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W Guo

Publications and source records attributed to W Guo.

At least 217 records · Page 12Linked to original sources

Changes in action potentials and ion currents in long-term cultured neonatal rat ventricular cells.

A primary culture of neonatal ventricular myocytes isolated from day-old rats was established for investigating the changes in action potentials and ion currents over long periods. Cells at days 5 and 15 in culture were studied. These changes in vitro were compared with those in situ derived from the age-matched freshly isolated cells. During primary culture, quiescent cells demonstrated shortening of action potential durations (APD) resembling the developmental changes observed in situ. The beating cultured cells were not associated with APD shortening. Despite constant current amplitudes, the densities of Ca2+ currents (ICa) decreased in the quiescent cultures at later ages as a result of cell enlargement. ICa densities were maintained in the beating cultured and freshly isolated cells. Acceleration in the inactivation of ICa was observed during developments both in vitro and in situ. In addition, the densities of transient outward currents (Ito) tripled and doubled in the quiescent and beating cells during 15-day cultures. However, Ito in beating cultured cells made less contribution to APD in contrast to the quiescent cultured and freshly isolated myocytes. These findings demonstrate that electrophysiological properties differ between two types of long-term cultured cells. ICa densities remained constant in the beating cultures, suggesting that cell beating may be required for the maintenance of ICa density in developing cardiomyocytes.

Action Potentials↗

Nocturnal growth hormone (GH) secretion is eliminated by infusion of GH-releasing hormone antagonist.

The neuroendocrine mechanisms underlying the generation of pulsatile GH secretion in humans are poorly understood. GH secretory pulses are likely to result from acute GHRH secretory episodes, acute decreases in hypothalamic somatostatin secretion, or a combination of these mechanisms. In earlier studies we demonstrated that a single i.v. bolus of a competitive GHRH antagonist [N-Ac-Tyr1,D-Arg2)GHRH-(1-29); GHRH-Ant] blocked 40% of the nocturnal GH release. Failure to more completely eliminate nocturnal GH secretion could be due to either incomplete antagonism of endogenous GHRH action by GHRH-Ant or a non-GHRH component of GH release. We subsequently investigated whether a continuous infusion of GHRH-Ant would more completely eliminate nocturnal GH secretion. Eight men were given a 400 micrograms/kg i.v. bolus of GHRH-Ant at 2300 h, followed by a 50 micrograms/kg.h i.v. infusion of GHRH-Ant between 2300-0700 h or a saline bolus followed by a saline infusion. An i.v. bolus of GHRH (1 microgram/kg) was given at 0500 h on both occasions. Blood was sampled every 10 min between 2300-0700 h. As measured by the area under the curve (AUC) from 2400-0500 h, GHRH-Ant suppressed GH secretion by an average of 89% (1795 +/- 412 vs. 164 +/- 46 micrograms/min.L; P = 0.004). The response to GHRH was suppressed by 79% (484 +/- 140 vs. 64 +/- 19 micrograms/min.L; P = 0.02). These data demonstrate that the previously observed nonsuppressible GH secretion was probably due to incomplete blockade of pituitary GHRH receptors and that all or nearly all of nocturnal GH pulsatility can be attributed to the effect of hypothalamic GHRH.

Adolescent↗

Genomic sequence of the DAX1 gene: an orphan nuclear receptor responsible for X-linked adrenal hypoplasia congenita and hypogonadotropic hypogonadism.

The gene responsible for X-linked adrenal hypoplasia congenita, DAX1, encodes a member of the nuclear hormone receptor superfamily. We sequenced 8851 bp that contained the DAX1 genomic region. The DAX gene was composed of two exons and one 3.4-kilobase intron. Putative TATA and GC boxes and a putative steroidogenic factor 1 response element were present in the 5'-flanking region. Two potentially polymorphic short tandem repeats were identified. The first exon encoded two putative novel zinc finger motifs within a putative DNA binding domain and part of the ligand binding domain, and the second exon encoded the remainder of the ligand binding domain. Although the putative DNA binding domain of DAX1 does not contain substantial sequence similarity to other nuclear hormone receptor superfamily members, the putative ligand binding domain had remarkable similarity to other family members. Single-strand conformational polymorphism analysis permitted identification of three new mutations in DAX1. In conclusion, single-strand conformational polymorphism analysis facilitates identification of mutations in the DAX1 gene, and the short tandem repeats may permit linkage analysis in families in which mutations are not yet identified. We speculate that DAX1 may be the most primitive member of the nuclear hormone receptor superfamily identified in mammals.

