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W Guo

Publications and source records attributed to W Guo.

At least 181 records · Page 10Linked to original sources
PubMed1997

Identification and characterization of homologues of the Exocyst component Sec10p.

The SEC10 gene product is a member of the Exocyst complex essential for exocytosis in the budding yeast Saccharomyces cerevisiae. We report here the cloning and characterization of human Sec10p (hSec10p; GenBank accession number U85946). hSec10p is a 77-kDa protein with 23% amino acid identity to yeast Sec10p and 37% identity to a C. elegans protein found in the database. Northern and Western blot analyses indicate that hSec10 has a broad tissue distribution. Immunofluorescence staining of COS cells cotransfected with hSec10p and a mammalian Sec8p demonstrates that these two proteins have an identical distribution in the cell including a localization in the peripheral cytoplasm. These data suggest that hSec10p is a component of the mammalian counterpart of the yeast Exocyst complex essential for post-Golgi traffic.

Amino Acid Sequence↗
PubMed1997

Identification of a ferritin light chain pseudogene near the glycerol kinase locus in Xp21 by cDNA amplification for identification of genomic expressed sequences.

We used cDNA amplification for identification of genomic expressed sequences (CAIGES) to identify genes in the glycerol kinase region of the human X chromosome. During these investigations we identified the sequence for a ferritin light chain (FTL) pseudogene in this portion of Xp21. A human liver cDNA library was amplified by vector primers, labeled, and hybridized to Southern blots of EcoRI-digested human genomic DNA from cosmids isolated from yeast artificial chromosomes in the glycerol kinase region of Xp21. A 3.1-kb restriction fragment hybridized with the cDNA library, was subcloned and sequenced, and a 440-bp intronless sequence was found with strong similarity to the FTL coding sequence. Therefore, the FTL pseudogene that had been mapped previously to Xp22.3-21.2 was localized specifically to the glycerol kinase region. The CAIGES method permits rapid screening of genomic material and will identify genomic sequences with similarities to genes expressed in the cDNA library used to probe the cloned genomic DNA, including pseudogenes.

Base Sequence↗
PubMed1997

DAX1 gene expression upregulated by steroidogenic factor 1 in an adrenocortical carcinoma cell line.

Two nuclear hormone receptor superfamily members, DAX1 and SF1, are required for normal adrenal cortical development. Mutations in DAX1 are responsible for X-linked adrenal hypoplasia congenita (AHC) and hypogonadotropic hypogonadism. Steroidogenic Factor 1 (SF1) regulates the expression of a number of steroidogenic genes and a putative SF1 response element (SF1-RE) in the DAX1 promoter which binds SF1 specifically. Therefore, we examined deletions in the DAX1 promoter driving expression of beta-galactosidase, with and without coexpression of SF1, in the human adrenocortical carcinoma cell line NCI-H295. We defined the DAX initiation start site and localized the putative SF1-RE at -135 to -143 bp. Loss of the putative SF1-RE region or specific removal of the 9-bp SF1 site resulted in decreased transcriptional activity by 2.3-to 2.5-fold. When cotransfected with 1550 bp of the DAX1 promoter, an SF1-containing expression vector increased the transcriptional activity of the DAX1 promoter by 4-fold. No significant change above baseline occurred when the cells were cotransfected with the 1541-bp fragment containing the entire 1550-bp promoter region minus the 9-bp SF1-RE. We conclude that the SF1-RE is an enhancer element within the DAX1 promoter and speculate that SF1 may be a transcription factor that acts, at least in part, through DAX1 for normal adrenal cortical development.

Adrenocortical Carcinoma↗
PubMed1997

Evidences of antagonism between amiodarone and triiodothyronine on the K+ channel activities of cultured rat cardiomyocytes.

