Prostaglandin D(2) synthase induces apoptosis in pig kidney LLC-PK1 cells.

BACKGROUND: Prostaglandin D(2) synthase (PGD(2)S), a unique member of the lipocalin family, is found at elevated levels in the serum of patients with renal impairment and has recently been implicated as a new biochemical marker of renal insufficiency. The aim of this study was to investigate the apoptotic effects of PGD2S on a pig kidney epithelial cell line (LLC-PK1) and to investigate the effects of prostaglandins and growth factors on this process. METHODS: Apoptosis was detected by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling (TUNEL), annexin V staining, and electron microscopy. RESULTS: A four- to fivefold increase in apoptosis was observed in PGD(2)S-treated cells as compared with controls and the apoptosis appeared to act via caspase-3. A cyclooxygenase-2 inhibitor, anti-PGD(2)S antibody, and selenium all significantly inhibited the apoptosis induced by PGD(2)S; however, none had any effect on the apoptosis induced by the known apoptotic inducer camptothecin. Furthermore, prostaglandins E(1) and E(2), known to induce mitogen-activated protein (MAP) kinase phosphorylation and exhibit cytoprotective effects, both inhibited PGD(2)S-induced apoptosis, while prostaglandin H(2) had no significant effect. Growth factors such as insulin, insulin-like growth factor-1, and platelet-derived growth factor also decreased PGD(2)S-induced apoptosis. In addition, PGD(2)S isolated from human serum seemed slightly more effective at inducing apoptosis than recombinantly expressed protein. CONCLUSIONS: We report on the induction of apoptosis by PGD(2)S in LLC-PK1 pig kidney epithelial cells, and speculate that the accumulation of PGD(2)S in the serum of kidney failure patients may further exacerbate renal problems and is most likely regulated by other prostaglandins and growth factors.

Prostaglandin D2 synthase induces apoptosis in PC12 neuronal cells.

Apoptosis of neuronal cells is a proposed cause of certain neurological disorders. Here, we report on a 5- to 6-fold increase in apoptosis by exposure to prostaglandin D2 synthase (PGD2S) in PC12 neuronal cells. Apoptosis was detected by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling (TUNEL) assay, and appears to be mediated via caspase-3 activation. Neutralization with anti-PGD2S antibody or pre-treatment with selenium, which inhibits PGD2S enzymatic activity, both significantly inhibited the PGD2S-induced apoptosis, however, neither had any effect on the apoptosis induced by the known neuronal apoptotic inducer, glutamate. In addition, prostaglandins E1, E2, and F2alpha all inhibited the PGD2S-induced apoptosis while prostaglandin H2 had no significant effect. Furthermore, PGD2S isolated from human serum was more effective at inducing apoptosis then recombinantly expressed protein, presumably due to glycosylation. This novel role of PGD2S, as an inducer of apoptosis, may have implications in PC12 differentiation and possibly some neurological disorders.

Self-assessed quality of life in peritoneal dialysis patients.

BACKGROUND/AIMS: Studies comparing quality of life (QOL) between peritoneal and hemodialysis patients have yielded inconsistent results. Physical (PCS) and mental component summary (MCS) scales of Short Form 36 (SF-36) health survey are highly validated measures of self-assessed QOL. We sought to evaluate these indices in PD patients: (1) as measures of QOL, (2) predictors of QOL, (3) to study change in QOL over time, and (4) to compare QOL in PD vs. hemodialysis patients. METHODS: SF-36 questionnaires were administered every 3 months to patients over a 2-year period and PCS and MCS were calculated. Mean follow-up was 15.3 +/- 6.6 months for PD and 14.5 +/- 5.7 months for HD. RESULTS: Average PCS in PD (31.8 +/- 7.8) was lower than HD (36.9 +/- 9.8) (p < 0.02), while MCS was similar in the groups (p = NS). The prevalence of depression was 26.1% in PD and 25.4% in HD patients (p = NS). Serum albumin was the only significant predictor of PCS among PD patients and explained much of the decrease in PCS in them. The number of hospitalizations and in-hospital days were significantly lower for PD compared to HD patients (p < 0.05). PCS as well as MCS remained stable in both groups throughout the observation period. CONCLUSION: Self-assessed physical function is diminished, while mental function is similar in PD compared to HD patients. When corrected for serum albumin, this difference is eliminated. Over time, QOL in patients treated with PD remained stable.

Self-assessed physical and mental function of haemodialysis patients.

