Interaction of herpes simplex virus glycoprotein gC with mammalian cell surface molecules

The entry of herpes simplex virus (HSV) into mammalian cells is a multistep process beginning with an attachment step involving glycoproteins gC and gB. A second step requires the interaction of glycoprotein gD with a cell surface molecule. We explored the interaction between gC and the cell surface by using purified proteins in the absence of detergent. Truncated forms of gC and gD, gC1(457t), gC2(426t), and gD1(306t), lacking the transmembrane and carboxyl regions were expressed in the baculovirus system. We studied the ability of these proteins to bind to mammalian cells, to bind to immobilized heparin, to block HSV type 1 (HSV-1) attachment to cells, and to inhibit plaque formation by HSV-1. Each of these gC proteins bound to conformation-dependent monoclonal antibodies and to human complement component C3b, indicating that they maintained the same conformation of gC proteins expressed in mammalian cells. Biotinylated gC1(457t) and gC2(426t) each bind to several cell lines. Binding was inhibited by an excess of unlabeled gC but not by gD, indicating specificity. The attachment of gC to cells involves primarily heparan sulfate proteoglycans, since heparitinase treatment of cells reduced gC binding by 50% but had no effect on gD binding. Moreover, binding of gC to two heparan sulfate-deficient L-cell lines, gro2C and sog9, both of which are mostly resistant to HSV infection, was markedly reduced. Purified gD1 (306t), however, bound equally well to the two mutant cell lines. In contrast, saturating amounts of gC1(457t) interfered with HSV-1 attachment to cells but failed to block plaque formation, suggesting a role for gC in attachment but not penetration. A mutant form of gC lacking residues 33 to 123, gC1(delta 33-123t), expressed in the baculovirus system, bound significantly less well to cells than did gC1(457t) and competed poorly with biotinylated gC1(457t) for binding. These results suggest that residues 33 to 123 are important for gC attachment to cells. In contrast, both the mutant and wild-type forms of gC bound to immobilized heparin, indicating that binding of these proteins to the cell surface involves more than a simple interaction with heparin. To determine that the contribution of the N-terminal region of gC is important for HSV attachment, we compared several properties of a mutant HSV-1 which contains gC lacking amino acids 33 to 123 to those of its parental virus, which contains full-length gC. The mutant bound less well to cells than the parental virus but exhibited normal growth properties.(ABSTRACT TRUNCATED AT 400 WORDS)     

Epitope mapping of cytochrome P450cam (CYP101)

OBJECTIVE: A retrospective study of women with inflammatory bowel disease, aged 16-45 years during the 20-year period 1967-1986, was carried out in North East Scotland. METHOD: Five-hundred and three women were identified: 15 patients had died from unrelated causes and 22 had emigrated, but 409 of the remaining 466 patients (88%) replied to the study questionnaire. RESULTS: Women with ulcerative colitis and Crohn's disease had normal fertility when compared with the general population of north east Scotland. However, unresolved infertility problems were more frequent in women who had undergone surgery for inflammatory bowel disease compared with those who had not (12% vs. 5% for Crohn's disease; 25% vs. 7% for ulcerative colitis). Disease relapse rates did not increase in pregnancy. CONCLUSIONS: Overall, at conception women with active disease were as likely to have a normal full-term pregnancy as those in remission. However, spontaneous abortion occurred in five (36%) pregnancies of women who had undergone previous surgery for Crohn's disease and had evidence of recurrent disease. Three of these pregnancies were associated with active disease.     

Structural integrity assessment of aging nuclear reactor pressure vessels

Irradiation embrittlement reduces both the cleavage fracture toughness and the ductile tearing toughness of reactor pressure vessel (RPV) steels. Extensive research programs have investigated the fracture behavior of heavy-section vessels containing flaws. Information obtained from that research has been used to develop regulatory guidance for evaluating the structural integrity of irradiated RPVs. Additional research programs have developed fracture analysis methods, and generated the data required for their implementation. Regulatory guidance employs fracture analysis technology to assure that adequate fracture-prevention margins for RPVs are maintained throughout the licensed operating period of nuclear power plants.     

Transforming growth factor-alpha promotes mammary tumorigenesis through selective survival and growth of secretory epithelial cells

Transforming growth factor (TGF)-alpha stimulates the growth and development of mammary epithelial cells and is implicated in the pathogenesis of human breast cancer. In this report we evaluate the consequences of overexpressing TGF-alpha in the mammary gland of transgenic mice and examine associated cellular mechanisms. When operating on a FVB/N genetic background (line MT100), TGF-alpha induced the stochastic development of mammary adenomas and adenocarcinomas f secretory epithelial origin in 64% of multiparous females. In contrast, tumors were exceedingly rare in virgin MT100 females, MT100 males, and multiparous FVB/N females. In MT100 females multiple foci of hyperplastic secretory lesions preceded the development of frank tumors; these initial lesions appeared during the involution period after the first lactation. Serial transplantation of these hyperplasias indicated an absence of proliferative immortality. Nevertheless, they gave rise to tumors at a low frequency and after a prolonged latency in virgin hosts; in multiparous hosts, tumors developed earlier and at a high incidence. The TGF-alpha transgene was highly expressed in hyperplasias and tumors but not in virgin and nonlesion-bearing tissue, suggesting that TGF-alpha overexpression provides a selective growth advantage. TGF-alpha also induced at lactation a 6.4-fold increase in DNA synthesis in MT100 epithelial cells, many of which were binucleated. MT100 mammary tissue experienced an obvious delay in involution, resulting in the postlactational survival of a significant population of unregressed secretory epithelial cells. In contrast, another line of transgenic mice on a CD-1 genetic background (MT42), in which TGF-alpha overexpression induced liver but not mammary tumors, failed to demonstrate postlactational epithelial cell survival. These data show that TGF-alpha promotes mammary tumorigenesis in multiparous MT100 mice by stimulating secretory epithelial cell proliferation during lactation and prolonging survival during involution. These points support the notion that TGF-alpha can act as a mitogen and also as a differentiation factor in mammary epithelium.     

