The neurologic complications of human immunodeficiency virus infection

CRMP-2 peptide mediated decrease of high and low voltage-activated calcium channels, attenuation of nociceptor excitability, and anti-nociception in a model of AIDS therapy-induced painful peripheral neuropathy

Background

The ubiquity of protein-protein interactions in biological signaling offers ample opportunities for therapeutic intervention. We previously identified a peptide, designated CBD3, that suppressed inflammatory and neuropathic behavioral hypersensitivity in rodents by inhibiting the ability of collapsin response mediator protein 2 (CRMP-2) to bind to N-type voltage-activated calcium channels (CaV2.2) [Brittain et al. Nature Medicine 17:822–829 (2011)].

Results and discussion

Here, we utilized SPOTScan analysis to identify an optimized variation of the CBD3 peptide (CBD3A6K) that bound with greater affinity to Ca²⁺ channels. Molecular dynamics simulations demonstrated that the CBD3A6K peptide was more stable and less prone to the unfolding observed with the parent CBD3 peptide. This mutant peptide, conjugated to the cell penetrating motif of the HIV transduction domain protein TAT, exhibited greater anti-nociception in a rodent model of AIDS therapy-induced peripheral neuropathy when compared to the parent TAT-CBD3 peptide. Remarkably, intraperitoneal administration of TAT-CBD3A6K produced none of the minor side effects (i.e. tail kinking, body contortion) observed with the parent peptide. Interestingly, excitability of dissociated small diameter sensory neurons isolated from rats was also reduced by TAT-CBD3A6K peptide suggesting that suppression of excitability may be due to inhibition of T- and R-type Ca²⁺ channels. TAT-CBD3A6K had no effect on depolarization-evoked calcitonin gene related peptide (CGRP) release compared to vehicle control.

Conclusions

Collectively, these results establish TAT-CBD3A6K as a peptide therapeutic with greater efficacy in an AIDS therapy-induced model of peripheral neuropathy than its parent peptide, TAT-CBD3. Structural modifications of the CBD3 scaffold peptide may result in peptides with selectivity against a particular subset of voltage-gated calcium channels resulting in a multipharmacology of action on the target.

Coxsackie B meningoencephalitis in a patient with acquired immunodeficiency syndrome and a multiple sclerosis-like illness

Both Coxsackie infection and multiple sclerosis (MS) are rare in human immunodeficiency virus (HIV) infection. We report a 35-year-old woman with known HIV infection of 12 years' duration and a clinical illness of 4 years' duration consistent with MS. The latter was characterized by optic neuritis, bilateral abducens palsies, recurrent Bell's palsy, hemiparesis, and ataxia coupled with white matter abnormalities on magnetic resonance imaging (MRI). Autopsy revealed Coxsackie B meningoencephalitis; no other infectious disease were detected and no histopathological features of MS were evident. We suggest that the relapsing-remitting neurological disease in this patient was the consequence of Coxsackie B meningoencephalitis. This is the first case report, to the best of our knowledge, of an enteroviral meningoencephalitis complicating human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS).

Differential sensitivity of thick and thin fibers to HIV and therapy-induced neuropathy

The study assessed HIV-related and anti-retroviral therapy-induced neuropathy in myelinated and unmyelinated nerve fibers. One hundred consecutive HIV patients were examined clinically and standard nerve conduction velocities were measured. In addition, electrically induced sympathetic skin response (SSR) was assessed in the palms and soles. The difference in delay of SSR in palms and soles (DeltaSSR) was calculated as an indirect measure of C-fiber conduction velocity. Thick fiber conduction velocities significantly decreased with age and increasing stage of the disease, whereas no effect of stage was found for DeltaSSR (p=0.6). In contrast, medication of at least one of the most known neurotoxic drugs zalcitabine, stavudine, or didanosine did not result in significantly lower conduction velocities in thick fibers (51.29+/-3.4 m/s vs. 50.86+/-3.5 m/s), but was related to an increased DeltaSSR. DeltaSSR allows an indirect measurement of C-fiber conduction velocity. In HIV this measure of unmyelinated sympathetic fibers was most sensitive to anti-viral treatment whereas conduction velocity of myelinated somatic fibers was more sensitive to disease-related neuropathy. The results suggest that HIV neuropathy preferably affects myelinated and anti-retroviral therapy unmyelinated fibers.

