Risk factors for Kaposi's sarcoma in homosexual men

Use of poppers (nitrite inhalants) among young men who have sex with men with HIV: A clinic-based qualitative study

Nitrite inhalants (poppers) are associated with HIV transmission and commonly used among young men who have sex with men (YMSM), a group at increased risk for HIV. Significant research gaps exist in understanding the context in which YMSM use poppers. Qualitative interviews were conducted with 15 YMSM (22-31 years) with HIV to better understand the context in which poppers are used and their impacts on HIV care outcomes, such as care retention and antiretroviral adherence. The Social Ecological Model was applied to understand intrapersonal, interpersonal, community, and system level influences on popper use. Factors influencing popper use included: ubiquity of popper use in sexual settings, introduction to poppers by casual sexual partners, patient-HIV provider communication surrounding poppers, neighborhood, substance use and HIV care systems, and the legal status of poppers. Implications for clinical care, public health, policy, and future research are discussed.

Pandemics and methodological developments in epidemiology history

The crisis spurred by the pandemic of COVID-19 has revealed weaknesses in our epidemiologic methodologic corpus, which scientists are struggling to compensate. This article explores whether this phenomenon is characteristic of pandemics or not. Since the emergence of population-based sciences in the 17th century, we can observe close temporal correlations between the plague and the discovery of population thinking, cholera and population-based group comparisons, tuberculosis and the formalization of cohort studies, the 1918 Great Influenza and the creation of an academic epidemiologic counterpart to the public health service, the HIV/AIDS epidemic, and the formalization of causal inference concepts. The COVID-19 pandemic seems to have promoted the widespread understanding of population thinking both with respect to ways of flattening an epidemic curve and the societal bases of health inequities. If the latter proves true, it will support my hypothesis that pandemics did accelerate profound changes in epidemiologic methods and concepts.

Prevalence, frequency, and motivations for alkyl nitrite use among gay, bisexual and other men who have sex with men in Australia

BACKGROUND AND AIMS

Gay, bisexual and other men who have sex with men (GBM) use alkyl nitrites ('poppers') at higher rates than other populations to functionally enhance sexual experiences. Their use has been associated with HIV sexual risk behaviours including receptive anal sex. We investigate the prevalence, frequency, and motivations for poppers use and their relationship with HIV risk. We also discuss the implications of the recent scheduling changes to poppers by the Australian Therapeutic Goods Administration.

METHODS

Data were drawn from the Following Lives Undergoing Change (Flux) study, a prospective observational study of licit and illicit drug use among GBM. Between 2014 and 2018, 3273 GBM enrolled in the study. In 2018, 1745 GBM provided data relating to frequency of and motivations for poppers use and were included in this analysis.

RESULTS

Median age was 33 years (IQR 25-46) and 801 GBM (45.9%) had used poppers in the previous six months ('recent use'). Among these men, 195 (24.3%) had used them weekly or more frequently. Most recent users (77.4%) reported using poppers for a 'buzz' during sex or to facilitate receptive anal intercourse (60.8%). The majority (57.7%) of HIV-negative men reporting recent poppers use were concurrently taking HIV pre-exposure prophylaxis. Recent poppers use was independently associated with receptive anal intercourse with casual partners (aOR 1.71; 95%CI 1.35-2.16) and chemsex (aOR 4.32; 95%CI 3.15-5.94). Poppers use was not associated with anxiety, depression, or drug-related harms. Only 15.4% of current users indicated they would stop using poppers if they were criminalised; 65.0% said they would 'find other ways' to obtain them.

CONCLUSIONS

Poppers are commonly used by Australian GBM to functionally enhance sexual experiences, particularly to facilitate receptive anal intercourse. Few men experienced drug-related harms from poppers use. Regulatory changes must ensure potential harms from popper use are minimised without increasing barriers to access or perpetuating stigma.

Prevalence and correlates of "popper" (amyl nitrite inhalant) use among HIV-positive Latinos living in the U.S.-Mexico border region

Poppers (nitrite inhalants) are legal, commonly used by men who have sex with men, and associated with HIV acquisition, yet research is lacking on popper use and associated adverse outcomes. People living with HIV (PLWH) in the U.S.-Mexico border region lead binational lives, including accessing care and having sex and drug use partners on both sides of the border, with broad personal and public health implications. Understanding popper use provides crucial information to guide policy and develop targeted interventions for binational PLWH. We examine prevalence and correlates of popper use among HIV-positive Latinos in the border region, an underserved population at risk for poor health outcomes. This cross-sectional study recruited a convenience sample from agencies in San Diego and Tijuana to complete quantitative surveys. Participants (N = 121) were primarily male (82.6%) and gay/bisexual (62%). Lifetime substance use (excluding cannabis) was reported by 72% of participants, and 25.6% reported lifetime popper use. Individuals recruited in the U.S. were significantly more likely to report use of poppers than were participants recruited in Mexico. Our regression model found that identifying as gay/bisexual and having bought, sold, or traded sex for money, drugs, or other goods were independently associated with popper use. Findings shed light on the profile of individuals who use poppers and lay the foundation for further research to understand the context of popper use as it relates to high-risk behavior among PLWH in this region of high transborder mobility. Binational collaborative approaches are needed to improve regional HIV care outcomes and reduce transmission risk.

Autoimmunity and dysmetabolism of human acquired immunodeficiency syndrome

Acquired immunodeficiency syndrome (AIDS) remains ill-defined by lists of symptoms, infections, tumors, and disorders in metabolism and immunity. Low CD4 cell count, severe loss of body weight, pneumocystis pneumonia, and Kaposi's sarcoma are the major disease indicators. Lines of evidence indicate that patients living with AIDS have both immunodeficiency and autoimmunity. Immunodeficiency is attributed to deficits in the skin- and mucosa-defined innate immunity, CD4 T cells and regulatory T cells, presumably relating human immunodeficiency virus (HIV) infection. The autoimmunity in AIDS is evident by: (1) overproduction of autoantibodies, (2) impaired response of CD4 cells and CD8 cells, (3) failure of clinical trials of HIV vaccines, and (4) therapeutic benefits of immunosuppression following solid organ transplantation and bone marrow transplantation in patients at risk of AIDS. Autoantibodies are generated in response to antigens such as debris and molecules de novo released from dead cells, infectious agents, and catabolic events. Disturbances in metabolic homeostasis occur at the interface of immunodeficiency and autoimmunity in the development of AIDS. Optimal treatments favor therapeutics targeting on the regulation of metabolism to restore immune homeostasis.

