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C C Chen

Publications and source records attributed to C C Chen.

At least 127 records · Page 7Linked to original sources
PubMed2000

A new member of the acid-sensing ion channel family.

Acid-sensing ion channels (ASICs) are members of the epithelial sodium channel (ENaC)-degenerin family of two-pass transmembrane segment protein subunits which form multimeric cation channels. Members of the ENaC-degenerin family are gated by stimuli as diverse as protons, peptides and mechanical distension. Here we describe a new member of the family, SPASIC or ASIC 4 (spinal cord ASIC) which is expressed throughout the central nervous system in an overlapping population of neurons that also express the ASIC subunit MDEG2. ASIC-4 which shows 44% identify with ASIC is developmentally regulated and expressed in a subset of sensory neurons as well as in the CNS. However, despite the strong homology with ASIC, the ASIC-4 transcript does not encode a proton gated cation channel.

Acid Sensing Ion Channels↗
PubMed2000

Tumor promotion of N-nitroso-N-(3-keto-1, 2-butanediol)-3'-nitrotyramine derived from nitrosation of Maillard reaction product in CD-1 mice.

N-Nitroso-N-(3-keto-1,2-butanediol)-3'-nitrotyramine (NO-NTA) is a product of a model browning system generated in the presence of sodium nitrite. Our previous study showed that NO-NTA had genotoxicity and proved to be an initiator and promoter on mouse C3H10T1/2 cells. In this study, a two-stage skin carcinogenesis protocol was used to promote CD-1 mouse skin carcinogenesis using NO-NTA. Twice weekly, for 38 weeks, topical application of NO-NTA at the concentration of 250 nmol to mice previously initiated with benzo(a)pyrene (BaP) caused 90% tumor incidence. However, no tumors were observed in mice treated with BaP or treated with NO-NTA alone. The NO-NTA-promoted tumors that were observed histologically in mice showed well-differentiated squamous cell carcinoma with invasion into the subcutaneous region. Application of the same amount of NO-NTA not only caused significant induction of hyperplasia but also epidermal ornithine decarboxylase (ODC) activity. Treatment of mouse skin (1 cm(2)) with various amounts of NO-NTA (10, 50, or 250 nmol) caused production of hydrogen peroxide by 1.63-, 1.91-, and 2. 38-fold, respectively, and marked induction of myeloperoxidase (MPO) by 21-, 39-, and 61-fold. These results indicate that NO-NTA is a new tumor promoter and may induce tumor promotion by oxidant stress in CD-1 mouse skin.

Animals↗
PubMed2000

Histological and immunoglobulin VH gene analysis of interfollicular small lymphocytic lymphoma provides evidence for two types.

Interfollicular small lymphocytic lymphoma (I-SLL) has not been well characterized and its relationship to small lymphocytic lymphoma (SLL) or chronic lymphocytic leukemia (CLL) is uncertain. Moreover, two different proliferation center growth patterns have been described with respect to reactive germinal centers. In this study, we evaluate the histological and immunophenotypic features of 13 cases of I-SLL and immunoglobulin heavy chain variable (VH) gene sequences from 10 cases. Immunophenotypic analyses indicate that cases showing either growth pattern have the same CD5-positive B cell phenotype typical of SLL or CLL. Sequence analysis revealed the use of VH, D, and J gene segments often found in CLL, although there may be more frequent use of J6. Similar to recent studies of CLL, there were approximately equal numbers of cases with either mutated or unmutated VH genes without evidence of ongoing mutation, consistent with I-SLL having either a naïve or memory B cell origin. Interestingly, the mutational status of the I-SLL VH genes seemed to correlate with the two different histological growth patterns. These studies support the proposal that I-SLL represents SLL/CLL and suggest the recently proposed two types of CLL originating from either memory or naïve B cells may have different histological patterns of growth in lymph nodes that show architectural preservation.

Adult↗
PubMed2000

Signal detection theory in the 2AFC paradigm: attention, channel uncertainty and probability summation.

