Comparison of Coccidioides immitis arthrospore, mycelium, and spherule cell walls, and influence of growth medium on mycelial cell wall composition.

Comparative lipid content, cell wall yield, neutral monosaccharide, glucosamine, and protein (amino acid) contents of arthrospores, mycelia, and spherules of Coccidioides immitis Cash were studied. Cellular lipid contents were found in the decreasing order: spherules, arthrospores, mycelia. Lipid content of mycelia did not reach the level of arthrospores or spherules even when mycelia were grown on relatively rich media. Cell wall yields of spherules were lower than for mycelia when grown on comparable media. Cell walls of arthrospores, mycelia, spherules, and spherule culture filtrate all contained 3-O-methylmannose, mannose, and glucose, but in varying amounts. Cell wall yield and cell wall glucose content increased in mycelia grown in increasingly rich media, whereas mannose content either decreased or remained constant.     

Association analysis of the monoamine oxidase A and B genes with attention deficit hyperactivity disorder (ADHD) in an Irish sample: preferential transmission of the MAO-A 941G allele to affected children.

Pharmacological and genetic studies suggest the importance of the dopaminergic, serotonergic, and noradrenergic systems in the pathogenesis of attention deficit hyperactivity disorder (ADHD). Monoamine oxidases A and B (MAO-A and MAO-B) degrade biogenic amines such as dopamine and serotonin and thereby control the levels of these neurotransmitters in the central nervous system. We examined four polymorphisms in the MAO-A gene (30 bp promoter VNTR, CA microsatellite in intron 2, 941G/T SNP in exon 8, and A/G SNP in intron 12) as well as two markers in the MAO-B gene (CA microsatellite in intron 2 and T/C SNP in intron 13) for association with ADHD in an Irish sample of 179 nuclear families. TDT analysis of the examined MAO-A markers revealed a significant association of the more active MAO-A 941G allele with the disorder (chi2 = 5.1, P = 0.03, OR = 1.7). In addition, haplotype analysis revealed a significantly increased transmission of a haplotype consisting of the shorter allele of the promoter VNTR (allele 1), the 6-repeat allele of the CA microsatellite and the G-allele of the 941G/T SNP (famhap global statistic 34.54, P = 0.01) to ADHD cases. No significant distortion in the number of transmitted alleles was observed between the two examined MAO-B polymorphisms and ADHD. These findings suggest the importance of the 941G/T MAO-A polymorphism in the development of ADHD at least in the Irish population.     

Premature senescence involving p53 and p16 is activated in response to constitutive MEK/MAPK mitogenic signaling

Oncogenic Ras transforms immortal rodent cells to a tumorigenic state, in part, by constitutively transmitting mitogenic signals through the mitogen-activated protein kinase (MAPK) cascade. In primary cells, Ras is initially mitogenic but eventually induces premature senescence involving the p53 and p16^INK4a tumor suppressors. Constitutive activation of MEK (a component of the MAPK cascade) induces both p53 and p16, and is required for Ras-induced senescence of normal human fibroblasts. Furthermore, activated MEK permanently arrests primary murine fibroblasts but forces uncontrolled mitogenesis and transformation in cells lacking either p53 or INK4a. The precisely opposite response of normal and immortalized cells to constitutive activation of the MAPK cascade implies that premature senescence acts as a fail-safe mechanism to limit the transforming potential of excessive Ras mitogenic signaling. Consequently, constitutive MAPK signaling activates p53 and p16 as tumor suppressors.     

Application of an intragenic genomic probe to genetic counselling for haemophilia B in the west of Scotland.

Total ascertainment revealed 28 families with haemophilia B in the west of Scotland (prevalence 1/26 870 males). In 12 of these families more than one person was affected and 26 living obligate carriers were identified and tested. Of these, 42% were heterozygous for a DNA polymorphism recognised by a factor IX genomic probe. No recombination was observed in 11 phase known and four phase unknown informative meioses. Definitive genetic counselling was possible for 14 of 42 females at risk, 11 could not be traced, in 10 the probe was not informative, and in seven paternal absence prevented interpretation. Linkage disequilibrium was apparent for this restriction fragment length polymorphism and haemophilia B in the west of Scotland.     

Cost-effective analysis of candidate genes using htSNPs: a staged approach

We have previously shown that the selection of haplotype tag single nucleotide polymorphisms (htSNPs) and their statistical analysis in a multi-locus transmission/disequilibrium test (TDT) results in a more cost-effective genotyping strategy in disease association studies of genes by minimising redundancy due to linkage disequilibrium between SNPs. Further savings can be achieved by the use of a two-stage genotyping strategy. This approach is illustrated here in conjunction with the multi-locus TDT in determining whether common alleles of the immune regulatory genes RANK and its ligand TRANCE (RANKL) are associated with type 1 diabetes (T1D). A saving of approximately 75% of potential genotyping reactions could be made with minimal loss of power. There was little evidence from our analysis for association between the TRANCE and RANK genes and T1D in the populations tested.     

Cell-matrix interactions during development and apoptosis of the mouse mammary gland in vivo.