Histopathology of Spindle Cell Vascular Tumors

Vascular tumors with a spindled morphology represent a diagnostic challenge in soft tissue pathology. It may be difficult to distinguish certain benign entities in this category from spindled vascular tumors of intermediate malignancy or even spindled variants of angiosarcoma. This article focuses on vascular tumors characterized by a predominantly spindled morphology, including spindle cell hemangioma, acquired tufted angioma (angioblastoma of Nakagawa), kaposiform hemangioendothelioma, Kaposi sarcoma, and spindle cell variants of angiosarcoma.

Until the lab takes it away from epidemiology

BACKGROUND

It is proposed that, historically, when the conditions are right for laboratory sciences to contribute to causal knowledge, they take the place of epidemiology as leaders in a given field.

METHODS

Review examples of cholera, pellagra, and Kaposi's sarcoma.

RESULTS

In the cases of cholera, pellagra, and Kaposi's sarcoma, epidemiology ceased to be at the forefront of knowledge acquisition when laboratory sciences identified more proximate causes than those that epidemiologic group comparisons could reveal.

CONCLUSION

These three examples deal with diseases, which, at the individual level, appear to rely predominantly on a single factor. For diseases whose causes still elude specific identification by the laboratory sciences, epidemiology may be uniquely equipped to play a leading role.

Inorganic nitrite therapy: historical perspective and future directions

Over the past several years, investigators studying nitric oxide (NO) biology and metabolism have come to learn that the one-electron oxidation product of NO, nitrite anion, serves as a unique player in modulating tissue NO bioavailability. Numerous studies have examined how this oxidized metabolite of NO can act as a salvage pathway for maintaining NO equivalents through multiple reduction mechanisms in permissive tissue environments. Moreover, it is now clear that nitrite anion production and distribution throughout the body can act in an endocrine manner to augment NO bioavailability, which is important for physiological and pathological processes. These discoveries have led to renewed hope and efforts for an effective NO-based therapeutic agent through the unique action of sodium nitrite as an NO prodrug. More recent studies also indicate that sodium nitrate may also increase plasma nitrite levels via the enterosalivary circulatory system resulting in nitrate reduction to nitrite by microorganisms found within the oral cavity. In this review, we discuss the importance of nitrite anion in several disease models along with an appraisal of sodium nitrite therapy in the clinic, potential caveats of such clinical uses, and future possibilities for nitrite-based therapies.

The Amyl Nitrite Expectancy Questionnaire for Men who have Sex with Men (AEQ-MSM): a measure of substance-related beliefs

A measure of perceived reinforcement associated with amyl nitrite was developed and evaluated among gay and bisexual men. This is the first known expectancy measure to date for this drug class. The Amyl Nitrite Expectancy Questionnaire for Men who have Sex with Men (AEQ-MSM) was completed online by 102 gay and bisexual men, between 2006 and 2008 in Queensland, Australia. The AEQ-MSM demonstrated good psychometric properties and was associated with consumption patterns. Factor analysis revealed three distinct reinforcement domains: "Enhanced sexual desire and pleasure," "Disorientation," and "Sexual negotiation." Limitations include sampling via self-selection, recruitment through health centers and self-report data. Implications for sexual activity and risk-taking, including reducing associated harm (e.g., HIV transmission), and future directions are discussed.

Use of illicit drugs and erectile dysfunction medications and subsequent HIV infection among gay men in Sydney, Australia

INTRODUCTION

Use of illicit drugs and oral erectile dysfunction medications (OEM) have been associated with risk behavior among gay men.

AIM

To determine the effects of illicit drugs and OEM as risk factors for HIV seroconversion in a community-based cohort of HIV-negative homosexually active men in Sydney, Australia.

MAIN OUTCOME MEASURES

Drug use in the previous 6 months and at the most recent sexual encounter; Most recent occasions of unprotected and protected anal intercourse; HIV-positive diagnosis.

METHODS

From June 2001 to June 2007, participants were followed up with 6-monthly detailed behavioral interviews and annual testing for HIV. Detailed information about sexual, drug-using and other behavior was collected.

RESULTS

Among 1,427 participants enrolled, 53 HIV seroconverters were identified by June 2007. At baseline, 62.7% reported using illicit drugs in the previous 6 months, including 10.7% who reported at least weekly use. Illicit drug use was associated with unprotected anal intercourse with casual partners (P < 0.001). Use of illicit drugs was associated with increased risk of HIV infection at a univariate level, and this risk increased with greater frequency of use. This was also true of the use of OEM. Use of each type of illicit drug was included in multivariate analysis, and after controlling for sexual risk behaviors, only use of OEM remained significantly predictive of HIV infection (Hazard ratios [HR] = 1.75, CI = 1.31-2.33, P < 0.001), although amyl nitrite was of borderline significance (HR = 1.26, CI = 0.98-1.62, P = 0.074).

CONCLUSION

The association between drug use and increased risk of HIV infection was strongest for drugs used specifically to enhance sexual pleasure, particularly OEM. The risk of infection was substantially increased when both OEM and methamphetamine were used. Within more "adventurous" gay community subcultures, the interconnectedness of sexual behavior and drug use may be key to understanding HIV risk and is an appropriate priority in HIV-prevention efforts in this population.

