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Biomedical subjects

C Fan

Publications and source records attributed to C Fan.

At least 109 records · Page 6Linked to original sources
PubMed1994

Clinical assessment of biplanar transesophageal echocardiography--a report of 125 cases.

One hundred and twenty-five patients with cardiovascular disease were examined by biplanar transesophageal echocardiography (BTEE), including 67 with rheumatic heart disease (7 monitored during operation), 22 with aortic diseases, 20 with congenital heart diseases, and 16 with other kinds of heart disease. The results showed that BTEE was not influenced by corpulent and pulmonary emphysema and was better than transthoracic echocardiography at imaging the interatrial septum, left atrium and left atrial appendage, thoracic aorta, and mitral artificial valve and at intraoperative monitoring. BTEE was also better than single-plane transesophageal echocardiography, because BTEE could be used to observe the heart and thoracic aorta in transverse and longitudinal planes, thus enlarging the transmission "window" as well as allowing the entire lesion to be imaged. This study suggests that BTEE will have good prospects in clinical application.

Adolescent↗
PubMed1994

[Taxonomy of 1043 strain producing actinospectacin].

Streptomyces strain 1043 was isolated from a soil sample collected in Hangzhou. The strain may produce two antibiotics--Actinospectacin and Streptovaricin. Its aerial mycelia are apricot orange to carnelian red on most media. An outstanding characteristic of 1043 strain is the development of pigment granules in both vegetative and aerial mycelia. Its culture and physiological characteristicus were found to resemble those of Streptomyces spectabilis. Streptomyces strain 1043 was named Streptomyces spectabilis 1043.

China↗
PubMed1993

The pharmacokinetic and pharmacodynamic interaction between propafenone and lidocaine.

Although propafenone is a known substrate and inhibitor of the cytochrome P450 4-hydroxylation pathway of debrisoquin (CYP2D6 isozyme), its effects on other hepatic mixed- function oxidative isozymes have not been extensively evaluated. We studied the influence of propafenone on the disposition of continuously infused lidocaine in 12 healthy male volunteers. Placebo or propafenone (225 mg every 8 hours) was orally administered for 4 days before and during lidocaine administration (2 mg/kg/hr for 22 hours). In the 11 (92%) subjects phenotyped as extensive metabolizers, propafenone significantly increased the lidocaine area under the plasma concentration time curve (81.7 +/- 16.2 versus 76.3 +/- 15.6 micrograms.hr/ml; p < or = 0.05) and reduced systemic lidocaine clearance (9.53 +/- 1.77 versus 10.27 +/- 2.24 ml/min/kg; p < or = 0.05), but did not significantly affect volume of distribution at steady state (2.48 +/- 0.33 versus 2.64 +/- 0.45 L/kg; p = 0.10) or mean residence time (4.37 +/- 0.92 versus 4.47 +/- 0.87 hours; difference not significant) compared with placebo, respectively. Adverse central nervous system effects were significantly worse in severity and duration during the propafenone phase (p < or = 0.05). Propafenone minimally inhibits the metabolism of lidocaine. This suggests that the ability of propafenone to inhibit metabolic pathways exclusive of the CYP2D6 isozyme may be limited. In addition, potentiation of disturbing central nervous system adverse effects may occur during combination therapy of propafenone and lidocaine.

Adult↗
PubMed1993

Antifibrillatory and electrophysiologic actions of moricizine alone and in combination with lidocaine: a prospective, randomized trial.

