Regular folding in solution-grown polyethylene crystal, 1. Model description

To re-consider the idea that a polymer chain should fold regularly rather than randomly, the pair s-chain crystalline growth philosophy was suggested. On the basis of this philosophy, the coordinated pair chain folding model (CPCFM) for polyethylene (PE) polymer single crystal is proposed, with the paired chain folding on average along the (110) plane of the orthorhombic crystal lattice and each of the coordinated pair chains folding alternatively at (100) and (010) planes. Being a regular folding model, the CPCFM explains most of the regular shapes of PE single crystals including lamellar diamond shape, flat based and non-flat based hollow pyramidal shapes, saddle shape, truncated diamond shape as well as twin crystal via either the single-chain nucleus or the two-chain nucleus. The folding conformation energies for the folds in a CPCFM are lower than those for conventional adjacent (110) folds. The configuration and conformation mentioned above, together with other evidences, discussed in part 2 of this series and an earlier communication make the CPCFM an acceptable regular folding model.     

Recurrent papilloedema and early onset optic atrophy in Beh?et's syndrome.

Two patients with Behçet''s syndrome and intracranial hypertension are reported. One developed a recurrence of papilloedema while receiving treatment but eventually made a full recovery, whereas the other developed optic atrophy within three months of onset despite treatment.     

Predictive testing for multiple endocrine neoplasia type 1 using DNA polymorphisms.

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominantly inherited predisposition to neoplastic lesions of the parathyroids, pancreas, and the pituitary. We have previously located the predisposing genetic defect to the long arm of chromosome 11 by genetic linkage. In this study, 124 members of six MEN1 families, including 59 affected individuals, were genotyped for restriction fragment length polymorphisms with different DNA probes, and the genetic linkage between these marker systems and MEN1 was determined. 13 marker systems (17 DNA probes) were found to be linked to MEN1. These markers are located within a region on chromosome 11 spanning 14% meiotic recombinations, with the MEN1 locus in the middle. Four of the marker systems are on the centromeric side of MEN1, and four on the telomeric side, based on meiotic crossovers. The remaining five DNA probes are closely linked to MEN1, with no crossovers in our set of families. The 13 marker systems can be used for an accurate and reliable premorbid test for MEN1. In most clinical situations it is possible to identify a haplotype of this part of chromosome 11 with the mutant MEN1 allele in the middle. The calculated predictive accuracy is greater than 99.5% if three such marker systems are informative. Therefore, genetic linkage testing can be used for informed genetic counseling in MEN1 families, and to avoid unnecessary biochemical screening programs.     

预测急性呼吸窘迫综合征发生及死亡的临床指标:红细胞输注的潜在作用

急性呼吸窘迫综合征(acute respiraory distress syndrome,ARDS)是一种常见的严重肺功能紊乱的肺部并发症。常并发于脓毒血症、创伤和抽吸术等严重损伤后。ARDS的发生及死亡率可因发生ARDS损伤类型的不同而有差别,提示ARDS的发病机制和预后因临床风险因素而不同。最近,对重症病人进     

Translational genomics to develop a Salmonella enterica serovar Paratyphi A multiplex polymerase chain reaction assay

The use of pathogen genome sequence data for the control and management of infections remains an ongoing challenge. We describe a broadly applicable, web-enabled approach that can be used to develop bacteria-specific polymerase chain reaction (PCR) assays. Salmonella enterica Paratyphi A has emerged as a major cause of enteric fever in Asia. Culture-based diagnosis is slow and frequently negative in patients with suspected typhoid and paratyphoid fever, potentially compromising patient management and public health. We used the MobilomeFINDER web-server to perform in silico subtractive hybridization, thus identifying 43 protein-coding sequences (CDSs) that were present in two Paratyphi A strains but not in other sequenced Salmonella genomes. After exclusion of 29 CDSs found to be variably present in Paratyphi A strains by microarray hybridization and grouping of remaining CDSs by genomic location, four dispersed targets (stkF, spa2473, spa2539, hsdM) were used to develop a highly discriminatory multiplex PCR assay. All 52 Paratyphi A strains within the diverse panel investigated produced one of two pathognomonic four-band signatures. Given rapid and ongoing expansion of DNA and comparative genomics databases, our universally accessible web-server-supported do-it-yourself approach offers the potential to contribute significantly to the rapid development of species-, serovar-, or pathotype-specific PCR assays targeting pre-existing and emerging bacterial pathogens.     

