A Burkholderia pseudomallei colony variant necessary for gastric colonization.

UNLABELLED: Diverse colony morphologies are a hallmark of Burkholderia pseudomallei recovered from infected patients. We observed that stresses that inhibit aerobic respiration shifted populations of B. pseudomallei from the canonical white colony morphotype toward two distinct, reversible, yet relatively stable yellow colony variants (YA and YB). As accumulating evidence supports the importance of B. pseudomallei enteric infection and gastric colonization, we tested the response of yellow variants to hypoxia, acidity, and stomach colonization. Yellow variants exhibited a competitive advantage under hypoxic and acidic conditions and alkalized culture media. The YB variant, although highly attenuated in acute virulence, was the only form capable of colonization and persistence in the murine stomach. The accumulation of extracellular DNA (eDNA) was a characteristic of YB as observed by 4',6-diamidino-2-phenylindole (DAPI) staining of gastric tissues, as well as in an in vitro stomach model where large amounts of eDNA were produced without cell lysis. Transposon mutagenesis identified a transcriptional regulator (BPSL1887, designated YelR) that when overexpressed produced the yellow phenotype. Deletion of yelR blocked a shift from white to the yellow forms. These data demonstrate that YB is a unique B. pseudomallei pathovariant controlled by YelR that is specifically adapted to the harsh gastric environment and necessary for persistent stomach colonization. IMPORTANCE: Seemingly uniform populations of bacteria often contain subpopulations that are genetically identical but display unique characteristics which offer advantages when the population is faced with infrequent but predictable stresses. The pathogen Burkholderia pseudomallei is capable of forming several reversible colony types, and it interconverted between one white type and two yellow types under certain environmental stresses. The two yellow forms exhibited distinct advantages in low-oxygen and acidic environments. One yellow colony variant was the only form capable of chronic stomach colonization. Areas of gastric infection were marked by bacteria encased in a DNA matrix, and the yellow forms were able to produce large amounts of extracellular DNA in vitro. We also identified the regulator in control of yellow colony variant formation. These findings demonstrate a role in infection for colony variation and provide a mechanism for chronic stomach colonization-a frequently overlooked niche in melioidosis.

HLA-DRB1*0102 is associated with TINU syndrome and bilateral, sudden-onset anterior uveitis but not with interstitial nephritis alone.

BACKGROUND: Tubulointerstitial nephritis and uveitis (TINU) syndrome is a rare form of uveitis. Previously, the authors had demonstrated a strong association of human leukocyte antigen (HLA) DRB1*0102 with TINU. Here, the authors performed HLA analysis on subjects with isolated bilateral sudden-onset uveitis (as in the TINU subtype) or with isolated tubulointerstitial nephritis (TIN). METHODS: Patients with sudden onset, anterior, bilateral uveitis not fulfilling a diagnosis of TINU were identified. Pathology reports were reviewed to identify subjects with biopsy-proven TIN. Molecular typing of the HLA-DRB1 gene was performed by the Luminex technology-based sequence-specific oligonucleotide (SSO) hybridisation method (One Lambda, Canoga Park, California). HLA-DRB1 allele frequencies were compared with normal published controls (http://www.ncbi.nlm.nih.gov/projects/gv/mhc/ihwg.cgi dbMHC Europe cohort) and the published TINU cohort (n=18). RESULTS: The authors included 28 subjects with uveitis and 14 with TIN. There was a significantly higher frequency of DRB1*0102 in the isolated uveitis cohort versus in normal controls (10.7% vs 0.6%, respectively, p<0.0001; RR 14.3 (6.9-29.8)). None of the nephritis patients showed this HLA subtype. Another association with HLA-DRB1*08 was seen in the isolated uveitis cohort with an allele frequency of 10.7% versus 2.7% in normal controls (p=0.0019; RR 4.0 (1.8-9.0)). In contrast, the HLA-DRB1*08 was not different from controls in the TINU cohort (allele frequency 2.8%, p=not significant). CONCLUSION: The incidence of HLA-DRB1*0102 is increased in sudden-onset bilateral anterior uveitis, as seen in patients with TINU. The same allele does not appear to occur in increased frequency in patients with isolated TIN. HLA DRB1*0102 might predispose to this subset of uveitis.

