Review on the durability of exterior wood coatings with reduced VOC-content

The main factors that contribute to the durability of exterior wood coatings are discussed with special emphasis on the recent developments to reduce the volatile organic compound (VOC) content in these types of coating like water-borne acrylic dispersions, water-borne alkyds or high solid alkyd formulations. The performance of a coating during outdoor weathering is determined by: photochemical degradation (only for paints that are not opaque), moisture permeability in relation to wood-moisture content and dimensional change and the microbiological degradation at the wood–coating interface. The results from various outdoor weathering studies are discussed. These studies show fairly consistent results with respect to the influence of coating type or wood species. However, a sound theory about the mechanism of failure, that can related to basic properties of the coating or the binder, has not yet been established.     

Benecol®—一种有效、安全降低血清胆固醇水平的独特食品配料

在世界范围内,心血管疾病——冠心病(CHD)、中风、周围动脉疾病的患病数量正在增加.据世界卫生组织(WHO)统计估计,每年大约有1600万人死于各种形式的心血管疾病.高血清胆固醇是导致各种心血管疾病的主要危险因素之一.近来,通过饮食方法如功能食品来降低胆固醇水平已经引起了极大关注.植物甾醇和植物甾烷醇是动物胆固醇的植物等价物,因为它们在植物细胞中的作用与胆固醇在动物细胞中的作用是一样的.如果在日常的饮食当中含有足量的植物甾醇或植物甾烷醇,则它们可以有效地降低胃肠道中对胆固醇的吸收量,从而降低血清胆固醇浓度.植物甾烷醇酯是世界上第一个基于植物甾醇的降低胆固醇的商业食品配料.1995年芬兰首次生产出添加植物甾烷醇酯的降胆固醇食品.如今,在全世界的24个国家销售Benecol品牌的各种植物甾烷醇酯强化食品,包括植物黄油、酸奶、牛奶、橙汁、通心粉等.Benecol食品含有植物甾烷醇酯,专门针对想通过饮食方法降低血清胆固醇水平的人群.植物甾烷醇酯的安全性已经得到了严格的安全性测试,并得到了40多项人体临床研究的证实.国际专业团体已经充分肯定了植物甾烷醇酯食品的降低胆固醇的功效.     

Limited oral bioavailability and active epithelial excretion of paclitaxel (Taxol) caused by P-glycoprotein in the intestine

In mice, the mdr1a and mdr1b genes encode drug-transporting proteins that can cause multidrug resistance in tumor cells by lowering intracellular drug levels. These P-glycoproteins are also found in various normal tissues such as the intestine. Because mdr1b P-glycoprotein is not detectable in the intestine, mice with a homozygously disrupted mdr1a gene [mdr1a(-/-) mice] do not contain functional P-glycoprotein in this organ. We have used these mdr1a(-/-) mice to study the effect of gut P-glycoprotein on the pharmacokinetics of paclitaxel. The area under the plasma concentration-time curves was 2- and 6-fold higher in mdr1a(-/-) mice than in wild-type (wt) mice after i.v. and oral drug administration, respectively. Consequently, the oral bioavailability in mice receiving 10 mg paclitaxel per kg body weight increased from only 11% in wt mice to 35% in mdr1a(-/-) mice. The cumulative fecal excretion (0-96 hr) was markedly reduced from 40% (after i.v. administration) and 87% (after oral administration) of the administered dose in wt mice to below 3% in mdr1a(-/-) mice. Biliary excretion was not significantly different in wt and mdr1a(-/-) mice. Interestingly, after i.v. drug administration of paclitaxel (10 mg/kg) to mice with a cannulated gall bladder, 11% of the dose was recovered within 90 min in the intestinal contents of wt mice vs. <3% in mdr1a(-/-) mice. We conclude that P-glycoprotein limits the oral uptake of paclitaxel and mediates direct excretion of the drug from the systemic circulation into the intestinal lumen.     

