Autonomic neuropathy in patients with HIV: course, impact of disease stage, and medication

Article Topic: Neuropathies Due to Infections and Antimicrobial Treatments

Purpose of eview

The aim of this review is to discuss the presentation, diagnosis, and management of polyneuropathy (PN) in selected infections. Overall, most infection related PNs are an indirect consequence of immune activation rather than a direct result of peripheral nerve infection,  Schwann cell infection, or toxin production, though note this review will describe infections that cause PN through all these mechanisms. Rather than dividing them by each infectious agent separately, we have grouped the infectious neuropathies according to their presenting phenotype, to serve as a guide to clinicians. Finally, toxic neuropathies related to antimicrobials are briefly summarized.

Recent findings

While PN from many infections is decreasing, increasing evidence links infections to variants of GBS. Incidence of neuropathies secondary to use of HIV therapy has decreased over the last few years.

Summary

In this manuscript, a general overview of the more common infectious causes of PN will be discussed, dividing them across clinical phenotypes: large- and small-fiber polyneuropathy, Guillain-Barré syndrome (GBS), mononeuritis multiplex, and autonomic neuropathy. Rare but important infectious causes are also discussed.

Direct and indirect cardiovascular and cardiometabolic sequelae of the combined anti-retroviral therapy on people living with HIV

With reports of its emergence as far back as the early 1900s, human immunodeficiency virus (HIV) has become one of the deadliest and most difficult viruses to treat in the era of modern medicine. Although not always effective, HIV treatment has evolved and improved substantially over the past few decades. Despite the major advancements in the efficacy of HIV therapy, there are mounting concerns about the physiological, cardiovascular, and neurological sequelae of current treatments. The objective of this review is to (Blattner et al., Cancer Res., 1985, 45(9 Suppl), 4598s-601s) highlight the different forms of antiretroviral therapy, how they work, and any effects that they may have on the cardiovascular health of patients living with HIV, and to (Mann et al., J Infect Dis, 1992, 165(2), 245-50) explore the new, more common therapeutic combinations currently available and their effects on cardiovascular and neurological health. We executed a computer-based literature search using databases such as PubMed to look for relevant, original articles that were published after 1998 to current year. Articles that had relevance, in any capacity, to the field of HIV therapy and its intersection with cardiovascular and neurological health were included. Amongst currently used classes of HIV therapies, protease inhibitors (PIs) and combined anti-retroviral therapy (cART) were found to have an overall negative effect on the cardiovascular system related to increased cardiac apoptosis, reduced repair mechanisms, block hyperplasia/hypertrophy, decreased ATP production in the heart tissue, increased total cholesterol, low-density lipoproteins, triglycerides, and gross endothelial dysfunction. The review of Integrase Strand Transfer Inhibitors (INSTI), Nucleoside Reverse Transcriptase Inhibitors (NRTI), and Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTI) revealed mixed results, in which both positive and negative effects on cardiovascular health were observed. In parallel, studies suggest that autonomic dysfunction caused by these drugs is a frequent and significant occurrence that needs to be closely monitored in all HIV + patients. While still a relatively nascent field, more research on the cardiovascular and neurological implications of HIV therapy is crucial to accurately evaluate patient risk.

The Effects of Acute Aerobic Exercise on Blood Pressure, Arterial Function, and Heart Rate Variability in Men Living With HIV

PURPOSE

This study aims to investigate the effects of acute cycling on blood pressure (BP), arterial function, and heart rate variability (HRV) in men living with HIV (MLHIV) using combined antiretroviral therapy (cART).

METHODS

Twelve MLHIV (48.7 ± 9.2 years; 25.2 ± 2.8 kg m-2) and 13 healthy controls (41.2 ± 9.9 years; 26.3 ± 2.9 kg m-2) performed a cycling bout (ES) (intensity: 50% oxygen uptake reserve; duration: time to achieve 150 kcal-MLHIV: 24.1 ± 5.5 vs. controls: 23.1 ± 3.0 min; p = 0.45), and a 20-min non-exercise session (NES).

