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Biomedical subjects

C C Chen

Publications and source records attributed to C C Chen.

At least 523 records · Page 29Linked to original sources
PubMed1991

Percutaneous reposition of dislodged coils in the treatment of a vertebral arteriovenous fistula--with CT follow-up.

We report a case of vertebral arteriovenous fistula in which embolization was complicated by migration of two coils and a partially inflated balloon. In order to relieve compression to the spinal cord, the displaced balloon was punctured percutaneously. For both relieving compression to the spinal cord and obliterating the residual fistula, the dislodged coils in the partially thrombosed epidural venous sinus were removed percutaneously and placed in the fistula, and more coils were implanted in the fistula percutaneously through the needle. CT follow-up half a year later showed complete resolution of compression of the spinal cord and complete recovery from myelopathy was clinically apparent.

Adult↗
PubMed1991

Cardioprotective effects of nucleoside transport inhibition in rabbit hearts.

The cardioprotective effects of a nucleoside transport inhibitor, R75231, were investigated in the isolated rabbit heart. The hearts were subjected to 20 minutes of global normothermic ischemia followed by reperfusion. Before ischemia either solvent (group 1), 5 mumol/L of adenosine (group 2), or 0.64 mg/L R75231 (group 3) was added to the perfusate. Preischemic hemodynamics were not changed by treatment, except for an increase in coronary flow in the adenosine group (126% of control; p less than 0.05). Upon reperfusion, coronary flow was depressed in the controls (72% of the preischemic control values), increased in the adenosine group (113%) and unchanged in the R75231 group (89%). Functional recovery was significantly better in the adenosine group as well as in the R75231 group as compared with the controls (p less than 0.05). Cardiac output was 74% of the preischemic control value in the R75231 group, 67% in the adenosine group, and only 38% in the controls. Analysis of the coronary effluent after reperfusion showed a significant inhibition of rapid release of purines and a reverse of the adenosine/inosine ratio in the R75231 group as compared with the others. We conclude that R75231 has a cardioprotective effect that is probably related to accumulation of endogenous adenosine.

Adenosine↗
PubMed1991

Disruption of the Golgi apparatus by brefeldin A inhibits the cytotoxicity of ricin, modeccin, and Pseudomonas toxin.

We have studied the cytotoxicity of ricin in cells treated with brefeldin A (BFA), which dramatically disrupts the structure of the Golgi apparatus causing Golgi content and membrane to redistribute to the ER. BFA inhibits the cytotoxicity of ricin in Chinese hamster ovary, normal rat kidney, and Vero cells and abolishes the enhancement of ricin cytotoxicity by NH4Cl, nigericin, swainsonine, and tunicamycin or by a mutation in endosomal acidification. BFA protects cells from the cytotoxicities of modeccin and Pseudomonas toxin, but has no effect on the intoxication by diphtheria toxin. Pretreatment of BFA does not protect cells from ricin treatment in the absence of BFA. Our results suggest that ricin, modeccin, and Pseudomonas toxin share a common pathway of intracellular transport from endosomes to the Golgi region where they are released into the cytosol. In contrast, the lack of protection of Vero cells from diphtheria toxin by BFA indicates that diphtheria toxin is released from acidified endosomes without involving the Golgi region.

ADP Ribose Transferases↗
PubMed1991

Haemolymph monophenol oxidase activity in Armigeres subalbatus infected with Brugia pahangi.

The activity of monophenol oxidase can be elicited in the haemolymph of Armigeres subalbatus by both blood and filaria-infected blood feeding. Haemolymph collected from both blood-fed and filaria-infected mosquitoes was investigated using a quantitative radiometric assay that measured the amount of tritiated water formed during the hydroxylation of L-[3,5-3H]tyrosine to dopa. Enzyme activity in filaria-infected mosquitoes was found to be significantly lower than that found in the blood-fed mosquitoes within 3 days post-ingestion, but still remained measurable 72 h post-ingestion. The decreased enzyme activity coincided in time with the development of capsules around the microfilariae. The consumption of monophenol oxidase by the melanization of migrating microfilariae in the haemocoel of filaria-infected mosquitoes and the effects of excretory and secretory products of developing larvae on monophenol oxidase activity are suggested.

Animals↗
PubMed1991

Bioactive principles from the roots of Lindera megaphylla.

d-Dicentrine was isolated from the root of Lindera megaphylla. It inhibited the aggregation of washed rabbit platelets induced by ADP, collagen, arachidonic acid, and PAF. It also inhibited the high potassium- and norepinephrine-induced contraction of rat thoracic aorta. In rat ventricular cells treated with 3 microM d-dicentrine, the action potential duration (ADP50) was prolonged from 59.9 +/- 11.3 msec to 201 +/- 28.7 msec.

