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Biomedical subjects

S Lau

Publications and source records attributed to S Lau.

10 recordsLinked to original sources
PubMed1992

Effect of endotoxin on serum granulocyte and granulocyte-macrophage colony-stimulating factor levels in dogs.

The biologic effects of endotoxin are attributed to the release of several cytokines, including interleukin-1, interleukin-6, tumor necrosis factor, and the colony-stimulating factors. To investigate the mechanism of endotoxin-induced neutrophilia in dogs, several cell lines known to proliferate selectively in response to recombinant human colony-stimulating factors were examined to determine their responses to recombinant canine granulocyte colony-stimulating factor (rcG-CSF) or recombinant canine granulocyte-macrophage colony-stimulating factor (rcGM-CSF). The murine cell line NFS-60 was found to respond well to rcG-CSF and the human cell line TALL-101 to rcGM-CSF, and these responses were neutralized by antibodies to these recombinant proteins. These bioassays were then used to determine G-CSF and GM-CSF levels in dogs after intravenous endotoxin administration. G-CSF levels increased by 2 h, peaked at 4 h, and had not returned to normal by 24 h after endotoxin. In contrast, GM-CSF was not detectible before or after endotoxin administration.

Animals↗
PubMed1992

Relations with parents and school and Chinese adolescents' self-concept, delinquency, and academic performance.

Current research and theory have suggested that the relational domains of family and school experiences are important to children's development. The present study thus examined how relations with parents and school were related to Chinese students' psychosocial and cognitive development in self-concept, delinquency, and academic performance. A total of 1668 secondary school students were studied, and results showed that better relation with parents was associated with higher general, academic, appearance, social, and physical ability self-concepts. Better relation with school was associated with higher academic performance, as shown in higher class rank, higher grand total exam scores, and higher scores in Chinese, English, mathematics, physical education, and music. Both poorer relations with parents and school were found to associate with more self-reported delinquency as well as more school records of misconduct.

Achievement↗
PubMed1992

Development of the Multi-Trait Personality Inventory (MTPI): comparison among four Chinese populations.

Anemic approach was adopted to develop a culture-specific instrument for the assessment of Chinese personality. The Multi-Trial Personality Inventory (MTPI) was administered to 1,673 men and 944 women in four major Chinese populations. It was found that Chinese in mainland China, Taiwan, Hong Kong, and the United States possess some common traits deeply rooted in the Chinese culture characterized by Confucian thoughts (e.g., self-discipline and moderation) and some additional traits nurtured by their respective environments. Consequently, findings of this study lent support to the hypothesis that, in spite of superficial discontinuities, there are basic continuities in the personality traits of mainland and overseas Chinese. The cross-cultural differences in personality were examined from a political-social perspective and also explained with a cultural-ecological model. In the development of the MTPI, a new methodology that relies on forming factor-consistent clusters was employed to deal successfully with the problem of complex factor space.

Adult↗
PubMed1991

Histamine measurement in whole blood and cell supernatants. A comparative study of two different radioimmunoassays.

Histamine as an important mediator of the allergic reaction has been measured by a number of methods both in whole blood and cell supernatants after in vitro release. We compared the fluorometric histamine assay with two radioimmunoassays and studied detection limit, recovery, cross-reactivity and accuracy in buffer-based standards as well as the sensitivity after IgE-mediated in vitro release from washed cells and whole blood. Our data indicate that the double-antibody RIA (Pharmacia) can be used for studies of basophil histamine release in both whole blood and cell supernatants. Due to significant cross-reactivity to N-methyl-histamine it cannot be used for histamine determinations in plasma. The second radioimmunoassay using succinyl-glycine as an acylating reagent and monoclonal antibodies, which have been raised to acylated histamine, is the most sensitive assay without any cross-reactivity with methylhistamine.

Antibodies, Monoclonal↗
PubMed1991

Innervation of the pulp-predentin border zone of the cat following denervation and reinnervation.

