Biomedical subjects

T C Lin

Publications and source records attributed to T C Lin.

At least 55 records · Page 3Linked to original sources

PubMed1997

Residues at the carboxy terminus of T4 DNA polymerase are important determinants for interaction with the polymerase accessory proteins.

Three T4 DNA polymerase accessory proteins (44P/62P and 45P) stimulate the polymerase (pol) activity and the 3'-5' exonuclease (exo) activity of T4 DNA polymerase (43P) on long, double-stranded DNA substrates. The 44P/62P "clamp loader" facilitates the binding of 45P, the "sliding clamp", to DNA that is primed for replication. Using a series of truncated 43P mutants, we identified a region at the extreme carboxy terminus of the DNA polymerase that is required for its interaction with accessory proteins. Truncation mutants of 43P lacking the carboxy-terminal 3, 6, or 11 residues retained full pol and exo activity on short synthetic primer-templates. However, the ability of the accessory proteins to enhance these activities on long double-stranded DNA templates was drastically reduced, and the extent of the reduction in activity was greater as more residues were deleted. One of the truncation mutants (N881), which had 17 residues removed from the carboxy terminus, showed reduced binding affinity and diminished pol activity but enhanced exo activity upon incubation with a small primer-template. The exo activity of the N881 mutant, on short, single-stranded DNA was unchanged, however, compared to the wild-type enzyme. These results are consistent with inferences drawn from the crystal structure of a DNA polymerase from a related T-even phage, RB69, where the carboxy-terminal 12 residues (equivalent to the 11 residues of 43P from phage T4) protrude from the thumb domain and are free to interact with complementary surfaces of the accessory proteins. The structural integrity of the thumb region in the N881 mutant is probably perturbed and could account for its reduced binding affinity and pol activity when incubated with short, double-stranded DNA substrates.

Amino Acid Sequence↗

PubMed1997

Stereomorphologic observation of bone tissue response to hydroxyapatite using SEM with the EDTA-KOH method.

To obtain further information on the interaction of hydroxyapatite (HA) and the bony implantation bed, 20- to 40- mesh dense HA particles were implanted into the tibiae of dogs. Following healing periods of 2 weeks, 1 month, and 3 months, the specimens were retrieved and prepared by either conventional preparatory procedures for scanning electron microscopy (SEM) of the EDTA-KOH method. Under SEM observation, the interparticular osteogenesis among HA particles progressed in a programmed sequence. Ample blood supply and osteoblasts initially presented in the interparticular space. The secretion of bone matrix resulted in the formation of immature bone. This scaffold was then transformed into mature lamellar bone during the following bone remodeling process. The serial changes closely resembled the pattern viewed in controls that did not implant HA. A spatial relationship between bone cells and HA was clearly demonstrated. In particular, the osteoblasts displayed an extremely flat appearance with many microappendages. The microappendages anchored cells to the HA surface and fused with granular material covering the HA crystals. The more characteristic cellular morphology was revealed by the EDTA-KOH method. Microscopic pictures clearly identified the three-dimensional images of ruffled borders of osteoclasts and the slender cytoplasmic processes of osteocytes. This study provided further evidence for the favorable biological response of HA to bone cells as well as the value of the EDTA-KOH method in examining the stereomorphology of bone cells.

Animals↗

PubMed1997

Large bowel tuberculosis and possible influencing factors for surgical prognosis: 30 years' experience.

The incidence of tuberculosis is rising in the United States. Similarly, the incidence of pulmonary tuberculosis in Taiwan is increasing, but that of large bowel tuberculosis in this region has not been reported. The purpose of this study was to investigate the changing disease pattern and to determine some possible surgical prognostic factors for large bowel tuberculosis. Seventy cases of large bowel tuberculosis treated at our institute during the period 1965-1995 were reviewed and analyzed. A steady decline in the case number of large bowel tuberculosis were noted from 1975, but there seems to be a slight increase in cases since 1990. The average age of these patients was 65.1 years, and none had human immunodeficiency virus infection. The ileocecum is the most common region of involvement. Of these 70 patients, 59 had not been definitively diagnosed until surgery. Active pulmonary tuberculosis was found in 18 patients (25.7%). The incidence of postoperative pulmonary complications was higher in patients with active pulmonary tuberculosis or disseminating large bowel tuberculosis. Postoperative abdominal complications, including intestinal obstruction, abdominal cutaneous fistula, and wound infection, were seen in 13 patients, none of whom had active pulmonary tuberculosis. Although the incidence of tuberculosis has been reduced for years, it is now rising. Physicians should bear in mind the possibility of large bowel tuberculosis in patients with intestinal obstruction without specific origin. Postoperative respiratory care is important for patients with pulmonary tuberculosis, with either active or disseminating lesions.

