Biomedical subjects

J F Chen

Publications and source records attributed to J F Chen.

At least 55 records · Page 3Linked to original sources

PubMed1999

The induction of liver microsomal cytochrome P450 by Glycyrrhiza uralensis and glycyrrhetinic acid in mice.

The effect of Glycyrrhiza uralensis Fisch (GRZ) aqueous extract and one of its active principles Glycyrrhetinic acid (GRT) on hepatic cytochrome P450 in mice were investigated. Oral administration of GRZ at 10 g/kg/d or GRT at 50 mg/kg/d for 7 days was found to increase the P450 contents up to 4.6 fold compared with the controls. The activities of aryl hydrocarbon hydroxylase (AHH, 3.1 and 3.3 fold), aminopyrine N-demethylase (ADM, 4.2 and 3.2 folds), and 7-ethoxycumarin O-deethylase (ECOD, 2.8 and 2.5 fold) were also shown to be increased. Western blot analysis showed that the subtypes of P450 isoforms induced selectively by GRZ and GRT included CYP1A1 (1.8 and 1.5 fold over that of the control, respectively), CYP2B1 (both 1.3 fold), and CYP2C11 (3.2 and 3.0 fold). Moreover, significant positive correlation between the P450 content or the isoforms and the corresponding enzyme activities mentioned above was observed.

Animals↗

PubMed1999

Identification of familial hypercholesterolemia in Taiwan: report of eleven cases.

BACKGROUND: Familial hypercholesterolemia is associated with a very high risk of premature coronary heart disease. In order to identify cases of familial hypercholesterolemia in Taiwan, we screened the hyperlipidemic patients in our metabolic clinics. METHODS: Hyperlipidemic patients were screened in the metabolic outpatient department and the cases which fulfilled the clinical criteria of definitive or possible familial hypercholesterolemia were further analyzed. Their clinical characteristics, including age, gender, physical findings, past history of coronary heart disease or cerebrovascular accident (CVA), family history, and lipid profiles before and after medical treatment, were reviewed. RESULTS: Eight women and 3 men fulfilled the diagnostic criteria. The mean age at diagnosis was 51.1 +/- 11.9 years old. Tendon xanthomas were found in 5 patients with definitive familial hypercholesterolemia. Coronary heart disease was confirmed in one patient and old CVA was noted in another 2 patients. The mean total cholesterol level was 390.3 +/- 88.9 mg/dl and the mean low density lipoprotein-cholesterol (LDL-cholesterol) level was 309.6 +/- 89.9 mg/dl before treatment. After a mean treatment duration of 45.2 months, the mean total cholesterol level and LDL-cholesterol level were 326.8 +/- 87.8 mg/dl and 249.1 +/- 91.1 mg/dl, respectively. CONCLUSION: Clinically diagnosed familial hypercholesterolemia indeed exists in Taiwan. As compared to other reports, the mean age at diagnosis in our series was older and the majority of patients were women. Most patients were not vigorously treated and the family members were not thoroughly screened. Adequate treatment of patients with familial hypercholesterolemia in clinical practice and screening their family members are crucial in preventing new or recurrent coronary heart disease.

Adult↗

PubMed1998

Nasopharyngeal carcinoma presenting as an intracranial abscess.

BACKGROUND: There are many conditions related to brain abscess. Brain abscesses resulting from nasopharyngeal carcinoma is rare. It is unusual for an intracranial abscess to appear as the initial clinical presentation of nasopharyngeal carcinoma. CASE REPORT: A 43-year-old male patient suffering from nasopharyngeal carcinoma with the initial manifestation of an intracranial abscess without symptoms and signs suggestive of the primary nasopharyngeal carcinoma is reported. The diagnosis was particularly elusive and was not made until the third admission. CONCLUSION: Although it is rare, intracranial abscess should be considered as one of the possible manifestations of nasopharyngeal carcinoma.

Adult↗

PubMed1998

Estimating the spatial autocorrelation function for ultrasound scatterers in isotropic media.