Adrenal Insufficiency↗

Effects of chronic hypoxia on the developmental changes in action potential of cultured neonatal rat ventricular myocytes.

The action potentials of rat ventricular myocytes are known to become progressively shortened within several weeks after birth. We studied the effects of long-term exposure to hypoxia on these developmental changes in cardiac action potentials. Single ventricular myocytes isolated from day-old neonatal rat hearts were cultured in normoxic conditions (21% O2) for more than 15 days. To test the influence of long-term exposure to hypoxia, O2 tension was lowered to 7.5% in some cells at day 6. Action potentials were measured at day 5 and day 15 in both the normoxic and hypoxic groups. Under normoxic conditions, action potential durations decreased by 44% between day 5 and day 15, while cell capacitance doubled (n=10-11). Under hypoxic conditions, action potential durations decreased slightly by 16% (n=6). This shortening was significantly attenuated when compared to that observed during normoxic conditions. Cell capacitance was not altered under the hypoxic conditions. These results suggest that 1) shortening of the action potential during normoxic culturing is prevented under hypoxic conditions, and 2) cell capacitance as seen in normoxic conditions is unaffected by hypoxic culturing.

Action Potentials↗

[Experiment study on biological and immunological characteristics of modified DNL of oral squamous cell carcinoma with TNF-alpha gene]

Growing characteristic of gene-transduced and nontransduced DNL in medium of containing rIL-2 was compared,and growing characteristic of gene-transduced DNL in medium of non containing rIL-2 was analyzed.DNA index (DI),cell cycle and immunologic phenotypes of gene-transduced and nontransduced DNL were analyzed with FACS.The results revealed interfered with growth,DL,cell cycle and immunologic phenotypes of DNL,and gene-transduced DNL couldn't growing infinitely.

Journal Article↗

The gene responsible for adrenal hypoplasia congenita, DAX-1, encodes a nuclear hormone receptor that defines a new class within the superfamily.

X-linked adrenal hypoplasia congenita (AHC) is an inherited disorder of the development of the adrenal cortex. The gene responsible for this genetic disorder has been identified using positional cloning methods and has been named DAX-1 based on its localization within the dosage-sensitive sex reversal (DSS) locus and the AHC locus on the X chromosome. The DAX-1 gene consists of two exons separated by a 3.4 kb intron. Analysis of DNA from patients with deletions in the AHC critical region in the X chromosome provided strong indication for the involvement of the DAX-1 gene in X-linked AHC. A number of intragenic mutations within the DAX-1 gene have also been identified in patients with isolated AHC. The DAX-1 gene product belongs to the nuclear hormone receptor superfamily based on the presence of an entire ligand binding domain present in the carboxy-terminal region of the receptor. However, DAX-1 has a domain structure which is very unusual with respect to other nuclear hormone receptor superfamily members. The amino-terminal portion of DAX-1 contains a novel domain consisting of 3.5 repeats of a 65-67 amino acid motif that contains two putative zinc finger structures in place of the more usual amino-terminal domain, DNA binding domain, and hinge region of the typical nuclear hormone receptors. It has been proposed that the amino-terminal portion of the DAX-1 protein is the DNA binding domain. The expression pattern of DAX-1 suggests that it may play a role in the regulation of steroidogenesis. Not only is DAX-1 expressed in the adrenal glands, but it is also expressed in the ovaries and testes. Most recently, we demonstrated that DAX-1 is also expressed in the hypothalamus and pituitary gland. The expression of DAX-1 in the neuroendocrine system suggests that interruption of the expression in these tissues may be the cause of the hypogonadotropic hypogonadism (HH) that is frequently associated with AHC. Interestingly, hybridization of a human DAX-1 cDNA probe with genomic DNA from various species indicated that a DAX-1 homologue may exist in yeast. Thus, DAX-1 or a DAX-1-like transcription factor may be the most primitive member of the nuclear hormone receptor superfamily. Although the molecular mechanism of action of DAX-1 is not yet characterized, its importance for the development and physiology of the adrenal gland and gonads is indicated by its involvement in AHC and HH. Analysis of the functions of DAX-1 along with its regulation of expression will not only provide information concerning the actions of this new member of the nuclear hormone receptor superfamily, but will also yield insight into the pathogenesis of AHC and HH and may allow for the development of gene therapy protocols for the treatment of these diseases.

