Genotype D amongst injection drug users with acute hepatitis B virus infection in British Columbia

The eight genotypes of hepatitis B virus (HBV) exhibit distinct geographical distributions. This study identified HBV genotypes and transmission modes associated with acute infection in British Columbia (BC), Canada, from 2001 to 2005. Seventy cases of acute HBV in BC were identified from laboratory reports using a standardized case definition. Interviews for risk factors and hepatitis history were conducted for each case. HBV genotypes were determined by BLAST comparison analysis of the surface (S) or preS gene sequence. To illustrate the distribution of genotypes identified amongst acute cases in BC, an annotated map was produced showing the global occurrence of HBV genotypes. The majority of acute HBV cases occurred in Caucasian, Canadian-born males, with 30% of cases reporting injection drug use (IDU) and 21% reporting incarceration. The most common genotype observed was genotype D (62.9%), followed by genotypes A (18.6%), C (11.4%), B (4.3%), and E (1.4%). A significant association was observed between Genotype D and IDU (P = 0.0025) and previous incarceration (P = 0.0067). Phylogenetic analysis of the S gene sequence demonstrated identical or high genetic relatedness amongst genotype D viral strains (86% sub-genotype D3), thus verifying transmission clustering amongst BC injection drug users. The association between acute HBV genotype and reported transmission modes has not been previously described in North America. Tracking of genotypes can help identify disease transmission patterns and target at-risk populations for preventive immunization.

Effect of high-fat diet on glucose homeostasis and gene expression in glucokinase knockout mice

AIM

We have generated a heterozygous glucokinase knockout mouse (gk(del/wt)), upon which we investigated the effect of high-fat diet (HFD) with respect to metabolic control and both hepatic and beta-cell gene expression. We also investigated the in vitro efficacy of a glucokinase activator (GKA) on glucose-stimulated insulin secretion (GSIS) in gk(del/wt)mouse islets.

METHODS

Male gk(del/wt)and gk(wt/wt)mice were grouped (n = 8-10) at 10 weeks of age and fed HFD or chow diet (CD) for 10 weeks. Multiple parameters including blood glucose, plasma insulin and glucose tolerance were assessed. Further animal groups were used for in vitro GSIS and islet and liver gene expression analysis.

RESULTS AND CONCLUSIONS

gk(del/wt)mice showed early-onset persistent hyperglycaemia, raised glycated haemoglobin levels, impaired GSIS and glucose tolerance but no change in plasma cholesterol, non-esterified fatty acids or triglyceride levels. After HFD feeding, insulin levels of gk(del/wt)mice were less than half that of gk(wt/wt)mice, although they were equivalent to gk(wt/wt)mice on CD. While gk(wt/wt)mice maintained moderate hyperglycaemia, gk(del/wt)mice became overtly diabetic, with worsened glucose tolerance. A GKA (GKA50) increased GSIS, at 10 mM glucose, in gk(del/wt)mice to an extent at least as great as that seen in gk(wt/wt)mice on both CD and HFD. gk(del/wt)mice showed only a small number of changes in gene expression compared with gk(wt/wt)mice. We propose the high fat-fed gk(del/wt)mouse as a model of type 2 diabetes and report retained efficacy of a GKA on in vitro GSIS.

[Pathomechanisms for aging of retinal pigment epithelium (RPE) and prophylactic therapy options in regard to AMD]

An intact retinal pigment epithelium (RPE) represents an essential condition for the visual process. This post-mitotic RPE monolayer combines different functions such as degradation of photoreceptor outer segments, vitamin A cycle, support of retinal metabolism and maintenance of the outer blood-retina barrier. As a consequence of excessive metabolism, high oxygen levels, exposition to light of short wave length and ensuing radical formation, the RPE is highly dependent on protective systems. In spite of differentiated defence mechanisms, aging processes cause cumulative RPE damage, representing a major component of age-related macular degeneration (AMD), the leading cause of irreversible severe vision loss in people over 50 years old. A better understanding of the underlying pathophysiology will help to develop new prophylactic options which is becoming more and more important with increasing life expectancy.

