The Government's decision to drastically and speedily increase the number of doctors in the country needs to be reviewed. The standard and quality of health care does not depend on the number of doctors, but on the improvement of the health care infrastructure. Increasing the number of government medical schools and increasing the intake of students should be done on a need-to basis, with the above perspective in mind. The selection criteria of candidates must not be compromised and the teaching staff must be adequate and experienced. The number of doctors should be gradually increased over the years in tandem with the development of the health care infrastructure and the deployment of doctors must be directed at providing equitable care to the people at all economic levels and geographic locations. The strength of academic staff in existing government medical schools must be upgraded to provide high level of teaching and research, perhaps reinforced with the recruitment of suitably qualified and experienced foreign teachers. The infrastructure of existing government medical schools must be upgraded to cater for the gradual increasing demand for more doctors as the country develops. The selection of candidates for the government medical schools must be based on merit and without undue emphasis on ethnic considerations, for it is only in the arena of fair competitiveness that excellence can be born. The considerations of merit in selection must include assessment of attitude, self-development, moral ethics and reasoning. If the above perspectives are fully appreciated, then there is really no requirement for private medical colleges in Malaysia.
seconds ; Schools, Medical ; Selection (Genetics) ; development aspects ; Teaching aspects

The insecticide susceptibility of Aedes aegypti larvae and adults from four areas of Ratchaburi Province, Thailand was investigated using World Health Organization standard procedures. The larvae of Ae. aegypti in all areas were found to be susceptible to temephos. The strain with the highest level of temephos resistance was subjected to temephos selection. The resistance ratios increased to 2.74-fold from their parental non selected strain after 5 generations of selection. For the adult of Ae. aegypti, the study was conducted to determine the effects of 0.75 % permethrin and 0.05 % deltamethrin impregnated paper selection on the strain having the highest with the highest LT50 level. The results showed the increase in the LT50 to 7.46 and 1.18-fold after the third selected generation with 0.75 % permethrin and 0.05 % deltamethrin respectively. Mortality rates after exposing adults to discriminating concentrations showed that field populations in Ratchaburi Province were resistant to permethrin and deltamethrin. Alternative non-chemical measures need to be used in new of the emergence of resistance in the mosquito population.
Cancer resistance to treatment ; Selection (Genetics) ; Aedes aegypti ; Permethrin ; decamethrin

One of the main topics in population genetics is identification of adaptive selection among populations. For this purpose, population history should be correctly inferred to evaluate the effect of random drift and exclude it in selection identification. With the rapid progress in genomics in the past decade, vast genome-scale variations are available for population genetic analysis, which however requires more sophisticated models to infer species' demographic history and robust methods to detect local adaptation. Here we aim to review what have been achieved in the fields of demographic modeling and selection detection. We summarize their rationales, implementations, and some classical applications. We also propose that some widely-used methods can be improved in both theoretical and practical aspects in near future.
Adaptation, Physiological ; genetics ; Demography ; Evolution, Molecular ; Genetics, Population ; Genome ; Models, Genetic ; Polymorphism, Genetic ; Selection, Genetic ; genetics

G46B is a promising holding line used for three-lines breeding strategy in hybrid rice, but it is susceptible to blast disease caused by Pyricularia grisea. To improve its blast resistance, three rice varieties, Digu, BL-1, and Pi-4, with blast resistance genes, Pi-d(t), Pi-b, and Pi-ta2, respectively, were used to be crossed with G46B, and 15 plants with these three blast resistance genes, Pi-d(t)1, Pi-b, and Pi-ta2, were selected from their F2 and B1C1 populations via a marker-aided crossing procedure. Among them, four plants were heterozygotes in the three resistance genes, with the genotype of Pi-d(t)1 pi-d(t)/Pi-b pi-b/ Pi-ta2 pi-ta2; ten plants were heterozygotes in two of the three resistance genes, of which six with the genotype of Pi-d(t)1 Pi-d(t)1/Pi-b pi-b/Pi-ta2 pi-ta2, three with the genotype of Pi-d(t)1 pi-d(t)1/Pi-b pi-b/Pi-ta2 Pi-ta2, and one with the genotype of Pi-d(t)1pi-d(t)1/Pi-b Pi-b/Pi-ta2 pi-ta2; and only one plant was homozygote in two of the three resistance genes with the genotype of Pi-d(t)1 Pi-d(t)/Pi-b pi-b/Pi-ta2 Pi-ta2. These results demonstrate the capacity of maker-assisted selection (MAS) in gene pyramiding for rice blast resistance and its enhancement for the efficiency in rice resistance breeding.
Crosses, Genetic ; Genes, Plant ; Genetic Markers ; Genotype ; Oryza ; genetics ; Plant Diseases ; genetics ; Selection, Genetic