Adrenal Insufficiency↗

A flow cytometric study on giant cell tumor of bone.

OBJECTIVE: Giant cell tumor of bone (GCT) is a comparatively common bone tumor in Chinese. Though GCT is generally considered as a benign tumor, it can pursue an aggressive course. The present study attempts to clarify whether the flow cytometric study can be an useful tool for prognosis of GCT patients. METHODS: DNA content and cell cycle studies on 96 pathologically confirmed GCT specimens and anti-GCT monoclonal antibody (GCF-5 McAb) labeling study on 30 GCTs were made by flow cytometry. RESULTS: 29 GCTs (30.2%) exhibited aneuploid and 67 (69.8%) diploid. Of 71 primary tumors, 16 (22.5%) exhibited aneuploid. The DNA index was 0.97+0.15, and the average S, G2/M phase cells 15.23+6.15%. Of 25 recurrent tumors, 13 (52%) were aneuploid, with an average DI of 1.08+0.17. The average S, G2/M phase cells was 19.56+7.12%. Between the primary and recurrent tumor groups, there was significant statistical difference both in S, G2/M phase cell percentage (P < 0.05) and DNA content (P < 0.01). There was no significant difference between Jaffe's grade I and grade II groups in DNA content or in S, G2/M phase cell percentage. GCF-5 McAb could combine with almost all cells of S, G2/M phase and part of the cells in G0/G1 phase. Significant relationship existed (r=0.468, P < 0.05) between the percentages of S, G2/M phase cells and GCF-5 positive cells. Between the primary and the recurrent tumor groups, there was a significant difference in the percentage of both S, G2/M phase cells and GCF-5 positive cells. CONCLUSION: Apparently flow cytometric study is of value in the evaluation of the biological behavior of GCT as well as the prognosis of the patients.

Adult↗

Modulated expression of transient outward current in cultured neonatal rat ventricular myocytes: comparison with development in situ.

OBJECTIVES: Developmental changes of cardiac ion channels have been characterized in freshly isolated mammalian heart cells. To investigate the regulatory factors of postnatal development in transient outward current (Ito) in cardiomyocytes, the modulated expression of Ito was studied in cultured neonatal rat ventricular cells. These changes in vitro were compared with those in situ in acutely isolated ventricular myocytes. METHODS: Ventricular cells were enzymatically isolated from day-old Wistar rats and cultured under various growth conditions from day 6 to 15. Whole-cell patch-clamp recording was used to study the functional expression of Ito. RESULTS: During development in situ from 5- to 15-day-old stages, Ito density was doubled at day 15 with a significant increase in membrane capacitance (Cm) of the myocytes. Some cells were incubated in serum-rich medium from day 6 to 15 during primary culture, revealing marked increases in both Cm and Ito density at day 15. However, no developmental changes in the Cm and Ito density were observed in serum-free medium. Under the serum-free condition, neither the addition of acidic fibroblast growth factor (aFGF) nor basic FGF (bFGF) to culture medium influenced the Cm. aFGF (10-60 ng/ml) failed to stimulate Ito expression. 72-h treatment with bFGF significantly promoted the Ito density in a concentration-dependent manner; nevertheless, prolonged administration from day 6 to 15 did not induce a further increase, resulting in lower Ito density than in age-matched freshly isolated and serum-treated preparations. The increase in Ito in cultured cells induced by serum and bFGF may be attributable to paralleling changes in the ionic selectivity of the channel, but was not caused by changes in the voltage-dependence of steady-state Ito activation and inactivation. CONCLUSIONS: bFGF and some other unknown serum factors may play important roles in the postnatal expression of Ito in the neonatal cardiomyocytes. The developmental increase in Ito and postnatal cell hypertrophy of neonatal cardiomyocytes can be regulated independently.

Animals↗

P53 gene abnormalities in osteosarcoma.