BACKGROUND: Physical (PCS) and mental (MCS) component summary scales of the Short Form 36 (SF-36) health survey are validated measures of quality of life (QOL) and functional status. We sought to evaluate the PCS and MCS in haemodialyis patients as compared to the general population and other chronic diseases. METHODS: A cohort of 134 haemodialysis patients (mean age 60.9+/-14.3 years, males 63.4%, Caucasians 66.4%) was followed from January 1996 to December 1998 (mean follow up 14.5+/-5.7 months). SF-36 questionnaires were administered every 3 months and PCS and MCS were calculated. Results were compared to the general population and other chronic diseases. Correlators of PCS and MCS, change in QOL over time, and the correlators of this change were determined. RESULTS: Mean PCS was 36.9+/-8.8 and mean MCS was 47+/-10.7. Compared to the general US population, these represent a decline of 8.7+/-0.8 for PCS (P<0.0001) and 2.7+/-0.8 for MCS (P<0.001). PCS and MCS in end-stage renal disease (ESRD) were lower than in most other chronic diseases studied. Univariate correlators of PCS in haemodialysis patients included age, male sex, haematocrit, serum albumin, and severity of comorbid cardiac and pulmonary illnesses. Multivariate analysis demonstrated independent correlators of PCS to be male sex, serum albumin and severity of comorbid cardiac and pulmonary diseases. Univariate as well as multivariate correlators of MCS included: serum albumin, KT/V(urea), and status living alone. A trend analysis revealed that both PCS and MCS tended to decline in the initial months of dialysis but stabilized over time. Status living alone was a significant predictor of improvement in MCS by univariate as well as multivariate analysis. CONCLUSIONS: Self assessed physical and mental health of haemodialysis patients is markedly diminished compared to the general population and other chronic diseases.

Cerebral salt-wasting syndrome: does it exist?

Cerebral salt-wasting syndrome (CSWS) has been regarded as a misnomer of the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). We take the position that CSWS does exist and might be more common than SIADH. Differentiation between groups has been difficult because of overlapping signs, symptoms, and associated diseases. Euvolemia in SIADH and hypovolemia in CSWS may be the only contrasting variables. However, clinical assessment of extracellular volume is accurate in about 50% of these patients. Determination of serum urate and fractional excretion rates of urate can differentiate one group from the other. In both groups, hyponatremia coexists with hypouricemia and increased fractional excretion of urate. When the hyponatremia is corrected by water restriction, hypouricemia and elevated FEurate correct in SIADH but persist in CSWS. Persistent hypouricemia and elevated FEurate were commonly noted with pulmonary and/or intracranial diseases. The absence of intracranial diseases in some patients suggests that renal salt wasting might be a more appropriate term than CSWS. A review of renal/CSWS reveals three studies involving hyponatremic neurosurgical patients who had decreased blood volume, decreased central venous pressure, and inappropriately high urinary sodium concentrations in the majority of them, suggesting that CSWS was more common than SIADH in neurosurgical patients. Evidence for the presence of a plasma natriuretic factor in CSWS is presented.

Partial characterization of apoptotic factor in Alzheimer plasma.

We have previously demonstrated that a plasma natriuretic factor is present in Alzheimer's disease (AD), but not in multi-infarct dementia (MID) or normal controls (C). We postulated that the natriuretic factor might induce the increased cytosolic calcium reported in AD by inhibiting the sodium-calcium antiporter, thereby activating the apoptotic pathway. To test for a factor in AD plasma that induces apoptosis, we exposed nonconfluent cultured LLC-PK1 cells to plasma from AD, MID, and C for 2 h and performed a terminal transferase-dUTP-nick-end labeling (TUNEL) assay. The plasma from AD increased apoptosis nearly fourfold compared with MID and C. The effect was dose dependent and the peak effect was attained after a 2-h exposure. Additionally, apoptotic morphology was detected by electron microscopy, and internucleosomal DNA cleavage was found. We inhibited apoptosis by removing calcium from the medium, inhibiting protein synthesis with cycloheximide, alternately boiling or freezing and thawing the plasma, and digesting a partially purified fraction with trypsin. Heating AD plasma to 56 degrees C did not deactivate the apoptotic factor. These results demonstrate the presence of an apoptotic factor in the plasma of patients with AD.

Beneficial effects of iron therapy in renal failure patients on hemodialysis.