Utility of brain biopsy in patients with acquired immunodeficiency syndrome before and after introduction of highly active antiretroviral therapy

OBJECTIVE

This study investigates the changing indications, results, and practice patterns of brain biopsy in patients with acquired immunodeficiency syndrome (AIDS) as treatment evolved with the development of highly active antiretroviral therapy (HAART).

METHODS

We collected data on 246 patients with AIDS who were undergoing brain biopsy of intracranial lesions. Patients were managed in accordance with a uniform protocol. Patients were divided into two groups of those biopsied in the era before (1992-1996) or after (1997-2001) the use of HAART.

RESULTS

The introduction of HAART led to a steep decrease in the number of biopsies performed annually. The protocol functioned well. Diagnoses were obtained for 92.3% of patients. Lymphoma was the most frequent diagnosis (52.9% of patients), followed by progressive multifocal leukoencephalopathy (18.9% of patients) and toxoplasmosis (8.1% of patients). No patient who underwent lesion biopsy for reasons of negative toxoplasmosis titers or atypical radiology evaluation was diagnosed with toxoplasmosis. Nineteen patients who experienced failed toxoplasmosis treatment were diagnosed with toxoplasmosis. Toxoplasmosis titers had a high specificity and a negative predictive value. Patients with progressive multifocal leukoencephalopathy or nondiagnostic biopsies were more likely to have solitary lesions. The average Karnofsky performance score at the time of biopsy was 72.4, which is still within the range of independent functioning. Significant intracerebral hemorrhages were only observed in patients with lymphoma who also had low platelet counts.

CONCLUSION

Although the number of patients with AIDS who require brain biopsy has decreased, the procedure still has merits. The paradigm we developed was useful for selecting patients for early biopsy. Patients with AIDS who also have intracerebral lesions should have toxoplasmosis titers performed, and those whose titers are negative for toxoplasmosis should undergo early brain biopsy.

CXCR4 chemokine receptor signaling mediates pain hypersensitivity in association with antiretroviral toxic neuropathy

Nucleoside reverse transcriptase inhibitors (NRTIs) are known to produce painful neuropathies and to enhance states of pain hypersensitivity produced by HIV-1 infection. It has also been observed that in some neuropathic pain models, chemokines and their receptors are upregulated, perhaps contributing to the pain state. In order to understand if chemokines are involved in NRTI-mediated sensory neuropathies, we treated rats with the anti-retroviral drug, 2',3'-dideoxycytidine (ddC), which is known to produce an extended period of hyperalgesia and allodynia. Using in situ hybridization, we observed that under normal conditions, CXCR4 chemokine receptors were widely expressed by satellite glia in the dorsal root ganglia (DRG) and Schwann cells in the sciatic nerve. A limited number of DRG neurons also expressed CXCR4 receptors. The chemokine SDF-1/CXCL12 was similarly expressed in glial cells in the DRG and peripheral nerve. Following a single administration of ddC, expression levels of CXCR4 mRNA in glia and neurons and SDF-1 mRNA in glia increased considerably. The functional nature of increased CXCR4 mRNA expression was confirmed by measuring SDF-1 induced [Ca2+]i increases in acutely isolated DRG neurons and glia. In contrast, the expression of the chemokine receptors CCR2 and CCR5 did not change following ddC treatment. Pain hypersensitivity produced by ddC could be inhibited by treatment with the CXCR4 antagonist, AMD3100. Hence, we postulate that NRTIs produce pain hypersensitivity through the upregulation of CXCR4 signaling in the DRG. Increased numbers of CXCR4 receptors would also explain the synergism observed between NRTI treatment and the proalgesic effects of HIV-1 infection.

