Biomedical subjects

C J Tseng

Publications and source records attributed to C J Tseng.

At least 19 recordsLinked to original sources

PubMed2002

Hyperbaric oxygen increases the lung's susceptibility to inhaled lipopolysaccharide in mice.

Hyperbaric oxygen (HBO2) has been shown to inhibit the adhesion function of beta(2)-integrin, which is important in mediating cell-to-cell adhesion and extravasation of inflammatory cells. In the present study, we examined the effects of HBO2 exposure on neutrophil infiltration and tissue injury in a model of acute lung inflammation induced by lipopolysaccharide (LPS) inhalation. Male C57BL/6 mice of 8 weeks old were exposed to 3 atmosphere absolute (ATA) 100% HBO2, 3 ATA hyperbaric air (HBA), or room air for 90 min. After exposure, they were exposed to aerosolized LPS solution (1 mg/ml) or saline in a plexiglass chamber for 10 min. Four hours after inhalation, bronchoalveolar lavage (BAL) was performed to determine protein concentration, LDH activity, total cells, and differential cell counts in the lavage fluid (BALF). Myeloperoxidase (MPO) content, lung histopathology, and plasma nitric oxide (NO) metabolite concentrations were also determined in separate sets of animals. We observed that LPS inhalation increased neutrophil number in the BALF, which was significantly inhibited by HBO2 but not HBA pre-exposure. However, MPO content in the lung was prominently increased by HBO2 pre-exposure, which correlated with increased PMN infiltration in lung tissues. Further, HBO2 plus LPS, but not saline inhalation caused a significant increase in the BALF protein level and LDH activity compared with that of LPS inhalation alone. LPS exposure induced significant increase in plasma NO metabolites, which was not potentiated by HBO2 pre-exposure. The inducible nitric oxide synthase inhibitor, aminoguanidine, significantly attenuated the increases in plasma NO metabolites and tissue MPO content as well as lung injuries. In summary, our data suggest that HBO2 pre-exposure increases the lung's susceptibility to inhaled LPS, which may be related to increased tissue neutrophil infiltration and dependent on interaction(s) between HBO2 exposure with LPS-induced nitric oxide production.

Administration, Inhalation↗

PubMed2002

Down-regulation of basal Fos expression at nucleus tractus solitarii underlies restoration of baroreflex response after antihypertensive treatment in spontaneously hypertensive rats.

Antihypertensive therapy not only normalizes the elevated blood pressure but also restores the reduced baroreceptor reflex response associated with hypertension, although the underlying mechanism is not fully understood. We assessed the hypothesis that a reversal of the enhanced basal Fos expression seen during hypertension in nucleus tractus solitarii, the terminal site of baroreceptor afferents, underlies the restoration of baroreceptor reflex sensitivity after antihypertensive treatment. Male adult spontaneously hypertensive or normotensive Wistar-Kyoto rats received for 3 weeks captopril (100 mg/kg/day) added to their drinking water. Evaluated subsequently under pentobarbital anesthesia, captopril-treated spontaneously hypertensive rats exhibited significantly lowered systolic blood pressure and restoration of the sensitivity in baroreceptor reflex control of heart rate to levels comparable with Wistar-Kyoto rats. Reverse transcription-polymerase chain reaction analysis and immunohistochemical evaluation revealed concomitant down-regulation of basal expression in nucleus tractus solitarii of c-fos gene at both mRNA and protein levels. Captopril treatment, on the other hand, elicited no discernible effect on systolic blood pressure, cardiac baroreceptor reflex sensitivity or basal expression of Fos protein at the nucleus tractus solitarii of normotensive Wistar-Kyoto rats. From these findings we suggest that a down-regulation of basal Fos expression in nucleus tractus solitarii may contribute to the restoration of baroreceptor reflex sensitivity in spontaneously hypertensive rats that received antihypertensive treatment such as captopril.

Animals↗

PubMed2001

Isolated paraaortic lymph node recurrence after definitive irradiation for cervical carcinoma.

