Search PubMed⌕ Search

Biomedical subjects

C H Huang

Publications and source records attributed to C H Huang.

At least 37 records · Page 2Linked to original sources
PubMed2001

Mixed-chain phospholipids: structures and chain-melting behavior.

It has long been established that diacyl phospholipids isolated from animal cell membranes are predominantly of a mixed-chain variety, meaning that the sn-1 and sn-2 acyl chains are saturated and unsaturated acyl chains, respectively. In general, monoenoic and dienoic acids are found in the sn-2 acyl chain of phosphatidylcholine (PtdCho), whereas polyenoic acids are in phosphatidylethanolamine (PtdEth). These unsaturated chains contain only cis-double bonds, which are always methylene-interrupted. In recent years, the structures and the chain-melting behavior of mixed-chain PtdCho and PtdEth have been systematically studied in this laboratory. Specifically, we have examined the effects of chain unsaturation of the sn-2 acyl chain on the phase transition temperature (Tm) of many PtdCho and PtdEth by high-resolution differential scanning calorimetry (DSC). The Tm values, for instance, obtained from all-unsaturated mixed-chain PtdEth derived from a common precursor can be grouped together according to their chemical formula to form a Tm-diagram. Hence, all the Tm values can be compared simply, systematically, and simultaneously using the Tm-diagram. In addition, the energy-minimized structures of mixed-chain phospholipids containing different numbers/positions of methylene-interrupted cis-double bonds have been simulated by molecular mechanics calculations (MM). In this review, the results of our MM and DSC studies carried out with various mixed-chain phospholipids are summarized. In addition, we emphasize that the combined approach of MM and DSC yields unique information that can correlate the various Tm-profiles seen in the Tm-diagram with the structural variation of mixed-chain lipids as caused by the introduction of different numbers/positions of methylene-interrupted cis-double bonds.

Chemical Phenomena↗
PubMed2001

Morphometric identification of luminal narrowing of myocardial capillaries after cardioplegic arrest.

BACKGROUND: Because there is no smooth muscle cell surrounding the capillary endothelial cells, the effect of coronary microcirculation at the capillary level following cardioplegic arrest and reperfusion would be much different from that of resistant arterioles. We therefore studied the effect of hypothermic blood cardioplegic arrest and subsequent reperfusion on the myocardial capillaries in cardiac operation patients. METHODS: Twenty-seven patients who underwent cardiac operations were included in this study. Three sequential biopsies (preischemia, ischemia, and reperfusion) were obtained from the right atrium. This study was restricted to blood vessels with a diameter of less than 8 microns. Ten randomly selected capillaries from each biopsy were measured for luminal surface area, endothelial cytoplasmic surface area, and total cross-sectional surface area of capillaries. RESULTS: From stereologic morphometric studies, the serial changes in total cross-sectional surface area were not statistically significant (p = 0.152). However, there was a significant swelling of endothelial cytoplasm following ischemia and reperfusion (p = 0.0007). Meanwhile, changes in luminal surface area of capillaries following ischemia and reperfusion were also remarkable (p = 0.0008). CONCLUSIONS: The most striking finding of this study was the progressive decrease in capillary lumen during ischemia and after reperfusion. The swelling of endothelial cells is a major determinant of luminal narrowing of capillaries in patients receiving cardioplegic arrest.

Adolescent↗
PubMed2001

Real-time PCR for rapid genotyping of angiotensin-converting enzyme insertion/deletion polymorphism.

