Iron uptake and transport by the carboxymycobactin-mycobactin siderophore machinery of Mycobacterium tuberculosis is dependent on the iron-regulated protein HupB

BioMetals - Iron-starved Mycobacterium tuberculosis utilises the carboxymycobactin-mycobactin siderophore machinery to acquire iron. These two siderophores have high affinity for ferric iron and...     

The U.N. convention on the law of the sea and military interests in the indian ocean

Abstract

The U.N. Law of the Sea Convention, ambiguous on military uses of the ocean space, weakens the legal basis for the maritime powers to pursue freely their military objectives in the oceans. Repudiation of the Convention by the United States will accelerate the creeping jurisdiction of the littoral states. The Convention enhances the security of the littoral states of the Indian Ocean, all of whom have only limited blue‐water capabilities and have sought to contain the military intrusions of the superpowers into the Indian Ocean.     

Calpain and Reactive Oxygen Species Targets Bax for Mitochondrial Permeabilisation and Caspase Activation in Zerumbone Induced Apoptosis

Fluorescent protein based signaling probes are emerging as valuable tools to study cell signaling because of their ability to provide spatio- temporal information in non invasive live cell mode. Previously, multiple fluorescent protein probes were employed to characterize key events of apoptosis in diverse experimental systems. We have employed a live cell image based approach to visualize the key events of apoptosis signaling induced by zerumbone, the active principle from ginger Zingiber zerumbet, in cancer cells that enabled us to analyze prominent apoptotic changes in a hierarchical manner with temporal resolution. Our studies substantiate that mitochondrial permeabilisation and cytochrome c dependent caspase activation dominate in zerumbone induced cell death. Bax activation, the essential and early event of cell death, is independently activated by reactive oxygen species as well as calpains. Zerumbone failed to induce apoptosis or mitochondrial permeabilisation in Bax knockout cells and over-expression of Bax enhanced cell death induced by zerumbone confirming the essential role of Bax for mitochondrial permeabilsation. Simultaneous inhibition of reactive oxygen species and calpain is required for preventing Bax activation and cell death. However, apoptosis induced by zerumbone was prevented in Bcl 2 and Bcl-XL over-expressing cells, whereas more protection was afforded by Bcl 2 specifically targeted to endoplasmic reticulum. Even though zerumbone treatment down-regulated survival proteins such as XIAP, Survivin and Akt, it failed to affect the pro-apoptotic proteins such as PUMA and BIM. Multiple normal diploid cell lines were employed to address cytotoxic activity of zerumbone and, in general, mammary epithelial cells, endothelial progenitor cells and smooth muscle cells were relatively resistant to zerumbone induced cell death with lesser ROS accumulation than cancer cells.     

Association of CYP3A5*3 polymorphism with development of acute leukemia

BACKGROUND:

CYP3A5 was observed to be an important genetic contributor to inter individual differences in CYP3A-dependent drug metabolism in acute leukemic patients. Loss of CYP3A5 expression was mainly conferred by a single nucleotide polymorphism at 6986A>G (CYP3A5*3). We investigated the association between CYP3A5*3 polymorphism and acute leukemia.

MATERIALS AND METHODS:

Two hundred and eighty nine acute leukemia cases comprising of 145 acute lymphocytic leukemia (ALL), 144 acute myeloid leukemia and 241 control samples were analyzed for CYP3A5*3 polymorphism using PCR-RFLP method. Statistical analysis was performed with SPSS version (15.0) to detect the association between CYP3A5*3 polymorphism and acute leukemia.

RESULTS:

The CYP3A5*3 polymorphism 3/3 genotype was significantly associated with acute leukemia development (χ²- 133.53; df-2, P 0.000). When the data was analyzed with respect to clinical variables, mean WBC, blast % and LDH levels were increased in both ALL and AML cases with 3/3 genotype. The epidemiological variables did not contribute to the genotype risk to develop either AML or ALL.

CONCLUSION:

The results suggest that the CYP3A5*3 polymorphism might confer the risk to develop ALL or AML emphasizing the significance of effective phase I detoxification in carcinogenesis. Association of the polymorphism with clinical variables indicate that the 3/3 genotype might also contribute to poorer survival of the patients.     

