Genome-wide association study and functional validation implicates JADE1 in tauopathy

Primary age-related tauopathy (PART) is a neurodegenerative pathology with features distinct from but also overlapping with Alzheimer disease (AD). While both exhibit Alzheimer-type temporal lobe neurofibrillary degeneration alongside amnestic cognitive impairment, PART develops independently of amyloid-β (Aβ) plaques. The pathogenesis of PART is not known, but evidence suggests an association with genes that promote tau pathology and others that protect from Aβ toxicity. Here, we performed a genetic association study in an autopsy cohort of individuals with PART (n = 647) using Braak neurofibrillary tangle stage as a quantitative trait. We found some significant associations with candidate loci associated with AD (SLC24A4, MS4A6A, HS3ST1) and progressive supranuclear palsy (MAPT and EIF2AK3). Genome-wide association analysis revealed a novel significant association with a single nucleotide polymorphism on chromosome 4 (rs56405341) in a locus containing three genes, including JADE1 which was significantly upregulated in tangle-bearing neurons by single-soma RNA-seq. Immunohistochemical studies using antisera targeting JADE1 protein revealed localization within tau aggregates in autopsy brains with four microtubule-binding domain repeats (4R) isoforms and mixed 3R/4R, but not with 3R exclusively. Co-immunoprecipitation in post-mortem human PART brain tissue revealed a specific binding of JADE1 protein to four repeat tau lacking N-terminal inserts (0N4R). Finally, knockdown of the Drosophila JADE1 homolog rhinoceros (rno) enhanced tau-induced toxicity and apoptosis in vivo in a humanized 0N4R mutant tau knock-in model, as quantified by rough eye phenotype and terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) in the fly brain. Together, these findings indicate that PART has a genetic architecture that partially overlaps with AD and other tauopathies and suggests a novel role for JADE1 as a modifier of neurofibrillary degeneration.

ID: 141: ANTIVIRAL INNATE IMMUNE RESPONSES IN HUMAN BRONCHIAL EPITHELIAL CELLS (HBECS) OF SMOKERS ARE IMPAIRED THROUGH EPIGENETIC MODIFICATIONS

Rationale

Chronic obstructive pulmonary disease (COPD) is a leading global cause of morbidity and mortality. Cigarette smoking (CS) is the main risk factor for the development of COPD and most COPD exacerbations are caused by respiratory infections including influenza. Influenza A virus (IAV) infections are more severe in smokers with increased morbidity and mortality. The mechanism of increased susceptibility to infections in smokers is likely due to alteration of immunologic host defenses. Our group has shown that Retinoic acid-inducible protein I (RIG-I) induction in the lung is inhibited by CS in our human lung organ culture model and two animal models.

Methods

We investigated RIG-I, TLR3 and interferon (IFN) induction by IAV in human bronchial epithelial cells (HBEC) isolated from smokers or non-smokers. Subcultured HBECs were infected with A/Puerto Rico/8/1934 (PR8) influenza virus at an MOI of 1. Virus-free diluents (mock) were used as negative controls. After 24 h infection, cells and supernatants were collected for qRT-PCR, immunoblot or ELISA to determine RIG-I, TLR3 and IFN expression levels.

Results

As expected, we found IAV PR8 exposure induced a vigorous IFN-β, IFN-λ 1 and IFN-λ 2/3 antiviral response in HBECs from nonsmokers as well as high RIG-I and TLR3 induction by virus. In cells from smokers, viral RIG-I and TLR3 mRNA induction was reduced 87% and 79% compared to the response from nonsmokers. CS inhibited viral induction of the IFN-β, IFN-λ1 and IFN-λ 2/3 mRNA response 85%, 96% and 95%, respectively, from that seen in HBEC from nonsmokers. However, preincubation with the demethylating agent 5-Aza-2-deoxycytidine reversed the immunosuppressive effects of CS exposure in HBEC since normal induction of all three IFNs was restored. We also demonstrated, even without virus infection, that IFN-β-mediated induction of RIG-I and TLR3 was also suppressed in cells from smokers.

