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Biomedical subjects

S Q Lew

Publications and source records attributed to S Q Lew.

At least 19 recordsLinked to original sources
PubMed2001

Biocompatibility of hemodialysis membranes: interrelations between plasma complement and cytokine levels.

Hemodialysis (HD) membrane biocompatibility is defined as absence of complement activation. We have recently shown that circulating levels of interleukin (IL) 1 and IL-2 predict death and survival, respectively, of HD patients. Studies have assessed IL-1 in treatments with biocompatible and less biocompatible dialysis membranes, but no study has correlated circulating levels of all these immunoreactants. We assessed these immunoreactants, and temperature as an outcome, during HD in patients treated with different membranes. Twelve stable patients, receiving thrice-weekly chronic bicarbonate HD, were randomly dialyzed with three different types of membranes, composed of: Cuprophan, cuprammonium rayon modified cellulose, and Hemophan. Blood was drawn from the arterial line port before (Pre) and 15, 30, and 60 min during and after (Post) HD. Patients' temperatures were measured before and after each treatment. The plasma concentrations of IL-1 and IL-2 and factors C3a and C5a were assessed by ELISA. There were no differences between baseline levels of any of the immunoreactants in patients treated with different dialyzers. C3a, C5a, and IL-1 levels increased significantly during HD treatments with all three different membranes. C3a, C5a, and IL-1 levels during Cuprophan and Hemophan treatments were significantly higher than the levels during modified cellulose treatment at 30 and 60 min and Post (p < 0.01). For all the immunoreactants, however, the Post levels were higher than the Pre levels. In contrast to IL-1, there were no differences in mean IL-2 levels during treatments when different membranes were compared. There were few correlations of plasma C3a and C5a levels with plasma IL-1 levels, but there was only one treatment time in one dialyzer group during which IL-2 and any of the other factors were correlated. Pre and Post temperature values and percent change in temperature were not correlated with any of the immunoreactants measured. These data show that C3a, C5a, and IL-1 responses are similar, but not identical, during treatments with different membranes. The response of circulating IL-2 levels to treatments is quite different from that of plasma C3a, C5a and IL-1 levels and suggests that these changes are not solely due to treatment factors. Treatment with modified cellulose membranes is associated with a different immunoreactive profile as compared with patients dialyzed using other cellulose membranes. We suggest that circulating IL-1 levels are good biocompatibility markers.

Adult↗
PubMed2000

Ethical issues in aging and renal disease.

The incidence of elderly patients reaching end-stage renal disease (ESRD) and requiring renal replacement is increasing. Better medical care is helping patients live longer but, at the same time, is raising ethical questions. Treatment decisions for ESRD patients present a forum for the consideration of ethical questions surrounding the issues of scarce health care resource allocation and the withholding or withdrawal of life-sustaining treatment. As background for the consideration of ethical issues in ESRD patients, the quality of life they experience and what they may expect as death approaches also are discussed.

Aged↗
PubMed2000

Renal abnormalities in sickle cell disease.

Renal abnormalities in sickle cell disease. Sickle cell nephropathy is indicated by sickled erythrocytes, with the consequent effects of decreased medullary blood flow, ischemia, microinfarct and papillary necrosis. Impaired urinary concentrating ability, renal acidification, hematuria, and potassium secretion are also found. There may be a causal relationship between an increase in nitric oxide synthesis and experimental sickle cell nephropathy, and some studies have indicated that the progression of sickle cell nephropathy is hemodynamically mediated. Although there are many studies showing that proteinuria, nephrotic syndrome, chronic progressive renal failure, and acute renal failure syndromes are the outcome of this disease, the pathogenic mechanism(s) and potential therapies remain to be elucidated. Survival of patients with sickle cell nephropathy who progress to end-stage renal disease (ESRD) is equal to non-diabetic ESRD patients, and graft survival rates are also similar for those who undergo renal transplantation. This article presents a historical review of the glomerular and tubular disorders associated with sickle cell nephropathy, and reviews therapeutic indications to slow its progression. Further research is needed.

