Search

Heat transfer experiment on water flow boiling was carried out in the upward direction under atmospheric pressure through a narrow rectangular channel heated on one-side by vapor having a gap of 2.75 mm, a width of 250 mm, and length of 1400 mm. The heat transfer coefficient and thermal hydraulic thresholds of the flow boiling in forced convective flow, such as the onset of nucleate boiling (ONB) and onset of fully developed nucleate boiling (OFDB) were investigated. The experiment was performed over a wide range of inlet temperature (75–95°C), mass flow rate (2–9 g/m), and heat fluxes (5–16 kW/m2). The effects of the parameters on the heat transfer coefficients have been discussed in detail. A series of ONB, FDB and heat transfer correlations were evaluated using the experimental data, and most of the correlations did not adequately fit the experimental results. A modified Hong et al. correlation and modified Zhu et al. correlation were used to predict the wall superheat at ONB and FDB respectively. The average errors (AEs) of the two correlations were 2.36% and −0.68%, and the root mean square errors (RMSEs) of them were both 14.00%. A modified Li and Wu correlation was used to predict heat transfer coefficients with the average error (AE) of 1.46% and the root mean square errors (RMSE) of 11.88%. [ABSTRACT FROM AUTHOR]

Freeze-drying is an effective method for aortal preservation. However, there are few studies on heat and mass transfer of aortal freeze-drying. In this study, the contactless weighing device was used to monitor freeze-drying process. The radiation view factor of the aortal segment was estimated, and the quasi-steady state model was used to analyze heat and mass transfer, there was a certain amount of heat flux in the frozen layer, which provided sublimation heat for internal sublimation interface. By theoretical calculation, the vapor diffusion coefficient was determined. The unsteady state model was used for numerical simulation. The simulated result of free water removal ratio was consistent with experiment result. Both heat flux density and mass flux density decreased non-linearly in the early stage, but approximately linearly in the late stage. The velocity of inner and outer sublimation interfaces was almost the same. The nodes temperature gradually increased and finally approached the heating temperature, and the temperature gradient of both dried and frozen layers decreased gradually with drying time. The water vapor pressure gradient was smaller near the aortal wall and larger in the middle region. [ABSTRACT FROM AUTHOR]

Freeze-drying is an effective method for preservation of aortas. In order to maintain the original properties of aortas, the sublimation drying process requires accurate monitoring. In this study, we used a contactless mass measurement device to monitor drying process, porcine aortic segments were divided into four series for freeze-drying, then relevant experiments and calculations were carried out to evaluate the quality of lyophilized samples. The study found that the sublimation process could not be accurately monitored by measured temperature, however, the real-time weighing could do it well, and was suitable to judge the endpoint of primary drying. Meanwhile, the change law of sublimation temperature was obtained by quasi-steady heat transfer equations. The removal ratio of free water during the primary drying greatly affected the properties of lyophilized samples, thorough sublimation had contributed to better performance of products, especially in mechanical properties. In addition, compared with annular aortic segments, the flaky samples had better heat transfer and performed better in histological scanning. [ABSTRACT FROM AUTHOR]

Purpose:The aim of this study was to test the validity and reliability of the translated Norwegian version of the Chronic Pain Acceptance Questionnaire (CPAQ-20) and the shorter version CPAQ-8 based on the same data. Method:The sample consisted of 120 women with chronic widespread musculoskeletal pain (CWP). The respondents completed CPAQ-20 and visual analogue scales (pain, fatigue, sleep problems and depression), General Health Questionnaire-12, The Pain Catastrophizing Scale, Fibromyalgia Impact Questionnaire and SF-8. Confirmatory factor analyses were performed on a one-factor baseline model, the previous validated CPAQ-20 and CPAQ-8 models, as well as an exploratory generated model based on the current sample. Results:The two-factor model of CPAQ-20 and a two-factor model of CPAQ-8 obtained adequate model fit and outperformed the baseline model. The exploratory factor, analysis-generated two-factor model obtained only a marginally better fit, supporting the two-dimensional model of CPAQ-20. CPAQ-20 and CPAQ-8 had Cronbach’s alphas between 0.75 (Pain Willingness subscales both versions) and 0.85. Both scales correlated significantly in the hypothesised direction with all the other scales. Conclusion:The Norwegian versions of CPAQ-20 and CPAQ-8 are reliable assessment tools with good construct validity for measurement of acceptance. Future studies should validate the scales in other Norwegian samples.Implication for RehabilitationCPAQ-20 and CPAQ-8 are valid Norwegian instruments for measuring acceptance of pain.Acceptance of pain is an important process in the rehabilitation of persons with chronic widespread pain.Treatment models supporting acceptance can now be developed and measured further in Norway. [ABSTRACT FROM PUBLISHER]

