Biomedical subjects

R M Novak

Publications and source records attributed to R M Novak.

At least 19 recordsLinked to original sources

PubMed2003

Brevibacterium casei bacteremia and line sepsis in a patient with AIDS.

Brevibacteria are obligately aerobic gram-positive bacilli that are associated with milk products and are also found on human skin. Strains of Brevibacterium casei have been found to correspond to Centers for Disease Control coryneform groups B-1 and B-3 and have been isolated from a variety of human clinical specimens. In this report, we describe a case of B. casei bacteremia and sepsis in a patient with AIDS associated with a contaminated Hickmann catheter and review the microbiology and characteristics of these emerging opportunistic pathogens.

AIDS-Related Opportunistic Infections↗

PubMed2001

Discordant CD4 T lymphocyte responses to antiretroviral therapy for HIV infection are associated with ex-vivo rates of apoptosis.

Our purpose was to determine if changes in CD4 cell counts in HIV-infected patients with good viral suppression on stable antiretroviral regimens could be predicted by ex-vivo rates of apoptosis of peripheral blood mononuclear cells (PBMC). Patients were grouped by lowest pre-treatment and highest on-treatment CD4 cell counts and classified as complete immune responders, partial responders, or non-responders. Whole blood was collected from a subgroup of patients and controls, and rates of the ex-vivo apoptosis of PBMC were assessed. Non-responders exhibited significantly increased apoptosis, whereas good immune responses were associated with decreased apoptosis. Persistently accelerated apoptosis may contribute to persisting immune deficiency independent of the viral load.

Adult↗

PubMed2000

Mycobacterium avium induces HIV upregulation through mechanisms independent of cytokine induction.

Mycobacterium avium complex (MAC) can induce upregulation of HIV. To investigate the underlying mechanisms, the effect of MAC-induced cytokines on HIV replication was first studied. Semiquantitative RT-PCR, followed by Northern blot analysis, revealed that mRNA encoding IL-6 and TNF-alpha was induced by MAC. However, production of these cytokines was undetectable and the addition of anti-cytokine antibodies to coinfected cells could only minimally block the MAC effect on HIV. Infection of U38 cells with MAC resulted in enhancement of HIV-1 LTR-CAT transcription. In addition, transient transfection of U937 cells with full-length wild-type as well as NF-kappaB-binding site-deleted mutant HIV-1 LTR-CAT constructs revealed that MAC-induced HIV-LTR CAT is NF-kappaB dependent. These findings, together with our previous work, indicate that MAC-induced cytokine expression increases the formation of NF-kappaB, which in turn enhances HIV-1 LTR-CAT transcription. However, additional factor(s) yet to be elucidated may play a more significant role in MAC-mediated HIV-upregulation.

Blotting, Northern↗

PubMed2000

Verbal working memory in HIV-seropositive drug users.

Recent evidence suggests that HIV-seropositive drug users are impaired on tasks of visuospatial working memory compared with drug users seronegative for HIV. In the current study we evaluated the performance of 30 HIV-seropositive male drug users and 30 risk-matched seronegative controls on two measures of verbal working memory, the Listening Span and the verbal Self Ordered Pointing Task. Impaired working memory performance was significantly more common among HIV-seropositive persons compared to controls, with the highest incidence of deficit among symptomatic participants. These findings indicate that working memory deficits in persons with HIV are not domain-specific and can be demonstrated reliably in drug users.

Adult↗

PubMed2000

Lymphoproliferative responses to mitogens and prepared antigens of M. avium complex in patients with HIV infection.

