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Biomedical subjects

C Chen

Publications and source records attributed to C Chen.

1,385 records · Page 77Linked to original sources
PubMedDate not supplied

Inhibition with antisense oligonucleotide suggests that IkappaB-alpha does not form a negative autoregulatory loop for NF-kappaB in mesangial cells.

The IkappaB proteins are important in the regulation of the NF-kappaB/Rel group of transcription factors which are pivotal in the inflammatory response. IkappaB-alpha is itself upregulated by activation of NF-kappaB and is postulated to be part of a negative feedback loop. This role of IkappaB-alpha has been challenged, however, by recent evidence that demonstrates (1) continued activation of NF-kappaB in mesangial and endothelial cells despite the resynthesis of IkappaB-alpha protein and (2) that inhibition of the transactivating activity of NF-kappaB by corticosteroids can be dissociated from a rise in IkappaB-alpha protein. We investigated the role of IkappaB-alpha in mesangial cells using a phosphorothioate antisense oligonucleotide directed against the translational start point of IkappaB-alpha. If IkappaB-alpha does function as a negative feedback inhibitor in these cells, then reducing IkappaB-alpha levels should lead to an increase in NF-kappaB activity. We first demonstrated that IkappaB-alpha protein resynthesis following stimulation could be specifically reduced. We then showed that NF-kappaB DNA binding was not increased with antisense treatment following stimulation. Finally, NF- kappaB-dependent gene signalling after stimulation (determined through an NF-kappaB luciferase reporter and upregulation of the mRNA of known NF-kappaB-responsive genes MCP-1 and IkappaB-alpha) was reduced rather than increased. These data suggest that IkappaB-alpha does not form a negative autoregulatory loop for NF-kappaB in mesangial cells and may actually reduce NF-kappaB activity. This may have relevance to therapies directed at inhibition of NF-kappaB activity in mesangial cell diseases.

Animals↗
PubMedDate not supplied

Seasonal home range changes of the Sichuan snub-nosed monkey (Rhinopithecus roxellana) in the Qinling Mountains of China.

The seasonal changes in home range and habitat use of the Sichuan snub-nosed monkey, Rhinopithecus roxellana, have been studied by radio tracking and direct observation in the Qinling Mountains of China. The home range size was 14.1 km(2) in spring, 9.5 km(2) in summer, 12.1 km(2) in autumn and 12.3 km(2) in winter; the total area used was 22.5 km(2). The area of the home range is closely correlated with the distribution and abundance of food resources. Seasonal change in the home range area is correlated with the phenology of the vegetation. An unusually large home range is a unique characteristic of this monkey.

Animals↗
PubMedDate not supplied

Drinking water source and spontaneous abortion: A cross-sectional study in a rural Chinese population.

The authors examined the association between the risk of spontaneous abortion and the type of drinking water source in a rural Chinese population. Information about pregnancy outcomes and various exposures was collected by means of a detailed interview questionnaire. 2,876 pregnancies occurring in 1989-1993 among 2,201 nonsmoking and non-alcohol-drinking women were analyzed by logistic regression. Generalized estimating equations were used to adjust for correlations between multiple pregnancies in the same woman. The use of pond water as a drinking water source was associated with a higher risk of spontaneous abortion than the use of well or river water (odds ratio, 1.63; 95% confidence interval, 1.11 to 2.39), adjusting for potential confounders. More studies are needed to identify the agents responsible for the observed association. The results of this study emphasize the importance of monitoring potential drinking-water contamination in communities.

Abortion, Spontaneous↗
PubMedDate not supplied

Comparison between electrochemical and optoelectrochemical impedance measurements for detection of DNA hybridization.

