Preliminary validity testing of the eHealth Literacy Questionnaire (eHLQ): a Confirmatory Factor Analysis (CFA) in Norwegian hospitalized patients

AIMS

To perform the first psychometric analysis of the Norwegian version of the eHLQ using confirmative factor analysis (CFA) procedures in a population of patients admitted to hospital using a cross-sectional design. The eHLQ consists of 35 items capturing the 7-dimensional eHealth Literacy Framework (eHLF) which describes users' attributes, user's interaction with technologies and user's experience with digital health systems.

METHODS

The 7 independent scales of the eHLQ was translated from Danish and culturally adapted into the Norwegian language following a standardised protocol. Assessment of construct validity of the eHLQ was undertaken using data from a cross-sectional survey of 260 patients hospitalized at a Norwegian University Hospital in the Oslo area during a two-week period in June 2021. The analysis included using correlation analysis (Pearsons R), internal consistency (Cronbach's alpha) and confirmatory factor analysis (CFA).

RESULTS

All factor loadings were high to acceptable (i.e. > 0.6), except for five items which had somewhat lower loadings. Regarding internal consistency, alpha ranged from 0.73 to 0.90. For optimal CFA fit for the different scale models, correlated residuals were required for five of the seven scales. Overall our analysis shows an intermediate fit of the orginal construct. Scale intercorrelations were all below 0.8, indicating an overall acceptable discriminant validity between the 7 dimensions.

CONCLUSIONS

The results from the CFA analysis indicate that for almost all 7 eHLQ scales, an acceptable model fit was achieved. The 260 hospitalized patients included in this study represented a variety of diagnoses, recruited from a geographically limited area. Further studies on psychometric properties of the Norwegian version of eHLQ in larger samples, diverse settings and by using more comprehensive approaches are warranted.

Cross-tissue immune cell analysis reveals tissue-specific features in humans

Despite their crucial role in health and disease, our knowledge of immune cells within human tissues remains limited. We surveyed the immune compartment of 16 tissues from 12 adult donors by single-cell RNA sequencing and VDJ sequencing generating a dataset of ~360,000 cells. To systematically resolve immune cell heterogeneity across tissues, we developed CellTypist, a machine learning tool for rapid and precise cell type annotation. Using this approach, combined with detailed curation, we determined the tissue distribution of finely phenotyped immune cell types, revealing hitherto unappreciated tissue-specific features and clonal architecture of T and B cells. Our multitissue approach lays the foundation for identifying highly resolved immune cell types by leveraging a common reference dataset, tissue-integrated expression analysis, and antigen receptor sequencing.

scRNA-seq assessment of the human lung, spleen, and esophagus tissue stability after cold preservation

BACKGROUND

The Human Cell Atlas is a large international collaborative effort to map all cell types of the human body. Single-cell RNA sequencing can generate high-quality data for the delivery of such an atlas. However, delays between fresh sample collection and processing may lead to poor data and difficulties in experimental design.

RESULTS

This study assesses the effect of cold storage on fresh healthy spleen, esophagus, and lung from ≥ 5 donors over 72 h. We collect 240,000 high-quality single-cell transcriptomes with detailed cell type annotations and whole genome sequences of donors, enabling future eQTL studies. Our data provide a valuable resource for the study of these 3 organs and will allow cross-organ comparison of cell types. We see little effect of cold ischemic time on cell yield, total number of reads per cell, and other quality control metrics in any of the tissues within the first 24 h. However, we observe a decrease in the proportions of lung T cells at 72 h, higher percentage of mitochondrial reads, and increased contamination by background ambient RNA reads in the 72-h samples in the spleen, which is cell type specific.

CONCLUSIONS

In conclusion, we present robust protocols for tissue preservation for up to 24 h prior to scRNA-seq analysis. This greatly facilitates the logistics of sample collection for Human Cell Atlas or clinical studies since it increases the time frames for sample processing.

FGF receptor genes and breast cancer susceptibility: results from the Breast Cancer Association Consortium

BACKGROUND

Breast cancer is one of the most common malignancies in women. Genome-wide association studies have identified FGFR2 as a breast cancer susceptibility gene. Common variation in other fibroblast growth factor (FGF) receptors might also modify risk. We tested this hypothesis by studying genotyped single-nucleotide polymorphisms (SNPs) and imputed SNPs in FGFR1, FGFR3, FGFR4 and FGFRL1 in the Breast Cancer Association Consortium.

METHODS

Data were combined from 49 studies, including 53 835 cases and 50 156 controls, of which 89 050 (46 450 cases and 42 600 controls) were of European ancestry, 12 893 (6269 cases and 6624 controls) of Asian and 2048 (1116 cases and 932 controls) of African ancestry. Associations with risk of breast cancer, overall and by disease sub-type, were assessed using unconditional logistic regression.

RESULTS

Little evidence of association with breast cancer risk was observed for SNPs in the FGF receptor genes. The strongest evidence in European women was for rs743682 in FGFR3; the estimated per-allele odds ratio was 1.05 (95% confidence interval=1.02-1.09, P=0.0020), which is substantially lower than that observed for SNPs in FGFR2.

CONCLUSION

Our results suggest that common variants in the other FGF receptors are not associated with risk of breast cancer to the degree observed for FGFR2.

Testicular testosterone: estradiol ratio in domestic cats and its relationship to spermatogenesis and epididymal sperm morphology

The phenomenon of teratozoospermia in felids is not fully understood. In this study, we investigated the testicular androgen:estrogen balance in domestic cats and correlated these data with epididymal sperm morphology and the degree of spermatogenic activity. During spring and summer, testes and blood samples were obtained from 37 mixed-breed domestic cats (12 to 48 mo). The epididymal sperm were harvested and evaluated for sperm counts, motility, and morphology. Distal cytoplasmic droplets were not considered a defect, and samples were considered normozoospermic if they contained more than 60% normal sperm (N = 25) or teratozoospermic if they contained less than 45% normal sperm (N = 12). The testicular and serum concentrations of testosterone (T) and 17β-estradiol (E2) were determined with an enzyme immunoassay. The gonadosomatic index and epididymal sperm numbers and motility did not differ between groups. The percentage of normal sperm was higher in normozoospermic (74.3 ± 2.0, mean ± SEM) than in teratozoospermic samples (43.1 ± 1.4). The most prevalent sperm defects in the teratozoospermic group were abnormal acrosomes (9.7 ± 2.0) and bent midpieces (12.2 ± 2.0) or tails (24.0 ± 2.7) with cytoplasmic droplets. Histomorphometric data were similar between groups, although there was a lower Leydig cell nuclear volume in teratozoospermic samples. Normozoospermic samples contained a higher percentage of haploid cells and had a higher index of total spermatogenic transformation than teratozoospermic samples. Serum concentrations of T (0.5 ± 0.1 vs. 0.8 ± 0.4 ng/mL) and E2 (9.5 ± 1.2 vs. 11.4 ± 2.3 pg/mL) and testicular T concentrations (471.6 ± 65.3 vs. 313.4 ± 57.6 ng/g) were similar between groups. However, compared with normozoospermic samples, teratozoospermic samples had higher testicular E2 concentrations (8.5 ± 3.6 vs. 5.4 ± 0.5 ng/g) and a lower T:E2 ratio (31.8 ± 4.1 vs. 87.2 ± 11.6). There were significant correlations between testicular E2 values and percentages of normal sperm (r = -0.55) as well as those with primary sperm defects (r = 0.58) or abnormal acrosomes (r = 0.64). The T:E2 ratio was also correlated with meiotic index (r = 0.45) and percentage of normal sperm (r = 0.58). In conclusion, a high testicular E2 concentration and a reduced T:E2 ratio were significantly associated with higher ratios of abnormal sperm types, suggesting that the balance between androgens and estrogens is an important endocrine component in the genesis of teratozoospermia in felids.

