis

We have previously shown that the isolated perfused cortical collecting duct (CCD) from chloride-depleted alkalotic (CDA) rats continues to secrete HCO3 for up to 3 h. To determine whether the sustained alteration in transport was associated with changes in intracellular ion concentrations, we performed energy-dispersive X-ray microanalysis in microdissected tubule bundles obtained from CDA rats and rats with normal acid-base status (CON). Before analysis, the bundles from both groups were incubated for 1 h in vitro in a modified Ringer solution (pH 7.4, 105 mM Cl). Principal (PC) and intercalated cells (IC) of the CCD from CON animals differed in the nuclear concentration of Na (17.0 vs. 24.7 mmol/l cell water), K (192.5 vs. 177.0 mmol/l cell water), and Cl (17.8 vs. 47.8 mmol/l cell water). Cells of the cortical thick ascending limb of Henle (CTAL) had the lowest Na and Cl values (11.5 and 14.8 mmol/l cell water, respectively). CDA resulted in no systematic Cl changes. In the IC the nuclear Na concentration was significantly increased (32.0 vs. 24.7 mmol/l cell water) and in all cells a small reduction in K concentration was detectable. These findings suggest that 1) the different transport functions of IC, PC, and CTAL are associated with differences in the intracellular ion composition, and 2) the sustained HCO3 secretion seen in CCD from CDA rats cannot be explained as the result of intracellular Cl depletion.

Cyclosporine-induced changes in glomerular filtration rate and urea excretion

PURPOSE

Cyclosporine is the mainstay of many immunosuppressant protocols, but confers a significant risk of nephrotoxicity. We sought to clarify the effects of cyclosporine on renal function in renal transplant recipients after induction of mild intravascular volume depletion.

PATIENTS AND METHODS

Two groups of renal transplant patients with normal allograft function at least 6 months after transplantation whose immunosuppressive regimens differed only by the presence or absence of cyclosporine usage were enrolled in a 10-day in-hospital protocol. After a 3-day control period, intravascular volume depletion was produced by dietary restriction of sodium chloride for 4 days and the administration of furosemide. Creatinine and urea clearances, true glomerular filtration rate (GFR) (by radioisotope technique), and the fractional excretion of sodium were measured. The patients were subsequently given a high amount of sodium chloride by intravenous infusion (3.8 mEq/kg body weight/day) for 3 days and the studies were repeated.

RESULTS

Ten patients treated with azathioprine and prednisone (azathioprine-treated) and nine patients treated with cyclosporine, azathioprine, and prednisone (cyclosporine-treated) were enrolled. The two groups developed a similar degree of intravascular volume depletion; blood pressure did not change and urine flow rates did not differ between the groups throughout the protocol. The cyclosporine-treated patients showed significant decreases in GFR, creatinine clearance, and urea clearance, and increases in blood urea nitrogen (BUN) and percent urea reabsorption after intravascular volume depletion; these findings resolved after challenge with the sodium chloride load. In contrast, the azathioprine-treated patients' BUN, urea clearance, GFR, and creatinine clearance did not significantly change throughout the protocol. The decrease in the fractional excretion of sodium after intravascular volume depletion was significantly greater in the cyclosporine-treated patients.

CONCLUSION

Cyclosporine predisposes to acute reversible nephrotoxicity by compromising the renal compensatory mechanisms. Proximal tubular function, as manifested by urea and sodium reabsorption, remains intact.

Total CO2 transport in rat cortical collecting duct in chloride-depletion alkalosis

Previous studies in chloride-depletion metabolic alkalosis (CDA) generated by intraperitoneal dialysis have suggested major alterations in chloride and bicarbonate transport beyond the distal convoluted tubule. To investigate the possible role of the cortical collecting duct (CCD) in the pathophysiology of CDA, isolated CCD segments were perfused in vitro from either control (CON) rats dialyzed against Ringer-bicarbonate or those made alkalotic by peritoneal dialysis with 0.15 M NaHCO3. Tubules from CDA animals secreted CO2 for greater than or equal to 3 h after dissection (-22.4 +/- 7.2 pmol.mm-1.min-1) compared with CON tubules that absorbed CO2 (18.3 +/- 4.2 pmol.mm-1.min-1). Replacement of luminal chloride with gluconate in the perfusate abolished net total CO2 (tCO2) secretion in tubules from CDA animals (from -21.5 +/- 4.5 to -2.7 +/- 2.3 pmol.mm-1.min-1) but did not alter net tCO2 absorption in tubules from CON animals. In contrast, removal of bath chloride increased net tCO2 secretion (-12.1 +/- 2.9 to -26.1 +/- 3.6 pmol.mm-1.min-1) in CDA tubules, whereas net tCO2 flux was altered from absorption to secretion in CON tubules (15.5 +/- 4.0 to -13.6 +/- 9.2 pmol.mm-1.min-1). These results demonstrate that 1) CDA generated in vivo within 45 min results in stable net tCO2 secretion in vitro up to 240 min in the CCD; 2) luminal chloride is necessary for tCO2 secretion; 3) the shift of net tCO2 flux from absorption to secretion in CON tubules in vitro was not sustained in contrast to CDA tubules.(ABSTRACT TRUNCATED AT 250 WORDS)

