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Biomedical subjects

Margaret Johnson

Publications and source records attributed to Margaret Johnson.

At least 19 recordsLinked to original sources
PubMed2006

Reconstitution of herpes simplex virus-specific T cell immunity in HIV-infected patients receiving highly active antiretroviral therapy.

Production of herpes simplex virus (HSV)-specific interferon- gamma by peripheral-blood mononuclear cells (PBMCs) of HSV-seropositive healthy donors and human immunodeficiency virus-infected persons was determined by use of ELISPOT. The mean +/- SD number of spot-forming cells/10(6) PBMCs was 314 +/- 74 in 11 healthy donors, 360 +/- 69 in 3 long-term nonprogressors (LTNPs), 186 +/- 52 in 9 newly diagnosed patients, and 181 +/- 59 in 33 patients who were receiving highly active antiretroviral therapy (HAART) for a median period of 30 months (range, 1-109 months). In 9 patients monitored prospectively while receiving virologically and immunologically successful first-line HAART, the number of spot-forming cells increased by 5.6/month (95% confidence interval, 1.2-9.9 [P=.01]) and 21.3/100 CD4 cells/mm(3) gained (95% confidence interval, 13.8-28.7 [P<.0001]). Responses were correlated with LTNP status and CD4 cell count.

Adolescent↗
PubMed2006

A randomized comparative trial of tenofovir DF or abacavir as replacement for a thymidine analogue in persons with lipoatrophy.

BACKGROUND: Long-term antiretroviral therapy, while dramatically reducing HIV-related morbidity and mortality, is associated with metabolic and morphological changes. Peripheral fat loss, lipoatrophy, appears most associated with prolonged therapy with thymidine nucleoside analogues. METHODS: A randomized, open-label, comparative study of switching from a thymidine nucleoside analogue to either tenofovir disoproxil fumarate (DF) or abacavir in 105 individuals on successful antiretroviral therapy with clinically evident moderate to severe lipoatrophy. RESULTS: Individuals were randomized to tenofovir DF (52) or abacavir (53). The switch was well tolerated and the majority of patients completed 48 weeks of study. One individual in the tenofovir DF group and three in the abacavir group discontinued due to drug-related adverse events. Both groups similarly maintained virological control. Limb fat mass increased similarly in both groups: mean increases by week 48 of 329 and 483 g in tenofovir DF and abacavir groups, respectively [mean 95% confidence interval for difference, -154.3 (range -492.8 to 184.3)]. This change from baseline was statistically significant in both groups (tenofovir DF, P = 0.01; abacavir, P = 0.0001). Mean total cholesterol, low density lipoprotein cholesterol and triglycerides improved modestly with switching to tenofovir DF but were unchanged with abacavir. The changes in these parameters were significantly greater in the tenofovir DF arm relative to abacavir. CONCLUSIONS: Switching from a thymidine nucleoside analogue to either tenofovir DF or abacavir leads to significant improvement in limb fat mass over 48 weeks. Tenofovir DF may have modest advantages over abacavir for changes in lipids. Peripheral lipoatrophy, when clinically apparent, resolves slowly following treatment switching.

Adenine↗
PubMed2006

96-week comparison of once-daily atazanavir/ritonavir and twice-daily lopinavir/ritonavir in patients with multiple virologic failures.