PURPOSE: To evaluate the clinical features of isolated paraaortic lymph node (PALN) recurrence after definitive radiotherapy, and analyze the prognostic factors and effect of salvage treatment. METHODS AND MATERIALS: Of a total 876 patients who received pelvic radiotherapy after the diagnosis of primary cervical carcinoma, 26 were found to have isolated PALN recurrence as the first recurrent site, and these patients enrolled in this study. Only those with primary-site carcinoma controlled and who were free of other distant metastases were eligible. Nineteen of the 26 patients accepted salvage therapy. Fourteen patients accepted concurrent chemoradiation (CCRT), 1 accepted radiation to the paraaortic region, and 4 accepted chemotherapy alone. Clinical parameters evaluated included tumor markers (SCC and CEA) and image studies. RESULTS: Seven of the 26 patients were alive and disease-free. All 7 survivors had salvage treatment with radiation to the paraaortic region and concurrent cisplatin-based chemotherapy. None of the patients receiving chemotherapy or radiation alone enjoyed long-term, disease-free survival. The 5-year survival rate for isolated PALN recurrence of the 14 patients who accepted salvage concurrent chemoradiation (CCRT) was 51.2%. The presence of a clinical symptom at the time of PALN recurrence was analyzed. Seven of the 12 asymptomatic patients and none of the 14 symptomatic patients survived without disease after salvage treatment. The SCC levels at recurrence showed a statistically significant relationship to disease-free survival. CONCLUSIONS: An SCC level of < or = 4 ng/ml and a lack of symptoms at the time of recurrence were good prognostic factors in isolated PALN recurrence after primary radiation therapy. In addition to concurrent CCRT, periodical surveillance with tumor markers and imaging studies allowed early detection and salvage of those patients.

Adult↗

PubMed2001

Cochlear gene delivery through an intact round window membrane in mouse.

Cochlear gene transfer studies in animal models have utilized mainly two delivery methods: direct injection through the round window membrane (RWM) or intracochlear infusion through a cochleostomy. However, the surgical trauma, inflammation, and hearing loss associated with these methods lead us to investigate a less invasive delivery method. Herein, we studied the feasibility of a vector transgene-soaked gelatin sponge, Gelfoam, for transgene delivery into the mouse cochlea through an intact RWM. The Gelfoam absorbed with liposomes and adenovirus, but not with adeno-associated virus (AAV), was successful in mediating transgene expression across an intact RWM in a variety of cochlear tissues. The Gelfoam technique proved to be an easy, atraumatic, and effective, but vector-dependent, method of delivering transgenes through an intact RWM. Compared with the more invasive gene delivery methods, this technique represents a safer and a more clinically viable route of cochlear gene delivery in humans.

Adenoviridae↗

PubMed2001

Griseofulvin potentiates antitumorigenesis effects of nocodazole through induction of apoptosis and G2/M cell cycle arrest in human colorectal cancer cells.

In this study, we demonstrate that apoptosis and G2/M cell cycle arrest were easily induced by treatment with the oral-antifungal agent, griseofulvin (GF). The mechanisms of GF-induced G2/M arrest were characterized as (a) induction of abnormal mitotic spindle formation, (b) elevation of cyclin B1/cdc2 kinase activity and (c) down-regulation of myt-1 protein expression. On the other hand, caspase 3 activation, Bcl-2 hyperphosphorylation and inhibition of the normal function of Bcl-2 associated with Bax were demonstrated to be the mechanisms of GF-induced apoptosis. DNA fragmentation and flow cytometry analyses demonstrated that combined treatment of GF with the cancer chemotherapeutic agent, nocodazole (ND), strongly potentiates the apoptotic effect and arrest of the G2/M cell cycle in 5 types of human cancer cells, but not in normal human keratinocytes (#76 KhGH). The combined treatment of GF and ND triggered the polymerization of purified tubulin in HT 29 but not in #76 KhGH cells. To further confirm these observations, the therapeutic efficacy was further examined in vivo by treating athymic mice bearing COLO 205 tumor xenografts, with GF (50 mg/kg), ND (5 mg/kg) or GF + ND. Combined treatment of GF and ND significantly enhanced the effect of ND, and led to cessation of tumor growth. These results suggest that chemotherapeutic agents (such as ND) administered in the presence of GF might provide a novel therapy for colorectal cancer.

Animals↗

PubMed2001

Applications of the telomerase assay in peritoneal washing fluids.

