423 research outputs found

    The C-terminal tail of the gp41 transmembrane envelope glycoprotein of HIV-1 clades A, B, C, and D may exist in two conformations: an analysis of sequence, structure, and function

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    AbstractIn addition to the major ectodomain, the gp41 transmembrane glycoprotein of HIV-1 is now known to have a minor ectodomain that is part of the long C-terminal tail. Both ectodomains are highly antigenic, carry neutralizing and non-neutralizing epitopes, and are involved in virus-mediated fusion activity. However, data have so far been biologically based, and derived solely from T cell line-adapted (TCLA), B clade viruses. Here we have carried out sequence and theoretically based structural analyses of 357 gp41 C-terminal sequences of mainly primary isolates of HIV-1 clades A, B, C, and D. Data show that all these viruses have the potential to form a tail loop structure (the minor ectodomain) supported by three, ÎČ-sheet, membrane-spanning domains (MSDs). This means that the first (N-terminal) tyrosine-based sorting signal of the gp41 tail is situated outside the cell membrane and is non-functional, and that gp41 that reaches the cell surface may be recycled back into the cytoplasm through the activity of the second tyrosine-sorting signal. However, we suggest that only a minority of cell-associated gp41 molecules – those destined for incorporation into virions – has 3 MSDs and the minor ectodomain. Most intracellular gp41 has the conventional single MSD, no minor ectodomain, a functional first tyrosine-based sorting signal, and in line with current thinking is degraded intracellularly. The gp41 structural diversity suggested here can be viewed as an evolutionary strategy to minimize HIV-1 envelope glycoprotein expression on the cell surface, and hence possible cytotoxicity and immune attack on the infected cell

    The Diplopoda (Myriapoda) of Madagascar described by Henri de Saussure and Leo Zehntner

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    uploaded by Plazi for Revue Suisse de Zoologi

    Proceedings of the 40th Annual Meeting, Southern Soybean Disease Workers (March 13-14, 2013, Pensacola Beach, Florida)

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    Contents Southern United States Soybean Disease Loss Estimates for 2012. Compiled by SR Koenning Update on Detection and Management of QoI Fungicide Resistant Cercospora sojina, the Causal Agent of Frogeye Leaf Spot in Soybean. C Bradley, G Zhang, V Chapara, R Ming, F Zeng, H Young Kelly, and M Newman Identification of Soybean Genotypes to Cercopsora sojina by Field Screening and Molecular Markers. A Mengistu and R Mian Soybean Vein Necrosis Virus. D Hershman Single Applications of Triazole Fungicides at R1 for Management of Cercospora Leaf Blight and Rust in Soybean. RW Schneider, CL Robertson, BM Ward, and EC Silva Observations on soybean rust management in Alabama in 2012. EJ Sikora, D Delaney, and M Delaney Graduate student paper competition (Clayton Hollier, moderator) Logical Areas of Collection: A Precision Concept for Management of Rhizoctonia solani AG1-IA. TN Spurlock, CS Rothrock, and WS Monfort Screening of Soybean Recombinant Inbred Lines against Phakopsora pachyrhizi. M Ganiger, DR Walker, and ZY Chen Effects of Minor Element Nutrition on Cercospora Leaf Blight of Soybean. BM Ward, CL Robertson, RW Schneider, and EC Silva Sensitivity of Cercospora kikuchii Populations to Methyl Benzimidazole, Carbamate, Quinone Outside Inhibitor, and Demethylation Inhibitor Fungicides. P Price, MA Purvis, CL Robertson, GB Padgett, and RW Schneider Effect of Foliar Application of Micronutrients on Severity of Rust in Soybean. EC Silva, BM Ward, CL Robertson, and RW Schneider Southern Soybean Disease Workers paper session (Tom Allen, moderator) History of Reniform Nematode in the South. RT Robbins Role of Seed Quality, Planting Date, and Seed Treatment on Soybean Stand and Yield. JC Rupe, R Holland, A Steger, S Goeke, EE Gbur, WJ Ross, M Wyss, J McCoy, and R Cingolani Screening Soybean Germplasm and Commercial Varieties for Resistance to Phomopsis Seed Decay: Results from 2012 Trials. S Li, G Sciumbato, P Chen, S Sun, J Rupe, R Holland, and A Steger A Novel Seed Treatment with Activity against SDS in Soybeans. C Graham Adenosylhomocysteinase (AHCY) is essential for Virulence of Cercospora kikuchii in soybeans. AK Chanda, RW Schneider, and Z-Y Chen Fungicide Timing Strategies: Targeting Yield Enhancement in Mississippi Soybean. TW Allen, D Cook, A Catchot, J Gore, and N Buehring Update from the United Soybean Board. K Whiting Industry Pest Information Platform for Extension and Education (iPiPE). S Isard, R Magarey, J Golod, and J Russo Proceedings of the Southern Soybean Disease Workers are published annually by the Southern Soybean Disease Workers. Text, references, figures, and tables are reproduced as they were submitted by authors. The opinions expressed by the participants at this conference are their own and do not necessarily represent those of the Southern Soybean Workers. Mention of a trademark or proprietary products in this publication does not constitute a guarantee, warranty, or endorsement of that product by the Southern Soybean Disease Workers

    Acyclovir suppression to prevent recurrent genital herpes at delivery.

