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Biomedical subjects

C L Cheng

Publications and source records attributed to C L Cheng.

At least 37 records · Page 2Linked to original sources
PubMed1999

Lamellar corneal autograft for corneal perforation.

BACKGROUND: Corneal perforation secondary to exteriorization of the haptic foot of the anterior chamber intraocular lens (IOL) is a rare complication in IOL surgery. CASE REPORT: A superior penetrating corneal defect developed in the right eye of a 74-year-old woman associated with exteriorization of the superior haptic of an anterior chamber IOL. METHODS: We describe the technique of repositioning and successful patching of the defect using a lamellar cornea-sclera rotational autograft. CONCLUSIONS: This technique is useful for small perforations when cornea donor tissue is not available.

Aged↗
PubMed1999

Effect of capsaicin on the micturition reflex in normal and chronic spinal cord-injured cats.

The effect of capsaicin (10-80 mg/kg sc) on reflex activity of the urinary bladder was examined in anesthetized normal as well as anesthetized and awake chronic spinal cord-injured (SCI) cats. In normal cats, capsaicin elicited a transient increase in the frequency of isovolumetric bladder contractions and reduced the volume threshold for inducing micturition, but did not depress the amplitude of bladder contractions or the reflex firing on bladder nerves. In anesthetized SCI cats, capsaicin depressed reflex bladder activity and firing on bladder nerves. In awake SCI cats, capsaicin initially decreased the volume threshold for inducing micturition; however, after a delay of 3-6 h the volume threshold increased and intravesical voiding pressure decreased. This effect persisted for 4-12 days. It is concluded that capsaicin-sensitive C fiber bladder afferents are not involved in initiating reflex micturition in normal cats, but play an essential role in triggering automatic micturition in chronic SCI cats. The results are consistent with the clinical data indicating that C fiber bladder afferents contribute to bladder hyperactivity and incontinence in patients with neurogenic bladder dysfunction.

Animals↗
PubMed1999

A cross-sectional survey of physical activity among middle aged women in Singapore.

OBJECTIVES: To assess the extent to which middle-aged women in Singapore engage in physical activity of a level which would result in long-term health benefits, and to determine the factors associated with this. METHODS: We conducted a cross-sectional survey of women aged between 35 and 60 years residing in Marine Terrace. A standardised questionnaire incorporating a modified Seven-Day Recall Questionnaire was used to record the level and type of physical activity engaged in over the past week. Demographic information and factors promoting or discouraging sports and exercise were also elicited. The total energy expenditure for household, occupational and sports activities of moderate intensity and above was calculated using metabolic equivalents (METs) in kcal/kg/week. RESULTS: Of the 341 respondents, 50.7% reported engaging in at least moderate activity for 30 minutes or more every day during the past week, thus fulfilling the WHO recommendations on physical activity. Housework contributed significantly to the energy expenditure on these activities among our target population. After adjusting for age, body mass index and educational level, we found that housewives without domestic help were most likely to fulfill the WHO recommendations. Housewives or working women with domestic help were the two groups at highest risk of low physical activity. A lack of time was the reason most commonly cited for not engaging in sports or exercise. CONCLUSION: Studies assessing physical activity in relation to disease risk among women should include domestic work in addition to the traditional leisure-time activities. There is a scope for further efforts to improve the level of activity in this population, which could be facilitated by the support of health professionals, employers and family members.

Adult↗
PubMed1998

DNA short tandem repeat profiling of Chinese population in Taiwan determined by using an automated sequencer.

We performed a population study on a Taiwan population using a set of nine short tandem repeat (STR) loci and the amelogenin locus. Allele and genotype frequencies of the STR systems D3S1358, vWA, FGA, TH01, TPOX, CSF1PO, D5S818, D13S317 and D7S820 were determined by polymerase chain reaction followed by automated sequencer analysis. A total of 80 alleles could be observed, using all systems, in a population of 500 individuals. No new intermediate fragments were found in these systems. Allele frequencies showed no deviation from the Hardy-Weinberg equilibrium. The mean exclusion power (MEP) ranged from 0.294 for TPOX to 0.711 for FGA (the combined MEP was > 0.999), the discriminating power (DP) ranged from 0.782 for TPOX to 0.964 for FGA, (the combined DP was > 0.99999999949).

