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Biomedical subjects

Y C Liu

Publications and source records attributed to Y C Liu.

At least 127 records · Page 7Linked to original sources
PubMed1998

Coordinated regulation of the tyrosine phosphorylation of Cbl by Fyn and Syk tyrosine kinases.

Cross-linking of the T cell antigen receptor (TCR)-CD3 complex induces rapid tyrosine phosphorylation and activation of Src (Lck and Fyn) and Syk (Syk and Zap-70) family protein tyrosine kinases (PTKs) which, in turn, phosphorylate multiple intracellular substrates. Cbl is a prominent PTK substrate suggesting a pivotal role for it in early signal transduction events. However, the regulation of Cbl function and tyrosine phosphorylation in T cells by upstream PTKs remains poorly understood. In the present study, we used genetic and biochemical approaches to demonstrate that Cbl directly interacts with Syk and Fyn via its N-terminal and C-terminal regions, respectively. Tyr-316 of Syk was required for the interaction with Cbl as well as for the maximal tyrosine phosphorylation of Cbl. However, both wild-type Syk and Y316F-mutated Syk phosphorylated equally well the C-terminal fragment of Cbl in vivo, suggesting the existence of an alternative, N terminus-independent mechanism for the Syk-induced tyrosine phosphorylation of Cbl. This mechanism appears to involve Fyn, since, in addition to its association with the C-terminal region of Cbl, Fyn also associated with Syk and enhanced the Syk-induced tyrosine phosphorylation of Cbl. These findings implicate Fyn as an adaptor protein that facilitates the interaction between Syk and Cbl, and suggest that Src and Syk family PTKs coordinately regulate the tyrosine phosphorylation of Cbl.

Cloning, Molecular↗
PubMed1998

Sexual behavior in male rats after radiofrequency or dopamine-depleting lesions in nucleus accumbens.

Considerable neurochemical evidence links dopamine (DA) in nucleus accumbens (NAcc) to male sexual behavior. The present experiments were conducted to extend this information to the male's sexual response to remote stimuli from estrous female (noncontact erection; NCE). Male rats were tested for copulation and NCE after either 6-hydroxydopamine (6-OHDA) or radiofrequency (RF) lesions in NAcc). Males with an average 78% depletion of DA in NAcc had a lower incidence of NCE, longer latency to display NCE, and fewer erections. DA-depleted males also had less locomotor activity after injections of d-amphetamine, and reductions in apomorphine-induced yawning, but a normal incidence of penile erection. Males with RF lesions of the NAcc had longer NCE latencies. All males copulated to ejaculation after either 6-OHDA or RF lesions with little or no deficit, although the 6-OHDA-treated males had longer intromission latencies. The NCE deficit supports the hypothesized role of NAcc DA in arousal processes in responding to remote cues from estrous females. The minimal effect of lesions on copulation suggests that the presence of additional proximal stimulation during copulation may overcome the deficits induced by DA depletions or lesions in NAcc.

Animals↗
PubMed1998

Cbl: complex formation and functional implications.

Chbl, a 120-kDa proto-oncogene product, whose gene was first identified as part of a transforming gene of a murine retrovirus and whose expression is predominant in haematopoietic cells, consists of an amino-terminal transforming region, a zinc Ring finger, multiple proline-rich stretches, and several potential phosphotyrosine-containing motifs. Cbl is rapidly tyrosine-phosphorylated in response to stimulation of a variety of cell-surface receptors and becomes associated with a number of intracellular signalling molecules such as protein tyrosine kinases, phosphatidylinositol 3-kinase, Crk, and 14-3-3 proteins through different protein-interacting modules, leading to the formation of multimolecular signalling complexes. Cbl and its transforming mutants have been shown to display both negative and positive regulatory activities in protein tyrosine kinase- and Ras-mediated signalling pathways. Nevertheless, the exact biological function of this adaptor protein remains largely unknown. The present review summarizes recent progress in our understanding of the structure, regulation and biological function of Chl and defines open questions for future research.

Animals↗
PubMed1998

Neuroregulation of mucus secretion by opioid receptors and K(ATP) and BK(Ca) channels in ferret trachea in vitro.