Mortality risk among hemodialysis patients receiving different vitamin D analogs

Intravenous vitamin D is standard therapy for secondary hyperparathyroidism in hemodialysis (HD) patients. In for-profit dialysis clinics, mortality was higher for patients on calcitriol compared to paricalcitol. Doxercalciferol, a second vitamin D2 analog, is currently available. We assessed mortality associated with each vitamin D analog and with lack of vitamin D therapy in patients who began HD at Dialysis Clinic Inc. (DCI), a not-for-profit dialysis provider. During the 1999-2004 study period we studied 7731 patients (calcitriol: n=3212; paricalcitol: n=2087; doxercalciferol: n=2432). Median follow-up was 37 weeks. Mortality rates (deaths/100 patient-years) were identical in patients on doxercalciferol (15.4, 95% confidence interval (13.6-17.1)) and paricalcitol (15.3 (13.6-16.9)) and higher in patients on calcitriol (19.6 (18.2-21.1)) (P<0.0001). In all models mortality was similar for paricalcitol versus doxercalciferol (hazard ratios=1.0). In unadjusted models, mortality was lower in patients on doxercalciferol (0.80 (0.66, 0.96)) and paricalcitol (0.79 (0.68, 0.92)) versus calcitriol (P<0.05). In adjusted models, this difference was not statistically significant. In all models mortality was higher for patients who did not receive vitamin D versus those who did (1.2 (1.1-1.3)). Mortality in doxercalciferol- and paricalcitol-treated patients was virtually identical. Differences in survival between vitamin D2 and D3 may be smaller than previously reported.

Comorbidity assessment using the Index of Coexistent Diseases in a multicenter clinical trial

BACKGROUND

The Hemodialysis (HEMO) Study is a multicenter trial designed to determine whether hemodialysis dose and membrane flux affect survival. Comorbid conditions are also important determinants of survival, and thus, an accurate and reliable method to assess comorbidity was required. Comorbidity was being assessed at baseline and annually in the HEMO Study using the Index of Coexistent Disease (ICED). We describe the instrument, its implementation in the HEMO Study, and the results of comorbidity assessment in the first 1000 randomized patients in the trial.

METHODS

The ICED aggregated the presence and severity of 19 medical conditions and 11 physical impairments within two scales: the Index of Disease Severity (IDS) and the Index of Physical Impairment (IPI). The final ICED score was determined by an algorithm combining the peak scores for the IDS and IPI. The range of the ICED was from 0 to 3, reflecting increasing severity.

RESULTS

Study personnel at 15 clinical centers were trained to update and abstract data from the dialysis medical records. Availability of data, measures of construct validity, and measures of reliability were adequate; 99.8% and 60.6% of patients had comorbid conditions in at least one IDS or IPI category, respectively. The distribution of patients by ICED level was 0 (0.2%), 1 (34.9%), 2 (31.2%), and 3 (33.7%). In multivariable analysis, the following factors were significantly associated with more severe comorbidity: older age, diabetes and other causes of renal disease, a lower level of education, employment status (unemployed and retired), longer duration of dialysis, and lower serum creatinine. There was a significant variation in the severity of comorbidity among clinical centers after adjustment for other factors. The R2 of the model was 25.3%, indicating that a substantial proportion of the variation in the ICED was not explained by these factors.

CONCLUSIONS

We conclude that comorbidity assessment using the ICED is feasible in multicenter clinical trials of dialysis patients. There is a large burden of comorbidity in dialysis patients, which is not well explained by the cause of renal disease, demographic, and socioeconomic factors and common clinical and laboratory measurements. These variables should not be considered substitutes for comorbid conditions in case-mix adjustment. Comorbidity assessment is useful to describe the sample population, to improve the precision of the treatment effect, and to use possibly as an outcome measurement.

Developing a health-related quality-of-life measure for end-stage renal disease: The CHOICE Health Experience Questionnaire

The Choices for Healthy Outcomes in Caring for End-Stage Renal Disease ([ESRD] CHOICE) Study was designed to evaluate the effectiveness of alternative dialysis prescriptions. As part of CHOICE, we developed an instrument for measuring health-related quality of life (HRQOL) for patients with ESRD that would complement the Medical Outcomes Study 36-Item Short-Form Survey (SF-36) and be sensitive to differences in dialysis modality (hemodialysis [HD] and peritoneal dialysis [PD]) and dialysis dose. The selection of HRQOL domains to be included was based on: (1) a structured literature review of 47 articles describing 53 different instruments; (2) content analysis of five focus groups with HD and PD patients, nephrologists, and other providers; (3) a survey of 110 dialysis providers about features of different modalities that affect patient HRQOL; and (4) a semistructured survey of 25 patients with ESRD on the effects of dialysis on functioning and HRQOL. To help prioritize domains and items identified by these methods, a representative sample of 136 dialysis patients rated each item for frequency and bother. A panel of nephrologists provided advice about the salience of items to modality or dose. Items and scales were selected with a preference for existing measures tested in patients with ESRD and were tested for reliability and validity. The first four steps yielded 22 HRQOL domains that included 96 items: 8 generic domains in the SF-36 (health perceptions, physical, social, physical and emotional role function, pain, mental health, and energy); 8 additional generic domains (cognitive functioning, sexual functioning, sleep, work, recreation, travel, finances, and general quality of life); and 6 ESRD-specific domains (diet, freedom, time, body image, dialysis access [catheters and/or vascular], and symptoms). New items were developed or adapted to assess ESRD-specific domains. Scales for these items showed adequate internal consistency (Cronbach's alpha > 0.70, except for time [alpha = 0.57] and quality of life [alpha = 0.68]), as well as convergent and discriminant construct validity in a sample of 928 patients. The final questionnaire included 21 domains (time was deleted) and 83 items. We have designed a patient-centered instrument, the CHOICE Health Experience Questionnaire, that addresses domains that may be sensitive to differences in dialysis modality and dose and shows evidence for reliability and validity as a measure of HRQOL in ESRD.

Comorbidity assessment in hemodialysis and peritoneal dialysis using the index of coexistent disease

The purpose of this paper is to describe the ICED, summarize outcomes of prior studies in which it was used, and describe the adaptations that have lead to the present instrument. We will then demonstrate its use in quantifying the burden of comorbid conditions in a sample of hemodialysis and peritoneal dialysis patients from our center, and show the relationship between ICED levels and outcomes in peritoneal dialysis patients.

