Dislocation-source shutdown and the plastic behavior of single-crystal micropillars

Dislocation dynamics simulations have been used to study the stress-strain response of single-crystal micropillars containing initial dislocation networks generated via a relaxation procedure intended to approximate real thermal annealing processes. We find that, when such networks are loaded, they exhibit periods of plastic deformation, caused by the operation of single junction-stabilized spiral sources, followed by intervals of purely elastic straining when the sources shut down. The results provide insight into the mechanisms responsible for the experimentally observed staircase stress-strain behavior.

A Study of the Regulating Gene of femA from Methicillin-resistant Staphylococcus aureus Clinical Isolates

The regulating gene of femA was studied in methicillin-resistant Staphylococcus aureus (MRSA). High-level MRSA, low-level MRSA and methicillin-sensitive S. aureus (MSSA) were identified by agar diffusion. β-Lactamases were detected by nitrocephin and the presence of the mecA gene was determined by polymerase chain reaction (PCR). Only isolates that were both β-lactamase-negative and mecA-positive were used. The femA gene and its 250 base pair (bp) upstream sequence were amplified by PCR and expression was determined by real-time fluorescent quantitative PCR. The 250 bp upstream sequence was labelled by BrightStar€ Psoralen–Biotin and detected by electrophoretic mobility shift assay (EMSA). Expression levels of femA in MSSA, low-level MRSA and high-level MRSA were 3.53 × 10−3%–29.91%, 5.54 × 10−3%–3.1 × 102% and 13.88–5.50 × 104%, respectively. EMSA detected a signal shift in 57 high-level MRSA isolates but not in four low-level MRSA and four MSSA strains. Expression of femA in high-level MRSA (non-β-lactamase-producing) was higher than in low-level MRSA and MSSA. The femA regulating gene probably lies in the 250 bp upstream sequence in MRSA and high-level expression is essential for high-level methicillin resistance.

Internet use and risk behaviours: an online survey of visitors to three gay websites in China

OBJECTIVES

To describe the risk behaviours of visitors to gay websites and to explore the role of the internet in the HIV transmission among the Chinese men who have sex with men (MSM).

METHODS

Between May and August 2006, visitors of three Chinese gay websites were invited to complete an online questionnaire about the use of the internet and risk sexual behaviours.

RESULTS

The median age of the online sample was 25 years old (range 18 to 64). Over three-quarters (77.6%) had an education of college or higher. Less than 44% of the online sample reported little or no risk for HIV transmission. These men had either had no anal intercourse (28.0%) or had always used a condom for anal intercourse (15.8%). Although only about half of the participants reported that their main purpose of visiting the gay websites was to look for sexual partners, most participants (86.1%) had used the internet to seek partners. Compared with men seeking sexual partners only on the internet, men seeking partners both in traditional gay venues and on the internet were older, less likely to be students and more likely to have unprotected anal intercourse, more than six sexual partners in the past 6 months and commercial sex behaviours.

CONCLUSION

The users of the gay websites are relatively young and well educated, and highly vulnerable to HIV/AIDS, given their low prevalence of consistent condom use and multiple-risk sexual behaviours. Effective intervention programmes should be implemented and strengthened in China, especially for those who seek sexual partners both on the internet and in traditional gay venues.

Vena caval filters for the prevention of pulmonary embolism

BACKGROUND

Pulmonary emboli can have potentially fatal consequences. Inferior vena caval filters are metal alloy devices that mechanically trap fragmented thromboemboli from the deep leg veins en route to the pulmonary circulation. Filters in current clinical use are designed to be introduced (and in the case of retrievable filters, removed) percutaneously. Although their deployment seems of theoretical benefit, their clinical efficacy and adverse event profile is unclear.

OBJECTIVES

To examine evidence for the effectiveness of vena caval filters in preventing pulmonary embolism (PE). Secondary outcomes were mortality, distal (to filter) thrombosis, and filter-related complications.

