Comparison of Ashdown's medium, Burkholderia cepacia medium, and Burkholderia pseudomallei selective agar for clinical isolation of Burkholderia pseudomallei

Ashdown's medium, Burkholderia pseudomallei selective agar (BPSA), and a commercial Burkholderia cepacia medium were compared for their abilities to grow B. pseudomallei from 155 clinical specimens that proved positive for this organism. The sensitivity of each was equivalent; the selectivity of BPSA was lower than that of Ashdown's or B. cepacia medium.     

Risk and protective factors for suicidal behavior in abused African American women

This study examined risk and protective factors that differentiate low-income, abused African American women (N = 200) who attempted suicide from those who had never made a suicide attempt. Results from multivariate analyses revealed that numerous and/or severe negative life events, a history of child maltreatment, high levels of psychological distress and depression, hopelessness about the future, and alcohol and drug problems were factors associated with attempter status. Protective factors associated with nonattempter status included hopefulness, self-efficacy, coping skills, social support, and effectiveness in obtaining material resources. Culturally competent intervention approaches for abused women should target increasing their protective factors and reducing their risk factors to decrease the likelihood that these women engage in suicidal behavior.     

Amplified region of chromosome band 11q13 in breast and squamous cell carcinomas encompasses three CpG islands telomeric of FGF3, including the expressed gene EMS1

DNA markers that map within the karyotypically defined band q13 on human chromosome 11 are amplified in a subset of mammary and squamous cell carcinomas. It is assumed that the amplified DNA includes a critical gene (or genes) whose overexpression provides a selective force in the development of the tumor. To help identify such genes, we have begun to construct a physical map of CpG islands in the region, making use of a squamous cell carcinoma cell line (UMSCC2) in which the 11q13 region is amplified 11-fold. We previously described the proximal end of this amplicon and the order of markers extending ～800 kb centromeric of the FGF3 locus (formerly INT2). We now report the use of chromosome jumping techniques to define additional CpG islands that lie distal to FGF3. These map within the amplified region in UMSCC2 cells and the most telomeric corresponds to the EMS1 gene. The data imply that the amplified DNA in UMSCC2 cells extends for over 1,500 kb and includes at least 7 potential genes. EMS1 and CCND1 (formerly PRAD1), the best candidates for the key gene on the 11q13 amplicon, are ≥800 kb apart. © 1993 Wiley-Liss, Inc.     

Homologues of insecticidal toxin complex genes in Yersinia enterocolitica biotype 1A and their contribution to virulence

Yersinia enterocolitica is an enteric pathogen that consists of six biotypes: 1A, 1B, 2, 3, 4, and 5. Strains of the latter five biotypes can carry a virulence plasmid, known as pYV, and several well-characterized chromosomally encoded virulence determinants. Y. enterocolitica strains of biotype 1A lack the virulence-associated markers of pYV-bearing strains and were once considered to be avirulent. There is growing epidemiological, clinical, and experimental evidence, however, to suggest that some biotype 1A strains are virulent and can cause gastrointestinal disease. To identify potential virulence genes of pathogenic strains of Y. enterocolitica biotype 1A, we used genomic subtractive hybridization to determine genetic differences between two biotype 1A strains: an environmental isolate, Y. enterocolitica IP2222, and a clinical isolate, Y. enterocolitica T83. Among the Y. enterocolitica T83-specific genes we identified were three, tcbA, tcaC, and tccC, that showed homology to the insecticidal toxin complex (TC) genes first discovered in Photorhabdus luminescens. The Y. enterocolitica T83 TC gene homologues were expressed by Y. enterocolitica T83 and were significantly more prevalent among clinical biotype 1A strains than other Yersinia isolates. Inactivation of the TC genes in Y. enterocolitica T83 resulted in mutants which were attenuated in the ability to colonize the gastrointestinal tracts of perorally infected mice. These results indicate that products of the TC gene complex contribute to the virulence of some strains of Y. enterocolitica biotype 1A, possibly by facilitating their persistence in vivo.     

Urban adolescents' perceptions of their neighborhoods: An examination of spatial dependence

Spatial dependence exists when the variation between observations is dependent on spatial location. In the present study, geostatistical methods were used to examine spatial dependence in adolescents' perceptions of their neighborhoods: whether adolescents living in close proximity perceived their neighborhoods more similarly than adolescents living further apart. Participants included 343 adolescents (53% male; 91% African American) enrolled in sixth grade, residing in Baltimore City, with geocoded home addresses. These addresses were used in combination with a measure of perceived neighborhood disorder and disadvantage to compute variogram plots, a geostatistical technique used to evaluate spatial dependence. Results indicated that perceptions of youth residing in close geographic proximity were more similar than perceptions of youth residing further apart. Adjusting for census‐level characteristics, but not individual and family characteristics, resulted in decreased variation among participants but did not eliminate the spatial dependence. Findings highlight the utility of geostatistical methods for social science research. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 277–293, 2004.     

