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Biomedical subjects

X Yao

Publications and source records attributed to X Yao.

At least 145 records · Page 8Linked to original sources
PubMed1996

Localization of the mineralocorticoid receptor in rat cochlear tissue.

Distribution of the mineralocorticoid receptor within rat cochlear tissue was studied by immunohistochemistry. Intense immunoreactions of mineralocorticoid receptor antibodies were observed in outer and inner hair cells of the organ of Corti, stria vascularis, spiral ligament and spiral ganglion cells. Moderate to weak immunostaining was observed in the spiral limbus and cochlear nerve. Results of this study suggest that cochlear tissue is a mineralocorticoid hormone target tissue.

Animals↗
PubMed1996

Localization of Cu/Zn-SOD and Mn-SOD in the rat cochlea.

Distributions of the copper/zinc-superoxide dismutase (Cu/Zn-SOD) and the manganese superoxide dismutase (Mn-SOD) in the rat cochlea were studied by immunohistochemistry with specific polyclonal antibodies to Mn-SOD and Cu/Zn-SOD. Coexpression of Mn-SOD and Cu/Zn-SOD was observed in the cochlear tissues with differing immunoactivity intensities. The presence of Cu/Zn- and Mn-SOD implies the existence of a defense system against free oxygen radical (FOR) injury in cochlear tissues.

Animals↗
PubMed1996

[Canonical correlation of body composition and pulmonary function in children aged eight to twelve].

Canonical correlation of body composition and pulmonary ventilation function in school boys and girls aged 8 to 12 and normally developed was analyzed. Skinfolds of triceps and subscapular angle were measured, and body composition was estimated as body fat percentage (BF%), body fat (BF) and lean body mass (LBM). Ventilation function was measured. Results indicated that correlation between body composition and ventilation function mainly attributed to a positive correlation between LBM and vital capacity (VC) and a negative correlation between BF% and a ratio of expiratory reserve volume (ERV) to VC. It suggests effects of body composition on ventilation function mainly attributed to LBM and BF%.

Body Composition↗
PubMed1996

[A study on neural regeneration after experimental epikeratophakia].

OBJECTIVE: To assess the effect of epikeratophakia (EKP) on corneal nerve regeneration and the recovery of corneal sensitivity. METHODS: 36 adult rabbits underwent epikeratophakia with either 0.2 mm or 0.3-0.35 mm circular trephination. A histochemical technique (acetylcholine esterase staining) was used to investigate the process of corneal nerve regeneration, and the recovery of corneal sensitivity was determined in 36 rabbits at various intervals after EKP. RESULTS: The corneal sensory nerves began to regenerate just peripheral to the host-donor interface 3 weeks following EKP, the nerve fibers traveled toward the stroma of the lenticules at 2 months, and formed a sparse subepithelial plexus at 8 months after surgery. A relative hyposthesia was found in the central zone of the lenticule when compared with its peripheral zone 4 months postoperatively. The sensitivity of the central zone remained lower at 5-8 months after EKP though it had remarkably increased. The density of re-innervated fibers was higher in the shallow incision than that in deeper one. CONCLUSION: It is suggested that the factors affecting the corneal innervation and the recovery of corneal sensitivity following EKP include; (1) the scar formation as a barrier; (2) the adaptation to the micro-environment around the lenticule; and (3) the depth of trephine cut. Therefore, a 0.2-0.25 mm depth of trephine incision is advantageous to the lamellar dissection, graft suturation and corneal nerve regeneration.

Animals↗
PubMed1996

[Relationship between body composition and serum thyroid hormone in children aged 8 to 12 years].

Eighty-one children aged 8 to 12 years were divided into three groups, i.e., obese, normal, and thin ones according to their body fat percentage, and serum thyroid hormone, zinc and copper concentrations were determined for them to study relationship between body composition and serum thyroid hormone, zinc and copper. Results indicated serum level of free 3,5,3'-triiodothyronine (FT3) was significantly higher in the obese group than in the other two groups, and that in the normal group was higher than that in the thin one. Analysis showed body fat composition correlated with serum FT3 positively. No correlation between body composition, serum thyroid hormone, and serum zinc and copper in children aged 8 to 12 years was observed in this experiment.

Adipose Tissue↗
PubMed1996

[Surgical treatment of primary liver cancer].

