Biomedical subjects

C C Yang

Publications and source records attributed to C C Yang.

At least 217 records · Page 12Linked to original sources

PubMed1994

Comparison of intravenous dipyridamole and adenosine Tc-99m MIBI myocardial imaging for detection of coronary artery disease.

A total of 44 patients referred for Tc-99m MIBI myocardial imaging for detection of coronary artery disease (CAD) were studied to compare the differences in heart beat, blood pressure, electrocardiographic changes and side effects during intravenous infusion of dipyridamole (ID) and adenosine (IA) and also to determine the degree of concordance between ID and IA Tc-99m MIBI imaging. These patients were divided into two groups: 20 suspected CAD patients constituted group I and 24 proven CAD patients formed group II. All patients received ID 0.56 mg/kg for 4 min and within about 10 days IA 0.14 microgram/kg/min for 6 min with Tc-99m MIBI imaging. The results revealed that maximal heart beat increased and maximal systolic blood pressure decreased in both IA and ID patients with no statistically significant differences. Transient second-degree AV block occurred with IA in 3 patients. Side effects, such as, chest pain, headache, dizziness and shortness of breath occurred more often and were in general more intense in IA patients, but they were typically mild and resolved spontaneously within 1 or 2 min of discontinuation of IA. Both IA and ID Tc-99m MIBI imaging were normal in 18 of 20 group I patients and were concordant for the presence of perfusion defects in the other 2 patients. Of 24 group II patients, all had myocardial perfusion defects on both tests and were concordant for the severity of the perfusion abnormalities. However, in other 2 patients. Of 24 group II patients, all had myocardial perfusion defects on both tests and were concordant for the severity of the perfusion abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗

PubMed1993

Solution conformation of cobrotoxin: a nuclear magnetic resonance and hybrid distance geometry-dynamical simulated annealing study.

The solution conformation of cobrotoxin has been determined by using proton nuclear magnetic resonance spectroscopy. With the combination of various two-dimensional NMR techniques, the 1H-NMR spectrum of cobrotoxin was completely assigned (Yu et al., 1990). A set of 435 approximate interproton distance restraints was derived from nuclear Overhauser enhancement (NOE) measurements. These NOE constraints, in addition to the 29 dihedral angle constraints (from coupling constant measurements) and 26 hydrogen bonding restraints (from the pattern of short-range NOEs), form the basis of 3-D structure determination by the hybrid distance geometry-dynamical simulated annealing method. The 23 structures that were obtained satisfy the experimental restraints, display small deviation from idealized covalent geometry, and possess good nonbonded contacts. Analysis of converged structures indicated that there are two antiparallel beta sheets (double and triple stranded), duly confirming our earlier observations. These are well defined in terms of both atomic root mean square (RMS) differences and backbone torsional angles. The average backbone RMS deviation between the calculated structures and the mean structure, for the beta-sheet regions, is 0.92 A. The mean solution structure was compared with the X-ray crystal structure of erabutoxin b, the homologous protein. This yielded information that both structures resemble each other except at the exposed loop/surface regions, where the solution structure seems to possess more flexibility.

Cobra Neurotoxin Proteins↗

PubMed1993

Mitochondrial DNA variants observed in Alzheimer disease and Parkinson disease patients.

Mitochondrial DNA (mtDNA) variants associated with Alzheimer disease (AD) and Parkinson disease (PD) were sought by restriction endonuclease analysis in a cohort of 71 late-onset Caucasian patients. A tRNA(Gln) gene variant at nucleotide pair (np) 4336 that altered a moderately conserved nucleotide was present in 9/173 (5.2%) of the patients surveyed but in only 0.7% of the general Caucasian controls. One of these patients harbored an additional novel 12S rRNA 5-nucleotide insertion at np 956-965, while a second had a missense variant at np 3397 that converted a highly conserved methionine to a valine. This latter mutation was also found in an independent AD + PD patient, as was a heteroplasmic 16S rRNA variant at np 3196. Additional studies will be required to determine the significance, if any, of these mutations.

Aged↗

PubMed1993

Separation and characterization of the A chain and B chain in beta 1-bungarotoxin from Bungarus multicinctus (Taiwan banded krait) venom.

