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Biomedical subjects

C C Yang

Publications and source records attributed to C C Yang.

At least 145 records · Page 8Linked to original sources
PubMed1997

Morbidity of dysfunctional voiding syndrome.

OBJECTIVES: External sphincter dyssynergia in the absence of an identifiable causative neurologic lesion (dysfunctional voiding, Hinman-Allen syndrome, non-neurogenic neurogenic bladder) has been known to cause significant morbidity. To determine the outcomes in this syndrome, we conducted a retrospective study of 37 patients referred for urodynamic studies and subsequently diagnosed with dysfunctional voiding. METHODS: After diagnosis, follow-up was conducted through chart review and telephone calls to the primary physicians or the patients. RESULTS: Follow-up was possible in 27 patients (17 female, 10 male; mean follow-up 49 months, range 4 to 192). The average age at diagnosis was 12 years. Eleven patients developed significant or ongoing morbidity. Ten of these 11 patients underwent 17 operations. Eight patients were cured through medication, behavioral modification, intermittent catheterization, and/or other nonoperative treatments. The remaining 8 patients did not experience significant morbidity but did not have resolution of their symptoms as of their last medical evaluation, and most were lost to follow-up. CONCLUSIONS: Dysfunctional voiding resulted in severe morbidity in 11 (40%) of 27 study patients. Eight patients (30%) were cured using nonoperative, conservative treatments, and 8 (30%) had unresolved symptoms within the follow-up period. Urodynamic studies are essential in the diagnosis of the syndrome but cannot be used to consistently predict outcome.

Adolescent↗
PubMed1997

Functional characterization of caudal hypoglossal neurons by spectral patterns of neuronal discharges in the rat.

This study evaluated the spectral characteristics of neuronal discharges in the caudal hypoglossal nucleus and their physiological relevance in adult, male Sprague Dawley rats which were anaesthetized and maintained with pentobarbital sodium. Based on auto-spectral analysis of extracellular single-neuron activity, three spectral patterns were identified in the spontaneous discharges of hypoglossal neurons. Neurons that exhibited a rhythmic pattern manifested a concentrated peak in the auto-spectrogram that corresponded to the mean discharge rate. A majority of hypoglossal neurons displayed the modulated pattern, which was manifested either as scattered power densities (wide-band modulated pattern) or with a peak frequency component that was different from the mean discharge rate (narrow-band modulated pattern). Neurons that exhibited a mixed pattern displayed both rhythmic and modulated spectral patterns. Cross-spectral analysis further revealed that respiratory modulation constituted a major physiological influence on caudal hypoglossal neurons. The respiratory modulated pattern, however, could be converted to a mixed pattern in the presence of a central dipsogen, angiotensin III. The results suggest that the spectral patterns of neuronal discharges in caudal hypoglossal neurons represent manifestations of multiple physiological information, including that regarding respiration and dipsogenesis, which is encoded in these neurons. It was also shown that this information may only be revealed by auto-spectral and cross-spectral analysis of neuronal discharge signals.

Angiotensin III↗
PubMed1997

Effect of growth factors on dermal fibroblast contraction in normal skin and hypertrophic scar.

We have examined the effects of four 'exogenous' growth factors, i.e. PDGF-BB (5 ng/ml), TGF-beta1 (5 ng/ml), bFGF (10 ng/ml) and EGF (10 ng/ml) on the contraction of floating collagen type I lattices populated by human normal skin (NS) and hypertrophic scar (HS) fibroblasts (FPCL). Only TGF-beta1 enhanced the contractility of both NS and HS fibroblasts in the collagen lattice (P < 0.01). Other growth factors (PDGF-BB, bFGF and EGF) did not affect FPCLs contraction at 72 h (P > 0.05). The onset effect of TGF-beta1 on NS-FPCL contraction was relative early at 24 h after FPCL casting as compared to a 72 h delay on HS-FPCL contraction. Besides, PDGF-BB was found to be able to enhance HS-FPCL contraction (P < 0.05) but not on NS-FPCL contraction on day 4. On the other hand, three enzyme-linked immunosorbent assays (ELISA) were performed to demonstrate quantitatively the 'endogenous' growth factors that fibroblasts secreted into the culture medium 48 h after FPCL casting. No appreciable difference was found between 10 NS and 11 HS samples tested for PDGF-AB immunoassay (11.48 +/- 5.5 pg/ml versus 12.20 +/- 5.34 pg/ml). The same result existed in 7 NS and 13 HS samples for TGF-beta2 immunoassay (15.15 +/- 6.2 pg/ml versus 11.84 +/- 7.46 pg/ml). In bFGF immunoassay study, relative variable data was noted in both 7 NS (18.18 +/- 13.18 pg/ml) and 12 HS samples (20.41 +/- 22.36 pg/ml). In conclusion, we suppose that TGF-beta role in wound healing may be due to the secondary exogenous influences. The endogenous ability of TGF-beta2 secretion (quantity) in HS fibroblasts are the same as NS fibroblasts but with delayed timing responses (quality) to exogenous TGF-beta1 effect in the collagen lattice. Further studies with timing-regulated selective specific monoclonal antibodies against the growth factor receptors may provide the therapeutic applications on HS during wound healing.

