Autosomal dominant tubulointerstitial kidney disease (ADTKD) in Ireland

Introduction: Autosomal dominant tubulointerstitial kidney disease (ADTKD) is a rare genetic cause of renal impairment resulting from mutations in the MUC1, UMOD, HNF1B, REN, and SEC61A1 genes. Neither the national or global prevalence of these diseases has been determined. We aimed to establish a database of patients with ADTKD in Ireland and report the clinical and genetic characteristics of these families.

Methods: We identified patients via the Irish Kidney Gene Project and referral to the national renal genetics clinic in Beaumont Hospital who met the clinical criteria for ADTKD (chronic kidney disease, bland urinary sediment, and autosomal dominant inheritance). Eligible patients were then invited to undergo genetic testing by a variety of methods including panel-based testing, whole exome sequencing and, in five families who met the criteria for diagnosis of ADTKD but were negative for causal genetic mutations, we analyzed urinary cell smears for the presence of MUC1fs protein.

Results: We studied 54 individuals from 16 families. We identified mutations in the MUC1 gene in three families, UMOD in five families, HNF1beta in two families, and the presence of abnormal MUC1 protein in urine smears in three families (one of which was previously known to carry the genetic mutation). We were unable to identify a mutation in 4 families (3 of whom also tested negative for urinary MUC1fs).

Conclusions: There are 4443 people with ESRD in Ireland, 24 of whom are members of the cohort described herein. We observe that ADTKD represents at least 0.54% of Irish ESRD patients.

Identification of a novel UMOD mutation (c.163G>A) in a Brazilian family with autosomal dominant tubulointerstitial kidney disease

Autosomal dominant tubulointerstitial kidney disease (ADTKD) is characterized by autosomal dominant inheritance, progressive chronic kidney disease, and a bland urinary sediment. ADTKD is most commonly caused by mutations in the UMOD gene encoding uromodulin (ADTKD-UMOD). We herein report the first confirmed case of a multi-generational Brazilian family with ADTKD-UMOD, caused by a novel heterozygous mutation (c.163G>A, GGC→AGC, p.Gly55Ser) in the UMOD gene. Of 41 family members, 22 underwent genetic analysis, with 11 individuals found to have this mutation. Three affected individuals underwent hemodialysis, one peritoneal dialysis, and one patient received a kidney transplant from a family member later found to be genetically affected. Several younger individuals affected with the mutation were also identified. Clinical characteristics included a bland urinary sediment in all tested individuals and a kidney biopsy in one individual showing tubulointerstitial fibrosis. Unlike most other reported families with ADTKD-UMOD, neither gout nor hyperuricemia was found in affected individuals. In summary, we report a novel UMOD mutation in a Brazilian family with 11 affected members, and we discuss the importance of performing genetic testing in families with inherited kidney disease of unknown cause.

The impact of sickle cell trait on glycated haemoglobin in diabetes mellitus

AIMS

To determine the effect of sickle cell trait on measurement of glycated haemoglobin (HbA(1c)) in African American patients with diabetes mellitus.

METHODS

This is a retrospective study including 885 outpatients who underwent HbA(1c) testing. Medical record review and sickle cell trait determinations based on the HbA(1c) assay were performed in African American participants. The relationship between HbA(1c) and serum glucose measurements was analysed.

RESULTS

Data were obtained from 385 AA (109 with SCT, 22 with haemoglobin C trait and 254 without haemoglobinopathy) and 500 European American patients. In a model created through multivariate repeated-effects regression, the relationship between HbA(1c) and simultaneous serum glucose did not differ between African American subjects with and without the sickle cell trait, but differed between African American subjects without the sickle cell trait and European Americans (P = 0.0002).

CONCLUSIONS

Sickle cell trait does not impact the relationship between HbA(1c) and serum glucose concentration. In addition, it does not appear to account for ethnic difference in this relationship between African Americans and whites.

Ethnic variation in the correlation between random serum glucose concentration and glycated haemoglobin

AIMS

To determine if the relationship between serum glucose concentration and glycated haemoglobin is different between African-Americans and whites.

METHODS

Retrospective cross-sectional study comparing the association between glycated haemoglobin and serum glucose levels, based upon ethnicity. Two databases were evaluated: (i) 4215 African-American and 6359 white outpatients who had simultaneous glycated haemoglobin, random serum glucose and creatinine concentration measurements between 2000 and 2007 at the North Carolina Baptist Hospital and (ii) 1021 white and 312 African-American Diabetes Heart Study (DHS) participants.

RESULTS

In North Carolina Baptist Hospital clinic attendees, a given glycated haemoglobin was associated with higher serum glucose concentrations in African-Americans compared with whites. In a multivariate model with glycated haemoglobin as the outcome variable, racial differences remained significant after adjustment for serum glucose, age, gender and kidney function. For individuals with a serum glucose between 5.6 and 8.3 mmol/l, the glucose : glycated haemoglobin ratio was 1.03 +/- 0.16 mmol/l/% in white individuals and 0.99 +/- 0.17 mmol/l/% in African-Americans (P < 0.0001). For a glycated haemoglobin value of 7.0%, there was a 0.98-mmol/l difference in predicted serum glucose concentration in 50-year-old African-American men, relative to white. Results were replicated in the DHS, where in a best-fit linear model, after adjustment for glucose, African-American race was a significant predictor of glycated haemoglobin (P < 0.0001).

