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Biomedical subjects

C C Wu

Publications and source records attributed to C C Wu.

At least 199 records · Page 11Linked to original sources
PubMed1998

Nitric oxide-independent activation of soluble guanylyl cyclase contributes to endotoxin shock in rats.

We investigated whether a complete inhibition of nitric oxide (NO) formation caused by bacterial endotoxin (lipopolysaccharide, LPS) in vivo prevents the hypotension and restores the vascular hyporeactivity to normal in vivo and ex vivo. The combination of dexamethasone (Dex; 3 mg/kg at 30 min before LPS) plus aminoguanidine (AG; 15 mg/kg at 2 h after LPS) inhibited the overproduction of nitrate (an indicator of NO) in the plasma and aortic smooth muscle and also prevented the development of the delayed hypotension in rats treated with LPS for 6 h. However, the vascular hyporeactivity to norepinephrine (NE) was only partially improved either in vivo or ex vivo in endotoxemic rats treated with Dex plus AG. Pretreatment of aortic rings with Nomega-nitro-L-arginine methyl ester (L-NAME) or 1H-[1,2, 4]oxidazolo[4,3-a]quinoxalin-1-one (ODQ) enhanced the contraction to NE in rings obtained from LPS-treated rats, but not in those from Dex plus AG-treated endotoxemic rats. Methylene blue, an inhibitor of soluble guanylyl cyclase (GC), completely restored contractions to NE and aortic cGMP levels to normal either in LPS-treated rats or in Dex plus AG-treated endotoxemic rats, whereas the cGMP level was partially inhibited by ODQ in LPS-treated rats only. These results suggest that non-NO mediator(s) also activates soluble GC during endotoxemia. Interestingly, we found that in the presence of tetraethylammonium (an inhibitor of K+ channels) plus L-NAME or charybdotoxin [a specific inhibitor of large-conductance Ca2+-activated K+ (KCa) channels] plus ODQ, the vascular hyporeactivity to NE in the LPS-treated group was also completely restored to normal. In addition, in the presence of L-NAME or ODQ, the vascular hyporeactivity to high K+ was abolished in rings from the LPS-treated group. These results suggest that LPS causes the production of other mediator(s), in addition to NO, which also stimulates soluble GC (i.e., increases the formation of cGMP) and then activates the large-conductance KCa channels in the vascular smooth muscle causing vascular hyporeactivity.

Animals↗
PubMed1998

Assessment of the coronary artery disease and systolic dysfunction in hypertensive patients with the dobutamine-atropine stress echocardiography: effect of the left ventricular hypertrophy.

This study was performed to evaluate whether left ventricular hypertrophy (LVH) can influence the diagnostic accuracy of coronary artery disease (CAD) using the dobutamine stress echocardiography (DSE) in hypertensive patients. In addition to the detection of CAD, the relationship between systolic dysfunction and the quantitation wall motion scoring system of DSE was studied also. DSE was performed in 101 patients. There were 45 (45%) patients with a history of acute myocardial infarction. Twenty-eight patients (28%) had electrocardiographic LVH and 59 patients (58%) had echocardiographic LVH. A total of 74 patients (73%) had angiographically documented CAD defined as > or = 50% diameter stenosis. For the 56 patients without history of myocardial infarction, the diagnostic sensitivity, specificity, and accuracy in detecting CAD were not influenced by LVH defined by either electrocardiography or echocardiography. For the total patients, the diagnostic sensitivity, specificity, and accuracy in detecting multivessel disease were also not influenced by LVH defined by either method. The resting global wall motion score was correlated well with the left ventricular ejection fraction in patients with and without LVH (r = -0.70, p < 0.001 vs. r = -0.70, p < 0.001). When using the resting wall motion score of 24 as a cutoff value, the diagnostic sensitivity, specificity, and accuracy of systolic dysfunction (defined by left ventricular ejection fraction <40%) were 79, 86 and 85%, respectively. In conclusion, the diagnostic accuracy of CAD using the DSE was not affected by LVH in hypertensive patients. In addition to detection of coronary artery disease, the resting wall motion score of DSE was able to detect systolic dysfunction in patients with and without LVH.

Aged↗
PubMed1998

Comparison of S-T segment/heart rate slope with exercise thallium imaging and conventional S-T segment criteria in detecting coronary artery disease: effect of exercise level on accuracy.