Alleles↗
PubMed1998

Incidental renal cell carcinoma: pathologic features and survival rate.

BACKGROUND: The aim of this study was to compare outcomes in patients with symptomatic and incidental renal cell carcinoma (RCC). METHODS: From October 1982 to December 1996, 200 patients with RCC were enrolled in this study. Their medical records were reviewed for symptoms, tumor stage, and lymph node and metastatic status. Symptomatic and incidental RCCs were compared by the overall survival rate of patients. The survival rate was determined by the Kaplan Meier method. Log rank testing was used to analyze the statistical difference in the survival period between both groups. RESULTS: The proportion of incidental RCC was 21% (42/200). The majority of cases (73.8%) were diagnosed primarily by abdominal ultrasonography. Incidental RCCs were smaller in size than symptomatic RCCs (5.1 +/- 2.0 cm vs. 7.5 +/- 1.8 cm, p = 0.001). Incidental RCCs were of a lower stage, and patients with incidental RCCs had significantly longer overall survival rates than those with symptomatic RCCs (p < 0.001). CONCLUSIONS: Ultrasonography is a useful tool for the detection of incidental RCC. Improvement in the overall survival rate of incidental RCC patients suggests that when these tumors are identified earlier, treatment results are better.

Adult↗
PubMed1998

Assessment of protein conformation in human benign and malignant astrocytomas by reflectance Fourier transform infrared microspectroscopy.

The secondary structure and composition of protein in the tissues of benign and malignant astrocytomas were determined by reflectance Fourier-transform infrared (FT-IR) microspectroscopy. The peak maximum of IR spectra of the tissues from recurrent malignant astrocytoma markedly appeared at higher frequency (1655 or 1663 cm(-1)), which was significantly different from that of the tissues from benign astrocytoma at 1651 cm(-1) and tissues from malignant astrocytoma at 1652 cm(-1). Malignant astrocytoma indicated slightly different compositions in the protein secondary structure from benign astrocytoma. However, a significant increase in beta-turn structure but a marked decrease in beta-sheet and random coil structures were observed in the protein secondary structure of the recurrent malignant astrocytoma. The phenomenon was more pronounced in recurrent malignant astrocytoma pretreated with radiation and chemotherapy. The rapid cell proliferation and cell differentiation of malignant astrocytoma with or without recurrence might be the possible explanations for the different compositions of protein conformational structures.

Adult↗
PubMed1998

Tumor angiogenesis and metastasis: correlation in invasive renal cell carcinoma.

BACKGROUND: Experience suggests that tumor growth is dependent on angiogenesis. The intensity of angiogenesis in human cancer is reported to be predictive of the probability of metastasis in many types of cancer. The aims of this study were 1) to determine the relationship of microvessel density (MVD) in renal cell carcinoma to pathologic stage, and 2) to evaluate the role of MVD in metastasis. METHODS: Paraffin-embedded tumor specimens were reviewed from 34 unselected patients with RCC who had undergone surgery from 1986 to 1990 at Taichung Veterans General Hospital. The pathology findings and clinical records were reviewed to note relationships between pathologic stage and whether or not metastasis had occurred. Specimens were studied from 16 cases (eight Stage I cancers, five Stage II and three Stage III) without metastasis and from 18 cases (two Stage I, six Stage II, six Stage III and four Stage IV) in which metastasis later developed. Microvessels were highlighted by immunostaining endothelial cells for factor VIII-related antigen. Microvessels were counted in a x-400 field (0.1885 mm2/field) in the most active areas of neovascularization. RESULTS: The 16 patients without metastasis have survived for between 65 and 136 months (mean, 94.5 months), up to the present time. Of the 18 patients with metastasis, 15 died and three survived, with mean survivals of 42.8 months (range, 12-99 months). Mean overall MVD was 99.6 vessels; mean MVD was 98.5, 96.2, 109.3 and 90.0 in Stages I, II, III and IV tumors, respectively. Mean MVD was 99.3 in patients without metastasis and 99.9 in patients with metastasis. CONCLUSIONS: MVD does not correlate with pathologic stage and is of no prognostic significance in renal cell carcinoma.