Published reports have demonstrated that antigens of Mycobacterium avium complex (MAC) can suppress the normal response to mitogens in lymphoproliferation assays. We therefore studied the lymphoproliferative (LP) function of PBMC from 55 HIV-infected patients and 16 controls in response to mitogens with and without MAC antigen. As expected, LP responses decline with progressive decline in CD4 count; MAC antigen in combination with PHA further suppresses that response in a dose-dependent manner. More relevant were the LP responses in those with CD4 counts less than 100. All patients with MAC disease had poor responses (stimulation index, SI < 10) to PHA or anti-CD3 with or without MAC antigen. Those who did not have nor subsequently developed MAC were both good (SI > 10) or poor responders (SI < 10). The suppressive effect of MAC on lymphocyte function may serve as a weak virulence factor which is only relevant in severely immunocompromised HIV patients.

AIDS-Related Opportunistic Infections↗

PubMed1999

Mycobacterium avium complex activates nuclear factor kappaB via induction of inflammatory cytokines.

A variety of microorganisms has been reported to directly induce NF-kappaB, a critical step in the regulation of genes involved in the cellular immune response. In this study, we demonstrate that proinflammatory cytokines such as tumor necrosis factor alpha (TNFalpha) produced upon activation by the Mycobacterium avium complex (MAC) preceed NF-kappaB activity in U937, a human monocytoid cell line. MAC induction of TNFalpha mRNA expression was detected within 15 min after MAC infection, whereas enhanced NF-kappaB binding activity was not detected until 90 to 120 min postinfection. Supershift analysis revealed increased p50 in the MAC-induced NF-kappaB binding complexes. Consistent with an autocrine mechanism, anti-TNFalpha antibody and dexamethasone, a known cytokine inhibitor, both completely suppressed the effect of MAC on the induction of NF-kappaB. Taken together, these findings suggest that exposure of monocyte cell membranes to MAC induces endogenous TNFalpha, which in turn enhances NF-kappaB binding activity. The rapid induction of TNFalpha may be important in the initial host response to MAC infection.

Autocrine Communication↗

PubMed1999

Reaction times are faster in HIV-seropositive patients on antiretroviral therapy: A preliminary report.

We evaluated subclinical mental and motor slowing in 142 HIV-seropositive patients without dementia, using computerized simple and choice reaction time tasks and self-report measures of psychological distress. Patients on antiretroviral therapy at the time of testing (n = 79) had significantly faster choice reaction times (p < 0.05), indicating faster mental processing speed, than untreated patients (n = 63). These faster RTs could not be attributed to differences in age, education, risk factors, degree of immunosuppression, substance abuse history, peripheral neuropathy, or psychological distress. Reaction time tasks should be investigated further as potential outcome measures in clinical trials, particularly for subjects with few or no overt cognitive deficits.

Adult↗

PubMed1998

Information processing and antiretroviral therapy in HIV-1 infection.

Computerized reaction time (RT) tasks are sensitive measures of subclinical HIV-related mental slowing. We previously reported that nondemented HIV-seropositive patients on antiretroviral therapy at the time of testing had faster choice RTs compared to matched untreated seropositive participants. In the present study, we evaluated the performance of 163 nondemented HIV-seropositive participants on a reaction time version of the Stroop task as a function of antiretroviral status. Persons on antiretroviral therapy at the time of testing had significantly faster reaction times than untreated individuals, although treated asymptomatic participants showed significantly less Stroop interference than treated symptomatic participants. These effects could not be attributed to differences in demographic variables, disease status, substance abuse, or psychological distress. These data indicate that central information processing is faster for patients treated with antiretroviral compounds compared to untreated patients, and suggest that reaction time tasks may have significant potential utility in clinical trials of neuroprotective compounds.

AIDS Dementia Complex↗

PubMed1997

Working memory deficits in HIV-seropositive drug users.

We studied the integrity of working memory operations in 38 HIV-seropositive and 20 seronegative drug users, using a modified version of the Tower of London task. This new task, the Tower of London-Working Memory version (TOL-WM), includes a delayed-response component in addition to the planning required for successful performance of the standard TOL. Symptomatic HIV-seropositive participants solved significantly fewer TOL-WM problems compared to matched seronegative controls. However, seropositive and seronegative subjects showed similar overall levels of planning efficiency, suggesting that the TOL-WM deficit may be associated primarily with failure to encode or maintain an adequate online memory representation. The results of this study confirm our previous report of a possible working memory deficit in HIV-1 infection and suggest that measures of working memory have particular utility in the evaluation of HIV-related cognitive deficits.

