Search PubMed⌕ Search

Biomedical subjects

C Chen

Publications and source records attributed to C Chen.

At least 739 records · Page 41Linked to original sources
PubMed1997

Endotracheal tube size selection guidelines for Chinese children: prospective study of 533 cases.

Appropriate selection of the size of an endotracheal tube (ETT) for use in children is important both in general anesthesia and critical care practice. Past published data on guidelines for selecting ETT size in children are based on Caucasian measurements. As body build is generally different in Chinese children compared with Caucasians of the same age group, guidelines for Chinese children are needed. The aim of this study was to determine guidelines for ETT size selection by recording and comparing age, body weight, length, head girth and circumference of the right fifth finger of the child. Correlations between internal diameter (ID) of the chosen ETT and the child's data were calculated and compared. In this study, 533 Chinese children. American Society of Anesthesiolgists class I or II, aged from 3 months to 6 years, undergoing oral intubation for general anesthesia for minor pediatric surgery were enrolled. Our results showed that body length (height) had the best correlation to the size of an uncuffed oral ETT. Through stepwise regression, a formula. ETT ID = 2 + (body length (cm)/30), was obtained.

Asian People↗
PubMed1997

D2-like dopamine receptor density in Tourette syndrome measured by PET.

UNLABELLED: Tourette syndrome (TS) is a chronic neurologic disorder characterized by the presence of involuntary motor and phonic tics. There is evidence that TS is associated with an abnormality of the dopaminergic system, involving postsynaptic D2 receptors. We tested the hypothesis that D2-like dopamine receptors are elevated in TS. METHODS: Twenty-nine adult patients with TS were studied by PET imaging with [11C]3-N-methylspiperone ([11C]NMSP). Two methods of data analysis were used. The first was a caudate-to-cerebellar ratio, measured at 45 min. The second method, applied in 20 subjects, was a two-PET scan procedure. Both used high specific activity [11C]NMSP, but the second scan was preceded by a dose of unlabeled haloperidol, which partially occupied the D2-like dopamine receptors. This was done to provide an absolute measure of receptor density (Bmax). All patients were compared to age- and sex-matched controls. RESULTS: Neither group showed significant differences from their control group in caudate-to-cerebellar ratio. However, the two-PET scan Bmax measurement demonstrated that 4 of the 20 patients had significantly elevated D2-like receptors. In this group of 20 patients, multiple linear regression analysis revealed a trend between the severity of vocal tics and Bmax values. This Bmax measure also revealed a significant (p < 0.05) association with performance on the Wisconsin Card Sorting Test. CONCLUSION: These findings suggest that not all patients with TS have an abnormality of D2-like receptors, but a subgroup of TS subjects has a significant D2-like dopamine receptor elevation. These findings also support the importance of applying a more quantitative method for Bmax determination to PET imaging analysis. The Bmax findings in the subgroup do not exclude an effect of intrasynaptic dopamine competition, but this effect may be less likely due to the high affinity of [11C]NMSP.

Adult↗
PubMed1997

Activation of the cloned human kappa opioid receptor by agonists enhances [35S]GTPgammaS binding to membranes: determination of potencies and efficacies of ligands.

