Biomedical subjects

C H Wu

Publications and source records attributed to C H Wu.

At least 127 records · Page 7Linked to original sources

PubMed1999

Chronic levothyroxin treatment is associated with ion channel abnormalities in cardiac and neuronal cells.

1. We investigated the ion currents responsible for repolarization of guinea-pig isolated myocytes (ICa) and rat hippocampal CA1 neurons (IA and IK) by means of the whole-cell holding technique. 2. The rat hypertrophied heart, induced by levothyroxin, caused exaggerated cardiac arrhythmias after coronary ischaemia-reperfusion. 3. We found an enhanced ICa in guinea-pig isolated myocytes and decreased IA and IK in rat hippocampal CA1 neurons following levothyroxin treatment. Blockade of the outward K+ current and an increment in inward Ca2+ current by chronic levothyroxin treatment contributed to the delayed repolarization and aggravated cardiac arrhythmias. 4. Animals treated with chronic levothyroxin may serve as pathological models for the investigation of the pattern of ion channel disorders with regard to impaired repolarization and aggravated cardiac arrhythmias.

Animals↗

PubMed1999

Tone burst-evoked myogenic potentials in human neck flexor and extensor.

Vestibular evoked myogenic potential (VEMP) has been proposed to be a manifestation of sacculocollic reflex. In a recent study using intracellular recording from neck flexor and extensor motoneurons, the neuronal connections and pathways underlying sacculocollic reflexes were determined in cats. The results showed that sacculocollic reflex displayed inhibitory connection to bilateral neck flexors and excitatory connection to bilateral neck extensors. A total of 16 normal young adults were tested with bilateral recordings of sternocleidomastoid (SCM) and splenius capitis (SC) muscles by acoustic stimulus of 500 Hz short tone burst. The results revealed that polarity of the wave I/II of VEMP on SC was the reverse of that on SCM. This implied that VEMP from ipsilateral SCM showed inhibitory neural activity; whereas VEMP from ipsilateral SC was an excitatory response. Using this non-invasive technique, the sacculocollic reflexes in human neck flexor and extensor were studied. The results in humans were consistent with the previous findings in cats.

Acoustic Stimulation↗

PubMed1999

The effect of click repetition rate on vestibular evoked myogenic potential.

Vestibular evoked myogenic potentials (VEMPs) generated by click stimulation and recorded on the sternocleidomastoid muscle have been used as a test of vestibular reflexes. Various parameters of the stimulus and recording setting have been studied. However, the influence of stimulation repetition rate of VEMPs and the most optimal stimulation rate for clinical use have not yet been defined. Each ear of 12 normal adults was tested at five different click stimulation rates (1 Hz, 5 Hz, 10 Hz, 15 Hz and 20 Hz) in random order. VEMP responses were evident in all 24 ears stimulated with 1 Hz, 5 Hz and 10 Hz. One ear was void of response at 15 Hz stimulation and nine ears at 20 Hz stimulation. The relative amplitude or the rank of amplitude in individual ears was higher at 1 Hz and 5 Hz stimulation, progressively decreasing as the stimulation rate increased. Comparisons of p13 and n23 latencies showed no difference among five stimulation rates, but variance was greatest at 20 Hz stimulation and smallest at 1 Hz. VEMPs generated at lower stimulation repetition rate seemed to be more marked and constant. However, with regard to examination time and patient compliance, a 5 Hz stimulus is advisable if both short examination time and higher signal/noise ratio are required.

Acoustic Stimulation↗

PubMed1999

Calcitonin gene-related peptide acts as a mitogen for human Gin-1 gingival fibroblasts by activating the MAP kinase signalling pathway.

