Japanese encephalitis virus antigenic variants with characteristic differences in neutralization resistance and mouse virulence

Two different plaque variants of Japanese encephalitis virus were selected from a wild-type Taiwanese isolate using Vero cells. One variant was found to exhibit small plaque morphology with retarded virus replication kinetics in Vero cells, and was demonstrated to be resistant to monoclonal antibody (mAb) E3.3 neutralization. The other variant showed large plaque morphology, was sensitive to mAb E3.3 neutralization, and manifested reduced virulence in mice on both intracranial and intraperitoneal inoculations. These two variants propagated in Vero cells retained high levels of infectivity but had relatively low HA titers as compared with the parent strain. The envelope sequences of these two variants showed four amino acid differences at residues E-85 (Glu/Arg), E-306 (Glu/Gly), E-331 (Ser/Arg), and E-387 (Met/Arg). Our results indicated the neutralizing epitope of Japanese encephalitis virus did not overlap with virus virulence determinant.

Preliminary findings of an in vitro human spleen mononuclear cell culture system for primary isolates of HIV type 1

Acute HIV-1 infection is often manifested with a high level of viremia. The cell types and tissues/organs that contribute to the virus load are thought to be of central and peripheral lymphoreticular origin. The establishment and permissiveness of organ-based cell culture systems from spleen with laboratory strains or primary isolates of HIV-1 have not been reported. We studied unseparated splenic mononuclear cells (SMCs) and adherent cells derived from human spleen and liver in comparison with blood monocyte-derived macrophages (MDMs). Unstimulated, SMCs were highly permissive to primary lymphotropic HIV-1 and dual/macrophage-tropic isolates (which are able to replicate in both MDMs and PBMCs). Furthermore, SMCs were found to replicate virus to high titer in a rapid log-phase manner and exhibited a prolonged stationary phase of virus production, unlike PBMCs, which required conventional activation with mitogens and exhibited a much shorter period of virus production. Interestingly, the SMCs maintained themselves as a mixed phenotype of nested lymphocytes with complex and well-differentiated macrophage(s) for extended periods of time. In addition, splenic macrophages readily purified by adherence were highly permissive to a dual/macrophage-tropic primary isolate, HIV-1ADA, intermediate with two laboratory strains, HIVR-1RF and HIV-lHXB3, and least permissive to the lymphotropic primary isolate HIV-1Mr452 and two other laboratory strains, HIV-1CC and HIV-1MN. The replication of HIV-1ADA as measured by extracellular p24 was sustained for up to 7 weeks and similar to the replication patterns observed with adherent hepatic macrophages and blood-derived MDMs. This study demonstrates that exogenous stimulation is not required for infection of these cells; either adherence-isolated and/or mixed lymphoid populations can be studied together, and viable stocks can be readily prepared and cryopreserved. In addition, these cells could be used for isolating new and/or other variants of HIV-1. Thus, the use of the SMC primary in vitro cell culture system for future studies involving HIV-1 is warranted.

Reduction in post-intubation respiratory resistance by isoflurane and albuterol

PURPOSE

This study examined the bronchodilating effects of 0.6 MAC and 1.1 MAC isoflurane (ISF) on respiratory system resistance (Rrs) following tracheal intubation and determined whether albuterol supplements that effect.

METHODS

Sixty-seven adult patients were anaesthetized with 2 micrograms.kg-1 fentanyl and 5 mg.kg-1 thiopentone and their tracheas intubated following administration of 1 mg.kg-1 succinylcholine. Respiratory system resistance was measured following intubation and the patients then randomized to receive either 1.1 MAC ISF in oxygen or 0.6 MAC ISF in 50% nitrous oxide and oxygen. Ten minutes later, Rrs was again measured. Patients were then further randomized to receive albuterol or a placebo using incremental doses of 2, 5, and 10 puffs (albuterol puff = 90 micrograms) delivered via a metered dose inhaler at ten minute intervals.

RESULTS

Isoflurane at 1.1 MAC decreased post-intubation Rrs by 23 +/- 5% (mean +/- sem) whereas the decrease was only 7 +/- 5% for 0.6 MAC ISF (P < 0.01). Two puffs of albuterol resulted in a further decrease of 12 +/- 3% (mean +/- sem) in Rrs compared with a 2 +/- 4% decrease in the placebo groups (P < 0.05). Additional puffs of albuterol resulted in no further changes in Rrs.

