Automated DNA fingerprinting analysis of Mycobacterium tuberculosis using fluorescent detection of PCR products.

DNA fingerprints of Mycobacterium tuberculosis are produced by restriction fragment length polymorphism analysis of the insertion element IS6110. We modified a PCR-based subtyping method, mixed-linker PCR with fluorescent-labeled IS6110-specific oligonucleotides, to demonstrate rapid, automated, and unattended electrophoretic analysis. Variation in band sizing (normally occurring with fragment mobility), an artifact of lane-to-lane and gel-to-gel differences, was controlled with an internal lane standard, resulting in accurate and precise DNA sizing. By using this method, fingerprint analysis can be performed using actual fragment length rather than estimated position analysis.     

Lithium ions and the release of transmitter at the frog neuromuscular junction.

1. Transmitter release has been examined at the frog neuromuscular junction when all or part of the Na of the Ringer is replaced by Li ions. 2. No immediate change occurs in either the mean quantal content of the end-plate potential or the miniature end-plate potential frequency on changing to Li Ringer but over the following hour both these quantities increase by more than two orders of magnitude. 3. During thefirst 30-40 min of an exposure to Li-Ringer the m.e.p.p. frequency rises exponentially with a time constant of 10 min, and the mean quantal content of the e.p.p. grows by addition of extra evoked quanta, the increment rising exponentially with a time constant the same as that of the m.e.p.p. frequency. 4. Following this initial period in Li-Ringer the m. e.p.p. frequency accelerates to a peak of several hundred quanta per second and then declines slowly over the next few hours. Just before the m.e.p.p.frequency peak the conduction velocity of the presynaptic action potential declines and shortly afterwards synaptic transmission fails as the action potential no longer conducts into the terminals. 5. The rise in the m.e.p.p. frequency during the first 30-40 min is independent of the [Ca-2+]o. At subsequent times before the peak external Cabecomes progressively more effective in accelerating the m.e.p.p. frequency and in the presence of 1mM-EGTA spontaneous release stabilizes at 60-80 quanta/sec. 6. The [Li-+]o strongly influences the rate of increases in both evoked and spontaneous release but not their extent; replacing only half the Na of the Ringer by Li increases the time constants of the increases to about 30 min. 7. Rises in the m.e.p.p. frequency can be irreversibly accelerated by tetanizing the nerve in a Li-Ringer in which the Ca has been chelated by EGTA. The extent of the increases in the m.e.p.p. frequency is dependent on the number of pulses in the tetanus and is little affected by the frequency of stimulation. Accumulation of Li ions inside the presynaptic terminals probably underlies the changes in spontaneous release. 8. When only 10 percent of the Na of the Ringer is replaced by Li-+ ions the magnitude of post-tetanic potentiation of the e.p.p. and of the post-tetanic rise in the m.e.p.p. frequency is increased. Under these conditions changes in facilitation of the e.p.p. are small. 9. Various mechanisms by which Li could alter transmitter release are discussed and it is suggested that intracellular Ca sequestering mechanisms of the presynaptic terminals are affected when an end-plate is exposed to Li-Ringer.     

Identification and Quantitation of Equine Serum and Secretory Immunoglobulin A

Immunoglobulin A (IgA) was demonstrated in equine serum and secretions. This immunoglobulin had a molecular weight extending from 150,000 to 700,000 and reacted with specific antihuman alpha-chain antiserum. Antigenic determinants specific for secretory IgA were demonstrated and found to be absent on serum IgA. Antigen binding activity was detected in IgA from tears. Purified IgA was antigenically distinct from equine IgG, IgM, IgG(T), and aggregating immunoglobulin. Quantitative studies demonstrated that IgA was the predominant immunoglobulin in tears and milk but not in colostrum. The electrophoretic mobility, size, presence of secretory component, and reaction with specific antihuman alpha-chain antiserum demonstrates that this immunoglobulin is the equine homologue of human IgA.     

Reverse dot blot assay (insertion site typing) for precise detection of sites of IS6110 insertion in the Mycobacterium tuberculosis genome

We have developed an amplification-based reverse dot blot assay for the detection of specific sites of insertion of the Mycobacterium tuberculosis insertion sequence IS6110. In this assay, a set of biotin-labeled amplicons representing the various copies of IS6110 and their flanking sequences is generated by linker-mediated PCR. The amplicons are then hybridized to immobilized oligonucleotide probes that are specific for known IS6110 insertion sites. The method was evaluated using an array of oligonucleotide probes corresponding to IS6110 insertion sites from M. tuberculosis strains CDC1551, Erdman, and H37Rv, and multidrug-resistant strain W. A set of 72 DNA samples from 60 M. tuberculosis clinical isolates was analyzed for the presence or absence of these insertion sites, and the assay was found to be highly reproducible. This method of identifying insertion sites has been named "insite" and can be used for the genotyping of M. tuberculosis complex strains based on IS6110 insertion site profiles.     

Immune responses of goats persistently infected with caprine arthritis-encephalitis virus.