BACKGROUND: In BMS Study 045, once-daily (QD) atazanavir/ritonavir (ATV/RTV) demonstrated comparable efficacy and safety to twice-daily (BID) lopinavir/ritonavir (LPV/RTV) over 48 weeks in treatment-experienced patients. Results of extended follow-up to 96 weeks are presented. METHODS: BMS Study 045 was an open-label, randomized, multi-national trial of HIV-infected patients with virologic failure on two or more prior HAART regimens designed to evaluate the efficacy and safety of ATV/RTV (300/100 mg) QD and LPV/RTV (400/100 mg) BID, each with tenofovir (300 mg) QD and one nucleoside reverse transcriptase inhibitor. The primary efficacy measure was the time-averaged difference (TAD) in reduction in HIV RNA from baseline. Secondary objectives included evaluation of safety and plasma lipid levels through week 96. RESULTS: Over 96 weeks, the ATV/RTV regimen demonstrated similar virologic efficacy to the LPV/RTV regimen. Mean reductions from baseline in HIV RNA were -2.29 and -2.08 log10 copies/ml, respectively [TAD (97.5% confidence interval): 0.14 log10 copies/ml (-0.13, 0.41)]. The LPV/RTV regimen resulted in significant increases in total cholesterol (+9%) and fasting triglycerides (+30%) in comparison with the ATV/RTV regimen, which demonstrated decreases in these parameters [-7 and -2%, respectively, (P < 0.0001)]. Grade 2-4 diarrhoea occurred less frequently in ATV/RTV patients (3%) in comparison with LPV/RTV patients (13%) (P < 0.01). Grade 3-4 elevations in bilirubin were more common in ATV/RTV patients (53%) than LPV/RTV patients (< 1%) (P < 0.0001), with no resulting discontinuations. CONCLUSIONS: Regimens containing once-daily ATV/RTV demonstrated comparable efficacy and safety, with significant reductions in total cholesterol and fasting triglycerides and improved gastrointestinal-tolerability in comparison with twice-daily regimens containing LPV/RTV over 96 weeks in treatment-experienced patients.

Adenine↗
PubMed2006

Pneumocystis pneumonia revisited: delayed diagnosis in an HIV infected individual with high blood and low lung CD4 T cell counts.

The peripheral blood CD4 count is a useful marker of immunological status in HIV infection. However, it makes up only 1% of total body CD4 cells [Parslow T. Lymphocytes and lymphoid tissue. In: Stites D, Terr A, Parslow D, editors. Basic and clinical immunology. Appleton and Lange; 1994. p. 22-40.] has a wide intra- and inter-individual variability [Turner BJ, Hecht FM, Ismail RB. CD4+ T-lymphocyte measures in the treatment of individuals infected with human immunodeficiency virus type 1. A review for clinical practitioners. Arch Intern Med 1994;154:1561-73.] and CD4 cell pathology is just one of the immune defects caused by HIV [Fauci S. Multifactorial nature of human immunodeficiency virus disease. Science 1993;262:1011-8.]. Thus a given value should always be interpreted within a specific clinical context. We describe an individual with Pneumocystis pneumonia (PCP) who was reviewed by HIV medical services several times before the correct diagnosis was made. On each occasion the possibility of PCP was discounted as he had a well-preserved blood CD4 count. Subsequent examination of his pulmonary T-lymphocyte subsets revealed marked CD4 lymphopenia.

AIDS-Related Opportunistic Infections↗
PubMed2006

Facial atrophy in HIV-related fat redistribution syndrome: a plastic surgical perspective on treatment options and a look to the future.

Approximately 50% of patients on highly active antiretroviral therapy (HAART) develop lipodystrophy with central and visceral fat accumulation and/or facial and limb atrophy. Although the exact mechanisms of this are not fully understood, the facial atrophy encountered is secondary to atrophy of the subcutaneous fat, and not the deeper fat pads, as has been suggested. More recently, the above features in combination with hyperlipidaemia and insulin resistance have been described and are referred to as HIV-related fat redistribution syndrome. This review looks at treatment options available for this stigmatizing condition.

Atrophy↗
PubMed2006

An open-label, randomized comparative pilot study of a single-class quadruple therapy regimen versus a 2-class triple therapy regimen for individuals initiating antiretroviral therapy.