In many peripheral tissues, calcitonin gene-related peptide (CGRP) is released from peptidergic sensory nerve fibres and acts like a growth factor during tissue development and regeneration. However, the ability of CGRP to influence gingival tissue has not been studied. To address this question, we have now examined the effects of CGRP on the proliferation of human gingival fibroblasts (Gin-1) in vitro. Gin-1 cells have approximately 3100 specific CGRP-binding sites with a Kd of 38.6 pM on their surface. Treatment with CGRP (0.1-100 nM) significantly stimulated cell proliferation in a dose-dependent manner, with maximal effects at 1-10 nM CGRP after 2 d. As one early cellular response to CGRP, p44-MAPK protein (also known as the extracellular signal response kinase [ERK]) was tyrosine- and threonine-phosphorylated within 2 min, and this phosphorylation was sustained for at least 1 h. The dose-response curve of MAPK activation was very similar to that observed for CGRP's stimulation of cell proliferation. In addition, CGRP's activation of MAPK stimulated its ability to phosphorylate the Elk-1 transcription factor. When cells were pretreated with PD98059, a selective inhibitor of MAPK kinase (also known as MEK), CGRP not only failed to induce phosphorylation of MAPK but also failed to stimulate Gin-1 cell proliferation. Our present data indicate that CGRP rapidly activates the MAPK signalling pathway, an effect which consequently stimulates the proliferation of gingival fibroblasts. Our data demonstrate specific cellular responses to CGRP by gingival fibroblasts and support the possibility that CGRP acts as a targeted local factor in the regulation of development, generation and/or regeneration of gingival tissues.

Analysis of Variance↗

PubMed1999

Discriminating glucose tolerance status by regions of interest of dual-energy X-ray absorptiometry. Clinical implications of body fat distribution.

OBJECTIVE: To determine whether measuring body fat distribution by dual-energy X-ray absorptiometry (DEXA) can be used to discriminate glucose tolerance status. RESEARCH DESIGN AND METHODS: Using a 75-g oral glucose tolerance test, a total of 1,015 Chinese subjects (559 men and 456 women) were categorized as having normal glucose tolerance (NGT), impaired glucose tolerance (IGT), or diabetes. Blood pressure and lipid profiles of these subjects were measured. Waist-to-hip ratio (WHR) and DEXA were used to evaluate the varying patterns of body fat distribution among the groups. RESULTS: Body fat distribution, as reflected by WHR and the centrality index, showed significant partial correlation coefficients with glycosylated hemoglobin, blood pressure, and lipid profiles in all subjects. After adjusting for age and BMI, there were significant differences among the three glycemic groups for all the cardiovascular risk factors except for total cholesterol level. The diabetic group had a significantly higher WHR and centrality index, but lower femoral fat percentage than the NGT and IGT groups. The diabetic group also showed higher abdominal fat percentage than the NGT group. Moreover, the IGT group had a higher centrality index than the NGT group. However, no significant differences were found in the percentage of lean tissue mass among the three groups. Using multiple stepwise logistic regression models, the centrality index remained a significant factor for discriminating different glucose tolerance status independent of the percentage total body fat. CONCLUSIONS: Central obesity has shown significant correlation with cardiovascular risk factors among the three different glycemic groups. Centrality index measured by DEXA appears to be the better predictor of glucose intolerance, compared with WHR, abdominal fat, and general obesity (reflected by percentage total body fat or BMI) in a large cohort of the Chinese population.

Absorptiometry, Photon↗

PubMed1999

A mullerian duct remnant myoma misdiagnosed as ovarian cancer in a woman with vaginal agenesis--a case report.

Leiomyoma are very common in the normal uterus; however, they are rather rare in mullerian duct remnant. We report a case of mullerian duct remnant leiomyoma associated with vaginal agenesis. The mass had papillary growth with cystic-solid components by ultrasound. Ovarian cancer was suspected preoperatively. Finally, a fibroid with hyalinization and chondroid metaplasia was diagnosed histopathologically. To the best of our knowledge, this is the first case of mullerian duct remnant leiomyoma with degeneration, mimicking ovarian cancer by ultrasound. We provide the clinical details of this case and discuss a diagnostic pitfall.

Adult↗

PubMed1999

Suppression of tumorigenicity in cervical carcinoma HeLa cells by an episomal form of adeno-associated virus.