RESULTS

At rest (p < 0.05), MLHIV presented higher brachial systolic/diastolic BP (SBP/DBP: 123.2 ± 14.2/76.8 ± 6.3 vs. 114.3 ± 5.1/71.6 ± 2.6 mmHg) and central BP (cSBP/cDBP: 108.3 ± 9.3/76.5 ± 6.5 vs. 101.6 ± 4.9/71.3 ± 4.4 mmHg) vs. controls but lower absolute maximal oxygen uptake (2.1 ± 0.5 vs. 2.5 ± 0.3 L min-1) and HRV indices reflecting overall/vagal modulation (SDNN: 24.8 ± 7.1 vs. 42.9 ± 21.3 ms; rMSSD: 20.5 ± 8.5 vs. 38.1 ± 22.8 ms; pNN50: 3.6 ± 4.2 vs. 13.6 ± 11.3%). DBP postexercise lowered in controls vs. MLHIV (∼4 mmHg, p < 0.001; ES: 0.6). Moreover, controls vs. MLHIV had greater reductions (p < 0.05) in augmentation index (-13.6 ± 13.7 vs. -3.1 ± 7.2% min-1; ES: 2.4), and HRV indices up to 5 min (rMSSD: -111.8 ± 32.1 vs. -75.9 ± 22.2 ms min-1; ES: 3.8; pNN50: -76.3 ± 28.3 vs. -19.0 ± 13.7% min-1; ES: 4.4). Within-group (ES vs. NES; p < 0.05) reductions occurred in controls for SBP (∼10 mmHg, 2 h), DBP (∼6 mmHg, 20, 30, and 70 min), cSBP (∼9 mmHg, 30 min), cDBP (∼7 mmHg, 30 and 70 min), augmentation index (∼10%, 30 min), and pNN50 (∼20%; up to 2 h), while in MLHIV only cSBP (∼6 mmHg, 70 min) and cDBP (∼4 mmHg, 30 min) decreased. Similar increases (up to 5 min) in heart rate (∼22 bpm) and decreases in SDNN (∼18 ms) and rMSSD (∼20 ms) occurred in both groups.

CONCLUSION

MLHIV under cART exhibited attenuated postexercise hypotension vs. healthy controls, which seemed to relate with impairments in vascular function.

Remission of progressive multifocal leukoencephalopathy in HIV- positive patient after multidisciplinary rehabilitation: a case report

Introduction: One of the most common neurologic disease in Acquired Immunodeficiency Syndrome (AIDS) caused by Human Immunodeficiency Virus (HIV) is represented by progressive multifocal leukoencephalopathy (PML), being caused by John Cunningham (JC) polyoma virus. Case presentation: We report a case of a 27 years old women, HIV-positive since childhood, under specific antiretroviral therapy with good adherence to it in that period but starting with adolescence adherence to highly active antiretroviral therapy (HAART) decreased. In this context her HIV viral load increased to a 690.000 copies/ml, and CD4 collapsed at 57 cells/mmc. She presented in our clinic with ataxic left hemiparesis, truncal ataxia and left hemi-hypoesthesia. Cerebrospinal fluid (CSF) showed a slightly pleocytosis and polymerase chain reaction performed from CSF diagnosed John Cunningham (JC) virus. Once diagnosis established, we reinitiated HAART, but some neurologic disorders persisted like difficulty of the left upper member, having the modified Rankin scale (mRS) of 5. The patient started a multidisciplinary rehabilitation (MDR) treatment, specifically adapted. It consisted of 4 sessions of neuromotor treatments, 20 sessions of massages, and 12 sessions of occupational therapy. According to MDR, the patient improved the ataxic walking, without support, presenting an improvement mRS of 3. Conclusions: AIDS patients with PML could require a prolonged MDR treatment for neurological disorders and rehabilitation treatment promptly should be applied when such diagnosis is suspected. Key words: progressive multifocal leukoencephalopathy, human immunodeficiency virus, neurological disorder, multidisciplinary rehabilitation,

The Study of Gonadal Hormonal Abnormalities and Sexual Dysfunction in HIV Positive Females: An Exploratory Study

INTRODUCTION

Every endocrine gland has been reported to be affected at varying rates in HIV. HIV is a highly stigmatized chronic disease with a substantial co-occurrence of mental and sexual health problems; however the sexual health problems in women have not been extensively studied.

