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Biomedical subjects

W C Ko

Publications and source records attributed to W C Ko.

At least 55 records · Page 3Linked to original sources
PubMed1998

The selective antianginal effect without changing blood pressure of butylidenephthalide in conscious rats.

Synthetic butylidenephthalide (Bdph), 60 mg/kg per os (p.o.) given 3 h prior to injection of pituitrin (4 U/kg, i.v.), significantly prevented T-wave lowering on lead II electrocardiograph in unanesthetized rats. The effective dose, 60 mg/kg, was about 1/56th of the median lethal dose (LD50, p.o.) in rats. However, Bdph (60 mg/kg, p.o.) did not affect systolic pressure and heart rate in unanesthetized rats. Therefore, Bdph, found in the rhizome of Ligusticum chuaxiong Hort. (L. wallichii Franch., Umbelliferae), appears to have selective antianginal effect without changing blood pressure and heart rate.

Angina Pectoris↗
PubMed1998

Infections due to non-O1 Vibrio cholerae in southern Taiwan: predominance in cirrhotic patients.

Although Taiwan is not an area where cholera is endemic, from October 1988 to October 1997 30 episodes of non-O1, non-O139 Vibrio cholerae infection were noted at the National Cheng Kung University Hospital in Taiwan. Infections generally occurred in hot seasons, and two episodes were concomitant with Vibrio vulnificus infection. Three major clinical presentations were found: bacteremia with concurrent spontaneous bacterial peritonitis or invasive soft-tissue infections that occurred solely in cirrhotic patients; self-limited acute febrile gastroenteritis that occurred in patients with no underlying medical disease; and necrotizing fasciitis or cellulitis that often resulted from a wound on extremities. Other manifestations included fatal pneumonitis in a drowned man and acute pyosalpinx. The differential diagnosis of invasive infections in cirrhotic patients should include infections due to non-O1 V. cholerae or V. vulnificus, and a third-generation cephalosporin and a tetracycline analogue or a fluoroquinolone alone is recommended for treatment of severe vibrio infections.

Acute Disease↗
PubMed1998

Suppurative Acinetobacter baumanii thyroiditis with bacteremic pneumonia: case report and review.

Suppurative thyroiditis is rare, and the major pathogens are Staphylococcus and Streptococcus species. We present a case caused by Acinetobacter baumanii, which has never before been reported. We review another 191 cases from the English-language literature (1980 to April 1997) and make a comparison with a review of 224 cases (1900-1980). As the numbers of immunocompromised patients increase, cases of suppurative thyroiditis are increasing. Pneumocystis carinii has become an important pathogen. Most patients (83.1%) with bacterial infections were euthyroid, whereas those with fungal or mycobacterial infections tended to be hypothyroid (62.5%) and hyperthyroid (50%), respectively.

Acinetobacter↗
PubMed1998

Clinical, electrophysiological characteristics, and radiofrequency catheter ablation of atrial tachycardia near the apex of Koch's triangle.

Atrial tachycardia, with its focus near the apex of Koch's triangle, may carry a potential risk of atrioventricular block during radiofrequency catheter ablation. The efficacy and safety of this procedure have never been addressed. The characteristics and catheter ablation results are reported for six patients with atrial tachycardia near the apex of Koch's triangle. All six patients were female aged 49.6 +/- 9.3 years (range 39-63). Organic heart disease was present in 3 (50%) of the 6 patients. The P wave in surface ECG had a mean axis of -28 degrees (range -90 degrees - +30 degrees) in the frontal plane. The catheter ablation was guided by activation sequence mapping. The energy was titrated from low power level. Atrial overdrive pacing was used to monitor the atrioventricular conduction should accelerated junctional rhythm occur. At the final successful ablation site, the local atrial activation was 41.8 +/- 9.1 ms before the P wave and His-bundle potential was present in 5 of the 6 patients. All patients had their atrial tachycardia eliminated without recurrence or heart block during a follow-up period of 17.7 +/- 8.5 months (range 6-30). In conclusion, atrial tachycardia near the apex of Koch's triangle has distinct clinical and electrophysiological features. Radiofrequency catheter ablation can be performed effectively. However, extreme care must be taken to prevent inadvertent atrioventricular block. Titrated energy application and continuous monitoring of atrioventricular conduction are mandatory.