Structural requirements for antioxidative and anti-inflammatory properties of apolipoprotein A-I mimetic peptides

Recently, attention has been focused on pharmacological treatments that increase HDL cholesterol to prevent coronary artery disease. Despite three decades of extensive research of human apolipoprotein A-I (apoA-I), the major protein component of HDL, the molecular basis for its antiatherogenic and anti-inflammatory functions remain elusive. Another protein component of HDL, apoA-II, has structural features similar to those of apoA-I but does not possess atheroprotective properties. To understand the molecular basis for the effectiveness of apoA-I, we used model synthetic peptides. We designed analogs of the class A amphipathic helical motif in apoA-I that is responsible for solubilizing phospholipids. None of these analogs has sequence homology to apoA-I, but all are similar in their lipid-associating structural motifs. Although all of these peptide analogs interact with phospholipids to form peptide:lipid complexes, the biological properties of these analogs are different. Physical-chemical and NMR studies of these peptides have enabled the delineation of structural requirements for atheroprotective and anti-inflammatory properties in these peptides. It has been shown that peptides that interact strongly with lipid acyl chains do not have antiatherogenic and anti-inflammatory properties. In contrast, peptides that associate close to the lipid head group (and hence do not interact strongly with the lipid acyl chain) are antiatherogenic and anti-inflammatory. Understanding the structure and function of apoA-I and HDL through studies of the amphipathic helix motif may lead to peptide-based therapies for inhibiting atherosclerosis and other related inflammatory lipid disorders.     

Role of SufI (FtsP) in cell division of Escherichia coli: evidence for its involvement in stabilizing the assembly of the divisome

The function of SufI, a well-studied substrate of the TatABC translocase in Escherichia coli, is not known. It was earlier implicated in cell division, based on the finding that multiple copies of sufI suppressed the phenotypes of cells with mutations in ftsI (ftsI23), which encodes a divisomal transpeptidase. Recently, sufI was identified as both a multicopy suppressor gene and a synthetic lethal mutant of ftsEX, which codes for a division-specific putative ABC transporter. In this study, we show that sufI is essential for the viability of E. coli cells subjected to various forms of stress, including oxidative stress and DNA damage. The sufI mutant also exhibits sulA-independent filamentation, indicating a role in cell division. The phenotypes of the sufI mutant are suppressed by factors that stabilize FtsZ ring assembly, such as increased expression of cell division proteins FtsQAZ or FtsN or the presence of the gain-of-function ftsA* (FtsA R286W) mutation, suggesting that SufI is a divisomal protein required during stress conditions. In support of this, multicopy sufI suppressed the divisional defects of mutants carrying the ftsA12, ftsQ1, or ftsK44 allele but not those of mutants carrying ftsZ84. Most of the division-defective mutants, in particular those carrying a ΔftsEX or ftsI23 allele, exhibited sensitivity to oxidative stress or DNA damage, and this sensitivity was also abolished by multiple copies of SufI. All of these data suggest that SufI is a division component involved in protecting or stabilizing the divisomal assembly under conditions of stress. Since sufI fulfils the requirements to be designated an fts gene, we propose that it be renamed ftsP.     

Influence of intramolecular cross-links on the molecular, structural and functional properties of PEGylated haemoglobin

The influence of intramolecular cross-links on the molecular, structural and functional properties of PEGylated {PEG [poly(ethylene glycol)]-conjugated} haemoglobin has been investigated. The sites and the extent of PEGylation of haemoglobin by reductive alkylation are not influenced by the presence of an alphaalpha-fumaryl cross-link at Lys-99(alpha). The propylated hexaPEGylated cross-linked haemoglobin, (propyl-PEG5K)(6)-alphaalpha-Hb, exhibits a larger molecular radius and lower colloidal osmotic pressure than propylated hexaPEGylated non-cross-linked haemoglobin, (propyl-PEG5K)(6)-Hb. Perturbation of the haem microenvironment and the alpha1beta2 interface by PEGylation of haemoglobin is reduced by intramolecular cross-linking. Sedimentation velocity analysis established that PEGylation destabilizes the tetrameric structure of haemoglobin. (Propyl-PEG5K)(6)-Hb and (propyl-PEG5K)(6)-alphaalpha-Hb sediment as stable dimeric and tetrameric molecules, respectively. The betabeta-succinimidophenyl PEG-2000 cross-link at Cys-93(beta) outside the central cavity also influences the molecular properties of haemoglobin, comparable to that by the alphaalpha-fumaryl cross-link within the central cavity. However, the influence of the two cross-links on the oxygen affinity of PEGylated haemoglobin are very distinct, indicating that the high oxygen affinity of PEGylated haemoglobin is not a direct consequence of the dissociation of the haemoglobin tetramers into dimers. alphaalpha-Fumaryl cross-linking is preferred to modulate both oxygen affinity and molecular properties of PEGylated haemoglobin, and cross-linking outside the central cavity could only modulate molecular properties of PEGylated haemoglobin. It is suggested that PEGylation induces a hydrodynamic drag on haemoglobin and this plays a role in the microcirculatory properties of PEGylated haemoglobin.     