AIM

To study the gonadal hormonal abnormalities and sexual dysfunction in HIV positive female patients and its possible association.

MATERIALS AND METHODS

This descriptive/exploratory study was conducted in the Department of General Medicine at a tertiary care hospital from September 2013 to August 2015. The study group included 50 diagnosed HIV-positive patients. They were also subjected to specific questions regarding sexual dysfunction by female counselors using female sexual function index. Visits of the subjects were scheduled independent of the menstrual cycle. Hormonal levels (free testosterone, FSH, LH) were measured.

RESULTS

Out of 50 patients, 26 patients in our study had sexual dysfunction (52%). Patients with age group between 30-39 years had the maximum sexual dysfunction compared to the other groups (<0.001). Patients with a CD4 count between 200 and 499 had the maximum sexual dysfunction (<0.02). Mean duration of HIV in the study was 30 months in sexual dysfunction group which was significant (p<0.005). Hormonal levels were found to be in normal range. All the study patients reported desire, arousal and lubrication problems whereas orgasm and satisfaction problems were noted in 60% patients with pain reported in 52%.

CONCLUSION

We identified that although the hormonal levels were in the normal range, they were comparatively in the lower range in the dysfunction group than the non-dysfunctional group. Both free testosterone and FSH levels were low indicating involvement of the pituitary rather than the gonads. We also conclude that duration of HIV and also level of CD4 count is related to sexual dysfunction.

Cardiac Involvement in Peripheral Neuropathies

Cardiac autonomic neuropathy (CAN) is the least recognized and understood complication of peripheral neuropathy. However, because of its potential adverse effects including sudden death, CAN is one of the most important forms of autonomic neuropathies. CAN presents with different clinical manifestations including postural hypotension, exercise intolerance, fluctuation of blood pressure and heart rate, arrhythmia, and increased risk of myocardial infarction. In this article, the prevalence, clinical presentations, and management of cardiac involvement in certain peripheral neuropathies, including diabetic neuropathy, Guillain-Barré syndrome, chronic inflammatory polyneuropathy, human immunodeficiency virus-associated neuropathy, hereditary neuropathies, and amyloid neuropathy are examined in detail.

Autonomic dysfunction is common in HIV and associated with distal symmetric polyneuropathy

Neurologic complications of HIV are well characterized in the central and peripheral nervous systems but not in the autonomic nervous system, perhaps due to the complexities of measuring autonomic function in medically ill populations. We hypothesized that autonomic dysfunction is common in HIV, can be meaningfully measured with an autonomic reflex screen, and is associated with distal symmetric polyneuropathy (DSP) but not with signs of CNS disease. We also sought to characterize immunovirologic and medical factors associated with autonomic dysfunction. We assessed 102 HIV-infected adults for autonomic dysfunction with a laboratory-based autonomic reflex screen summarized as the composite autonomic severity score (CASS). The total neuropathy score (TNS) was used to quantify DSP based on neurologic interview/examination, quantitative sensory testing, and nerve conduction studies. Autonomic dysfunction was common, with a CASS  ≥  3 in 61 % of participants, of whom 86 % were symptomatic. Greater CASS abnormalities demonstrated univariate association with increasing TNS, age, viral load, hypertension, and use of medications (particularly anticholinergics), but not with antiretrovirals, current/nadir CD(4+) count, HIV duration, metabolic factors, or signs of CNS disease. The TNS was the only significant predictor of the CASS in multivariate analysis; anticholinergic medications were marginally significant. This study demonstrates that autonomic dysfunction is common and frequently symptomatic in HIV and that an autonomic reflex screen, adjusted for anticholinergic medication, is useful in its assessment. Association of autonomic dysfunction with DSP suggests common factors in their pathogenesis, and autonomic neuropathy may be part of the spectrum of HIV-associated peripheral nerve pathologies.