Animals↗
PubMed1991

Captopril renography in the diagnosis of renal artery stenosis and the prediction of improvement with revascularization. The Yale Vascular Center experience.

To enhance diagnosis and predict improvement in blood pressure control following surgery or renal angioplasty in patients with hypertension and renal artery stenosis (RAS), we employed captopril renography in 113 clinically selected patients, all of whom had renal angiography to verify the diagnosis. Criteria for normal captopril renograms were established from an initial cohort of 23 hypertensive patients with normal angiograms who had been judged to be at high risk for RAS using the same clinical criteria. Renal revascularization or nephrectomy was performed in 45 patients and the success of the procedure was determined in the 40 patients for whom 3-month follow-up was available. In these 113 patients, 58 (51%) had RAS. Captopril renography was 91% sensitive and 87% specific in identifying or excluding RAS. Diagnostic utility was preserved in those patients with renal insufficiency (serum creatinine equal to or greater than 1.5 mg/dL) (n = 46). Scintigraphic abnormalities induced by captopril were strongly associated with cure or improvement in blood pressure control following revascularization or nephrectomy (16 of 19), while the lack of captopril-induced change was associated with failure of such intervention (17 of 21) (P = .0001). We conclude that captopril renography is sensitive and specific for the diagnosis of RAS in a clinically selected high-risk group of hypertensives, and that the test accurately predicts the success or failure of therapeutic intervention.

Adolescent↗
PubMed1991

Dicentrine, a natural vascular alpha 1-adrenoceptor antagonist, isolated from Lindera megaphylla.

1. The pharmacological activity of dicentrine, isolated from Lindera megaphylla, was determined in rat isolated thoracic aorta, guinea-pig isolated trachea and human platelet-rich plasma. 2. Dicentrine was found to be a potent alpha 1-adrenoceptor blocking agent in rat thoracic aorta as revealed by its competitive antagonism of noradrenaline- (pA2 = 8.19 +/- 0.09) or phenylephrine (pA2 = 9.01 +/- 0.10)-induced vasoconstriction. These effects still persisted in denuded aorta. It was less potent than prazosin (pA2 = 10.60 +/- 0.10), but was more potent than phentolamine (pA2 = 7.53 +/- 0.10) or yohimbine (pA2 = 6.20 +/- 0.05). 3. Inositol monophosphate formation induced by noradrenaline (3 microM) in rat thoracic aorta was suppressed by dicentrine (3-10 microM) and prazosin (3 microM). 4. A high concentration of dicentrine (30 microM) did not affect the aortic contraction induced by the thromboxane receptor agonist U-46619 (1 microM), angiotensin II (1 microM), high potassium (60 mM) or carbachol (3 microM). 5. Contraction of guinea-pig trachea caused by histamine or carbachol was slightly inhibited by dicentrine (30 microM), while beta-adrenoceptor relaxation to isoprenaline in trachea was not affected. 6. Aggregation in human platelet-rich plasma induced by adrenaline (10 microM) was blocked by yohimbine (5 microM). A high concentration of dicentrine (greater than 30 microM) caused slight inhibition of aggregation, the release reaction and thromboxane formation. Complete blockade was obtained with 150 microM dicentrine. 7. It is concluded that dicentrine is a potent, selective alpha 1-adrenoceptor antagonist in vascular smooth muscle.

Adrenergic alpha-Antagonists↗
PubMed1991

Antihaemostatic and antithrombotic effect of some antiplatelet agents isolated from Chinese herbs.

Five antiplatelet agents have been isolated from Chinese herbs. Apigenin and magnolol are inhibitors of thromboxane synthesis, while osthole, protopine and norathyriol are inhibitiors of phosphoinositide breakdown. Thirty min after intraperitoneal (i.p.) administration of these drugs, tail bleeding time of mice was prolonged markedly in a dose-dependent manner by norathyriol, protopine, osthole and magnolol, but not by apigenin. However, the antiplatelet agents (up to 200 mg kg-1, i.p.) could not prevent acute thromboembolic death in mice. In endotoxin-induced experimental disseminated intravascular coagulation in rats, norathyriol (50-100 mg kg-1, i.p.) prevented the decrease in platelet counts and fibrinogen, and the prolongation of plasma prothrombin time. Norathyriol (100 mg kg-1, i.p.) also suppressed ex-vivo platelet aggregation induced by collagen and ADP in rat plasma.

Animals↗
PubMed1991

Simplified captopril renography in diagnosis and treatment of renal artery stenosis.

