Antiretroviral drugs for AIDS

Liver as a target of human immunodeficiency virus infection

Liver injury is a characteristic feature of human immunodeficiency virus (HIV) infection, which is the second most common cause of mortality in HIV-infected patients. Now it is recognized that liver plays a key role in HIV infection pathogenesis. Antiretroviral therapy (ART), which suppresses HIV infection in permissive immune cells, is less effective in hepatocytes, thereby making these cells a silent reservoir of HIV infection. In addition to direct hepatotoxic effects of HIV, certain ART treatment modalities provide hepatotoxic effects. The exact mechanisms of HIV-triggered chronic hepatitis progression are not elucidated, but the liver is adversely affected by HIV-infection and liver cells are prominently involved in HIV-elicited injury. These effects are potentiated by second hits like alcohol. Here, we will focus on the incidence of HIV, clinical evidence of HIV-related liver damage, interactions between HIV and liver cells and the role of alcohol and co-infection with hepatotropic viruses in liver inflammation and fibrosis progression.

Ni-Pd Catalyzed Cyclization of Sulfanyl 1,6-Diynes: Synthesis of 1'-Homonucleoside Analogues

The Ni-Pd catalyzed addition-cyclization of sulfanyl 1,6-diynes 2-9 with nucleobases is described. The reactions of N-tethered 1,6-diynes with N³-benzoylthymine, N⁴,N⁴-bis(Boc)cytosine, N³-benzoyluracil and N⁶,N⁶-bis(Boc)adenine exclusively afforded the pyrrolylmethyl and furylmethyl nucleotides in good yields. Deprotection of nucleobases was completed by treatment with acids or bases. Furthermore, the reactions of pyrroles and furans with nucleophiles such as alkoxides and amines underwent detosylation and conversion to the alkoxymethyl- and arylaminomethyl-pyrroles and furans in good yields.

Synthesis of 2'-deoxy-1'-homo-N-nucleosides with anti-influenza activity by catalytic methyltrioxorhenium (MTO)/H2O2 oxyfunctionalization

This paper describes a new route for the synthesis of 1'-homo-N-nucleoside derivatives by means of either methyltrioxorhenium (MTO) or supported MTO catalysts, with H(2)O(2) as the primary oxidant. Under these selective conditions, the oxyfunctionalization of the heterocyclic ring and the N heteroatom oxidation were operative processes, regardless of the type of substrate used, that is, purine or pyrimidine derivatives. In addition, the oxidation of 1'-homo-N-thionucleosides, showed the occurrence of site-specific oxidative nucleophilic substitutions of the heterocyclic ring. The MTO/H(2)O(2) system showed, in general, high reactivity under both homogeneous and heterogeneous conditions, affording the final products with high conversion values of substrates and from medium to high yields. Many of the novel 1'-homo-N-nucleoside analogues were active against the influenza A virus, without any cytotoxic effects, retaining their activity in both protected and unprotected forms.

Potential anti-HIV agents from marine resources: an overview

Human immunodeficiency virus (HIV) infection causes acquired immune deficiency syndrome (AIDS) and is a global public health issue. Anti-HIV therapy involving chemical drugs has improved the life quality of HIV/AIDS patients. However, emergence of HIV drug resistance, side effects and the necessity for long-term anti-HIV treatment are the main reasons for failure of anti-HIV therapy. Therefore, it is essential to isolate novel anti-HIV therapeutics from natural resources. Recently, a great deal of interest has been expressed regarding marine-derived anti-HIV agents such as phlorotannins, sulfated chitooligosaccharides, sulfated polysaccharides, lectins and bioactive peptides. This contribution presents an overview of anti-HIV therapeutics derived from marine resources and their potential application in HIV therapy.

Anti-HIV-1 efficacy of extracts from medicinal plants

The anti-HIV-1 activities of butanol, hexane, chloroform and water extracts from four widely used folk medicinal plants (Sophora flavescens, Tulipa edulis, Herba ephedra, and Pachyma hoelen Rumph) were evaluated in this study. The hexane extract of Pachyma hoelen Rumph, PH-4, showed effective inhibition against HIV-1. The 50% effective concentration (EC(50)) of PH-4 was 37.3 microg/ml in the p24 antigen assay and 36.8% in the HIV-1 recombinant RT activity test (at 200 microg/ml). In addition, the PH-4 showed the protective effect on the infected MT-4 cells, with a 58.2% rate of protection. The 50% cytotoxic concentration (CC(50)) of PH-4 was 100.6 microg/ml. These results suggest that PH-4 from Pachyma hoelen Rumph might be the candidate for the chemotherapy agent against HIV-1 infection with further study.

Evaluation of quantitative liver function tests in HIV-positive patients under anti-retroviral therapy

Background and aims

Quantitative tests of liver function (QTLF) which are based on the hepatic metabolism or clearance of test substances have been successfully used to predict prognosis of a variety of different liver diseases. Still sufficient data in HIV-patients under anti-retroviral therapy (ART) are lacking. Therefore, the aim of this prospective study was to investigate if and to what extent ART influences a broad panel of quantitative tests of liver function in patients with HIV-infection.

Patients and methods

Nineteen patients (14 males, 5 females, mean age 40 years) with HIV-infection underwent QTLF including lidocaine half-life test (LHT), galactose elimination capacity (GEC), and indocyanine green clearance (IGC). These tests were performed before and 3 to 6 months after initiation of anti-retroviral therapy. Twenty age-matched healthy, medication-and virus-free adults served as controls.

Results

Lidocaine half-life was significantly lower in HIV-patients without ART. Combining anti-retroviral therapies shifted cytochrome p450 activity back into standard ranges. Galactose elimination capacity as a parameter of cytosolic liver function and indocyanine green clearance as a parameter of liver perfusion were not affected by ART.

Conclusions

QTLF may be a tool to predict prognosis or hepatic complications in HIV-infected patients with liver disease. Early determination of lidocaine half-life seems to be useful - this should be considered during the treatment of HIV-positive individuals.

