Engineering N-linked protein glycosylation with diverse O antigen lipopolysaccharide structures in Escherichia coli

Campylobacter jejuni has a general N-linked protein glycosylation system that can be functionally transferred to Escherichia coli. In this study, we engineered E. coli cells in a way that two different pathways, protein N-glycosylation and lipopolysaccharide (LPS) biosynthesis, converge at the step in which PglB, the key enzyme of the C. jejuni N-glycosylation system, transfers O polysaccharide from a lipid carrier (undecaprenyl pyrophosphate) to an acceptor protein. PglB was the only protein of the bacterial N-glycosylation machinery both necessary and sufficient for the transfer. The relaxed specificity of the PglB oligosaccharyltransferase toward the glycan structure was exploited to create novel N-glycan structures containing two distinct E. coli or Pseudomonas aeruginosa O antigens. PglB-mediated transfer of polysaccharides might be valuable for in vivo production of O polysaccharides-protein conjugates for use as antibacterial vaccines.     

Identification of a mammalian gene structurally and functionally related to the CDC25 gene of Saccharomyces cerevisiae.

The yeast Saccharomyces cerevisiae CDC25 gene encodes a nucleotide-exchange-factor (NEF) that can convert the inactive GDP-bound state of RAS proteins to an active RAS-GTP complex. CDC25 can activate the yeast RAS proteins as well as the human H-ras protein. CDC25 is a member of a family of yeast genes that likely encode NEFs capable of regulating the RAS-related proteins found in yeast. By aligning the amino acid sequence of CDC25-related gene products we found a number of conserved motifs. Using degenerate oligonucleotides that encode these conserved sequences, we have used polymerase chain reactions to amplify fragments of mouse and human cDNAs related to the yeast CDC25 gene. We show that a chimeric molecule, part mouse and part yeast CDC25, can suppress the loss of CDC25 function in the yeast S. cerevisiae.     

The impact of intra operative ultrasound in metastases liver surgery

BACKGROUND: Twenty-five to 50% of the patients with hepatic metastases are potential candidates for curative surgery. Intraoperative ultrasound has been employed to guide the surgery. AIM: To evaluate this method in liver surgeries and compare it to other imaging methods. PATIENTS AND METHODS: Thirty-five patients (20 females, with median age of 56 years) with hepatic metastases were prospectively studied between February 2001 and July 2003. Patients had as primary tumors: colorectal cancer (24), neuroendocrine tumors (3), renal cell carcinoma (2), melanoma (2), others (4). Each patient was submitted to at least: computed tomography (30), ultrasonography (14) and magnetic resonance imaging (8). Intraoperative ultrasound was performed in all patients in order to detect liver nodules. The number and location of liver lesions were compared to preoperative results. RESULTS: Intraoperative ultrasound was useful in 23 (65.6%) of the 35 surgeries and changed the planned surgical strategy in 9 (25.7%). There was a statistical significant correlation between the mean number of nodules identified by ultrasonography, computed tomography, magnetic resonance imaging and intraoperative ultrasound. We found no statistical difference between magnetic resonance imaging and intraoperative ultrasound in identifying hepatic nodules. Fifty-five nodules were submitted to histological evaluation, the gold standard method and 52/55 (94.5%) were identified by intraoperative ultrasound. Intraoperative ultrasound identified 91.6% of the smaller than 1.5 cm lesions, ultrasonography identified 15.0% of them, computed tomography 33.3% and magnetic resonance imaging 66.6%. CONCLUSIONS: Intraoperative ultrasound is crucial in the evaluation and decision making in hepatic surgery. Intraoperative ultrasound presents the highest sensibility in the detection of hepatic nodules compared to other imaging methods, especially for small lesions.     

Socialization Patterns and Their Associations with Unprotected Anal Intercourse,HIV, and Syphilis Among High-Risk Men Who Have Sex with Men and Transgender Women in Peru

The association of socialization patterns with unprotected anal intercourse (UAI) and HIV/STI prevalence remains underexplored in men who have sex with men (MSM) and transgender women (TW) in developing country settings. We evaluated the correlation of UAI, HIV, and syphilis with MSM/TW venue attendance and social network size among high-risk MSM and TW in Peru according to self-reported sexual identity. Frequency of venue attendance and MSM/TW social network size were lowest among heterosexual MSM and highest among TW respondents. Attendance (frequent or occasional) at MSM/TW venues was associated with increased odds of insertive UAI among heterosexual participants. Frequent venue attendance was associated with increased odds of receptive UAI among gay/homosexual, bisexual, and TW participants. Further investigation of the differing socialization patterns and associations with HIV/STI transmission within subgroups of Peruvian MSM and TW will enable more effective prevention interventions for these populations.     

Diagnosis and management of hepatic artery in-stent restenosis after liver transplantation by optical coherence tomography:A case report

BACKGROUND Percutaneous transluminal angioplasty and stenting represent an effective treatment for hepatic artery stenosis after liver transplantation. In the first year after stenting, approximately 22% of patients experience in-stent restenosis, increasing the risk of artery thrombosis and related complications, and 50% experience liver failure. Although angiography is an important tool for diagnosis and the planning of therapeutic interventions, it may raise doubts, especially in small-diameter arteries, and it provides low resolution rates compared with newer intravascular imaging methods, such as optical coherence tomography(OCT).CASE SUMMARY A 64-year-old male developed hepatic artery stenosis one year after orthotropic liver transplantation and was successfully treated with percutaneous transluminal angioplasty with stenting. Five months later, the Doppler ultrasound results indicated restenosis. Visceral arteriography confirmed hepatic artery tortuosity but was doubtful for significant in-stent restenosis(ISR) and intrahepatic flow reduction. To confirm ISR, identify the etiology and guide treatment, OCT was performed. OCT showed severe stenosis due to four mechanisms: Focal and partial stent fracture, late stent malapposition, in-stent neointimal hyperplasia, and neoatherosclerosis.CONCLUSION Intravascular diagnostic methods can be useful in evaluating cases in which initial angiography results are not sufficient to provide a proper diagnosis of significant stenosis, especially with regard to ISR. A wide range of diagnoses are provided by OCT, resulting in different treatment options. Interventional radiologists should consider intravascular diagnostic methods as additional tools for evaluating patients when visceral angiography results are unclear.