Biomedical subjects

J R Wu

Publications and source records attributed to J R Wu.

At least 55 records · Page 3Linked to original sources

PubMed1995

Effect of capsaicin on membrane currents in cultured vascular smooth muscle cells of rat aorta.

The application of capsaicin (1 microM) produced a minor relaxant effect in endothelium-denuded rat aortae. However, capsaicin caused a greater relaxation of blood vessels precontracted with high K+ or phenylephrine. The effects of capsaicin on the ionic currents were also examined in A7r5 vascular smooth muscle cells. The tight-seal whole-cell voltage clamp technique was used. Capsaicin inhibited the Ba2+ inward current (IBa) through the voltage-dependent L-type Ca2+ channel in a concentration-dependent fashion, whereas calcitonin gene-related peptide and phenylephrine produced a minor increase in IBa. Capsaicin did not alter the overall shape of current-voltage relationship of IBa. However, capsaicin (3 microM) shifted the quasi-steady-state inactivation curve of IBa to more negative membrane potential by about 5 mV. These effects of capsaicin on IBa were reversible. In addition, capsaicin had inhibitory effects on voltage dependent K+ currents. These results suggest that inhibition of the voltage-dependent L-type Ca2+ channel is involved in the capsaicin-induced relaxation of the vascular smooth muscle, whereas capsaicin-induced inhibition of voltage-dependent K+ channels might produce an increase in cell excitability.

Animals↗

PubMed1995

Isolated persistent fifth aortic arch with right-sided aortic arch.

A persistent fifth aortic arch was recognized in a 4-year-old boy by echocardiography, magnetic resonance imaging and angiocardiography. The case was unique in at least two respects: right-sided aortic arch, and systemic-to-pulmonary connection without intracardiac lesion. This rare type of anomaly was correctly diagnosed and successfully repaired by patch closure of the arch. This is the first report of this combination of lesions in the Orient.

Angiocardiography↗

PubMed1995

Frozen section of diagnosis of breast lesions.

Frozen section diagnosis rendered in 549 consecutive breast biopsies performed in 5 years in a single pathology laboratory was correlated with the final pathological diagnosis. There were no false positive reports among the 220 (40.1%) biopsies interpreted as benign lesions in paraffin sections. Among 329 (59.9%) malignant biopsies on paraffin sections, 3 cases were interpreted as benign lesions on frozen sections. Three false negatives included 2 ductal carcinoma in situ and one infiltrating ductal carcinoma associated with papillomatosis. The tumors were small and confined to the breast without any evidence of metastasis. There was a very good correspondence between the frozen section diagnosis and the paraffin section diagnosis (K = 0.98). The sensitivity of frozen section diagnosis was 99.1% and the clinical diagnostic specificity was 100%. Our results suggest that frozen section diagnosis is a highly reliable procedure, but small lesions (less than 1 cm in diameter, or non-palpable) should not be subjected to frozen section examination to avoid unnecessary loss of neoplastic tissue during the frozen section. The careful investigation of paraffin-embedded tissue is recommended for small breast lesions in breast conserving lumpectomy.

Breast Diseases↗

PubMed1995

Relationship between left atrial pressure and atrial natriuretic peptide in children with cardiac disease.

To evaluate the relationship between atrial pressure and the concentrations of atrial natriuretic peptide (ANP) in plasma of children with cardiac disease combined with increased left atrial loading. We extracted plasma ANP through a Sep-Pak C18 cartridge and proceeded to radioimmunoassay. Of the nine children, aged from 20 days to 10 years, cardiac diseases included transposition of the great arteries (four cases), ventricular septal defect (three cases), patent ductus arteriosus (one case) and mitral regurgitation (one case). The concentrations of ANP in plasma in the left atrium were greater than in the inferior vena cava, and the concentrations of ANP in plasma in the inferior vena cava correlated significantly with the mean left atrial pressure (r = 0.89, p < 0.01), and the concentrations of ANP in plasma in the left atrium correlated significantly with the mean left atrial pressure (r = 0.85, p < 0.01). This study indicated that left atrial pressure may have an important influence on secretion of ANP in various cardiac conditions.