Assessment of mitochondrial toxicity by analysis of mitochondrial protein expression in mononuclear cells

BACKGROUND

Real-time PCR has quantified decreased mitochondrial DNA levels in association with nucleoside reverse transcriptase inhibitor (NRTI) therapy of HIV-infected populations. However, real-time PCR is best suited to distinguish log differences in an analyte. In an effort to monitor individuals in more detail, we developed a flow cytometric assay to gauge mitochondrial function.

METHODS

Flow cytometric quantification of a mitochondrial DNA-encoded mitochondrial protein (cytochrome c oxidase subunit I (COX-I)) and a nuclear DNA-encoded mitochondrial protein [ATP synthase subunit D (Sub-D)] was optimized and validated.

RESULTS

Intra-assay and interassay variability was low using peripheral blood mononuclear cells (PBMCs) (CV of 6.15% for COX-I and 7.11% Sub-D, and 9.38% and 9.83% for COX-I and Sub-D, respectively). Mitochondrial protein depletion was evident with in vitro treatment of cells with ethidium bromide (EtBr) and zalcitabine (ddC). Mitochondrial protein expression in 40 healthy adults clustered tightly. Depletion of mitochondrial protein, however, was neither detected in cryopreserved PBMC from NRTI-treated children (n = 9) nor in adults with a history of symptoms consistent with mitochondrial toxicity or ongoing treatment with didanosine (ddI) or stavudine (d4T) (n = 51).

CONCLUSIONS

A validated flow cytometric assay allows simultaneous detection of mitochondrial DNA and nuclear DNA encoded proteins at the single cell level, offering a method to monitor for mitochondrial function. Prospective studies are required to evaluate whether mitochondrial protein loss is observed in at-risk patients prior to the onset of symptoms from mitochondrial dysfunction.

Natural history and predictors of severity of chronic hepatitis C virus (HCV) and human immunodeficiency virus (HIV) co-infection

Co-infection by the hepatitis C virus (HCV) is observed in up to 30% of HIV-infected individuals. In studies conducted in the 'pre-HAART era', the late consequences of HCV-related chronic liver disease were overshadowed by extra-hepatic causes of deaths, related to severe immune deficiency, and the impact of HCV infection on mortality of HIV-infected patients was low. While the development of HAART has resulted in a significant decrease in morbidity and mortality amongst HIV-infected patients, this clear benefit allowed the expression of liver-related complications associated with HCV chronic infection. The impact of HCV on HIV remains debated but HIV infection significantly modifies the natural history of HCV infection. HIV infection increases levels of HCV viraemia by 2- to 8-fold, resulting in a significant decrease in spontaneous recovery of acute hepatitis. HIV co-infection also worsens the histological course of HCV infection by increasing and accelerating the risk of cirrhosis or leading to rare but lethal fibrosing cholestatic hepatitis. Liver disease is now one of the leading causes of morbidity and mortality in co-infected patients, even if HAART and especially protease inhibitors, may decrease the severity of the liver disease and the liver-related mortality. Several non-exclusive pathogenic processes explain the increasing rate of liver complications associated with HCV-related liver disease.

Pharmacology of current and promising nucleosides for the treatment of human immunodeficiency viruses

Nucleoside antiretroviral agents are chiral small molecules that have distinct advantages compared to other classes including long intracellular half-lives, low protein binding, sustained antiviral response when a dose is missed, and ease of chemical manufacture. They mimic natural nucleosides and target a unique but complex viral polymerase that is essential for viral replication. They remain the cornerstone of highly active antiretroviral therapy (HAART) and are usually combined with non-nucleoside reverse [corrected] transcriptase and protease inhibitors to provide powerful antiviral responses to prevent or delay the emergence of drug-resistant human immunodeficiency virus (HIV). The pharmacological and virological properties of a selected group of nucleoside analogs are described. Some of the newer nucleoside analogs have a high genetic barrier to resistance development. The lessons learned are that each nucleoside analog should be treated as a unique molecule since any structural modification, including a change in the enantiomeric form, can affect metabolism, pharmacokinetics, efficacy, toxicity and resistance profile.

Non-alcoholic fatty liver disease in HIV-positive patients predisposes for acute-on-chronic liver failure: two cases

Non-alcoholic fatty liver disease is a prominent feature in HIV-positive patients. We present two patients with long-lasting HIV-infection who suffered from this disease, as induced by highly active anti-retroviral therapy (HAART). The patients developed acute-on-chronic (AOC) liver failure after either (case 1) acute infection with hepatitis A virus (HAV) or (case 2) methamphetamine abuse ('Ecstasy'). Approximately 1 week after visiting an area endemic for HAV, case 1, a male patient, presented with icterus, elevated liver transaminases and HAV IgM. Previous examinations had demonstrated normal liver transaminase activities while hepatic steatosis had been suspected. He developed complications associated with liver failure including renal failure as well as pleural and pericardial effusions. Case 2, a second male patient, developed both liver failure and lactic acidosis 24 h after methamphetamine abuse. Both patients suffered from fatty liver in the pre-acute stage as indicated by ultrasound examination. After developing symptoms of liver failure, HAART was discontinued in both patients. Follow-up visits demonstrated that the patients recovered clinically with almost normalized laboratory parameters. In HIV infection, HAART-induced hepatopathological alterations may exist despite the absence of relevant laboratory parameters. These patients are likely to develop AOC liver failure when subjected to acute risk factors such as hepatitis viruses and narcotics or other drugs. In patients treated with HAART, we thus highly recommend hepatitis A and B virus vaccinations, and close monitoring of liver parameters.