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    OBJECTIVE: To determine if suppressive acyclovir near term decreased the frequency of clinical recurrences at delivery in women with recurrent genital herpes simplex virus (HSV) infection. METHODS: We conducted a prospective, double-blind, randomized trial in 234 women with recurrent genital herpes. Women with genital infection of any frequency were enrolled. Patients received either suppressive oral acyclovir 400 mg three times daily or an identical placebo after 36 weeks' gestation. Clinical lesions were identified, and HSV cultures were obtained at delivery. The frequencies of clinical and subclinical HSV recurrences at delivery were evaluated. RESULTS: Six percent of patients treated with acyclovir, and 14% of patients treated with placebo had clinical HSV at delivery (p = 0.046). No patients in the acyclovir group had positive HSV cultures, compared with 6% of placebo-treated patients (p = 0.029). There was no significant difference in subclinical HSV shedding in the acyclovir group (0%) compared with the placebo-treated group (3%) (p = 0.102). CONCLUSIONS: Suppressive acyclovir therapy significantly decreased the incidence of clinical genital herpes and the overall incidence of HSV excretion at delivery in patients with previous herpes infection

    Acyclovir Suppression to Prevent Clinical Recurrences at Delivery After First Episode Genital Herpes in Pregnancy: An Open-Label Trial

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    Objective: To continue evaluation of the use of acyclovir suppression in late pregnancy after first episode genital herpes simplex virus (HSV) infection, using an open-label study design. Methods: Ninety-six women diagnosed with genital herpes for the first time in the index pregnancy were prescribed suppressive acyclovir 400 mg orally three times daily from 36 weeks until delivery in an open-label fashion. Herpes cultures were obtained when patients presented for delivery. Vaginal delivery was permitted if no clinical recurrence was present; otherwise a Cesarean delivery was performed. NeonatalHSV cultures were obtained and infants were followed clinically. Rates of clinical and asymptomatic genital herpes recurrences and Cesarean delivery for genital herpes were measured, and 95% confidence intervals were calculated. Results: In 82 patients (85%) compliant with therapy, only 1% had clinical HSV recurrences at delivery. In an intent to treat analysis of the entire cohort, 4% had clinical recurrences (compared with 18–37% in historical controls). Asymptomatic shedding occurred in 1% of women without lesions at delivery. Two of the four clinical recurrences were HSV-culture positive. No significant maternal or fetal side-effects were observed. Conclusions: In clinical practice the majority of patients are compliant with acyclovir suppression at term. The therapy appears to be effective at reducing clinical recurrences after a first episode of genital herpes complicating a pregnancy

    Predicting iliac limb occlusions after bifurcated aortic stent grafting: Anatomic and device-related causes