Atrial Natriuretic Factor↗

PubMed1995

[Current clinical approaches and gene mutation study of beta-thalassemia major].

Forty-one cases of beta-thalassemia major were assessed for their clinical manifestations and gene mutation. The age distribution was from 1 to 18 years old. Patient's initial clinical symptoms began mostly before 2 years of age (90.2%). Patient's initial hematological data included mean hemoglobin value, 5.8 +/- 1.2 gm/dl, hemoglobin F value, 85.0 +/- 12.1%, hemoglobin A2 value 2.3 +/- 1.8%, reticulocyte count 9.2 +/- 9.0%. Eight different point mutations were characterized. Of these mutations, C to T substitution at nucleotide (nt) 654 of intervening sequence (IVS) 2, accounting for 46.3% of mutant beta-globin genes, is the most common mutation in our series, followed by frameshift codons 41/42 with a four nucleotides (TCTT) deletion for 31.7%; A to G substitution at position -28 of the promotor area for 8.5%; A to T substitution at codon 17 for 6.1%; frameshift codons 27/28 (insertion of C) for 2.4%; G to T substitution at nucleotide 1 of IVS-1 for 2.4%; frameshift codons 71/72 (insertion of A) and IVS-1 3' end TAG-->GAG for 1.2%. The first four mutations account for 92.6% of all beta-globin gene mutations in our series. As to mutations in each individual, the incidence of compound heterozygotes of two different mutations is much higher than homozygotes of a single mutation, 78.0% vs. 22.0%. Compound heterozygotes of C to T substitution at nt 654 of IVS-2 and frameshift codons 41/42 with a four nucleotides deletion is the most common pattern of beta-thalassemia mutation in our patients (41.5%). Patients with beta(0)/-28 beta(+) compound heterozygote mutation had much delayed initial symptoms than beta (0)/beta(0) homozygote mutation, but clinical manifestation may be aggravated when the mutation combined with glucose-6-phosphate dehydrogenase deficiency. Severity of iron overload was significantly correlated with total transfusion amount and patient's age in simple regression analysis (p < 0.001). Splenectomy may effectively prolong transfusion interval, maintain higher hemoglobin level before each transfusion and palliate clinical symptoms (p < 0.01). Iron-chelating agent therapy can effectively lower the total amount of serum ferritin. Higher severity of iron overload correlates with higher incidence of EKG and cardiac abnormalities in patients with beta-thalassemia major.

Adolescent↗

PubMed1994

Phosphatidylserine-containing membranes alter the thermal stability of prothrombin's catalytic domain: a differential scanning calorimetric study.

Denaturation profiles of bovine prothrombin and its isolated fragments were examined in the presence of Na2EDTA, 5 mM CaCl2, and CaCl2 plus membranes containing 1-palmitoyl-2-oleoyl-3-sn-phosphatidylcholine (POPC) in combination with bovine brain phosphatidylserine (PS). We have shown previously [Lentz, B. R., Wu, J. R., Sorrentino, A. M., & Carleton, J. A. (1991) Biophys. J. 60, 70] that binding to PS/POPC (25/75) large unilamellar vesicles resulted in an enthalpy loss in the main endotherm of prothrombin denaturation (Tm approximately 57-58 degrees C) and a comparable enthalpy gain in a minor endotherm (Tm approximately 59 degrees C) accompanying an upward shift in peak temperature (Tm approximately 73 degrees C). This minor endotherm was also responsive to Ca2+ binding and, in the absence of PS/POPC membranes, corresponded to melting of the N-terminal, Ca2+ and membrane binding domain (fragment 1). Peak deconvolution analysis of the prothrombin denaturation profile and extensive studies of the denaturation of isolated prothrombin domains in the presence and absence of PS/POPC vesicles suggested that membrane binding induced changes in the C-terminal catalytic domain of prothrombin (prethrombin 2) and in a domain that links fragment 1 with the catalytic domain (fragment 2). Specifically, the results have confirmed that the fragment 2 domain interacts with the stabilizes the prethrombin 2 domain and also have shown that fragment 2 interacts directly with the membrane. In addition, the results have demonstrated a heretofore unrecognized interaction between the catalytic and membrane binding domains. This interaction can account for another portion of the denaturation enthalpy that appears at high temperatures in the presence of membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Autonomic and sensory cardiovascular activities of nonivamide: intrathecal administration of clonidine.

