Peritoneal Catheters and Exit-Site Practices toward Optimum Peritoneal Access: A Review of Current Developments

Objective

This review updates the 1998 International Society for Peritoneal Dialysis (ISPD) recommendations for peritoneal dialysis catheters and exit-site practices (Gokal R, et al. Peritoneal catheters and exit-site practices toward optimum peritoneal access: 1998 update. Perit Dial Int 1998; 18:11–33.)

Design

Data Sources: The Ovid and PubMed search engines were used to review the Medline databases of January 1980 through June 2003. Searches were restricted to human data; primary key word searches included dialysis, peritoneal dialysis, and continuous ambulatory peritoneal dialysis cross referenced with access, catheter, dialysis catheter, peritoneal dialysis catheter, and Tenckhoff catheter. Related searches were provided via the PubMed related articles link. Study Selection: Reports were selected if they provided identifiable information on catheter design, catheter placement technique, and survival or placement complications. Reports without such data were excluded from review. Each study was then categorized by its characteristics: single-center or multicenter; retrospective or prospective; controlled trial, with or without random patient assignment; or review article.

Main Results

There are few randomized controlled evaluations testing how catheter design and/or placement influence long-term survival and function, and these are typically conducted at a single center. The majority of reports represent retrospective single-center experiences, and these are supplemented by occasional multicenter data registries.

Conclusions

There is substantial variability in catheter outcomes between centers, and this variability is more closely correlated with operator and center characteristics than with catheter design. Some catheter designs appear to impact long-term catheter success, and, in some cases, specific patient characteristics and dialysis formats combine with specific catheter designs to influence catheter survival. Most reporters prefer two-cuff designs and placement of the deep cuff at an intramuscular location. Intramuscular cuff placement results in fewer pericatheter leaks and hernias, but makes catheter removal more difficult. High-risk patients (those with previous pelvic surgery) benefit from visual inspection of the peritoneum during catheter placement, and in randomized controlled trials, catheters with pre-shaped arcuate subcutaneous segments (“swan neck” designs) reduce the risk of early drainage failure via “migration.”

Transdisciplinary synthesis for ecosystem science, policy and management: The Australian experience

Mitigating the environmental effects of global population growth, climatic change and increasing socio-ecological complexity is a daunting challenge. To tackle this requires synthesis: the integration of disparate information to generate novel insights from heterogeneous, complex situations where there are diverse perspectives. Since 1995, a structured approach to inter-, multi- and trans-disciplinary(1) collaboration around big science questions has been supported through synthesis centres around the world. These centres are finding an expanding role due to ever-accumulating data and the need for more and better opportunities to develop transdisciplinary and holistic approaches to solve real-world problems. The Australian Centre for Ecological Analysis and Synthesis (ACEAS <http://www.aceas.org.au>) has been the pioneering ecosystem science synthesis centre in the Southern Hemisphere. Such centres provide analysis and synthesis opportunities for time-pressed scientists, policy-makers and managers. They provide the scientific and organisational environs for virtual and face-to-face engagement, impetus for integration, data and methodological support, and innovative ways to deliver synthesis products. We detail the contribution, role and value of synthesis using ACEAS to exemplify the capacity for synthesis centres to facilitate trans-organisational, transdisciplinary synthesis. We compare ACEAS to other international synthesis centres, and describe how it facilitated project teams and its objective of linking natural resource science to policy to management. Scientists and managers were brought together to actively collaborate in multi-institutional, cross-sectoral and transdisciplinary research on contemporary ecological problems. The teams analysed, integrated and synthesised existing data to co-develop solution-oriented publications and management recommendations that might otherwise not have been produced. We identify key outcomes of some ACEAS working groups which used synthesis to tackle important ecosystem challenges. We also examine the barriers and enablers to synthesis, so that risks can be minimised and successful outcomes maximised. We argue that synthesis centres have a crucial role in developing, communicating and using synthetic transdisciplinary research.

Wistar rats acquire and maintain self-administration of 20 % ethanol without water deprivation, saccharin/sucrose fading, or extended access training

RATIONALE

Operant self-administration (SA) is an important model of motivation to consume ethanol (EtOH), but low rates of voluntary consumption in rats are thought to necessitate water deprivation and saccharin/sucrose fading for acquisition of responding.

OBJECTIVES

Here, we sought to devise an effective model of SA that does not use water deprivation or saccharin/sucrose fading.

METHODS

First, we tested if Wistar rats would acquire and maintain SA behavior of 20 % EtOH under two conditions, water deprivation (WD) and non-water deprivation (NWD). Second, we tested the efficacy of our SA procedure by confirming a prior study which found that the NK1 antagonist L822429 specifically blocked stress-induced reinstatement of EtOH seeking but not SA. Finally, we assessed the effect of naltrexone, an FDA-approved medication for alcohol dependence that has been shown to suppress EtOH SA in rodents.

RESULTS

Lever presses (LPs) and rewards were consistent with previous reports that utilized WD and saccharin/sucrose fading. Similar to previous findings, we found that L822429 blocked stress-induced reinstatement but not baseline SA of 20 % EtOH. Moreover, naltrexone dose-dependently decreased alcohol intake and motivation to consume alcohol for rats that are self-administering 20 % EtOH.

CONCLUSIONS

Our findings provide a method for voluntary oral EtOH SA in rats that is convenient for experimenters and eliminates the potential confound of sweeteners in EtOH-operant SA studies. Unlike models that use intermittent access to 20 % EtOH, this method does not induce escalation, and based on pharmacological experiments, it appears to be driven by the positive reinforcing effects of EtOH.