Polyomaviruses and human diseases

Polyomaviruses are small, nonenveloped DNA viruses, which are widespread in nature. In immunocompetent hosts, the viruses remain latent after primary infection. With few exceptions, illnesses associated with these viruses occur in times of immune compromise, especially in conditions that bring about T cell deficiency. The human polyomaviruses BKV and JCV are known to cause, respectively, hemorrhagic cystitis in recipients of bone marrow transplantation and progressive multifocal leukoencephalopathy in immunocompromised patients, for example, by HIV infection. Recently, transplant nephropathy due to BKV infection has been increasingly recognized as the cause for renal allograft failure. Quantitation of polyomavirus DNA in the blood, cerebrospinal fluid, and urine, identification of virus laden "decoy cells" in urine, and histopathologic demonstration of viral inclusions in the brain parenchyma and renal tubules are the applicable diagnostic methods. Genomic sequences of polyomaviruses have been reported to be associated with various neoplastic disorders and autoimmune conditions. While various antiviral agents have been tried to treat polyomavirus-related illnesses, current management aims at the modification and/or improvement in the hosts' immune status. In this chapter, we provide an overview of polyomaviruses and briefly introduce its association with human diseases, which will be covered extensively in other chapters by experts in the field.

Multiple Sclerosis–Like Clinical and Magnetic Resonance Imaging Findings in Human Immunodeficiency Virus Positive-Case

OBJECTIVE

Neurologic complications may develop during the course of acquired immunodeficiency syndrome. Differential diagnosis of the chronic progressive myelopathy related to human immunodeficiency virus must include multiple sclerosis.

CASE REPORT

We report a human immunodeficiency virus-positive case with progressive myelopathy who showed multiple sclerosis-like white matter lesions on cranial magnetic resonance imaging. Viral screening revealed positive serology for human immunodeficiency virus.

CONCLUSION

This case suggests that in a patient who presents with a multiple sclerosis-like clinical course and cerebral white matter lesions, a human immunodeficiency virus-related clinical picture should be taken into consideration in the differential diagnosis.

Phylogenetic evidence of widespread distribution of genotype 3 JC virus in Africa and identification of a type 7 isolate in an African AIDS patient

JC virus (JCV) is the cause of progressive multifocal leukoencephalophathy (PML) in immunocompromised patients. The paucity of reports from Africa has led to the hypothesis that PML is rare because of an absence of virus genotypes associated with the condition. Genotypes 3 and 6 have been identified in East and West Africa but the distribution of types across the rest of Africa is unknown. Full-length sequences of five JCV cerebrospinal fluid samples from PML patients in South Africa are reported here. Three isolates from African AIDS patients grouped with type 3A or 3B, and one with type 7, while one from a Caucasian leukaemia patient grouped with type 2D. Widespread distribution of type 3 on the continent may reflect migration patterns in antiquity, but this is the first report of type 7 in an African individual. Type 2D has only been isolated previously in South Asia, although transmission of this genotype to Europeans who later settled in South Africa is not unlikely.

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

The purpose of this article is to examine the prevalence, degree, and natural course of pupillary neuropathy (PANP), cardiovascular autonomic neuropathy (CANP), and sensorimotor neuropathy (SNP) and to study the impact of disease stage and medication on neuropathy in 61 consecutive patients with HIV. PANP, CANP, and SNP were assessed by standardized test procedures. Overall prevalence of PANP, CANP, and SNP were 66%, 15%, and 15%, respectively. The maximal pupillary area (pupillary measure, p <0.0001) and the lying-to-standing ratio (cardiovascular measure, p <0.0001) were abnormal as compared with control subjects. The changes in CD4+ T-lymphocytes and respiratory sinus arrhythmia percentile during 2 years of follow-up correlated significantly (r = 0.758, p = 0.007). Patients with CANP were more often in an advanced disease stage than patients without CANP (p = 0.004). SNP, but not PANP or CANP, was associated with the intake of the neuropathogenic drugs dideoxycytidine, dideoxyinosine, and 2',3' didehydro-2',3' dideoxythymidine (p <0.05). Autonomic and sensorimotor neuropathy are frequent in patients with HIV, and progression of CANP may put patients at risk for unexpected cardiorespiratory arrest.