Adult↗
PubMed1997

Steady-state pharmacokinetics of delavirdine in HIV-positive patients: effect on erythromycin breath test.

OBJECTIVE: The steady-state kinetics of delavirdine and desisopropyldelavirdine were evaluated in human immunodeficiency virus-positive patients after escalating oral doses and after repeated oral administrations at the same dose level. STUDY DESIGN: Patients (n = 8 males) were given escalating oral doses of delavirdine mesylate, in a sequential fashion, over 14 days for phases 1 (200 mg every 8 hours), 2 (300 mg every 8 hours), and 3 (400 mg every 8 hours). Control patients (n = 4 males) were given 300 mg oral doses of drug every 8 hours for all three phases. Hepatic CYP3A activity was evaluated with the erythromycin breath test (ERMBT). RESULTS: In the escalating-dose group, delavirdine displayed nonlinear kinetics as indicated by the decreasing oral clearance, maximum steady-state plasma concentration/minimum steady-state plasma concentration ratio, and log-linear terminal rate constant, as well as by increasing half-life at higher doses; the ratio of desisopropyl-delavirdine formation clearance to elimination clearance was also reduced. In the control group, the kinetics of delavirdine and desisopropyl-delavirdine were unchanged. Plasma protein binding was linear for delavirdine in the escalating-dose and control groups; on average, the fraction unbound was about 2.3% and 2.0%, respectively. Hepatic CYP3A activity was markedly reduced after short- and long-term exposure to all doses of delavirdine mesylate. Delavirdine could maximally inhibit 70% to 75% of predose ERMBT values, with an IC50 of about 0.9 mumol/L. CONCLUSION: Delavirdine is a potent and reversible inhibitor of hepatic CYP3A; it is also a substrate for this CYP450 isoform. It is likely that delavirdine will exhibit drug-drug interactions when coadministered with other CYP3A substrates.

Administration, Oral↗
PubMed1997

Sequences necessary for nitrate-dependent transcription of Arabidopsis nitrate reductase genes.

Nitrate increases the transcription of the two Arabidopsis thaliana nitrate reductase genes. We demonstrated previously that 238 and 330 bp of the 5' flanking regions, designated as NP1 and NP2, of the two nitrate reductase genes NR1 and NR2, respectively, are sufficient for nitrate-dependent transcription (Y. Lin, C.-F. Hwang, J.B. Brown, C.-L. Cheng [1994] Plant Physiol 106: 477-484). Here we identify the cis-acting elements of NP1 and NP2 that are necessary for nitrate-dependent transcription by linker-scanning (LS) analysis. In transgenic plants one LS mutant of NP1 and two LS mutants of NP2 exhibited significantly lower nitrate-induced reporter gene chloramphenicol acetyltransferase activity. To distinguish which of these three mutants lost nitrate inducibility, competitive reverse-transcriptase polymerase chain reaction was used to measure the chloramphenicol acetyltransferase mRNA levels before and after nitrate induction. The single LS mutant in NP1 lost its response to nitrate, whereas the two LS mutants in NP2 partially lost their response to nitrate. A 12-bp sequence is conserved between the NP1 site and the two NP2 sites. This sequence motif is also conserved in the 5' flanking regions of other nitrate-inducible plant genes. Gel mobility shift experiments indicate that these three regions bind to similar proteins. The binding is constitutive with respect to nitrate treatment and was observed in both nonphotosynthetic suspension cells and green leaves.

