In vivo knockdown of p85alpha with an antisense oligonucleotide improves insulin sensitivity in Lep(ob/ob) and diet-induced obese mice

Phosphoinositide 3-kinase is a key signaling intermediate necessary for the metabolic actions of insulin. In this study, we assessed the effects of in vivo knockdown of the p85alpha subunit of phosphoinositide 3-kinase on insulin sensitivity, using an antisense oligonucleotide, in lean mice, diet-induced obese mice, and obese leptin-deficient Lep (ob/ob) mice. Mice were injected with either p85alpha-targeted antisense oligonucleotide or saline twice weekly for 4 weeks. Fasting levels of glycemia and insulinemia and insulin and glucose tolerance tests were used to determine insulin sensitivity. Western blot analysis and real-time polyacrylamide chain reaction were used to assess p85alpha protein and mRNA expression. IN VIVO administration of antisense oligonucleotide resulted in 50 and 60% knockdown of liver p85alpha protein and mRNA, respectively, in the lean, diet-induced obese and Lep (ob/ob) mice. This was associated with increased phosphoinositide 3-kinase activity and improved insulin sensitivity in diet-induced obese and Lep (ob/ob) mice. Thus, p85alpha could be an important therapeutic target to ameliorate insulin resistance.

Predicting vigilance: a fresh look at an old problem

Individual differences in vigilance are ubiquitous and relevant to a variety of work environments in industrial, transportation, medical and security settings. Despite much previous work, mostly on personality traits, it remains difficult to identify vigilant operators. This paper reviews recent research that may point towards practically useful predictor variables for vigilance. Theoretical approaches to identifying predictors that accommodate the heterogeneous nature of vigilance tasks are compared. The article surveys recent empirical studies using personality measures, ability tests and scales for stress and coping as predictors of vigilance. Promising new constructs include trait scales linked to fatigue, abnormal personality and the stress state of task engagement. Implications of the data reviewed for occupational selection are discussed. Selection should be based on a multivariate assessment strategy, cognitive task analysis of the operational vigilance task and use of work sample measures to capture typical stress responses to the task. This review paper surveys recent research that may point towards practically useful predictor variables for vigilance. The article surveys recent empirical studies using personality measures, ability tests and scales for stress and coping as predictors of vigilance. Selection should be based on a multivariate assessment strategy.

Rituximab inhibits structural joint damage in patients with rheumatoid arthritis with an inadequate response to tumour necrosis factor inhibitor therapies

OBJECTIVE

To determine if treatment with a B cell-targeted therapy can inhibit the progression of structural joint damage in patients with rheumatoid arthritis (RA), exhibiting an inadequate response to tumour necrosis factor (TNF) inhibitors.

METHODS

In this phase III study, patients with an inadequate response to a TNF inhibitor and receiving methotrexate were randomised to rituximab or placebo. Radiographs were obtained at baseline, week 24 and week 56 after randomisation. Patients with an inadequate response to their randomised therapy could receive rescue medication from week 16. From week 24, eligible patients from both treatment arms could receive open-label rituximab. Patients were analysed according to their original treatment group. Radiographs were scored using the Genant-modified Sharp method. The primary radiographic endpoint was change in total Genant-modified Sharp score at week 56.

RESULTS

Rituximab treatment caused significant reduction in joint damage progression compared with placebo. The mean change from baseline in the total Genant-modified Sharp score at week 56 was significantly lower for patients treated with rituximab than for patients treated with placebo (1.00 vs 2.31; p = 0.005), and was supported by changes in erosion score (0.59 and 1.32 for rituximab plus methotrexate vs placebo plus methotrexate, respectively; p = 0.011) and joint space narrowing score (0.41 and 0.99, respectively; p<0.001).

CONCLUSIONS

This study provides the first evidence that a B cell-targeted therapy-rituximab-can significantly inhibit the progression of structural joint damage in patients with RA with long-standing, active and treatment-resistant disease.

Leap for Life: innovative patient education to optimize outcomes among patients with cardiovascular disease

OBJECTIVE

To evaluate the Leap for Life cardiovascular risk factor education program based on outcome measurements of self-reported hospital readmission, goal achievement, satisfaction, and educational model preference.

SETTING

Four hospitals and one senior center of Baylor Health Care System in the Dallas, Texas, area.

DESIGN

Administration of a satisfaction questionnaire and resurvey of participants by telephone at 3, 6, and 12 months.