CONCLUSIONS

African-Americans have higher glycated haemoglobin values at given serum glucose concentrations relative to whites. This finding may contribute to the observed difference in glycated haemoglobin values reported between these race groups.

Comparison of glycated albumin and hemoglobin A(1c) levels in diabetic subjects on hemodialysis

Glycated albumin is thought to more accurately reflect glycemic control in diabetic hemodialysis patients than hemoglobin A(1c) because of shortened red cell survival. To test this, glycated hemoglobin and albumin levels were measured in blood samples collected from 307 diabetic subjects of whom 258 were on hemodialysis and 49 were without overt renal disease. In diabetic subjects with renal disease, relative to those without, the mean serum glucose and glycated albumin concentrations were significantly higher while hemoglobin A(1c) tended to be lower. The glycated albumin to hemoglobin A(1c) ratio was significantly increased in dialysis patients compared with the controls. Hemoglobin A(1c) was positively associated with hemoglobin and negatively associated with the erythropoietin dose in hemodialysis patients, whereas these factors and serum albumin did not significantly impact glycated albumin levels. Using best-fit multivariate models, dialysis status significantly impacted hemoglobin A(1c) levels without a significant effect on glycated albumin. Our results show that in diabetic hemodialysis patients, hemoglobin A(1c) levels significantly underestimate glycemic control while those of glycated albumin more accurately reflect this control.

Characteristics of sudden death in hemodialysis patients

Hemodialysis (HD) is an intermittent procedure during which large fluid and electrolyte shifts occur. We hypothesized that sudden death occurrences in HD patients are related to the timing of HD, and that they occur more frequently in the 12 h period starting with dialysis and in the 12 h period at the end of the dialysis-free weekend interval. In a retrospective study, 228 patient deaths were screened to determine if they met the criteria for sudden death. Information was obtained from clinic charts, dialysis center records, and interview of witnesses of the death event. There were 80 HD patients who met the criteria for sudden death. A bimodal distribution of death occurrences was present, with a 1.7-fold increased death risk occurring in the 12 h period starting with the dialysis procedure and a threefold increased risk of death in the 12 h before HD at the end of the weekend interval (P=0.011). Patients with sudden death had a high prevalence of congestive heart failure and coronary artery disease. Only 40% of patients experiencing sudden death were receiving beta-blockers, and the prior monthly serum potassium value was less than 4 mEq/l in 25%. Sudden death is temporally related to the HD procedure. Every other day HD could be beneficial in preventing sudden death. Careful attention to the usage of beta-blockers and to the maintenance of normal serum potassium values is indicated in HD patients at risk for sudden death.

Mutations of the UMOD gene are responsible for medullary cystic kidney disease 2 and familial juvenile hyperuricaemic nephropathy

INTRODUCTION

Medullary cystic kidney disease 2 (MCKD2) and familial juvenile hyperuricaemic nephropathy (FJHN) are both autosomal dominant renal diseases characterised by juvenile onset of hyperuricaemia, gout, and progressive renal failure. Clinical features of both conditions vary in presence and severity. Often definitive diagnosis is possible only after significant pathology has occurred. Genetic linkage studies have localised genes for both conditions to overlapping regions of chromosome 16p11-p13. These clinical and genetic findings suggest that these conditions may be allelic.

AIM

To identify the gene and associated mutation(s) responsible for FJHN and MCKD2.

METHODS

Two large, multigenerational families segregating FJHN were studied by genetic linkage and haplotype analyses to sublocalise the chromosome 16p FJHN gene locus. To permit refinement of the candidate interval and localisation of candidate genes, an integrated physical and genetic map of the candidate region was developed. DNA sequencing of candidate genes was performed to detect mutations in subjects affected with FJHN (three unrelated families) and MCKD2 (one family).

RESULTS

We identified four novel uromodulin (UMOD) gene mutations that segregate with the disease phenotype in three families with FJHN and in one family with MCKD2.

CONCLUSION

These data provide the first direct evidence that MCKD2 and FJHN arise from mutation of the UMOD gene and are allelic disorders. UMOD is a GPI anchored glycoprotein and the most abundant protein in normal urine. We postulate that mutation of UMOD disrupts the tertiary structure of UMOD and is responsible for the clinical changes of interstitial renal disease, polyuria, and hyperuricaemia found in MCKD2 and FJHN.

Relationship between underlying renal disease and renal transplantation outcome

The purpose of this study is to better characterize graft and patient survival posttransplantation by examining survival according to underlying renal disease for all first-time renal allograft recipients in the United Network for Organ Sharing (UNOS) registry. From 1987 through 1996, the UNOS registry collected data on 23,838 living and 67,183 cadaveric renal transplantations. This investigation included all patients undergoing their first renal transplantation for whom the underlying cause of renal failure could be identified and categorized. Gross 1- and 3-year patient and graft survival according to underlying renal disease are included. In addition, a Cox proportional hazards model was created to analyze the effect of underlying disease on graft and patient survival after adjusting for comorbid conditions, demographics, and type of renal transplant (living versus cadaveric). The association between underlying disease and graft and patient survival is shown. Amyloidosis, sickle cell anemia, scleroderma, and radiation nephritis are associated with poor graft and patient survival. The risk ratio for patient mortality was more than twice that for immunoglobulin A nephropathy for a number of conditions, including analgesic nephropathy, amyloidosis, and both forms of diabetes mellitus.

