Structure and absolute configuration of the sesquiterpenoid emmotins

The trunk wood of Emmotum nitens (Icacinaceae) contains the aromatic sesquiterpenes (2R,3S)-2-hydroxy-3-(2′-hydroxyisopropyl)-5,8-dimethyl-1-oxo-1,2,3,4-tetrahydronaphthalene (emotin-F), 2-hydroxy-3-(2′-hydroxyisopropyl)-5,8-dimethylnaphthalene (emmotin-G) and 3-(2′-hydroxyisopropyl)-5,8-dimethyl-1,2-naphtho-quinone (emmotin-H). The identity of the carbon skeletons of these emmotins was proved by conversion of all three into an identical quinoxaline derivative. The nature of this skeleton and the absolute configuration of emmotin-F, as well as of the previously described emmotins A and B, was established by conversion of emmotin-F into (+)-occidol.     

Gallium toxicity and adaptation in Pseudomonas fluorescens

When cultured in a defined citrate medium supplemented with 1 mM gallium (III) Pseudomonas fluorescens ATCC 13525 experienced a lag phase of 40 h with no apparent diminution in cellular yield. Following initial uptake of the metal-ligand complex, gallium was secreted in the spent fluid. This lag phase was abolished either by inoculating the medium with gallium adapted cells or by inclusion of iron (III) (20 microM) in the growth medium. In the culture enriched with both gallium and iron (III), X-ray fluorescence spectra revealed a gradual decrease of gallium from the spent fluid as growth progressed. In a phosphate deficient medium, no cellular multiplication was observed in the presence of gallium. The inhibitory influence mediated by the trivalent metal was reversed by the addition of (20 microM) iron (III). Although bacterial growth was accompanied by an initial decrease in exocellular gallium, a marked increment in the concentration of this metal was observed in the spent fluid at stationary phase of growth. Citrate was not detected in the exocellular fluid at cessation of bacterial multiplication. Electrophoretic analyses revealed numerous variations in the cytoplasmic protein profiles of the control and metal stressed cells. Gallium induced the syntheses of polypeptides with apparent molecular masses of 89 kDa, 50 kDa, 39 kDa, 26 kDa and 12 kDa.     

Exocellular and intracellular accumulation of lead in Pseudomonas fluorescens ATCC 13525 is mediated by the phosphate content of the growth medium

Pseudomonas fluorescens appears to elicit disparate lead detoxification mechanisms in phosphate-rich and phosphate-deficient media. When grown in the presence of 0.1 mM Pb2+ complexed to citrate, the sole source of carbon, only a slight diminution in cellular yield was observed in the former medium. However, in a phosphate-deficient milieu, lead imposed approximately a 30% reduction in bacterial multiplication. At stationary phase of growth, 72% of the metal was found in the bacterial cells from the phosphate-deficient medium, while that from phosphate-rich broth contained only 12.5%. The latter medium was characterized by an insoluble pellet that accounted for 73.5% of the lead. Although no citrate was detected in the phosphate-rich media after 40 h of incubation, only 72% of citrate was consumed even after 70 h of growth in the phosphate-deficient cultures. The inclusion of lead did not appear to enhance the production of either extracellular proteins or carbohydrates.     

Genes and people in the caspian littoral: A population genetic study in northern Iran

Data for the distribution of alleles controlling two blood group systems and secretor status, for hemoglobin types, five serum protein groups and 15 red cell enzyme systems has been obtained. Eleven of the systems showed polymorphic variation and these systems have been used to calculate genetic distances using Morton's Kinship measure. No systematic relationship between genetic distance and geographic location of linguistic affiliation is apparent. There is, however, an apparent cline of decreasing frequency of PGD^c from east to west and also significant differences in the frequency of G6PD deficiency corresponding to variation in the ecology of the region. Genetic distance comparisons with other selected populations reveal that the Turkic and Turkoman speaking peoples in the Caspian area cluster with the Kurds, Greeks and Iranis. The Persian speakers are genetically remote from these populations; they are, however, close to the Parsis who migrated from Iran to India at the end of the Seventh Century A.D. Several unusual genetic variants were detected, including a novel MDH pheno-type, a superoxide dismutase phenotype identical with the Scandinavian type, and rare forms of LDH, PGM locus 2, ceruloplasmin, diaphorase, peptidases and PHI.     