Adolescent↗

PubMed1997

Factors predictive of response and survival in patients with metastatic colorectal cancer in Taiwan.

5-Fluorouracil in combination with leucovorin has been shown to be active in therapeutic trials of metastatic colorectal carcinoma. In this study, we administered these drugs to 72 patients with metastatic colorectal carcinoma. Thirty-six of them without previous exposure to 5-fluorouracil were treated with weekly bolus injections of 5-fluorouracil (425 mg/m2) and leucovorin (25 mg/m2) supplemented with oral levamisole. Another 36 patients with or without prior 5-fluorouracil treatment received 5-fluorouracil 3,000 mg/m2 and leucovorin 300 mg/m2 in a 48-hour continuous infusion every two weeks. Clinical efficacy and toxicity were assessed by WHO criteria. Variables were tested for relations to response and survival by univariate and multivariate analysis. The response rate was 19.4% in weekly bolus arm and 13.9% in biweekly high-dose infusion arm (P = 0.527). Median survivals in the two arms were 18.4 months (weekly) and 21 months (biweekly) respectively (P = 0.708). Gastrointestinal side effects including nausea, vomiting, diarrhea and mucositia were the major toxicities of these regimens. By multivariate analysis, the only factor to influence response rate was the site of metastases (P = 0.009). The only factor to affect survival was performance status of the patient (P = 0.0001). We concluded that the two 5-fluorouracil based regimens are well-tolerated and shown to have a response rate comparable with previous reports of similar regimens in patients with metastatic colorectal cancer. Only liver metastases seemed to have a better response to therapy. Performance status is the most important prognostic factor in patients with metastatic colorectal cancer.

Adjuvants, Immunologic↗

PubMed1997

Enterovesical fistula: 10 years experience.

BACKGROUND: Enterovesical fistula is a relatively uncommon complication of pelvic malignancies, diverticulitis of the colon, postoperative irradiation or trauma. Early diagnosis of enterovesical fistula is difficult and its management, complicated. The main purpose of this study is to investigate the most appropriate diagnostic method and to discuss the choice among different surgical managements. METHODS: From 1986 to 1995, 30 patients with enterovesical fistula were diagnosed and treated at Veterans General Hospital-Taipei. The records were reviewed retrospectively with regard to symptoms, primary disease process, diagnostic studies, management, complications, mortality and follow-up. RESULTS: Recurrent urinary tract infection (UTI) accounted for 73% and was the most common presenting symptom. Fecaluria (43%) and urine per rectum (40%) were another two common presenting symptoms. The major cause of these cases was malignancy (36%), followed by postoperative radiotherapy (17%) and iatrogenic injury (17%). Most of these cases were diagnosed by cystography (90%), barium enema (75%) or cystoscopy (69%). The rectum (52%) was the most common site involved, followed by the sigmoid colon (39%). The surgical management was individualized for each patient according to the general condition and the disease process. CONCLUSIONS: By combining the results of cystography, barium enema and cystoscopy, diagnosis of enterovesical fistula can be established in almost all cases. Single-stage operation for enterovesical fistula should be limited to those patients in good nutritional state and without severe inflammation, radiation injury, intestinal obstruction, other major medical problem, advanced malignancy or old age.

Adult↗

PubMed1996

Functional consequences and exonuclease kinetic parameters of point mutations in bacteriophage T4 DNA polymerase.