HIV infection and hepatic enzyme abnormalities: intricacies of the pathogenic mechanisms

Liver enzyme elevations are common in human immunodeficiency virus (HIV)-infected patients, and their diagnosis or management may be difficult because of the intricacies of the pathogenic mechanisms involved. These include hepatotoxicity related to the highly active antiretroviral therapy (HAART) regimen, idiosyncratic or immunoallergic mechanisms, and direct cytotoxicity enhanced by an underlying liver disease. Liver enzyme abnormalities may also reflect hepatitis B (HBV) or hepatitis C (HCV) infection, which each have their own risks for chronic immune-mediated liver disease (including hepatitis flare after immune reconstitution) and of direct cytotoxicity. Finally, other factors may affect liver deterioration, including alcohol-related liver disease, nonalcoholic steatohepatitis associated with metabolic syndromes (e.g., hyperlipidemia, diabetes, or being overweight) that are potentially HAART related, and use of medication or illicit drugs (e.g., methamphetamine). A better understanding of these complex interactions, including adjustments of dosages of antiretroviral drugs, will probably help in the management of HIV-infected patients with liver enzyme abnormalities.

The effect of highly active antiretroviral therapy for HIV on the anti-HCV specific humoral immune response

The effect of highly active antiretroviral therapy (HAART) on HCV replication is controversial, with some studies reporting no effect and others increases, reductions and even clearances of HCV RNA after treatment. In this study, the effect of HAART was investigated on the titre of anti-HCV specific antibodies and on the relationship between these antibodies and HCV RNA level in a cohort of 24 patients with inherited bleeding disorders. A significant inverse correlation between antibodies to both total HCV proteins and HCV RNA (R = -0.42, P = 0.05) and between antibodies to HCV envelope glycoproteins and HCV RNA (R = -0.54, P = 0.01) was observed pre-HAART. The relationship disappeared or was obscured after therapy (R = 0.24, P = 0.30 and R = 0.16, P = 0.50, respectively). Thus, we show that HAART affects the HCV specific humoral immune responses without affecting the HCV RNA level.

Adoptive immunotherapy in chimeras with donor lymphocytes

Allogeneic stem cell transplantation has a well-defined indication in the treatment of hematological malignancies. The beneficial immune effect of allogeneic marrow transplantation has long been known, but only recently have methods been developed to separate the graft-versus-leukemia (GVL) effect from graft-versus-host disease (GVHD). Animal experiments have shown that lymphocytes from the marrow donor can be transfused without causing severe GVHD if stable chimerism and tolerance is established. First clinical studies have been preformed in patients with recurrent chronic myelogenous leukemia. In these patients complete molecular remissions were induced that persist without further maintenance treatment. These results have been confirmed in larger multicenter studies in Europe and the USA. The best results were obtained in chronic myelogenous leukemia (CML); repeated successes have been reported in relapsing acute myeloid leukemia (AML), myelodysplastic syndromes and multiple myeloma (MMY), and rare responses were reported for acute lymphoid leukemia. Contrary to animal experiments GVHD has been observed in human patients although to a lesser extent than expected in transplants not given immunosuppression. Secondly myelosuppression has been observed in patients treated with relapsing CML. In CML the incidence of GVHD could be reduced by depleting CD8+ T cells from the donor lymphocyte concentrate. Alternatively only small numbers of T lymphocytes can be transfused and in the case of failing responses, the numbers of donor lymphocytes may be increased. Results in recurrent AML have been improved by the use of low-dose cytosine arabinoside, granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor mobilized blood cells as compared to lymphocytes only. In MMY the response rate is higher than in AML, but the remissions are of limited duration in most patients. Several protocols have been designed to include preemptive donor lymphocyte transfusion in patients with a high relapse risk after transplantation. Problems remain to avoid chronic GVHD and to circumvent the immune escape mechanisms of leukemia.

Drug interactions between antiretroviral drugs and comedicated agents

HIV-infected individuals usually receive a wide variety of drugs in addition to their antiretroviral drug regimen. Since both non-nucleoside reverse transcriptase inhibitors and protease inhibitors are extensively metabolised by the cytochrome P450 system, there is a considerable potential for pharmacokinetic drug interactions when they are administered concomitantly with other drugs metabolised via the same pathway. In addition, protease inhibitors are substrates as well as inhibitors of the drug transporter P-glycoprotein, which also can result in pharmacokinetic drug interactions. The nucleoside reverse transcriptase inhibitors are predominantly excreted by the renal system and may also give rise to interactions. This review will discuss the pharmacokinetics of the different classes of antiretroviral drugs and the mechanisms by which drug interactions can occur. Furthermore, a literature overview of drug interactions is given, including the following items when available: coadministered agent and dosage, type of study that is performed to study the drug interaction, the subjects involved and, if specified, the type of subjects (healthy volunteers, HIV-infected individuals, sex), antiretroviral drug(s) and dosage, interaction mechanism, the effect and if possible the magnitude of interaction, comments, advice on what to do when the interaction occurs or how to avoid it, and references. This discussion of the different mechanisms of drug interactions, and the accompanying overview of data, will assist in providing optimal care to HIV-infected patients.

Acute hepatic failure and lactate acidosis associated with antiretroviral treatment for HIV

Severe hepatotoxicity is a rare but potentially life-threatening side effect of antiretroviral therapy. In this case report we describe an HIV-positive patient who was admitted to our clinic with evidence of severe acute pancreatitis 18 months after the introduction of antiretroviral treatment, which included stavudine and didanosine. Shortly afterwards, she developed lactate acidosis and acute hepatic failure associated with renal failure. Renal support (hemofiltration) was required for three days. The patient subsequently developed grade III encephalopathy, as well as a large pleural effusion and ascites. Although the reported outcome of patients with liver failure due to antiretroviral treatment is poor, with a high mortality rate, our patient fully recovered after intensive supportive care and cessation of the antiretroviral agents. Liver biopsy revealed microvesicular steatosis and giant mitochondria, which are the typical hallmarks of mitochondrial damage, the presumed mechanism of antiretroviral drug toxicity. More than three years later the patient has an excellent clinical status with a stable HIV infection and no need for antiretroviral treatment. This case report indicates the need for increased awareness of the potential hepatotoxicity of an antiretroviral therapy, as severe side effects may occur more frequently with increasing use of such treatment.