The S-T segment/heart rate (ST/HR) slope has been proposed as a more accurate electrocardiographic criterion for the diagnosis of coronary artery disease, but studies comparing the diagnostic value of the ST/HR slope with exercise thallium imaging are scant. The aims of this study were to assess the diagnostic accuracy of the ST/HR slope, conventional S-T segment criteria and exercise thallium imaging in detecting coronary artery disease and to evaluate the effect of exercise level on the sensitivity and specificity of these three techniques. Ninety consecutive patients underwent treadmill testing and exercise thallium single-photon emission computed tomography (SPECT) simultaneously. All 90 patients also underwent coronary angiography within 1 month of the exercise test. We found that exercise thallium SPECT had a significantly higher diagnostic accuracy than either the ST/HT slope or conventional S-T segment criteria (thallium imaging 82%, ST/HR slope 67%, conventional S-T segment criteria 63%). The overall accuracy of the ST/HR slope was slightly but insignificantly greater than conventional S-T segment criteria (ST/HR slope 67%, conventional S-T segment criteria 63%; p = 0.639). In 50 patients with a lower exercise level, defined as not achieving 85% of their maximal predicted heart rate, the accuracy of the ST/HR slope was insignificantly greater (ST/HR slope 72%, conventional S-T segment criteria 66%; p = 0.517). In 40 patients with adequate exercise, the accuracy rate was the same (60%) for both the ST/HR slope and conventional S-T segment criteria. We conclude that exercise thallium imaging is more accurate than the ST/HR slope in diagnosing coronary artery disease and that the accuracy of the ST/HR slope is marginally better than conventional S-T segment criteria only in patients with a lower exercise level, and not in those with adequate exercise.

Cardiac Catheterization↗
PubMed1998

Bacterial corneal ulcer: a multivariate study.

A retrospective clinicomicrobiological review of 314 patients with bacterial corneal ulcers from January 1982 to December 1992 was performed. Multivariate statistical analysis was done with multiple logistic regression using PROC LOGIST of SAS statistical software. Positive cultures were grown from 134 (42.7%) of the patients. Pseudomonas aeruginosa, staphylococci, and Acinetobacter spp. were the most frequent pathogens. Significant associations between contact lens use and P. aeruginosa (odds ratio, OR 8.16), between previous herpes simplex keratitis and Streptococcus spp. (OR 18.2) were found. Acinetobacter spp. occurred more frequently in eyes with burn and/or lagophthalmos (OR 13.1/26.2). Staphylococcus aureus was associated with trauma (OR 6.27) and age under 50 (OR 5.08-13.6). Nonpseudomonal gram-negative bacilli were associated with age over 50 (OR 3.24). Drug sensitivity tests for these isolated microorganisms showed that vancomycin and ceftazidime were the most effective agents.

Adolescent↗
PubMed1998

Corynebacterial pneumonia in an African hedgehog.

A 3-mo-old, male African hedgehog (Atelerix albiventris) was anorectic and lethargic for a period of 3 days prior to death. Necropys revealed lungs that were diffusely firm, dark red, and dorsally adhered by fibrinous tags to the pericardial sac. Histopathology revealed necrosuppurative bronchopneumonia with pulmonary abscesses and suppurative pericarditis and myocarditis. A Corynebacterium sp. was isolated from the lungs. We believe this is the first reported case of corynebacterial pneumonia in an African hedgehog.

Animals↗
PubMed1998

Hepatic resection for bilobar multicentric hepatocellular carcinoma: is it justified?

BACKGROUND: Hepatic resection for multiple hepatocellular carcinomas (HCCs) involving both lobes of the liver is rarely recommended because of high operative risks and low radicality. Thus the justification of hepatic resection for bilobar multicentric HCC remains undefined. METHODS: Two hundred eleven patients with HCC, who underwent curative hepatic resection, were studied retrospectively. The patients were divided into two groups. Group A consisted of 39 patients with bilobar (both sides of Cantlie's line) multicentric HCCs. Group B consisted of 172 patients with HCC with solitary or unilobar lesions. The backgrounds and resectional results of patients in groups A and B were compared. RESULTS: Patients in group A usually required multiple separate liver resections and a longer operative time. However, the operative blood loss, amount of blood transfused, and operative morbidity and mortality rates were not significantly different. Patients in group A showed higher incidences of associated satellite nodules, microscopic vascular invasion, and a lack of capsules. The 6-year disease-free and actuarial survival rates of patients in groups A and B were 30.5% and 41.8% (p = 0.17) and 42.9% and 51.4% (p = 0.12), respectively. For patients in group A the presence of satellite nodules in any resected tumor was the only independent unfavorable feature that influenced the actuarial survival rate after multivariate analysis. CONCLUSIONS: Liver resection is justified for bilobar multicentric HCCs in selected patients, if the tumors can be totally resected. Postoperative adjuvant therapies should be considered when satellite nodules are present in any resected tumor.

