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Biomedical subjects

A Kuang

Publications and source records attributed to A Kuang.

42 records · Page 3Linked to original sources
PubMed1991

[Synthesis of hexamethyl propylamine oxime and comparative study of its diastereoisomers].

This is a report on the synthesis of hexamethyl-propylene-amine oxime (HM-PAO), a new agent for regional cerebral blood flow (gamma CBF) imaging, the separation of its diastereoisomers (dl- and meso-HM-PAO), and a comparative study of three forms of Tc- 99m labelled HM-PAO (dl-, meso- and mixture-) in chromatography, mice biodistribution and rabbit imaging. The results showed that the Rf value of Tc-99m-dl-HM-PAO (0.8-1.0) on silica G thin layer chromatography with MEK as solvent was different from that of Tc-99m-meso-HM-PAO (0.6-0.8), and that the retention of dl- isomer in the brain was higher and more static than those of meso-and mixture HM-PAO but identical with Ceretec, a dl-HM-PAO kit manufactured by Amersham Inc., England. The primary clinical applications for gamma CBF SPECT imaging demonstrated a satisfactory result.

Animals↗
PubMed1990

[Effect of monoamine neurotransmitters in the hypothalamus in a cortisol-induced rat model of yang-deficiency].

Eight monoamine neurotransmitters in hypothalamus of normal and cortisol-induced Yang-deficiency rats were measured with HPLC-ECD. These neurotransmitters included: (1) Noradrenaline (NA); (2) Adrenaline (A); (3) 3-methoxy-4-hydroxyphenyl glycol (MHPG); (4) 3,4-dihydroxyphenylacetic acid (DOPAC); (5) Dopamine (DA); (6) 5-hydroxyindole-3-acetic acid (5-HIAA); (7) Homovanillic acid (HVA); and (8) Serotonin (5-HT). With the mobile phase of 10% methanol-0.15 M chloroacetic acid-sodium hydroxide buffer, the neurotransmitters might be well separated, the sensitivity was similar to that of gas chromatography-mass spectrogram with the lower limit of 0.1 ng, this assay was simple and might be accomplished with half an hour. The Yang-strengthening Chinese herbs Radix Aconiti Praeparata, Cortex, Cinamomi, Epimedium brevicorum and Herba Cistanchis were used in the study and the following were founded: (1) In the hypothalamus of cortisol-induced Yang-deficiency rat NA decreased and a increased when compared with that of the normal controls (both P less than 0.05). (2) After 4 weeks of administration of Yang-strengthening herbs, the NA and A of the Yang-deficiency rats returned to nearly normal and it suggested these herbs have the effect of "supporting the right and recovering the source"; DA markedly increased both in control rats and Yang-deficiency rats (P less than 0.05, P less than 0.001 respectively); DOPAC obviously decreased both in control rats and Yang-deficiency rats (P less than 0.001); 5-HT and 5-HIAA increased in the control rats (both P less than 0.001) and HVA significantly decreased in Yang-deficiency rats. (3) The ratio of DA/DOPAC and 5-HT/5-HIAA markedly increased both in the control and Yang-deficiency rats after using Yang-strengthening herbs (P less than 0.01-0.001) and it suggested Yang-strengthening herbs could inhibit the activity of monoamine oxidase in hypothalamus.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1989

Repression of the IgH enhancer in teratocarcinoma cells associated with a novel octamer factor.

Embryonal carcinoma (EC) cell lines are models for early cells in mouse embryogenesis. A 300-base pair fragment of the heavy chain enhancer was inactive in F9 EC cells, unlike in other nonlymphoid cells where it has significant activity. Alterations of the octamer motif increased enhancer activity. Nuclear extracts from F9 cells contained an octamer binding protein (NF-A3) that was unique to EC cells; the amount of NF-A3 decreased upon differentiation. It is proposed that NF-A3 represses specific regulatory sequences that contain the octamer motif. Thus, the same DNA sequence mediates either negative or positive transcriptional effects, depending on the cell type.

Animals↗
PubMed1989

Purified bovine NF-kappa B recognizes regulatory sequences in multiple genes expressed during activation of T- and B-lymphocytes.

To characterize the NF-kappa B binding factor in molecular terms and to facilitate the cloning of its gene, we have purified this protein from bovine spleen tissue. We have found it is a 42,000-dalton protein that exists in solution as a dimer. We were able to use the purified protein to show that the same polypeptide is able to recognize sites important for activation of genes in either B- or T-lymphocytes. Moreover, we were able to define a consensus sequence which allows ascertainment of a wider variety of sequences that are capable of interacting with this protein. The implication of the same protein in gene regulation in two different lineages of lymphoid cells reveals an unexpected unity in the mechanism of gene expression during B- and T-lymphocyte activation. This also suggests that other regulatory events must participate with NF-kappa B activation in determining B- or T-cell-specific expression.

Animals↗
PubMed1988

NF-kappa B protein purification from bovine spleen: nucleotide stimulation and binding site specificity.

The activity of the enhancer for the kappa immunoglobulin light chain gene critically depends on the presence in the nucleus of the NF-kappa B protein. We purified NF-kappa B over 50,000-fold and identified two protein species, 42 and 44 kDa, that could be eluted and renatured from a sodium dodecyl sulfate/polyacrylamide gel to give specific DNA-binding activity. Binding of the purified bovine NF-kappa B as well as that from human and murine B- or T-lymphoid cell extracts was dramatically stimulated by nucleoside triphosphates. This effect distinguished NF-kappa B from a related factor, H2-TF1. Purified NF-kappa B interacted efficiently with regulatory sequences that function during either B- or T-lymphocyte activation, including the human immunodeficiency virus enhancer and a NF-kappa B binding site we detected in the interleukin 2 enhancer.

Animals↗