The mortality rate of patients with primary liver cancer (PLC) was 20.40 per 100,000 Chinese per year, that takes the second place among all forms of cancer. Surgical resection remains the modality of primary choice in the treatment of PLC. 2051 patients with PLC were treated by liver resection from 1960 to 1993. Of those, 94.1% were hepatocellular carcinoma (HCC) and the incidence of cirrhosis and chronic hepatitis was found in 86.5%. Small PLC (< or = 5 cm in diameter) was found in 25.1% of all cases. In the small PLC group, 176 cases were found the tumor < or = 3 cm in diameter. All 2051 patients received liver resection and 44.0% of them had local radical resection. The overall mortality rate within one month after operation was 1.1%. The overall 5-year survival rate was 36.1%. Improved surgical result was obtained in 515 patients with small PLC (< or = 5 cm in diameter). No operative death occurred in this group and the 5-year survival rate was 79.8%. Moreover, the patients with very small PLC (< or = 3 cm in diameter) prolonged their survival. The 5-year survival rate was 85.3%. Early diagnosis and early resection of PLC are one of the key points for improving the long-term results. Improvements in operative techniques play an important role in reducing post-operative complications, lowering operative mortality and obtaining better operative results. Rehepatectomy for recurrent liver cancer can improve the surgical results. 95 patients underwent rehepatectomy with a 5-year survival rate of 53.2% and 25.0% after the first and second operation respectively. One patient survived 18 years. For unresectable large tumors, two-stage resection can be used. We collected 659 cases of large unresectable tumors from 1974 to 1994. Among them, 73 cases were resected in two-stage operation. The resection rate was 11.1%, and the 5-year survival rate was 61.5%. Postoperative comprehensive treatment is also important for upregulating cellular immunological function, preventing tumor recurrence, and improving surgical results.

Adult↗
PubMed1995

Recruitment of semiallogeneic dendritic cells to the thymus during post-cyclosporine thymic regeneration.

Based on studies of the thymic microenvironment in the model of cyclosporine (CsA)-associated syngeneic graft-versus-host disease, we have hypothesized that immune tolerance develops after CsA is stopped, as the thymus regenerates and recruits new dendritic cells. CsA normally induces medullary involution with destruction of the medullary dendritic cells (DC) and epithelium. This principle could provide practical advantages for transplantation if it is used to recruit new DC into the thymic medulla. Here we administer LEW x BN F1 splenocytes to BN rats and treat them with a short course of CsA. After CsA is stopped, the F1 cells are rapidly recruited to the thymus, and by 10 days after CsA, they are localized at the corticomedullary junction, the natural location of thymic DC. In contrast, dexamethasone, which induces cortical involution, did not lead to thymic recruitment of F1 DC. Recruitment was better if the splenocytes were administered before CsA was stopped. Engraftment of the thymus was also achieved using bone marrow and temporary skin grafts as sources of DC. These observations provide the basis for a novel approach to inducing tolerance to alloantigens with minimal immune suppression and define the goals for further development.

Animals↗
PubMed1995

Primary structure and functional expression of a cGMP-gated potassium channel.

Cyclic nucleotides modulate potassium (K) channel activity in many cells and are thought to act indirectly by inducing channel protein phosphorylation. Herein we report the isolation from rabbit of a gene encoding a K channel (Kcn1) that is specifically activated by cGMP and not by cAMP. Analysis of the deduced amino acid sequence (725 amino acids) indicates that, in addition to a core region that is highly homologous to Shaker K channels, Kcn1 also contains a cysteine-rich region similar to that of ligand-gated ion channels and a cyclic nucleotide-binding region. Northern blot analysis detects gene expression in kidney, aorta, and brain. Kcn1 represents a class of K channels that may be specifically regulated by cGMP and could play an important role in mediating the effects of substances, such as nitric oxide, that increase intracellular cGMP.

Amino Acid Sequence↗
PubMed1995

Hydrocephalus induction in mice infected with herpes simplex virus type 2 after antiviral treatment.

By using antiviral chemotherapy to moderate the lethal effect of wild-type herpes simplex virus type 2 (HSV-2), a new mouse model for herpes simplex virus (HSV)-induced hydrocephalus was developed. Groups of BALB/c mice were infected either intracerebrally (i.c.) or intraperitoneally (i.p.) with a lethal dose of HSV-2. The antiviral agent 2'-fluoro-5-methylarabinosyluracil (FMAU) was administered i.p. 2 days after virus inoculation. By day 21, 80 and 71.4% of the mice infected i.c. or i.p., respectively, survived. The surviving animals were randomly subdivided into different groups and some were challenged i.c. or i.p. with a lethal or superlethal dose of homologous virus. The mice were sacrificed at 2 or 3 months after the initial virus infection. Neuropathological changes of the brains were assessed. Dilation of lateral and third ventricles was noted in the animals initially inoculated i.c., especially in all the animals inoculated i.c. and challenged i.c. with a superlethal virus inoculum, but not in those inoculated i.p. Microscopic examination of hydrocephalic brains revealed evidence of viral meningoencephalitis. Two different mechanisms of ventricular enlargement in this animal model are proposed. This model is relevant since HSV-induced cases of hydrocephalus have been reported to occur in humans and in particular neonates. Issues of virus persistence and expression, long-term evaluation for disease progression, and intervention strategies could be examined with this model.