Adult↗

PubMed1995

Delayed recognition memory span in HIV-1 infection.

We administered a spatial version of the Delayed Recognition Span Test (DRST), a working memory task performed abnormally by patients with basal ganglia disease, to a group of 96 HIV-seropositive and 83 seronegative subjects with a high prevalence of substance abuse. For comparison purposes, we also administered the Symbol-Digit Modalities Test (SDMT) and the Trail Making Test (TMT), measures which detect HIV-related mental slowing efficiently in gay men but are nonspecifically impaired in subjects with a history of substance abuse. As predicted, scores on the TMT and the SDMT did not discriminate the groups, but HIV-seropositive subjects had significantly shorter spatial spans (p < .007) and DRST total scores (p < .005). These effects could not be attributed to differences in age, education, estimated intelligence, or psychological distress, because the groups were well matched on these variables. The DRST is a promising measure of HIV-related cognitive dysfunction in substance abusers, who are often nonspecifically impaired on psychomotor tasks. These preliminary data also indicate that working memory function should be studied further in HIV-seropositive subjects.

AIDS Dementia Complex↗

PubMed1995

Human immunodeficiency virus and Mycobacterium avium complex coinfection of monocytoid cells results in reciprocal enhancement of multiplication.

Disseminated Mycobacterium avium complex (MAC) infection is an important opportunistic infection in AIDS patients. Because cells of macrophage lineage are targets for both human immunodeficiency virus (HIV) and MAC, the monocytoid cell line U937 was coinfected with both pathogens. Coinfected cultures had increased HIV replication (more than threefold at day 6) and an increased percentage of HIV-infected cells compared with cultures infected only with HIV. The kinetics of HIV replication were significantly increased in this coinfection system as measured by flow cytometry. When cells were infected concurrently, the rate of intracellular growth of MAC was not significantly affected. However, cells preinfected with HIV before infection with MAC showed significant enhancement of MAC growth compared with control cells. The kinetics of cell death were also increased in the coinfection system compared with singly infected controls. Thus, coinfection of monocytoid cells with HIV and MAC in vitro results in reciprocal enhancement of multiplication.

Cell Survival↗

PubMed1993

Antiviral phospholipids. Anti-HIV drugs conjugated to the glycerobackbone of phospholipids.

Heteroatom fatty acid analogs of myristic acid containing oxygen or sulfur substituted for the alkyl methylene groups inhibit replication of the human immunodeficiency virus (HIV) in infected cells by acting as alternative substrates during the viral protein myristoylation event. In this class of compounds, 12-methoxydodecanoic acid is the most potent compound but is approximately 10(3)-fold less active than azidothymidine. The antiviral activity of 12-methoxydodecanoic acid can be enhanced > 40-fold by preparing L-alpha-phosphatidylethanolamine containing 12-methoxydodecanoic acid in both alkyl chains. In addition, the diacylated L-alpha-phosphatidylcholine analog containing 12-methoxydodecanoic acid in both alkyl chains (i) has a 15-fold better antiviral selectivity, (ii) is 7-fold more potent, and (iii) is 10-100-fold more synergistic with azidothymidine than 12-methoxydodecanoic acid. Because of potent synergism, the antiviral selectivity of the diacylated L-alpha-phosphatidylcholine analog is > 10(4) when coadministered with azidothymidine. Phospholipid conjugates are chiral at the C-2 carbon of the glycerol backbone and most interesting is the observation that both the D- and L-isomers of phosphatidylcholine, phosphatidylglycerol, phosphatidic acid, and phosphatidylserine have approximately equal antiviral activity. Phospholipase A2 stereospecifically hydrolyzes only the L isomer of phospholipids and similar activity for both the D- and L- phospholipid isomers suggests that phospholipase A2 is not the rate-limiting enzyme for release of the drugs in vivo.