Arabidopsis↗
PubMed1997

A chlorate-resistant mutant defective in the regulation of nitrate reductase gene expression in Arabidopsis defines a new HY locus.

Light acts both directly as a signal and indirectly through photosynthesis to regulate the expression of genes encoding nitrate reductase (NR). Here, we report the isolation and characterization of a novel chlorate-resistant mutant that is defective in the regulation of NR gene expression. The response of NR2, but not NR1 or the gene encoding nitrate reductase (NiR), to light signals was impaired in this Arabidopsis mutant, designated cr88. In addition to NR2, the light regulation of the genes encoding the chlorophyll a/b binding protein (CAB) and the small subunit of ribulose bisphosphate carboxylase (RBCS) was also impaired in this mutant. These results suggest that the pathway through which light regulates the expression of NR2, CAB, and RBCS genes is different from those that regulate the expression of NR1 and NiR. An examination of the deetiolation process under different light spectrum showed that cr88 is defective in red light-mediated deetiolation. Complementation tests with various long hypocotyl (hy) mutants indicated that CR88 identifies a new HY locus. The possible functions of CR88 are discussed.

Arabidopsis↗
PubMed1997

Detrusor-sphincter dyssynergia induced by cold stimulation of the urinary bladder of rats.

Instillation of cold water into the urinary bladder has been used as a diagnostic test to evaluate neurogenic dysfunctions of the lower urinary tract (LUT). This study examined the effects of cold stimulation on the LUT of urethan-anesthetized rats. Urinary bladder pressure and external urethral sphincter (EUS) electromyogram (EMG) were recorded during cystometrograms in which body- or room-temperature saline was infused continuously into the bladder and voided through the urethra. Subsequent infusion of cold saline (6-8 degrees C) into the bladder increased by approximately 100% the duration and amplitude of supraspinal reflex bladder contractions, increased baseline bladder pressure, increased the pressure threshold for inducing micturition, and increased EUS EMG activity. Blocking EUS activity by transecting the pudendal nerves or by administering a neuromuscular blocking agent markedly reduced or eliminated the effect of cold stimulation. Capsaicin pretreatment suppressed the effect of cold stimulation. It is concluded that cold temperatures stimulate capsaicin-sensitive C fiber bladder afferents that reflexly activate the EUS, producing detrusor and sphincter dyssynergia and increasing urethral outlet resistance. This in turn increases the amplitude and duration of bladder contractions during voiding.

Acclimatization↗
PubMed1996

Fluid percussion brain injury in the developing and adult rat: a comparative study of mortality, morphology, intracranial pressure and mean arterial blood pressure.

Changes in intracranial pressure (ICP) and mean arterial blood pressure (MABP) were measured for 30 min following an experimental fluid percussion traumatic brain injury in postnatal day 17 (P17), P28 and adult rats. Under enflurane anesthesia the left femoral artery was cannulated for MABP measurements and a 20 gauge needle was stereotaxically positioned into the right lateral ventricle for ICP measurements. Three different injury severities (mild: 1.35-1.45 atm, moderate: 2.65-2.75 atm, severe: 3.65-3.75 atm) were delivered over the left parietal cortex to each of the age groups. The biomechanical/physiological results indicated that fluid percussion generated reproducible traumatic brain injuries in the developing rat. Furthermore, with increasing injury severity the physiological responses (in terms of ICP and MABP) became more pronounced, resulting in a corresponding increase in mortality (mild, moderate, severe, respectively, P17: 27%, 36%, 100%; P28: 33%, 30%, 75%; adult: 0%, 20%, 55%). Compared to adult animals, developing rats exhibited pronounced hypotension in response to closed head injury, which most likely explains the greater percent mortality among the younger animals. The utilization of this model will allow for future studies addressing the consequences of traumatic brain injury when it is sustained early in development.

Analysis of Variance↗
PubMed1996

Possible changes in secondary structure and composition of human lens capsules in hereditary congenital cataract.