Superficial distal and deep nephrons in correction of metabolic alkalosis

Chloride is necessary and sufficient to correct alkalosis induced by dialysis vs. 0.15 M NaHCO3. To determine the contribution of the cortical (SC) distal convolution (DCT) and juxtamedullary (JM) nephrons to correction, we examined Cl and total CO2 (tCO2) transport in alkalotic Sprague-Dawley rats infused with 5% dextrose (group DM) or with 5% dextrose and 80 mM Cl (group CC); in papillary studies in alkalotic Munich-Wistar rats, 6% albumin was added to the infusate. In cortical studies, changes in plasma Cl and tCO2 were 4.9 +/- 0.7 vs. 0.7 +/- 0.9 and -6.0 +/- 0.8 vs. 0.4 +/- 0.9 meq/l and in tCO2 excretion (133 +/- 28 vs. -8 +/- 10 mueq/min) in groups CC and DM, respectively; results in papillary studies were similar. Delivery of tCO2 out of late SC DCT (CC 146 +/- 20 and DM 146 +/- 23 pmol/min) and Henle's loop (CC 145 +/- 18 and DM 202 +/- 56 pmol/min) and reabsorption within DCT (CC 15 +/- 24 and DM 45 +/- 19 pmol/min) did not differ. During correction of chloride-depletion alkalosis, the increment in bicarbonate excretion does not emanate from DCT of SC nephrons or JM nephrons but rather from the collecting duct.

Successful renal allografts in recipients with crossmatch-positive, dithioerythritol-treated negative sera. Race, transplant history, and HLA-DR1 phenotype

Graft survival was examined in 15 renal allograft recipients from a group of 20 patients with IgM autolymphocytotoxic antibody that could be removed in a crossmatch assay using a reducing agent, dithioerythritol (DTE). The significant differences in this group of 20 patients compared with end-stage renal disease (ESRD) patients lacking autolymphocytotoxic antibodies included an increased frequency of black patients (P = 0.002), a lack of previous transplants (P = 0.003), and an increased frequency of the HLA-DR1 phenotype (P = 0.0001). Sex and the number of transfusions did not appear significant, whereas the cause of ESRD was primarily systemic lupus erythematosus. Fifteen of the 20 patients were transplanted against a positive donor crossmatch. Eleven were recipients of cadaveric kidneys, nine of which are still functioning for periods ranging from 0.5 to 40 months. Two fo the cadaveric recipients died with functional grafts. Four received living-related donor transplants, one of which was lost to acute rejection one month posttransplant, while the remaining three have survived 1.5, 9, and 21 months, respectively. Fourteen patients had immediate allograft function with no hyperacute rejection and only one case of acute tubular necrosis (ATN) was found. In summary, a negative crossmatch using DTE-treated, autologous reactive recipient sera may identify a group of patients who can be transplanted with minimal concern for hyperacute rejection or ATN. In addition to cause of ESRD, race, transplant history, and HLA-DR phenotype may further define this group of transplant candidates having IgM autolymphocytotoxic antibody. Extrapolation of these conclusions to transplant candidates lacking autolymphocytotoxic antibodies is not warranted.

Abnormal captopril renogram with a technetium-99m-labeled hippuran analog

A case of renovascular hypertension is presented in which the [131I]hippuran renogram was initially normal, but became strikingly abnormal upon administration of the angiotensin converting enzyme (ACE) inhibitor captopril. The patient presented with fibromuscular dysplasia of the renal arteries, which was shown by hippuran renography to be functionally significant on the right side. She became normotensive after angioplasty of the right renal artery. Hypertension recurred a year later, at which time the renogram was normal without captopril, but showed functionally significant left renal artery stenosis with captopril challenge. Both the conventional agent, [131I]hippuran, and an experimental new 99mTc-labeled hippuran analog, [99mTc]MAG3, were used. Angiography confirmed progression of disease on the left side, which was successfully treated by angioplasty. Functionally significant unilateral renal artery stenosis was thus demonstrated first on the right side and then, 1 yr later, on the left side, using hippuran and [99mTc]MAG3. Anatomic progression of disease was documented by angiography.