Tobacco, hypertension, and vascular disease: risk factors for renal functional decline in an older population

BACKGROUND

A decline in renal function with age has been noted in some but not all individuals. The purpose of this study was to identify risk factors associated with a clinically significant increase in serum creatinine (of at least 0.3 mg/dL) in an older nondiabetic population.

METHODS

A retrospective case-control study was performed analyzing data obtained from 4142 nondiabetic participants of the Cardiovascular Health Study Cohort, all at least 65 years of age, who had two measurements of serum creatinine performed at least three years apart. Cases were identified as participants who developed an increase in serum creatinine of at least 0.3 mg/dL, with controls including participants who did not sustain such an increase.

RESULTS

There was an increase in the serum creatinine of at least 0.3 mg/dL in 2.8% of the population. In a multivariate "best-fit" model adjusted for gender, weight, black race, baseline serum creatinine, and age, the following factors were associated with an increase in serum creatinine: number of cigarettes smoked per day, systolic blood pressure, and maximum internal carotid artery intimal thickness.

CONCLUSIONS

These data suggest that three very preventable or treatable conditions-hypertension, smoking, and prevalent vascular disease, which are associated with large and small vessel disease-are highly associated with clinically important changes in renal function in an older population.

Peritoneal dialysate fill-volumes and hernia development in a cohort of peritoneal dialysis patients

A retrospective case control study was performed on a cohort of 244 peritoneal dialysis patients followed over 5 years to determine whether dialysate fill-volume was associated with hernia development. The laboratory and clinical parameters of patients who developed hernias during this time period were compared with those of patients who did not develop hernias. Information on 27 patients who developed hernias was compared with that on 217 patients who did not develop hernias. Dialysate fill-volume was similar between groups (2.2 +/- .3 L for patients with hernias vs. 2.2 +/- .3 L for controls). Three patients with fill-volumes of 1.5 L developed hernias, and no patients with fill-volumes of 3 L developed hernias. Age, duration of time on dialysis, and body surface area were also similar between groups. This investigation could not find a relationship between fill-volume and hernia formation. From this study it would appear that physicians should not hesitate to increase fill-volume based on concerns of hernia development.

A reciprocal graph to plot the reciprocal serum creatinine over time

In patients who have a linear decline in renal function over time, plotting the reciprocal serum creatinine versus time has been found to be useful in monitoring renal disease progression and predicting the start of dialysis. Unfortunately, producing such plots is cumbersome because of the inherent difficulties of plotting a reciprocal number on standard graph paper. This technical note presents a graph in which the y-axis is represented as a reciprocal axis. In this manner, one is able to directly plot the serum creatinine over time and must not rely on plotting the reciprocal value. This approach may make the plotting of such data easier for the nephrologist and make this clinical tool more useful.

An international study of patient compliance with hemodialysis

CONTEXT

International differences in compliance of patients undergoing hemodialysis are poorly characterized and could contribute to international survival differences.

OBJECTIVE

To compare international differences in patient compliance with hemodialysis treatments.

DESIGN

A prospective observational study of patients undergoing hemodialysis in 1995 and a cross-sectional survey of health care professionals caring for hemodialyzed patients in 1996.

SETTING AND PATIENTS

Four dialysis centers in the southeastern United States with 415 patients undergoing hemodialysis, 1 center in Sweden with 84 patients, and 4 centers in Japan with 194 patients participated in the prospective observational study. In the cross-sectional survey, nurses and nephrologists from the United States (n = 49), Japan (n = 21), and Sweden (n = 16) responded to questions regarding the compliance of their patients undergoing hemodialysis.

MAIN OUTCOME MEASURES

Percentage of patients who miss a dialysis treatment and number of missed dialysis treatments.

RESULTS

Of 415 US patients, 147 missed 699 treatments over a 6-month period (28.1 missed treatments per 100 patient-months or 2.3% of all prescribed treatments). During a 3-month period, there were 0 missed treatments per 100 patient-months for patients from Japan and 0 missed treatments per 100 patient-months for patients from Sweden (P<.001). In the cross-sectional survey, the mean (SD) estimated percentage of patients missing a treatment per month was 4% (3%) for the United States, 0% for Japan, and 0.1% (3%) for Sweden (P<.001).

CONCLUSIONS

Noncompliance is much more common in US patients undergoing hemodialysis than Swedish and Japanese patients. The implications of these results for international differences in survival deserve further study.

Sudden and cardiac death rates in hemodialysis patients

BACKGROUND

Sudden and cardiac death (including death from congestive heart failure, myocardial infarction, and sudden death) are common occurrences in hemodialysis patients. The intermittent nature of hemodialysis may lead to an uneven distribution of sudden and cardiac death throughout the week. The purpose of this study was to assess the septadian rhythm of sudden and cardiac death in hemodialysis patients.

METHODS

Data from the United States Renal Data System (USRDS) were obtained to examine the day of death for United States hemodialysis and peritoneal dialysis patients from 1977 through 1997. The days of death were also determined for patients in the Case Mix Adequacy Study of the USRDS.