Activation of kappa receptors inhibits adenylate cyclase, enhances K+ conductance and reduces Ca++ conductance via pertussis toxin-sensitive G proteins. We recently cloned a human kappa opioid receptor and stably expressed it in Chinese hamster ovary (CHO) cells. In this study, the effects of activation of the human kappa receptor by agonists on [35S]GTPgammaS binding to CHO cell membranes were examined. The presence of GDP and Mg++ was essential for the kappa agonist (-)-U50,488H-induced increase in [35S]GTPgammaS binding to be observed and the optimal concentration was 3 microM and 5 mM, respectively. The presence of 100 mM Na+ was necessary to produce the maximal signal-to-background ratio. (-)U50,488H-induced increase in [35S]GTPgammaS binding was time- and tissue concentration-dependent. (-)U50,488H increased [35S]GTPgammaS binding in a dose-dependent manner with an EC50 of 3.1 nM. (+)-U50,488H had no effect, which indicates that this effect is stereospecific. Naloxone (1 microM) or norbinaltorphimine (10 nM) shifted the dose-response curve of (-)-U50,488H to the right by 100-fold. These results indicate that enhancement of [35S]GTPgammaS binding by (-)-U50,488H is a kappa receptor-mediated event. Pretreatment of the cells with pertussis toxin, but not cholera toxin, abolished the (-)-U50,488H-induced increase in [35S]GTPgammaS binding, which indicates the involvement of Gi and/or Go proteins. [35S]GTPgammaS binding induced by (-)-U50,488H had a Kd value of 0.34 +/- 0.08 nM and a Bmax value of 431 +/- 29 fmol/mg protein. The rank order of potencies of opioid ligands tested in stimulating [35S]GTPgammaS binding was dynorphin A 1-17 > (+/-)-ethylketocyclazocine > beta-funaltrexamine, (-)-U50,488H, tifluadom > nalorphine > pentazocine, nalbuphine > buprenorphine. Dynorphin A 1-17, (+/-)-ethylketocyclazocine, (-)-U50,488H, tifluadom and beta-funaltrexamine were full agonists, but nalorphine and pentazocine were partial agonists producing maximal responses of 68% and 23% of those of full agonists, respectively. Nalbuphine and buprenorphine had low levels of agonist activities. Norbinaltorphimine and naloxone were antagonists devoid of activities. Enhancement of [35S]GTPgammaS binding by kappa agonists provides a simple functional measure for receptor activation and can be used for determination of potencies and efficacies of opioid ligands at the kappa receptor.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1997

Substance P release in the rat periaqueductal gray and preoptic anterior hypothalamus after noxious cold stimulation: effect of selective mu and kappa opioid agonists.

Intracerebral microdialysis was used to measure changes in the extracellular level of substance P (SP) released from the periaqueductal gray (PAG) and the preoptic anterior hypothalamus (POAH) of freely moving Sprague-Dawley rats after noxious cold stimulation. Artificial cerebrospinal fluid was perfused into the dialysis probe in the PAG or POAH and samples were collected every 30 min for 4 hr. SP-like immunoreactivity in the samples was measured by radioimmunoassay. In the PAG, SP base-line release was 0.43 +/- 0.08 fmol/fraction. SP release was increased to 1.3 +/- 0.4 fmol/fraction during the first collection period after noxious cold. Pretreatment with the selective mu opioid receptor agonist PL017 (0.8-3.4 nmol) or the kappa opioid receptor agonist dynorphin A1-17 (4.6-9.2 nmol), administered into the PAG by microinjection, produced dose-related inhibition of the cold-evoked SP release. Naloxone (10 mg/kg s.c.) administration 10 min before these opioid agonists reduced the inhibition of SP release. In the POAH, SP base-line release was 0.45 +/- 0.06 fmol/fraction and noxious cold did not cause any significant change in SP release. Microdialysis of SP (271 fmol-271 pmol/microl/min, for 30 min) into the PAG, but not the POAH, induced dose-related analgesia (35-68% MPA) in the cold-water tail-flick test. However, microdialysis of SP into the POAH or PAG failed to induce any significant change in body temperature. These data suggest that 1) SP released from the PAG acts as a neuromodulator to transmit nociceptive information; 2) opioid receptor agonists can suppress this information by inhibiting SP release; 3) SP evoked by noxious cold may have a role in triggering the antinociceptive function of the PAG; and 4) SP does not appear to act as a neuromodulator for thermoregulatory responses in the POAH.

Animals↗
PubMed1997

Transfusion requirements are correlated with the degree of proteolysis of von Willebrand factor during orthotopic liver transplantation.

