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Biomedical subjects

X He

Publications and source records attributed to X He.

At least 415 records · Page 23Linked to original sources
PubMed1993

[The extensiveness and specificity of analgesia of electroacupuncture (EA) at different points on the nociceptive responses of neuron in spinal dorsal horn].

The experiments were performed in anaesthetized rats. The responses of convergent neurons in spinal dorsal horn to noxious stimuli (10mA, 2ms) given at the hindpaw receptive field were recorded extracellularly by glass microelectrodes. The effects of EA on the nociceptive response were observed. EA was applied on ipsilateral "Zusanli" or "Xiaguan" point with high and low intensity. EA (18V, 100Hz) applied on ipsilateral either "Zusanli" or "Xiaguan" could produce strong inhibition on nociceptive responses of convergent neurones (62.74 +/- 4.94% and 64.24 +/- 7.30%). EA (2V, 100Hz) of "Zusanli" also obviously inhibited the nociceptive responses (52.05 +/- 6.69%). But the same EA of "Xiaguan" lacked this inhibitory effect (9.50 +/- 7.67%). There was statistically significant difference between EA effects of "Zusanli" and "Xiaguan" (P < 0.001) when intensity of EA is lower. These results suggested that analgesia of high intensity EA is extensive, but that of low intensity EA is produced only when the point is in the same or nearby spinal segment with nociceptive field, showing the extensiveness and specificity of EA analgesia of different points.

Acupuncture Analgesia↗
PubMed1993

[The effects of optical isomers of gossypol on Sertoli cells in vitro].

This study was designed to investigate the effects of gossypol optical isomers on Sertoli cells of 20-day-old Wistar rats in vitro. The dosages used were 10 micrograms/ml of (+/-) and (+) gossypol and 5 micrograms/ml (-) gossypol. After 24 h in culture, we found that different optical isomers induced different degrees of morphological changes in Sertoli cells. The changes in mitochondria were obvious. It was shown that the activity of SDH in mitochondria was reduced, or some enzymatic granules became coarser, after gossypol treatment. Under EM we found that the mitochondria had become swollen, the cristae were arranged irregularly, or even broken or absent. The damage caused by the different optical isomers on Sertoli cells was in the order of (+) < (+/-) < (-) gossypol. These changes coincided with changes in Sertoli cells of rats following oral administration of gossypol.

Animals↗
PubMed1992

In vivo incorporation of 14C-phenylalanine into ascidian tunichrome.

Ascidia ceratodes exposed to 14C-phenylalanine in the surrounding seawater incorporates the radiolabel into newly biosynthesized tunichrome molecules. Radioactivity can be detected in tunichrome extracted from circulating blood cells within one day following initial exposure to the radiolabel; weak activity (less than or equal to 4 microCi/mol tunichrome = 22 nmol phenylalanine/mol tunichrome) is detected in 1 to 10 days; significantly higher amounts of radiolabel (57 microCi/mol tunichrome = 318 nmol phenylalanine/mol tunichrome) appear 20 days after seawater exposure. Therefore, phenylalanine can function as a precursor in the biosynthesis of tunichrome.

Animals↗
PubMed1992

Twin of I-POU: a two amino acid difference in the I-POU homeodomain distinguishes an activator from an inhibitor of transcription.

I-POU, a POU domain nuclear protein that lacks two conserved basic amino acids of the POU homeodomain is coexpressed in the developing Drosophila nervous system with a second POU domain transcription factor, Cf1-a. I-POU does not bind to DNA but forms a POU domain-mediated, high affinity heterodimer with Cf1-a, inhibiting its ability to bind and activate the dopa decarboxylase gene. The I-POU/Cf1-a dimerization interface encompasses only the N-terminal basic region and helices 1 and 2 of the POU homeodomains with precise amino acid and alpha-helical requirements. twin of I-POU, an alternatively spliced transcript of the I-POU gene, encodes a protein containing the two basic amino acid residues absent in I-POU. Twin of I-POU is incapable of dimerizing with Cf1-a, but can act as a positive transcription factor on targets distinct from those regulated by Cf1-a. These findings suggest that the I-POU genomic locus simultaneously generates both a specific activator and inhibitor of gene transcription, capable of modulating two distinct regulatory programs during neural development.

Amino Acid Sequence↗
PubMed1992

Brain 4: a novel mammalian POU domain transcription factor exhibiting restricted brain-specific expression.