The effects of nonivamide on the cardiovascular system were examined and compared with the effects of substance P (SP) in rats. Intravenous (i.v.) injection (10 micrograms/kg) of nonivamide produced triphasic pressure responses (A; depressor, B; pressor, and C; depressor) and biphasic bradycardia responses (f; fast bradycardia and s; slow bradycardia). IA injection (10 micrograms/kg) into the epigastric artery caused hypotension and mild tachycardia. The effects of atropine, vagotomy, SP antagonist, propranolol, and clonidine on these responses were examined and mechanisms responsible for the nonivamide-induced responses are postulated as follows. A and f are due to vagal reflex resulting from the excitation of afferent sensory neurons in the heart and are parasympathetic efferent effects from the nucleus solitarius. B is involved in sympathetic activation, partly caused by the release of SP in the spinal cord. C is due to the vasodilatory effect of SP released from perivascular stores. s was diminished by vagotomy and is due to the bradycardiac effect of acetylcholine, released by SP, from cardiac stores. The activation of the autonomic system is inhibited by clonidine and involved in the wide spectrum of nonivamide-induced cardiovascular effects.

Animals↗

PubMed1994

Study on the children of Kaohsiung with acute viral infection of lower respiratory tract by direct immunofluorescence assay.

This study retrospectively reviewed those pediatric patients of acute lower respiratory tract infection with positive virus identification by direct immunofluorescence assay (Direct IF) from Jan, 1992 to Dec, 1993. One hundred and eighteen patients with 133 positive Direct IF results (107 cases with single virus identified, and 11 cases with more than one) were included. The sex ratio was 1.6:1 with males predominant; age, 22.1 (1 approximately 154.8) (months); duration of admission, 5.7 (1 approximately 69) (days); peripheral white blood cell count, 10,600 +/- 3,800/mm3; C-reactive protein, 17.0 (0 approximately 163.3) mu/ml; body temperature, 37.1 +/- 1.1 degrees C in those cases with single virus. The symptoms were cough 105 cases (98.1%), rhinorrhea 46 cases (43.0%), dyspnea and/or tachypnea 43 cases (40.2%) and diarrhea 15 cases (14.0%). The viruses identified were: Adenovirus (52 cases, 39.1%). Influenza B (45 cases, 33.8%), Parainfluenza 1 (28 cases, 20.1%), Parainfluenza 3 (19 cases 14.3%), Respiratory Syncytial virus (17 cases, 12.8%), and Influenza A (9 cases, 6.8%). The seasonal incidence rates were spring (49 cases, 36.8%), summer (46 cases, 34.6%), autumn (23 cases, 17.3%), and winter (15 cases, 11.3%). The results showed much similarity with others, except the commonest viral type (Adenovirus in this study; Respiratory Syncytial virus in others) and the seasonal incidence rate (higher in spring and summer in this study but not in others). In conclusion, most children with acute viral lower respiratory tract infection had an uneventful course and Direct IF is a reliable method for viral detection in that disease.

Acute Disease↗

PubMed1994

Phospholipid-specific conformational changes in human prothrombin upon binding to procoagulant acidic lipid membranes.

This paper provides evidence to demonstrate that human prothrombin undergoes conformational changes upon binding to procoagulant membranes specifically containing phosphatidylserine (PS). Fourier transform infrared spectroscopy was used to show a slight increase in ordered (alpha-helix, beta-sheet, beta-turns) secondary structure upon binding to PS-containing membranes. Thermograms representing prothrombin and prothrombin fragment 1 denaturation were obtained using differential scanning calorimetry. These were analyzed and interpreted in terms of changes in prothrombin domain organization associated with binding to PS-containing membranes. Changes in either secondary structure or domain organization upon binding to negatively-charged phosphatidylglycerol-containing membranes were, if they occurred at all, much less dramatic. The results paralleled results obtained previously with bovine prothrombin (1, 2). The implications of these results in terms of a possible molecular mechanism for the cofactor-like role of platelet membrane vesicles in prothrombin activation are discussed.