Formal literature review of quality-of-life instruments used in end-stage renal disease

Although quality-of-life assessment is an important complement to conventional clinical evaluation, there are limited opportunities for researchers in end-stage renal disease (ESRD) to examine evidence for a range of quality-of-life measures. To better understand how quality of life has been conceptualized, measured, and evaluated for ESRD, we conducted a structured literature review. Eligible articles were identified from a MEDLINE search, expert input, and review of references from eligible articles. A standardized instrument was created for article review and included type of measure, instrument development process, study sample characteristics, quality-of-life domains, and reliability and validity testing. From 436 citations, 78 articles were eligible for final review, and of those, 47 articles contained evidence of reliability or validity testing. Within this set, there were 113 uses of 53 different instruments: 82% were generic and 18% were disease specific. Only 32% defined quality of life. The most frequently assessed domains were depression (41%), social functioning (32%), positive affect (30%), and role functioning (27%). Testing was completed for test-retest reliability (20%), interrater reliability (13%), internal consistency (22%), content validity (24%), construct validity (41%), criterion validity (55%), and responsiveness (59%). Few articles measuring quality of life in ESRD defined quality-of-life domains or adequately described instrument development and testing. Generic measures, such as the Sickness Impact Profile, and disease-specific measures, such as the Kidney Disease Questionnaire, had been tested more thoroughly than others. Standardized reporting and more rigorous testing could help researchers make informed choices about instruments that would best serve their own and their patients' needs.

Post-transcriptional regulation of E2A proteins via lipopolysaccharide and CD40 signaling

The transcription factor E2A plays a crucial role in B cell development, the control of immunoglobulin gene rearrangement and expression. Here we report that in primary mouse B cells lipopolysaccharide (LPS) is able to induce the level of E2A protein by over 50-fold in days of culture. In contrast, CD40 signaling is insufficient to cause an E2A increase and can in fact prevent the LPS-mediated induction of E2A. These results suggest that E2A induction requires both proliferation and differentiation. We find that E2A protein induction is regulated post-transcriptionally since E2A mRNA is not induced by LPS. We have thus identified an important additional layer of regulation affecting the activity of E2A transcription factors.

Use of focus groups to identify concerns about dialysis. Choice Study

BACKGROUND

Patients with end-stage renal disease (ESRD) may have quality-of-life (QOL) concerns that are not fully appreciated by their providers. The authors conducted focus groups with dialysis patients and dialysis professionals to determine whether this qualitative method would reveal differences between patients' and providers' views about: 1) domains of QOL that are affected by ESRD and dialysis; and 2) aspects of dialysis that affect QOL.

METHODS

Separate focus group discussions were held with: 8 adult hemodialysis patients (mean age 50 years; 3 women; mean duration of dialysis 8.5 years), 5 adult peritoneal dialysis patients (mean age 54 years; 3 women; mean duration of dialysis 4.6 years), 8 nephrologists (mean of 12 years of dialysis practice), and 9 other health professionals involved in dialysis care (3 nurses, 2 dietitians, 2 social workers, and 2 technicians; mean of 10 years experience in dialysis care). Discussions were audiotaped, transcribed verbatim, and reviewed independently by three investigators to identify and categorize distinct thoughts.

RESULTS

1,271 distinct thoughts were identified and grouped into 20 related categories, which included ten QOL domains and ten aspects of dialysis that affect QOL. Compared with the professionals, the patients identified one additional relevant QOL domain (10 vs 9), and one additional aspect of dialysis that affects QOL (10 vs 9), and expressed more thoughts per domain (p < 0.05), although the contents of their comments were frequently similar. Among QOL domains, the numbers of related thoughts identified by patients and professionals, respectively, were: freedom/control (60, 89); social relationships (36, 11); anxiety (37, 4); role function (24, 10); energy (12, 10); body image (16, 4); sex (11, 21); mental attitude (21, 0); sleep (15, 1), and cognitive function (13, 7). Among aspects of dialysis that affect QOL, the numbers of thoughts identified by patients and professionals were: general dialysis issues (159, 105); relationships with staff (62, 110); patient education (63, 68); diet (44, 40); scheduling (57, 3); vascular or peritoneal access issues (31, 17), adaptation to dialysis (16, 14); dialysis dose (18, 8); symptoms (25, 0), and self-care (5, 24).

CONCLUSIONS

Although health professionals have a good understanding of patient concerns about the effects of ESRD and dialysis, the focus group discussions revealed a breadth and depth of QOL concerns that they may not fully appreciate.

Prevalence, predictors, and consequences of late nephrology referral at a tertiary care center

Despite improvements in dialysis care, mortality of patients with end-stage renal disease (ESRD) remains high. One factor that has thus far received little attention, but might contribute to morbidity and mortality, is the timing of referral to the nephrologist. This study examines the hypothesis that late referral of patients to the nephrologist might lead to suboptimal pre-ESRD care. Clinical and laboratory data were obtained from the patient records and electronic databases of New England Medical Center, its affiliated dialysis unit (Dialysis Clinics, Inc., Boston), and the office records of the outpatient nephrology clinic. Early (ER) and late (LR) referral were defined by the time of first nephrology encounter greater than or less than 4 mo, respectively, before initiation of dialysis. Multivariate models were built to explore factors associated with LR, and whether LR is associated with hypoalbuminemia or late initiation of dialysis. Of the 135 patients, 30 (22%) were referred late. There were no differences in age, gender, race, and cause of ESRD between ER and LR patients. However, there were significant differences in insurance coverage between these two groups. In the multivariate analysis, patients covered by health maintenance organizations were more likely to be referred late (odds ratio = 4.5) than patients covered by Medicare. Compared to ER, LR patients were more likely to have hypoalbuminemia (56% versus 80%), hematocrit <28% (33% versus 55%), and predicted GFR <5 ml/min per 1.73 m2 (17% versus 40%) at the start of dialysis, and less likely to have received erythropoietin (40% versus 17%) or have a functioning permanent vascular access for the first hemodialysis (40% versus 4%). It is concluded that late referral to the nephrologist is common in the United States and is associated with poor pre-ESRD care. Pre-ESRD care of patients treated by nephrologists was also less than ideal. The patient-, physician-, and system-related factors behind this observation are unclear. Meanwhile, pre-ESRD educational efforts need to target patients, generalists, and nephrologists.

Induction of the Igkappa 3' enhancer by distinct pathways can be inhibited by cross-linking of the CD40 receptor

Upon treatment with lipopolysaccharide (LPS), primary B cells proliferate and differentiate into plasma cells with concomitant up-regulation of immunoglobulin (Ig) gene expression. Here we examine the role of the Igkappa 3' enhancer in this process using a kappa3'-enhancer-driven beta-globin reporter gene in transgenic mice. We find that LPS treatment up-regulates kappa3' enhancer activity as a function of differentiation rather than proliferation, since proliferation only (induced by cross-linking of CD40) is insufficient to activate the element, whilst differentiation with only limited proliferation (LPS + transforming growth factor-beta) does allow activation to occur. The Igkappa 3' enhancer is also induced by cross-linking of surface Ig and this signal can synergize with LPS activation, suggesting that distinct activation pathways are used. Nevertheless, both of these pathways can be inhibited by co-cross-linking of CD40. Thus Ig enhancers in the heavy and light chain loci are differentially regulated in response to CD40.

"U" curve association of blood pressure and mortality in hemodialysis patients. Medical Directors of Dialysis Clinic, Inc

BACKGROUND

Hypertension may play an important role in the pathogenesis of the excess cardiovascular and cerebrovascular (CV) morbidity observed in hemodialysis patients (HD). However, the optimal blood pressure (BP) range for HD patients has not been defined. We postulated that there is a "U" curve relationship between BP and CV mortality. To explore this hypothesis we studied 5,433 HD patients in Dialysis Clinic Inc., a large not-for-profit chain, over a five year period.