OBJECTIVE: The aim of this study was to detect telomerase activity in peritoneal ascites and to assess whether it can be used as an assistant tool for the early detection of ovarian cancer. METHODS: Telomerase activity was measured by TRAP assay in 47 patients with ovarian malignancies and 50 patients with benign uterine leiomyomas (control group). RESULTS: All 26 peritoneal washing cytology positive cases were telomerase positive. Of the 21 peritoneal washing cytology negative cases, 3 were telomerase positive. When these 3 were reevaluated for peritoneal cytology, malignant ascitis was identified in 1. All telomerase negative cases were negative for peritoneal washing cytology. The sensitivity and specificity of peritoneal cytology and telomerase testing in correlation with true malignant cells were 96 (26/27) and 100% (20/20) versus 100 (27/27) and 90% (18/20), respectively. The false negative rate of peritoneal cytology was 4.7% (1/21). The false positive rate of the telomerase test in relation to malignant ascites was 6.9% (2/29). CONCLUSION: Our preliminary results reveal a high sensitivity and specificity of both telomerase testing and conventional cytology in peritoneal fluids. Our data suggest that the telomerase test in peritoneal fluids can be used as an adjuvant to cytopathological methods in the diagnosis of malignant peritoneal ascites, particularly in cases of negative cytology. In these cases, a review of peritoneal histocytology is advised.

Adult↗

PubMed2001

Negative predictive value of human papillomavirus test following conization of the cervix uteri.

OBJECTIVE: The goal of this study was to determine/evaluate the negative predictive value of human papillomavirus (HPV) testing following conization of cervix uteri. METHODS: A prospective analysis was undertaken on 79 cone biopsies of women with high-grade lesions (cervical intraepithelial neoplasia (CIN) III). HPV testing was performed on cervical smears before and after conization. We correlated the margin status (defined as positive cone margin or endocervical curettage status) and positive conization HPV status with the residual disease in a hysterectomy specimen. A Digene II kit was used to perform HPV testing. HPV detection was done by Hybrid Capture assay. RESULTS: Of the 79 patients, 47(59.5%) had positive margins after conization. HPV testing was positive in 37 cases (78.7%) and negative in 10 cases (21.3%). Residual disease was found in 31 of 47 (66%) postconization hysterectomy specimens. No residual lesions were found in HPV-negative cases. Of the 32 cases with negative margins following conization, HPV testing was negative in 25 cases (78%) and was positive in 7 cases (22%). Among these 25 cases with negative HPV tests, no residual lesion was detected, and in 7 HPV-positive cases, only one residual lesion was found. CONCLUSION: HPV testing is potentially an effective tool in predicting residual dysplasia after conization and could potentially assist in the decision between hysterectomy and conservative follow-up in women with CIN III.

Cervix Uteri↗

PubMed2001

Modulation of catecholamine release by endogenous adenosine in the rat adrenal medulla.

Adenosine was shown to inhibit norepinephrine (NE) release from sympathetic nerve endings. The purpose of this study was to examine whether endogenous adenosine restrains NE and epinephrine release from the adrenal medulla. The effects of an adenosine receptor antagonist, 1,3-dipropyl-8-(p-sulfophenyl) xanthine (DPSPX), on epinephrine and NE release induced by intravenous administration of insulin in conscious rats were examined. Plasma catecholamines were measured by HPLC with an electrochemical detector. DPSPX significantly increased plasma catecholamine in both control rats and rats treated with insulin. The effect of DPSPX on plasma catecholamine was significantly greater in rats treated with insulin. Additional experiments were performed in adrenalectomized rats to investigate the contribution of the adrenal medulla to the effect of DPSPX on plasma catecholamine. The effect of DPSPX and insulin on epinephrine in adrenalectomized rats was significantly reduced compared with that of the controls. Finally, we tested whether endogenous adenosine restrains catecholamine secretion partially through inhibiting the renin-angiotensin system. The effect of DPSPX on plasma catecholamine in rats pretreated with captopril (an angiotensin-converting enzyme inhibitor) was reduced. These results demonstrate that under basal physiological conditions, endogenous adenosine tonically inhibits catecholamine secretion from the adrenal medulla, and this effect is augmented when the sympathetic system is stimulated. The effect of endogenous adenosine on catecholamine secretion from the adrenal medulla is achieved partially through the inhibitory effect of adenosine on the renin-angiotensin system.

Adenosine↗

PubMed2001

A surgical approach appropriate for targeted cochlear gene therapy in the mouse.