Three groups of T4 DNA polymerase mutants were prepared and characterized. In the first group, Ala and Asn were substituted for four acidic residues in the exonuclease domain that were chosen on the basis of their sequence alignment with the Klenow fragment from Escherichia coli DNA polymerase I. Two divalent metal ions required for catalyzing the 3'-5' exonuclease reaction are ligated by carboxyl groups from these conserved Asp and Glu residues. The Ala and Asn replacements have a profound effect on the exonuclease activity of T4 DNA polymerase and also have a significant, but less pronounced influence on its polymerase activity which is located in a domain distal to the exonuclease region. The kcat values for the exonuclease reaction were reduced by 3-4 orders of magnitude by these replacements, but the values of Km(app) did not differ greatly from the wild-type enzyme. The second group consists of replacements of other residues, that are conserved in the exonuclease domain of eukaryotic DNA polymerases, but do not contribute to divalent metal ion coordination. Many of these alterations resulted in decreased exonuclease and/or polymerase activity. Mutants in the third group have substitutions of conserved residues in the polymerase domain which diminished polymerase and altered exonuclease activities. Our results, combined with structural data on crystals of protein N388, a truncated form of T4 DNA polymerase (Wang et al., 1996), show that: (i) the reduction in the relative specific exonuclease activities of mutants in the first group was significantly less than that of mutants in the Klenow fragment, despite the nearly identical geometric arrangement of the metal liganding groups in two proteins; (ii) altered residues, that affect exonuclease and/or polymerase activities in mutants of the second group, cluster within a small area of the exonuclease domain, suggesting that this area may be directly or indirectly involved in polymerase activity; (iii) mutations in the third group, which affect polymerase and exonuclease activities, may participate in DNA and dNTP binding. Our results point to the functional interdependence of the polymerase and exonuclease domains in T4 DNA polymerase, a property not observed with the Klenow fragment.

Amino Acid Sequence↗

PubMed1996

Crystal structures of an NH2-terminal fragment of T4 DNA polymerase and its complexes with single-stranded DNA and with divalent metal ions.

We report the crystal structure of an NH2-terminal 388-residue fragment of T4 DNA polymerase (protein N388) refined at 2.2 A resolution. This fragment contains both the 3'-5' exonuclease active site and part of the autologous mRNA binding site (J. D. Karam, personal communication). The structure of a complex between the apoprotein N388 and a substrate, p(dT)3, has been refined at 2.5 A resolution to a crystallographic R-factor of 18.7%. Two divalent metal ion cofactors, Zn(II) and Mn(II), have been located in crystals of protein N388 which had been soaked in solutions containing Zn(II), Mn(II), or both. The structure of the 3'-5' exonuclease domain of protein N388 closely resembles the corresponding region in the Klenow fragment despite minimal sequence identity. The side chains of four carboxylate residues that serve as ligands for the two metal ions required for catalysis are located in geometrically equivalent positions in both proteins with a rms deviation of 0.87 A. There are two main differences between the 3'-5' exonuclease active site regions of the two proteins: (I) the OH of Tyr-497 in the Klenow fragment interacts with the scissile phosphate in the active site whereas the OH of the equivalent tyrosine (Tyr-320) in protein N388 points away from the active center; (II) different residues form of the binding pocket for the 3'-terminal bases of the substrate. In the protein N388 complex the 3'-terminal base of p(dT)3 is rotated approximately 60 degrees relative to the position that the corresponding base occupies in the p(dT)3 complex with the Klenow fragment. Finally, a separate domain (residues 1-96) of protein N388 may be involved in mRNA binding that results in translational regulation of T4 DNA polymerase (Pavlov & Karam, 1994).

Amino Acid Sequence↗

PubMed1996

Central serotonergic lesions increase voluntary alcohol consumption in Sprague Dawley rats: moderation by long-term ethanol administration.

The relationship between central serotonergic activities and voluntary alcohol consumption was studied in Sprague-Dawley rats, which normally have low alcohol preference. After initial screening for an evenly matched baseline alcohol preference, selective central serotonergic lesioning was induced by intracisternal injection of the serotonergic neurotoxin 5,7-dihydroxytryptamine (5,7-DHT). Control rats received injections of vehicle only. Both 5,7-DHT and vehicle-treated rats were further divided into two subgroups, which either had continued free access to ethanol (alcohol-drinking) or were deprived of it (alcohol-free). All rats were then tested again for alcohol preference. All rats were then killed, and the levels of monoamines in the brains were determined by high performance liquid chromatography with electrochemical detection. Behavioral results indicated that all 5,7-DHT-treated rats had significantly higher alcohol preference and consumption than the corresponding sham controls. Except in the cerebellum, the 5,7-DHT-treated rats had significantly lower levels of serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in most brain regions compared with those in the corresponding sham controls. Treatment with 5,7-DHT also resulted in a decrease in serotonin turnover in all brain regions in the alcohol-free rats, except in the cerebellum. In alcohol-drinking rats, however, 5,7-DHT treatment only reduced serotonin turnover in the pons. The levels of norepinephrine and dopamine in several brain regions were not significantly different. Thus, it appeared that in the Sprague Dawley rats, 5,7-DHT treatment depleted 5-HT and 5-HIAA levels in most brain regions while increasing alcohol consumption. Chronic alcohol-drinking attenuated the increase in alcohol consumption associated with serotonergic lesions. Voluntary alcohol consumption seemed more associated with 5-HT turnover than with tissue 5-HT levels. Our data also suggested that tolerance to alcohol-induced hypothermia was primarily attributable to long-term alcohol drinking rather than serotonergic lesioning.

