Multisegment coloboma in a case of Marfan syndrome: another possible effect of increased TGFß signaling.

Colobomata are etiologically heterogeneous and may occur as an isolated defect or as a feature of a variety of single-gene disorders, chromosomal syndromes, or malformation syndromes. Although not classically associated with Marfan syndrome, colobomata have been described in several reports of Marfan syndrome, typically involving the lens and rarely involving other ocular structures. While colobomata of the lens have been described in Marfan syndrome, there are very few reports of coloboma involving other ocular structures. We report a newborn boy presenting with coloboma of the iris, lens, retina, and optic disk who was subsequently diagnosed with Marfan syndrome. Marfan syndrome is a disorder of increased TGFß signaling, and recent work in the mouse model suggests a role for TGFß signaling in eye development and coloboma formation, suggesting a causal association between Marfan syndrome and coloboma.

The Escherichia coli Cpx envelope stress response regulates genes of diverse function that impact antibiotic resistance and membrane integrity.

The Cpx envelope stress response mediates adaptation to stresses that cause envelope protein misfolding. Adaptation is partly conferred through increased expression of protein folding and degradation factors. The Cpx response also plays a conserved role in the regulation of virulence determinant expression and impacts antibiotic resistance. We sought to identify adaptive mechanisms that may be involved in these important functions by characterizing changes in the transcriptome of two different Escherichia coli strains when the Cpx response is induced. We show that, while there is considerable strain- and condition-specific variability in the Cpx response, the regulon is enriched for proteins and functions that are inner membrane associated under all conditions. Genes that were changed by Cpx pathway induction under all conditions were involved in a number of cellular functions and included several intergenic regions, suggesting that posttranscriptional regulation is important during Cpx-mediated adaptation. Some Cpx-regulated genes are centrally involved in energetics and play a role in antibiotic resistance. We show that a number of small, uncharacterized envelope proteins are Cpx regulated and at least two of these affect phenotypes associated with membrane integrity. Altogether, our work suggests new mechanisms of Cpx-mediated envelope stress adaptation and antibiotic resistance.

Incidence of post-dural puncture headache in research volunteers.

OBJECTIVE: To determine the frequency and risk factors of post-dural puncture headache (PDPH) in research volunteers. BACKGROUND: Despite increasing interest in measuring cerebrospinal fluid (CSF) biomarkers to investigate disease pathogenesis and diagnosis, previous case series have evaluated lumbar puncture (LP) safety only in clinical care. PDPH is a common complication after LP. METHODS: We determined the frequency of PDPH in neurologically unselected HIV seropositive and seronegative adults volunteering for research, as well as the variables associated with the development of PDPH. Variables studied were body mass index (BMI), HIV serostatus, volume of CSF removed, number of previous LPs, use of pre-medication, LP position, lumbar space, number of needle passes, whether or not aspiration was used, CSF white blood cell counts, CSF red blood cell counts, CD4 count, CD4 nadir, CSF HIV viral load, plasma HIV viral load, and race. RESULTS: Of 675 LPs performed over 1 year, headache developed in 38 (5.6%; 95% CI 4.2, 7.1). Most PDPH (92%) resolved spontaneously or with conservative medical management; 3 required epidural blood patch. Greater headache risk was associated with lower BMI (BMI ≤25 vs >25) (OR 3.3; CI 95% 1.5, 7.0; P = .001) and less prior LP experience (previous LPs ≤2 vs >2) (OR 2.1; CI 95% 1.1, 4.1; P = .03). PDPH was not significantly (P > .05) related to HIV serostatus, CSF volume, or gender. CONCLUSION: In this study, where tolerance to risk was low because LPs were done for research rather than clinical purposes and healthy controls were included, adverse effects were mild and self-limited.

Characterization of the induction and cellular role of the BaeSR two-component envelope stress response of Escherichia coli.

The bacterial cell envelope is the interface between a bacterium and its environment and is constantly exposed to environmental changes. The BaeSR two-component system regulates one of six envelope stress responses in Escherichia coli and is induced by spheroplasting, overexpression of the pilin subunit PapG, and exposure to indole. The known BaeR regulon is small, consisting of eight genes, mdtABCD-baeSR, acrD, and spy, two of which encode the BaeSR two-component system itself. In this study, we investigated the molecular nature of the BaeS-inducing cue and the cellular role of the BaeSR envelope stress response. We demonstrated that at least two flavonoids and sodium tungstate are novel inducers of the BaeSR response. Interestingly, flavonoids and sodium tungstate led to much stronger induction of the BaeSR response in an mdtA efflux pump mutant, while indole did not. These findings are consistent with the hypothesis that flavonoids and sodium tungstate are natural substrates of the MdtABC efflux pump. Indole has recently been implicated in cell-cell signaling and biofilm repression through a putative interaction with the LuxR homologue SdiA. Using genetic analyses, we found that induction of the BaeSR response by indole occurs via a pathway separate from the SdiA biofilm pathway. Further, we demonstrated that the BaeSR response does not influence biofilm formation, nor is it involved in indole-mediated inhibition of biofilm formation. We hypothesize that the main function of the Bae response is to upregulate efflux pump expression in response to specific envelope-damaging agents.

Prediction and functional analysis of the replication origin of the linear plasmid pSCL2 in Streptomyces clavuligerus.

pSCL2 (120 kb), one of the linear plasmids found in Streptomyces clavuligerus NRRL3585, was isolated and partially sequenced. Computational analysis of the central region of pSCL2 revealed the presence of two open reading frames that appear to encode proteins highly homologous to RepL1 and RepL2, replication proteins from pSLA2-L, the large linear plasmid in Streptomyces rochei. The S. clavuligerus open reading frames were designated repC1 and repC2, encoding the proteins RepC1 (150 amino acids) and RepC2 (102 amino acids), respectively. The RepC and RepL proteins have identical translation features and very similar predicted secondary and tertiary structures. Functional analysis confirmed that RepC1 is essential for replication initiation of pSCL2, whereas RepC2 is dispensable but may play a role in copy number control. The RepC and RepL proteins do not show similarity to any other bacterial plasmid replication proteins. Three regions of DNA sequence, Box 1 (1050-850 bp), Box 2 (723-606 bp), and Box 3 (224-168 bp), located upstream of repC1, were also shown to be essential or very important for replication of pSCL2.