Screening of selected plant extracts for in vitro inhibitory activity on human immunodeficiency virus

As part of our screening of anti-AIDS agents from natural sources, extracts of 15 medicinal plants widely used in the folk medicines of North America and Europe were evaluated in vitro. Most of the extracts tested were relatively nontoxic to human lymphocytic MT-2 cells, but only the extracts of Hysopp officinalis and Dittrichia viscosa exhibited anti-HIV activity in an in vitro MTT assay. The 50% hydroalcohol extract of Hysopp officinalis and the aqueous extract of Dittrichia viscosa showed inhibitory effects against HIV-1 induced infections in MT-2 cells at concentrations ranging from 50 to 100 microg/mL and 25 to 400 microg/mL, respectively. Both extracts showed no appreciable cytotoxicity at these concentrations.

Acute liver failure associated with antiretroviral treatment for HIV: a report of six cases

BACKGROUND/AIMS

Severe hepatotoxicity is a rare but potentially fatal side effect of all antiretrovirals. We report a series of six human immunodeficiency virus (HIV)-infected patients admitted with acute liver failure (ALF) over a 25-month period, of whom five died. All had been treated with a range of antiretroviral therapy and only two had had acquired immune deficiency syndrome (AIDS) defining illnesses.

RESULTS

Median duration of antiretroviral therapy was 12.5 months (range 1-23). Median time from the introduction of new antiretroviral therapy to the onset of ALF was 8 weeks (range 2-12). The development of ALF was unrelated to duration of HIV treatment or type of antiretroviral therapy, and was not predicted by close out-patient supervision and monitoring of liver function. Biochemical investigations were variable but revealed a predominantly hepatocellular pattern. Liver biopsy revealed typical features of mitochondrial toxicity in only one case, with confluent hepatocellular necrosis, inflammation and cholestasis seen in the others.

CONCLUSIONS

There is a need to increase awareness of the potential hepatotoxicity of antiretroviral therapy and to develop means of predicting its development. With increasing usage of antiretroviral therapy, severe hepatotoxicity and ALF may arise more frequently, and the outcome is poor despite intensive supportive therapy.

Hepatitis C and human immune deficiency coinfection at the era of highly active antiretroviral therapy

Interactions between human immunodeficiency virus (HIV) and hepatitis C virus (HCV) have been widely studied before the introduction of highly active antiretroviral therapies (HAART). We reviewed the potential impact of HAART on hepatitis C as well as the interactions between HIV and HCV therapies. Physicians should be aware of the potential risk of: (i) symptomatic liver disease in HCV-HIV-coinfected patients at the era of triple antiretroviral therapy; (ii) potential liver deterioration paralleling immune restoration; (iii) lack of impact of triple antiretroviral therapy on HCV load; and (iv) potential drug-related hepatitis which may modify the natural history of HCV-related liver disease. Liver biopsies should be performed regularly in these patients in order to identify patients with severe liver disease who require early initiation of anti-HCV therapy under close monitoring of their immune status. Treatment is, to date, based on the combination of ribavirin and interferon with an expected sustained response rate around 25%. An important unresolved issue is to better delineate the temporal place of anti-HCV and anti-HIV antiviral therapies. At least in coinfected patients with significant liver disease, namely necro-inflammatory activity and/or fibrosis >or= 2, we believe that anti-HCV therapy is the priority since it lessens the risk of drug-induced hepatitis and of hepatitis due to immune restoration.

Effects of HAART on hepatitis C, hepatitis G, and TT virus in multiply coinfected HIV-positive patients with haemophilia

In multiply coinfected human immunodeficiency virus (HIV)-positive patients, we investigated the effects of high-activity antiretroviral therapy (HAART) using HIV protease inhibitors on three other viruses: hepatitis C virus (HCV), hepatitis G virus (HGV), and TT virus (TTV). Viral concentrations were measured serially by polymerase chain reaction methods in five patients with quadruple infection (HIV, HCV, HGV, and TTV) and in two patients with triple infection (HIV, HCV, and HGV) before and during HAART. In addition, CD4+ cell counts and serum alanine aminotransferase (ALT) levels were measured serially. Generally we observed no difference in serum HCV RNA, HGV RNA, or TTV DNA concentrations between samples obtained before and after initiation of HAART, whereas HIV RNA concentration decreased and CD4 counts increased in most patients. However, two patients had markedly decreased concentrations of HCV RNA and HGV RNA, respectively, more than 12 months after beginning HAART. Normalization of serum ALT levels was observed in a patient with decline of HCV RNA concentrations. No interactions were observed among these four viruses. HAART had no apparent direct effects on HCV, HGV, or TTV. Further studies will be required to elucidate whether the restoration of immune status through suppression of HIV replication by HAART may affect HCV or HGV RNA concentrations.

Anti-HIV activity of medicinal plant extracts

As part of our screening of anti-AIDS agents from natural sources, ethanolic and aqueous extracts of 15 medicinal plants widely used in the folk medicine of the Iberian Peninsula were evaluated in vitro. Most of the extracts tested were relatively nontoxic to human lymphocytic MT-2 cells, but only the extracts of Tuberaria lignosa and Sanguisorba minor magnolii exhibited anti-HIV activity in an in vitro MTT assay. The aqueous extracts of these plants showed inhibitory effects against HIV-1 induced infections in MT-2 cells at concentrations ranging from 12.5 to 50 microg/ml and 50 microg/ml, respectively. Both extracts showed no appreciable cytotoxicity at these concentrations.

Smaller amounts of antiretroviral drugs are needed when combined with an active ribozyme against HIV-1

We have tested for combined anti-HIV-1 effects of a hammerhead ribozyme and antiretroviral drugs and the possibility of reducing the drug burden of patients on highly active antiretroviral therapy (HAART). The antiretroviral compounds used represent the three groups in HAART: nucleoside analogue reverse-transcriptase inhibitors, nonnucleoside reverse-transcriptase inhibitors, and protease inhibitors. A human T cell line (HUT78), stably expressing a hammerhead ribozyme targeted to nef (hhRz.nef(9016-9029)), was infected with HIV-1(SF2) in the presence of a single drug. The combined effects on HIV-1 replication were measured by p24 antigen determinations over a 2-week period. In the presence of the ribozyme, smaller amounts of antiretroviral drugs were required to reduce the HIV-1 p24 levels equally as much as when only drugs were present. The results support a strategy of combining ribozyme gene therapy with HAART to improve the long-term outcome of anti-HIV-1 therapy.