Dissociation between progression of coronary artery calcification and endothelial function in hemodialysis patients: a prospective pilot study

Chronic kidney disease profoundly disturbs calcium-phosphate metabolism and predisposes to premature atherosclerosis. Both coronary artery calcification (CAC) and endothelial dysfunction are common in hemodialysis (HD) patients. We hypothesized that a calcium-free phosphate binder would improve endothelial function and delay progression of vascular calcification in HD patients.

METHODS

This was a randomized parallel-group trial in HD patients comparing lanthanum carbonate (LC) with a non-LC phosphorus binders control group (non-LC) at a 1 : 1 randomization. CAC was obtained at baseline, 6, and 12 months, and endothelial function (brachial artery flow-mediated dilation - FMD) at baseline and 6 months.

RESULTS

13 patients were randomized (LC n = 7 and non-LC n = 6). CAC scores (Log ± SE) at baseline were 7.21 ± 0.62 (LC) and 6.07 ± 0.73 (control). CAC increased in the non-LC group (33 ± 17% and 77 ± 22% at 6 and 12 months), but tended to decrease in the LC group (-10 ± 11% and -2 ± 11% at 6 and 12 months). There was statistically less progression in CAC in the LC group compared to control at 6 (p = 0.002) and 12 months (p = 0.003). There was no difference between groups in FMD (p = 0.7). Markers of inflammation did not change significantly.

CONCLUSION

A slower rate of progression of CAC occurred in the LC group, independent of changes in FMD. This is the first study showing dissociation between progression of CAC and FMD in HD patients. Larger studies are warranted to elucidate the impact of different phosphate sequestration therapies on atherosclerosis in HD patients.

Coordinated dysregulation of mRNAs and microRNAs in the rat medial prefrontal cortex following a history of alcohol dependence

Long-term changes in brain gene expression have been identified in alcohol dependence, but underlying mechanisms remain unknown. Here, we examined the potential role of microRNAs (miRNAs) for persistent gene expression changes in the rat medial prefrontal cortex (mPFC) after a history of alcohol dependence. Two-bottle free-choice alcohol consumption increased following 7-week exposure to intermittent alcohol intoxication. A bioinformatic approach using microarray analysis, quantitative PCR (qPCR), bioinformatic analysis and microRNA-messenger RNA (mRNA) integrative analysis identified expression patterns indicative of a disruption in synaptic processes and neuroplasticity. About 41 rat miRNAs and 165 mRNAs in the mPFC were significantly altered after chronic alcohol exposure. A subset of the miRNAs and mRNAs was confirmed by qPCR. Gene ontology categories of differential expression pointed to functional processes commonly associated with neurotransmission, neuroadaptation and synaptic plasticity. microRNA-mRNA expression pairing identified 33 miRNAs putatively targeting 89 mRNAs suggesting transcriptional networks involved in axonal guidance and neurotransmitter signaling. Our results demonstrate a significant shift in microRNA expression patterns in the mPFC following a history of dependence. Owing to their global regulation of multiple downstream target transcripts, miRNAs may have a pivotal role in the reorganization of synaptic connections and long-term neuroadaptations in alcohol dependence. MicroRNA-mediated alterations of transcriptional networks may be involved in disrupted prefrontal control over alcohol drinking observed in alcoholic patients.

Directional limits on persistent gravitational waves using LIGO S5 science data

The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence level (C.L.) upper-limit maps of GW strain power with typical values between 2-20×10(-50)  strain(2) Hz(-1) and 5-35×10(-49)  strain(2) Hz(-1) sr(-1) for pointlike and extended sources, respectively. The latter result is the first of its kind. We also set 90% C.L. limits on the narrow-band root-mean-square GW strain from interesting targets including Sco X-1, SN 1987A and the Galactic center as low as ≈7×10(-25) in the most sensitive frequency range near 160 Hz.

Associations between CMS's Clinical Performance Measures project benchmarks, profit structure, and mortality in dialysis units

Prior studies observing greater mortality in for-profit dialysis units have not captured information about benchmarks of care. This study was undertaken to examine the association between profit status and mortality while achieving benchmarks. Utilizing data from the US Renal Data System and the Centers for Medicare & Medicaid Services' end-stage renal disease (ESRD) Clinical Performance Measures project, hemodialysis units were categorized as for-profit or not-for-profit. Associations with mortality at 1 year were estimated using Cox regression. Two thousand six hundred and eighty-five dialysis units (31,515 patients) were designated as for-profit and 1018 (15,085 patients) as not-for-profit. Patients in for-profit facilities were more likely to be older, black, female, diabetic, and have higher urea reduction ratio (URR), hematocrit, serum albumin, and transferrin saturation. Patients (19.4 and 18.6%) in for-profit and not-for-profit units died, respectively. In unadjusted analyses, profit status was not associated with mortality (hazard ratio (HR)=1.04, P=0.09). When added to models with profit status, the following resulted in a significant association between profit status (for-profit vs not-for-profit) and increasing mortality risk: URR, hematocrit, albumin, and ESRD Network. In adjusted models, patients in for-profit facilities had a greater death risk (HR 1.09, P=0.004). More patients in for-profit units met clinical benchmarks. Survival among patients in for-profit units was similar to not-for-profit units. This suggests that in the contemporary era, interventions in for-profit dialysis units have not impaired their ability to deliver performance benchmarks and do not affect survival.