Conclusions

Our results suggest that active smoking reduces expression of antiviral cytokines in primary HBECs. This effect likely occurs via downregulation of RIG-I and TLR3 through epigenetic modifications. Reduction in lung epithelial cell RIG-I and TLR3 responses may be one major mechanism contributing to the increased incidence of viral respiratory infections in smokers and to viral induction of acute exacerbations of COPD.

ID: 106: ALVEOLAR ESCAPE BY BACILLUS ANTHRACIS SPORES DOES NOT REQUIRE A CARRIER CELL AND IS NOT ALTERED BY LETHAL TOXIN

Rationale

The lung is the entry site for Bacillus anthracis in inhalation anthrax, the most deadly form of the disease. B. anthracis spores must escape from the alveolus, pass to the regional lymph nodes, germinate and enter the circulatory system as vegetative bacteria to cause systemic disease. Of the resident lung cells, three have been reported to take up B. anthracis spores: the antigen presenting cells (APC) alveolar macrophages and dendritic cells, and alveolar epithelial cells (AEC). Also, B. anthracis produces the exotoxins lethal factor and protective antigen (PA) which combine to form lethal toxin (LT), a metalloproteinase important in pathogenicity. The roles of carrier cells and the effects of B. anthracis toxins in escape of spores from the alveolus are unclear, especially in humans.

Methods

We employed a human lung organ culture model and a human A549 alveolar epithelial cell culture model, along with fluorescent confocal imaging to quantitate spore partitioning between APC and AEC, and the effects of B. anthracis LT and PA on this process. Cell types were distinguished by positive staining for HLA-DR (APC) and cytokeratin (AEC).

Results

We found that spores progressed through the lung slice over time, and that spore movement was not dependent on cell internalization. Both free and cell-associated spores moved through slices between 2 and 48 hrs of incubation. However, partitioning of spores between AEC, APC, and the extracellular space did not significantly change over this time. After 2 hrs, 4.7% of spores were in APC; 13.8% in AEC; and 81.5% were not cell-associated. By 48 hrs, 2.9% were in APC; 12.7% were in AEC; and 84.4% were not cell-associated. Spores also internalized in a non-uniform manner, with more variable spore internalization into AEC than into APC. At all incubation times, the majority of cell-associated spores were in AEC, not in APC. PA and LT did not affect transit of the spores through the lung tissue or the distribution of spores into AEC and APC. In A549 cells, spore internalization increased significantly after 24 hrs incubation. However, there was no statistically consistent effects of PA or LT on spore internalization in A549 cells.

Conclusions

Overall, our results support a “Jailbreak”-like model of spore escape from the alveolus that involves transient passage of spores, although this occurs through intact AEC. However, subsequent transport of spores by APC from the lung to the lymph nodes may occur.

Mechanisms of HIV-1 Tat neurotoxicity via CDK5 translocation and hyper-activation: role in HIV-associated neurocognitive disorders

The advent of more effective antiretroviral therapies has reduced the frequency of HIV dementia, however the prevalence of milder HIV associated neurocognitive disorders [HAND] is actually rising. Neurodegenerative mechanisms in HAND might include toxicity by secreted HIV-1 proteins such as Tat, gp120 and Nef that could activate neuro-inflammatory pathways, block autophagy, promote excitotoxicity, oxidative stress, mitochondrial dysfunction and dysregulation of signaling pathways. Recent studies have shown that Tat could interfere with several signal transduction mechanisms involved in cytoskeletal regulation, cell survival and cell cycle re-entry. Among them, Tat has been shown to hyper-activate cyclin-dependent kinase [CDK] 5, a member of the Ser/Thr CDKs involved in cell migration, angiogenesis, neurogenesis and synaptic plasticity. CDK5 is activated by binding to its regulatory subunit, p35 or p39. For this manuscript we review evidence showing that Tat, via calcium dysregulation, promotes calpain-1 cleavage of p35 to p25, which in turn hyper-activates CDK5 resulting in abnormal phosphorylation of downstream targets such as Tau, collapsin response mediator protein-2 [CRMP2], doublecortin [DCX] and MEF2. We also present new data showing that Tat interferes with the trafficking of CDK5 between the nucleus and cytoplasm. This results in prolonged presence of CDK5 in the cytoplasm leading to accumulation of aberrantly phosphorylated cytoplasmic targets [e.g.: Tau, CRMP2, DCX] that impair neuronal function and eventually lead to cell death. Novel therapeutic approaches with compounds that block Tat mediated hyper-activation of CDK5 might be of value in the management of HAND.