The interchain disulfide bond between A chain and B chain of beta 1-bungarotoxin (beta 1-Bgt) was selectively cleaved by dithiothreitol, and the A and B chains were separated by HPLC. The separated A and B chains did not show detectable enzymatic activity and lethal toxicity, but exhibited an immunoreactivity with anti-beta 1-Bgt antibody. Analytical isoelectrofocusing revealed that the A chain is a neutral subunit with pI = 7.4, and the B chain is a basic one with pI = 9.6. The A chain exhibited a Ca(2+)-binding ability as revealed by fluorescence measurement. Moreover, fluorescence studies showed that the intact interchain disulfide bond is essential for maintaining the hydrophobic character of substrate binding site in beta 1-Bgt and stabilizing the architectural environment of Trp-19 in the A chain. However, combination of the A chain and B chain failed to restore the biological activities and physiochemical properties which the intact beta 1-Bgt possessed. These, together with our previous result that the Trp-19 of the A chain is involved in substrate binding, suggest that the integrity of the interchain disulfide bond favors the maintenance of the active conformation of beta 1-Bgt.

Anilino Naphthalenesulfonates↗

PubMed1993

Structural determinants of the intrinsic fluorescence emission in notexin and phospholipase A2 enzymes.

Fluorescence measurements of the homologous proteins, notexin and PLA2 enzymes from Naja naja atra, Naja nigricollis, and Hemachatus haemachatus venoms, showed that the wave-length of maximum emission and the quantum yield of their intrinsic fluorescence emission spectra were different. To verify the factors which affected their fluorescence characteristics, the dynamics of tryptophan residues in those homologous proteins were studied by quenching with acrylamide, iodide, and cesium. The degrees of exposure of tryptophanyl groups in notexin and PLA2 enzymes assessed by acrylamide quenching were found to be the major factor that determined their fluorescence characteristics. However, the positively charged groups surrounding tryptophan residues of PLA2 enzymes from N. naja atra and N. nigricollis venoms might affect the quantum yield of their fluorophores. Tryptophan residues of notexin were in an environment with less fluctuation, which did not allow free diffusion of ionic quencher. This might render its tryptophan residues to fluoresce at a shorter wavelength. These results suggested that the structural determinants affecting the intrinsic fluorescence emission of homologous proteins can be easily assessed by quenching studies.

Acrylamide↗

PubMed1993

Unsustained dipsogenic response to chronic central infusion of angiotensin-III in spontaneously hypertensive rats.

We evaluated the chronic effect of angiotensin-III (AIII) in the promotion of drinking behavior in spontaneously hypertensive (SH) and normotensive Wistar-Kyoto (WKY) rats, using conscious, freely moving, male, adult animals that had been instrumented with an intracerebroventricular (icv) cannula connected to an osmotic mini-pump for 7-day infusion. Chronic icv infusion of AIII (5 or 10 pmol/min) elicited robust, dose-dependent, and Ile7-AIII (100 pmol/min; as specific antagonist)-reversible dipsogenesis in both SH and WKY rats, with higher water intake in the former strain. However, the drinking response in the SHRs exhibited a sharp drop after 3 days of AIII infusion, during which acute AIII (80 pmol, icv) challenges also failed to induce dipsogenesis. Chronic icv infusion of bestatin (150 pmol/min), an aminopeptidase-B inhibitor, did not by itself discernibly affect basal drinking. When combined with AIII (5 or 10 pmol/min), however, bestatin, respectively, suppressed and augmented the dipsogenic response of SH and WKY rats to the heptapeptide. These results suggest that chronic administration of AIII did not produce sustained drinking behavior in SHRs, possibly because of the development of early desensitization of the angiotensin receptors.

Aminopeptidases↗

PubMed1993

Renin suppressibility and blood pressure response during acute sodium loading in patients with essential hypertension.