ThurGood: evaluating assembly-to-assembly mapping

The alignment and mapping of large genomic sequences is the focus of much recent research. However, relatively little has been done so far about testing and validating alignment methods. We introduce criteria and new tools we have developed for alignment evaluation. These tools have already proved useful in the evaluation and ranking of several methods for assembly-to-assembly mapping, which were recently used to map multiple versions of the human genome to each other (Istrail et aL, 2004).

Peritoneal catheters and exit-site practices toward optimum peritoneal access: a review of current developments

OBJECTIVE

This review updates the 1998 International Society for Peritoneal Dialysis (ISPD) recommendations for peritoneal dialysis catheters and exit-site practices (Gokal R, et al. Peritoneal catheters and exit-site practices toward optimum peritonealaccess: 1998 update. Perit Dial Int 1998; 18:11-33.)

DESIGN

DATA SOURCES

The Ovid and PubMed search engines were used to review the Medline databases of January 1980 through June 2003. Searches were restricted to human data; primary key word searches included dialysis, peritoneal dialysis, and continuous ambulatory peritoneal dialysis cross referenced with access, catheter, dialysis catheter, peritoneal dialysis catheter, and Tenckhoff catheter. Related searches were provided via the PubMed related articles link.

STUDY SELECTION

Reports were selected if they provided identifiable information on catheter design, catheter placement technique, and survival or placement complications. Reports without such data were excluded from review. Each study was then categorized by its characteristics: single-center or multicenter; retrospective or prospective; controlled trial, with or without random patient assignment; or review article.

MAIN RESULTS

There are few randomized controlled evaluations testing how catheter design and/or placement influence long-term survival and function, and these are typically conducted at a single center. The majority of reports represent retrospective single-center experiences, and these are supplemented by occasional multicenter data registries.

CONCLUSIONS

There is substantial variability in catheter outcomes between centers, and this variability is more closely correlated with operator and center characteristics than with catheter design. Some catheter designs appear to impact long-term catheter success, and, in some cases, specific patient characteristics and dialysis formats combine with specific catheter designs to influence catheter survival. Most reporters prefer two-cuff designs and placement of the deep cuff at an intramuscular location. Intramuscular cuff placement results in fewer pericatheter leaks and hernias, but makes catheter removal more difficult. High-risk patients (those with previous pelvic surgery) benefit from visual inspection of the peritoneum during catheter placement, and in randomized controlled trials, catheters with pre-shaped arcuate subcutaneous segments ("swan neck" designs) reduce the risk of early drainage failure via "migration."

Dialysate composition and hemodialysis hypertension

Dialysis prescriptions have evolved to take advantage of new technology and serve a burgeoning patient population. High-sodium bicarbonate-based dialysate was first formulated in 1982 to enable short, safe, comfortable, high-efficiency hemodialysis (HD). Near-universal adaptation of these high-sodium formulas has virtually eliminated profound dialysis disequilibrium and greatly reduced dialysis discomfort, but has created a syndrome of dialysis salt loading with accentuated postdialysis thirst, interdialytic weight gain, and hypertension. Available technology will soon permit individuals to receive isonatremic dialysis with dialysate customized to the patient's serum sodium activity. Then, rather than choosing between comfortable, safe, high-efficiency dialysis with salt loading; cramps, asthenia, and symptomatic hypotension using low-sodium, high-efficiency rapid HD to control blood pressure (BP) and weight gain; or comfortable, slow, low-efficiency HD with BP control, physicians may be able to minimize symptoms and avoid dialysis salt loading while providing maximum time for rehabilitative activities. The current use of a single sodium activity for all patients ignores the inter- and intraindividual variability in serum sodium activity in our patients. This results in undesired consequences for 20-40% of patients. The application of even more severe salt loading through high-salt sodium modeling only accentuates the long-term problems of excessive thirst, weight gain, and hypertension.

Near-infrared spectroscopic measurement of urea in dialysate samples collected during hemodialysis treatments

Single-beam spectra were collected over the combination region of the near-infrared spectrum for 80 samples collected from 15 people over a two-week period. Partial least-squares (PLS) regression was used to generate an optimized calibration model for urea. PLS calibration models accurately measure urea in the spent dialysate matrix. Prediction errors are on the order of 0.15 mM, which is sufficient for the clinical assessment of the dialysis process. In addition, the feasibility of a global calibration model is demonstrated by generating a calibration model from samples and spectra obtained from 12 people to predict the level of urea in samples collected from 3 different people. In this case, the standard error of prediction is 0.09 mM. Spectra were modified in order to systematically examine the impact of resolution and noise. Little impact is observed by altering the spectral resolution from 4 to 32 cm-1. Spectral noise, however, plays an important role in the accuracy of these calibration models. Increasing the magnitude of the spectral noise increases the prediction errors and increases the width of the spectral range necessary for extracting the analytical information. The utility of the method is demonstrated by analyzing dialysate samples collected during actual dialysis treatments. In addition, the necessary resolution and spectral quality necessary for reliable on-line urea monitoring is identified. These findings indicate that a dedicated, on-line urea spectrometer must posses a resolution of 16 cm-1 coupled with a sample thickness of 1.5 mm and spectral noise levels on the order of 25 micro-absorbance units when measured as the root-mean-square (RMS) noise of 100% lines.