1. Opioid agonists inhibit neurogenic mucus secretion in the airways. The mechanism of the inhibition is unknown but may be via opening of potassium (K+) channels. We studied the effect on neurogenic secretion in ferret trachea in vitro of the OP1 receptor (formerly known as delta opioid receptor) agonist [D-Pen2,5]enkephalin (DPDPE), the OP2 receptor (formely kappa) agonist U-50,488H, the OP3 receptor (formerly micro) agonist [D-Ala2, N-Me-Phe, Gly-ol5]enkephalin (DAMGO), the ATP-sensitive K+ (K(ATP)) channel inhibitor glibenclamide, the large conductance calcium activated K+ (BK(Ca)) channel blocker iberiotoxin, the small conductance K(Ca) (SK(Ca)) channel blocker apamin, the K(ATP) channel opener levcromakalim, a putative K(ATP) channel opener RS 91309, and the BK(Ca) channel opener NS 1619. Secretion was quantified by use of 35SO4 as a mucus marker. 2. Electrical stimulation increased tracheal secretion by up to 40 fold above sham-stimulated levels. DAMGO or DPDPE (10 microm each) significantly inhibited neurogenic secretion by 85% and 77%, respectively, effects which were reversed by naloxone. U-50,488H had no significant inhibitory effect on neurogenic secretion, and none of the opioids had any effect on ACh-induced or [Sar9]substance P-induced secretion. 3. Inhibition of neurogenic secretion by DAMGO or DPDPE was reversed by iberiotoxin (3 microM) but not by either glibenclamide or apamin (0.1 microM each). Iberiotoxin alone did not affect the neurogenic secretory response. 4. Levcromakalim, RS 91309 or NS 1619 (3 nM-3 microM) inhibited neurogenic secretion with maximal inhibitions at 3 microM of 68%, 72% and 96%, respectively. Neither levcromakalim nor RS 91309 at any concentration tested significantly inhibited acetylcholine (ACh)-induced secretion, whereas inhibition (60%) was achieved at the highest concentration of NS 1619, a response which was blocked by iberiotoxin. 5. Inhibition of neurogenic secretion by levcromakalim (3 microM) or RS 91309 (30 nM) was inhibited by glibenclamide but not by iberiotoxin. In contrast, inhibition by NS 1619 (30 nM and 3 microM) was blocked by iberiotoxin but not by glibenclamide. 6. We conclude that, in ferret trachea in vitro, OP1 or OP3 opioid receptors inhibit neurogenic mucus secretion at a prejunctional site and that the mechanism of the inhibition is via opening of BK(Ca) channels. Direct opening of BK(Ca) channels or K(ATP) channels also inhibits neurogenic mucus secretion. In addition, opening of BK(Ca) channels inhibits ACh-evoked secretion of mucus. Drugs which open BK(Ca) channels may have therapeutic anti-secretory activity in bronchial diseases in which neurogenic mechanisms and mucus hypersecretion are implicated in pathophysiology, for example asthma and chronic bronchitis.

Adenosine Triphosphate↗
PubMed1998

Effects of the cysteinyl leukotriene receptor antagonists pranlukast and zafirlukast on tracheal mucus secretion in ovalbumin-sensitized guinea-pigs in vitro.