Preparation and Properties of Nanocomposites from Pristine and Modified SWCNTs of Comparable Average Aspect Ratios

Low color, flexible, space-durable polyimide films with inherent and robust electrical conductivity to dissipate electrostatic charge (ESC) have been under investigation as part of a materials development activity for future NASA space missions. The use of single-walled carbon nanotubes (SWCNTs) is one means of achieving this goal. Even though the concentration of SWCNTs needed to achieve ESC dissipation is typically low, it is dependent upon purity, size, dispersion and functionalization. In this study, SWCNTs prepared by the electric arc discharge method were used to synthesize nanocomposites using the LaRCTM CP2 backbone as the matrix. Pristine and functionalized SWCNTs were mixed with an alkoxysilane terminated amide acid of LaRC TM CP2 and the soluble imide form of the polymer and the resultant nanocomposites evaluated for mechanical, thermal and electrical properties. Due to the preparative conditions for the pristine and functionalized SWCNTs, the average aspect ratio for both was comparable. This permitted the assessment of SWCNT functionalization with respect to various interactions (e.g. van der Waals, hydrogen bonding, covalent bond formation, etc.) with the matrix and the macroscopic effects upon nanocomposite properties. The results of the study are described.

The use of consensus guidelines for management of cytomegalovirus infection in renal transplantation

Cytomegalovirus (CMV) infection imposes a significant economic burden on susceptible patients after renal transplantation. Our study was conducted to determine the prediction, probability, consequences, and treatment costs of CMV infection under Canadian consensus guidelines in 270 sequential transplant patients. Transplant patients from donors positive (D(+)) for CMV into recipients negative (R(-)) for CMV received antiviral prophylaxis for 14 weeks and all but donor negative (D(-))/R(-) patients were monitored weekly for the CMVpp65 marker expression. Marker-positive patients and patients with CMV infection or disease received antiviral treatment. Within the first 6 months, 27% of the 270 patients tested had incidences of asymptomatic CMV infection, while 9% had CMV syndrome or disease. Only 1% of patients had infection after 6 months. The CMVpp65 marker levels were significantly greater in patients with syndrome or disease; but post-test probabilities and predictive value of the marker assay were low. Mean direct costs for care were $2256 and ranged from $927 for D(-)/R(-) patients to $7069 in the D(+)/R(-) patients. Extension of antiviral prophylaxis to D(+) or D(+)/R(+) patients significantly increased the estimated mean costs for an absolute reduction to 4% in CMV syndrome or disease. Our studies show that current guidelines for treatment enable effective control of CMV infection; however, alternative strategies have different economic impact.

Bevacizumab wirkt nicht toxisch auf Zellen des menschlichen Auge

OBJECTIVE

Intravitreal anti-vascular endothelial growth factor (VEGF) treatment with bevacizumab (Avastin) has emerged as a promising therapy for the treatment of choroidal neovascularisation in age-related macular degeneration. Intravitreal administration of bevacizumab is "off-label," and only very limited data regarding short-term toxicity exist. Therefore, we investigated the safety of different doses of bevacizumab on the anterior- and posterior-segment cells of the human eye.

METHODS

Primary human retinal pigment epithelium (RPE) cells, human optic nerve head astrocytes (ONHA), human trabecular meshwork cells (TMC), and cornea buttons not suitable for transplantation were treated with bevacizumab (25 microg/ml, 250 microg/ml, and 2,500 microg/ml) for 48 h, corresponding to 0.1x, 1x, and 10x the dosage used intravitreally. Bevacizumab-related toxicity was evaluated by a colorimetric test (MTT) measuring inhibition of RPE, ONHA, and TMC cell proliferation. Additionally, cell viability was quantified by live/dead fluorescence assay. Corneal endothelium was quantified by phase-contrast microscopy.

RESULTS

Bevacizumab showed adverse effects on primary RPE cell proliferation as well as on cell viability at a concentration of 2,500 microg/ml. The lower concentrations of 25 microg/ml and 250 microg/ml had no influence on RPE cell proliferation or cell viability. There was no toxicity for any investigated concentration on human ONHA, TMC, or corneal endothelium.

CONCLUSION

In this study, a 10-fold concentration (compared with common clinical use) of the VEGF-blocking antibody bevacizumab had toxic effects on primary RPE. There was no toxicity for lower concentrations or toxicity to other cell types of the anterior and posterior segments. Therefore, the clinical use of bevacizumab at concentrations of 1-1.25 mg intravitreally seems to be safe.

The clock gene Per2 links the circadian system to the estrogen receptor

Circadian rhythms regulate diverse physiological processes including homeostatic functions of steroid hormones and their receptors. Estrogen receptor-alpha (ERalpha) is essential for normal mammary gland physiology and is a prognostic marker for the treatment of breast cancer. We report that Per2, a core clock gene, links the circadian cycle to the ERalpha signaling network. Binding of enhances ERalpha degradation, while suppression of Per2 levels leads to ERalpha stabilization. In turn, Per2 itself is estrogen inducible in these cells, suggesting a feedback mechanism to attenuate stimulation by estrogen. In addition, overexpression of Per2 in breast cancer cells leads to significant growth inhibition, loss of clonogenic ability and apoptosis. Taken together, these results further support a critical role for peripheral circadian regulation in tissue homeostasis and suggest a novel role for clock genes in estrogen receptor-positive breast cancer.