To compare the oncosuppressive activity of integrated and episomal adeno-associated virus (AAV), two Epstein-Barr virus (EBV) derived episomal form vectors, p205 and p220, were used to generate plasmids containing episomal AAV. HeLa cells transfected with p205, p220, and the plasmids with forward (pA205-1, pA220-1) and reverse (pA205-1, pA220-2) orientation of inserted AAV DNA were designated H205, H220, HA205-1, HA220-1, HA205-1, and Ha220-2, respectively. The respective average copy numbers of pA205 and pA220 per cell are 4.9-6.9 and 4.3. The AAV-transfected HeLa cells displayed growth inhibition when compared to parental and the vector-transfected HeLa cells. Nude mice assay showed that the tumor size from HA205-1 and HA205-2 cells were 11.3 and 22.6%, and those from HA220-1 and HA220-2 cells were 54.8 and 57.3%, respectively, when compared to parental HeLa cells. HA205-1 cells containing forward AAV insert exerted more oncosuppressive effect than HA205-2 cells containing reverse AAV insert. Our data indicate that the episomal AAV can exert oncosuppressive activity as compared to the integrated AAV in HeLa cells.

Animals↗

PubMed1999

Endoscopic ultrasonography in the differential diagnosis of giant gastric folds.

Giant gastric folds (or large gastric folds) are found in both benign and malignant diseases, and differential diagnosis with either upper gastrointestinal X-ray or endoscopy is difficult. Sometimes, even endoscopic biopsy cannot establish a definitive diagnosis. Recently, endoscopic ultrasonography (EUS) has been used to study giant gastric folds. We performed EUS in 25 patients with giant gastric folds that had been detected with upper gastrointestinal X-ray or endoscopy. The definitive diagnoses were confirmed by histopathology, other examinations, or long-term follow-up. The final diagnoses of these 25 patients were gastric varices in eight, gastric lymphangiectasis in one, gastritis in four, gastric carcinoma (scirrhous type) in six, and gastric lymphomas in six. All patients with gastric varices had anechoic tortuous varicose veins in the submucosal layer. EUS images of gastric lymphangiectasis were similar to those of gastric varices. EUS revealed regular gastric wall thickening of the second (mucosa) and third (submucosa) layers in all cases of gastritis. The fourth (muscularis propria) layer was intact in the only case of mucosa-associated lymphoid tissue lymphoma (MALToma), but not in the other five cases of gastric lymphoma. The second and third layers of this MALToma were irregular in thickness and heterogenous in echogenicity, different from the characteristic EUS findings in gastritis. The fourth layer was markedly thickened only in malignant conditions. Differentiation of gastric cancer from lymphoma with EUS was difficult because of overlapping EUS findings. In conclusion, EUS is indicated for the differential diagnosis of giant gastric folds. In addition, it avoids the risk associated with biopsy of gastric varices.

Adult↗

PubMed1999

Pre-dialysis glycemic control is an independent predictor of mortality in type II diabetic patients on continuous ambulatory peritoneal dialysis.

OBJECTIVE: To evaluate the impact of pre-dialysis glycemic control on clinical outcomes for type II diabetic patients on continuous ambulatory peritoneal dialysis (CAPD). MATERIALS AND METHODS: One hundred and one type II diabetic patients receiving CAPD for at least 3 months were enrolled in a single institute. The patients were classified into two groups according to status of glycemic control. In the good glycemic control group, more than 50% of blood glucose determinations were within 3.3-11.0 mmol/L and glycosylated hemoglobin (HbA1C) levels were within 5%-10% at all times. In the poor glycemic control group, less than 50% of blood glucose determinations were within 3.3-11.0 mmol/L, or HbA1C levels were above 10% at least 6 months before peritoneal dialysis was started. In addition to glycemic control status, pre-dialysis serum albumin, cholesterol levels, residual renal function, peritoneal membrane function, and modes of glycemic control were also recorded. RESULTS: The patients with good glycemic control had significantly better survival than those with poor glycemic control (p < 0.01). There was no significant difference in pre-dialysis morbidity between two groups. No significant differences were observed in patient survival between patients with serum albumin above 30 g/L and those with serum albumin under 30 g/L; between those with cholesterol levels above or below 5.2 mmol/L; and between those with different peritoneal membrane solute transport characteristics as evaluated by a peritoneal equilibration test (PET). Furthermore, there was no significant difference in survival between patients who controlled blood sugar by diet and those who controlled it by insulin. Cardiovascular disease and infection are the major causes of death in both groups. Although good glycemic control predicts better survival, it does not change the pattern of mortality in diabetic patients maintained on CAPD. CONCLUSIONS: Glycemic control before starting dialysis is a predictor of survival for type II diabetic patients on CAPD. Patients with poor glycemic control predialysis are associated with increased morbidity and shortened survival.