CONCLUSION

We conclude that following tracheal intubation the reduction in Rrs produced by ISF is highly concentration dependent. Albuterol results in a small further reduction in Rrs.

Binding of src-like kinases to the beta-subunit of the interleukin-3 receptor

We have previously shown that stimulation of 32D cl3 cells with interleukin (IL)-3 results in the activation of three src-like tyrosine kinases, fyn, hck, and lyn. The beta subunit of the IL-3 receptor co-immunoprecipitated with hck in lysates of both unstimulated and IL-3-stimulated cells; however, the beta subunit did not precipitate with either fyn or lyn. The association of these three kinases with the beta subunit of the IL-3 receptor was further investigated using bacterial fusion proteins encoding the unique, SH3, and SH2 domains of these three kinases. Fusion proteins of both hck and fyn bound to a 150-kDa tyrosine-phosphorylated protein present in lysates of IL-3-stimulated cells. This protein was identified as the beta subunit of the IL-3 receptor by immunoblotting with an anti-beta antibody. Glutathione S-transferase (GST) fusion proteins containing the SH2 domain of hck bound to the beta subunit although the amount of beta subunit that bound to the SH2 domain alone was only 30% of that which bound to the fusion protein containing the unique, SH3, and SH2 domains. This indicates that the SH2 domain is one of the motifs involved in binding hck to the beta subunit. A GST fusion protein encoding a 236-amino acid region of the cytoplasmic tail of the beta subunit, which contained four tyrosine residues, bound to hck and fyn. Binding to both proteins was dramatically increased when the GST-beta fusion protein was tyrosine-phosphorylated. Far Western blot analysis was used to demonstrate the binding of the unique, SH3, and SH2 domains of hck to this 236-amino acid region of the beta subunit; tyrosine phosphorylation of this protein increased the binding of both the unique region and the SH2 domain probes. These data indicate that binding of hck to the beta subunit is mediated by both phosphotyrosine-dependent and -independent mechanisms.

Contraceptives for lactating women: a comparative trial of a progesterone-releasing vaginal ring and the copper T 380A IUD

From approximately one week before normal ovulation resumes, lactating women require protection against pregnancy by a contraceptive that is safe for both infant and mother in a multicenter one-year study, the natural hormone, progesterone, delivered vaginally by a sequence of four contraceptive rings designed for continuous use, was evaluated as a contraceptive for nursing mothers in comparison with the Copper T 380A IUD. Individual rings release in effective average dose of 10 mg day for a 3 month period. Evaluation included measures of lactational performance as well as of contraceptive efficacy and safety to mother and child. Nine participating clinics enrolled 802 ring users and 734 IUD acceptors between postpartum days 29 and 63. Life table analyses were performed with parallel decrements for ring and IUD subjects. Continuation in the study and analysis required that subjects not stop breastfeeding. The ring, with a one-year pregnancy rate of 1.5 per 100, did not differ significantly from the IUD with respect to contraceptive effectiveness (p > 0.05). More than half of the ring subjects were continuing at 6 months post admission and a quarter (23.5 per hundred) were still using the ring and breastfeeding one year after admission. Women with the IUD, however, had higher continuation rates (p < 0.001) at both time points. The largest single decrement for each method was that for weaning. Ring users had more complaints of vaginal problems but had fewer vaginal disorders on examination. At 12 months postpartum, 46 per 100 continuing ring users remained in amenorrhea. Lactation performance and the health and weight gain of the infants were similar among users of either regimen.

Transient global amnesia and thalamic hemorrhage

A left rostral thalamic hematoma was found in a 52-year-old hypertensive man who suffered from a 10-h episode of transient global amnesia (TGA). A neuropsychological study revealed no cognitive impairment in a follow-up period for 5 years. The left rostral part of the thalamus appears to be responsible for his TGA, due probably to an interference of the mamillothalamic tract, ventroamygdalofugal pathway or dorsal noradrenergic bundle.

A review of nonparametric tests for changepoint problems, with application to a recombinant drug therapy clinical trial

We review general classes of nonparametric tests for the changepoint problem. We extend these tests to analyze the results of a clinical trial examining whether pretreatment of surgical patients with erythropoietin reduces their subsequent need for blood transfusions. We find a changepoint in baseline hemoglobin levels, below which pretreatment with erythropoietin appears particularly beneficial relative to placebo.