During orthotopic liver transplantation (OLT) excessive bleeding is the main cause of death and graft failure. The acute bleeding tendency that accompanies OLT, particularly during the anhepatic period and after reperfusion of the graft, is due to the depletion or functional abnormalities of several hemostasis components caused by the enhanced activity of enzymes such as plasmin, trypsin and leukocyte proteases. We surmised that enhanced proteolysis might also cause abnormalities of von Willebrand factor (vWF), and that these abnormalities are implicated in the bleeding tendency that develops during OLT. Therefore, the pattern of vWF proteolysis was studied with 16 patients with chronic liver disease, in serial blood samples obtained before OLT, during the anhepatic stage, after graft reperfusion and at the end of the surgical procedure. vWF became markedly degraded during the anhepatic and reperfusion stages, as shown by the partial loss of high molecular weight multimers, the relative decrease of the intact 225 kD subunit and the increase of the native proteolytic fragments of 176 and 140 kD. Novel proteolytic fragments also became detectable. Using monoclonal antibody epitope mapping, it could be demonstrated that some of the proteolytic fragments corresponded in apparent molecular mass to those produced in vitro by incubating purified vWF with plasmin or elastase, but other fragments could not be attributed to these proteases. During the anhepatic and reperfusion stages there was a significant correlation between the degree of vWF degradation and the total amount of blood components transfused to replace blood losses. To evaluate whether or not vWF degradation could be controlled by the administration of a broad-spectrum protease inhibitor such as aprotinin, 5 patients were given a bolus dose of 500,000 U before surgery followed by 100,000 U/h during surgery, 5 were given a 2,000,000 U bolus followed by 500,000 U/h, and no aprotinin was given to the remaining 6 patients. There were no differences in the patterns or degrees of vWF degradation between patients treated with aprotinin or not. In conclusion, there is a marked degradation of a key hemostasis protein during OLT. These alterations may be of clinical significance, because they are correlated with the transfusion requirements.

Adult↗
PubMed1997

Disease expression in X-linked retinitis pigmentosa caused by a putative null mutation in the RPGR gene.

PURPOSE: To determine the disease expression in X-linked retinitis pigmentosa (XLRP) caused by a putative null mutation in the RPGR (retinitis pigmentosa GTPase regulator) gene. METHODS: In a family with XLRP, haplotype analysis was performed with polymorphic microsatellite markers from the Xp chromosomal region, and genomic polymerase chain reaction sequencing was used to identify sequence variations in the RPGR gene. Hemizygotes and heterozygotes were evaluated clinically and with visual function tests. Optical coherence tomography (OCT) was performed on heterozygotes. Postmortem donor retinas from a heterozygote were examined by microscopy and immunocytochemistry. RESULTS: X-linked inheritance was confirmed by haplotype analysis using Xp markers. Sequence analysis of the RPGR gene identified a single base pair change, a G-->T transversion, that converts codon 52 GGA (Gly) to TGA (stop codon); the mutation segregates with the disease. A hemizygote in the third decade of life had barely measurable rod function and severely impaired cone function that diminished further over a 7-year interval. Heterozygotes varied in degree of disease expression from mild to severe. Perimetry showed loci with normal rod and cone sensitivity interspersed with loci having either equal rod and cone dysfunction or rod > cone dysfunction. Electroretinographic photoreceptor responses had equal reductions in rod and cone maximal amplitude. OCT cross sectional reflectance images of retinal regions with severe dysfunction showed reduced thickness of the retina and retinal pigment epithelium-choriocapillaris (RPE-CC) complex and increased reflections posteriorly. Regions with mild dysfunction showed similar OCT findings but with preserved retinal thickness. Retinal histopathology in a heterozygote revealed loss of photoreceptors throughout, with retention of only a few islands of cones with tiny or absent outer segments and rods lacking outer segments. CONCLUSIONS: This RPGR gene mutation, in its mildest expression in heterozygotes, causes a relatively equal disturbance of rod and cone photoreceptor function. Detectable structural change by OCT at the level of the RPE-CC can be present in patches of retina with minimal functional disturbance. More advanced disease stages in heterozygotes show greater rod than cone dysfunction, and the end stage in hemizygotes and heterozygotes is that of typical RP, with only barely detectable cone function from residual cones in a thinned retina with abnormal RPE and choriocapillaris.

Adult↗
PubMed1997

Cloning and sequence analysis of the 5'-flanking region of goat beta-lactoglobulin gene.