Sequential changes in renin-aldosterone secretions and blood pressure (BP) response during acute sodium (Na) loading were studied in 50 patients with essential hypertension (EH) and nine normotensive volunteers. Following an infusion of 2 L of isotonic saline at a rate of 500 mL/h, plasma renin activity (PRA) and the plasma aldosterone concentration (PAC) were similarly suppressed, while sodium excretion appreciably increased in hypertensive as well as normotensive subjects. When patients were divided into two subgroups according to the extent of renin suppression, 26 were classified as adequate responders with the proportion of decrement of PRA at the end of the infusion exceeding 50% of the baseline values, while 24 were inadequate responders with a decrement of less than 50%. The extent of renin suppression was consistently greater in adequate responders than in inadequate responders throughout the course of infusion. Adequate responders also had a higher pre-saline PRA and attained a smaller post-saline natriuretic response than inadequate responders. Although the mean BP in both subgroups remained stable at all periods, inadequate responders had a minor but significantly higher percent of increment of MBP at the end of the infusion than adequate responders (3.6 +/- 2.0 vs -1.7 +/- 1.4%, p < 0.05). These results suggest that renin suppressibility during acute Na loading may be either linked with maintenance of BP homeostasis or may merely reflect the sodium-volume status of essential hypertension, with patients with greater suppression of renin being more Na-volume resistant than those with less inhibition.

Adult↗

PubMed1993

Pyogenic liver abscess in Taiwan: emphasis on gas-forming liver abscess in diabetics.

Ninety-seven cases of pyogenic liver abscesses in a 4-yr period were studied: 27.8% (27 cases) were associated with biliary tract stone, 5.2% (five cases) were associated with biliary tract cancer, and there were two cases of diabetes (2.1%) associated with anal infection, but 63.9% (63 cases) were diagnosed as cryptogenic. Forty patients (64.5%) in the cryptogenic group had diabetes mellitus, and 23 of them (23/40, 57.5%) had gas-forming infection. All patients received parenteral antibiotics therapy, percutaneous aspiration, drainage, or operation. The overall mortality was 16.5%. Diabetes mellitus alone, without demonstrable infectious foci, was an important predisposing factor for pyogenic liver infection. Furthermore, to evaluate the clinical importance of gas-forming pyogenic liver infections, we separated these 42 diabetic patients into gas-forming and non-gas-forming groups, after sonography and CT scan. Klebsiella pneumoniae was the major pathogen in both groups. There was no significant difference in the clinical manifestations, complication, bacterial culture, or laboratory data between these two groups, except that the AST level was higher in the gas-forming group. However, the gas-forming group had higher mortality rate (30.4% vs. 5.3%). Gas-forming liver abscesses were common among the diabetics. Early and adequate drainage for pyogenic liver abscesses with parenteral antibiotics are crucial in their management.

Causality↗

PubMed1993

Tracheal deviation: an unusual complication of platysma myocutaneous flap.

Reconstruction of the intraoral defect caused by tongue cancer was done for a patient by using a platysma myocutaneous flap. The relatively short neck, scar contracture, and inactive movement of the involved side of the neck resulted in tracheal deviation, an unusual complication not appearing in previous reports. In order to avoid airway problems during intubation, the surgeon and anesthestist should seriously consider the possibility of this rare complication in patients who have had the platysma myocutaneous flap technique. Careful preoperative evaluation and skillful intubation of the fiberoptic bronchoscope are demanded in cases where next general anesthesia is needed.

Adult↗

PubMed1993

Management of windshield facial injuries.

Between Jan. 1986 and Dec. 1990, 99 patients with automobile windshield facial injuries were hospitalized in Kaohsiung Medical College hospital. All patients were injured by old type windshields in car accidents. Seventy-three patients (74%) were male and twenty-six (26%) were female. Ages ranged from 6 to 62 years (mean age 31 years). Fifty-seven patients (58%) were car drivers and forty-two (42%) were front seat passengers. All patients had typical multiple U-shaped lacerations on the face. The major injury sites were localized to the upper one third of the face. The wounds were repaired immediately after careful debridement. A total of 21 facial bone fractures were noted. All were open fractures with large, deep avulsion wounds. Displaced and comminuted fractures received reduction and fixation before wound closure. Three patients had cranial bone fracture with no displacement. Brain edema and subarachnoid hemorrhage were found by brain CT scan in two and one patients respectively. They were treated conservatively. In one patient with frontal sinus fracture the glass pieces penetrated into the brain. The foreign bodies were removed from the brain and frontal sinus. Eyeball rupture was found in 16 patients, including two patients in whom both eyes were involved. Eight eyeballs needed immediate evisceration and ten eyeballs received reparation. Blindness occurred in all these patients. Of the 99 patients in this study, 15% sustained additional injury. Most were wounds on the extremities. Because serious injuries can be caused by the old type of windshields, it should be abandoned. Driving with the seat belt fastened is the best way to insure safety.