To improve the diagnosis and forecast the response to surgery or renal angioplasty in patients with hypertension and renal artery stenosis, we employed a simplified captopril renography protocol in conjunction with renal arteriography in 94 clinically selected patients. Fifty hypertensive patients (group 1) with a high clinical likelihood of renovascular hypertension were evaluated using a simplified captopril renography protocol and renal angiography on the arterial side. Criteria for normal captopril renal scintigrams were established based on this original cohort and validated in an additional 44 clinically comparable patients (group 2). Renal revascularization or nephrectomy was performed in 39 patients, and success of the procedure was determined in the 34 patients for whom 3-month follow-up was available. In the 94 patients, 44 (47%) had renal artery stenosis. Simplified captopril renography was 91% sensitive and 94% specific in identifying or excluding renal artery stenosis in the combined group, with no difference in the diagnostic utility between groups 1 and 2, or in those with renal insufficiency (n = 38) or those with bilateral disease (n = 17). Scintigraphic abnormalities induced by captopril were strongly associated with cure or improvement in blood pressure control following revascularization or nephrectomy (15 of 18), while the lack of captopril-induced changes was associated with failure of such intervention (13 of 16) (p = 0.0004). We conclude that simplified captopril renography is highly sensitive and specific in the diagnosis of renal artery stenosis in a clinically selected high-risk population and that the test accurately predicts the success or failure of therapeutic intervention.

Aged↗
PubMed1991

Aldehyde dehydrogenase deficiency, flush patterns and prevalence of alcoholism: an interethnic comparison.

A study was performed to verify that the prevalence of alcohol abuse and dependence in Formosan aborigines differs from that of Taiwanese (Chinese Han people), using analysis of aldehyde dehydrogenase (ALDH) isozymes and flush patterns on randomly sampled 70 Atayal, 66 Paiwan, 61 Yami and 94 Taiwanese subjects were studied. The activity of an isomer of ALDH having a low Km (ALDH-I) in hair roots was analysed by isoelectric focusing assay. The subjective experience of flushing response after alcohol ingestion was assessed. Results showed that the rate of ALDH-I deficiency in Taiwanese (51.1%) was significantly higher than in aborigines, i.e., 6.4%, 3.9%, and 0% in Atayal, Paiwan, and Yami subjects, respectively. The percentage occurrence of ALDH-I deficiency and prevalence of alcohol dependence in Taiwanese and aborigines were negatively correlated. The predominant pattern of self-reported flush response after alcohol use among aborigines was of slow onset. The flush response to alcohol ingestion was examined in relation to aldehyde metabolizing enzyme. Since alcohol sensitivity is an important factor in the development and maintenance of the alcohol ingestion habit in humans, our results support the hypothesis that there is a biological basis in the different rates of alcohol abuse and dependence among different ethnic groups.

Adult↗
PubMed1991

The value and role of computed tomography in blunt injury of the abdomen.

The use of computed tomography (CT) has had a tremendous impact on the evaluation and management of blunt abdominal trauma. The ability of CT to confirm the absence of intraperitoneal injury and/or significant hemoperitoneum, in correlation to the patient's physiological status, provides extremely valuable information so that unnecessary abdominal surgery is avoided. CT not only demonstrates the presence of injury and delineates it's extent, including the size of the hemoperitoneum, but may also provide information concerning the hemodynamic status of the patient. We reviewed the abdominal CT examination of 38 patients with blunt abdominal trauma at our institution from April 1989 to May 1990. There were no false negative cases and only one false positive case. Thus, we concluded that CT is not only a highly sensitive and accurate modality, but also an invaluable radiological diagnostic tool in the evaluation of blunt abdominal injury.

Abdominal Injuries↗
PubMed1991

Benign chest wall lipoblastoma: report of a case.

This report deals with a 22-month-old boy who had a benign lipoblastoma on the chest wall. The tumor was located intrathoracically and was well-encapsulated. It was yellowish in color with a shiny cut surface and consisted of multiple lobules. Histologically, peripheral immature lipoblasts with fat vacuoles of various size and central mature fat cells containing a single, large fat vacuole are characteristic of this tumor. No local recurrence has been found during the 17 months since total excision.

Adult↗
PubMed1991

Preliminary experience with growth factor and porcine graft-young collagenous wettable membrane in the treatment of chronic diabetic ulcer.

Chronic ulcers are well-known complication of diabetes mellitus, often compounded by infection. Healing of lesions is problematic in some cases using conventional treatment. We have treated a group of six hospitalized diabetic patients with chronic ulcer by a combined regimen consisting of metabolic control, parenteral antibiotics, growth factor and porcine graft-young collagenous wettable membrane (YCWM) treatment. Five of our uncontrolled group had their ulcers improved at 87 +/- 37.6 hospital days after 45.8 +/- 20.2 days of growth factor and YCWM treatment. In conclusion, growth factor and porcine graft-YCWM therapy may be promising as an alternative choice in treatment of chronic diabetic ulcer.