Single step PCR for detection of allelic variation of MDR1 gene (P-glycoprotein) among three ethnic groups in Malaysia

BACKGROUND: P-glycoprotein (PgP) is the most extensively studied ATP-binding cassette (ABC) coded by MDR1 gene. To date, 29 single nucleotide polymorphisms (SNPs) have been identified; but only SNP C3435T has been correlated with intestinal PgP expression levels and shown to influence the absorption of orally taken drugs that are PgP substrates. Individuals homozygous for the T allele have more than fourfold lower PgP expression compared with C/C individuals. We developed a one step primer based allele specific PCR method to detect SNP at C3435T to investigate the distribution of this genotype in the local population. METHOD: DNA was extracted from 5 mL of whole blood using standard salting-out method. Primers were designed specific to 3' end which amplify the variants of C3435T. The method was validated by direct DNA sequencing. Seven hundred and sixty-three healthy blood donors comprising of three major ethnic groups in Malaysia were recruited and DNA subjected to genotyping of C3435T using this method. RESULT: The method was found to be robust and reproducible in detecting SNP of C3435T. Interethnic variations in genotype and allele frequency were observed in PgP among the ethnic groups. In comparison to both the Caucasians and the other Asian countries, the Malay and Chinese showed a higher frequency of allele C (50-60%); while the Indian exhibits a lower frequency (40%), similar to other Indian populations. DISCUSSION AND CONCLUSION: Using a new simple method to investigate the distribution of C3435T, we found that the allele frequency of MDR1 showed variablity between the different ethnic groups within the Malaysian population.     

Characterization of a new SNP c767A/T (Arg222Trp) in the candidate TSG FUS2 on human chromosome 3p21.3: prevalence in Asian populations and analysis of association with nasopharyngeal cancer

The FUS2 gene, encoding a novel cytoplasmic acetyltransferase, resides in the tumor suppressor gene region on human chromosome 3p21.3 and is considered a promising candidate tumor suppressor gene. We have identified a new single nucleotide polymorphism (SNP), c767A/T, in the coding region of the gene. The polymorphism leads to a non-conservative amino acid change (R222W) located between the acetyltransferase (GNAT) and the proline-rich domains of the protein. We have analyzed 254 subjects included in 14 sub-populations. The occurrence of the SNP varies with the ethnicity of the population, suggesting that this SNP could be a valuable biomarker for population genetics. It is most prevalent in various Asian populations (T allele frequency>0.54), followed by the Canadian polar Inuit (T allele frequency=0.3), African American (T allele frequency=0.17), and Caucasian population (T allele frequency=0.1). Since nasopharyngeal carcinoma (NPC) is frequent in Southern China, Taiwan, Borneo and polar Canada, we further tested for the possible association of the FUS2 SNP with this form of endemic cancer. Our analysis, albeit limited, suggests no likely association between NPC and the FUS2 gene polymorphism. Further large-scale case-control studies are necessary and warranted to prove the strength of this contention.     

Correlation between clinical indication for treatment and liver histology in HBeAg‐negative chronic hepatitis B: a novel role of α‐fetoprotein

Background: It is unclear whether clinical indication for antiviral treatment is in agreement with histological indication in HBeAg‐negative chronic hepatitis B (CHB). This study aimed to clarify this relationship and identify factors associated with liver histology. Patients and methods: We investigated 152 consecutive, treatment‐naïve, HBeAg‐negative CHB patients who had undergone liver biopsies at a tertiary medical centre in Taiwan. Clinical indications for treatment included a serum alanine aminotransferase level more than twice the upper limit of normal and an hepatitis B virus DNA level >2000 IU/ml. Factors associated with the histological indication (Ishak's grade ≥7 and/or stage ≥2) were analysed. Results: The association between the clinical and the histological indications was significant (P=0.011). However, the agreement was poor (κ value=0.197). In patients satisfying the clinical indication, age >52 years [odds ratio (OR)=2.669, P=0.042], serum α‐fetoprotein (AFP) level >7 ng/ml (OR=7.070, P<0.001) and platelet count <130 × 10⁹/L (OR=11.720, P=0.025) were identified to be independent factors associated with histological indication. In patients who did not satisfy the clinical indication, multivariate analysis revealed that only an AFP level >7 ng/ml (OR=10.345, P=0.021) was independently associated with histological indication. Combining the clinical indication and/or AFP level >7 ng/ml to predict liver histology, the sensitivity and the negative predictive value could improve from 86 to 94.4% and 66.7 to 81% respectively. Conclusion: AFP level is associated with liver histology in HBeAg‐negative CHB. Serum AFP level can serve as a surrogate indicator to identify patients who need antiviral treatment.     

Major gastrointestinal manifestations in lupus patients in Asia: lupus enteritis, intestinal pseudo-obstruction, and protein-losing gastroenteropathy

Gastrointestinal (GI) symptoms are common in patients with systemic lupus erythematosus (SLE) and may be due to the disease itself, side-effects of medications, or non-SLE causes. However, GI manifestations of lupus attract far less attention than the other major organ involvements, are infrequently reviewed and rarely documented in published lupus databases or cohort studies including those from countries in Asia. According to three reports from two countries in Asia, the cumulative prevalence of SLE GI manifestations range from 3.8% to 18%. In this review, we focus on three major GI manifestations in patients from Asian countries: lupus enteritis, intestinal pseudo-obstruction, and protein-losing gastroenteropathy, for which early recognition improves outcome and reduces morbidity and mortality.