The location of four fimbrin-encoding genes, agfA, fimA, sefA and sefD, on the Salmonella enteritidis and/or S. typhimurium XbaI-BlnI genomic restriction maps

The recombinant oncotoxin OLX-209 [e23(Fv)PE38KDEL] has been developed to target cancers with erbB-2 expression and is nearing a clinical trial. Important in clinical planning is the selection of patients on the basis of tumor expression of erbB-2. ErbB-2 gene amplification occurs in cancers of the breast, stomach, and ovary. Patients with these diseases and evident overexpression are candidates for OLX-209 therapy. In lung cancer, overexpression of erbB-2 is also frequent, but in most cases, it is not caused by gene amplification. This study demonstrates that OLX-209 has activity on lung cancer cells with varying levels of erbB-2 expression in the presence and absence of gene amplification. In vitro sensitivity of cell lines to OLX-209 is related to erbB-2 expression level. Normal bronchial epithelial cells were not sensitive. Effective treatment of lung cancer cell lines growing as xenografts in nude mice was shown with Calu-3 (a lung adenocarcinoma line with high levels of p185(erbB-2) caused by gene amplification) and three other lung adenocarcinomas (A549, NCI-H1466, and 201T) with lower levels of p185(erbB-2) and no gene amplification. The 201T cell line was isolated recently from a lung tumor with erbB-2 expression in the original tumor. The results of this study indicate that patients with erbB-2-positive, non-small cell lung cancer should be included in clinical trials of OLX-209.     

Enhancement of aquareovirus infectivity by treatment with proteases: mechanism of action

The effects of protease digestion on the polypeptide composition and on the infectivity of striped bass virus, an aquareovirus, were examined. Both trypsin and chymotrypsin enhanced the infectivity of the virus. Enhancement of infectivity was correlated with the digestion of the outer capsid protein, VP7. These studies support the assertion that VP7 is the outermost capsid protein and suggest that VP4 and VP5 are exposed on the outer surface of infectious particles. The possible role of VP7 in the variation in virulence observed among aquareovirus isolates is discussed.     

航天飞机的地面保障系统

美国航天飞机的地面保障系统包括航天跟踪和数据网(STDN)、网控制中心(NCC)、航天指控中心(MCC)和有效载荷操作控制中心(POCC)。本文综述上述各部分的组成、任务及它们之间的关系,并就我国载人航天测控通信网的操作控制中心的建设提出了基本看法。     

光纤通信区域网技术现状与发展趋势

指出了OFLAN的结构和特点,评述了发展OFLAN的关键技术,并对国内外OFLAN的发展应用作了详尽论述,最后综合概括了未来OFLAN技术的发展趋势。     

Prostaglandin E2 receptor subtype EP2 gene expression in the mouse uterus coincides with differentiation of the luminal epithelium for implantation

Among the PGs, PGE2 is considered especially important for implantation and decidualization. Four major PGE2 receptor subtypes, EP1, EP2, EP3, and EP4, mediate various PGE2 effects via their coupling to distinct signaling pathways. Previously, we have shown that the EP1, EP3, and EP4 genes are expressed in the periimplantation mouse uterus in a spatio-temporal manner, suggesting compartmentalized actions of PGE2 during this period. In this study, we examined the expression of the EP2 gene in the mouse uterus during the periimplantation period (days 1-8) and during experimentally induced progesterone (P4)-maintained delayed implantation and its resumption by 17beta-estradiol (E2). We also examined its regulation in the uterus by ovarian steroid hormones. Our results establish that EP2 messenger RNA (mRNA) is expressed exclusively in the luminal epithelium primarily on day 4 (the day of implantation) and day 5 (early implantation) of pregnancy. In (P4)-maintained delayed implanting mice, EP2 mRNA was present in the luminal epithelium, and the expression was further enhanced regardless of the location of the blastocysts after reinitiation of implantation. This observation suggests little or no embryonic influence in regulating EP2 expression and, instead, shows its regulation by P4 and E2. Indeed, treatment with E2 and/or P4 exhibited unique regulation of this gene. The treatment of adult ovariectomized mice with E2 down-regulated the basal levels of EP2 mRNA, whereas that with P4 up-regulated its levels in the luminal epithelium. The up-regulation of EP2 mRNA levels by P4 was further augmented by superimposition of the E2 treatment, suggesting a synergistic interaction between E2 and P4 in regulating this gene in the uterus. Collectively, the results suggest that EP2 could be a potential mediator of PGE2 actions in regulating luminal epithelial differentiation and serve as a marker for uterine receptivity for implantation.     