Epithelial cell survival is dependent on extracellular signals provided by both soluble factors and by adhesion. In the mammary gland, extensive apoptosis of epithelial cells occurs rapidly when lactation ceases, but the mechanism of apoptosis induction is not known. In tissue culture, mammary epithelial cells require laminin as a survival ligand and specific beta1 integrins are necessary to suppress apoptosis. To explore the possibility that dynamic changes in cell-matrix interactions contribute to the onset of apoptosis during mammary involution in vivo, a detailed immunohistochemical analysis of the expression of integrin subunits and their extracellular matrix ligands during mouse mammary gland development has been performed. The kinetics of apoptosis were determined by using tissue samples obtained from virgin, pregnant, lactating, and involuting gland. The maximal elevation of apoptosis occurred within 24 hr of weaning as determined by histologic analysis and caspase-3 staining. A wide variety of laminin subunits, together with nidogen-1 and -2, and perlecan were identified within the basement membrane region of epithelial ducts, lobules, and alveoli in both human and mouse mammary gland. However, no change in the distribution of any of the basement membrane proteins or their cognate integrin receptors was observed during the transition from lactation to apoptosis. Instead, we discovered that altered ligand-binding conformation of the beta1 integrin to a nonbinding state coincided with the immediate onset of mammary apoptosis. This finding may provide a novel dynamic mechanism for inhibiting the transduction of extracellular matrix survival signals, thereby contributing to the onset of apoptosis in a developmental context in vivo.     

Treg-Cell Control of a CXCL5-IL-17 Inflammatory Axis Promotes Hair-Follicle-Stem-Cell Differentiation During Skin-Barrier Repair

1. Download high-res image (91KB)
2. Download full-size image

     

High rates of clustering of strains causing tuberculosis in Harare, Zimbabwe: a molecular epidemiological study

We examined the pattern of tuberculosis (TB) transmission (i.e., reactivation versus recent transmission) and the impact of human immunodeficiency virus (HIV) infection in Harare, Zimbabwe. Consecutive adult smear-positive pulmonary TB patients presenting to an urban hospital in Harare were enrolled. A detailed epidemiological questionnaire was completed, and tests for HIV type 1 and CD4 cell counts were performed for each patient. Molecular fingerprinting of the genomic DNA recovered from cultures of sputum was performed by two molecular typing methods: spacer oligonucleotide typing (spoligotyping) and analysis of variable number of tandem DNA repeats (VNTRs). A cluster was defined as isolates from two or more patients that shared the same spoligotype pattern or the same VNTR pattern, or both. DNA suitable for typing was recovered from 224 patients. The prevalence of HIV infection was 79%. Of 187 patient isolates (78.6%) typed by both spoligotyping and analysis of VNTRs, 147 were identified as part of a cluster by both methods. By spoligotyping alone, 84.1% of patient isolates were grouped into 20 clusters. The cluster size was generally <8 patient isolates, although three large clusters comprised 68, 25, and 23 patient isolates. A total of 89.4% of the patient isolates grouped into 12 clusters defined by analysis of VNTRs, with 2 large clusters consisting of 127 and 13 patient isolates, respectively. Thirty-six percent of patient isolates with a shared spoligotype and 17% with a shared VNTR pattern were geographically linked within Harare, but they were not linked on the basis of the patient's home district. In a multivariate analysis, there were no independent predictors of clustering, including HIV infection status. Comparison with the International Spoligotype database (Pasteur Institute, Pointe a Pitre, Guadeloupe) demonstrated that our three largest spoligotype clusters are well recognized and ubiquitous in Africa. In this epidemiologically well characterized urban population with a high prevalence of HIV infection, we identified a very high level of strain clustering, indicating substantial ongoing recent TB transmission. Geographic linkage could be detected in a proportion of these clusters. A small group of actively circulating strains accounted for most of the cases of TB transmission.     

Levonorgestrel intrauterine system (LNG-IUS) with conjugated oral equine estrogen: a successful regimen for HRT in perimenopausal women

BACKGROUND: This study was designed to assess the long-term efficacy (5 years) of the levonorgestrel-releasing intrauterine system (LNG-IUS) in protecting the endometrium from hyperplasia during estrogen replacement therapy in perimenopausal women. METHODS: Prospective, open, outpatient clinical trial in London and Oxford. Eighty-two women received oral conjugated equine estrogen 1.25 mg daily and LNG-IUS releasing 20 mug levonorgestrel per 24 h. Endometrial biopsy and histological assessment were performed annually. Endometrial thickness was measured by vaginal ultrasonography. RESULTS: Non-proliferative endometrium was present at the end of cycles 12, 24, 36, 48 and 60 in 98.6, 98.6, 95.5, 96.8 and 95.2% of the participants respectively. No endometrial hyperplasias were confirmed throughout a period of 60 cycles. The proportion of amenorrhoeic women increased from 54.4% at 12 cycles to 92.7% at the end of the study. The continuation rate per 100 women at 60 cycles was 79.84 (95% CI 71.0-88.6). CONCLUSIONS: The LNG-IUS with estrogen supplementation in perimenopausal women suppresses endometrial proliferation resulting in amenorrhoea and relieves vasomotor symptoms. The treatment regimen is well tolerated and provides an alternative strategy for perimenopausal women with the likelihood of increasing compliance.