The autocorrelation function pertaining to spatial distributions of ultrasonic scatterers in soft tissue is believed to contain useful information related to tissue morphology. A simple processing method applied to radio-frequency echo signals estimates this function for a sample having isotropic scattering conditions. It utilizes backscattered echo signals from the sample and echo signals from a reference object having defined scattering properties. The ratio of the echo signal power spectrum from the sample to the echo signal power spectrum from the reference object is obtained, and corrected for attenuation differences between the two media. This yields a "form factor" for the sample, whose inverse Fourier transform is the autocorrelation function. The method was tested using tissue-mimicking samples for which spatial autocorrelation functions could be modeled from the dimensions of embedded scatterers. The shapes of the measured autocorrelation functions were in reasonable agreement with those estimated, although measured functions overestimated the function at small lag distances. Scatterer diameters estimated from the zeros of the autocorrelation function agreed to within 6% of expected values when the measurement system bandwidth satisfied minimal criteria.

Humans↗

PubMed1997

Transplantation of microencapsulated PC12 cells provides long-term improvement of dopaminergic functions.

The purpose of this study is to examine if microencapsulated PC12 cells may provide long term effects to the hemiparkinsonian rats. A modified technique was used to encapsulate PC12 cells into gelled microspheres. We found that the PC12 cells can survive in the modified microcapsules in vitro. Most of the PC12 cells formed cluster 3 weeks after incubation. The PC12 cell-loaded microcapsules were also examined in vitro. Adult Sprague-Dawley rats, anesthetized with chloral hydrate, were injected unilaterally with 6-hydroxydopamine into the medial forebrain bundle. The effectiveness of this lesion was tested by measuring apomorphine or methamphetamine-induced rotation one month after lesioning. The unilaterally lesioned rats were transplanted with microencapsulated PC12 cells. Results showed that apomorphine and methamphetamine-induced rotations were greatly suppressed after transplantation. One year after the grafting, the animals were anesthetized with urethane for the voltammetric study. Low dose of KCl was directly injected into the grafted striatum through pressure microejection. We found that KCl-induced DA release, as measured by voltammetric techniques, was regenerated in the striatum. The animals were later sacrificed for histological examination. We found that capsules were present in the lesioned striatum one year after grafting. Most of the capsules contained no PC12 cell. However, some capsules were filled entirely with PC12 cells. Taken together, our data suggested that PC12 cells can survive in the capsule in vitro and may provide long-term dopaminergic effects to the hemiparkinsonian rats.

Animals↗

PubMed1997

Effect of infection brain edema on NMDA receptor binding in rat brain in vivo.

The purpose of this study was to determine the effect of infection brain edema (IBE) in the rat model induced by injecting pertussis bacilli (PB) into the left carotid artery. The specific binding of N-methyl-D-aspartate (NMDA) receptor with [3H] MK-801 was measured in the neuronal membrane of cerebral cortex. The Scatchard plots were performed. The Bmax values were 0.623 +/- 0.082 and 0.606 +/- 0.087 pmol/mg protein in the group that received normal saline (NS) and PB respectively (P < 0.05). The Kd values were 43.1 +/- 4.2 and 30.5 +/- 3.0 nM in the groups NS and PB respectively. The results indicated that the affinity of NMDA receptor was significantly higher in the group PB than group NS, whereas the total number of NMDA receptors had not changed in the IBE model. The increase of affinity of NMDA receptor can be blockaded by MK-801 pretreatment in vivo.

Animals↗

PubMed1997

Conditional, tissue-specific expression of Q205L G alpha i2 in vivo mimics insulin action.