SEARCH STRATEGY

We searched the Cochrane Peripheral Vascular Diseases Group Specialised Register (last searched August 2007), the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library 2007, Issue 3, MEDLINE (1966 to August 2007), and EMBASE (1966 to August 2007). Filter manufacturers and clinicians interested in filters were contacted for information.

SELECTION CRITERIA

Controlled clinical trials (CCTs) and randomised controlled trials (RCTs) that examined the efficacy of filters in preventing PE were selected.

DATA COLLECTION AND ANALYSIS

Three authors extracted information independently. Incidence figures were extracted from survival tables. Dichotomous outcomes were analysed as hazard ratio estimates.

MAIN RESULTS

One RCT was included. The PREPIC (Prévention du Risque d'Embolie Pulmonaire par Interruption Cave) trial was an open RCT of 400 participants with documented proximal deep vein thrombosis (DVT) or PE and who received concurrent anticoagulation. Permanent caval filters prevented PE at eight years (HR 0.37, 95% CI 0.17 to 0.79, in favour of the filter). No reduction in mortality was seen, but this reflected an older study population (mean age 73 years); the majority of deaths were due to cancer or cardiovascular causes. There was an increased incidence of DVT in the filter group (HR 1.52, 95% CI 1.02 to 2.27). No details were recorded of adverse events of filters.

AUTHORS' CONCLUSIONS

Limited generalisability prevents any conclusions to be drawn from the PREPIC trial in that permanent filters were used and the study lacked statistical power to detect a reduction in PE over shorter and more clinically significant time periods. However, the PREPIC trial demonstrated that permanent caval filters were associated with an increased risk of long term lower limb DVT. There is a marked paucity of caval filter outcomes evidence when used within their currently approved indications. There is also a lack of retrievable filter trials. Further trials are needed to assess vena caval filter safety and effectiveness.

Characterising alternate splicing and tissue specific expression in the chicken from ESTs

Alternate splicing is believed to produce the greatest diversity in transcriptional complexity and function in eukaryotic species. In this study, we present an analysis of alternative splicing events that occur in the chicken, using the recently sequenced genomic sequence and over 580,000 EST sequences mapped back to the genome. A carefully controlled EST-to-genome mapping pipeline is presented, based around the EXONERATE program using the est2genome model, which also considers several quality control steps to filter out erroneous matches. The data is then used to estimate the level of alternate splicing events with respect to Ensembl predicted transcripts. The EST-genome mappings are characterised at the exon level, in order to classify individual splicing events and provide estimates of novel transcripts not currently annotated by the Ensembl genome database. This is the first large scale analysis of this kind in an avian species, and suggests that chicken displays a similar level of alternate splicing as that found in other higher vertebrates such as human and mouse, both in terms of the number of genes that undergo alternate splicing events, and the average number of transcripts produced per gene. The EST data suggests alternate splicing may occur in some 50-60% of the chicken gene set and with an average of around 2.3 transcripts per gene which undergo this process. The EST data is also used to look at gene and transcript usage in the tissues sequenced in embryonic and adult libraries. Genes which display notable biases were analysed in more detail, including twinfilin-2 and embryonic heavy chain myosin. This also highlights several as yet functionally un-annotated genes which appear to be important in embryonic tissues and also undergo alternate splicing events. The analysis also demonstrates some of the difficulties involved in using EST-based data to annotate transcriptional activity in eukaryotic genes, where a broad spectrum of tissues and a large number of sequenced transcripts are required in order to fully characterise alternate splicing and differential expression.

The g.243A>G mutation in intron 17 of MUC4 is significantly associated with susceptibility/resistance to ETEC F4ab/ac infection in pigs

Using a porcine radiation hybrid panel, we assigned the mucin 4 (MUC4) gene to SSC13q41, which harbours the enterotoxigenic Escherichia coli (ETEC) F4ab/ac receptor locus. In addition, we identified two SNPs in intron 17 of MUC4 (DQ124298:g.243A>G and DQ124298:g.334A>G) in the parental population of a White Duroc x Erhualian cross. Association analysis showed that the MUC4 g.243A>G mutation was strongly associated with ETEC F4ab/ac, and especially with F4ac adhesion phenotypes in the White Duroc x Erhualian resource population, indicating that this polymorphism was in a significant linkage disequlibrium with the ETEC F4ab/ac receptor locus. Because of different linkage disequlibrium values between the ETEC F4ab and F4ac adhesion phenotypes and the MUC4 g.243A>G mutation, we argue that the inheritance of F4ab and F4ac receptors might be under the control of two closely linked loci.