Effects of repeated in vivo inhalant nitrite exposure on gene expression in mouse liver and lungs

Exposure to inhalant organic nitrites (drugs of abuse commonly known as "poppers") has been reported to enhance tumor growth in mice, but the mechanism is not fully defined. This study examined the effect of repeated in vivo nitrite exposures on gene expression in the mouse liver and lungs using a gene array panel of 94 cancer- and angiogenesis-related genes. Using 2-fold change as a threshold criterion, repeated nitrite exposure was found to alter the expression of 65 and 23 genes in the liver and lungs, respectively. Six genes were significantly upregulated (p<or=0.05), viz., those encoding VEGF, VEGFD (vascular endothelial growth factor A and D, respectively) in the lungs and FGF1, FGF4 (fibroblast growth factor 1 and 4, respectively), Hsp70 (heat shock 70kDa protein 4), and PF4 (platelet factor 4) in the liver. mRNA encoding HO-1 (heme oxygenase-1) and Smad7 were marginally (p=0.057) stimulated in the liver. Follow-up studies in the liver revealed significant nitrite-induced expression of VEGF protein and mRNA. Immuno-staining of liver slices revealed that the increased hepatic VEGF expression resided mainly in hepatocytes. Stimulation of hepatic VEGF expression by ISBN was not different in endothelial nitric oxide synthase (eNOS) knockout vs. wild-type mice. In conclusion, multiple exposures to inhalant nitrite appeared to cause alteration in the expression of a number of genes relating to cancer and angiogenesis, including VEGF. eNOS presence did not appear to be essential for nitrite-induced VEGF expression. These studies demonstrate that in vivo exposure to inhalant nitrites results in changes in the angiogenesis cascade.

Behavioral interventions for HIV-positive and HCV-positive drug users

The nature, context and frequency of use of various licit and illicit non-injection drugs associated with an elevated risk of HIV infection. Beyond HIV, a high proportion of HIV-infected IDUs are co-infected with HCV (hepatitis C virus). In this review, we provide a brief review of the epidemiology of these problems, discuss behavioral interventions that can reduce ongoing high risk behaviors among HIV-seropositive IDUs and MSM-DUs, and review the literature which has evaluated their effectiveness. The majority of these interventions have focused on HIV-seronegative heterosexuals and therefore need to be considered in this larger context; however, where possible we discuss the potential impact of these interventions among HIV-seropositive persons. In addition, we briefly discuss interventions which have the potential to simultaneously reduce ongoing transmission of both HIV and HCV. Finally, given the dearth of information on the effectiveness of behavioral interventions in reducing the burden of the HIV and HCV epidemics among persons already infected with either or both viruses, we describe some newer, promising interventions and offer suggestions for future studies.

Determination of Nitric Oxide–Donor Effects on Tissue Gene Expression In Vivo Using Low‐Density Gene Arrays

Gene array technology has been used to examine gene expression changes following drug treatments, including administration of nitric oxide (NO) donors. High-density arrays represent a powerful and popular method to analyze a large number of genes simultaneously. On the other hand, low-density arrays, available commercially at a lower cost, allow for the use of gene-specific primers, which reduces the risk of cross-hybridization among genes with similar sequence. For certain experiments in which the hypothesis is focused on a selected set of genes, use of low-density arrays might be more productive and cost-effective. Here, we describe our experience using low-density arrays to examine the effect of exposure to the NO-donor isobutyl nitrite on the expression of 23 cancer- and angiogenesis-related genes in mouse tissues. Detailed descriptions of data capture procedures, statistical tests, and confirmation studies using real-time quantitative (RTQ) reverse transcription polymerase chain reaction (RT-PCR) are presented. Three simple statistical methods, namely Student's t test, significant analysis of microarrays (SAM), and permutation adjusted t statistics (PATS), were applied on our gene array data, and their utilities were compared. All three methods yielded concordant results for the most significant genes, namely vascular endothelial growth factor (VEGF), VEGF receptor 3, Smad5, and Smad7. RT-PCR confirmed VEGF upregulation as observed via gene arrays. PATS appeared to be more robust than SAM in handling our small gene array data set. This statistical method, therefore, appears more suited for analyzing low-density gene array data. We conclude that low-density gene array is a useful screening method that can be performed with lower cost and less cumbersome data treatment.

Production of macrophage IL-1beta was inhibited both at the levels of transcription and maturation by caspase-1 following inhalation exposure to isobutyl nitrite

Epidemiological studies have identified abuse of nitrite inhalants as an independent co-factor in HIV infection and in Kaposi's sarcoma (KS) in AIDS patients. In the present study we investigated the ability of macrophages from mice exposed to isobutyl nitrite to produce the inflammatory cytokine IL-1beta, upon stimulation with IFN-gamma and LPS. The production of IL-1beta was inhibited up to 55%. IL-1beta mRNA transcription was reduced by 35% following nitrite inhalant exposure, consistent with inhibition of activation-induced phosphorylation of macrophage mitogen-activated protein kinase p38. However, synthesis of the 31 kDa IL-1beta precursor protein was only marginally inhibited. Caspase-1, which cleaves the precursor IL-1beta into mature 17 kDa IL-1beta, was examined. Nitrite inhalant exposure blocked activation-induced increases in caspase-1 activity, consistent with a 50% reduction in 17 kDa IL-1beta shown in Western blots. Thus, exposure to nitrite inhalants reduced macrophage production of IL-1beta by reducing transcription, as well as post-translational processing mediated by caspase-1.