Hypertension in cyclosporine-treated renal transplant recipients is sodium dependent

PURPOSE

Physicians increasingly prescribe cyclosporine as an immunosuppressive agent for both organ-transplant and non-organ-transplant recipients. Investigators have reported a high incidence of drug-induced hypertension even when clinical nephrotoxicity was not present. We wanted to determine the reason.

PATIENTS AND METHODS

A comparison was made of hypertension in 15 cyclosporine-treated transplant recipients with that in a similar group of 15 azathioprine-treated transplant recipients.

RESULTS

Hypertension in the cyclosporine group responded differently from that seen in the azathioprine group and from previously described forms of post-transplantation hypertension. Hypertensive cyclosporine-treated patients show a sodium acquisitive renal state that responds to sodium restriction. Unlike rat models, which suggest cyclosporine-induced stimulation of the renin-angiotensin system, or previous forms of post-transplant hypertension in humans, plasma renin levels were not elevated and blood pressure did not respond to a test dose of captopril.

CONCLUSION

Hypertension in cyclosporine-treated patients is an iatrogenic form of hypertension that may be associated with an early, subtle, renal defect in sodium excretion, a genesis of hypertension that is consistent with Guyton's view of essential hypertension.

Important risk factors of allograft survival in cadaveric renal transplantation. A study of 426 patients

Multiple risk factors contribute to the allograft survival of patients who have cadaveric renal transplantation. A retrospective review of 19 such factors in 426 patients identified race, DR match, B + DR match, number of transplants, and preservation time to have a significant influence. The parametric analysis confirmed the effect to be primarily in the early phase, i.e., first 6 months. All patients received cyclosporine with other methods of immunosuppression resulting in an overall 1-year graft survival rate of 66%. The overall 1-year graft survival rate in the white race was 73% and in the black race was 57% (p = 0.002). Allograft survival and DR match showed white recipients with a 1 DR match to have 75% survival at 1 year compared with 57% in the black patient (p = 0.009). If HLA B + DR match was considered, the white recipient allograft survival increased to 76%, 84%, and 88% for 1, 2, and 3 match kidneys by parametric analysis. Patients receiving first grafts had better graft survival (68%) than those undergoing retransplantation (58%) (p = 0.05). Organ preservation less than 12 hours influenced allograft survival with a 78% 1-year survival rate compared with 63% for kidneys with 12-18 hours of preservation. Despite the benefits of B + DR typing, short preservation time, and first transplants to the white recipient, the allograft survival in the black recipient remained uninfluenced by these parameters.

On the mechanism by which chloride corrects metabolic alkalosis in man

To determine whether administration of chloride corrects chloride-depletion metabolic alkalosis (CDA) by correction of plasma volume contraction and restoration of glomerular filtration rate or by an independent effect of chloride repletion, CDA was produced in normal men by the administration of furosemide and maintained by restriction of dietary sodium chloride intake. Negative sodium balance (-112 +/- 16 meq) and reduced plasma volume (2.53 versus 2.93 liters, p less than 0.05) developed. The cumulative chloride deficit of 271 +/- 16 meq was then repleted by oral potassium chloride (267 +/- 19 meq) over 36 hours with continued serial measurements of glomerular filtration rate, effective renal plasma flow, plasma volume, body weight, and plasma renin and aldosterone levels. CDA was corrected, even though body weight, plasma volume, glomerular filtration rate, and renal plasma flow all remained reduced and plasma aldosterone was elevated; urinary bicarbonate excretion increased during correction. Administration of an identical potassium chloride load to similarly sodium-depleted but not chloride-depleted normal subjects produced no change in acid-base status. It is concluded that chloride repletion can correct CDA by a renal mechanism without restoring plasma volume or glomerular filtration rate or by altering sodium avidity.

A comparison of OKT3 monoclonal antibody and corticosteroids in the treatment of acute renal allograft rejection

The monoclonal antibody OKT3 (Ortho Pharmaceutical, Raritan, NJ) was utilized in two separate protocols for treatment of acute renal allograft rejection in patients receiving cyclosporine, azathioprine, and prednisone for maintenance immunosuppression. In Group I, 54 patients received steroids for primary treatment of acute rejection with OKT3 used for resistant rejections and second rejection episodes. In Group II, 34 patients received OKT3 as primary treatment of acute rejection while steroids were used for rescue and second rejection episodes. OKT3 successfully reversed 82% of initial acute rejection episodes in Group II as compared with a 63% reversal with steroids in Group I. Rescue treatment was required in only 15% of Group II patients compared with 33% of Group I patients. Overall patient survival was 96% and 94%, respectively, for steroid primary and OKT3 primary treatments. Allograft survival at 3 months was identical, 74% in both groups. Based on allograft survival data, OKT3 is equally effective either as primary treatment for allograft rejection, or for rescue therapy if initial corticosteroid treatment fails.