Degree of Immunity Induced by Killed Vaccines to Experimental Salmonellosis in Mice

Killed vaccines, deoxycholate-extracted or heated, were shown to induce an effective degree of immunity which protected against death (100%), prevented extensive multiplication, and left the mice with low residual salmonella populations in spleen and liver after intravenous (iv) or intraperitoneal (ip) challenge with virulent Salmonella typhimurium. Protection was most effective against the ip challenge route and less effective against the iv route. A study of the kinetics of the population of bacteria in the spleens and livers of immunized animals showed that after ip challenge there was an initial reduction of 99% at 6 hr after challenge, maintenance of levels of less than 10(3) bacteria per organ, and a final population of 10(2) to 10(3) per organ at 21 days. With iv challenge, after an initial reduction of 90% at 6 hr, growth ensued to levels above 10(6) bacteria per organ until 8 days, followed by a steady decline yielding residual populations of 10(3) to 10(4) in some cases. Organ hypertrophy correlated with bacterial population. Morbidity was prevented (as measured by gain in body weight) by immunization against ip challenge but not against iv challenge. Killed vaccines protected by their ability to induce an immune state which reduced the initial challenge population, prevented extensive multiplication, yet allowed "cellular immunity" to develop due to response to the living challenge infection itself. The consequence was a low-level carrier state similar to that induced by recovery from sublethal virulent infection.     

Malignant schwannoma with melanocytic and neuroepithelial differentiation in an infant with congenital giant melanocytic nevus: A complex neurocristopathy

We describe an infant girl, born with a pigmented giant nevus, who developed a malignant schwannoma in the retroperitoneum at 16 months of age. At birth the nevus covered over 50% of her body and histologically was a compound nevus with extension into the deep dermis surrounding dermal appendages. The malignant schwannoma was biphasic with areas composed of spindle and round cells. Ultrastructurally, the majority of the tumor cells exhibited a Schwann cell phenotype, but neuroepithelial and melanocytic cells were identified as well. We believe that this constellation of findings represents a form of neurocristopathy. Neurocristopathy, as defined by Bolande (Hum Pathol 5:409–429, 1974), is a disease that results from aberrations in the migration, growth, or cytodifferentiation of neural crest tissues. These diseases may be simple (a singular pathologic process, usually localized) or complex (multiple neuroectodermal lesions). We report this case because the occurrence of retroperitoneal malignant schwannoma arising in a 16-month-old infant born with a pigmented giant nevus is unique, and may represent a previously undescribed form of a complex neurocristopathy.     

The complete sequence of the coding region of the ATM gene reveals similarity to cell cycle regulators in different species

Ataxia-telangiectasia (A-T) is an autosomal recessive disorderinvolving cerebellar degeneration, immunodeficiency, radiationsensitivity, and cancer predisposition. A-T heterozygotes aremoderately cancer prone. The A-T gene, designated ATM, was recentlyidentified in our laboratory by positional cloning, and a partialcDNA clone was found to encode a polypeptide with a PI-3 kinasedomain. We report here the molecular cloning of a cDNA contigspanning the complete open reading frame of the ATM gene. Thepredicted protein of 3056 amino acids shows significant sequencesimilarities to several large proteins in yeast, Drosophilaand mammals, all of which share the PI-3 kinase domain. Manyof these proteins are involved in the detection of DNA damageand the control of cell cycle progression. Mutations in theirgenes confer a variety of phenotypes with features similar tothose observed in human A-T cells. The complete sequence ofthe ATM gene product provides useful clues to the function ofthis protein, and furthers understanding of the pleiotropicnature of the A-T mutations.     

Volume and surface area estimates of astrocytes in the sensorimotor cortex of the cat

Electron micrographs of random sections through 133 astrocytes taken from the anterior and posterior sigmoid gyri of adult cats were used to estimate average astrocyte cell volume. Average soma volume was derived by two methods: (1) assuming that each approximated the shape of a prolate spheroid, a value of 2.2 ± 0.1 × 10^?13l. was calculated by substituting measurements of major (mean 10.4 ± 0.2 μm) and minor (mean 6.2 ± 0.1 μm) cell axes into the formula for volume; (2) applying Weibel's point-counting method of morphometry, a value of 1.9 ± 0.09 × 10^?13l. was obtained based on ratios of volume density and nuclear volume, calculated from measurements of nuclear axes. Because of the use of random sections through the cells sampled, the axial measurements on which both methods depend represent possible underestimations by as much as 21%; the resulting average value for soma volume might be as much as 3.2 × 10^?13l. Astrocyte somata from the deepest layer of the cortex had a significantly larger average volume than those from more superficial layers (P < 0.05). Average total cell volume (soma plus processes), estimated by calculating the volume of the tissue sample that was occupied by astrocytes and dividing that value by the number of astrocytes in the sample, amounted to 5.7 × 10^?13l. Point-counting morphometry revealed that 15.5% of the cortex consists of astrocytic cytoplasm. Average total cell surface area, estimated from intercepts of grid lines with cell membrane profiles of astrocytes within the sample, was 1.9 × 10^?5 cm²; average surface area of astrocyte somata, based on axial measurements, amounted to 2.5 × 10^?6 cm² or 13% of the surface area of the whole cell.Only 18 gap junctions were identified in the random sections through 133 astrocytes; these and other considerations bearing on the possible relationship of the data presented to electrical measurements in living astrocytes are discussed.