Therapeutic manipulations of the mammalian cochlea, including cochlear gene transfer, have been predominantly studied using the guinea pig as the experimental model. With the significant developments in mouse genomics and the availability of mutant strains of mice with well-characterized hearing loss, the mouse justifiably will be the preferred animal model for therapeutic manipulations. However, the potential advantages of the mouse model have not been fully realized due to the surgical difficulty of accessing its small cochlea. This study describes a ventral approach, instead of the routinely used postauricular approach in other rodents, for accessing the mouse middle and inner ear, and its application in cochlear gene transfer. This ventral approach enabled rapid and direct delivery of liposome-transgene complex to the mouse inner ear while avoiding blood loss, facial nerve morbidity, and mortality. Transgene expression at 3 days was detected in Reissner's membrane, spiral limbus, spiral ligament, and spiral ganglion cells, in a pattern similar to that previously described in the guinea pig. The successful access and delivery of material to the mouse cochlea and the replication of gene expression seen in the guinea pig demonstrated in this study should promote the use of the mouse in future studies investigating targeted cochlear therapy.

Animals↗

PubMed2001

Value of human papillomavirus deoxyribonucleic acid testing after conization in the prediction of residual disease in the subsequent hysterectomy specimen.

OBJECTIVE: Our aim was to evaluate human papillomavirus deoxyribonucleic acid testing after conization in predicting residual disease in the subsequent hysterectomy specimen. STUDY DESIGN: A prospective study was conducted on 75 patients with grade 3 cervical intraepithelial neoplasia who had cone margins or endocervical curettage specimens showing disease and who elected to undergo hysterectomy after conization. All patients underwent high-risk human papillomavirus deoxyribonucleic acid testing by the Hybrid Capture II (Digene Corporation, Gaithersburg, MD) system before conization and at the time of hysterectomy (within 2-7 weeks after conization). The presence of human papillomavirus deoxyribonucleic acid in cells obtained by endocervical brush before hysterectomy was correlated with residual disease in the hysterectomy specimens. RESULTS: Of the 92 patients enrolled, 75 were eligible. Of these 75 patients, 52 (69.3%) had persistent human papillomavirus deoxyribonucleic acid after conization, and 27 (36.0%) of the 75 patients had residual cervical neoplasia in the hysterectomy specimens. Those with negative results for human papillomavirus deoxyribonucleic acid after conization were all (23/23) without residual disease in the uterus (100% negative predictive value). All those who had residual disease (27/27) had positive results for human papillomavirus deoxyribonucleic acid at the time of hysterectomy (100% sensitivity). Postconization human papillomavirus deoxyribonucleic acid status (odds ratio, 4.000; 95% confidence interval, 1.531-10.449; P =.005) and grade of dysplasia after endocervical curettage (classified as grade 2 cervical intraepithelial neoplasia or less severe disease vs grade 3 cervical intraepithelial neoplasia: odds ratio, 6.612; 95% confidence interval, 2.837-15.409; P =.0002) were significantly associated with residual tumor in the uterus. CONCLUSIONS: This prospective study confirms an excellent sensitivity and negative predictive value of human papillomavirus deoxyribonucleic acid testing after conization in predicting residual cervical neoplasia. A strategy of managing patients with grade 3 cervical intraepithelial neoplasia, based on postconization human papillomavirus deoxyribonucleic acid findings and endocervical curettage results, is proposed.

Adult↗

PubMed2001

High prevalence of high grade squamous intraepithelial lesions and microinvasive carcinoma in women with a cytologic diagnosis of low grade squamous intraepithelial lesions.

OBJECTIVE: To evaluate the histologic nature of low grade intraepithelial lesion (LSIL) in a region with a high prevalence of invasive cervical carcinoma and to propose a management protocol. STUDY DESIGN: Comparing the follow-up of 877 women with LSIL during a 43-month period, taking into consideration the histologic nature determined by colposcopic biopsy, endocervical curettage, conization or hysterectomy as the final pathologic diagnosis. RESULTS: During the study period, from July 1994 to February 1998, a total of 128,925 Pap smears were performed at our institute, with 877 (0.68%) diagnosed as LSIL. Among these, 722 women with CIN1-SIL and 32 with human papillomavirus-related changes (HPV-SIL) were enrolled in the study. Of the 543 women with CIN 1/squamous intraepithelial lesion, 145 (27%) cases of high grade squamous intraepithelial lesion were disclosed histologically, as were 16 (3%) cases of microinvasion. Among those followed at an interval of three months with a Pap smear alone, the persistence rate was 46.8%, while the regression rate was 40%. Thirty-two women with HPV/SIL underwent histologic evaluation, revealing 18% CIN 2/3 with no microinvasion. CONCLUSION: A high percentage of CIN 2/3 as well as microinvasive lesions will go unnoticed in the absence of colposcopic evaluation.