Antiviral Agents↗

PubMed1993

Negative images of mycobacteria in aspiration biopsy smears from the lymph node of a patient with acquired immunodeficiency syndrome (AIDS): report of a case and a review of the literature.

Negative images of acid-fast bacilli were observed in Diff-Quik-stained smears of lymph node aspirates from a patient with acquired immunodeficiency syndrome (AIDS) and disseminated Mycobacterium avium-intracellulare infection. The significance of this finding in relation to the diagnosis and treatment of this infection is discussed and the literature pertaining to this observation is reviewed.

Acquired Immunodeficiency Syndrome↗

PubMed1993

Human neutrophil oxidative response and phagocytic killing of clinical and laboratory strains of Enterococcus faecalis.

Many clinical isolates of Enterococcus faecalis produce a hemolysin/bacteriocin that is plasmid mediated. Recent human epidemiologic studies and animal research suggest that this hemolysin/bacteriocin may enhance the pathogenicity of hemolysin-producing enterococci compared with non-hemolysin-producing strains. These studies determined that clinical strains that produce hemolysin/bacteriocin differed from non-hemolysin-producing clinical and laboratory strains in their ability to induce the production of reactive oxygen intermediates in human peripheral blood neutrophils and in their susceptibility to phagocytic killing in vitro. The induction of superoxide anion generation by neutrophils was demonstrated to be directly proportional to the presence of the hemolysin/bacteriocin plasmid and was transferable to a non-hemolysin-producing laboratory strain by transconjugation. The presence of the plasmid, however, did not effect killing by phagocytic cells in vitro. It is proposed that hemolysin/bacteriocin-producing strains of enterococcus may be more pathogenic due to reactive oxygen product-induced tissue injury in vitro.

Conjugation, Genetic↗

PubMed1993

Depressed neutrophil superoxide production in human immunodeficiency virus infection.

Neutrophil (PMNL) superoxide (O2-) production was evaluated in 71 patients with human immunodeficiency virus (HIV) infection at different stages of disease. In vitro O2- production was significantly depressed for PMNL isolated from HIV-positive patients compared with control PMNL at rest and after stimulation. The degree of impairment of O2- production was more pronounced for patients with lower absolute CD4+ lymphocyte counts. Antiretroviral therapy with zidovudine was also associated with impaired O2- production, but this may reflect a longer duration of disease for treated patients. Zidovudine had no direct inhibitory effect on O2- production by control PMNL in vitro, and serial measurements of O2- production by PMNL from patients before and after initiation of zidovudine did not demonstrate an in vivo inhibitory effect. Impaired PMNL oxidative metabolism in HIV infection may contribute to the increased risk of serious bacterial infections, certain opportunistic infections, and perhaps the pathogenesis of HIV infection itself.

Adult↗

PubMed1993

Frequency of cells positive for HIV-1 p24 antigen assessed by flow cytometry.