Targeted bacterial immunity buffers phage diversity

Bacteria have evolved diverse defense mechanisms that allow them to fight viral attacks. One such mechanism, the clustered, regularly interspaced, short palindromic repeat (CRISPR) system, is an adaptive immune system consisting of genetic loci that can take up genetic material from invasive elements (viruses and plasmids) and later use them to reject the returning invaders. It remains an open question how, despite the ongoing evolution of attack and defense mechanisms, bacteria and viral phages manage to coexist. Using a simple mathematical model and a two-dimensional numerical simulation, we found that CRISPR adaptive immunity allows for robust phage-bacterium coexistence even when the number of virus species far exceeds the capacity of CRISPR-encoded genetic memory. Coexistence is predicted to be a consequence of the presence of many interdependent species that stress but do not overrun the bacterial defense system.     

Effects of polycythemia on systemic endothelial function in chronic hypoxic lung disease

Chronic obstructive pulmonary disease (COPD) is a major risk factor for cardiovascular disease. Polycythemia, a common complication of hypoxic COPD, may affect systemic vascular function by altering blood viscosity, vessel wall shear stress (WSS), and endothelium-derived nitric oxide (NO) release. Here, we evaluated the effects of hypoxia-related polycythemia on systemic endothelial function in patients with COPD. We investigated blood viscosity, WSS, and endothelial function in 15 polycythemic and 13 normocythemic patients with COPD of equal severity, by recording brachial artery diameter variations in response to hyperemia and by using venous occlusion plethysmography (VOP) to measure forearm blood flow (FBF) responses to a brachial artery infusion of acetylcholine (ACh), bradykinin (BK), sodium nitroprusside (SNP), substance P (SP), isoptin, and N-monomethyl-L-arginine (L-NMMA). At baseline, polycythemic patients had higher blood viscosity and larger brachial artery diameter than normocythemic patients but similar calculated WSS. Flow-mediated brachial artery vasodilation was increased in the polycythemic patients, in proportion to the hemoglobin levels. ACh-induced vasodilation was markedly impaired in the polycythemic patients and negatively correlated with hemoglobin levels. FBF responses to endothelium- (BK, SP) and non-endothelium-dependent (SNP, isoptin) vasodilators were not significantly different between the two groups. L-NMMA infusion induced a similar vasoconstrictor response in both groups, in accordance with their similar baseline WSS. In conclusion, systemic arteries in polycythemic patients adjust appropriately to chronic or acute WSS elevations by appropriate basal and stimulated NO release. Overall, our results suggest that moderate polycythemia has no adverse effect on vascular function in COPD.     

Effect of Different Antibiotics and Non-Steroidal Anti-Inflammatory Drugs on the Growth of Lactobacillus casei Shirota

The purpose of this study was to investigate whether some non-steroidal anti-inflammatory drugs (NSAIDs) could cause inhibition of the growth of Lactobacillus casei Shirota (LcS) or whether this microorganism is able to use some of them as the sole carbon source, considering that the simultaneous consumption of NSAIDs and a dairy drink fermented with LcS could help to prevent the appearance or improve the healing of gastric ulcers. Acetylsalicylic acid (ASA), sodium acetylsalicylate (SAS), acetaminophen, sodium naproxen, and sodium ibuprofen were added as the sole carbon source to a basal medium and tested for biodegradation by LcS. The same NSAIDs were added in different concentrations to disks and plated on MRS Agar to test the possible inhibitory effect of these compounds on LcS. Also, the resistance of LcS to 12 different antibiotics was studied on MRS agar. None of the NSAIDs tested could be used by LcS as the sole carbon source at the assayed concentrations. In the case of the disk diffusion method, sodium naproxen showed inhibition zones for the 500-μg disks and sodium ibuprofen was inhibitory for the 250- and 500-μg disks. However, when the macrobroth dilution method was used, the growth of LcS was inhibited by ASA, SAS, acetaminophen, and sodium ibuprofen. This strain showed resistance to the antibiotics sulfamethoxazole with trimethoprim, pefloxacin, and gentamicin. This is the first study on the effect of NSAIDs on probiotic bacteria. The results of the biodegradation test indicate that the simultaneous consumption of NSAIDs and a dairy beverage with LcS is not likely to change the bioavailability of the drugs.     