Deficiency of the G protein subunit G alpha i2 that is known to mediate the inhibitory control of adenylylcyclase impairs insulin action [11]. Using the promoter for the phosphoenolpyruvate carboxykinase gene, conditional tissue-specific expression of the constitutively active mutant form (Q205L) of G alpha i2 was achieved in mice harboring the transgene. Expression of Q205L G alpha i2 was detected in liver and adipose tissue of transgenic mice. Whereas the G alpha i2 deficient mice displayed blunted glucose tolerance, the Q205L G alpha i2 expressing mice displayed enhanced glucose tolerance. Hexose transport and the recruitment of GLUT4, but not GLUT1, transporters to the membrane were elevated in adipocytes from Q205L G alpha i2 expressing mice in the absence of insulin. Additionally, hepatic glycogen synthase was found to be activated in Q205L G alpha i2 expressing mice, in the absence of the administration of insulin. Serum insulin levels in transgenic mice fasted overnight were equivalent to those of their control littermates. These data demonstrate that much as G alpha i2 deficiency leads to insulin resistance, expression of Q205L constitutively active G alpha i2 mimics insulin action in vivo, reflecting a permissive role of G alpha i2 in signaling via this growth factor receptor tyrosine kinase linked pathway.

Adipocytes↗

PubMed1997

Correlation of fine needle aspiration cytology and frozen section biopsies in the diagnosis of thyroid nodules.

AIMS: To evaluate the correlation of fine needle aspiration (FNA) cytology and frozen section biopsy in the diagnosis of thyroid nodules. METHODS: The medical records of 662 patients who underwent FNA cytology of the thyroid and thyroid surgery were analysed. Frozen section biopsies were taken from 586 of the 662 patients. The diagnostic correlations of FNA cytology, frozen section, and both FNA cytology and frozen section with definitive histological assessment were evaluated. RESULTS: Among the 662 patients who received FNA cytology, there were 356 cases (53.8%) diagnosed as benign, 114 cases (17.2%) as malignant, 148 cases (22.4%) as indeterminate, and 44 cases (6.6%) as unsatisfactory. The positive predictive value for the detection of malignancy by FNA cytology was 92.1% and the negative predictive value was 95.2%. The incidence of malignancy in the indeterminate cytological diagnosis was 23%. The diagnosis from frozen sections was benign in 445 cases (75.9%), malignant in 134 cases (22.9%), and deferred in 7 cases (1.2%). By frozen section, the positive and negative predictive values were 97% and 95.5%, respectively. Diagnostic accuracy up to 98% was achieved when FNA cytology and frozen section diagnoses were in agreement. No false positives were observed when FNA cytology and frozen sections were both positive for malignancy. When FNA cytology and frozen section diagnoses were discordant, frozen section showed a higher accuracy (78.9%) than FNA cytology (21.1%). In the face of an indeterminate or unsatisfactory cytological diagnosis, the diagnostic accuracy of frozen sections reached 92.6%. CONCLUSIONS: The results confirm that FNA cytology is a useful tool in the initial evaluation of thyroid nodules. Intraoperative frozen section is a valuable procedure to confirm the cytological diagnosis and identify malignancy in patients with indeterminate or unsatisfactory cytological diagnosis. With reliance on frozen sections as an intraoperative guide of thyroid surgery, the possibility of unnecessary extensive surgery and the need for the second operation are considerably lower.

Biopsy, Needle↗

PubMed1997

Glomerular transforming growth factor-beta1 mRNA as a marker of glomerulosclerosis-application in renal biopsies.

