Recombinant Human Collagen XV Regulates Cell Adhesion and Migration

The C-terminal end of collagen XV, restin, has been the focus of several studies, but the functions of full-length collagen XV have remained unknown. We describe here studies on the production, purification, and function of collagen XV and the production of a monoclonal N-terminal antibody to it. Full-length human collagen XV was produced in insect cells using baculoviruses and purified from the cell culture medium. The yield was 15 mg/liter of cell culture medium. The collagen XV was shown to be trimeric, with disulfide bonds in the collagenous region. Rotary shadowing electron microscopy revealed rod-like molecules with a mean length of 241.8 nm and with a globular domain at one end. The globular domain was verified to be the N-terminal end by N-terminal antibody binding. The molecules show flexibility in their conformation, presumably due to the many interruptions in their collagenous domains. The ability of collagen XV to serve as a substrate for cells was tested in cell adhesion assays, and it was shown that cells did not bind to collagen XV-coated surfaces. When added to the culture medium of fibroblasts and fibrosarcoma cells, however, collagen XV rapidly bound to their fibronectin network. Solid phase assays showed that collagen XV binds to fibronectin, laminin, and vitronectin and that it binds to the collagen/gelatin-binding domain of fibronectin. No binding was detected to fibrillar collagens, fibril-associated collagens, or decorin. Interestingly, collagen XV was found to inhibit the adhesion and migration of fibrosarcoma cells when present in fibronectin-containing matrices.     

Putrescine transport in a cyanobacterium Synechocystis sp. PCC 6803

The transport of putrescine into a moderately salt tolerant cyanobacterium Synechocystis sp. PCC 6803 was characterized by measuring the uptake of radioactively-labeled putrescine. Putrescine transport showed saturation kinetics with an apparent K(m) of 92 +/- 10 microM and V(max) of 0.33 +/- 0.05 nmol/min/mg protein. The transport of putrescine was pH-dependent with highest activity at pH 7.0. Strong inhibition of putrescine transport was caused by spermine and spermidine whereas only slight inhibition was observed by the addition of various amino acids. These results suggest that the transport system in Synechocystis sp. PCC 6803 is highly specific for polyamines. Putrescine transport is energy-dependent as evidenced by the inhibition by various metabolic inhibitors and ionophores. Slow growth was observed in cells grown under salt stress. Addition of low concentration of putrescine could restore growth almost to the level observed in the absence of salt stress. Upshift of the external osmolality generated by either NaCl or sorbitol caused an increased putrescine transport with an optimum 2-fold increase at 20 mosmol/kg. The stimulation of putrescine transport mediated by osmotic upshift was abolished in chloramphenicol-treated cells, suggesting possible involvement of an inducible transport system.     

University students' knowledge of, and attitudes towards, hiv and AIDS, homosexuality and sexual risk behaviour: a questionnaire survey in two finnish universities

Summary This study describes Finnish university students' knowledge and attitudes towards HIV and AIDS, homosexuality and sexual risk behaviour. Finnish-speaking students were randomly selected from all registered students at two universities in Finland (N=9715, n=950). The data were collected by using a modified version of the State University of New York at Buffalo School of Nursing AIDS Study Questionnaire on sexual risk behaviour developed by Held and Chng. The total response rate was 35% (n=333). The data were analysed using quantitative statistical methods. Normally distributed data were analysed by t-test and one-way ANOVA, with Bonferroni corrections. Non-normally distributed data were analysed using the Mann-Whitney U-test and Kruskal-Wallis test, followed by a post-hoc test. The majority of students were familiar with HIV and AIDS, including its mode of transmission. However, there were still some misconceptions concerning HIV and AIDS. The oldest students and women had a more positive attitude towards people living with HIV and AIDS (PLWHA). Of patients with HIV or AIDS, intravenous drug users were perceived most negatively. Male students had more homophobic attitudes. Students who reported that religion had an important role in their lives had significantly stricter attitudes towards sexual risk behaviour. Students' knowledge correlated positively with general attitudes towards HIV and AIDS. Knowledge about HIV and AIDS will lead to more positive attitudes towards HIV and AIDS as a disease, towards those infected as well as homosexual people. There is a need to focus on preventive health care and sexual health promotion by educating young people and changing their attitudes towards sexual risk behaviour.     

Rab13 is upregulated during osteoclast differentiation and associates with small vesicles revealing polarized distribution in resorbing cells

Osteoclasts are bone-resorbing multinucleated cells that undergo drastic changes in their polarization due to heavy vesicular trafficking during the resorption cycle. These events require the precise orchestration of membrane traffic in order to maintain the unique characteristics of the different membrane domains in osteoclasts. Rab proteins are small GTPases involved in regulation of most, if not all, steps of vesicle trafficking. The investigators studied RAB genes in human osteoclasts and found that at least 26 RABs were expressed in osteoclasts. Out of these, RAB13 gene expression was highly upregulated during differentiation of human peripheral blood monocytic cells into osteoclasts. To study its possible function in osteoclasts, the investigators performed immunolocalization studies for Rab13 and various known markers of osteoclast vesicular trafficking. Rab13 localized to small vesicular structures at the superior parts of the osteoclast between the trans-Golgi network and basolateral membrane domain. Rab13 localization suggests that it is not involved in endocytosis or transcytosis of bone degradation products. In addition, Rab13 did not associate with early endosomes or recycling endosomes labeled with EEA1 or TRITC-conjugated transferrin, respectively. Its involvement in glucose transporter traffic was excluded as well. It is suggested that Rab13 is associated with a putative secretory function in osteoclasts.     