OBJECTIVE: To develop a real-time PCR technique for detection of the insertion/deletion (I/D) polymorphism of angiotensin-converting enzyme (ACE) gene. DESIGN AND METHODS: Three primers were designed for performing real-time PCR in the presence of SYBR Green I as flurochrome followed by melting curve analysis. Forty human genomic DNA that have been genotyped by two-rounds of conventional PCR were used for evaluation of this technique. RESULTS: Melting curve analysis indicated the melting peak at 73.9 degrees C and 76.2 degrees C corresponding to the presence of I and D alleles, respectively. Comparable genotyping results were obtained by both conventional and real-time PCR. Besides, the mistyping of ID allele individuals by the first run of conventional PCR were accurately genotyped by single-tube real time PCR. CONCLUSIONS: The real-time PCR method presented in this study provides a rapid and sensitive way for genotyping of ACE gene that may be suitable for large-scale clinical and epidemiologic study.

Alleles↗
PubMed2001

The influence of inserting a Fuji pressure sensitive film between the tibiofemoral joint of knee prosthesis on actual contact characteristics.

OBJECTIVE: To investigate the influence of inserting a Fuji pressure sensitive film between the tibiofemoral joint of knee prosthesis on actual contact characteristics. DESIGN: A finite element analysis was used to investigate the alteration of contact characteristics of the tibiofemoral joint due to inserting a pressure sensitive film between the contacting surfaces. BACKGROUND: The discrepancy between actual contact behaviors of tibiofemoral joint of knee prosthesis and the measurement using Fuji pressure sensitive film was not discussed extensively. The change of direct contact circumstance of the tibiofemoral joint due to inserting a pressure sensitive film was not well reported. METHOD: A two-dimensional finite element model of the tibiofemoral joint of knee prosthesis in the sagittal plane was constructed. Four different radii of the femoral component were used to investigate the conformity effect. Two-layers of plane strain element were used to model the pressure sensitive film. The influence of inserting a pressure sensitive film on the actual contact characteristics was analyzed by comparing the results of the change in contact radius. RESULTS: Inserting a pressure sensitive film between contacting surfaces would disturb the original contact behaviors, especially in the lowest conformity design. The maximum difference of contact radius between the model simulating actual contact circumstance and the model with inserting a pressure sensitive film between contacting surface was 77% in the lowest conformity condition at the smallest load. CONCLUSIONS: This study proposes a quantitative analysis of contact characteristics in the tibiofemoral joint of knee prosthesis between the models with and without inserting a pressure sensitive film into the contact surface. The measurement of contact area in artificial tibiofemoral joints by using Fuji pressure sensitive film is always overestimated its true contact area by 14-77%. RELEVANCE: This study revealed the measurement of contact characteristics of artificial tibiofemoral joints by using Fuji pressure sensitive film which depends on not only the applied load, but also the conformity and material properties of the contact surface. Therefore, the information of the conformity and material properties of the contact surface should be provided as well as the applied load wherever a measurement of contact characteristics using Fuji pressure sensitive film is analyzed and interpreted.

Biomechanical Phenomena↗
PubMed2001

The investigation of three-dimensional vibration for piezoelectric rectangular parallelepipeds using the AF-ESPI method.

Electronic speckle pattern interferometry (ESPI) is a powerful tool for the full-field measurement of a deformed body. In this paper, a three-dimensional vibrating block that couples the out-of-plane and in-plane motions is investigated using the amplitude-fluctuation ESPI (AF-ESPI). This method demonstrates the advantages of combining high processing speed, such as in the subtraction method, with high fringe sensitivity, such as in the time-averaged method. The optical system for AF-ESPI is then employed to analyze the volume vibration of piezoelectric material for a rectangular parallelepiped configuration. Based on the fact that fringe patterns measured by the AF-ESPI method appear as a clear picture only at the resonant frequency, both the natural frequencies and the out-of-plane and in-plane vibration mode shapes are successfully obtained in this study. Finally, the impedance analysis as well as the finite element method (FEM) with three-dimensional model are also conducted to compare with the result obtained by AF-ESPI. It is shown that the numerical calculation and the experimental result agree fairly well for both the resonant frequency and the mode shape in three-dimensional configurations.

Journal Article↗
PubMed2001

Vibration characteristics of composite piezoceramic plates at resonant frequencies: experiments and numerical calculations.