Adult↗
PubMed1998

Effect of butylidenephthalide on calcium mobilization in isolated rat aorta.

Butylidenephthalide (Bdph), an antispasmodic compound originally isolated from the rhizome of Ligusticum chuaxiong, has a selective anti-anginal effect without changing blood pressure. Experiments have been performed to determine the mechanism of this action. Synthetic Z-butylidenephthalide concentration-dependently relaxed phenylephrine (1 microM)- or KCl (60 mM)-induced precontractions of intact and denuded rat aorta rings. The relaxation induced by Bdph was endothelium-independent. Bdph (30-300 microM) concentration-dependently reduced cumulative phenylephrine- and KCl-induced contractions of intact rat aortic rings and non-competitively inhibited their log concentration-response curves. The pD2' values of Bdph for phenylephrine- and KCl-induced contraction were 3.66+/-0.13 (n = 8) and 3.71+/-0.07 (n = 8), respectively, which were not significantly different from each other. Bdph also concentration-dependently reduced cumulative Ca2+-induced contractions of intact rat aortic rings in high-KCl (60 mM) Ca2+-free physiological salt solution and non-competitively inhibited its log concentration-response curve. The pD2' value of Bdph for the Ca2+-induced contractions was 3.21+/-0.01 (n = 7) which was significantly different from the pD2' value obtained from the cumulative KCl-induced contractions. These results suggest that Bdph inhibits calcium release from calcium stores more selectively than calcium influx from extracellular space via voltage-dependent calcium channels. The inhibition by Bdph of calcium release from KCl-sensitive calcium stores might be similar to its inhibition of calcium release from phenylephrine-sensitive calcium stores. However, because phenylephrine generates inositol-1,4,5-trisphosphate (IP3) whereas KCl does not, the inhibitory effect of Bdph might not be related to IP3 production.

Animals↗
PubMed1998

Minocycline and cefotaxime in the treatment of experimental murine Vibrio vulnificus infection.

We conducted an in vivo study with the mouse model of Vibrio vulnificus infection to evaluate the efficacies of therapy with minocycline or cefotaxime alone and in combination. V. vulnificus was introduced subcutaneously into the area over the right thigh. The inoculum size ranged from 1.0 x 10(3) to 1.2 x 10(8) CFU from experiment to experiment but was constant for all animals in the same experiment. Antibiotics were given intraperitoneally 2 h after the bacteria were inoculated. In experiments 1 to 4, the standard dose for humans was used to treat the infection, while in experiment 5, five times the standard dose for humans was used to treat the infection. In experiment 1, with a small inoculum of 5 x 10(3) CFU, all mice in the saline-treated control group and the cefotaxime-, minocycline-, and combined antibiotic-treated groups survived. In experiment 2, with a moderate inoculum of 1.2 x 10(5) CFU, all the mice in the three antibiotic-treated groups survived, while only two of nine mice in the control group survived. In experiment 3, with a large inoculum of 8.0 x 10(7) CFU, six of nine mice in the combined antibiotic-treated group survived, while only one of nine mice in the cefotaxime-treated group and none of the mice in the control and minocycline-treated groups survived. In experiment 4, with a large inoculum of 1.2 x 10(8) CFU, 8 of 20 mice in the combined antibiotic-treated group survived, while none of the 20 mice in the control group, the group treated with cefotaxime alone, and the group treated with minocycline alone survived. In experiment 5, in which mice were infected with a large inoculum of 6.6 x 10(7) CFU and treated with five times the standard human dose of antibiotics, 10 of 12 mice in the combined antibiotic-treated group survived, while only 4 of 12 mice in the minocycline-treated group, 1 of 12 mice in the cefotaxime-treated group, and none of the mice in the control group survived. In experiments 3 to 5, the difference in the survival rates between the combined antibiotic-treated and minocycline-treated groups was statistically significant (P < 0.05). These results indicate that combination therapy with cefotaxime and minocycline is distinctly more advantageous than therapy with the single antibiotic regimen for the treatment of severe experimental V. vulnificus infections.