Alcohol Drinking↗

PubMed1996

Leiomyosarcoma of the rectum: a series of twelve cases.

BACKGROUND: Leiomyosarcoma of the rectum is a rare disease without well-documented report on its management and prognosis in Taiwan. To evaluate the effectiveness and prognosis of different treatments for rectal leiomyosarcoma, we reviewed a series of 12 patients with rectal leiomyosarcoma treated at our hospital. METHODS: This study is a retrospective review of 12 rectal leiomyosarcomas treated at VGH-Taipei from 1976 to 1995, with emphasis on symptoms, therapeutic procedures and prognosis. RESULTS: The majority of tumors occurred in men (n = 10) and the average age at presentation was 54.4 years. Bloody stool and perianal pain were the two most common symptoms. Nine tumors were found in the lower rectum, within 4 cm above the dentate line. Five patients received abdominoperineal resection, four received wide local excision, and three had diversion colostomy. The effect of adjuvant therapy, either chemo- or radiotherapy, was poor. The overall one-year and five-year survival rates were 83% and 46%, respectively. Liver was the principal metastatic site. The local recurrence rate was much higher in patients receiving wide local excision than in those receiving abdominoperineal resection (100% vs. 20%). CONCLUSIONS: Abdominoperineal resection is an appropriate choice of treatment for patients with operable rectal leiomyosarcoma due to its lower local recurrence rate. Wide local excision could be considered when the lesion is less than 2 cm in diameter or when patients are not suitable for radical surgery. The effect of adjuvant therapy, either radiotherapy or chemotherapy, is poor for rectal leiomyosarcoma.

Adult↗

PubMed1996

Microscopic FT-IR/DSC system used to simultaneously investigate the conversion process of protein structure in porcine stratum corneum after pretreatment with skin penetration enhancers.

A newly developed microscopic Fourier transform infrared (FT-IR) spectrometry combined with differential scanning calorimetry (DSC) was used to investigate the thermal response and IR spectral changes of protein structure in porcine stratum corneum (SC) after pretreatment with the skin penetration enhancers propylene glycol (PG), azone/PG, oleic acid (OA)/PG, vitamin C, and vitamin C+ OA/PG. The amide I and II bands of protein were used as probe to determine the structural transformation of protein with temperature. A reheating process was also performed. Dual effects of enhancer and temperature on the protein conformational changes of porcine SC were studied. The results indicate that the new FT-IR/DSC system can continuously determine the thermoresponsive conversion process from alpha-helix to beta-sheet in keratin structure of porcine SC pretreated with different enhancers. The thermally induced keratin conversion in protein structure of porcine SC, independent of pretreatment with skin penetration enhancers, was irreversible. The process of conformational transition in protein was found to be partially from alpha-helix to random coil structure or partially from alpha-helix to beta-sheet structure during heating. The kinetics of this conversion between first-heating and second-heating processes were significantly different; the process of conversion for all first-heated porcine SC samples during second-heating process were slower than that of porcine SC samples during first-heating process. Moreover, it was also found that the skin penetration enhancers, when present during the heating process, were able to synergistically and promotively alter the keratin conversion in protein structure of porcine SC, with the PG, OA/PG and azone/PG enhancers being the most effective.

Animals↗

PubMed1996

Premedication with diclofenac and prednisolone to prevent postoperative pain and swelling after third molar removal.

