Characterizing cognitive control abilities in children with 16p11.2 deletion using adaptive 'video game' technology: a pilot study

Assessing cognitive abilities in children is challenging for two primary reasons: lack of testing engagement can lead to low testing sensitivity and inherent performance variability. Here we sought to explore whether an engaging, adaptive digital cognitive platform built to look and feel like a video game would reliably measure attention-based abilities in children with and without neurodevelopmental disabilities related to a known genetic condition, 16p11.2 deletion. We assessed 20 children with 16p11.2 deletion, a genetic variation implicated in attention deficit/hyperactivity disorder and autism, as well as 16 siblings without the deletion and 75 neurotypical age-matched children. Deletion carriers showed significantly slower response times and greater response variability when compared with all non-carriers; by comparison, traditional non-adaptive selective attention assessments were unable to discriminate group differences. This phenotypic characterization highlights the potential power of administering tools that integrate adaptive psychophysical mechanics into video-game-style mechanics to achieve robust, reliable measurements.

Feedback mechanisms of arterial pressure control

Arterial blood pressure varies very little among human beings and most other mammals for that matter. This suggests that a powerful control scheme is at work; it becomes more apparent when we break the various feedback loops and observe the excursions of blood pressure in the absence of any control. Two important control loops are found in the baroreceptor reflexes operating over the short term and the kidneys operating over the long term. The aortic and carotid baroreceptors stabilize pressure, preventing short-term fluctuations; when this control loop is surgically removed, lability increases with little change in the average pressure. Over the long term, the kidneys determine the average level of arterial pressure; when they are removed, pressure slowly drifts up and down as fluid is inadvertently accumulated or lost. There are several possible connections between the function of the kidneys and arterial pressure, including the release of vasoactive endocrines by the kidney and the adjustment of body fluids via salt and water excretion. Because salt excretion and water excretion often change in parallel, it has been difficult to identify the individual importances of each. However, we found that increasing the sodium stores of the body while holding volume constant does not produce hypertension, expanding fluid volume while maintaining or actually decreasing sodium concentration does lead to hypertension. Hence, when the kidneys are normal, long-term stability results from this loop: fluid volumes alter arterial pressure; pressure alters renal excretion; excretion alters fluid volumes.

Increase in plasma esterified F2-isoprostanes following intravenous iron infusion in patients on hemodialysis

BACKGROUND

In epoetin-treated dialysis patients, currently iron is administered by the intravenous route to maintain optimum erythropoiesis. However, rapid infusion of iron in excess of transferrin binding capacity can lead to the availability of unbound iron that can theoretically catalyze peroxidation of lipids, such as low-density lipoprotein (LDL), which when oxidatively modified is proinflammatory and promotes atherogenesis.

METHODS

To address this issue, our study used one of the most specific measures of lipid peroxidation available, namely gas chromatography/mass spectometry (GC/MS) analysis of F2-isoprostanes. Using a prospective design, blood samples were collected 15 minutes before (pre) and 30 minutes after (post) a one-hour infusion of 700 mg bolus of intravenous iron in 22 adult home-hemodialysis patients on a non-hemodialysis day.

RESULTS

With iron-dextran infusion, serum iron markedly increased (mean +/- SE, 42 +/- 4 vs. 311 +/- 92 microg/dL, P < 0.0001) and exceeded the transferrin saturation of 100% in 22 out of 22 patients (pre 23 +/- 3 vs. post 165 +/- 8%, P < 0.0001). Plasma concentrations of free F2-isoprostanes did not change significantly following infusion of iron (pre 40 +/- 5 vs. post 39 +/- 6 pg/mL). However, levels of F2-isoprostanes esterified in plasma lipoproteins increased significantly in the postinfusion samples (pre 199 +/- 19 vs. post 233 +/- 25 pg/mL, P < 0.004). Pre-infusion levels of serum iron correlated directly with pre-infusion levels of esterified F2-isoprostanes (r = 0.56, P = 0.008), which persisted in the postinfusion period (r = 0.43, P = 0.04). However, there was no correlation between esterified F2-isoprostanes and serum ferritin levels. In the last four patients in whom blood samples were collected five hours after the intravenous iron infusion, there were further increases in esterified F2-isoprostanes that very closely correlated with postinfusion serum iron levels (r = 0.99, P = 0.013). In a control study, the in vitro addition of iron dextran to blood samples did not increase free or esterified F2-isoprostanes, suggesting that the increase in esterified F2-isoprostanes seen in vivo after iron infusion in patients is not due to a procedural artifact.

CONCLUSION

Collectively our data suggest that high levels of serum iron appearing soon after a large bolus of iron infusion is associated with significant, albeit modest, increases in levels of F2-isoprostanes esterified in plasma lipoproteins that tended to increase with time. Although it is uncertain whether this degree of lipid peroxidation may have deleterious effects, it may be sagacious to explore whether this can be prevented by slow infusion of frequent smaller doses of iron and, if necessary, along with administration of antioxidants.

Are conventional cardiovascular risk factors predictive of two-year mortality in hemodialysis patients?

BACKGROUND

In general population hypertension, diabetes mellitus, overweight, hyperlipidemia and smoking are well-established risk factors for cardiovascular disease. However, the effect of these conventional risk factors on cardiovascular disease and mortality of patients on hemodialysis is not well understood. Indeed, some risk factors such as high blood pressure, hyperlipidemia and excess weight have been recently claimed to correlate with improved survival.

OBJECTIVE

This study was undertaken to define the prevalence of these conventional risk factors in 453 hemodialysis patients, predominantly African-Americans, to determine their influence on two-year survival.