Anemia, Sickle Cell↗
PubMed2000

Moderate metabolic acidosis and its effects on serum parameters in hemodialysis patients.

We screened the laboratory data of 50 chronic hemodialysis patients selected randomly over a 21-month period to generate 158 data points which identified two groups: (1) those with a predialysis total CO(2) concentration less than or equal to 19 mEq/l (data A; n = 57) and (2) those with a predialysis total CO(2) concentration greater than 19 mEq/l (data B; n = 101). Then, both groups were compared for the following parameters: predialysis blood urea nitrogen (BUN), serum phosphorus, uric acid, creatinine, and albumin concentrations, Kt/V, urea reduction ratio, normalized protein catabolic rate, dry weight, ultrafiltration, blood flow and dialysis flow rates, duration of dialysis treatment, and blood pressure. Group data A had significantly higher predialysis BUN, phosphorus, and uric acid concentrations than group data B. There were significant inverse correlations between predialysis serum bicarbonate and predialysis BUN, phosphorus, and uric acid concentrations. Although it is not clear what the long term side effects of moderate metabolic acidosis are, we recommend its correction.

Acidosis↗
PubMed1999

Peritoneal dialysis-associated peritonitis caused by Propionibacteria species.

There are an increasing number of reports about unusual causes of peritonitis in peritoneal dialysis (PD) patients. The Propionibacteria species is a microorganism that is a normal skin flora. Under the presence of certain risk factors, it may produce serious infections. Patients at risk of having Propionibacteria sp infections have malignancy, diabetes mellitus, foreign bodies, or immunodeficiency. We describe a PD-associated peritonitis in a 51-year-old woman that was caused by Propionibacteria sp. This patient's risk factors for developing Propionibacteria sp peritonitis include a history of CREST syndrome, malignancy of the breast, and recent catheter surgery. To our knowledge, this is the first case of a PD-associated peritonitis caused by Propionibacteria sp reported in the literature.

Breast Neoplasms↗
PubMed1999

Women issues in female patients receiving peritoneal dialysis.

About 50% of the population receiving peritoneal dialysis (PD) in the United States are women. Nephrologists generally address medical issues related to end-stage renal disease, ie, anemia, hypercholesterolemia, secondary hyperparathyroidism. In female PD patients, specific topics should also be addressed. They include menstruation, birth control methods, osteoporosis, child bearing, postmenopausal hormone replacement and its consequences, screening of gynecological malignancies, sexual problems, and hemoperitoneum. We briefly describe in a multidisciplinary view the management of these issues.

Adult↗
PubMed1999

Biochemical parameters, nutritional status and efficiency of dialysis in CAPD and CCPD patients.

BACKGROUND/AIMS: Several studies indicate that small solute transport is influenced by peritoneal dialysate volume and dwell time. This study focuses on the clinical impact of peritoneal dialysis modality, continuous ambulatory peritoneal dialysis (CAPD) and continuous cycling peritoneal dialysis (CCPD). METHODS: We studied 18 patients on CAPD and 11 on CCPD for 18 months and assessed biochemical parameters, nutritional status and efficiency of dialysis at 6-month intervals. RESULTS: Four-hour D/P urea and creatinine ratios were similar in both CAPD and CCPD patients. However, 24-hour D/P urea and creatinine ratios were significantly higher in CAPD than in CCPD patients (0.9 +/- 0.1 vs. 0.8 +/- 0.2 and 0.8 +/- 0.1 vs. 0.6 +/- 0.2, p < 0.05 and p < 0.01, respectively). The dialysate urea nitrogen concentration was significantly different between the two groups (65 +/- 14 mg/dl in CAPD, 48 +/- 13 mg/dl in CCPD; p < 0.05). Total weekly Kt/V and total weekly creatinine clearance were not significantly different between CAPD and CCPD patients at 18 months (1.6 +/- 0.4 vs. 1.7 +/- 0.3 and 52 +/- 21 vs. 50 +/- 12 liters, respectively). Two-way ANOVA with a post-hoc Bonferroni-Dunn test showed serum potassium concentration was significantly lower in CCPD patients at 18 months (3.8 +/- 0.5 mEq/l, p < 0.05), and significant increases in triglyceride levels in the CAPD groups by 18 months (301 +/- 286 mg/dl, p < 0.05). CONCLUSION: This study demonstrates that the mean serum triglyceride level increases in CAPD patients over time, and the mean serum potassium concentration decreases in CCPD patients at 18 months. Dialysis adequacy and nutritional status are not significantly different between the two peritoneal dialysis modalities, CAPD and CCPD. We suggest the peritoneal dialysis prescription for CAPD or CCPD with respect to volume and frequency of exchanges be individualized to achieve adequate of therapy.