Effects of acute and chronic treatments with amiodarone, both in the presence and the absence of exogenous triiodothyronine (T3), on repolarizing outward K+ currents were investigated by patch-clamp technique in cultured newborn rat ventricular cells. Acute exposure to amiodarone dose-dependently inhibited the transient outward (Ito IC50 = 4.9 microM) and the steady-state outward (IK, IC50 = 6.3 microM) K4 currents. The dose-response curve of this acute inhibitory action was unaffected by the presence of T3. When amiodarone was applied chronically. 72-h exposure to a low dose of the drug (1 microM) significantly decreased the current densities of Ito and I kappa for the cells cultured in a serum-supplemented medium containing 0.12 nM T3. In a serum-free medium without T3o chronic amiodarone treatment revealed null effect on either Ito or IK. In addition, 72-h in-vitro treatment with Ti enhanced the current densities of both Ito (EC50 = 0.13 nM) and I kappa (EC50 = 0.33 nM). Concentration-response analysis indicated that amiodarone (1 microM) showed competitive inhibition towards the action of T3 on Ito but noncompetitive inhibition towards the action of T3 on IK. These results suggest that different ionic mechanisms are produced by acute and long-term treatments with amiodarone. The latter showed T3-dependent inhibition of cardiac Ito and IK. When chronically administered, amiodarone may antagonize T3 and thereby counteract its hormonal effect on K+ channels. This implies that, at the myocyte level, antagonism of the action of thyroid hormones in K+ channel activities may contribute to the cardiac effects of chronic amiodarone therapy.

Amiodarone↗
PubMed1997

Developmental changes of the ultrarapid delayed rectifier K+ current in rat ventricular myocytes.

Recent studies have shown the presence of a 4-aminopyridine (4-AP) sensitive, ultrarapid delayed rectifier K+ current (IK,ur) in adult human atria, but an apparent absence of this current in adult human ventricles. The present experiment was designed to investigate the postnatal changes of IK,ur in rat ventricular myocytes. The presence of IK,ur was evaluated with the use of a low concentration of 4-AP (50 micro;M). In 3-day-old newborns, the channel activity of rapidly activating outward current was predominantly the transient outward current (Ito). IK,ur could be recorded in a small number of 3-day-old cells lacking Ito (16%). In 10-day-old and adult rat ventricular myocytes, almost all cells expressed Ito and its current density increased significantly with age. The fraction of cells expressing IK,ur dramatically decreased with age and no IK,ur-like component could be detected in the adult cells. These findings first demonstrate that the expression of IK,ur is regulated developmentally in mammalian ventricular myocytes.

4-Aminopyridine↗
PubMed1997

Roles of the voltage-gated K+ channel subunits, Kv 1.5 and Kv 1.4, in the developmental changes of K+ currents in cultured neonatal rat ventricular cells.

To investigate the roles of voltage-gated K+ channel subunits, Kv 1.5 and Kv 1.4, in the developmental regulation of K+ currents, we determined the K+ channel activities and the distributions of K+ channel subunits in the same single cultured neonatal rat ventricular cells, using a whole-cell patch-clamp technique and an immunocytochemical analysis of K+ channel proteins. In 5-day cultured cells, two types of 4-aminopyridine (4-AP)-sensitive and rapidly activating K+ currents, the transient outward current (Ito) and the ultrarapid delayed rectifier (IKur), could be distinguished. A small proportion of 5-day cells expressing sole IKur demonstrated an intense anti-Kv 1.5 antibody labeling with punctate distribution outlining the cells, while a weak staining was observed in the majority of 5-day cells expressing sole Ito. At day 15 of cell culture, only Ito was present with a lower level of the immunocytochemical expression of Kv 1.5 channel protein. Staining of the Kv 1.4 channel protein was qualitatively similar in the 5-day cells expressing either Ito or IKur. However, anti-Kv 1.4 antibody did not label the 15-day cultured cells showing remarkably increased Ito density. Our results strongly indicate that the Kv 1.5 channel expression may underlie the developmental regulation of IKur, while Kv 1.4 channel does not contribute to the postnatal increase in Ito.

Animals↗
PubMed1997

Differential effects of chronic membrane depolarization on the K+ channel activities in cultured rat ventricular cells.

OBJECTIVE: Although there is widespread interest in the regulation of K+ channel gene expression by membrane depolarization, its effects on cardiac ion channel activity remain unclear. In the present study, we investigated the influences of chronic membrane depolarization on the functional expression of K+ channels in cultured rat cardiomyocytes. METHODS: Single ventricular cells isolated from day-old rat hearts were cultured for nearly 10 days. From day 6, chronic depolarization induced by elevating the K+ concentration of growth medium to 20 mM was developed for 72 h. Whole-cell patch-clamp techniques were used to record action potentials and ion currents. RESULTS: Compared with controls, longer action potential durations associated with relatively positive resting potentials were observed after 72-h high K+ incubation. Chronic membrane depolarization caused a significantly reduced density of transient outward current (Ito) without affecting the channel kinetics and voltage-dependence. Delayed rectifier K+ current (IK) in cultured cells could be inhibited by E-4031, showing the drug-sensitive and -resistant components with different kinetic properties. The E-4031-sensitive current activated rapidly, and the drug-resistant current was characterized by slow activation. Both the rapid (IKr) and slow (IKs) components constituted IK recorded from the control and depolarization-treated cells, while in the latter group the current density of IKr was slightly increased and that of IKs was enhanced by 80% with a small hyperpolarizing shift (5 mV) in the voltage-dependent activation curve. CONCLUSIONS: These observations suggest that the effects of chronic membrane depolarization differ depending on the phenotype of the cardiac K+ channels.