The POU domain gene family of transcription factors share a conserved bipartite DNA binding domain, and exhibit distinct temporal and spatial patterns of expression during development, particularly in the forebrain. A cDNA encoding a new member of the POU-III class of the POU domain gene family, referred to as Brn-4, was isolated from a rat hypothalamic cDNA library. Like other mammalian POU-III genes previously characterized (Brn-1, Brn-2, Tst-1), Brn-4 transcripts are initially widely expressed at all levels of the developing neural tube, but in contrast to other previously described POU-III genes, are subsequently restricted to only a few regions of the adult forebrain, including the supraoptic and paraventricular nuclei of the hypothalamus. Brn-4 was shown to bind to DNA sequences containing the octamer motif and to trans-activate promoters containing this DNA binding motif, based on the actions of a unique N-terminal information. This ontogenic pattern of Brn-4 expression in concert with that of Oct-2 and Pit-1, indicates that certain POU domain genes potentially exert their primary functions widely during early neural development, and in a very limited set of neurons in the mature brain.

Amino Acid Sequence↗
PubMed1992

[RFLPs study of parental origin and mechanism of 3 cases with X chromosome structural abnormality].

In this study, we analysed the parental origin and mechanism of X chromosome abnormalities in 3 cases by using RFLPs on short or long arm of X chromosome as genetic markers. Their karyotypes were 46,X,dup(X)(p21); 46,X,del(X)(p11); 46,X,i(Xq). The results demonstrated that the dup(X)(p21) and the del(X)(p11) were of paternal origin and i(Xq) was of maternal origin. The dup(X)(p21) arose from an unequal sister chromatid exchange. The del(X) (p11) occurred through X chromosome breakage and deletion mechanism. The i(Xq) resulted from X chromosome centromere misdivision in oocyte.

Adolescent↗
PubMed1992

[Study on variation of plasma gamma-aminobutyric acid concentration in rat model of hepatic encephalopathy due to fulminant hepatic failure].

The plasma gamma-aminobutyric acid (GABA) concentration was measured by a radio-receptor assay in rat model of hepatic encephalopathy due to fulminant hepatic failure (FHF) induced by intraperitoneal injection of D-galactosamine (GalN). The results showed that, in FHF group, the plasma GABA increased parallelly with the degree of hepatic encephalopathy after GalN i.p. (r = 0.944, P less than 0.05). In about 48 h, mean plasma GABA concentration was elevated nearly 8-fold. These findings suggest that, in liver failure, elevated plasma GABA concentration may play a role in the pathogenesis of hepatic encephalopathy.

Animals↗
PubMed1992

Nude mouse interim host model for human parathyroid grafts. I. Structure and secretory function.

Human parathyroid (PTG) tissues from cadaver (C-PTG), fetus (F-PTG) and PTG adenoma (A-PTG) were transplanted into the kidney subcapsule of Balb/C nude mice as interim host. The structure and secretory function of the tissues were checked 30, 60, 90, 120, and 150 days after operation. The results showed that PTG tissues from all three donors could retain their structure and secretory function for more than 100 days in the nude mice. The growth and function of PTG tissues from the three donors in nude mice were compared.

Adenoma↗
PubMed1992

[Identification of sex in mouse preimplantation embryos by indirect immunofluorescent assay].

Indirect immunofluorescent assay was used for detecting male-specific H-Y antigen on preimplantation embryos. Our results showed that, embryos examined, 54.1% were H-Y positive (male) and 45.9% were H-Y negative (female). Significant difference was not found between natural sex ratio of kunming strain mouse (male: 52.1%; female: 47.9%) and our results (P greater than 0.05). Moreover, the results sequentially were confirmed by cytogenetic method. 75.50% H-Y positive embryos were male and 82.97% H-Y negative embryos were female respectively (P less than 0.01). Some factors influencing the accurency of sex selection with indirect immunofluorescent assay were also discussed.

Animals↗
PubMed1991

Autoregulation of the immune response in autoimmune disease and cardiac transplantation by photoinactivated autologous lymphocytes.

These studies demonstrate that photochemotherapy can be successfully evaluated in animal models. The therapy mediates specific suppression of immune responses and appears to operate at the level of the effector T cells. Future studies will focus on isolation and characterization of the host response to photochemotherapy. The extention of this form of therapy to conditions mediated by dysfunctional regulation of effector T cells is already in progress in clinical trials of cardiac allograft transplantation and autoimmune disease. The results of these trials will provide more evidence on the role of this form of therapy in autoregulation of the immune response.