Neural implementation of classical High-Threshold Theory reveals fundamental flaws in its applicability to realistic neural systems and to the two-alternative forced-choice (2AFC) paradigm. For 2AFC, Signal Detection Theory provides a basis for accurate analysis of the observer's attentional strategy and effective degree of probability summation over attended neural channels. The resulting theory provides substantially different predictions from those of previous approximation analyses. In additive noise, attentional probability summation depends on the attentional model assumed. (1) For an ideal attentional strategy in additive noise, summation proceeds at a diminishing rate from an initial level of fourth-root summation for the first few channels. The maximum improvement asymptotes to about a factor of 4 by a million channels. (2) For a fixed attention field in additive noise, detection is highly inefficient at first and approximates fourth-root summation through the summation range. (3) In physiologically plausible root-multiplicative noise, on the other hand, attentional probability summation mimics a linear improvement in sensitivity up to about ten channels, approaching a factor of 1000 by a million channels. (4) Some noise sources, such as noise from eye movements, are fully multiplicative and would prevent threshold determination within their range of effectiveness. Such results may require reappraisal of previous interpretations of detection behavior in the 2AFC paradigm.

Attention↗
PubMed2000

Effect of phenylephrine on focal atrial fibrillation originating in the pulmonary veins and superior vena cava.

OBJECTIVES: This study was aimed at evaluating the effects of phenylephrine infusion on the occurrence of focal atrial fibrillation (AF). BACKGROUND: Paroxysmal AF can be initiated by ectopic atrial beats originating in the pulmonary vein (PV) or superior vena cava (SVC). The effect of change in autonomic tone on this focal AF is unknown. METHODS: This study included 12 patients with frequent bursts of AF documented by 24-h Holter monitoring. The number and coupling interval of spontaneous ectopic activity and bursts of AF were evaluated for 1 min before and after phenylephrine (2 to 3 microg/kg) injection. RESULTS: After detailed mapping, four patients had a focus located in the left superior PV, six in the right superior PV and two in the SVC. In 10 patients with AF foci originating in the PVs, the frequency of ectopic activity (19.5 +/- 27.4 vs. 11.4 +/- 22.9 beats/min, p = 0.059) was reduced as well as AF bursts (14 +/- 3 vs. 1.8 +/- 2.7 bursts/min, p = 0.005) before versus after phenylephrine injection; the minimal coupling interval of ectopic activity and AF bursts became longer compared with baseline. The maximal percent increase in sinus cycle length after phenylephrine injection was significantly greater in patients with complete suppression of AF compared with those with partial suppression (43 +/- 19 vs. 14 +/- 5%, p = 0.01). However, no significant effect of phenylephrine on AF originating in the SVC was found. CONCLUSIONS: Change in autonomic tone induced by phenylephrine injection was effective in suppressing focal AF originating in the PVs but not in the SVC.

Aged↗
PubMed2000

Repeated hypotensive episodes due to hepatic outflow obstruction during liver transplantation in adult patients.

We report two cases of unusual repeated hypotension, decreased cardiac output, decreased mixed venous oxygen saturation, decreased central venous pressure, pulmonary artery pressure, and pulmonary wedge pressure after the completion of all vascular anastamoses of liver transplantation. These unstable hemodynamics appear to reflect a clinically relevant picture of hypovolemia. However, the real cause was partial hepatic outflow obstruction. The obstruction was suspected because hypotension was alleviated by elevating the full-sized liver graft ventrally and to the left. Doppler ultrasound examination confirmed that the flow velocity of the hepatic vein outflow was insufficient when the liver fell to its resting position in the right hepatic fossa. An additional side-to-side cavo-caval anastomosis resolved the problem in one patient, whereas the other required not only the additional anastomosis, but also application of a tissue expander filled with 770 mL normal saline beneath the liver to eliminate the obstruction. We emphasize that obstruction of the hepatic outflow causes only temporal hypovolemia because of a decrease of venous return and that treatment of this complication should be surgical intervention to relieve the obstruction. Blind resuscitation with fluids will not solve the problem and, in fact, may result in fluid overload with subsequent complications.

