Differentiation of Helicobacter pylori isolates by polymerase chain reaction—restriction fragment length polymorphism

Objective: To investigate the association between the diversity of urease gene and urease activity of clinical isolates of Helicobacter pylori (H. pylori). Methods: Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of urease gene and rapid urease activity test were used to study the urease activity of different clinical isolates of H. pylori. Results: H. pylori clinical isolates were divided into 4 types according to their PCR-RFLP results of urease gene and urease activity. Type Ⅰ , possessing strong urease activity (0. 11) and presented 1 fragment of 1. 7 kb by PCR-RFLP, had close relations with gastric ulcer; type Ⅱ , with the weakest urease activity (0. 07) and 2 fragments (1. 3 and 0. 4 kb respectively) , was associated with duodenal bulb ulcer; type Ⅲ , with the strongest urease activity (0. 12) and 2 fragments (0. 4 and 0. 17 kb) with or without 1 fragment (0. 23 or 0. 37 kb) , was responsible for gastritis; type Ⅳ , with weak urease activity (0. 09) and 2 fragments     

The nature of polymorphism of the HLA-DRB intron sequences is lineage specific

Abstract: The sequence database of HLA-DRB genes is mainly derived from mRNA analysis or has focused exclusively on the polymorphism of the 2nd exon. Little is known about the non-coding sequences of the different DRB alleles which represent about 94% of the genes. In this study we have determined the sequence of the 3' 500 bp intron 1 fragment adjacent to exon 2 in all serologically defined HLA-DRB genes and their most frequent allelic subtypes. The intron sequences turned out to be highly polymorphic. Similar to the class I introns, this variability was not characterized by random point mutations but by a highly systematic diversity reflecting the lineage-specific relationship of the HLA-DR alleles. With a few exceptions in DRB1*15, 13 and 08 as well as DRB 4 and 5, the variability mirrors the serological diversity. As well as delivering insight into the genetic relationship between the different DRB alleles, these sequences will provide an extremely valuable basis for developing advanced DRB sequencing strategies for clinical purposes.     

Hepatitis B virus genetic diversity and its impact on diagnostic assays

Summary.  Hepatitis B virus (HBV) circulates in blood as closely related, but genetically diverse molecules called quasispecies. During replication, HBV production may approach 10¹¹ molecules/day, although during peak activity this rate may increase 100–1000 times. Generally, DNA polymerases have excellent fidelity in reading DNA templates because they are associated with an exonuclease which removes incorrectly added nucleotides. However, the HBV-DNA polymerase lacks fidelity and proofreading function partly because exonuclease activity is either absent or deficient. Thus, the HBV genome and especially the envelope gene, is mutated with unusually high frequency. These mutations can affect more than one open reading frame because of overlapping genes. The S gene contains an exposed major hydrophilic region (residues 110–155), which encompasses the 'a' determinant that is important for inducing immunity. Nucleotide substitutions in this region are common and result in reduced binding or failure to detect hepatitis B surface antigen (HBsAg) in diagnostic assays. Adaptive immunity also depends on the recognition of HBsAg by specific antibody and variants pose a threat if they interfere with binding to antibody. Finally, genomic hypervariability allows HBV to escape selection pressures imposed by antiviral therapies, vaccines and the host immune system, and is responsible for creating genotypes, subgenotypes and subtypes.     

HLA-DR 52- and 51-associated DRB1 alleles in Kenya, East Africa

The genes of the major histocompatibility complex (MHC) are amongst the most polymorphic loci known in the human population. The population genetics of the MHC encoded HLA loci of sub-Saharan Africa are of major interest because of their particular genetic diversity. Here we report on the HLA-DR 52- and 51-associated determinants of the DRB1 loci observed in 165 East African individuals studied in Nairobi, Kenya. The HLA-DR typing was done by serologic and by molecular DNA techniques (PCR-SSOP). The most frequent allele identified was DRB1*1101, followed by DRB1*1503 and DRB1*1302. Some unexpected alleles were repeatedly identified: DRB1*1108, DRB1*1316 and DRB1*1421. Most oftheDR 52-and 51-associated DRB1 alleles were correctly identified by serology as part of the DR3, DR5, DR6 and DR2 groups respectively. The HLA-DRB1 profile reported here corroborates previous genetic and linguistic data supporting the concept that the Eastern African Black population is genetically distinct from other African Black populations. This has important implications in public health issues related to the genetic profile of a population (transplantation, vaccine design for example).     