Becaplermin↗
PubMed1997

Anterior chamber angles shallowing and intraocular pressure after topical pilocarpine.

Pilocarpine has been well recognized as the drug of choice for acute angle-closure glaucoma. The purpose of this study is to clarify quantitatively the change of anterior chamber angle and depth with the passage of time after pilocarpine drop administration. Chamber angles of the four quadrants and chamber depths were measured in 18 normal subjects by Scheimpflug Video Image prior to and 30, 60, and 180 minutes after administration of one drop of 4% pilocarpine in one eye, while the opposite eye served as control. The anterior chamber angle and depth showed a significant shallowing at 30, 60 and 180 minutes after 4% pilocarpine administration with a maximal effect of -3.61 degrees and -0.15 mm at 30 minutes, respectively, while the reduction of intraocular pressure reached its maximal effect at 180 minutes. These facts should be well understood in the treatment of angle-closure glaucoma.

Adult↗
PubMed1997

Generation of infectious virus particles by transient co-expression of human immunodeficiency virus type 1 gag mutants.

We have demonstrated that COS7 cells transiently co-expressing myristylation-defective (Myr-) and protease-defective (PR-) human immunodeficiency virus (HIV) mutants can release infectious virions when co-transfected with an amphotropic murine leukaemia virus envelope protein expression plasmid (SV-A-MLV-env). In contrast, no infectious virions were detected when a PR-, noninfectious HIV gag mutant was co-expressed with the Myr- mutant, although the Myr- mutant could still process the immature core particles in trans. This result indicates that generation of functionally normal Gag proteins is required for virus infectivity in our complementation system. A mutant with a 56-amino-acid deletion in the N-terminal region of the capsid (CA) domain could still complement the PR- mutant to generate infectious virions, suggesting that the deletion mutant could provide a functional protease for processing in the PR- mutant. This result is consistent with the concept that mutations within the N-terminal region of the CA domain have no major effects on Gag-Pol incorporation into particles.

Animals↗
PubMed1997

Processing and intracellular localization of the herpes simplex virus type 1 proteinase.

The herpes simplex virus type 1 (HSV-1) capsid protein VP24 (encoded by UL26) was expressed as a GST-fusion protein and used to prepare a group of monoclonal antibodies. These were used to characterize the protein in capsids and virus infected cells and demonstrated that it exists as two polypeptide species. The nature of the relationship between these two species was investigated and found to be associated with disulphide bonding. Under non-reducing conditions a species corresponding to dimers of VP24 was identified in preparations of B capsids, the site of action of the proteinase. Biochemical subcellular fractionation studies suggested that only cleaved forms of UL26 and UL26.5 gene products could be detected in the nucleus of the infected cell at early times post-infection.

Animals↗
PubMed1997

Cellular recombination pathways and viral terminal repeat hairpin structures are sufficient for adeno-associated virus integration in vivo and in vitro.

