Absence of detectable human herpesvirus 8 in the semen of human immunodeficiency virus-infected men without Kaposi's sarcoma

The prevalence of human herpesvirus 8 (HHV-8)/Kaposi's sarcoma (KS)-associated herpesvirus was investigated in the semen of 99 human immunodeficiency virus (HIV)-infected men (median CD4 cell count, 357/mm3) by use of a polymerase chain reaction (PCR) assay capable of detecting <10 copies of HHV-8 DNA. Of the subjects, 95 (96%) self-identified as men who have sex with men (MSM), and 3 had a history of clinical KS. Seminal cell specimens were negative for HHV-8 in 98 subjects. None of the 26 without KS (27.1% of 96 tested) who were seropositive for HHV-8 by IFA for latency-associated nuclear antigens had HHV-8 detected in their semen. The only subject with any evidence for seminal HHV-8 DNA was seropositive for HHV-8 and had active KS. HHV-8 was detected in 10 (10.4%) of 96 peripheral blood mononuclear cell specimens. The prevalence of HHV-8 DNA by PCR in semen of HIV-infected MSM without KS is low.     

Testing a mathematical model for initial chemical reaction fouling using a dilute protein solution

A 1 wt% lysozyme solution was used as a model fluid to test a previously formulated mathematical model for the initial chemical reaction fouling rate of a heat transfer surface. The experimental results showed that, at a given wall temperature, a maximum initial fouling rate existed over a range of fluid velocities. The maximum rate and the fluid velocity at which it occurred both increased as the wall temperature increased. These observations were consistent with the model. Quantitatively, the average absolute percent deviation between the experimental results and the optimum model predictions was 23,3%. The decrease in initial fouling rate with increasing velocity at high fluid velocities was even greater than predicted by the model.     

Structural modeling of the pro-ocytocin-neurophysin precursor

The hormonal precursor pro-ocytocin-neurophysin is activated by selectivecleavage at Arg2-Ala13, producing mature ocytocin and neurophysin. Tounderstand the cleavage mechanism better, and in particular the recognitionof the cleavage site, it is necessary to characterize the three-dimensionalstructure of the precursor molecule. Here we combine a variety ofexperimental data with molecular modeling and dynamics calculations toderive possible precursor conformations. In the models obtained, theN-terminus of the precursor, corresponding to the ocytocin segment, ishydrogen bonded in a pocket of the neurophysin moiety in a similar mannerto a crystallographically obtained non-covalent complex between the twomolecules. The calculations suggest that although the ocytocin segment isrelatively flexible, it adopts a stable, broad loop structure in thevicinity of the cleavage region, which may constitute the structuralelement recognized by the cleaving enzyme. The calculations also suggest apossible widening of the distance between the two neurophysin domains inthe precursor relative to that in the non-covalent neurophysin- ocytocincomplex.     

Interactions between immunoglobulin-like and catalytic modules in Clostridium thermocellum cellulosomal cellobiohydrolase CbhA

Cellobiohydrolase CbhA from Clostridium thermocellum cellulosome is a multi-modular protein composed starting from the N-terminus of a carbohydrate-binding module (CBM) of family 4, an immunoglobulin(Ig)-like module, a catalytic module of family 9 glycoside hydrolases (GH9), X1(1) and X1(2) modules, a CBM of family 3 and a dockerin module. Deletion of the Ig-like module from the Ig-GH9 construct results in complete inactivation of the GH9 module. The crystal structure of the Ig-GH9 module pair reveals the existence of an extensive module interface composed of over 40 amino acid residues of both modules and maintained through a large number of hydrophilic and hydrophobic interactions. To investigate the importance of these interactions between the two modules, we compared the secondary and tertiary structures and thermostabilities of the individual Ig-like and GH9 modules and the Ig-GH9 module pair using both circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC). Thr230, Asp262 and Asp264 of the Ig-like module are located in the module interface of the Ig-GH9 module pair and are suggested to be important in 'communication' between the modules. These residues were mutated to alanyl residues. The structure, stability and catalytic properties of the native Ig-GH9 and its D264A and T230A/D262A mutants were compared. The results indicate that despite being able to fold relatively independently, the Ig-like and GH9 modules interact and these interactions affect the final fold and stability of each module. Mutations of one or two amino acid residues lead to destabilization and change of the mechanism of thermal unfolding of the polypeptides. The enzymatic properties of native Ig-GH9, D264A and T230A/D262A mutants are similar. The results indicate that inactivation of the GH9 module occurs as a result of multiple structural disturbances finally affecting the topology of the catalytic center.     