Purpose:Diagnostic and prognostic evaluation remains challenging in arrhythmogenic right ventricular cardiomyopathy (ARVC). We measured plasma concentration of soluble ST2 (sST2) and assessed its association with right ventricular (RV) function and ventricular arrhythmias in patients with ARVC. Methods:We included patients with ARVC and genotype positive relatives. Soluble ST2 was determined by ELISA. We assessed myocardial function by echocardiography including strain by speckle tracking technique. Results:We included 44 subjects (age 41 ± 15 years, 21 (48%) female). Soluble ST2 was associated with RV global strain (r = 0.44;p = 0.008), as well as with left ventricular (LV) function. Plasma levels of sST2 were higher in patients with ventricular arrhythmias than in patients without ventricular arrhythmias (35 ± 13 ng/mL vs. 26 ± 7 ng/mL,p = 0.009). The association between sST2 and ventricular arrhythmias remained significant even after adjusting for RV function (Wald = 5.2;p = 0.02). Conclusions:Soluble ST2 is associated with RV and LV function in patients with ARVC. Soluble ST2 may aid in the determination of disease severity in ARVC. [ABSTRACT FROM PUBLISHER]

Familial lecithin:cholesterol acyltransferase (LCAT) deficiency is a rare metabolic disease with lipid deposition in several organs. The authors report a man with hypertension and proteinuria. Renal biopsy revealed glomerular changes, including peculiar thrombus-like deposits, consistent with LCAT deficiency. He was found to be compound heterozygous for two mutations of the LCAT gene. He received a kidney graft from his father. The authors also describe LCAT deficiency-related lesions in the explanted native kidneys and in biopsies at 2 days, 6 weeks, and 1 year after transplantation. The morphology of this disease is characteristic, and the diagnosis should be suspected from the ultrastructural findings. [ABSTRACT FROM AUTHOR]

Objective. Our study aimed to investigate the relationship between exercise-induced pulmonary arterial hypertension and genetic changes related to the transforming growth factor-β (TGF-β) signalling pathway in patients with cardiac septal defects. Design. In a population-based group of 44 patients (age 13-25 years) with either isolated ventricular septal defect (n=27) or isolated atrial septal defect (n=17), right ventricular systolic pressure response to submaximal exercise was studied by echocardiography and classified as normal (≤45 mmHg), borderline (45-50 mmHg) or abnormal (>50 mmHg). Three genes related to TGF-β, bone morphogenetic protein receptor type 2 (BMPR2), activin receptor-like kinase 1 (ALK1) and endoglin (ENG), were analyzed by DNA sequencing (only BMPR2) and multiplex ligand-dependent probe amplification (BMPR2, ALK1 and ENG). Results. Pressure response was borderline in five and abnormal in nine patients. Five patients showed mutations in exon 12 of the bone morphogenetic protein receptor type 2 gene. The previously described polymorphism S775N (c. 2324, G > A) was found in three patients with normal pressure response. The mutation Y589C (c. 1766, A > G), which has not been described previously, was found in two of 14 patients with borderline/abnormal pressure response. Conclusion. Genetic changes in the BMPR2 gene may be overrepresented in patients with cardiac septal defects and exercise-induced pulmonary hypertension. [ABSTRACT FROM AUTHOR]