Adult↗
PubMed2000

Isolation of immunoglobulin from egg yolk by anionic polysaccharides.

Isolation conditions of immunoglobulin in egg yolk (IgY) were optimized by the addition of various levels of Na-alginate (Alg), lambda-carrageenan (lambda-Cg), Na-carboxymethyl cellulose (CMC), and pectin (PC) to 6-fold diluted yolk. The mixtures were then reacted at pH 4.0-6.0 for 30 min. The optimal isolation conditions of IgY for Alg, lambda-Cg, and CMC were at the 0.1% level and at pH 5.0, while those for PC were at the 0.15% level and at the same pH. The remaining lipid and remaining protein in the supernatants thus obtained was 0.5-3.8% and 10-17%, respectively, and more than 90% of lipoproteins were precipitated. The IgY recovery was determined to be 33-74% by means of single radial immunodiffusion method when IgY was isolated under the optimal conditions. PC showed the best recovery of IgY, while lambda-Cg provided the least. The interactions between polysaccharides and lipoproteins were mainly ionic bonds, hydrophobic interactions, and hydrogen bonds as determined by the addition (0-2.0 M) of NaSCN or urea to the polysaccharide-lipoprotein precipitates.

Alginates↗
PubMed2000

Antiplatelet aggregation principles from Ephemerantha lonchophylla.

Bioactivity-directed separation led to the identification of four compounds, viz. denbinobin (1), 3,7-dihydroxy-2,4-dimethoxyphenanthrene (2), 3-methylgigantol (3), and erianthridin (4) from the ethanolic extract of Ephemerantha lonchophylla. Antiplatelet tests were carried out using 4 different aggregation inducers, viz. arachidonic acid (AA), thrombin, collagen and platelet activating factor (PAF). The results indicated that only compounds 2, 3, and 4 exhibited generally significant anti-aggregation activities with that against AA-induced aggregation being most effective. Estimated IC50, values in this regard for 2, 3, and 4 were 24 microM, 30 microM and 9 microM, respectively.

Medicine, Chinese Traditional↗
PubMed2000

Effect of honey on naringin absorption from a decoction of the pericarps of Citrus grandis.

To measure naringin/naringenin absorption of a decoction prepared from the pericarps of Citrus grandis and to investigate the effect of honey on naringin/naringenin absorption, six healthy males received 200 mL decoctions of untreated and honey-treated Pericarpium Citri Grandis in a randomized crossover design. The absorption was measured by renal recovery of naringenin glucuronides/sulfates over 48 hours. The contents of naringin/naringenin in 200 mL decoctions of untreated and honey-treated Pericarpium Citri Grandis were determined to be 261.5/23.8 mumol and 303.3/11.6 mumol, respectively. The mean cumulated renal excretion of naringenin glucuronides/sulfates after intake of these two decoctions were 74.8 mumol (26.2% of dose) and 49.8 mumol (15.8% of dose), respectively. Paired Student's t-test showed that the difference of the total renal recovery of naringin/naringenin between the two decoctions was significant. The results indicated that honey significantly reduced naringin/naringenin absorption by 33.4% in humans and suggested that honey treatment might alter the efficacy of Pericarpium Citri Grandis.

Absorption↗
PubMed2000

Inducible nitric oxide synthase inhibitors from Saposhnikovia divaricata and Panax quinquefolium.

A series of polyacetylenes, falcarinone, panaxynol, falcarindiol, panaxydol, and panaxytriol, were isolated from Saposhnikovia divaricata (Turcz.) Schischk and Panax quinquefolium L. These polyacetylenes were identified as active principles on the inhibition of nitrite production by inducible nitric oxide synthase (iNOS). Treatment with 10 microM of panaxynol, falcarindiol, panaxydol and panaxytriol decreased the LPS/IFN-gamma-stimulated accumulation of nitrite by 71.92 +/- 3.07, 69.95 +/- 3.68, 45.48 +/- 6.11 and 36.85 +/- 8.80%, respectively. The IC50 value of falcarinone, panaxynol, falcarindiol, panaxydol and panaxytriol was > 20, 2.23, 1.98, 6.58 and 9.85 microM, respectively.