Under general anesthesia the inferior alveolar nerves of 8 cats were transected unilaterally and the cut ends reapposed. Two of these animals were, under general anesthesia, perfused with fixative 2 days later and 6 animals 12 or 15 weeks later, and the crowns of the mandibular canine teeth were prepared for ultrastructural examination. The distribution of axons at the pulp-predentin border and in the predentinal tubules was measured on the operated and control sides. In unoperated teeth the innervation at the pulp-predentin border paralleled that in the predentinal tubules being denser more coronally. The axons at the pulp-predentin border had disappeared by 2 days after denervation but had returned by 12 weeks and later with a density and distribution similar to that of the control sides.

Animals↗
PubMed1990

IgE-mediated allergic reactions to potatoes.

We investigated sera of 12 patients with IgE-mediated hypersensitivity reactions to potato, using different in vitro methods. Radioallergosorbent test classes 2-4 (7.6-46.5% binding) were measured with potato allergen disks. Immunoblot detected allergen bands with an isoelectric point range of approximately 4.5-5.2 and mainly in a molecular weight range between 16.00 and 30.00 kD. But also at molecular weights of 43.00 and 65.00 kD allergen bands (IgE specificities) could be detected. Histamine release assay performed with isolated fractions of the potato extract showed a great individual variation and positive results of fractions of molecular weights between 10.00 and 80.00 kD. From our data we conclude that raw potato is a 'multiallergenic' vegetable.

Adolescent↗
PubMed1979

Inorganic mercury(II)-binding components in normal human blood serum.

The interaction of Hg(II) with human blood serum was studied at physiological pH. Most of the Hg(II) was found to be associated with the proteins, and only a small fraction was associated with the low-molecular-weight substances in serum. Albumin is the major Hg(II)-binding protein (greater than or equal to 90%) in serum. Among the amino acids, L-cysteine has the highest affinity for Hg(II). In dialyzed serum having equimolar concentrations of Hg(II), albumin, and L-cysteine, the amount of Hg(II) found in the supernatant after ultracentrifugation was about 6--7%. There are preferential Hg(II)-binding sites on the albumin molecule. However, no significant change in the circular dichroism spectrum of albumin was detected until at least two equivalents of Hg(II) were present. Hg(II) can mediate the formation of the albumin dimer as well as a ternary complex of the type albumin-Hg(II)-L-cysteine. The latter presumably plays an important role in the transport of Hg(II) between blood and various tissues.

Blood Proteins↗
PubMed1975

Decrease of epidermal histidase activity by tumor-promoting phorbol esters.

The potent skin tumor promoter (12-O-tetradecanoyl phorbol-13-acetate (TPA) stimulates epidermal macromolecular synthesis as well as proliferation, but little is known of specific functional aberrations produced by TPA. This report presents results of a study on the effects of TPA on epidermal histidase (L-histidine ammonia lyase), an enzyme found in normal epidermis but not in dermis or in mouse squamous cell carcinomas. Histidase activity was assayed on postmitochondrial supernatants obtained from hairless mouse epidermis after removal by keratotome. Topical TPA treatment at doses active in tumor promotion (1.7 to 17.0 nmoles/application) produced dose-dependent decreases in epidermal histidase specific activity at 19 hr posttreatment. The onset of the decrease occurred at 12 hr with recovery to control level specific activity by 5 days, showing kinetics similar to those obtained for stimulation of DNA synthesis. This decrease in histidase could not be attributed to a general inhibition of soluble protein synthesis or to the appearance of an inhibitor of histidase activity. The strong promoter TPA produced a greater histidase decrease than did the moderate promoter and mitogen 12,13-didecanoyl phorbol at equimolar dose, while phorbol, a nonpromoter and nonmitogen, produced no effects on histidase. The relationship of this histidase depression to tumor promotion and not initiation is further indicated by the finding that (a) Tween 60, a structurally unrelated tumor promotor, also produced a decrease in histidase; and (b) the tumor initiator urethan and an initiating dose of 9,10-dimethybenz(a)anthracene showed no effects on histadase activity.

Ammonia-Lyases↗