RESULTS

There was an even distribution of sudden and cardiac deaths for patients on peritoneal dialysis, and hemodialysis patients dying of noncardiac deaths also had an even distribution. For all hemodialysis patients, Monday and Tuesday were the most common days of sudden and cardiac death. For patients in the Case Mix Adequacy Study designated as Monday, Wednesday, and Friday dialysis patients, 20.8% of sudden deaths occurred on Monday compared with the 14.3% expected (P = 0.002). Similarly, 20.2% of cardiac deaths occurred on Monday compared with the 14.3% expected (P = 0.0005). Similar trends were found on Tuesday for Tuesday, Thursday, and Saturday dialysis patients.

CONCLUSIONS

The intermittent nature of hemodialysis may contribute to an increased sudden and cardiac death rate on Monday and Tuesday for patients enrolled in the USRDS.

A comparison of the calcium-free phosphate binder sevelamer hydrochloride with calcium acetate in the treatment of hyperphosphatemia in hemodialysis patients

Current phosphate binders used in hemodialysis patients include calcium-based binders that result in frequent hypercalcemia and aluminum-based binders that result in total body aluminum accumulation over time. This investigation describes the use of a calcium- and aluminum-free phosphate-binding polymer in hemodialysis patients and compares it with a standard calcium-based phosphate binder. An open-label, randomized, crossover study was performed to evaluate the safety and effectiveness of sevelamer hydrochloride in controlling hyperphosphatemia in hemodialysis patients. After a 2-week phosphate binder washout period, stable hemodialysis patients were administered either sevelamer or calcium acetate, and the dosages were titrated upward to achieve improved phosphate control over an 8-week period. After a 2-week washout period, patients crossed over to the alternate agent for 8 weeks. Eighty-four patients from eight centers participated in the study. There was a similar decrease in serum phosphate values over the course of the study with both sevelamer (-2.0 +/- 2.3 mg/dL) and calcium acetate (-2.1 +/- 1.9 mg/dL). Twenty-two percent of patients developed a serum calcium greater than 11.0 mg/dL while receiving calcium acetate, versus 5% of patients receiving sevelamer (P < 0.01). The incidence of hypercalcemia for sevelamer was not different from the incidence of hypercalcemia during the washout period. Patients treated with sevelamer also sustained a 24% mean decrease in serum low-density lipoprotein cholesterol levels. Sevelamer was effective in controlling hyperphosphatemia without resulting in an increase in the incidence of hypercalcemia seen with calcium acetate. This agent appears quite effective in the treatment of hyperphosphatemia in hemodialysis patients, and its usage may be advantageous in the treatment of dialysis patients.

Administration and pharmacokinetics of high-dose cyclophosphamide with hemodialysis support for allogeneic bone marrow transplantation in acute leukemia and end-stage renal disease

We report a patient with pre-existing end-stage renal disease (ESRD) who underwent successful matched related donor allogeneic bone marrow transplantation for AML in second complete remission (CR2) using conditioning with high-dose cyclophosphamide (CY, 60 mg/kg/day x 2) and TBI (165 cGy twice daily x 4 days). The timing of hemodialysis after high-dose CY was extrapolated from available data on the pharmacokinetics of high-dose CY and hemodialysis clearance of conventional dose CY and its metabolites. Pharmacokinetic analyses indicated that the elimination of high-dose CY and its alkylating metabolites is impaired in ESRD but is cleared with hemodialysis. The patient's early post-transplant course was uncomplicated, and WBC and platelet engraftment occurred by day +22. Bone marrow examination on day +25 showed trilineage engraftment with no AML; cytogenetics showed 100% donor karyotype. The patient remains in remission with 100% donor karyotype at 3 years post transplant. Clinical results indicate that the administration of high-dose CY is feasible with hemodialysis support for patients with ESRD.

Dialysis modality and delayed graft function after cadaveric renal transplantation

The purpose of this investigation was to compare outcomes in the immediate posttransplant period for hemodialysis (HD) and peritoneal (PD) dialysis patients who received cadaveric renal transplantation. Data were obtained from the United Network of Organ Sharing on all cadaveric graft recipients who were dialysis-dependent at the time of transplantation between April 1994 and December 1995. Baseline characteristics were compared between groups, and multivariate logistic regression was performed with outcome measures including urine production in the first 24 h posttransplantation (U24), requirement for dialysis in the first week posttransplant (FWDIAL), and treatment for acute rejection during the initial hospitalization. The odds of oliguria (not producing urine in the first 24 h) were 1.49 (1.28 to 1.74) times higher in HD versus PD patients. After adjustment for other comorbid conditions including age, gender, race, HLA mismatch, time on dialysis, panel-reactive antibodies, and cold and warm ischemia time, the odds of oliguria were 1.60 (1.14 to 2.25) times higher in black HD patients compared with PD patients and 1.29 (1.06 to 1.57) times higher in white HD patients. In a similar manner, after adjustment for significant comorbid conditions, the odds of requiring dialysis in the first week were 1.56 (1.22 to 2.0) times higher in black HD patients versus PD patients and 1.40 (1.21 to 1.60) times higher in white HD patients. The rate of acute rejection was similar during the first hospitalization. These results suggest that there is an association between hemodialysis and delayed graft function. Differences in biocompatibility between the two modalities could potentially be responsible.

Frequency and causes of discrepancy between Kt/V and creatinine clearance

This study examines the frequency of discrepancy between Kt/V urea and creatinine clearance (Ccr) measurements in patients on peritoneal dialysis (PD) and the reasons for this discrepancy.

DESIGN

Nonrandomized, retrospective data analysis.