The principles of the electrochemical and optoelectrochemical impedance measurements on bare electrolyte/dielectric/semiconductor structures are described. The analysis of the experimental curves allows access to several indications concerning the electrical behavior of such structures. The application of these techniques to follow the electrical behavior of structures modified with two biological systems was investigated. The antibody/antigen recognition did not change the surface charge and, therefore, did not affect the impedance curves with respect to the applied potential. By contrast, the hybridization of two complementary DNA strands on the surface of the structure induced a variation of flat band potential of the semiconductor leading to a shift of impedance curves along the potential axis. This means that it is possible to detect directly the DNA hybridization without the use of labeled probes. The use of light allows the surface to be probed locally. In the future, the application of this technique for direct detection of hybridization on DNA chips should be possible.

Biosensing Techniques↗
PubMedDate not supplied

The effect of dietary lysine deficiency on the immune response to Newcastle disease vaccination in chickens.

The effect of lysine deficiency on chicken immune function was evaluated using broiler chickens fed a diet with lysine at 67% of the control diet (1.24% lysine). The evaluation of humoral immune function was conducted by measuring the antibody production to a live Newcastle disease virus (NDV) vaccination using the hemagglutination inhibition (HI) test and enzyme-linked immunosorbent assay (ELISA). The cellular immune function was evaluated through the use of cutaneous basophil hypersensitivity test. The antibody response to NDV vaccination was reduced in broiler chickens fed a lysine-deficient diet when measured by ELISA but not when measured by HI. The cell-mediated immune response was also reduced by lysine deficiency.

Animals↗
PubMedDate not supplied

Whole-body hyperthermia combined with hyperfractionated irradiation of the thorax in dog: acute physiological response.

Whole-body hyperthermia has potential as an adjuvant treatment with chemotherapy and radiation therapy for diseases such as lung cancer which require both local and systemic control. The acute toxicity of whole-body hyperthermia combined with whole-thorax irradiation was studied in dogs. Twenty-eight dogs received three 2-h whole-body hyperthermia (WBH) treatments at 42.0 degrees C deep rectal temperature. Twenty-four of these dogs were also randomized to receive radiation doses of 18, 22.5, 27, 31.5, 40.5 or 45 Gy. Irradiation was given in 1.5 Gy fractions over 6 weeks. Three WBH treatments were given to 28 dogs with all dogs surviving treatment. WBH was given on days 1, 22 and 40 of the 6-week interval. Thirty-one dogs received radiation doses of 18-49.5 Gy without WBH. Deep rectal temperature was maintained at 41.9 +/- 0.3 degrees C over 2 h with an average of 20 min outside the chamber for irradiation. Two dogs required intervention with emergency medications during WBH treatment. One of the two dogs developed permanent neurological injury. Continuous physiological monitoring was necessary for successful WBH. WBH plus thoracic irradiation was well tolerated. All dogs survived all treatments. A significant but transient increase in peripheral blood leucocytes and a decrease in platelet counts occurred after each WBH treatment. The addition of thoracic irradiation up to 45 Gy in 1.5 Gy fractions did not appear to alter the acute toxicity of WBH with the exception of an increase in the protein content of lung lavage fluids. In conclusion, multiple WBH treatments of 2 h at a target temperature of 42 degrees C in addition to thoracic irradiation up to 45 Gy in 1.5 Gy fractions was administered with only mild acute toxicities occurring. Core temperature could be maintained for up to 20 min outside of the WBH chamber which allowed irradiation to be given concurrently with hyperthermia at a core temperature of 42 degrees C +/- 0.1 degree C.

Animals↗
PubMedDate not supplied

Determination of the need for tricuspid valve replacement: value of preoperative right ventricular angiocardiography.