RESULT

High cholesterol was found in 30% of the patients, high LDL-cholesterol in 25% and high triglycerides in 16%. Lipoprotein(a) (LP(a)) was elevated in 68% of the patients. 31% of our patients had predialysis mean arterial blood pressure (MAP) over 114, and 25% were obese based on a body mass index (BMI) over 30, 26% were diabetic and 25% were active smokers. Smoking was more common among our male and Caucasian patients. The aggregate score for the risk factors were 2.4+/-0.1 per patient, which increased to 3.2+/-0.1 in patients with obesity or diabetes, to 3.0+/-0.1 with hypertension and to 2.8+/-0.1 with active smoking. In multivariate Cox model analysis, prealbumin, body weight and blood pressure showed a positive correlation with two-year survival whereas diabetes mellitus had a negative correlation. Hyperlipidemia did not correlate to patients' two-year mortality. Smoking was associated with higher mortality, but that did not reach statistical significance.

CONCLUSION

Conventional risk factors at least over a two-year period do not readily account for the higher mortality of a group of predominantly African-American patients on hemodialysis. The lack of prediction is speculated to be partly due to the overriding beneficial effects of better nutrition and due to the presence of other yet to be well-defined factors such as hyperhomocysteinemia, oxidative stress, coronary calcification, hitherto unidentified uremic toxins or a combination of these factors.

Anemia and iron target realization in 1998: clinical management of anemia in 1,639 patients on hemodialysis

Anemia management in hemodialysis patients continues to evolve, and recently, greater emphasis has been placed on the wider use of intravenous iron to maintain adequate iron levels. This survey provides scarcely available yet potentially useful information on the clinical treatment of anemia in a large cohort of hemodialysis patients. The erythropoietin and iron administration details and pertinent laboratory measurements from 1,639 patients were analyzed for the month of December, 1998. A standardized protocol had been used in that erythropoietin was begun at a total weekly dose of 150 U/kg IV or 100 U/kg subcutaneously and was then adjusted to maintain a hematocrit (Hct) of 33-36%. Iron supplements, oral, IV, or both, were administered to maintain percent transferrin saturation (TSAT) at 20-30% and/or a serum ferritin of 100-500 ng/ml. No intravenous iron was administered if the ferritin was more than 500 ng/ml. Although 82% of patients were on iron supplementation and, among them, 58% were on IV iron, the percentage of patients with TSAT >20, i.e., bioavailable iron, was only 51%. The serum ferritin was high at 498 +/- 10 ng/ml (mean +/- SEM) and 88% and 10% of patients had serum ferritin >100 and >1,000 ng/ml, respectively, suggestive of sequestration of part of the infused iron. Erythropoietin was administered to 96% of patients, 99.5% by IV route. The latter was consistent with the US dialysis population at large but in variance with DOQI preference for the subcutaneous route. The target Hct range of 33-36 was found in 33%, with a mean Hct of 34.0 +/- 0.12. When the data were reanalyzed by excluding patients who had not been receiving erythropoietin and had not been on dialysis for at least 3 months, the percentage of patients achieving the target Hct increased to 37%. Paired analysis of 875 patients present in 1996 and 1998 showed that, although there was a marked increase in the use of IV iron, the improvement in anemia was modest, and there was evidence for increased iron accumulation. In summary, this 1998 survey on the clinical practice of anemia management in a large hemodialysis population indicates that there is a marked increase in need-based IV iron usage that was associated with modest improvement in anemia and evidence for increased iron storage. A maintenance iron dosing protocol with smaller doses of iron, such as 25 mg of iron dextran per hemodialysis, may make bioavailable iron continuously present for erythropoiesis, yet may reduce the chance for iron catalyzed lipid peroxidation and tissue iron deposition.

Efficacy and side effects of intermittent intravenous and oral doxercalciferol (1alpha-hydroxyvitamin D(2)) in dialysis patients with secondary hyperparathyroidism: a sequential comparison

Most reports on the effectiveness and side effects of oral versus parenteral calcitriol or alfacalcidol in hemodialysis patients with secondary hyperparathyroidism show no advantage of parenteral treatment. The efficacy and safety of intravenous doxercalciferol (1alphaD(2)) were studied in hemodialysis patients with secondary hyperparathyroidism (plasma intact parathyroid hormone [iPTH]: range, 266 to 3,644 pg/mL; median, 707 pg/mL). These results were compared with those of a previous trial using intermittent oral 1alphaD(2); the same 70 patients were entered onto both trials, and 64 patients completed both trials per protocol. Twelve weeks of open-label treatment in both trials were preceded by identical 8-week washout periods. Degrees of iPTH suppression from baseline were similar in the two trials, with iPTH level reductions less than 50% in 89% and 78% of patients during oral and intravenous treatment, respectively. Grouping patients according to entry iPTH levels (<750 and >/=750 pg/mL) showed similar but more rapid iPTH suppression in the low-iPTH groups, whereas longer treatment and larger doses were required by the high-iPTH groups. Highest serum calcium levels averaged 9.82 +/- 0.14 and 9.67 +/- 0.11 mg/dL during oral and intravenous 1alphaD(2) treatment, respectively (P: = not significant [NS]). Prevalences of serum calcium levels greater than 11.2 mg/dL during oral and intravenous treatment were 3.62% and 0.86% of calcium measurements, respectively (P: < 0.001). Highest serum phosphorus levels during oral and intravenous treatment averaged 5.82 +/- 0.21 and 5.60 +/- 0.21 mg/dL, respectively (P: = NS). The percentage of increments in serum phosphorus levels during oral treatment exceeded that during intravenous treatment during 5 of 12 treatment weeks. Thus, intermittent oral and intravenous therapy with 1alphaD(2) reduced iPTH levels effectively and similarly, hypercalcemia was less frequent, and serum phosphorus levels increased less during intravenous than oral 1alphaD(2) therapy, suggesting that intravenous 1alphaD(2) therapy may be advantageous in patients prone to hypercalcemia or hyperphosphatemia.

