Long-term remission in progressive multifocal leukoencephalopathy caused by idiopathic CD4+ T lymphocytopenia: a case report.

Progressive multifocal leukoencephalopathy is caused by JC virus, an opportunistic infection of the central nervous system. Antiretroviral treatment for progressive multifocal leukoencephalopathy in human immunodeficiency virus-infected patients is beneficial, but few data exist for patients who are not infected with human immunodeficiency virus. Idiopathic CD4+ T lymphocytopenia excludes human immunodeficiency virus infection. We describe a patient with progressive multifocal leukoencephalopathy with underlying idiopathic CD4+ T lymphocytopenia in whom functional recovery occurred without antiviral therapy.

Characterizing complex chemosensors: information-theoretic analysis of olfactory systems.

The mechanisms that underlie a wine lover's ability to identify a favorite vintage and a dog's ability to track the scent of a lost child are still deep mysteries. Our understanding of these olfactory phenomena is confounded by the difficulty encountered when attempting to identify the parameters that define odor stimuli, by the broad tuning and variability of neurons in the olfactory pathway,and by the distributed nature of olfactory encoding. These issues pertain to both biological systems and to newly developed 'artificial noses' that seek to mimic these natural processes. Information theory, which quantifies explicitly the extent to which the state of one system (for example, the universe of all odors) relates to the state of another (for example, the responses of an odor-sensing device),can serve as a basis for analysing both natural and engineered odor sensors. This analytical approach can be used to explore the problems of defining stimulus dimensions, assessing strategies of neuronal processing, and examining the properties of biological systems that emerge from interactions among their complex components. It can also serve to optimize the design of artificial olfactory devices for a variety of applications, which include process control, medical diagnostics and the detection of explosives.

Progressive multifocal leucoencephalopathy: analysis of JC virus DNA from brain and kidney tissue.

JC virus-specific DNA from both brain and kidney of the PML case G.S. was analysed by restriction mapping and Southern blot analysis. The genome of JCV DNA from brain (JCV GS-B) was full length, whereas JCV DNA GS from kidney (JCV GS-K) was 120 bp smaller. Restriction maps, constructed from JCV GS-B using various enzymes showed that most cleavage sites were consistent with standard map sites. Comparison of virus DNA from brain and kidney revealed that JCV GS-specific cleavage sites were identical, and that the DNAs were therefore of the same subtype. The deletion in kidney DNA was situated in the area of the origin of replication which is known to be hypervariable in the JCV genome. Restriction maps revealed that the DNA from each organ was homogeneous in length but a proportion of the DNA molecules were heterogeneous in restriction sites. It is concluded from these data that initial infection with one JCV subtype was followed by the development of heterogeneous DNA molecules.

Quantification of human polyomavirus JC in brain tissue and cerebrospinal fluid of patients with progressive multifocal leukoencephalopathy by competitive PCR.

Activation of human polyomavirus JC (JCV) infection is the cause of the central nervous system (CNS) disease progressive multifocal leukoencephalopathy (PML). Previous studies with uncontrolled quantification systems suggested that the virus load in the CNS correlates with the state of disease and might reflect therapeutic effects. Therefore the aim of this study was the development of a competitive system with standard PCR techniques that allowed rapid detection of JCV subtypes, simultaneous differentiation of the two human polyomaviruses JCV and BKV and absolute quantification of the virus burden in initial diagnosis and progressive disease states. Subtype- and species-specificity of the PCR was achieved with the development of a degenerative PCR primer pair that detected JCV DNA in a range regularly found in PML samples, but did not amplify BKV DNA. The accuracy of the system was evaluated by quantification of known amounts of cloned JCV DNA with a competitive JCV-specific template that exhibited a comparable amplification rate to that of the native product. The calibration study demonstrated a linear correlation over a wide range of DNA concentrations on the background of buffer or JCV-negative diagnostic samples. The reliability of the system for PML diagnosis was analysed by calibration and determination of the virus burden in tissue and cerebrospinal fluid (CSF) of 11 PML patients confirming the accuracy in both types of samples under diagnostic conditions. Comparison of the JCV DNA concentration in tissue and CSF by a tightly controlled quantification technique revealed for the first time differences in a range of about four orders of magnitude and a variable virus load in CSF samples taken at comparable states of disease. This pointed to an individual course of virus shedding and demonstrates that a controlled competitive PCR system of high accuracy is essential for reliable quantification of virus DNA either in initial diagnosis, in progressive disease or for the evaluation of therapeutic effects.

Focal brain lesions in patients with AIDS: aetiologies and corresponding radiological patterns in a prospective study.