Acids↗

PubMed1994

Correction of aortico-left ventricular tunnel in a small Oriental infant: a brief clinical review.

In reviewing 56 cases of aortico-left ventricular tunnel from 39 reported articles, none of the patients operated on were Oriental. In this report, a 4 month-old male infant was successfully operated on. The tunnel was closed with a Dacron patch on the aortic orifice. The child is now free from symptoms, except for mild residual aortic regurgitation, and is developing normally 5 year-11 month after repair. A brief clinical review has been attempted in these reported cases.

Aorta↗

PubMed1994

Balloon pulmonary valvuloplasty in infants and children: technique and immediate result.

Between 1986 and Feb. 1993, 20 patients with moderately severe isolated pulmonary stenosis underwent cardiac catheterization and balloon pulmonary valvuloplasty (BPV). Their ages ranged from 7 months to 11 years old (mean 6.2 years), their weights ranged from 8 to 45 kg (mean 14.5 kg). Immediately after BPV, the right ventricular pressure decreased from 89 +/- 21 to 46 +/- 16 mmHg (p < 0.005). The pressure gradient across the pulmonary valve reduced by 68%, from 68 +/- 23 to 24 +/- 16 mmHg (p < 0.005). There was no significant changes in both pulmonary artery pressure (19 +/- 4 versus 21 +/- 3 mmHg), and aortic pressure (102 +/- 11 versus 104 +/- 11 mmHg). Successful BPV (pulmonic pressure gradient < 36 mmHg) was achieved in 15 cases (75%). Among the 5 unsuccessful cases, 2 patients underwent redilatation which had excellent results. Another 2 patients received operations, one was a dysplastic pulmonary valve, the other was due to a gradient across the pulmonary valve > 120 mmHg before BPV. The remaining one had only 40 mmHg gradient after BPV, and he was doing well on follow-up. There were no significant complications in these series. BPV is an effective and safe procedure. It should be the treatment of choice for significant pulmonary stenosis in infants and children.

Catheterization↗

PubMed1993

Influence of pentachlorophenol on light emission from single barnacle muscle fibers preloaded with aequorin.

Experiments show that the resting ouabain-insensitive sodium efflux in giant fibers from the barnacle Balanus nubilus is stimulated by external application of pentachlorophenol (PCP). This work has now been extended to include a study of muscle fibers preloaded with the Ca2+ indicator aequorin to determine whether PCP is able to increase light emission; and whether its potency depends on the number of chlorine atoms and external pH. The results obtained are as follows: 1) PCP causes a dose-dependent, multiphasic rise in light emission; the threshold concentration in fibers not poisoned with ouabain was in the low micromolar range. 2) The efficacy of PCP is considerably greater than that of less-chlorinated phenols and phenol. 3) The response to PCP is a sigmoidal function of external pH both in unpoisoned and ouabain-poisoned fibers. Reducing external pH potentiates its efficacy. 4) The response to PCP depends on the external Ca2+ concentration, and the requirement for Ca2+ is usually absolute.

Aequorin↗

PubMed1993

[Study on coronary artery lesions in patients with Kawasaki disease: recent 9 years' experience].