Animals↗
PubMed1998

Inducible beta-lactam resistance in Aeromonas hydrophila: therapeutic challenge for antimicrobial therapy.

Despite the abundant amount of knowledge about inducible chromosomally mediated beta-lactamases among Aeromonas species, extended-spectrum beta-lactam-resistant A. hydrophila strains selected in clinical practice were rarely reported. In the present study, two strains of A. hydrophila, A136 and A139, with markedly different susceptibilities to extended-spectrum cephalosporins were isolated from blood and the tip segment of an arterial catheter of a burn patient. Another strain (A136m) was selected in vitro by culturing A136 in a subinhibitory concentration of cefotaxime, the beta-lactam agent administered for the treatment of Aeromonas bacteremia in this patient. Typing studies by arbitrarily primed PCR and pulsed-field gel electrophoresis indicated a clonal relationship among strains A136, A136m, and A139. These strains were identified to be of DNA hybridization group 1. Wild-type strain A136 was resistant only to ampicillin and cephamycins, but A136m and A139 were highly resistant to the expanded- and broad-spectrum cephalosporins. The presence of increased beta-lactamase activity in A139 suggests that A139 is a derepressed mutant which overexpresses beta-lactamases. These results call attention to the use of beta-lactam agents for the treatment of invasive Aeromonas infections.

Aeromonas hydrophila↗
PubMed1998

Premaxillary size and craniofacial growth in patients with cleft lip and palate.

BACKGROUND: Premaxillary size in individuals with cleft lip and palate is variable, ranging from a mere nubbin to a large protuberance. The purpose of this study was to evaluate the effect of premaxillary size on craniofacial growth in cleft lip and palate patients. MATERIALS AND METHODS: Premaxillary size was measured using 181 dental casts of bilateral complete cleft lip and palate (BCLP) infants. The infants had no associated systemic malformations, and were approximately one year of age. Data were obtained from the files of the Chang Gung Craniofacial Center. The mean size (mean = 19.3 mm) of the premaxilla and standard deviation (SD = 2.0 mm) were calculated. A sample of 55 subjects was divided into three groups: large premaxilla; [LP; 15 boys, 5 girls; mean age 5.2 years; premaxillary size > (19.3 + 2.0) mm; mean size 22.6 mm]; small premaxilla [SP; 15 boys, 5 girls; mean age = 5.1 years; premaxillary size < (19.3-2.0) mm; mean size = 16.5 mm] and bilateral-median facial dysplasia [B-MFD; 6 boys, 9 girls; mean age 5.1 years; mean size 10.5 mm]. They all had a bilateral cheiloplasty at about 3 months of age and palatoplasty at about one year of age. Lateral cephalograms were taken at about 5 years of age to compare the craniofacial complex among the three groups. RESULTS: The LP group tended to have a longer maxilla, longer anterior maxillary height and more protruded maxilla, producing a better interjaw relation and larger overjet. The opposite phenomena were observed in the B-MFD group, and the SP group had results between those of the LP group and the B-MFD group. CONCLUSION: BCLP patients with large premaxilla had superior maxillary growth (in depth and anterior height) as compared to those with small premaxilla.

Child↗
PubMed1997

Mechanisms involved in the antiplatelet activity of tetramethylpyrazine in human platelets.