Animals↗
PubMed1995

De novo synthesis of glucocorticoid hormone regulated inner ear proteins in rats.

Changes of rat inner ear de novo protein synthesis in response to dexamethasone (DEX), a synthetic glucocorticoid, have been analyzed by high resolution two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (2D-SDS-PAGE) and fluorography. Two proteins (M(r) 41,000 and 35,000) were amplified and one protein (M(r) 47,000) was suppressed by DEX in a cochlear culture medium. In the culture medium conditioned by vestibular tissue, three proteins (M(r) 67,000, 57,000 and 50,000) were amplified after DEX administration. In cochlear and vestibular tissues, glucocorticoid-responsive protein synthesis was down-regulated by DEX, including two proteins (M(r) 39,000 and 35,000) in the cochlea and five proteins (M(r) 80,000, 64,000, 59,000, 56,000 and 40,000) in the vestibule. The regulation of these inner ear proteins by DEX suggests that glucocorticoid may play an important role in normal inner ear microhomeostasis, as well as in the treatment of some inner ear disorders.

Animals↗
PubMed1995

Glucocorticoid receptor expression in the postnatal rat cochlea.

The glucocorticoid receptor (GR) expression in the neonatal rat cochlea was investigated by utilization of a polyclonal antibody against GR, the immunoreactivity of which exhibited a distinct, age-dependent developmental pattern in tissues of the spiral ligament (SL). Immunostaining of GR appeared initially at the 7th postnatal day (PND), increased rapidly between the 14th and 21st PND, and reached adult-like expression levels by the 21st PND. Less pronounced, developmentally regulated expression patterns of GR were observed in cells of the spiral limbus (SLi), spiral ganglion (SG), organ of Corti (OC), and cochlear nerve (CN). For example, high expression levels of GR were observed in the SLi, SG and OC at 3 PND; subsequently, GR immunoreactivity levels decreased from 7 to 14 PND, and then GR immunoreactivity intensified in these regions by 21 PND. No remarkable changes in GR expression were observed in stria vascularis (SV). These data indicate that GR expression in the inner ear is tissue and age-specific, and that GR expression parallels both Na,K-ATPase expression and endocochlear potential development.

Aging↗
PubMed1995

Characterization of fractured permeable porous media using relaxation-weighted imaging techniques.

The inversion time (TI) weighted inversion-recovery spin-echo (IRSE) imaging technique was used for laboratory characterization of fractures and porous matrix in permeable media. The method is based on the fact that relaxation rates in fractures and those in surrounding porous matrix are substantially different. Thus, by selectively suppressing imaging signals from either fractures or porous matrix, one can highlight fluid distributions in either of these regions so that fractures can be unambiguously identified and surrounding porous structures can be characterized. The advantages over conventional NMR spin-echo imaging are demonstrated with various fractured porous rock types. A technique to speed acquisitions of images of fluid distributions in porous matrix is also demonstrated.

Calcium Carbonate↗
PubMed1995

Novel furostanol glycosides from Allium macrostemon.

Further studies by means of preparative HPLC led to the isolation of two new furostanol saponins, macrostemonosides G (1) and I (3), along with an artifact, macrostemonoside H (2) from the bulbs of Allium macrostemon Bunge. On the basis of chemical evidence and spectral analyses (1H-,13C-NMR,1H-1H COSY,1H-13C COSY, HMBC and FAB-MS), the structure of 1 was established as 26-O-beta-D-glucopyranosyl-22-hydroxy-5 beta-furost-25(27)-ene-3 beta,12 beta,26 triol 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-galactopyranoside and 2 as the 22-methoxy derivative of 1; 3 was deduced to be 26-O-beta-D-glucopyranosyl-22-hydroxy-5 beta-furost-25(27)-ene-12-one-3 beta,26- diol 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-galactopyranoside. Preliminary pharmacological tests showed that macrostemonoside G (1) could inhibit ADP-induced human platelet aggregation in vitro (IC50 = 0.871 mM).

Adult↗
PubMed1995

Polarized distribution of actin isoforms in gastric parietal cells.

