Relative carriage rates of nuclear dehydrogenating clostridia in two populations of different colorectal cancer risk

Carriage of nuclear dehydrogenating clostridia has been associated with colon cancer and implicated in its aetiology. This study has compared the carriage of these organisms in a British population at high risk for the development of colon cancer with a low risk Nigerian population. Clostridia were found in all of the stools from both populations. Nuclear dehydrogenating clostridia were only found in the stools of the British subjects (32%). These results support the suggestion that the carriage rate of nuclear dehydrogenating clostridia in a population is related to the risk of colon cancer.     

Neuropeptide Y-immunoreactive cells in the caudal medulla project to the median preoptic nucleus

The region surrounding the anteroventral third ventricle, particularly the median preoptic nucleus, has been implicated in the control of fluid balance and blood pressure. Previous studies indicate that catecholaminergic inputs from the caudal medulla are important in these controls. In this study we report that neuropeptide Y-immunoreactive cells in the caudal medulla project to the median preoptic nucleus in the basal forebrain. Notably these cells are found in the caudal ventral lateral medulla and the nucleus of the solitary tract. Since catecholaminergic projections to the median preoptic nucleus also arise from these regions the possibility of interactions between NPY and catecholamines exists, particularly in the control of fluid balance and blood pressure.     

Inhibition of contact sensitivity reactions to DNFB by topical cyclosporin application in the guinea-pig.

Contact sensitivity skin reactions to dinitrofluorobenzene (DNFB) were inhibited by twice daily topical application of cyclosporin (CsA, 2%) in normal guinea-pigs and in those with enhanced contact sensitivity reactions following pre-treatment with cyclophosphamide. In contrast to oral administration of CsA (25 mg/kg) for 4 days, topical application of the drug over the same period did not result in systemic absorption (as measured by radioimmunoassay) or in any evidence of nephrotoxicity.     

Androgen receptor YAC transgenic mice carrying CAG 45 alleles show trinucleotide repeat instability

X-linked spinal and bulbar muscular atrophy (SBMA) is caused by a CAG repeat expansion in the first exon of the androgen receptor (AR) gene. Disease-associated alleles (37-66 CAGs) change in length when transmitted from parents to offspring, with a significantly greater tendency to shift size when inherited paternally. As transgenic mice carrying human AR cDNAs with 45 and 66 CAG repeats do not display repeat instability, we attempted to model trinucleotide repeat instability by generating transgenic mice with yeast artificial chromosomes (YACs) carrying AR CAG repeat expansions in their genomic context. Studies of independent lines of AR YAC transgenic mice with CAG 45 alleles reveal intergenerational instability at an overall rate of approximately 10%. We also find that the 45 CAG repeat tracts are significantly more unstable with maternal transmission and as the transmitting mother ages. Of all the CAG/CTG repeat transgenic mice produced to date the AR YAC CAG 45 mice are unstable with the smallest trinucleotide repeat mutations, suggesting that the length threshold for repeat instability in the mouse may be lowered by including the appropriate flanking human DNA sequences. By sequence-tagged site content analysis and long range mapping we determined that one unstable transgenic line has integrated an approximately 70 kb segment of the AR locus due to fragmentation of the AR YAC. Identification of the cis - acting elements that permit CAG tract instability and the trans -acting factors that modulate repeat instability in the AR YAC CAG 45 mice may provide insights into the molecular basis of trinucleotide repeat instability in humans.      