The experimental measurement of the resonant frequencies for the piezoceramic material is generally performed by impedance analysis. In this paper, we employ an optical interferometry method called the amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) to investigate the vibration characteristics of piezoceramic/aluminum laminated plates. The AF-ESPI is a powerful tool for the full-field, noncontact, and real-time measurement method of surface displacement for vibrating bodies. As compared with the conventional film recording and optical reconstruction procedures used for holographic interferometry, the interferometric fringes of AF-ESPI are produced instantly by a video recording system. Because the clear fringe patterns measured by the AF-ESPI method will be shown only at resonant frequencies, both the resonant frequencies and corresponding vibration mode shapes are obtained experimentally at the same time. Excellent quality of the interferometric fringe patterns for both the in-plane and out-of-plane vibration mode shapes are demonstrated. Two different configurations of piezoceramic/aluminum laminated plates, which exhibit different vibration characteristics because of the polarization direction, are investigated in detail. From experimental results, we find that some of the out-of-plane vibration modes (Type A) with lower resonant frequencies cannot be measured by the impedance analysis; however, all of the vibration modes of piezoceramic/aluminum laminated plates can be obtained by the AF-ESPI method. Finally, the numerical finite element calculations are also performed, and the results are compared with the experimental measurements. Excellent agreements of the resonant frequencies and mode shapes are obtained for both results.

Letter↗
PubMed2001

Experimental and numerical investigations of resonant vibration characteristics for piezoceramic plates.

Electronic speckle pattern interferometry (ESPI) is a full field, non-contact technique for measuring the surface displacement of a structure subjected to static loading or, especially, to dynamic vibration. In this article we employ an optical system called the amplitude-fluctuation ESPI with out-of-plane and in-plane measurements to investigate the vibration characteristics of piezoceramic plates. Two different configurations of piezoceramic plates, namely the rectangular and the circular plates, are discussed in detail. As compared with the film recording and optical reconstruction procedures used for holographic interferometry, the interferometric fringes of AF-ESPI are produced instantly by a video recording system. Because the clear fringe patterns will be shown only at resonant frequencies, both the resonant frequencies and the corresponding mode shapes are obtained experimentally at the same time by the proposed AF-ESPI method. Excellent quality of the interferometric fringe patterns for both the in-plane and out-of-plane vibration mode shapes is demonstrated. The resonant frequencies of the piezoceramic plates are also measured by the conventional impedance analysis. From experimental results, we find that the out-of-plane vibration modes (type A) with lower resonant frequencies cannot be measured by the impedance analysis and only the in-plane vibration modes (type B) will be shown. However, both the out-of-plane (bending) and in-plane (extensional) vibration modes of piezoceramic plates are obtained by the AF-ESPI method. Finally, the numerical finite element calculations are also performed, and the results are compared with the experimental measurements. It is shown that the numerical calculations and the experimental results agree fairly well for both the resonant frequencies and the mode shapes.

Journal Article↗
PubMed2001

Emergence of reduced susceptibility and resistance to fluoroquinolones in Escherichia coli in Taiwan and contributions of distinct selective pressures.

