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Biomedical subjects

Y C Wu

Publications and source records attributed to Y C Wu.

At least 73 records · Page 4Linked to original sources

Paradoxical cerebral air embolism after removal of a central venous catheter: case report.

Paradoxical cerebral air embolization through a residual tract after the removal of a central venous catheter is a serious complication of central venous cannulation. Air embolisms resulting from residual catheter tracts in general patients and in single lung transplant patients have been reported. The generally accepted mechanism of this complication is failure of a spontaneous collapse or thrombotic obliteration of a well-formed catheter tract. It may be related to the duration of catheter insertion, the patient's nutritional status, the diameter of the indwelling catheter, the upright position of the patient, deep inspiration or coughing, and improper wound dressing and catheter removal. Cardiovascular collapse, pulmonary or neurologic sequelae, and even death, are commonly noted in patients with air embolism. In this article, we report on cerebral air embolization as a complication with the removal with a central venous catheter in a patient with bullous emphysema. A high degree of suspicion and a prompt diagnosis are required for successful application of established therapy. Simple prophylactic procedures and constant awareness of the unusual mechanism of air embolism remain the best treatment.

Aged↗

Thoracoscopic retrieval of metal rods after penetrating chest injury: case report.

Thoracoscopy has been used for both diagnostic and therapeutic purposes. Its use in the trauma field is rapidly increasing. Here, we present a case of chest trauma that was successfully treated using the thoracoscopic approach. A 43-year-old male patient was brought to our emergency room with a severe right chest wall-penetrating metal-rod injury, which had occurred after falling from a height. The chest X-ray showed an upper right lung lobe injury. Video-assisted thoracoscopic surgery (VATS) was performed for diagnosis of any other associated injury and for management of the penetrating injury. The prognosis was good. We believe that minimal thoracoscopic surgery is an alternative way that provides a more rapid diagnosis, and a less-invasive and safe operation for acute chest trauma patients.

Adult↗

Antiplatelet actions of aporphinoids from Formosan plants.

Seventeen aporphines were tested for antiplatelet activity. L-(+)-hemovine HCl and 7-hydroxydehydrothalicsimidine strongly inhibited platelet aggregation induced by adenosine 5'-diphosphate (ADP), arachidonic acid (AA), collagen, and platelet-activating factor (PAF). The latter showed the strongest antiplatelet activity with an IC50 of 70.4 microM against AA-induced platelet aggregation.

Animals↗

Determination of hydroxyaromatic compounds in water by solid-phase microextraction coupled to high-performance liquid chromatography.

Solid-phase microextraction (SPME) coupled with high-performance liquid chromatography (HPLC) for the analysis of hydroxyaromatic compounds is described. Three kinds of fibers [50 microns carbowax-templated resin (CW-TPR), 60 microns polydimethylsiloxane-divinylbenzene (PDMS-DVB) and 85 microns polyacrylate (PA) fibers] were evaluated. CW-TPR and PDMS-DVB were selected for further study. The parameters of the desorption procedure (such as desorption mode, the composition of the solvent for desorption and the duration of fiber soaking) were studied and optimized. The effect of the structure and physical properties of analytes, carryover, duration of absorption, temperature of absorption, pH and ionic strength of samples were also investigated. The method was applied to environmental samples (lake water) using a simple calibration curve.

Adsorption↗

Mixed-valence compound-based biosensor.

A cobalt(II)hexacyanoferrate-based biosensor has been prepared simply by codeposition of an enzyme, together with the electrochemical formation of a cobalt (II)hexacyanoferrate compound electrochemically. The compound can be generated at a constant potential of -0.05 V (vs. Ag/AgCl). This compound possesses the catalytic property of reducing hydrogen peroxide to water at the operating potential of 0.0 V vs. Ag/AgCl. The mixed-valence compound-based biosensor possesses an unique interference-independent feature, which is important for biomedical application; this feature is attributed to the low overvoltage characteristic of cobalt (II)hexacyanoferrate. The electrochemical glucose biosensor responds to a series of glucose injections with linearity up to 5 mM (with correlation coefficient R = 0.9999) and the sensitivity of the linear portion is 733 nA/(cm2 x mM). The detection limit is 2 x 10(-6)M (S/N = 3). Both the potential-dependent electron transfer rate constant and the apparent Michaelis-Menten constant were studied in rotating disk experiments. The apparent Michaelis-Menten constant, Km' calculated from the slope of the "Lineweaver-Burke" type reciprocal plot is 28 mM. A fast-response characteristic is observed in the rotating disk experiment and the 95% response time is 14.5 sec. No response was observed from the addition of either 2 x 10(-4)M galactose, acetaminophen, ascorbic acid, uric acid, cysteine, tyrosine, dopamine, or 1,4-dihydroxyquinone in the absence and/or in the presence of 5 x 10(-4)M glucose.

