An unbiased method for estimation of total epidermal nerve fibre length

It is of interest to quantify accurately lineal biological features such as nerve fibres, capillaries, and tubules for studies of development and diseases such as sensory neuropathy, and for evaluation of therapeutic regimens in humans and animal models. An unbiased stereological method to sample and estimate total length of immunostained epidermal nerve fibres by using vertical sections of punch skin biopsies from two human volunteers is presented. The essential steps in the procedure are as follows: (1) serially section the skin punch in a random plane perpendicular to the cutaneous surface; (2) immunostain a known fraction of total sections with antibody specific for nerve fibres; (3) orient a test line-grid over the epidermis; and (4) count intersections between test lines and immunostained epidermal nerve fibres. The optical fractionator method is employed to estimate total length of immunostained epidermal nerve fibres in the biopsy. By using these techniques the total length of nerve fibre in a defined region can be determined without methodological bias, assumptions or correction factors.

Stereological analysis of cerebral atrophy in human immunodeficiency virus-associated dementia

Brain atrophy is a common finding in patients with AIDS, but the relationship of atrophy to HIV-associated dementia is unclear. We used unbiased, stereological methods on postmortem brain specimens to estimate volumes of different brain regions in patients prospectively diagnosed with and without HIV-associated dementia. Thirty HIV-seropositive (9 without AIDS/without dementia, 6 with AIDS/without dementia, 15 with AIDS/with dementia) and 7 HIV-seronegative controls were studied using the technique of point counting and Cavalieri's principle of volume estimation. There was a significant reduction in the mean neocortical volume (15%, p = 0.032) in the group with AIDS when compared to the seronegative controls, and this difference was accentuated when comparing only the group with HIV-associated dementia to the seronegatives (neocortex: 18%, p = 0.020). There were no significant differences between the AIDS groups with and without HIV-associated dementia, although there was a trend for smaller volumes in the most severely demented patients. There were no differences in white matter volumes between groups. In conclusion, patients dying with AIDS and particularly those with HIV-associated dementia, show significant neocortical atrophy when compared to seronegative controls. The lack of a significant difference in cerebral atrophy between HIV-seropositive patients with and without dementia suggests that atrophy may be a more generalized phenomenon of AIDS as opposed to a specific marker for HIV-associated dementia.

Localization of HIV-1 in human brain using polymerase chain reaction/in situ hybridization and immunocytochemistry

Human immunodeficiency virus type 1 (HIV-1) infects the brains of a majority of patients with the acquired immunodeficiency syndrome (AIDS), and has been linked to the development of a progressive dementia termed "HIV-associated dementia." This disorder results in severe cognitive, behavioral, and motor deficits. Despite this neurological dysfunction, HIV-1 infection of brain cells does not occur significantly in neurons, astrocytes, or oligodendrocytes, but is restricted to brain macrophages and microglia. To identify possible low-level or latent infection of other brain cells, we combined the techniques of the polymerase chain reaction with in situ hybridization for the detection of HIV DNA, and used immunocytochemistry to identify the HIV-expressing cells. In the 21 adult brains studied (15 AIDS and 6 seronegative control brains), we found that polymerase chain reaction/in situ hybridization was both sensitive and specific for identifying HIV-infected cells. In all brains, the majority of infected cells were macrophages and microglia. In several brains, however, a substantial minority of cells harboring HIV DNA were identified as astrocytes. Neurons, oligodendrocytes, and endothelial cells were not infected with HIV, even in cases with HIV-associated dementia. These findings confirm previous data regarding the importance of macrophage/microglial infection, and essentially exclude neuronal infection in pathogenetic models of HIV-associated neurological disease. These data also demonstrate that latent or low-level infection of astrocytes occurs in AIDS, a finding that may be of importance in understanding HIV neuropathogenesis.

Neuroepidemiology of HIV infection

There are a variety of HIV-related neurologic complications that have numerous causes. HIV-related neurologic illnesses are specific to the stage of HIV infection, although the greatest burden of neurologic disease and the most disabling syndromes occur in the more advanced stages. As the number of HIV-infected persons continues to increase worldwide and as antiretroviral and other anti-infective therapies improve patient survival in the advanced stages of HIV infection, the burden of neurologic disease will continue to increase.

Low-dose zalcitabine-related toxic neuropathy: frequency, natural history, and risk factors

We studied the features and frequency of sensory neuropathy among 79 HIV-1-infected individuals participating in a multicenter clinical trial of zalcitabine (2'3'-dideoxycytidine, or ddC) antiretroviral therapy. The trial compared zalcitabine monotherapy (2.25 mg/day) versus combination therapy (2.25 mg/day ddC) with zidovudine (ZDV, formerly AZT) versus monotherapy with ZDV alone. Neuropathy developed in 34% of ddC recipients but in only 4% of comparable patients treated with ZDV alone--a 7.9-fold increase in the attack rate of neuropathy. Using risk factor analysis, we found that diabetes mellitus was significantly associated with the development of toxic neuropathy (p = 0.02), and weight loss may contribute to its appearance. Like HIV-associated sensory neuropathy, ddC-related toxic neuropathy is a predominantly sensory, length-dependent, symmetric, painful neuropathy. Dose reduction lessened the severity of symptoms, although objective signs of neuropathy persisted. Patients with subclinical neuropathies or significant neuropathy risks such as diabetes may be poor candidates for ddC therapy.

Quantitation of human immunodeficiency virus in brains of demented and nondemented patients with acquired immunodeficiency syndrome

We measured human immunodeficiency virus (HIV) DNA in brains of 15 patients who died with acquired immunodeficiency syndrome (AIDS). All had been followed prospectively prior to death; 7 were demented and 8 were not demented. HIV was detected in 13 of 15 brains by polymerase chain reaction (PCR) and in the remaining 2 by presence of viral RNA or viral antigen. Quantitative PCR showed a wide range in amounts of HIV DNA with no significant difference between brains of demented and nondemented patients. These results suggest that qualitative features of the virus, rather than increased virus load per se, may be responsible for the clinical differences between HIV-infected patients with and without dementia.

Laboratory testing in peripheral nerve disease

Selecting appropriate laboratory tests in diagnosing peripheral neuropathies is important because it increases the yield of correct diagnoses and is cost effective. A large number of tests are available. This article provides a guide to selecting appropriate tests and reviews the clinical situations that suggest specific tests. Electrodiagnostic testing is valuable in almost all patients with peripheral neuropathy. Quantitative sensory testing adds additional information and is especially useful in patients with small fiber neuropathy. On occasion, routine blood tests may discover metabolic disorders causing a patient's neurologic disorder. A number of antibody assays for neuropathies are available commercially, with the most useful being anti-MAG, anti-GM1, anti-GQ1b, anti-Hu, and anticalcium channel antibodies, but only in very select situations and not as "screening studies". The role of cutaneous nerve and skin biopsies in selected disorders is discussed.