A Case of Possible Darunavir/Ritonavir-Induced Peripheral Neuropathy

A 65-year-old man, M.S.M., known as being HIV infected for 20 years, presented with muscle ache and progressive weakness 3 months after initiation of darunavir as a part of his antiretroviral therapy (ART). The patient's treatment included darunavir/ritonavir 600/100 mg twice daily, plus a backbone of didanosine and abacavir which were the backbone in his previous regimen for several years according to his drug resistance profile. Three months after initiation of darunavir/ritonavir the patient exhibited clinical symptoms of severe pain and progressive weakness of his lower limbs; he was unable to walk and was totally wheelchair-bound. Severe sensory peripheral polyneuropathy was revealed on electromyogram (EMG). All medications, including ART, were stopped. Within two months, concomitantly with initiation of raltegravir, etravirine and emcitricabine/tenofovir, the patient recovered, gained weight, resumed walking and his CD4 counts rose from 270 to 450 cells/mm3. A second EMG study 3 months after initiation of his new ART regimen showed compete recovery of the previously diagnosed peripheral neuropathy. In this report, we present a case of severe HIV-1-related acute demyelinating polyneuropathy which initiated after new generation PI darunavir/ritonavir was given and resolved after cessation of the drug without the use of immune-based therapies. The variety of HIV-related polyneuropathies will be discussed.

HIV peripheral neuropathy

Peripheral neuropathies are the most common neurological manifestations occurring in HIV-infected individuals. Distal symmetrical sensory neuropathy is the most common form encountered today and is one of the few that are specific to HIV infection or its treatment. The wide variety of other neuropathies is akin to the neuropathies seen in the general population and should be managed accordingly. In the pre-ART era, neuropathies were categorized according to the CD4 count and HIV viral load. In the early stages of HIV infection when CD4 count is high, the inflammatory demyelinating neuropathies predominate and in the late stages with the decline of CD4 count opportunistic infection-related neuropathies prevail. That scenario has changed with the present almost universal use of ART (antiretroviral therapy). Hence, HIV-associated peripheral neuropathies are better classified according to their clinical presentations: distal symmetrical polyneuropathy, acute inflammatory demyelinating polyradiculoneuropathy (AIDP) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), mononeuropathies, mononeuropathies multiplex and cranial neuropathies, autonomic neuropathy, lumbosacral polyradiculomyelopathy, and amyotrophic lateral sclerosis (ALS)-like motor neuropathy. Treated with ART, HIV-infected individuals are living longer and are at a higher risk of metabolic and age-related complications; moreover they are also prone to the potentially neurotoxic effects of ART. There are no epidemiological data regarding the incidence and prevalence of the peripheral neuropathies. In the pre-ART era, most data were from case reports, series of patients, and pooled autopsy data. At that time the histopathological evidence of neuropathies in autopsy series was almost 100%. In large prospective cohorts presently being evaluated, it has been found that 57% of HIV-infected individuals have distal symmetrical sensory neuropathy and 38% have neuropathic pain. It is now clear that distal symmetrical sensory neuropathy is caused predominantly by the ART's neurotoxic effect but may also be caused by the HIV itself. With a sizeable morbidity, the neuropathic pain caused by distal symmetrical sensory neuropathy is very difficult to manage; it is often necessary to change the ART regimen before deciding upon the putative role of HIV infection itself. If the change does not improve the pain, there are few options available; the most common drugs used for neuropathic pain are usually not effective. One is left with cannabis, which cannot be recommended as routine therapy, recombinant human nerve growth factor, which is unavailable, and topical capsaicin with its side-effects. Much has been done to and learned from HIV infection in humans; HIV-infected individuals, treated with ART, are now dying mostly from cardiovascular disease and non-AIDS-related cancers. It hence behooves us to find new approaches to mitigate the residual neurological morbidity that still impacts the quality of life of that population.

Neuromuscular manifestations of HIV/AIDS

The human immunodeficiency virus (HIV) epidemic, now entering its fourth decade, affects approximately 33 million people living in both developed and resource-limited countries. Neurological complications of the peripheral nervous system are common in HIV-infected patients, and neuromuscular pathology is associated with significant morbidity. Peripheral neuropathy is the most common neuromuscular manifestation observed in HIV/AIDS, and in the antiretroviral era, its prevalence has increased. The purpose of this review was to describe the clinical spectrum of neuromuscular disorders in the setting of HIV infection and to provide an approach to diagnosis and management.