Colposcopy↗

PubMed2001

Significance of cardiac troponin I and creatine kinase release after coronary intervention.

BACKGROUND: Cardiac troponin I is a highly sensitive and specific marker for early detection of myocardial injury. Whether it can be used to monitor myocardial injury after coronary intervention is uncertain. This study was designed to measure the cardiac troponin I and creatine kinase (CK) after coronary intervention and investigate their clinical significance. METHODS: We measured cardiac troponin I and CK levels before intervention and 4 hours, 8 hours, 12 hours and 24 hours after apparently successful coronary intervention in 106 eligible patients. Nine patients were excluded due to missing data. We also followed up the clinical outcome to record major cardiac events (MACE). RESULTS: The frequency of cardiac troponin I increase after coronary intervention was higher than that of CK increase (40.2% vs 8.2%). The frequency of cardiac troponin I increase in the stent group was significantly higher than that in the PTCA group (49.2% vs 21.9%, p < 0.001). The frequency of cardiac troponin I increase was also higher than that of CK increase in patients with in-hospital events (58.8% vs 14.7%). CONCLUSIONS: Cardiac troponin I is more sensitive than creatine kinase in detecting myocardial injury after coronary intervention. The incidence of cardiac troponin I increase is significantly higher in patients undergoing stenting than in patients treated with balloon angioplasty only. The cardiac troponin I increase is more highly correlated with in-hospital events than is creatine kinase.

Adult↗

PubMed2001

Transthoracic and transesophageal echocardiographic diagnosis of aneurysm of the sinus of Valsalva: a review of five year experience.

BACKGROUND: Aneurysms of the sinus of Valsalva (SVA) are uncommon congenital lesions. The clinical presentations vary from asymptomatic to progressive heart failure following rupture of the aneurysm into an adjacent cardiac chamber. Retrograde aortogram is the diagnostic tool of choice preoperatively. Recent studies have demonstrated that the SVA can be accurately diagnosed using transthoracic two-dimensional, and color Doppler flow mapping, even for surgical preparation without cardiac catheterization. We report our 5-year experience of transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) in the evaluation of SVA. METHODS: Eleven adult patients with SVA with or without rupture were studied using both TTE and TEE. All of the diagnoses were subsequently comfirmed by either cardiac catheterization or surgical findings. RESULTS: Aneurysms originated in the right coronary sinus (n = 9) and noncoronary sinus (n = 2); they ruptured into the right ventricle in 5 patients and the right atrium in 5 patients. An unruptured right SVA was noted in 1 patient. Both TTE and TEE could identify the site of the aneurysm, rupture sites, and the receiving chamber equally well. Co-existent cardiac lesions included 11 cases of valvular aortic regurgitation (mild in 7, moderate in 2 and severe in 2). Two cases of perimembranous type ventricular septal defect (VSD) and 6 cases of supracristal type VSD (including 1 case of tetraology of Fallot, 3 supracristal, 1 muscular and 1 subaortic) were noted. Three cases were complicated with valvular vegetations (1 aortic valve, 1 aortic and tricuspid valve and 1 aortic and pulmonic valve). One patient had patent ductus arteriosus and 2 patients had pulmonic valvular stenosis. CONCLUSIONS: TEE provides clearer definition for the detailed anatomy of the ruptured sac and co-existent cardiac lesions than TTE through high resolution and closer approach. We conclude that TEE is a powerful complementary diagnostic tool in the evaluation of patients with SVA. TEE also provides additionally useful information for guiding the surgical approach and for assessing the operative results even without cardiac catheterization.

Adult↗

PubMed2000

Reciprocal regulation of nitric oxide and glutamate in the nucleus tractus solitarii of rats.