Iron deficiency is a common problem in patients treated with hemodialysis. If not detected and treated appropriately, the effectiveness of recombinant human erythropoietin therapy is compromised. Much has been learned in recent years with respect to iron therapy for hemodialysis patients. A series of studies have clearly defined the efficacy of intravenous iron compounds, and recently released clinical practice guidelines have set the appropriate clinical context for the use of these agents. The purpose of this article is to examine the beneficial effects of iron replacement therapy for hemodialysis patients.

Prevalence of hypertension in a hemodialysis population.

BACKGROUND: Accurate information on prevalence and status of blood pressure (BP) control in hemodialysis patients is lacking. Our Hemodialysis Quality Improvement Program, sought to determine: 1) The extent and control of hypertension (HTN), 2) whether Erythropoietin (EPO) dose or intradialytic fluid loss had any effect on BP and 3) a means to follow the severity of HTN. PATIENTS AND METHODS: The pre/post mid-week dialysis BP readings of 190 patients (64+/-14.1 years, 53% males, 77% whites) were evaluated over a 3 month period. HTN was defined as BP >150/90. Hypertension was further characterized according to whether the patients had normal or elevated pre-dialysis systolic, pre-dialysis diastolic, post-dialysis systolic or post-diastolic BP readings on more than 6 of the possible 13 recordings. The average EPO dose and weight loss during dialysis was correlated with BP. To better understand the extent of HTN, systolic and diastolic pressures were separately graded from 0 to 3 and a number designated as hypertension sensitivity index (HSI) was assigned to each patient. RESULTS: Of the 190 patients, 146 (76.8%) were hypertensive. 117 out of 146 hypertensive patients (80.1%) had persistent elevation of BP despite being on one or more antihypertensive medications. Most patients were on calcium channel blockers (39%) with 27% being on beta-blockers and 14% on Angiotensin converting enzyme inhibitors. There was no correlation between the number of medications used and the control of HTN. The dose of EPO also had no effect on the degree of HTN. 69.8% of all HTN was systolic. Of this, 64.7% was pre-dialysis and 35.3% post-dialysis. Multiple regression analysis demonstrated a significant correlation with loss of weight during dialysis and lowering of systolic BP (r = 0.33, p = 0.0001). The mean HSI for this population was 2.3+/-1.8. CONCLUSION: HTN was a frequent finding in our hemodialysis population and it was controlled in only 19.9% of hypertensive patients. Most of this HTN was pre-dialysis systolic. There was a significant correlation between fluid loss during dialysis and lowering of blood pressure. The use of the HSI has proven to be helpful in differentiating type and severity of HTN.

Regulation of renal urate excretion: a critical review.

Uric acid metabolism is reviewed as it relates mainly to kidney and electrolyte disorders, with emphasis on the difficulties in understanding urate transport because of its bidirectional transport and the species differences in which animal data may not have relevance to the human condition. A critical review of the effects of pyrazinamide and extracellular volume expansion on urate transport raises questions about the current popular teachings that pyrazinamide exclusively blocks tubule urate secretion and extracellular volume expansion has a major role in controlling urate excretion. There appears to be a renal salt-wasting syndrome with overlapping clinical features that make it indistinguishable from the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), except possibly for extracellular volume depletion. Hypouricemia and the elevation in the fractional excretion of urate (%E/Furate) are extensively reviewed with a proposal to use the persistence of hypouricemia and elevated %E/Furate after the correction of hyponatremia to differentiate these patients from those with SIADH. An algorithm is proposed to differentiate one group from the other. A plasma natriuretic factor has been shown in some with probable renal salt wasting, which includes patients with AIDS, cancer, and pulmonary and intracranial diseases. The natriuretic factor may have etiologic implications and diagnostic and therapeutic applications.

Reticulocyte hemoglobin content in the evaluation of iron status of hemodialysis patients.