Systemic Central Nervous System (CNS)-targeted Delivery of Neuropeptide Y (NPY) Reduces Neurodegeneration and Increases Neural Precursor Cell Proliferation in a Mouse Model of Alzheimer Disease

Neuropeptide Y (NPY) is one of the most abundant protein transmitters in the central nervous system with roles in a variety of biological functions including: food intake, cardiovascular regulation, cognition, seizure activity, circadian rhythms, and neurogenesis. Reduced NPY and NPY receptor expression is associated with numerous neurodegenerative disorders including Alzheimer disease (AD). To determine whether replacement of NPY could ameliorate some of the neurodegenerative and behavioral pathology associated with AD, we generated a lentiviral vector expressing NPY fused to a brain transport peptide (apoB) for widespread CNS delivery in an APP-transgenic (tg) mouse model of AD. The recombinant NPY-apoB effectively reversed neurodegenerative pathology and behavioral deficits although it had no effect on accumulation of Aβ. The subgranular zone of the hippocampus showed a significant increase in proliferation of neural precursor cells without further differentiation into neurons. The neuroprotective and neurogenic effects of NPY-apoB appeared to involve signaling via ERK and Akt through the NPY R1 and NPY R2 receptors. Thus, widespread CNS-targeted delivery of NPY appears to be effective at reversing the neuronal and glial pathology associated with Aβ accumulation while also increasing NPC proliferation. Overall, increased delivery of NPY to the CNS for AD might be an effective therapy especially if combined with an anti-Aβ therapeutic.

Correlation between reduction in plasma HIV-1 RNA concentration 1 week after start of antiretroviral treatment and longer-term efficacy

BACKGROUND

Early assessment of antiretroviral drug efficacy is important for prevention of the emergence of drug-resistant virus and unnecessary exposure to ineffective drug regimens. Current US guidelines for changing therapy are based on measurements of plasma HIV-1 RNA concentrations 4 or 8 weeks after the start of treatment with cut-off points of 0.75 or 1.00 log, respectively. We investigated the possibility of assessing drug efficacy from measurements of plasma HIV-1 concentrations made during the first week on therapy.

METHODS

The kinetics of virus decay in plasma during the first 12 weeks of treatment was analysed for 124 HIV-1-infected patients being treated for the first time with a protease inhibitor. Patients with a continuous decline of HIV-1 concentrations and in whom HIV-1 was either undetectable or declined by more than 1.5 log at 12 weeks were defined as good responders; the rest were poor responders.

FINDINGS

The individual virus decay rate constants (k) at day 6 correlated significantly (r>0.66, p<0.0001) with changes in HIV-1 concentrations at 4, 8, and 12 weeks, and correctly predicted 84% of the responses with a cut-off value of k=0.21 per day (in log scale). Reduction in plasma HIV-1 of less than 0.72 log by day 6 after initiation of therapy predicted poor long-term responses in more than 99% of patients.

INTERPRETATION

These results suggest that changes in HIV-1 concentration at day 6 after treatment initiation are major correlates of longer-term virological responses. They offer a very early measure of individual long-term responses, suggesting that treatment could be optimised after only a few days of therapy.