Apiaceae↗
PubMed2000

Anti-hepatitis B virus effects of wogonin isolated from Scutellaria baicalensis.

By using an HBV-producing cell line (MS-G2) in vitro culture system, we found that wogonin isolated from Scutellaria baicalensis can suppress HBV surface antigen production (P < 0.001) without evidence of cytotoxicity. By assaying the endogenous HBV DNA polymerase activity, we found that both the relaxed circular and the linear forms of HBV DNA are significantly reduced in the wogonin-treated group. Wogonin deserves to be further evaluated for the treatment of human HBV infection.

Flavanones↗
PubMed2000

The use of SPECT bone scans to evaluate patients with idiopathic jaw pain.

OBJECTIVE: The purpose of this study was to investigate the potential usefulness of single photon emission computed tomography (SPECT) bone scanning with technetium-99m methylene diphosphonate (Tc-99m MDP) in the diagnosis of idiopathic jaw pain. Unlike planar bone scanning, SPECT uses tomographic technology to provide 3-dimensional images, which are more useful in localizing small lesions. STUDY DESIGN: Twenty patients, each with a diagnosis of chronic idiopathic jaw pain, were compared after SPECT bone scanning with 20 age-matched and gender-matched normal controls. Uptake was identified and compared in sites with previously detected jaw pathoses and jaw pain. RESULTS: Nineteen of 20 patients with jaw pain evaluated with SPECT had positive scans, in contrast with 12 of 20 control subjects (P <.04). Positive scans were correlated with painful sites in 15 of 20 patients, with the remaining 5 patients demonstrating no uptake in painful locations. Patients with jaw pain demonstrated 37 of 80 mouth quadrants with positive scans, in contrast with 21 of 80 mouth quadrants in the controls (P <.01). Nineteen of 24 painful mouth quadrants had uptake in the pain group. Of the 21 quadrants positive in the controls, 17 were correlated with previously detected jaw pathoses. The sensitivity and specificity for detecting painful sites were 0.79 and 0.68, respectively. The sensitivity and specificity for detecting previously identified pathoses in the jaws of normal controls were 0. 80 and 0.93, respectively. CONCLUSION: Patients with idiopathic jaw pain had a significantly greater frequency of positive SPECT bone scans when compared with normal controls. However, the sensitivity and specificity of SPECT bone scans in detecting painful sites were low. These findings suggest that SPECT bone scanning with Tc-99m MDP is not indicated as a routine imaging procedure for the detection of jaw pathoses, but may be considered as a potential research tool in the future study of chronic idiopathic jaw pain.

Adult↗
PubMed2000

Ultrasound and sestamibi scan as the only preoperative imaging tests in reoperation for parathyroid adenomas.

BACKGROUND: In an effort to determine an efficient algorithm for the evaluation of patients with parathyroid adenomas in the reoperative setting, we explored the combination of using ultrasound scans (US) and sestamibi scintigraphy as the only preoperative imaging tests. METHODS: We analyzed the outcomes of 62 consecutive patients who were treated between January 1995 and May 1999 and who were referred for persistent primary hyperparathyroidism after initial surgical exploration, at which time no abnormal parathyroid glands had been found. Although all patients underwent US, computed tomography scan, magnetic resonance imaging, and sestamibi scan, we analyzed the success of localization and reoperation using only the results of US and sestamibi scan. RESULTS: Sixty-one patients (98%) underwent curative reoperations. The sensitivity, positive predictive value, and accuracy for US were 90%, 86%, and 84%, respectively; the corresponding values for sestamibi imaging were 78%, 94%, and 74%, respectively. In 58 of 62 cases (94%) preoperative US and/or sestamibi scan accurately identified the adenoma. In 3 patients for whom combined US and sestamibi scan were inaccurate, 1 adenoma was found by intraoperative US in the strap muscle; 1 adenoma was found by blind cervical thymectomy, and 1 adenoma was found by planned sternotomy that was based on computed tomography findings. CONCLUSIONS: This study supports an algorithm of obtaining US and sestamibi scan as the initial and perhaps only preoperative localization tests for patients with primary hyperparathyroidism after failed operation, at which time no abnormal glands had been found.