Characterization of polymorphisms of transferrin receptor and their association with susceptibility to ETEC F4ab/ac in pigs

Diarrhoea caused by enterotoxigenic Escherichia coli (ETEC) expressing F4 (F4ab, F4ac and F4ad) fimbriae is a significant cause of mortality and morbidity in newborn and weaned pigs. The locus controlling susceptibility towards ETEC F4ab/ac has been mapped to SSC13q41, in which TFRC (transferrin receptor) was localized and considered as a positional candidate gene for ETEC F4ab/ac receptor. In this study, we determined susceptibility/resistance to ETEC F4ab/ac in a total of 755 F2 animals from a White Duroc x Erhualian intercross using a microscopic enterocyte adhesion assay. We identified two TFRC polymorphisms (SNPs 591 A>G and 632 A>G) in a single exon after comparative sequencing analysis of 2371-bp amplicons containing the complete coding region of TFRC using RNA of eight full-sib F2 animals with susceptible and resistant phenotypes. The intron sequences flanking the two exon polymorphisms were obtained, revealing an intron polymorphism (SNP 291 C>T). We genotyped the 19 founder animals of the White Duroc x Erhualian intercross for the identified polymorphisms, showing that only the 291 C>T polymorphism is a highly informative marker. We further genotyped all 59 F1 and 755 F2 animals for the 291 C>T polymorphism, and the association of this polymorphism with susceptibility/resistance to ETEC F4ab/ac in these F2 animals was evaluated by the transmission disequilibrium test. The result showed that the 291 C>T polymorphism is not a causal mutation, however, has a significant linkage disequilibrium with the ETEC F4ab/ac, especially F4ac receptor locus.

Vena caval filters for the prevention of pulmonary embolism

BACKGROUND

Pulmonary emboli can have potentially fatal consequences. Inferior vena caval filters are metal alloy devices that mechanically trap fragmented thromboemboli from the deep leg veins en route to the pulmonary circulation. Filters in current clinical use are designed to be introduced (and in the case of retrievable filters, removed) percutaneously. Although their deployment seems of theoretical benefit, their clinical efficacy and adverse event profile is unclear.

OBJECTIVES

To examine evidence for the effectiveness of vena caval filters in preventing pulmonary embolism (PE). Secondary outcomes were mortality, distal (to filter) thrombosis, and filter-related complications.

SEARCH STRATEGY

Searches were conducted in the Cochrane Peripheral Vascular Diseases Group Specialised Register (last searched May 2007), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2007), MEDLINE (1966 to May 2007), and EMBASE (1966 to May 2007). Filter manufacturers and clinicians interested in filters were contacted for information.

SELECTION CRITERIA

Controlled clinical trials (CCTs) and randomised controlled trials (RCTs) that examined the efficacy of filters in preventing PE were selected.

DATA COLLECTION AND ANALYSIS

Three authors extracted information independently. Incidence figures were extracted from survival tables. Dichotomous outcomes were analysed as hazard ratio estimates.

MAIN RESULTS

One RCT met the inclusion criteria. The PREPIC trial was an open RCT of 400 participants with documented proximal deep vein thrombosis (DVT) or pulmonary embolism and who received concurrent anticoagulation.PREPIC demonstrated the efficacy of permanent caval filters in preventing PE at eight years (HR 0.37, 95% CI 0.17 to 0.79, in favour of the filter). No reduction in mortality was seen, but this reflected an older study population (mean age 73 years); the majority of deaths were due to cancer or cardiovascular causes. There was an increased incidence of DVT in the filter group (HR 1.52, 95% CI 1.02 to 2.27). No details were recorded of adverse events of filters. No CCTs suitable for inclusion were found.