Accidents, Traffic↗

PubMed1992

Nonidentical DNA-binding sites of endonuclease NaeI recognize different families of sequences flanking the recognition site.

NaeI endonuclease uses a two-site binding mechanism to cleave substrate DNA: reaction-rate studies imply that occupancy of the second DNA site causes an allosteric change in the protein that enables DNA cleavage at the first site [Conrad, M., & Topal, M. D. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 9707-9711]. Measurements of relative binding affinities for 14-base-pair DNA fragments containing the NaeI recognition sequence GCCGGC and various flanking sequences showed that the two DNA-binding sites are not identical. G.C-rich flanking sequences were preferred by the activator binding site, whereas A.T-rich flanking sequences were preferred by the substrate binding site: GGGTGCCGGCAGGG was preferred 8-fold more by the activator site but 14-fold less by the substrate site than TTTCGCCGGCGTTT. Substitution of pyrimidine or 7-deazapurine for purine immediately 3' to GCCGGC reduced DNA affinity for only the activator site by up to 26-fold, implying that the activator DNA-binding site requires N-7 base contacts immediately flanking GCCGGC. The implications of nonidentical DNA-binding sites, one of which binds a specific DNA site to allosterically activate the other, are discussed.

Allosteric Regulation↗

PubMed1992

Inhibition of lymphocyte proliferation by liver arginase.

The activities of thymidine kinase and uridine kinase (enzymes for pyrimidine salvage pathway) in phytohemagglutinin (PHA)--prestimulated lymphocytes were inhibited by arginase in a similar pattern to the inhibition on thymidine incorporation. Further study revealed that arginase did not directly affect the activities of these enzymes in the cell-free system. Thymidine kinase and uridine kinase activities of PHA-prestimulated lymphocytes were inhibited by arginase making their activities as low as that cultured in arginine-free RPMI-1640 medium. These results suggest that arginine-depletion in the culture medium is the primary mode of action of arginase on the inhibition of mitogen-stimulated lymphocyte proliferation.

Animals↗

PubMed1992

Immunochemical properties of Naja naja atra (Taiwan cobra) phospholipase A2 using polyclonal and monoclonal antibodies.

The immuno-chemical properties of Naja naja atra phospholipase A2 (NNA-PLA2) were studied by using the chemically modified PLA2 derivatives and the PLA2 homologues toward anti-NNA-PLA2 polyclonal and monoclonal antibodies. Anti-NNA-PLA2 polyclonal antibodies inhibited the enzymatic activity of NNA-PLA2 and Hemachatus haemachatus DE-I by 87% and 68%, respectively. However, the enzymatic activities of Naja nigricollis CMS-9 and notexin were not significantly affected by the polyclonal antibodies. Competitive enzyme immunoassay revealed that the affinity of NNA-PLA2 for polyclonal antibodies was 330-fold higher than that of Hemachatus haemachatus DE-I. Naja nigricollis CMS-9 and notexin failed to inhibit the binding of NNA-PLA2 to polyclonal antibodies. This implies that the epitope(s) of NNA-PLA2 might comprise some substituted residues in the sequence of PLA2 homologues. Three monoclonal antibodies against NNA-PLA2 were prepared by a hybridoma technique. Two of these monoclonal antibodies inhibited the enzymatic activity of NNA-PLA2, but the other did not. Removal of the N-terminal octapeptide affected the epitope interacting with these monoclonal antibodies. Selective modification of tyrosine residues at positions 3 and 63 or lysine residues at positions 6 and 65 induced a substantial reduction in affinity of NNA-PLA2 for polyclonal and monoclonal antibodies. The three monoclonal antibodies failed to recognize PLA2 homologues. The comparison of the sequence of NNA-PLA2 to those of PLA2 homologues showed that most of the amino acid substitutions of PLA2 homologues occur in the spatially nearby region of the N-terminal region and residues at positions 63 and 65.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Native American mitochondrial DNA analysis indicates that the Amerind and the Nadene populations were founded by two independent migrations.