Of 530 patients undergoing tricuspid valve surgery from January 1, 1961 through December 31, 1987, those 362 patients having had preoperative right ventricular angiocardiography were studied. Mean age was 58.5 years. There were 71 males and 291 females. Tricuspid valve replacement (TVR) was performed in 126 (34.8%), and 236 underwent tricuspid valve repair (65.2%). The predominant pathology was combined tricuspid insufficiency and stenosis in 18 patients (4.9%), and isolated tricuspid insufficiency in 344 (95.1%). There were no complications related to the right ventriculogram. Preoperative angiographic severity of tricuspid valve incompetence was grade 1 in 23 patients (6.4%), grade 2 in 65 (17.9%), grade 3 in 109 (30.1%), and grade 4 in 165 (45.6%). Intraoperative assessment of the severity of tricuspid valve incompetence correlated 72% of the time with the preoperative angiographic assessment, in those patients with more severe degrees of incompetence (grade 3+ or 4+), p (X 2) less than 0.001. Increasing severity of preoperative angiographic triscuspid valve incompetence was associated with the requirement for TVR (vs. repair), p (X 2) = 0.0002. In conclusion, preoperative right ventricular angiography is a useful method for assessing tricuspid valve function and may predict the requirement for TVR in patients undergoing tricuspid valve surgery.

Adolescent↗
PubMedDate not supplied

Small synthetic ligands of the cholecystokinin-B/gastrin receptor can mimic the function of endogenous peptide hormones.

The gastric cholecystokinin-B/gastrin receptor (CCK-BR) is a key regulator of enterochromaffin-like cell function and proliferation. Over the last decade, a number of small non-peptide CCK-BR "antagonists" have been discovered. Here, we demonstrate that some of these non-peptide ligands in fact possess significant ability to activate the human CCK-BR, and are, therefore, more properly categorized as partial agonists. When tested in COS-7 cells transiently expressing the recombinant human CCK-BR, saturating concentrations of the small "peptoid" ligands PD 135,158 and PD 136,450 stimulated inositol phosphate formation to 23 and 43 percent, respectively, of the maximum response induced by a considerably larger endogenous peptide agonist, cholecystokinin octapeptide. In contrast, the benzodiazepine-derived CCK-BR ligand, YM022, acted as a "true" high-affinity antagonist of cholecystokinin-induced inositol phosphate formation (pA2 = 9.69). Consistent with recent findings in animal experiments, our data reveal that small synthetic ligands have the potential to function as either CCK-BR agonists or antagonists. These dual properties of synthetic molecules must be considered when evaluating candidate drugs for human disease.

Animals↗
PubMedDate not supplied

Correlations of serum lipids, uric acid, and albumin among mothers, offspring, and siblings in Taipei, Taiwan.

The purpose of this study was to investigate the correlations of serum lipids, uric acid, and albumin, among mothers (n = 111), offspring (n = 208), and siblings (n = 57) in Taipei, Taiwan. Analytical items included serum triglyceride, serum total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, uric acid, and albumin. Statistical analysis was performed according to the SAS UNIVARIATE procedure; while regression coefficient, parent-offspring regressions, paired-comparison and heritability were estimated. These results show higher heritabilities of four types of serum lipids, uric acid and albumin between mothers and testers (bYX) or siblings (bZX) by parent-offspring regression analysis. Regression coefficients (bYX) of six characters were significantly different (p < 0.05-0.01). Regression coefficients (bZX) for total cholesterol, low-density lipoprotein cholesterol, uric acid, and albumin were significantly different (p < 0.05-0.01), showing the result of genetic control, because their heritabilities were very high at 0.75-1.0, 0.77-1.0, 0.96-1.0, and 0.48-0.82, respectively. This study disclosed that the serum lipids of children in Taipei, Taiwan were significantly correlated with that of parents, which may be attributed to the result of genetic control.

Child↗
PubMedDate not supplied

Review of the development, validation, and application of predictive instruments in interventional cardiology.