OBJECTIVE: The P53 tumor suppressor gene shows the most frequent genetic alteration in human tumors. Mutation, deletion and rearrangement of P53 gene have been found in several types of neoplasm including osteosarcoma. The present study is to clarify the status of abnormalities of this gene in osteosarcoma in China. MATERIALS AND METHODS: Forty-six osteosarcomas were collected from 32 male and 14 female patients aged 20.6 years on average. Eight patients had lung metastasis. Immunohistochemistry, Southern blot and contrast flow cytometry were used for the study. RESULTS: Twenty-seven of 46 (58.7%) osteosarcoma specimens showed strongly positive reaction to the MoAb BP53-12 staining (+2 - +3), which indicated overexpression of P53 protein in osteosarcoma. Contrast study with DNA flow cytometry made on osteosarcoma showed that most of the tumors with strongly positive P53 have higher DNA content than those of negative ones. Alterations of the restriction pattern of the P53 gene were detected in 4 of 20 osteosarcomas in the Hind III group and 3 of 24 in the Eco R I group. Three of them were part or whole deletion of the gene and five of them had extraband which indicated rearrangement of the gene. CONCLUSIONS: The results of this study showed that overexpression of P53 oncoprotein is one of the most frequent genetic changes in osteosarcoma and P53 oncoprotein expression analysis could be a prognostic parameter in osteosarcoma. P53 gene abnormalities play an important role in the development of transformation and proliferation of osteosarcoma cells.

Adult↗

A study on detection of serum fasting total bile acid and choloyglycin in neonate for cholestasis.

Enzyme-linked colorimetric analysis and radioimmunoassay were employed to detect serum fasting total bile acids (FBA) and choloyglycin (CG) respectively in cases of 32 neonatal hepatitis, 33 cases of neonatal unconjugated hyperbilirubinemia and 34 cases of breast milk jaundice (BMJ). FBA and CG in acute period of neonatal hepatitis were obviously elevated and decreased gradually in convalescent and recovered period. The difference was significant for each stage as compared with controls. Acute FBA correlated strongly with the course. Both neonatal unconjugated hyperbilirubinemia and BMJ differed significantly from controls in FBA and CG. The results suggested that serum FBA and CG were helpful in judging the course and state of neonatal hepatitis, and cholestasis might existed in neonatal unconjugated hyperbilirubinemia.

Bile Acids and Salts↗

Cloning of a new pectate lyase gene pelC from Fusarium solani f. sp. pisi (Nectria haematococca, mating type VI) and characterization of the gene product expressed in Pichia pastoris.

Antibodies prepared against a pectate lyase (PLA) produced by a phytopathogenic fungus Fusarium solani f. sp. pisi (Nectria haematococca, mating type VI) were previously found to protect the host against infection. The cDNA and gene (pelA) for PLA were cloned and sequenced. A new pectate lyase gene, pelC, was isolated from a genomic library of F. solani pisi with pelA cDNA as a probe. A 1.3-kb DNA fragment containing the pelC gene and its flanking regions was identified and sequenced. The coding region of pelC was amplified by reverse transcription-polymerase chain reaction using total RNA isolated from a pectin-induced F. solani pisi culture as template. The open reading frame of pelC was predicted to encode a 23.3-kDa protein of 219 amino acid residues, which shares 51% identity with PLA from F. solani pisi. No typical fungal leader peptide sequence could be identified at the N-terminus of the predicted protein sequence. The amplified pelC cDNA was expressed in Pichia pastoris yielding a pectate lyase C (PLC) with a molecular mass of 26.0 kDa and containing carbohydrates. PLC was purified to homogeneity using Mono Q anion-exchange chromatography. Purified PLC required Ca2+ for its activity and showed optimal lyase activity at pH 9.5 and 55 degrees C. Rapid drop in the viscosity of the substrate and Mono Q anion-exchange chromatography of the products generated by the lyase showed that PLC cleaved polygalacturonate chains in an endo fashion. Western blot using antibodies raised against PLA and PLC showed that PLC and PLA are immunologically related to each other.

Amino Acid Sequence↗

A multinuclear solid-state NMR study of phospholipid-cholesterol interactions. Dipalmitoylphosphatidylcholine-cholesterol binary system.

