Rapid detection of quinolone-resistant Salmonella by real time SNP genotyping

A total of 63 isolates were screened for the gyrA mutation (87Asp-Tyr) in Salmonella enterica serovars using real time PCR. All of the isolates were successfully identified as resistant or susceptible, consistent with the MIC result of the agar dilution method and gyrA sequencing.     

Gender differences in body-sway factors of center of foot pressure in a static upright posture and under the influence of alcohol intake

This study aimed to examine gender differences in 4 body-sway factors of the center of foot pressure (CFP) during a static upright posture and the influence of alcohol intake on them. Four body-sway factors were interpreted in previous studies using factor analysis (the principal factor method and oblique solution by promax-rotation) on 220 healthy young males and females as follows; unit time sway, front-back sway, left-right sway and high frequency band power. The CFP measurement for 1 min was carried out twice with 1 min rest. The measurements of blood pressure, heart rate, whole body reaction time, standing on one leg with eyes closed, and CFP were carried out before and after the alcohol intake using 11 healthy young males and females. The measurement device used was an Anima's stabilometer G5500. The data sampling frequency was 20 Hz. Reliability of 4 body-sway factors was very high. Significant gender differences were found in the left-right sway and the high frequency band power factors, but the influence on body-sway is, as a whole, can be disregarded. These four sway factors can determine the influence of alcohol intake as efficient as 32 sway parameters.     

Synthesis and properties of bifunctional chloroalkyl nitrosamines with an intercalating moiety

Three N-nitroso-N-(arylcarbonyloxymethyl)-3-chloropropylamines were synthesized, and their chemical and biological properties were studied. All arylcarboxylates intercalated with double-stranded DNA, and their mutagenicity and DNA cross-linking activity were affected by their ring structure. The DNA interstrand cross-link formation increased dose dependently after treatment with the acridine analog. The anthraquinone analog showed the highest bacterial mutagenicity among the three nitrosamines in Salmonella typhimurium TA100, while in Salmonella typhimurium TA92, which can detect cross-linking agents, the acridine analog showed the highest mutagenicity. This agreed with the result of a cross-linking assay. These results suggest that the three-ring aromatic moiety gives DNA-intercalating ability to cross-linkable chloropropyl nitrosamine, and the acridine analog is considered as a possible new antitumor lead compound.     

BIG2, a guanine nucleotide exchange factor for ADP-ribosylation factors: its localization to recycling endosomes and implication in the endosome integrity

Small GTPases of the ADP-ribosylation factor (ARF) family play a key role in membrane trafficking by regulating coated vesicle formation, and guanine nucleotide exchange is essential for the ARF function. Brefeldin A blocks the ARF-triggered coat assembly by inhibiting the guanine nucleotide exchange on ARFs and causes disintegration of the Golgi complex and tubulation of endosomal membranes. BIG2 is one of brefeldin A-inhibited guanine nucleotide exchange factors for the ARF GTPases and is associated mainly with the trans-Golgi network. In the present study, we have revealed that another population of BIG2 is associated with the recycling endosome and found that expression of a catalytically inactive BIG2 mutant, E738K, selectively induces membrane tubules from this compartment. We also have shown that BIG2 has an exchange activity toward class I ARFs (ARF1 and ARF3) in vivo and inactivation of either ARF exaggerates the BIG2(E738K)-induced tubulation of endosomal membranes. These observations together indicate that BIG2 is implicated in the structural integrity of the recycling endosome through activating class I ARFs.     

Sequence dependence of substrate recognition and cleavage by yeast RNase III

Yeast Rnt1p is a member of the double-stranded RNA (dsRNA) specific RNase III family of endoribonucleases involved in RNA processing and RNA interference (RNAi). Unlike other RNase III enzymes, which recognize a variety of RNA duplexes, Rnt1p cleaves specifically RNA stems capped with the conserved AGNN tetraloop. This unusual substrate specificity challenges the established dogma for substrate selection by RNase III and questions the dsRNA contribution to recognition by Rnt1p. Here we show that the dsRNA sequence adjacent to the tetraloop regulates Rnt1p cleavage by interfering with RNA binding. In context, sequences surrounding the cleavage site directly influence the cleavage efficiency. Introduction of sequences that stabilize the RNA helix enhanced binding while reducing the turnover rate indicating that, unlike the tetraloop, Rnt1p binding to the dsRNA helix may become rate-limiting. These results suggest that Rnt1p activity is strictly regulated by a combination of primary and tertiary structural elements allowing a substrate-specific binding and cleavage efficiency.     