Profile of central nervous system pathology in patients with AIDS: an autopsy study from India

OBJECTIVE

To study the spectrum of neuropathological brain lesions in HIV/AIDS cases.

DESIGN

Retrospective autopsy study between 1988 and mid-1996 at a tertiary level public hospital.

METHODS

Eighty-five adult brains, with at least 21 sections from each, were examined using routine and special stains.

RESULTS

Risk factors in 64 men (75%) and 21 women (25%) included heterosexual contact with multiple sexual partners (83 cases, 98%), homosexual behaviour (one case, 1%) and blood transfusion (one case, 1%). Central nervous system (CNS) lesions were observed in 67 cases (79%). Opportunistic infections were present in 33 cases (39%), which included toxoplasmosis (11 cases, 13%), tuberculosis (10 cases, 12%), cryptococcosis (seven cases, 8%), and cytomegalovirus infection (six cases, 7%). Multifocal myelin loss was observed in 18 cases (21%), microglial nodules in 15 cases (18%), and angiocentric pallor in five cases (6%). Infarcts/haemorrhages were present in 13 cases (15%), choroid plexitis in 21 cases (25%), lymphocytic meningitis without opportunistic infection in 21 cases (25%), and calcification in four cases (5%). A dual infectious pathology was observed in one case (1%). Multinucleated giant cells and primary CNS lymphoma were not found in any of our cases.

CONCLUSIONS

Patient profile and risk factors for AIDS in India differ from those reported in industrialized countries. Although not reported from India in the pre-AIDS era, toxoplasmosis was the most frequently observed CNS opportunistic infection in our study. CNS tuberculosis is frequently observed in Indian AIDS cases compared with reports from industrialized countries where its occurrence is uncommon. Death due to systemic opportunistic infections may punctuate the course of HIV encephalitis and prevent its full-blown morphological expression.

Cerebellar degeneration associated with human immunodeficiency virus infection

Cerebellar disorders associated with HIV infection are typically the result of discrete cerebellar lesions resulting from opportunistic infections such as toxoplasmosis and progressive multifocal leukoencephalopathy or primary CNS lymphoma. Clinical symptoms and pathologic abnormalities related to the cerebellum may also be observed with HIV dementia. A primary cerebellar degeneration with HIV has not previously been reported. Ten patients were identified over an 8-year period at five medical centers. All patients had clinical, laboratory, and radiologic evaluations, and three had neuropathologic examinations. Patients presented with progressively unsteady gait, slurred speech, and limb clumsiness. Examination revealed gait ataxia, impaired limb coordination, dysarthria, and abnormal eye movements. Cognition, strength, and sensory function remained normal. CD4 lymphocyte counts varied between 10 and 437 cells/mm3. Neuroimaging studies showed prominent cerebellar atrophy. Neuropathology showed focal degeneration of the cerebellar granular cell layer and unusual focal axonal swellings in the brainstem and spinal cord. Cultures, histopathology, and immunochemical studies showed no conclusive evidence of infection. We report a syndrome of unexplained degeneration of the cerebellum occurring in association with HIV infection.

Neuroleptic malignant syndrome in the acquired immunodeficiency syndrome

Patients infected by the human immunodeficiency virus are predisposed to many infectious and noninfectious complications and often receive a variety of drugs. Furthermore, they seem to have a particular susceptibility to idiosyncratic adverse drug reactions. It is therefore surprising that only a few cases of the neuroleptic malignant syndrome have been described in patients with the acquired immunodeficiency syndrome. A high index of suspicion is required to diagnose the neuroleptic malignant syndrome in these patients, as its usual manifestations, including fever and altered consciousness, are frequently attributed to an underlying infection.