Insulin is protein-anabolic in chronic renal failure patients

To examine the protein anabolic actions of insulin in chronic renal failure, the authors measured four sets of whole body leucine fluxes during insulin alone and insulin with amino acid infusion in nine uremic patients before hemodialysis (B-HD). Seven were restudied 8 wk after initiation of maintenance hemodialysis (HD). Six normal subjects served as control (N). All values ( micro mol/kg/h, mean +/- SEM) are presented in the sequence of B-HD, HD, and N, and only P < 0.05 are listed. During Flux 1 (baseline), D (leucine release from body protein degradation) were 114 +/- 7, 126 +/- 4, and 116 +/- 6, respectively. C (leucine oxidation rates) were 18 +/- 2, 17 +/- 2, and 21 +/- 3, respectively. S (leucine disappearance into body protein [index of protein synthesis]) were 96 +/- 6, 107 +/- 4, and 94 +/- 4, respectively, and balances (net leucine flux into protein [values were negative during fasting]) were -18 +/- 2, -17 +/- 2, and -21 +/- 3, respectively. During Flux 2 (low-dose insulin infusion), D were 89 +/- 3, 98 +/- 6, and 94 +/- 5, respectively; C were 12 +/- 1, 11 +/- 2, and 18 +/- 1, respectively (P = 0.02); S were 77 +/- 4, 87 +/- 5, and 76 +/- 5, respectively, and balances were -12 +/- 1, -11 +/- 2, and -18 +/- 1, respectively (P = 0.02). During Flux 3 (high-dose insulin infusion): D were 77 +/- 3, 82 +/- 7, and 84 +/- 5, respectively; C were 9 +/- 1, 8 +/- 1, and 14 +/- 1, respectively (P = 0.005); S were 68 +/- 4, 74 +/- 6, and 70 +/- 5, respectively, and balances were -9 +/- 1, -8 +/- 1, and -14 +/- 1, respectively (P = 0.005). In Flux 4 (insulin infused with amino acids): D were 73 +/- 3, 107 +/- 18, and 85 +/- 7, respectively; C were 35 +/- 4, 29 +/- 5, and 39 +/- 3, respectively; S were 105 +/- 5, 145 +/- 15, and 113 +/- 6, respectively (P = 0.02), and balances were 32 +/- 4, 38 +/- 5, and 27 +/- 3, respectively. These data show that B-HD and HD patients were as sensitive as normal subjects to the protein anabolic actions of insulin. Insulin alone reduced proteolysis and leucine oxidation, and insulin given with amino acids increased net protein synthesis.

Are there gender differences in the prescribing of hypnotic medications for insomnia?

Gender differences in the prescribing patterns of general classes of medications for insomnia were examined. The classes of medications included: zopiclone, antidepressants, benzodiazepines, antihistamines and no medication. The sample comprised a sub-set of respondents from 2620 questionnaires of the Canadian Multicentre Sleep Database. Respondents for this database were contacted through physicians, announcements in the media and local pharmacies. The results indicated that gender alone was not associated with differential prescribing for insomnia, nor was gender associated with patterns of medication use such as frequency of taking medication, length of use, taking more or less medication than prescribed or attempts to stop taking medication. Demographic factors were included in the analysis and age and marital status were associated with different prescribing patterns for men and women with insomnia. It is possible that physicians refer to stereotypic expectations when prescribing hypnotics.

The genome sequence of the malaria mosquito Anopheles gambiae

Anopheles gambiae is the principal vector of malaria, a disease that afflicts more than 500 million people and causes more than 1 million deaths each year. Tenfold shotgun sequence coverage was obtained from the PEST strain of A. gambiae and assembled into scaffolds that span 278 million base pairs. A total of 91% of the genome was organized in 303 scaffolds; the largest scaffold was 23.1 million base pairs. There was substantial genetic variation within this strain, and the apparent existence of two haplotypes of approximately equal frequency ("dual haplotypes") in a substantial fraction of the genome likely reflects the outbred nature of the PEST strain. The sequence produced a conservative inference of more than 400,000 single-nucleotide polymorphisms that showed a markedly bimodal density distribution. Analysis of the genome sequence revealed strong evidence for about 14,000 protein-encoding transcripts. Prominent expansions in specific families of proteins likely involved in cell adhesion and immunity were noted. An expressed sequence tag analysis of genes regulated by blood feeding provided insights into the physiological adaptations of a hematophagous insect.

Design of a compartmentalized shotgun assembler for the human genome

Two different strategies for determining the human genome are currently being pursued: one is the "clone-by-clone" approach, employed by the publicly funded project, and the other is the "whole genome shotgun assembler" approach, favored by researchers at Celera Genomics. An interim strategy employed at Celera, called compartmentalized shotgun assembly, makes use of preliminary data produced by both approaches. In this paper we describe the design, implementation and operation of the "compartmentalized shotgun assembler".

Effect of grapefruit juice on pharmacokinetics of microemulsion cyclosporine in African American subjects compared with Caucasian subjects: does ethnic difference matter?

This study aims to determine the effect of grapefruit juice (GJ) on microemulsion cyclosporine (CsA) in 11 African American subjects, and it was compared to those in 11 Caucasian subjects. Each subject received two oral doses of CsA with water (W) or GI as well as i.v. CsA. Regardless of race, GJ significantly increased the peak concentration (Cmax) and area under the time-curve (AUC) of CsA; however, the magnitude of GJ effects was different between African American subjects and Caucasian subjects (p = 0.0003). GJ increased peak concentration of CsA by 39% in African American subjects, while the difference in Caucasian subjects was only 8% (p > 0.05). GJ also increased AUC of CsA in African American subjects by 60%, while GJ increased that in Caucasian subjects by 44% (p = 0.0001). The absolute bioavailability of CsA was 21% lower in African American subjects compared with Caucasian subjects when it was given with water (p = 0.048), but these differences disappeared when it was given with GJ (p = 0.6). These findings suggest that concurrent administration of GJ increases the bioavailability of CsA in African American subjects in greater magnitude compared with Caucasian subjects.