A potential role for interferon-alpha in the pathogenesis of HIV-associated dementia

Previous studies in patients receiving interferon-alpha (IFN-alpha) therapy and patients with systemic lupus erythematosus have demonstrated that elevated cerebrospinal fluid (CSF) levels of IFN-alpha are associated with cognitive dysfunction. We measured IFN-alpha levels in CSF and blood by ELISA in human immunodeficiency virus (HIV)-positive patients with (n = 21) and without (n = 23) dementia and HIV-negative controls (n = 48). IFN-alpha was significantly elevated in the CSF of HIV-positive patients with dementia compared to those without dementia and controls. An increasing amount of IFN-alpha in the CSF was correlated with the clinical parameter of increasing Memorial Sloan Kettering scores; although these correlations were not statistically significant, they further suggest an association of increased CSF IFN-alpha with neurocognitive dysfunction in AIDS. Immunocytochemical staining of brains demonstrated IFN-alpha-positive macrophages and astrocytes in frontal cortex and white matter and IFN-alpha mRNA was detected by reverse transcriptase-polymerase chain reaction, further indicating that IFN-alpha is made by cells within the brain and suggesting that the significant increases of IFN-alpha protein found in the CSF of patients with HIV-associated dementia complex are derived from intrinsic brain cells such as macrophages and astrocytes. Increased local production of IFN-alpha during HIV infection may contribute directly or indirectly to the pathogenesis of HIV-associated dementia.

Immunocytochemical quantitation of human immunodeficiency virus in the brain: correlations with dementia

The pathogenesis of human immunodeficiency virus (HIV)-associated dementia is unclear, and the underlying pathological substrate has been a matter of debate. In a prospectively clinically characterized population of acquired immunodeficiency syndrome (AIDS) patients we investigated the relationship between the clinical syndrome of HIV-associated dementia and the presence and relative quantity of immunocytochemical markers for HIV-1 (gp41 antibody), and for macrophages and microglia (HAM-56 antibody). Sections from the basal ganglia and frontal lobes from the brains of 51 patients were studied, and the data were stratified for severity of dementia (16 nondemented, 12 mildly demented, 23 severely demented), rate of dementia progression, duration of AIDS, use of antiretrovirals, and several other demographic features. We found a highly significant correlation between the degree of macrophage staining and the severity of dementia but only a borderline correlation between the presence and amount of gp41-positive cells and dementia. Several nondemented patients showed abundant gp41 immunoreactivity, and some severely demented showed little to no gp41 immunoreactivity. Other correlations with the immunostaining data, including antiretroviral use, were not significant. We conclude that the presence of macrophages and microglia is a better correlate with HIV-associated dementia than is the presence and amount of HIV-infected cells in the brain. These data support the concept that the pathogenesis of HIV-associated dementia is likely due to indirect effects of HIV infection of the brain, possibly through the actions of macrophages and microglia.

Cutaneous innervation in sensory neuropathies: evaluation by skin biopsy

OBJECTIVE

To use punch skin biopsies to evaluate the loss of intra-epidermal nerve fibers in sensory neuropathies.

BACKGROUND

Previous assessments of epidermal nerve fibers have been constrained by relatively insensitive staining techniques and variability in quantification.

METHODS

Punch skin biopsies were performed on the heel and leg of HIV-seronegative controls, HIV-seropositive individuals without neuropathy, and patients with sensory neuropathies, including HIV-seronegative and HIV-positive individuals. After formalin fixation, 50-microns free-floating sections were stained with a monoclonal antibody to neuron-specific ubiquitin hydrolase, PGP9.5. The number of intraepidermal fibers/mm in at least three sections from each patient was counted by one observer blinded to site and clinical status.

RESULTS

Dermal and epidermal nerve fibers were readily identified and quantified. The immunostaining technique reliably demonstrated a dermal plexus of myelinated and unmyelinated fibers parallel to the surface of the skin. In the epidermis, unmyelinated fibers ascended vertically between the keratinocytes to reach the stratum corneum. The number of intra-epidermal fibers/mm in the distal leg (mean +/- SEM) was 17.84 +/- 3.03 in seven HIV-seronegative controls. Epidermal fiber number was significantly reduced (p = 0.01) in five HIV-infected patients with sensory neuropathies associated with didanosine or zalcitabine therapy (1.07 +/- 0.40) and in eight HIV-seronegative patients with sensory neuropathies (3.1 +/- 3.1). Four of five neurologically normal HIV-seropositive subjects had reduced numbers of epidermal fibers, suggesting a subclinical neuropathy. Serial biopsies in one individual demonstrated the evolution of degenerating epidermal fibers after development of zalcitabine-induced sensory neuropathy.

CONCLUSION

Skin biopsies stained with the sensitive panaxonal marker anti-PGP9.5 demonstrated significant reduction in intraepidermal fibers in sensory neuropathies. This simple and repeatable technique is a reliable method for quantitation of small cutaneous sensory fibers. In addition, skin biopsies may be useful in assessing the course and spatial distribution of involvement in peripheral nerve disease.

Unifying hypothesis for the pathogenesis of HIV-associated dementia complex, vacuolar myelopathy, and sensory neuropathy

Neurological diseases associated with HIV infection include dementia, vacuolar myelopathy, and sensory neuropathy. Although in vitro studies suggest that other nervous system cell types could harbor HIV, immunohistochemical and in situ hybridization studies have indicated that only macrophages/microglia are significantly infected in the central nervous system. In the peripheral nervous system, even HIV-infected macrophages are rare. Therefore, theories regarding the pathogenesis of HIV-associated neurologic disorders have centered around the elaboration of substances that may be toxic to neurons, oligodendrocytes or myelin. These potential toxins include HIV proteins, cellular metabolites, and cytokines. In this review we present evidence that there are large numbers of macrophages/microglia present in the nervous system of patients with these diseases and that they produce tumor necrosis factor (TNF)-alpha. The large increase in macrophage activity late in HIV infection may be due to the diminution in production by CD4-positive T cells of cytokines such as interleukin (IL)-4 and IL-10 which are inhibitors of macrophage activities. We hypothesize that HIV-associated dementia complex, vacuolar myelopathy, and sensory neuropathy are directly or indirectly related to the increased numbers of macrophages found in brain, spinal cord, and peripheral nerve. Future therapies may be directed towards inhibition of macrophage functions.

Magnetic resonance imaging measurement of gray matter volume reductions in HIV dementia

OBJECTIVE

The authors recently reported smaller basal ganglia volumes for patients with HIV-associated dementia than for HIV-infected patients without dementia and a seronegative comparison group. The purpose of the current study was to determine whether HIV dementia is associated with volume reductions in other brain regions.

METHOD

The authors measured volumes of CSF and gray and white tissue on cranial magnetic resonance images from homosexual men who were 1) infected with HIV with HIV-associated dementia complex, 2) infected with HIV without dementia, and 3) HIV seronegative.

RESULTS

Results suggest that loss of white matter occurs with HIV infection and is more severe in HIV-positive patients with dementia than in those without dementia. There was some generalized volume reduction in gray matter in HIV-positive demented patients, although group differences did not reach significance when adjusted for age. Volume of posterior cortex, however, was significantly smaller among HIV-positive patients with dementia than in either remaining group. There were no significant differences between HIV-positive nondemented patients and HIV-negative subjects in these regions.