BACKGROUND: Nonsteroidal anti-inflammatory drugs (NSAIDs) and steroid are able to effectively reduce the postoperative sequelae after impacted third molar removal. However, few studies have evaluated the activity of the combined effects of these two drugs. The purpose of this study was to evaluate whether a single dose of prednisolone, taken orally before operation, would increase the effects of diclofenac in preventing pain and swelling after surgical removal of impacted third molars. METHODS: Thirty healthy patients requiring surgical removal of four third molars were randomly assigned to two groups. In group A, patients were preoperatively given 50 mg of either diclofenac or placebo when impacted teeth were removed on each side. In group B, in addition to 50 mg of diclofenac, 10 mg of prednisolone or placebo was administered. Postoperative pain, swelling and range of mouth opening were recorded. RESULTS: Preoperative administration of 50 mg of diclofenac could relieve pain and swelling more than the placebo. Additional 10 mg of prednisolone could further reduce swelling. CONCLUSIONS: The combination of diclofenac and prednisolone has a better analgesic and anti-inflammatory effect.

Adult↗

PubMed1996

Activation of factor X by factor VIIa complexed with human-mouse tissue factor chimeras requires human exon 3.

In an attempt to define sequence elements in human and mouse tissue factor (TF) that are responsible for the species specificity observed in their interaction with human factor VIIa (HVIIa), we constructed human-mouse chimeric TF cDNAs, inserted them into plasmid vectors, and induced their expression in E. coli. Assays for procoagulant activity were carried out with the resulting E. coli lysates using (HVIIa) human and mouse (MVIIa). The ratio of the procoagulant activities, HVIIa/MVIIa, revealed that human TF exon 3 was essential for activity when the TF:VIIa complex was formed with HVIIa. By ligating the maltose binding protein (MBP) gene to TF cDNAs it was possible to construct, express and purify MBP-TF chimeras as well as to estimate their specific activities. With selected MBP-TF chimeras and HVIIa we determined kinetic parameters for the activation of human factor X. Replacement of exon 3 in human TF cDNA with the corresponding exon from mouse TF cDNA resulted in both lower affinity for HVIIa and failure to convert bound HVIIa into a potent protease.

Amino Acid Sequence↗

PubMed1996

Hirschsprung's disease manifested with obstructive colitis in adult: a case report.

Hirschsprung's disease rarely occurs in adult. If it occurs, the symptoms and signs are usually milder than those in children and manifest in form of chronic or intermittent constipation. Definite surgical intervention could be performed with good results. We reported a 36-year-old male adult with Hirschsprung's disease who manifested as obstructive colitis. The clinical course presented as abdominal fullness and pain, and colonoscopy revealed ulcerations and pseudopolyps formation in the sigmoid colon and rectum. Ganglion was absent in transanal rectal biopsy. Soave's procedure with protective ileostomy was done. Patient's bowel movements turned normal after closure of ileostomy three months later. The literature was also reviewed.

Adult↗

PubMed1995

Environments of the four tryptophans in the extracellular domain of human tissue factor: comparison of results from absorption and fluorescence difference spectra of tryptophan replacement mutants with the crystal structure of the wild-type protein.

The local environments of the four tryptophan residues of the extracellular domain of human tissue factor (sTF) were assessed from difference absorption and fluorescence spectra. The difference spectra were derived by subtracting spectra from single Trp-to-Phe or Trp-to-Tyr replacement mutants from the corresponding spectrum of the wild-type protein. Each of the mutants was capable of enhancing the proteolytic activity of factor VIIa showing that the mutations did not introduce major structural changes, although the mutants were more susceptible to denaturation by guanidinium chloride. The difference spectra indicate that the Trp residues are buried to different extents within the protein matrix. This evaluation was compared with the x-ray crystal structure of sTF. There is excellent agreement between predictions from the difference spectra and the environments of the Trp residues observed in the x-ray crystal structure, demonstrating that difference absorption and particularly fluorescence spectra derived from functional single-Trp replacement mutants can be used to obtain information about the local environments of individual Trp residues in multi-tryptophan proteins.

Base Sequence↗

PubMed1995

Five new pregnane glycosides from Cynanchum taiwanianum.

Five new pregnane glycosides, taiwanosides A [1], B [2], C [3], D [4], and E [5], together with wilfosides C1N [6], C2N [7], M1N [8], and K1N [9], were isolated from the roots of Cynanchum taiwanianum. Their structures were determined on the basis of spectroscopic and chemical evidence.

Acetylation↗

PubMed1995

Antihypertensive effect of corilagin in the rat.