AUTHORS' CONCLUSIONS

Limited generalisability prevents any conclusions to be drawn from PREPIC. PREPIC employed permanent filters and lacked statistical power to detect a reduction in PE over shorter and more clinically significant time periods. However, PREPIC demonstrated that permanent caval filters are associated with an increased risk of long term lower limb DVT. There is a marked paucity of evidence regarding caval filter outcomes when used within their currently approved indications. There is also a lack of retrievable filter trials. Further trials are needed to assess vena caval filter safety and effectiveness.

Myocardial Fiber Length Mapping with MR Diffusion Tensor Imaging

Diffusion tensor MRI is emerging as a rapid, nondestructive method to map myocardial fiber organization. A precise biological description of myocardial fiber performance requires knowledge of four variables: length, force, velocity and time. However, study of quantification of myocardial fiber length is lacking. The current study aims to show myocardial fiber length maps of formalin-fixed heats. Diffusion tensor MRI with medium diffusion resolution (15 directions) was performed in one isolated pig heart. Fiber length maps were investigated in multiple short-axis slices. The results provide supplementary information of myocardial fiber organization. To our knowledge, the present study is the first report of the myocardial fiber length mapping.

Prognostic significance of osteopontin in hepatitis B virus-related hepatocellular carcinoma

BACKGROUND AND AIMS

Osteopontin (OPN) is known to be associated with metastasis in many types of cancers. Since OPN is a highly phosphorylated and glycosylated protein, the modification after transcription is very important to its function. In hepatocellular carcinoma (HCC), the elevated expression of OPN at mRNA levels and its relationship with metastasis and poorer prognosis of the patients have been reported. However, the prognostic impact of OPN at protein levels on the patients with hepatitis B virus (HBV)-related HCC after hepatectomy is still limited.

PATIENTS AND METHODS

The expression of OPN was examined at protein level by using immunohistochemistry in 72 patients who underwent hepatectomy for HBV-related HCC, and its prognostic significance in disease-free and overall survival of the patients was also analyzed by log-rank test and multivariate Cox regression analyses.

RESULTS

Thirty-nine of 72 (54.17%) HBV-related HCC specimens were positive for OPN with cytoplasmic staining. OPN was highly expressed in the specimens with capsular infiltration compared to those without (P<0.05), and also was significantly related with portal vein invasion (P<0.01) and lymph node invasion (P<0.01). The mean disease-free survival (DFS) was only 13.55+/-14.77 months when the HBV-related HCC specimens highly expressed OPN compared to 36.00+/-18.68 months for those with low expression (P<0.001). The overall survival (OS) of the patients was 18.63+/-17.28 months when the HCC over-expressed OPN compared to 42.59+/-16.85 months for HCC with the low expressed OPN (P<0.001). Multivariate analysis showed that OPN over-expression was the strongest independent adverse prognostic factor for both DFS (P=0.01) and OS (P=0.014).

CONCLUSIONS

OPN over-expression was closely related to capsular infiltration, venous invasion, lymph node metastasis, and also with worse prognosis, suggesting that OPN might be deemed as a useful molecular marker for predicting the prognosis of HCC.

Minocycline increases quality and longevity of chronic neural recordings

Brain/machine interfaces could potentially be used in the treatment of a host of neurological disorders ranging from paralysis to sensory deficits. Insertion of chronic micro-electrode arrays into neural tissue initiates a host of immunological responses, which typically leads to the formation of a cellular sheath around the implant, resulting in the loss of useful signals. Minocycline has been shown to have neuroprotective and neurorestorative effects in certain neural injury and neurodegenerative disease models. This study examined the effects of minocycline administration on the quality and longevity of chronic multi-channel microwire neural implants 1 week and 1 month post-implantation in auditory cortex. The mean signal-to-noise ratio for the minocycline group stabilized at the end of week 1 and remained above 4.6 throughout the following 3 weeks. The control group signal-to-noise ratio dropped throughout the duration of the study and at the end of 4 weeks was 2.6. Furthermore, 68% of electrodes from the minocycline group showed significant stimulus-driven activity at week 4 compared to 12.5% of electrodes in the control group. There was a significant reduction in the number of activated astrocytes around the implant in minocycline subjects, as well as a reduction in total area occupied by activated astrocytes at 1 and 4 weeks.