Abstract Severe to profound hearing impairment (HI) is estimated to affect around 1/2000 young children. Advances in genetics have made it possible to identify several genes related to HI. This information can cast light upon prognostic factors regarding the outcome in cochlear implantation, and provide information both for scientific and genetic counselling purposes. From 1992 to 2005, 273 children from 254 families (probands) were offered cochlear implants in Norway. An evaluation of the causes of HI, especially regarding the genes GJB2, GJB6, SLC26A4, KCNQ1, KCNE1, and the mutation A1555G in mitochondrial DNA was performed in 85% of the families. The number of probands with unknown cause of HI was thus reduced from 120 to 68 (43% reduction). Ninety-eight (46%) of the probands had an identified genetic etiology of their HI. A relatively high prevalence of Jervell and Lange-Nielsen syndrome was found. The main causes of severe and profound HI were similar to those found in other European countries. GJB2 mutations are a common cause of prelingual HI in Norwegian cochlear implanted children. Sumario Se estima que la hipoacusia (HI) severa a profunda afecta alrededor de 1/2000 niños pequeños. Los avances en la genética han hecho posible la identificación de varios genes relacionados con HI. Esta información puede proporcionar luz en los factores pronóstico relacionados con el resultado de los implantes cocleares, y dar información tanto para fines científicos como para asesoramiento genético. De 1992 a 2005, a 273 niños de 254 familias (propósitos) se les ofreció un implante coclear en Noruega. Una evaluación de las causas de la HI, especialmente de los genes GJB2, GJB6, SLC26A4, KCNQ1, KCNE1 y la mutación A1555G del DNA mitocondrial se realizó en 85% de las familias. El número de propósitos con causa desconocida de HI se redujo de 120 a 68 (reducción del 43%). Noventa y ocho (46%) de los sujetos tuvieron una causa genética identificada. Se encontró una prevalencia relativamente alta del Síndrome de Jervell and Lange Nielsen. Las principales causas de la HI severa a profunda fueron similares a las encontradas en los países Europeos. Las mutaciones de GJB2 son una causa común de hipoacusia pre-lingüística en niños noruegos con implante coclear. [ABSTRACT FROM AUTHOR]

Objective. The objective of this project was to determine whether nonsense mutation in the low density lipoprotein receptor (LDLR) induces nonsense-mediated mRNA decay (NMD). Material and methods. Four known nonsense mutations (W23X, S78X, E207X and W541X) in the LDLR gene, which are found in Norwegian familial hypercholesterolaemia (FH) patients, were investigated. Epstein-Barr virus (EBV) transformed lymphocytes from patients heterozygous for these mutations in the LDLR gene were analysed. Flow cytometric analysis was used to determine the amount and function of the cell surface LDLRs. The expression of LDLR mRNA in lymphocytes was quantified by real-time polymerase chain reaction (PCR). The presence of NMD was tested using the inhibitors gentamicin, emetine or cycloheximide. Results. Cells from heterozygous FH patients with nonsense mutations in the LDLR gene contained significantly less LDLR protein (p<0.05). In addition, flow cytometric analysis revealed that these patients had a reduced LDL-uptake compared to controls (p<0.005). Cells from heterozygous FH patients with nonsense mutations W23X, S78X or W541X in the LDLR gene showed significantly decreased levels of LDLR mRNA (p<0.005). LDLR mRNA was reduced in the mutant lymphocyte S78X prior to treatment with pharmacological inhibitors, and after treatment the level of LDLR mRNA increased to the same level as that of normal cells. Conclusion. In the present study, NMD was confirmed in the LDLR gene. Translation inhibitors showed reduced NMD caused by nonsense mutated LDLR transcripts. Knowledge of NMD might have an important impact in clinical medicine as genetic intervention develops. [ABSTRACT FROM AUTHOR]