Prevalence and Phase Variable Expression Status of Two Autotransporters,NalP and MspA,in Carriage and Disease Isolates of Neisseria meningitidis

Neisseria meningitidis is a human nasopharyngeal commensal capable of causing life-threatening septicemia and meningitis. Many meningococcal surface structures, including the autotransporter proteins NalP and MspA, are subject to phase variation (PV) due to the presence of homopolymeric tracts within their coding sequences. The functions of MspA are unknown. NalP proteolytically cleaves several surface-located virulence factors including the 4CMenB antigen NhbA. Therefore, NalP is a phase-variable regulator of the meningococcal outer membrane and secretome whose expression may reduce isolate susceptibility to 4CMenB-induced immune responses. To improve our understanding of the contributions of MspA and NalP to meningococcal-host interactions, their distribution and phase-variable expression status was studied in epidemiologically relevant samples, including 127 carriage and 514 invasive isolates representative of multiple clonal complexes and serogroups. Prevalence estimates of >98% and >88% were obtained for mspA and nalP, respectively, with no significant differences in their frequencies in disease versus carriage isolates. 16% of serogroup B (MenB) invasive isolates, predominately from clonal complexes ST-269 and ST-461, lacked nalP. Deletion of nalP often resulted from recombination events between flanking repetitive elements. PolyC tract lengths ranged from 6–15 bp in nalP and 6–14 bp in mspA. In an examination of PV status, 58.8% of carriage, and 40.1% of invasive nalP-positive MenB isolates were nalP phase ON. The frequency of this phenotype was not significantly different in serogroup Y (MenY) carriage strains, but was significantly higher in invasive MenY strains (86.3%; p<0.0001). Approximately 90% of MenB carriage and invasive isolates were mspA phase ON; significantly more than MenY carriage (32.7%) or invasive (13.7%) isolates. This differential expression resulted from different mode mspA tract lengths between the serogroups. Our data indicates a differential requirement for NalP and MspA expression in MenB and MenY strains and is a step towards understanding the contributions of phase-variable loci to meningococcal biology.     

Imaging Axl expression in pancreatic and prostate cancer xenografts

The receptor tyrosine kinase Axl is overexpressed in and leads to patient morbidity and mortality in a variety of cancers. Axl–Gas6 interactions are critical for tumor growth, angiogenesis and metastasis. The goal of this study was to investigate the feasibility of imaging graded levels of Axl expression in tumors using a radiolabeled antibody. We radiolabeled anti-human Axl (Axl mAb) and control IgG1 antibodies with ¹²⁵I with high specific radioactivity and radiochemical purity, resulting in an immunoreactive fraction suitable for in vivo studies. Radiolabeled antibodies were investigated in severe combined immunodeficient mice harboring subcutaneous CFPAC (Axl^high) and Panc1 (Axl^low) pancreatic cancer xenografts by ex vivo biodistribution and imaging. Based on these results, the specificity of [¹²⁵I]Axl mAb was also validated in mice harboring orthotopic Panc1 or CFPAC tumors and in mice harboring subcutaneous 22Rv1 (Axl^low) or DU145 (Axl^high) prostate tumors by ex vivo biodistribution and imaging studies at 72 h post-injection of the antibody. Both imaging and biodistribution studies demonstrated specific and persistent accumulation of [¹²⁵I]Axl mAb in Axl^high (CFPAC and DU145) expression tumors compared to the Axl^low (Panc1 and 22Rv1) expression tumors. Axl expression in these tumors was further confirmed by immunohistochemical studies. No difference in the uptake of radioactivity was observed between the control [¹²⁵I]IgG1 antibody in the Axl^high and Axl^low expression tumors. These data demonstrate the feasibility of imaging Axl expression in pancreatic and prostate tumor xenografts.