During a nine year period, two-dimensional echocardiography was used to evaluate the coronary artery lesions in 293 patients with Kawasaki disease. There were 170 males and 123 females (M: F = 1.4:1), with a mean age of 28.5 months (2 months-10 years). Patients were randomly divided into 3 groups according to different treatment regimens: group A, aspirin 60-80 mg/kg alone, 199 patient; group B, aspirin plus intravenous gamma globulin (IVGG) 400 mg/kg for 5 days, 80 patients; group C, aspirin plus a single dose of IVGG 2.0 gm/kg, 14 patients. A total of 106 patients (36.2%) had coronary artery lesions. The prevalence of coronary artery lesions in groups A, B, and C was 42.7%, 22.5% and 21.4% respectively. It was the highest in group A (P < 0.01). Coronary artery involvement occurred with equal frequency in males and females. There was a significantly greater incidence of coronary artery lessons in infants younger than 1 year of age than in older children (P < 0.05). From the serial echocardiographic studies, the coronary artery lesions occurred earliest on the 5th day of onset, with the prevalence of 23.6% in the acute stage, and 35.4% at the subacute stage. The prevalence of coronary artery abnormalities in group A was significantly higher than in group B and C at 2-3 weeks and 7-8 weeks after the onset of the fever (P < 0.01). Coronary artery lesions were further classified into 3 morphologic types: dilated form, fusiform and saccular aneurysm. The prevalence of saccular aneurysms was higher in group A than in group B and C (10.0% vs 1.2%, 0%, P < 0.01). Moreover, the regression rate was also higher in group A than the other groups (P < 0.01). Fifteen cineangiograms were performed on 14 patients and they confirmed the presence of coronary lesions in all cases. Better visualization of the lesions was achieved by cineangiography than by echocardiography, especially in the middle and distal portions of the coronary artery. In group A, a six months old boy expired, 25 days after suffering from fever, due to myocardial infarction and congestive heart failure, which was also confirmed by a postmortem examination. It appears that gamma globulin infusion especially a single high dose regimen, is more effective than the conventional aspirin therapy for Kawasaki disease. The IVGG groups are also associated with a lesser prevalence of coronary lesions, a lesser degree of severity and a greater chance of regression.

Age Factors↗

PubMed1993

[Congenital nasopharyngeal teratoma: report of a case and review of the literature].

Teratomas are the most common congenital tumors, but teratomas of the nasopharynx are rare and seen almost exclusively in infants, usually in neonates. An unusual case of a neonate with respiratory distress is presented and a nasopharyngeal mass protruding into the oral cavity. After successful removal of the mass, pathological examination revealed a mature teratoma. The management and differential diagnosis are discussed, accompanied by a review of the literature.

Female↗

PubMed1993

Clinical study of Mycoplasma pneumoniae pneumonia.

From 1982 to 1991, we experienced 76 patients with Mycoplasma pneumoniae pneumonia which were confirmed by serologic tests. There were 32 (42%) male and 44 (58%) female patients. One patient had underlying disease of diabetes mellitus while the other patients were in good health. The age ranged from 9 months old to 72 years old. All the patients complained of fever and coughing; 63% had dry cough and 37% had sputum production. Upper respiratory tract complaints such as rhinorrhea, sore throat, or earache were noted in 57% of the patients. Fifty-five percent of the patients had GI symptoms of anorexia, nausea, vomiting, or diarrhea. Other complaints included myalgia/arthralgia (29%), headache (30%), and general malaise (32%). Dyspnea (17%) and chest pain (20%) were occasional complaints. Seventy-one percent of the patients had WBC counts < 10000/cu mm and 29% > 10000/cu mm. The mean value of C-reactive protein (CRP) was 53.1 micrograms/ml, while 16% of the patients had a CRP value above 100 micrograms/ml. Thirty-one percent of the patients were noted to have a transient elevation of serum transaminase. Four different patterns of infiltration were seen in chest radiographic manifestation: 1) peribronchial and perivascular interstitial infiltrates (18.4%), 2) nonhomogeneous patchy consolidations (22.4%), 3) homogeneous acinar consolidations (27.6%), and 4) mixed interstitial and alveolar infiltrates (27.6%). Interstitial infiltration was more commonly seen in pediatric than adult patients (46% vs 20%). Other features of the radiologic manifestation were as follows: unilateral lesions in 80% of patients, single lobe lesions in 77%, lower lobe predominant in 69%, pleural effusion in 7%, and radiographic deterioration in 10%. Mycoplasmal pneumonia should be considered in the differential diagnosis of community-acquired pneumonias.