CONCLUSIONS

In conjunction with findings from previous research, the authors conclude that HIV dementia is associated with specific gray matter volume reduction in basal ganglia and posterior cortex, as well as with generalized volume reduction of white matter.

Normative data for a brief neuropsychologic test battery in a cohort of injecting drug users

Recent epidemiologic studies of the cognitive performance of injecting drug users have demonstrated the need to establish appropriate test norms for this population. This report provides normative data from a group of 150 injecting drug users on a battery of standardized tests of cognitive performance stratified by age group (range 20 to 49 years) and educational level (mean 11.6, standard deviation 2.0). The analysis also includes estimation of partial correlations between neuropsychologic test scores and age and education. The analysis demonstrates that age and education are important determinants of performance for several of these tests, and provides norms that may be of use as a reference for clinical evaluation and research in drug user populations.

AIDS dementia complex: evaluation with proton MR spectroscopic imaging

PURPOSE

To investigate cerebral metabolic changes in acquired immunodeficiency syndrome dementia complex (ADC) with proton magnetic resonance (MR) spectroscopic imaging and compare the findings with those of conventional MR imaging.

MATERIALS AND METHODS

Seven patients with ADC (all men; age range, 33-58 years; mean, 43 years) with human immunodeficiency virus (HIV) infection and seven age-matched volunteers without HIV infection underwent spectroscopic and conventional MR imaging.

RESULTS

Patient spectra were characterized by reduced levels of N-acetyl aspartate and increased levels of choline in white-matter regions. Lactate was detected in the cerebrospinal fluid of five patients. Four patients with mild to moderate dementia had more extensive metabolic abnormalities than three patients with only mild neurocognitive changes.

CONCLUSION

Proton MR spectroscopic imaging shows extensive metabolic changes and is more sensitive than conventional MR imaging in the detection of central nervous system involvement in ADC.

HIV Dementia Scale: a rapid screening test

HIV dementia has an annual incidence of 7% after AIDS development and eventually affects 20% of all HIV-infected persons. Accurate and early diagnosis of HIV dementia can lead to optimized therapeutic and management decisions. The purpose of this study was to design a valid instrument to identify HIV dementia. Five groups totalling 152 outpatients were evaluated; HIV-seronegative (SN) (n = 34); asymptomatic HIV-seropositive (ASX) (n = 38); AIDS, nondemented (AIDS) (n = 53); AIDS, mildly demented (Dm) (n = 39); and AIDS, severely demented (Ds) (n = 7). None had CNS opportunistic infections or delirium due to drug intoxication or systemic illness at the time of testing. Patients were evaluated with three different screening instruments: (a) the newly developed HIV Dementia Scale (HDS), (b) the Minimental State Exam (MMSE), and (c) the Grooved Pegboard (PB). Mean HDS scores (+/- SD) (maximum = 16) for each group were as follows: SN, 14.9 +/- 1.69; ASX, 14.1 +/- 1.72; AIDS, 12.8 +/- 3.17; Dm, 8.0 +/- 3.81; and Ds, 3.5 +/- 2.94. A Receiver-Operating Characteristic curve was used to derive an optimal HDS cut-off score of < or = 10 for identifying HIV dementia, with a sensitivity of 80%, specificity 91%, and positive predictive value 78%. The efficiencies of each instrument for identifying HIV dementia were as follows: HDS-84%, PB-86%, and MMSE-72%. The HDS is a reliable and quantitative scale that is superior to other widely used bedside tests such as the MMSE for identifying HIV dementia.

Cognitive performance after progression to AIDS: a longitudinal study from the Multicenter AIDS Cohort Study

OBJECTIVE

To describe changes in cognitive functioning before and after development of an acquired immune deficiency syndrome (AIDS)-defining illness or CD4+ lymphocyte count < 200/mm3 in participants in the Multicenter AIDS Cohort Study.

METHODS

The study population included participants who either were diagnosed with an AIDS-defining illness (n = 52) or had at least one measurement of CD4+ count < 200/mm3 (n = 57) and who had at least four neuropsychological (NP) evaluations, two or more before and two or more after the AIDS diagnosis. A group of subjects with clinical diagnosis of dementia (n = 29) was also included for comparison. The NP test battery included measures of attention, memory, constructional abilities, and psychomotor speed. Longitudinal data analysis, using the generalized estimating equation, was performed separately for each NP measure. Time was measured in months from the date of clinical AIDS or CD4+ < 200/mm3.

RESULTS

Before AIDS< the dementia group showed significant decline (slope different from zero) only on measures of psychomotor speed. For all other measures, there was no evidence of decline in performance before AIDS for the other groups. After development of AIDS, the group with clinical AIDS showed significant decline on psychomotor speed but none on the other cognitive measures. The group with CD4+ < 200/mm3 did not show significant decline on any of the cognitive measures after AIDS. As expected, the dementia group showed significant decline on all measures. Sensory neuropathy was associated with a significant decline in performance on measures of psychomotor speed after AIDS. Antiretroviral therapy was not associated with any measurable changes in NP performance.

CONCLUSION

These results are consistent with previous findings showing no significant decline in cognitive functions before AIDS, unless overt dementia is present, and no decline in immunosuppressed subjects who have had no AIDS-defining illness. By contrast, in subjects who have developed clinical AIDS, there is mild decline in fine motor skills but no significant change in other cognitive domains.

Diagnosis of progressive multifocal leukoencephalopathy by stereotactic brain biopsy utilizing immunohistochemistry and the polymerase chain reaction

This report describes the diagnosis of progressive multifocal leukoencephalopathy (PML) in nine patients using cytopathologic and histopathologic examination of computed tomographically guided stereotactic brain biopsies in combination with immunostaining for SV-40-related antigen and the polymerase chain reaction (PCR) for the JC virus. In four patients the diagnosis of PML was based on the microscopic appearance of the biopsies and immunostaining for SV-40-related antigen. In one of these patients the diagnosis was also supported by PCR for the JC virus. In two patients whose biopsies were only suggestive of PML, a definitive diagnosis was possible utilizing immunohistochemistry and PCR. In another case the histopathologic features were atypical of PML, and the diagnosis was established with immunostaining and PCR. The diagnosis of PML was established by PCR alone in two patients whose biopsies showed only suggestive or nonspecific findings. We conclude that the accuracy of stereotactic biopsy in the diagnosis of PML is enhanced by using a combination of light microscopy, immunohistochemistry and PCR.

