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Biomedical subjects

David A Cooper

Publications and source records attributed to David A Cooper.

At least 19 recordsLinked to original sources
PubMed2003

Polyclonal proliferation and apoptosis of CCR5+ T lymphocytes during primary human immunodeficiency virus type 1 infection: regulation by interleukin (IL)-2, IL-15, and Bcl-2.

We measured apoptosis of subsets of T lymphocytes by single-cell analysis of caspase activation, to confirm high turnover of chemokine receptor CCR5(+) T cells in subjects with acute, primary human immunodeficiency virus type 1 (HIV-1) infection (PHI). High levels of spontaneous apoptosis, consisting mainly of CD8(+) T lymphocytes, were closely associated with increases in the activation markers Ki-67, CD38, and the HIV coreceptor CCR5 and with decreases in Bcl-2 and the interleukin (IL)-7 receptor at the single-cell level. Increased expression of Ki-67 and CCR5 ex vivo, as well as increased apoptosis, was seen in all T cell receptor beta-chain variable region (TCRBV) subfamilies studied. The addition of IL-2 or IL-15, but not IL-7, significantly inhibited caspase activation, increased Bcl-2 expression, and rapidly initiated proliferation in vitro of CD8(+) T cells expressing CCR5 and multiple TCRBV subfamilies. Furthermore, IL-15 receptor alpha-chain messenger RNA levels were increased in peripheral blood mononuclear cells during PHI. These results suggest that CCR5(+)Ki-67(+)Bcl-2(dim) activated T cells generated during PHI traffic via blood to tissue sites, where the cells may survive and/or further proliferate under the local influence of IL-2 or IL-15. Understanding cytokine effects on CCR5(+) T cells will be important in understanding chronic HIV-1 replication and pathogenesis.

Adult↗
PubMed2003

Prospective evaluation of the effects of antiretroviral therapy on body composition in HIV-1-infected men starting therapy.

OBJECTIVE: Little prospective data are published on the natural history of HIV-associated lipodystrophy (HIVLD) in individuals beginning their first antiretroviral regimen. To investigate this a study was designed to explore changes in body composition occurring with antiretroviral therapy. STUDY DESIGN: A non-randomized, prospective, exploratory study of 40, HIV-infected men, naive to treatment, beginning antiretroviral therapy. Regular assessments of body composition, and metabolic and immunological parameters were performed. RESULTS: Mean follow-up was 96 (SD 45) weeks of therapy. There were increases in limb fat, central abdominal fat and lean mass over the initial 24 weeks of therapy followed by a selective, progressive loss of limb fat from week 24. There was a median 13.6% [interquartile range (IQR), 0.9-26.3] loss of limb fat per year from week 24 onwards. Treatment with stavudine, higher baseline HIV RNA, higher baseline 'T' score and lower week 24 lean mass were associated with higher rate of limb fat loss from week 24. In multivariate analysis, treatment with stavudine was the strongest independent factor associated with rate of limb fat loss (P = 0.05). Hypercholesterolaemia developed early in treatment, whereas hypertriglyceridaemia, hyperinsulinaemia and decreased bone mineral density developed later. The largest changes in CD4 cell counts and HIV viral load, seen early into treatment, were associated with gain rather than loss of fat. CONCLUSIONS: This is the first prospective study demonstrating that treatment with antiretrovirals results in progressive, selective loss of limb fat. Loss of limb fat occurred after the period of most intense immune restoration, making an immune aetiology unlikely.

Adipose Tissue↗
PubMed2003

Brief report: incubation and duration of specific symptoms at acute retroviral syndrome as independent predictors of progression to AIDS.

The incubation and duration of acute retroviral syndrome (ARS) have been associated with progression to AIDS. We assessed the independent effect of specific symptoms at ARS on the rate of progression to AIDS or a CD4+ count of <200 cells/mm3 in 70 ARS patients. The incubation and duration of ARS features were stratified on their medians. The Cox regression model was used to calculate the adjusted relative hazard (ARH) of progression. Short incubations of fever (ARH = 5.8, P = 0.004), fatigue (ARH = 2.7, P = 0.06), and myalgia (ARH = 3.8, P = 0.04) were associated with faster disease progression, as was the long duration of most symptoms (ARH range: 3.1-8.1, P < 0.03 to P < 0.001). Pathogenetic mechanisms involved in the incubation of ARS features may be associated with progression to AIDS.