Reocclusion: the flip side of coronary thrombolysis

Since the introduction of thrombolytic therapy for acute myocardial infarction, the incidence of coronary artery reocclusion has been intensively studied. Also, the prediction and diagnosis of reocclusion by angiographic and clinical variables, as well its invasive and pharmacologic prevention, have gained much attention. By angiographic definition, reocclusion requires three angiographic observations: one with an occluded artery, one with a reperfused artery and a third for the assessment of subsequent occlusion (true reocclusion). Since the introduction of early intravenous reperfusion therapy, most studies use only two angiograms: one with a patent and one with a nonpatent infarct-related artery. A search for all published reocclusion studies revealed 61 studies (6,061 patients) with at least two angiograms. The median time interval between the first angiogram after thrombolysis and the second was 16 days (range 0.1 to 365). Reocclusion was observed in 666 (11%) of 6,061 cases. Interestingly, the 28 true reocclusion studies showed an incidence of reocclusion of 16 +/- 10% (mean +/- SD), and the 33 studies with only two angiograms 10 +/- 8% (p=0.04), suggesting that proven initial occlusion of the infarct-related artery is a risk factor for reocclusion after successful thrombolysis. The other predictors for reocclusion are probably severity of residual stenosis of the infarct-related artery after thrombolysis and perhaps the flow state after lysis. Reocclusion is most frequently seen in the early weeks after thrombolysis. The clinical course in patients with reocclusion is more complicated than in those without this complication. Left ventricular contractile recovery after thrombolysis is hampered by reocclusion. Routine invasive strategies have not been proven effective against reocclusion. In the prevention of reocclusion, both antiplatelet and antithrombin strategies have been tested, including hirudin and hirulog, but the safety of these agents in thrombolysis is still questionable. Thus, reocclusion after thrombolysis is an early phenomenon and is more frequent after proven initial occlusion of the infarct-related artery. Reocclusion can be predicted by angiography after thrombolysis. Because reocclusion is detrimental, strategies to prevent it should be developed and carried out after thrombolytic therapy for acute myocardial infarction as soon as they are deemed safe.     

Benign anal lesions, inflammatory bowel disease and risk for high-risk human papillomavirus-positive and -negative anal carcinoma

A central role in anal carcinogenesis of high-risk types of human papillomaviruses (hrHPV) was recently established, but the possible role of benign anal lesions has not been addressed in hrHPV-positive and -negative anal cancers. As part of a population-based case-control study in Denmark and Sweden, we interviewed 417 case patients (93 men and 324 women) diagnosed during the period 1991-94 with invasive or in situ anal cancer, 534 patients with adenocarcinoma of the rectum and 554 population controls. Anal cancer specimens (n = 388) were tested for HPV by the polymerase chain reaction. Excluding the 5 years immediately before diagnosis, men, but not women, with anal cancer reported a history of haemorrhoids [multivariate odds ratio (OR) 1.8; 95% confidence interval (CI) 1.04-3.2] and unspecific anal irritation (OR 4.5; CI 2.3-8.7) significantly more often than controls. Women with anal cancer did not report a history of benign anal lesions other than anal abscess to any greater extent than controls, but they had used anal suppositories more often (OR 1.5; CI 1.1-2.0). Patients with hrHPV in anal cancer tissue (84%) and those without (16%) reported similar histories of most benign anal lesions, but anal fissure or fistula was more common among hrHPV-positive cases. Ulcerative colitis and Crohn's disease, reported by <1% of study participants, were not associated with anal cancer risk. The higher proportion of hrHPV-positive anal cancers among case patients with anal fissure or fistula suggests that such mucosal lesions may provide direct viral access to basal epithelial layers. Since risk associations with benign anal lesions in men may be confounded by unreported sexual behaviour, and since risk associations in women were generally negative, it seems unlikely that benign anal lesions act as promoters in hrHPV-associated anal carcinogenesis. Moreover, benign anal lesions appear not to be linked to an alternative, hrHPV-unassociated causal pathway to anal cancer. Ulcerative colitis and Crohn's disease were not supported as causal factors for anal cancer.     

