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1.
The gene encoding ClpC in Bacillus anthracis was amplified from the chromosome by polymerase chain reaction using degenerate oligonucleotide primers. These primers also amplified a second DNA fragment identified as a clpB homolog. Both genes were suggested to be functional. Contrary to Bacillus subtilis which possesses clpC but not clpB, many Bacillus species were found to harbor both clpC and clpB. We also found that Clostridium strains could possess clpB, clpC, or both. All the Gram-negative strains tested had clpB only.  相似文献   
2.
Plant Molecular Biology - In the above mentioned publication, part of Fig. 6B was distorted (extra diagonal lines appeared). The original article has been corrected and the proper version...  相似文献   
3.
Summary A membrane protein that is immunochemically similar to the red cell anion exchange protein, band 3, has been identified on the basolateral face of the outer medullary collecting duct (MCD) cells in rabbit kidney. In freshly prepared separated rabbit MCD cells, M.L. Zeidel, P. Silva and J.L. Seifter (J. Clin. Invest. 77:1682–1688, 1986) found that Cl/HCO 3 - exchange was inhibited by the stilbene anion exchange inhibitor, DIDS (4,4-diisothiocyano-2,2-disulfonic stilbene), with aK 1 similar to that for the red cell. We have measured the binding affinities of a fluorescent stilbene inhibitor, DBDS (4,4-dibenzamido-2,2-disulfonic stilbene), to MCD cells in 28.5 mM citrate and have characterized both a high-affinity site (K 1 s =93±24 mM) and a lower affinity site (K 2 s =430±260 nM), which are closely similar to values for the red cell of 110±51 nM for the high-affinity site and 980±200 nM for the lower affinity site (A.S. Verkman, J.A. Dix & A.K. Solomon,J. Gen. Physiol. 81:421–449, 1983). When Cl replaces citrate in the buffer, the two sites collapse into a single one withK 1 s =1500±400 nM, similar to the singleK 1 s =1200±200 nM in the red cell (J.A. Dix, A.S. Verkman & A.K. Solomon,J. Membrane Biol. 89:211–223, 1986). The kinetics of DBDS binding to MCD cells at 0.25 M–1 are characterized by a fast process, =0.14±0.03 sec, similar to =0.12±0.03 sec in the red cell. These similarities show that the physical chemical characteristics of stilbene inhibitor binding to MCD cell band 3 closely resemble those for red cell band 3, which suggests that the molecular structure is highly conserved.  相似文献   
4.
    
Extracellular matrix components play an important role in modulating cellular activity. To study such capacities of the matrix, fibroblasts are frequently cultured in a three-dimensional gel and contraction is assessed as a measure of cellular activity. Since a connective tissue contains several types of collagen, we investigated the effect of gels composed of collagen I alone or in combination with 10% collagen III and/or 5% collagen V on contraction by human periodontal ligament fibroblasts. Gels containing collagen V contracted much faster than those without this type of collagen. Blocking of the integrin beta1-subunit with an activity-blocking antibody delayed (gels with collagen V) or almost completely blocked (gels without collagen V) contraction. Use of an antibody directed against integrin alpha2beta1 resulted in delay of gel contraction for gels both with and without collagen V. Anti-integrin alpha v beta3 or RGD peptides partially blocked contraction of gels containing collagen V, but had no effect on gels consisting of collagen I alone. The beta1-containing integrins are involved in the basal contraction by fibroblasts that bind to collagens I and III. The enhanced contraction, stimulated by collagen V, appears to be mediated by integrin alpha v beta3. We conclude that collagen V may play an important modulating role in connective tissue contraction. Such a modulation may occur during the initial stages of wound healing and/or tissue regeneration.  相似文献   
5.
The reaction between low molecular weight S-nitrosothiols and hemoglobin is often used to synthesize S-nitrosohemoglobin, a form of hemoglobin suggested to be involved in the regulation of vascular oxygen delivery. However, this reaction has not been studied in detail, and several groups have reported a variable co-formation of oxidized methemoglobin (metHb) during synthesis. This study examines the mechanism of metHb formation and shows that nitrosylhemoglobin (HbNO) can also be formed. Generation of metHb and HbNO is largely dependent on the presence of protein thiol groups. We present evidence for a mechanism for the formation of metHb and HbNO involving the intermediacy of nitroxyl anion. Specifically, the reaction of nitroxyl with S-nitrosothiols to liberate nitric oxide and reduced thiol is proposed to be central to the reaction mechanism.  相似文献   
6.

Objective

We estimated HIV-free infant survival and mother-to-child HIV transmission (MTCT) rates in Zimbabwe, some of the first community-based estimates from a UNAIDS priority country.

Methods

In 2012 we surveyed mother-infant pairs residing in the catchment areas of 157 health facilities randomly selected from 5 of 10 provinces in Zimbabwe. Enrolled infants were born 9–18 months before the survey. We collected questionnaires, blood samples for HIV testing, and verbal autopsies for deceased mothers/infants. Estimates were assessed among i) all HIV-exposed infants, as part of an impact evaluation of Option A of the 2010 WHO guidelines (rolled out in Zimbabwe in 2011), and ii) the subgroup of infants unexposed to Option A. We compared province-level MTCT rates measured among women in the community with MTCT rates measured using program monitoring data from facilities serving those communities.