Clinicopathologic correlations of HIV-1-associated vacuolar myelopathy: an autopsy-based case-control study

To determine the clinical correlates of HIV-1-associated vacuolar myelopathy (VM), we designed a case-control study based on 215 AIDS autopsies in which we examined the spinal cord. We defined a case as an individual dying with AIDS and with VM present at autopsy; we defined a control as an individual dying with AIDS without VM. VM was found in 100 of 215 (46.5%) autopsies, with no apparent temporal trends. A higher number of AIDS-defining illnesses was strongly associated with the likelihood of VM (trend chi-square = 26.52, p < 0.001). Systemic infection with Mycobacterium avium-intracellulare and Pneumocystis carinii pneumonia were each associated with the pathologic findings of VM in both univariate and multivariate models. In the brain, multinucleated giant cells were detected in more cases than in controls (odds ratio = 3.68, 95% CI = 1.73 to 7.47, p < 0.001). The clinical features of HIV-1 dementia were not associated with VM; in contrast, predominantly sensory neuropathy was more common in VM cases than in controls (odds ratio = 5.00, 95% CI = 1.35 to 18.5, p < 0.05). Fifty-six cases with VM had detailed neurologic evaluations, but only 15 (26.8%) had signs and symptoms of myelopathy. The presence of symptomatic myelopathy was related to the pathologic severity: none of 17 cases with grade 1, five of 26 with grade 2, and 10 of 13 with grade 3 had clinical features of myelopathy (trend chi-square = 21.16, p < 0.005). VM is a common neuropathologic finding that is frequently unrecognized during life. The association with the number of systemic illnesses, M avium-intracellulare infection, and P carinii pneumonia suggests that the development of VM is related to the severity of immunosuppression.

Temporal trends in the incidence of HIV-1-related neurologic diseases: Multicenter AIDS Cohort Study, 1985-1992

OBJECTIVE

To describe temporal trends in the incidence of human immunodeficiency virus (HIV)-related neurologic diseases in the Multicenter AIDS Cohort Study from 1985 to 1992.

METHODS

The incidence rates of six neurologic disorders were examined: toxoplasmosis, cryptococcal meningitis, primary CNS lymphoma, progressive multifocal leukoencephalopathy, HIV dementia, and sensory neuropathy. Poisson modeling was used to test linear trends over time and the effects of progressive immunosuppression, antimicrobial prophylaxis, and antiretroviral drug therapy.

RESULTS

There was an upward temporal trend in all incidence rates, except for HIV dementia. Progressive immunosuppression in the cohort explained all calendar trends except for sensory neuropathy, where an increasing temporal trend remained even after adjusting for CD4+ cell count, and for HIV dementia where a slight decline was noted, although the effects were not statistically significant. We noted a protective trend of antimicrobial prophylaxis on toxoplasmosis and cryptococcal meningitis, but, in contrast, use of antiretroviral agents was not protective against HIV dementia. Men receiving didanosine, zalcitabine, or stavudine were more likely to develop sensory neuropathy.

CONCLUSION

Despite the earlier and more widespread use of antimicrobial and antiretroviral agents, neurologic conditions still occurred frequently in this cohort, with annual rates above 1.5 per 100 person-years for HIV dementia and sensory neuropathy. Sensory neuropathy seems to be increasing in incidence and HIV dementia declining slightly in this cohort. As the epidemic matures and more people with profound immunosuppression live longer, the overall incidence of HIV-related neurologic diseases can be expected to rise.

Demented and nondemented patients with AIDS differ in brain-derived human immunodeficiency virus type 1 envelope sequences

Human immunodeficiency virus (HIV) dementia is a common clinical syndrome of uncertain pathogenesis in patients with AIDS. In several animal models of retrovirus-induced brain disease, specific viral envelope sequences have been found to influence the occurrence of central nervous system disease. Therefore, to search for unique envelope sequences correlated with HIV dementia, we studied 22 HIV-infected patients who were neurologically assessed premortem and classified into demented (HIVD) (n = 14) and nondemented (ND) (n = 8) groups. Using DNA from autopsied brain and spleen, we amplified, cloned, and sequenced a 430-nucleotide region including the V3 loop and flanking regions. All brain-derived clones in both clinical groups showed marked homology to the macrophage-tropic consensus sequence within the V3 loop. Two amino acid positions within (position 305) and outside (position 329) the V3 region showed significant divergence between the two clinical groups. At position 305, a histidine was predominant in the HIVD group and was not observed in the ND group, but a proline was predominant in the ND group and was not observed in the HIVD group. Similarly, at position 329, a leucine was predominant in the HIVD group but rarely observed in the ND group, whereas an isoleucine was predominant in the ND group at this position. In addition, the HIVD group had 21 amino acid residues at specific positions that were unique relative to the ND group, whereas only 2 residues at specific positions were unique to the ND group. These data suggest that distinct HIV envelope sequences are associated with the clinical expression of HIV dementia.

Cerebrospinal fluid human immunodeficiency virus type 1 (HIV-1) p24 antigen levels in HIV-1-related dementia

Human immunodeficiency virus type 1 (HIV-1) p24 antigen, a putative marker of virus load, was assayed in 79 blood and 83 cerebrospinal fluid (CSF) samples from 90 HIV-1-seropositive individuals with or without dementia. Twenty-eight subjects had no evidence of neuropsychological impairment, 17 had mild impairment without objective evidence of dementia, and 45 were demented. HIV-1 p24 antigen was detected more frequently in CSF samples from demented (19/40) than normal (1/26) or mildly impaired (1/17) subjects and in 67% of individuals with significant dementia (MSK stages 2-4). p24 Antigen was detected less frequently in CSF from demented subjects on antiretroviral drugs than untreated demented individuals. Overall, the sensitivity of the antigen capture assay in CSF among demented individuals was 47.5%; the specificity, 95.0%; positive predictive value, 90.4%; negative predictive value, 66.1%; and the efficiency, 72.2%. A direct relationship was also noted between the degree of cognitive impairment and blood p24 antigen detection frequency and antigen concentration. CD4+ blood lymphocyte counts were lower for demented individuals, and HIV-1 p24 antigen was detected more frequently and p24 antigen concentration was higher in blood and CSF from individuals with low CD4+ blood lymphocyte counts. beta 2-Microglobulin levels were higher in CSF from demented subjects and correlated directly with CSF p24 antigen concentration. However, in contrast to CD4+ blood lymphocyte counts and beta 2-microglobulin levels, only p24 antigen concentration correlated with dementia severity. Therefore, p24 antigen can be a useful marker for dementia related to HIV-1 infection.

Elevated central nervous system prostaglandins in human immunodeficiency virus-associated dementia

The dementia associated with human immunodeficiency virus (HIV) is poorly understood. Dementia is accompanied by infection and activation of macrophage lineage cells in the brain and production of toxic products by these cells has been postulated to play a role in the pathogenesis of dementia. Eicosanoids are potential products of activated macrophages that can mediate cell injury. We measured the levels of prostaglandin E2 in the cerebrospinal fluid of HIV-positive individuals with dementia and/or myelopathy and compared these levels with those of HIV-negative patients with other neurological diseases and HIV-positive patients without dementia. Cerebrospinal fluid prostaglandin E2 levels were increased in dementia. This increase was associated with severity of dementia and correlated with cerebrospinal fluid levels of neopterin and beta 2-microglobulin. Prostaglandins F2 alpha and thromboxane B2, additional products of the cyclooxygenase pathway of arachidonic acid metabolism, were also elevated in dementia, but leukotriene C4, a product of the lipoxygenase pathway was not. Since synthesis of prostaglandins is regulated in part by the levels of inducible forms of cyclooxygenase, we measured the levels of cyclooxygenase-1 and 2 mRNAs in the brains of HIV-positive individuals with and without dementia by reverse transcriptase polymerase chain reaction. Levels of intact cyclooxygenase-1 mRNA were higher in the brains of demented individuals, but this did not reach statistical significance. These data demonstrate that prostaglandins are increased in the central nervous system in HIV-associated dementia and may play a role in the development of neurological dysfunction.