As transforming growth factor-beta1 (TGF-beta1) is implicated in the pathogenesis of glomerulosclerosis, the aim of the study was to demonstrate if levels of glomerular TGF-beta1 mRNA in renal biopsies correlated with glomerulosclerosis. Glomeruli were collected by microdissection from renal biopsies in patients with membranous nephropathy, lupus nephritis, diabetic nephropathy, minimal change disease and IgA nephropathy presented by proteinuria when serum creatinine was <3 mg%. Glomerular mRNAs were reverse transcribed and TGF-beta1, alpha2(IV) collagen, beta-actin cDNA quantitated by competitive polymerase chain reaction (PCR). By semiquantitative electron microscopy, a 3.5-fold increase of glomerular TGF-beta1/beta-actin mRNA ratio in the moderate sclerotic group (n = 23, p < 0.01) and a 1.5-fold increase in the mild sclerotic group (n = 22, p < 0.05) were observed when compared to the minimal sclerotic group (n = 12). A concordant increase of glomerular alpha2(IV) collagen mRNA was found with 2.2- and 1.3-fold in moderate and mild sclerotic groups, respectively. The TGF-beta1/beta-actin mRNA ratios were highest in membranous nephropathy (466.4 +/- 133.4, n = 11), followed by lupus nephritis (394.9 +/- 94.8, n = 12) and diabetic nephropathy (333.2 +/- 97.6, n = 10). Patients with minimal change disease(233.1 +/- 54.1, n = 15)and IgA nephropathy(185.3 +/- 39.6, n = 9) had low levels. The degree of glomerulosclerosis in each group followed the TGF-beta1/beta-actin mRNA ratios indicating that the level is the major determinant ofglomerulosclerosis but not the disease entities. Glomerular TGF-beta1/beta-actin mRNA ratio did not correlate with clinical parameters such as the urinary protein excretion and creatinine clearance. These results suggest that glomerular TGF-beta1/beta-actin mRNA ratio may be used as a marker of glomerulosclerosis in renal biopsy to reflect the local sclerotic process.

Actins↗

PubMed1997

[Suppressive effects of a plant-origin polyol, dulcitol on collagen-induced arthritis in mice].

Dulcitol was isolated chemically from Celastrus obiculatus Thumb and determined by HPLC. Effects of dulcitol were examined on collagen-induced arthritis (CIA) in DBA/1J mice. From 6 weeks after the first immunization with bovine type II collagen, dulcitol (100 mg/kg body weight/day) was administered orally to immunized mice for 9 weeks. Clinical score of CIA was improved significantly by dulcitol intervention compared with the non-treated CIA mice. Radiographic score of phalangeal destruction was also improved by dulcitol treatment. These findings suggest that dulcitol may play a role in regulation of some inflammatory responses in the present arthritis model. Significant reduction of percentage of CD4+ and CD8+ T cell subsets in the spleen leucocytes of CIA mice was observed by flow cytometry. Almost normal level of CD4+ and CD8+ T cells was observed in dulcitol-treated groups, suggesting T cell-modifying effect of dulcitol in CIA. Weight of spleen was larger in CIA mice and it was not affected by dulcitol. Anti-collagen antibody titer was increased in CIA mice, and it was not affected by dulcitol, either. Improvement of the changes of CD4+ and CD8+ T cells in the spleen by dulcitol may suggest its modulatory effect on cellular immunity.

Animals↗

PubMed1997

False-positive whole-body iodine-131 scan due to intrahepatic duct dilatation.

Focal retention of radioactivity in the liver on whole-body 131I scan was interpreted as a metastatic lesion in a patient with well-differentiated thyroid cancer. Intrahepatic duct dilatation, usually resulting from biliary tract obstruction by bile stone, is a common disorder and may cause bile stasis. A patient with papillary thyroid cancer and a previous history of biliary tract stones had focal retention of radioactivity in the liver on whole-body 131I scan. Abdominal CT, endoscopic retrograde cholagiopancreatography, radionuclide cholangiography and sequential 131I scans demonstrated that this focal retention of radioactivity was caused by intrahepatic duct dilatation. Focal retention of radioactivity is visualized on delayed images but not on early images. The radioactivity initially increases and then decreases on following days.

Bile Ducts, Intrahepatic↗

PubMed1996

Autocorrelation of integrated power Doppler signals and its application.

The integrated power Doppler signal arising from blood flow is a random process. In this article, a general approach to model this random process is studied. Both the theoretical and experimental results show that the temporal autocorrelation function of the integrated power Doppler signals is directly related to properties of the insonified medium, such as the scattering strengths and velocities of all moving scatterers, and as well as the properties of the Doppler imaging system, such as the point spread function (psf) of the power Doppler images. Some initial experiments are performed to test the proposed model. Its potential application for flow measurement, such as perfusion evaluation, is also discussed.