Tetramethylpyrazine is the active ingredient of a Chinese herbal medicine. In this study, tetramethylpyrazine was tested for its antiplatelet activities in human platelet suspensions. In human platelets, tetramethylpyrazine (0.5-1.5 mM) dose-dependently inhibited both platelet aggregation and ATP-release reaction induced by a variety of agonists (i.e., ADP, collagen, and U46619). Tetramethylpyrazine (0.5 mM) did not significantly change the fluorescence of platelet membranes labeled with diphenylhexatriene, even at the high concentration (1.5 mM). Furthermore, tetramethylpyrazine (0.5-1.5 mM) dose-dependently inhibited [3H]inositol monophosphate formation stimulated by collagen (5 microg/ml) in [3H]myoinositol loaded platelets. Tetramethylpyrazine (0.5-1.5 mM) also dose-dependently inhibited the intracellular free Ca2+ rise of Fura 2-AM loaded platelets stimulated by collagen (5 microg/ml). Moreover, tetramethylpyrazine (0.5-1.5 mM) inhibited thromboxane B2 formation stimulated by collagen. At a higher concentration (1.0 mM), tetramethylpyrazine has also been shown to influence the binding of FITC-triflavin to platelet glycoprotein IIb/IIIa complex. Triflavin, a specific glycoprotein IIb/IIIa complex antagonist purified from Trimeresurus flavoviridis venom. It is concluded that the antiplatelet activity of tetramethylpyrazine may possibly involve two pathways: 1) at a lower concentration (0.5 mM), tetramethylpyrazine is shown to inhibit phosphoinositide breakdown and thromboxane A2 formation; and 2) at a higher concentration (1.0 mM), it leads to the inhibition of platelet aggregation through binding to the glycoprotein IIb/IIIa complex.

Blood Platelets↗
PubMed1997

Stereoselectivity of butylidenephthalide on voltage-dependent calcium channels in guinea-pig isolated ileum.

Two geometric isomers, the Z- and the E- forms, can be separated from synthetic mixtures of butylidenephthalide (Bdph). Z-Bdph (50-100 microM) non-competitively inhibited Ca(2+)-induced contractions in depolarized (K+, 60 mM) guinea-pig ileum longitudinal smooth muscle, with a pD2' value of 3.88 +/- 0.20 (n = 5). However, E-Bdph (20-100 microM) competitively inhibited these contractions with a pA2 value of 4.56 +/- 0.18 (n = 5) which was significantly (P < 0.05) greater than the pD2' value of Z-Bdph. In contrast, the two isomers had no stereoselective inhibitory action on Ca2+ influx through pre- or post-junctional membranes of cholinergic nerve endings from which the transmitter acetylcholine is released or on Ca2+ release from intracellular stores. Therefore, the trans-Z and cis-E forms of Bdph might have geometric stereoselectivity for voltage-dependent calcium channels (VDC) in guinea-pig longitudinal smooth muscle. Both isomers might inhibit more selectively the contractile twitch responses evoked by electrical stimulation than by cumulative acetylcholine- or carbachol-induced transient contractions in guinea-pig ileum longitudinal smooth muscle.

Animals↗
PubMed1997

Interaction of thrombin-activated platelets with extracellular matrices (fibronectin and vitronectin): comparison of the activity of Arg-Gly-Asp-containing venom peptides and monoclonal antibodies against glycoprotein IIb/IIIa complex.