Epidemiology of HIV-related neuropathy: a systematic literature review

We sought to identify and summarize the incidence and prevalence of neuropathy among HIV patients and subgroups. A systematic search of the literature was performed using MEDLINE and EMBASE. The relevant literature was identified based on predefined criteria. Prevalence data were collected from cross-sectional and cohort studies. Incidence data were collected from cohort and case-control studies. Thirty-seven studies were included of which there were 23 cohort studies, 13 cross-sectional studies, and one case-control study. The prevalence of neuropathy among HIV patients derived from 25 studies varied from 1.2% to 69.4%. Regarding the development of neuropathy among HIV-positive patients, standardized by study duration, the rates per 100 person-years ranged from 0.7 to 39.7. Among older patients there is a greater risk of neuropathy. The same seems to be the case for patients with more severe disease. Currently available studies providing information on the incidence and prevalence of neuropathy among HIV patients suggest a significant burden, but there is a great variation in results across studies. There is no definitive explanation for the variation. However, it underscores the fact that complexity of the disease, along with absence of standardized diagnostic criteria, has considerably influenced the methodologies and outcomes of the studies.

Decreased heart rate variability in HIV positive patients receiving antiretroviral therapy: importance of blood glucose and cholesterol

The presence of autonomic dysfunction in HIV patients is largely unknown. Early studies found autonomic dysfunction in patients with AIDS. Antiretroviral combination therapy (ART) has dramatically changed the course of the disease and improved prognosis and decreased morbidity.

AIM

To evaluate whether autonomic dysfunction is present in an ART treated HIV population and if so to identify factors of importance.

METHODS

HIV patients receiving ART for at least 12 months (n = 97) and an age-matched control group of healthy volunteers (n = 52) were included. All were non-diabetic and had never received medication for hypertension. Following a 10 min resting period a 15 min ECG recording was performed. Heart-rate variability (HRV) analysis was performed in accordance with current guidelines and data reported as mean [interquartile range].

RESULTS

Mean normal-to-normal (NN) and total HRV measured as standard deviation of normal-to-normal (SDNN) was lower in HIV patients compared to controls (905 vs. 982 ms; p<0.001 and 48 vs. 54 ms; p = 0.028, respectively). No differences were found between the groups in parasympathetic activity measured as square root of the mean squared difference of successive NN-intervals (RMSSD) or the percent of differences between adjacent NN intervals greater than 50 ms (pNN50). In the HIV positives, haemoglobin A1c correlated inversely with SDNN, RMSSD and pNN50 (p<0.05). Total cholesterol and LDL-C correlated inversely with RMSSD and pNN50 (p<0.05). Neither HIV duration, HIV-RNA, CD4 cell count nor CD4 nadir correlated with time or phase domain HRV variables.

CONCLUSIONS

Moderate autonomic dysfunction is present in HIV positives patients even with suppressed viral load due to ART. The dysfunction is correlated with HbA1c and hypercholesterolemia but not to duration of HIV or whether the patients were receiving protease inhibitors as part of the ART regime.

NeuroAIDS: an evolving epidemic

Over 60,000 Canadians are infected with human immunodeficiency virus (HIV). Greater than 50% of these individuals will develop a neurological disorder despite the availability of highly active antiretroviral therapy. HIV causes nervous system disease at all stages of infection with adverse effects on quality of life, adherence to medications, employment and survival. These disorders include opportunistic infections in addition to distinct HIV-associated neurological syndromes and undesirable treatment-related effects. The latter two groups of disorders are often undiagnosed and untreated in both adolescents and adults. Direct HIV infection of central nervous system causes HIV-associated dementia, which is a progressive subcortical dementia. HIV infection of the peripheral nervous system produces a painful sensory neuropathy termed distal sensory polyneuropathy, which may be exacerbated by several antiretroviral drugs. Other important HIV-induced neurological disorders include vacuolar myelopathy and an increased risk of seizures. Future issues that will confound the presentation and treatment of HIV-induced nervous system disorders include the increasing prevalence of drug-resistant HIV strains, increasing age of HIV-infected patients, hepatitis C virus co-infection and the Immune Reconstitution Inflammatory Syndrome. Herein, we review the clinical presentations, underlying pathogenesis and treatments of this burgeoning group of neurological disorders.