The human parvovirus adeno-associated virus (AAV) is unique in its ability to target viral integration to a specific site on chromosome 19 (ch-19). Recombinant AAV (rAAV) vectors retain the ability to integrate but have apparently lost this ability to target. In this report, we characterize the terminal-repeat-mediated integration for wild-type (wt), rAAV, and in vitro systems to gain a better understanding of these differences. Cell lines latent for either wt or rAAV were characterized by a variety of techniques, including PCR, Southern hybridization, and fluorescence in situ hybridization analysis. More than 40 AAV-rAAV integration junctions were cloned, sequenced, and then subjected to comparison and analysis. In both immortalized and normal diploid human cells, wt AAV targeted integration to ch-19. Integrated provirus structures consisted of head-to-tail tandem arrays with the majority of the junction sequences involving the AAV inverted terminal repeats (ITRs). No complete viral ITRs were directly observed. In some examples, the AAV p5 promoter sequence was found to be fused at the virus-cell junction. Data from dot blot analysis of PCR products were consistent with the occurrence of inversions of genomic and/or viral DNA sequences at the wt integration site. Unlike wt provirus junctions, rAAV provirus junctions mapped to a subset of non-ch-19 sequences. Southern analysis supported the integration of proviruses from two independent cell lines at the same locus on ch-2. In addition, provirus terminal repeat sequences existed in both the flip and flop orientations, with microhomology evident at the junctions. In all cases with the exception of the ITRs, the vector integrated intact. rAAV junction sequence data were consistent with the occurrence of genomic rearrangement by deletion and/or rearrangement-translocation at the integration locus. Finally, junctions formed in an in vitro system between several AAV substrates and the ch-19 target site were isolated and characterized. Linear AAV substrates typically utilized the end of the virus DNA substrate as the point of integration, whereas products derived from AAV terminal repeat hairpin structures in the presence or absence of Rep protein resembled AAV-ch-19 junctions generated in vivo. These results describing wt AAV, rAAV, and in vitro integration junctions suggest that the viral integration event itself is mediated by terminal repeat hairpin structures via nonviral cellular recombination pathways, with specificity for ch-19 in vivo requiring additional viral components. These studies should have an important impact on the use of rAAV vectors in human gene therapy.

Base Sequence↗
PubMed1997

Selective activation of vasomotor component of SAP spectrum by nucleus reticularis ventrolateralis in rats.

We evaluated the contribution of the rostral nucleus reticularis ventrolateralis (NRVL) to the vasomotor component in the spectrum of systemic arterial pressure (SAP) signals by quantifying the transfer function between electrical stimulation of this medullary nucleus and the SAP response. Sprague-Dawley rats anesthetized with pentobarbital sodium, paralyzed with pancuronium, and mechanically ventilated were used. Broad-band stimulation of the NRVL with computer-generated rectangular current pulses (10-50 microA, 1 ms), at a mean spike rate of 50 pulses/s and randomized modulation frequency of 0-3 Hz, elicited a site-specific and intensity-related pressor response. Intriguingly, the corresponding autospectrum of SAP signals exhibited prevailing power density only in the lower frequency range (0-0.8 Hz). This low-pass response characteristic was confirmed by the observation that 90% of the total magnitude of transfer function between NRVL stimulation and SAP response concentrated between 0 and 0.6 Hz. The magnitude of NRVL-SAP transfer function was significantly reduced by phentolamine or prazosin but appreciably enhanced by yohimbine. We conclude that the NRVL may contribute to the very-low (0-0.25 Hz)- and low (0.25-0.8 Hz)-frequency components of the SAP spectrum, which are belived to reflect sympathetic modulation on vasomotor activity via alpha-adrenergic neurotransmission.

Adrenergic alpha-Antagonists↗
PubMed1997

Diminished vasomotor component of systemic arterial pressure signals and baroreflex in brain death.

We compared the cardiovascular autonomic regulatory mechanisms between patients with brain death or under a persistent vegetative state and healthy volunteers, based on auto- and cross-spectral analysis of systolic blood pressure (SBP) and interpulse interval (PPI) signals. Brain-dead patients exhibited a significant reduction in the absolute and relative power of the low-frequency (LF; 0.04-0.15 Hz) component in both SBP and PPI spectra, along with appreciable decrease in the very low frequency (VLF; 0.004-0.04 Hz), LF, and high-frequency (HF; 0.15-0.4 Hz) power of the PPI signals. Patients in a persistent vegetative state exhibited a power of the VLF and LF component in the SBP spectrum that was comparable to that in healthy subjects, although a discernible reduction in the VLF, LF, and HF power of the PPI spectrum was manifested by the former group. Assessments with the magnitude of SBP-PPI transfer function and linear regression analysis of beat-to-beat fluctuations in SBP and PPI revealed a progressive decline in spontaneous baroreflex sensitivity from healthy subjects to patients in a persistent vegetative state or with brain death. We conclude that the vasomotor component of systemic arterial pressure signals and spontaneous baroreflex are highly correlated with the functional integrity of the brain stem.

Adult↗
PubMed1997

Midodrine for the treatment of intradialytic hypotension.