US national survey of physician practices for the secondary and tertiary prevention of ischemic stroke. Design, service availability, and common practices

BACKGROUND AND PURPOSE: Stroke is largely a preventable disease. However, there are little data available concerning the use of stroke prevention diagnostic and treatment modalities by practicing physicians. These data are critical for the rational allocation of resources and targeting of educational efforts. The purposes of this national survey were to gather information about physicians' stroke prevention practice patterns and their attitudes and beliefs regarding secondary and tertiary stroke prevention strategies. METHODS: We conducted a national survey of stroke prevention practices among a stratified random sample of 2000 physicians drawn from the American Medical Association's Physician Masterfile. The survey focused on the availability of services and the use of diagnostic and preventive strategies for patients at elevated risk of stroke. RESULTS: Sixty-seven percent (n = 1006) of eligible physicians completed the survey. Diagnostic studies considered readily available by at least 90% of physicians included carotid ultrasonography, transthoracic echocardiography, Holter monitoring, and brain CT and MRI scans. MR angiography was perceived as being readily available by 68% and transesophageal echocardiography by 74% of respondents. Twelve percent of physicians reported cerebral arteriography and 10% reported carotid endarterectomy as not being readily available. Multiple logistic regression analyses showed that the availability of services varied with physician specialty (noninternist primary care, internal medicine, neurology, surgery), practice setting (nonmetropolitan versus small metropolitan or large metropolitan areas), and for carotid endarterectomy, region of the country (South, Central, Northeast, and West). The odds of carotid endarterectomy being reported as readily available were approximately 2.5 to 3.5 times greater for physicians practicing in the central, northeastern, and western regions compared with those practicing in the South, independent of practice setting and specialty. With regard to stroke prevention practices, 61% of physicians reported prescribing 325 mg of aspirin for stroke prevention, while 33% recommend less than 325 mg and 4% use doses of 650 mg or more. Seventy-one percent of physicians using warfarin reported monitoring anticoagulation with international normalized ratios, and 78% reported monitoring anticoagulated patients at least once a month. Fewer than 20% of physicians reported knowing the perioperative carotid endarterectomy complication rates at the hospital where they perform the operation themselves or refer patients to have the procedure done. CONCLUSIONS: Although all routine and most specialized services for secondary and tertiary stroke prevention are readily available to most physicians, variation in availability exists. The use of international normalized ratios for monitoring warfarin therapy has not yet become universal. Physician knowledge of carotid endarterectomy complication rates is generally lacking. Depending on their causes, these problems may be addressed through targeted physician education efforts and systematic changes in the way in which services are provided.     

Temporal patterns of antihypertensive medication use among older adults, 1989 through 1992. An effect of the major clinical trials on clinical practice?

OBJECTIVE: To describe the changing patterns of antihypertensive medication use in the years immediately before and after the publication of the results of three major clinical trials of the treatment of hypertension in older adults. DESIGN: In this cohort study, adults 65 years or older were examined annually on four occasions between June 1989 and May 1992, and the use of antihypertensive medications was assessed by inventory at each visit. The four visits defined the boundaries of three study periods. For each study period, participants receiving antihypertensive therapy were either continuous users (n = 1667, 1643, and 1605, respectively) or starters (n = 157, 142, 120) of hypertensive therapy. The large clinical trials that convincingly proved the efficacy and safety of low-dose diuretic therapy in older adults were published during the latter parts of period 2 and the early parts of period 3. RESULTS: Among starters, the proportion initiating therapy on diuretics increased from 35.9% in period 2 to 47.5% in period 3, significantly so among women (P = .04). The proportions initiating other drugs displayed no significant trends. Among continuous users, the use of diuretics, beta-blockers, and vasodilators generally decreased over the 3-year period, while the use of calcium channel blockers and angiotensin-converting enzyme inhibitors increased significantly in each of the three periods (P < .05). The decline of 2.7% in the prevalence of diuretic use in period 1 abated during period 2 (1.8% decline), and it slowed significantly (P = .03) to almost a complete halt during period 3 (0.2% decline). The rate of increase in the use of calcium channel blockers slowed significantly (P = .01) between period 1 (+6.7%) and period 3 (+2.8%). CONCLUSIONS: Although other factors such as cost may have been important, the temporal trends in antihypertensive drug therapy coincided in time with and may have reflected in part the influence of the major clinical trials on the patterns of clinical practice.