Low intercellular adhesion molecule 1 and high 5T4 expression on tumor cells correlate with reduced disease-free survival in colorectal carcinoma patients

The purpose of this study was to investigate the prognostic value of the expression of intercellular adhesion molecule 1 (ICAM-1), leukocyte function antigen 3 (LFA-3), human leukocyte differentiation antigen (HLA)-ABC, HLA-DR, and 5T4 with regard to disease-free survival in Dukes' B and C colorectal carcinoma patients. Forty-one patients (28 Dukes' B and 13 Dukes' C) were entered into this study. Immunocytochemistry was performed on cytospin preparations of enzymatically digested colorectal carcinoma cell suspensions. The frequency of metastases and the duration of disease-free survival were compared between the 25% lowest expressers and the 75% remaining patients for ICAM-1, LFA-3, HLA-ABC, and HLA-DR, and between the 25% highest expressers and the 75% remaining patients for 5T4. Low numbers of ICAM-1-expressing tumor cells were associated with a shorter disease-free survival (P < 0. 001), independent of Dukes' stage. High numbers of 5T4-expressing tumor cells were associated with shorter disease-free survival in Dukes' B patients (P = 0.04). Cox proportional hazard analysis indicated that low numbers of ICAM-1(+) and high numbers of 5T4(+) cells were independent prognostic factors with relative risks of 13. 0 (P = 0.0002) and 4.7 (P = 0.02), respectively. The combination of 5T4 and ICAM-1 marker information identified subgroups of patients with a good (high ICAM-1) or poor (low ICAM-1/high 5T4) prognosis. Neither a lack of HLA-ABC and LFA-3 expression nor the presence of HLA-DR on the tumor cells gave additional prognostic information. These findings demonstrate that low ICAM-1 and high 5T4 expression on tumor cells are prognostic markers, additional to Dukes' stage, for reduced disease-free survival in Dukes' B and C colorectal carcinoma patients.     

Do HPV-negative cervical carcinomas exist?

Based on improvements in HPV detection technology, it appears that an almost 100% HPV association is reached for cervical cancer, as demonstrated in an accompanying paper in this issue of the Journal. Factors which may explain the rare cases in which no HPV DNA is detectable include: improper sampling; disruption of HPV by integration events; the existence of still unidentified HPVs; sensitivity of the method; and the mechanism of transformation. Finally, epidemiological studies identifying HPV independent risk factors are necessary to answer the question of whether HPV independent pathways exist for cervical carcinogenesis.     

Differential induction of inositol phosphate metabolism by three adipokinetic hormones

Sheep naturally infected by visna-maedi virus often develop a chronic interstitial lung disease characterized by an alveolitis comprising lymphocytes, neutrophils and macrophages. The alpha chemokine interleukin-8 (IL-8) was detected in cell free bronchoalveolar lavage fluid from naturally infected animals, confirmed by RT-PCR, presenting typical lesions of maedi and elevated total alveolar cell counts. No detectable IL-8 was found in the fluid obtained from uninfected animals. IL-8 concentration in alveolar fluid is correlated with alveolar neutrophil counts. Bronchoalveolar lavage cells from infected animals were found to contain a large amount of IL-8 mRNA and may contribute to IL-8 production. In situ hybridization showed that macrophages were the predominant cell type expressing IL-8 mRNA. Sustained production of IL-8 by alveolar macrophages during visna-maedi infection could suffice for neutrophil attraction to the alveoli, and may contribute to the development of lesions.     

Primary structure and phylogeny of the Calvin cycle enzymes transketolase and fructosebisphosphate aldolase of Xanthobacter flavus

Xanthobacter flavus, a gram-negative facultatively autotrophic bacterium, employs the Calvin cycle for the fixation of carbon dioxide. Cells grown under autotrophic growth conditions possess an Fe(2+)-dependent fructosebisphosphate (FBP) aldolase (class II) in addition to a class I FBP aldolase. By nucleotide sequencing and heterologous expression in Escherichia coli, genes encoding transketolase (EC 2.2.1.1.; CbbT) and class II FBP aldolase (EC 4.1.2.13; CbbA) were identified. A partial open reading frame encoding a protein similar to pentose-5-phosphate 3-epimerase was identified downstream from cbbA. A phylogenetic tree of transketolase proteins displays a conventional branching order. However, the class II FBP aldolase protein from X. flavus is only distantly related to that of E. coli. The autotrophic FBP aldolase proteins from X. flavus, Alcaligenes eutrophus, and Rhodobacter sphaeroides form a tight cluster, with the proteins from gram-positive bacteria as the closest relatives.