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    AbstractObjective: Graft limb occlusion may complicate endovascular abdominal aortic aneurysm repair. The precise etiologic factors that contribute to the development of these graft limb thromboses have not been defined. We evaluated our experience with bifurcated aortic endografts to determine factors that may predict subsequent limb thrombosis. The management of the thrombosed limbs and the results after treatment were also investigated. Methods: During a 4-year period, 351 patients with aortic aneurysms underwent treatment with bifurcated endografts (702 graft limbs at risk). These 351 bifurcated devices included AneuRx (Medtronic, Minneapolis, Minn; n = 35), Ancure (Guidant, Menlo Park, Calif; n = 8), Gore (W.L. Gore & Associates, Sunnyvale, Calif; n = 25), Talent (World Medical, Sunrise, Fla; n = 255), Teramed (Teramed, Minneapolis, Minn; n = 10), and Vanguard (Boston Scientific Vascular, Natick, Mass; n = 18). Details regarding the type of device, mechanism of deployment, and aortoiliac artery anatomy were collected prospectively and analyzed. Graft limbs were analyzed for diameter, use of additional endograft iliac extensions, deployment in the external iliac artery, and endograft to vessel oversizing. Follow-up included physical examination, duplex ultrasonography, and spiral computed tomographic scans at 1 month, 6 months, and 12 months and annually thereafter. The follow-up period ranged from 2 to 54 months, with a mean follow-up period of 20 months. Results: Twenty-six of 702 limbs (3.7%) had an occlusion develop. The risk of limb thrombosis was associated with a smaller limb diameter. Mean graft limb diameter was 14 mm in the occluded population, and patent limbs had a mean diameter of 16 mm. Thrombosis occurred in 16 of 291 limbs (5.5%) that were 14 mm or less and in 10 of 411 limbs (2.4%) that were greater than 14 mm (P = .03). Extension of a graft to the external iliac artery was performed in 96 of the 702 limbs. Eight of these 96 limbs (8.3%) had thrombosis develop as compared with 18 of 606 (3.0%) that extended to the common iliac artery (P = .01). No significant association was present between limb thrombosis and the contralateral or ipsilateral side of a device, the configuration of the iliac graft limb end (closed web, open web, or bare spring), or the degree of iliac graft limb oversizing. AneuRx, Ancure, Vanguard, and Talent grafts each sustained limb occlusions, with no occlusions seen among the Gore and Teramed devices. No significant increased risk of graft limb thrombosis was observed in unsupported grafts (1/16; 6.3%) versus supported grafts (25/686; 3.6%; P = not significant). Thromboses occurred between 1 day and 23 months after surgery. Thirteen of the 26 thromboses (50%) occurred within 30 days of surgery. Presenting symptoms were mild to moderate claudication in eight patients (30.8%), severe claudication in 16 patient (61.5%), and paresthesia and rest pain in two patients (7.7%). Eighteen of 26 patients (69.2%) eventually needed intervention to reestablish flow to the occluded limb, including thrombolysis and stenting in two patients (7.7%), axillary femoral bypass in one patient (3.8%), femoral-femoral bypass in 13 patients (50.0%), and axillary-bifemoral bypass in two patients (7.7%). All patients with mild to moderate symptoms under observation had improvement in symptoms with no further interventions necessary. All revascularizations were successful in relieving symptoms. Conclusion: Graft limb occlusion is a recognized complication of endovascular treatment of abdominal aortic aneurysms that may be associated with smaller graft limb diameter and extension to the external iliac artery. Occlusions usually necessitate additional intervention for resolution of ischemic symptoms. The use of small diameter grafts should be avoided when possible to reduce the risk of graft limb occlusions. (J Vasc Surg 2002;36:679-84.

    A model for fresh produce shelf-space allocation and inventory management with freshness-condition-dependent demand

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    Asignificant amount of work has investigated inventory control problems associated with fresh produce. Much of this work has considered deteriorating inventory control with many models having been proposed for various situations. However, no researchers have specifically studied fresh produce, which has its own special characteristics. Most research categorizes fresh produce into more general deteriorating categories with random lifetimes and nondecaying utilities. However, this classification is not reasonable or practical because the freshness of an item usually plays an important role in influencing the demand for the produce. In this paper, a single-period inventory and shelf-space allocation model is proposed for fresh produce. These items usually have a very short lifetime. The demand rate is assumed to be deterministic and dependent on both the displayed inventory (the number of facings of items on the shelves) and the items' freshness condition (which decreases over time). Several problem instances of different sizes are provided and solved by a modified generalized reduced gradient algorithm

    Canonical theory of spherically symmetric spacetimes with cross-streaming null dusts

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    The Hamiltonian dynamics of two-component spherically symmetric null dust is studied with regard to the quantum theory of gravitational collapse. The components--the ingoing and outgoing dusts--are assumed to interact only through gravitation. Different kinds of singularities, naked or "clothed", that can form during collapse processes are described. The general canonical formulation of the one-component null-dust dynamics by Bicak and Kuchar is restricted to the spherically symmetric case and used to construct an action for the two components. The transformation from a metric variable to the quasilocal mass is shown to simplify the mathematics. The action is reduced by a choice of gauge and the corresponding true Hamiltonian is written down. Asymptotic coordinates and energy densities of dust shells are shown to form a complete set of Dirac observables. The action of the asymptotic time translation on the observables is defined but it has been calculated explicitly only in the case of one-component dust (Vaidya metric).Comment: 15 pages, 3 figures, submitted to Phys. Rev.

    Toward a Quantization of Null Dust Collapse

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    Spherically symmetric, null dust clouds, like their time-like counterparts, may collapse classically into black holes or naked singularities depending on their initial conditions. We consider the Hamiltonian dynamics of the collapse of an arbitrary distribution of null dust, expressed in terms of the physical radius, RR, the null coordinates, VV for a collapsing cloud or UU for an expanding cloud, the mass function, mm, of the null matter, and their conjugate momenta. This description is obtained from the ADM description by a Kucha\v{r}-type canonical transformation. The constraints are linear in the canonical momenta and Dirac's constraint quantization program is implemented. Explicit solutions the constraints are obtained for both expanding and contracting null dust clouds with arbitrary mass functions.Comment: 10 pages, 2 figures (eps), RevTeX4. The last two sections have been revised and corrected. To appear in Phys. Rev.
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