SETTING

Single PD unit of a university teaching hospital.

PATIENTS

All adult patients receiving PD at our center from January 1995 to December 1996.

METHODS

Actual (a) and desired (d) body weight (BW) were used to calculate urea volume of distribution (V) and body surface area (BSA). Patients were divided into four groups based upon their total small solute clearances (Kt/V and Ccr, normalized by actual weight) and three additional groups based upon actual/desired (a/d) body weight ratio. An additional analysis was performed for the subset of anuric patients. Data collected for all patients included the following: total Kt, total Ccr, 4-hour dialysate/ plasma (D/P) creatinine, serum albumin concentration, duration of PD, actual body weight, age, and height.

RESULTS

Twenty-three percent of the clearance measurements in our study were discrepant, defined as having values for either Kt/V or Ccr (but not both) above the accepted targets of Kt/V > or = 2.0/wk and Ccr > or = 60 L/wk/ 1.73 m2. Patients with both values above target are more likely to have higher residual renal function. Patients who are significantly less than BWd and patients on PD for a longer time are more likely to have adequate Kt/V but not Ccr. Furthermore, patients who are less than 90% or greater than 110% of BWd have markedly different values for Kt/V and Ccr when BWa versus BWd values are used.

CONCLUSIONS

Kt/V and Ccr values are frequently discrepant; a number of factors affect these two measurements to varying degrees, including weight, degree of residual renal function, and duration of PD.

A randomized trial of sevelamer hydrochloride (RenaGel) with and without supplemental calcium. Strategies for the control of hyperphosphatemia and hyperparathyroidism in hemodialysis patients

OBJECTIVE

We have previously shown sevelamer hydrochloride (RenaGel) to be an effective and well-tolerated treatment for hyperphosphatemia in hemodialysis patients.

PATIENTS AND METHODS

We performed a randomized clinical trial to compare the efficacy of RenaGel alone and RenaGel with calcium, using the serum phosphorus concentration and intact parathyroid hormone (PTH) as the principal outcomes of interest. Calcium (900 mg elemental) was provided as a once-nightly dose on an empty stomach. 71 patients were randomized and included in the intent-to-treat population; 55 completed the 16-week study period (2 weeks washout, 12 weeks treatment, 2 weeks washout). 49% of subjects were taking vitamin D metabolites.

RESULTS

Serum phosphorus and PTH rose significantly when patients stopped their phosphate binders during both washout periods. RenaGel and RenaGel with calcium were equally effective at reducing serum phosphorus (mean change -2.4 mg/dL vs. -2.3 mg/dL). RenaGel with calcium was associated with a small increase in serum calcium (mean change 0.3 mg/dL vs. 0.0 mg/dL in RenaGel group, P = 0.09) that was not statistically significant. During the treatment phase, the reduction in PTH tended to be greater in the RenaGel with calcium group (median change -67.0 vs. -22.5 pg/mL in RenaGel group, P = 0.07). Non-users of vitamin D metabolites treated with RenaGel with calcium experienced a significant decrease in PTH (median change -114.5 vs. -22 pg/mL in RenaGel group, P = 0.006). Adverse events were seen with equal frequency in both groups, being generally mild in intensity, and rarely attributable to the drugs.

CONCLUSION

We conclude that RenaGel and RenaGel with calcium are similarly effective in the treatment of ESRD-related hyperphosphatemia. Provision of supplemental calcium or metabolites of vitamin D with RenaGel may enhance control of hyperparathyroidism.

A case control study of proximal calciphylaxis

The purpose of this investigation was to describe the clinical presentation of nine patients with calciphylaxis involving the proximal lower extremities or trunk and to compare the clinical characteristics of these patients with those of 347 hemodialysis patients from the same geographic area. Patients were identified primarily through a computer search of pathology records, identifying patients with the term "calciphylaxis" in the biopsy report. All patients had pathologic specimens consistent with calciphylaxis. All the calciphylaxis patients were white and were markedly obese. While two patients had markedly elevated parathyroid hormone levels, most patients did not show severe derangements of calcium phosphate metabolism compared with other dialysis patients. A logistic regression model identified body mass index and low serum albumin 3 months before diagnosis as being highly associated with a diagnosis of calciphylaxis. Diabetes mellitus and parameters of calcium-phosphate metabolism were not significantly associated with proximal calciphylaxis. These findings suggest that white race, morbid obesity, and poor nutritional status are associated with proximal calciphylaxis in dialysis patients.