Blood Glucose↗

PubMed1999

Surgical treatment of morbid obesity with vertical banded gastroplasty: a comparison between TA90-4.8 and TA90-B.

BACKGROUND: In this study, we wanted to determine the results of vertical banded gastroplasty for morbid obesity and compare the results of using the TA90-4.8 with using the TA90-B instrument. METHODS: Patients with body weight over 100% of or 45 kg above their ideal body weight, body mass index (BMI) over 40 kg/m2, or BMI over 35 kg/m2 with osteoarthritis, venous stasis, sleep apnoea, or frequent abortion were selected for surgical intervention. They were purposely divided into two groups. Vertical banded gastroplasty was performed in group A with two applications of TA90-4.8 (N = 26) and in group B with one application of TA90-B (N = 24). The outlet of the gastric pouch was 10 to 12 mm and reinforced with a 1.5 cm strip of Marlex to give a circumference of 5.5 cm. The follow-up body weight, BMI, and percentage of weight in excess of the ideal weight were compared between the two groups. The results were classified as excellent (0 to 25% excess weight), fair (26 to 50% excess weight), good (51 to 75% excess weight), poor (76 to 100% excess weight), and worse (> 100% excess weight). A failure was defined as a body weight of greater than 76% excess weight and a repeated operation being needed regardless of the ultimate outcome. RESULTS: There were no differences between the two groups regarding age, gender, preoperative body weight, BMI, and excess weight. The operative time was longer for group A (175 +/- 39 min) than for of group B (140 +/- 23 min) (p < 0.0001). In the follow-up period, the postoperative body weight, BMI, and excess weight showed no differences between the two groups. Four patients in group A had poor results, three due to staple disruption and one due to sweet-eating. One patient in group B had stenosis of the stomach pouch and needed another operation to release the stenosis. Thus, five failures (10%) were found in this study. CONCLUSION: Vertical banded gastroplasty is an effective modality for treating morbid obesity. Two applications of TA90-4.8 are not recommended because they result in frequent staple disruption.

Adult↗

PubMed1999

Correlation of arterial and end-tidal carbon dioxide in spontaneously breathing patients during ambulatory gynecologic laparoscopy.

Laparoscopy can be performed while patients are under total intravenous anesthesia (TIVA), or sedated and breathing spontaneously through the normal airway. Respiratory monitoring is difficult when patients are sedated or anesthetized, however. The purposes of this study were to evaluate the reliability of end-tidal carbon dioxide (ETCO2) measurement for monitoring arterial carbon dioxide pressure (PaCO2), and to assess the PaCO2/ETCO2 gradient among patients receiving TIVA while breathing spontaneously through the normal airway. Sixty patients were divided into two groups: group 1 patients (n = 30) received general anesthesia with controlled ventilation, while group 2 patients (n = 30) received TIVA with spontaneous breathing through the normal airway; ETCO2 was sampled through a 10-French suction catheter inserted into the nasopharynx via the nasal airway. Arterial blood gas and ETCO2 were recorded at the time of preinduction, induction, CO2 insufflation, and change to Trendelenburg tilt position (20 degrees-30 degrees), and at 10-minute intervals thereafter. The results showed that ETCO2 was highly correlated with PaCO2 in group 1 (correlation coefficient r = 0.85), but not in group 2 (r = 0.55). In group 2, the PaCO2/ETCO2 gradient increased as time elapsed, with significant differences (p < 0.05) between the values at induction and those at 30 minutes after the change to the Trendelenburg position and thereafter. These results indicate that the ETCO2 and PaCO2 values correlate well during the first 20 minutes after the change to the Trendelenburg position in laparoscopy patients receiving TIVA with spontaneous breathing, but that PaCO2 monitoring is still necessary.

Adult↗

PubMed1999

Bepridil inhibition of sodium current in rat hippocampal CA1 neurons.