Action Potentials↗
PubMed1997

Role of intestinal P-glycoprotein (mdr1) in interpatient variation in the oral bioavailability of cyclosporine.

Interpatient differences in the oral clearance of cyclosporine (INN, ciclosporin) have been partially attributed to variation in the activity of a single liver enzyme termed CYP3A4. Recently it has been shown that small bowel also contains CYP3A4, as well as P-glycoprotein, a protein able to transport cyclosporine. To assess the importance of these intestinal proteins, the oral pharmacokinetics of cyclosporine were measured in 25 kidney transplant recipients who each had their liver CYP3A4 activity quantitated by the intravenous [14C-N-methyl]-erythromycin breath test and who underwent small bowel biopsy for measurement of CYP3A4 and P-glycoprotein. Forward multiple regression revealed that 56% (i.e., r2 = 0.56) and 17% of the variability in apparent oral clearance [log (dose/area under the curve)] were accounted for by variation in liver CYP3A4 activity (p < 0.0001) and intestinal P-glycoprotein concentration (p = 0.0059), respectively. For peak blood concentration, liver CYP3A4 activity accounted for 32% (p = 0.0002) and P-glycoprotein accounted for an additional 30% (p = 0.0024) of the variability. Intestinal levels of CYP3A4, which varied tenfold, did not appear to influence any cyclosporine pharmacokinetic parameter examined. We conclude that intestinal P-glycoprotein plays a significant role in the first-pass elimination of cyclosporine, presumably by being a rate-limiting step in absorption. Drug interactions with cyclosporine previously ascribed to intestinal CYP3A4 may instead be mediated by interactions with intestinal P-glycoprotein.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Relationship of esophageal anastomotic tension to the development of gastroesophageal reflux.

BACKGROUND/PURPOSE: Gastroesophageal reflux (GER) is a common occurrence after repair of congenital esophageal atresia and is believed to be more frequent when the esophageal anastomosis is performed under tension. This study documents that esophageal anastomotic tension correlates directly with the severity of acid reflux into the esophagus in the rabbit model. METHODS: Eight adult rabbits underwent complete esophageal transection with immediate reanastomosis (EA) and 12 underwent resection of a 1-cm segment of the midesophagus with reanastomosis under mild tension (EAT). Three-weeks postoperation continuous lower esophageal pH (LEpH) values were recorded for a 24-hour period for each rabbit, and compared with five normal unoperated rabbits. RESULTS: The normal rabbit's average LEpH is 7.7. EA rabbits had LEpH values below 5.0 for a mean of 56 min/24 hr (3.8% of monitored time). EAT rabbits had LEpH values below 5.0 for a mean of 328 min/24 hr (25.5% of monitored time; P < .05). EA rabbits had a mean of 8.8 reflux episodes under 5.0/24 hr, whereas EAT rabbits had a mean of 29.6 reflux episodes under 5.0. All EAT rabbits had moderate to severe anastomotic strictures; no EA rabbits had strictures. There were no anastomotic leaks. CONCLUSIONS: Esophageal anastomosis with mild tension in the rabbit causes severe GER with resultant anastomotic strictures in almost all rabbits, in contrast to rabbits undergoing esophageal anastomosis without tension in whom strictures did not develop and had only small reduction in esophageal pH values.

Anastomosis, Surgical↗
PubMed1997

Induction of Na+/myo-inositol co-transporter mRNA after rat cryogenic injury.