Risk factor paradox in hemodialysis: better nutrition as a partial explanation

The higher mortality rate in patients on hemodialysis is primarily due to the higher rate of cardiovascular disease. Yet, paradoxically, overweight, hypertension, and hyperlipidemia, which are cardiovascular risk factors in the general population, have been reported to correlate with better patient survival in hemodialysis. To examine whether this "risk factor paradox" in hemodialysis is due to the positive influence of accompanying better nutrition, we prospectively obtained data on fasting lipids, biochemical markers of nutrition, body mass index (BMI), and blood pressure (BP) in 453 hemodialysis patients and related them to 1 year mortality. As previously noted, body weight, blood pressure, and certain serum lipids positively correlated with survival. Serum prealbumin, one of the most sensitive and specific biochemical markers for nutrition, correlated positively with hypercholesterolemia (r = 0.30, p < 0.001) and BMI (r = 0.12, p < 0.02), but not with mean arterial pressure (MAP) (r = 0.01, p = NS). By analysis of variance, patients in the upper tertile (i.e., higher levels) of BMI and cholesterol but not MAP had significantly higher serum prealbumin and creatinine compared with those in the lower tertile. Our data lend support to the hypothesis that, in patients on hemodialysis, the positive effect of higher BMI and hyperlipidemia but not of high BP could be partially explained on the basis of the accompanying better nutrition. Although not proven, correcting risk factors while improving nutrition may offer better outcomes for patients on dialysis.

Race-dependent survival disparity on hemodialysis: higher serum aluminum as an independent risk factor for higher mortality in whites

The mortality rate on hemodialysis therapy remains unacceptably high, and it is worse in whites than blacks. Substantially elevated serum aluminum levels have been shown to predict mortality on hemodialysis. However, whether this is a factor in the race-dependent survival difference on hemodialysis therapy is presently unknown. To determine the relevance of serum aluminum level on race-dependent survival disparity on chronic hemodialysis therapy, 1-year survival of 118 whites was prospectively compared with 473 age- and sex-matched blacks. The variables predictive for survival, including serum aluminum level, were defined separately in whites and blacks using Cox univariate and multivariate analyses. The 1-year mortality rate was significantly greater in whites than blacks (18% versus 12%; P: < 0.001). Serum albumin level, body mass index (BMI), and creatinine level had a positive influence, whereas age had a negative influence on survival in both groups in the univariate analysis. The mean serum aluminum level was significantly greater in whites (n = 118) than blacks (n = 473; 20 +/- 2.3 versus 14 +/- 0.6 [SE] ng/mL; P: = 0.0009) and was not caused by increased duration on dialysis, increased prescription of aluminum-containing phosphate binders, or reduced delivered dose of dialysis. Unlike the blacks, serum aluminum levels had a significant negative influence on the survival of whites, and this persisted in multivariate analysis after controlling for age, sex, diabetes, albumin level, creatinine level, and BMI (relative risk, 1.013; 95% confidence interval, 1.004 to 1.023; P: < 0.007). In summary, this study suggests that whites undergoing hemodialysis may have greater serum aluminum levels than blacks, which might contribute to the whites' greater rate of mortality. Because hyperaluminemia is a modifiable risk factor, studies are required to verify our findings, explore the mechanism of elevated aluminum levels in whites, and test the hypothesis that reducing serum aluminum levels in whites may improve their survival.

Intermittent doxercalciferol (1alpha-hydroxyvitamin D(2)) therapy for secondary hyperparathyroidism

Hypercalcemia and hyperphosphatemia frequently necessitate vitamin D withdrawal in hemodialysis patients with secondary hyperparathyroidism. In short-term trials, doxercalciferol (1alpha-hydroxyvitamin D(2) [1alphaD(2)]) suppressed intact parathyroid hormone (iPTH) effectively with minimal increases in serum calcium and phosphorus (P) levels. This modified, double-blinded, controlled trial examined the efficacy and safety of 1alphaD(2) use in 138 hemodialysis patients with moderate to severe secondary hyperparathyroidism by using novel dose titration; 99 patients completed the study. Hemodialysis patients with secondary hyperparathyroidism were enrolled onto this study, consisting of washout (8 weeks), open-label 1alphaD(2) treatment (16 weeks), and randomized, double-blinded treatment with 1alphaD(2) or placebo (8 weeks). Oral 1alphaD(2) was administered at each hemodialysis session, with doses titrated to achieve target iPTH levels of 150 to 300 pg/mL. Baseline iPTH levels (897 +/- 52 [SE] pg/mL) decreased by 20% +/- 3.4% by week 1 (P: < 0.001) and by 55% +/- 2.9% at week 16; iPTH levels returned to baseline during placebo treatment but remained suppressed with 1alphaD(2) treatment. In 80% of the patients, iPTH level decreased by 70%, reaching the target level in 83% of the patients. Grouping patients by entry iPTH level (<600, 600 to 1,200, and >1,200 pg/mL) showed rapid iPTH suppression in the group with the lowest level; greater doses and longer treatment were required in the group with the highest level. During open-label treatment, serum calcium and P levels were 9.2 +/- 0.84 (SD) to 9.7 +/- 1.05 mg/dL and 5.4 +/- 1.10 to 5.9 +/- 1.55 mg/dL, respectively. During double-blinded treatment, serum calcium levels were slightly greater with 1alphaD(2) than placebo, but P levels did not differ. During double-blinded treatment, 3.26% and 0.46% of serum calcium measurements exceeded 11.2 mg/dL with 1alphaD(2) and placebo, respectively (P: < 0.01); median level was 11.6 mg/dL during hypercalcemia. Intermittent oral 1alphaD(2) therapy effectively suppresses iPTH in hemodialysis patients with secondary hyperparathyroidism, with acceptable mild hypercalcemia and hyperphosphatemia.

