Polio vaccine samples not linked to AIDS.
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Acquired Immunodeficiency Syndrome↗
Biomedical subjects
S Kwok
Publications and source records attributed to S Kwok.
The comparative impact of video-consultation on neurosurgical health services.
This study evaluated the impact of telemedicine technology on the provision of neurosurgical health services. We focused on the differences between the use of real time audio-visual teleconferencing and teleradiology versus conventional telephone consultations in the referral of neurosurgical patients from a large district general hospital. All patients requiring emergency neurosurgical consultation were included for randomization into telephone consultation only (Mode A), teleradiology and telephone consultation (Mode B) and video-consultation (Mode C). Measures of effectiveness included diagnostic accuracy and adverse events during the transfer and Glasgow Outcome Score. In a 10-month period, 327 patients were recruited and randomized into the study: the male/female ratio was 2:1 and the number of patients required to be transferred to the neurosurgical unit was 125 (38%). There was a trend towards a more favourable outcome in the video-consultation mode (44%, Mode C), versus teleradiology (31%, Mode B), versus telephone consultation (38%, Mode A). The interim data of this prospective randomized trial suggests that video-consultation may have a favourable impact on emergency neurosurgical consultations.
Emergencies↗
Plasma viral load in HIV-1 and HIV-2 singly and dually infected individuals in Guinea-Bissau, West Africa: significantly lower plasma virus set point in HIV-2 infection than in HIV-1 infection.
BACKGROUND: The intriguing differences in the natural course, transmissibility, and epidemiological characteristics of human immunodeficiency virus type 1 (HIV-1) and HIV-2 are still insufficiently explained. Differences in plasma viral load are an obvious possibility, but this has been difficult to investigate because of the lack of tests for HIV-2 RNA. OBJECTIVE: To compare plasma HIV RNA load between individuals infected with HIV-1 and HIV-2 in Guinea-Bissau, a West African country with high prevalence and incidence of HIV-1 and HIV-2 infection. METHODS: A total of 102 participants were recruited from ongoing prospective cohort studies. These included 19 HIV-1 and 29 HIV-2 seroincident cases tested at a median of less than 2 years after seroconversion as well as seroprevalent cases with single (9 HIV-1 cases and 31 HIV-2 cases) or dual (n = 14) infections. Plasma HIV RNA levels were determined by a commercial HIV-1 assay and an experimental HIV-2 assay based on the same principles. RESULTS: The viral set point, ie, the semi-equilibrium reached after seronconversion, was 28-fold lower in recent HIV-2 seroconverters than in recent HIV-1 seroconverters (median, 2500 and 70,000 RNA copies per milliliter, respectively; P<. 001). This difference appeared to persist to symptomatic stages of the diseases. Dually infected individuals had lower plasma HIV-1 RNA levels than singly infected individuals. CONCLUSIONS: The differences between HIV-1 and HIV-2 infection are likely to be caused by differences in plasma viral set point and load, but the mechanisms through which HIV-2 infection is contained to a higher degree than HIV-1 remain to be identified. Arch Intern Med. 2000;160:3286-3293.
Acquired Immunodeficiency Syndrome↗
Dissociation of immunologic and virologic responses to highly active antiretroviral therapy.
OBJECTIVE: Immunologic markers, levels of HIV DNA, and infectious HIV were compared in partial responders (PR) to HAART who had high plasma HIV RNA levels but stable or increasing levels of CD4+ peripheral blood mononuclear cells (PBMC), and patients with complete failure (CF) who had very low or decreasing levels of CD4+ PBMC and high plasma HIV RNA levels. DESIGN AND METHODS: CD4 and CD8 levels were monitored by flow cytometry. Beta2-microglobulin (beta2M) and neopterin levels were measured by quantitative enzyme immunoassays. Plasma and PBMC from 11 PR and 13 CF were analyzed for infectious HIV levels in limiting dilution cultures. Polymerase chain reaction (PCR) assays were used to quantify cellular HIV DNA and plasma HIV RNA. RESULTS: In comparison with CF, PR had little or no CD4+ cell loss, a substantial increase in CD8+ cells, significantly fewer positive plasma HIV cultures (p = .03), lower frequencies of infectious HIV in total PBMC (p = .005) and in CD4+ PBMC (p < .001), and lower frequencies of HIV DNA in CD4+ PBMC (p = .007). CONCLUSIONS: Lower levels of infectious HIV and a lower frequency of CD4+ PBMC that contain "productive" HIV DNA in PR as compared with CF may contribute to the stable or increasing CD4+ PBMC levels of the PR. However, HAART may also have effects on lymphocyte homeostasis independent of its antiviral activity.