Inhaled isobutyl nitrite inhibited macrophage inducible nitric oxide by blocking NFkappaB signaling and promoting degradation of inducible nitric oxide synthase-2

We previously reported that inhaled isobutyl nitrite inhibited macrophage tumoricidal activity by inhibiting inducible nitric oxide (NO) production. In the present study, a much shorter inhalant exposure regimen (five daily exposures) inhibited inducible NO and the NO synthase (NOS2). One of the ways in which NO and NOS2 are regulated is by ubiquitin-dependent NOS2 degradation. Immunoprecipitated NOS2 showed increased poly-ubiquitination, following exposure to the inhalant. In addition, Western blots of macrophage nuclear extracts for the NFkappaB subunit, p65, showed that exposure to the inhalant inhibited NFkappaB signaling, necessary for induction of NOS2. The inhalant blocked phosphorylation of the NFkappaB inhibitor, IkappaBalpha. The inhibition of NFkappaB signaling following inhalant exposure was confirmed using mice transgenic for the kappaB-dependent promoter of the HIV 5' LTR linked to luciferase. The data suggested that inhalant exposure likely inhibited macrophage NO production by blocking NFkappaB-mediated activation signaling and promoting poly ubiquitination of NOS2.

Inhalant nitrite exposure alters mouse hepatic angiogenic gene expression

Inhalant nitrites are drugs of abuse that have been shown to enhance tumor growth rate in mice and are epidemiologically linked to an increased risk of Kaposi's sarcoma. Because nitrites produce nitric oxide, we hypothesized that their toxicological effects might be partly mediated via regulation of angiogenic factors such as vascular endothelial growth factor (VEGF). Preliminary studies showed that isobutyl nitrite (ISBN) incubation stimulated VEGF protein expression in J774 macrophage cells. C57BL/6 mice exposed to ISBN in air exhibited significant up-regulation of VEGF protein and mRNA in the liver, but not in the lung. Liver mRNA expression of VEGF receptor 2 (VEGFR-2), VEGFR-3, Smad5, and Smad7 was also significantly altered. These results demonstrate that in vivo exposure to an inhalant nitrite results in altered tissue expression of VEGF and its receptors, suggesting that some of its toxicological effects may be mediated partly through a mechanism involving angiogenesis.

The chemical bases of the various AIDS epidemics: recreational drugs, anti-viral chemotherapy and malnutrition

In 1981 a new epidemic of about two-dozen heterogeneous diseases began to strike non-randomly growing numbers of male homosexuals and mostly male intravenous drug users in the US and Europe. Assuming immunodeficiency as the common denominator the US Centers for Disease Control (CDC) termed the epidemic, AIDS, for acquired immunodeficiency syndrome. From 1981-1984 leading researchers including those from the CDC proposed that recreational drug use was the cause of AIDS, because of exact correlations and of drug-specific diseases. However, in 1984 US government researchers proposed that a virus, now termed human immunodeficiency virus (HIV), is the cause of the non-random epidemics of the US and Europe but also of a new, sexually random epidemic in Africa. The virus-AIDS hypothesis was instantly accepted, but it is burdened with numerous paradoxes, none of which could be resolved by 2003: Why is there no HIV in most AIDS patients, only antibodies against it? Why would HIV take 10 years from infection to AIDS? Why is AIDS not self-limiting via antiviral immunity? Why is there no vaccine against AIDS? Why is AIDS in the US and Europe not random like other viral epidemics? Why did AIDS not rise and then decline exponentially owing to antiviral immunity like all other viral epidemics? Why is AIDS not contagious? Why would only HIV carriers get AIDS who use either recreational or anti-HIV drugs or are subject to malnutrition? Why is the mortality of HIV-antibody-positives treated with anti-HIV drugs 7-9%, but that of all (mostly untreated) HIV-positives globally is only 1.4%? Here we propose that AIDS is a collection of chemical epidemics, caused by recreational drugs, anti-HIV drugs, and malnutrition. According to this hypothesis AIDS is not contagious, not immunogenic, not treatable by vaccines or antiviral drugs, and HIV is just a passenger virus. The hypothesis explains why AIDS epidemics strike non-randomly if caused by drugs and randomly if caused by malnutrition, why they manifest in drug- and malnutrition-specific diseases, and why they are not self-limiting via anti-viral immunity. The hypothesis predicts AIDS prevention by adequate nutrition and abstaining from drugs, and even cures by treating AIDS diseases with proven medications.

Using the case-discussion method to teach epidemiology and biostatistics

Medical students must learn the principles of epidemiology and biostatistics to critically evaluate the medical literature. However, this subject has traditionally been difficult to teach. In 1997 at the Albert Einstein College of Medicine, the required first-year course in epidemiology and biostatistics was revised to use the case-discussion teaching method. In preparation for the course, experienced faculty participated in an intensive, two-day training workshop. The course, taught to 163 first-year medical students, was structured in two parts: (1) three lectures complemented by a detailed syllabus, followed by a multiple-choice midterm exam; and (2) six case-discussion seminars, followed by a short answer/essay final exam. There were seven case-discussion groups with 23-24 students each. The program was evaluated using subjective faculty feedback, examination scores, and student evaluation questionnaires. Faculty noted excellent student preparation and participation. Multiple-choice exam scores were comparable to those from earlier years, and a short answer/essay exam demonstrated good student mastery of the required material. Student evaluation was overwhelmingly positive, and significantly improved from prior years of the course. Positive student evaluations of the course using this teaching method continued over the next four years; National Board of Medical Examiners examination scores indicated success in mastery of the material; and student assessment of the course improved on the AAMC Graduation Questionnaire. This favorable experience suggests that case-discussion teaching can be employed successfully in teaching principles of epidemiology and biostatistics to medical students.

Kaposi's sarcoma: aetiopathogenesis, histology and clinical features

Kaposi's sarcoma (KS) represents today one of the most common skin cancers in transplanted Mediterranean subjects and, since the epidemic of human immunodeficiency virus/acquired immune deficiency syndrome, in young unmarried single men. The disease has been associated with the recent identified human herpesvirus (HHV)-8 or KS herpesvirus and its incidence in the general population shows a north to south gradient that parallels the HHV-8 increasing prevalence from Nordic countries to sub-Saharan regions. The identification of the aetiopathogenetic mechanisms (viral agents and immunodeficiency) involved in the pathogenesis of KS, are relevant for identifying susceptible subjects (HHV-8 seropositive subjects), monitoring the immune levels in iatrogenic immune suppressed patients, and developing new therapeutic approaches based on antiviral and immune modulators.