We report the results of a hospital-based study of 188 consecutive patients seropositive for the human immune deficiency virus type 1 (HIV-1) who presented in a 4-year period (1988-1991) with possible signs or symptoms of first-ever central nervous system disease. Confirmed diagnoses were cerebral toxoplasmosis in 47 patients (25.0%), HIV-1 encephalopathy in 19 (10.1%), progressive multifocal leucoencephalopathy (PML) in 9 (4.8%), cerebral lymphoma in 1 (0.5%), and other conditions in 9 patients (4.8%). Seventy-three subjects (38.8%) showed focal brain lesions on initial computed tomography or magnetic resonance imaging, which were assessed prospectively. Positive predictivity for toxoplasmosis was 100% if multiple lesions occurred in combination with mass effect or contrast enhancement (23 patients), or if at least one space-occupying or enhancing lesion was located in the basal ganglia or the thalamus (26 patients). Solitary lesions with mass effect or contrast enhancement were seen in 26 patients and were caused by cerebral toxoplasmosis in 22 (84.6%). Eight of the 9 PML patients presented with one or more non-enhancing, non-mass lesions, although the predictive value of this pattern was low (47.1% for PML). Thus, in our epidemiological context, certain imaging findings in HIV-1-seropositive patients were highly predictive of cerebral toxoplasmosis. This may differ from findings from other parts of the world where cerebral toxoplasmosis may be less prevalent among HIV-1-infected individuals.

Diagnostic criteria and clinical procedures in HIV-1 associated progressive multifocal leukoencephalopathy.

The diagnosis of definite progressive multifocal leukoencephalopathy (PML) has been a neuropathological domain. We reviewed all Human Immunodeficiency Virus Type 1 (HIV-1) seropositive patients in our institution between 01.01.1989 and 31.12.1994 and identified 20/823 cases with PML by clinical and imaging criteria. Diagnosis was neuropathologically confirmed in 5 cases. Diagnostic criteria included rapid onset (< 2 weeks) of multifocal neurological signs and symptoms, advanced immunosuppression and asymmetric uni- or multifocal white matter lesions without mass effect, contrast enhancement or cortical atrophy in magnetic resonance imaging (MRI). The overall incidence of PML was stable over the observation period (approximately equal to 2.5%). The mean age at onset (41.7 years) was significantly lower compared to HIV-1 seronegative PML patients (peak in the sixth decade of life), male patients prevailed (100%). Mean survival (3.9 months) was extremely short. Human polyoma virus JC (JCV) polymerase chain reaction (PCR) in the cerebrospinal fluid (CSF) demonstrated a considerable rate of possible cerebral co-infection with HIV-1 and JCV as well as subclinical infection with JCV. Therefore demonstration of JCV deoxyribonucleic acid by PCR in the CSF alone is not sufficient for clinical PML diagnosis. We present diagnostic criteria on the basis of epidemiological, neuroradiological and CSF parameters that allow us to make the clinical diagnosis of PML. Although quick and safe, routine stereotactic brain biopsy is not necessary to confirm the diagnosis.

Olfactory sensitivity to the pheromone, androstenone, is sexually dimorphic in the pig.

Sexually dimorphic pheromone pathways have been used successfully to study insect olfactory coding. As one of the few mammalian species with an identified sex pheromone, the domestic pig (Sus scrofa) may be an ideal vertebrate species in which to examine sex differences in olfactory processing of a specific stimulus. In this experiment, androstenone and control odor detection thresholds were measured in adult male, female, and castrated male pigs. In an operant task, pigs were tested with descending concentration series of both androstenone and geraniol. All groups were equally sensitive to geraniol, but there was a sex difference in sensitivity to the odor of androstenone. Female pigs' detection threshold was a dilution fivefold lower than the threshold for intact males. Castrated males did not differ significantly from either males or females. This is the first example of a sexual dimorphism in sensitivity to a mammalian pheromone.

Understanding the pathophysiology of vasomotor symptoms (hot flushes and night sweats) that occur in perimenopause, menopause, and postmenopause life stages.

Vasomotor symptoms (VMS), commonly called hot flashes or flushes (HFs) and night sweats, are the menopausal symptoms for which women seek treatment during menopause most often. VMS are a form of temperature dysfunction that occurs due to changes in gonadal hormones. Normally, core body temperature (CBT) remains within a specific range, oscillating with daily circadian rhythms. Physiological processes that conserve and dissipate heat are responsible for maintaining CBT, and tight regulation is important for maintenance of optimal internal organ function. Disruption of this tightly controlled temperature circuit results in exaggerated heat-loss responses and presents as VMS. The mechanistic role related to changes in gonadal hormones associated with VMS is not understood. Hormone therapy is the most effective treatment for VMS and other menopausal symptoms. Estrogens are known potent neuromodulators of numerous neuronal circuits throughout the central nervous system. Changing estrogen levels during menopause may impact multiple components involved in maintaining temperature homeostasis. Understanding the pathways and mechanisms involved in temperature regulation, probable causes of thermoregulatory dysfunction, and "brain adaptation" will guide drug discovery efforts. This review considers the processes and pathways involved in normal temperature regulation and the impact of fluctuating and declining hormones that result in VMS during the menopausal transition.