Clinical correlates of hypertensive end-stage renal disease

Although there has been much discussion regarding the etiology of hypertensive renal disease, clinical characteristics of this condition have not been thoroughly studied. The purpose of this investigation was to identify clinical correlates of hypertensive end-stage renal disease (ESRD) in a population of patients older than 50 years and to compare these clinical findings with those in a group of ESRD patients with certain known disorders (established diagnoses). Data regarding demographics, cause of ESRD, educational level, presence of diabetes mellitus, angina, myocardial infarction, and peripheral vascular disease were obtained from the Southeastern Kidney Council for patients starting renal replacement therapy between January 1, 1990, and August 1, 1996. Clinical characteristics were compared for white and black patients. Demographic variables and comorbid conditions were compared between groups with general linear regression or logistic regression contrast techniques. A logistic regression model was formed with hypertensive ESRD or established diagnoses as the outcome variable and comorbid and socioeconomic variables as the independent variables. Hypertensive ESRD was diagnosed in 24% of white and 38% of black patients, while established diagnoses were present in 17% of white and 7% of black ESRD patients. The most common established diagnoses were polycystic kidney disease, specified glomerulonephritis, and nephrolithiasis or obstruction. In a logistic regression model, white patients were found more likely to be classified as having hypertensive ESRD if they were older, suffered from angina and other forms of atherosclerosis, smoked, and were less educated. White patients with hypertensive ESRD were more than 2.4 times as likely to suffer from angina as patients with established diagnoses. For black patients, the presence of peripheral vascular disease and female gender were associated with an increased chance of being diagnosed as having hypertensive ESRD. The results of this investigation show that there is a strong association between atherosclerosis and hypertensive ESRD in older white patients. In black patients, the association between atherosclerosis and hypertensive ESRD was also present, but not as strong. The unique association of hypertensive ESRD with atherosclerosis suggests that atherosclerosis is a risk factor for chronic renal failure and that a primary renal microvascular disorder may lead to both hypertension and progressive renal insufficiency.

Is renal revascularization in diabetic patients worthwhile?

PURPOSE

This retrospective review describes surgical management of atherosclerotic renovascular disease (RVD) in hypertensive adults with diabetes mellitus.

METHODS

From July 1987 through July 1995, 54 consecutive hypertensive diabetics (mean 213/103 mm Hg; mean medications three drugs) requiring either insulin (16 patients) or oral hypoglycemic therapy (38 patients) had operative repair of atherosclerotic RVD. Renal dysfunction (serum creatinine [SCr] > or = 1.3 mg/dl) was present in 82% of patients (mean SCr 2.4 mg/dl). Associations between blood pressure and renal function response to operation and preoperative parameters were examined. Clinical characteristics, response to operation, and dialysis-free survival were compared with those of 291 nondiabetic patients.

RESULTS

Four (7.4%) operative deaths occurred. Among 50 survivors blood pressure response was considered cured or improved in 72% and unchanged in 28%. Of 42 patients with renal dysfunction 40% had improved function including three patients removed from dialysis. No preoperative parameter examined demonstrated a significant association with blood pressure or renal function response. During follow-up 10 additional patient deaths occurred, and eight patients progressed to dialysis dependence. Time to death or dialysis was associated with preoperative estimates of glomerular filtration (p = 0.03) and the change in estimates of glomerular filtration after operation (p = 0.01). Compared with 291 nondiabetics, the diabetic group had no statistical difference in improved function response (40% vs 51%, p = 0.21); however, diabetics had a significantly lower rate of beneficial blood pressure response (72% vs 89%, p = 0.01) and an increased risk of dialysis or death during follow-up (p = 0.02). By multivariate analysis independent predictors of time to death or dialysis included the presence of diabetes mellitus, patient age, history of congestive heart failure, and increased serum creatinine.

CONCLUSIONS

Most of the selected diabetic patients had a beneficial blood pressure response after undergoing operative repair of atherosclerotic RVD, albeit at a lower rate compared with nondiabetics. In diabetics poor renal function before and after operation was associated with progression to dialysis and death. Improved renal function after operation was associated with improved survival; however, function response to renal revascularization was difficult to predict.

Utilization of inpatient and outpatient resources for the management of hemodialysis access complications

Complications of hemodialysis accesses are a major cause of morbidity in chronic hemodialysis patients. Although several investigators have reported on the utilization of inpatient services for hemodialysis access complications, there is a paucity of data regarding the utilization of outpatient services and temporary accesses for these complications. In this retrospective study, we identified all access-related inpatient admissions and outpatient encounters and procedures performed in an incident cohort of hemodialysis patients. Eighty-eight patients were followed for an average of 487.4 +/- 316.9 days, for a total of 119.1 patient-years of risk. The mean age was 57.0 +/- 14.6 years, with 55% females and 65% blacks; 31% of patients had diabetes mellitus as the primary cause of end-stage renal disease. Patients were referred to our nephrology practice a median of 56 days prior to the placement of a hemodialysis access and a median of 76 days prior to the initiation of hemodialysis. At the initiation of hemodialysis, 48 native arteriovenous fistulas and 40 polytetrafluoroethylene grafts were placed. Only 28 patients (31.8%) had a permanent access placed at least 14 days before the start of hemodialysis, resulting in the placement of 93 temporary accesses during the first week of dialysis therapy. Because of access complications, 21 patients had failure of their primary access, requiring the placement of 33 additional permanent accesses, including six native arteriovenous fistulas, 23 polytetrafluoroethylene grafts, and four permacaths, or an average of 0.28 new accesses per patient-year of risk. During the study period, 45 patients (51%) had at least one access complication. To manage these access complications, 25 fistulograms (0.21 per patient-year of risk) were performed and 116 additional temporary accesses (0.97 per patient-year of risk) were placed, including 50 femoral (43.1%), 52 subclavian (44.8%), and 14 internal jugular (12.1%) catheters. A total of 2.43 inpatient days and 1.05 outpatient encounters per year of patient risk were directly attributed to admissions solely for access complications. There is significant utilization of outpatient services, temporary accesses, and fistulograms in the management of hemodialysis access complications. These services should be included whenever a review of hemodialysis access procedures or costs are undertaken.