Impact of lower delivered Kt/V on the survival of overweight patients on hemodialysis

Impact of lower delivered Kt/V on the survival of overweight patients on hemodialysis.

BACKGROUND

A recent study suggests that overweight (OW) patients on hemodialysis are more likely to receive inadequate doses of dialysis. Because underdialysis is associated with higher mortality, OW patients might be at risk for higher mortality. This is in contrast with our recent observation in which survival was better in OW patients on hemodialysis. The objective of this study was to verify whether being OW was associated with underdialysis and to determine the influence of underdialysis on the survival of OW patients.

METHOD

Kt/V measurements were obtained in 1151 patients on hemodialysis for two consecutive months, and their survival was prospectively followed for nine months. Body weights were defined by body mass index (BMI): OW if BMI was> 27.5, underweight (UW) if BMI was <20, and normal weight (NW) if BMI was 20 to 27.5.

RESULTS

The Kt/V was inversely related to BMI (r = -0. 30, P < 0.0001). Kt/V in the OW patients was significantly lower than Kt/V in the NW or UW patients. By using a Kt/V threshold of 1.2, more patients were underdialyzed in the OW group (24%) than in the NW (15%) or UW (7%) groups. Underdialysis in the whole study group was associated with a 1.6-fold increase in the relative risk (RR) for mortality. The risk was more pronounced (RR, 2.6) in the underdialyzed OW patients compared with adequately dialyzed OW patients. In multivariate analysis, underdialysis in OW patients (RR, 4.3), but not in UW or NW patients, was a significant and independent risk factor for mortality.

CONCLUSION

Our results verify that in the current practice of dialysis prescription, OW patients are less likely to receive adequate dialysis, and, to our knowledge for the first time, suggest that such underdialysis in OW patients might exert a negative influence on their survival. Prospective studies are required to test whether ensuring adequate delivery of dialysis in the OW patients might further improve their survival.

Effects of normal hematocrit on ambulatory blood pressure in epoetin-treated hemodialysis patients with cardiac disease

BACKGROUND

Hypertension is a recognized complication of partial correction of anemia with recombinant human erythropoietin (epoetin) in hemodialysis patients. We used interdialytic ambulatory blood pressure (ABP) monitoring to study the effects of partially corrected anemia versus normal hematocrit (hct) on BP in hemodialysis patients.

METHODS

Repeated interdialytic ABP monitoring was performed for up to one year in 28 chronic hemodialysis patients with cardiac disease who were randomized to achieve and maintain normal hct levels (42 +/- 3%, group A) or anemic hct levels (30 +/- 3%, group B) with epoetin. Routine BP measurements obtained at dialysis treatments were also evaluated.

RESULTS

Mean hct levels were 30.7 +/- 0.7% in group A and 30.6 +/- 0.7% in group B at baseline, then 39.3 +/- 1.2% (group A) and 33.5 +/- 0.6% (group B) at four months, and 42.0 +/- 1.1% (group A) and 30.4 +/- 1.0% (group B) at 12 months. Baseline ABP and routine dialysis unit BP levels were not different between the groups. At 2, 4, 8, and 12 months of follow-up, there were no statistically significant differences in any BP parameters between groups or increases in any BP parameters in either group A or group B patients compared with baseline. At 12 months, the mean nighttime diastolic BP (DBP) in group A patients was slightly but significantly lower than the mean daytime DBP (daytime DBP 76.6 +/- 1.9 mm Hg vs. nighttime DBP 72.9 +/- 2.1 mm Hg, P < 0.05). The mean daytime and nighttime BPs were not different from each other at two, four, and eight months in group A or at any time in group B, and in both groups, most patients had little diurnal change in BP.

CONCLUSION

Correction of hct to normal with epoetin in chronic hemodialysis patients with cardiac disease did not cause increased BP as assessed by interdialytic ABP monitoring or by the measurement of routine predialysis and postdialysis BP. There was little diurnal change in systolic or diastolic BP at baseline or after correction of anemia to normal levels, and although mean nighttime DBP was lower than mean daytime DBP at 12 months in group A, the maintenance of normal hct levels did not affect the abnormal diurnal BP pattern seen at moderately anemic hct levels in most patients.

Influence of excess weight on mortality and hospital stay in 1346 hemodialysis patients

BACKGROUND

Body mass index (BMI) at its extremes contributes to morbidity and mortality in the general population. Its influence on morbidity and mortality in patients on hemodialysis is not clearly defined.

METHODS

The BMI in 1346 patients attending limited-care hemodialysis units across the state of Mississippi was determined, and its relation to one-year mortality and hospital stay was assessed using the Cox proportional hazard model.