Letrozole Versus Testosterone. A Single-Center Pilot Study of HIV-Infected Men Who Have Sex with Men on Highly Active Anti-Retroviral Therapy (HAART) with Hypoactive Sexual Desire Disorder and Raised Estradiol Levels

INTRODUCTION

Since the advent of Highly Active Anti-Retroviral Therapy (HAART), men with HIV experience good quality of life and expect to have normal sexual function. However, it appears that men infected with HIV commonly complain of sexual problems. There is evidence that men on HAART develop low sexual desire that is associated with raised estradiol levels. It has been postulated that abnormal metabolism seen in this group of men increases the aromatization of testosterone to estradiol. We hypothesized that letrozole, an aromatase inhibitor that inhibits the conversion of testosterone to estradiol, would be beneficial in these men.

AIM

The aim of this study was to compare the effects of testosterone vs. an aromatase inhibitor, letrazole, in HIV-infected men with raised estradiol and low sexual desire.

METHODS

Thirteen men who have sex with men on HAART with low sexual desire as well as raised estradiol levels (>120 pmol/L) were randomly allocated to receive either parenteral testosterone (Sustanon 250 intramuscular injection) (N = 6) or letrozole 2.5 mg orally daily (N = 7) for 6 weeks.

MAIN OUTCOME MEASURES

Sex steroid hormone assays, sex hormone-binding globulin, virological, hematological, and biochemical parameters were measured before and after treatment. Each subject was given the Spector Sexual Desire Inventory and the Depression/Anxiety Stress Scale before and immediately after treatment. Subjects were also asked to estimate the number of actual sexual acts before and after treatment. Results. Inventory data showed a rise in dyadic desire in both treatment arms. Mean actual sexual acts rose from 0.33 to 1.5 in the testosterone group and from 0.43 to 1.29 for the letrozole group. Luteinizing hormone increased in seven of seven men on letrozole. Serum testosterone increased in seven of seven men on letrozole. There were no adverse events from either medication.

CONCLUSION

Letrozole may be useful in the management of men on HAART who have low sexual desire.

Modulation of host immunity by HIV may be partly achieved through usurping host autonomic functions

Modulation of host immunity has been observed in human immunodeficiency virus (HIV) infections. HIV is believed to influence host immunity through a variety of mechanisms including direct effects on host T cell survival, indirect effects on cytokine profile through modulation of immune cells, and modulation of endocrine functions that affect immunity such as steroids. We hypothesize that HIV infection may also alter host immunity through modulation of host sympatho-vagal balance. Specifically, we propose that HIV drives autonomic balance towards sympathetic bias, which can contribute to a T helper (Th)2 type immunity. A variety of paraviral syndromes associated with HIV infection such as QT prolongation, cachexia, cardiomyopathy, and lipodystrophy are consistent with evidence of autonomic dysfunction. Immunomodulatory effects of autonomic dysfunction toward Th2 bias are presented. A plausible mechanism by which HIV can influence autonomic balance through hypothalamic manipulation is offered. Shift to Th2 dominance is associated with HIV disease progression and can be viewed as a viral adaptation to promote its own survival. Autonomic remodeling by HIV may exemplify this phenomenon. Our hypothesis has implications for treatment of HIV and its associated syndromes.

Growth hormone treatment improves peripheral muscle oxygen extraction-utilization during exercise in patients with human immunodeficiency virus-associated wasting: a randomized controlled trial