Biosensing Techniques↗

Aromin-A, an Annonaceous acetogenin from Annona cherimola.

Chromatographic fractionation of a MeOH extract from the stems of Annona cherimola led to the isolation of a new non-adjacent, bis-THF ring acetogenin (one THF ring being at C-4 and the other at C-16), aromin-A (1) along with the known cytotoxic acetogenin squamocin (2). The structures of these isolates were established by means of mass spectrometry and spectroscopic techniques.

Antineoplastic Agents, Phytogenic↗

Emphysema surgery--loop ligation approach.

OBJECTIVES: To demonstrate the efficacy of using thoracoscopic endoloop ligation of bullae in patients with bullous emphysema. METHODS: From 1992 to 1997, 93 advanced age (mean age, 66 years) and oxygen dependency patients underwent thoracoscopic procedure using endoloop ligation for treatment of bullous emphysema. Clinical data were collected from chart review. Thoracoscopic loop ligation of bulla was carried out under general anesthesia with double lumen endotracheal tube and single lung ventilation. RESULTS: Eighty-two patients (88%) exhibited subjective improvement in their symptom status at 3-month follow-up (from grade 2 or 3 to grade 1 or 2) according to the modified Medical Research Council dyspnea scale. The mean duration of chest drainage was 7.5 days (range, 4-19 days). Average hospital stay was 9.5 (range, 5-26) days. There was no post-operative death. A comparison of pre-operative and post-operative functional evaluation was available in 27 patients who showed an average increase in FEV1 (from 0.89 to 1.12 l) and declined in residual volume after operation. Complications include persistent airleak over 10 days in nine patients (9.7%), wound infection in three patients and localized empyema in five patients. There was no recurrent after a mean follow-up of 37 months. CONCLUSION: Thoracoscopic loop ligation of bulla has proven to be a safe, reliable and cost effective means of technique for bullous emphysema.

Aged↗

New annonaceous acetogenins from Rollinia mucosa.

Four new compounds, a mixture of 20,23-cis-2,4-trans-bullatalicinone (1) and 20,23-cis-2,4-cis-bullatalicinone (2), rollimusin (3), and rolliacocin (4), along with eight known acetogenins, were isolated from an ethyl acetate extract of the unripe fruits of Rollinia mucosa. The structures and stereochemistry of 1-4 were determined on the basis of spectral data and chemical evidence.

4-Butyrolactone↗

Aggregation inhibitory activity of minor acetophenones from Paeonia species.

Two minor acetophenones, 2,5-dihydroxy-4-methoxy-acetophenone (2) and 2,5-dihydroxy-4-methylacetophenone (7) from Paeonia species were found to selectively inhibit the aggregation of rabbit platelets induced by arachidonic acid. They were more potent than the major compound, paeonol (1), and 7 also inhibited the formation of TXA2 and PGD2 from arachidonic acid.

Acetophenones↗

Detection of Epstein-Barr virus in esophageal squamous cell carcinoma in Taiwan.