Changepoint statistics for assessing a treatment-covariate interaction

We formulate a stochastic process approach, related to that of Miller and Siegmund (1982, Biometrics 38, 1001-1016), for comparing two treatments in the setting where a covariate might affect the difference between the treatments. We illustrate the approach with data from a recent clinical trial examining whether pretreating subjects scheduled for major elective surgery with erythropoietin reduces their subsequent requirement for blood transfusion. The approach is valuable in identifying a changepoint in baseline hemoglobin level below which subjects appear to be more responsive to the infusion of erythropoietin.

Large-scale Vero cell culture on microcarriers in a twenty-liter stirred tank fermentor

In biotechnology, animal cell culture is an important process for the production of many biologicals such as vaccines, monoclonal antibodies, or other recombinant products. Among many established continuous cell lines, Vero cells can be maintained in many passages in cultures without inducing tumorigenicity and have been recommended by World Health Organization for the production of human biologicals. Owing to its anchorage-dependent growth characteristics, Vero cells can be grown on microcarrier in a suspension vessel where microcarrier provides the culture system with a high culture surface to volume ratio. In this paper we compared the growth kinetics of Vero cells on Cytodex 1 microcarrier in a 20-liter fermentor vs. 100 ml spinner flask culture. The kinetics of Vero cell growth in the 20-liter fermentor was similar to the results obtained from small spinner flask culture, as determined by cell specific growth rate or corresponding doubling time. The approximately 150-fold increase in culture vessel volume did not compromise the growth kinetics of Vero cells, suggesting the system is applicable for large stirred-tank fermentor cultures.

Effect of pretreatment counseling on discontinuation rates in Chinese women given depo-medroxyprogesterone acetate for contraception

The study examined the effect of pretreatment counseling upon discontinuation of 150 mg depo-medroxyprogesterone acetate (Depo-Provera (DMPA)), given for contraception. A total of 421 Chinese women participated, 204 receiving detailed structured pretreatment and ongoing counseling on the hormonal effects and probable side effects of DMPA and 217 receiving only routine counseling. The primary study endpoint was termination rate; secondary endpoints were frequency of medical events and reasons for termination. Study termination rates were significantly lower in the intensive structured counseling group than in the routine counseling group. At one year, the total cumulative termination rates were 11% (23/204) and 42% (92/217), respectively (p < 0.0001). The most common reasons for terminating DMPA were menstrual changes. No pregnancy, serious or unexpected medical events were reported, nor were statistically or clinically significant changes in vital signs observed. We conclude that pretreatment counseling on expected side effects increases the acceptability of DMPA.

A cytopathic infectivity assay of human immunodeficiency virus type 1 in human primary macrophages

In addition to CD4+ T lymphocytes, cells of monocyte/macrophage lineage are a major target for human immunodeficiency virus type 1 (HIV-1) infection. In vitro studies of HIV-1 infection in human monocyte-derived macrophages can be undertaken by a reproducible cell-based assay. A macrophage-based infectivity assay was developed based on the semi-quantitative scoring of HIV-1 induced cytopathology in monolayer macrophage cultures. The assay exhibited dilution-dependent linearity with all three primary macrophage-tropic isolates tested. The end-point infectivity titers determined by this assay correlated with the results obtained by detecting viral p24 antigen in the culture supernatant. The applications of the assay in both neutralization and anti-viral protocols yielded identical results with the more time-consuming and costly p24 formats. Since the assay offers a simple and low-cost method of measuring HIV-1 infectivity in human primary macrophages, it can be used quite easily for large-scale screening or evaluation of candidate vaccines and anti-viral agents.

OKT3 prophylaxis in renal grafts with prolonged cold ischemia times: association with improvement in long-term survival

The data on patients participating in two randomized, prospective studies with similar immunosuppressive regimens were updated and combined to evaluate the long-term effects of OKT3 according to cold ischemia time (< or = or > 24 hr). Among 159 patients in the OKT3 and 153 in the cyclosporine A (CsA) group, 8 and 12 deaths occurred, respectively (P = NS). In patients with cold ischemia > 24 hours, OKT3 prophylaxis resulted in a lower mean number of rejection episodes per patient than did CsA prophylaxis within one year (mean +/- SEM: 0.87 +/- 0.11 vs. 1.35 +/- 0.14, respectively; P = 0.008) and within five years (1.07 +/- 0.12 vs. 1.49 +/- 0.15, respectively; P = 0.032). In contrast, rejection incidences in patients with cold ischemia < or = 24 hours was not significantly different in the two groups. In all study patients, there was a trend towards higher graft survival rates in the OKT3 group versus the CsA group (at 5 years, 73% vs. 66%, respectively; P = 0.182). Among recipients of kidneys with cold ischemia times > 24 hours, OKT3 patients had significantly higher graft survival than CsA patients at two years (84% vs. 64%, respectively) and at five years (71% vs. 56%, respectively; P = 0.045). Significant differences were not observed in recipients of kidneys with cold ischemia times < or = 24 hours. In conclusion, patients receiving renal grafts with long cold ischemia times strongly benefit from OKT3 prophylaxis.