Recurrent intradialytic hypotension is probably the most severely disabling feature in dialysis patients and the etiology is multifactorial. We assessed the efficacy and safety of midodrine, a selective alpha1-adrenergic pressor agent in 12 patients with recurrent intradialytic hypotension. Symptomatic intradialytic hypotension was defined as hypotensive symptoms occurring with a systolic blood pressure < 100 mm Hg or with 25% decrease in systolic blood pressure in those patients with a basal systolic blood pressure of 100 mm Hg. The patients who suffered from symptomatic intradialytic hypotension and failed to improve after cautious body weight adjustment were included into the study. The lowest intradialytic and postdialysis blood pressures were monitored for 18 consecutive dialysis sessions before and after midodrine treatment. Clinical signs and symptoms were also recorded during both periods. With midodrine, the mean (+/- SE) lowest systolic and diastolic blood pressure increased significantly from 68.7 +/- 3.1 and 42.8 +/- 2.0 mm Hg to 84.7 +/- 3.9 and 52.7 +/- 2.7 mm Hg respectively during the study (p < 0.01). Midodrine treatment also significantly increased postdialysis systolic and diastolic blood pressures from baseline values of 90.8 +/- 3.8 and 58.3 +/- 3.0 mm Hg to 113.3 +/- 7.1 and 70.6 +/- 3.1 mm Hg (p < 0.01 and p < 0.01 respectively). In addition, oral administration of midodrine also significantly decreased the total volume of intravenous fluid administered during symptomatic hypotension. The clinical signs and symptoms during dialysis were improved in all patients. There were no differences in hemoglobin, serum albumin, urea, creatinine, fasting blood sugar or volume removed per dialysis between both periods of the study. In conclusion, our study has demonstrated that midodrine is a safe and effective treatment for the prevention of recurrent intradialytic hypotension if routinely premedicated before each dialysis session.

Administration, Oral↗
PubMed1997

Scombroid fish poisoning: an overlooked marine food poisoning.

Scombroid fish poisoning is a food-borne chemical intoxication caused by certain spoiled fish that contain a large amount of histamine and some biogenic diamines. It has gradually become a world-wide medical problem and probably is the most common cause of fish poisoning. As the data on the incidents of scombroid fish poisoning in Taiwan remains scarce, we report 2 incidents of scombroid fish poisoning in Northern Taiwan. We collected data of the 2 outbreaks of suspected fish poisoning which were reported to us in 1996. An epidemiological investigation was undertaken. Questionnaire interviews were given to persons who ate lunch in the same cafeteria in outbreak 2. The leftover fish were sent for species identification and toxin analysis. The first incident involving 4 women occurred in March 1996. All cases experienced flush, dizziness, blurred vision and skin rashes after eating lunch. A non-scombroid fish of Makaira with histamine levels as high as 84.13 mg/100 g flesh was implicated in this incident. In August 1996, another incident involving some cases who ate lunch at the same cafeteria were investigated. A total of 146 questionnaires were distributed with a return of 132 questionnaires (90.4%). Fifty-five employees reported positive signs or symptoms; 48 persons who ate fish and 7 women who did not eat fish were ill. Fish was the only food associated with the illness with an attack rate of 73.8% (p < 0.001). The incriminated fish was later identified as a scombroid fish of Euthynnus with a histamine content of 271.9 mg/100 g flesh in 1 leftover piece and 118.5 mg/100 g flesh in another piece. Most cases in these 2 outbreaks received treatment with antihistamines and had rapid and complete recovery. The diagnosis of scombroid fish poisoning could be misdiagnosed as food allergy or bacterial food poisoning if physicians are not aware of such poisoning. The nonspecific but characteristic symptomatology of histamine food poisoning and previous consumption of fish should alert physicians to the possibility of scombroid fish poisoning. Unless complicated with shock or respiratory distress, supportive treatment with antihistamines usually concludes with a good prognosis. Toxin analysis of the fish flesh remains the most important step in approaching a confirmed diagnosis.

Adolescent↗
PubMed1997

Peritoneoscintigraphy using Tc-99m MAA for diagnosis of diaphragmatic disruption in a peritoneal dialysis patient.

Massive hydrothorax is an infrequent but well-recognized complication of continuous ambulatory peritoneal dialysis (CAPD), and is often regarded as a contraindication to its use. We describe here a patient with massive hydrothorax that appeared during CAPD. Peritoneoscintigraphy was performed to demonstrate the clinical suspicion of a pleuroperitoneal communication and the pleurodesis using tetracycline was commenced and this allowed the successful continuance of CAPD.

