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Biomedical subjects

D L Walker

Publications and source records attributed to D L Walker.

At least 91 records · Page 5Linked to original sources
PubMed1982

Distribution of papovavirus, myelin-associated glycoprotein, and myelin basic protein in progressive multifocal leukoencephalopathy lesions.

To study how viruses interact with oligodendroglia and produce demyelination, we immunostained paraffin and epon sections of lesions from patients with progressive multifocal leukoencephalopathy (PML) with antisera to papovaviruses, oligodendroglial myelin-associated glycoprotein (MAG), and myelin basic protein (MBP) according to the peroxidase-antiperoxidase method. In paraffin sections from a rapidly progressive case of PML, hyperimmune JC virus antiserum stained single oligodendroglia which were located in white matter that appeared normal histologically and stained normally with MAG and MBP antisera. In zones surrounding areas of demyelination, virus containing oligodendroglia were most numerous and MAG staining of periaxonal regions was decreased, but there was little change in MBP staining. In demyelinated regions, both MAG and MBP staining were severely altered; also there was much less JC virus staining. In tissue from three other chronic cases, viral antiserum stained fewer oligodendrocytes and the differences in MAG and MBP staining were much less striking. In epon sections from two biopsies of central nervous system tissue, we studied the electron microscopic appearance of oligodendroglia that also had been stained by JC virus antiserum. Virions were present in all nuclei and in some cytoplasmic regions. The results suggest that changes in MAG distribution are useful indicators of early oligodendroglial abnormalities which can cause myelin breakdown.

Aged↗
PubMed1982

Is progressive multifocal leukoencephalopathy a chronic disease because of defective interfering particles or temperature-sensitive mutants of JC virus?

JC virus was examined for temperature sensitivity and for evidence of defective interfering particles as a means of explaining the slow chronic nature of progressive multifocal leukoencephalopathy (PML). JC virus direct from the brain tissue of seven persons with PML was not temperature sensitive as indicated by in vitro assay at 37 and 39 degrees C. In fact, more cells contained viral antigen at 39 than at 37 degrees C. The amount of infectious virus also was increased at 39 degrees C. Virions isolated directly from diseased brain tissue had a higher buoyant density than did virus from the same PML patient passaged in culture and containing genomic deletions. In contrast to DNA from culture-passed virus, DNA extracted from virions direct from brain tissue was homogeneous in length. In 13 separate cases examined, the viral DNA direct from the brain was homogeneous although variations in length were noted among DNAs from different cases. Restriction enzyme cleavage patterns identified all as JC virus DNA. It was concluded that neither temperature sensitivity nor DI particles can be used to explain the slow, progressive nature of PML.

Adult↗
PubMed1980

Experimental glioma in primates: a computed tomography model.

Owl and squirrel monkeys inoculated intracerebrally with human polyomavirus obtained from the brain of patient with progressive multifocal leukoencephalopathy developed cerebral gliomas. Among these tumors, three out of five were detected and accurately localized by contrast enhanced computed tomography (CT) when the animals were still clinically normal. Various CT features of these tumors corresponded to specific pathologic changes, such as histologic type and presence of hemorrhage and necrosis. Also, tumor progression was clearly demonstrated in repeat scans of one animal. The CT sensitivity and the capability of distinguishing various pathologic features are encouraging. It appears that a much needed, suitable model of experimental cerebral tumors in primates is now available for CT studies.

Animals↗
PubMed1980

Rapid detection and identification of JC virus and BK virus in human urine by using immunofluorescence microscopy.

An indirect immunofluorescence method was developed and used to detect urinary excretion of abnormal transitional cells infected with JC virus (JCV) or BK virus (BKV). This method was compared with urinary cytology, electron microscopy, viral culture, and viral serology in groups of immunosuppressed renal transplant recipients and normal controls. The indirect immunofluorescence method detected and identified JCV excretion in four persons, BKV excretion in one person, and both JCV and BKV excretion in eight others. Viral antigen was identified only in the nuclei of cytologically abnormal cells. Of these 13 persons, 8 also had polyoma virions detected in the urine by electron microscopy. With repeated study of sequential urine samples, 30% of transplant recipients and 6% of normal controls were positive by one or more microscopy methods. Serological results confirmed a high incidence of both JCV and BKV multiplication in the immunosuppressed patients. However, serology did not correlate directly with urinary virological findings. Urinary cytology and the indirect immunofluorescence method were rapid and sensitive methods for detecting and identifying urinary excretion of JCV and BKV.