The arteriovenous oxygen difference (a-vO(2) difference), a measure of peripheral muscle oxygen extraction-utilization during exercise, is reduced in antiretroviral-treated patients with human immunodeficiency virus (HIV), thus causing a shift in the cardiac output-oxygen consumption (Q-VO(2)) relationship. We investigated the impact of recombinant human GH (rhGH) treatment on a-vO(2) difference and the Q-VO(2) relationship during submaximal exercise by randomizing 12 HIV-infected patients (mean +/- sem: age, 43.3 +/- 1.5 yr; body mass, 69.5 +/- 2.9 kg; body mass index, 22.4 +/- 0.9 kg/m(2); maximum oxygen consumption, 33.6 +/- 1.5 ml/kg x min), with documented unintentional weight loss (>or=10% within the preceding 12 months) despite antiretroviral therapy, to receive 3 months of rhGH (6 mg/d) in a double-blind, placebo-controlled, cross-over trial. We assessed Q (determined noninvasively using CO(2) rebreathing), and subsequently a-vO(2) difference, from Q-VO(2) relationships. At study entry, the mean slope (8.1 +/- 1.0 liters/min x 1-liter increase in VO(2)) and intercept (3.1 +/- 1.3 liters/min), generated from each patient's Q-VO(2) relationship, were greater and lower, respectively, than those reported for healthy individuals (6.0 and 4.0, respectively), thereby indicating a deficit in the a-vO(2) difference. After 3 months of rhGH treatment, the slope decreased to 7.0, and the intercept increased to 3.5. After 1 month of rhGH treatment, the a-vO(2) difference (at a VO(2) of 1250 ml/min) significantly (P < 0.05) increased (17.1 +/- 8.9%) from baseline (9.92 +/- 0.51 ml/dl) and remained elevated (10.39 +/- 0.48 ml/dl) after 3 months of treatment. No significant changes were seen with placebo. Therefore, treatment with rhGH leads to an improvement in peripheral muscle oxygen extraction-utilization and the Q-VO(2) relationship during exercise in patients with HIV-associated wasting despite antiretroviral therapy.

Psychological risk factors for HIV pathogenesis: mediation by the autonomic nervous system

BACKGROUND

Epidemiologic studies have identified psychological risk factors for specific physical diseases, but the biological mechanisms mediating these relationships remain poorly defined.

METHODS

Social inhibition and autonomic nervous system (ANS) activity were assessed on multiple occasions in 54 gay men with asymptomatic human immunodeficiency virus (HIV) infection. Following baseline ANS assessment, plasma HIV-1 viral load and CD4+ T cell levels were monitored for 12-18 months to assess relationships between ANS activity and HIV pathogenesis.

RESULTS

We confirmed the previously reported relationship between socially inhibited temperament and vulnerability to viral pathology. Plasma viral load set-point was elevated eight-fold in socially inhibited individuals, and these individuals showed poorer virologic and immunologic response to initiation of highly active antiretroviral therapy (HAART). Effects were independent of duration of infection, HAART regimen, demographic characteristics, and health-relevant behavior. Neurophysiologic assessments documented elevated ANS activity in socially inhibited individuals, and mediational analyses showed that such differences could account for 64%-92% of the covariance between social inhibition and virologic parameters.

CONCLUSIONS

These data provide the first clinical evidence that differential neural activity mediates relationships between psychological risk factors and infectious disease pathogenesis. Such findings also suggest novel targets for adjunctive therapy in long-term control of HIV-1 disease.

Decreased peak arteriovenous oxygen difference during treadmill exercise testing in individuals infected with the human immunodeficiency virus

OBJECTIVE

To determine if arteriovenous oxygen difference was lower in asymptomatic individuals with human immunodeficiency virus (HIV) infection than in sedentary but otherwise healthy controls.

DESIGN

Quasi-experimental cross-sectional.

SETTING

Clinical exercise laboratory.

PARTICIPANTS

Fifteen subjects (10 men, 5 women) with HIV and 15 healthy gender- and activity level-matched controls (total N=30).

INTERVENTION

Participants performed an incremental maximal exercise treadmill test to exhaustion. Electrocardiogram, metabolic, and noninvasive cardiac output measurements were evaluated at rest and throughout the tests. Data were analyzed by using analysis of covariance.

MAIN OUTCOME MEASURES

Peak oxygen consumption (Vo(2)), cardiac output, stroke volume, and arteriovenous oxygen difference. The arteriovenous oxygen difference was determined indirectly using the Fick equation.