Aluminium mobilization from acidic forest soils in Leigongshan area, Southwestern China: Laboratory and field study

Aluminium mobilization from acidic forest soils in the remote Leigongshan area in southwestern China was investigated in the field and by a laboratory batch experiment using sequential extractions with HCl solutions with pH of approximately 3.4. Experimental data showed that strongly organically bound aluminium (Alp-Alcu) decreased significantly after sequential extraction, whereas exchangeable aluminium (Alex) increased in all three horizons. In the A-horizon with higher base saturation (BS), dissolved aluminium exchanged with base cations (BCs) on soil complex, causing lower aluminium release but significant leaching of BCs. In AB- and B-horizon with lower BS, more dissolved aluminium remained in solution. Al3+ activities in both experimental soil extracts and field soil waters strongly deviated from those predicted by the gibbsite model (i.e., pAl = pKsp + 3.0 pH) despite a significant increase in Al3+ with a decrease in pH. The soil organic-bound aluminium model, using Alcu and Alp to account for differences in the size of available Al pools in the soil, gave considerably better fits to both experimental and field data. SOM-Al model, approved by using Alex instead of organically bound aluminium (i.e., Alp and Alcu), could depict the changes in Al activities most successfully. We have concluded that Alp-Alcu is the main source of aqueous aluminium, whereas Alex plays an important role in regulating aluminium solubility during soil acidification.

Quantitative urinalysis of the mercapturic acid conjugates of allyl formate using high-resolution NMR spectroscopy

As end products of xenobiotic metabolism via glutathione conjugation, mercapturic acids (MCAs) can be used as markers to indicate exposure to allylic compounds as well as the rate and efficiency of their excretion. In addition, the formation of certain MCAs indicates metabolism via the known toxin acrolein, a strong electrophile. High-resolution 1H NMR spectroscopy has been employed to quantitatively measure the presence of MCAs in the urine of Sprague-Dawley rats, collected in the 8 h following 25 and 50 mgkg(-1) i.p. doses of allyl formate (AF), a model toxin. 3-Hydroxypropylmercapturic acid (HPMA) was found to be the only 1H NMR-observable MCA excreted in the urine, exhibiting a percentage recovery of approximately 20% at the 25 mgkg(-1) dose level, and approximately 30% at the 50 mgkg(-1) dose level.

Blood-based biomarkers for detecting mild osteoarthritis in the human knee

OBJECTIVE

This study was designed to test the utility of a blood-based approach to identify mild osteoarthritis (OA) of the knee.

METHODS

Blood samples were drawn from 161 subjects, including 85 subjects with arthroscopically diagnosed mild OA of the knee and 76 controls. Following RNA isolation, an in-house custom cDNA microarray was used to screen for differentially expressed genes. A subset of selected genes was then tested using real-time RT-PCR. Logistic regression analysis was used to evaluate linear combinations of the biomarkers and receiver operating characteristic curve analysis was used to assess the discriminatory power of the combinations.

RESULTS

Genes differentially expressed (3543 genes) between mild knee OA and control samples were identified through microarray analysis. Subsequent real-time RT-PCR verification identified six genes significantly down-regulated in mild OA: heat shock 90kDa protein 1, alpha; inhibitor of kappa light polypeptide gene enhancer in B-cells, kinase complex-associated protein; interleukin 13 receptor, alpha 1; laminin, gamma 1; platelet factor 4 (also known as chemokine (C-X-C motif) ligand 4) and tumor necrosis factor, alpha-induced protein 6. Logistic regression analysis identified linear combinations of nine genes--the above six genes, early growth response 1; alpha glucosidase II alpha subunit; and v-maf musculoaponeurotic fibrosarcoma oncogene homolog B (avian)--as discriminatory between subjects with mild OA and controls, with a sensitivity of 86% and specificity of 83% in a training set of 78 samples. The optimal biomarker combinations were then evaluated using a blind test set (67 subjects) which showed 72% sensitivity and 66% specificity.