Multiscale carbon nanotube-carbon fiber reinforcement for advanced epoxy composites

We report an approach to the development of advanced structural composites based on engineered multiscale carbon nanotube-carbon fiber reinforcement. Electrophoresis was utilized for the selective deposition of multi- and single-walled carbon nanotubes (CNTs) on woven carbon fabric. The CNT-coated carbon fabric panels were subsequently infiltrated with epoxy resin using vacuum-assisted resin transfer molding (VARTM) to fabricate multiscale hybrid composites in which the nanotubes were completely integrated into the fiber bundles and reinforced the matrix-rich regions. The carbon nanotube/carbon fabric/epoxy composites showed approximately 30% enhancement of the interlaminar shear strength as compared to that of carbon fiber/epoxy composites without carbon nanotubes and demonstrate significantly improved out-of-plane electrical conductivity.

Adherence to combined Lamivudine+Zidovudine versus individual components: A community-based retrospective medicaid claims analysis

Adherence to a fixed dose combination of dual nucleoside antiretroviral therapy was compared between human immunodeficiency virus (HIV)-infected patients newly started on a fixed dosed combination of lamivudine (3TC) 150 mg/zidovudine (ZDV) 300 mg versus its components taken as separate pills. Medicaid pharmacy claims data were used for analyses. To examine the association between treatment group and medication adherence, three types of multivariate regressions were employed. In addition, all regressions were conducted for the whole population using data from 1995 to 2001 as well as a subpopulation, which excluded data prior to September 1997. Model covariates included patient characteristics, healthcare utilization, and non-study antiretroviral therapy use. The likelihood of > or =95% adherence among patients on combination therapy was three times greater than patients taking 3TC and ZDV in separate pills. Also, combination therapy patients had on average 1.4 fewer adherence failures per year of follow-up and nearly double the time to adherence failure compared to the separate pills group. Consistency among study results suggests that fixed dose combination therapies such as lamivudine (3TC) 150 mg/ zidovudine (ZDV) 300 mg should be considered when prescribing HIV treatment that includes an appropriate dual nucleoside.

Biomarkers in transplantation: Prospective, blinded measurement of predictive value for the flow cytometry crossmatch after negative antiglobulin crossmatch in kidney transplantation

This prospective, blinded observational study was conducted to measure the predictive value the of flow cytometric crossmatch for biopsy-proven acute rejection, graft loss, or death following kidney transplantation. Patients were selected for renal transplantation on the basis of a conventional antihuman globulin cytotoxic T-cell crossmatch. Flow crossmatch was performed simultaneously, but the results were not disclosed to the transplant team. A total of 257 kidney transplant recipients were enrolled in the study; 78 patients experienced biopsy-proven rejection in the first post-transplant year, and 41 patients lost their graft or died during the period of follow-up (mean: 2046 days). Kaplan-Meier estimates of rejection, graft loss, or patient death did not differ between subjects with a positive or negative flow crossmatch. Cox analyses showed no influence of the flow crossmatch on the risk of biopsy-proven acute rejection (P = 0.987). The sensitivity and specificity of the flow crossmatch for prediction of biopsy-proven rejection were 0.128 and 0.883, and the positive and negative post-test probabilities were 0.323 and 0.301, respectively. The magnitude of the channel shift did not influence the multivariate Cox regression model. The area under the receiver operating characteristic curve of the flow crossmatch was 0.483 (P = 0.71) and 0.572 (P = 0.38), respectively for the living and cadaver transplant recipients, indicating no discriminative value in this study population. Flow crossmatch appears to have no significant incremental value in predicting biopsy-proven acute rejection, graft loss, or death following kidney transplantation in patients who have a negative antihuman globulin cytotoxic T-cell crossmatch against their donor.