HIV-related neurological disability and prospects for rehabilitation

The worldwide epidemic of acquired immunodeficiency syndrome (AIDS) continues to expand. Modest progress in prolonging survival has focused attention on the issue of quality of life among persons living with AIDS. Physical functional status (disability) is one of the most important determinants of quality of life. This paper outlines a conceptual approach to AIDS disability and provides new data examining the epidemiology of physical functional deficits in the population. In addition, the common neuromuscular and central neurological impairments encountered in AIDS are discussed with suggestions for potential rehabilitation interventions. The paper concludes with the author's view of the future of rehabilitation in persons with AIDS and human immunodeficiency virus infection.

AIDS and cerebrovascular disease

BACKGROUND

Although neurological complications of human immunodeficiency virus (HIV) infection are common, the presence of cerebrovascular disease (CVD) has been seldom reported. The purpose of this report is to review available data on the association between stroke and acquired immunodeficiency syndrome (AIDS).

SUMMARY OF REVIEW

A review of all literature published between mid-1976 and December 1994 was performed through a MEDLINE search with the following key words: AIDS, CVD, human T-cell lymphotropic virus type III, and HIV-1. Only reports of clinical stroke in patients with AIDS or HIV infection and autopsy series with stroke findings were selected. The type of study, population, number of stroke patients, subtype and etiology of stroke, and associated AIDS conditions were described. Six clinical series and 11 autopsy series were found, with a total of 1885 cases with AIDS, AIDS-related complex, and HIV carriers. Forty percent had a neurological complication, but only 1.3% had a stroke syndrome. Ischemic infarcts were more common than intracerebral hemorrhages. Cerebral infarcts were generally due to nonbacterial thrombotic endocarditis or concomitant opportunistic central nervous system infection, and intracerebral hemorrhages were usually associated with thrombocytopenia, primary central nervous system lymphoma, and metastatic Kaposi's sarcoma. Autopsy findings of CVD were generally not related with clinical stroke before death. Data are not available to determine the role of risk factors for AIDS in CVD.

CONCLUSIONS

Because of limitations of the available data, it is still not clear whether there is an association between AIDS and stroke. Further studies are needed to better define the epidemiology of CVD in association with AIDS.

Focused review: physiatric management of HIV-related disability

Since 1981, the epidemic of acquired immunodeficiency syndrome (AIDS), due to infection with human immunodeficiency virus (HIV), has grown and challenged health care providers in the United States. Although the total number of AIDS cases diagnosed each year appears to be reaching a plateau, cases attributable to heterosexual transmission are rising. With improved treatment, survival of persons with HIV infection is expected to increase; this change suggests that the prevalence of HIV-related physical disability will also increase. This article outlines the pathophysiology and systemic manifestations of HIV infection. The more common neuromuscular and neurological complications at each stage of the disease are presented, and appropriate rehabilitation interventions are discussed. The indications for aerobic exercise in persons with HIV infection and the approach to disability management in pediatric HIV infection are presented. Psychosocial considerations related to access to rehabilitations services, discrimination on the basis of HIV infection or membership in HIV risk behavior groups, and vocational rehabilitation are discussed. The review concludes that rehabilitation interventions in persons with HIV infection are based on functional deficits, rather than disease processes, suggesting that a general physiatric fund of knowledge should be adequate to manage most HIV disability.

Genotype profile of human polyomavirus JC excreted in urine of immunocompetent individuals

The human polyomavirus JC (JCV) causes the central demyelinating disease progressive multifocal leukoencephalopathy in about 5% of AIDS patients. To characterize the type profile of JCV in a control population in the United States, 54 females (10 to 79 years of age; average age, 43.4 years) and 51 males (18 to 94 years of age; average age, 47.9 years) were examined for the excretion of different genotypes of JCV in their urine by PCR followed by direct cycle sequencing. The group consisted of 89 patients of a general medical clinic in addition to 16 healthy volunteers. The overall incidence of JC viruria was 43 of 105 (40.9%) subjects, with a marked increase for those subjects above the age of 30 years. Two men were found to excrete two different types of JCV at the same time, indicating double infections. Of the three different genotypes of JCV identified to date, type 1 strains (European) were the most common in this cohort (64% of total strains) followed by type 2 (East Asian) (18%). No type 3 (East African) strains were detected. Indirect evidence for the existence of JCV type 3 was found in seven individuals (16%) in the form of a type 1/3 recombinant (also called type 4). In addition, a single example of JCV which differs from types 1, 2, and 3 and may represent a phylogenetically older type (type 5) was found in a 59-year-old African-American. Delineation of sequence variations between JCV types is essential for the design of primers for sensitive PCR with clinical samples.