Adenoma↗
PubMed2000

Performance characteristics of PM10 samplers under calm air conditions.

The size range of airborne particles that is closely related to specific deposition regions in the human respiratory tract and excess lung burden of these deposited particles is associated with disease. Size-selective sampling, therefore, needs to be performed to assess the related health risks. Performance criteria applied to these samplers must be well characterized in order to provide accurate and reliable results. The PM10 samplers that have been used in place of the total suspended particulate samplers for the collection of ambient air particles are more relevant to potential inhalation hazards. In order to be certified, a PM10 sampler must meet reliable performance specifications, primarily the aerosol penetration test with liquid and solid particles in a wind tunnel (wind speeds of 2, 8, and 24 km/hr). This testing is intended to assure reasonable accuracy in aerosol measurements. However, the sampler performance under calm air conditions has not been well studied. In the present study, the sampling heads of three devices--the Harvard impactor, the Personal Environmental Monitor (PEM), and the Sierra Andersen model 241 dichotomous sampler PM10 inlet head--were tested for aerosol separation efficiency. With the consideration of bias and imprecision of the measurements, five specimens of each type of sampler were chosen for performance testing, repeating the tests 5 times for each specimen. An ultrasonic atomizing nozzle was used to nebulize potassium sodium tartrate tetrahydrate and dioctyl phthalate particles as the solid and liquid challenge aerosols, respectively. The aerosol number concentrations and size distributions upstream and downstream of the samplers were measured by using an aerosizer calibrated against a settling velocity chamber. The results showed that among the samplers tested, the dichotomous sampler PM10 inlet head had the best fit to the PM10 convention, while the other two samplers not only appeared to have a steeper separation-curve slope but also had significant particle bounce when challenged with solid particles. Analysis of variance also confirmed the superiority of the dichotomous samplers. Surface-coating with oil or grease greatly reduced the problem of particle bounce.

Aerosols↗
PubMed2000

Shortening of cardiac action potentials in endotoxic shock in guinea pigs is caused by an increase in nitric oxide activity and activation of the adenosine triphosphate-sensitive potassium channel.