Tadalafil dosed once a day in men with erectile dysfunction: a randomized, double-blind, placebo-controlled study in the US

The efficacy and safety of tadalafil, dosed once a day for the treatment of erectile dysfunction, was assessed in a randomized, double-blind, placebo-controlled, parallel-design study at 15 US centers. Following a 4-week treatment-free run-in period, patients (>or=18 years of age) were randomly assigned to 24 weeks treatment with tadalafil 2.5 mg, tadalafil 5 mg or placebo. Primary efficacy endpoints were change at 24 weeks in International Index of Erectile Function Erectile Function (EF) Domain score and mean per-patient percentage 'yes' responses to Sexual Encounter Profile diary questions 2 and 3. Tadalafil significantly improved erectile function compared with placebo for all three co-primary efficacy endpoints. Few patients discontinued because of adverse events (2.1%, placebo; 6.3%, tadalafil 2.5 mg; 4.1%, tadalafil 5 mg). Common treatment-emergent adverse events (>or=5%) were nasopharyngitis, influenza, viral gastroenteritis and back pain. Tadalafil 2.5 mg and 5 mg, dosed once a day for 24 weeks, was well tolerated and significantly improved erectile function.

A three-part study to investigate the incidence and potential etiologies of tadalafil-associated back pain or myalgia

The potential mechanisms underlying back pain and/or myalgia experienced by men taking tadalafil were investigated. An integrated analysis of 10 placebo-controlled tadalafil clinical trials (N=1846) showed that the incidence of back pain and/or myalgia was 9.4% in patients receiving tadalafil 10 mg (N=394), 8.3% in patients receiving tadalafil 20 mg (N=883) and 3.7% in placebo-treated patients (N=569). One (0.3%) patient receiving tadalafil 10 mg, six (0.7%) patients receiving tadalafil 20 mg, and no patients receiving placebo discontinued treatment due to back pain and/or myalgia. In a prospective study in healthy volunteers, no substantial changes were observed in laboratory markers indicative of inflammation or muscle damage, and tadalafil did not affect renal plasma flow nor produce lumbar or gluteal myositis by positron emission tomography scan or magnetic resonance imaging. Although the mechanism of back pain and/or myalgia remains unknown, these events appear to be self-limiting and a general effect of phosphodiesterase 5 inhibition.

Neuroepithelial bodies not connected to pulmonary slowly adapting stretch receptors

Neuroepithelial bodies (NEBs) are believed to be connected with one of the known types of airway receptors. The present studies determined whether NEB afferents are pulmonary slowly adapting stretch receptors (SARs). NEBs are immunoreactive with antibodies against protein gene product (PGP) 9.5 and calcitonin gene-related peptide (CGRP), whereas SARs are reactive with antibody to Na(+)/K(+)-ATPase. Using histochemical staining in combination with confocal microscopy, we compared the morphology of NEBs and SARs in the rat. Our results show that NEBs and SARs are different in location, size, and shape. Double staining of airway tissues for PGP (or CGRP) plus Na(+)/K(+)-ATPase shows that NEBs and SARs do not co-localize. In addition, we electrophysiologically recorded single-unit activity of SARs from the cervical vagus nerve, identified their receptive fields, dissected them into blocks, and then double-stained and examined the receptor structures. We found that the blocks contain the SAR, but not NEB structures. Thus, we conclude that NEBs are not connected to SARs.

Haemostatic complications in haemodialysis patients: effect of type of vascular access and dialysis filter

Impaired haemostasis is common in patients with end-stage renal disease, and may cause either thrombotic or bleeding complications. The purpose of this study was to assess whether plasma markers of coagulation activation in patients undergoing chronic haemodialysis (HD) can identify high-risk individuals, and to test the relevancy of type of vascular access or dialysis filter. We measured plasma levels of prothrombin fragment 1+2, fibrin D-dimers and tissue factor in 82 HD patients before and after dialysis. Clinical endpoints during the year following blood sampling were thrombosis in blood access, changes in blood access, other thromboembolic events, bleeding complications, ischaemic vascular disease, or death. We found elevated baseline levels of all three parameters in HD patients, compared to normal reference ranges. Plasma levels of all parameters (particularly fibrin D-dimers) were significantly higher in patients with prosthetic grafts and central venous dialysis catheters than in patients with native vessels. Patients with AV-fistulas or grafts who had bleeding complications (n=7) had significantly higher plasma levels of fibrin D-dimer and prothrombin fragment 1+2. Bleeding complications also occurred more frequently among the patients with prosthetic grafts (3/18) or central venous dialysis catheters (3/11) compared with those with grafts from native vessels (1/53). Other than a bleeding tendency, our data do no show any correlation between coagulation parameters and other clinical complications during haemodialysis. In conclusion, we found elevated plasma levels of markers of coagulation activation among HD patients. High levels of D-dimers and prothrombin fragment 1+2 correlated to bleeding diathesis instead of thromboembolism, and this tendency was most pronounced in patients with prosthetic grafts.