Partial N-terminal amino acid sequences of three nonstructural proteins of two flaviviruses

Partial N-terminal amino acid sequences for the three largest nonstructural proteins of two flaviviruses, yellow fever virus and St. Louis encephalitis virus, have been obtained. The determined sequences of these proteins exhibit significant amino acid sequence homology, and allow the positioning of these three nonstructural proteins in the polyprotein sequence deduced from the nucleotide sequence of yellow fever virus (C. M. Rice, E. M. Lenches, S. R. Eddy, S. J. Shin, R. L. Sheets, and J. H. Strauss, 1985, Science 229, 726-733.) The deduced start points support the hypothesis that the N terminus of nonstructural glycoprotein NS1 results from cleavage by signalase, whereas the N termini of NS3 and NS5 result from cleavages following double basic residues that are flanked by amino acids with short side chains.     

From the Cover: Structure of PolC reveals unique DNA binding and fidelity determinants

PolC is the polymerase responsible for genome duplication in many Gram-positive bacteria and represents an attractive target for antibacterial development. We have determined the 2.4-Å resolution crystal structure of Geobacillus kaustophilus PolC in a ternary complex with DNA and dGTP. The structure reveals nascent base pair interactions that lead to highly accurate nucleotide incorporation. A unique β-strand motif in the PolC thumb domain contacts the minor groove, allowing replication errors to be sensed up to 8 nt upstream of the active site. PolC exhibits the potential for large-scale conformational flexibility, which could encompass the catalytic residues. The structure suggests a mechanism by which the active site can communicate with the rest of the replisome to trigger proofreading after nucleotide misincorporation, leading to an integrated model for controlling the dynamic switch between replicative and repair polymerases. This ternary complex of a cellular replicative polymerase affords insights into polymerase fidelity, evolution, and structural diversity.     

Comparison of Tetrahymena ARS sequence function in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe

Summary We have isolated several Tetrahymena thermophila chromosomal DNA fragments which function as autonomously replicating sequences (ARS) in the heterologous Saccharomyces cerevisiae and Schizosaccharomyces pombe selection systems. The Tetrahymena ARS sequences were first isolated in S. cerevisiae and were derived from non-ribosomal micro- and macronuclear DNA. Sequence analysis of the ARS elements identified either perfect or close matches with the 11 by S. cerevisiae ARS core consensus sequence. Subcloning studies of two Tetrahymena ARS elements defined functional regions ranging in size from 50 to 300 bp. Testing of the ARS elements in S. pombe revealed that most of the T. thermophila inserts confer ARS function in both yeasts, at least in the sense of promoting a high transformation frequency to plasmids which contain them. However, the actual sequences responsible for ARS activity were not always identical in the two yeasts.     

Accuracy of frozen section diagnosis in borderline ovarian malignancy

This study was conducted to determine the accuracy of frozen section diagnosis in borderline ovarian tumors. Thirty-three patients were evaluated on the basis of frozen sections between February 1992 and December 1997. Frozen section diagnosis and final diagnosis were divided into three categories: for frozen section diagnosis: 1 = benign, 2 = borderline, 3 = 'at least' borderline, and for final diagnosis: 1 = benign, 2 = borderline, 3 = cancer. Three patients with a benign diagnosis according to their frozen sections were reclassified as borderline in the final diagnosis and all of them were of the mucinous type. The frozen section diagnosis of tumors of borderline malignancy was inaccurate in 3 of 23 patients. Four of 7 patients with at least borderline according to their frozen section diagnosis had invasive cancer at the final diagnosis. The correlation between frozen section diagnosis and final pathological examination was 72.7% (24/33). We found 9% (2/22) inaccurate results in the serous type and 36.6% (4/11) in the mucinous type. The sensitivity and specificity of frozen section diagnosis were found to be 86.95 and 57.14%, respectively. We concluded that frozen section evaluation in identifying a borderline ovarian malignancy is accurate enough to exclude the presence of a benign pathology.     

Glutathione S-transferase M1, T1, and P1 gene polymorphism in laryngeal squamous cell carcinoma

PURPOSE: To investigate the influence of the glutathione S-transferase (GST) M1, T1, and P1 genotypes on the laryngeal squamous cell carcinoma risk. MATERIAL AND METHODS: The study group consisted of 42 white patients with laryngeal squamous cell carcinoma (39 of them were male, mean age: 53, range: 37-67 and 3 of them were female, mean age: 47, range: 32-55) and 89 control subjects (nonsmokers = 47, smokers = 42) (58 male and 31 female, mean age: 51, range: 30-72). DNA samples were isolated from blood samples using high pure polymerase chain reaction (PCR) Template Preparation Kit. The detection of GST T1, GST M1, and P1 polymorphisms were detected by using real-time PCR. RESULTS: Gene polymorphisms at GST M1 and P1 were not significantly different in patient and control groups. However, GST T1 null type significantly increased in laryngeal cancer patients when compared with the nonsmoking controls (P =.04). CONCLUSIONS: There was a significant association between GST T1 null genotype and laryngeal squamous cell carcinoma. However the potential role of GSTs as markers of susceptibility to laryngeal carcinoma needs further studies in a larger number of patients.     

Postmenopausal endometrial cancer screening: is there a correlation between transvaginal sonographic measurement of endometrial thickness and body mass index?

OBJECTIVE: The aim of this study was to correlate the body mass index with transvaginal sonographic measurement of endometrial thickness in a cohort of postmenopausal women who were admitted for endometrial cancer surveillance. MATERIAL AND METHODS: Transvaginal sonographic measurement of endometrial thickness was performed in 97 postmenopausal women who attended the gynecology clinic for endometrial cancer screening with no history of hormone replacement therapy and correlated with body mass index. Baseline characteristics including age, years since menopause and body mass index were recorded for each subject. The relationship between transvaginal sonographic endometrial thickness and baseline characteristics was assessed in each. RESULTS: Body mass index was significantly correlated with years since menopause (r = 0.292, p = 0.004) and age (r = 0.243, p = 0.01) but not with endometrial thickness (r = -0.07, p = 0.454). Endometrial thickness versus time since menopause correlation was found to be significant (r = 0.274, p = 0.03) in patients with a body mass index lower than 30. CONCLUSION: The present findings indicate that endometrial thickness does not differ with body mass index in the screening of postmenopausal women for endometrial cancer.     

Polycythemia vera and pregnancy: a case report with the use of hydroxyurea in the first trimester

Polycythemia vera (PV) is rarely associated with pregnancy. A 34-year-old patient treated with hydroxyurea for PV became pregnant and was referred to our clinic. At the patient's request, pregnancy was continued. The patient's hematocrit level remained below 45% without any treatment throughout her pregnancy, and a healthy male infant (without any congenital malformations or complications) was delivered at 37 weeks. This case report suggests that normal pregnancy and delivery is possible in patients with PV.     

Asymptomatic bilateral mixed-type laryngocele and laryngeal carcinoma

A laryngocele is an abnormal dilatation of the laryngeal saccule. The relationship between layngoceles and laryngeal carcinoma is still debated. We present the case of a 45-year-old male patient with bilateral asymptomatic laryngocele and laryngeal squamous cell carcinoma. We discuss the possible etiopathogenetic influence of increased intralaryngeal pressure with preoperative CT and explorative findings, and the current literature is reviewed.