Multinuclear (1H, 13C, 31P) MASNMR and static solid-state 31P NMR were used to study the molecular interactions between dipalmitoylphosphatidylcholine (DPPC) and free cholesterol (CHOL) in multilayers of DPPC containing 0-65 mol % CHOL with respect to total lipid at temperatures between 25 and 55 degrees C. 13C chemical shifts and line shapes for DPPC and CHOL resonances were measured in 13C MASNMR spectra. The apparent chemical shift anisotropy (CSA) of the DPPC acyl methylene resonances [(CH2)n] was calculated from the 1H MASNMR spectra. CSA and line shape changes were recorded as a function of CHOL content by 31P static solids and MASNMR. The presence of CHOL significantly changed the 13C chemical shifts and line shapes of DPPC carbonyl carbons below or above the main transition temperature of pure DPPC. Chemical shift changes were also observed for CHOL carbons as a function of the mixing ratio, signifying a changing local environment of CHOL. For mixtures with CHOL > 50 mol %, 13C MASNMR detected crystalline CHOL in the monohydrate form. When the excess CHOL was in a submicroscopic crystalline form that was not readily detected by differential scanning calorimetry, or optical microscopy (but readily observed by 13C MASNMR), the 31P powder pattern was affected, suggesting interaction of the excess CHOL with the aqueous interface of the bilayer. These results suggest the potential of 13C MASNMR for detection of crystalline CHOL in biological samples.

1,2-Dipalmitoylphosphatidylcholine↗

Identification of a putative steroidogenic factor-1 response element in the DAX-1 promoter.

The nuclear hormone receptor, DAX-1, is responsible for X-linked adrenal hypoplasia congenita and hypogonadotrophic hypogonadism. We recently cloned the 5' flanking region of the human DAX-1 gene and in this report we describe the identification of a putative steroidogenic factor 1 (SF-1) response element approximately 110 bases upstream of the TATA box. Both DAX-1 and SF-1 are expressed in similar tissues including the adrenal cortex, gonads, hypothalamus, and the pituitary gland. Like DAX-1, SF-1 expression has been shown to be essential for the development of the adrenal cortex. We demonstrate that SF-1 is able to efficiently bind to the putative SF-1 response element found in the DAX-1 promoter in vitro. This suggests that SF-1 may directly regulate the expression of DAX-1 and that these two transcription factors may be components of a cascade required for development of steroidogenic tissues.

Base Sequence↗

Diagnosis of X-linked adrenal hypoplasia congenita by mutation analysis of the DAX1 gene.

OBJECTIVE: To develop a rapid diagnostic approach to individuals with the X-linked cytomegalic form of adrenal hypoplasia congenita (AHC) and hypogonadotropic hypogonadism (HH) due to mutations in DAX1, a new member of the nuclear hormone receptor gene superfamily. DESIGN: Molecular genetic diagnostic investigations of individuals with AHC and their relatives included polymerase chain reaction amplification of DAX1 for identification of intragenic mutations and fluorescence in situ hybridization with a cosmid containing the DAX1 gene for evaluation of larger deletions. PARTICIPANTS: Families that had males affected with AHC were evaluated for mutations involving the DAX1 gene. RESULTS: DAX1 mutations were identified in four families that had males affected with AHC. Two apparently independent pedigrees had an identical frame-shift mutation due to a single base pair deletion, and a third had a larger deletion involving the entire DAX1 locus. The fourth family was evaluated by fluorescence in situ hybridization for prenatal diagnosis, and both the DAX1 locus and the contiguous glycerol kinase region were deleted. CONCLUSIONS: Molecular genetic and molecular cytogenetic techniques represent rapid and complementary approaches to the diagnosis of mutations in the DAX1 gene responsible for AHC and the associated HH. Specific diagnosis of the cause of adrenal insufficiency in these boys permits anticipatory management of the HH and prenatal counseling for parents of the affected child and other members of their families.

Adrenal Insufficiency↗

Association of triadin with the ryanodine receptor and calsequestrin in the lumen of the sarcoplasmic reticulum.