Immunologic dynamics in hemophiliac patients infected with hepatitis C virus and human immunodeficiency virus: influence of antiretroviral therapy

Infection with hepatitis C virus (HCV) or human immunodeficiency virus (HIV) or both is common in hemophiliac patients due to putative transmission through clotting factor concentrates. Recently, highly active antiretroviral therapy (HAART) has been found to markedly improve viremia and immunologic parameters in patients infected with HIV. This report considers interactions between these viral infections, the immune system, and antiretroviral therapy. A total of 130 male hemophiliac patients were grouped according to type of viremia (HCV, HIV, both, or neither). Along with 30 healthy men age-matched to viremic patients, these groups were compared with respect to viral load and immunologic parameters. Thirty-five patients treated as above for HIV were serially followed up. HCV infection was associated with reduced peripheral B-cell and CD4+-cell counts and with increased serum IgG and IgM levels, whereas HIV infection was associated with reduced peripheral CD4+-cell counts and increased serum IgG and IgA levels. In patients with both viruses, HCV and HIV RNA load correlated inversely with peripheral B-cell and CD4+-cell counts, respectively. HAART reduced levels of both viruses in the blood. Of the 25 patients with both viruses, HAART eliminated HCV in 2. In conclusion, immunologic dynamics differed between hemophiliac patients infected with HCV, HIV, or both. The relative dynamics of HCV viral load, peripheral B-cell count, and serum IgM level were similar to those of HIV viral load, CD4+-cell count, and serum IgA.

Immunologic dynamics in hemophiliac patients infected with hepatitis C virus and human immunodeficiency virus: influence of antiretroviral therapy

Infection with hepatitis C virus (HCV) or human immunodeficiency virus (HIV) or both is common in hemophiliac patients due to putative transmission through clotting factor concentrates. Recently, highly active antiretroviral therapy (HAART) has been found to markedly improve viremia and immunologic parameters in patients infected with HIV. This report considers interactions between these viral infections, the immune system, and antiretroviral therapy. A total of 130 male hemophiliac patients were grouped according to type of viremia (HCV, HIV, both, or neither). Along with 30 healthy men age-matched to viremic patients, these groups were compared with respect to viral load and immunologic parameters. Thirty-five patients treated as above for HIV were serially followed up. HCV infection was associated with reduced peripheral B-cell and CD4+-cell counts and with increased serum IgG and IgM levels, whereas HIV infection was associated with reduced peripheral CD4+-cell counts and increased serum IgG and IgA levels. In patients with both viruses, HCV and HIV RNA load correlated inversely with peripheral B-cell and CD4+-cell counts, respectively. HAART reduced levels of both viruses in the blood. Of the 25 patients with both viruses, HAART eliminated HCV in 2. In conclusion, immunologic dynamics differed between hemophiliac patients infected with HCV, HIV, or both. The relative dynamics of HCV viral load, peripheral B-cell count, and serum IgM level were similar to those of HIV viral load, CD4+-cell count, and serum IgA.

Subcutaneous interleukin-2 in combination with anti-retroviral therapy for treatment of HIV-1-infected subjects

A total of 11 HIV-1 positive patients, with CD4+ cell counts between 200 and 500/microl, who were in stable anti-retroviral therapy, were treated with subcutaneous recombinant human IL-2 thrice weekly administered on an out-patient basis in a dose-escalating manner. Subcutaneous IL-2 was well tolerated and associated with only mild to moderate constitutional symptoms and local inflammation at the injection site. CD4+ cell count increased from 404 +/- 48/microl at baseline to 639 +/- 88/microl at week 6, with proportionate increases in naive cells and memory cells. Increased doses of IL-2 were then needed to sustain the number of CD4+ cells. After discontinuation of IL-2 treatment, CD4+ cell count returned to baseline levels. IL-2 induced a reduction in the percentage of CD8+ CD38+ and CD8+ HLA-DR+ cells, an increase in the fraction of CD8+ CD25+ and CD8+ CD122+, and an elevation in the number of NK-cells. IL-2 did not induce any clinically significant change in plasma HIV-RNA. In conclusion, IL-2 can safely be administered subcutaneously on an out-patient basis to HIV-infected individuals with CD4+ cell counts from 200/microl to 500/microl and with some improvement in immunological abnormalities. Continuous therapy, however, seems to result in the development of tachyphylaxia.

Illness behavior, emotional stress and psychosocial factors among asymptomatic HIV-infected patients

BACKGROUND

Over the last years the way in which patients with chronic physical illness respond to their illness (illness behavior) has been explored by several studies. This study sought to examine characteristics of illness behavior and to investigate the association between illness behavior and psychosocial and clinical variables among asymptomatic HIV-infected subjects.

METHODS

Seventy-three asymptomatic HIV+ outpatients completed self-report questionnaires to evaluate illness behavior (Illness Behavior Questionnaire), psychological stress symptoms (Brief Symptom Inventory), personality variables (External Locus of Control and Courtauld Emotional Control Scales) and social support (Social Provision Scale).

RESULTS

Psychological morbidity ('caseness' = 34%) was associated with a pattern of illness behavior characterized by conviction of disease progression, irritability, dysphoria, psychological perception of illness and low denial. Individual capacity to express emotions, adequate levels of social support and low levels of depression, as well as clinical variables (high number of CD4+ cells, recent notification of HIV infection and nonintravenous drug use category) influenced a more adaptive illness behavior. Psychological stress and low CD4+ cell count were the main predictors of the affective dimension of illness behavior.

CONCLUSIONS

Psychosocial variables resulted to influence the tendency to interpret illness in a nonadaptive way in asymptomatic HIV-infected subjects. Such variables merit to be routinely examined within the doctor-patient relationship in AIDS clinics.