Adult↗
PubMed1999

Mycobacterium fortuitum peritonitis in two patients receiving continuous ambulatory peritoneal dialysis.

We present two cases of non-resolving peritonitis treated with a standard peritonitis protocol. The organism identified from the peritoneal effluent was Mycobacterium fortuitum, a group IV (Runyon's classification) rapidly growing, nontuberculous mycobacterium. M. fortuitum is ubiquitous and can be isolated from a number of natural sources. Risk factors these two patients had for developing M. fortuitum peritonitis included underdialysis, the immunocompromised state associated with end stage renal disease, prior or prolonged broad spectrum antibiotic treatment, and possible exposure to environmental factors, since both were hospitalized at about the same time. The isolates were resistant to the conventional antibiotics recommended for the treatment of this mycobacterium. Both patients, however, responded to catheter removal and antibiotics administered according to the sensitivities of the mycobacterium isolated.

Adult↗
PubMed1999

Outcome of an opportunistic infection after polymicrobial peritonitis in an HIV-infected patient treated with peritoneal dialysis.

The prevalence of human immuodeficiency virus (HIV)-infected patients with end stage renal disease (ESRD) is likely to increase and many of them will be on peritoneal dialysis as renal replacement therapy. Infectious complications are a major problem associated with peritoneal dialysis (PD). It has been speculated that the HIV-positive peritoneal dialysis population may develop peritonitis more frequently than other peritoneal dialysis patients. We present the complications and unexpected good response to medical management of PD-associated peritonitis in a young HIV-infected black male. He had two unusual and serious infections; the first was a polymicrobial peritonitis which predisposed the patient to an unusual infection caused by Corynebacteria JK for which he was successfully treated without catheter removal.

AIDS-Related Opportunistic Infections↗
PubMed1998

Raw shellfish consumption among renal disease patients. A risk factor for severe Vibrio vulnificus infection.

BACKGROUND: Raw shellfish-associated Vibrio vulnificus septicemia, with a case-fatality rate of nearly 50%, occurs most commonly in immunocompromised patients or those with liver disease. METHODS: Sixty patients with renal disease treated with hemodialysis at The George Washington University and awaiting renal transplantation completed an initial survey that assessed their raw shellfish eating habits and knowledge regarding the pathogen V. vulnificus. Patients were then given educational materials describing the risks of eating raw shellfish and, one month later, completed a second survey that assessed their knowledge retention and intent to eat or not eat raw shellfish in the future. RESULTS: Sixty of 68 (88%) eligible patients completed the survey. Forty-eight percent of patients reported having eaten raw shellfish after being diagnosed with kidney disease, with the highest rates reported among subjects < or = 49 years old and subjects with more than a high school education. Prior to receiving the educational materials, no patient had heard of the pathogen V. vulnificus. Three quarters of patients reported never having been advised by a physician to avoid eating raw shellfish. One month after reading the educational materials, 75% of patients said they would refrain from eating raw shellfish in the future. CONCLUSIONS: In view of their immunocompromised status, patients with end-stage renal disease should be counseled to abstain from eating raw shellfish.