Nitric oxide (NO) and glutamate are both important mediators of the central cardiovascular regulation in the nucleus tractus solitarii. Our previous studies revealed that the central cardiovascular effects of NO in the nucleus tractus solitarii could be inhibited by glutamate receptor blockade. On the other hand, nitric oxide synthase (NOS) inhibitor attenuated the cardiovascular effects of glutamate. Thus, NO and glutamatergic systems appear to interact in central cardiovascular regulation. The present study examined whether NO and glutamate may affect each other's release/production in the nucleus tractus solitarii. A microdialysis probe was implanted into the nucleus tractus solitarii of male Sprague-Dawley rats, and the changes in the extracellular levels of glutamate and NO were determined by high performance liquid chromatography coupled with electrochemical detection and an NO analyzer, respectively. The results showed that NO solution elicited >10 fold increases in the extracellular level of glutamate, which returned to normal 60 min after the end of NO perfusion. The NO donor N-acetyl-penicillamine (SNAP) had an effect similar to NO solution. Furthermore, the glutamate level was reduced to 61% of basal value by perfusion with the NOS inhibitor, N(G)-monomethyl-L-arginine (L-NMMA). When glutamate receptor agonist N-methyl-D-aspartic acid (NMDA) or alpha-amino-3-hydroxy-5-methylixoxazole-4-propionic acid (AMPA) was administered into the nucleus tractus solitarii, the extracellular NO level was increased by 70-100%, whereas glutamate receptor antagonists (MK-801 hydrogen maleate and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX)) did not alter the basal levels of NO. These results suggest that NO and glutamate may enhance each other's release/production in the nucleus tractus solitarii. This reciprocal regulation of NO and glutamate may be important in central cardiovascular control in the nucleus tractus solitarii.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed2000

Mechanisms of nordihydroguaiaretic acid-induced [Ca2+]i increases in MDCK cells.

The effect of nordihydroguaiaretic acid (NDGA), a lipoxygenase inhibitor, on Ca2+ signaling in Madin Darby canine kidney (MDCK) cells has been investigated. NDGA (10-100 microM) increased [Ca2+]i concentration-dependently. The [Ca2+]i increase comprised an initial slow rise and a plateau over a time period of 5 min. Ca2+ removal partly inhibited the Ca2+ signals induced by 25-100 microM NDGA and abolished that induced by 10 microM NDGA. In Ca(2+)-free medium, pretreatment with 0.1 mM NDGA for 12 min abolished the [Ca2+]i increase induced by the mitochondrial uncoupler carbonylcyanide m-chlorophenylhydrazone (CCCP; 2 microM) and the endoplasmic reticulum (ER) Ca2+ pump inhibitor thapsigargin (1 microM). However, 0.1 mM NDGA still increased [Ca2+]i after Ca2+ stores had been depleted by pretreating with 2 microM CCCP, 1 microM thapsigargin and 0.1 mM cyclopiazonic acid. NDGA (50 microM) activated Mn2+ quench of fura-2 fluorescence at 360 nm excitation wavelength, which was almost abolished by 50 microM La3+. This implies NDGA induced Ca2+ influx mainly via a La(3+)-sensitive pathway. Consistently, 50 microM La3+ pretreatment inhibited 0.1 mM NDGA-induced [Ca2+]i increase. Adding 3 mM Ca2+ increased [Ca2+]i in cells pretreated with 0.1 mM NDGA in Ca(2+)-free medium, suggesting NDGA activated capacitative Ca2+ entry. Pretreatment with 0.1 mM NDGA for 200 s prior to Ca2+ did not alter 1 microM thapsigargin-induced capacitative Ca2+ entry. Pretreatment with 40 microM aristolochic acid to inhibit phospholipase A2 reduced 0.1 mM NDGA-induced Ca2+ release by 65%, but inhibiting phospholipase C with 2 microM U73122 had little effect. This suggests NDGA-induced Ca2+ release was independent of inositol 1,4,5-trisphosphate (IP3), but was modulated by phospholipase A2.

Animals↗

PubMed2000

A novel action of the antianginal drug bepredil: induction of internal Ca(2+) release and external Ca(2+) influx in Madin-Darby canine kidney (MDCK) epithelial cells.