A survey of 1,203 Escherichia coli isolates from 44 hospitals in Taiwan revealed that 136 (11.3%) isolates were resistant to fluoroquinolones and that another 261 (21.7%) isolates had reduced susceptibility. Resistance was more common in isolates responsible for hospital-acquired (mostly in intensive care units) infections (17.5%) than in other adult inpatient (11.4%; P = 0.08) and outpatient isolates (11.9%; P > 0.1). Similarly, reduced susceptibility was more common in isolates responsible for hospital-acquired infections (30.9%) than in other adult inpatient (21.0%; P = 0.04) and outpatient (21.4%; P = 0.06) isolates. Isolates from pediatric patients were less likely to be resistant (1.3 versus 12.0%; P < 0.01) but were nearly as likely to have reduced susceptibility (17.7 versus 21.9%; P > 0.1) as nonpediatric isolates. There was an inverse relationship in the proportion of isolates that were resistant versus the proportion that had reduced susceptibility among isolates from individual hospitals (R = 0.031; P < 0.05). In an analysis of isolates from two hospitals, all 9 resistant strains possessed double point mutations in gyrA and all 19 strains with reduced susceptibility strains had single point mutations; no mutations were found among fully susceptible strains. Risk factors for resistance included underlying cancer (odds ratio [OR], 83; 95% confidence interval [CI(95)], 7.3 to 2,241; P < 0.001), exposure to a quinolone (OR, undefined; P = 0.02), and exposure to a nonquinolone antibiotic (OR, 20; CI(95), 2.2 to 482; P < 0.001); underlying cancer was the only independent risk factor (OR, 83; CI(95), 8.6 to 807; P < 0.001). There were no significant associations between any of these factors and reduced susceptibility. Whereas acute and chronic quinolone use in cancer patients is a major selective pressure for resistance, other undetermined but distinct selective pressures appear to be more responsible for reduced susceptibility to fluoroquinolones in E. coli.

Adolescent↗
PubMed2001

RT-PCR reveals muscarinic acetylcholine receptor mRNA in the pre-Bötzinger complex.

Muscarinic receptors mediate the postsynaptic excitatory effects of acetylcholine (ACh) on inspiratory neurons in the pre-Bötzinger complex (pre-BötC), the hypothesized site for respiratory rhythm generation. Because pharmacological tools for identifying the subtypes of the muscarinic receptors that underlie these effects are limited, we probed for mRNA for these receptors in the pre-BötC. We used RT-PCR to determine the expression of muscarinic receptor subtypes in tissue punches of the pre-BötC taken from rat medullary slices. Cholinergic receptor subtype M(2) and M(3) mRNAs were observed in the first round of PCR amplification. All five subtypes, M(1)-M(5), were observed in the second round of amplification. Our results suggest that the majority of muscarinic receptor subtypes in the pre-BötC are M(2) and M(3), with minor expression of M(1), M(4), and M(5).

Animals↗
PubMed2001

Role of intraventricular dispersion of early diastolic filling in indicating left ventricular diastolic dysfunction: assessment by color M-mode inflow propagation velocity.

The intraventricular to mitral E velocity ratio (IvE/MvE) and the color M-mode Doppler inflow propagation velocity (LVIPV) were evaluated in 36 healthy controls and 33 patients with hypertension and/or ischemic heart disease. The intraventricular E velocity was significantly lower than the mitral E velocity in the control group (52 vs. 68 cm/s, p < 0.001), but they are similar in the disease group (59 vs. 63 cm/s, p = nonsignificant). Compared with the control group, the disease group had a higher IvE/MvE (0.95 +/- 0.28 vs. 0.78 +/- 0.23, p < 0.01). Nevertheless, the LVIPV was not significantly different between the disease and control groups (53 +/- 14 vs. 56 +/- 13 cm/s, p = nonsignificant). The LVIPV did not correlate with the IvE/MvE (r = 0.202, p = nonsignificant). Therefore, an intraventricular dispersion of early diastolic filling does not seem to indicate impaired left ventricular relaxation.

Adolescent↗
PubMed2001

New advances in lung cancer chemotherapy: topotecan and the role of topoisomerase I inhibitors.