Gender and laterality affect recurrences of acute anterior uveitis.

AIM: Acute anterior uveitis (AAU) associated with HLA-B27 or axial spondyloarthritis (axial SpA) is primarily unilateral and recurrent. We tested the hypotheses that disease laterality and gender affected recurrences of AAU. METHODS: We studied 207 AAU subjects who were either HLA-B27 positive or had a verified history of axial SpA with documentation of the first uveitis episode. We recorded gender, laterality, duration, and time between episodes. RESULTS: Of 207 subjects, 126 (60.9%) had axial spondyloarthritis. Of the 179 with known HLA-B27 status, 174 (97.2%) were HLA-B27 positive. The initial episode of AAU occurred slightly more often in the right eye, 109 (52.6%), than in the left, 91 (44.0%) or bilaterally, 7 (3.4%), but the difference between right and left was not significant (p=0.23). Interestingly, 69.4% of subsequent episodes occurred in the same eye affected previously (95% CI 59.3%, 78.3%, p=0.0001). In subjects with recurrent AAU, the probability of being disease-free for one year was 38.9% (95% CI 29.1%, 52.0%) using Kaplan-Meier estimates. Univariate analyses showed that male gender (p=0.03) and AAU which recurred in the same eye (p=0.04) was associated with a shorter time interval between episodes. Multivariate analysis by the Cox proportional hazards model showed similar results. CONCLUSIONS: The initial episode of unilateral AAU associated with HLA-B27 or axial SpA randomly affects either eye. Subsequent episodes occur more often in the same eye previously affected. Male gender and history of unilateral AAU in the same eye are associated with a shortened time interval between relapses.

The significance of fertilization.

The fertilization of a human egg, often thought of as initiating the life of a person, is in reality but the beginning of a beginning for one or more individuals. While pronuclear fusion establishes a diploid genome, this is at first a structural entity without function. No significant RNA synthesis occurs between germinal vesicle breakdown and early cleavage, and in fact embryonic genes do not begin to find expression until about the 4- to 8- cell stage. Gene expression then progressively spreads throughout the genome, during prenatal development and beyond. The progressive nature is well shown in the early mouse embryo by the widening range of energy sources utilizable, by the rising levels of glycogen storage and by the increasing uptake of nucleic acids and protein precursors. While HCG-B RNA is transcribed in human embryos about 2 days after fertilization, it is not expressed until 16-cell stage is not linked to physical or functional integration, each cell being inherently capable of giving rise to an entire person (together with a complex of placental structures); alternatively, cells from separate embryos on being brought together can jointly lead to the establishment of a chimeric individual. Multiplicity can also originate later, the primitive streak stage being the normal time for monozygotic twinning. Only when that stage has passed does true individuality exist, for (excluding anomalies) just one person can now eventuate. The gene-transfer function of fertilization can be replaced or augmented by intranuclear or intra-blastocyst gene injection, or by the use of teratocarcinoma or embryo-stem cells.

Bisexuality and the problem of its social acceptance.

Professor Austin explores four main areas in this paper. First of all he outlines the physical development of sex differentiation in the embryo. He develops this by describing the clinical manifestations of abnormality which can appear at that stage. Professor Austin points out that there are relatively few people with abnormalities and that those who do show homosexual tendencies are not noticeably different from the norm in terms of their sexual equipment and hormone levels. It is much more likely that their psychological and social development has a greater influence in differentiating them sexually. The last section of the paper is a synopsis of society's reactions to homosexuality or bisexuality which term in Professor Austin's opinion is more accurate and descriptive of the condition.