Altered cortical blood flow in HIV-seropositive individuals with and without dementia: a single photon emission computed tomography study

OBJECTIVE

To quantitatively demonstrate the pattern of cerebral perfusion abnormalities in HIV-1-infected individuals described as 'patchiness' or inhomogeneity in previous qualitative emission tomographic imaging studies.

DESIGN

We aimed to create a quantitative measure of inhomogeneity in HIV-infected individuals. High-frequency variance in cortical profiles is an indication of inhomogeneity in the distribution of radiotracer in the cerebral cortex. Therefore, the study analysis was designed to enable the estimation of variance frequencies in cortical profiles.

METHODS

Regional cerebral blood flow was examined in nine mildly demented and 10 cognitively normal HIV-1-seropositive individuals and eight seronegative normal controls using single photon emission computed tomography with the radiotracer [I-123]-N-isopropyl-p-iodoamphetamine. Quantitative analysis was performed using circumferential profiles of cerebral cortical perfusion. Fourier transform power spectra of the profiles were examined as an index of patchiness in tracer distribution.

RESULTS

Normal controls were characterized by strong middle frequency and weak high-frequency power. Both HIV-1-infected groups showed a significant power shift from middle to high frequencies.

CONCLUSIONS

Increased high-frequency variations in both HIV-1-infected groups indicates diffuse cortical perfusion changes compared with normal controls. This study suggests that there are cerebral bloodflow abnormalities in HIV-1-infected individuals both with and without clinically severe dementia.

Cytomegalovirus encephalitis in acquired immunodeficiency syndrome (AIDS)

Cytomegalovirus encephalitis (CMVE) is frequently diagnosed only at postmortem because its specific clinical features have not been fully identified. We have described the clinical, radiologic, and laboratory features of CMVE in a retrospective review of 14 autopsy-confirmed cases of CMVE and compared them with a control group of demented acquired immunodeficiency syndrome (AIDS) patients without CMVE. CMVE was more common among homosexual men, and a subacute onset was more typical (mean duration of presenting symptoms was 3.5 weeks versus 18 weeks in demented controls). Median survival times were 4.6 weeks for CMVE and 28 weeks for controls. CMVE was accompanied by prominent systemic CMV infection at autopsy, including CMV adrenalitis (92%), CMV pneumonitis (42%), systemic Mycobacterium avium intracellulare (MAI; 58%), and CMV retinitis (58%). Hyponatremia and MAI bacteremia were found in 58% of CMVE cases. Polymerase chain reaction (PCR) of CSF samples identified CMV genome in 33% of CMVE cases. CMVE was associated with periventricular enhancement on CTs and periventricular lesions with meningeal enhancement on MRI scans. CMVE should be particularly suspected in homosexual men presenting with subacute encephalopathy who have had AIDS for more than 1 year and have a history of systemic CMV infection. Other features supporting the diagnosis of CMVE include periventricular lesions, hyponatremia, and identification of CMV genome in CSF by PCR.

Cytokine dysregulation in HIV-associated neurological disease

AIDS is associated with three major neurological syndromes: dementia (HIVD), vacuolar myelopathy (VM) and plainful sensory neuropathy (PSN). The pathogenesis of these conditions remains unclear although they all demonstrate a marked increase in macrophage number and activation despite systemic immunosuppression. It was therefore of interest to determine the profile of cytokine and HIV expression in brain, spinal cord and peripheral nerves of AIDS patients with AD, VM and PSN, as compared to AIDS patients without neurological disease and seronegative controls. RNA was extracted from brain, spinal cord and peripheral nerve and RT/PCR for cytokine and HIV mRNA was performed. In situ RT/PCR was performed to determine the number and type of cells expressing cytokine message and this was compared to the number of cells containing HIV DNA detected with in situ PCR. We found a consistent profile of increased TNF alpha and decreased IFN gamma and IL4 in all three syndromes compared to AIDS patients without neurological disease. IL1 did not increase in parallel with TNF alpha IL10 was decreased in the VM tissue. HIV transcripts were increased in the AD brains compared to non-demented controls but were detected only occasionally in spinal cord and not at all in peripheral nerve. Preliminary data from in situ RT/PCR suggests that a large number of cells are expressing. TNF alpha but only a small number are infected with HIV.(ABSTRACT TRUNCATED AT 250 WORDS)

Dementia in AIDS patients: incidence and risk factors. Multicenter AIDS Cohort Study

We determined incidence and future projections of dementia after AIDS onset in 492 homosexual men with AIDS in the Baltimore/Los Angeles sites of the Multicenter AIDS Cohort Study, 64 of whom developed dementia. We studied various risk factors for dementia, including demographic and clinical features, medical history, markers of immune status before AIDS, and zidovudine use. During the first 2 years after AIDS, HIV dementia developed at an annual rate of 7%. Overall, 15% of the cohort followed through death developed dementia. The median survival after dementia was 6.0 months. Using a proportional hazards model, risk factors for more rapid development of dementia were lower hemoglobin (relative hazard, 0.59 per additional 2 g/dl; p = 0.0005) and body mass index (relative hazard, 0.64 per additional 5 kg/m2; p = 0.05) 1 to 6 months before AIDS, more constitutional symptoms 7 to 12 months before AIDS (relative hazard, 1.68 per additional symptom, p = 0.005), and older age at AIDS onset (relative hazard, 1.60 per decade older; p = 0.009). In a multivariate model, pre-AIDS hemoglobin remained the most significant predictor of dementia. There were no significant risks defined from demographic characteristics, specific AIDS-defining illnesses, zidovudine use before AIDS, or CD4+ lymphocyte count before AIDS. We project that 12 months after the first AIDS diagnosis, 7.1% of survivors will have dementia. The observed association between anemia, low weight, constitutional symptoms, and dementia suggests a role for cytokines inducing both systemic and neurologic disease.

Clinical-neuropathologic correlation in HIV-associated dementia

The structural abnormalities that correlate with the clinical manifestations of HIV-associated dementia (HIVD) are unclear. In a prospectively categorized group of patients with and without HIVD who were followed to autopsy, we correlated HIV-related neuropathologic changes with the presence and severity of HIVD. We also assessed the effect of antiretroviral therapy on the neuropathologic changes. Finally, using reverse transcriptase-polymerase chain reaction on homogenized brain tissue, we correlated the relative expression of mRNA for tumor necrosis factor-alpha (TNF-alpha) with cognitive impairment and with the patterns of neuropathologic changes. The presence of multinucleated giant cells and diffuse myelin pallor were specific for HIVD, but these pathologic changes occurred in only 50% of patients with dementia. Patients treated with antiretroviral agents for > 12 months were less likely to show multinucleated giant cells or diffuse myelin pallor. Levels of mRNA for TNF-alpha from frontal subcortical white matter were significantly greater in patients with HIVD than in AIDS patients without dementia or in seronegative controls. We conclude that routine histopathologic examination of the brain fails to detect multinucleated giant cells and diffuse myelin pallor in 50% of patients dying with HIVD. This suggests that more subtle neuropathologic correlates for the clinical manifestations of HIVD exist. Our observations of elevated levels of TNF-alpha mRNA in HIVD indicate that indirect mechanisms of brain dysfunction, such as abnormal cytokine expression, may contribute to the pathogenesis of HIVD.