1. We investigated the inhibitory effects of the cysteinyl leukotriene (CysLT1) receptor antagonists, pranlukast and zafirlukast, on 35SO4 labelled mucus output, in vitro, in guinea-pig trachea, induced by leukotriene D4 (LTD4) or by antigen challenge of sensitized animals. Agonists and antagonists were administered mucosally, except in selected comparative experiments where drugs were administered both mucosally and serosally to assess the influence of the epithelium on evoked-secretion. 2. LTD4 increased 35SO4 output in a concentration-related manner with a maximal increase of 23 fold above controls at 100 microM and an approximate EC50 of 2 microM. Combined mucosal and serosal addition of LTD4 did not significantly affect the secretory response compared with mucosal addition alone. Neither LTC4 nor LTE4 (10 microM each) affected 35SO4 output. Pranlukast or zafirlukast significantly inhibited 10 microM LTD4-evoked 35SO4 output in a concentration-dependent fashion, with maximal inhibitions of 83% at 10 microM pranlukast and 78% at 10 microM zafirlukast, and IC50 values of 0.3 microM for pranlukast and 0.6 microM for zafirlukast. Combined mucosal and serosal administration of the antagonists (5 microM each) gave degrees of inhibition of mucosal-serosal 10 microM LTD4-evoked 35SO4 output similar to those of the drugs given mucosally. Pranlukast (0.5 microM) caused a parallel rightward shift of the LTD4 concentration-response curve with a pKB of 7. Pranlukast did not inhibit ATP-induced 35SO4 output. 3. Ovalbumin (10-500 microg ml(-1) challenge of tracheae from guinea-pigs actively sensitized with ovalbumin caused a concentration-related increase in 35SO4 output with a maximal increase of 20 fold above vehicle controls at 200 microg ml(-1). The combination of the antihistamines pyrilamine and cimetidine (0.1 mM each) did not inhibit ovalbumin-induced 35SO4 output in sensitized guinea-pigs. Neither mucosal (10 microM or 100 microM) nor mucosal-serosal (100 microM) histamine had any significant effect on 35SO4 output. 4. Pranlukast or zafirlukast (5 microM each) significantly suppressed ovalbumin-induced secretion in tracheae from sensitized guinea-pigs by 70% and 65%, respectively. 5 We conclude that LTD4 or ovalbumin challenge of sensitized animals provokes mucus secretion from guinea-pig trachea in vitro and this effect is inhibited by the CysLT1 receptor antagonists pranlukast and zafirlukast. These antagonists may be beneficial in the treatment of allergic airway diseases in which mucus hypersecretion is a clinical symptom, for example asthma and allergic rhinitis.

Adenosine Triphosphate↗
PubMed1998

Primary liver abscess due to Klebsiella pneumoniae in Taiwan.

Pyogenic liver abscess is an uncommon complication of intra-abdominal or biliary tract infection and is usually a polymicrobial infection associated with high mortality and high rates of relapse. However, over the past 15 years, we have observed a new clinical syndrome in Taiwan: liver abscesses caused by a single microorganism, Klebsiella pneumoniae. We reviewed 182 cases of pyogenic liver abscess during the period September 1990 to June 1996; 160 of these cases were caused by K. pneumoniae alone, and 22 were polymicrobial. When patients with K. pneumoniae liver abscess were compared with those who had polymicrobial liver abscess, we found higher incidences of diabetes or glucose intolerance (75% vs. 4.5%) and metastatic infections (11.9% vs. 0) and lower rates of intra-abdominal abnormalities (0.6% vs. 95.5%), mortality (11.3% vs. 41%), and relapse (4.4% vs. 41%) in the former group. Liver abscess caused by K. pneumoniae is a new clinical syndrome that has emerged as an important infectious complication in diabetic patients in Taiwan.

Female↗
PubMed1998

Adding ketamine in a multimodal patient-controlled epidural regimen reduces postoperative pain and analgesic consumption.

UNLABELLED: We designed this double-blind study to evaluate the effect of adding small-dose ketamine in a multimodal regimen of postoperative patient-controlled epidural analgesia (PCEA). Ninety-one patients, ASA physical status I-III, undergoing major surgery, received a standardized general anesthesia and epidural catheterization in an appropriate intervertebral space after surgery. A PCEA device was programmed to deliver a regimen of morphine 0.02 mg/mL, bupivacaine 0.8 mg/mL, and epinephrine 4 microg/mL, with the addition of ketamine 0.4 mg/mL (ketamine, n = 45) or without (control, n = 46). The mean visual analog pain scale (VAS) scores during cough or movement for the first 3 days after surgery were higher in the control group than in the ketamine group (P < 0.05), whereas the mean VAS score at rest for the first 2 days were higher in the control group than in the ketamine group (P < 0.05). Furthermore, patients in the control group consumed more multimodal analgesics than patients in the ketamine group for the first 2 days (P < 0.05). The sedation scores and the incidence of side effects (pruritus, nausea, emesis, sleep deprivation, motor block, and respiration depression) were similar between the two groups. We conclude that adding ketamine 0.4 mg/mL in a multimodal PCEA regimen provides better postoperative pain relief and decreases consumption of analgesics. IMPLICATIONS: Many studies have evaluated one or a combination of two analgesics for postoperative pain control, but few have examined a multimodal approach using three or four different epidural analgesics. This study demonstrates an additive analgesic effect when ketamine is added to a multimodal analgesic treatment.