LEARNING OBJECTIVE

This article should enable the reader: (i) to learn about the clinical and molecular aspects of KS in order to have a multidisciplinary approach to a tumour that shows unique features; (ii) to consider the role of viral agents and immunity; and (iii) to recognize properties of an opportunistic neoplasm. The identification of the HHV-8 role in KS pathogenesis should establish a relevant tool in the clinical management of KS patients.

Public health policy and gay bathhouses

Public health policy on bathhouses has been limited and poorly documented. This volume is intended to expand policy-makers' and prevention-professionals' knowledge and awareness about gay bathhouses. The present paper provides a context and an overview for the volume by describing the bathhouse environment and how it differs from other public sex environments, and by describing public policies that have been implemented.

Cytotoxicity by nitrite inhalants is not related to peroxynitrite formation

Nitrite inhalant abuse has been correlated with HIV and Kaposi's sarcoma. Mouse models of inhalant exposure show immunosuppression and loss of immune cells. In the present study, isobutyl nitrite caused a dose-dependent loss of viability of a macrophage cell line. In the absence of cells, isobutyl nitrite reacted with hydrogen peroxide to form peroxynitrite. However, assays of mitochondrial respiration and nitration that detect peroxynitrite indicated that very little was present in cell cultures following exposure to the inhalants. Isobutyl, isoamyl, and butyl nitrites inhibited mitochondrial respiration, but only at high concentrations. Similarly, the nitrating activity of isobutyl nitrite occurred only at high concentrations and was not affected by the presence of hydrogen peroxide. Western blots showed that the inhalant did not increase nitrotyrosine formation in RAW cells or in peritoneal exudate macrophages (PEM) from exposed mice. Thus, the toxicity induced by isobutyl nitrite was probably not due to peroxynitrite formation.

Acute exposure to the abused inhalant, isobutyl nitrite, reduced T cell responsiveness and spleen cellularity

Isobutyl nitrite is an inhalant abused principally by male homosexuals. We have reported that subchronic inhalation exposure (45 min/day for 14 days) to 900 ppm isobutyl nitrite was immunosuppressive. In the present study, the effects of acute exposure to the inhalant were examined. Mice were exposed in an inhalation chamber to 900 ppm isobutyl nitrite for 45 min. One day later, spleen cellularity was reduced by 39% without selectively depleting CD4(+) or CD8(+) cells. The numbers of peripheral blood leukocytes and peritoneal cells were also reduced. Following acute inhalation exposure, T cell proliferative responses stimulated with allogeneic cells or anti-CD3 and anti-CD28 antibodies were inhibited, while mitogen-induced responses were not affected. Purified T cells exposed to the inhalant also had compromised responses, suggesting a direct effect on T cells. However, the cumulative effects of multiple exposures were necessary to inhibit T-dependent antibody responses or T cell or macrophage cytotoxicity.

Epidemics of vascular toxicity and pulmonary hypertension: what can be learned?

Epidemics of vascular disease caused by toxins and infectious agents affecting both humans and animals have been common in history. Examples of agents implicated include anorexients, ergotamine, mercury, arsenic, vinyl chloride, thorotrast, plant alkaloids, nitrites, toxic oil, tryptophan and bacterial, viral and parasitic infections. A major characteristic of these disorders is endothelial dysfunction, which may manifest itself in vasospastic disorders, sclerodermiform skin lesions, fibrosis, osteolytic lesions, polyneuropathy and portal and pulmonary hypertension. Angiosarcoma may also be a late outcome. These diseases are more common than is generally appreciated. The aetiology is usually multifactorial. This and other factors contribute to delayed recognition.

Relationship between pharmacokinetics and hemodynamic effects of inhaled isobutyl nitrite in conscious rats

Our objective was to examine the pharmacokinetic/hemodynamic properties of inhaled isobutyl nitrite (ISBN) in rats. ISBN is one of the volatile organic nitrites that has been used primarily as a drug of abuse. Recent studies indicate, however, that these compounds may be superior to organic nitrates for cardiovascular use because they do not produce vascular tolerance. Rats inhaled ISBN over an exposure range of 20 to 1200 ppm for 1 hour. The effects of ISBN on blood pressure and heart rate were determined and blood concentrations of ISBN were analyzed with use of gas chromatography. Apparent steady-state blood levels of ISBN were achieved during inhalation and were linear with exposure concentration (blood concentration: 0.05 to 3.5 microM; exposure concentration: 23 to 1177 ppm; r2= 0.92). Inhaled ISBN caused rapid, dose-dependent, and parallel reductions in systolic and diastolic pressure, while heart rate increased maximally to 22%. A sigmoid Emax model could describe the mean arterial pressure effect of inhaled ISBN (Emax= 55%; EC50= 0.51 microM). After inhalation, blood pressure and heart rate quickly returned to baseline, without any withdrawal rebound effect. Inhaled ISBN produced a rapid onset of action on heart rate and blood pressure, and these effects were sustained over 60 minutes of exposure. Abrupt drug withdrawal did not lead to hemodynamic rebound. The blood pressure effects were related to ISBN blood concentration by the sigmoid Emax model. These results provide new information on the pharmacokinetic/pharmacodynamic relationship of a representative nitrite inhalant.

Interview Mode and Measurement of Sexual Behaviors: Methodological Issues

Studies of sexual and other sensitive behaviors are often fraught with a variety of reporting biases. When IAQs are used to collect data, respondents may underreport certain sensitive behaviors and overreport normative behaviors. SAQs can also pose problems: requiring that respondents be literate and able to follow skip patterns. In recent years, the development of computerized technologies--audio-CASI and T-ACASI--have begun to overcome some of the limitations of IAQs and SAQs. By providing a more private mode for data collection and standardized delivery of all questions, as well as automated skip patterns and range checks, audio-CASI and T-ACASI have been tested in a number of studies and found to be an effective way of reducing response bias, and thus, contributing to a better understanding of the prevalence and patterns of sexual and other sensitive behaviors.