Mitochondrial DNAs (mtDNAs) from 167 American Indians including 87 Amerind-speakers (Amerinds) and 80 Nadene-speakers (Nadene) were surveyed for sequence variation by detailed restriction analysis. All Native American mtDNAs clustered into one of four distinct lineages, defined by the restriction site variants: HincII site loss at np 13,259, AluI site loss at np 5,176, 9-base pair (9-bp) COII-tRNA(Lys) intergenic deletion and HaeIII site gain at np 663. The HincII np 13,259 and AluI np 5,176 lineages were observed exclusively in Amerinds and were shared by all such tribal groups analyzed, thus demonstrating that North, Central and South American Amerinds originated from a common ancestral genetic stock. The 9-bp deletion and HaeIII np 663 lineages were found in both the Amerinds and Nadene but the Nadene HaeIII np 663 lineage had a unique sublineage defined by an RsaI site loss at np 16,329. The amount of sequence variation accumulated in the Amerind HincII np 13,259 and AluI np 5,176 lineages and that in the Amerind portion of the HaeIII np 663 lineage all gave divergence times in the order of 20,000 years before present. The divergence time for the Nadene portion of the HaeIII np 663 lineage was about 6,000-10,000 years. Hence, the ancestral Nadene migrated from Asia independently and considerably more recently than the progenitors of the Amerinds. The divergence times of both the Amerind and Nadene branches of the COII-tRNA(Lys) deletion lineage were intermediate between the Amerind and Nadene specific lineages, raising the possibility of a third source of mtDNA in American Indians.

Asian People↗

PubMed1992

Mitochondrial DNA complex I and III mutations associated with Leber's hereditary optic neuropathy.

Four new missense mutations have been identified through restriction analysis and sequencing of the mitochondrial DNAs (mtDNA) from Leber's hereditary optic neuropathy (LHON) patients who lacked the previously identified 11778 mutation. Each altered a conserved amino acid and correlated with the LHON phenotype in population and phylogenetic analyses. The nucleotide pair (np) 13708 mutation (G to A, ND5 gene) changed an alanine to a threonine and was found in 6/25 (24%) of non-11778 LHON pedigrees and in 5.0% of controls, the np 15257 mutation (G to A, cytochrome b gene) changed an aspartate to an asparagine and was found in 4 of the 13708-positive pedigrees and 0.3% of controls, the np 15812 mutation (G to A, cytochrome b gene) changed a valine to a methionine and was detected in two of the 15257-positive pedigrees and 0.1% of controls and the np 5244 mutation (G to A, ND2 gene) changed a glycine to a serine and was found in one of the 15812-positive patients and none of 2103 controls. The 15257 mutation altered a highly conserved amino acid in an extramembrane domain of cytochrome b that is associated with the ligation of the low potential b566 heme and the 5244 mutation altered a strongly evolutionarily conserved region of the ND2 polypeptide. The 13708 and 15812 mutations changed moderately conserved amino acids. Haplotype and phylogenetic analysis of the four np 15257 mtDNAs revealed that all harbored the same rare Caucasian haplotype and that the np 13708, np 15257, np 15812 and np 5244 mutations were added sequentially along this mtDNA lineage. Since the percentage of sighted controls decreases as these mutations accumulate, it appears that they interact synergistically, each increasing the probability of blindness. The involvement of both mitochondrial complex I (np 5244, 11778, 13708) and complex III (np 15257, 15812) mutations in LHON indicates that the clinical manifestations of this disease are the product of an overall decrease in mitochondrial energy production rather than a defect in a specific mitochondrial enzyme.

Base Sequence↗

PubMed1992

The adipofascial turnover flap for elbow coverage.