METHODS

Cox regression, with fixed and time-varying covariates, was used to assess the effect of systolic blood pressure (SBP) and diastolic blood pressure (DBP), pre- and post-dialysis, on CV mortality, while adjusting for age, gender, ethnicity, primary cause of end-stage renal disease, Kt/V, serum albumin, and antihypertensive medications.

RESULTS

The overall impact of BP on CV mortality was modest. Pre-dialysis, neither systolic nor diastolic hypertension were associated with an increase in CV mortality. Post-dialysis, SBP > or = 180 mm Hg (RR = 1.96, P < 0.015) and DBP > or = 90 mm Hg (RR = 1.73, P < 0.05) were associated with increased CV mortality. Low SBP (SBP < 110 mm Hg) was associated with increased CV mortality, pre- and post-dialysis.

CONCLUSIONS

The results suggest the presence of a "U" curve relationship between SBP post-dialysis and CV mortality in HD patients.

PMA/ionomycin induces Ig kappa 3' enhancer activity which is in part mediated by a unique NFAT transcription complex

The Ig kappa 3' enhancer is required for high levels of Ig kappa gene expression. We now show that kappa 3' enhancer function increases five- to eightfold after stimulation of primary murine B cells with phorbol 12-myristate 13-acetate (PMA) and the calcium ionophore ionomycin. In the presence of cyclosporin A this induction is almost halved, suggesting that transcription factors of the NFAT family contribute to kappa 3' enhancer induction. Indeed, we identify a novel NFAT binding site which is required for full enhancer function. We find that this site is transcriptionally active in stimulated B cells, T cells and fibroblasts and that both PMA and ionomycin are required for maximal induction. Time course analysis of the components of the protein-DNA complex in primary lymphocytes reveals that both NFATp and NFATc are present in the complex after 15 min, while only NFATc is detectable after 4 h. This suggests that NFATc plays the dominant role in controlling long-term responses of this transcription factor family. Furthermore, JunB, JunD, FosB and cFos form part of the DNA-protein complex in Bal-17 B cells. Complex formation as well as transcriptional activity can also be induced by crosslinking of surface Ig. We have, thus, identified a unique NFAT complex in B cells that contributes to Ig kappa gene expression.

Effect of formaldehyde/bleach reprocessing on in vivo performances of high-efficiency cellulose and high-flux polysulfone dialyzers

Among the several disadvantages of reprocessed dialyzers is the concern that reuse could decrease the clearance of uremic toxins, leading to a decrease in the delivered dose of dialysis. To examine this possibility in the clinical setting, the clearances of small molecular weight solutes (urea and creatinine) and middle molecular weight substances (beta 2 microglobulin) were compared during dialysis with "high-efficiency" cellulose (T220L) and "high-flux" polysulfone (F80B) dialyzers reprocessed with formaldehyde and bleach. In a crossover study, six chronic hemodialysis patients were alternately assigned to undergo 21 dialysis treatments with a single T220L dialyzer or F80B dialyzer. Each patient was studied during first use (0 reuse), 2nd reuse (3rd use), and 5th, 10th, 15th, and 20th reuse of each dialyzer. Urea, creatinine, and beta 2 microglobulin clearances were measured at blood flow rates of 300 ml/min (Qb 300) and 400 ml/min (Qb 400). Total albumin loss into the dialysate was measured during each treatment. Urea or creatinine clearance of new T220L dialyzers was not significantly different from that of new F80B dialyzers at either Qb. Urea clearance of F80B dialyzers at Qb 300 decreased from 241 +/- 2 ml/min for new dialyzers to 221 +/- 5 ml/min after 20 reuses (P < 0.001), and Qb 400 from 280 +/- 4 ml/min for new dialyzers to 253 +/- 7 ml/min after 20 reuses (P = 0.001). Similarly, with reuse, creatinine clearance of F80B dialyzers also decreased at Qb 300 (P = 0.07) and Qb 400 (P = 0.03). In contrast, urea or creatinine clearance of T220L dialyzers did not decrease with reuse at either Qb. Urea clearance of T220L dialyzers was significantly higher than that of F80B at Qb 300 at the 5th, 10th, 15th, and 20th reuse (P < 0.001, = 0.005, = 0.004, and = 0.006, respectively), and Qb 400 at the 2nd, 5th, 10th, 15th, and 20th reuse (P = 0.04, 0.008, 0.03, 0.02, and 0.008, respectively). Beta 2 microglobulin clearance of T220L dialyzers was < 5.0 ml/min across the reuses studied. Beta 2 microglobulin clearance of F80B was < 5.0 ml/min for new dialyzers, but increased to 21.2 +/- 5.3 ml/min (Qb 300) and 23.6 +/- 3.3 ml/min (Qb 400) after 20 reuses (P < 0.001). Throughout the study, albumin was undetectable in the dialysate with T220L dialyzers. With F80B dialyzers, albumin was detected in the dialysate in four instances (total loss during dialysis, 483 mg to 1.467 g). In summary, the results of this study emphasize the greater need for information on dialyzer clearances during clinical dialysis, especially with reprocessed dialyzers. A more accurate knowledge of dialyzer performance in vivo would help to ensure that the dose of dialysis prescribed is indeed delivered to the patients.

Effects of complement depletion on the pharmacokinetics and gene delivery mediated by cationic lipid-DNA complexes

We show that lipoplexes activate complement in human serum in vitro and deplete complement when administered intravenously (i.v.) to mice. This raised the possibility that complement proteins might alter gene expression mediated by lipoplex in animals. To investigate this phenomenon, complement levels were depleted to less than 5% in ICR mice by intraperitoneal (i.p.) injection of cobra venom factor and anti-C3 antibodies. The pharmacokinetics and distribution of radio labeled DOTAP-cholesterol (1.0:0.9 molar ratio)-DNA (5:1 positive charge ratio) complexes containing 131I-labeled p-hydroxybenzamidine phosphatidylethanolamine and 125I-labeled DNA were measured in mice after i.v. administration. Greater than 75% of the injected lipoplex appeared in the lungs 5 min following injection. The lipid and DNA were eliminated from the lungs at a constant ratio. Distribution in various organs was not affected by complement depletion. Expression of luciferase was highest in the lungs and showed a dose-dependent increase as the amount of DNA injected increased from 3 to 60 microg. Reporter gene expression was not affected by complement depletion. In addition, complement depletion had no effect on either the distribution or gene expression in the heart, spleen, or liver. We conclude that cationic lipid-DNA complexes interact with serum complement proteins upon i.v. injection in mice, but this interaction does not influence the lipofection efficiency or systemic distribution of the lipoplex.