RESULTS

Of these patients, 89% were black, and 11% were white. Thirty-eight percent of patients were overweight (BMI > 27.5), and 13% were underweight (BMI < 20). The highest (27.60 +/- 0.29, mean +/- SE) and the lowest (24.54 +/- 0.48) BMI were noted in black females and white males, respectively. BMI, race, hematocrit (Hct), and biochemical markers of better nutrition positively influenced the survival, whereas age, serum globulin, and diabetes had a negative influence. In a Cox multivariate analysis, BMI, age, diabetes, prealbumin, and creatinine, but not race, serum albumin, Hct, or serum globulin, retained significant influence on survival. Compared with the normal weight (BMI between 20 and 27.5), the one-year survival rate was significantly higher in the overweight patients and lower in the underweight patients. With a one-unit increase in BMI over 27.5, the relative risk for dying was reduced by 30% (P < 0.04), and with a one-unit decrease in BMI below 20, the relative risk was increased by 1.6-fold (P < 0.01). Furthermore, underweight patients had significantly lower levels of biochemical markers of nutrition and higher frequency and longer duration of hospital stay.

CONCLUSION

Adequate dialysis with special attention to proper nutrition aimed to achieve the high end of normal BMI may help to reduce the high mortality and morbidity in hemodialysis patients.

Rehabilitation, aging and chronic renal disease

Restorative management of the disabled elderly requires knowledge about realistic functional expectations, in addition to knowledge about a patient's particular disease. Health outlook, especially sense of control, should also be assessed because rehabilitation depends on the patient's active participation. A comparison of 349 older end-stage renal disease (ESRD) patients on chronic dialysis and 354 similar-age persons selected as a control group showed that significantly compromised physical function and health outlook were reported by the dialysis patients compared with the control group. Increasing exercise capacity and participation in dialysis self-care activity are recommended ways to improve physical functioning and health outlook among ESRD patients. Individuals who cannot perform strenuous activity can improve in level of fitness; improvements in anemia and muscle strength are key variables. Clinical application of therapeutic and rehabilitative strategies to improve physical function and health outlook in the geriatric renal patient is greatly needed.

Retroperitoneal fibrosis associated with carcinoma of the cervix: review of the literature

Microinvasive cervical cancer presented in a woman with retroperitoneal fibrosis in remission following steroid therapy. The cervical lesion was treated surgically with good outcome. Review of the literature documenting this association reveals three other cases, one following and two preceding the diagnosis of retroperitoneal fibrosis. The case reports are reviewed and potential difficulties in the management of these patients are discussed.

Leuprolide acetate in the management of ureteral obstruction caused by endometriosis

Endometriotic ureteral obstruction is a serious event commonly diagnosed late and therefore associated with a major risk of hydronephrotic renal atrophy. The standard therapy is surgical. However, medical treatment has been reported using danazol, progestins, and estrogen-progestin combinations, although solid documentation of the effect of hormonal therapy against ureteral endometriosis is lacking. Gonadotropin-releasing hormone (GnRH) agonist treatment of endometriosis has yielded good results but has not been adequately reported in patients with ureteric involvement. We report three patients treated with a GnRH agonist, leuprolide acetate, for 6-9 months as a preoperative course. One patient had bilateral and two had unilateral obstruction. The preoperative course relieved the obstruction in the patient with bilateral disease and in one with unilateral changes. The failure occurred in a patient with intrinsic ureteric endometriosis. This early experience suggests a place for GnRH agonist therapy for patients with ureteric obstruction due to endometriosis, probably, but not necessarily, in conjunction with a planned surgical procedure. If medical therapy is attempted, close surveillance of renal function is mandatory.

Digital clubbing due to secondary hyperparathyroidism

Five patients in our dialysis population had digital changes suggestive of clubbing in association with severe secondary hyperparathyroidism. All had parathyroidectomies between June 1986 and December 1987. They represented 0.6% of the patients in our dialysis population and 17.8% of our patients who required operative management of secondary hyperparathyroidism. The clubbing was occasionally painful, and the digits were tender in response to palpation. Parathyroidectomy yielded excessive amounts of hyperplastic parathyroid tissue in each case. Postoperatively, the symptoms were relieved, when present, and the digital changes were stabilized. We believe that these findings are associated with severe secondary hyperparathyroidism and should be looked for in dialysis patients with renal osteodystrophy.

Attenuation of ischemic renal injury with fructose 1,6-diphosphate

Fructose 1,6-diphosphate (FDP) has been shown to attenuate tissue injury associated with ischemia and shock by enhancing the anaerobic carbohydrate utilization and by inhibiting oxygen-free-radical generation by the neutrophils. Previously, we have reported that FDP prevents ischemic renal failure if administered prior to the ischemic insult. The present study was designed to determine whether this agent could prevent renal damage when administered during the postischemic reperfusion period. Rats were subjected to 30 min of bilateral renal artery occlusion and infused with FDP (350 mg/kg body wt) beginning 10 min after release of the renal artery clamps. Control rats received an equal volume of glucose/saline solution. A third group of rats were sham operated. Twenty-four hours after injury, BUN, creatinine, and fractional sodium excretion values were less in FDP-treated rats than in control rats (P less than 0.001, P less than 0.005, and P less than 0.001, respectively) and not different from values observed in sham-operated rats. Inulin clearance was greater (P less than 0.001) in FDP-treated rats than in control rats (665 +/- 38 microliters/min/g kidney wt). Renal histology was also better preserved in the FDP-treated group. These data suggest that FDP infused after the initiation of an acute ischemic insult provides significant, but not complete, functional and histologic protection from renal damage.