The sequence of the human genome

A 2.91-billion base pair (bp) consensus sequence of the euchromatic portion of the human genome was generated by the whole-genome shotgun sequencing method. The 14.8-billion bp DNA sequence was generated over 9 months from 27,271,853 high-quality sequence reads (5.11-fold coverage of the genome) from both ends of plasmid clones made from the DNA of five individuals. Two assembly strategies-a whole-genome assembly and a regional chromosome assembly-were used, each combining sequence data from Celera and the publicly funded genome effort. The public data were shredded into 550-bp segments to create a 2.9-fold coverage of those genome regions that had been sequenced, without including biases inherent in the cloning and assembly procedure used by the publicly funded group. This brought the effective coverage in the assemblies to eightfold, reducing the number and size of gaps in the final assembly over what would be obtained with 5.11-fold coverage. The two assembly strategies yielded very similar results that largely agree with independent mapping data. The assemblies effectively cover the euchromatic regions of the human chromosomes. More than 90% of the genome is in scaffold assemblies of 100,000 bp or more, and 25% of the genome is in scaffolds of 10 million bp or larger. Analysis of the genome sequence revealed 26,588 protein-encoding transcripts for which there was strong corroborating evidence and an additional approximately 12,000 computationally derived genes with mouse matches or other weak supporting evidence. Although gene-dense clusters are obvious, almost half the genes are dispersed in low G+C sequence separated by large tracts of apparently noncoding sequence. Only 1.1% of the genome is spanned by exons, whereas 24% is in introns, with 75% of the genome being intergenic DNA. Duplications of segmental blocks, ranging in size up to chromosomal lengths, are abundant throughout the genome and reveal a complex evolutionary history. Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems. DNA sequence comparisons between the consensus sequence and publicly funded genome data provided locations of 2.1 million single-nucleotide polymorphisms (SNPs). A random pair of human haploid genomes differed at a rate of 1 bp per 1250 on average, but there was marked heterogeneity in the level of polymorphism across the genome. Less than 1% of all SNPs resulted in variation in proteins, but the task of determining which SNPs have functional consequences remains an open challenge.

Gender-dependent racial difference in disposition of cyclosporine among healthy African American and white volunteers

Pharmacokinetic studies of intravenous and oral cyclosporine (cyclosporin) were performed in 22 healthy African American (n = 11) and white (n = 11) volunteers. Blood cyclosporine concentrations were measured by high performance liquid chromatography. Concentration versus time data were analyzed by noncompartmental models, and statistical analyses were performed by ANOVA. The clearance of intravenous and oral cyclosporine was 4.3 +/- 0.9 mL/min/kg and 13.5 +/- 4.5 mL/min/kg, respectively, in African Americans and 3.7 +/- 0.5 mL/min/kg and 9.6 mL/min/kg, respectively, in the white volunteers (P = .0001). There was a significant race and gender interaction (P = .038). Bioavailability was lower in African Americans (32.8 +/- 6.6%) compared with white volunteers (39.3 +/- 7.1%; P = .049), with a significant race and gender interaction (P = .048). The dose-adjusted area under the curve (AUC) of intravenous and oral cyclosporine was 54.3 +/- 10.6 ng x hr/mL per milligram and 18.1 +/- 4.1 ng x hr/mL per milligram, respectively, in African Americans and 61.9 +/- 6.8 ng x hr/mL per milligram and 24.2 +/- 4.6 ng x hr/mL per milligram, respectively, in white volunteers (P = .023). These findings suggest that disposition of cyclosporine is dependent both on race and on gender.

Resistance to replication of human immunodeficiency virus challenge in SCID-Hu mice engrafted with peripheral blood mononuclear cells of nonprogressors is mediated by CD8(+) T cells and associated with a proliferative response to p24 antigen

High levels of resistance to challenge with human immunodeficiency virus type 1 SF162 were observed in animals engrafted with peripheral blood mononuclear cells of four long-term nonprogressors (LTNPs). Resistance was abrogated by depletion of CD8(+) T cells in vivo and was observed only in LTNPs with proliferative responses to p24. In a subgroup of nonprogressors, CD8(+) T cells mediated restriction of challenge viruses, and this response was associated with strong proliferative responses to p24 antigen.