The antihypertensive effect of corilagin, one of the ellagitannins purified from the seeds of Euphoria longana Lam. (Sapindaceae), was investigated in the spontaneously hypertensive rat (SHR). Administration of corilagin into conscious SHR at 5 mg/kg produced an antihypertensive effect equivalent to that induced by 1 mg/kg of guanethidine. This dose-dependent hypotensive effect was comparable with that observed in anesthetized SHR animals. Corilagin did not modify the baroreflex sensitivity in phenylephrine-challenged SHR. Corilagin reduced plasma noradrenaline in a dose-dependent fashion, an effect that was maintained in adrenalectomized rats. Failure of the antagonists for alpha2-adrenoceptors, idazoxan and yohimbine, as well as for dopamine receptors, haloperidol and domperidone, to reverse the antihypertensive actions of corilagin ruled out the participation of these receptors. Moreover, corilagin attenuated the pressor effects of methoxamine and Bay K8644 to a similar degree, indicating the direct effect of corilagin on vascular activity in rats. These results suggest that corilagin possesses the ability to lower blood pressure through the reduction of noradrenaline release and (or) direct vasorelaxation.

Adrenergic alpha-Antagonists↗

PubMed1995

Direct or indirect skin lipid-ordering effect of pyrrolidone carboxylate sodium after topical treatment with penetration enhancers.

The structural changes in the lipid of the excised skin of nude mice and the porcine stratum corneum was investigated by in vitro treatment with vitamin C, oleic acid, or DMSO. The CH2 stretching vibrational peaks of lipid near 2920 cm-1 (asymmetric) and 2850 cm-1 (symmetric) shifted to higher wavenumber due to the lipid-disorder after in vitro treatment with above enhancers. The spectral shift of the asymmetric CH2 band was more sensitive than that of the symmetric CH2 band. The higher wavenumber of CH2 stretching bands decreased gradually to the lower region after co-treatment or posttreatment with pyrrolidone carboxylate sodium (PCA Na). Such a decrease was dependent on the PCA Na concentration and the time of treatment. The higher the concentration of PCA Na used, the lower value of the permeability coefficient of vitamin C through the excised skin and the downward spectral shift of asymmetric CH2 band were obtained. When PCA Na coexisted with vitamin C in the cell donor compartment, a competitive effect between PCA Na and vitamin C was found. The oleic acid was supposed to directly insert it into the lipid structure to form a rigid structure, leading to larger spectral shift of both stretching bands but lesser restoring ability after PCA Na treatment. However, DMSO only displaces water from the lipid head groups and protein domain of skin to indirectly loosen the lipid structure, resulting in lesser spectral shift of the CH2 stretching bands to higher region, which was easier and better restoration after PCA Na application. The PCA Na enabled to restore the disordered lipid structure to order state might be attributed to PCA Na previously penetrated into skin and then absorbed water to directly or indirectly rearrange the disordered lipid bilayer structure.

Absorption↗

PubMed1995

Comparative effects of strophanthidin in tilapia and human heart tissues.

It is well documented that the cardiotonic steroid strophanthidin increases myocardial contractile force through an inhibition of the sarcolemmal Na(+)-K+ pump in mammalian heart cells. The aim of the present study was to determine the effect of this digitalis substance on action potential and contraction in cardiac tissues obtained from a cultured freshwater fish tilapia (Oreochromis sp.) and compare with those observed in human heart tissues obtained at cardiac surgery. In tilapia atria superfused at 25 degrees C 1-2 microM strophanthidin shortened the spontaneous cycle length while increased progressively the twitch force. In tilapia ventricular tissues, strophanthidin also increased the force but shortened the APD50. When temperature of the superfusate was elevated from 25 to 37 degrees C, strophanthidin induced a smaller positive or even negative inotropic effect but increased significantly the diastolic tension through an inhibition of the relaxation process. High temperature also facilitated the occurrence of delayed afterdepolarizations, repetitive slow response action potentials and episodes of contracture. The same concentration of stroph induced rather sustained positive inotropic effects without deteriorating actions in human ventricular trabeculae driven at 37 degrees C. In human atrial trabeculae, however, 2 microM strophanthidin readily induced abnormal automatic and triggered rhythms along with the positive inotropy. The present findings provide the functional evidence for the presence of sarcolemmal Na+, K(+)-pump in fish myocardial fibers. The major differences in the electro-mechanical actions of strophanthidin in tilapia versus human heart tissues are the smaller positive inotropy and the proneness to contracture in tilapia heart at 37 degrees C.

Action Potentials↗