Adult↗
PubMed1998

Combined effects of dexamethasone and aminoguanidine on rats with endotoxemia.

The effects of a combination of dexamethasone (DEX, an inhibitor of inducible nitric oxide synthase (iNOS) synthesis) and aminoguanidine (AG, an inhibitor of iNOS activity) on the anesthetized rat treated with endotoxin (lipopolysaccharide, LPS) were examined. In addition, we investigated whether a complete inhibition of nitric oxide (NO) formation caused by LPS prevents the hypotension, restores the vascular hyporeactivity to normal and improves the survival rate. The combination of DEX (3 mg/kg at 30 min prior to LPS) plus AG (15 mg/kg at 2 h after LPS) inhibited the overproduction of nitrate (an indicator of NO) and prevented the development of delayed hypotension, but further enhanced tachycardia in rats treated with LPS for 6 h. In addition, the vascular hyporeactivity to norepinephrine (NE) was, however, only partially restored in endotoxemic rats treated with DEX plus AG. During the experimental period, the survival rate of LPS-rats treated with DEX plus AG was also improved when compared to that of rats treated with LPS only. The beneficial effects of the combined therapy with DEX plus AG on rats with endotoxemia, suggesting that (i) combined treatment of animals with DEX plus AG may reduce some of the detrimental effects of LPS and (ii) NO only partially contributes to the vascular hyporeactivity in endotoxic shock.

Animals↗
PubMed1998

Beneficial effects of tetramethylpyrazine, an active constituent of Chinese herbs, on rats with endotoxemia.

Tetramethylpyrazine, an inhibitor of phosphodiesterase, has been widely used for treatment of cardiovascular diseases in China. Here, we investigate the effects of tetramethylpyrazine on hypotension, vascular hyporeactivity to norepinephrine (NE), release of tumor necrosis factor-alpha (TNF alpha) and nitric oxide (NO) in a rat model of circulatory shock induced by bacterial endotoxin (E. coli lipopolysaccharide, LPS). Male Wistar-Kyoto rats were anesthetized and instrumented for the measurement of mean arterial pressure (MAP) and heart rate (HR). Injection of LPS (10 mg/kg, i.v.) resulted in a fall in MAP and an increase of HR. In contrast, animals pretreated with tetramethylpyrazine (10 micrograms/kg, i.p. at 30 min prior to LPS) maintained a significantly higher MAP, but tachycardia was further enhanced at 60 min and 120 min when compared to rats given only LPS (LPS-rats). The pressor effect of NE (1 microgram/kg, i.v.) was also significantly reduced after treatment of rats with LPS. Similarly, the thoracic aorta obtained from rats after in vivo studies showed a significant reduction in the contractile responses elicited by NE (1 microM). Pretreatment of LPS-rats with tetramethylpyrazine partially, but significantly, prevented this LPS-induced hyporeactivity to NE in vivo and ex vivo. The injection of LPS resulted in a significant increase in the plasma TNF alpha level at 60 min, whereas the effect of LPS on the plasma nitrate (an indicator of NO formation) level increased in a time-dependent manner. This increment of both TNF alpha and nitrate levels induced by LPS was significantly reduced in LPS-rats pretreated with tetramethylpyrazine. The early hypotension caused by LPS was slightly, but significantly, prevented by pretreatment with tetramethylpyrazine, suggesting that tetramethylpyrazine affects the endothelial constitutive NOS (eNOS). This was examined by the effect of tetramethylpyrazine on acetylcholine (ACh, 1 microM)-induced relaxation in rats treated with tetramethylpyrazine for 4 h. However, tetramethylpyrazine had no significant effects on the ACh-induced relaxation, indicating that tetramethylpyrazine does not affect the activity of eNOS. Thus, tetramethylpyrazine attenuates the early hypotension and the delayed circulatory failure caused by endotoxin in the rat. These effects may be due to inhibition of the release of circulation factors and TNF alpha, which usually reveal synergism upon the induction of iNOS.

Animals↗
PubMed1998

Femoral interlocking nailing: a review of the experience at Chang Gung Memorial Hospital.