AIM: To study the effects of bepridil on sodium current in rat hippocampal neurons. METHODS: All experiments were performed on acutely isolated hippocampal pyramidal neurons by means of whole-cell patch-clamp techniques. Recording media contained ion channel blockers to allow the selective activation of voltage-dependent sodium currents. RESULTS: Bepridil reduced the amplitudes of sodium current in time- and concentration-dependent manners. The half-blocking time was about 10 min in bepridil 10 micromol.L-1, and IC50 was 2.6 (2.3-2.9) micromol.L-1. Bepridil 10 micromol.L-1 shifted the maximal activation of sodium current from -50 mV to -40 mV, and the characteristic voltage of inactivation from -71 mV to -89 mV without changing the slope factor. CONCLUSION: Bepridil blocked voltage-dependent sodium current of hippocampal CA1 neurons and might have therapeutic actions for ischemia-induced brain damage.

Animals↗

PubMed1999

[Effects of glutamate on transient outward potassium current of dissociated hippocampal neurons in ca1 sector in rats].

The effects of glutamate on the transient outward potassium current of dissociated hippocampal CA(1) neurons of 7-10 d rats were studied by the whole-cell patch clamp technique. It was found that glutamate could block the transient potassium current in a dose- and time-dependent manner. The effect was partly voltage-dependent. These results suggest that glutamate may decrease the membrane conductance of K(+) channels in hippocampal neurons.

Animals↗

PubMed1998

Identification and subcellular localization of a novel Cu,Zn superoxide dismutase of Mycobacterium tuberculosis.

Periplasmic copper, zinc superoxide dismutases (Cu,ZnSOD) of several Gram-negative pathogens have been shown to play an important role in protection against exogenous superoxide radicals and in determining virulence of the pathogens. Here we report the cloning and characterization of the sodC gene, encoding Cu,ZnSOD, from the Gram-positive Mycobacterium tuberculosis. The predicted protein sequence contains 240 amino acids with a putative signal peptide at the N-terminus and shows approximately 25% identity to other bacterial sodC. Recombinant proteins of a full-length sodC and a truncated form lacking the putative signal peptide were overexpressed in Escherichia coli and affinity purified. Renatured recombinant M. tuberculosis sodC protein possessed characteristics of a Cu,ZnSOD. Immunoblotting with an antiserum against the recombinant M. tuberculosis Cu,ZnSOD allowed detection of a single polypeptide in the lysate of M. tuberculosis. This polypeptide has a similar size as the recombinant protein without the putative signal peptide indicating that the endogenous Cu,ZnSOD in M. tuberculosis might be processed and secreted. Furthermore, immunogold electron microscopic image showed that Cu,ZnSOD is located in the periphery of M. tuberculosis. The enzymatic activity and subcellular localization of this novel Cu,ZnSOD suggest that it may play a role in determining virulence of M. tuberculosis.

Amino Acid Sequence↗

PubMed1998

Synthesis and cytotoxicity of 2-acetyl-4,8-dihydrobenzodithiophene-4, 8-dione derivatives.

2-Acetyl-4,8-dihydrobenzo[1,2-b:4,5-b']dithiophene-4,8-dione (9) and 2-acetyl-4,8-dihydrobenzo[1,2-b:5,4-b']dithiophene-4,8-dione (19), together with 10 related mono- and disubstituted derivatives, were synthesized and evaluated in vitro by NCI against eight cancer types. All compounds showed significant activity against melanoma, HL-60 leukemia, NCI-H23 non-small-cell lung cancer, OVCAR-3 ovarian cancer, and MDA-MB-435 and MDA-N breast cancer cell lines. Compound 11, 2-(1'-acetoxyethyl)-4,8-dihydrobenzo[1,2-b:4,5-b']dithiophene-4, 8-dione, showed the highest overall potency (mean GI50 = 40 nM).

Animals↗

PubMed1998

Vascular pathology of malignant cervical lymphadenopathy: qualitative and quantitative assessment with power Doppler ultrasound.