BK virus and a new type of JC virus excreted by HIV-1 positive patients in rural Tanzania

HIV-1 positive patients from Tanzanian villages near Shirati were examined for urinary excretion of the human polyomaviruses JC and BK using the polymerase chain reaction (PCR). BK virus (BKV) was detected in 11 of 23 individuals tested. The BKV DNA sequences were all closely related to prototype Gardner strain and BKV (DUN). In contrast, a new type of JCV, termed Type 3 [or JCV (Shi)], was identified in seven of these same 23 individuals by comparison with Type 1 and Type 2 sequences of the VP1/intergenic/T antigen region of U.S., European and Asian strains. This suggests that JCV and BKV, although closely related, have different evolutionary histories within the African population. The six BKV regulatory regions amplified all showed the archetypal configuration. However, two of the seven JCV regulatory regions showed rearrangements: a small deletion and an inverted repeat. JCV causes a fatal demyelinating disease, progressive multifocal leukoencephalopathy (PML), in about 5% of AIDS patients in Europe and the U.S.A., but only one case has been reported in Africa. Our results suggest that this rarity of PML is not due to the absence of JCV in the African population.

Opioid use in HIV patients with neurological changes

The neurological changes that are common in the HIV population may complicate the use of analgesics, particularly opioids. These changes, in combination with care providers' fear of opioids, often lead to the inappropriate use of antagonists, such as naloxone. Used injudiciously, naloxone can lead to withdrawal syndrome, return of severe pain, and other adverse effects. The authors describe the many disease and treatment-related causes for pain in patients with HIV disease, as well as common neurologic conditions that alter cognition and complicate the use of opioids. A case study is included to illustrate the dangers of inappropriate naloxone use.

AIDS presenting as progressive multifocal leukoencephalopathy with clinical response to zidovudine

Progressive multifocal leukoencephalopathy (PML) due to JC virus can be the initial manifestation of AIDS. A 40-year-old man seropositive for HIV-1 presented with aphasia, hemiparesis, and hemianopsia, and with magnetic resonance imaging of the brain typical of PML. He quickly became bed bound, incontinent, and mute. The diagnosis of PML was established by histopathology in a brain biopsy with positive immunocytochemistry for polyomavirus capsid proteins, and detection of JCV DNA by polymerase chain reaction using JCV-specific primers. High dose zidovudine therapy was initiated (1200 mg/day). Within two weeks the patient began to respond, and after three months he was able to walk and care for himself and was discharged. He lived for two years from the onset of PML. While cytarabine has been the drug most widely used for PML treatment, this is the second confirmed case with apparent response to zidovudine. High dose zidovudine may benefit some previously untreated AIDS patients with onset as PML.

Evaluation and treatment of HIV-related illnesses in the emergency department

Individuals infected with the human immunodeficiency virus (HIV) present frequently to emergency departments for treatment of complications. A working knowledge of the multisystem problems seen in HIV-infected patients is essential for the emergency physician. These problems are reviewed, with an emphasis on the respiratory, central nervous system, and gastrointestinal complications seen in patients with the acquired immune deficiency syndrome (AIDS). A practical approach is offered for management of febrile episodes and the other problems an emergency physician is likely to encounter.