Adolescent↗
PubMed1998

Equal levels of blood pressure control in ESRD patients receiving high-efficiency hemodialysis and conventional hemodialysis.

The present study compared the status of hypertension and adequacy of blood pressure control in 73 end-stage renal disease (ESRD) patients treated with four different modalities of hemodialysis, namely, conventional hemodialysis (CHD) with cuprophan 1.1 m2 at a blood flow rate of 300 mL/min, high-efficiency hemodialysis (HED) with cuprophan 1.6 m2 at a blood flow rate of 450 to 500 mL/min, high-flux hemodialysis (HFD) with F80 polysulfone 1.8 m2 at a blood flow rate 500 mL/min, and high-flux hemodiafiltration (HDF) with F80 2 x 1.8 m2 in series at a blood flow rate of 600 to 650 mL/min. Thirty of the 73 patients (41%) were receiving one or more antihypertensive agents to control their hypertension. The percentage of patients taking antihypertensive medication was less in the groups treated with HED, HFD, and HDF compared with the CHD group: 38%, 39%, and 39%, respectively, in the HED, HFD, and HDF groups versus 56% in the CHD group. Control of systolic and diastolic hypertension was achieved in a higher percentage of patients treated with HED, HFD, and HDF compared with patients treated with CHD. Sixty-two percent of HED, 58% of HFD, and 61% of HDF patients compared with 44% of CHD patients had systolic blood pressure less than 150 mm Hg, whereas 77% of HED, 76% of HFD, and 78% of HDF patients compared 56% of CHD patients had diastolic blood pressure less than 90 mm Hg. However, the differences in the use of antihypertensive medication and control rates of hypertension did not reach statistical significance. The average blood pressure of all patients was 144/89 mm Hg; this did not differ significantly between the four groups. There also were no significant differences in etiology of ESRD, hematocrit, biochemical data, as well as use and dose of recombinant human erythropoietin between the four groups. Compared with the CHD patients, the average treatment times with high-efficiency treatments were shorter, with HDF patients showing the shortest mean treatment time of 157+/-41 minutes per hemodialysis session. The mean Kt/V was higher in the groups treated with HED, HFD, or HDF (1.31+/-0.3, 1.30+/-0.4, and 1.43+/-0.3, respectively) than in the CHD group (1.12+/-0.3; P < 0.05). Interdialytic weight gain also did not differ among the four groups. There was no correlation between predialysis mean arterial pressure and either treatment time (r = 0.04, P = NS), Kt/V (r = 0.03, P = NS), ultrafiltration rate (r = 0.06, P = NS), or interdialytic weight gain (r= -0.08, P = NS). There also was no significant association between Kt/V and use of antihypertensive medications (chi-square = 1.76, P = NS). There was, however, a significant positive correlation between interdialytic weight gain and treatment time (r = 0.33, P < 0.01). We conclude that the use of short dialysis sessions with efficient hemodialysis treatments, namely, HFD and HDF, was associated with similar levels of blood pressure control in ESRD patients.

Adult↗
PubMed1998

Assessment of PD treatment delivered by 125I-Iothalamate plasma disappearance.

The calculation of treatment delivered to PD patients requires the collection of PD effluent, plasma and urine samples. 125I-Iothalamate plasma disappearance, which eliminates the need for PD effluent collections, was tested as an alternate method to measure the weekly PD treatment delivered. Two protocols were designed. In protocol A, a 35 microCi dose of 125I-Iothalamate was injected in three subjects and allowed to equilibrate. A plasma sample was taken and patients returned on both of the following two days with timed labeled effluent bags and a 24-hour urine collection for each day. The timed PD effluent and 24-hour urine collections were measured for 125I-Iothalamate, urea and creatinine concentrations. 125I-Iothalamate and urea clearances were strongly correlated for both PD (R2 = 0.76, n = 24) and renal (R2 = 0.92, n = 6) clearances. In protocol B, thirteen subjects were given a 35 microCi injection of 125I-Iothalamate. A blood sample was taken one hour post injection and a second blood sample taken on day five. Kt/V were calculated from the 125I-Iothalamate plasma disappearance curve and compared to weekly Kt/V values extrapolated from one day's collections (Traditional Method). The comparison of Kt/V values found by 125I-Iothalamate Method vs. the "Traditional Method" yielded R2 = 0.79, n = 13. In conclusion, the plasma disappearance of 125I-Iothalamate is an alternate method of determining weekly Kt/V, over an extended period of time, which eliminates the need for PD effluent collections.