Closure of soft tissue defects in the vicinity of the elbow with exposed bone or joint remains a difficult problem. Local adipofascial turnover flaps covered by a skin graft were successfully used to reconstruct two elbow defects. The flap's base was placed 1.5 to 2.0 cm from the wound edge. The flap-to-base area ratio, which is an important index of flap survival, in addition to the traditional length-to-width ratio were 3.25 and 3.3, respectively. The undermined skin of the flap donor site was preserved rather than discarded as in the conventional deepithelialized turnover flap. The primary benefits of this flap are that it is an easy and rapid one-stage procedure, it requires limited immobilization of the involved joint, and it leaves an inconspicuous donor site scar. The motion of the elbow joint was not impeded because the adiposal component of the flap faced the exposed vital structures. The padding is not thick, but is sufficient to cover and protect the elbow. The flap is especially indicated for small- to medium-sized, complicated elbow wounds.

Accidents, Traffic↗

PubMed1992

[Dipyridamole Tc-99m MIBI myocardial perfusion scintigraphy in patients with post-infarction chest pain symptom].

To evaluate the efficacy of stress Tc-99m MIBI myocardial perfusion imaging using intravenous dipyridamole in detecting coronary artery disease (CAD) and to determine if chest pain symptom is a proper index for detection of myocardial ischemia in post-infarction patients, we observed 73 cases (65 men, 8 women, 38-79 years old) between Sept. 1990 and May 1992. All patients were suffered from old myocardial infarction (MI) evidenced by history and ECG and were divided into two groups: group I involving 41 patients with post-infarction chest pain symptom and group II including 32 patients without post-infarction chest pain symptom. Among them, 19 (group IA) of group I and 11 (group IIA) of group II received coronary arteriography (CAG) for comparison. Of the 41 group I post-infarction chest pain patients, 17 suffered from old anterior or antero-septal wall (AW) MI, 21 from old inferior wall (IW) MI, 1 from old lateral wall (LW) MI and 2 from combined old AW and IW (AIW) MI by ECG. All 17 patients with AWMI suffered from AW perfusion defect (7 were MI, 10 were MI with ischemia) but 7 of them from multivessel disease (MVD) by Tc-99m MIBI. All 21 patients with IWMI suffered from IW perfusion defect (9 were MI, 12 were MI with ischemia) but 13 of them from MVD by Tc-99m MIBI. Of the patient with LWMI and 2 patients with AIWMI suffered from MVD by Tc-99m MIBI. Of the 32 group II post-infarction patients without chest pain symptom, 12 suffered from old AWMI, 14 from old IWMI, 2 from old LWMI, 3 from AIWMI and 1 from ALWMI by ECG. Of the 12 patients with AWMI, 11 suffered from AW perfusion defect (6 were MI, 5 were MI with ischemia) but 1 of them from MVD by TC-99m MIBI. All 14 patients with IWMI suffered from IW perfusion defect (12 were MI, 2 were MI with ischemia) but 4 of them from MVD by Tc-99m MIBI. Of the 2 patients with LWMI suffered from LW infarction by Tc-99m MIBI. Of the 3 patients with AIWMI and 1 with ALWMI suffered from MVD by Tc-99m MIBI. Of the 11 patients in group IA and 5 patients in group IIA with AWMI, CAG revealed the incidence of infarct-related recanalization of LAD was 9/11(82%) and 4/5(80%) respectively and the respective incidence of MVD was 6/11(55%) and 0/5(0%).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1992

A mitochondrial DNA variant, identified in Leber hereditary optic neuropathy patients, which extends the amino acid sequence of cytochrome c oxidase subunit I.

A G-to-A transition at nucleotide pair (np) 7444 in the mtDNA was found to correlate with Leber hereditary optic neuropathy (LHON). The mutation eliminates the termination codon of the cytochrome c oxidase subunit I (COI) gene, extending the COI polypeptide by three amino acids. The mutation was discovered as an XbaI restriction-endonuclease-site loss present in 2 (9.1%) of 22 LHON patients who lacked the np 11778 LHON mutation and in 6 (1.1%) of 545 unaffected controls. The mutant polypeptide has an altered mobility on SDS-PAGE, suggesting a structural alteration, and the cytochrome c oxidase enzyme activity of patient lymphocytes is reduced approximately 40% relative to that in controls. These data suggest that the np 7444 mutation results in partial respiratory deficiency and thus contributes to the onset of LHON.

Amino Acid Sequence↗