The assessment of iron status for hemodialysis patients has been hindered by the inaccuracy of commonly used diagnostic tests. A novel assay, the reticulocyte hemoglobin content (CHr), has recently been found to sensitively detect functional iron deficiency among nonuremic patients treated with recombinant erythropoietin (rHuEPO). The purpose of this study was to evaluate the CHr for the assessment of iron status in hemodialysis patients. One hundred sixty-four stable hemodialysis patients had a mean CHr of 27.5 +/- 2.8 pg with a normal distribution of values. The mean CH (mature red cell hemoglobin content) was 26.4 +/- 2.4 pg. There was a close correlation between CHr and CH (r = 0.86, P < 0.0001). A significant subgroup of patients (12.2%) had CHr values < CH. These patients had recent increases in rHuEPO dose, and a lower mean transferrin saturation and hematocrit, suggesting the recent onset of functional iron deficiency due to the increase in rHuEPO dose. In the second phase of the study, 32 patients were randomly selected to receive treatment with a single dose infusion of 1,000 mg of intravenous iron dextran (IVFe). Patients were classified as iron deficient (N = 7) if they responded with a significant reticulocytosis (sustained 1 basis point increase in corrected reticulocyte index within 2 weeks). All other patients were classified as iron replete (N = 25). A CHr < 26 pg at baseline predicted iron deficiency with a sensitivity of 100%, specificity of 80%. The serum ferritin, transferrin saturation and percentage of hypochromic red blood cells all were less accurate. The time to correction of iron deficiency at the level of the reticulocyte was found to be within 48 hours as measured by correction of the mean CHr to > 26 pg, and by the shift of the vast majority of the reticulocyte population to CHr > 26 pg within this time span. We conclude that CHr < 26 pg is an accurate measure of iron status in hemodialysis patients, that a CHr value < CH indicates the acute onset of iron deficiency, and that a single dose infusion of intravenous iron results in correction of iron deficiency at the level of the reticulocyte within 48 hours.

Paraneoplastic syndromes of the kidney.

Malignant disease is associated with a wide variety of derangements in renal function and electrolyte homeostasis. In many cases this leads to a clinically significant worsening of health status and rarely may lead to the patient's death. In this review we discuss several of the important abnormalities of renal structure and function associated with neoplastic disease.

Iron management in end-stage renal disease.

One of the important components of successful anemia therapy in patients with end-stage renal disease (ESRD) treated with recombinant human erythropoietin is the maintenance of adequate available iron. To accomplish this task, iron status must be serially monitored and supplemental iron administered as required. Among nonuremic subjects, the body's iron supply is tightly conserved, and iron deficiency usually develops only when chronic blood loss occurs. In patients with ESRD, iron deficiency occurs more frequently, because of increased external losses of iron, decreased availability of the body's storage of iron, and perhaps a deficit in intestinal iron absorption. Detecting iron deficiency in these patients can be difficult because of the inaccuracy of available diagnostic tests. The goals of iron therapy in ESRD include the prevention of iron deficiency by chronically supplementing iron, and the prompt treatment of overt iron deficiency. Oral iron supplements are inexpensive and safe, but poor patient compliance and reduced intestinal absorption may limit their effectiveness. Intravenous iron supplements have a greater efficacy then oral iron, which must be weighed against the small risk of allergic reactions. We present strategies for using the various diagnostic tests and treatment modalities to effectively manage iron supply for predialysis, hemodialysis, and peritoneal dialysis patients.

The evaluation of iron status in hemodialysis patients.

Effective treatment of anemia in hemodialysis patients requires ongoing monitoring of iron status. The purpose of this study was to determine levels of commonly used iron indices predictive of iron deficiency in this population. Forty-seven patients with baseline serum ferritin levels < 600 ng/mL were treated with intravenous iron dextran (INFeD; Schein Pharmaceutical Inc., Florham Park, NJ), 1000 mg over ten hemodialysis treatments. Patients whose hematocrit value increased by 5% or who had a 10% decrease in their erythropoietin dose by 2 months were classified as having iron deficiency (N = 31; 66%). All other subjects were classified as having adequate iron (N = 16; 34%). There was no statistically significant difference in baseline serum ferritin, transferrin saturation, mean cell volume, mean cell hemoglobin content, or red cell distribution width between the two groups. Receiver operator curves demonstrated that none of the iron indices had a high level of utility (both sensitivity and specificity > 80%). Two tests had marginal utility, serum ferritin at a level of < 150 ng/mL, and transferrin saturation < 21%. It was concluded that because of the tests' marginal utility, they should only be interpreted in the context of the patient's underlying erythropoietin, responsiveness. In patients who are responsive to erythropoietin, a transferrin saturation value < 18% or serum ferritin level < 100 ng/mL should be used to indicate inadequate iron. When erythropoietin resistance is present, transferrin saturation of < 27% or serum ferritin < 300 ng/mL should be used to guide iron management.

The safety of intravenous iron dextran in hemodialysis patients.