Eight cesarean-derived goat kids were inoculated with caprine arthritis-encephalitis virus (CAEV), and proliferative responses of their peripheral blood mononuclear cells to mitogens and CAEV antigen were monitored for 9 months. Antibody specific for CAEV was measured by an enzyme-linked immunosorbent assay. Five cesarean-derived noninfected goats were tested simultaneously. Significant differences between the infected and control mononuclear cell proliferation reactions to CAEV began 14 days post-inoculation and continued in a fluctuant manner until 134 days post-inoculation. The magnitude of the proliferative reaction steadily increased in infected goats until the end of the experiment at 271 days post-inoculation. Responses to mitogens were not significantly different between infected and control goats. Virus-inoculated goats produced CAEV-specific antibody that reached a maximum level between 49 and 77 days post-inoculation and then declined to lower levels through 271 days post-inoculation. The virus-inoculated goats developed mild but characteristic clinical evidence of caprine arthritis-encephalitis, and CAEV was reisolated from four goats at 286 days post-inoculation. The five control goats developed neither an anti-CAEV immune response nor clinical disease, and CAEV could not be reisolated from them.     

The effects of reverse monocular deprivation in monkeys II. Electrophysiological and anatomical studies

Summary Monkeys had one eye closed at about 30 days of age for 14, 30, 60, or 90 days, then opened, and the fellow eye closed for another 120 days. The animals then had at least 10 months of binocular visual experience before extensive behavioral training and testing were carried out. In terminal experiments concluded more than 18 months later, microelectrode investigations of the striate cortex demonstrated that there was almost a complete absence of binocular neurons in all animals. The initially deprived eyes (IDEs) dominated the majority of cortical neurons, even when soma size measurements of lateral geniculate neurons indicated that the LGN cells driven by the IDE had not regained their normal size. The monkeys which had significant interocular differences in spatial vision also exhibited abnormalities in the distribution of the metabolic enzyme, cytochrome oxidase (CO), within the striate cortex. These results demonstrate that many of the severe alterations in cortical physiology and eye dominance produced by early monocular form deprivation can be reversed, with recovery of normal cortical function, via the reverse-deprivation procedure.Supported by National Eye Institute grants R01 EY01120, R01 EY03611, R01 EY01139, and EY02520     

Epstein-Barr virus gene expression and epithelial cell differentiation in oral hairy leukoplakia.

Hairy leukoplakia (HL) is an Epstein-Barr (EB) virus related lesion of oral mucosa that is principally associated with human immunodeficiency virus-induced immunosuppression. To understand the nature of EB virus involvement in these lesions, this study compares the distribution of EB virus DNA and EB viral gene products with the pattern of keratinocyte differentiation in 12 lateral tongue biopsies of HL. Evidence of replicating EB viral infection and abundant virus production was demonstrated in the superficial epithelium of most (92%) samples by means of in situ hybridization and immunocytochemical techniques. Epstein-Barr virus latent membrane protein also was identified in 45% of samples, suggesting that this viral gene product, which is usually associated with EB virus latent infection, may be transiently expressed during viral replication in HL epithelium. The absence of detectable EB virus involvement in basal keratinocytes, however, fails to support the theory that latent infection occurs in basal epithelium. From this study, EB viral gene expression in HL appears to be linked with epithelial maturation. Conversely, the normal patterns of keratinocyte differentiation in these lesions do not appear to be appreciably altered by association with EB virus.     

Leukocyte cytotoxicity in a persistent virus infection: presence of direct cytotoxicity but absence of antibody-dependent cellular cytotoxicity in horses infected with equine infectious anemia virus.

Antibody-dependent cellular cytotoxicity and direct cytotoxicity assays were performed with equine infectious anemia virus-infected target cells, equine leukocytes, and equine anti-equine infectious anemia virus antibody to determine whether these mechanisms play a role in controlling viral replication in equine infectious anemia. Direct cytotoxicity was observed by using peripheral blood mononuclear cells from 7 of 10 infected horses. Antibody-dependent cellular cytotoxicity was not observed. The antibody-dependent cellular cytotoxicity reaction in horses was then studied by using sheep erythrocytes and trinitrophenylated sheep erythrocytes as target cells. Lysis of these target cells was mediated by neutrophils, monocytes, and lymphocytes. The reaction was activated by antibody of the immunoglobulin G class but not by immunoglobulin G(T). Furthermore, immunoglobulin G(T) efficiently inhibited immunoglobulin G in this function.     

Translocation (X;20) involving the inactive X chromosome in a patient with myeloproliferative disorder

We report a patient with an unclassifiable myeloproliferative disorder and the rare t(X;20)(q13;q13.3) as the sole cytogenetic abnormality. The breakpoint on Xq is consistent with other reports of translocations involving the X chromosome with breakpoints that cluster to Xq13 and association with myeloid disorders. Late replication studies demonstrated the inactive X chromosome was involved in this translocation. The critical event in patients with myeloproliferative disease and deletion of 20q appears to be the loss of tumor suppressor genes. This may also be the mechanism in this patient with a potential cryptic deletion associated with the translocation. Alternatively, spreading of X inactivation into the derivative chromosome 20 provides a second mechanism for the loss of function of tumor suppressor genes on 20q. The finding in this patient of t(X;20) together with three others reported in the literature indicates that this may represent a primary non-random abnormality associated with myeloid malignancy, which may take on clinical significance with the accumulation of more cases.