Mutations in the KCNQ1, HERG, SCN5A, minK and MiRP1 genes cause long QT syndrome (LQTS), of which there are two forms: the Romano Ward syndrome and the Jervell and Lange-Nielsen syndrome. We have performed DNA sequencing of the LQTS-associated genes in 169 unrelated patients referred for genetic testing with respect to Romano Ward syndrome and in 13 unrelated patients referred for genetic testing with respect to Jervell and Lange-Nielsen syndrome. A total of 37 different mutations in the 5 genes, of which 20 were novel, were identified. Among patients with the most stringent clinical criteria of Romano Ward syndrome, a mutation was identified in 71 %. Twelve of the 13 unrelated patients referred for genetic testing with respect to Jervell and Lange-Nielsen syndrome were provided with a molecular genetic diagnosis. Cascade genetic screening of 505 relatives of index patients with molecularly defined LQTS identified 251 mutation carriers. The observed penetrance was 41 %. Although caution must be exerted, the prevalence of heterozygotes for mutations in the LQTS-associated genes in Norway could be in the range 1/100-1/300, based on the prevalence of patients with Jervell and Lange-Nielsen syndrome. [ABSTRACT FROM AUTHOR]

The article discusses the importance of student's participation in various school activities particularly in school administration and curriculum planning. It mentions that a healthy relationship between students and teachers is important to develop an effective learning environment. Participation of students in the decision-making body of the school will result to successful improvement programs which will give way to an educational change. Student government is vital in cultivating student voice which will promote school reforms.

Objective: Missense mutations in the proprotein convertase subtilisin/kexin type 9 (PCSK9) gene have been found to cause autosomal dominant hypercholesterolemia. The objective of this study was to investigate possible mechanisms by which mutation D374Y in the PCSK9 gene causes hypercholesterolemia. Material and Methods: Binding and internalization of low-density lipoprotein LDL in Epstein-Barr virus (EBV)-transformed lymphocytes from D374Y heterozygotes were examined. The autocatalytic activity of the D374Y mutant was studied in transiently transfected HEK293 cells. Results: As determined by Western blot analysis of transiently transfected HEK293 cells, the autocatalytic activity of the D374Y mutant was approximately 95% of the wild-type. Levels of PCSK9 mRNA in EBV-transformed lymphocytes from D374Y heterozygotes and normal controls were similar and less than 1/1000 of the level in HepG2 cells. The amount of cell surface LDL receptors (LDLRs) in EBV-transformed lymphocytes from five D374Y heterozygotes was non-significantly increased by 17% compared with the amount in normal controls. LDLR-dependent binding and internalization of LDL in EBV-transformed lymphocytes from D374Y heterozygotes were non-significantly reduced by 11% and 12%, respectively, compared to the corresponding values in normal controls. Conclusions: LDLR-mediated endocytosis of LDL is not reduced in EBV-transformed lymphocytes from D374Y heterozygotes. Because of the extremely low levels of PCSK9 mRNA in EBV-transformed lymphocytes, it is possible that the LDLR-dependent endocytosis of LDL could be more severely affected in hepatocytes from D374Y heterozygotes than in EBV-transformed lymphocytes. [ABSTRACT FROM AUTHOR]

Objectives: To explore changes in the incidence of fatal and nonfatal myocardial infarction (MI) and stroke in the same male population over two decades.Design: Men aged 40-49 born in the years 1923-1932 (N= 16,209) resident in Oslo participated in a cardiovascular screening programme in 1972-1973. Nonfatal cases of MI and stroke were obtained from hospital records and causes of death were ascertained by linkage to Statistics Norway. The closing date was December 31, 1993.Results: The cohort had a lower mortality rate than the general Norwegian population. First nonfatal and fatal MIs declined in each age and birth cohort during the entire follow-up. The incidence of nonfatal and fatal stroke decreased about 10 years after the initial screening. The risk of men with Rose questionnaire-based symptoms of angina or claudication was between that of healthy men and men with established cardiovascular disease or diabetes.Conclusions: There has been a reduction in both nonfatal and fatal incident cases of MI and stroke 10 years later indicating a pronounced change in all age groups and a lasting change throughout the period of follow-up. The Rose questionnaire predicted both future stroke and MI. [ABSTRACT FROM AUTHOR]