Creatinine↗
PubMed1998

The effects of increasing exchange volume and frequency on peritoneal dialysis adequacy.

AIM: Peritoneal dialysis adequacy guidelines are generally not met with the standard prescription of continuous ambulatory peritoneal dialysis (CAPD), four 2-liter (1) exchanges daily. The aim of this study is to determine the effects of increasing exchange volume singularly or in combination with frequency on peritoneal dialysis adequacy. PATIENTS AND METHODS: Fourteen stable ESRD patients receiving peritoneal dialysis were evaluated for adequacy and nutritional status between the fourth and sixth months during a six-month baseline period in which the dialysis prescription was four two-liter exchanges daily and during a six-month intervention period in which patients (n = 7) from group 1 were prescribed CAPD four 2.5-liter exchanges daily while patients (n = 7) from group 2 were prescribed continuous cycling peritoneal dialysis (CCPD - 12 l) using four 2.5 liters during the night and a 2-liter wet day. RESULTS: Mean total weekly urea Kt/V (TWKt/V) increased significantly from 1.6 +/- 0.2 to 2.1 +/- 0.2, p <0.01 in group 1, and from 1.6 +/- 0.4 to 2.1 +/- 0.5, p <0.001 in group 2. Mean normal total weekly creatinine clearance increased significantly from 51 +/- 11 to 60 +/- 8 l/1.73 m2, p <0.05 in group 1, and from 45 +/- 6 to 58 +/- 9 l/1.73 m2, p <0.01 in group 2. Serum albumin of almost all patients in the intervention groups were higher than in the baseline groups. Mean serum albumin increased from 3.6 +/- 0.4 to 4.0 +/- 0.4 g/dl, p <0.01 in group 1, and from 3.8 +/- 0.2 to 4.0 +/- 0.4, p <0.05 in group 2. The magnitude of the decrement in BUN and serum creatinine were greater in group 2 than group 1 (p <0.001 and p <0.05, respectively). When the two intervention groups were compared to each other, no significant differences in the delivered dialysis dose or nutritional status were noted. CONCLUSION: In conclusion, it is possible to achieve currently proposed adequacy target by increasing the exchange volume singularly or in combination with frequency in most peritoneal dialysis patients.

Adult↗
PubMed1997

Control of hypertension is better during hemodialysis than during continuous ambulatory peritoneal dialysis in ESRD patients.

This study compared the status and adequacy of blood pressure (BP) control in 21 ESRD patients treated with HD and CAPD at different time periods. Patients were considered to be hypertensive it they were receiving antihypertensive medications during the study period. During HD, 9 of the 21 patients (43%) required antihypertensive drugs to control their hypertension; whereas, during CAPD, the number of patients taking antihypertensive drugs increased to 15 (71%) (p < 0.05). Adequate control of hypertension (systolic BP < 150 mmHg and/or diastolic BP < 90 mmHg) was achieved in 17 patients (81%) during HD compared to 11 patients (52%) during CAPD (p < 0.05). Average ultrafiltration rate was 1.28 +/- 0.1 l/day during HD and 1.30 +/- 0.2 l/day during CAPD (p = NS). Mean Kt/V during HD was 1.24 +/- 0.1; whereas, mean weekly Kt/V during CAPD was 1.81 +/- 0.2. There were no significant differences in hematocrit or usage of recombinant human erythropoietin (rHuEPo) between the two treatment modalities. However, the weekly dose of rHuEpo was higher during HD than during CAPD (p < 0.05). Mean body weight was significantly higher (p < 0.01) and serum albumin was lower (p < 0.05) during CAPD than during HD in the same group of patients. We conclude that hypertension appears to be controlled better by HD than by CAPD in ESRD patients. The gain in body weight observed with CAPD treatment may reflect an increase in total body fluid volume which may partly explain why hypertension is less adequately controlled during CAPD than during HD treatment.