Genes involved in systemic and arterial bed dependent atherosclerosis--Tampere Vascular study

Background

Atherosclerosis is a complex disease with hundreds of genes influencing its progression. In addition, the phenotype of the disease varies significantly depending on the arterial bed.

Methodology/Principal Findings

We characterized the genes generally involved in human advanced atherosclerotic (AHA type V–VI) plaques in carotid and femoral arteries as well as aortas from 24 subjects of Tampere Vascular study and compared the results to non-atherosclerotic internal thoracic arteries (n=6) using genome-wide expression array and QRT-PCR. In addition we determined genes that were typical for each arterial plaque studied. To gain a comprehensive insight into the pathologic processes in the plaques we also analyzed pathways and gene sets dysregulated in this disease using gene set enrichment analysis (GSEA). According to the selection criteria used (>3.0 fold change and p-value <0.05), 235 genes were up-regulated and 68 genes down-regulated in the carotid plaques, 242 genes up-regulated and 116 down-regulated in the femoral plaques and 256 genes up-regulated and 49 genes down-regulated in the aortic plaques. Nine genes were found to be specifically induced predominantly in aortic plaques, e.g., lactoferrin, and three genes in femoral plaques, e.g., chondroadherin, whereas no gene was found to be specific for carotid plaques. In pathway analysis, a total of 28 pathways or gene sets were found to be significantly dysregulated in atherosclerotic plaques (false discovery rate [FDR] <0.25).

Conclusions

This study describes comprehensively the gene expression changes that generally prevail in human atherosclerotic plaques. In addition, site specific genes induced only in femoral or aortic plaques were found, reflecting that atherosclerotic process has unique features in different vascular beds.     

Job strain and tobacco smoking: an individual-participant data meta-analysis of 166,130 adults in 15 European studies

Background

Tobacco smoking is a major contributor to the public health burden and healthcare costs worldwide, but the determinants of smoking behaviours are poorly understood. We conducted a large individual-participant meta-analysis to examine the extent to which work-related stress, operationalised as job strain, is associated with tobacco smoking in working adults.

Methodology and Principal Findings

We analysed cross-sectional data from 15 European studies comprising 166 130 participants. Longitudinal data from six studies were used. Job strain and smoking were self-reported. Smoking was harmonised into three categories never, ex- and current. We modelled the cross-sectional associations using logistic regression and the results pooled in random effects meta-analyses. Mixed effects logistic regression was used to examine longitudinal associations. Of the 166 130 participants, 17% reported job strain, 42% were never smokers, 33% ex-smokers and 25% current smokers. In the analyses of the cross-sectional data, current smokers had higher odds of job strain than never-smokers (age, sex and socioeconomic position-adjusted odds ratio: 1.11, 95% confidence interval: 1.03, 1.18). Current smokers with job strain smoked, on average, three cigarettes per week more than current smokers without job strain. In the analyses of longitudinal data (1 to 9 years of follow-up), there was no clear evidence for longitudinal associations between job strain and taking up or quitting smoking.

Conclusions

Our findings show that smokers are slightly more likely than non-smokers to report work-related stress. In addition, smokers who reported work stress smoked, on average, slightly more cigarettes than stress-free smokers.     

Single nucleotide polymorphism -799C/T in matrix metalloproteinase-8 promoter region in arterial disease

Arterial disease is associated with elevated serum matrix metalloproteinase (MMP)-8 concentration. We studied the role of two promoter region single nucleotide polymorphisms (SNPs) of MMP-8 gene in the arterial disease. The population comprised patients with arterial disease (n?=?124) and healthy blood donors (n?=?100) as a reference group for MMP-8 SNPs (-799C/T and -381A/G) genotypes and serum concentrations. Genotype frequencies for MMP-8 -799C/T SNP in arterial disease were C/C (43.5%), C/T (32.3%) and T/T (24.2%), and in the reference group they were C/C (50.0%), C/T (40.0%) and T/T (10.0%; P?=?0.012). The -799C allele frequency was lower in the patients (59.7%) than in the reference group (70.0%; P?=?0.023). The -799C allele showed protective effects against the arterial disease with an odds ratio [95% confidence interval (CI)] of 0.372 (0.141-0.980, P?=?0.045) after adjustment for age, gender, and serum MMP-8 and TIMP-1 concentrations. Only in the reference group and whole study population (n?=?224), the -799TT genotype significantly associated with an increase in serum MMP-8 concentrations (P?=?0.047, 0.025). The -799C allele appeared protective against the arterial disease. The genotype may have an effect on systemic MMP-8 levels which could not, however, be seen in the arterial disease patients probably as a result of the strong inflammation involved in the disease pathogenesis.     

Controls of organic and inorganic carbon in randomly selected Boreal lakes in varied catchments

Organic and inorganic carbon concentrations in lakes and the links to catchment and water quality were studied in variable landscapes using the Finnish Lake Survey data base including 874 randomly selected lakes sampled during autumn overturn. The median total organic carbon (TOC) in these boreal lakes was 7.8 mg l^?1, the median total inorganic carbon (TIC) 1.6 mg l^?1 and the median partial pressure of CO₂ (pCO₂) 900 μatm. When the data was divided into subgroups according to land use in the catchment, the proportion of TIC of the total carbon (TC) in lakes was highest (31%) in agricultural areas and lowest (10%) in peatland areas. Elevated TIC concentrations were associated with agricultural land in the catchment, whereas elevated TOC concentrations were observed in lakes with high peatland proportion in the catchment. Two contrasting important sources of CO₂ in lakes were identified on the basis of statistical analysis of the data; weathering processes in the catchments and decomposition of organic matter. CO₂ was also strongly associated with total nutrients TN and TP, implying the importance of quality of organic matter and availability of nutrients for the decomposition processes.