Reduced basal ganglia volume in HIV-1-associated dementia: results from quantitative neuroimaging

Although brain atrophy is a common neuroradiologic and pathologic finding in patients with HIV-1 infection, especially those with HIV-1-associated dementia complex, it is not clear whether specific regions of the brain are differentially responsible for tissue loss. In this study, we measured volumes of basal ganglia structures on MRIs for three groups: HIV-1-infected homosexual men with HIV-1-associated dementia complex (HIV+ demented), HIV-1-infected homosexual men without HIV dementia (HIV+ nondemented), and noninfected homosexual men. All groups were comparable on age and years of education, and the HIV+ groups were comparable on level of immunosuppression. Total brain volume was smaller in the HIV+ nondemented patients in comparison with HIV- control subjects; the HIV+ demented patients demonstrated even smaller brain volumes than the HIV+ nondemented patients. Smaller basal ganglia volumes, after corrections for intracranial volume, distinguished HIV+ demented patients from the other two groups; there were no differences between the HIV+ nondemented and HIV- groups on basal ganglia volumes. This study suggests that HIV infection causes generalized brain atrophy, but that the clinical features of HIV dementia develop with selective basal ganglia atrophy, consistent with the characterization of HIV dementia as subcortical.

Cerebral white matter changes in acquired immunodeficiency syndrome dementia: alterations of the blood-brain barrier

The cause of acquired immunodeficiency syndrome (AIDS) dementia, which is a frequent late manifestation of human immunodeficiency virus (HIV) infection, is unknown but radiological and pathological studies have implicated alterations in subcortical white matter. To investigate the pathological basis of these white matter abnormalities, we performed an immunocytochemical and histological analysis of subcortical white matter from AIDS patients with and without dementia, from pre-AIDS patients (asymptomatic HIV-seropositive patients), and from HIV-seronegative control subjects. Reduced intensity of Luxol fast blue staining, designated "diffuse myelin pallor," was detected in 8 of 15 AIDS dementia patients, 3 of 13 AIDS nondemented patients, and none of the pre-AIDS patients (n = 2) or control subjects (n = 9). In contrast to Luxol fast blue staining, sections stained immunocytochemically for myelin proteins did not show decreased staining intensities in regions of diffuse myelin pallor. In addition, neither demyelinated axons nor active demyelination were detected in light and electron micrographs of subcortical white matter from brains of patients with AIDS dementia. An increase in the number of perivascular macrophages and hypertrophy of astrocytes and microglia occurred in brain sections from HIV-infected patients. These changes were not specific to dementia or regions of diffuse myelin pallor and they occurred in both gray and white matter. In contrast to the lack of myelin pathology in AIDS dementia brains, significant accumulations of serum proteins in white matter glia were detected in the brains of 12 of 12 patients with AIDS dementia and 6 of 12 AIDS patients without dementia. Serum protein-immunopositive cortical neurons were detected in the frontal cortex of 11 of 12 patients with AIDS dementia and 3 of 12 nondemented AIDS patients. Seronegative control subjects showed minimal serum protein immunoreactivity in both cortex and white matter. We conclude therefore that alterations in the blood-brain barrier and not demyelination contribute to the development of AIDS dementia.

Regional brain atrophy in HIV-1 infection: association with specific neuropsychological test performance

Quantified magnetic resonance imaging (MRI) was related to neuropsychological (NP) test scores in an asymptomatic HIV-1 seropositive group, a non-demented AIDS/ARC group, a group of subjects with HIV-1 dementia, and a seronegative control group. The MRIs were quantified using three planimetric measures of brain structure: the bicaudate ratio (a measure of caudate region atrophy), the bifrontal ratio (a measure of frontal region atrophy), and the ventricle to brain ratio (a measure of overall cerebral atrophy). Cognitive performance was assessed with standard NP tests. Significant correlations between the MRI ratios and many of the NP tests were observed. Of the tests grooved pegboard, part B of the trail making test, the verbal fluency test, and the digit span forward were associated with MRI abnormalities. The bicaudate ratio was most closely associated with the NP tests. These findings indicate that ventricular enlargement, especially in the region of the caudate, is closely related to poor NP test performance in HIV-1 infection.

Intracerebral cytokine messenger RNA expression in acquired immunodeficiency syndrome dementia

The pathogenesis of the dementia associated with human immunodeficiency virus (HIV) infection is unclear, but has been postulated to be due to indirect effects of HIV infection including the local production of cytokines. To determine which cytokines are produced in the nervous system and to identify any correlations with dementia, cytokine and HIV messenger RNA expression was analyzed by reverse transcriptase-polymerase chain reaction in the brains from 24 HIV-infected patients with and without dementia and 9 HIV-uninfected control subjects. Levels of tumor necrosis factor-alpha messenger RNA were significantly higher and levels of interleukin (IL)-4 messenger RNA were significantly lower in demented compared to nondemented HIV-infected patients. Demented patients also had lower IL-1 beta levels than did nondemented patients. No significant differences were detected in the amounts of leukemia inhibitory factor, IL-6, transforming growth factor-beta 1 and -beta 2, monokine induced by gamma interferon-2 (MIG-2), or interferon-gamma messenger RNAs. IL-10 and IL-2 messenger RNAs were undetectable in all brains examined. Cytokine messenger RNA levels in nondemented HIV-positive patients were similar to those in HIV-negative control subjects. HIV transcripts were more abundant in subcortical white matter than in the basal ganglia, cortex, or deep white matter. Our findings suggest a possible role for tumor necrosis factor-alpha in the development of neurological dysfunction. Increased levels of tumor necrosis factor-alpha messenger RNA were not associated with increased levels of IL-1 beta messenger RNA, suggesting differential regulation of these monokines in acquired immunodeficiency syndrome dementia.(ABSTRACT TRUNCATED AT 250 WORDS)

Low education as a possible risk factor for cognitive abnormalities in HIV-1: findings from the multicenter AIDS Cohort Study (MACS)

The present study reports new and unexpected results of cognitive abnormalities among human immunodeficiency virus type 1 (HIV-1) asymptomatic subjects in the Multicenter AIDS Cohort Study. The major purpose of our analyses is to estimate the separate and combined effects of serostatus and education level on the prevalence of cognitive abnormality. Cognitive "abnormality" was defined as performance that deviated > or = 2 SDs below the mean of the total seronegative group on at least one of the five neuropsychological screening tests (Grooved Pegboard, Verbal Fluency, Digit Span, Symbol Digit Modalities, Rey Auditory Verbal Learning). The predicted prevalence of cognitive abnormality was 38% in seropositive individuals with no more than 12 years of education, compared with < 17% in the other education-serostatus groups. This interaction between education level and serostatus remained after controlling for the possible confounding effects of age, ethnicity, CD4 level, depression, prior drug history, and learning disability using logistic regression. To account for these findings, we suggest that low education might reflect an indirect index of lower reserve capacity (i.e., a risk factor) that lowers the threshold for neuropsychological abnormalities in cases of early HIV-1 infection.