Myo-inositol is one of the major organic osmolytes in the brain. It is stored in the cells by the Na+/myo-inositol co-transporter (SMIT) which is regulated by extracellular osmolality. First, in order to confirm that local change of the osmolality induces alteration of the SMIT mRNA in brain, we examined change of SMIT mRNA of the animals with hypertonic NaCl application to the cortex. Application of hypertonic NaCl up-regulated the SMIT mRNA expression widely surrounding the application site. We next investigated the role of SMIT in brain during vasogenic edema, we examined expression of SMIT mRNA in the rat brain after cryogenic injury. The expression of SMIT mRNA was markedly increased 12 h after surgery and the induction of the mRNA extended to the entire cortex of the affected side. Up-regulated expression was found predominantly in the neurons in remote areas. The induction of SMIT mRNA was found until the 3rd day after surgery. These findings suggest that osmotic stress may spread over a wide area in the cortex in case of vasogenic edema produced by cryogenic injury and that the cells respond to this stress by increasing SMIT expression.

Animals↗
PubMed1997

Developmental regulation of Na+ / myo-inositol cotransporter gene expression.

myo-Inositol plays a role in many important aspects of cellular regulation including membrane structure, signal transduction and osmoregulation. It is taken up into the cells by the Na+ / myo-inositol cotransporter (SMIT). We investigated developmental changes in the expression of SMIT mRNA and protein in the rat. In the fetal rat brain, SMIT mRNA was abundantly and diffusely expressed throughout the whole brain and the spinal cord. Positive signals were expressed in neuronal and non-neuronal cells in these regions. SMIT is gradually down-regulated nearer birth, but intense signals were still detected in the brain at postnatal day one. In the adult rat brain, very weak hybridization signals were detected throughout whole brain except for the choroid plexus where SMIT mRNA expression remained high. In contrast, the pattern of developmental regulation of SMIT gene expression in the kidney was opposite to that seen in the brain. Signals in the kidney were very weak during embryonic stages, whereas SMIT expression increased significantly after birth. These results suggest that myo-inositol and its transporter play an important role in the CNS developmental stage.

Aging↗
PubMed1997

Role of screening for hepatitis C virus in children with malignant disease and who undergo bone marrow transplantation.

BACKGROUND: Children with malignant disease who received multiple blood transfusions before the clinical definition of hepatitis C virus (HCV) require evaluation for HCV infection. STUDY DESIGN AND METHODS: The role of HCV infection in 54 children with primary malignant disease was evaluated in terms of the following aspects: prevalence of HCV infection, distribution of HCV subtype, the benefit of screening of blood donors, and the presence of chronic liver disease. The benefit of screening for HCV in a subset of patients who underwent bone marrow transplantation (BMT) was also evaluated. RESULTS: Seventeen patients (31.4%) of 54 tested were seropositive in a second-generation HCV antibody test. Thirteen patients (24.0%) were also positive for circulating HCV RNA. HCV subtype 1b and HCV subtype 2b were found in six and two patients, respectively. Multiple HCV genotypes were present in two patients. One of these two patients had relatively progressive liver disease. Before the introduction of blood screening with a second-generation HCV antibody test, 15 of 35 patients seroconverted, whereas none of 7 patients seroconverted after the screening was used (p = 0.032). For patients who underwent BMT, the screening drastically decreased the seroconversion rate, from 7 of 11 patients to 0 of 6 (p = 0.016). CONCLUSION: A considerable number of children with primary malignant disease who received multiple blood transfusions became infected by HCV before HCV screening was used. Patients who underwent BMT were at high risk for HCV infection. Screening with a second-generation HCV antibody test has proven to be remarkably beneficial in preventing HCV infection in these children.

Adolescent↗
PubMed1997

Apparent digenic inheritance of Waardenburg syndrome type 2 (WS2) and autosomal recessive ocular albinism (AROA).

Waardenburg syndrome (WS) is a clinically and genetically heterogeneous disease accounting for >2% of the congenitally deaf population. It is characterized by deafness in association with pigmentary anomalies and various defects of neural crest-derived tissues. At least four types are recognized (WS1, WS2, WS3 and WS4) on the basis of clinical and genetic criteria. Two previously described families seemed to delineate a new subtype characterized by WS2 in conjunction with ocular albinism (OA). Since mutations in the MITF gene are responsible for some instances of WS2, we screened for mutations in one of the WS2-OA families and discovered a 1 bp deletion in exon 8 of MITF. OA previously has been associated with compound heterozygosity for a mutant TYR allele and the TYR(R402Q) allele, a functionally significant polymorphism that is associated with moderately reduced tyrosinase catalytic activity. In this family, all of the individuals with the OA phenotype are either homozygous or heterozygous for TYR(R402Q), and heterozyous for the 1 bp deletion in MITF This suggests that the WS2-OA phenotype may result from digenic interaction between a gene for a transcription factor (MITF) and a gene that it regulates (TYR).