The actin genes encode several structurally similar, but perhaps functionally different, protein isoforms that mediate contractile function in muscle cells and determine the morphology and motility in nonmuscle cells. To reveal the isoform profile in the gastric monomeric actin pool, we purified actin from the cytosol of gastric epithelial cells by DNase I affinity chromatography followed by two-dimensional gel electrophoresis. Actin isoforms were identified by Western blotting with a monoclonal antibody against all actin isoforms and two isoform-specific antibodies against cytoplasmic beta-actin and gamma-actin. Densitometry revealed a ratio for beta-actin/gamma-actin that equaled 0.73 +/- 0.09 in the cytosol. To assess the distribution of actin isoforms in gastric glandular cells in relation to ezrin, a putative membrane-cytoskeleton linker, we carried out double immunofluorescence using actin-isoform-specific antibodies and ezrin antibody. Immunostaining confirmed that ezrin resides mainly in canaliculi and apical plasma membrane of parietal cells. Staining for the beta-actin isoform was intense along the entire gland lumen and within the canaliculi of parietal cells, thus predominantly near the apical membrane of all gastric epithelial cells, although lower levels of beta-actin were also identified near the basolateral membrane. The gamma-actin isoform was distributed heavily near the basolateral membrane of parietal cells, with much less intense staining of parietal cell canaliculi and no staining of apical membranes. Within parietal cells, the cellular localization of beta-actin, but not gamma-actin, isoform superimposed onto that of ezrin. In a search for a possible selective interaction between actin isoforms and ezrin, we carried out immunoprecipitation experiments on gastric membrane extracts in which substantial amounts of actin were co-eluted with ezrin from an anti-ezrin affinity column. The ratio of beta-actin/gamma-actin in the immunoprecipitate (beta/gamma = 2.14 +/- 0.32) was significantly greater than that found in the cytosolic fraction. In summary, we have shown that beta- and gamma-actin isoforms are differentially distributed in gastric parietal cells. Furthermore, our data suggest a preferential, but not exclusive, interaction between beta-actin and ezrin in gastric parietal cells. Finally, our results suggest that the beta- and gamma-actin-based cytoskeleton networks might function separately in response to the stimulation of acid secretion.

Actins↗
PubMed1995

Alternative Function of the Electron Transport System in Azotobacter vinelandii: Removal of Excess Reductant by the Cytochrome d Pathway.

The N(inf2)-fixing bacterium Azotobacter vinelandii was grown in an O(inf2)-regulated chemostat with glucose or galactose as substrate. Increasing the O(inf2) partial pressure resulted in identical synthesis of the noncoupled cytochrome d terminal oxidase, which is consistent with the hypothesis that A. vinelandii uses high rates of respiration to protect the nitrogenase from oxygen. However, cell growth on glucose showed a lower yield of biomass, higher glycolytic rate, higher respiratory rate, and lower cytochrome o content than cell growth on galactose. Elemental analysis indicated no appreciable change in the C-to-N ratio of cell cultures, suggesting that the major composition of the cell was not influenced by the carbon source. A poor coordination of glucose and nitrogen metabolisms in A. vinelandii was suggested. The rapid hydrolysis of glucose resulted in carbonaceous accumulation in cells. Thus, Azotobacter species must induce a futile electron transport to protect cells from the high rates of glucose uptake and glycolysis.

Journal Article↗
PubMed1995

Expression of Na, K-ATPase alpha and beta isoforms in the neonatal rat cochlea.

The postnatal expression of five Na, K-ATPase alpha (alpha 1, alpha 2, alpha 3) and beta (beta 1, beta 2) subunit isoforms in the rat cochlea was investigated by immunocytochemistry. High levels of expression of the alpha 1 and beta 2 isoforms were observed in stria vascularis (SV) at all developmental stages. alpha 1 and beta 1 isoforms showed a distinct time-dependent developmental expression pattern in tissues of the spiral ligament (SL) and spiral limbus (SLi). Limited, temporary expression of alpha 2 and alpha 3 subunit isoforms were found in SV and SL. Expression of each isoform was also seen in organ of Corti (OC), spiral ganglion (SG), cochlear nerve (CN) and Kölliker's Organ (KO). These observations suggest that individual isoforms may exert specific actions postnatally during final cochlear maturation.

Animals↗
PubMed1995

[Application of oesophagogastric double anastomosis in the treatment of esophageal caustic stricture].

Between 1982 and 1992, nine cases of oesophageal caustic stricture underwent oesophagogastric double anastomosis with success. There was no need to dissect and resect the strictured esophagus, and traumatizing organs adjacent to oesophgus was avoided. This method also eliminated the possibility of occurrence mediastinal abscess due to postoperative rebindling or infection by the esophageal segment. Indications for this operation are as follows: the esophageal stenosis located below the aorta arch; the stomach mobilized and pulled up to the upper level above the aorta arch dispite the presence of scattered caustic shrinkage; to assess the location and extent of corrosive injury and determine the level of reestablishment of the digestive tract through routine preoperative fiberoptic oesophagoscopy. This simplified procedure shortens the operating time, but yields excellent result.

Adolescent↗