OXA-14, another extended-spectrum variant of OXA-10 (PSE-2) beta-lactamase from Pseudomonas aeruginosa.

Pseudomonas aeruginosa 455, isolated in Ankara, Turkey, produced a pI 6.2 beta-lactamase determined by plasmid pMLH53 and resisted all beta-lactams except carbapenems. This beta-lactamase, named OXA-14, corresponded to OXA-10 (PSE-2) except that aspartate replaced glycine at position 157 and thus is intermediate between OXA-10 and OXA-11, which has aspartate at position 157 and a further substitution at position 143.     

A sexually dimorphic ratio of orbitofrontal to amygdala volume is altered in schizophrenia.

BACKGROUND: Neuroanatomic sexual dimorphisms have been correlated with behavioral differences between healthy men and women. We have reported higher orbitofrontal cortex to amygdala ratio (OAR) in women than men. Although gender differences in schizophrenia are evident clinically and correlate with neuroanatomic measures, their relationship to OAR has not been examined. METHODS: Magnetic resonance imaging was performed in 31 neuroleptic-na?ve schizophrenic patients (16 men) and 80 healthy volunteers (34 men), aged less than 50 years. An automated tissue segmentation procedure was combined with expert-guided parcellation of orbitofrontal and amygdala volumes. RESULTS: Men with schizophrenia had increased OAR relative to healthy men, whereas women had decreased OAR. Increased OAR in men with schizophrenia reflected abnormally low amygdala volumes, whereas decreased OAR in women reflected abnormally low orbitofrontal volumes. Less severe negative symptoms were associated with increased OAR in men but with decreased OAR in women. In men, increased amygdala volume was associated with greater symptom severity, whereas in women higher volumes of both amygdala and orbitofrontal regions were associated with lesser severity of negative symptoms. CONCLUSIONS: These opposite OAR abnormalities, whereby men show feminization and women masculinization, suggest gender-mediated effects of the underlying neuropathologic processes. The correlations with symptom severity suggest that neuroanatomic abnormalities in OAR reflect compensatory brain changes.     

Does work with visual display units impair visual activities after work?

It is well established that visual display unit (VDU) operators complain of visual fatigue and visual stress during after-work hours. The present study was divided into two parts. In the first part, standard eye examinations were performed on a group of VDU workers (n = 32) and a control group (n = 15); those subjects who were found to have correct vision (n = 16 and 13, respectively) participated in the second part. The eye examinations revealed that on the average, the VDU workers suffered more than twice as many visual impairments as the controls. In those with correct vision, the near point of accommodation was measured at the beginning of the workday at the start of the week, and at the end of the workday, four days later. In the VDU group, the decrease in accommodation was uniformally distributed between zero and 1.0 diopter, whereas among the non-VDU workers, 77% of the decrease was between zero and 0.25 diopter. The dynamic range of accommodation in the VDU workers on the second examination was smaller than on the first. We conclude that some of the visual stress and visual fatigue that developed at work hindered visual activities after work.     

Helicobacter pylori infection in haemodialysis patients and renal transplant recipients

Background. It is known that Helicobacter pylori (Hp) plays an important role in gastritis and peptic ulcer disease in the general population. Although dyspeptic complaints are frequent in haemodialysis (HD) patients and renal transplant recipients, there are few reports regarding the prevalence of Hp and its possible effects on this group of patients. This study was performed to examine the prevalence of Hp infection in patients on regular HD treatment and to detect its role in the pathogenesis of dyspepsia in this group of patients. Methods. Two hundred and one patients with dyspeptic complaints were included in the study. The groups consisted of 47 HD, 54 renal transplant recipients, and 100 non-renal disease patients. Upper gastrointestinal endoscopies were performed and gastric antral biopsies were obtained for urease test in all patients. Results. Twenty-eight (60%) of the 47 HD and 28 (70%) of the 54 RTR were positive for Hp. Sixty-four (64%) of the 100 patients with various gastrointestinal complaints and known to have no renal dysfunction were positive for Hp. The Hp prevalences among the three groups were not significantly different (P <0.05). The prevalence of Hp infection did not correlate with the haemodialysis duration nor the post-transplantation duration (P <0.05). There was no correlation between the prevalence of Hp infection and duration of haemodialysis therapy or time post-transplantation. Conclusion. These findings suggest that HD patients are not protected against Hp infection as the Hp prevalences are as high as that for the non-renal disease group. The increased dyspeptic complaints may be partly related to Hp infection.     

A comparison of two data analyses from two observer performance studies using Jackknife ROC and JAFROC

The authors compared two methodological approaches, Jackknife ROC and JAFROC, in analyzing data ascertained during FROC (free-response receiver operating characteristics) type studies. Observer rating data obtained from two observer performance studies were analyzed. During the first study, seven radiologists interpreted 120 mammography examinations depicting 57 masses under five different conditions with and without the results of computer-aided detection (CAD). In the second study, eight radiologists interpreted 110 examinations depicting 51 masses under six different display conditions with and without CAD results. Readers rated the detection task in a FROC type response. Jackknife ROC (using the software of LABMRMC with the highest rating per case) and JAFROC were used to compute differences, if any, in summary performance levels among all reading modes in each study as well as for all paired data sets. The results of the different analytical approaches are compared. The overall results for all modes were significantly different for the first study (p < 0.05) and not significant (p > 0.05) for the second study using either analytical approach. In the first study, the performance levels represented by three paired data sets were significantly different (p < 0.05) when computed using LABMRMC and four pairs were significantly different (p < 0.05) using JAFROC. In eight of ten pairs, JAFROC produced lower p values than LABMRMC. In the second study, LABMRMC showed no significant differences for any paired data sets and JAFROC showed a significant difference for one pair. In 15 of 16 pairs, p values computed by JAFROC were lower than those computed by LABMRMC.     