Molecular biology and pathogenesis of human polyomavirus infections.

The two human polyomaviruses JC and BK are ubiquitous in the human population. Primary infection leads to lifelong persistence in the kidney, the CNS and in lymphoid cells. Virus is shed into the urine and is transmitted at least in part by the oral route. Under limited changes of the immunological state persistent polyomavirus infection is activated to an asymptomatic virus production. However, in severe long-lasting immunosuppression, highly effective virus multiplication can be accompanied by extended cytolytic damage of viral target cells leading to fatal disease. Whereas BKV is associated with severe urogenital disorders, JCV affects the CNS, leading to progressive multifocal leukoencephalopathy (PML). Although the number of PML cases is steadily increasing because of the AIDS epidemic, the mechanisms responsible for the change from asymptomatic-activated to the diseased state are not yet understood. As a possible pathogenic factor, the role of genomic heterogeneity of the transcriptional control region in the induction of disease is discussed.

Virus-host interactions and diagnosis of human polyomavirus-associated disease.

Persistent human polyomavirus infection is asymptomatic with limited states of virus production in the healthy individual, in immunocompromised patients, however, infection may lead to uncontrolled virus growth and fatal disease. Predominantly the CNS and in rare cases the urogenital tract are affected. During the AIDS epidemic, the number of cases is steadily increasing, thus dictating the need for an early and fast differential diagnosis. Virological diagnosis is essentially based on the detection of virus products in tissue or body fluids. Although sensitive and specific diagnostic techniques are available for the diagnosis of polyomavirus infection, widely accepted standards are not yet reached. This is in part due to the low number of cases in the past, but also to asymptomatic viral activation in nondiseased patients. Thus, additional parameters have to be evaluated to provide complementary tools for differential diagnosis.

Nucleotide sequence and genome organization of the murine polyomavirus, Kilham strain.

The polyomavirus Kilham strain (KV) represents a second murine member of the polyomavirus family. However, in contrast to other polyomaviruses, KV exhibits a stringent host and cell specificity. To determine the relationship of these viruses, the complete DNA sequence of KV consisting of 4754 bp was determined. The predicted organization of K virus was found to be comparable to that of other members of the polyomavirus family with two strands coding in an opposite direction of an intergenic region harboring putative control elements for gene expression. These include consensus elements for the origin of DNA replication as well as predicted promoter protein binding domains. Inferred signal sequences for 3' and 5' end formation of mRNAs and splice/branch site consensus sequences resemble those found among the SV40 group of viruses. From the organization of the genome two nonstructural proteins, large T and small t antigen, are predicted, both of which share the same amino-terminal sequence. Three putative capsid proteins VP1, VP2, and VP3 are encoded by alternative open reading frames. The nucleotide sequence in the proposed origin of DNA replication and the inferred amino acid sequence of the viral proteins suggest an evolutionary relationship placing KV between the murine PyV and the SV40 group of viruses. In the region bearing putative transcriptional control elements less nucleotide similarity to that of other polyomaviruses is found and this may reflect the unique host and cell specificity of KV.

Evidence of human polyomavirus BK and JC infection in normal brain tissue.

Infection with the polyomaviruses JC and BK is ubiquitous in the human population and JCV is the only virus associated with the central nervous system disease progressive multifocal leukoencephalopathy. In the attempt to analyze the pathogenesis of polyomavirus infections we asked whether human polyomaviruses invade the brain during persistence. Brain autopsy material from 67 individuals with disorders other than PML was examined for the presence of polyomavirus DNA. Southern blot analysis demonstrated JCV-specific full-length virus genomes in healthy brain tissue in about 20% of the patients. Type-specific analysis with polymerase chain reaction and sequencing confirmed these data. Additionally, the presence of BKV DNA sequences covering an early gene fragment and the control region with flanking early and late protein coding sequences was detected. Cloning of the complete BKV genome from two cases supported the assumption that not only full-length JCV DNA was present in those tissue specimens but also BKV genomes. The data obtained demonstrate that dual infection of the brain with the polyomaviruses JCV and BKV is a common event and give strong evidence that both viruses frequently establish a latent CNS infection.

DNA rearrangements in organ-specific variants of polyomavirus JC strain GS.

Variants of JC virus (JCV) strain GS were isolated directly from the central nervous system (variant GS/B) and the kidney (variant GS/K) of a patient with progressive multifocal leukoencephalopathy and were cloned and sequenced. The genomes of the isolates were shown to be nearly identical in the nucleotide sequences of their protein-coding regions, suggesting that both had originated from a single infecting JCV genome. In contrast, the arrangement of the putative elements of transcriptional control revealed considerable differences. The tandemly repeated elements found twice within the enhancer region of JCV GS/B variant were not present in the GS/K variant. The missing elements were replaced by DNA segments containing simian virus 40 and adenovirus E1A core enhancer elements. These differences in the organ-specific GS variants suggest that rearrangements within elements of transcriptional control might be involved in altering the virus-cell interaction in the course of a JCV infection.