Urinary PCO2 for hemodynamically unstable patients

BACKGROUND

Gastric intramural pH (pHi) derived from gastric PCO2 has been successfully used to assess splanchnic ischemia for patients with unstable hemodynamics, but with some limitations. Urinary bladder, also an easily accessible hollow viscus, should provide as a useful route for the same purpose. However, no study has used urinary PCO2 to evaluate the adequacy of perfusion in critically ill patients.

METHODS

Fifty patients admitted to intensive care unit were included and divided into hemodynamically stable and unstable groups. Several parameters such as arterial pressure, dopamine dosage, heart rate, serum lactate, arterial blood gas, urinary PCO2, and concentrations of Na, K and Cl in urine were measured. Patients with some other renal or pre-renal conditions that might affect urinary PCO2 were excluded.

RESULTS

Urinary PCO2 was markedly higher (78.6 +/- 9.9 vs. 43.1 +/- 1.7 mmHg, p < 0.0001) in unstable group. Serum anion gap level, dopamine dosage and heart rate were significantly higher and PaO2/FiO2 ratio as well as mean arterial pressure was lower in unstable group. Serum lactate, arterial pH and other parameters failed to distinguish between groups. Dopamine dosage significantly correlated with urinary PCO2 (r = 0.5357, p = 0.0149) in unstable group.

CONCLUSIONS

With careful selection of patients, urinary PCO2 can effectively differentiate hemodynamically unstable patients from stable ones. It also correlates significantly with dopamine dosage in patients with unstable hemodynamics.

Pilot study on the effects of a computer-based medical image system

Current medical imaging systems are developed for the purpose of data management. Evaluations of these systems are usually done by assessing users' subjective appreciation rather than objectively gauging performance influence. The present report discusses the evaluation of a medical image presentation system prototype utilizing a cognitive approach. Experimental results showed hypothesized performance improvement attributed to advanced presentation techniques. However, this improvement was almost inadvertently masked by users' previous strategies and interactions with new technology. Overall these data demonstrate the potential benefit of implementing such a system in actual practice as well as provide an example of applying the cognitive approach in evaluating the usability of medical systems.

Increased excretion of tumor necrosis factor alpha and interleukin 1 beta in urine from patients with IgA nephropathy and Schönlein-Henoch purpura

Urinary proteins (5 mg/ml) collected from a group of 16 patients including 13 with IgA nephropathy and 3 with Schönlein-Henoch purpura (SHP) and from a control group consisting of 6 patients with diabetic nephropathy, 5 patients with hypertensive nephrosclerosis, and 5 healthy hospital staff members were studied for the contents of interleukins (IL) 1 beta, 2, 4, 6, and 12 and tumor necrosis factor alpha (TNF-alpha). Eleven patient with IgA nephropathy or SHP (11/16) but only 1 of the controls (1/16) had TNF-alpha activity in urinary proteins (p < 0.01). The IL-1 beta activity exhibited a similar tendency but to a lesser extent (10 of 16 patients with IgA nephropathy or SHP vs. 2 of 16 with other conditions, p < 0.05). Conversely, the detection rates of IL-2, IL-4, and IL-6 in both groups were not significantly different. IL-12 was not found in any of the samples from both groups. Sera and nonpurified urine samples from the same individuals were also measured for cytokines. IL-1 beta, IL-2, IL-4, and IL-12 were absent in all these samples, but TNF-alpha was found in four of the serum samples from patients with IgA nephropathy. Urinary proteins (2 mg/ml) were analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, whereby peptides of 52, 49, 45, 34, 30, and 11 kD could be demonstrated in the patients with IgA nephropathy or SHP. Urinary proteins (200 micrograms/ml from patients with IgA nephropathy or SHP exerted a mitogen-like effect on the normal human mononuclear cells, as demonstrated by 3H-thymidine incorporation. In addition, these urinary proteins (400 micrograms/ml) enhanced the proliferative activity of the cultured rat glomerular mesangial cells. The exaggerated proliferation of rat glomerular mesangial cells exerted by urine proteins from 2 patients with active disease was markedly suppressed after treatment with glucocorticoids/cyclophosphamide. These results suggest that patients with IgA nephropathy or SHP can excrete excessive amounts of TNF-alpha and IL-1 beta in the urine. The inconsistent presence of these two cytokines in urine and serum may indicate that they can be produced locally and that they are implicated in the development of mesangial inflammation and glomerular damage.