An analysis of body weight and hemodialysis adequacy based on the urea reduction ratio

The purpose of this study was to evaluate inadequate hemodialysis risk in patients with body weights in the upper quartile of a sample distribution using the urea reduction ratio (URR). Using a case-control design and a simple random sample (n = 315) of hemodialysis (HD) patients, postdialysis weights were divided into quartiles based with a cut-off value at the upper quartile, which was equal to > 81 kilograms (kg). The dichotomous outcome, URR > 65% and URR < 65% constituted the classification for inadequate dialysis risk. The odds ratio (OR) was used to evaluate inadequate dialysis risk based on this outcome. A multivariate logistic regression model was used to adjust for confounding variables and validated for goodness of fit. Those in the > 81 kg group were given more dialysis session time in minutes and used higher efficiency dialyzers as indicated by the coefficient of ultrafiltration (KUf), yet were more likely to have URRs < 65% compared to other patients in the sample (p < 0.001). This finding persisted in the logistic regression model when simultaneously fitting both gender and dialysis session time. Patients weighing > 81 kg experienced an increased risk of inadequate dialysis when compared to all others (OR 4.02, 95% CI [confidence interval] 2.217-7.29). A postdialysis weight > 81 kg increased the risk of inadequate dialysis for patients in this sample. This effect was confounded by a dialysis time x weight interaction term. Also, women were found to have a lower inadequate dialysis risk compared to men after adjusting for weight classification. We, therefore, conclude that patients who weigh > 81 kg may experience inadequate dialysis despite longer, more efficient dialysis sessions. Longer dialysis sessions may benefit some patients, but the effect in larger patients may not be a uniform response.

Effect of grapefruit juice on the pharmacokinetics of microemulsion cyclosporine and its metabolite in healthy volunteers: does the formulation difference matter?

This study was conducted to determine the effect of grapefruit juice on the pharmacokinetics of microemulsion cyclosporine and its major metabolites, M1 and M17, in 12 healthy volunteers. Each subject received two oral doses of microemulsion cyclosporine with water or grapefruit juice. Each subject also received intravenous cyclosporine on a separate occasion. Blood samples were collected for assay of cyclosporine, M1, and M17 during a 24-hour period, and were analyzed by a high-performance liquid chromatography method. Compared with water, administration with grapefruit juice significantly increased peak concentration (Cmax) and area under the concentration-time (AUC) of cyclosporine. Administration with grapefruit juice increased the absolute bioavailability of microemulsion cyclosporine by 45%. For cyclosporine metabolites, administration with grapefruit juice decreased the Cmax and AUC of M1 by 21% and 15%, respectively. These findings suggest that concurrent administration with grapefruit juice increases the bioavailability of microemulsion cyclosporine significantly compared with water in healthy volunteers. The grapefruit juice affects each metabolite formation and its pharmacokinetics differently, which suggests that the major site of its formation is different.

Using the Quetelet body mass index as a mortality indicator for patients starting renal replacement therapy

OBJECTIVE

The purpose of this study was to compare clinical profiles and mortality risk of patients starting renal replacement therapy (RRT) across three Quetelet body mass index (BMI) classifications: lean, normal, and obese.

SAMPLE/SETTING

All patients applying for dialysis services using Health Care Financing Administration (HCFA) from 2728-U4 were sampled during the period of April 1, 1995 through June 30, 1995 in two end-stage renal disease (ESRD) Networks. These two ESRD networks encompassed 7 states and provided 846 patients for this analysis.

DESIGN

A descriptive survival study was used with a follow-up period of 18 months.

METHODS

The Quetelet BMI was calculated based on dividing the predialysis (i.e. before the first dialysis) weight in kilograms by the height in meters squared (kg/m2). Lean, normal, and obese groups were established by quartiles for each gender. A normal BMI consisted of all patients in which the observed BMI was greater than the 25th percentile or less than the 75th percentile.

RESULTS

The lean risk group had more health problems than either the normal or obese group, most notably, a higher prevalence of chronic obstructive pulmonary disease (n = 35, 16.99%) [p = 0.007] and peripheral vascular disease (n = 51, 24.76%) [p = 0.005].

CONCLUSIONS

Death risk was higher in the lean group compared to the normal group after adjusting for age, sex, diabetes, coronary artery disease (CAD), and albumin ratio levels. Based on the simplicity of this technique, recommendations for using the Quetelet BMI as a part of routine patient screening is advocated. Obtaining height and weight are necessary assessment parameters for patients starting dialysis therapy. Using the Quetelet BMI will help nurses to identify those patients who are at nutritional risk.

Depression and short REM latency in subjects with chronic fatigue syndrome

OBJECTIVE

The hypothesized polysomnographic marker for depression, Rapid Eye Movement Latency (REML), was used to investigate two groups of subjects; Chronic Fatigue Syndrome (CFS)-not depressed and CFS-depressed.

METHOD

CFS subjects were classified into depressed and not depressed groups, using the Diagnostic Interview Schedule (DIS), and subsequently were studied in a sleep laboratory to ascertain REML.

RESULTS

Short REML showed a statistically significant correlation with the depressed state in CFS subjects.

CONCLUSION

Short REM latency is associated with depression in the CFS population.

Progression of human immunodeficiency virus disease is associated with increasing disruptions within the CD4+ T cell receptor repertoire

The immunodeficiency caused by human immunodeficiency virus (HIV) infection may be related to loss of diversity in the T cell receptor (TCR) repertoire. A cross-sectional study of the CD4 TCR repertoire was done for patients at various stages of HIV infection. Semiquantitative polymerase chain reaction was used to study the relative usage of the variable chain beta (BV) subfamilies and the size distributions of transcripts (CDR3 size analysis) within these subfamilies. The relative usage of the TCRBV subfamilies of patients and controls was not significantly different. The proportion of subfamilies with abnormal CDR3 size patterns was higher in the HIV-infected patients (25%, 95% confidence interval [CI], 17%-33%) than in the controls (7.2%, 95% CI, 2.3%-12.1%; P < .001), with a significant negative correlation between the number of CD4 cells and the percentage of abnormal TCRBV subfamilies. These results indicate that progressive loss of CD4 T cells is accompanied by increasing disruptions within the T cell receptor repertoire.