OBJECTIVE: To investigate the roles of nitric oxide and adenosine triphosphate (ATP)-sensitive potassium channels (KATP) in the shortening of cardiac action potential in endotoxic shock. DESIGN: Prospective animal study with concurrent controls. SETTING: University animal research laboratory. SUBJECTS: Adult Hartley guinea pigs, weighing 300-400 g. INTERVENTIONS: Guinea pigs were anesthetized and mechanically ventilated for 6 hrs. Lipopolysaccharide (LPS) or saline (sham group) were given intravenously. Drug effects were examined at the end of 6 hrs. MEASUREMENTS AND MAIN RESULTS: Plasma nitrate concentration was measured hourly, while guanosine 3',5'-cyclic monophosphate (cGMP) content and action potential duration at 90% of repolarization (APD90) of papillary muscle were examined every 2 hrs in the 6-hr endotoxemia in both the sham and the LPS-treated groups. The basal levels of these three variables showed no difference in the two groups. In the sham group, these variables did not change significantly (n = 14 for plasma nitrate determination; n = 5 for cGMP content measurement; n = 5-14 for APD90 measurement; all p > .05). But in the LPS-treated group, both plasma nitrate concentration and cGMP content of papillary muscle showed time-dependent increases and they were significantly higher than those in the sham group (at the 6th hr, plasma nitrate: 42.6 +/- 7.7 vs. 21.8 +/- 3.1 micromol/L, both n = 14, p < .01; cGMP: 1.52 +/- 0.15 vs. 0.73 +/- 0.08 pmol/mg protein, both n = 5, p < .01). In contrast, APD90 revealed a time-dependent decrease compared with that in the sham group (at the 6th hr, 137.1 +/- 52 vs. 188.2 +/- 4.8 msecs, both n = 14, p < .001). In the following 60-min in vitro recording of action potentials after the end of 6-hr endotoxemia, the shortened APD90 in the LPS-treated group did not recover and remained shorter compared with that in the sham group, in which the APD90 showed no significant changes (at the 60th min, 165.1 +/- 5.7 vs. 200.2 +/- 3.8 msecs, each n = 14, p < .01). However, in the presence of glibenclamide, a specific KATP blocker (100 micromol/L; n = 10), the APD90 could be reversed almost completely to the same value as that in the sham group (n = 14) (196.6 +/- 3.5 vs. 200.2 +/- 3.8 msecs; p > .05), despite glibenclamide having no effect on the APD90 in the sham group. In the LPS-treated group, NG-nitro-L-arginine methyl ester (1 mmol/L; n = 4), methylene blue (10 micromol/L; n = 5), and aminoguanidine (100 micromol/L; n = 4) significantly prolonged the shortened APD90 (192.5 +/- 3.1, 195.0 +/- 3.3, and 176.5 +/- 3.3 msecs, respectively; p < .01, p < .01, and p < .05, respectively, compared with that without these agents, 165.1 +/- 5.7 msecs, n = 14). These agents had negligible effects on the APD90 in the sham group (all p > .05). Furthermore, 8-bromoguanosine-3',5'-cyclic monophosphate (500 micromol/L; n = 5) decreased APD in intact papillary muscle (mean reduction of APD90, 13.5 +/- 3.5%, n = 5; p < .05), an effect abolished by pretreatment with glibenclamide (100 micromol/L; n = 5) that did not have an effect by itself. CONCLUSIONS: In this experimental model, we provide reasonably convincing evidence to suggest that in endotoxic shock, an increase in nitric oxide activity may activate KATP, which plays a major role in the shortening of APD, presumably through a cGMP-dependent pathway.

Action Potentials↗
PubMed2000

Spontaneous bowel perforation in infants and young children: a clinicopathologic analysis of pathogenesis.

BACKGROUND: In children beyond the neonatal stage, spontaneous bowel perforation with no specific cause is rare. It has attracted little notice and does not fit into any established clinical category. This often results in treatment delays. To determine the underlying pathogenesis, a clinicopathologic analysis of this group of patients was performed. METHODS: From 1984 through 1997, 15 previously healthy children (10 boys and 5 girls) with bowel perforations were enrolled in this study. Children in whom the specific cause was established were excluded. The ages of the patients ranged from 3 months to 5 years, 5 months (average age: 2 years, 4 months). Data on clinical course, surgical and pathologic findings, and outcomes were analyzed. RESULTS: All the patients had high fever and acute, watery diarrhea with clinical dehydration. Abdominal distension developed and bowel perforation ensued 5 to 30 days after the onset of diarrhea. In all cases, the perforation consisted of either an isolated patch of bowel (n = 8) or patchy lesions in a segment (n = 7), which was confined to one of the following three anatomic watershed areas: the splenic flexure (n = 7); the lower sigmoid (n = 3); and the ileocecal region (n = 5). One patient died, and three had major sequelae including intra-abdominal abscess, adhesion ileus, and peristomal fistula. Specimens from 13 patients were submitted for histopathologic evaluation. All specimens had acute suppurative inflammation diffusely around the perforation site. Seven had areas of coagulation necrosis of the muscularis propria, especially in the inner circular muscle layer. CONCLUSION: In acute diarrheal diseases, dehydration may cause bowel ischemia and lead to perforation. Physicians should be alert to the possibility of this abdominal catastrophe when progressive abdominal distension followed by acute diarrheal episodes occurs in children.

Acute Disease↗