BACKGROUND: Scanty information is available on the changes in conformational structure and composition of human lens capsule in cases of hereditary congenital cataract. The purpose of this study was to use Fourier-transformed infrared (FT-IR) spectroscopy to determine the secondary structure and composition of hereditary cataractous human lens capsule, as compared with normal human lens capsule. METHODS: FT-IR spectroscopy with the Fourier self-deconvolution and curve-fitting program was performed, and second-derivative analysis was used to verify the peak positions and assignments of the IR spectra. RESULTS: The curve-fit FT-IR spectra revealed that the content of hydroxylysine and arginine were clearly higher in the lens capsule of the hereditary congenital patient, but the content of aspartic acid significantly lower, than in normal human lens capsules. The secondary conformational changes in alpha-helix, triple helix and random coil structures were important findings in the lens capsule of a hereditary cataractous patient. CONCLUSION: Possible alterations in secondary structures and compositions of lens capsule are observed in the hereditary congenital cataractous patient by using FT-IR spectroscopy with curve-fitting and second-derivative analysis.

Adult↗
PubMed1996

Progressive changes in secondary conformation and composition of the senile cataractous human lens capsules.

The lens capsules of senile cataractous patients were differentiated into three progressive grades of immature (I, II and III) and two progressive grades of mature (I' and II') groups using Fourier transform infrared (FT-IR) microspectroscopy with Fourier self-deconvolution and curve-fitting algorithms, according to the changes in IR peak position and its structural composition. The secondary conformation of both immature-II and mature-I' cataractous human lens capsules was found to change significantly when enhancing the beta-sheet structure but simultaneously decreasing the beta-turn structures, as compared with the composition of normal human and immature-I cataractous lens capsules. The increase in beta-sheet structural proportion might possibly be attributable to the age-related cataractogenesis. We also found that the IR peak at 1651 cm-1 assigned to a-helix shifted to 1647 cm-1 that corresponded to disordered structure, but the IR peak at 1662 cm-1 due to beta-turn structure disappeared and another new IR peak assigned to alpha-helix structure appeared at 1656 cm-1, for both immature-III and mature-II' cataractous lens capsules. It increased the compositions of beta-sheet and disorder structures and simultaneously decreased the triple helix and beta-turn structures, but maintained the same level in alpha-helix structure. This suggests that FT-IR microspectroscopy can act as a potential tool to exactly differentiate the maturity of senile cataractous human lens capsules according to the changes in IR peak position and compositions in amide I band.

Adult↗
PubMed1995

Effect of diabetic duration on the secondary structures of the human lens capsules in diabetic cataracts.

The decrease in triple helix content from 16% to 9% and in beta-turn content from 45% to 33%, combined with markedly increased random coil structure (16%) can be found in the secondary structure contents of lens capsule of the premature cataractous patients with longer diabetic history. However, almost the same peak position and secondary structure content are observed in the curve-fitted IR amide I band of lens capsules of both non-diabetic controls and premature cataractous patients with shorter diabetic history, even if the cataracts are senile. The present study emphasizes the duration of diabetes as a major cause to alter the secondary conformation of the cataractous human lens capsules in diabetic patients.

Adult↗
PubMed1995

Expression of Aequorea green fluorescent protein in plant cells.

The coding region of the green fluorescent protein (GFP) from Aequorea victoria has been fused to the cauliflower mosaic virus 35S promoter and introduced into maize leaf protoplasts. Transient expression of GFP was observed. In addition, the coding region of GFP was fused to an Arabidopsis heat shock promoter and co-transformed with another construct in which GFP has been replaced with chloramphenicol acetyltransferase (CAT). The heat-induced expression of GFP in maize protoplasts parallels that of CAT. While GFP was expressed in both dark-grown and green maize leaf protoplasts, no green fluorescence was observed in similarly transformed Arabidopsis protoplasts.

Arabidopsis↗