Female↗
PubMed1996

Predicted combustion product deposition in the human airway.

Fires involving modern polymeric materials produce toxic vapours and particles of widely varying composition and size depending on available oxygen and localized temperatures. Adverse health effects of inhaled combustion-generated particles depend on physiological interactions at the airway deposition site. The present work is a theoretical investigation into the importance of airway humidity and temperature profiles, initial particle size, particle size distribution and ionic concentration on airway particle deposition. A modified numerical model accounting for hygroscopic particle growth was used to predict airway deposition of 0.1-10.0 microm mass median aerodynamic diameter (MMAD) particles. Dynamic humidity profiles were generated with an unsteady state model of heat and water vapour transport. Results suggest that for hygroscopic particles < 2.0 microm, MMAD dynamic end-inspiratory humidity profiles produce up to 250% greater predicted nasopharyngeal deposition than steady state humidity profiles. Assuming combustion products are hygroscopic, these results also suggest that less pulmonary deposition will occur than previously predicted. In addition, higher upper airway concentrations of combustion products may have significant health consequences independent of pulmonary deposition patterns.

Computer Simulation↗
PubMed1996

Increase of nitric oxide synthases and nitrotyrosine in inclusion-body myositis.

To investigate the possible role of nitric oxide (NO)-induced 'oxidative stress' in the pathogenesis of inclusion-body myositis (IBM), we immunostained muscle biopsies of 12 patients with IBM with isoform-specific antibodies against the neuronal and inducible forms of nitric oxide synthase and with antibodies against nitrotyrosine. Between 70 and 80% of IBM vacuolated muscle fibers contained inclusions strongly immunoreactive with all three antibodies, which by immuno-electronmicroscopy co-localized mainly to cytoplasmic paired-helical filaments, and also to amorphous structures and floccular material. Excess intracellular NO can combine with superoxide to produce highly reactive peroxynitrite which can nitrate tyrosines of proteins. The presence of nitrotyrosine is indicative of NO-induced "oxidative stress'. Our data suggest that this mechanism may play a pathogenic role in IBM.

Enzyme Induction↗
PubMed1996

Rifampicin: an inhibitor of Xp12-specific protein phosphorylation in Xanthomonas oryzae pv. oryzae.

Phosphorylation of the three Xp12-specific phosphoproteins was drastically reduced by rifampicin, an antibiotic that specifically inhibits the host-cell RNA polymerase. However, this inhibitory effect could not be found in spontaneous mutants of Xanthomonas oryzae pv. oryzae whose RNA polymerase are resistant to the drug. The inhibitory effect of rifampicin treatment also resulted suppression of the Xp12 multiplication cycle. This implies the physiological significance of this effect and supports our previous prediction that phosphorylation plays an important role in the life cycle of Xp12. The acid- and alkali-labile character of the Xp12-specific phosphoproteins and the chemical stability of the phosphoryl linkages show that the corresponding protein kinase catalyzes the formation of an acyl phosphorylation. Subsequent fractionation of cell lysate revealed that the phosphoproteins were located in the periplasm. Actinomycin D, which affects transcription through DNA condensation rather than its binding to RNA polymerase, was not able to cause the inhibition effect. On the other hand, cerulenin was found to reduce the acyl phosphorylation which hints at a possible role of cell membrane in the phosphorylation. Here we present the evidence for the functional involvement of the rifampicin treatment on protein phosphorylation. A possible mechanism of rifampicin on the alternation of acyl phosphorylation is proposed.

Anti-Bacterial Agents↗
PubMed1996

Antioxidation of human low density lipoprotein by unconjugated and conjugated bilirubins.

We demonstrate here that both unconjugated bilirubin (Bu) and conjugated bilirubin (Bc) can protect human low density lipoprotein(LDL) against oxidation by oxyradicals generated by 2,2'-azo-bis (2 amidinopropane) dihydrochloride at 37 degrees. The oxidation was assessed by agarose gel electrophoresis and was further corroborated by assaying the malondialdehydes and lipid peroxides formed throughout oxidation. On a per mole basis, Bu and less so Bc was more effective than ascorbate in preventing LDL oxidation. Since oxidative modification of human LDL was implicated in plaque formation in blood vessels leading to atherogenesis, the data suggested that either bile pigment may help reduce the risk of atherogenesis.

Amidines↗