We were the first to report 5'-flanking sequences of goat beta-lactoglobulin (beta LG) gene (867 bp) including a promoter (770 bp) and part of the first exon (97 bp). The fragment was isolated from Chinese goat tissue with PCR, and then cloned and sequenced. Sequence comparison showed 94.6% homology with sheep and 88% homology with cattle, respectively. There are highly conserved transcription factor binding sites as well. It suggested that the proximal 406 bp of 5'-flanking sequences of sheep beta LG possess strong tissue-specific DNAaseI-hypersensitive sites. Sheep beta LG transgenes containing only the 406-bp 5'-flanking sequences were efficiently expressed in the mouse mammary gland at a high level. These goat beta LG 5'-flanking sequences could possibly direct heterologous protein expression in the milk of transgenic animals.

Animals↗
PubMed1997

Creating an environment for linking knowledge-based systems to a clinical database: a suite of tools.

A difficulty in using knowledge-based systems has been linking them to clinical databases. The challenge is in making a correct mapping from the data in the knowledge base to the data in the database. At Columbia-Presbyterian Medical Center, we have built a suite of tools developed to create queries that address this challenge. The tools were designed to allow users to easily retrieve data from the database without requiring the users have extensive database and vocabulary knowledge. The tools help users write correct queries (Query Builder), find correct terms in the clinical database (MED Browser), aggregate the resulting data into a useful form (Clinical Database Browser), and allow the user to test the query within the environment of the knowledge-based system (Event Playback). The tools have been in use for one year.

Artificial Intelligence↗
PubMed1997

Clinical and microbiological features of liver abscess after transarterial embolization for hepatocellular carcinoma.

OBJECTIVES: To present the clinical and microbiological features of liver abscess after transarterial embolization (TAE) for hepatocellular carcinoma (HCC). METHODS: We retrospectively reviewed records of 452 TAE procedures in 289 patients with HCC over a 2-yr period. RESULTS: Four men and one woman with a mean age of 68.4 yr were diagnosed with liver abscess 1-8 wk (mean 4.6 wk) after the embolization. The incidence was 1.1% (5/452). Common symptoms included fever, chills, and right upper quadrant pain. Serum aminotransferase, alkaline phosphatase, and gamma-glutamyltransferase levels and leukocyte count were frequently elevated. All the abscesses appeared as areas of hypodensity on CT scan and hypoechogenicity on ultrasonogram. The areas contained gas in the embolized tumor, which led to the suspicion and finally the diagnosis of abscess. In contrast to predominance of gram-negative aerobes in sporadic pyogenic liver abscesses, the causative microorganism was predominantly gram positive (60%). All patients were treated with parenteral antibiotics plus percutaneous aspiration, drainage, or operation, but one patient died from the abscess. CONCLUSIONS: For patients receiving TAE for HCC, few specific clinical or radiological features could readily differentiate patients complicated with liver abscess from those without. This may delay a timely diagnosis and lead to significant morbidity. Hence, in patients with risk factors, including old age, previous biliary tract disease, large tumor size (>5 cm), and gas forming in the embolized tumor, aspiration of the suspected focal hepatic lesion should be performed as soon as possible.

Abdominal Pain↗
PubMed1997

Blood-brain disposition and antinociceptive effects of -D-penicillamine2,5-enkephalin in the mouse.

Although intravenous administration of [D-penicillamine2, 5]-enkephalin (DPDPE) produces significant antinociception in rodents, the duration of antinociception is short ( approximately 15 min). The present study was conducted to test the hypothesis that duration of antinociception for DPDPE is determined by both systemic and regional disposition (i.e., blood-brain translocation), and that the magnitude of antinociception is related more closely to concentrations in brain tissue than in blood. Systemic disposition was examined after i.v. administration of DPDPE (10-100 mg/kg) to male CD-1 mice. The relationship between antinociception and concentration in blood and brain tissue was assessed by determining antinociception 10 min after administration of DPDPE (10-100 mg/kg); effect versus brain tissue concentration data were fit with pharmacodynamic models to recover EC50 estimates. In addition, the time course of antinociception, as well as blood and brain tissue concentrations, were examined after an i.v. bolus dose (40 mg/kg) of DPDPE. The systemic disposition of DPDPE was nonlinear; both clearance and volume of distribution were dose-dependent. Antinociception increased proportionately with increasing concentrations of DPDPE in blood or brain tissue, with an EC50 of 1.42 +/- 0.06 microg/g expressed as brain tissue concentration. However, the brain-to-blood concentration ratio also increased with increasing dose, suggestive of saturable translocation of DPDPE across the blood-brain barrier. Antinociception appeared rapidly (within 5 min) and dissipated within approximately 15 min after a 40 mg/kg i.v. dose. These results suggest that rapid elimination from blood and active efflux from brain limit the duration of action of DPDPE.