Emergence of a unique O3:K6 clone of Vibrio parahaemolyticus in Calcutta, India, and isolation of strains from the same clonal group from Southeast Asian travelers arriving in Japan

Active surveillance of Vibrio parahaemolyticus infection among hospitalized patients in Calcutta, India, was initiated in January 1994. The incidence of cases of V. parahaemolyticus infection suddenly increased in February 1996 and has remained high since then. One hundred thirty-four strains of V. parahaemolyticus isolated from January 1994 to August 1996 were examined for serovar, the presence of the thermostable direct hemolysin gene (tdh) and tdh-related hemolysin genes (trh1 and trh2), production of urease, and antibiogram. Strains of the O3:K6 serovar appeared for the first time in February 1996. The O3:K6 serovar strains accounted for 50 to 80% of the strains isolated during the high-incidence period (February to August 1996). All of the serovar O3:K6 strains carried the tdh gene but not the trh genes and did not produce urease. All of the isolates except two were sensitive to all of the antibiotics tested. These and the results of analysis by an arbitrarily primed PCR method indicated that the O3:K6 serovar strains belong to a unique clone. When the O3:K6 serovar strains, isolated from travelers arriving in Japan from Southeast Asian countries, were compared by the arbitrarily primed PCR method, the strains isolated between 1982 and 1993 were distinct from Calcutta O3:K6 while the strains isolated in 1995 and 1996 were indistinguishable from the Calcutta O3:K6 strains. The results suggest that this unique O3:K6 clone may have become prevalent not only in Calcutta but also in Southeast Asian countries very recently. Not only the O3:K6 strains but also the non-O3:K6, tdh-bearing strains isolated in 1996 produced thermostable direct hemolysin at high levels, and thus the level of hemolysin produced does not appear to have influenced the high incidence of serovar O3:K6 strains.     

Identification and characterization of kinetically competent carbinolamine and alpha-iminoglutarate complexes in the glutamate dehydrogenase-catalyzed oxidation of L-glutamate using a multiwavelength transient state approach

A highly constrained and heavily overdetermined multiwavelength transient state kinetic approach has been used to study the oxidative deamination of L-glutamate catalyzed by beef liver glutamate dehydrogenase. Spectra generated using the known enzyme-reduced coenzyme-substrate spectrum served as models for deconvolution of kinetic scan data. Deconvolution of the multiwavelength time course array shows formation of three distinguishable intermediates in the reaction sequence, an ultrablue-shifted complex, an ultrared-shifted complex, and a blue-shifted complex. The ultrablue-shifted entity is identified as the enzyme-NADPH-alpha-iminoglutarate complex (ERI) and the ultrared as the enzyme-NADPH-alpha-carbinolamine complex (ERC). The blue-shifted complex is characterized as the E-NADPH-ketoglutarate species (ERK). The location of these species along the reaction coordinate has been determined and their kinetic competency in the reaction sequence has been established by fitting the concentration time courses of the components for both the alpha-deuterio- and the alpha-protio-L-glutamate reactions to the now highly constrained differential equations derived from a kinetic scheme involving the sequential formation of alpha-iminoglutarate, alpha-carbinolamine, and alpha-ketoglutarate-reduced coenzyme complexes, following the formation of two prehydride transfer complexes.     

Imaging of squamous cell carcinoma of the hypopharynx

The hypopharynx is a clinically silent area and early lesions may be asymptomatic for a long period. At presentation, primary squamous cell carcinoma of this area is usually advanced. Almost all of these lesions are studied with imaging as part of the clinical work-up. The goal of this article is to help the practicing radiologist convey a report which provides information that will directly influence treatment of patients with hypopharyngeal carcinoma.