Review article: nitroimidazole resistance in Helicobacter pylori

The efficacy of a nitroimidazole-containing regimen for the treatment of Helicobacter pylori infection is decreased by nitroimidazole resistance. Nitroimidazoles are meta- bolized by H. pylori by several nitro-reductases of which an oxygen-insensitive NADPH nitroreductase encoded by the rdxA gene is the most important. Null mutations in this gene are associated with resistance. Susceptibility testing to nitroimidazoles may give variable results. This is not only related to the slow growth under specific conditions, but also to variability in the activity of the other nitroreductases and the ability to deactivate toxic metabolites of an NI and to repair DNA damage. Moreover, co-infections with resistant and susceptible bacteria are frequently found. The presence of nitroimidazole resistance is related to the previous use of this drug. The prevalence of resistance is rising and nowadays 10-50% of the isolates are resistant. Resistance reduces the efficacy of a treatment regimen to a variable degree. This is related to efficacy of the other components of the regimen and the treatment duration. Whether a nitroimidazole is still effective in resistant strains remains unresolved. When nitroimidazole resistance is present, a nitro-imidazole-containing regimen should be avoided or a regimen with other highly effective components should be used.

Conferral of an antiviral state to CD4+ cells by a zipper motif envelope mutant of the human immunodeficiency virus type 1 transmembrane protein gp41

We showed in a transient coexpression study that a single proline substitution for any of the five conserved leucine or isoleucine residues located in the envelope (Env) transmembrane protein gp41 zipper motif of the human immunodeficiency virus type 1 dominantly interferes with wild-type Env-mediated viral infectivity. In the present study, we intended to explore the feasibility of developing a genetic anti-HIV strategy targeting the zipper motif. Stable HeLa-CD4-LTR-beta-gal clones that harbored silent copies of Tat-regulated expression cassettes encoding the zipper motif Env mutants were first generated. Expression of any of the five Env mutants in transfectants interfered with exogenously expressed homologous HXB2 Env-mediated cytopathic effects. Mutant transfectants 566, 573, and 580 were further examined. Viral transmission mediated by the laboratory-adapted T cell-tropic HXB2 and NL4-3 viruses was greatly reduced in these transfectants compared with that observed in the env-defective control deltaKS and wt env transfectants. Moreover, viral replication mediated by the NL4-3 virus and a macrophage-tropic ADA-GG virus was delayed or reduced in human T cells harboring the mutant 566 or 580 env construct as opposed to those observed in cells harboring the control deltaKS or mutant 573 env construct. The wt and mutant Env proteins formed a hetero-oligomer when they were coexpressed. These results demonstrate that zipper motif Env mutants 566 and 580 confer an anti-HIV state to the host CD4+ cells, which indicates that dominant inhibitory mutants targeting the gp41 zipper motif might function as genetic anti-HIV agents to combat HIV-1 infection.

ddC- and 3TC-bis(SATE) monophosphate prodrugs overcome cellular resistance mechanisms to HIV-1 associated with cytidine kinase deficiency

A 2',3'-dideoxycytidine (ddC)-resistant T-lymphoid cell line (MOLT-4/8rddC250), in which deoxycytidine kinase (dCK) gene-expression was decreased when compared with parental cells, has been selected. Cytotoxic and antiretroviral activity of ddC and 3TC was significantly lower in MOLT-4/8rddC250-than in parental MOLT-4/8 cells. ddC- and 3TC-bis(SATE)phosphotriesters completely overcame cellular resistance mechanisms and showed comparable both cytotoxic and antiretroviral activity in parental and ddC-resistant cells.

Inhibition of human immunodeficiency virus replication by RD6-Y664, a novel benzylhydroxylamine derivative

We have examined novel benzylhydroxylamine derivatives for their inhibitory effects on the replication of human immunodeficiency virus (HIV) in cell cultures. Among the series, O-(2-chloro-6-fluorobenzyl)hydroxylamine (RD6-Y664) was found to be the most potent inhibitor of HIV-1. The EC50 for HIV-1 strain IIIB was 1.6 micrograms/ml with a selectivity index greater than 38 in MT-4 cells. It also inhibited the replication of other HIV strains including a non-nucleoside reverse transcriptase (RT) inhibitor-resistant mutant, a nucleoside RT inhibitor-resistant mutant and HIV-2, in acutely infected cells. However, the compound did not affect HIV-1 production in chronically infected cells. A time-of-addition experiment and detection of proviral DNA synthesis suggested that RD6-Y664 targeted an early step of the viral replication cycle, presumably a process prior to reverse transcription. In fact, an assay for HIV-1 RT revealed that the compound did not suppress enzyme activity. Furthermore, RD6-Y664 did not show any inhibition of gp120-CD4 interaction, or binding of anti-CXCR4 antibody to CXCR4.

Hyperlipidemia under treatment with proteinase inhibitors

To define the extent and time course of HIV-proteinase inhibitor (PI) effects on serum lipid levels 148 patients on triple combination therapy including PIs and 91 patients on therapy with two nucleosides as a control group were evaluated. In the PI group there was a significant increase in total cholesterol after 3, 6 and 12 months compared to the baseline level (198, 204 and 203 vs. 176 mg/dl). The increase in triglycerides was 25.5% from the baseline at month 3. Indinavir had a significantly higher impact on cholesterol levels than saquinavir. No changes in lipids were seen in the control group. It was concluded that hyperlipidemia is associated with PI use, becomes evident within 3 months of treatment and seems to be substance specific.

Selective vertical transmission of HIV-1 antiretroviral resistance mutations

OBJECTIVE

To examine the patterns of vertical transmission of zidovudine (ZDV) resistance mutations.

DESIGN

HIV-1 reverse transcriptase codons 10-250 were sequenced from 24 pairs of ZDV-exposed women and their HIV-infected infants as part of the Women and Infants Transmission Study.

METHODS

Viral RNA was extracted from tissue culture supernatants and sequenced using fluorescent dye-primer chemistry and an automated sequencer.