Methodological limitations of the ESRD Core Indicators Project: an ESRD network's experience with implementing an ESRD quality survey. Medical Review Board of the ESRD Network of New England

ESRD Network Number 1, composed of Maine, New Hampshire, Vermont, Massachusetts, Connecticut, and Rhode Island, developed a Network Core Indicator Pilot Project using the dialysis units represented on the Medical Review Board. Network 1's Core Indicator Pilot Project aimed to (1) estimate the proportion of end-stage renal disease (ESRD) patients in Network 1 receiving hemodialysis treatments associated with a urea reduction ratio less than 60% to 65%, (2) elucidate the patient characteristics associated with a hemodialysis dose less than 65%, (3) define the processes in the delivery of hemodialysis that limit the provision of an adequate dialysis dose, and (4) initiate the routine collection of measures of dialysis dose, the analysis of those data, and feedback to the participating dialysis units. In the course of the Core Indicator Pilot Project, we observed little uniformity in the sampling method for the postdialysis blood urea nitrogen sample. Thirty-three percent of the hemodialysis units reported that this critical blood sample was drawn immediately before the dialysis treatment was terminated; 25% were obtained immediately at the end of the dialysis treatment and 42% drew the sample > or = 5 minutes after all blood was reinfused to the patient. Especially in the presence of unappreciated blood recirculation in the angioaccess or postdialysis urea rebound, the lack of standardization in obtaining this critical blood sample to support the urea reduction ratio calculation greatly compromises any comparisons of performance across dialysis facilities and may jeopardize patient care. Future ESRD quality improvement efforts must focus not only on the results of the outcome measure but also on the process by which the measure is achieved. These fundamental principles of quality assessment should be considered by policy specialists, payers, providers, and developers of clinical practice guidelines.

Benzene poisoning, a risk factor for hematological malignancy, is associated with the NQO1 609C-->T mutation and rapid fractional excretion of chlorzoxazone

Benzene is a ubiquitous occupational hematotoxin and leukemogen, but people vary in their response to this toxic agent. To evaluate the impact of interindividual variation in enzymes that activate (i.e., CYP2E1) and detoxify (i.e., NQO1) benzene and its metabolites, we carried out a case-control study in Shanghai, China, of occupational benzene poisoning (BP; i.e., hematotoxicity), which we show is itself strongly associated with subsequent development of acute nonlymphocytic leukemia and the related myelodysplastic syndromes (relative risk, 70.6; 95% confidence interval, 11.4-439.3). CYP2E1 and NQO1 genotypes were determined by PCR-RFLP, and CYP2E1 enzymatic activity was estimated by the fractional excretion of chlorzoxazone (fe(6-OH)) for 50 cases of BP and 50 controls. Subjects with both a rapid fe(6-OH). and two copies of the NQO1 609C-->T mutation had a 7.6-fold (95% confidence interval, 1.8-31.2) increased risk of BP compared to subjects with a slow fe(6-OH) who carried one or two wild-type NQO1 alleles. In contrast, the CYP2E1 PstI/RsaI polymorphism did not influence BP risk. This is the first report that provides evidence of human susceptibility to benzene-related disease. Further evaluation of susceptibility for hematotoxicity and hematological malignancy among workers with a history of occupational exposure to benzene is warranted.

An epidemiologic study of early biologic effects of benzene in Chinese workers

Benzene is a recognized hematotoxin and leukemogen, but its mechanisms of action in humans are still uncertain. To provide insight into these processes, we carried out a cross-sectional study of 44 healthy workers currently exposed to benzene (median 8-hr time-weighted average; 31 ppm), and unexposed controls in Shanghai, China. Here we provide an overview of the study results on peripheral blood cells levels and somatic cell mutation frequency measured by the glycophorin A (GPA) gene loss assay and report on peripheral cytokine levels. All peripheral blood cells levels (i.e., total white blood cells, absolute lymphocyte count, platelets, red blood cells, and hemoglobin) were decreased among exposed workers compared to controls, with the exception of the red blood cell mean corpuscular volume, which was higher among exposed subjects. In contrast, peripheral cytokine levels (interleukin-3, interleukin-6, erythropoietin, granulocyte colony-stimulating factor, tissue necrosis factor-alpha) in a subset of the most highly exposed workers (n = 11) were similar to values in controls (n = 11), suggesting that benzene does not affect these growth factor levels in peripheral blood. The GPA assay measures stem cell or precursor erythroid cell mutations expressed in peripheral red blood cells of MN heterozygous subjects, identifying NN variants, which result from loss of the GPA M allele and duplication of the N allele, and N phi variants, which arise from gene inactivation. The NN (but not N phi) GPA variant cell frequency was elevated in the exposed workers compared with controls (mean +/- SD, 13.9 +/- 8.4 mutants per million cells versus 7.4 +/- 5.2 per million cells, (respectively; p = 0.0002), suggesting that benzene produces gene-duplicating but not gene-inactivating mutations at the GPA locus in bone marrow cells of exposed humans. These findings, combined with ongoing analyses of benzene macromolecular adducts and chromosomal aberrations, will provide an opportunity to comprehensively evaluate a wide range of early biologic effects associated with benzene exposure in humans.

The Ig kappa 3'-enhancer triggers gene expression in early B lymphocytes but its activity is enhanced on B cell activation

Ig kappa gene expression is controlled by two enhancers, one located within the major intron (Ei) and the other located downstream of C kappa (E3'). Whereas loss of E3' has previously been shown to diminish kappa expression, we show here that a rearranged kappa transgene lacking Ei is well expressed, even at the pre-B cell stage. This suggests that E3' alone might be sufficient to give properly regulated transcription throughout B cell development. Indeed, we show that a transgene composed of a beta-globin reporter linked to E3' is expressed in a B cell-specific manner, becoming activated at the late pro-B to pre-B cell stage but with dramatically enhanced activity on B cell activation. Thus, E3' becomes active as a transcription enhancer at the stage when V kappa-J kappa rearrangement is being initiated and is sufficient to yield an expression pattern in a linked reporter gene similar to that of fully rearranged kappa genes.

Transmembrane passage of cytokine-inducing bacterial products across new and reprocessed polysulfone dialyzers

The widespread use of bicarbonate dialysate and reprocessed high-efficiency and "high-flux" dialyzers has raised concerns about the increased risk of reverse-transfer of dialysate contaminants into the blood compartment. To evaluate this concern, the reverse-transfer of bacterial products from contaminated bicarbonate dialysate into the blood compartment was compared during in vitro dialysis with new or reprocessed high-flux polysulfone dialyzers. In vitro dialysis was carried out at 37 degrees C by use of a counter-current recirculating loop dialysis circuit with either new high-flux polysulfone dialyzers or dialyzers reprocessed once or 20 times with formaldehyde (0.75%) and bleach (< 1%) with an automated system. Heparinized whole blood from healthy volunteers was circulated through the blood compartment, and bicarbonate dialysate was circulated in the dialysate compartment. The dialysate was challenged sequentially by 1:1000 and 1:100 dilutions of a sterile Pseudomonas aeruginosa culture supernatant (bacterial challenge). Samples were drawn from the blood and dialysate compartments 1 h after each challenge. Peripheral blood mononuclear cells (PBMC) were harvested by Ficoll-Hypaque separation from whole blood in the blood compartment and a 5 x 10(6) PBMC/mL cell suspension was prepared. Likewise, dialysate samples (0.5 mL) were added to 0.5 mL suspension of 5 x 10(6) PBMC/mL drawn at baseline. All PBMC suspensions were incubated upright in a humidified atmosphere at 37 degrees C with 5% CO2 for 24 h, and total interleukin-1 alpha (IL-1 alpha) and tumor necrosis factor-alpha (TNF alpha) cytokine production (cell-associated and secreted) was measured by radioimmunoassay. Eight experiments were performed for each arm of the study with the same donor for each arm. One hour after contaminating the dialysate with a 1:1000 dilution of the bacterial challenge, IL-1 alpha production by PBMC harvested from the blood compartment was 160 +/- 0, 171 +/- 11, and 270 +/- 35 pg, respectively, for new dialyzers, dialyzers reprocessed once, and dialyzers reprocessed 20 times (P = 0.004). One hour after challenging the dialysate with 1:100 dilution, IL-1 alpha production by PBMC harvested from the blood compartment was 188 +/- 20, 228 +/- 35, and 427 +/- 67 pg, respectively, for new dialyzers, dialyzers reprocessed once, and dialyzers reprocessed 20 times (P = 0.006). IL-1 alpha production by PBMC from dialyzers reprocessed 20 times was significantly greater than both new and dialyzers reprocessed once. However, there were no significant differences between new dialyzers and dialyzers reprocessed once. Similarly, after the 1:1000 challenge, TNF alpha production by PBMC harvested from the blood compartment was 160 +/- 0, 160 +/- 0, and 213 +/- 22 pg, respectively, for new dialyzers, dialyzers reprocessed once, and dialyzers reprocessed 20 times (P = 0.008). After the 1:100 challenge, TNF alpha production was 168 +/- 8, 188 +/- 20, and 225 +/- 32 pg, respectively, for new dialyzers, dialyzers reprocessed once, and dialyzers reprocessed 20 times (P = 0.20). These results demonstrate that reprocessing of high-flux polysulfone dialyzers with bleach increases the risk of reverse-transfer of bacterial products from contaminated dialysate, and this risk appears to increase with the number of reuses. Consequently, units that reprocess membranes with bleach and have suboptimal water quality might subject their patients to a higher risk of cytokine-related morbidity.

