Biomedical subjects

T-C Kao

Publications and source records attributed to T-C Kao.

4 recordsLinked to original sources

PubMed2006

KCNQ channels mediate IKs, a slow K+ current regulating excitability in the rat node of Ranvier.

Mutations that reduce the function of KCNQ2 channels cause neuronal hyperexcitability, manifested as epileptic seizures and myokymia. These channels are present in nodes of Ranvier in rat brain and nerve and have been proposed to mediate the slow nodal potassium current I(Ks). We have used immunocytochemistry, electrophysiology and pharmacology to test this hypothesis and to determine the contribution of KCNQ channels to nerve excitability in the rat. When myelinated nerve fibres of the sciatic nerve were examined by immunofluorescence microscopy using antibodies against KCNQ2 and KCNQ3, all nodes showed strong immunoreactivity for KCNQ2. The nodes of about half the small and intermediate sized fibres showed labelling for both KCNQ2 and KCNQ3, but nodes of large fibres were labelled by KCNQ2 antibodies only. In voltage-clamp experiments using large myelinated fibres, the selective KCNQ channel blockers XE991 (IC50 = 2.2 microm) and linopirdine (IC50 = 5.5 microm) completely inhibited I(Ks), as did TEA (IC50 = 0.22 mm). The KCNQ channel opener retigabine (10 microm) shifted the activation curve to more negative membrane potentials by -24 mV, thereby increasing I(Ks). In isotonic KCl 50% of I(Ks) was activated at -62 mV. The activation curve shifted to more positive potentials as [K+]o was reduced, so that the pharmacological and biophysical properties of I(Ks) were consistent with those of heterologously expressed homomeric KCNQ2 channels. The ability of XE991 to selectively block I(Ks) was further exploited to study I(Ks) function in vivo. In anaesthetized rats, the excitability of tail motor axons was indicated by the stimulus current required to elicit a 40% of maximal compound muscle action potential. XE991 (2.5 mg kg(-1) i.p.) eliminated all nerve excitability functions previously attributed to I(Ks): accommodation to 100 ms subthreshold depolarizing currents, the post-depolarization undershoot in excitability, and the late subexcitability after a single impulse or short trains of impulses. Due to reduced spike-frequency adaptation after XE991 treatment, 100 ms suprathreshold current injections generated long trains of action potentials. We conclude that the nodal I(Ks) current is mediated by KCNQ channels, which in large fibres of rat sciatic nerve appear to be KCNQ2 homomers.

Action Potentials↗

PubMed2005

Sero-epidemiology of Toxocara canis infection among aboriginal schoolchildren in the mountainous areas of north-eastern Taiwan.

A sero-epidemiological study of Toxocara canis infection was conducted among Atayal schoolchildren (aged 7-12 years) residing in the mountainous areas of north-eastern Taiwan. The 73 children investigated were each checked for anti-Toxocara IgG, in ELISA based on the larval excretory-secretory antigens of T. canis larvae. A short, self-administered questionnaire was then used to collect relevant information from each subject, including data on the keeping of dogs, playing in soil, eating raw vegetables, and whether the subjects normally washed their hands before eating. Once the seropositive children had been identified, odds ratios (OR), with their corresponding 95% confidence intervals (CI) and P-values, were calculated for each potential risk factor. When diluted 1:64, sera from 42 (57.5%) of the children gave a positive result in the ELISA, indicating that these 42 children were seropositive for T. canis infection. Seropositivity did not appear to be associated with the age or gender of the subject, the eating of raw vegetables, or the regular failure to wash hands prior to a meal. Compared with the other subjects, however, those who admitted living in a household where dogs were kept (OR = 3.79; CI = 1.23-11.69; P = 0.02) or playing in soil (OR = 3.00; CI = 1.10-8.16; P = 0.03) appeared at increased risk of seropositivity.

Age Distribution↗

PubMed2003

Late-presenting appendicitis: a laparoscopic approach to a complicated problem.

BACKGROUND: Acute appendicitis is the most common abdominal condition necessitating urgent surgical intervention in the United States. The objective of this study was to determine if interval laparoscopic appendectomy after initial nonoperative treatment for late appendicitis presenting as an appendiceal mass is a safe alternative to immediate appendectomy. METHODS: Thirty two consecutive patients (aged 16-74 years) during a 5-year period presented with appendiceal mass. Seventeen received initial nonsurgical treatment followed by interval laparoscopic appendectomy (aged 16-60 years; group 1). Fifteen underwent immediate appendectomy (aged 16-74 years; group 2). RESULTS: All patients in the interval laparoscopic appendectomy group improved with initial therapy and underwent surgery an average of 4.9 months later. Although the operative time and the complication rate were similar between groups 1 and 2, the time to return to baseline activities was significantly less in group 1 after adjusting for age (p = 0.02 or less). CONCLUSIONS: Interval laparoscopic appendectomy is safe in patients with chronic appendicitis and allows for judicious diagnostic evaluation of the appendiceal mass and planned surgery under controlled conditions.

Acute Disease↗

PubMed1998

Preoperative and operative factors to predict incontinence, impotence and stricture after radical prostatectomy.

The purpose of this study was to determine the incidence of patient-self reported post prostatectomy incontinence, impotence, bladder neck contracture or stricture, better, same or worse quality of life and willingness for same treatment again in a large group of radical prostatectomy (RP) patients and to determine if these morbidities are predictable with demographic, surgical or prostate cancer (PC) factors. Methods: A patient self-reporting questionnaire was completed and returned by 374 out of 458 eligible (81.7%) RP patients from one center, 267 (72.2%) have been operated since 1990 and all of whom were a minimum six month postoperative (75%>1 y). Questionnaire results were independently analyzed by a third party and correlated to demographic, operative, and tumor factors in an ongoing comprehensive PC database. Results: The patient self-reported incidence of post prostatectomy incontinence (any degree), impotence, and bladder neck contracture or stricture was 72.2, 87.4, and 25.9%, respectively. The reported rate of incontinence requiring protection was 39.0% and only 2.4% had persistent bladder neck contracture/stricture. Pathologic stage (continuous variable) was the only factor to significantly predict incontinence and no factor could predict impotence or bladder neck contracture/stricture in univariate analysis. No factor was predictive of morbidity by multivariate analysis. Despite incontinence and impotence significantly affecting QOL self-reporting (P=0.001, 0.001, respectively) and willingness to undergo RP again (P=0.001, 0.067, respectively), the majority of patients would choose surgery again. Conclusions: Although radical prostatectomy morbidity is common and affects patient-reported overall QOL, most patients would choose the same treatment again. Demographic, preoperative, operative, and tumor factors did not reliably predict patient-reported morbidity in this series.

Journal Article↗