BACKGROUND: Malignant vascular pathology has traditionally been studied with invasive angiography or in vitro immunohistochemistry. The objective of this study was to investigate the vascular patterns and vascular density of benign and malignant cervical lymphadenopathy using power Doppler ultrasound combined with a computed quantitative image processing system. METHODS: Investigations of 189 cervical lymph node lesions were undertaken prospectively using a 5-10 MHz linear array transducer in power mode. The types of vascular patterns displayed with power Doppler ultrasound, after sweep-scanning over the whole lymph node, were classified as hilar, spotted, peripheral, or mixed. Quantitative assessment of vascularity was made by sampling three parallel planes of each lymph node. A computed image processing system automatically calculated the density of vascular signals (called the "vascularity index" in this study) within the lymph node plane. RESULTS: Malignant lymph node lesions were shown to have higher vascularity indices (0.169+/-0.147, P < 0.01). The vascular patterns of benign lesions were mostly of avascular or hilar type (in 83% of cases). Malignant lesions were characterized by patterns of mixed (47%), spotted (20%), or peripheral type (11%). When vascular pattern (nonhilar type) and vascularity index (maximum > or = 0.09) were combined, the specificity for diagnosing malignant lymphadenopathy was as high as 97%. Variance in tumor vascularity was noted in both the benign and malignant groups. CONCLUSIONS: Power Doppler ultrasound combined with a computed image processing system provided an objective tool for assessing tumor vascularity quantitatively. Using this modality, the vascular pathology of malignant lymphadenopathy was found to be characterized by higher vascular density and aberrant vascular patterns.

Adolescent↗

PubMed1998

2-Phenyl-4-quinolone prevents serotonin-induced increases in endothelial permeability to albumin.

To investigate the role of 2-phenyl-4-quinolone in enhancing endothelial monolayer paracellular barrier function and preventing the disturbance of paracellular barrier function by vasoactive agents, the study examined the effect of 2-phenyl-4-quinolone on serotonin-mediated macromolecule transfer and microfilament changes in cultured rat heart endothelial cells. Serotonin-treated endothelial cells induced concentration-dependent increases in the passage of Evans blue dye-bound bovine serum albumin. Incubation of the endothelial monolayers with 2-phenyl-4-quinolone antagonized serotonin- and cytochalasin B-induced macromolecular permeability. 2-Phenyl-4-quinolone also opposed the effect of serotonin or cytochalasin B on the distribution and quantity of actin filaments in the endothelial cytoskeleton. Furthermore, 2-phenyl-4-quinolone alone led to an apparent quantitative increase in F actin fluorescence in endothelial cells. The addition of 10(-7) M 2-phenyl-4-quinolone had an effect on serotonin-induced changes in the myosin and distribution of myosin were comparable to that on serotonin monolayers. In conclusion, 2-phenyl-4-quinolone attenuated the serotonin-induced permeability of rat heart endothelial cells and this was associated with stabilization of F actin microfilaments and changes in the myosin organization. This result suggests that influences on cytoskeletal assembly may be involved in this process.

Actin Cytoskeleton↗

PubMed1998

Decreased protein kinase C activation mediates inhibitory effect of norathyriol on serotonin-mediated endothelial permeability.

We examined the mechanisms of norathyriol on the serotonin-induced increased permeability of rat heart endothelial cell monolayers. The present study showed that the activation of rat heart endothelial cell protein kinase C by phorbol myristate acetate led to the dose-dependent increase in endothelial permeability to albumin, an effect that was inhibited by staurosporine (a protein kinase inhibitor). Staurosporine also attenuated the serotonin-induced increase in permeability. Norathyriol abolished both serotonin- and phorbol myristate acetate-induced permeability. We investigated whether norathyriol, by inhibiting protein kinase C activation, attenuated the serotonin-induced permeability. Immunofluorescence studies demonstrated that norathyriol prevented the redistribution of protein kinase C isozymes following stimulation with serotonin. Western blot analysis showed that norathyriol significantly inhibited the serotonin-induced translocation of the alpha protein kinase C isozyme from the cytosolic to the particulate fraction. In conclusion, norathyriol attenuates the serotonin-induced permeability of rat heart endothelial cells to macromolecules in association with inhibition of protein kinase C activation. This decrease in endothelial cell permeability may be one of the mechanisms for the protective effects of norathyriol against edema formation in response to inflammatory agonists in vivo.

Animals↗