Intracellular survival of persistent group A streptococci in cultured epithelial cells

Group A streptococcus (GAS) is the principle etiologic agent of bacterial pharyngotonsillitis and a wide range of other diseases. Failure to eradicate GAS from patients has been documented in 5-30% of patients with pharyngotonsillitis, in spite of the continued sensitivity of GAS to penicillin and other beta-lactams. It was recently proposed that eradication failure might be attributed to the ability of GAS to maintain an intracellular reservoir during antibiotic treatment. We have previously shown that strains derived from patients with bacterial eradication failure, despite antibiotic treatment (persistent strains), adhered to and were internalized by cultured epithelial cells more efficiently than strains that were successfully eradicated. Since, penicillin and other beta-lactams do not penetrate well into mammalian cells, intracellular survival of GAS is crucial in order to persist during prolonged antibiotic treatment. In this study, we compared the survival of GAS strains from cases of eradication failure and eradication success, using an epithelial cell culture model. We found that persistent strains show significantly increased intracellular survival, compared to the 'eradication success' strains. This finding supports the idea that an intracellular reservoir of GAS plays a role in the etiology of antibiotic eradication failure.     

Joint Photographic Experts Group (JPEG) compatible data compression of mammograms

We have developed a Joint Photographic Experts Group (JPEG) compatible image compression scheme tailored to the compression of digitized mammographic images. This includes a preprocessing step that segments the tissue area from the background, replaces the background pixels with a constant value, and applies a noise-removal filter to the tissue area. The process was tested by performing a just-noticeable difference (JND) study to determine the relationship between compression ratio and a reader's ability to discriminate between compressed and noncompressed versions of digitized mammograms. We found that at compression ratios of 15∶1 and below, image-processing experts are unable to detect a difference, whereas at ratios of 60∶1 and above they can identify the compressed image nearly 100% of the time. The performance of less specialized viewers was significantly lower because these viewers seemed to have difficulty in differentiating between artifact and real information at the lower and middle compression ratios. This preliminary study suggests that digitized mammograms are very amenable to compression by techniques compatible with the JPEG standard. However, this study was not designed to address the efficacy of image compression process for mammography, but is a necessary first step in optimizing the compression in anticipation of more elaborate reader performance (ROC) studies.     

Molecular mechanism of kNBC1–carbonic anhydrase II interaction in proximal tubule cells

We have recently shown that carbonic anhydrase II (CAII) binds in vitro to the C-terminus of the electrogenic sodium bicarbonate cotransporter kNBC1 (kNBC1-ct). In the present study we determined the molecular mechanisms for the interaction between the two proteins and whether kNBC1 and CAII form a transport metabolon in vivo wherein bicarbonate is transferred from CAII directly to the cotransporter. Various residues in the C-terminus of kNBC1 were mutated and the effect of these mutations on both the magnitude of CAII binding and the function of kNBC1 expressed in mPCT cells was determined. Two clusters of acidic amino acids, L⁹⁵⁸DDV and D⁹⁸⁶NDD in the wild-type kNBC1-ct involved in CAII binding were identified. In both acidic clusters, the first aspartate residue played a more important role in CAII binding than others. A significant correlation between the magnitude of CAII binding and kNBC1-mediated flux was shown. The results indicated that CAII activity enhances flux through the cotransporter when the enzyme is bound to kNBC1. These data are the first direct evidence that a complex of an electrogenic sodium bicarbonate cotransporter with CAII functions as a transport metabolon.     

Genetic association of the PERIOD3 (PER3) Clock gene with extreme obesity

BackgroundObesity has reached epidemic proportions worldwide, affecting life quality and span. Susceptibility to obesity is partly mediated by genetic differences. Indeed, several genes from the clock gene family have already been shown to be intimately associated with obesity in diverse ethnic groups. In the present study, an association between BMI and the rs707467, rs228697 and rs228729 PER3 (Period Circadian Clock 3) polymorphisms in subjects with class II (BMI ≥ 35.0–39.9 kg/m²) and class III obesity (>40 kg/m², extreme obesity) were carried out using TaqMan real-time PCR. Overall, 259 Brazilian adults were genotyped, of whom 122 had class II or III obesity (BMI ≥ 35.0 kg/m²) and 137 were controls having normal weight (BMI > 18.5 and <24.9 kg/m²).ResultsPER3 tag SNP (rs228729) shows a significant association with extreme obesity (1000 permutation p = 0.03 and p = 0.04), for genotype and allele frequency respectively) and a haplotype among the three assessed SNPs (alleles G/T/A, rs228697, rs228729, and rs707467, respectively, 1000 permutation p = 0.03) was significantly more prevalent in the group with obesity.ConclusionThis exploratory association study suggests that PER3 rs228729 may be associated with extreme obesity in Brazilian adults, however, replication is needed.