Expression of human polyomavirus JC T antigen by an adenovirus hybrid vector and its binding to DNA sequences encompassing the JC virus origin of DNA replication.

In the search for factors that influence the outcome of human polyomavirus JC (JCV) infection, the roles not only of host-related immunological control but also of virus-dependent regulatory steps have to be taken into account. Besides cell-specific control of early expression of the multifunctional virus protein large tumour antigen (T Ag), control mechanisms involve individual steps of the DNA replication process. For the analysis of T Ag DNA binding, the protein was expressed by an adenovirus hybrid vector in the 293 cell line to provide saturating amounts of JCV T Ag. After determination of the size and immunoreactivity, functional activity was analysed by specific DNA binding. To avoid the interference of cellular proteins, T Ag was immunoprecipitated prior to the reaction. Binding to T Ag-binding sites I and II within a 141 bp DNA segment in the control region was analysed using deletion mutants of a JCV subtype from brain tissue of a patient with fatal central nervous system disease. The specificity of the binding was confirmed by recombinant T Ag binding to origin of DNA replication (ori) sequences of wild-type JCV genomes. These data document that recombinant T Ag overexpressed by the adenovirus vector in eukaryotic cells was JCV-specific, had the expected length and exhibited specific ori-binding activity, thus providing the essential tool for future analysis of virus-host interactions at the level of viral DNA replication.

Human polyomavirus JC control region variants in persistently infected CNS and kidney tissue.

The question of a possible role for JC virus (JCV) genomic rearrangements in the pathogenesis of progressive multifocal leukoencephalopathy (PML) was addressed by analysis of the genomic complexity and the transcriptional control region (TCR) of the JCV DNA population in persistently infected CNS and kidney tissue. After cloning of full-length viral DNA, no extensive changes were detected in the coding regions of the JCV genome by restriction analysis suggesting an intact JCV DNA population. For further analysis of the distribution of JCV subtypes, the non-coding region was amplified by PCR. Molecular analysis revealed homogeneous JCV TCR populations in almost 50% of the individuals. Heterogeneity was found in two CNS samples with three and five different JCV subtypes, respectively, and in four kidney specimens with two TCR subtypes. Altogether, seven TCR subtypes were identified. One in each group represented single promoter element TCRs without duplication of sequences. The TCR of the major variant JCV-W1 was comparable in sequence and structure to that of the PML prototype JCV Mad-1 DNA. The identification of dominant PML-derived JCV TCR subtypes in most persistently infected individuals suggests that rearrangements of the JCV TCR can be associated with the persistent state of infection. However, it appears unlikely that PML-associated JCV subtypes are generated anew in each individual host in the course of persistence. The findings rather suggest that a limited number of stable JCV subtypes circulate in different geographical regions of the world.

Progressive multifocal leucoencephalopathy: detection of papovavirus JC in kidney tissue.

Cellular DNA of the kidney from a patient with PML was analyzed by reassociation kinetics for the presence of JC virus DNA. Various amounts of viral DNA sequences were detected in different areas of the kidney. The highest concentration (175 genome equivalents/cell) was found in the renal medulla and there were almost none in the renal cortex. Differentiation from the closely related BK virus was carried out by reassociation kinetics and restriction enzyme cleavage with subsequent Southern blot analysis. The enzyme Hind II, which does not cleave within the BK virus genome, generated four restriction enzyme fragments in the cellular DNA from the kidney, thus documenting the presence of JC virus DNA. By examination of the renal DNA with the "no-cut" restriction enzyme XHO I and the "one-cut" enzymes Eco RI and BAM HI it was possible to show that free and not integrated viral DNA was present in these cells. Nonhomogeneous defective DNA bands were not detectable. By in situ hybridization the epithelial cells lining the collecting tubules were found as predominant site of the viral infection in the kidney.

Association of polyomaviruses JC, SV40, and BK with human brain tumors.

Human brain tumors of 11 different types were analyzed by Southern blot analysis for the presence of JCV, SV40, and BKV. In 21 tumor specimens examined with JCV- and SV40-specific probes no positive hybridizations were obtained. Analysis for BKV DNA, however, revealed the presence of BKV-specific sequences in 11 of 24 tumor specimens. No hybridization was found in DNA from CNS tissues from different areas of 29 individuals without CNS tumors. The BKV DNA sequences were associated with high molecular weight cellular DNA, suggesting a chromosomal location. These data provide evidence for the involvement of BKV in the development of human brain tumors.