Triadin is a major membrane protein that is specifically localized in the junctional sarcoplasmic reticulum of skeletal muscle and is thought to play an important role in muscle excitation-contraction coupling. In order to identify the proteins in the skeletal muscle that interact with triadin, the cytoplasmic and luminal domains of triadin were expressed as glutathione S-transferase fusion proteins and immobilized to glutathione-Sepharose to form affinity columns. Using these affinity columns, we find that triadin binds specifically to the ryanodine receptor/Ca2+ release channel and the Ca(2+)-binding protein calsequestrin from CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid)-solubilized skeletal muscle homogenates. The luminal but not the cytoplasmic domain of triadin-glutathione S-transferase fusion protein binds [3H]ryanodine receptor, whereas neither the cytoplasmic nor the luminal portion of triadin binds [3H]PN-200-100-labeled dihydropyridine receptor. In addition, the luminal domain of triadin interacts with calsequestrin in a Ca(2+)-dependent manner and is capable of inhibiting the reassociation of calsequestrin to the junctional face membrane. These results suggest that triadin is the previously unidentified transmembrane protein that anchors calsequestrin to the junctional region of the sarcoplasmic reticulum, and is involved in the functional coupling between calsequestrin and the ryanodine receptor/Ca2+ release channel.

Animals↗

Expression of DAX-1, the gene responsible for X-linked adrenal hypoplasia congenita and hypogonadotropic hypogonadism, in the hypothalamic-pituitary-adrenal/gonadal axis.

DAX-1, an orphan member of the nuclear hormone receptor superfamily, is responsible for X-linked adrenal hypoplasia congenita (AHC) and the frequently associated hypogonadotropic hypogonadism (HH). The entire DAX-1 genomic region has been sequenced and a putative steroidogenic factor-1 response element has been identified in the promoter region of the gene. The purpose of these investigations was to determine if DAX-1 was expressed in the central nervous system, particularly the hypothalamus and pituitary, in order to better understand the relationship of mutations in this gene to HH associated with AHC. We used Northern blot analysis and reverse transcription PCR to demonstrate that DAX-1 was expressed in the hypothalamus and the pituitary, and to confirm its expression in adrenal cortex and gonads. The expression of DAX-1 in these tissues indicates the involvement of DAX-1 in the development of the reproductive system at multiple levels within the hypothalamic-pituitary-adrenal/gonadal axis. We also observed the expression of DAX-1 in a human adrenocortical carcinoma cell line, NCI-H295, that has features characteristic of the fetal adrenal cortex. Therefore, NCI-H295 cells will be a useful cellular model for investigating the involvement of DAX-1 in the regulation of steroidogenesis.

Adrenal Cortex↗

The effect of epidermal growth factor on mucosal function after ileal resection.

Since epidermal growth factor (EGF) enhances gut mucosal regeneration, the present study was undertaken to evaluate the effect of EGF on brush-border membrane enzyme activity and glutamine uptake in the intestinal remnant following extensive small bowel resection. Twenty-four adult male New Zealand White rabbits were divided into three groups: Group 1 (n = 12) served as controls. Groups 2 and 3 (n = 6 each) underwent a 50-60% mid-jejunoileal resection with anastomosis of the remaining intestine, leaving 90 cm between the pylorus and the ileocecal valve. Group 3 rabbits had a subcutaneous osmotic pump implanted to deliver EGF for 7 days at 0.3 micrograms/kg/hr. Rabbits from Groups 2 and 3 were sacrificed 3 weeks postoperation. Mucosa from the proximal and distal segments of the remaining intestine was analyzed for wet/dry weight, maltase and aminooligopeptidase activity, and glutamine uptake. There was a twofold increase in mucosal dry weight/cm of intestine in rabbits without EGF at 3 weeks (Group 2) and a fourfold increase in those given EGF (Group 3). The maltase enzyme capacity (UEnzyme/rabbit) increased from 37 +/- 10 in controls (Group 1) to 167 +/- 30 without EGF and 207 +/- 30 with EGF. The aminooligopeptidase enzyme capacity (UEnzyme/rabbit) increased from 55 +/- 10 to 147 +/- 20 and 226 +/- 30 in Groups 1, 2, and 3, respectively. Glutamine uptake capacity (microM glutamine/min) also increased significantly, from 63 +/- 19 in Group 1 to 88 +/- 6 without EGF and 162 +/- 18 with EGF (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