OBJECTIVE: Markers of HIV disease progression such as soluble p24 antigen detection and CD4 lymphocyte depletion are most useful in the later stages of HIV disease and are relatively insensitive as therapeutic monitors. Flow cytometric detection of HIV-1 replication in CD4 lymphocytes was evaluated for use as a marker in predicting disease progression earlier in the course of HIV disease. DESIGN: To determine whether the number of HIV-1-infected CD4 cells, as measured by p24 antigen detection, can be correlated with disease progression, we used flow cytometry to detect intracellular HIV-1 p24 in CD4 lymphocytes from HIV-1-seropositive subjects at all stages of HIV disease. METHODS: Mononuclear cells from HIV-1-seropositive subjects and uninfected control subjects were permeabilized and stained with anti-HIV-1 p24 monoclonal antibodies. The cells were then stained with a fluorescein isothiocyanate-conjugated goat antimurine immunoglobulin G followed by a phycoerythrin-conjugated monoclonal anti-CD4 antibody. The percentage of p24-positive CD4 lymphocytes was compared with absolute CD4 counts, soluble p24 detection and Walter Reed classification. RESULTS: CD4 lymphocyte absolute counts and the percentage of CD4 lymphocytes declined as the Walter Reed classification indicated disease progression. The mean percentage of p24 antigen-positive CD4 lymphocytes increased with disease progression. Only 30% of Walter Reed stage 6 subjects were soluble p24 antigen-positive, whereas 68% were cellular p24 antigen-positive. CONCLUSION: The percentage of p24 antigen-positive CD4 lymphocytes increased as HIV disease progressed. Flow cytometric quantitation of p24 antigen-positive CD4 cells is a useful method of monitoring in vivo HIV replication and disease progression.

Biomarkers↗

PubMed1993

Treatment of cryptosporidial diarrhea in an AIDS patient with paromomycin.

OBJECTIVE: To report a case of diarrhea caused by Cryptosporidium in an AIDS patients which was successfully treated with paromomycin. CASE SUMMARY: An AIDS patient with a 12-month history of cryptosporidial diarrhea unresponsive to other treatment measures was treated with paromomycin 500 mg q6h for 14 days. Before initiating therapy, the patient was experiencing, on average, 20 bowel movements per day and had lost more than 25 kg. After therapy was initiated, the number of bowel movements dropped to 1-2 per day and the patient began to gain weight. The diarrhea recurred when therapy was discontinued. After retreatment for 14 days with paromomycin 500 mg q6h, the diarrhea stopped. The patient has not had a recurrence of Cryptosporidium diarrhea, stool cultures remain negative for Cryptosporidium oocysts, and the patient has regained most of the weight. DISCUSSION: Literature concerning the use of paromomycin for the treatment of cryptosporidiosis is discussed. A treatment algorithm for the management of cryptosporidiosis in AIDS patients is presented. CONCLUSIONS: We believe that we have presented a clear example of a case in which paromomycin was effective in treating and eradicating intestinal cryptosporidiosis in an AIDS patient. Paromomycin is the most effective agent available to date for the treatment of this devastating complication of AIDS.

AIDS-Related Opportunistic Infections↗

PubMed1990

The effect of interleukin 4 (BSF-1) on infection of peripheral blood monocyte-derived macrophages with HIV-1.

The effects of various cytokines were examined in an in vitro model of human immunodeficiency virus type 1 (HIV-1) infection of human peripheral blood monocyte-derived macrophages (MDM). Monocytes were obtained from blood of normal donors by Ficoll/hypaque gradient centrifugation and adherence. These cells were allowed to mature in the presence of varying concentrations of cytokines. After five days in culture, cells were harvested, counted, and inoculated with S5G7, an HTLV-IIIB subclone. The cells were replated in the presence of the same concentrations of cytokines. Culture supernatants were sampled over 28 days for p24 antigen (Ag) as measured by Ag capture assay. In repeat experiments, the following observations were made: 1. MDM from some donors could be infected only in the presence of tumor necrosis factor-alpha (TNF-alpha), granulocyte/macrophage colony-stimulating factor (GM-CSF) or interleukin 4 (IL-4); 2. The effect of GM-CSF was variable; TNF alpha also enhanced HIV replication above controls; 3. IL-4 was the most potent enhancer of HIV-1 replication in MDM of the cytokines tested, inducing p24 Ag levels 75-230 times those seen in control cultures run simultaneously. This effect was dose dependent. Ag production was not observed until Day 14 postinfection in most experiments. Multinucleated giant cell formation was observed only in the presence of IL-4.

Acquired Immunodeficiency Syndrome↗