Findings

Among 8568 women with known HIV serostatus, 1107 (12.9%) were HIV-infected. Among all HIV-exposed infants, HIV-free infant survival was 90.9% (95% confidence interval (CI): 88.7–92.7) and MTCT was 8.8% (95% CI: 6.9–11.1). Sixty-six percent of HIV-exposed infants were still breastfeeding. Among the 762 infants born before Option A was implemented, 90.5% (95% CI: 88.1–92.5) were alive and HIV-uninfected at 9–18 months of age, and 9.1% (95%CI: 7.1–11.7) were HIV-infected. In four provinces, the community-based MTCT rate was higher than the facility-based MTCT rate. In Harare, the community and facility-based rates were 6.0% and 9.1%, respectively.

Conclusion

By 2012 Zimbabwe had made substantial progress towards the elimination of MTCT. Our HIV-free infant survival and MTCT estimates capture HIV transmissions during pregnancy, delivery and breastfeeding regardless of whether or not mothers accessed health services. These estimates also provide a baseline against which to measure the impact of Option A guidelines (and subsequently Option B+).  相似文献   
7.
8.

Background

Angiogenesis, the formation of new blood vessels from existing vasculature, plays an essential role in tumor growth, invasion, and metastasis. 16K hPRL, the antiangiogenic 16-kDa N-terminal fragment of human prolactin was shown to prevent tumor growth and metastasis by modifying tumor vessel morphology.

Methodology/Principal Findings

Here we investigated the effect of 16K hPRL on tumor vessel maturation and on the related signaling pathways. We show that 16K hPRL treatment leads, in a murine B16-F10 tumor model, to a dysfunctional tumor vasculature with reduced pericyte coverage, and disruption of the PDGF-B/PDGFR-B, Ang/Tie2, and Delta/Notch pathways. In an aortic ring assay, 16K hPRL impairs endothelial cell and pericyte outgrowth from the vascular ring. In addition, 16K hPRL prevents pericyte migration to endothelial cells. This event was independent of a direct inhibitory effect of 16K hPRL on pericyte viability, proliferation, or migration. In endothelial cell-pericyte cocultures, we found 16K hPRL to disturb Notch signaling.

Conclusions/Significance

Taken together, our data show that 16K hPRL impairs functional tumor neovascularization by inhibiting vessel maturation and for the first time that an endogenous antiangiogenic agent disturbs Notch signaling. These findings provide new insights into the mechanisms of 16K hPRL action and highlight its potential for use in anticancer therapy.  相似文献   
9.
    
Almost 500 million people worldwide suffer from Type I allergy, a genetically determined immunodisorder which is based on the production of IgE antibodies against per se harmless antigens (allergens). Due to their worldwide distribution and heavy pollen production, grasses represent a major allergen source for approximately 40% of allergic patients. We purified Phl p 4, a major timothy grass (Phleum pratense) pollen allergen with a molecular mass of 61.3 kDa and a pl of 9.6 to homogeneity. Circular dichroism spectroscopical analysis indicates that Phl p 4 contains a mixed alpha-helical/beta-pleated secondary structure and, unlike many other allergens, showed no reversible unfolding after thermal denaturation. We show that Phl p 4 is a major allergen which reacts with IgE antibodies of 75% of grass pollen allergic patients (n=150) and induces basophil histamine release as well as immediate type skin reactions in sensitized individuals. Phl p 4-specific IgE from three patients as well as two rabbit-anti Phl p 4 antisera cross-reacted with allergens present in pollen of trees, grasses, weeds as well as plant-derived food. Rabbit antibodies raised against Phl p 4 also inhibited the binding of allergic patients IgE to Phl p 4. Phl p 4 may thus be used for diagnosis and treatment of sensitized allergic patients.  相似文献   
10.
    
The emergence of strains of multidrug‐resistant Gram‐negative bacteria mandates a search for new types of antimicrobial agents. Alyteserin‐2a (ILGKLLSTAAGLLSNL.NH2) is a cationic, α‐helical peptide, first isolated from skin secretions of the midwife toad, Alytes obstetricans, which displays relatively weak antimicrobial and haemolytic activities. Increasing the cationicity of alyteserin‐2a while maintaining amphipathicity by the substitution Gly11→ Lys enhanced the potency against both Gram‐negative and Gram‐positive bacteria by between fourfold and 16‐fold but concomitantly increased cytotoxic activity against human erythrocytes by sixfold (mean concentration of peptide producing 50% cell death; LC50 = 24 µm ). Antimicrobial potency was increased further by the additional substitution Ser7→Lys, but the resulting analogue remained cytotoxic to erythrocytes (LC50 = 38 µm ). However, the peptide containing d ‐lysine at positions 7 and 11 showed high potency against a range of Gram‐negative bacteria, including multidrug‐resistant strains of Acinetobacter baumannii and Stenotrophomonas maltophilia (minimum inhibitory concentration = 8 µm ) but appreciably lower haemolytic activity (LC50 = 185 µm ) and cytotoxicity against A549 human alveolar basal epithelial cells (LC50 = 65 µm ). The analogue shows potential for treatment of nosocomial pulmonary infections caused by bacteria that have developed resistance to commonly used antibiotics. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.  相似文献   
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