HIV infection induces changes in CD4+ T-cell phenotype and depletions within the CD4+ T-cell repertoire that are not immediately restored by antiviral or immune-based therapies

Changes in CD4+ T-cell surface marker phenotype and antigen receptor (TCR) repertoire were examined during the course of HIV infection and following therapy. A preferential decline in naive CD4+ T cells was noted as disease progressed. Following protease inhibitor therapy, naive CD4+ T cells increased only if they were present before initiation of therapy. Disruptions of the CD4+ TCR repertoire were most prevalent in patients with the lowest CD4+ T-cell counts. Antiviral or IL-12 therapy-induced increases in CD4+ T-cell counts led to only minor changes in previously disrupted repertoires. Thus, CD4+ T-cell death mediated by HIV-1 infection may result in a preferential decline in the number of naive CD4+ T cells and disruptions of the CD4+ T-cell repertoire that are not immediately corrected by antiviral or immune-based therapies.

Modeling mortality risk in hemodialysis patients using laboratory values as time-dependent covariates

Proportional hazards analyses assume that the magnitude of mortality risk for a predictor variable remains proportional over time. In a time-dependent model, the explanatory variable violates this assumption, and repeat observations are required to accommodate the change in risk that occurs over time. Using a retrospective cohort design, we tested the following laboratory values for a time-by-covariate interaction: hematocrit (HCT), serum albumin (ALB), and serum creatinine (CR). A random sample of 4,083 hemodialysis patients whose specimens were analyzed in a central laboratory over a 3-year period served as the study group. Using the baseline observation, we discovered significant probability values for the interaction terms TIME*CR (P = 0.013) and TIME*ALB (P < 0.01). The beta coefficient for TIME*HCT was not significant, indicating that the proportional hazard assumption was not violated by this covariate. Based on these results, we fitted a multivariate regression model containing two time-dependent covariates (CR and ALB) using a data structure that incorporated repeat observations of these laboratory values. Patients with high ALB levels experienced the lowest mortality risk. Similarly, serum CR levels were higher in long-term survivors. This analysis verifies the clinical importance of monitoring ALB and CR levels over time and the hazard of using a single laboratory observation to make long-term projections. Additionally, the predictive values of the time-dependent covariates ALB and CR affirm the significance of nutritional approaches directed toward maintaining visceral and somatic protein content throughout renal replacement therapy.

Vascular access thrombosis in new hemodialysis patients

This study identifies factors that are associated with the risk of access thrombosis in 267 new hemodialysis patients. There are few longitudinal studies evaluating the risk of access thrombosis despite the need for long-term use of the access for maintenance hemodialysis. We used a prospective design following patients from 26 providers in Renal Network Council #12 (Iowa, Missouri, Kansas, and Nebraska) for 1 year who were starting hemodialysis. There were significant increases in access thrombosis relative risk (RR) associated with the placement of a polytetrafluoroethylene graft compared with patients with the arteriovenous fistula (RR 1.98; 95% confidence interval [CI] = 1.3, 3,01). The probability of remaining thrombosis free 90 days after first use was 90.1% (95% CI = 82.9, 94.4) for arteriovenous fistula patients, but only 71.6% (95% CI = 63.5, 78.2) for polytetrafluoroethylene graft patients. In arteriovenous fistula patients with more than 30 days maturity time the risk of thrombosis was significantly lower than in those with less maturity time (RR 0.40; 95% CI = 0.14, 0.84); however, there was no significant difference for maturity time among patients with a polytetrafluoroethylene graft. Reduced thrombosis risk also was observed in patients with dialyzer blood flow rates greater than 300 mL/min (RR 0.66; 95% CI = 0.44, 0.99). Total heparin dose and erythropoietin therapy were not associated with the risk of thrombosis. No differences in risk were found for age, renal diagnosis, or type of dialyzer.

Mononuclear cell (MNC) subtypes in osteoarthritis synovial fluid. Comparison with MNC subtypes in rheumatoid arthritis synovial fluid

OBJECTIVE

To examine mononuclear cell (MNC) subtypes in osteoarthritis (OA) synovial fluid (SF) and compare these results with MNC subtypes in SF from patients with rheumatoid arthritis (RA).

METHODS

MNC were obtained from SF by gradient centrifugation with Ficoll-Hypaque. MNC subtypes were identified using color immunofluorescence with monoclonal antibody pairs and flow cytometry.

RESULTS

Significantly lower percentages of CD3+ (p < 0.01) and CD4+ cells (p < 0.01) were found in patients with OA. No differences were noted between CD8+ cells and the CD4/CD8 ratio. Significantly higher percentages of CD14+ (p < 0.001) and CD16+/CD56+ (p < 0.001) were found in patients with OA.

CONCLUSION

Significant differences in MNC subtypes in OA and RA were noted that may reflect differences in pathophysiologic mechanisms operational in each disease.