Analgesics, Opioid↗
PubMed1997

[Bacterial vaginosis in pregnant women].

OBJECTIVES: To determine the prevalence of bacterial vaginosis (BV) in pregnant women and to assess the association between BV and adverse pregnancy outcome. METHODS: Bacterial vaginosis was screened in 380 healthy pregnant women during different gestational weeks by clinical features and Grams stained vaginal smears. The pregnancy outcome of these gravidae was followed up. RESULTS: The prevalence of BV in pregnant women was 6.8% (26/380). The incidence of puerperal infection, neonatal infection, and jaundice of newborn were higher in women with BV than those without BV (14.3%, 9.5%, and 23.8% v.s. 2.2%, 1.3%, and 5.4%, respectively P < 0.05, P < 0.05, P < 0.005). CONCLUSION: Pregnant women with BV are associated with maternal infection, neonatal infection, and jaundice of newborn. It is necessary to treat BV during pregnancy.

Adult↗
PubMed1997

[The mechanisms of progesterone treatment on endometrial carcinoma].

OBJECTIVE: To study the mechanisms of the exogenic progestrerone treatment on endometrial carcinoma. METHODS: We observed the morphologic changes of the endometrial cancer cells treated by exogenic progesterone with light and electronic microscopy. RESULTS: The main changes of the tumor cell treated were well differentiation, increase in secretory activity and apoptosis of tumor cells. CONCLUSIONS: Progesterone may directly affect tumor cells, inhibit the growth of tumor cells and lead to well differentiation. Clinically with preoperative and postoperative progesterone therapy, it can decrease the peritoneum implantation and metastasis, and also decrease the recurrence after operation.

Adenocarcinoma↗
PubMed1997

[Expression of glutathione S-transferase-pi in operative specimens as marker of chemoresistance in patients with ovarian cancer].

OBJECTIVE: To study the relationship between the expression of glutathione S-transferase-pi (GST-pi) in operative specimens and chemoresistance in patients with ovarian cancer. METHODS: The expression of GST-pi in 87 epithelial ovarian cancer tissues and 30 normal ovarian epithelial tissues was determined with labelled streptavidin biotin method (LSAB). All the patients had not received chemotherapy before operation. We used Chi-Square and Cox-Mantel test to analyze the relativity between the expression of GST-pi and clinical pathological data, chemotherapeutic response, prognosis in patients with ovarian cancer. RESULTS: (1) 59 (67.8%) of 87 ovarian cancer tissue were demonstrated to be positive expression with GST-pi, but all 30 normal ovarian epithelial tissue were negative. (2) There was no direct correlation between the expression of GST-pi and clinical pathological data. (3) 43 (43/59) of GST-pi positive cases were chemoresistant, while only 3 (3/28) of GST-pi negative ones were chemoresistant. (4) The difference in the chemotherapeutic response between the two groups was obviously significant (P < 0.005). The survival period of the patients with GST-pi positive expression was also obviously shorter than that of those with GST-pi negative expression (P = 0.004). CONCLUSION: These results strongly suggest that GST-pi expression in epithelial ovarian cancer tissues is closely related to chemoresistance clinically and it may be served as a useful marker to predict the prognosis of patients.

Antineoplastic Agents↗
PubMed1997

[Image analysis of tumor cells from common intracranial neoplasms on frozen and paraffined slices].

Image analysis technique was used to measure four parameters [the form factor (FF), area, perimeter and diameter] of nuclei in 76 cases of common intracranial tumors on forzen and paraffined slices. The results showed that the area, perimeter, diameter of nuclei on frozen slices were much larger than those on paraffined slices while the FF showed no significant difference between two kinds of slices (P > 0.05). The parameters of the area, perimeter, and diameter of nuclei on two kinds of slices became larger and the parameters of FF became smaller as the grade of astrocytoma ascended. It is considered that the results of present study will be helpful to the diagnosis of common intracranial tumors on frozen slices.

Astrocytoma↗