Analgesia, Epidural↗
PubMed1998

Extremely high prevalence of nasopharyngeal carriage of penicillin-resistant Streptococcus pneumoniae among children in Kaohsiung, Taiwan.

Resistance (intermediate and high) to penicillin among Streptococcus pneumoniae strains is an emerging problem worldwide. From 1995 to 1997, isolates of S. pneumoniae not susceptible to penicillin were seen with increasing frequency from blood, cerebrospinal fluid, pleural fluid, and middle ear fluid from pediatric patients at the Veterans General Hospital-Kaohsiung. To determine the prevalence of carriage of these penicillin-nonsusceptible S. pneumoniae isolates, we obtained nasopharyngeal swab specimens from 2,905 children (ages, 2 months to 7 years) attending day-care centers or kindergartens or seen in our outpatient clinic. S. pneumoniae was isolated from 611 children, and 584 strains were available for analysis. The oxacillin disc test was used as a screening test to evaluate penicillin susceptibility. The MICs of 11 antibiotics (penicillin, cefaclor, cefuroxime, ceftriaxone, cefotaxime, imipenem, chloramphenicol, clarithromycin, rifampin, vancomycin, and teicoplanin) were determined by the E-test. Only 169 (29%) of the strains were susceptible to penicillin; 175 (30%) strains were intermediately resistant and 240 (41%) were highly resistant. The isolates also demonstrated high rates of resistance to other beta-lactams (46% were resistant to cefaclor, 45% were resistant to cefuroxime, 45% were resistant to ceftriaxone, 31% were resistant to cefotaxime, and 46% were resistant to imipenem). The rate of resistance to macrolide antimicrobial agents was strikingly high; 95% of the isolates were not susceptible to clarithromycin. However, 97% were susceptible to rifampin and 100% were susceptible to the two glycopeptides (vancomycin and teicoplanin). While reports of penicillin-resistant S. pneumoniae increased worldwide through the 1980s, the high prevalence (71%) of resistance reported here is astonishing. Surveillance of nasopharyngeal swab specimen cultures may provide useful information on the prevalence of nonsusceptible strains causing invasive disease. Such information could be used to guide therapy of pneumococcal infections.

Ambulatory Care Facilities↗
PubMed1998

[Septicemic melioidosis in Southern Taiwan: a case report].

The patient was a 56 year-old man, a resident of Hen-Tsueng Township in Ping-Tung County. He worked as a ranger at Ken-Ting Farm in southern Taiwan, and had been to Thailand for sight-seeing 5 years ago. He came to our outpatient department about one month prior to hospitalization for intermittent fever of one week duration. At that time, complete blood count was within normal limits and a chest roentgenogram was unremarkable. He was given erythromycin without showing any clinical improvement. Two days prior to admission, he noted pain in the left hip. The next day, severe dyspnea developed suddenly and chest x-ray film revealed bilateral nodular lesions. Physical examination on hospitalization revealed an acutely ill and jaundiced male with a temperature of 37.4 degrees C, blood pressure: 110/47 mmHg, pulse rate: 137/min, and respiratory rate: 26/min. There were rales in both lungs, but no lymphadenopathy or organ enlargement. Laboratory study showed WBC: 1,470/mm(3), platelet count: 47,000/mm(3), blood sugar: 226 mg/dL, mildly elevated transaminases and bilirubin, and BUN: 69 mg/dL, Cr: 4.3 mg/dL. Arterial blood gas analysis indicated an acute metabolic acidosis with PaO2 of 32 mmHg. Despite the initial impression of melioidosis and administration of ceftazidime plus gentamicin, his condition rapidly deteriorated and expired 18 hours after admission. Two sets of blood cultures grew Burkholderia pseudomallei. Melioidosis has been called a great imitator of diseases and culture results are frequently misinterpreted. The mortality is high even with suggested therapy with ceftazidime, cotrimoxazole, amoxicillin-clavulanate, chloramphenicol, and/or tetracycline. There has been a total of 10 cases reported in southern Taiwan and 2 of them were clearly indigenous. Melioidosis should be included in the reportable diseases, and its prevalence in Taiwan also should be investigated.