Defects of DNA mismatch repair in human prostate cancer

Loss of mismatch repair (MMR) function leads to the accumulation of errors that normally occur during DNA replication, resulting in genetic instability. Germ-line mutations of MMR genes in the patients with hereditary nonpolyposis colorectal cancer lead to inactivation of MMR protein functions, and the defects of MMR are well correlated to the high rate of microsatellite instability in their tumors. Previous studies (T. Uchida, et al. Oncogene, 10: 1019-1022, 1995; S. Egawa, et al. Cancer RES:, 55: 2418-2421, 1995; J. M. Cunningham, et al. Cancer RES:, 56: 4475-4482, 1996; X. Gao, et al. Oncogene, 9: 2999-3003, 1994; H. Rohrbach, et al. Prostate, 40: 20-27, 1999) have shown that genetic instability (chromosomal and microsatellite instability) is detectable in human prostate cancer. To elucidate the role of MMR genes in the tumorigenesis of prostate cancer, we evaluated the expression of these genes in human cancer cell lines and in tumor specimens. Using Western blot analysis, we detected loss among MSH2, MLH1, PMS2, and PMS1 proteins in DU145, LNCaP, p69SV40T, M2182, and M12 cells. In addition, genomic instability in the prostate cell lines including DU145, PC3, LNCaP, p67SV40T, M2182, and M12 was detected by a microsatellite mutation assay. Significantly, immunohistochemical analysis of prostatic tissue revealed the reduction or absence of MMR protein expression in the epithelium of prostate tumor foci compared with normal adjacent prostate tissue. In contrast to hereditary nonpolyposis colorectal cancer, characterized by defects predominantly in MLH1 and MSH2, the samples we examined showed more tumor foci with loss of PMS1 and PMS2. PMS1, which is only expressed in the basal cells in normal glands, is conspicuously absent in most prostate cancer. From these results, we conclude that there are defects of MMR genes in human prostate cancer.

A flow cytometric protocol for titering recombinant adenoviral vectors containing the green fluorescent protein

As the use of adenoviral vectors in gene therapy protocols increases, there is a corresponding need for rapid, accurate, and reproducible titer methods. Multiple methods currently exist for determining titers of recombinant adenoviral vector, including optical absorbance, electron microscopy, fluorescent focus assay, and the "gold standard" plaque assay. This paper introduces a novel flow cytometric method for direct titer determination that relies on the expression of the green fluorescent protein (GFP), a tracking marker incorporated into several adenoviral vectors. This approach was compared to the plaque assay using 10(-4)- to 10(-6)-fold dilutions of a cesium-chloride-purified, GFP expressing adenovirus (AdEasy + GFP + GAL). The two approaches yielded similar titers: 3.25 +/- 1.85 x 10(9) PFU/mL versus 3.46 +/- 0.76 x 10(9) green fluorescent units/(gfu/mL). The flow cytometric method is complete within 24 h in contrast to the 7 x 10 days required by the plaque assay. These results indicate that the GFU/mL is an alternative functional titer method for fluorescent-tagged adenoviral vectors.

Nurses as writers

Although nurses are expected to be competent in on-the-job writing, most nurses receive little formal education in the types of writing required in practice. Thus, it is important for faculty in schools of nursing to include in the curricula various types of writing assignments to help students develop these skills. This article describes how at one university a course, "Nurses as Writers," provides opportunities for students to learn and practice the types of writing needed in their professional careers.

Pharmacokinetic modeling of recombinant interleukin-2 in patients with human immunodeficiency virus infection

A novel model was developed to characterize the time-varying clearance of recombinant interleukin-2 (IL-2). Sixty-eight patients with human immunodeficiency virus infection received 83 cycles of IL-2 either by continuous infusion or by subcutaneous injection for 5 days. IL-2 concentrations after intravenous infusions peaked at 24 hours and then declined by 55% to 78% during the remainder of the infusion. Soluble IL-2 receptors increased greater than 10-fold before gradually returning to baseline. Subcutaneous administration showed a dose-dependent decrease in area under the concentration-time curve (AUC) between days 1 and 5. A model was developed in 9 patients who had IL-2 concentrations and soluble IL-2 receptors determined by ELISA. Concentrations were fitted by an indirect stimulatory pharmacodynamic model. An additional 59 patients with only IL-2 concentrations were fitted to a simplified empiric model. Both models provided an overall r2 of 0.99 for the plot of observed versus fitted concentrations. The time-dependent increase in IL-2 clearance, likely receptor-mediated, was well described with use of an indirect-effects pharmacokinetic-pharmacodynamic model.