The effect of the antianginal drug bepridil on Ca(2+) signaling in Madin-Darby canine kidney (MDCK) cells was investigated by using fura-2 as a Ca(2+) probe. Bepridil at 10-50 microM evoked a significant rise in cytosolic free Ca(2+) concentration ([Ca(2+)](i)) in a dose-dependent manner. The [Ca(2+)](i) rise consisted of an immediate initial rise and a slow decay. Removal of external Ca(2+) partly inhibited the Ca(2+) signals by reducing both the initial rise and the decay phase, suggesting that bepridil activated both external Ca(2+) influx and internal Ca(2+) release. In Ca(2+)-free medium, pretreatment with 50 microM bepridil nearly abolished the Ca(2+) release induced by thapsigargin (1 microM), an endoplasmic reticulum Ca(2+) pump inhibitor, and vice versa, pretreatment with thapsigargin inhibited most of the bepridil-induced Ca(2+) release, suggesting that the thapsigargin-sensitive Ca(2+) store was the main source of bepridil-induced Ca(2+) release. Bepridil (50 microM) induced considerable Mn(2+) quench of fura-2 fluorescence at an excitation wavelength of 360 nm, which was partly inhibited by La(3+) (0.1 mM). Consistently, La(3+) (0.1 mM) pretreatment significantly inhibited the bepridil-induced [Ca(2+)](i) rise. Addition of 3 mM Ca(2+) induced a significant [Ca(2+)](i) rise after prior incubation with 10-50 microM bepridil in Ca(2+)-free medium, suggesting that bepridil induced dose-dependent capacitative Ca(2+) entry. However, 50 microM bepridil inhibited 1 microM thapsigargin-induced capacitative Ca(2+) entry by 38%. Pretreatment with aristolochic acid (40 microM) so as to inhibit phospholipase A(2) inhibited 50 microM bepridil-induced internal Ca(2+) release by 42%, but inhibition of phospholipase C with U73122 (2 microM) or inhibition of phospholipase D with propranolol (0.1 mM) had little effect, suggesting that bepridil induced internal Ca(2+) release in an inositol 1,4,5-trisphosphate-independent manner that could be modulated by phospholipase A(2)-coupled events. This is the first report providing evidence that bepridil, currently used as an antianginal drug, induced a rise in [Ca(2+)](i) in a non-excitable cell line.

Angina Pectoris↗

PubMed2000

Systemic administration of d-amphetamine induces long-lasting oxidative stress in the rat striatum.

The long-term effect of d-amphetamine (AMPH) on the induction of oxidative stress was examined in vivo in the rat brain. In this study, 2,3-dihydroxybenzoic acid (2,3-DHBA) and malonaldehyde (MDA) were used as the index of the hydroxyl radical and lipid peroxidation, respectively. The levels of 2,3-DHBA, MDA and dopamine (DA) in striatal homogenates were examined 7 days following injection of a single large dose of AMPH (7.5 mg/kg, i.p.) in rats pretreated with desipramine (10 mg/kg, i.p.), an agent that inhibits the metabolism of AMPH. Our results showed that 2,3-DHBA and MDA levels were significantly increased by AMPH, whereas DA and its metabolites, DOPAC and HVA were depleted in the striatum. Pretreatment with the glutamate NMDA receptor subtype antagonist MK-801 (1 mg/kg, i.p.) attenuated the increases of 2,3-DHBA and MDA, and provided partial protection against the long-lasting loss of DA produced by AMPH. Overall, the results demonstrate that AMPH could induce sustained production of free radical and oxidative damage, and lead to DA terminal degeneration in the striatum of the rat.

Animals↗

PubMed2000

Effect of sevoflurane on Ca2+ mobilization in Madin-Darby canine kidney cells.

We investigated the effect of the volatile anesthetic sevoflurane on Ca2+ signaling in Madin-Darby canine kidney (MDCK) cells by using the fluorescent dye fura-2/AM (1-[2-(5-carboxyoxazol-2-yl)-6-aminobenzofuran-5-oxy]-2-(2'-amino-5'-methylphenoxy)-ethane-N,N,N,N-tetraacetic acid pentaace-toxymethyl ester) as the Ca2+ indicator. At a concentration of 0.15 mM, sevoflurane did not alter basal cytosolic free calcium concentration ([Ca2+]i); however, at concentrations of 0.45-0.6 mM, sevoflurane did elevate [Ca2+]i, mainly by releasing Ca2+ from the endoplasmic reticulum (ER) store. Sevoflurane (0.15 mM) did not change either the [Ca2+]i peak evoked by high doses of ATP or UTP or inhibition of the ER Ca2+ pump, although it did significantly slow down the decay of the [Ca2+]i rise. Lastly, sevoflurane inhibited the capacitative Ca2+ entry and Mn2+ quench of fura-2 fluorescence induced by Ca(2+)-mobilizing ligands.

Anesthetics, Inhalation↗