Risk factors for Kaposi's-sarcoma-associated herpesvirus (KSHV/HHV-8) seropositivity in a cohort of homosexual men, 1981-1996

A newly identified herpesvirus has been associated with Kaposi's sarcoma. We determined risk factors for Kaposi's-sarcoma-associated herpesvirus/human herpesvirus 8 (KSHV/HHV-8) seropositivity and incidence of infection over time in a cohort of Danish homosexual men followed from 1981 to 1996. Antibodies to a latent nuclear (LANA) and a structural (orf65) antigen of KSHV/HHV-8 were measured by immunofluorescence and ELISA/WB respectively. Through linkage with the national AIDS registry, all cohort members diagnosed with AIDS as of September 1996 were identified and their hospital records were scrutinized to record all diagnoses of KS. Overall, 21.1% (52/246) of the men were KSHV/HHV-8-seropositive in 1981. Among the initially seronegative, the rate of KSHV/HHV-8 seroconversion was highest between 1981 and 1982 and declined steadily thereafter. In a multivariate analysis of the status at enrollment in 1981, KSHV/HHV-8 seropositivity was not associated with age but was independently associated both with number of receptive anal intercourses (OR = 2.83; p = 0.03) and with sex with US men (OR = 2.27; p < 0.05). In a multivariate analysis of follow-up data, risk of KSHV/HHV-8 seroconversion was independently associated with having visited homosexual communities in the United States, and current HIV-positive status. More than 5 years' homosexual experience was associated with an insignificantly increased risk (RR = 2.68). KS occurred only in HIV-positive men who were KSHV/HHV-8-positive at or prior to their KS diagnosis. In conclusion, KSHV/HHV-8 appears to be sexually transmitted, probably by receptive anal intercourse, and may have been introduced to Danish homosexual men via sex with US men. The epidemic of KSHV/HHV-8 is now declining. These findings are concordant with the view that KSHV/HHV-8 may have been actively spread simultaneously with and by the same activities that lead to the spread of HIV.

Human herpesvirus 8 (HHV-8) in the pathogenesis of Kaposi's sarcoma and other diseases

The discovery of Kaposi's Sarcoma-associated herpesvirus/human herpesvirus-8 (KSHV/ HHV-8) and subsequent studies of this virus have provided a body of evidence that support the concept that this is an etiologic agent for Kaposi's sarcoma (KS). Several studies have indicated that this virus may also be a causal agent for primary effusion lymphoma (PEL) and Castleman's disease as well. First generation serologic assays for HHV-8 have now been developed. The preponderance of data suggest that the incidence of HHV-8 infection is highest in populations at risk for KS: male homosexuals, immunosuppressed patients, and those who live in endemic regions. HHV-8 encodes for functional homologs of human proteins that may play a role in the development of disease. As we learn more about the steps by which this virus can lead to KS and/or other diseases, rational therapies and preventative strategies may be possible.

Foreign-protein-mediated immunodeficiency in hemophiliacs with and without HIV

Hemophilia-AIDS has been interpreted in terms of two hypotheses: the foreign-protein-AIDS hypothesis and the Human Immunodeficiency Virus (HIV)-AIDS hypothesis. The foreign-protein-AIDS hypothesis holds that proteins contaminating commercial clotting factor VIII cause immunosuppression. The foreign-protein hypothesis, but not the HIV hypothesis, correctly predicts seven characteristics of hemophilia-AIDS: 1) The increased life span of American hemophiliacs in the two decades before 1987, although 75% became infected by HIV--because factor VIII treatment, begun in the 1960s, extended their lives and simultaneously disseminated harmless HIV. After 1987 the life span of hemophiliacs appears to have decreased again, probably because of widespread treatment with the cytotoxic anti-HIV drug AZT. 2) The distinctly low, 1.3-2%, annual AIDS risk of hemophiliacs, compared to the higher 5-6% annual risk of intravenous drug users and male homosexual aphrodisiac drug users--because transfusion of foreign proteins is less immunosuppressive than recreational drug use. 3) The age bias of hemophilia-AIDS, i.e. that the annual AIDS risk increased 2-fold for each 10-year increase in age--because immunosuppression is a function of the lifetime dose of foreign proteins received from transfusions. 4) The restriction of hemophilia-AIDS to immunodeficiency diseases--because foreign proteins cannot cause non-immunodeficiency AIDS diseases, like Kaposi's sarcoma. 5) The absence of AIDS diseases above their normal background in sexual partners of hemophiliacs--because transfusion-mediated immunotoxicity is not contagious. 6) The occurrence of immunodeficiency in HIV-free hemophiliacs--because foreign proteins, not HIV, suppress their immune system. 7) Stabilization, even regeneration, of immunity of HIV-positive hemophiliacs by long-term treatment with pure factor VIII. This shows that neither HIV nor factor VIII plus HIV are immunosuppressive by themselves. Therefore, AIDS cannot be prevented by elimination of HIV from the blood supply and cannot be rationally treated with genotoxic antiviral drugs, like AZT. Instead, hemophilia-AIDS can be prevented and has even been reverted by treatment with pure factor VIII.