Heterozygosity for a defective gene for CC chemokine receptor 5 is not the sole determinant for the immunologic and virologic phenotype of HIV-infected long-term nonprogressors

HIV-1-infected long-term nonprogressors are a heterogeneous group of individuals with regard to immunologic and virologic markers of HIV-1 disease. CC chemokine receptor 5 (CCR5) has recently been identified as an important coreceptor for HIV-1 entry into CD4+ T cells. A mutant allele of CCR5 confers a high degree of resistance to HIV-1 infection in homozygous individuals and partial protection against HIV disease progression in heterozygotes. The frequency of CCR5 heterozygotes is increased among HIV-1- infected long-term nonprogressors compared with progressors; however, the host defense mechanisms responsible for nonprogression in CCR5 heterozygotes are unknown. We hypothesized that nonprogressors who were heterozygous for the mutant CCR5 gene might define a subgroup of nonprogressors with higher CD4+ T cell counts and lower viral load compared with CCR5 wild-type nonprogressors. However, in a cohort of 33 HIV-1-infected long-term nonprogressors, those who were heterozygous for the mutant CCR5 gene were indistinguishable from CCR5 wild-type nonprogressors with regard to all measured immunologic and virologic parameters. Although epidemiologic data support a role for the mutant CCR5 allele in the determination of the state of long-term nonprogression in some HIV-1- infected individuals, it is not the only determinant. Furthermore, long-term nonprogressors with the wild-type CCR5 genotype are indistinguishable from heterozygotes from an immunologic and virologic standpoint.

The geoepidemiology of primary biliary cirrhosis

There are apparently large geographical and secular variations in the prevalence of primary biliary cirrhosis worldwide. Most studies suggest that the disease is most common in Northern Europe, particularly northern Britain and Scandinavia, and that the prevalence is increasing. This comprehensive review of the literature explores to what extent these variations could be real rather than artifactual due to lack of comparability among studies. The major design flaws are examined and guidelines for better practice are outlined. It is hoped that other researches will utilize these recommendations for future studies so that true variations can be identified and hypotheses regarding disease causation may be formulated and investigated. These guidelines include: stringent case inclusion criteria; definition of date of disease onset; well-defined study period, area and population; multiple case finding methods; rigorous tracing of all possible cases. Preliminary results of the authors' study using these guidelines are described and report a point prevalence of 235 per million population in 1994 in the north of England, the highest yet reported.

Requirement for nursing care services and associated costs in acute spinal cord injury

The purpose of this study was to analyze the requirement for professional nursing care and the nursing care costs for patients with acute spinal cord injury. This descriptive study used a convenience sample of 50 consecutively admitted spinal cord-injured (SCI) patients who agreed to participate. Trained data collectors interviewed patients daily, reviewed the chart and spoke with the patient's nurses, after which nursing diagnoses were determined and acuity calculated. The sample consisted of 26 quadriplegic (Q), 5 ventilator-dependent quadriplegic (V) and 19 paraplegic (P) SCI subjects. The median length of stay (LOS) was 16 days with an intensive care unit (ICU) LOS of 4 days. LOS in the intermediate unit was 11 days. Median hours of nursing care was 143 (translating to $2458) for the entire acute care hospitalization. Specific hours of care and consequent costs were determined for all three groups through both phases of care. Significant differences were found in the hours of nursing care required among the three groups (X2 7.18, df = 2, p < .03), even though no difference was found in the LOS. A nursing consumption ratio (hours of nursing care/hours of LOS) demonstrated that ventilator-dependent SCI patients required the greatest number of nursing care hours.

Development of the brine shrimp Artemia is accelerated during spaceflight

Developmentally arrested brine shrimp cysts have been reactivated during orbital spaceflight on two different Space Shuttle missions (STS-50 and STS-54), and their subsequent development has been compared with that of simultaneously reactivated ground controls. Flight and control brine shrimp do not significantly differ with respect to hatching rates or larval morphology at the scanning and transmission EM levels. A small percentage of the flight larvae had defective nauplier eye development, but the observation was not statistically significant. However, in three different experiments on two different flights, involving a total of 232 larvae that developed in space, a highly significant difference in degree of flight to control development was found. By as early as 2.25 days after reactivation of development, spaceflight brine shrimp were accelerated, by a full instar, over ground control brine shrimp. Although developing more rapidly, flight shrimp grew as long as control shrimp at each developmental instar or stage.