Systemic hypertension and the kidney in black patients

Hypertension occurs more frequently in U.S. blacks than whites and is more severe. Blacks represent a disproportionate percentage of patients receiving dialysis treatment. This disproportion raises the question of whether the renal circulation of blacks is more sensitive to the damaging effects of elevated intraarterial pressure or whether it is structurally different in ways that would render it more prone to damage. The first part of the question has not been conclusively answered although some data support the hypothesis. For the second part, it is clear that malignant nephrosclerosis of blacks is different from that of whites in an absence of fibrinoid necrosis of arterioles and glomeruli and the presence of musculomucoid intimal hyperplasia of small arteries. Whether this is a genetically determined reaction to damage has not been determined. It is a widely held belief that the kidney is the cause of much essential hypertension. In fact 6 cases of essential hypertension in blacks have been "cured" by renal transplantation, strongly supporting the belief. Also blacks differ from whites in 2 ways that could be relevant for their increased prevalence of hypertension: they excrete sodium loads more slowly and have a markedly lower urinary kallikrein. The former could be responsible for the predominance of salt-dependent hypertension in blacks and the latter could reflect a racial deficiency in a naturally occurring vasodilator system.

Importance of chloride for the correction of chronic metabolic alkalosis in the rat

To determine whether chloride repletion without sodium could correct chronic chloride depletion metabolic alkalosis (CDA) in Sprague-Dawley rats without volume expansion and without increasing glomerular filtration rate (GFR), CDA was generated by peritoneal dialysis (PD) against 0.15 M NaHCO3 and maintained for 7-10 days by a chloride-restricted diet supplemented with sodium and potassium salts. Control animals were dialyzed against Ringer bicarbonate. The maintenance period of chronic CDA, compared with control, was characterized by hypokalemic metabolic alkalosis (serum TCO2 31.9 +/- 0.6 vs. 23.1 +/- 0.5 meq/l, P less than 0.05), volume contraction (plasma volume 3.76 +/- 0.08 vs. 4.19 +/- 0.22 ml/100 g body wt, P less than 0.05), decreased GFR (838 +/- 84 vs. 1045 +/- 45 microliters.min-1.100 g body wt-1, P less than 0.05), increased plasma renin activity (PRA) (63 +/- 13 vs. 12 +/- 3 ng.ml-1.h-1, P less than 0.05), but unchanged plasma aldosterone concentrations (PAC) (4.1 +/- 1.0 vs. 3.4 +/- 1.6 ng/dl, P = NS). Complete correction of chronic CDA was accomplished by 24 h of ingestion of choline chloride drink, and despite negative sodium balance, neutral potassium balance, continued bicarbonate ingestion, and persistent volume contraction (plasma volume 3.76 +/- 0.08 vs. 3.73 +/- 0.12 ml/100 g body wt pre- and postcorrection, P = NS), GFR remained decreased (659 +/- 87 vs. 1,045 +/- 45 microliters.min-1.100 g body wt-1, P less than 0.05), PRA decreased (63 +/- 13 vs. 33 +/- 5 ng.ml-1.h-1, P less than 0.05), but PAC did not change (4.1 +/- 1.0 vs. 6.1 +/- 1.6 ng/dl, P = NS) after correction of CDA.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of chloride and extracellular fluid volume on bicarbonate reabsorption along the nephron in metabolic alkalosis in the rat. Reassessment of the classical hypothesis of the pathogenesis of metabolic alkalosis

Volume expansion has been considered essential for the correction of chloride-depletion metabolic alkalosis (CDA). To examine the predictions of this hypothesis, rats dialyzed against 0.15 M NaHCO3 to produce CDA and controls, CON, dialyzed against Ringer-HCO3 were infused with either 6% albumin (VE) or 80 mM non-sodium chloride salts (CC) added to 5% dextrose (DX) and studied by micropuncture. CDA was maintained in rats infused with DX. VE expanded plasma volume (25%), maintained glomerular filtration rate (GFR), but did not correct CDA despite increased fractional delivery of total CO2 (tCO2) out of the proximal tubule (36 +/- 2%) as compared with VE/CON (24 +/- 4%; P less than 0.05). In contrast, CC corrected CDA despite volume contraction (-16%) and lower GFR than CC/CON; proximal tCO2 delivery in CC/CDA (29 +/- 4%) did not differ from VE/CDA. CC was associated with an increment in tCO2 excretion. The data strongly suggest that maintenance and correction of CDA are primarily dependent upon total body chloride and its influences on intrarenal mechanisms and not on the demands of sodium or fluid homeostasis.