Acute Disease↗
PubMed2003

Pharmacokinetics of once-daily saquinavir hard-gelatin capsules and saquinavir soft-gelatin capsules boosted with ritonavir in HIV-1-infected subjects.

OBJECTIVE: To investigate the pharmacokinetics of once-daily saquinavir (SQV) hard-gelatin capsule (HGC)/ritonavir (RTV), 1600/100 mg, compared with once-daily SQV soft-gelatin capsule (SGC)/RTV, 1600/100 mg. METHODS: We evaluated 13 randomly selected HIV-1-infected subjects taking once-daily SQV SGC/RTV, 1600/100 mg, plus dual nucleoside reverse transcriptase inhibitors (NRTIs) in this pharmacokinetic (PK) substudy. Subjects took 1 week of SQV HGC/RTV and NRTIs, followed by steady-state SQV PK determinations. Subjects then changed to SQV SGC/RTV and NRTIs for 1 week, followed again by steady-state SQV PK determinations. Area under the plasma concentration versus time curve (AUC), maximum concentration (C(max)), minimum concentration (C(min)), time to C(max), and elimination half-life were calculated. RESULTS: There was no significant difference in AUC values between HGCs and SGCs, with a median (plus interquartile range [IQR]) of 50.0 (42.6-71.5) versus 35.5 (28.0-50.2) mg/L/h, respectively ( =.056). Intersubject variability resulted in 4 of 13 subjects on the SQV SGCs and 2 of 13 subjects on the SQV HGCs having a C(min) below the minimum effective concentration of 0.05 mg/L. CONCLUSION: Once-daily SQV HGCs, 1600 mg, boosted with once-daily RTV, 100 mg, resulted in PK parameters that were similar to those observed with 1600 mg of SQV SGC/100 mg RTV once daily. Once-daily SQV HGC/RTV, 1600/100 mg, may be easier to use in developing countries and may increase access where drug costs can be less, the capsule size is smaller, and the need for refrigeration is lessened.

Administration, Oral↗
PubMed2003

No increase in protease resistance and a decrease in reverse transcriptase resistance mutations in primary HIV-1 infection: 1992-2001.

Rates of antiretroviral resistance in recently transmitted virus in Sydney, Australia fluctuated over the past decade, influenced by treatment trends. Current rates of drug resistance are not high in historical terms or compared with those reported. Rates of resistance to reverse transcriptase inhibitors peaked in the mid-1990s, fell dramatically with the introduction of combination therapy and appear to have plateaued at 10-15% over the past 3 years. Primary resistance mutations in the protease gene are still rare.

Acute Disease↗
PubMed2003

Latest update of tests and improvements to US Coast Guard viscous oil pumping system.

Over the past nine years, the US Coast Guard has incorporated the prevention through people (PTP) philosophy as a "human factors" approach to learn how maritime operations can be regulated safer and be more efficient by evaluating training, management policies, operational procedures, and establishing partnerships with the maritime industry. One of the key elements of applying a PTP approach is identifying and incorporating lessons learned from major marine casualties and pollution incidents. Since 1997, the US Coast Guard National Strike Force has responded to three major oil spills involving foreign freight vessels grounding, which included the removal of highly viscous oil using various lightering equipment and systems. An informal workgroup consisting of the US Coast Guard, US Navy Supervisor of Salvage (NAVSUPSALV), and various representatives from oil pollution clean-up companies met at the following facilities: the Chevron Asphalt Facility in Edmonds, WA (September 1999), the Oil and Hazardous Materials Simulated Environmental Test Tank (OHMSETT) testing facility in Leonardo, New Jersey (November 1999 and March 2000), the Alaska Clean Seas (ACS) warehouse annex in Prudhoe Bay, AK (October 2000), and Cenac Towing Company facility in Houma, LA (May 2002). The group shared ideas and techniques, and tested different pumps and hose lengths with viscous oil. It was during the early tests that the first quantitative results showed just how efficient lubricated transport of heavy oil product could be, and broadened the knowledge of such methods to the entire industry. Although this technology had existed for many years in the oil production and handling industry, its use had never been investigated in a laboratory setting with regard to salvage response lightering systems.

Accidents↗
PubMed2003

Rates of transmission of antiretroviral drug resistant strains of HIV-1.