Objective tumor responses and survival rates with standard chemotherapy options for small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC) have been disappointing. However, several promising new classes of agents have emerged in recent years, including the taxanes, mitotic spindle inhibitors, antimetabolites, and topoisomerase I and II inhibitors. The molecular target of several of these new agents is topoisomerase I, an enzyme that is essential for DNA replication and is up-regulated in tumor cells. Inhibition of this enzyme by drugs such as topotecan and irinotecan leads to cell death and is the basis for their anticancer activity. The process of DNA replication is halted by the covalent binding of the drug in a topoisomerase I drug/DNA ternary reaction intermediate. The pharmacokinetics of the approved regimen--a 30-min infusion daily for 5 days at 21-day intervals--are well defined, with proportional increases in the area under the plasma concentration-time curve, peak plasma concentration, and steady state concentration following application of higher doses. The antitumor activities of both the intravenous and oral formulations of topotecan have been tested in clinical trials. Topotecan is well tolerated and has demonstrated good efficacy in patients with relapsed SCLC when administered as monotherapy or in combination regimens as first-line or second-line therapy. Preliminary trials also indicate that topotecan is well tolerated and has activity in the first-line treatment of NSCLC. In this article an overview of new agents in lung cancer chemotherapy is provided, with particular attention paid to the topoisomerase I inhibitors. A review of topotecan--the first topoisomerase I inhibitor to be approved for second-line therapy in SCLC--is presented as an illustration of the promise these new agents hold for the treatment of SCLC and NSCLC.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2001

Corneal melt as the initial presentation of primary Sjögren's syndrome.

Corneal melting is a rare complication of S ogren's syndrome (SS). Previously reported cases of corneal ulceration occurred in patients with established SS, usually secondary to RA. We describe the first case of corneal ulceration with stromal melting as the initial presentation of primary SS. A 79-year-old man without prior sicca symptoms developed a large sterile corneal ulcer that required extensive treatment over several months with ocular lubricants, systemic immunosuppressives, and surgical repair. Evaluation for an underlying connective tissue disease revealed positive antinuclear antibodies (1:640 speckled) and anti-SSA antibody. A lip biopsy established the diagnosis of SS. Ulceration later occurred in the contralateral eye. Two years after the last corneal ulcer and no longer taking prednisone, the patient's ocular disease remained quiescent taking azathioprine 175 mg and hydroxychloroquine 400 mg daily. This case highlights the potential for primary SS to present with serious ocular complications despite lack of a priori sicca symptoms, as well as the importance of immunosuppressive therapy in the treatment of this complication.

Aged↗
PubMed2001

Analysis of estrogenic hormones in municipal wastewater effluent and surface water using enzyme-linked immunosorbent assay and gas chromatography/tandem mass spectrometry.

Although the estrogenic hormones 17 beta-estradiol and 17 alpha-ethinyl estradiol can be quantified in polluted waters by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/tandem mass spectrometry (GC/MS/MS), the compounds often are present at concentrations below detection limits. Enzyme-linked immunosorbent assays (ELISAs) provide a sensitive and robust means of quantifying estrogenic hormones in wastewater effluents and surface waters. Results from ELISA analysis of estrogenic hormones in secondary wastewater effluent indicate concentrations comparable to those that cause vitellogenesis in fish. Confirmatory analyses by GC/MS/MS are consistent with ELISA results. Effluent filtration, using sand filtration or microfiltration, removes approx. 70% of the hormones from secondary effluent, while advanced treatment, using reverse osmosis, removes more than 95% of hormones. The detection limits for estrogenic hormones are approx. 0.1 ng/L in wastewater effluent and 0.05 ng/L in surface water. The ELISA technique provides a relatively simple and practical method of assessing the fate of estrogenic hormones in engineered and natural systems.

Chromatography, High Pressure Liquid↗
PubMed2001

Cystitis glandularis mimics bladder cancer--three case reports and literature review.

Cystitis glandularis is an uncommon proliferative disorder of the mucus-producing glands within the mucosa and submucosa of urinary bladder epithelium. We report three cases with gross hematuria on first presentation. Both sonography and computer tomography revealing bladder tumor and transurethral resection was performed in all three cases. Cystitis glandularis was confirmed by pathology. Short-term follow-up of sonography and cystoscopy showed good results.

Adult↗
PubMed2001

Adult Wilms' tumor associated with polycythemia--a case report.