Phylogenetic Analysis of the DNA Polymerase Gene of a Novel Alphaherpesvirus Isolated from an Indian <Emphasis Type="Italic">Gyps</Emphasis> Vulture

The DNA polymerase gene of a novel herpesvirus, vulture herpesvirus (VHV), isolated from an Indian Gyps vulture was completely sequenced using primer walking and transposon insertion strategies. DNA sequencing analysis revealed a single open reading frame (ORF) of 3660 nucleotides (53% G-C content) able to encode 1219 amino acids. Identification was based on a nucleotide sequence identity of approximately 50% to other herpesvirus sequences found in Genbank. Nine motifs were identified that are conserved amongst all known herpesviruses and are found within the 3–5 exonuclease and DNA binding functional domains of the DNA polymerase enzyme. Phylogenetic analysis using Clustal W with neighbour-joining revealed VHV to group within the subfamily Alphaherpesvirinae, more closely related to the avian herpesviruses than to those of other species. Partial sequence data also revealed VHV to contain other genes fundamental to the structure and replication of all herpesvirus genomes. A Real Time PCR Taqman assay specific for the VHV DNA polymerase gene was designed to detect the presence of VHV genomic material in post mortem tissue samples from diseased birds. Positive tissues included the spleen, rectum, thymus, kidney and brain. A herpesvirus specific to vultures may pose a threat to the management of captive breeding programs being established to assist the survival of wild populations of Gyps vultures.     

The association of access to medical care with regular source of care and sociodemographic characteristics in patients with HIV and tuberculosis

PURPOSE: To examine satisfaction with access to health care in two populations, one with HIV and one with TB, and examine the effect of having a regular doctor and sociodemographic characteristics. DESIGN: Cross-Sectional survey. PATIENTS: A sample of HIV inpatients hospitalized at seven Los Angeles sites (N = 217) and TB outpatients chosen randomly from the Los Angeles County TB Registry Census (N = 313). ANALYSIS: We performed bivariate and multivariate regression analyses of satisfaction with access to care on gender, race/ethnicity, age, education, income, insurance, and having a regular doctor. MAIN OUTCOME MEASURES: A six-item scale of satisfaction with access to care (range 0-100; Cronbach's alpha 0.87). RESULTS: The mean satisfaction with access score for the HIV sample was significantly lower than the TB sample (53.5 vs. 61.2, p<0.001). The HIV sample multivariate analysis (including all the variables) showed that increasing age (p<0.021 and having a regular doctor (p<0.002) were associated with better access, and that low income (p<0.005) was associated with poor access. In the TB sample analysis, only increasing age was associated with better satisfaction with access to care (p< 0.01). CONCLUSION: HIV patients receiving care in the private sector reported less satisfaction with access to care compared to TB patients receiving care in the public health sector. The traditional factors of socio-economic status and having a regular doctor were associated with satisfaction with access-to-care in the HIV sample but not the TB sample. Our findings suggest that certain characteristics of the TB public health programs may explain these differences and suggests that, perhaps, the existence of a similar public health program for vulnerable low-income populations with HIV would improve their satisfaction with access, as well.     

bcl-2 rearrangement in Hodgkin's disease. Results of polymerase chain reaction, flow cytometry, and sequencing on formalin-fixed, paraffin-embedded tissue.

We examined 81 cases of Hodgkin's disease for evidence of the t(14;18) translocation, using the polymerase chain reaction assay on lysates of formalin-fixed, paraffin-embedded tissue. Seven of 74 amplifiable cases (9%) were positive for the translocation, which involves the bcl-2 oncogene and the immunoglobulin heavy chain gene. Two of these cases were sequenced and the breakpoints had the same pattern found in follicular lymphoma. The nuclei from one of the cases were sorted into large and small subpopulations. The t(14;18) signal was more intense in the large nucleus subpopulation, which contained a greater proportion of Reed-Sternberg-like nuclei. These results are consistent with the hypothesis that Reed-Sternberg cells carry the translocation, but they do not exclude the possibility that the translocation is found in cells representing the reactive component of Hodgkin's disease. The results also demonstrate that routinely processed material is suitable for polymerase chain reaction-based analysis of translocations, although the sensitivity is reduced 10- to 100-fold, compared with fresh tissue.     