BACKGROUND: It is clear that transmission of drug resistant HIV-1 is possible and occurs regularly. However, there is a lack of clarity concerning the true rate of this transmission in a given population, the impact of combination therapies on this rate, and the contribution of transmitted resistant virus to treatment failure either in an individual or on a population basis. OBJECTIVES: To provide a review of our current understanding of rates of transmission of drug resistant HIV-1 in various populations and to report the results of a study conducted to determine this rate in Sydney, Australia in the years 1992-2000. STUDY DESIGN: A review of the literature combined with a prospective study of antiretroviral drug resistance in 130 individuals who were diagnosed with symptomatic primary infection at St. Vincent's Hospital, Sydney, Australia between 1992 and 2000. Sequencing of reverse transcriptase (RT) and protease (PR) was performed by the TruGene HIV-1 genotyping kit (Visible Genetics Inc.). RESULTS: The results found in the Sydney population contrast with much of the literature. The prevalence of mutations that conferred primary resistance to protease inhibitors (PIs) was only 0.8% at position V82I. Secondary mutations/polymorphisms were seen in the PR at position L10I/V, K20R, M36I, L63P, A71T/V, or V77I in 60%. L63P was the most frequently found mutation (46.3%). The incidence of protease-resistant strains of HIV in primary HIV-1 infection did not change after the introduction of PIs in 1996. The distribution of the most common resistance mutations in the RT was as follows; M41L (8.5%) and T215Y (8.5%) and K70R (4.8%). The frequency of mutations associated with NRTI resistance was significantly lower in the post 1995 samples (43.9 vs. 19.1%, P < 0.05). Moreover, both M41L and K70R, but not T215Y, occurred with significantly decreased frequency in the post 1995 samples. CONCLUSIONS: In contrast to other studies we found no increase in the rate of PR resistance and a decrease in the rate of RT resistance in recently transmitted virus over the period 1992-2000. The reasons for the differences between these results and those reported from elsewhere may relate to treatment regimens used in the transmitting population and may have implications for treatment policies in this country.

Anti-HIV Agents↗
PubMed2003

Effect of therapeutic drug monitoring on outcome in antiretroviral experienced HIV-infected individuals.

BACKGROUND: The role of therapeutic drug monitoring (TDM) in the routine management of HIV-infected individuals is still unclear, largely due to a lack of basic data regarding specific drug concentrations and how they correlate with maximal effect and minimal toxicity within given populations. Nevertheless, it has a potentially important role to play in the management of HIV-infected patients, with the aim of limiting toxicity, optimising antiviral effect and decreasing virological failure and emergence of viral resistance. OBJECTIVES: To measure serum concentrations of specific antiretroviral drugs in individuals changing antiretroviral therapy and assess relationship to virological response. STUDY DESIGN: A prospective, non-randomised, 24-week study of 40 antiretroviral experienced HIV-infected patients. Subjects had failed their previous antiretroviral regimen and were beginning new regimens based on genotypic testing. Serum antiretroviral concentrations and virological response was measured after initiation of treatment. RESULTS: There was a significant correlation between higher concentrations of lopinavir and efavirenz and better virological outcome. This was not seen with amprenavir. CONCLUSIONS: Use of TDM in this setting helps predict virological response to therapy. Optimal use of TDM would require dose adjustment on the basis of a TDM level. Further research is necessary to enable this practice to become routine in the management of HIV-infected patients.

Adult↗
PubMed2003

Greater reversal of CD4+ cell abnormalities and viral load reduction after initiation of antiretroviral therapy with zidovudine, lamivudine, and nelfinavir before complete HIV type 1 seroconversion.

In a prospective open-label study, 41 male subjects received nelfinavir, zidovudine, and lamivudine stratified as either: early stage (ES; negative/indeterminate Western blot; n = 19) or late stage (LS; positive Western blot; n = 22) primary HIV-1 infection. Despite higher median baseline HIV-1 RNA levels and lower CD4(+) cell numbers in the ES subjects, a significantly greater decline in viral load (-3.46 vs. -2.83 log(10) copies/ml; p = 0.023) and increase in CD4(+) cell number (+85 vs. +41 cells/month increase, p = 0.01) were observed over the first 3 months of therapy such that both groups had comparable results at 1 year. The proportion with HIV-1 RNA < 50 copies/mL at 1 year was similar (9 of 19 ES subjects and 11 of 22 LS subjects by intention-to-treat analysis). Memory CD4(+) cell numbers, and activated CD4(+) percentages, were also significantly improved in ES subjects. Despite poorer prognostic markers at baseline ES subjects achieved responses similar to those of LS subjects after 1 year of treatment.