The epidemiology and transmission of AIDS: a hypothesis linking behavioural and biological determinants to time, person and place

Epidemiologically, the Acquired Immune Deficiency Syndrome, AIDS, is transmitted and distributed in the USA and Europe almost entirely in well-defined subsets of populations engaging in, or subjected to, the effects of behaviours which carry high risks of genital and systemic infections. The persons predominantly affected are those engaging in promiscuous homosexual and bisexual activity, regular use of addictive drugs, and their sexual and recreational partners. In such persons and in subsets of populations with corresponding life-styles, the risk of AIDS increases by orders of magnitude. Because of continuity of risk behaviour and of associated indicator infections, the incidence of AIDS over 3-5 year periods is predictable to within 10% of actual totals of registered cases in the USA and UK. Secondary transmission of AIDS beyond these groups is minimal or, in many locations, absent. There is no indication of appreciable spread by heterosexual transmission to the general population. The Human Immunodeficiency Virus, HIV, is transmissible to some extent in general populations, and more so among promiscuous persons. It may cause viraemia, lymphadenopathy and latent infection (HIV disease) in anyone. In persons engaging in risk behaviours which themselves alter or suppress immune responses, it can interact with MHC, antibodies to other organisms and to semen, and other allogenic antigens to initiate a programmed death of CD4 lymphocytes and other defensive cells, as in graft-host rejections. This occurs also in haemophiliacs receiving transfusions of blood products, and is more pronounced in persons with reactive HLA haplotypes. The susceptibility of particular subsets of populations to AIDS is thereby largely explained. But these changes occur in the absence of HIV, and so do Kaposi's sarcoma, lymphadenopathies and opportunistic infections which are regarded as main indicators of AIDS. The hypothesis that HIV-1 can do all this by itself and thereby cause AIDS is falsifiable on biological as well as epidemiological grounds. An alternative hypothesis is proposed, linking the incidence of AIDS to the evolution of contemporary risk behaviour in particular communities and locations in the USA, UK and probably in most of Europe. It does not pretend to explain the reported incidence of AIDS in Africa and other developing regions where data are insufficient to provide validation of the pattern of disease and contributory variables. The immediate, practical implication of this alternative hypothesis is that existing programmes for the control of AIDS are wrongly orientated, extremely wasteful of effort and expenditure, and in some respects harmful.

Intrarectal inoculation of macaques by the simian immunodeficiency virus, SIVmne E11S: CD4+ depletion and AIDS

Macaca nemestrina and Macaca fascicularis were inoculated with various doses of a single-cell clone of SIVmne-infected HuT 78 cells (E11S) by both the intravenous and intrarectal routes. Animals inoculated intravenously at each dose seroconverted and virus was isolated from peripheral blood mononuclear cells, but only the high-dose intrarectally exposed macaques became viremic and seroconverted. However, some seronegative, virus isolation negative intrarectally inoculated macaques showed evidence of infection and disease.

Dissent in science: styles of scientific practice and the controversy over the cause of AIDS

In this paper, we use a scientific controversy, and the efforts to legitimize and undermine a theory, to examine the co-production of facts and the rules for verifying facts over time. We discuss these processes in terms of what we call 'styles of scientific practice.' In contrast to the focus of idealist philosophers on theory production and validation as forms of logic or ways of thinking, our styles of practice also include the activities of hands and eyes and the discourses between multiple actors in diverse situations. We discuss aspects of the different styles of practice deployed by opponents in a current controversy surrounding the etiology of AIDS to understand how the same data are interpreted in different ways to support diametrically opposed views. Our study describes and examines rules of confirmation used by supporters of the theory that HIV causes AIDS. For example, we introduce an 'epidemiological' style of practice used by AIDS researchers to synthesize information to understand this disease. Styles of practice stress the historically located collective efforts of scientists, technicians, administrators, institutions, and various 'publics' as they build and sustain ways of knowing. Yet, we also show that the 'history' is also a contested construction, not a given in dusty archives. We describe the different versions of history constructed by various participants in the debate to validate their current constructions and definitions of the disease AIDS. Finally, we discuss the politics behind disease definitions and the consequences of different definitions.

T cell functions are impaired by inhaled isobutyl nitrite through a T-independent mechanism

Isobutyl nitrite is representative of a group of inhalants abused by male homosexuals and adolescents. Inhalation exposure of mice to isobutyl nitrite at 900 ppm for 45 min per day for 14 days caused serious deficits in T cell-mediated immune responses. Cytotoxic T lymphocyte (CTL) activity was reduced by 36% following the exposure. T cell proliferative responses to mitogenic and allogeneic stimulation were reduced by 37% and 51%, respectively. The exposure did not directly alter the ability of cells to synthesize or respond to IL-2. Accessory cell function in facilitating T cell activation was inhibited by about 50% following exposure to the inhalant.

Inhaled isobutyl nitrite compromises T-dependent, but not T-independent, antibody induction

Habitual abuse of nitrite inhalants has been linked in epidemiological studies with seropositivity to human immunodeficiency virus and, separately, with Kaposi's sarcoma among AIDS patients. Mice exposed to isobutyl nitrite in an inhalation chamber for 45 min/day for 14 days had depressed IgM and IgG antibody responses. The inhibition was dose-dependent at 750-900 ppm, but antibody responses were increased at an intermediate (600 ppm) dose. Gender differences in immunotoxicity were not observed. Antibody responses to a T-independent antigen (DNP-ficoll) were not affected by the immunotoxic exposure, suggesting that B-cells were refractory to the toxic exposure. Toxic exposure to isobutyl nitrite did not selectively deplete a particular spleen cell population, but caused equivalent reductions of T-cells and B-cells. Finally, exposed mice remained immunocompromised for 3-5 days after terminating exposures. Normal immune responses returned by 5-7 days, suggesting that inhibition of cellular function was reversible.

Entangled epidemics: cocaine use and HIV disease

Over the past decade, two epidemics have had a severe impact on public health in this country. These health problems involve cocaine abuse and AIDS (or HIV disease). The processes of these two conditions are clearly not independent of each other and may be quite complex. Understanding of this relationship has been hampered by a myriad of social, biological and behavioral variables that are entangled with the basic cocaine-HIV association. This article presents a paradigm for discussion of the interaction between cocaine exposure and HIV disease based on three mechanisms: the relationship between cocaine exposure and increased opportunity for HIV exposure, the direct role that cocaine plays in altering susceptibility to HIV infection, and the influence that cocaine use has on the progression of HIV disease. The goal of this structured approach is to enhance conceptual understanding of the cocaine-HIV relationship while recognizing the complexity of the issue and the limitations of current research efforts. This model will serve as a framework for the discussion of implications for future research, clinical practice, and public policy.