Within the last few years, risk assessment has become an integral part of clinical practice, particularly for thoracic surgery and interventional procedures. Risk assessment statistical models are being used in medical decision making, quality improvement tools, and as aids to patient counseling. This literature review was conducted to evaluate the types of predictive models and outcomes measures that have been examined, and methods used in development, validation, and application of these models. A Medline search performed to identify articles (limited to human studies) published in English from 1980 to 1999 resulted in 89 articles, of which 71 were evaluable. Populations studied for model development included patients undergoing coronary artery bypass graft (CABG), percutaneous transluminal coronary revascularization (PTCR), cardiac catheterization, or stenting procedures and patients with angina or stroke. The models were equally developed from a single center versus multicenter and from retrospective databases versus prospective studies. In terms of model perspectives, only three of the models measured cost or cost-effectiveness as the outcome; the remainder considered only clinical outcomes. The most commonly reported types of predictive models were developed using logistic regression and Bayesian techniques, followed by neural networks, rule-based artificial intelligence, simultaneous equation system, and multiple linear regression. Factors to consider when developing or evaluating a predictive model include uniformity of definitions of outcomes, uniformity of definitions of variables, completeness of data, number and frequency of variables, timeliness and source of data, development population characteristics, development and testing (validation) cohorts, and calibration and discrimination. Application of these models to an individual patient can spur quality improvement efforts that can lead to dramatic, system-wide improvements in outcomes.

Cardiovascular Diseases↗
PubMedDate not supplied

Events following implantation of an intraluminal ringed prosthesis in the ascending, transverse, and descending thoracic aorta.

From March 1978 through July 1985, 23 patients underwent implantation of 24 intraluminal ringed prostheses (IRP). There were 18 men and 5 women, with a mean age of 54.7 years, range 15-74 years. Eleven IRP were placed in the ascending aorta, two in the transverse arch, and 11 in the descending aorta. Pathology included acute aortic dissection in four patients, chronic dissection in four, and aortic aneurysm in 16. There were eight hospital deaths (35%). Causes of death included acute cardiac failure in seven patients, and ruptured abdominal aortic aneurysm in one. IRP complications requiring revision included right coronary artery occlusion in three of 11 patients (27%) with an IRP in the ascending aorta. Graft revision was also required in three of 11 IRP implanted in the descending aorta (27%), due to graft occlusion in one and graft stenosis in two. Of the six patients with IRP complications, there were three hospital deaths (50%). All 15 hospital survivors were followed for a mean of 68.5 months, range 5-112 months. There were four late deaths (26.7%). Causes of late death included hemoptysis in one, cardiomyopathy in one, and aortic redissection and rupture in two. We conclude that patients undergoing repair of aortic pathology with IRP have an important risk of early phase events, as technical problems can occur due to malposition and slippage of the securing rings.

Adolescent↗
PubMedDate not supplied

Metabolism of alcohol and ketone by cytochrome P-450 oxygenase: fluoren-9-ol in equilibrium with fluoren-9-one.

Fluoren-9-ol and fluoren-9-one were used as model substrates to study microsomal metabolism of alcohols and carbonyl compounds. It was found that there was an oxidoreductase(s) present in the microsomal preparation that catalyzed interconversion of this alcohol and ketone using pyridine nucleotides as cofactors. The alcohol could also be oxygenated to the ketone by microsomes and NADPH. It required molecular oxygen. This oxygenation was inhibited by SKF 525-A and CO, suggesting the involvement of P-450 oxygenase. Using highly purified P-450 oxygenase components, it was shown that fluoren-9-ol was oxygenated by the complete system to fluoren-9-one. Exclusion of cytochrome P-450 or its reductase resulted in no oxygenation. Dilauroylglyceryl-3-phosphorylcholine was without effect on the reaction. Fluoren-9-one, on the other hand, was reduced to fluoren-9-ol by NADPH-cytochrome P-450 reductase and NADPH. It is suggested that other alcohols and carbonyl compounds are similarly metabolized.

Alcohols↗
PubMedDate not supplied

Aortic arch digital arteriography: an alternative technique to digital venous angiography and routine arteriography in the evaluation of cerebrovascular insufficiency.