Platelets adhere to fibronectin and vitronectin substrates following activation with physiological concentrations of thrombin. Adhesion of activated-platelets to either substrate is dependent upon the amount of fibronectin and vitronectin, and the duration of the adhesion assay. In this study, we showed that the Arg-Gly-Asp-containing peptides (including naturally occurring polypeptides, triflavin, trigramin and rhodostomin, synthetic peptides GRGDS, GRGDSPK, GRGDF, and GRGD and monoclonal antibodies, 7E3, 10E5 and AP2, raised against glycoprotein IIb/IIIa complex, inhibited the adhesion of activated-platelets to fibronectin and vitronectin-coated plates in a dose-dependent manner. In fibronectin-coated plates, GRGDF was shown to be much more efficient than GRGDS, GRGDSPK and GRGD at inhibiting the adhesion of activated-platelets to immobilized fibronectin. On the other hand, there were no marked differences in the abilities of these three peptides (GRGDF, GRGDS and GRGDSPK) to inhibit platelet adhesion to immobilized vitronectin. Furthermore, the RGD-containing venom peptide, triflavin was more effective than rhodostomin and trigramin at inhibiting the adhesion of activated-platelets to either substrates. The monoclonal antibodies raised against glycoprotein IIb/IIIa complex (i.e., 7E3, 10E5 and AP2) inhibited platelet adhesion to fibronectin and vitronectin in a similar dose-dependent manner. Interestingly, we found that 7E3 was more efficient than 10E5 and AP2 in this reaction. These studies suggest that the glycoprotein IIb/IIIa complex, present on activated-platelets, may interact with fibronectin and vitronectin substrates through the Arg-Gly-Asp-dependent mechanism. Since fibronectin and vitronectin are present in the subendothelial matrix, they may be involved in platelet-vessel wall interaction. The Arg-Gly-Asp containing peptide, especially triflavin, is an ideal therapeutic agent for inhibiting thrombus formation by interrupting platelet-platelet and platelet-subendothelium interactions.

Antibodies, Monoclonal↗
PubMed1997

In vitro synergism between cefotaxime and minocycline against Vibrio vulnificus.

We conducted time-kill studies to evaluate the inhibitory activities of either cefotaxime or minocycline alone and the two drugs in combination against a clinical strain of Vibrio vulnificus. The MICs of cefotaxime and minocycline were 0.03 and 0.06 microg/ml, respectively. When approximately 5 x 10(5) CFU of V. vulnificus per ml was incubated with cefotaxime at 0.03 or 0.05 microg/ml, the bacterial growth was inhibited during the initial 2 and 8 h, respectively. Thereafter, V. vulnificus regrew and the level of growth reached that of the control. Within the dose range of less than five times the MIC, the duration of the inhibitory effect of cefotaxime was proportional to its concentration. When minocycline at 0.015, 0.03, 0.045, and 0.06 microg/ml was used to evaluate the inhibitory effect, a similar trend was observed. Either antibiotic at a concentration of five times the MIC or greater prevented the regrowth of V. vulnificus for at least 48 h. When cefotaxime at 0.05 microg/ml and minocycline at 0.045 microg/ml were combined in the same culture, the inhibitory effect against V. vulnificus persisted for more than 48 h, with no regrowth noted. The use of a combination of these two antibiotics resulted in the reduction of growth by 6 orders of magnitude compared to the use of either of the two antibiotics alone, and the number of surviving organisms in the presence of the antibiotics combined was approximately 3 orders of magnitude less than that in the starting inoculum. We conclude that cefotaxime and minocycline acted synergistically in inhibiting V. vulnificus in vitro.

Anti-Bacterial Agents↗
PubMed1997

Scrub typhus associated with multiorgan failure: a case report.

The spectrum of clinical severity for scrub typhus ranges from inapparent, mild, to severe or fatal. The pathologic changes are focal or disseminated multiorgan vasculitis of the small blood vessels, a fact that helps explain the great diversity of clinical manifestations that can be encountered. We reported a case of scrub typhus with unusual and serious multiorgan involvement, including tubulointerstitial nephritis (TIN) with acute renal failure (ARF), interstitial pneumonitis with adult respiratory distress syndrome (ARDS), disseminated intravascular coagulation (DIC), liver function impairment, upper gastrointestinal bleeding, prolonged hyperamylasaemia and hyperlipasaemia. Chloramphenicol administration rapidly altered the clinical course, but with sequelae of renal impairment and prolonged hyperamylasaemia and hyperlipasaemia for 10 months.

Anti-Bacterial Agents↗
PubMed1997

Percutaneous transluminal coronary angioplasty of the left anterior descending artery through a left main coronary artery of anomalous origin.