OBJECTIVE: Recently, an association between viral infection and the development of esophageal carcinoma has been reported, particularly the human papilloma virus (HPV) and Esptein-Bar virus (EBV). However, geographic variation in carcinogenesis is realized. In this study, we investigate the viral carcinogenesis and the biologic effect of viral infection on esophageal squamous cell carcinoma (ESCC) in Taiwan. METHODS: To determine the association of viral infection (EBV and HPV) with ESCC, we applied polymerase chain reaction (PCR), immunohistochemistry, and in situ hybridization (ISH) to examine 119 surgical specimens from different sites of esophagus in 31 ESCC patients. Additionally, an immunoperoxidase method was used to detect EBV latent membrane protein-1 (LMP-1), p53, CD45RO (UCHL-1), Fas ligand (Fas L), and RNA ISH with oligonucleotide sequences was used to detected interleukin-6 (IL-6) mRNA. RESULTS: By PCR, EBV DNA was detected in 11 cases (35.5%). Expression of EBERs in ESCC was further confirmed with ISH. Nonetheless, no LMP-1 expression was detected. On the other hand, human papillomavirus (HPV) was identified in only one case (3.2%) of ESCC. Furthermore, HPV was located by ISH in the distant normal region rather than in tumor cells. In EBV-positive cases, accumulation of p53 protein was detected in 10 lesions (91%); CD45RO+ lymphocytes together with expressions of FasL and IL-6 were respectively identified in 100%, 63.6%, and 54.5% of 11 EBV-positive lesions. Interestingly, in the EBV-negative cases (n = 20), p53 protein was detected in 40% of lesions; CD45RO 30%; FasL 50%, and IL-6 10%. CONCLUSIONS: In this study, no correlation was found between the presence of EBV in ESCC and the patients' age, sex, as well as survival. Although our results indicate that EBV could be associated with ESCC, the clinical role of EBV in ESCC remains to be determined.

Aged↗

Two components of transducer adaptation in auditory hair cells.

Mechanoelectrical transducer currents in turtle auditory hair cells adapted to maintained stimuli via a Ca(2+)-dependent mechanism characterized by two time constants of approximately 1 and 15 ms. The time course of adaptation slowed as the stimulus intensity was raised because of an increased prominence of the second component. The fast component of adaptation had a similar time constant for both positive and negative displacements and was unaffected by the myosin ATPase inhibitors, vanadate and butanedione monoxime. Adaptation was modeled by a scheme in which Ca(2+) ions, entering through open transducer channels, bind at two intracellular sites to trigger independent processes leading to channel closure. It was assumed that the second site activates a modulator with 10-fold slower kinetics than the first site. The model was implemented by computing Ca(2+) diffusion within a single stereocilium, incorporating intracellular calcium buffers and extrusion via a plasma membrane CaATPase. The theoretical results reproduced several features of the experimental responses, including sensitivity to the concentration of external Ca(2+) and intracellular calcium buffer and a dependence on the onset speed of the stimulus. The model also generated damped oscillatory transducer responses at a frequency dependent on the rate constant for the fast adaptive process. The properties of fast adaptation make it unlikely to be mediated by a myosin motor, and we suggest that it may result from Ca(2+) binding to the transducer channel or a nearby cytoskeletal element.

Adaptation, Physiological↗

The epidemiology of Japanese encephalitis on Taiwan during 1966-1997.

Japanese encephalitis (JE) is an endemic disease in Taiwan. A mass vaccination program of children against JE was first implemented in 1968. Along with general improvements in various aspects of living conditions over the years, the program has brought JE well under control. The main characteristics of JE epidemiology in Taiwan in the past 3 decades are as follows. The transmission mode remains unchanged-that is, the amplification stage of the virus in pigs is followed by a human epidemic each year. The frequency of JE incidence has dropped significantly. The incidence rate of confirmed cases was 2.05 per 100,000 in 1967, the highest in record, and merely 0.03 per 100,000 in 1997. Confirmed cases occur sporadically all over the island. The peak of the epidemic season has shifted from August in the 1960s to June since the 1980s. The age distribution of confirmed cases has shifted gradually from mainly children to adults. Vaccine efficacy for those having received more than 2 doses of the vaccine is estimated to be about 85%.

Adult↗

Leiomyosarcoma of the gastric cardia and fundus.