RESULTS

Peak VO(2) was significantly lower (P<.0005) in participants with HIV (24.6+/-1.2mL.kg(-1).min(-1)) compared with controls (32.0+/-1.2mL.kg(-1).min(-1)). There were no significant intergroup differences in cardiac output or stroke volume at peak exercise. Peak arteriovenous oxygen difference was significantly lower (P<.04) in those infected with HIV (10.8+/-0.5 volume %) than in controls (12.4+/-0.5 volume %).

CONCLUSION

The observed deficit in aerobic capacity in the participants with HIV appeared to be the result of a peripheral tissue oxygen extraction or utilization limitation. In addition to deconditioning, potential mechanisms for this significant attenuation may include HIV infection and inflammation, highly active antiretroviral therapy medication regimens, or a combination of these factors.

Modulating effect of respiration on atrioventricular conduction time assessed using PR interval variation

Respiratory sinus arrhythmia (RSA) is the variation of heart rate (or RR interval) in phase with respiration and has been extensively studied. However, the effect of respiration on atrioventricular conduction delay (and hence PR interval length) has not yet received much attention. This work reports on measurements of respiration and associated RR and PR variability, in 11 subjects, assessed through surface electrocardiogram measurements, for both paced and spontaneous respiration in the supine position. A wavelet-based approach was used to extract RR and PR intervals. The accuracy of RR and PR interval measurement was consistent with previously published work. Respiratory atrioventricular conduction delay variability (RCV) was assessed using three techniques: spectral, peak-to-trough and cosinor methods. All measures showed statistically significant variations in PR interval due to respiration during paced respiration at 6 min(-1). Of the three measures, cosinor analysis was most reliable in highlighting RCV. Using this measure, statistically significant RCV was seen in ten out of the 11 subjects during paced respiration. The magnitude of the variability was estimated as +/- 5.9% of the mean PR interval. In spontaneous respiration, statistically significant RCV was seen in approximately half of the subjects, with an estimated variability of +/- 1.5%. As a control, statistically significant values for RSA were also obtained from the same data, which agreed with previously published measurements. It was concluded that respiration does indeed modulate atrioventricular conduction delay, deep breathing in the supine position accentuates this effect, and cosinor analysis provides a reliable means for quantifying this effect.

Epidemiology and clinical features of HIV-1 associated neuropathies

Peripheral neuropathy is common in human immunodeficiency virus type-1 (HIV-1) infection. Peripheral neuropathies complicate all stages of the HIV-1 disease and cause considerable morbidity and disability in HIV-1 infected individuals and acquired immunodeficiency syndrome (AIDS) patients. Whereas symptomatic neuropathies occur in approximately 10% to 15% of HIV-1-infected patients overall, pathologic evidence of peripheral nerve involvement is present in virtually all end-stage AIDS patients. There are 6 major clinical types of HIV-associated neuropathies that are regularly seen in large HIV-1 clinics. Distal sensory polyneuropathy (DSP) is the most common among the HIV-1-associated neuropathies. DSP generally occurs in later stages of HIV-1 infection and it follows an indolent and protracted clinical course. The dominant clinical features in DSP include distal pain, paresthesia and numbness in a typical length-dependent fashion with proximal to distal gradient. Whereas toxic neuropathies--secondary to certain antiretroviral agents--are clinically similar to DSP, their temporal relation to neurotoxic medication helps distinguish them from other HIV-1-associated neuropathies. DSP and toxic neuropathy may coexist in a single patient. Acute and chronic inflammatory demyelinating polyradiculoneuropathies (AIDP and CIDP) produce global limb weakness. AIDP may occur at seroconversion and it can therefore be the initial manifestation of HIV-1 infection. CIDP generally occurs in the mid to late stages of HIV-1 infection. Progressive polyradiculopathy (PP) occurs in patients with advanced immunodeficiency and is generally caused by the opportunist cytomegalovirus (CMV) infection. Mononeuropathy multiplex (MM) in early stages of HIV-1 infection is immune mediated, whereas in advanced AIDS it is caused by the CMV infection. Finally, subclinical autonomic nervous system involvement is common in all stages of HIV-1 infection. Because HIV-1-associated neuropathies are diverse in their etiology and pathogenesis, a precise clinical diagnosis is required to formulate a rational therapeutic intervention.