Bacteremia↗
PubMed1998

Randomized, double-blind, placebo-controlled study of the safety and efficacy of vitamin B complex in the treatment of nocturnal leg cramps in elderly patients with hypertension.

Nocturnal leg cramps is a common and troublesome problem in elderly individuals, and their etiology is unknown. Treatment with quinine is a common practice, but the effectiveness of the drug is doubtful and adverse drug effects are common. This randomized, double-blind, placebo-controlled study was conducted to evaluate the safety and efficacy of vitamin B complex capsules (fursulthiamine 50 mg, hydroxocobalamin 250 micrograms, pyridoxal phosphate 30 mg, and riboflavin 5 mg) in 28 elderly patients with hypertension who had severe nocturnal leg cramps that disturbed their sleep. Self-reported ratings of leg cramp frequency, duration, and intensity were used to evaluate severity of nocturnal leg cramps. Both the patients taking vitamin B capsules (n = 14) and those taking placebo (n = 14) received medications three times daily, and were examined regularly at 2-week intervals for 3 months. After 3 months, 86% of the patients taking vitamin B had prominent remission of leg cramps, whereas those taking placebo had no significant difference from baseline. Treatment with vitamin B complex significantly reduced the frequency, intensity, and duration of nocturnal leg cramps. Because quinine is not without potential for side effects, and vitamin B complex is a relatively safe and effective alternative, clinicians should reconsider the treatment of choice for nocturnal leg cramps.

Aged↗
PubMed1998

Small cell carcinoma of the cervix: analysis of clinical and pathological findings.

PURPOSE OF INVESTIGATION: An attempt to better identify small cell carcinoma of the cervix and evaluate its prognosis. METHODS: From January of 1970 to March of 1995, a total of seven patients diagnosed with small cell carcinoma of the cervix by pathologic revision were retrospectively reviewed. Clinical information including age, clinical stage, lymph-vascular space invasion, lymph node metastases, prognoses were analyzed. RESULTS: All specimens stained positive for neuron-specific enolase (NSE) and four were positive for chromogranin (CGR). The majority of patients (71%) died of disease within 18 months. Only one patient had an abnormal Pap smear before definite diagnosis, and only one patient was well and alive after a combination of surgery and multi-agent chemotherapy (p<0.05). CONCLUSION: Pap smears may not be an appropriate screening method for detecting small cell carcinoma of the cervix. Immunohistological staining may be helpful in diagnosis of small cell carcinoma of the cervix. Because of a very poor prognosis, more effective therapeutic protocol should be further defined in the management of cervical small cell carcinoma.

Adult↗
PubMed1998

Elimination of hypercapnia may postpone the clinical presentation of malignant hyperthermia: a case report.

Malignant hyperthermia is a rare complication in clinical anesthesia, especially associated with the administration of succinylcholine or inhalation anesthetics. A 19-year-old patient, suffering from traumatic mandible fracture, underwent open reduction under general anesthesia. Unfortunately, following administration of succinylcholine, he also suffered severe facial twitch and the first episode of hypercapnia. After adequate management, the symptoms subsided. However, two hours later, the hypercapnia recurred, combined with progressive elevation of body temperature. After administration of intravenous dantrolene 120 mg, the patient's condition became stable and the procedure was completed without sequelae. As the muscle contracture test is not available in Taiwan, the clinical grading scale is presented as an alternative diagnostic method for malignant hyperthermia.

Adult↗
PubMed1998

Nonalcoholic fatty liver disease: assessment of variability in pathologic interpretations.