Digital arch arteriography is a technique in which the cervicocerebral vasculature is studied by injecting small amounts of contrast material (20 ml or less of diatrizoate meglumine 60%) into the aortic arch. It was used as the initial phase of arteriography in 100 patients with cerebrovascular disease. Five to ten series were obtained in various projections to evaluate the cerebrovascular system. Because suboptimal studies may be repeated, only 3% of carotid bifurcations were suboptimally visualized by digital arch arteriography as compared with 17% by film arch angiography. Intracranial vascular pathology was identified less reliably than with selective angiography. Digital arch arteriography yielded excellent studies in cases when digital venous angiography was suboptimal (20%). Digital arch arteriography may be preferable to digital venous angiography as a screening test in patients with significant cardiac or renal dysfunction because of the lower contrast load.

Aorta, Thoracic↗
PubMedDate not supplied

Post-mortem glycosylated hemoglobin (HbA1c): evidence for a history of diabetes mellitus.

Glycosylated hemoglobin (HbA1c) levels on blood obtained from 28 cadavers were compared with that of healthy volunteers and patients with diabetes mellitus. Levels of HbA1c did not correlate with post-mortem intervals of four to 36 hours, suggesting that HbA1c is stable under these conditions. All deceased with a history of diabetes mellitus, five cases, had an elevated post-mortem blood HbA1c. Twenty-three deceased had a negative history for diabetes mellitus and seven of this group had an elevated HbA1c. These seven cases had diagnosis of malignancies and a history of prolonged exposure to steroids in excess compared to the remaining 16 cases.

Adolescent↗
PubMedDate not supplied

A correlative approach for the identification of antimutagens that demonstrate chemopreventive activity.

Seventy natural and synthetic compounds were tested for potential to inhibit mutation induced by 7,12-dimethylbenz(a)anthracene (DMBA) in Salmonella typhimurium strain TM677. Results were compared with their ability to inhibit DMBA-induced preneoplastic lesions in a mouse mammary gland organ culture system. The response mediated by fifty-five of the test compounds was either positive or negative in both test systems, indicating that the combined use of these assays should aid in the discovery of antimutagenic agents that have cancer chemopreventive potential.

9,10-Dimethyl-1,2-benzanthracene↗
PubMedDate not supplied

Chorea-ballismus with nonketotic hyperglycemia in primary diabetes mellitus.

PURPOSE: To describe the neuroimaging (Ct, MR, and single-photon emission CT [SPECT]) findings in a series of patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus and to correlate the imaging findings with the clinical presentation. METHODS: The neuroimaging and clinical data from 10 patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus were evaluated. Family and drug histories, as well as other causes of chorea, were excluded. All 10 patients had CT, 5 also had MR imaging, and 3 had SPECT examinations. Three had follow-up CT and MR imaging studies, and MR findings were correlated with CT findings in 5 cases. Two experienced neuroradiologists, aware of the diagnosis but blinded to the clinical status of the patients, evaluated all images and reached a consensus as to the final interpretation. RESULTS: CT studies in 9 of 10 patients showed a hyperdense putamen and/or caudate nucleus; in 1, the CT findings were normal. T1-weighted MR images in all 5 patients who had MR imaging (including the patient with a normal CT study) showed hyperintense lesions without significant T2 signal alternation at the basal ganglia. In all 3 of the patients who had SPECT studies of the brain, the scans revealed hypoperfusion at corresponding areas. All 3 follow-up studies depicted resolution of the lesions in the abnormal basal ganglia. Increased hypointensity on T2-weighted and gradient-echo T2*-weighted images was also observed in the sequential MR images. In all patients, the initial side of involvement correlated well with the neuroimaging findings. The chorea resolved within 2 days after treatment of the hyperglycemia in 9 patients. CONCLUSION: In patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus, CT and T1-weighted MR images show unilateral or bilateral lesions of the putamen and/or caudate. SPECT scans show hypoperfusion. These findings may be related to petechial hemorrhage and/or myelin destruction. Early recognition of these imaging characteristics may facilitate diagnosis of primary diabetes mellitus with hyperglycemia and prompt appropriate therapy.

Aged↗