Adult↗
PubMed1980

Integration pattern of human JC virus sequences in two clones of a cell line established from a JC virus-induced hamster brain tumor.

The physical state of the JC virus (JCV) genome was studied in two clonal cell lines (clones 2 and 7) derived from a tissue culture cell line (HJC-15) established from a hamster brain tumor induced by JCV. Saturation-hybridization and reassociation kinetic analyses, using in vitro (32)P-labeled JCV DNA, indicated that clone 7 and 2 cells contain 9 to 10 and 4 to 5 copies per cell, respectively, of all or most of the viral genome. Both cell DNAs were analyzed by using the Southern blotting procedure with three restriction endonucleases: XhoI, which does not cleave JCV DNA; EcoRI, which cleaves once; and HindIII, which cleaves three times. With each DNA, a variety of JCV-specific DNA fragments were detected. The following conclusions are possible: (i) JCV DNA is integrated into cell DNA in both clonal lines; (ii) both clonal lines contain multiple copies of the viral genome integrated in a tandem head-to-tail orientation; (iii) neither clonal line contains detectable free-form I, II, or III JCV DNA; (iv) each clonal line contains multiple independent sites of JCV DNA integration; and (v) most or all of the sites of integration on the cellular or the viral genome, or both, are different in clone 7 DNA than in clone 2 DNA. Thus, although both clone 7 and clone 2 cells were established from the HJC-15 tumor cell line, they differ in the copy number and integration pattern of JCV DNA.

Animals↗
PubMed1980

Progressive multifocal leukoencephalopathy (PML): in vitro cell-mediated immune responses to mitogens and JC virus.

Cell-mediated immunity was studied by in vitro tests in seven patients with progressive multifocal leukoencephalopathy (PML). Lymphocyte proliferation in response to mitogenic stimulation was reduced to a variable degree in all patients, indicating a general impairment of cell-mediated immune responsiveness, although mitogen-induced production of the lymphokine migration inhibitory factor (LIF) was normal in most cases. Cell-mediated immunity to JC virus (JCV) was assessed by LIF production in response to JCV antigen. In the six PML patients tested, LIF production with JCV antigen was absent despite the presence of antibody to JCV in serum. This contrasted with positive LIF production in seropositive normal individuals and patients and patients with other diseases. These results provide the first in vitro evidence of a depressed cell-mediated immune response to JCV in patients with PML, and support the hypothesis that PML is accompanied by a selective marked deficiency in cellular response to this virus in association with a general depression of cell-mediated immunity of variable severity.

Adult↗
PubMed1980

Human polyomavirus infections with JC virus and BK virus in renal transplant patients.

Infection with the human polyomaviruses JC virus and BK virus was studied in 61 immunosuppressed renal transplant patients. Urine cytologic studies, indirect immunofluorescence microscopy, electron microscopy, and serologic studies were used to assess viral activity. Patients records were abstracted for events associated with polyomavirus infections. Polyomavirus excretion in urine was detected in 12 of 61 patients (20%). Eleven excreted JC virus and nine, BK virus. Fourfold hemagglutination-inhibition antibody titer rises occurred in 25 of 61 patients (41%). The serologic data suggested that most JC virus infections were primary, whereas most BK virus infections resulted from virus reactivation. During this 2-year study, 32 of 61 patients (52%) had evidence of active viral replication. Urinary tract excretion was associated with drug-requiring diabetes mellitus (P = 0.001), arterial occlusive disease (P = 0.03), and ureteral stricture with loss of renal function (P = 0.02). Antibody increases to BK virus were associated with a rising seurum creatinine (P = 0.02) and need for transplant biopsy (P = 0.02). Polyomavirus replication was therefore associated with an increased frequency of transplant related complications.

Adolescent↗
PubMed1979

Restriction endonuclease cleavage map of the DNA of JC virus.