The treatment of anemia in hemodialysis patients is frequently hindered by the presence of suboptimal iron stores. Intravenous iron dextran is in common use to maintain iron stores in this population, but there are little published data regarding the incidence and type of adverse events. The purpose of this study was to evaluate the safety of this medication. Charts from four hemodialysis centers of all 573 patients treated with intravenous iron dextran (INFeD; Schein Pharmaceutical, Inc, Florham Park, NJ) between July 1, 1993, and June 30, 1995, were studied. Twenty-seven patients (4.7%) had adverse reactions that were related to iron dextran. Four patients (0.7%) had reactions classified as serious (one cardiac arrest; three others required hospitalization). Ten patients (1.7%) had reactions classified as anaphylactoid. No patients died or developed permanent disability as a result of reactions. The most common adverse reactions included itching (1.5% of patients) and dyspnea or wheezing (1.5%); others included chest pain (1.0%), nausea (0.5%), hypotension (0.5%), swelling (0.5%), dyspepsia (0.5%), diarrhea (0.5%), skin flushing (0.3%), headache (0.3%), cardiac arrest (0.2%), and myalgias (0.2%). Five of all the reactions occurred during a test dose; four of these were anaphylactoid. Several factors were studied as possible predictors of adverse reactions. A positive history of drug allergy (odds ratio, 2.4; P = 0.03) and history of multiple drug allergy (odds ratio, 5.5; P = 0.0004) were significant predictors of reactions. In summary, we found serious adverse reactions to be uncommon in hemodialysis patients treated with intravenous iron dextran. Future prospective studies will help confirm this finding.

Proximal calciphylaxis in four insulin-requiring diabetic hemodialysis patients.

We present four cases of proximal calciphylaxis in end-stage renal disease patients treated with hemodialysis. All patients were diabetic and developed lesions in areas that had previously served as sites of insulin injection. We review the presentation, pathogenesis, pathology, prognosis, and treatment of this devastating condition. Finally, we hypothesize that subcutaneous injection of insulin may play a pathogenic role in the development of proximal calciphylaxis.

Role of volume overload in dialysis-refractory hypertension.

It has been observed that while most hypertensive hemodialysis patients normalize their blood pressure with volume removal, there is a population of hemodialysis patients whose hypertension is refractory to volume removal. Our hypothesis is that such patients are still volume overloaded posthemodialysis and are not at a "true" dry weight. This study used atrial natriuretic peptide (ANP) assays (as a marker of hydration status) to study this hypothesis. Three groups of patients were studied: normotensive hemodialysis patients (n = 12; group 1), hypertensive hemodialysis patients who consistently normalize their blood pressure with fluid removal (n = 12; group 2), and hypertensive hemodialysis patients whose hypertension is refractory to fluid removal (n = 9; group 3). Plasma ANP levels were measured before and after hemodialysis by radioimmunoassay after extraction on Sep-Pac (Penninsula Laboratories, Belmont). On the day of study the predialysis mean arterial pressures in the three groups were 94.9 +/- 1.9 mm Hg in the normotensive group, 119.5 +/- 2.7 mm Hg in the dialysis-sensitive hypertension group, and 134.4 +/- 3.8 mm Hg in the dialysis-refractory hypertension group (P < 0.05 for comparisons between all groups). Mean arterial pressure did not change predialysis and postdialysis in the normotensive group (94.9 +/- 1.9 mm Hg to 93.1 +/- 1.8 mm Hg, respectively; P = 0.24), decreased in the dialysis-sensitive hypertension group (119.5 +/- 2.7 mm Hg to 100.8 +/- 3.7 mm Hg, respectively; P < 0.0001), and did not change in the dialysis-refractory hypertension group (134.4 +/- 3.8 mm Hg to 133.8 +/- 2.9 mm Hg, respectively; P = 0.77). Predialysis and postdialysis serum ANP levels were, respectively, 235.8 +/- 27.7 pg/mL and 237.8 +/- 36.2 pg/mL (P = 0.92) in the normotensive group, 809.2 +/- 295.5 pg/mL and 161.1 +/- 48.6 pg/mL (P = 0.03) in the dialysis-sensitive hypertension group, and 1,728.3 +/- 309.9 pg/mL and 1,936.1 +/- 359.1 pg/mL (P = 0.22) in the dialysis-refractory hypertension group. Mean predialysis ANP levels were higher in the dialysis-refractory hypertension group than in the dialysis-sensitive hypertension group (1,728.3 +/- 309.9 pg/mL v 809 +/- 359.1 pg/mL; P = 0.048). Mean prehemodialysis ANP in all hypertensive patients (n = 21) was higher (1,203.1 +/- 232.9) than in the normotensive patients (235.8 +/- 27.7) (P = 0.004). In conclusion, our findings are consistent with a hypothesis that inadequate removal of excess volume during hemodialysis plays a major role in dialysis-refractory hypertension.