Survival of patients undergoing renal replacement therapy in one center with special emphasis on racial differences

This study compared racial differences in end-stage renal disease (ESRD) in 550 patients starting renal replacement therapy at a large academic dialysis center between January 1, 1990, and December 31, 1993, with follow-up through December 31, 1994. Patient groups were compared with respect to cause of ESRD, comorbid factors at the start of dialysis therapy, choice of modality, transplantation rate, and survival. Fifty-eight percent of the patients were white and 42% were African-American. There was a similar distribution of causes of ESRD between races. African-American patients were less likely to choose peritoneal dialysis as initial therapy (11.6% v 29.3%; P < 0.001) and were less likely to change dialysis modality. Transplantation rates were significantly different between African-American and white patients (9.3% v 27.6%; P < 0.001). African-Americans less frequently received living-related, living-nonrelated, and cadaveric renal transplants. Given differences in transplantation rates and in survival of transplanted patients versus patients on dialysis, survival analysis was performed without censoring for transplantation. A multivariate Cox proportional hazards model was formed, and the following were identified as being significant independent predictors of survival: age, race, age-race interaction, serum albumin at the start of dialysis, activity level at the start of dialysis, and presence of congestive heart failure and cancer. Age had little effect on survival among African-American patients, while it was a significant predictor of survival in white patients. In the group of patients starting dialysis before the age of 30 years, African-American patients had a significantly increased mortality risk compared with white patients. However, white patients older than 50 years had a higher mortality risk; this risk difference increased with age. Racial differences in mortality among older white patients could not be explained by differences in comorbid conditions, transplantation rates, or withdrawal from dialysis.

An elevated ratio of measured to predicted creatinine production in CAPD patients is not a sensitive predictor of noncompliance with the dialysis prescription

OBJECTIVE

To determine the effect a period of "intentional noncompliance" in stable continuous ambulatory peritoneal dialysis (CAPD) patients has on the ratio of measured to predicted creatinine generation.

DESIGN

Prospective study that compares baseline to noncompliant periods in individual CAPD patients.

PATIENTS

Nine chronic, stable CAPD patients.

STUDY DESIGN

At baseline, measured creatinine production and adequacy parameters (KT/V, creatinine clearance, lean body mass, and protein equivalent of nitrogen appearance) were calculated from 24-hour collections of dialysate and urine while patients were performing their routine dialysis prescriptions. After three days of intentional noncompliance (one less exchange/day) the patients repeated their 24-hour collections, again performing their routine number of exchanges. Measured creatinine production and adequacy parameters were again calculated. Predicted creatinine production for each patient was calculated from standard equations. All parameters at baseline were compared to corresponding parameters after intentional noncompliance.

RESULTS

In all patients, except one where there was no change, there was a statistically significant increase in not only the ratio of measured to predicted creatinine production but also all other parameters.

CONCLUSION

As suspected by previous investigators, this study suggests that one cause of an elevated ratio of measured to predicted creatinine production may be a recent period of noncompliance with the patient's dialysis prescription. However, these data suggest that an isolated ratio of measured to predicted creatinine generation is not a sensitive predictor of noncompliance with the peritoneal dialysis prescription.

Case report: analgesic nephropathy: a soda and a powder

Analgesic nephropathy has long been considered a potentially preventable cause of renal disease. Early reports were described in patients who consumed analgesics containing phenacetin. In recent data, the removal of phenacetin from analgesic preparations resulted in a reduction in analgesic-induced end stage renal disease in Europe and Australia. However, a reduction in the incidence of analgesic nephropathy has not occurred uniformly, suggesting that phenacetin is not the sole cause. Current data raise concerns regarding adverse renal effects of acetaminophen and nonsteroidal antiinflammatory drugs. Aspirin taken alone may be of least concern. The diagnosis of analgesic nephropathy is suggested in subjects with chronic renal failure, a history of daily consumption of analgesic preparations, small bumpy kidneys, and renal papillary necrosis or chronic interstitial nephritis. However, the spectrum of disease may be changing, because these agents also may increase the risk of cardiovascular disease and chronic renal disease due to nephrosclerosis, glomerulonephritis, and diabetes mellitus. Potential pathogenetic mechanisms in analgesic nephropathy include direct cellular injury induced by analgesics, prostaglandin inhibition with reduction or redistribution of renal blood flow, and interesting new concepts regarding the role of caffeine in increasing oxygen demand and reducing oxygen supply in the medulla. The primary goal of therapy is discontinuation of analgesic consumption. Because of the association between analgesic intake and uroepithelial tumors, surveillance of patients for neoplasm is suggested.

Xanthine analysis in biological fluids by capillary electrophoresis

Xanthine, a precursor of uric acid, is measured here in serum, urine, and cerebrospinal fluids by capillary electrophoresis (CE) after deproteinization with acetonitrile. The migration time is about 7.5 min with a minimum detection limit of 0.4 mg/l. Different purines and pyrimidines did not interfere with the determination. The method demonstrates the suitability of the CE for determination of small molecules present in a complex matrix at levels of ca. 1mg/l. It also demonstrates that acetonitrile deproteinization is a simple and effective method for preparing samples for CE, allowing a large volume to be introduced into the capillary.