Anti-HIV Agents↗
PubMed2003

Pharmacokinetics of lower doses of saquinavir soft-gel caps (800 and 1200 mg twice daily) boosted with itraconazole in HIV-1-positive patients.

OBJECTIVE: The pharmacokinetics of 800 mg and 1200 mg of saquinavir soft-gel caps (SQV-SGC) twice daily plus 100 mg itraconazole once daily were compared to 1400 mg SQV-SGC twice daily without itraconazole. METHODS: The pharmacokinetics of SQV were determined in 17 randomly selected patients on 1400 mg twice daily SQV-SGC without itraconazole and after 2 weeks with lower SQV-SGC doses plus itraconazole. SQV plasma concentrations were determined by HPLC. Pharmacokinetic parameters were calculated by a non-compartmental model. RESULTS: Median (+IQR) area under plasma concentration-versus-time curve (AUC0-12h) were 3.33 (1.96-7.34), 4.29 (3.14-7.67) and 4.07 (2.76-4.49) mg/l x h for SQV 1400 mg without itraconazole, SQV 1200 mg with itraconazole and SQV 800 mg with itraconazole, respectively. These differences were not statistically significant. The median Cmin was above the proposed minimum effective concentration of 0.05 mg/l for all three regimens. CONCLUSION: SQV-SGC 800 mg or 1200 mg twice daily boosted with 100 mg of itraconazole once daily resulted in adequate SQV pharmacokinetics not significantly different from SQV-SGC 1400 mg twice daily.

Adult↗
PubMed2002

Comprehensive analyses of a unique HIV-1-infected nonprogressor reveal a complex association of immunobiological mechanisms in the context of replication-incompetent infection.

We recently demonstrated that a unique HIV-1-infected nonprogressor was infected with a nonevolving replication-incompetent HIV-1 strain, showing a total absence of viral evolution in vivo. Potent immune responses against HIV-1 were observed in his PBMC, despite an apparent lack of viral replication for at least 8 years. His PBMC resisted superinfection with CCR5, CXCR4, and dual-tropic HIV-1 strains, although highly purified CD4+ T cells supported infection, but without any visible cytopathic effect. Potent noncytolytic CD8+ T cell antiviral activity was shown to protect his PBMC from productive infection. This activity was not mediated by several known chemokines or IFN-gamma, which were produced at high levels after PHA activation of his CD8+ T cells, indicating the action of other CAF-like CD8 factors. This antiviral activity was a memory response, induced by HIV-specific stimulation to similar levels observed by PHA stimulation, but absent in ex vivo resting T cells. Immunological mechanisms associated with this antiviral suppressive activity included vigorous Gag-specific helper T cell proliferative responses and high-level IFN-gamma release by both CD4 and CD8 T cells. These responses were broadly directed against multiple Gag epitopes, both previously reported and some novel epitopes. Strong HIV-specific helper T cell function was also associated with strong neutralizing antibodies. Understanding how to induce these protective immune responses in other individuals could provide a major step forward in the design of effective immunotherapies or vaccines against HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed2002

A randomized, double-blind study of gemfibrozil for the treatment of protease inhibitor-associated hypertriglyceridaemia.

BACKGROUND: Hypertriglyceridaemia is common in patients with HIV, especially those taking protease inhibitors or with lipodystrophy, frequently observed at levels associated with accelerated cardiac disease. This study aimed to explore the efficacy and safety of gemfibrozil for hypertriglyceridemia in patients with HIV infection. METHODS: A 16-week, randomized, double-blind, comparative study of low saturated fat diet versus low saturated fat diet with gemfibrozil 600 mg twice daily in patients with triglycerides > or = 3mmol/l receiving protease inhibitor therapy. Following a 4-week period of dietary intervention alone, patients were randomized to gemfibrozil or matching placebo. The primary outcome was the difference in mean change in fasting triglycerides at week 16 between the two groups. RESULTS: 37 men were randomized (17 gemfibrozil, 20 placebo) with median fasting triglycerides 5.6 mmol/l. Mean changes in triglycerides from week 4 to week 16 were -1.22 mmol/l and +0.35 mmol/l for the gemfibrozil and placebo groups respectively (between-group mean difference of 1.57 mmol/l; 95% confidence interval, -6.7 to 3.5; = 0.08). Only one patient treated had triglycerides return to a desirable range (< or = 2.00 mmol/l). No significant changes in the other metabolic parameters were observed. Gemfibrozil was well tolerated, did not appear to induce additional protease inhibitor toxicity, and did not induce changes in CD4 lymphocyte counts or HIV RNA load. CONCLUSIONS: Gemfibrozil is safe and demonstrated at most, modest efficacy for hypertriglyceridemia in HIV-infected patients receiving protease inhibitors. Given the level of response, however, it is unclear whether these reductions will confer clinical benefit, at least in the presence of continued protease inhibitor use.