Aged↗
PubMed1990

Vasorelaxing effect in rat thoracic aorta caused by denudatin B, isolated from the Chinese herb, magnolia fargesii.

Denudatin B is an antiplatelet agent isolated from the flower buds of Magnolia fargesii. We studied the effects of denudatin B on the vasoconstriction of rat thoracic aorta induced by high potassium (K+) solution, norepinephrine (NE) and caffeine, and to elucidate its mode of action. The contraction of rat aorta caused by high K+ (60 mM) and cumulative concentrations of CaCl2 (0.03-3 mM) was inhibited concentration dependently by denudatin B with an IC50 of 21.2 micrograms/ml. NE (3 microM)-induced phasic and tonic contractions of rat aorta were inhibited by pretreatment with denudatin B (10-100 micrograms/ml). The relaxing action of denudatin B persisted in denuded aorta, in Ca2(+)-free and EGTA (2 mM)-containing medium. The vasorelaxing effects were not affected by indomethacin (20 microM), hemoglobin (10 microM) or methylene blue (50 microM) and were not accompanied by PGI2 formation. In quin-2/AM-loaded cultured rat vascular smooth muscle cells, denudatin B (100 micrograms/ml) inhibited the increase of intracellular calcium caused by NE (3 microM) in the presence or absence of extracellular calcium. Denudatin B did not affect the caffeine (10 mM)-induced contraction and the increase in intracellular calcium. Denudatin B (100 micrograms/ml) increased the cGMP, but not the cAMP level in intact and denuded aorta. The 45Ca2+ influx induced in rat aorta by high K+ (60 mM) or NE (3 microM) was markedly inhibited by denudatin B in a concentration-dependent manner. These results indicate that denudatin B relaxed vascular smooth muscle by inhibiting the Ca2+ influx through voltage-gated and receptor-operated Ca2+ channels; its effect to increase cGMP may enhance the vasorelaxation.

Animals↗
PubMed1990

Inhibition of thrombin- and collagen-induced phosphoinositides breakdown in rabbit platelets by a PAF antagonist--denudatin B, an isomer of kadsurenone.

Denudatin B, an isomer of kadsurenone, was isolated from Magnolia fargesii. It inhibited the aggregation and ATP release of washed rabbit platelets caused by platelet-activating factor (PAF) in a concentration-dependent manner. The IC50 on PAF (2 ng/ml)-induced aggregation was about 10 micrograms/ml. High concentration of denudatin B (greater than 50 micrograms/ml) also inhibited the aggregation and ATP release of platelets caused by ADP, collagen, arachidonic acid and thrombin. However, shape change of platelets still existed. Prolongation of the incubation time with platelets could not cause further inhibition, and the aggregability of platelets could be restored after denudatin B was washed out from platelets. Thrombin-induced thromboxane B2 formation was almost completely suppressed. In the absence of extracellular calcium (EGTA 1 mM), ATP release caused by thrombin was inhibited. Thrombin-induced rise of the intracellular calcium concentration was suppressed by denudatin B, but not by BN52021 or kadsurenone. The generation of inositol phosphate in washed platelets caused by collagen, PAF and thrombin was also suppressed. The data indicate that PAF antagonist denudatin B has nonspecific antiplatelet action at high concentration by inhibiting phosphoinositides breakdown induced by collagen and thrombin.

Animals↗
PubMed1990

Complete nucleotide sequence of the streptococcal C5a peptidase gene of Streptococcus pyogenes.

Streptococcal C5a peptidase (SCP), a recently discovered virulence factor of Streptococcus pyogenes, specifically cleaves the human serum chemotaxin C5a near its carboxyl terminus, destroying its ability to serve as a chemoattractant. We previously localized the SCP gene, scpA, to the 5.8-kb insert of the recombinant plasmid pTT1. Here we present the complete nucleotide sequence of scpA and its flanking regions. The gene initiates at a TTG codon and consists of 3501 base pairs, specifying a precursor protein of 128,252 daltons. Sequences resembling the promoter and ribosome-binding site of Gram-positive organisms are found upstream of scpA. The predicted amino acid sequence reveals the presence of a 31-residue signal peptide, putative cell wall spanning and membrane anchor domains. Regions of SCP show significant similarity to the sequences involved in the formation of the active site of the prokaryotic serine protease subtilisin. Results of Southern hybridization studies indicate that sequences highly similar to that of scpA are present in all serotypes of S. pyogenes tested.

Adhesins, Bacterial↗