Anti-HIV Agents↗
Effect of influenza vaccination on viral replication and immune response in persons infected with human immunodeficiency virus receiving potent antiretroviral therapy.
Nineteen patients infected with human immunodeficiency virus (HIV) with varying levels of viral suppression achieved with antiretroviral therapy were evaluated to determine whether trivalent influenza vaccine activated HIV replication. Humoral immune responses and CD4+ lymphocyte subsets were compared in 5 HIV-uninfected vaccinated subjects. Transient elevations of plasma HIV RNA levels (76-89 copies/mL) appeared within 2 weeks in 3 of 11 patients with <50 copies/mL at baseline. Sustained elevation in HIV plasma RNA was observed in 7 of 8 patients with baseline HIV RNA of >50 copies/mL. HIV DNA decreased in patients with <400 RNA copies/mL at baseline and showed an HIV RNA increase after vaccination (n=8) when compared with 8 patients with <50 copies/mL at baseline who lacked viral response to vaccination. Concurrent decreases in proviral DNA and memory phenotype CD4+ cells in association with increased plasma HIV RNA after vaccination in patients with <400 RNA copies/mL at baseline suggest that in vivo mobilization of the latently infected cell reservoir may occur during potent antiretroviral therapy.
Adult↗
PCR-Based assay to quantify human immunodeficiency virus type 1 DNA in peripheral blood mononuclear cells.
An assay that quantifies the amount of human immunodeficiency virus type 1 (HIV-1) DNA in peripheral blood mononuclear cells has been developed. PCR amplification of the HIV-1 DNA is performed in the presence of an internal quantitation standard, and colorimetric detection of the amplified product is performed with microwell plates. The copies of HIV-1 DNA are normalized to total genomic DNA input. The assay has an analytical sensitivity of 10 input copies per amplification reaction and a three-log detection range. In an analysis of sequential samples from patients on combination therapy, HIV-1 DNA was quantifiable for all individuals tested, including those with undetectable plasma HIV-1 RNA. In a separate study, a comparison of HIV-1 DNA levels was made with a group of long-term survivors and progressors. The mean HIV-1 DNA levels were lower in the long-term survivors than in the progressors (P, 0.04). The mean HIV-1 RNA levels were also lower, but the difference was not statistically significant (P, 0.164). A quantitative DNA assay will provide an additional tool to gain insight into the natural history of infection and the continued efficacy of potent antiretroviral therapies.
Anti-HIV Agents↗
Suppression of lymphocyte mitogenesis by tamoxifen: studies on protein kinase C, calmodulin and calcium.
The effect of tamoxifen (TX; 1.0 microM) on the mitogenic response of rat lymphocytes was compared with the effect of drugs that are known to act on protein kinase C (PKC), calmodulin (CM), and calcium (Ca(2+)). The calcium ionophore A23187 (0.2 microM) was mitogenic on its own which was not influenced by TX. The agents modulating PKC or CM (phorbol-myristate-13-acetate; R24571, chlorpromazine) influenced mitogenesis differently than did TX. General inhibition of lymphocyte proliferation was seen with the Ca(2+) antagonist agents (EGTA, TMB-8) as with TX. The antiproliferative effect of TX was partially reversed by the increase of Ca(2+) in the culture medium when T cell mitogens were used, but not in the case of lipid A, a B lymphocyte mitogen. However, the concanavalin A-induced Ca(2+) influx was further elevated by TX which differed from the effect of the Ca(2+) channel-blocking agent verapamil. The results suggest that TX resets the threshold stimulus necessary for mitogenesis and is completely reversible.
Animals↗
HIV mediates a productive infection of the brain.
BACKGROUND: Approximately one quarter of patients with AIDS develop severe cognitive deficits called HIV-associated dementia complex. There is some controversy regarding the importance of viral load and distribution in mediating this neurologic disease. OBJECTIVE: Brain HIV proviral and RNA loads were compared to define the molecular nature of HIV infection of the brain. METHOD: Neuropathologic examination was performed on brains from 10 autopsies of patients with AIDS that had short post-mortem intervals and no evidence of opportunistic infection. Viral DNA and RNA were extracted and quantified from multiple brain regions. These findings were compared with triple-label immunofluorescence for viral and cell markers. RESULTS: Brains with histopathologic evidence of HIV encephalitis contained abundant HIV RNA and DNA. Regions without productive HIV infection showed minimal proviral load. By immunocytochemistry, only brain macrophages/microglia double labeled for viral proteins. CONCLUSIONS: HIV mediates a productive infection of brain macrophages/microglia. There was no evidence supporting the hypothesis of substantial neuronal or macroglial infection, or evidence of substantial proviral burden prior to the development of productive infection.