The minimal importance of the hollow viscera to peritoneal transport during peritoneal dialysis in the rat

The authors investigated whether the abdominal viscera are important surfaces for peritoneal transport by performing peritoneal dialysis in rats without their abdominal viscera and again when the parietal walls were shielded from contact with dialysate. Urea, creatinine, glucose, and inulin were added to the peritoneal cavity and the percentage of the administered dose absorbed was calculated. Controls with and without parietal shields only absorbed 11% more urea and creatinine, 5-15% more glucose, and 7-12% more inulin, respectively, than eviscerated rats. The findings raise the possibility that the abdominal contents do not account for most of peritoneal transport.

15 years of experience with renal replacement therapy in patients starting therapy before age 20

This study retrospectively evaluates the survival on renal replacement therapy among patients starting dialysis before their twentieth birthday. The cohort included all patients starting therapy from 1972 through August, 1987 at the University of Mississippi or Kidney Care, Inc. Fifty-five patients, median age 17 years, range 5-19 years, underwent 335 patient years of therapy. Nineteen initially received CAPD; 12 home hemodialysis, 2 were transplanted prior to dialysis, and the remaining 22 patients were entered into dialysis in a free standing facility. Thirty-one patients received a cadaveric transplant and four patients received a living related transplant. The median transplant survival was 1360 days. There were 10 patients on renal replacement therapy over 10 years and a survival plot projected a 70% survival at 10 years. Nine patients died. Three percent of the time on renal replacement therapy was spent hospitalized. Although the hospitalization rate is significant, the pediatric patient may be expected to have a long survival on renal replacement therapy.

CAPD patients as renal transplant patients

Most authors state that the continuous ambulatory peritoneal dialysis (CAPD) patient is not at increased risk when transplanted. These patients are always exposed to the risk of peritonitis, which may increase if patients are peritoneally dialyzed while immunosuppressed. The postoperative course of patients transplanted from our CAPD program from 1979 through August 1985 was evaluated. The transplant survival of patients dialyzed by CAPD, home hemodialysis, and at a free-standing dialysis facility were compared. Pretransplant dialysis modality did not influence long-term transplant success. Three of seven patients who required dialysis postoperatively developed peritonitis. The dialysis catheter was removed in two patients and one was treated by lavaging the peritoneal cavity with antibiotics. There was one instance of dialysate leaking through a drain in the transplant bed. This patient was converted to hemodialysis for subsequent dialysis. The dialysis catheters were removed at the time of discharge from hospital. Literature review confirmed this experience. Peritoneal dialysis post-transplant exposes the patient to a 10-33% risk of peritonitis and a 10% risk of a wound complication. Peritoneal dialysis patients are subject to risks unique to peritoneal dialysis. These complications do not translate into excessive morbidity or graft loss.

Diabetes, dialysate losses, and serum lipids during continuous ambulatory peritoneal dialysis

We evaluated changes in dialysate losses of protein and absorption of glucose, serum chemistries including protein electrophoresis, and serum lipids among patients who had undergone continuous ambulatory peritoneal dialysis (CAPD) for at least 1 year. The patients' race, sex, and the presence of diabetes mellitus did not influence the results. Over a 2-year period, daily protein losses and glucose absorption from dialysate were constant, serum protein electrophoresis did not show changes consistent with the nephrotic syndrome, serum cholesterol increased after 1 year of therapy but stabilized thereafter, and concentrations of high density lipoproteins did not decrease.

Mechanism of attenuated hydrochlorothiazide response during indomethacin administration

Indomethacin antagonizes the natriuretic and chloruretic response to hydrochlorothiazide in most studies. Neither the mechanism nor nephron site of this antagonism has been determined. To identify sites and potential mechanisms, cortical micropuncture was performed during hydrochlorothiazide treatment in control and indomethacin rats. Indomethacin reduced (P less than 0.005) FeCl from 5.20 +/- 0.49% to 2.26 +/- 0.49% (mean +/- SE). MAP, CIn, and plasma volume were not different between groups. SNGFR and fractional proximal fluid and chloride delivery were not different between groups. Fractional chloride delivery to early distal tubules was 10.8 +/- 0.4% in control but 6.2 +/- 0.3% in indomethacin rats (P less than 0.001). Calculated loop chloride reabsorption was greater in indomethacin than control rats during hydrochlorothiazide administration (41.0 +/- 1.6% vs. 34.3 +/- 2.3%; P less than 0.05). Fractional chloride delivery to late distal tubules was 7.8 +/- 0.7% in control and 4.6 +/- 0.3% in indomethacin rats (P less than 0.005), but distal tubule chloride reabsorption was not different between groups. Papillary tissue chloride was less in control than indomethacin rats during hydrochlorothiazide (P less than 0.05). Urinary PGE2 excretion was reduced (P less than 0.001) by indomethacin during hydrochlorothiazide. Thus indomethacin induced reductions in hydrochlorothiazide response result in part from increased chloride reabsorption in the loop segment. This suggests indomethacin antagonizes hydrochlorothiazide by reducing chloride delivery to hydrochlorothiazide's site of action in the distal tubule rather than by effects of indomethacin on hydrochlorothiazide pharmacokinetics.