The unanticipated difficult airway with recommendations for management

PURPOSE: To review the current literature and generate recommendations on the role of newer technology in the management of the unanticipated difficult airway. METHODS: A literature search using key words and filters of English language and English abstracted publications from 1990-96 contained in the Medline, Current Contents and Biological Abstracts databases was carried out. The literature was reviewed and condensed and a series of evidence-based recommendations were evolved. CONCLUSIONS: The unanticipated difficult airway occurs with a low but consistent incidence in anaesthesia practice. Difficult direct laryngoscopy occurs in 1.5-8.5% of general anaesthetics and difficult intubation occurs with a similar incidence. Failed intubation occurs in 0.13-0.3% general anaesthetics. Current techniques for predicting difficulty with laryngoscopy and intubation are sensitive, non-specific and have a low positive predictive value. Assessment techniques which utilize multiple characteristics to derive a risk factor tend to be more accurate predictors. Devices such as the laryngeal mask, lighted stylet and rigid fibreoptic laryngoscopes, in the setting of unanticipated difficult airway, are effective in establishing a patient airway, may reduce morbidity and are occasionally lifesaving. Evidence supports their use in this setting as either alternatives to facemask and bag ventilation, when it is inadequate to support oxygenation, or to the direct laryngoscope, when tracheal intubation has failed. Specifically, the laryngeal mask and Combitube have proved to be effective in establishing and maintaining a patent airway in "cannot ventilate" situations. The lighted stylet and Bullard (rigid) fibreoptic scope are effective in many instances where the direct laryngoscope has failed to facilitate tracheal intubation. The data also support integration of these devices into strategies to manage difficult airway as the new standard of care. Training programmes should ensure graduate physicians are trained in the use of these alternatives. Continuing medical education courses should allow physicians in practice the opportunity to train with these alternative devices.     

Differential responses in anterior pituitary luteinizing hormone (LH) content and LH beta- and alpha-subunit mRNA, and plasma concentrations of LH and testosterone, in bulls treated with the LH-releasing hormone agonist deslorelin

Tooth loss diminishes oral function and quality of life, and national health targets aim to reduce population levels of tooth loss. OBJECTIVES: The purpose of this study was to determine tooth loss incidence and predictors of tooth loss among older adults in South Australia. METHODS: Data were obtained from a cohort study of a stratified random sample of community-dwelling dentate people aged 60+ years. Interviews and oral examinations were conducted among 911 individuals at baseline and among 693 of them (76.1%) 2 years later. Incidence rates and relative risks were calculated for population subgroups and multivariate logistic regression was used to construct risk prediction models. A method was developed to calculate 95% confidence intervals (95% CI) for relative risks (RR) from logistic regression models using a Taylor series approximation. RESULTS: Some 19.5% (95% CI = 15.4-23.6%) of people lost one or more teeth during the 2 years. Men, people with a recent extraction, people who brushed their teeth infrequently, smokers and people born outside Australia had significantly (P < 0.05) greater risk of tooth loss. Baseline clinical predictors of tooth loss included more missing teeth, retained roots, decayed root surfaces, periodontal pockets and periodontal recession. In a multivariate model that controlled for baseline clinical predictors, former smokers (RR = 2.55, 95% CI = 1.48-4.40) and current smokers (RR = 2.06, 95% CI = 0.92-4.62) had similarly elevated risks of tooth loss compared with non-smokers. CONCLUSIONS: The findings from this population suggest that a history of smoking contributes to tooth loss through mechanisms in addition to clinical disease processes alone.     

Fast, sensitive magnetic-field sensors based on the Faraday effectin YIG

Magnetic-field sensors based on the Faraday effect in ferrimagnetic iron garnets are investigated in terms of their sensitivity, speed, and directionality. Signal-to-noise measurements at 80 Hz on small (typically 5-mm-diameter×3-mm-long) samples of yttrium iron garnet (YIG) yield noise equivalent magnetic fields of 10 nT/√Hz. Frequency-response measurements exhibit virtually flat response to approximately 700 MHz     

Quantitative probing the interfacial structure of TPO/CPO blends by transmission electron microscopy via EDX

High-resolution scanning transmission electron microscope (HR STEM) measurements were performed on a thermoplastic polyolefin (TPO) substrate coated with chlorinated polyolefin (CPO). This CPO was a maleated chlorinated polypropylene containing 21.8 wt% Cl. The TPO investigated was a blend of high-modulus isotactic polypropylene (iPP) with a crystalline ethylene-butene copolymer (EB9) containing 9 wt% butene. For these injection-molded samples, examined ca. 10 mm from the mold gate, a stratified morphology found at TPO surface consisting of thin fibers of EB9 trapped in a transcrystalline iPP matrix, with crystalline lamellae propagating from the matrix across the EB9 domains. This structure was unperturbed when the plaques were coated (from tetrahydrofuran solution) with a 5 μm layer of CPO, but underwent changes of increasing severity when subjected either to a dry bake at 120 °C or annealing at 120 °C in the presence of xylene vapor. The interfacial structure between the CPO and the TPO was probed by TEM with energy dispersive X-ray imaging (EDX). The elemental chlorine across the interface gave good fits to a tan h function, and the interface thickness increased from 23 ± 2 nm to 28 ± 1 nm upon annealing at 120 °C for 30 min. After annealing in the presence of xylene vapor, this value increased to 50 ± 4 nm. As reference points, we determined an interface thickness of 29 ± 3 nm for the CPO-EB interface and 15 ± 2 nm for the interface between CPO and iPP.