RESULTS

For 17 of these pairs, maternal and infant sequences were identical to one another and lacking known ZDV resistance mutations. The remaining seven maternal sequences contained known mutations associated with ZDV resistance at reverse transcriptase codons 70, 210, 215 and 219. In each case where the maternal HIV isolate showed a pure mutant species, the infant sequence was identical. When the maternal sequence showed the presence of a sequence mixture at codon 70 or 219, the infant's virus showed only wild-type sequence even when the ZDV-resistant mutant was quantitatively dominant in the mother. The single maternal HIV isolate showing mixed sequence at codon positions 210 and 215 transmitted an unmixed mutant to the infant at both positions. When maternal mixtures were present at sites not associated with ZDV resistance, only the dominant species appeared in the infant.

CONCLUSIONS

When maternal HIV isolates contained mixed wild-type and ZDV-resistant subpopulations, only a single component of the mixture could be detected in the infected infants. Resistance mutants without the codon 215 mutation were not transmitted from mixtures, even when the mutants formed the majority of circulating maternal virus. In perinatal HIV transmission, specific ZDV-resistant HIV genotypes circulating in the maternal virus pool may influence whether infection in the infant will be established by a wild-type or ZDV-resistant HIV strain.

Cycloguanil and its parent compound proguanil demonstrate distinct activities against Plasmodium falciparum malaria parasites transformed with human dihydrofolate reductase

The lack of suitable antimalarial agents to replace chloroquine and pyrimethamine/sulfadoxine threatens efforts to control the spread of drug-resistant strains of the malaria parasite Plasmodium falciparum. Here we describe a transformation system, involving WR99210 selection of parasites transformed with either wild-type or methotrexate-resistant human dihydrofolate reductase (DHFR), that has application for the screening of P. falciparum-specific DHFR inhibitors that are active against drug-resistant parasites. Using this system, we have found that the prophylactic drug cycloguanil has a mode of pharmacological action distinct from the activity of its parent compound proguanil. Complementation assays demonstrate that cycloguanil acts specifically on P. falciparum DHFR and has no other significant target. The target of proguanil itself is separate from DHFR. We propose a strategy of combination chemotherapy incorporating the use of multiple parasite-specific inhibitors that act at the same molecular target and thereby maintain, in combination, their effectiveness against alternative forms of resistance that arise from different sets of point mutations in the target. This approach could be combined with traditional forms of combination chemotherapy in which two or more compounds are used against separate targets.

[Interactions between the human immunodeficiency virus and hepatitis C virus]

INTRODUCTION

Prevalence of hepatitis C virus (HCV) infection in human immunodeficiency virus (HIV)-infected subjects is around 9%, varying according to the mode of contamination. Reciprocal interactions between the two viruses have to be evaluated.

CURRENT KNOWLEDGE AND KEY POINTS

HCV infection is usually associated with chronic hepatitis and detectable viremia in HIV-infected patients. HIV infection enhances HCV replication, leading to more severe liver lesions and to a more rapid occurrence of cirrhosis. This underlines the need for both early diagnosis and therapy in order to avoid severe evolution of the liver disease.

FUTURE PROSPECTS AND PROJECTS

Even though the rate of long-term responses to interferon alpha is low, improvement may be expected from combined therapies, especially with combination including ribavirin. The impact of both antiretroviral triple therapy and accompanying immune restoration on natural history and treatment of HCV infection has to be assessed, as the above mentioned consensual conclusions may be modified in a near future.

Human immunodeficiency virus infection, Part I

Initially recognized in 1982, acquired immunodeficiency syndrome (AIDS) has been the leading cause of death among young adults in the United States for much of this decade, and it has had a devastating impact on people in the developing world. It is estimated that 42 million people worldwide have been infected with human immunodeficiency virus (HIV), the virus that causes AIDS, and that almost 12 million people have died from AIDS-related diseases through 1997. Among these 12 million are 3 million children. Two thirds of the more than 30 million people with HIV or AIDS reside in sub-Saharan Africa. In the United States, 641,086 patients have been diagnosed with AIDS through 1997, and at least 385,000 have died. However, for the first time, new highly active antiretroviral therapies that include multiple drugs that attack the virus at several sites have slowed the progression from HIV to AIDS and from AIDS to death for those infected with HIV. The cumulative effect of these changes has been a reduction in both AIDS incident cases and AIDS deaths. Recent epidemiologic trends indicate that the proportion of AIDS incident cases and new HIV infections are increasing among women, African-Americans, and Hispanics, and the infections are more likely to be acquired through heterosexual transmission. The clinical management of HIV infection and AIDS has become increasingly complex in recent years. In addition to complete medical and social histories and physical examinations, hematologic, biochemical, serologic, and immunologic laboratory tests are required to predict the likelihood that patients will develop opportunistic infections and other complications related to HIV infection. Among the most important laboratory tests are measurements of HIV in plasma (viral load) in conjunction with peripheral blood CD4+ helper T lymphocyte counts. These tests are potent predictors of disease progression and their results have become markers for clinical response to therapy. The development of highly active antiretroviral therapy has had a profound impact on the epidemiology of AIDS and on the lives of individual patients. Through combinations of antiretroviral drugs, especially protease inhibitors, viral suppression can be achieved. However, adherence to these complex medical regimens and drug interactions have been problems for many patients. In addition, numerous questions remain unanswered, most importantly those regarding the timing of the initiation of treatment, the durability of viral suppression and clinical response, and the optimal "salvage" regimens for patients failing therapy either clinically or virologically.