Ethnic Minorities, Migration and Risk of Undernutrition in Children

Well-controlled, comparative studies suggest that in "food rich" or "resource rich" environments, ethnic minority status is not an independent risk factor for malnutrition. In England, Australia, and the United States, nutrient intake, nutritional status measures and growth are comparable between children of ethnic minorities and non-minority children of similar economic status. Children of recent immigrants are an exception to this generalization, suggesting that recent arrival in a new environment is a risk factor for malnutrition. Family-level studies of intraethnic diversity are required to develop more sensitive and specific profiles of risk factors for malnutrition.     

Multicultural Health Care in Practice

This study presents a first assessment of the challenges faced by Dutch health care providers dealing with the increasing cultural diversity in Dutch society. Qualitative interviews with 24 Dutch caregivers and policy-makers point to a number of important difficulties encountered when confronted with the growing diversity of patient populations. The study focuses explicitly on the challenges health care providers perceive in their direct interactions with patients. On the basis of the observations of the 24 respondents five strategies were formulated to improve the delivery of care in a multicultural environment. Their findings were further evaluated by confronting the empirical data with care-ethical notions (attentiveness, responsibility, competence, and responsiveness) and intercultural communication-theory.     

Diversity in Clinical Psychology

Clinical psychology is not as diverse as society, and the generalizability of clinical psychology to diverse groups has largely been untested. Some progress has been made in increasing the number of ethnic minorities receiving PhD degrees in clinical psychology and in increasing ethnic minority representation in clinical trials. Nevertheless, clinical psychologists and clinical psychology research are not diverse. A stages of change model may be useful in motivating clinical psychologists to diversify. A future scenario involving inertia and a second involving change are offered.     

利用SRAP和ISSR标记分析川党参的 遗传多样性

目的:川党参Codonopsis tangshen的遗传多样性研究.方法:对18个不同来源地的川党参种质进行SRAP(sequence-related amplified polymorphism),ISSR (inter simple sequence repeat)分析.利用TREECONW软件分析遗传相似系数,UPGMA方法构建亲缘关系系统图.结果:29条SRAP引物组合共得到329条扩增条带,其中有266条呈现多态性,占80.85%,平均遗传相似系数为0.712 1.21条ISSR引物共得到223条扩增条带,其中有166条呈现多态性,占74.44%,平均遗传相似系数为0.778 1.2种标记均表明川党参具有较高的遗传多样性.聚类结果显示川党参种质亲缘关系与地理分布相关性不显著.2种标记系统得到了相似但并不完全相同的聚类图,2种标记方法间存在显著相关性(r=0.802,P＜0.01).结论:川党参种质的遗传多样性水平较高.SRAP与ISSR标记均适用于川党参种质的遗传多样性分析.     

Rh phenotype prediction by DNA typing and its application to practice

The complexity of the RHD and RHCE genes, which is the greatest of all blood group systems, confounds analysis at the molecular level. RH DNA typing was introduced in 1993 and has been applied to prenatal testing. PCR-SSP analysis covering multiple polymorphisms was recently introduced for the screening and initial characterization of partial D. Our objective is to summarize the accrued knowledge relevant to the approaches to Rh phenotype prediction by DNA typing, their possible applications beyond research laboratories and their limitations. The procedures, results and problems encountered are highly detailed. It is recommended that DNA typing comprises an analysis of more than one polymorphism. We discuss future directions and propose a piecemeal approach to improve reliability and cost-efficiency of blood group genotyping that may eventually replace the prevalent serology-based techniques even for many routine tasks. Transfusion medicine is in the unique position of being able to utilize the most extensive phenotype databases available to check and develop genotyping strategies.