Correlation of pediatric echocardiographic Doppler and catheter-derived valvar aortic stenosis gradients and the influence of aortic regurgitation

This report suggests that in the absence of aortic regurgitation, Doppler peak and mean gradients are useful predictors of catheter peak-to-peak aortic stenosis gradients >50 mm Hg; however, in the presence of aortic regurgitation, the predictive value diminishes dramatically, but improves when electrographic data are incorporated. We present potentially useful equations to help predict the need for interventional catheterization for valvar aortic stenosis.

Characterization of plasmid DNA transfer into mouse skeletal muscle: evaluation of uptake mechanism, expression and secretion of gene products into blood

The expression of naked plasmid DNA coding for firefly luciferase (pRSVluc) or a secreted protein, human-alpha-1-antitrypsin (pRcCMVhAAT) in mouse skeletal muscle was characterized following administration by an improved intramuscular injection technique. Injection guided by intense illumination along the longitudinal axis of the mouse quadriceps muscle and parallel to the myofibers yielded 200-fold higher levels of luciferase expression than perpendicular injection. Luciferase expression was inhibited by an excess of non-coding DNA or dextran sulfate suggesting that muscle DNA uptake mechanism(s) can be saturated. Injected plasmid DNA was rapidly eliminated from the muscle as evidenced by tissue distribution studies of radiolabeled hAAT plasmid and Southern analysis. However, PCR analysis demonstrated that hAAT cDNA persisted in the muscle for at least 1 month after injection. Immunohistochemistry techniques indicated that the hAAT gene was expressed by the muscle fibers. ELISA analysis of serum samples collected from intramuscularly injected mice demonstrated that secreted hAAT protein concentration peaked in serum by day 7, started to decline by day 14 and was barely detectable 21 days post-injection. RT-PCR analysis demonstrated that hAAT transcript persisted at the site of injection for at least 1 month indicating that the decline of serum hAAT concentration 21 days post-injection was not due to the absence of hAAT transcript. However, the decline of hAAT protein concentration in the serum was inversely correlated with accumulation of murine anti-hAAT antibodies in circulation.

Intratracheal gene delivery to the mouse airway: characterization of plasmid DNA expression and pharmacokinetics

Intratracheal administration of plasmid DNA resulted in gene expression in mouse airways in the absence of any enhancing agent. Administration of plasmid DNA encoding the chloramphenicol acetyltransferase gene (CAT) in sterile water lead to CAT transgene expression that peaked between 1 and 3 days and was detected up to 28 days after DNA administration. Transgene expression was independent of mouse gender, age and strain. Levels of expression from DNA in various isotonic solutions did not differ from levels obtained with DNA administered in water, suggesting that transfection is not dependent on damage to airway cells caused by a hypo-osmotic delivery vehicle. Pharmacokinetic studies using radiolabeled plasmid DNA showed that DNA was rapidly degraded, while higher levels of radioactivity were retained for longer duration following administration of cationic liposome-DNA complexes in the airway. Southern blot and PCR analysis confirmed that DNA complexed with DOTMA-DOPE was retained in the airways for a longer period. However, cationic liposomes DOTMA-DOPE (1:1) or DOTAP complexed with DNA, did not enhance expression over DNA alone. These results suggest that 'naked' plasmid DNA should be included as a control in all studies on intratracheal gene delivery using nonviral systems.

Screening for acquired cystic kidney disease: a decision analytic perspective

Acquired cystic kidney disease (ACKD) increases the risk of renal malignancy, and many authors suggest routine screening of dialysis patients for ACKD and renal tumors. However, they have defined neither the target population, the optimal screening strategy, the magnitude of its benefit, nor its risk. We used decision analysis to evaluate strategies of performing either computed tomography (CT) or ultrasound every three years on all dialysis patients and annually on patients found to have cysts. We compared these strategies to a strategy of seeking cysts and cancer only if these are clinically suspected. The baseline analysis shows that both CT and ultrasound may decrease cancer deaths by half for patients with a life expectancy of 25 years. Screening for ACKD offers these patients as much as a 1.6 year gain in life expectancy. However, for the majority of patients beginning renal replacement therapy, age or comorbid disease substantially limits life expectancy. For such patients, the gain in life expectancy from an ACKD screening program is measured in days. Sensitivity analyses show that the benefit of screening depends on the rate of malignant transformation, which needs better definition. The gain in life expectancy does not appear to be large enough to justify an ACKD screening program for the entire ESRD population. However, for the youngest and healthiest patients, a screening program would be of benefit. The magnitude of this benefit is uncertain, because the analysis was consistently biased in favor of the screening strategies.

Repression of the immunoglobulin heavy chain 3' enhancer by helix-loop-helix protein Id3 via a functionally important E47/E12 binding site: implications for developmental control of enhancer function

The activity of the immunoglobulin 3' enhancer is restricted to the late stages of B lymphoid development. Here we further examine the molecular basis for the temporally restricted activity of the B-lymphoid IgH 3' enhancer. We demonstrate that a binding site (E5 site) for the E47 and/or E12 proteins is functionally important for enhancer activity. The multimerized E5 site acts as a B cell-specific enhancer and, when assayed in COS cells, can be transactivated by E47/E12 proteins. This transactivation in COS cells, as well as the activity of the full length 3' enhancer in plasma cells, can be repressed by overexpression of the dominant negative nuclear regulator Id3. When examining the tissue distribution of Id3 in murine cell lines, we find that Id3 is expressed throughout the pre-B and B cell stages, but is down-regulated at the plasma cell stage. Thus, Id3 may contribute to the temporal regulation of the IgH 3' enhancer.