The exact cause, prevalence, and rate of progression of nonalcoholic fatty liver disease (NAFLD) are unclear because of a lack of agreement on the pathologic features associated with the different types of NAFLD, their clinical syndromes, and because of a lack of accuracy in the interpretation of these pathologic features. Studies of NAFLD would be aided by a consistent and standardized approach to the interpretation of pathologic features. The aim of our study was to assess interobserver and intraobserver variation in the histologic abnormalities associated with NAFLD. We identified histologic features of NAFLD as reported in the literature, and we identified patients with the diagnosis of NAFLD through the databases of two large institutions. Histologic parameters were evaluated for each liver biopsy specimen by four hepatopathologists and twice by two of the four pathologists (blindly). Interobserver and intraobserver concordance among the pathologists was measured by kappa statistics. Nineteen histologic parameters compartmentalized into steatosis, inflammation, liver cell injury, and fibrosis were evaluated on 53 liver biopsy specimens. Significant, substantial, or moderate concordance was present in only six items: the extent of steatosis, sinusoidal location of fibrosis, perivenular fibrosis, grade of fibrosis, ballooning degeneration, and the presence of vacuolated nuclei. Substantial or moderate concordance also was seen for interobserver readings for location of steatosis and periportal injury. Parameters of inflammation were not scored as reliably as parameters of fibrosis and cell injury. We conclude that only some histologic features previously reported in NAFLD (especially those with substantial and moderate concordance for both interobserver and intraobserver interpretation) are interpreted uniformly by experienced pathologists. These histologic features might prove useful for the development of a standardized and reliable pathologic scoring system that includes the full histologic spectrum of NAFLD and its various clinical outcomes.

Biopsy↗
PubMed1998

Dideoxy fingerprinting for rapid screening of rpoB gene mutations in clinical isolates of Mycobacterium tuberculosis.

Rifampin is a key component of therapeutic regimens for tuberculosis control, and a marker for multidrug resistance of Mycobacterium tuberculosis. Mutations responsible for conferring rifampin resistance in M. tuberculosis are known to occur in a 69-bp region of the rpoB gene. In this study, we assessed the accuracy of dideoxy fingerprinting (ddF), a hybrid technique employing elements of dideoxy sequencing and single-strand polymorphism analysis, for rapid screening of rifampin resistance in clinical isolates of M. tuberculosis. This technique was used to analyze 72 M. tuberculosis isolates. The results were compared with those of automated dideoxy sequencing and the antibiotic resistance profile (determined with the BACTEC system). Of the 72 isolates, 50 were rifampin resistant. The ddF findings were completely consistent with those of dideoxy sequencing in all isolates. In 68 (94%) isolates, the ddF findings were consistent with the rifampin resistance status determined with the BACTEC system; all four isolates with inconsistent results had no mutation in the 69-bp region, but were resistant to rifampin. Our findings suggest that ddF accurately detects mutations in the rifampin resistance-associated 69-bp region of the rpoB gene in clinical isolates of M. tuberculosis, and may be a valuable screening tool for rifampin resistance.

DNA Fingerprinting↗
PubMed1998

beta-Lactam resistance and beta-lactamase isoforms of Moraxella catarrhalis isolates in Taiwan.

Moraxella catarrhalis is an important pathogen in both upper and lower respiratory tract infections. More than 90% of isolates worldwide produce beta-lactamase. The beta-lactamases produced by M. catarrhalis can be differentiated by isoelectric focusing (IEF) into BRO-1 and BRO-2 patterns. In this study, we investigated the prevalence of various beta-lactamase isoforms in clinical isolates of M. catarrhalis in Taiwan, as well as the relationships of these isoforms with antibiotic resistance. A total of 271 clinical isolates of M. catarrhalis were collected from 12 large medical laboratories in Taiwan from 1 August 1993 to 31 July 1995. The overall prevalence of beta-lactamase production was 98.2% (266 of 271 isolates). Analytical IEF revealed BRO-1 was the most common beta-lactamase pattern among the isolates (238 isolates, 88%); BRO-2 was the only other pattern found, with 32 (12%) isolates. The geometric mean minimum inhibitory concentration of ampicillin for BRO-1 producers was 63-fold higher than that for beta-lactamase-negative isolates, and 6.5-fold higher than that for BRO-2 producers. beta-Lactam antibiotics, such as amoxicillin + clavulanate and the cephalosporins, tested were very active against this species, regardless of whether the isolate produced beta-lactamase or not. In conclusion, beta-lactamase is common among clinical isolates of M. catarrhalis in Taiwan, with BRO-1 being the most common isoform. However, because most isolates tested were still sensitive to amoxicillin + clavulanate and cephalosporins, these agents appear to be reliable alternatives to first-line therapy when M. catarrhalis is contributing to a clinical infection.

Anti-Bacterial Agents↗