Microstructures, mechanical properties and corrosion resistances of extruded Mg-Zn-Ca-xCe/La alloys

Magnesium alloys are considered as good candidates for biomedical applications, the influence of Ce/La microalloying on the microstructure, mechanical property and corrosion performance of extruded Mg-5.3Zn-0.6Ca (wt%) alloy has been investigated in the current study. After Ce/La addition, the conventional Ca2Mg6Zn3 phases are gradually replaced by new Mg-Zn-Ce/La-(Ca) phases (T1'), which can effectively divide the Ca2Mg6Zn3 phase. The Ca2Mg6Zn3/T1' structure in Mg-Zn-Ca-0.5Ce/La alloy is favorably broken into small particles during the extrusion, resulting in an obvious refinement of secondary phase. The dynamic recrystallized grain size is dramatically decreased after 0.5Ce/La addition, and the tensile yield strength is improved, while further addition reverses the effect, due to the grain coarsening. However, the corrosion resistance of extruded Mg-Zn-Ca alloy deteriorates after Ce/La addition, because the diameter of secondary phase particle is remarkably decreased, which increases the amount of cathodic sites and accelerates the galvanic corrosion process.

Asian-American cultural perspectives on birth defects: focus on cleft palate

The treatment of birth defects and other disabilities is influenced by cultural beliefs of the individual, family and society. The recent influx of Asian/Pacific immigrants and refugees has challenged professionals to provide appropriate services to individuals with cleft palate and their families from these populations. The issues of folk and religious beliefs are complex, and the variations among them are often intertwined. Their comprehension is important because studies have reported a higher incidence of cleft lip and/or palate among Asian/Pacific populations. Successful communication with Asian individuals requires recognition and consideration of cultural diversity and differing interactional styles.

Neuropeptides and neurotransmitters in human placental villi

The human placenta contains many kinds of bioactive substances which are more or less similar to those from the hypothalamic-pituitary-gonadal axis. Most of the studies were carried out mainly with term placenta. The present study, therefore, was attempted to identify, quantify and characterize these substances in the human placenta at the early pregnancy. Using the RIA, immunohistochemistry, HPLC, tissue culture and intrauterine injection methods, we have found that: (1) many kinds of neuropeptides and neurotransmitters are present in the placental villi; (2) LH-RH, NT and SRIF positive immunoreactive granules are localized in the cytotrophoblast and those of beta-EP, 5-HT positive granules in the syncytiotrophoblast; (3) synthetic LH-RH and dynorphin (Dyn) stimulate the hCG secretion of the early placental villi in vitro, and (4) the antisera of LH-RH, NT, Dyn and NE antagonist-alpha-MPT significantly reduced the number of blastocyst implantations in the early pregnant rat. These results indicate that in the human placenta there possibly exists a self-regulation mechanism for the synthesis and secretion of placental hormones and neurotransmitters. Therefore, the human placenta can be regarded as a neuroendocrine organ.

NtMYB12a acts downstream of sucrose to inhibit fatty acid accumulation by targeting lipoxygenase and SFAR genes in tobacco

MYB12 promotes flavonol biosynthesis in plants by targeting several early biosynthesis genes (EBGs) of this pathway. The transcriptions of these EBGs are also induced by sucrose signal. However, whether MYB12 is activated by sucrose signal and what the other roles MYB12 has in regulating plant metabolism are poorly understood. In this study, two NtMYB12 genes were cloned from Nicotiana tabacum. Both NtMYB12a and NtMYB12b are involved in regulating flavonoids biosynthesis in tobacco. NtMYB12a is further shown to inhibit the accumulation of fatty acid (FA) in tobacco leaves and seeds. Post-translational activation and chromatin immunoprecipitation assays demonstrate that NtMYB12a directly promotes the transcriptions of NtLOX6, NtLOX5, NtSFAR4 and NtGDSL2, which encode lipoxygenase (LOX) or SFAR enzymes catalyzing the degradation of FA. NtLOX6 and NtLOX5 are shown to prevent the accumulation of FA in the mature seeds and significantly reduced the percentage of polyunsaturated fatty acids (PUFAs) in tobacco. Sucrose stimulates the transcription of NtMYB12a, and loss function of NtMYB12a partially suppresses the decrease of FA content in tobacco seedlings caused by sucrose treatment. The regulation of sucrose on the expression of NtLOX6 and NtGDSL2 genes is mediated by NtMYB12a, whereas those of NtLOX5 and NtSFAR4 genes are independent of sucrose.