Prostaglandin E2 but not I2 restores furosemide response in indomethacin-treated rats

Indomethacin attenuates furosemide's natriuretic response. Although this has been attributed to cyclooxygenase inhibition, attempts to correlate prostaglandin (PG) production with furosemide's natriuresis have led some investigators to conclude that prostaglandins are not involved in this response. This study was designed to evaluate the effects of intraaortic administration of PGE2, PGI2 (100 ng X kg-1 X min-1), or the vasodilators secretin or bradykinin (75 microU X kg-1 X min-1) on the furosemide-indomethacin antagonism. Fractional sodium excretion (FENa) during furosemide administration was 4.59 +/- 0.50% in control rats but 1.84 +/- 0.33% in indomethacin-treated rats (Indo) (P less than 0.001). PGE2 prevented indomethacin from attenuating furosemide's response (FENa, 3.91 +/- 0.25%; P = NS vs. control; P less than 0.01 vs. Indo). PGI2, however, failed to prevent the furosemide-indomethacin antagonism (FeNa, 1.94 +/- 0.59%, P less than 0.001 vs. control; P = NS vs. Indo). Inulin clearance, arterial pressure, filtered sodium load, and renal blood flow were not different between groups. Neither secretin nor bradykinin prevented the indomethacin-furosemide antagonism. This study is consistent with the hypothesis that indomethacin antagonizes furosemide's natriuretic response by prostaglandin synthesis inhibition. Furthermore, PGE2 seems to restore furosemide's response through actions other than a vasodilatory effect.

Serial monitoring of T-cell subset ratios with monoclonal antibodies in steroid- and antithymocyte globulin-treated patients with renal allotransplants

Sequential changes in T-cell subsets or their ratios were employed to predict severity of rejection crises and to identify those patients who might require future antirejection therapy. Forty-two percent of the transplant recipients had a pretransplant OKT4:8 ratio in the range of 1.3 +/- 0.5. By contrast, only 11% had a OKT4:8 ratio of 2.9 or greater. Examination of the entire study group demonstrated that the mean OKT4:8 ratios fell (P less than 0.01) in the first week following the transplant procedure. All patients had at least one episode of acute rejection. There was a marked increase (P less than 0.05) in the OKT4:8 ratio between the first week value and the value immediately preceding (within 3 days) the start of the rejection episode which was 2.64 +/- 0.27. The mean OKT4:8 ratio in the 15 patients leaving the hospital with a functioning transplant was 1.18 +/- 0.35. Three months post-transplant, the OKT4:8 ratio was 1.98 +/- 0.39 in the 12 patients with functioning allografts. This value was not different from those patients' initial pretransplant values. Clinically, the rejection episodes could be divided into two groups based on their response to intravenous methylprednisolone therapy. The first group (n = 9) had milder rejection crises which responded rapidly to administration of one course of methylprednisolone. The second group of patients (n = 9) were also treated initially with methylprednisolone, to which they did not respond, and subsequently received antithymocyte globulin in an attempt to control their ongoing rejection crises. Following the transplant procedure, the OKT4:8 ratio decreased in patients who were destined to have steroid-responsive rejection episodes (P less than 0.01). The OKT4:8 ratio however, failed to fall in those who required ATG for control of their transplant rejection episodes. The onset of rejection episodes was associated with an increase in OKT4:8 ratio in both groups. Following steroid administration, two patterns of OKT4:8 cell responses were observed. Those in whom renal function improved demonstrated a decline in OKT4:8 ratio from 2.4 +/- 0.4 to 1.4 +/- 0.4 (P less than 0.05). However, no change occurred in the OKT4:8 ratios with steroid therapy (2.6 to 2.4 +/- 0.33, P greater than 0.05) in individuals in whom the serum creatinine concentration failed to decline. The patients who failed to respond to steroid therapy were treated with antithymocyte globulin (ATG).(ABSTRACT TRUNCATED AT 400 WORDS)

Long-term hemodialysis at reduced dialysate flow rates

20 stable hemodialysis patients were maintained on a dialysate flow rate of 300 ml/min (QD 300) to determine the safety of prolonged reductions in dialysate flow rate. After 24 months, QD 300 compared to QD 500 resulted in no change in weight, blood pressure, BUN, hematocrit, creatinine, bicarbonate, potassium, cholesterol, or calcium. Serum phosphate concentration increased between month 13 and month 17 but then stabilized. No adverse symptoms developed. EEGs and motor nerve conduction studies following 24 months at QD 300 were normal. We conclude that QD 300 does not impair dialysis efficiency for most small molecules and saves $1.38 per patient per dialysis.

Evaluation of continuous ambulatory peritoneal dialysis

This study was undertaken to ascertain whether 19 patients maintained on continuous ambulatory peritoneal dialysis (CAPD) for at least 1 year experienced any deterioration in peritoneal membrane function. Selected serum chemistries and skinfold measurements were also evaluated to determine whether patients dialyzed by CAPD could maintain a normal nutritional status. This study demonstrates that patients maintained on CAPD had stable dialysate protein losses, glucose absorption from the dialysate, and constant urea, creatinine, and sodium removal. When these patients were subdivided by incidence of peritonitis, the group with a lower incidence of peritonitis (one episode every 349 +/- 155 SEM days) showed stable serum protein concentration and improvement in upper arm area whereas the group with a high incidence of peritonitis (one episode every 95 +/- 7 SEM days) showed a reduction in upper arm muscle area. Thus, our data suggest that over a 1-year period, there is no deterioration in peritoneal membrane characteristics and CAPD is effective in maintaining the nutritional status of the patient. However, both membrane function and nutritional status may be impaired by frequent episodes of infection.