Animals↗
PubMed1991

I-POU: a POU-domain protein that inhibits neuron-specific gene activation.

A novel, structurally distinct POU-domain protein has been identified that inhibits activation by another positive POU-domain regulator of neuron-specific transcription units. Two Drosophila POU-domain proteins, I-POU and Cf1-a, are coexpressed in overlapping subsets of neurons during development. Because I-POU lacks two basic residues in the N terminus of its homeodomain, it cannot bind DNA, but it does form a stable heterodimeric complex with Cf1-a, preventing Cf1-a from binding to DNA recognition elements and from transactivating the dopa-decarboxylase gene. The inhibition by I-POU provides a potential strategy by which the activation of genes in development is controlled by a homeodomain-containing protein that does not bind DNA.

Amino Acid Sequence↗
PubMed1991

Disialoganglioside GD2 in human neuroectodermal tumor cell lines and gliomas.

Monoclonal antibodies (mAbs) recognizing the disialoganglioside II3(NeuAc)2GgOse3Cer (GD2) were produced by immunizing mice with the GD2-expressing neuroblastoma cell line LAN-1 and a prefusion boost with purified GD2 coupled to Salmonella minnesota. Two IgM mAbs were isolated which demonstrated high levels of reactivity (binding ratios in excess of 100) with GD2 by solid-phase radioimmunoassay and positivity in high-performance thin-layer chromatography (HPTLC) immunostain; only one (DMAb-20) was subsequently shown by analysis with a panel of defined ganglioside species to be specific for the minimum epitope of GD2 GalNAc beta 1-4(NeuAc alpha 2-8-NeuAc alpha 2-3)Gal-, DMAb-20 was used to evaluate the expression of GD2 by malignant glioma and medulloblastoma cell lines using cell surface radioimmunoassay. indirect membrane immunofluorescence. HPTLC immunostain, and densitometric analysis of extracted gangliosides from selected cell lines. Sixteen of 20 (80%) malignant glioma and 5 of 5 medulloblastoma cell lines reacted with DMAb-20; in agreement with previous studies, 5 of 5 neuroblastoma and 2 of 3 melanoma cell lines also reacted with DMAb-20, GD2 was proportionally increased in the glioma and medulloblastoma cell lines relative to levels in normal brain, as determined by densitometric analysis. In a phenotypic survey of malignant glioma biopsies, tumor cells in 24 of 30 (80%) cases stained positively with DMAb-20. Reactive astrocytes, both within the adjacent to tumors, were frequently intensely stained. Among the morphological variants of glioblastoma examined, the most intense staining with DMAb-20 was observed in neoplastic gemistocytes, with the weakest or absent staining in small cell glioblastomas. As GD2 is a commonly expressed surface antigen of gliomas and medulloblastomas, expression of which is retained in tissue culture. DMAb-20 will be useful in determining the functional role of GD2 in cell-cell interaction, adhesion, and invasion, and in defining altered growth control mechanisms of central nervous system neoplasms in in vitro models.

Animals↗
PubMed1991

Mechanisms of complex transcriptional regulation: implications for brain development.

The large number of transcription factors, their diverse sequence-specific interactions with DNA sites and with other transcription factors, and their ability to be modified in response to a variety of environmental cues and intracellular signals provide combinatorial codes for highly complex and yet highly organized patterns of gene expression likely to underlie the determination of diversity of neuronal phenotypes. Subtle differences in the combinations of transcription factors are likely to have profound consequences for cell phenotype, similar to the mechanism involved in the specification of cell types in yeast (reviewed in Herskowitz, 1989). Although our current understanding of transcriptional regulation in the brain comes largely from phenomenological studies, recent technical progress on two fronts promises a bright future. Homologous recombination technology in embryonic stem cells (reviewed in Capecchi, 1989; Rossant, 1990) allows the disruption of particular genes in transgenic mice and definition of the roles of identified transcription factors in mammalian neurogenesis. A second technological advance, targeted tumorigenesis, has provided neuronal model cell lines (Mellon et al., 1990; reviewed in Cepko, 1988; McKay et al., 1988) that mimic certain neuronal differentiation pathways. These combined genetic, cell biological, and biochemical approaches will greatly facilitate the study of neural development and function.

Animals↗