ARF tumor suppressor induces mitochondria-dependent apoptosis by modulation of mitochondrial Bcl-2 family proteins

A tumor suppressor gene product, ARF, sensitizes cells to apoptosis in the presence of appropriate collateral signals. In this study, we analyzed the mechanism of ARF-dependent apoptosis and demonstrated that ARF induces mitochondria-dependent apoptosis in p53 wild-type, ARF/p16-null cells. We also found that ARF evokes cytochrome c release from mitochondria, decreases mitochondrial membrane potential, and activates pro-caspase-9 to induce apoptosis. Our findings suggest that this apoptotic cellular modulation is brought about by up-regulation of the proapoptotic Bcl-2 family proteins Bax and Bim and down-regulation of antiapoptotic Bcl-2 in mitochondrial fractions. Additionally, ARF seems to down-regulate Bcl-2 in a p53-dependent manner while up-regulating Bax/Bim via a p53-independent pathway.     

Cytopathologic and clinicopathologic features of ovarian hepatoid carcinoma. A case report

BACKGROUND: Hepatoid carcinoma is a rare ovarian tumor and is thought to be a different histopathologic subtype from hepatoid-type yolk sac tumor based upon its pathologic features. However, the cytopathologic characteristics of ovarian hepatoid carcinoma (OHC) have not been reported previously. We report the clinicopathologic and cytopathologic features and immunoreactivity of a case of OHC. CASE: A 36-year-old woman presented to our department with lower abdominal pain. A left ovarian tumor was found on pelvic examination, magnetic resonance imaging and computed tomography. The tumor was diagnosed as a hepatoid carcinoma of the left ovary based upon the histopathology of the surgically resected specimen. Cytopathologic specimens from a tumor touch preparation of the tumor exhibited pleomorphic tumor cells with abundant cytoplasm. The nuclei contained rough, granular chromatin and large, prominent nucleoli. Several tumor cells were multinucleated. Tumor cells were immunoreactive for alpha-fetoprotein (AFP). Hematoxylin and eosin staining revealed that the tumor cells were in a sinusoidal pattern resembling hepatocellular carcinoma without any glandular formation. The tumor cells were negative for human chorionic gonadotropin while positive for AFP, alpha-1-antitripsin, CA-125 and carcinoembryonic antigen. CONCLUSION: Cytopathologic examination is of considerable aid in the diagnosis of OHC since cytopathologic preparations highlight the characteristic cell pleomorphism.     

Characterization of folding pathways of the type-1 and type-2 periplasmic binding proteins MglB and ArgT

The family of periplasmic binding proteins (PBPs) is believed to have arisen from a common ancestor and to have differentiated into two types. At first approximation, both types of PBPs have the same fold pattern, reflecting their common origin. However, the connection between the main chains of a type 2 PBP is more complicated than a type 1 PBP's. We have been interested in the possibility that such structural changes affect the folding of PBPs. In this study, we have characterized the folding pathways of MglB (a type 1 PBP) and ArgT (a type 2 PBP) by using urea gradient gel electrophoresis, fast protein size-exclusion liquid chromatography and hydrophobic dye ANS binding assay. We found a distinct difference in folding between these two proteins. The folding of MglB followed a simple two-state transition model, whereas the folding of ArgT was more complicated.     

Borg proteins control septin organization and are negatively regulated by Cdc42

The Cdc42 GTPase binds to numerous effector proteins that control cell polarity, cytoskeletal remodelling and vesicle transport. In many cases the signalling pathways downstream of these effectors are not known. Here we show that the Cdc42 effectors Borg1 to Borg3 bind to septin GTPases. Endogenous septin Cdc10 and Borg3 proteins can be immunoprecipitated together by an anti-Borg3 antibody. The ectopic expression of Borgs disrupts normal septin organization. Cdc42 negatively regulates this effect and inhibits the binding of Borg3 to septins. Borgs are therefore the first known regulators of mammalian septin organization and provide an unexpected link between the septin and Cdc42 GTPases.