OBJECTIVETo elucidate the evolution pattern of human influenza virus A H3 subtype by detecting positive selected codons in hemagglutinin gene.

METHODSAll H3 sequences in NCBI GenBank and influenza sequence database were downloaded and two step cluster method was applied to divide sequences into six groups, which were corresponding to different period by turns. Fixed Effect Model was applied to detect positive selected codons in each group, and two step cluster method was then used again to summarize variation patterns of selective pressure among sites.

RESULTSPositive selected codons were different in groups corresponding different periods. 50 amino acid codons had been identified as positive selected sites in at least one time span. Among them, 42 codons belonged to one of the five known antigen-combinng regions. A larger amount of sites as well as relatively higher selection pressure were identified in antibody combining regions A and B. Results showed that the 50 sites could be divided into seven different patterns. While other six patterns corresponding to positive selected codons at only one time span, the sites of the seventh pattern were under positive selection in several periods.

CONCLUSIONPositive selection codons in evolution of H3A1 strains were alternated in different time period whereas antibody combining regions A and B played more important roles in the evolution process. Other 8 identified codons out of the antibody combining regions might belong to unknown antigen regions.

Amino Acid Sequence ; Codon ; Hemagglutinins ; genetics ; Humans ; Influenza A Virus, H3N2 Subtype ; genetics ; Influenza, Human ; genetics ; Selection, Genetic

OBJECTIVETo analyze the human leukocyte antigens(HLA)-A, -B, -Cw, -DRB1 and DQB1 nucleotide sequences between patients waiting for allogenic hematopoietic stem-cell transplantation (HSCT) and donors in Chinese population, and to establish strategy for maximizing optimal donor selection.

METHODSHLA high-resolution typing in a total of 537 recipient-donor pairs was determined by sequence based typing (SBT) method. The nucleotide BLAST tool was used to compare the nucleotide sequences among recipient-donor pairs.

RESULTSOnly 16.20% (88/537) of recipient-donor pairs were found to fully match for nucleotide sequences of all HLA-A,-B,-Cw, -DRB1 and -DQB1 loci. Mismatch rate in single locus were 8.38% in HLA-A, 0.74% in HLA-B, 12.29% in HLA-C, 2.42% in HLA-DRB1, and 2.79% in HLA-DQB1, respectively. Mismatch rate in two or multiple HLA loci was 42.65%. Nonpermissive allele mismatch combinations (A 02:01-A 02:06, A 02:06-A 02:07, Cw 03:04-Cw 15:02, Cw 03:03-Cw 04:01, Cw 03:04-Cw 14:02, Cw 03:03-Cw 08:01, DRB1 04:03:01-DRB1 04:05) were detected in single mismatch HLA locus of recipient-donor pairs, mismatches of B 07:05:01-B 07:06, Cw 07:01:01-Cw 07:06 combinations outside of epitope positions were detected in two recipient-donor pairs.

CONCLUSIONOur data suggested that attention should be paid in comparing nucleotide sequences between recipient and donor, and in distinguishing nucleotide sequence mismatches within and outside of the epitope positions. These results could serve as guidelines for donor selection.

Base Sequence ; Donor Selection ; methods ; Epitopes ; genetics ; HLA Antigens ; genetics ; Hematopoietic Stem Cell Transplantation ; methods ; Humans ; Tissue Donors

OBJECTIVETo assess the impact of natural selection and genetic background on the polymorphisms of HLA-G 3-untranslated regions (UTR) among five ethnic Chinese populations.