A physical map of the sites cleaved by the following restriction endonucleases was derived for the DNA of JC virus, a human polyomavirus: EcoRI, HpaI, and PstI (one site each); HindII (four sites); and HindIII (three sites). By agarose gel electrophoresis of fragmented DNA, the size of full-length DNA of JC virus was estimated to be 5,125 +/- 105 base pairs (98 +/- 2% of the length of simian virus 40 DNA).

DNA Restriction Enzymes↗
PubMed1979

Infectivity of the DNA from four isolates of JC virus.

The infectivity of JC virus DNA was demonstrated in its most permissive cell culture, primary human fetal glial cells. The amount of infectivity observed in these heterogeneous cultures varied considerably between batches of cells. Contrary to results obtained with the papovaviruses simian virus 40 and BK virus, the calcium technique (F. L. Graham and A. J. van der Eb, Virology 52:456--467, 1973) was found to be more efficient at promoting JC virus DNA infectivity than the DEAE-dextran method (J. H. McCutchan and J. S. Pagano, J. Natl. Cancer Inst. 41:351--357, 1968): maximum infectivity titers of 4 x 10-(4) and 6 x 10(3) fluorescent cell units per microgram of DNA, respectively. These values represent an approximate recovery of infectivity from virus of between 0.02 and 0.14%. Comparisons of infectivity of DNAs obtained from four isolates of JC virus and which differed in their degrees of heterogeneity did not reveal significant differences. The JC virus DNA was not infectious in primary human fetal lung and kidney cells.

Antigens, Viral↗
PubMed1978

Brain tumors in owl monkeys inoculated with a human polyomavirus (JC virus).

Owl monkeys were inoculated intracerebrally, subcutaneously, and intravenously with JC, BK, or SV40 virus. Two of four adult owl monkeys inoculated with JC virus, a human polyomavirus, developed brain tumors at 16 and 25 months after inoculation, respectively. A grade 3 to grade 4 astrocytoma (resembling a human glioblastoma multiforme) was found in the left cerebral hemisphere and brainstem of one monkey. The second monkey developed a malignant tumor in the left cerebral hemisphere containing both glial and neuronal cell types. Impression smears prepared from unfixed tissue of this tumor showed cells that contained polyomavirus T antigen. Virion antigens were not detected. Tumor cells cultured in vitro also contained T antigen but were negative for virion antigen. Infectious virus was not isolated from extracts of this tumor.

Antibodies, Viral↗
PubMed1978

Induction of peripheral neuroblastomas in Syrian hamsters after injection as neonates with JC virus, a human polyoma virus.

Neuroblastomas developed in 10 of 31 Syrian hamsters inoculated intraocularly with JC virus, a human polyoma virus. The latent period was 6 to 11 months. Primary tumors occurred in the abdominal cavity, pelvis, mediastinum, and neck region. The origin of one tumor from the adrenal gland was demonstrated. Metastases were seen in the liver, bone marrow, and lymph nodes. Two neuroblastomas arising in this experiment were transplanted serially in weanling hamsters, and a tissue culture cell line was established from one of the transplanted tumors. T-antigen was detected in three of five primary tumors tested and in the transplanted tumors. Antibody against T-antigen was demonstrated in sera from five of six animals with neuroblastomas. Neuroblastomas also developed after combined s.c. and i.p. injection of JC virus.

Animals↗
PubMed1977

Adenine arabinoside in the treatment of progressive multifocal leukoencephalopathy: use of virus-containing cells in the urine to assess response to therapy.

Two patients with biopsy-proved progressive multifocal leukoencephalopathy (PML) were treated with near-maximal doses of adenine arabinoside (Ara-A), 18.6 and 20 mg per kilogram of body weight per day for 14 days. In both patients, clinical progression of the disease was correlated with an increase in the size of low-density lesions seen by computerized tomography. One of the patients was observed to excrete abnormal epithelial cells into the urine. These cells contained papovaviruslike particles, and JC virus was cultured from the urine sediment. The relative number of these abnormal cells declined during Ara-A treatment. Both patients died shortly after the conclusion of therapy without a change in the progression of the central nervous system disease. Systemic administration of Ara-A did not offer significant clinical benefit in the treatment of these 2 advanced cases of PML.

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