PATIENTS

161 patients with cardiovascular disease enrolled in the Leap for Life program during calendar year 1997. Patients were primarily male (59%), with an average age of 66 years; they had an average of 4 cardiovascular disease risk factors.

RESULTS

Of the 152 participants who took part in the telephone follow-up, 19% reported a hospital admission with a cardiovascular diagnosis during the 12-month follow-up period. Twenty-one percent reported meeting all of their goals; 56%, some of their goals; and 23%, none of their goals. All stated that the educational sessions met their informational needs, and 75% preferred the Leap for Life setting over other educational settings. CONCLUSION AND NEXT STEPS: These data provide initial validation of the program and are being used as a starting point for another assessment that involves individualized health enhancement measures and 6- and 12-month follow-up of participants using a survey designed to assess readiness, lifestyle changes, and quality of life.

Chronic liver injury in rats and humans upregulates the novel enzyme angiotensin converting enzyme 2

BACKGROUND

Angiotensin converting enzyme (ACE) 2 is a recently identified homologue of ACE that may counterregulate the actions of angiotensin (Ang) II by facilitating its breakdown to Ang 1-7. The renin-angiotensin system (RAS) has been implicated in the pathogenesis of cirrhosis but the role of ACE2 in liver disease is not known.

AIMS

This study examined the effects of liver injury on ACE2 expression and activity in experimental hepatic fibrosis and human cirrhosis, and the effects of Ang 1-7 on vascular tone in cirrhotic rat aorta.

METHODS

In sham operated and bile duct ligated (BDL) rats, quantitative reverse transcriptase-polymerase chain reaction was used to assess hepatic ACE2 mRNA, and western blotting and immunohistochemistry to quantify and localise ACE2 protein. ACE2 activity was quantified by quenched fluorescent substrate assay. Similar studies were performed in normal human liver and in hepatitis C cirrhosis.

RESULTS

ACE2 mRNA was detectable at low levels in rat liver and increased following BDL (363-fold; p < 0.01). ACE2 protein increased after BDL (23.5-fold; p < 0.05) as did ACE2 activity (fourfold; p < 0.05). In human cirrhotic liver, gene (>30-fold), protein expression (97-fold), and activity of ACE2 (2.4 fold) were increased compared with controls (all p < 0.01). In healthy livers, ACE2 was confined to endothelial cells, occasional bile ducts, and perivenular hepatocytes but in both BDL and human cirrhosis there was widespread parenchymal expression of ACE2 protein. Exposure of cultured human hepatocytes to hypoxia led to increased ACE2 expression. In preconstricted rat aorta, Ang 1-7 alone did not affect vascular tone but it significantly enhanced acetylcholine mediated vasodilatation in cirrhotic vessels.

CONCLUSIONS

ACE2 expression is significantly increased in liver injury in both humans and rat, possibly in response to increasing hepatocellular hypoxia, and may modulate RAS activity in cirrhosis.

Does leucocytosis identify bacterial infections in febrile neonates presenting to the emergency department?

OBJECTIVE

This study was undertaken to evaluate the discriminatory power of the peripheral white blood cell (WBC) count to identify bacterial infections in a cohort of febrile neonates (<or=28 days of age) presenting to an emergency department.

METHODS

Retrospective medical record review using descriptive statistics and a receiver operating characteristic (ROC) curve. Neonates who presented to a tertiary care paediatric emergency department between 1 January 1999 and 22 August 2002, had a temperature >or=38 degrees C, underwent lumbar puncture, and had a WBC count obtained were included. They were divided according to microbiological and radiographic findings into four groups: bacterial infections, viral infections, pneumonia, and negative sepsis evaluations.

RESULTS

A total of 69 febrile neonates met the inclusion criteria. The number of neonates in each group was as follows: 8 with bacterial infections, 10 with viral infections, 3 with pneumonias, and 48 with negative sepsis evaluations. There was substantial overlap in WBC counts among the groups. The area under the ROC curve was 0.7231 (95% CI 0.5665 to 0.8797).

CONCLUSION

In a cohort of febrile neonates evaluated in the emergency department, the WBC count had modest discriminatory power in identifying neonates with bacterial infections and demonstrated substantial overlap among groups. The present data suggest against the use of any WBC count threshold to identify bacterial infections in febrile neonates presenting to the emergency department.