The outcomes of ESRD and its treatment

In recent years, the notion that studying outcomes is a distinct form of clinical research has gained currency. This article offers a conceptual framework for thinking about outcomes research in end-stage renal disease and examines one issue in detail. Although the meaning of the term "outcome" is often assumed, it is currently used in two ways. In the broader sense, outcomes are the results of health care. These may include survival and the presence or absence of symptoms and clinical signs of disease. As it has recently been used in the medical literature, however, the term outcomes frequently connotes outcomes with respect to patient function and experience. Patient experience comprises functional status, general well-being, and satisfaction with care. The principle that the outcomes of end-stage renal disease should be studied has been established. A substantial body of knowledge has accumulated regarding characteristics of the patient population, of the treatments administered, and of the consequences with respect to survival. Whether the investigation and practice of renal replacement therapy should encompass the measurement of patient experience has been a subject of controversy. Reasons to perform such measurements are enumerated, and countervailing arguments are examined critically. The technological prerequisites for success in the widespread measurement of patient experience are set forth.

Regulated activity of the IgH intron enhancer (E mu) in the T lymphocyte lineage

The activity of the IgH (E mu) enhancer in the T lymphocyte lineage has been investigated using both transgenic mice and transfection studies. Thymocyte fractionation experiments indicate that a transgene consisting of the bacterial chloramphenicol acetyl transferase (CAT) gene, linked to E mu and the SV40 early promoter (E mu-CAT), is expressed only in thymocytes with a mature medullary phenotype and not in immature cells. Transfection of this same construct into two thymoma cell lines representing different stages of thymocyte development mimics the pattern of activity observed in vivo. Further transfection experiments suggest that this pattern of expression might be attributed to the differential activity of the E2E3 and octanucleotide motifs of E mu during development. In contrast, an Ig lambda transgene (linked to E mu and an Ig V lambda promoter) is expressed in the majority of thymocytes. We envisage that the different patterns of expression of the two transgenes reflect interactions between their respective promoters and the factors which are bound to E mu at different stages of thymocyte development. Although differing in their pattern of expression within the thymus, the two transgenes share the property of extinction in peripheral T lymphocytes. These results indicate that the expression of E mu-linked transgenes in the thymus cannot simply be explained by activation of the enhancer in a lymphoid progenitor cell prior to B/T lineage divergence. Rather, the enhancer (or components of it) must be independently activated (and inactivated) during T lymphocyte development. Furthermore, this activity is consistent with the developmental timing of Ig DH-JH rearrangements in these cells.

Monitoring dialysis patients' health status

We report 3 years of experience with quarterly assessments of the self-reported health of dialysis outpatients using the Short Form-36 (SF-36) Health Survey. The SF-36 measures eight different dimensions of health: physical function, role limitations due to physical problems, bodily pain, general health perceptions, vitality, social function, role limitations due to emotional problems, and general mental health. On each dimensions, the respondent receives a score from 0 to 100. A higher score indicates better health. Program logistics and results are described, including reliability coefficients, standard deviations, and standard errors of measurement for the SF-36 in this patient population. The SF-36 was completed an average of 4.4 times by 112 patients over an average 14-month follow-up; 40 patients responded at least six times. On most dimensions, the dialysis patients' scores were lower and more variable than those of a sample of the general US population matched for age and sex. For example, mean initial physical function score (+/- SD) was 48.5 +/- 31.2 for the dialysis patients and 84.8 +/- 23.3 for the general population. The mean initial general health perception score of the dialysis patients was 43.7 +/- 23.9 with 71.9 +/- 20.3 for the general population. In contrast, general mental health scores were more comparable. The mean initial general mental health score was 69.6 +/- 17.5 for our patients and 75.5 +/- 18.0 for the general population. Reliability (Cronbach's alpha) ranged from 0.77 for general mental health to 0.93 for physical function. The 95% confidence intervals around individual scores were approximately 20 points, except for role-physical and role-emotional, which were both approximately 30 points. Two case reports compare information obtained from the SF-36 with the dialysis team's assessments of the patient, as recorded in the medical record. The two patients' comments on reviewing their SF-36 results are also summarized. Patient reactions to the health status assessment program are explored, and potential benefits and areas for further work are outlined. Serial measurement of the health status of dialysis patients allows the recognition of clear patterns in individual patient responses. These patterns sometimes suggest that the patient is either substantially more or less impaired than the dialysis team had thought. Changes in these patterns, both transient and protracted, frequently exceed 95% confidence intervals for patient-level scores. Longitudinal health status profiles of individual dialysis patients, accumulated by repeated self-assessment using the SF-36, enhance rather than merely restate the providers' intuitive judgments expressed in the medical record.

Activation of the immunoglobulin kappa 3' enhancer in pre-B cells correlates with the suppression of a nuclear factor binding to a sequence flanking the active core

Both the kappa intron and the kappa 3' enhancer are required for high levels of immunoglobulin kappa gene expression. The activity of both enhancer elements can be induced by LPS in pre-B cells. While the LPS induction of the kappa intron enhancer is mediated by NF-kappa B, this factor is not responsible for activation of the 3' enhancer. Dissection of the 3' enhancer has shown that in pre-B cells the activity of the kappa 3' enhancer is repressed by a region flanking an active core element. We have now scanned this flanking region for nuclear factor binding sites and have identified sites for B-cell specific E47/E12-like proteins and two ubiquitous nuclear proteins. Furthermore, we have identified a nuclear factor in pre-B cells whose binding activity is suppressed in response to LPS. In its tissue-distribution and binding specificity this factor appears to be identical to the lymphoid specific protein LEF-1. The position of the LEF-1 binding site within the 3' enhancer and its response to LPS raise the possibility that LEF-1 may be the target for a second pathway able to mediate LPS induction of immunoglobulin kappa gene transcription.

Vascular occlusion with a balloon-expandable stent occluder

PURPOSE

To evaluate the effectiveness of a new vascular occlusion device.

MATERIALS AND METHODS

The device was created by coating a balloon-expandable stent with a silicone sleeve that tapers to a blind-ended nozzle at its leading end. Once crimp-mounted on an angioplasty balloon catheter, the device is introduced over a guide wire through a small end hole in the nozzle.

RESULTS

The device was tested for stability and occlusive ability. No migration was measured over a pulsatile pulse range of 50-300 mm Hg, and mean flow rate in the occluded vessel was reduced from 443 mL/min +/- 99 (standard deviation) to 1.9 mL/min +/- 2.7. Subsequently, 12 arteries were occluded in three dogs, and immediate vascular occlusion was achieved in all vessels. An arteriovenous fistula was created in another six dogs and was successfully occluded with the device. Follow-up arteriography at 3 months demonstrated persistent occlusion with no migration of the device.

CONCLUSION

This new occlusive device offers immediate vascular occlusion with excellent stability.

Sonographic assessment of fetal cardiac arrhythmias

The fetus with an arrhythmia may be at high risk both from the arrhythmia itself and from the condition that provoked it. Incorrect diagnosis and inappropriate or delayed treatment may further compound the hazard. Although echocardiography can specifically identify the arrhythmia, this technique requires very skilled and careful examination by a physician who fully understands how to differentiate optimally between similar-appearing but mechanistically different arrhythmias. Congenital heart disease may also be present and must be evaluated specifically. This report describes ultrasound recording techniques used to diagnose arrhythmias and includes a discussion of M-mode echocardiography, two-dimensional imaging, pulsed Doppler, and color-flow Doppler. It also differentiates specific arrhythmias--premature atrial contractions, ventricular tachycardia, atrial flutter, complete heart block, and supraventricular tachycardia--and presents the optimal diagnostic tools for each.