Excess mortality in small dialysis centers. The result of dialyzing high-risk patients

End Stage Renal Disease Network 12 regularly collects information describing the Medicare dialysis population within its boundaries (Iowa, Nebraska, Missouri, and Kansas). Hoping to foster a regional quality improvement program, Network 12 began calculating provider specific mortality rates in 1988. These rates were extremely variable, but small dialysis units (< or = 30 patients) generally had higher mortality rates than their larger counterparts. To determine why mortality rates were inversely proportional to the number of patients treated within the center, we undertook a more intensive statistical review of patient mortality rate within the network. Actual and expected mortality rates were derived for each Network 12 dialysis center. Forty-eight percent of dialysis centers served 30 or fewer patients (small centers), and 40% had an expected mortality rate < or = 5 deaths per year. In 1989 and 1990, the crude mortality rate for dialysis centers enrolling 30 or fewer patients exceeded that of larger dialysis centers (p = 0.02). When Standardized Mortality Ratios were analyzed, this relationship disappeared (p = 0.83). Statistical review of dialysis providers is a complex process. Adjusting mortality rates for patient characteristics known to influence survival obviated the relation of dialysis unit size to patient mortality rate within Network 12. This suggests that patients were not randomly assigned to dialysis units and that small providers enrolled a disproportionate number of high risk patients. Adjusting mortality rates for endemic patient characteristics did not reduce the extreme variability noted in small mortality rates. This uncertainty, embedded in probability theory, cannot be eliminated from the statistical analysis of small samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Validation of flow cytometry analysis in the objective assessment of spermatogenesis: comparison to the quantitative testicular biopsy

Objective determination of spermatogenesis has been accomplished by quantitative testicular biopsy, which, although laborious, has served as the standard for spermatogenic assessment. Aspiration deoxyribonucleic acid (DNA) flow cytometry of the testis, however, has simplified this determination, and has correlated with indirect hormonal parameters of spermatogenesis and qualitative observations of the seminiferous epithelium. Nevertheless, this important modality has yet to be validated against quantitative micrometry of the testis. To determine this correlation we submitted 29 incisional testicular biopsies for simultaneous quantitative analysis and DNA flow cytometry. Micrometric parameters included the mean tubular wall thickness, and the mean tubular concentration of late spermatids and Sertoli cells. The percentage of haploid, diploid and tetraploid cells was determined for each patient. For the entire patient population a statistically significant correlation was observed between the percentage of haploid cells and the tubular concentration of late spermatids (r = 0.784, p < 0.0005) as well as the mean tubular spermatid-to-Sertoli cell ratio (r = 0.824, p < 0.0005). A similar correlation was noted for various etiological subsets of patients: spinal cord injury (r = 0.809, p < 0.002), genital tract obstruction (r = 0.705, p < 0.02) and miscellaneous diagnoses (r = 0.828, p < 0.02). For the group with testicular failure quantitative micrometry and flow cytometry demonstrated severe impairment in all patients although a statistically significant correlation could not be shown because of the small range of values. DNA flow cytometry analysis correlates strongly with the current standard of quantitative spermatogenic assessment and, therefore, it may be validated as a simplified and highly objective method of determining spermatogenesis.

The value of quantitative testicular biopsy and deoxyribonucleic acid flow cytometry in predicting sperm recovery from electrostimulated ejaculates

Spermatogenic abnormalities have been reported in the majority of men following spinal cord injury, and they contribute to the multifactorial etiology of reproductive dysfunction. Thus far, few have studied the seminiferous epithelium in this group of patients by objective criteria. While quantitative micrometry and flow cytometric analysis are accurate and reproducible methods of quantitating spermatogenesis, the latter is simpler and permits needle aspiration for tissue recovery. The objective of this study is to determine the value of quantitative micrometry and flow cytometric analysis as methods of predicting total sperm yield in electrostimulated ejaculates. Incisional testicular biopsy was performed in 12 anejaculatory men, and the tissue specimens were divided for analysis by quantitative micrometry and flow cytometric analysis. Quantitative micrometry consisted of determining the mean tubular wall thickness, mean tubular concentration of the Sertoli cells and mature spermatids in a minimum of 10 round seminiferous tubules per patient. Specimens were prepared for flow cytometric analysis and the deoxyribonucleic acid histogram was analyzed to determine the percentage of cells in each ploidy compartment. Of the quantitative micrometry parameters analyzed a significant correlation resulted between the total sperm yield per electroejaculate and the mean tubular concentration of late spermatids (p = 0.001) as well as with the mean tubular ratio of late spermatids to Sertoli cells (p = 0.003). The tubular concentration of spermatids resulted in a sensitivity and specificity of 100% and 75%, respectively, to predict adequate sperm yield in semen. Likewise, the mean tubular ratio of spermatids to Sertoli cells resulted in a sensitivity and specificity of 75% and 87.5%, respectively, in its ability to predict normal sperm yield in the recovered ejaculate. Deoxyribonucleic acid flow cytometry analysis showed a normal haploid compartment in all 6 specimens studied, and each was associated with high numbers of sperm in recovered semen. Quantitative histometric parameters correlate significantly with the total sperm yield obtained in electrostimulated ejaculates and may have a role in the selection of candidates for treatment in reproductive rehabilitation programs.

Ten-minute silver stain for Pneumocystis carinii and fungi in tissue sections

A ten-minute methenamine silver staining procedure for the rapid demonstration of Pneumocystis carinii and fungi in tissue sections has been developed. The procedure is optimal for both urgent and routine histologic diagnosis of diffuse, progressive, and life-threatening pulmonary infiltrates, especially in the compromised host, and of fungal lesions in general. Moreover, it is simple and brief, is applicable to both paraffined and frozen sections, and can easily be used by the pathology resident or pathologist if the need arises. It consistently yields results that are far superior to those obtained by Grocott's original methenamine silver method, and as good as or superior to those of modified silver methods and such nonsilver procedures as Giemsa's, Gram-Weigert, and toluidine blue stains.