Renovascular disease in older patients beginning renal replacement therapy

Renovascular disease (RVD) in older patients can cause progressive renal insufficiency and even end-stage renal disease (ESRD). The frequency of this clinical problem is not well defined. Renal duplex sonography (RDS) correctly identifies the presence of RVD with an overall accuracy of approximately 95%. Therefore, the purpose of this study was to utilize RDS as a noninvasive tool to identify the presence of critical RVD (> or = 60% diameter-reducing stenosis or occlusion) in patients 50 years of age or older beginning renal replacement therapy. A total of 53 consecutive participating patients were prospectively interrogated. Complete interrogations occurred in 45 of the 53 patients (85%), and 92 of the 103 kidneys (89%). Critical RVD was noted in 10 of 45 patients (22%). RVD was bilateral in 5 patients, unilateral in 5 patients, and there were 4 renal artery occlusions noted. All patients with critical RVD were white (10 of 25 white patients or 40%). Total pack years of smoking as well as associated cardiovascular and cerebrovascular conditions were greater in those patients with critical RVD compared to those without. These results indicate that RDS remains technically feasible as renal blood flow and function decline. Unsuspected RVD possibly contributory to renal insufficiency exists in a significant number of primarily white patients 50 years of age or older beginning renal replacement therapy. These patients are generally smokers with a high frequency of associated extrarenal atherosclerosis The addition of RVD as a separate category of disease causing ESRD would improve U.S. Renal Data System ESRD classification. RVD should be recognized as a cause of ESRD.

Polyol pathway mediates high glucose-induced collagen synthesis in proximal tubule

The polyol pathway in diabetes is activated in tissues that are not dependent on insulin for glucose uptake. To examine the role of the polyol pathway in renal extracellular matrix accumulation, we incubated murine proximal tubule cells in either normal or high glucose concentration in the presence or absence of the aldose reductase inhibitor sorbinil. Rising medium glucose from 100 to 450 mg/dl for 72 hours increased cell sorbitol levels sevenfold. Addition of 0.4 mM sorbinil reduced sorbitol content to virtually undetectable levels as measured by gas chromatography. Sorbinil (0.1 to 0.2 mM) also reduced the secretion of collagens types IV and I in the high glucose concentration after 48 to 72 hours but had no appreciable effect in the normal glucose concentration. Concordantly, 0.1 mM sorbinil inhibited the high glucose-induced stimulation of alpha 1(IV) and alpha 2(I) mRNA levels without affecting levels in normal glucose concentration. To study the role of transcriptional activation of collagen genes, we transfected proximal tubule cells with a chloramphenicol acetyltransferase (CAT) reporter gene linked to the promoter and regulatory elements of alpha 1(IV) gene. CAT activity increased several-fold in the cells grown in the high versus normal glucose concentration; this transcriptional activation in culture media containing high glucose concentration was reduced by treatment of the cells with 0.1 mM sorbinil. Thus, high ambient glucose activates the polyol pathway in proximal tubule cells, and may mediate the high glucose-induced stimulation of gene expression for collagens types IV and I.(ABSTRACT TRUNCATED AT 250 WORDS)

Survival of elderly men with congestive heart failure

Congestive heart failure (CHF) is the most common discharge diagnosis for elderly patients. The survival of elderly (age greater than or equal to 75 years) patients with CHF has not recently been reported, especially with reference to left ventricular ejection fraction (LVEF). A patient database was searched for the diagnosis of CHF and then screened for age greater than or equal to 75, Framingham Criteria for CHF and an LVEF evaluation. Ninety-four men fitted all criteria, including a minimum potential follow-up of 3 years. Life-table analysis was employed to compare their survival experience to an expected survival based on a sex- and age-equivalent subset of the 1980 Census data. Causes of death were determined from autopsy, medical records or death certificates. Mean age at onset of CHF was 82.5. Forty-three per cent had an LVEF greater than or equal to 0.45. There was no difference in the prevalence of potential aetiologies between those with LVEF greater than or equal to 0.45 versus LVEF less than 0.45. Life-table analysis revealed that CHF patients had a worse survival than controls for the first 5 years after diagnosis, attributable primarily to a high first-year mortality (28%) for the CHF group. There was no difference in survival between the LVEF greater than or equal to 0.45 and LVEF less than 0.45 groups.

Interactions of molecules with nucleic acids. X. Covalent intercalative binding of the carcinogenic BPDE I(+) to kinked DNA

A theoretical model is proposed for the covalent binding of (+) 7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene denoted by BPDE I(+), to N2 on guanine. The DNA must kink a minimum of 39 degrees to allow proper hybrid configurations about the C10 and N2 atoms involved in bond formation and to allow stacking of the pyrene moiety with the non-bonded adjacent base pair. Conservative (same sugar puckers and glycosidic angles as in B-DNA) and non-conservative (alternating sugar puckers as in intercalation sites) conformations are found and they are proposed structures in pathways connecting B-DNA, an intercalation site, and a kink site in the formation of a covalently intercalative bound adduct of BPDE I(+) to N2 on guanine. Stereographic projections are presented for (3') and (5') binding in the DNA. Experimental data for bending of DNA by BPDE, orientation of BPDE in DNA and unwinding of superhelical DNA is explained. The structure of a covalent intercalative complex is predicted to result from the reaction. Also, an anti----syn transition of guanine results in a structure which allows the DNA to resume its overall B-form. The only change is that guanine has been rotated by 200 degrees about its glycosidic bond so that the BPDE I(+) is bound in the major groove. The latter step may allow the DNA to be stored with an adduct which may produce an error in the genetic code.