The invention of the interlocking nail has broadly extended the indications for reamed intramedullary nailing. It has even become the treatment of choice for most complex femoral shaft fractures. At Chang Gang Memorial Hospital, about 180 femoral cases have been treated with this technique each year since December 1986. With this accumulation of experience, both theoretical and clinical advancements are continuously developing and are regularly reported in the literature. In this article, experiences in the past few years with this technique are reviewed and evaluated. The author believes that to be a good trauma orthopedist, through training in femoral interlocking nailing, both theoretically and technically, is absolutely imperative. This device does, however, still have some disadvantages, but further improvements are anticipated with the advance of modern science.

Biomechanical Phenomena↗
PubMed1998

Cementless ceramic total hip arthroplasty: a 5 to 16 year follow-up.

BACKGROUND: Cementless total hip arthroplasty (THA) was invented to replace cemented THA and thus avoided cement disease, which shortened the longevity of implants. Ceramic THA was an early type of cementless THA which was used at our institution for several years. In the literature, reports about ceramic THA are very rare, moreover, the results of THA are controversial. This retrospective study was to report our experience. MATERIALS AND METHODS: Seventy-two cementless ceramic THAs were performed and followed for at least 5 years (range, 5 to 16 years; average, 9.8 years) at our institution. Patients ranged in age from 23 to 68 years (average, 45 years) with a male to female ratio of 3 to 1. A modified d'Aubigne and Postels' method was used to evaluate the functional and radiographic outcomes. RESULTS: Only 51.4% of the cases achieved a satisfactory result. Furthermore, the complication rate was very high, especially for aseptic loosening (34.7%). For ankylosing spondylitis cases, the satisfactory result rate was only 30% (2/7) and the unsatisfactory cases even had a loosening rate of 80% (4/5). CONCLUSION: Compared to other types of cementless THA, the satisfactory result rate with ceramic THA was markedly lower and the complication rate was relatively higher. Therefore, we conclude that cementless ceramic THA is not an ideal implant and its usage should be strictly restricted.

Adult↗
PubMed1998

Succinylcholine-induced cardiac arrest in unsuspected becker muscular dystrophy--a case report.

A five year-old boy undergoing elective tonsillectomy sustained cardiac arrest following the administration of a single dose of succinylcholine during induction of anesthesia. With a 10-minute cardiopulmonary resuscitation (CPR) during which intravenous calcium gluconate, epinephrine, and sodium bicarbonate were given and DC counter shock applied, we were successful to restore cardiac activity without neurological sequelae. The cause of cardiac arrest we speculated was hyperkalemia, possibly secondary to succinylcholine-induced rhabdomyolysis. It is suggested that succinylcholine should not be used in patients with known or suspected muscular dystrophy.

Child, Preschool↗
PubMed1997

Painless Prinzmetal's ST elevation related to propranolol: a case report.

Previous studies have shown that propranolol, an effective mainstay for angina pectoris and unstable angina, can induce coronary arterial spasm in patients with variant angina. However, no report has yet associated it with painless Prinzmetal's ST elevation in patients without a history of variant angina. The present communication describes such an unusual and negligible case after propranolol overdose. Coronary arterial spasm can be induced by beta-blocker, not only in patients with variant angina but also in normal persons.

Administration, Oral↗
PubMed1997

Myocardial contrast echocardiography can be used to quantify intramyocardial blood volume: new insights into structural mechanisms of coronary autoregulation.

BACKGROUND: Changes in intramyocardial blood volume (IBV) mediate autoregulatory adaptations to coronary stenosis. This study investigated whether (1) myocardial contrast echocardiography (MCE) can quantify changes in IBV during coronary stenosis and (2) the relation between coronary resistance- and MCE-derived IBV could yield insight into structural mechanisms of IBV change. METHODS AND RESULTS: A circulating in vitro model with constant flow and varying volume was used to determine whether indicator dilution theory could be applied to MCE. Contrast echo was performed with albumin microbubbles, and time-intensity data were fit to a gamma-variate function. With six different volumes, bubble transit time was linearly related to volume (r=.91). To determine whether changes in IBV could be quantified in vivo, the left anterior descending coronary artery in 12 dogs was instrumented with a flow probe, occluder, and intracoronary pressure catheter, and non-flow-limiting stenoses were created. IBV was derived by use of coronary resistance measurements applied to models that assumed autoregulation to occur via vasodilatation or microvascular recruitment. MCE-IBV was calculated from microbubble transit rates. At constant flow, MCE and resistance IBV increased with stenosis. Although MCE and resistance IBV were linearly related, MCE overestimated IBV derived from the vasodilatation model and underestimated IBV calculated from the recruitment model. CONCLUSIONS: MCE can quantify autoregulatory increases in IBV that maintain resting myocardial perfusion. These data suggest that both microvessel vasodilatation and recruitment are dual mechanisms of IBV change. MCE thus may be a clinically useful technique for the detection and quantification of coronary artery disease at rest.