CONCLUSIONS

Linear combinations of blood RNA biomarkers offer a substantial improvement over currently available diagnostic tools for mild OA. Blood-derived RNA biomarkers may be of significant clinical value for the diagnosis of early, asymptomatic OA of the knee.

Increased extracellular glutamate evoked by 1-methyl-4-phenylpyridinium [MPP(+)] in the rat striatum is not essential for dopaminergic neurotoxicity and is not derived from released glutathione

A number of studies have implicated the interactions of the excitatory amino acid L-glutamate (Glu) with its ionotropic and metabotropic receptors as important components of the mechanism underlying the dopaminergic neurotoxicity of 1-methyl-4-phenylpyridinium [MPP(+)]. Furthermore, microdialysis experiments have demonstrated that perfusion of relatively high concentrations of MPP(+) into the rat striatum evoke a delayed, massive release of Glu. Interestingly, perfusion of MPP(+) also mediates a similar release of glutathione (GSH). Together, these observations raise the possibility that the rise of extracellular Glu mediated by MPP(+) may be the result of hydrolysis of released GSH by gamma-glutamyl transpeptidase (gamma-GT). In the present investigation it is demonstrated that perfusions of solutions of 0.7 and 1.3 mM MPP(+) dissolved in artificial cerebrospinal fluid into the rat striatum evoke neurotoxic damage to dopaminergic terminals, assessed by both a two-day test/challenge procedure and tyrosine hydroxylase immunoreactivity, but without the release of Glu. Perfusions of 2.5 mM MPP(+) cause more extensive dopaminergic neurotoxicity and a dose-dependent release of Glu. However, neither this release of Glu nor MPP(+)-induced dopaminergic neurotoxicity are blocked by the irreversible gamma-GT inhibitor acivicin. Together, these observations indicate that a rise of extracellular levels of Glu is not essential for the dopaminergic neurotoxicity of MPP(+). Furthermore, the rise of extracellular Glu caused by perfusion of 2.5 mM MPP(+) is not the result of the gamma-GT-mediated hydrolysis of released GSH. It is possible that the rise of extracellular levels of Glu, L-aspartate, L-glycine and L-taurine evoked by perfusions of 2.5 mM MPP(+) into the rat striatum may reflect, at least in part, the release of these amino acids from astrocytes.

Changes of knowledge, attitudes, beliefs, and preference of bar owner and staff in response to a smoke-free bar law

OBJECTIVE

To examine attitudinal changes of bar owners and staff regarding a smoke-free bar law.

DESIGN

Bar owners and staff were random selected and telephone interviewed in June 1998, shortly after a smoke-free bar law was enacted, and October 2002. Similar instruments were used in both surveys to collect data on attitudes related to secondhand smoke (SHS) and behaviours related to the smoke-free bar law.

PARTICIPANTS

651 and 650 respondents worked for either stand alone bars or combination bars.

MEASURES

Preference of working in a smoke-free environment, concerns of the effect of SHS, and how to comply with the law.

RESULTS

The percentage of bar owners or staff working in stand alone bars who prefer to work in a smoke-free environment increased from 17.3% in 1998 to 50.9% in 2002 (p < 0.001). Significantly more respondents (45.5%) working in stand alone bars were concerned about the effects of SHS on their health, comparing to 21.6% in 1998 (p < 0.001). When patrons smoked in the bar, 82.1% of stand alone bar owners or staff in the 2002 survey would ask them to stop or to smoke outside, increased from only 43.0% in the 1998 survey (p < 0.001).

CONCLUSION

A positive and significant attitudinal change related to the smoke-free bar law occurred among California bars.