Diagnosis of T-cell lymphoma in body fluids: cytologic features and unusual flow cytometric findings

OBJECTIVE: To demonstrate the unique morphologic and phenotypic features observed in cases of T-cell lymphomas presenting as effusions. STUDY DESIGN: Cytologic slides and flow cytometric histograms of 8 cases of body fluids with T-cell lymphoma were retrospectively reviewed. Morphologic features, flow cytometric histograms and immunophenotypes of the cells were evaluated. RESULTS: Three of the 8 cases showed 1 or more of the following: intermediate-to-large cells with an increased nuclear-cytoplasmic ratio, finely granular or vacuolated cytoplasm and round or convoluted vesicular nuclei with a prominent single or multiple nucleoli. Flow cytometric studies of these 3 cases showed an abnormal scatter pattern in the myelomonocytic region of the histograms. Phenotypic analysis revealed variable expression of a T-cell phenotype. The remaining cases showed the conventional morphologic and flow cytometric features of a T-cell lymphoma. CONCLUSION: Morphologic alterations of neoplastic T-cells in body fluids can result in a variety of potentially incorrect diagnoses. The unusual flow cytometric histogram can serve as a useful clue for the diagnosis of T-cell lymphoma in body fluids but could be a potential pitfall for a false negative. Detailed cytologic evaluation combined with flow cytometric study can improve diagnostic accuracy.     

Free radical scavenging and radioprotective activity of dehydrozingerone against whole body gamma irradiation in Swiss albino mice

Dehydrozingerone (DZ) was explored for in vitro-in vivo antioxidant potential and in vivo radioprotective activity against whole body gamma irradiation in Swiss albino mice. DZ scavenged the ABTS (2, 2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) and DPPH (1, 1-dipehnyl-2-picrylhydrazyl) free radicals at room temp. DZ reduced Fe (III) to Fe (II) at pH 7.4 and scavenged the NADH/phenazine methosulfate generated superoxide radical in cell free system. DZ also scavenged the nitric oxide radical generated by sodium nitroprusside. To evaluate the radioprotective activity, mice were exposed to whole body gamma irradiation 30 min after the drug treatment at a dose rate of 1.66 Gy/min. Pretreatment with DZ 75, 100 and 125 mg/kg, i.p. reduced the radiation induced mortality and increased the mean survival times (MSTs). An i.p. dose of DZ 100 mg/kg was found the most effective dose in preventing radiation sickness and increasing the MST. Pretreatment DZ100 mg/kg maintained the spleen index (spleen weight/body weight x 100) and stimulates the endogenous spleen colony forming units (CFU). Pretreatment with DZ100 mg/kg maintained the villus height close to normal, prevents mucosal erosion and basement membrane damage in irradiated mice jejunum. However, no significant reductions in dead, inflammatory and mitotic cells were observed in DZ pretreated mice, but there was an increased in crypt cells proliferation and regeneration. Pretreatment with DZ100 mg/kg significantly elevated the endogenous antioxidant enzymes (GSH, GST and SOD) in mice at 2, 4 and 8 h post sham irradiation. Radiation induced fall in endogenous antioxidant enzymes was significantly prevented by DZ pretreatment. Pretreatment with DZ 75 and 100 mg/kg reduced the radiation induced micronucleated polychromatic erythrocytes (MPCE) and normochromatic erythrocytes (MNCE) in mice bone marrow. DZ also maintained the polychromatic erythrocytes (PCE) and normochromatic erythrocytes (NCE) ratio (P/N ratio) in irradiated mice. Dose modifying factor (DMF) was calculated by using the graded radiation dose (8.0, 9.0, 9.5 and 10 Gy). DZ 100 mg/kg elevated radiation LD(50) from 9.1 to 10.0 Gy, indicating the DMF of 1.09.     

Modulation of tight junction barrier function by outer membrane proteins of enteropathogenic Escherichia coli: role of F-actin and junctional adhesion molecule-1

Enteropathogenic Escherichia coli (EPEC) is a major cause of infantile diarrhea. In this work we investigated the effect of outer membrane proteins (OMP) of EPEC on barrier integrity and the role of actin, junctional adhesion molecule (JAM) and signaling pathways contributing to these changes. Barrier function was assessed by transepithelial electrical resistance (TER). OMP of wild type EPEC, eaeA and maltoporin mutants decreased TER levels of Caco-2 cells. The OMP of espB mutant was deficient in decreasing TER of Caco-2 cells. The proteinase K-digested wild type OMP and EAF mutant OMP did not cause any change in barrier function. Our previous studies have demonstrated that EPEC OMP induced changes in cadherin junctions of Caco-2 cells. Immunofluorescence revealed disruption in actin cytoskeleton by EPEC OMP. However, no change in expression of junctional adhesion molecule-1 was observed. NF-kappaB inhibitor slightly blocked the decrease in TER and protected against actin disruption while ERK1/2 inhibitor had no effect in blocking these changes. In conclusion, our data suggest that the OMP of EPEC alter intestinal barrier function by disrupting actin cytoskeleton and signaling pathways like NF-kappaB may have a role in regulating barrier changes.