Blood Pressure↗
PubMed1996

Zinc modulates mononuclear cellular calcitriol metabolism in peritoneal dialysis patients.

Zinc has long been known to play a role in maintaining immunologic function. Hypozincemia, however, is common in patients with end-stage renal disease (ESRD) treated with continuous ambulatory peritoneal dialysis (CAPD). We previously demonstrated that zinc depletion limits the ability of animals to achieve maximum circulating calcitriol levels in response to the stress of calcium or phosphorus depletion. It was unclear, however, whether changes in the circulating levels of calcitriol in these settings was associated with a direct effect on renal 1-alpha hydroxylase activity, or whether the zinc dependence of the stimulated calcitriol response involved an integrated systemic response in intact animals. In addition it was unclear whether circulating zinc levels or zinc nutritional status modified calcitriol metabolism in humans. To better understand the role zinc plays in the immune response in patients with ESRD, we studied IL-1, calcitriol and tumor necrosis factor-alpha production by mononuclear cells from blood and peritoneal effluents of 22 patients with ESRD treated with CAPD. Macrophages from peritoneal effluents and peripheral blood mononuclear cells were isolated and pulsed with phytohemagglutinin in medium to which different concentrations of zinc chloride, copper chloride, and carbonyl cyanide p-(trifluoromethoxy)-phenyl-hydrazone (FCCP), an inhibitor of mitochondrial function were added. Supernatant interleukin-1, calcitriol, and tumor necrosis factor-alpha levels were subsequently measured. We demonstrated a zinc concentration dependent increase in stimulated IL-1 alpha and -beta, and TNF-alpha release in both peripheral mononuclear cells and peritoneal macrophages from patients with ESRD treated with CAPD. The effect is zinc specific, as it is not reproduced by copper or chloride supplementation. A zinc concentration dependent increase in peritoneal macrophage calcitriol release was also noted. FCCP blocked the cellular production of IL-1 alpha, IL-1 beta, and TNF-alpha, but had little effect on zinc-induced stimulated mononuclear cell supernatant calcitriol levels. The different shape of the zinc dose response curve, and the lack of correlation between paired IL-1 and calcitriol supernatant levels suggests the effect of zinc on mononuclear cellular cytokine and calcitriol production is mediated through different pathways.

Animals↗
PubMed1996

Nutrition, ageing and GFR: is age-associated decline inevitable?

Due to the paucity of long-term observational data, it is still unclear whether the decreased glomerular filtration rate (GFR) noted in older humans is a results of true changes in renal function over time. The fact that a carefully characterized subpopulation of subjects showed no decrease in GFR over time suggests that the 'physiological decrease' in GFR noted in the elderly is not inevitable. In studies in our patient population, there was a significant correlation between creatinine clearance and nutritional protein intake in elderly patients without renal disease. In our studies, elderly subjects without renal disease who ingested > 1 g/kg day of protein had creatinine clearances in the range of 90-100 ml/min/1.73 m2, while those with lower protein intakes had lower creatinine clearances. Our studies suggest that GFR is not a fixed function, and that its value may change both over short periods and over decades in humans, with these changes being associated with changes in nutritional protein intake. Low levels of GFR are not necessarily equivalent to a diagnosis of renal disease. Diet must be considered in the assessment of renal function in elderly patients before a diagnosis of renal insufficiency can be made. Decreased GFR is not an inevitable consequence of ageing in humans.

Aging↗