Embryogenesis, hatching and larval development of Artemia during orbital spaceflight

Developmental biology studies, using gastrula-arrested cysts of the brine shrimp Artemia franciscana, were conducted during two flights of the space shuttle Atlantis (missions STS-37 and STS-43) in 1991. Dehydrated cysts were activated, on orbit, by addition of salt water to the cysts, and then development was terminated by the addition of fixative. Development took place in 5 ml syringes, connected by tubing to activation syringes, containing salt water, and termination syringes, containing fixative. Comparison of space results with simultaneous ground control experiments showed that equivalent percentages of naupliar larvae hatched in the syringes (40%). Thus, reactivation of development, completion of embryogenesis, emergence and hatching took place, during spaceflight, without recognizable alteration in numbers of larvae produced. Post-hatching larval development was studied in experiments where development was terminated, by introduction of fixative, 2 days, 4 days, and 8 days after reinitiation of development. During spaceflight, successive larval instars or stages, interrupted by molts, occurred, generating brine shrimp at appropriate larval instars. Naupliar larvae possessed the single naupliar eye, and development of the lateral pair of adult eyes also took place in space. Transmission electron microscopy revealed extensive differentiation, including skeletal muscle and gut endoderm, as well as the eye tissues. These studies demonstrate the potential value of Artemia for developmental biology studies during spaceflight, and show that extensive degrees of development can take place in this microgravity environment.

Powerlessness in acute spinal cord injury patients: a descriptive study

The purpose of this study was to describe the frequency and characteristics of the nursing diagnosis, powerlessness, in an acute spinal cord injury (SCI) population. This descriptive study had a sample of 50 SCI patients admitted during the acute phase of injury to a model systems SCI center. Patients with a length of stay of greater than or equal to 15 days experienced a significantly higher (p less than .01) occurrence of powerlessness than did those with hospitalization of less than 15 days. Powerlessness was not found to cluster or occur in any pattern but was random throughout hospitalization. There was a statistically significant relationship (p less than .01) between the occurrence of powerlessness and patient acuity, with the occurrence increasing as acuity increased in severity. Quadriplegics and patients over the age of 60 years had a higher occurrence of powerlessness (p less than .05). This study demonstrated powerlessness was a commonly occurring diagnosis in acute SCI.

Brine shrimp development in space: ground-based data to shuttle flight results

The brine shrimp, Artemia salina, has been used as a model system to assess microgravity effects on developing organisms. Following fertilization and early development, the egg can arrest in early gastrula as a dehydrated cyst stage that is stable to harsh environments over long time periods. When salt water is added, the cysts can reactivate, with embryonic development and egg hatching occurring in about 24 h. A series of larval molts or instars, over about a 2 week period, results in the adult crustacean. We have assessed these developmental events in a closed syringe system, a bioprocessing module, in ground-based studies, and have conducted preliminary in-orbit experiments aboard the Space Shuttle Atlantis during the flights of STS-37 and STS-43. Although the in-flight data are limited, spectacular degrees of development have been achieved.

Use of a new CD4-positive HeLa cell clone for direct quantitation of infectious human immunodeficiency virus from blood cells of AIDS patients

A new CD4-positive HeLa cell line (clone 1022) with increased sensitivity for human immunodeficiency virus (HIV) isolates derived from AIDS patients could titer infectivity of HIV from most isolates at a level equal to that observed using normal human phytohemagglutinin (PHA)-stimulated lymphocyte cultures. By use of this clone with a focal immunoassay (FIA), peripheral blood mononuclear cells (PBMC) producing HIV were detected in 15% of seropositive asymptomatic patients and 23% of AIDS patients at a frequency of 1 in 2 x 10(4) to 3 x 10(6) PBMC. HIV detection by primary FIA correlated with low CD4-positive cells counts. HIV activation in cocultures with PHA blasts resulted in increasing numbers of cells releasing HIV starting 3-4 days after cocultivation. The low incidence of HIV detection by direct FIA compared with the high incidence of HIV isolation after cocultivation with PHA blasts provided quantitative infectivity data suggesting that HIV was in a state of latency or low expression in most PBMC of AIDS patients.