Animals↗
PubMed1997

Functional development of the vibrissae somatosensory system of the rat: (14C) 2-deoxyglucose metabolic mapping study.

Functional development of the rat whisker somatosensory system was studied by using the (14C) 2-deoxyglucose (2DG) metabolic mapping technique. Restrained rat pups had their left mystacial vibrissae stroked for 30 minutes and their brains harvested, sectioned, and autoradiographed from the level of the lower medulla to the frontal cortex. Subjects were tested at postnatal days (PNDs) 0-9 and 21. At birth, all subjects exhibited a significant increase of 2DG uptake in the left spinal trigeminal nuclei, the principal trigeminal sensory nucleus, and a portion of the right ventral posteromedial thalamic nucleus. The primary somatosensory cortex exhibited significant 2DG uptake contralateral to stimulation by PND 6, followed by the secondary somatosensory cortex at PND 7. The pattern of 2DG uptake in the somatosensory cortices became more intense and well defined by PND 9. Given that the somatosensory system develops in an orderly fashion from the periphery to higher brain structures, the present results show that brain structures mediating whisker sensory input are not metabolically active until projections from lower somatosensory centers are established. Neurons become responsive to whisker stimulation in the subcortical structures at birth and in the somatosensory cortex a few days later. This cortical activity follows the organization of the upper tier of thalamocortical fibers into a "barrelfield." Moreover, there is a gradual enhancement in functional activity of the vibrissa neurons at different somatosensory nuclei as rats mature. The present study elucidates the time course of functional development in the rat somatosensory system.

Animals↗
PubMed1997

Beneficial effects of dantrolene on lipopolysaccharide-induced haemodynamic alterations in rats and mortality in mice.

We investigated the effect of dantrolene, an inhibitor of Ca2+ release from the sarcoplasmic reticulum, on the induction of nitric oxide (NO) synthase II by bacterial endotoxin (lipopolysaccharide) in the anaesthetised rat and on survival in a murine model of severe endotoxaemia. Injection of lipopolysaccharide (i) induced biphasic changes of rectal temperature and blood glucose: an initial increased phase (< 180 min after injection of lipopolysaccharide) followed by a decreased phase (at 240-360 min), (ii) caused a fall in mean arterial blood pressure from 115 +/- 3 mmHg (time 0) to 83 +/- 6 mmHg at 360 min, (iii) resulted in a substantial hyporeactivity to noradrenaline (1 microg/kg i.v.), (iv) raised plasma nitrate (an indicator of NO formation) in a time-dependent manner, (v) elicited a significant increase in NO synthase II activity in the lung and (vi) caused a 80% lethality (in mice). Pretreatment of animals with dantrolene not only attenuated the delayed circulatory failure, but also prevented the overproduction of NO and the induction of NO synthase II caused by lipopolysaccharide in the rat, and improved survival in a murine model of severe endotoxaemia. Thus, dantrolene has beneficial haemodynamic effects in animals with endotoxin shock. We propose that a decrease of free cytosolic Ca2+ levels plays an important role in the prevention of NO synthase II induction.

Animals↗
PubMed1997

Inhibition of platelet adhesion to collagen by cGMP-elevating agents.

In the present study, we examined the effects and action mechanisms of cGMP-elevating agents on platelet adhesion to collagen fiber. YC-1, a nitric oxide (NO)-independent activator of soluble guanylate cyclase, inhibited both initial and long-term platelet adhesion to collagen, and the inhibitory effect was potentiated by dipyridamole, a selective inhibitor of cGMP-specific phosphodiesterase. Sodium nitroprusside (SNP), a NO-donor, and 8-bromo-cGMP also inhibited the initial platelet adhesion, but inhibited long-term adhesion only in the presence of dipyridamole. Collagen-induced intracellular Ca2+ mobilization and actin polymerization were prevented by YC-1, SNP and 8-bromo-cGMP. Since blockade of Ca2+ mobilization and actin polymerization caused by collagen led to decrease of platelet adhesion, we suggest that the inhibitory activity of cGMP-elevating agents on the adhesion of platelets to collagen is resulting from interference of these signaling pathways.

Actins↗