Adolescent↗

PubMed1992

Abolition with chloramine-T of inactivation in barnacle muscle fibers results in stimulation of the ouabain-insensitive sodium efflux.

The hypothesis that chloramine-T stimulates the basal Na+ efflux in barnacle fibers as the result of the entry of trigger Ca2+ into the myoplasm from the bathing medium was examined in this study. Two reasons for doing so can be given. One is that the oxidant is known to abolish inactivation in sodium and potassium channels. The other is that L-type Ca2+ channels are present in barnacle fibers, and an increase in internal free Ca2+ in these fibers is known to stimulate the Na+ efflux, particularly in ouabain-poisoned fibers. The results of the experiments are as follows: (i) Chloramine-T exerts a biphasic effect on the Na+ efflux: inhibition is followed by stimulation, the threshold concentration being 10(-5) M. This is also found to be the threshold concentration for shortening of these fibers. (ii) The kinetics of the inhibitory effect resemble those of ouabain. (iii) Ouabain is without effect on the stimulatory phase caused by chloramine-T. (iv) Application of chloramine-T after the full effect of 10(-4) M-ouabain is reached elicits solely a stimulatory response. (v) The dose-response curves for the stimulatory action of chloramine-T in unpoisoned and ouabain-poisoned fibers are alike except that the threshold concentration is less than 10(-5) M in poisoned fibers. (vi) Basal light emission from unpoisoned and ouabain-poisoned fibers loaded with the photoprotein, aequorin, some 60 min beforehand increases as soon as they are exposed to 10(-4) M chloramine-T. The response recorded in unpoisoned fibers is monophasic and usually transitory, whereas it is multiphasic and usually sustained in ouabain-poisoned fibers. (vii) The dose-response curve for chloramine-T shows a shift to the left in poisoned fibers. (viii) The magnitude of the rise in light emission depends on the external Ca2+ concentration. A rise fails to take place in the nominal absence of external Ca2+. Taken together, these results support the above hypothesis that chloramine-T causes the entry of trigger Ca2+ into the myoplasm from the outside and provide evidence that stimulation of the Na+ efflux is associated not only with this event but also with a reduced Na+ gradient resulting from inhibition of the membrane Na+/K(+)-ATPase system by the oxidant. Thus, the suggestion put forward is that this oxidant promotes reverse Na+/Ca2+ exchange and is able to exert multiple effects on membrane transport.

Animals↗

PubMed1992

The propagation of Lamb waves in a plate bordered with layers of a liquid.

The influence of liquid layers on the propagation of Lamb waves in a plate of finite thickness is studied theoretically. The dispersion equations of Lamb waves in a plate bordered with layers of liquids are derived. Numerical solutions of the equations show that the phase velocity of Lamb waves changes with the thickness of the liquid layers. For the lowest antisymmetrical mode of very thin plates, the numerical results calculated from the dispersion equations are compared with those derived from the bending wave acoustic impedance approach. The limitation of the latter is discussed. Applications of Lamb waves pertinent to biosensing are also presented.

Acoustics↗

PubMed1992

Congenital absence of the pulmonary valve: report of two cases with review of the literature.

Congenital absence of the pulmonary valve is an uncommon combination of anomalies. Recently, we encountered two such cases, one associated with tetralogy of Fallot (case 1), the other with ventricular septal defect (case 2). Clinically, our cases had minimum symptoms. The congenital cardiac anomalies were diagnosed with physical examination, chest x-ray film, echocardiography, and confirmed with cineangiography. These procedures disclosed a rudimentary pulmonary valve, pulmonary regurgitation and aneurysmal dilatation of the main and right pulmonary artery. In case 2, the right lower pulmonary artery occlusion and left hydronephrosis were also demonstrated by magnetic resonance imaging. The two cases underwent surgical repair to correct the tetralogy of Fallot and the ventricular septal defect respectively. Our experience in diagnosing these cardiac anomalies is reported.

Child↗