OBJECTIVE: To examine the antiviral potency and tolerability profile of a single-class four drug (quadruple) nucleoside reverse transcriptase inhibitor (NRTI) regimen compared with a 2-class standard-of-care regimen. METHODOLOGY: A three-centre, randomized, open-label comparative pilot study of zidovudine/lamivudine/efavirenz (triple) versus abacavir/lamivudine/zidovudine/tenofovir (quadruple) therapy in HIV-1-infected, treatment-naive individuals. Both regimens were taken without regard to food and consisted of a twice-daily regimen and 3 pills/day. The study power was based on time-weighted average changes in HIV-1 RNA load. RESULTS: A total of 114 individuals (56 triple, 57 quadruple) received at least one dose of medication. Patients were well matched at baseline for viral load (mean 5.26 log10 versus 5.13 log10, respectively) and CD4 cell count (median 193 versus 153 cells/mm3, respectively). The two regimens performed similarly with regards to all endpoints. At week 48, by intention-to-treat, missing=failure analysis, 68% of triple- and 67% of quadruple-drug treated patients had an HIV-1 RNA <50copies/ml (P>0.05). On-treatment analysis showed 40/40 (100%) of triple- and 39/40 (97.5%) of quadruple-drug treated patients (P=0.996) had responded to <50copies/ml. No unexpected adverse events were reported. Changes in total cholesterol and triglycerides were modest but significantly favoured the quadruple therapy regimen at multiple time points. CONCLUSION: This pilot study suggests a quadruple NRTI-based regimen provides similar antiviral potency, tolerability and administrative characteristics to a 2-class triple therapy regimen. These findings should be confirmed in a more fully powered study. Potent quadruple NRTI-based regimens may have advantages for some individuals with regards to salvageability, tolerability and drug interactions.

Adenine↗
PubMed2005

Atazanavir plus ritonavir or saquinavir, and lopinavir/ritonavir in patients experiencing multiple virological failures.

OBJECTIVE: To evaluate atazanavir/ritonavir (ATV/RTV) (300/100 mg) once daily, atazanavir/saquinavir (ATV/SQV) (400/1200 mg) once daily, and lopinavir/ritonavir (LPV/RTV) (400/100 mg) twice daily, each with tenofovir (300 mg) once daily and a nucleoside reverse transcriptase inhibitor in treatment-experienced HIV-infected patients. METHODS: Randomized, open-label, 48-week multicenter trial of 358 randomized adult patients who had failed two or more prior HAART regimens with baseline HIV RNA > or = 1000 copies/ml and CD4 cell count > or = 50 x 10(6) cells/l. RESULTS: The primary efficacy endpoint [plasma HIV RNA reduction assessed by time-averaged difference (TAD)] was similar for ATV/RTV and LPV/RTV [TAD 0.13; 97.5% confidence interval, -0.12 to 0.39] at 48 weeks. Mean reductions from baseline for ATV/RTV and LPV/RTV were comparable at 1.93 and 1.87 log10 copies/ml, respectively. Mean CD4 cell count increases were 110 and 121 x 10(6) cells/l for ATV/RTV, and LPV/RTV, respectively. The efficacy of ATV/SQV was lower than LPV/RTV by both these parameters. Declines in total cholesterol and fasting triglycerides were greater with ATV/RTV and ATV/SQV than with LPV/RTV (P < or = 0.005). Lipids in the LPV/RTV arm at week 48 generally increased from baseline. Lipid-lowering agents were used more frequently in the LPV/RTV arm than in the ATV arms (P < 0.05 versus ATV/RTV), as were antidiarrheal agents (P < or = 0.04 versus both ATV treatments). No new or unique safety findings emerged. CONCLUSIONS: ATV boosted with RTV is as effective and well tolerated as LPV/RTV in treatment-experienced patients, with a more favorable impact on serum lipids. Pharmacokinetically enhanced ATV provides a suitable choice for therapy of treatment-experienced HIV-infected patients.

Adenine↗
PubMed2005

Long term probability of detection of HIV-1 drug resistance after starting antiretroviral therapy in routine clinical practice.

BACKGROUND: Little is known about the long term risk of development of HIV-1 drug resistance for patients starting antiretroviral therapy (ART) with three or four drug regimens in routine clinical practice. METHODS: We analysed a large cohort study of patients seen in one of six large HIV clinics in and around London, UK. The focus of this analysis was on patients who started ART with two nucleosides plus either a single protease inhibitor (PI), a PI with ritonavir, abacavir or a non-nucleoside reverse transcriptase inhibitor (NNRTI). RESULTS: 4306 patients were followed; 1436 (33%) started with a single PI, 279 (6%) with a PI plus ritonavir, 156 (4%) with triple nucleosides and 2435 (57%) with an NNRTI. The overall cumulative risk of viral load failure was 38% by 6 years. Risk of > or =1 major IAS-USA mutation was 27% by 6 years; risk of mutations from at least two of the three main drug classes was 20% over the same period. These are lower limit estimates as test results were not available for many with viral load failure. Risk of PI mutations being detected in people who started ART with regimens containing a PI with ritonavir was significantly lower than the risk of NNRTI mutations being detected in those starting with NNRTI-containing regimens (relative hazard 0.3195% CI 0.15-0.61; p = 0.0008). CONCLUSION: In routine practice, rates of viral load failure and of resistance detection in patients who started ART with three or four drugs are appreciable.