AIDS Dementia Complex↗
Human immunodeficiency virus type 1-specific cytotoxic T lymphocyte activity is inversely correlated with HIV type 1 viral load in HIV type 1-infected long-term survivors.
HIV-1-specific cytotoxic T cell (CTL) activity has been suggested to correlate with protection from progression to AIDS. We have examined the relationship between HIV-specific CTL activity and maintenance of peripheral blood CD4+ T lymphocyte counts and control of viral load in 17 long-term survivors (LTSs) of HIV-1 infection. Longitudinal analysis indicated that the LTS cohort demonstrated a decreased rate of CD4+ T cell loss (18 cells/mm3/year) compared with typical normal progressors (approximately 60 cells/mm3/year). The majority of the LTSs had detectable, variable, and in some individuals, quite high (>10(4) RNA copies/ml) plasma viral load during the study period. In a cross-sectional analysis, HIV-specific CTL activity to HIV Gag, Pol, and Env proteins was detectable in all 17 LTSs. Simultaneous analysis of HIV-1 Gag-Pol, and Env-specific CTLs and virus load in protease inhibitor-naive individuals showed a significant inverse correlation between Pol-specific CTL activity and plasma HIV-1 RNA levels (p = 0.001). Furthermore, using a mixed linear effects model the combined effects of HIV-1 Pol- and Env-specific CTL activity on the viral load were significantly stronger than the effects of HIV-1 Pol-specific CTL activity alone on predicted virus load. These data suggest that the presence of HIV-1-specific CTL activity in HIV-1-infected long-term survivors is an important component in the effective control of HIV-1 replication.
CD4 Lymphocyte Count↗
Arabidopsis cop8 and fus4 mutations define the same gene that encodes subunit 4 of the COP9 signalosome.
The pleiotropic constitutive photomorphogenic/deetiolated/fusca (cop/det/fus) mutants of Arabidopsis exhibit features of light-grown seedlings when grown in the dark. Cloning and biochemical analysis of COP9 have revealed that it is a component of a multiprotein complex, the COP9 signalosome (previously known as the COP9 complex). Here, we compare the immunoaffinity and the biochemical purification of the COP9 signalosome from cauliflower and confirm its eight-subunit composition. Molecular cloning of subunit 4 of the complex revealed that it is a proteasome-COP9 complex-eIF3 domain protein encoded by a gene that maps to chromosome 5, near the chromosomal location of the cop8 and fus4 mutations. Genetic complementation tests showed that the cop8 and fus4 mutations define the same locus, now designated as COP8. Molecular analysis of the subunit 4-encoding gene in both cop8 and fus4 mutants identified specific molecular lesions, and overexpression of the subunit 4 cDNA in a cop8 mutant background resulted in complete rescue of the mutant phenotype. Thus, we conclude that COP8 encodes subunit 4 of the COP9 signalosome. Examination of possible molecular interactions by using the yeast two-hybrid assay indicated that COP8 is capable of strong self-association as well as interaction with COP9, FUS6/COP11, FUS5, and Arabidopsis JAB1 homolog 1, the latter four proteins being previously defined subunits of the Arabidopsis COP9 signalosome. A comparative sequence analysis indicated that COP8 is highly conserved among multicellular eukaryotes and is also similar to a subunit of the 19S regulatory particle of the 26S proteasome.
Alleles↗
Development of calibrated viral load standards for group M subtypes of human immunodeficiency virus type 1 and performance of an improved AMPLICOR HIV-1 MONITOR test with isolates of diverse subtypes.