Laboratory and clinical markers of HIV infection in a national haemophilia cohort treated with recombinant factor VIII concentrate. The Association of Hemophilia Clinic Directors of Canada

Over an interval of approximately six months beginning in October 1993, most haemophilia A patients in Canada were switched from a plasma-derived intermediate-purity factor VIII concentrate (i.p. VIII) to a recombinant factor VIII (rVIII). In order to determine the consequence of this change in therapy on progression of HIV infection, we gathered surveillance data on clinical status and CD4 and CD8 cell counts in those patients who were HIV seropositive at the time of switching concentrates. Data were recorded at the time of switchover, annually for 2 years thereafter, and retrospectively at a point 1 year prior to the switch. CD4 cells fell significantly over the study period. Multiple direct comparisons revealed that this decline was restricted to the time intervals which included the final year in which patients received intermediate-purity factor VIII concentrate (i.p. VIII). In the 2 year interval in which rVIII was used exclusively, there was a nonsignificant fall in CD4 cells. Changes in CD4 cells did not correlate with the intensity of exposure to either i.p.VIII or rVIII. CD8 cells did not fall significantly over the study period. There was no obvious reduction in the incidence of death or clinical progression over the 2 years in which rVIII was used. However, we are hopeful that the stabilizing trend in CD4 cell counts which followed the introduction of rVIII will be predictive of corresponding clinical stabilization over the coming years.

Placental transfer of ritonavir with zidovudine in the ex vivo placental perfusion model

OBJECTIVE

The object was to determine the placental transfer of ritonavir alone and in combination with zidovudine.

STUDY DESIGN

Twelve placental perfusion studies were performed at trough (1-2 microg/mL) and peak (approximately 20 microg/mL) combinations of ritonavir and zidovudine. Accumulation of ritonavir was determined.

RESULTS

Transfer of ritonavir at trough concentrations was undetectable (<0.025 microg/mL). The clearance index of ritonavir at peak concentration was 0.085 +/- 0.05 and was unaffected by zidovudine. The fetal concentration of ritonavir was 0.0758 +/- 0.22 microg/mL at a maternal concentration of approximately 20 microg/mL and 25.5 +/- 6.9 microg/mL at a concentration of 100 microg/mL. There was no tissue accumulation of ritonavir either alone or with zidovudine.

CONCLUSION

The clearance index of ritonavir at therapeutic levels was extremely low, with little accumulation in the fetal compartment and no accumulation in placental tissue. Zidovudine does not significantly affect the transfer or accumulation of ritonavir.

The work of clinical nurse specialists (HIV/AIDS) in areas with a low prevalence of HIV infection

The role of the clinical nurse specialists (HIV/AIDS) who work in areas with a low known prevalence of HIV is considered and their contribution to patient care, either directly or indirectly through the education and support of other health care workers, is discussed. Attention is given to the implications for nursing practice and the role of the clinical nurse specialist associated with the relative infrequency of contact with patients who have HIV disease; and some of the issues for people living with HIV/AIDS in rural areas are alluded to. Finally, some of the limitations of the clinical nurse specialist role are delineated and some consideration is given to the future role of clinical nurse specialists for HIV and AIDS.

Frequency and determinants of use of antiretroviral and prophylactic therapies against Pneumocystis carinii Pneumonia (PCP) before AIDS diagnosis in Italy

To determine the frequency and the determinants of use of antiretroviral drugs and prophylaxis for Pneumocystis carinii Pneumonia (PCP) among HIV-infected individuals before AIDS diagnosis, a questionnaire was sent to all physicians reporting at least one AIDS case during the first six months of 1994 to the Italian National AIDS Registry. Information on cases diagnosed between 1 January and 31 March 1995 was collected. Information was obtained for 878 (66.4%) of the 1323 persons with AIDS: 447 (50.9%) had received antiretroviral drugs and 343 (39.1%) PCP prophylaxis, whereas 303 cases (34.5%) had received both. Individuals who became aware of being HIV-positive shortly before AIDS diagnosis were less likely to have started antiretroviral therapy (adjusted odds ratio (AOR): 0.05, 95% CI: 0.03-0.09). Homosexual men and heterosexuals were more likely to begin therapy (AOR: 1.40, 95% CI: 0.83-2.37 and AOR: 1.79, 95% CI: 1.05-3.05, respectively) compared to injecting drug users. Individuals living in Southern Italy and foreigners were less likely to start therapy (AOR: 0.75, 95% CI: 0.49-1.16 and AOR: 0.40, 95% CI: 0.15-1.09, respectively) compared to those living in Northern Italy. Results were similar for PCP prophylaxis. Lack of awareness of HIV infection, HIV exposure category, and geographical area were the most important factors associated with treatment before AIDS diagnosis.

An Integrated “Care Path” Approach: Useful for Implementation and Coordination of New Care Guidelines for Treatment of HIV Infections

Recently, the 1997 revised guidelines were published for the treatment of HIV-infected patients. These guidelines, while having a dramatic effect on the morbidity and mortality associated with HIV infection, will require the implementation of a coordinate interdisciplinary “Care Path” for each patient. This review presents updated information on the HIV life cycle and the latest approach to antiretroviral therapy. The new approach to therapy is to utilize combination antiretroviral therapy including two retroviral inhibitors with a protease inhibitor. Further, the importance of viral load has become a primary indicator of prognosis and therapy efficacy. The CD4 cell count is important, but it is of secondary significance in treatment effectiveness measurement and indication of disease progress. The complexity of the new guidelines increases the need for a well-planned interdisciplinary “Critical Path” which is then utilized for development of a patient-specific “Care Path.”

What clinicians need to know about antiviral drugs and viral resistance

The development of safe and effective antiviral therapies for the management of a variety of viral infections has expanded tremendously in recent years. Treatment is now possible for serious and potentially life-threatening infections with herpesviruses, respiratory viruses such as influenza A and respiratory syncytial virus, and the human immunodeficiency virus. The increased availability and use of antiviral drugs, however, has led to the emergence of drug-resistant viruses, especially in immunocompromised hosts. With this review, the major antiviral agents are presented with a description of the mechanisms of action, the evolution of drug resistance, and the need for in vitro antiviral susceptibility testing.

The HIV global pandemic: the development and emerging implication

AIDS was first observed in 1981. The World Health Organisation has estimated that over 6 million AIDS cases had occurred by late 1995 but that only one-third had been reported. There is an annual increase world-wide of 20%, but in Asia it is in excess of 150% each year. HIV-1 can be classified into two major groups: M which contains 10 subtypes and O which contains several heterogenous viruses. HIV-2, found mainly in Africa, contains at least five subtypes. Combination therapies with nucleoside analogues are now recommended.