Characterization of an endo-beta-1,4-glucanase gene induced by auxin in elongating pea epicotyls

A gene (EGL1) encoding an endo-beta-1,4-D-glucanase (EGase, EC 3.2.1.4) of pea (Pisum sativum) has been cloned and characterized. EGL1 encodes a 486-amino acid polypeptide, including a 24-mer putative signal peptide. The mature protein has a calculated molecular mass of 51.3 kD and an isoelectric point of 9.1. This pea EGase shares significant similarity with EGases from other plant species, but it appears to be distinct from the EGases associated with abscission and fruit ripening. Although EGL1 transcripts are detected in all parts of pea plants, they are relatively abundant in flowers and young pods undergoing rapid growth and most abundant in elongating epicotyls of etiolated seedlings. When epicotyl segments (6 mm long, 4 mm from the apical hook) are incubated in a 5 microM solution of the synthetic auxin analog 2,4-dichlorophenoxyacetic acid, the concentration of EGL1 mRNA increases about 10-fold when the segments elongate most rapidly.

Gene activation by UV light, fungal elicitor or fungal infection in Petroselinum crispum is correlated with repression of cell cycle-related genes

The effects of UV light or fungal elicitors on plant cells have so far been studied mostly with respect to defense-related gene activation. Here, an inverse correlation of these stimulatory effects with the activities of several cell cycle-related genes is demonstrated. Concomitant with the induction of flavonoid biosynthetic enzymes in UV-irradiated cell suspension cultures of parsley (Petroselinum crispum), total histone synthesis declined to about half the initial rate. A subclass of the histone H3 gene family was selected to demonstrate the close correlation of its expression with cell division, both in intact plants and cultured cells. Using RNA-blot and run-on transcription assays, it was shown that one arbitrarily selected subclass of each of the histone H2A, H2B, H3 and H4 gene families and of the genes encoding a p34cdc2 protein kinase and a mitotic cyclin were transcriptionally repressed in UV-irradiated as well as fungal elicitor-treated parsley cells. The timing and extent of repression differed between the two stimuli; the response to light was more transient and smaller in magnitude. These differential responses to light and elicitor were inversely correlated with the induction of phenylalanine ammonia-lyase, a key enzyme of phenylpropanoid metabolism. Essentially the same result was obtained with a defined oligopeptide elicitor, indicating that the same signaling pathway is responsible for defense-related gene activation and cell cycle-related gene repression. A temporary (UV light) or long-lasting (fungal elicitor) cessation of cell culture growth is most likely due to an arrest of cell division which may be a prerequisite for full commitment of the cells to transcriptional activation of full commitment of the cells to transcriptional activation of pathways involved in UV protection or pathogen defense. This conclusion is corroborated by the observation that the histone H3 mRNA level greatly declined around fungal infection sites in young parsley leaves.

Human plasma enhances the infectivity of primary human immunodeficiency virus type 1 isolates in peripheral blood mononuclear cells and monocyte-derived macrophages

Physiological microenvironments such as blood, seminal plasma, mucosal secretions, or lymphatic fluids may influence the biology of the virus-host cell and immune interactions for human immunodeficiency virus type 1 (HIV-1). Relative to media, physiological levels of human plasma were found to enhance the infectivity of HIV-1 primary isolates in both phytohemagglutinin-stimulated peripheral blood mononuclear cells and monocyte-derived macrophages. Enhancement was observed only when plasma was present during the virus-cell incubation and resulted in a 3- to 30-fold increase in virus titers in all of the four primary isolates tested. Both infectivity and virion binding experiments demonstrated a slow, time-dependent process generally requiring between 1 and 10 h. Human plasma collected in anticoagulants CPDA-1 and heparin, but not EDTA, exhibited this effect at concentrations from 90 to 40%. Furthermore, heat-inactivated plasma resulted in a loss of enhancement in peripheral blood mononuclear cells but not in monocyte-derived macrophages. Physiological concentrations of human plasma appear to recruit additional infectivity, thus increasing the infectious potential of the virus inoculum.