Cytogenetic characterization of the transgenic Big Blue(R) Rat2 and Big Blue(R) mouse embryonic fibroblast cell lines

The transgenic Big Blue^® Rat2 and Big Blue^® mouse embryonicfibroblast cell lines have been used to complement the transgenicBig Blue® rat and mouse in vivo mutagenesis assays. However,limited information is available regarding the karyology ofthese cell lines. Therefore, we have characterized the ploidy,mitotic index, spontaneous frequencies of chromosome and chromatidaberrations and rate of micronucleus (MN) formation in bothcell lines. We have also characterized the frequency of sisterchromatid exchange (SCE) in transgenic Big Blue^® mouse cells.Big Blue^® Rat2 cells are hyperploid and have extremely highbaseline frequencies of cytogenetic damage. In addition, BigBlue^® Rat2 cells are BrdU-resistant, therefore, SCE frequenciescannot be assessed in these cells. We conclude that Big Blue^®Rat2 cells are not useful for routine cytogenetic toxicologystudies. The transgenic Big Blue^® mouse cell line is polyploidand consistently yields a low mitotic index (1%) in untreatedcells. These mouse cells also exhibited moderately high baselinefrequencies of chromosome and chromatid aberrations, however,baseline frequencies of SCE and of MN were not elevated. TransgenicBig Blue^® mouse embryonic fibroblasts were further studiedfor MN induction following treatment with Nethyl-N-nitrosourea(ENU) for 0.5 h at concentrations of 0.425,0.85 and 1.7 mM.Concentration-dependent increases in MN were observed in thesecells. Thus, while an ENU-induced cytogenetic response usingtransgenic Big Blue^® mouse cells demonstrates that thiscellular model could be used to cytogenetically complement themutagenesis assays, the low mitotic index and the high spontaneousfrequency of chromosome damage confounds its use for routinegenetic toxicology studies. ³To whom correspondence should be addressed. Tel: +1 919 541 3275; Fax: +1 919 541 1460; Email: tindall{at}niehs.nih.gov     

The effect of 2-amino-4-phosphonobutyrate (APB) on acetylcholine release from the rabbit retina: evidence for on-channel input to cholinergic amacrine cells

The light-evoked release of acetylcholine (ACh) from the rabbit retina was taken as a measure of cholinergic amacrine cell activity. The glutamate analogue DL-(+/-)-2-amino-4-phosphonobutyric acid (APB) prevented the light-evoked release of ACh and also selectively abolished the ON-responses of ganglion cells and the ERG b-wave. It is concluded that the input to cholinergic amacrine cells involves mainly the depolarizing bipolar cells, which subserve ON-channels. L-(+)-stereoisomer of APB was 15 times more potent than the D-(-)-isomer in suppressing ACh release and the b-wave, suggesting that the mechanism of action of APB does not involve antagonism of excitatory amino acids.     

Functional defects in the fanconi anemia pathway in pancreatic cancer cells

Biallelic BRCA2-mutations can cause Fanconi anemia and are found in approximately 7% of pancreatic cancers. Recently, several sequence changes in FANCC and FANCG were reported in pancreatic cancer. Functional defects in the Fanconi pathway can result in a marked hypersensitivity to interstrand crosslinking agents, such as mitomycin C. The functional implications of mutations in the Fanconi pathway in cancer have not been fully studied yet; these studies are needed to pave the way for clinical trials of treatment with crosslinking agents of Fanconi-defective cancers. The competence of the proximal Fanconi pathway was screened in 21 pancreatic cancer cell lines by an assay of Fancd2 monoubiquitination using a Fancd2 immunoblot. The pancreatic cancer cell lines Hs766T and PL11 were defective in Fancd2 monoubiquitination. In PL11, this defect led to the identification of a large homozygous deletion in FANCC, the first cancer cell line found to be FANCC-null. The Fanconi-defective cell lines Hs766T, PL11, and CAPAN1 were hypersensitive to the crosslinking agent mitomycin C and some to cis-platin, as measured by cell survival assays and G(2)/M cell-cycle arrest. These results support the practical exploration of crosslinking agents for non-Fanconi anemia patients that have tumors defective in the Fanconi pathway.