Benzene and its phenolic metabolites produce oxidative DNA damage in HL60 cells in vitro and in the bone marrow in vivo

Benzene, an important industrial chemical, is myelotoxic and leukemogenic in humans. It is metabolized by cytochrome P450 2E1 to various phenolic metabolites which accumulate in the bone marrow. Bone marrow contains high levels of myeloperoxidase which can catalyze the further metabolism of the phenolic metabolites to reactive free radical species. Redox cycling of these free radical species produces active oxygen. This active oxygen may damage cellular DNA (known as oxidative DNA damage) and induce genotoxic effects. Here we report the induction of oxidative DNA damage by benzene and its phenolic metabolites in HL60 cells in vitro and in the bone marrow of C57BL/6 x C3H F1 mice in vivo utilizing 8-hydroxy-2'-deoxyguanosine as a marker. HL60 cells (a human leukemia cell line) contain high levels of myeloperoxidase and were used as an in vitro model system. Exposure of these cells to phenol, hydroquinone, and 1,2,4-benzenetriol resulted in an increased level of oxidative DNA damage. An increase in oxidative DNA damage was also observed in the mouse bone marrow in vivo 1 h after benzene administration. A dose of 200 mg/kg benzene produced a 5-fold increase in the 8-hydroxydeoxyguanosine level. Combinations of phenol, catechol, and hydroquinone also resulted in significant increases in steady state levels of oxidative DNA damage in the mouse bone marrow but were not effective when administered individually. Administration of 1,2,4-benzenetriol alone did, however, result in a significant increase in oxidative DNA damage. This represents the first direct demonstration of active oxygen production by benzene and its phenolic metabolites in vivo. The conversion of benzene to phenolic metabolites and the subsequent production of oxidative DNA damage may therefore play a role in the benzene-induced genotoxicity, myelotoxicity, and leukemia.

Patient-based health status measures in outpatient dialysis. Early experiences in developing an outcomes assessment program

This paper describes the initial development of a patient-based outcomes assessment program in an outpatient dialysis unit. This project presented four logistical and practical issues that are discussed in this paper: patient acceptance of quarterly administrations of a generic health status survey (the SF-36); timing of administration during dialysis session; respondent burden; and staff burden. Also discussed are three issues related to the clinical use of these assessments: medical record status of SF-36 data; use in clinical decisionmaking; and clinicians' responses to aggregate data from patient-based health status assessments. The investigation reported presents strong evidence of patient acceptance of the SF-36. Data collection problems reflected the nature of a busy dialysis unit, and most have been corrected. Considering functional status, the role functioning of dialysis patients is most adversely affected; among well-being measures, patients are most compromised by pain and lack of energy. Clinicians' reviews of these results point to the need for normative data, information about severity of primary and comorbid diseases, and knowledge of relationships between SF-36 scores and physiologic parameters to make clinical use of generic health outcome assessments.

Epizootic of pseudorabies among ten swine herds

An epizootic of pseudorabies in 10 swine herds located near Greensburg in Decatur County, Indiana was investigated. Records of Decatur County swine herds previously quarantined because of pseudorabies were obtained. For the 1988 epizootic, clinical findings were considered, location of each of the 10 swine herds in relation to the other herds was determined, and potential fomites were considered. Meteorologic data prior to, during, and after the epizootic were obtained, correlated, and analyzed. A source-receptor model, based on wind direction and speed data, was used to determine whether weather conditions in the Greensburg area enhanced the potential for aerosol spread of pseudorabies virus between herds. On the basis of lack of other modes of spread of pseudorabies and on meteorologic and source-receptor data, aerosol transmission of pseudorabies virus between the 10 herds was probable.

The importance of the 3'-enhancer region in immunoglobulin kappa gene expression

The first enhancers to be identified in the immunoglobulin gene loci are located in the J-C intron. However, deletion of the immunoglobulin kappa intron-enhancer has little effect on the transcription of kappa transgenes. Here we ask whether the second kappa enhancer which we recently identified at the 3'-end of the locus plays a role in kappa gene expression. We show that its omission leads to 20-40 fold lower expression of kappa transgenes and to poor allelic exclusion. Transfection experiments show that activity of the 3'-enhancer, like that of the kappa-intron enhancer, can be induced in a pre-B cell line by incubation with bacterial lipopolysaccharide. Whereas induction of the kappa-intron enhancer is due to induction of NF-kappa B activity, deletion mapping of the 3'-enhancer localises its activity to a 50 nucleotide region that lacks an NF-kappa B site; indeed the 3'-enhancer allows kappa expression in a cell line which lacks NF-kappa B. Thus, both the 3'- and intron-enhancers can be induced at the same stage of differentiation but by distinct pathways. Furthermore, unlike the intron-enhancer, the 3'-enhancer plays a critical role in the transcription of rearranged immunoglobulin kappa genes.

Ablative radioactive iodine therapy for apparently localized thyroid carcinoma. A decision analytic perspective

Adjuvant therapy with ablative radioiodine after surgical resection of apparently localized thyroid carcinoma remains controversial because of the favorable prognosis of thyroid carcinoma and the risk of leukemia from the radioiodine. No controlled trials have been performed to examine this issue. We constructed a decision analytic model to examine whether patients with apparently localized thyroid carcinoma should receive radioiodine. Our analysis suggests that radioiodine modestly improves life expectancy by 2 to 15 months, depending on the patient's age and sex. This model predicts that the benefit of a reduction in the likelihood of recurrence outweighs the risk of leukemia from radioiodine.

Decision analysis in clinical cardiology: when is coronary angiography required in aortic stenosis?

Decision analysis offers a reproducible, explicit approach to complex clinical decisions. It consists of developing a model, typically a decision tree, that separates choices from chances and that specifies and assigns relative values to outcomes. Sensitivity analysis allows exploration of alternative assumptions. Cost-effectiveness analysis shows the relation between dollars spent and improved health outcomes achieved. In a tutorial format, this approach is applied to the decision whether to perform coronary angiography in a patient who requires aortic valve replacement for critical aortic stenosis.

The immunoglobulin kappa locus contains a second, stronger B-cell-specific enhancer which is located downstream of the constant region

The description of cell lines capable of transcribing immunoglobulin heavy or light chain genes in the apparent absence of an active enhancer has led us to look for novel enhancers in the immunoglobulin gene loci. Here we show that there is a second B-cell-specific enhancer in the mouse kappa locus and that this is located 9 kb downstream of C kappa. This enhancer is some 7-fold stronger than the kappa-intron enhancer and shows striking sequence homologies to the lymphotropic papovavirus, IgH and kappa-intron enhancers. The location of the kappa 3' enhancer between C kappa and the RS element means that it is deleted in some B cells that express lambda light chains.

Human immunodeficiency virus infection in health care workers. A method for estimating individual occupational risk

Physicians and other health care workers are concerned about their occupational risk of acquiring human immunodeficiency virus infection. We have developed an approach that can help health care workers estimate their cumulative risk of infection with human immunodeficiency virus. Illustrations are used to develop a score that reflects an individual's occupational exposures and social behavior. This score is then translated into the probability that the worker is infected.