Purification, cloning and characterization of two xylanases from Magnaporthe grisea, the rice blast fungus

Magnaporthe grisea, the fungal pathogen that causes rice blast disease, secretes two endo-beta-1,4-D-xylanases (E. C. 3.2.1.8) when grown on rice cell walls as the only carbon source. One of the xylanases, XYN33, is a 33-kD protein on sodium dodecyl sulfate-polyacrylamide gel and accounts for approximately 70% of the endoxylanase activity in the culture filtrate. The second xylanase, XYN22, is a 22-kD protein and accounts for approximately 30% of the xylanase activity. The two proteins were purified, cloned, and sequenced. XYN33 and XYN22 are both basic proteins with calculated isoelectric points of 9.95 and 9.71, respectively. The amino acid sequences of XYN33 and XYN22 are not homologous, but they are similar, respectively, to family F and family G xylanases from other microorganisms. The genes encoding XYN33 and XYN22, designated XYN33 and XYN22, are single-copy in the haploid genome of M. grisea and are expressed when M. grisea is grown on rice cell walls or on oatspelt xylan, but not when grown on sucrose.

The P50 evoked potential component and mismatch detection in normal volunteers: implications for the study of sensory gating

Sensory gating is a complex, multistage, multifaceted physiological function believed to be protecting higher cortical centers from being flooded with incoming irrelevant sensory stimuli. Failure of such mechanisms is hypothesized as one of the mechanisms underlying the development of psychotic states. Attenuation of the amplitude of the P50 evoked potential component with stimulus repetition is widely used to study sensory gating. In the current study, we investigated the responsiveness of the P50 component to changes in the physical characteristics of ongoing trains of auditory stimuli. Forty normal volunteers were studied in a modified oddball paradigm. At all cerebral locations studied, P50 amplitudes were higher in response to infrequent stimuli. We postulate that the increase in P50 amplitude reflects the system's recognition of novel stimuli or "gating in" of sensory input. The ratio of the amplitude of the responses to the infrequent stimuli to those of the frequent stimuli was significantly higher for the posterior temporal regions. This finding provides further evidence that the temporal lobes may be significantly involved in sensory gating processes. Although this study only included normal subjects, the data generated contribute to the understanding of sensory gating mechanisms that may be relevant to psychotic states.

Site dependence of postmortem blood methadone concentrations

A case investigated by the Office of the Chief Medical Examiner, State of Maryland, identified methadone at a heart blood concentration of 2.4 mg/L and a subclavian blood concentration of 0.8 mg/L. Due to these discrepant results, a study was undertaken to determine whether such inconsistencies occurred in other methadone cases. Of the 15 cases studied, only four had heart blood and alternate blood concentrations within 20% of one another. In only 53% of the cases were variations of < 60% observed. The data failed to show a trend where one site was consistently higher or lower than the other site.

Anti-Nform antibody in hemodialysis patients

The anti-Nform antibody is produced by dialysis patients following reuse of dialyzers sterilized with formaldehyde and it has been implicated as a cause of hemolytic anemia. Formaldehyde is one of the common disinfectants used for reprocessing capillary hemodialyzers. The safety of formaldehyde and the clinical significance of anti-Nform antibody need further evaluation. Amongst 45 patients practising dialyzer reuse, anti-Nform antibody was detected in 5 (11.1%), but not amongst 111 patients not reusing their dialyzer (p < 0.005). The presence of anti-Nform was not related to the sex, or duration of dialysis with positive anti-Nform antibody. Direct Coombs' test was positive amongst 80% of all tested patients with anti-Nform antibody, and in 38% of patients reusing dialyzers but without anti-Nform antibody. No tests of hemolysis (including direct Coombs' test) discriminated between anti-Nform antibody-positive and -negative patients, nor between anti-Nform antibody patients with and without overt hemolysis. The best diagnostic test for hemolysis in anti-Nform antibody-positive patients was hematocrit rise after cessation of dialyzer reuse. It appears that despite the induction of anti-Nform antibody, hemolysis is rarely a serious consequence of dialyzer reuse.