BACKGROUND: Gastric leiomyosarcoma is rare among gastric malignancies, and only 20% of the cases are located in the gastric cardia or fundus. It has clinical manifestations different from tumors in other sites of the stomach. We reviewed cases of leiomyosarcoma of the gastric cardia or fundus to evaluate their clinicopathologic characters and patient survival. METHODS: From May, 1981, to June, 1998, a total of 15 patients who underwent curative resection of leiomyosarcoma of the gastric cardia or fundus were retrospectively identified and studied. All the clinical and pathologic data were reviewed and recorded. RESULTS: There were 11 men and four women. Their mean age was 59.1 years (range, 37-73 years). Tarry stools and epigastric fullness and pain were the most common symptoms, followed by body weight loss. All 15 patients had submucosal tumors in the gastric cardia or fundus, as shown by endoscopy, barium contrast radiography and computerized tomography. The incidence of esophageal involvement by the tumors was quite low. The mean tumor size was 10 cm, ranging from 4 cm to 20 cm. Locoregional organs were involved in nine patients. The median and mean survivals were 17.8 months and 31.7 months, respectively (range, 10.1-80.1 months) after curative resection. The three-year and five-year survival rates were 53% and 22%, respectively. CONCLUSIONS: The definitive preoperative diagnosis of the tumor is difficult before surgery, even though imaging studies show positive findings. Surgical resection with an adequate safe margin of normal tissue is the treatment of choice. Tumor size, serosal invasion with locoregional organ involvement and high tumor grade were the prognostic factors in the study.

Adult↗

[Immunity against diphtheria in Taiwan].

The vaccination of combined diphtheria, pertussis, and tetanus (DPT) vaccine provides good immunity against childhood diphtheria in Taiwan. However, a waning protective antibody level has been observed with an increase in age. Therefore, we assessed diphtheria immunoglobulin (DIG) level in Taipei City as representatives of urban dwellers and in King-Shan County as representatives of rural dwellers to evaluate the status of immunity against diphtheria in the population of Taiwan. In total, 1239 serum samples collected from the resident population, age 0-91 years, were detected by toxin neutralization test with VERO cells. The DIG level > or = 0.01 IU/mL was considered to be seropositive and > or = 0.1 IU/mL was considered to be fully protective. The positive rate and fully protective rate for all persons were 79.9% and 36.6%, respectively. The age specific positive rate and fully protective rate for children under 14 years of age were 97.0% and 78.0%, for 20-29 years of age group, were 38.0% and 8.3%, respectively, to be the lowest record among tested age groups. Then, both rates increased proportionately with age. Among those birth cohorts born in the diphtheria immunization era (since 1955), the antibody levels were inversely correlated with age, suggesting a decreased opportunity for exposure to natural diphtheria infection in the recent years and the duration of the vaccine inoculation. This finding indicates the need of a booster vaccination for young adults to ensure a full term protection and a long lasting diphtheria control.

Adolescent↗

Antibody responses to an immunodominant nonstructural 1 synthetic peptide in patients with dengue fever and dengue hemorrhagic fever.

Two flaviviruses, dengue (DEN) virus and Japanese encephalitis (JE) virus, are important because of their global distribution and the frequency of epidemics in tropical and subtropical areas. To study the B-cell epitopes of nonstructural 1 (NS1) glycoprotein and anti-NS1 antibody response in DEN infection, a series of 15-mer synthetic peptides from the predicted B-cell linear epitopes of DEN-2 NS1 protein were prepared. Enzyme-linked immunosorbent assay (ELISA) was performed to analyze antibody responses to these peptides from sera of both DEN and JE patients. One peptide derived from DEN-2 NS1, D2 NS1-P1 (amino acids 1-15), was identified as the immunodominant epitope that reacted with sera from dengue fever (DF) patients but not JE patients. The isotype of D2 NS1-P1-specific antibodies was mainly immunoglobulin M (IgM) in all sera that tested positive. A specificity study demonstrated that sera from all four DEN types reacted with D2 NS1-P1. A dynamics study showed that specific antibodies to this peptide could be detected as early as 2 days after the onset of symptoms. We observed significant anti-D2 NS1-P1 antibody responses in 45% of patients with primary and secondary infections with DF or with dengue hemorrhagic fever. This is the first report demonstrating that significant anti-DEN NS1 antibodies can be induced in the sera of patients with primary DEN infection.

Amino Acid Sequence↗