Possible roles for nitric oxide in AIDS and associated pathology

The endogenous free radical, nitric oxide (NO), plays a neurotransmitter-like role in vascular endothelium, a second-messenger role in N-methyl-D-aspartate (NMDA)-responsive neurons in the central nervous system (CNS), a neurotoxic role after its release from these neurons, and a cytotoxic role after its release by macrophages. NO also derives from exogenous sources, such as the nitrite inhalants, amyl, butyl and isobutyl nitrite. There is evidence that abuse of nitrite inhalants can affect immunomodulation, and epidemiological studies suggest that such abuse may be a cofactor in the pathogenesis of acquired immunodeficiency syndrome (AIDS). Hitherto, however, the potential role of NO in such pathogenesis has not been examined. This paper presents some current evidence that implicates both endogenous and exogenous sources of NO in AIDS and associated pathology.

AIDS and promiscuity: muddles in the models of HIV prevention

AIDS has been blamed on promiscuity and the promiscuous, and a major goal of many HIV-prevention programs has been to induce people to reduce the number of their sexual partners. Despite the salience of this concept in the AIDS discourse of scientists, policymakers, the media, religious leaders, and the gay community, critical analysis of the role of promiscuity in this epidemic has been lacking. Following a review of promiscuity in various genres of AIDS discourse, this article discusses promiscuity in American society and in HIV-prevention campaigns. The relative risks associated with monogamy, abstinence and promiscuity are examined, and the author concludes that the partner-reduction strategy, instead of contributing to a reduction in HIV transmission has been an impediment to AIDS prevention efforts, exacerbating the problem by undermining the sex-positive approaches to risk reduction that have proven effective. Responsibility for this misguided strategy is attributed to a moralistic approach to AIDS and to the misapplication of epidemiological concepts and inappropriate social science models to the task of promoting healthy forms of sexuality.

The role of drugs in the origin of AIDS

It is proposed that the new American and European AIDS epidemics are caused by recreational and anti-HIV drugs rather than by human immunodeficiency virus (HIV). Chronologically, the AIDS epidemic in the 1980s followed a massive escalation in the consumption of recreational drugs that started in the 1960s and 70s. Epidemiologically, both epidemics derive about 80% of their victims from the same groups of 20-44 year-olds, of which 90% are males. In America 32% of these are intravenous drug users and their children, about 60% are male homosexuals who are long-term users of oral aphrodisiac drugs and an unknown percentage are prescribed the cytotoxic DNA chain terminator AZT, as inhibitor of HIV. Direct evidence indicates that these drugs are necessary for HIV-positives and sufficient for HIV-negatives to develop AIDS diseases. The drug-AIDS hypothesis predicts correctly that: (i) AIDS is new in the US, because the drug epidemic is new, while the HIV epidemic is old--fixed at a constant 1 million Americans since 1985; (ii) despite an increase in venereal diseases, AIDS remains restricted to long-term drug users and small groups with clinical deficiencies; (iii) over 72% of AIDS occurs in 20-44 year-old males, because they make up over 80% of hard psychoactive drug use; (iv) distinct AIDS diseases correlate with the use of distinct drugs, eg Kaposi's sarcoma with nitrite inhalants, tuberculosis with intravenous drugs, and leukopenia, anemia, and nausea with AZT; (v) AIDS diseases are only acquired after long-term drug consumption, rather than after single contacts as the virus-hypothesis predicts. The drug hypothesis can be tested epidemiologically and experimentally in animals. It predicts that most AIDS can be prevented by stopping the consumption of drugs, and provides a rational basis for therapy.

AIDS acquired by drug consumption and other noncontagious risk factors

The hypothesis that human immunodeficiency virus (HIV) is a new, sexually transmitted virus that causes AIDS has been entirely unproductive in terms of public health benefits. Moreover, it fails to predict the epidemiology of AIDS, the annual AIDS risk and the very heterogeneous AIDS diseases of infected persons. The correct hypothesis must explain why: (1) AIDS includes 25 previously known diseases and two clinically and epidemiologically very different epidemics, one in America and Europe, the other in Africa; (2) almost all American (90%) and European (86%) AIDS patients are males over the age of 20, while African AIDS affects both sexes equally; (3) the annual AIDS risks of infected babies, intravenous drug users, homosexuals who use aphrodisiacs, hemophiliacs and Africans vary over 100-fold; (4) many AIDS patients have diseases that do not depend on immunodeficiency, such as Kaposi's sarcoma, lymphoma, dementia and wasting; (5) the AIDS diseases of Americans (97%) and Europeans (87%) are predetermined by prior health risks, including long-term consumption of illicit recreational drugs, the antiviral drug AZT and congenital deficiencies like hemophilia, and those of Africans are Africa-specific. Both negative and positive evidence shows that AIDS is not infectious: (1) the virus hypothesis fails all conventional criteria of causation; (2) over 100-fold different AIDS risks in different risk groups show that HIV is not sufficient for AIDS; (3) AIDS is only 'acquired,' if at all, years after HIV is neutralized by antibodies; (4) AIDS is new but HIV is a long-established, perinatally transmitted retrovirus; (5) alternative explanations disprove all assumptions and anecdotal cases cited in support of the virus hypothesis; (6) all AIDS-defining diseases occur in matched risk groups, at the same rate, in the absence of HIV; (7) there is no common, active microbe in all AIDS patients; (8) AIDS manifests in unpredictable and unrelated diseases; and (9) it does not spread randomly between the sexes in America and Europe. Based on numerous data documenting that drugs are necessary for HIV-positives and sufficient for HIV-negatives to develop AIDS diseases, it is proposed that all American/European AIDS diseases, that exceed their normal background, result from recreational and anti-HIV drugs. African AIDS is proposed to result from protein malnutrition, poor sanitation and subsequent parasitic infections. This hypothesis resolves all paradoxes of the virus-AIDS hypothesis. It is epidemiologically and experimentally testable and provides a rational basis for AIDS control.