METHODSPCR and DNA sequencing were used to determine the polymorphisms among 432 individuals from the five ethnic populations. Their genetic background was determined by genotyping of 10 short tandem repeats (STRs).

RESULTSEight variations were identified among Gelao, Mongolian and Kirgiz populations, while only 7 were found in Shui and Dai people. For all 3 southern populations (Gelao, Shui, and Dai), the observed heterozygosites (Ho) was higher than expected heterozygosities (He). But this was reversed for the 2 northern populations (Mongolian and Kirgiz). The Ho and He of the 10 neutral STRs were in random distribution. Ewens-Watterson testing based on haplotypes of the HLA-G 3'UTR has suggested that a natural selection had occurred in the region where Dai and Shui had inhabited, but not in the northern region where Mongolian and Kirgiz population inhabited. Polygenetic trees based on the HLA and STRs were also different.

CONCLUSIONThe HLA-G 3'UTR of Dai and Shui people who lived in southern China may have subjected to a selection pressure. Based on current knowledge, this pressure may have been driven by a pathogenic selection.

3' Untranslated Regions ; genetics ; China ; ethnology ; Female ; HLA-G Antigens ; genetics ; Humans ; Male ; Microsatellite Repeats ; Polymorphism, Genetic ; Selection, Genetic

OBJECTIVETo investigate botanical characters and yield of four cultivars of Chrysanthemum morifolium for further study on their genetic diversity and selective breeding.

METHODThe characters were observed and yield was investigated by field randomized block and analysis of variance.

RESULT AND CONCLUSIONThe botanical characters are difference among four cultivars; the amount of single flower head is the main factor influencing on the output of Chrysanthemum morifolium (r = 0.925); the yield of "Hongxinju" and "Xiaobaiju" are remarkably higher than that of "Dabaiju" and "Changbanju".

Breeding ; Chrysanthemum ; anatomy & histology ; genetics ; growth & development ; Genetic Variation ; Plants, Medicinal ; anatomy & histology ; genetics ; growth & development ; Selection, Genetic

Pdm09 virus outbreak occurred in Mainland China in May 2009, a few months later, the prevalence of seasonal H1N1(sH1N1) influenza virus that already circulated in human for tens of years began to decline and disappeared afterwards. To identify the reason for the rapid decline of sH1N1 in mainland China, we sequenced the HA1 of sH1N1 during 2006-2011, and then analyzed the selective pressure in different phases. Our results showed before Pdm09 outbreak, the omega value was 0. 36 while after Pdm09 outbreak the omega value was 0. 28 and significant difference (t test, P<0. 05) was identified. We concluded that sH1N1 obtained stronger purifying selection after Pdm09 outbreak in China. This might one of the major reasons causing the disappearance of sH1N1 in human.
China ; Humans ; Influenza A Virus, H1N1 Subtype ; classification ; genetics ; isolation & purification ; Influenza, Human ; virology ; Phylogeny ; Seasons ; Selection, Genetic

Brain metastasis was a common metastasis site and leading cause of death in non-small cell lung cancer (NSCLC). Tyrosine kinase inhibitors had improved survival of NSCLC patients with positive drive gene. It also brings good news to NSCLC patients with positive drive gene and brain metastases. However, there is still no effective treatment for NSCLC patients with drive gene-negative and brain metastases. In recent years, immunotherapy has made breakthrough progress and become important first and second line treatment options of NSCLC especially in patients with drive gene-negative. The role of immunotherapy in specific populations of NSCLC-brain metastasis patients, especially drive gene-negative patients has become the focus of attention. In this report, we review the research progress of immunotherapy in NSCLC with brain metastases, especially in driver-negative patients, analyze the limitations of existing research and future challenge.
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Brain Neoplasms ; immunology ; secondary ; therapy ; Carcinoma, Non-Small-Cell Lung ; genetics ; pathology ; Humans ; Immunotherapy ; methods ; Lung Neoplasms ; genetics ; pathology ; Patient Selection