Adult↗
PubMed2005

Iatrogenic effects of group treatment for antisocial youths.

It has been argued that group treatment of antisocial adolescents may increase rather than decrease conduct problems. One mechanism that has been suggested to underlie this effect is "deviancy training," wherein during group sessions deviant peers reinforce each other's antisocial actions and words. These 2 hypotheses have important implications and warrant close review at conceptual and empirical levels. In this article, the authors present such a review. Conceptually, deviancy training potential of treatment sessions appears less significant than the more extensive peer influences outside treatment. Empirical findings previously cited in support of iatrogenic effects appear on close examination to provide little support. Finally, 17 of 18 new meta-analytic tests produced results not supportive of iatrogenic or deviancy training effects.

Adolescent↗
PubMed2004

A randomized study comparing a three- and four-drug HAART regimen in first-line therapy (QUAD study).

BACKGROUND: Evidence from randomized controlled trials supports the use of triple therapy. Research is required on the effectiveness of quadruple therapy in comparison to this and the relative effectiveness of specific highly active antiretroviral therapy (HAART) combinations. METHODS: Antiretroviral-naive individuals (n = 53) with an HIV-1 viral load >100 000 copies/mL were randomized to receive three-drug HAART with zidovudine/lamivudine (Combivir) and efavirenz or quadruple therapy with zidovudine/lamivudine/abacavir (Trizivir) and efavirenz (quad regimen). Patients continued on HAART for 48 weeks with regular clinical and immunological assessment. Standard and ultrasensitive (<5 copies/mL) viral load testing was carried out. RESULTS: A DAVG (difference in averages) analysis of the fall in viral load and increase in CD4 count showed no significant differences between regimens. Triple therapy resulted in a -4.17 log change (95% CI, -4.48 to -3.85) and quadruple therapy in a -4.36 log change (95% CI, -4.68 to -4.03) in viral load. For CD4 counts, the triple therapy arm increased by 164 cells/mm(3) (95% CI 112-217) and the quadruple arm by 185 (95% CI, 133-237). In an intent-to-treat analysis, 77% of patients in the triple therapy group reached an undetectable viral load (<50 copies/mL) compared with 84.2% of the quadruple therapy group. For ultrasensitive viral load testing, 23% and 18% of each group, respectively, reached undetectable viral loads. The hazard ratio for attaining a viral load of <5 copies/mL was 0.59 (95% CI, 0.26-1.33) for quadruple versus triple therapy. Three individuals in the triple therapy arm and nine in the quadruple therapy arm discontinued treatment. CONCLUSIONS: No differences in any analyses were observed between a standard of care regimen (zidovudine/lamivudine and efavirenz) and the quad regimen (zidovudine/lamivudine/abacavir and efavirenz).

Alkynes↗
PubMed2004

Acetyl-l-carnitine: a pathogenesis based treatment for HIV-associated antiretroviral toxic neuropathy.