Cytokine expression of macrophages in HIV-1-associated vacuolar myelopathy

Macrophages are frequently present within the periaxonal and intramyelinic vacuoles that are located primarily in the posterior and lateral funiculi of the thoracic spinal cord in HIV-associated vacuolar myelopathy. But the role of these macrophages in the formation of the vacuoles is unclear. One hypothesis is that cytokines, such as interleukin-1 (IL-1) and tumor necrosis factor (TNF)-alpha, are produced locally by macrophages and have toxic effects on myelin or oligodendrocytes. The resulting myelin damage eventually culminates in the removal of myelin by macrophages and vacuole formation. We studied thoracic spinal cord specimens taken at autopsy from HIV-positive (+) and HIV-negative individuals. The predominant mononuclear cells present in HIV+ spinal cords are macrophages. They are located primarily in the posterior and lateral funiculi regardless of the presence or absence of vacuolar myelopathy. Macrophages and microglia are more frequent in HIV+ than HIV-negative individuals and these cells frequently stain for class I and class II antigens, IL-1, and TNF-alpha. Activated macrophages positive for IL-1 and TNF-alpha are great increased in the posterior and lateral funiculi of HIV+ individuals with and without vacuolar myelopathy, suggesting they are present prior to the development of vacuoles. Cytokines, such as TNF-alpha, may be toxic for myelin or oligodendrocytes, leading to myelin damage and removal by macrophages and vacuole formation.

Neurologic prognosis of cytomegalovirus polyradiculomyelopathy in AIDS

Cytomegalovirus (CMV) polyradiculomyelopathy is an uncommon but distinctive clinical syndrome in HIV-infected patients in which ascending motor weakness, areflexia, loss of sphincter control, paresthesias, and varying sensory impairment develop subacutely in association with a polymorphonuclear pleocytosis, increased protein, and hypoglycorrhachia in CSF. Responses to treatment with ganciclovir have varied in reported cases. We report three additional cases: two of these patients responded to treatment and the third was demonstrated to have CMV resistant to ganciclovir. We review other reported cases and identify factors predictive of ganciclovir resistance, which include persistent polymorphonuclear pleocytosis and hypoglycorrhachia on serial CSF studies, and positive CMV cultures from CSF or blood after induction therapy. We conclude that ganciclovir may be an effective therapy for CMV polyradiculomyelopathy, but the presence of these factors, or the development of the syndrome in a patient already being treated with ganciclovir, should prompt consideration of alternative antiviral therapy.

Radiographic imaging of sinusitis in HIV infection

Magnetic resonance images (MRI) of the brain from 75 homosexual men were reviewed to evaluate the frequency and severity of incidental sinus disease associated with human immunodeficiency virus (HIV). All scans had been performed for reasons other than a history of sinus disease. The opacification of each sinus cavity was scored such that 0 = normal, 1 = < 25%, 2 = 25% to 75%, and 3 = > 75% opacification. Subjects were then stratified by clinical status into four groups: HIV-, HIV+ without HIV-related symptoms, AIDS-related complex (ARC), or AIDS. Grade 1 mucosal thickening was present in 52% to 55% of HIV- and HIV+ subjects alike. Moderate disease (grade 2 or 3) was seen in seven of 52 HIV+ subjects, but none of the 23 HIV- controls. The incidence of maxillary sinus thickening was 69% in men with AIDS, compared to 30% in HIV- men (chi 2 = 4.1, p < 0.05). Mean maxillary sinus scores were 1.25 +/- 0.29 in those with AIDS compared to 0.43 +/- 0.15 in HIV- men (f = 5.11, p < 0.05). Our results suggest that maxillary sinus disease is more common and more severe in patients who have AIDS.

Effect of chronic substance abuse on the neuropsychological performance of intravenous drug users with a high prevalence of HIV-1 seropositivity

Limited data are available on cognitive performance in populations of intravenous drug users during the early, asymptomatic stages of human immunodeficiency virus type 1 (HIV-1) infection. Between 1988 and 1990, 151 participants from the AIDS Link to Intravenous Experience (ALIVE) Study in Baltimore, Maryland, were evaluated neuropsychologically on a semiannual basis. This analysis focused on whether history of substance abuse influenced neuropsychological test performance. At baseline, 102 participants were HIV-1-seropositives who were free of acquired immunodeficiency syndrome and 49 participants were seronegative. Multivariate analyses, adjusting for correlation of repeated outcome measures, were conducted to determine predictors of neuropsychological functioning. Effects of the frequency of reported past use of marijuana, heroin, cocaine, barbiturates, and alcohol were not statistically associated with performance on the tests. Age and education were the most important predictors of test performance, and a significant practice effect was observed for most measures. After adjustment for age, education, the practice effect, and frequency of drug use, neuropsychological performance over time did not vary by HIV-1 serostatus. Overall, after acutely intoxicated individuals were excluded, neither frequency of drug and alcohol use nor HIV-1 seropositivity significantly influenced neuropsychological test performance over a 1-year period.

Patterns of cerebral atrophy in HIV-1-infected individuals: results of a quantitative MRI analysis

Cerebral atrophy is a common radiologic manifestation of HIV dementia. To evaluate the relationship between cognitive impairment and cerebral atrophy, adjusting for age and immune status, we used standardized planimetry to measure the ventricle-brain ratio (VBR) and the bifrontal (BFR) and bicaudate (BCR) ratios, three measures of cerebral atrophy. We analyzed cranial MRIs of 23 HIV-1-seronegative controls (SN) and 116 HIV-1-infected individuals. Of the HIV-1-seropositive individuals, 37 had HIV dementia (DM group), 40 had neurologic or neuropsychological abnormalities insufficient for HIV dementia (NP+ group), and 39 were neurologically normal (NML group). We performed comparisons using analysis of covariance with correction for multiple comparisons. Both the VBR, a general measure of overall cerebral atrophy, and the BCR, a measure of atrophy in the region of the caudate nucleus, are significantly associated with dementia. The association is stronger for BCR enlargement than for VBR enlargement, suggesting that selective caudate region atrophy is associated with HIV dementia. These results indicate that overall cerebral atrophy and prominent caudate region atrophy are important radiographic features of HIV dementia.

HIV-1 infection and intravenous drug use: longitudinal neuropsychological evaluation of asymptomatic subjects

A previous baseline cross-sectional comparison of cognitive performance of a group of AIDS-free, HIV-seropositive intravenous drug users with seronegative control intravenous drug users revealed no significant differences attributable to HIV. We now present longitudinal follow-up results from the same cohort of 160 intravenous drug users. There were no differences in performance by serostatus group at either 6- or 12-month follow-up visits, although differences by age and education were observed. Improvement in performance secondary to practice effects was comparable in both serostatus groups. These findings confirm that chronic intravenous drug use may be associated with a wide range of neuropsychological deficits, but there is no evidence that such preexisting deficits interact with HIV infection to produce additional cognitive impairment in otherwise asymptomatic intravenous drug users. Together with results from other high-risk groups such as homosexual/bisexual men and hemophiliacs, these results confirm that neurocognitive abnormalities during the presymptomatic stages of HIV infection are rare, regardless of the route of acquisition of the virus.