Diet↗
PubMed2002

Clinical features of acute retroviral syndrome differ by route of infection but not by gender and age.

The rate of HIV disease progression is associated with the severity of the acute retroviral syndrome (ARS). We explored the clinical features of ARS by gender, age and route of infection among 378 individuals with documented ARS enrolled in 5 prospective cohort studies with similar enrollment criteria. No major differences were detected by gender or by age. Several symptoms were reported less frequently in the injecting drug users as compared with infection acquired through sexual contacts (either heterosexual or homosexual). This was observed in particular for fever (50% vs. 77%, p=.001), skin rash (21% vs. 51%, p=.001), pharyngitis (18% vs. 43%, p=.004), and myalgia (29% vs. 52%, p=.01). Genital ulcerations were present only in cases of sexual exposure to HIV. Injecting drug users had or reported symptoms associated with the ARS less frequently than persons acquiring HIV via sexual transmission.

Acute Disease↗
PubMed2002

Abacavir substitution for nucleoside analogs in patients with HIV lipoatrophy: a randomized trial.

CONTEXT: Peripheral lipoatrophy may complicate antiretroviral therapy of human immunodeficiency virus (HIV) infection, often related to duration and type of nucleoside analog therapy, and may have a mitochondrial pathogenesis. No proven therapy exists for lipoatrophy, but abacavir is a nucleoside analog that may be less toxic to mitochondria. OBJECTIVE: To determine if substitution of stavudine or zidovudine with abacavir improves HIV lipoatrophy without affecting control of HIV replication. DESIGN: Randomized, open-label 24-week study. SETTING: Seventeen hospital HIV outpatient clinics and primary care centers in Australia and England, with randomization from June 2000 through January 2001. PARTICIPANTS: A total of 111 adults (109 men) with moderate or severe lipoatrophy who were receiving stavudine (n = 85) or zidovudine (n = 26) and had stable plasma HIV RNA levels below 400 copies/mL and no prior abacavir therapy. INTERVENTION: Patients were randomly assigned to switch from stavudine or zidovudine to abacavir, 300 mg twice per day, while continuing all other antiretroviral therapy (n = 54) or to continue all antiretroviral therapy (n = 57). MAIN OUTCOME MEASURES: The primary end point was limb fat mass, measured by dual-energy x-ray absorptiometry; key secondary end points were plasma HIV RNA levels, adverse events, physician-assessed (via subjective measures) lipodystrophy severity, total and central fat mass, and fasting metabolic (lipid, glycemic, and lactate) levels. RESULTS: There was a significant increase in limb fat in the abacavir group relative to the stavudine/zidovudine group (0.39 vs 0.08 kg; mean difference, 0.31; 95% confidence interval [CI], 0.06-0.57 kg), as well as significant relative increases in subcutaneous thigh (P =.01), arm (P<.001), and abdominal (P =.001) fat areas on computed tomography. Switching had no significant effect on secondary end points, including plasma HIV RNA (for unadjusted comparison between groups at week 24, odds ratio, 1.38; 95% CI, 0.48-3.96). Change in limb fat mass at week 24 did not correlate with change in subjectively determined perceived lipoatrophy severity (r = -0.06; P =.53 by Spearman correlation). Hypersensitivity to abacavir was seen in 5 patients (10%). CONCLUSIONS: In this sample of lipoatrophic HIV-infected adults, switching from stavudine or zidovudine to abacavir for 24 weeks led to significant, albeit modest, objectively measured increases in limb fat. Clinical lipoatrophy, as assessed subjectively, did not resolve, however, and at the rate of increase observed may take years to resolve with use of this strategy. Longer-term follow-up is needed.

Absorptiometry, Photon↗