Both Wilms' tumor (nephroblastoma) in adults and polycythemia in Wilms' tumor are rare. Herein we report an extremely rare case of adult Wilms' tumor associated with polycythemia. A 41-year-old female was incidentally found to have right renal mass by abdominal sonography in a routine health examination. Laboratory examination revealed polycythemia (hemoglobin 20.2 g/dL). Although physical examination was unremarkable, CT scan revealed an homogeneous mass at the middle pole of right kidney, and chest x-ray revealed no metastatic lesions. Right radical nephrectomy was performed smoothly. Grossly, the tumor of 5 x 4.5 x 4.5 cm in size was well circumscribed, and had no vascular structure or collecting system involvement. Microscopic features were consistent with adult nephroblastoma. The post-operative course was uneventful. At follow-up, the patient was well, showed no evidence of recurrence and her hemoglobin level had returned to normal (hemoglobin 14.5 g/dl). We suggest that the relationship between polycythemia and Wilms' tumor should be carefully evaluated before surgical treatment.

Adult↗
PubMed2001

Risk factors for mortality in primary isolated coronary artery bypass grafting surgery.

BACKGROUND AND PURPOSE: Identifying the risk factors for mortality in coronary artery bypass grafting (CABG) surgery is important to improve surgical results. The purpose of this study was to identify the risk factors for mortality in primary isolated CABG in a series of Taiwanese patients. METHODS: Medical records of 914 patients who underwent primary isolated CABG surgery in Veterans General Hospital-Taipei during the period from January 1, 1991, to December 31, 1995, were reviewed. Eighteen clinical and seven operative variables were included in the univariate and multivariate analyses to identify the determinants of mortality in CABG surgery. RESULTS: Thirty-one patients (3.4%) died within 30 days after surgery; 41 (4.5%) died during hospitalization for the procedure. After univariate and multivariate analyses, emergency surgery, history of myocardial infarction, concomitant peripheral artery occlusive disease (PAOD), and prolonged cardiopulmonary bypass (CPB) were found to be significant determinants of mortality in primary isolated CABG. Other variables, including age, sex, angina class, NYHA class, diabetes mellitus, the number of anastomoses, aortic cross-clamp time, stenosis of the left main coronary artery, the number of stenotic coronary arteries, history of congestive heart failure, and a left ventricular ejection fraction less than 35%, were not significant determinants of mortality. Patients undergoing emergency surgery were found to be at highest risk of mortality. CONCLUSIONS: Patients undergoing emergency surgery who had a history of myocardial infarction, concomitant PAOD, or prolonged CPB were at higher risk of mortality in CABG surgery. More comprehensive techniques in myocardial protection, surgical procedures, and postoperative care should be used in the treatment of high-risk patients to reduce mortality.

Aged↗
PubMed2001

The pressure waveform of coronary sinus in human hearts.

BACKGROUND: The pressure waveform of coronary sinus in human hearts has never been well described. Retrograde cardioplegia perfusion has become a popular method of myocardial protection in recent years, and identification of the pressure waveform of the coronary sinus might help intubate the coronary sinus in retrograde cardioplegia perfusion by differentiating it from that of the right atrium. The purpose of this study is to identify the pressure waveform of the coronary sinus. METHODS: We inserted a catheter into the coronary sinus under direct vision via a right atriotomy after completion of open heart operation in eight patients. The pressure waveforms of coronary sinus and central venous line, as well as the electrocardiogram (EKG), were recorded simultaneously after the patient was stable and weaned from the cardiopulmonary bypass. The recorded pressure waveforms of coronary sinus and central venous line were compared. RESULTS: The pressure waveform of coronary sinus was found to have three peaks, more prominent than those of the central venous line waveform. CONCLUSIONS: The pressure waveform of coronary sinus could be distinguished from that of the central venous line. The difference might help coronary sinus cannulation for retrograde cardioplegia perfusion.

Adolescent↗