Cellular response to conditional expression of the hepatitis B virus precore and core proteins in cultured hepatoma (Huh-7) cells

BACKGROUND

The expression of the hepatitis Be antigen (HBeAg) is one of several strategies used by hepatitis B virus (HBV) to ensure persistence. The HBeAg may function as a toleragen in utero and has been shown to regulate the host's immune response.

AIM

The aim of this study was to examine the effect of the HBV precore and core protein on cellular gene expression in the hepatoma cell line Huh-7.

STUDY DESIGN

Huh-7 cells with tight regulated expression of the HBV core or precore protein were produced using the Tet-Off tetracycline gene expression system. Changes in cellular gene expression in response to core/precore expression compared to Huh-7 cells not expressing the proteins were determined using a commercial high-density oligonucleotide array (Affymetrix Hu95A GeneChip) containing probes for 12,626 full-length human genes.

RESULTS

Analysis of differential mRNA gene expression profiles at 7 days post precore and core expression revealed 45 and 5 genes, respectively, with mRNA changes greater than three-fold. The most striking feature was in Huh-7 cells expressing the precore protein in which 43/45 genes were downregulated 3-11-fold. These included genes that encoded products that regulate transcription/DNA binding proteins, cell surface receptors, cell-cycle/nucleic acid biosynthesis and intracellular signalling and trafficking. The only known gene, which was upregulated encoded a cytoskeletal protein. For the core cell line, 4/5 genes were downregulated 3-15-fold upon core induction and included genes that encoded products that affect intermediary metabolism, cell surface receptors and intracellular signalling. The one gene, which was upregulated was a cytokine gene.

CONCLUSION

The results of this study show that HBV precore protein has a much greater effect on cellular gene expression in comparison to the core protein, suggesting that core and precore proteins may have diverse effects on cellular functions and equally different roles in modulating HBV pathogenesis.

Training patterns and sports injuries in triathletes

Sports-related injuries are a significant health problem within Australia, and constitute a national health priority. There is limited Australian research data available on factors that contribute to triathlon injuries, and in particular on how training patterns relate to injury risk. This study examined the association between training patterns and injury in mostly non-elite triathletes. A cross-sectional survey of 258 triathletes completed a questionnaire that focused on injuries they had sustained during the previous three triathlon seasons. Statistical associations were found between hours of training and sustaining an injury. These associations were U shaped, with those triathletes training at low levels and at high levels more likely to sustain an injury. The results suggest that, for non-elite triathletes, the likelihood of sustaining an injury is least when training for a total of 8 to 10 hrs per week, specifically cycling for five to six hrs and running for three to four hrs weekly. Time spent on swimming training does not appear to affect injury risk. This research is seen as a contribution towards assisting triathletes in the planning of training programs aimed at reducing the risk of injury.

Commonality of elastic relaxation times in biofilms

Biofilms, sticky conglomerations of microorganisms and extracellular polymers, are among the Earth's most common life forms. One component for their survival is an ability to withstand external mechanical stress. Measurements indicate that biofilm elastic relaxation times are approximately the same (about 18 min) over a wide sample of biofilms though other material properties vary significantly. A possible survival significance of this time scale is that it is the shortest period over which a biofilm can mount a phenotypic response to transient mechanical stress.

Introductory postcards: do they increase response rate in a telephone survey of older persons?

The purpose of this study was to assess whether contact by mail via an introductory postcard would increase the response rate to a telephone survey in a selected population of 348 people 60 years and older. Of this group, 208 were sent a postcard introducing the study and informing them that someone would call in the next 1-2 weeks to conduct a telephone interview. The remaining sample of 140 did not receive the introductory postcard. Amongst the potential participants who were contacted and able to participate (n = 240), the response rate for completed interview was 58.0% for those sent a postcard and 42.3% for those who were not. The refusal rate was 25.3% (postcard sent) and 37.2% (not sent a postcard). When the outcome of contact is collapsed to two categories, 'agreed to participate' and 'refusal', the response rate to participate was 73.5% (sent a postcard) and 59.0% (not sent a postcard) (chi(2) 5.14, d.f. 1, sign. 0.023). The response rate amongst those who recall being sent a postcard rose to 86.0%. Whether agreeing to participate or refusing to be involved in the survey was dependent on being sent an introductory postcard. The conclusion is that mailing a postcard prior to the first telephone contact increases the participation rates of older persons in a telephone survey at very little extra cost (A$0.60 per person).