Bilateral fallopian tubal polyps: radiologic and pathologic correlation

A case of bilateral fallopian tube filling defects found on hysterosalpingography performed on a patient for infertility work-up is presented. Repeat hysterosalpingography performed 4 years later showed no change. Microsurgical resection revealed the defects to be fallopian tubal polyps of endometrial origin.

Common cardiac drugs and rehabilitation

Cardiac patients are often on drugs. They invariably benefit from a rehabilitation programme where they may be seen more frequently than in a routine follow-up clinic. Rehabilitation units must keep alert for drug-induced adverse effects or symptomatic deterioration, as well as the more usual psychological and physical benefits they induce.

Evoked potentials: nursing perspectives

An evoked potential is an electrical manifestation of the brain's response to an external stimulus. Evoked potential studies provide a sensitive, quantitative assessment of portions of the neurological system which may enhance clinical data but do not indicate specific diagnosis. Nurses, by enhancing self knowledge related to evoked potential studies, should be better able to present concise information to patient and families. The outcome will be a more knowledgeable and less anxious patient.

Effect of microaggregate blood filtration on granulocyte concentrates in vitro

To determine the effect of transfusing granulocyte concentrates through microaggregate blood filters, granulocytes prepared with a cell processor were passed through screen and depth microaggregate filters. Pre- and postfiltration evaluations were made of total granulocyte count, levels of muramidase, granulocyte viability, motility, phagocytosis, bactericidal activity, and hydrogen peroxide-forming capacity. Compared to prefiltration levels, a significant (p less than 0.05) decrease in postfiltration granulocyte counts was seen for all the depth filters studied but not for the standard 170 microns (control) or the 40 microns screen filter. For the various tests of granulocyte function evaluated prefiltration, no significant postfiltration differences (p greater than 0.05) were seen for any of the filters studied. Screen microaggregate filters retained only 1 to 3 percent of granulocytes contained in the concentrates, and thus appear satisfactory for use in clinical transfusions. The large percentage of neutrophils retained by the depth filters (20-62%), however, precludes their use for transfusion of granulocyte concentrates.

H2O2 release from human granulocytes during phagocytosis. I. Documentation, quantitation, and some regulating factors

The extinction of fluorescence of scopoletin during its oxidation by horseradish peroxidase (HPO) provides a highly sensitive and specific assay for small quantities of peroxide in solution. With this assay, the release of free H2O2 into the extracellular medium by phagocytizing human granulocytes has been documented and quantitated, and some of the regulating factors have been determined. Under basal conditions granulocytes released less than 0.01 nmol/ml of H2O2 (2.5 X 10-6 polymorphonuclear leukocytes/ml). Upon the addition of phagocyte particles (latex, opsonized yeast, or staphylococci), an abrupt increase in extracellular peroxide concentration was observed (greater than 50-fold above basal levels) after latencies as short as 10 s. Release reflected increased intracellular H2O2 production during phagocytosis in that it paralleled the respiratory burst and was absent when phagocytosis was prevented or when cells from patients with chronic granulomatous disease were utilized. Evidence that scpoletin oxidation occurred predominantly in the extracellular medium was obtained by demonstrating a marked inhibition when HPO was omitted from the reaction mixture or when exogenous catalase was added. Similarly, it was found that exogenous serum also inhibited scopoletin oxidation, apparently because of the presence of competing hydrogen donors. H2O2 formation and release were observed at rates which closely paralleled those of phagocytosis. With O2 consumption as an approximate index of H2O2 formation, the fractions released during maximal rates of particle uptake were calculated as follows: for latex, 15.7%; for staphylococci, 10.3%; and for yeast, 4.9%. It is postulated that release is due to diffusion of free H2O2 from an expanded intracellular pool of this substance that develops during phagocytosis. This poos represents tha net of increased synthesis versus catabolism by various enxymatic pathways for H2O2 disposal within the cells. The close relationship between rates of H2O2 formation and rates of phagocytosis by human granulocytes suggests a role for specialized areas of the cell membrane, involved in particle ingestion, in the trigger mechanism for H2O2 synthesis. The consequences of H2O2 release to other cells or organisms in the immediate environment of phagocytizing granulocytes remain to be determined.