Differential expression of mRNAs for JC virus large and small tumor antigens in brain tissues from progressive multifocal leukoencephalopathy patients with and without AIDS

JC virus (JCV) causes progressive multifocal leukoencephalopathy (PML), the fatal demyelinating infection of oligodendrocytes, in up to 5% of AIDS patients. An intron-differential RNA PCR was developed to study the expression of alternately spliced JCV early mRNAs in brain tissues from PML patients with and without AIDS and in JCV-induced hamster brain tumors. The method utilizes primers that span the large tumor (T) and small tumor (t) antigen introns allowing amplification of specific cDNAs in the presence of contaminating viral genomic DNA. Hybridization with specific junctional probes and DNA sequence analysis confirmed the identity of the PCR products. Sequencing showed that JCV early mRNA is alternatively spliced as previously predicted by analogy to simian virus 40. Large T antigen mRNA was detected in all the brain tissues from PML patients with and without AIDS. The expression of small t antigen mRNA varied depending upon the association of PML with AIDS and upon other unknown factors. Of the 12 PML/AIDS brain tissue samples, 11 (92%) expressed small t antigen mRNA, whereas only 8 of 13 (62%) brain samples from patients with PML alone showed detectable levels of small t antigen mRNA. Human immunodeficiency virus 1 proviral DNA was detected in 10 of 12 PML/AIDS brain samples. The results indicate that alternative splicing of JCV early mRNA is regulated in the human brain and that the production of small t antigen may not be essential for the pathogenesis of PML.

The acquired immune deficiency syndrome: an overview for the emergency physician, Part 2

Human immunodeficiency virus (HIV) affects all organ systems. Infection of the heart can manifest with evidence of myocarditis, pericarditis, or cardiomyopathy. The most common gastrointestinal symptom is diarrhea, which can result from infection with a variety of bacterial, fungal, or protozoal organisms. In about 15% of cases, no pathogen is recognized and the diarrhea syndrome is termed AIDS enteropathy. Any portion of the alimentary tract can be affected as well as the liver, gallbladder, and pancreas. Cryptosporidium, a previously infrequent cause of human illness, has emerged as an important pathogen in the HIV-infected patient and is responsible for chronic diarrhea, cholecystitis, and biliary tract obstruction. Evidence of neurologic involvement is present in more than 80% of patients at the time of autopsy. Cryptococcal meningitis, toxoplasma encephalitis, and neurosyphilis are the most often encountered central nervous system infections. While all three are responsive to therapy, treatment must be prolonged or persist for the duration of the patient's life to avoid recurrence. Peripheral nervous system manifestations include myelopathy, myopathy, and a variety of peripheral neuropathies. Retinal infection with cytomegalovirus (CMV) and toxoplasma can lead to irreversible loss of vision. Cotton wool spots are a common benign physical finding that must be differentiated from the early signs of CMV or toxoplasma infection. Management of the HIV-infected patient, while most often conducted by specialists in Internal Medicine or Infectious Diseases, is often an issue for the emergency physician. Many of the commonly afforded therapies are reviewed. Part 1 of this two-part series discussed the pathophysiology and clinical expression, epidemiology, laboratory testing, and the general clinical manifestations of AIDS, as well as dermatologic, pulmonary, and cardiac symptoms. Part 2 discusses the gastrointestinal, neurologic, and ocular symptoms, as well as the treatment and management of the AIDS patient.

Type-specific amplification of viral DNA using touchdown and hot start PCR

Two types of JC virus (JCV) are found in infected brain and kidney tissues. A highly reliable PCR assay to determine viral type in tissue is presented. This type-specific system is analogous to allele-specific PCR used to detect point mutations in cellular genes. Specific amplification of two fragments, using four pairs of type-specific primers, is based on a single nucleotide difference at the 3'-ends of the primers. A combination of three conditions in the PCR reaction was required for specificity: 'hot start', a ramped ('touchdown') cycle profile, and a slightly lowered molar concentration of the specific primers and dNTPs. Efficient yield of PCR product is not lost under these conditions, and even the least selective mismatches (C:A and T:G) provided specific amplification. Type-specific restriction enzyme sites within the amplified fragments confirm type designation.