Blood Flow Velocity↗

PubMed1996

[Clinical study on combined treatment of shuizhi tuyuan powder and nifedipine in treating hypertension patients complicated with left ventricular hypertrophy].

Patients with essential hypertension complicated with left ventricular hypertrophy (LVH) confirmed by ultrasonic cardiography were divided randomly into observation group and control group. Both groups were treated with nifedipine. Shuizhi Tuyuan Powder (SZTYP, consisted of Hirudo nipponia and Eupolyphaga sinensis) was given in addition to the observation group. The therapeutic course for the two groups were 6 months. Results showed that after one course of treatment, the myocardial weight index lowered from 136.8 +/- 7.5 g/m2 to 130.5 +/- 6.4 g/m2 in observation group, while in control group, it lowered from 136.7 +/- 7.4 g/m2 to 134.3 +/- 6.2 g/m2, the difference between the two groups was significant (P < 0.01). The symptoms were relieved in part of the patients with early stage of cerebrovascular disease treated with SZTYP. The results suggested that SZTYP combined with nifedipine has active curative effect on essential hypertension patients complicated by LVH and part patients in early stage of cerebrovascular disease.

Adult↗

PubMed1995

Fractional moving blood volume: estimation with power Doppler US.

PURPOSE: To estimate the fraction of moving blood in tissue with power Doppler ultrasound (US). MATERIALS AND METHODS: Power Doppler US measurements of moving scatterers in a flow tube were made as a function of successive dilutions of the perfusate. Measurements were normalized relative to the maximum Doppler power in the center of the flow tube at the highest concentration and were used to calculate the fractional dilution of the perfusate for each run with each dilution used to represent increasing amounts of non-moving soft tissue in the sample volume. The technique was also applied to two clinical examples. RESULTS: Successive dilutions of the perfusate in the flow experiment showed a monotonic, linear decrease in the Doppler power as a function of dilution. CONCLUSION: The power Doppler US technique has the potential to more accurately estimate alterations in blood flow and has the advantage of being a continuous parameter that can be depth normalized.

Blood Circulation↗

PubMed1994

Irreversible blockade of D2 dopamine receptors by fluphenazine-N-mustard increases D2 dopamine receptor mRNA and proenkephalin mRNA and decreases D1 dopamine receptor mRNA and mu and delta opioid receptors in rat striatum.

The consequences of irreversibly-inhibiting D2 dopaminergic receptors on the expression of D1 and D2 dopamine receptor mRNAs and proenkephalin mRNA and on the levels of mu- and delta-opioid receptors in rat striatum were studied following single or repeated administration of the irreversibly-acting D2 dopamine receptor antagonist, fluphenazine-N-mustard (FNM). The density of dopamine and opioid receptors was determined by receptor autoradiography and the levels of the mRNA for the D1 and D2 dopamine receptors and proenkephalin were measured by in situ hybridization histochemistry. Repeated treatment of rats with FNM for 6 days produced more than 80% inhibition of D2 dopamine receptors but less than 25% inhibition of D1 dopamine receptors. Repeated treatment with FNM also resulted in statistically significant increases in D2 dopamine receptor mRNA but decreases in D1 dopamine receptor mRNA. In contrast, acute treatment with FNM for 3 h had no significant effects on D1 or D2 dopamine receptor mRNAs in striatum. An examination of the effects of FNM on the opioid system showed that repeated treatment with FNM for 6 days produced more than a 2-fold increase in the expression of proenkephalin mRNA in striatum. This was accompanied by significant decreases in mu- and delta-opioid receptors in striatum, mainly by reducing the size of the patch compartment of striatum. Acute treatment with FNM for 3 h produced small increases in proenkephalin mRNA and mu-opioid receptors in striatum but had no significant effects on delta-opioid receptors. These results suggest that persistent inhibition of D2 dopamine receptors differentially regulates the expression of D1 and D2 dopamine receptor mRNA in striatum, and that the magnitude, duration and interval of inhibiting dopaminergic transmission may be important factors in regulating dopamine receptor mRNA expression. These results also suggest that D2 dopamine antagonists indirectly down-regulate opioid receptors by increasing the expression of proenkephalin mRNA, thereby increasing enkephalin which, in turn, decreases opioid receptors in striatum.