BACKGROUND: Nucleoside analogue reverse transcriptase inhibitors (NRTI) disrupt neuronal mitochondrial DNA synthesis, impairing energy metabolism and resulting in a distal symmetrical polyneuropathy (DSP), an antiretroviral toxic neuropathy (ATN) that causes significant morbidity in HIV disease. Serum acetyl-l-carnitine (ALCAR) levels are decreased in neuropathy associated with NRTI therapy. ALCAR enhances neurotrophic support of sensory neurons and promotes energy metabolism, potentially causing nerve regeneration and symptom relief. OBJECTIVE: To assess the efficacy of oral ALCAR (1500 mg twice daily) for up to 33 months in an open cohort of 21 HIV-positive patients with established ATN. METHODS: Skin biopsies were excised from the leg before ALCAR treatment, at 6-12 month intervals thereafter and from HIV-negative non-neuropathic controls. Fibre types in epidermal, dermal and sweat gland innervation were quantified immunohistochemically. RESULTS: After 6 month's treatment, mean immunostaining area for small sensory fibres increased (epidermis 100%, P = 0.006; dermis 133%, P < 0.05) by more than that for all fibre types (epidermis 16%, P = 0.04; dermis 49%, P < 0.05; sweat glands 60%, P < 0.001) or for sympathetic fibres (sweat glands 41%, P < 0.0003). Compared with controls, epidermal, dermal and sweat gland innervation reached 92%, 80% and 69%, respectively, after 6 month's treatment. Innervation improvements continued (epidermis and dermis) or stabilized (sweat glands) after 24 month's treatment. Neuropathic grade improved in 76% of patients and remained unchanged in 19%. HIV RNA load, CD4 and CD8 cell counts did not alter significantly throughout the study. CONCLUSIONS: ALCAR treatment improves symptoms, causes peripheral nerve regeneration and is proposed as a pathogenesis-based treatment for DSP.

Acetylcarnitine↗
PubMed2004

Intracellular and plasma pharmacokinetics of nelfinavir and M8 in HIV-infected patients: relationship with P-glycoprotein expression.

One of the targets of antiretroviral therapy is within cells infected with HIV. In order to improve therapeutic efficacy, it is therefore important that the intracellular pharmacokinetics of drugs, such as nelfinavir mesylate and its active metabolite M8, are studied in addition to plasma pharmacokinetics. Previously, the intracellular accumulation of protease inhibitors has been reported in vivo, displaying the following hierarchy: nelfinavir > saquinavir > ritonavir > indinavir. Multidrug resistance transporters, such as P-glycoprotein (P-gp), may result in a lower intracellular concentration of drug via an efflux mechanism, thus contributing to sanctuary site formation. The objective of this study was to determine concentrations of nelfinavir and M8 in plasma and peripheral blood mononuclear cells from HIV-infected patients, and to ascertain the relationship between intracellular accumulation and lymphocyte P-gp expression. Venous blood samples from 12 HIV-infected patients (viral load <50 copies/ml) receiving nelfinavir (1250 mg twice daily) and dual nucleoside reverse transcriptase inhibitor therapy were collected over a full dosage interval (0, 2, 4, 8 and 12 h). Plasma and intracellular (cell-associated) drug concentrations were measured by HPLC-MS/MS. Drug exposure in plasma and cells was expressed as the area under the concentration-time curve (AUC(0-12h)), derived from non-compartmental modelling. The ratio of intracellular AUC(0-12h)/total plasma AUC(0-12h) was calculated to determine cellular drug accumulation. P-gp expression on lymphocytes was determined by flow cytometry. The median (range) AUC(0-12h) of nelfinavir in plasma and cellular compartments was 21.8 mg x h x l(-1) (5.64-50.8) and 104.6 mg x h x l(-1) (23.1-265.7), respectively. Corresponding values for M8 in plasma and cells were 6.60 mg x h x l(-1) (2.16-17.3) and 19.6 mg x h x l(-1) (5.14-60.8). A ratio of plasma M8/plasma nelfinavir (AUC(0-12h)) and intracellular M8/intracellular nelfinavir (AUC(0-12h)) gave median values of 0.32 and 0.17, respectively. The cellular accumulations [median; (range)] of nelfinavir and M8 were 5.30 (2.28-16.2) and 2.32 (1.01-10.7), respectively. A significant correlation between plasma and intracellular nelfinavir minimum concentration (Cmin) (r2=0.34; P=0.049), but not between plasma and intracellular M8 Cmin was observed. C(0h) concentrations were higher than C(12h) for both nelfinavir and M8. No relationship was observed between nelfinavir or M8 accumulation and lymphocyte cell surface expression of P-gp. This study illustrates that intracellular concentrations were higher than plasma concentrations for both nelfinavir and M8, suggesting lymphocyte accumulation. The mechanism of differential intracellular accumulation of nelfinavir and M8 remains to be elucidated. It may be that affinities for influx transporters or fundamental drug characteristics play a major role in the greater accumulation of nelfinavir than M8.

ATP Binding Cassette Transporter, Subfamily B, Mem↗