An Australian survey of in-patient protocols for quadriceps exercises following anterior cruciate ligament reconstruction

Current practices regarding in-patient strengthening exercise prescription following anterior cruclate ligament (ACL) reconstruction are scarcely addressed in the literature and remain unreported for Australian hospitals. An observational, questionnaire-based study was used to Investigate in-patient quadriceps strengthening practices in Australian hospitals after ACL reconstruction. Questionnaires were returned by 248 hospitals (76% response rate) and of these 88 hospitals reported performing ACL reconstructions. These hospitals were surveyed to determine the types of quadriceps strengthening exercises prescribed during the in-patient period. Information was sought regarding routine management strengthening practices. A variety of quadriceps exercises such as static quadriceps contractions (SQC), straight leg raises (SLR) and inner range quadriceps (IRQ) were frequently prescribed, although no standard practice currently exists. Static quadriceps exercises were prescribed by 91% of hospitals surveyed, IRQ exercises were used by 30%, and 49% reported using SLR exercises. Current literature tends to support the performance of SQC and SLR exercises during the early postoperative period following ACL reconstruction. Conversely, current clinical practice is incongruent with regard to the scientific recommendations for IRQ performance.

Cross-resistance testing of antihepadnaviral compounds using novel recombinant baculoviruses which encode drug-resistant strains of hepatitis B virus

Long-term nucleoside analog therapy for hepatitis B virus (HBV)-related disease frequently results in the selection of mutant HBV strains that are resistant to therapy. Molecular studies of such drug-resistant variants are clearly warranted but have been difficult to do because of the lack of convenient and reliable in vitro culture systems for HBV. We previously developed a novel in vitro system for studying HBV replication that relies on the use of recombinant baculoviruses to deliver greater than unit length copies of the HBV genome to HepG2 cells. High levels of HBV replication can be achieved in this system, which has recently been used to assess the effects of lamivudine on HBV replication and covalently closed circular DNA accumulation. The further development of this novel system and its application to determine the cross-resistance profiles of drug-resistant HBV strains are described here. For these studies, novel recombinant HBV baculoviruses which encoded the L526M, M550I, and L526M M550V drug resistance mutations were generated and used to examine the effects of these substitutions on viral sensitivity to lamivudine, penciclovir (the active form of famciclovir), and adefovir, three compounds of clinical importance. The following observations were made: (i) the L526M mutation confers resistance to penciclovir and partial resistance to lamivudine, (ii) the YMDD mutations M550I and L526M M550V confer high levels of resistance to lamivudine and penciclovir, and (iii) adefovir is active against each of these mutants. These findings are supported by the limited amount of clinical data currently available and confirm the utility of the HBV-baculovirus system as an in vitro tool for the molecular characterization of clinically significant HBV strains.

In vitro susceptibilities of wild-type or drug-resistant hepatitis B virus to (-)-beta-D-2,6-diaminopurine dioxolane and 2'-fluoro-5-methyl-beta-L-arabinofuranosyluracil

Prolonged treatment of chronic hepatitis B virus (HBV) infection with lamivudine ([-]-beta-L-2',3'-dideoxy-3' thiacytidine) or famciclovir may select for viral mutants that are drug resistant due to point mutations in the polymerase gene. Determining whether such HBV mutants are sensitive to new antiviral agents is therefore important. We used a transient transfection system to compare the sensitivities of wild-type HBV and four lamivudine- and/or famciclovir-resistant HBV mutants to adefovir [9-(2-phosphonyl-methoxyethyl)-adenine; PMEA] and the nucleoside analogues (-)-beta-D-2, 6-diaminopurine dioxolane (DAPD) and 2'-fluoro-5-methyl-beta-L-arabinofuranosyluracil (L-FMAU). The drug-resistant mutants contained amino acid substitutions in the polymerase protein. We found that the M550I and M550V plus L526M substitutions, which confer lamivudine resistance, did not confer cross-resistance to adefovir or DAPD, but conferred cross-resistance to L-FMAU. The M550V substitution in isolation conferred a similar phenotype to M550I, except that it did not confer significant resistance to L-FMAU. The L526M substitution, which is associated with famciclovir resistance, conferred cross-resistance to L-FMAU but not to adefovir or DAPD. Inhibition of HBV secretion by DAPD, L-FMAU, and adefovir did not always correlate with inhibition of the generation of intracellular HBV replicative intermediates, suggesting that these analogs may preferentially inhibit specific stages of the viral replication cycle.