The diagnostic utility of elevation in cerebrospinal fluid beta 2-microglobulin in HIV-1 dementia. Multicenter AIDS Cohort Study

We measured serum and CSF beta 2-microglobulin (beta 2M) levels in HIV-1 seropositive individuals with and without dementia to determine the frequency and diagnostic utility of elevation of CSF beta 2M. We compared 34 samples from 27 patients with HIV-1 dementia with 110 samples from 54 HIV-1 seropositive participants in the Multicenter AIDS Cohort Study, none of whom had progressive dementia. Neurosyphilis and CNS opportunistic processes were excluded in all subjects. We stratified the nondemented subjects by duration of HIV seropositivity and peripheral blood CD4 count. Compared with the nondemented group, demented subjects had significantly higher CSF total protein, IgG%, and CSF albumin/serum albumin ratios. A highly significant association was found between elevated CSF beta 2M and reduced CD4 count (p less than 0.0001). No significant differences were noted between the demented and nondemented groups in CSF WBC count or in the frequency of CSF HIV-1 isolation. The mean CSF beta 2M was 1.9 mg/l in the nondemented subjects compared with 4.2 mg/l in those with dementia (p less than 0.0001). We derived a cutoff of 3.8 mg/l from the distribution of CSF beta 2M in the nondemented group. The determination of CSF beta 2M had a sensitivity of 44%, specificity of 90%, and a positive predictive value of 88% for diagnosis of HIV dementia when compared with nondemented subjects with CD4 counts less than 200. In those without dementia, there was a strong correlation between serum and CSF beta 2M (r = 0.50, p less than 0.0001), but in demented subjects CSF beta 2M was elevated independently of serum levels, suggesting that CSF beta 2M is produced within the brain in HIV dementia. In the absence of CNS opportunistic processes, elevated CSF beta 2M greater than 3.8 mg/l is a clinically useful marker for HIV dementia.

Asymptomatic HIV infection does not cause EEG abnormalities: results from the Multicenter AIDS Cohort Study (MACS)

We conducted EEG testing in 200 asymptomatic homosexual men, half of whom were HIV seropositive. We chose to include half of the subjects because they were rated as impaired on a neuropsychological screening test. We used both traditional visual EEG interpretation and quantitative EEG analysis. Abnormal EEGs and borderline degrees of EEG slowing occurred in 32% of these men. These EEG changes were not related to HIV serostatus. EEG changes did correlate with the impaired neuropsychological test performance. Clinicians faced with abnormal EEG results or borderline EEG slowing in an asymptomatic HIV-seropositive patient should not attribute the EEG change to effects of the serostatus itself but should look for other causes.

Cerebrospinal fluid beta 2-microglobulin in patients with AIDS dementia complex: an expanded series including response to zidovudine treatment

OBJECTIVE

To determine the relationship between cerebrospinal fluid (CSF) beta 2-microglobulin (beta 2M) and severity of AIDS dementia complex (ADC), and between CSF beta 2M and response of ADC to zidovudine.

DESIGN

A prospective study.

SETTING

Tertiary referral hospital.

PATIENTS, PARTICIPANTS

Seventy-eight patients with varying stages of ADC were selected from a subgroup of a cohort of HIV-seropositive patients who are being studied prospectively for the neurological complications of HIV-1 infection. To enter our study, patients had to have an ADC stage of at least 0.5 (equivocal symptoms or abnormal neurological signs in the absence of functional impairment). A control group of 11 HIV-1-seropositive, neurologically normal patients was chosen randomly from the patients followed in the Multicenter AIDS Cohort Study.

INTERVENTIONS

Patients were assessed neurologically and neuropsychologically and computed tomography of the brain and CSF studies were performed.

MAIN OUTCOME MEASURES

Patients were staged according to severity of ADC on clinical criteria. Neuropsychological test scores were converted to an impairment score. CSF beta 2M was quantified in both serum and CSF of all patients and in 10 patients with pre- and post-zidovudine assessments.

RESULTS

There was a high correlation between CSF beta 2M concentration and severity of ADC (P less than 0.0001); treatment with zidovudine significantly reduced these concentrations (P = 0.013). CSF beta 2M concentration was independent of CSF white-cell count and blood-brain barrier impairment. Other CSF changes in the same patients (including blood-brain barrier permeability to albumin, intrathecal synthesis of immunoglobulin G and HIV-1-p24-antigen levels) were less useful as objective correlates of ADC severity and response to zidovudine therapy.

CONCLUSIONS

CSF beta 2M may be a valuable marker of ADC severity and response to antiviral therapy.

Cytokine expression in the brain during the acquired immunodeficiency syndrome

The pathogenesis of central nervous system (CNS) disease in acquired immunodeficiency syndrome (AIDS) is poorly understood but may be related to specific effects of the immune system. Cytokines such as tumor necrosis factor and interleukin-1 may have toxic effects on CNS cells and have been postulated to contribute to the pathogenesis of the neurological complications of human immunodeficiency virus (HIV) infection. To characterize viral and immunological activity in the CNS, frozen specimens taken at autopsy from the cerebral cortex and white matter of HIV-seropositive and -seronegative individuals were stained immunocytochemically for mononuclear cells, major histocompatibility complex (MHC) antigens, HIV, astrocytes, and the cytokines interleukin-1 and -6, tumor necrosis factor-alpha and -beta, and interferon gamma. Levels of soluble CD4, CD8, and interleukin-2 receptor, as well as interferon gamma, tumor necrosis factor-alpha, beta 2-microglobulin, neopterin, and interleukin-6 and -1 beta were assayed in the cerebrospinal fluid and plasma of many of these individuals during life. The HIV-seropositive group included individuals without neurological disease, those with CNS opportunistic infections, and those with HIV encephalopathy. Perivascular cells, consisting primarily of macrophages with some CD4+ and CD8+ T cells and rare B cells, were consistently MHC class II positive. MHC class II antigen was also present on microglial cells, which were frequently positive for tumor necrosis factor-alpha. HIV p24 antigen, when present, was found on macrophages and microglia. Endothelial cells were frequently positive for interleukin-1 and interferon gamma and less frequently for tumor necrosis factor and interleukin-6. There were gliosis and significant increases in MHC class II antigen, interleukin-1, and tumor necrosis factor-alpha in HIV-positive patients compared to HIV-negative brains. Cerebrospinal fluid from most of the patients tested had increased levels of tumor necrosis factor, beta 2-microglobulin, and neopterin. There was no correlation in HIV-positive individuals between levels of cytokines and the presence or absence of CNS disease. These data indicate that there is a relative state of "immune activation" in the brains of HIV-positive compared to HIV-negative individuals, and suggest a potential role for the immune system in the pathogenesis of HIV encephalopathy.