Albinism, Ocular↗
PubMed1997

IGF-I regulates K(+)-channel expression of cultured neonatal rat ventricular myocytes.

Insulin-like growth factor (IGF) I has been known as an important peptide during heart development and myocardial hypertrophy. In the present study, the effects of IGF-I on cardiac K(+)-channel expression were investigated in cultured neonatal rat ventricular myocytes. Two distinct 4-aminopyridine (AP)-sensitive and rapidly activating outward K+ currents (IK) were observed. The predominant K(+)-channel current in cultured cells was a fast inactivating current similar to a 4-AP-sensitive transient outward current [I(to) half-maximal inhibitory concentration (IC60) = 0.87 mM]. Some cells lacking I(to) expressed an IK with little or no slow inactivation. IK exhibited higher sensitivity to inhibition by 4-AP (IC50 = 66.5 microM) and could be enhanced by isoproterenol but unaffected by tetraethylammonium. These characteristics indicate that IK might be the rat isoform of ultrarapid delayed rectifier K+ current IKur previously described in human atrial myocytes. Seventy-two-hour exposure to 60 ng/ml IGF-I induced myocyte hypertrophy and increased the percentage of cells expressing only IKur and the cells expressing both Ito and IKur. In some cultured myocytes, immunofluorescent staining with a polyclonal antibody specific to the COOH terminus of Kv1.5 K(+)-channel protein was performed in the same single cells after voltage-clamp recordings. The IGF-I-pretreated cells expressing larger IKur revealed a significantly intense antibody labeling. These observations indicate that the long-term administration of IGF-I can regulate the K(+)-channel expression of cultured neonatal rat ventricular myocytes. This is important for understanding the role of IGF-I in the modulation of cardiac excitability.

4-Aminopyridine↗
PubMed1997

[The relationship between environmental concentration and exposure concentration in the airborne dust of workplace].

The authors studied the relationship between environmental concentration and exposure concentration in the airborne dust of workplaces, using instantaneous fixed points sampling and personal wear sampling. The results showed that there was a correlation between two kinds of concentrations in the automatic and man-made packing workplaces (r = 0.9914, 0.9977). A relationship between them in the unsteady workplace was found after analysed by one-accumulated generating operation (1-AGO) (r = 0.9945). The samples of environmental and exposure concentrations could be thought from the same normal distribution, that is, the bivariable random sampling in the normal distribution population. Moreover, the exposure concentration could be estimated by environmental one after 1-AGO in the unsteady workplace of airborne dust.

Air Pollutants, Occupational↗
PubMed1997

116 cases of coronary angina pectoris treated with powder composed of radix ginseng, radix notoginseng and succinum.

116 cases of coronary angina pectoris were treated with a powder composed of Radix Ginseng, Radix Notoginseng and Succinum, which was an empirical prescription of Dr. Yue Meizhong ([symbol: see text]), and compared with patients treated Fufang Danshen Tablet (a compound prescription of Radix Salviae Miltiorrhizae) as the control group. Results indicated that the curative effects and ECG in the treated group were better than that in the control group (P < 0.01), so were improvement of general symptoms, physical strength as well as changes of lipid metabolism and microcirculation of nail fold.

Adult↗
PubMed1997

[Ahmed valve implantation for refractory glaucoma].

OBJECTIVE: To evaluate the short-term and long-term efficacy of Ahmed valve implantation for refractory glaucoma and discuss its intraoperative and postoperative complications and management. METHODS: 20 cases of refractory glaucoma underwent Ahmed valve implantation, including 9 cases of neovascular glaucoma, 7 cases of aphakic or pseudophakic glaucoma, 3 cases of congenital glaucoma and one primary chronic angle-closure glaucoma. RESULTS: One month postoperatively, the intraocular pressure (IOP) was less than or equal to 2.8 kPa (1 kPa = 7.5 mmHg) in fifteen cases, with a total success rate of 75%. For cases with neovascular glaucoma, the success rate was 55.6%, while for the others, the rate was 90.9%. After six months of follow-up for 12 patients, the total success rate was 58.3%, for neovascular glaucomas and other glaucomas, the rate was 40.0% and 71.4%, respectively. The complications included transient hyphema, early postoperative hypotony, obstruction of the tube tip, tube touch to lens or cornea, tube exposure, exudative choroidal detachment and dropout of the plate. CONCLUSION: Ahmed valve implantation is an effective method in the management of refractory glaucoma in spite of its unnegligible complications.

Adult↗