Accurate determination of plasma human immunodeficiency virus type 1 (HIV-1) RNA levels is critical for the effective management of HIV-1 disease. The AMPLICOR HIV-1 MONITOR Test, a reverse transcription-PCR-based test for quantification of HIV-1 RNA in plasma, was developed when little sequence information on HIV-1 isolates from outside North America was available. It has since become apparent that many non-subtype B isolates, particularly subtypes A and E, are detected inefficiently by the test. We describe here the AMPLICOR HIV-1 MONITOR Test, version 1.5, an upgraded test developed to minimize subtype-related variation. We also developed a panel of HIV-1 standards containing 30 HIV-1 isolates of subtypes A through G. The virus particle concentration of each cultured viral stock was standardized by electron microscopic virus particle counting. We used this panel to determine the performance of the original AMPLICOR HIV-1 MONITOR Test and version 1.5 of the test with HIV-1 subtypes A through G. The original test underestimated the concentration of HIV-1 subtype A, E, F, and G RNA by 10-fold or more, whereas version of the 1.5 test yielded equivalent quantification of HIV-1 RNA regardless of the subtype. In light of the increasing intermixing of HIV-1 subtypes worldwide, standardization of PCR-based tests against well-characterized viral isolates representing the full range of HIV-1 diversity will be essential for the continued utility of these important clinical management tools.
Acquired Immunodeficiency Syndrome↗
The Arabidopsis homologue of an eIF3 complex subunit associates with the COP9 complex.
The Arabidopsis COP9 complex is a multi-subunit repressor of photomorphogenesis which is conserved among multicellular organisms. Approximately 12 proteins copurify with the COP9 complex. Seven of these proteins are orthologues of subunits of the recently published mammalian COP9 complex. Four of the proteins show amino acid similarity to various subunits of the COP9 complex, eIF3 complex and 19S cap of the proteasome. We have studied one of these proteins in order to determine if it is a component of the COP9 complex. Arabidopsis p105 is highly similar to the p110 subunit of the human elF3. The p105 gene is induced during photomorphogenesis, and RNA and protein analysis reveal different tissue accumulation patterns. p105 is found in a large protein complex. p105 interacts in yeast with both COP9 and FUS6, two known components of the COP9 complex. Our results indicate that p105 is not a component of the COP9 core complex, though it may interact with components of the complex.
Amino Acid Sequence↗
Early prognostic indicators in primary perinatal human immunodeficiency virus type 1 infection: importance of viral RNA and the timing of transmission on long-term outcome.
The time of perinatal human immunodeficiency virus type 1 (HIV-1) transmission and the pattern of early plasma viremia as predictors of disease progression were evaluated in infected infants followed from birth. Cox proportional hazards modeling demonstrated that a 1-log higher HIV-1 RNA copy number at birth was associated with a 40% increase in the relative hazard (RH) of developing CDC class A or B symptoms (P = .004), a 60% increase in developing AIDS (P = .01), and an 80% increase in the of risk death (P = .023) over the follow-up period of up to 8 years. The peak HIV-1 RNA copy number for infants during primary viremia was also predictive of progression to AIDS (RH, 9.9; 95% confidence interval [95% CI], 1.8-54.1; P = .008) and death (RH, 6.9; 95% CI, 1.1-43.8; P = .04). The results indicate that high levels of HIV-1 RNA at birth and during primary viremia are associated with early onset of symptoms and rapid disease progression to AIDS and death in perinatally infected children.
Acquired Immunodeficiency Syndrome↗
Laboratory markers of antiviral activity.
Quantitative assays for viral nucleic acids have been instrumental in monitoring the response of patients to various antiviral therapies. The level of viraemia is predictive of clinical outcome in that a reduced risk of progression to AIDS or death was observed with lower plasma human immunodeficiency virus (HIV) RNA levels. Rebound in viral levels often signals therapeutic failures, some of which are associated with the development of drug resistance. Quantitative plasma assays for HIV, hepatitis C virus (HCV), cytomegalovirus (CMV) and hepatitis B virus (HBV) have been developed. Over time, modifications to these assays have been required to meet new demands. For example, as antiviral therapies have become more effective, HIV and HCV assays of greater sensitivity are required in order to follow patients for longer periods of time and to fully assess the extent of viral suppression. For HIV-1, a large percentage of patients treated with combination therapies had viral loads that were below the detection limit of the ultrasensitive assay (50 copies/ml). To assess the residual viral burden in this patient population an assay to quantify HIV-1 proviral DNA in peripheral blood mononuclear cells was developed. Studies to date indicate that proviral DNA remains easily detectable despite undetectable plasma RNA and may be useful in monitoring this patient population. To increase assay throughput, a new generation of quantitative assays that will provide real-time detection and a 6 log10 detection range from a single amplification is under development.
Antiviral Agents↗
Reduction of HIV-1 in blood and lymph nodes following potent antiretroviral therapy and the virologic correlates of treatment failure.