Animals↗

PubMed1994

Lesions of mouse striatum induced by 6-hydroxydopamine differentially alter the density, rate of synthesis, and level of gene expression of D1 and D2 dopamine receptors.

To study the effects of altering dopaminergic input on the levels and rate of synthesis of dopamine receptors, corpora striata of mice were lesioned unilaterally with 6-hydroxydopamine (6-OHDA), and the densities and levels of the mRNAs for D1 and D2 dopamine receptors were determined. The results showed that 6-OHDA caused significant reductions in D1 dopamine receptors and in D1 dopamine receptor mRNA in dorsolateral and dorsomedial regions of the lesioned striatum. By contrast, 6-OHDA lesions caused significant increases in D2 dopamine receptors and in D2 dopamine receptor mRNA in dorsolateral and ventrolateral regions of the lesioned striatum. To assess the effects of 6-OHDA lesions on the rate of synthesis of D1 and D2 dopamine receptors, the irreversibly acting dopamine receptor antagonist 2-ethoxy-1-ethoxycarbonyl-1,2- dihydroquinoline (EEDQ) was administered, and the rate of recovery of these receptors determined. The lesions decreased the rate of synthesis of D1 dopamine receptors in dorsolateral striatum but increased the rate of synthesis of D2 dopamine receptors in dorsolateral striatum. Correlation of these molecular events with dopaminergic behaviors showed that the rate of recovery from EEDQ-induced cataleptic activity and the recovery from inhibition of quinpirole-induced rotational behavior was more rapid than the recovery of either the D1 or D2 dopamine receptor. These results suggest that dopaminergic denervation differentially affects the rate of synthesis of D1 and D2 dopamine receptors in mouse striatum, and that these alterations in the rates of synthesis of the receptors may be explained by corresponding alterations in the levels of the respective transcripts for these receptors.

Animals↗

PubMed1994

A method for determination of frequency-dependent effective scatterer number density.

Previous researchers have shown that for low scatterer concentrations, the scatterer number density in an ultrasound pulse-echo experiment can be obtained from ratios of the fourth to the second moment of the backscattered signal. In this paper a new method is presented for determining an effective scatterer number density, which is the actual number density multiplied by a frequency-dependent factor that depends on the differential scattering cross sections of all scatterers. The method of data reduction goes beyond the work of previous authors in that, in addition to accounting for the possibility that different sets of scatterers may dominate the echo signal at different frequencies, it also explicitly retains both the temporal nature of the data acquisition and the properties of the ultrasound field in the data reduction. Tests of the method in phantoms yielded good agreement between measured values of the effective scatterer number density and number densities calculated using first principles.

Acoustics↗

PubMed1994

Statistical uncertainty in estimates of an effective scatterer number density for ultrasound.

In a previous paper [J. Acoust. Soc. Am. 95, 77-85 (1994)], a method for determining an effective scatterer number density in ultrasonography was presented. This is the actual number density multiplied by a frequency-dependent factor that depends on the differential scattering cross sections of all scatterers. This method involves evaluating the ratio of the fourth moment to the square of the second moment of echo signals scattered from the sample. The random processes involved in forming these echo signals give rise to an uncertainty in the estimated effective scatterer number density. This uncertainty is evaluated here using error propagation. The statistical uncertainty depends on the effective number of scatterers contributing to the segmented echo signal; it increases when the effective number of scatterers increases. Tests of the statistical uncertainty estimator were in good agreement with uncertainties computed from experimental data.

Models, Theoretical↗