NtMYB12a acts downstream of sucrose to inhibit fatty acid accumulation by targeting lipoxygenase and SFAR genes in tobacco

MYB12 promotes flavonol biosynthesis in plants by targeting several early biosynthesis genes (EBGs) of this pathway. The transcriptions of these EBGs are also induced by sucrose signal. However, whether MYB12 is activated by sucrose signal and what the other roles MYB12 has in regulating plant metabolism are poorly understood. In this study, two NtMYB12 genes were cloned from Nicotiana tabacum. Both NtMYB12a and NtMYB12b are involved in regulating flavonoids biosynthesis in tobacco. NtMYB12a is further shown to inhibit the accumulation of fatty acid (FA) in tobacco leaves and seeds. Post-translational activation and chromatin immunoprecipitation assays demonstrate that NtMYB12a directly promotes the transcriptions of NtLOX6, NtLOX5, NtSFAR4 and NtGDSL2, which encode lipoxygenase (LOX) or SFAR enzymes catalyzing the degradation of FA. NtLOX6 and NtLOX5 are shown to prevent the accumulation of FA in the mature seeds and significantly reduced the percentage of polyunsaturated fatty acids (PUFAs) in tobacco. Sucrose stimulates the transcription of NtMYB12a, and loss function of NtMYB12a partially suppresses the decrease of FA content in tobacco seedlings caused by sucrose treatment. The regulation of sucrose on the expression of NtLOX6 and NtGDSL2 genes is mediated by NtMYB12a, whereas those of NtLOX5 and NtSFAR4 genes are independent of sucrose.

[Clinical evaluation of a domestically prepared enzyme immunoassay kit for the detection of hepatitis B surface antigen]

National Institute of Preventive Medicine (NIPM) has succeeded in the development of an enzyme immunoassay (EIA) kit for detection of hepatitis B surface antigen. The sandwich principle was used for the test. Guinea pig anti-HBs IgG was used for coating microtiter plates and Horseradish peroxidase was conjugated with goat specific anti-HBs. Its stability is longer than 4 months. The lowest detectable dose is 0.7 ng/ml or better for subtype ad of HBsAg tested with Hepatitis Sensitivity Panel, Bureau of Drug and Food, Department of Health. The regression curve was determined by testing 66 samples with Auszyme II (EIA Kit. Abbott Lab.) and NIPM Kit, while Auszyme II used as a reference kit. The two EIA kits correlated well with a coefficient of determination (r2) of 0.86. Evaluation on 1,157 patients' and officers' serum samples in Tri-Service General Hospital showed that the positive rate was 24.7% (286/1,157) by RIA (Clinical Assays, Travenol Lab., USA) and that of NIPM EIA Kit was 24.4% (282/1,157). There was no statistical significance in terms of positive rate (p greater than 0.05). The positive rates of 534 blood donors are 22.1% (118/534) and 21.9% (117/534) respectively. Another evaluation on 974 serum samples in National Taiwan University Hospital showed that the positive rate was 27.2% (265/974) by Ausria II-125 (RIA. Abbott Lab.) and that of NIPM EIA Kit was 27.4% (267/974). The undetectable rate and false positive rate of NIPM EIA Kit were 0.41% (4/974) and 0.62% (6/974) respectively. In comparison with four other kind of commercial EIA Kits, the results of NIPM EIA Kit were satisfactory also. We have scaled up the reagent preparations for the kit, except the antibody coated microtiter plate preparation. At the end of March 1985 we will supply 850 EIA kits for the Development Center for Biotechnology for their hepatitis B vaccine production program.