While coronary arteries of anomalous origin are uncommon, some forms seem to be predisposed to atherosclerosis. Very few cases of percutaneous transluminal coronary angioplasty (PTCA) in anomalous arteries have been reported. We report a case of successful PTCA of the left anterior descending artery through an anomalous left main coronary artery originating from the right aortic sinus in a 65-year-old man with unstable angina. PTCA was performed using an 8 F 3.5 cm right Judkins guiding catheter to dilate a discrete 90% stenosis of the left anterior descending artery. After PTCA, the patient became symptom free. Using the proper guiding catheter, PTCA can be performed in coronary arteries of anomalous origin with excellent results.

Aged↗
PubMed1997

Acute Q fever as a cause of acute febrile illness of unknown origin in Taiwan: report of seven cases.

Acute Q fever, caused by Coxiella burnetii has been well documented in Western countries, but only recently identified in Taiwan. Seven cases diagnosed by indirect fluorescent antibodies to phase II antigens of C. burnetii are reported. The patients were all men and a history of animal contact could be traced in most cases. Clinical manifestations were high fever, chills, relative bradycardia and elevated serum aminotransferases. Therapy with tetracycline or clarithromycin resulted in defervescence within 96 hours. Combining the knowledge on the prevalence of Q fever in Taiwan, the typical exposure history and clinical features in acute Q fever infection, primary care physicians may be able to avoid invasive but futile diagnostic intervention for patients with prolonged febrile illness. Prior to results from serologic testing, empiric therapy with tetracycline or its analogs may be considered for patients with typical clinical manifestations.

Adult↗
PubMed1997

Clinical characteristics and antimicrobial susceptibility of invasive group B streptococcal infections in nonpregnant adults in Taiwan.

To understand group B streptococcal infections other than peripartum events in adults and to provide a regional antimicrobial therapy guide, we conducted a retrospective analysis of invasive diseases caused by group B streptococcus (GBS) in 33 nonpregnant adults treated in a medical center in southern Taiwan, from January 1993 to July 1994. Antimicrobial susceptibility tests were performed using the agar dilution method. The incidence of the disease was 1.6 per 1,000 nonpregnant adult admissions, and the mean age of patients was 58 years (range 17-86 years). Primary bacteremia (13) and soft-tissue infections (11) were the most common manifestations. Nearly all the patients had underlying disease(s) and/or condition(s); the three most common were diabetes mellitus (13), malignancy (5), and liver cirrhosis (5). There were eight nosocomial infections and six patients died. Of 32 GBS strains tested, 27 were susceptible to penicillin G and the rest were intermediately susceptible. All strains were uniformly susceptible to cephalothin, cefotaxime, ofloxacin, and vancomycin; two strains were susceptible to gentamicin and nearly half were intermediately susceptible. Our findings imply a requirement for higher doses of penicillin or combination with an aminoglycoside for treatment of GBS infection. First-generation cephalosporins may be an alternative for the treatment of GBS infections in Taiwan.

Adolescent↗
PubMed1997

Mouse skin damage caused by a recombinant extracellular metalloprotease from Vibrio vulnificus and by V. vulnificus infection.

Vibrio vulnificus wound infection is characterized by an intense acute cellulitis which spreads along the subcutaneous tissue with severe tissue destruction. Toxins produced by the bacteria appear to be involved in the pathogenesis of skin necrosis and to facilitate microbial dissemination in vivo. We report microscopic studies of mouse skin damage caused by a single intradermal injection of V. vulnificus or of an extracellular metalloprotease isolated from this organism. The gene encoding this metalloprotease has been cloned and expressed in Escherichia coli. The crude metalloprotease extract obtained from the periplasmic fraction by osmotic shock was used in this study. Intradermal injection of this preparation resulted in marked edematous changes of the skin, which extended throughout the dermis and subcutaneous tissues and into adjacent muscles. The collagen and elastic fibers degenerated and some muscle cells even appeared necrotic. Blood vessels became congested, with moderate perivascular neutrophil and mononuclear cell infiltration. There was no evidence of necrotic changes in the blood vessel itself. These results show that the damage to the connective tissues caused by V. vulnificus is at least partly attributable to its protease. Therefore, the protease seems to be an important virulence factor of this microbe.

Animals↗