Host defense mechanisms in continuous ambulatory peritoneal dialysis

We investigated whether dialyzate obtained from patients undergoing CAPD had any harmful effects on the function of their own lymphocytes and granulocytes and on those of normal controls. When tested in dialyzate obtained after a 4 hr intraperitoneal residence, lymphocyte viability and transformation responses to phytohemagglutinin and protein A were similar for patients and controls. Neutrophil function assessed by the nitroblue tetrazolium test (NBT) was not altered. Our results suggest that dialyzate, after a 4 hr intraperitoneal stay, does not impair lymphocyte and granulocyte function.

Peritonitis in continuous ambulatory peritoneal dialysis patients

Peritonitis is the most important complication of continuous ambulatory peritoneal dialysis (CAPD). We reviewed our experience with peritonitis over a 2 1/2-year period. Our patients spent 4% of their total time on dialysis in hospital due to peritonitis. Thirty-eight percent of the episodes of peritonitis were treated without hospitalization. We evaluated the dialysate bag change technique as commonly performed with currently available devices (extension tubing and titanium Luerlock Tenckhoff catheter adapter). The aseptic techniques described for dialysis extension tubing changes appear adequate (with no increased incidence of peritonitis demonstrated shortly after an extension tubing set change). Long-term sterility is maintained at the dialysate bag puncture port and at the orifice of the dialysis catheter adapter (no positive cultures from the bag port and orifice of the titanium adapter). Etiologic diagnosis of uremia was not a risk factor predisposing to peritonitis. The incidence of peritonitis was greater among patients with less formal education and lower income. Out data suggest that patients with less formal education and of lower economic status be carefully evaluated before commencing CAPD.

A model of long-term peritoneal dialysis in the dog

We describe two preparations for chronic peritoneal dialysis in the dog. In one group uremia was induced by nephrectomy and in the other by ureteral ligation. Peritoneal access was obtained using the Ash disc column catheter. Survival of the animals ranged from 27 to 83 days. Using a dialysis schedule similar in concept to continuous ambulatory peritoneal dialysis in man we found that dialysate-induced ultrafiltration, equilibration of solute between serum and dialysate, as well as protein losses into dialysate approximated values found in patients undergoing continuous ambulatory peritoneal dialysis. Careful attention to detail is required in order to maintain these animals. The advantages of these models are their technical simplicity and prolonged survival making intermediate range studies feasible. Disadvantages include anemia, seen in the anephric animals, technical problems with the disc column catheter, the need for maintenance of strict aseptic technique when performing dialysis exchanges, and difficulties maintaining adequate nutrition.

Augmentation of peritoneal clearance by dipyridamole

We performed a double blind crossover trial in which dipyridamole was administered to ten patients undergoing intermittent peritoneal dialysis at 2 liters/hour (10 min infusion, 30 min intraperitoneal dwell of dialysate and 20 min drainage of dialysate). After the patients received the drug for 3 days at a dose of 75 mg three times daily, peritoneal inulin clearance increased by 1.2 ml/min (P less than 0.05), and glucose absorption increased by 12.1 g (P less than 0.05). The mechanism of the observed drug-induced effects is unknown.

Abdominal hernia in patients undergoing continuous ambulatory peritoneal dialysis

We found abdominal hernias in 12 of 51 patients trained for continuous ambulatory peritoneal dialysis. Five patients were noted to have abdominal hernias before the start of continuous ambulatory peritoneal dialysis, and the conditions of seven patients were diagnosed during routine clinic visits. Four patients had incarceration. We suggest that a careful search for the presence of a hernia be performed at the initial examination for peritoneal dialysis. Continued monitoring of the patient's condition for the development of a hernia is essential. If a hernia is found, elective repair should be performed.

The Tenckhoff catheter for peritoneal dialysis--an appraisal

We prospectively evaluated early (within 40 days) catheter complications in all patients receiving a dialysis catheter between 1/8/80 and 1/8/81. 50% of patients achieved a functioning catheter at the first insertion and 24% required replacement of the catheter because of poor dialysate flow. Leaking from the catheter exit site occurred in 20%, infection at the exit site in 9% and peritonitis in 19% of patients. In patients who maintain a catheter over 40 days and undergo treatment by long-term peritoneal dialysis median catheter survival was 400 days with delayed cytheter failure primarily due to failure to resolve a clinical episode of peritonitis. Although the Tenckhoff catheter is readily inserted frequent complications occur.

Stereospecific lactate absorption during peritoneal dialysis

Patients undergoing peritoneal dialysis were studied to determine if peritoneal absorption was selective. Dialysis was performed using dialysate exchange schedules similar to those for intermittent peritoneal dialysis and continuous ambulatory peritoneal dialysis. The clearance rate from the peritoneal cavity during hourly dialysate exchanges was 6.2 ml/min for D (-)-lactate and 8.7 ml/min for L(+)-lactate (p less than 0.01). L(+)-Lactate disappeared more rapidly from the dialysate during the long-cycle exchanges. Our results suggest that clearance of lactate from the peritoneal cavity is relatively stereospecific and raises the question of selective absorption for other organic anions.

Peritoneal dialysis during peritonitis

Peritonitis during peritoneal dialysis is the most frequent complication associated with this dialysis technique. We studied patients undergoing peritoneal dialysis when they were without peritonitis and during episodes of clinical infection. Peritonitis was associated with a significantly decreased dialysate effluent volume, increased absorption of glucose, clearance of urea and creatinine, and protein loss in the dialysate effluent. We suggest that the changes occurring to the peritoneal dialyzing surface with peritonitis might be explained by alterations in peritoneal blood flow, effective membrane surface area, or permeability.