Potent antiretroviral therapy can reduce plasma HIV RNA levels below the threshold of detection for periods of a year or more. The magnitude of HIV RNA reduction in the lymphoid tissue in patients with suppression of HIV RNA levels in plasma beyond 6 months has not been determined. We evaluated levels of HIV RNA and DNA and characterized resistance mutations in blood and inguinal lymph node biopsies obtained from 10 HIV-infected subjects who received 36-52 weeks of indinavir (IDV)/zidovudine (ZDV)/lamivudine (3TC), IDV, or ZDV/3TC. After 1 year of therapy, viral RNA levels in LN of individuals remained detectable but were log10 = 4 lower than in subjects on the triple drug regimen with interruption of therapy or in those treated with ZDV/3TC alone, who had viral loads in their lymph nodes indistinguishable from those expected for untreated patients. In all cases viral DNA remained detectable in lymph nodes and peripheral blood mononuclear cells (PBMC). When plasma virus suppression was incomplete, lymph node and PBMC cultures were positive and drug resistance developed. These studies indicate that pronounced and sustained suppression of plasma viremia by a potent antiretroviral combination is associated with low HIV RNA levels in the lymph nodes 1 year after treatment. Conversely, the persistence of even modest levels of plasma virus after 1 year of treatment reflects ongoing viral replication, the emergence of drug resistance, and the maintenance of high burdens of virus in the lymph nodes.
Anti-HIV Agents↗
The effects of internal primer-template mismatches on RT-PCR: HIV-1 model studies.
We investigated the effects of internal primer-template mismatches on the efficiency of reverse transcription and PCR amplification. As models, RNA transcripts representative of different HIV-1 group M subtypes were evaluated with a previously described gag primer pair system. We observed that the presence of two to four mismatches in the primer-template duplexes did not have a significant effect on RT-PCR. However, the presence of five and six mismatches with the 28 and 30 base primers reduced PCR product yield by approximately 22- and 100-fold respectively, relative to the homologous template. The amount of reduction was reproducible from experiment to experiment and was independent of the initial copy number input. Under the conditions used, viral RNA measurements of the more divergent HIV-1 subtypes (A and E) would be underestimated, while isolates of subtypes B, C, D and F-H are expected to be efficiently amplified and accurately measured. The reduced amplification efficiency for targets similar to HIV subtypes A and E can be improved 4- to 10-fold by lowering the annealing temperature and implementing a reverse transcription step that gradually increases in temperature. The additional substitution of either 5-methylcytosine for cytosine throughout or the substitution of inosine at positions of variable bases resulted in a <4-fold difference in product yield between the homologous and most divergent templates.
DNA Primers↗
Dietary regulation of the very low density lipoprotein receptor in mouse heart and fat.
The very low density lipoprotein (VLDL) receptor is a member of the LDL receptor family. As opposed to the LDL receptor, the VLDL receptor is expressed primarily in muscle and adipose tissue. Although the VLDL receptor is capable of binding lipoproteins, its functional role is still unclear. Previous studies found that VLDL receptor expression is unaffected by fasting in the rat. The current studies examined whether VLDL receptor expression is altered with fasting in the mouse. Balb/c mice were fasted for periods up to 48 hours, killed, hearts and epididymal fat obtained, and total membranes prepared. To detect the VLDL receptor a portion of the rat VLDL receptor was expressed as a bacterial fusion protein, purified and used to immunize rabbits. The antibodies raised specifically recognized intact VLDL receptor. When cardiac membranes were immunoblotted, VLDL receptor expression increased progressively with fasting, doubling at 36 hours. In contrast, VLDL receptor expression decreased progressively with fasting in membranes from epididymal fat, being reduced 70% by 48 hours. Thus, VLDL receptor expression appears to be regulated in mouse heart and fat by nutritional perturbation, supporting a potential role for the VLDL receptor in the delivery of triglycerides/fatty acids as fuel.
Adipose Tissue↗
A rapid and simple method for extracting human immunodeficiency virus type 1 RNA from plasma: enhanced sensitivity.
We present here a rapid and simple technique for processing human immunodeficiency virus (HIV)-infected plasma by high-speed centrifugation. HIV type 1 virions are pelleted from up to 1 ml of plasma, gently lysed with a nonionic detergent, and directly amplified. The procedure has few manipulations and requires approximately 1.5 h for the processing of 24 samples. Viral recovery ranges from 80 to 90%, with an analytical sensitivity approaching 20 copies/ml.
HIV Infections↗