OBJECTIVE: The Cardiac Arrhythmia Suppression Trial II showed that moricizine acutely increases the occurrence of sudden cardiac death. Thus the objective of this investigation was to evaluate the antifibrillatory properties of moricizine (a new antiarrhythmic agent) alone and in combination with lidocaine (an established antifibrillatory agent). DESIGN: Prospective, double-blind, randomized, placebo-controlled trial. SETTING: Laboratory at a large, university-affiliated medical center. SUBJECTS: Eighteen domestic farm swine with a mean weight of 39 +/- 5 kg. INTERVENTIONS: After pentobarbital anesthesia, the animals were instrumented. A bipolar pacing catheter was placed in the right ventricular apex and a pig-tail catheter was placed in the aortic arch for induction of ventricular fibrillation and aortic blood pressure monitoring. Subsequently, the pigs were randomized to moricizine or control (0.9% saline) groups. Each group underwent three treatment phases: baseline, drug (moricizine 2 mg/kg loading dose, 1.5 mg/kg/hr infusion, or saline bolus and infusion), and drug combined with lidocaine (5 mg/kg loading dose, 4 mg/kg/hr infusion). Ventricular fibrillation threshold was determined every 5 to 10 mins over a 1-hr period during each treatment phase. RESULTS: Ventricular fibrillation threshold values in the animals randomized to control were 16.8 +/- 7.6, 18.1 +/- 8.9, and 23.9 +/- 10.4 mA at baseline during saline infusion, and when saline was combined with lidocaine, respectively. The values during the saline-lidocaine combination treatment phase were significantly greater than the values at baseline and during saline treatment alone (p < .001). Ventricular fibrillation threshold values in the animals randomized to receive moricizine were 15.5 +/- 4.4, 18.1 +/- 5.1, and 21.1 +/- 8.4 mA at baseline, during moricizine infusion, and when moricizine was combined with lidocaine. The values during the lidocaine-moricizine combination treatment phase were significantly greater than values at baseline (p = .005), but not during moricizine treatment alone (p = .16). The increase in ventricular fibrillation threshold from baseline to moricizine (17%) was similar to the increase from baseline to saline (7%), p = .37. The increase in ventricular fibrillation threshold when lidocaine was added to moricizine (13%) was less than the increase with lidocaine alone (32%), p = .05. CONCLUSION: In this experimental model, moricizine, at the dose studied, lacked antifibrillatory properties. Moreover, moricizine did not contribute to the antifibrillatory effects of lidocaine.

Animals↗
PubMed1993

Stability of famotidine in an extemporaneously prepared oral liquid.

The stability of famotidine in an extemporaneously prepared oral liquid stored at 4 and 24 degrees C for 30 days was studied. Famotidine liquid was prepared by pulverizing and suspending 12 40-mg tablets in distilled water. This mixture was diluted with cherry syrup to a total volume of 60 mL, resulting in a famotidine concentration of 8 mg/mL. The liquid was divided into two 30-mL amber glass bottles and stored at 4 degrees C and at room temperature (24 degrees C). Samples from each of the two bottles were assayed for famotidine content by high-performance liquid chromatography. Each sample was assayed in duplicate at time 0 and on days 2, 5, 10, 15, 20, 25 and 30. The concentration of famotidine remained above 90% of original concentration for 20 days at 4 degrees C and for 15 days at room temperature. After 30 days, famotidine concentration was reduced by 15% and 24% at 4 degrees C and room temperature respectively. Famotidine liquid 8 mg/mL compounded extemporaneously from tablets was stable for 20 days at 4 degrees C and for 15 days at 24 degrees C.

Chromatography, High Pressure Liquid↗
PubMed1992

Fatty acid biosynthesis redirected to medium chains in transgenic oilseed plants.

Medium-chain fatty acids (FAs), found in storage lipids of certain plants, are an important renewable resource. Seeds of undomesticated California bay accumulate laurate (12:0), and a 12:0-acyl-carrier protein thioesterase (BTE) has been purified from this tissue. Sequencing of BTE enabled the cloning of a complementary DNA coding for a plastid-targeted preprotein. Expression of the complementary DNA in the seeds of Arabidopsis thaliana resulted in BTE activity, and medium chains accumulated at the expense of long-chain (greater than or equal to 16) FAs. Laurate became the most abundant FA species and was deposited in the storage triacylglycerols. These results demonstrate a mechanism for medium-chain FA synthesis in plants.

Acetyltransferases↗
PubMed1992

Reaction of cyanide with cytochrome ba3 from Thermus thermophilus: spectroscopic characterization of the Fe(II)a3-CN.Cu(II)B-CN complex suggests four 14N atoms are coordinated to CuB.

Cytochrome ba3 from Thermus thermophilus reacts slowly with excess HCN at pH 7.4 to create a form of the enzyme in which CuA, cytochrome b, and CuB remain oxidized, while cytochrome a3 is reduced by one electron, presumably with the formation of cyanogen. We have examined this form of the enzyme by UV-visible, resonance Raman, EPR, and electron nuclear double resonance spectroscopies in conjunction with permutations of 13C- and 15N-labeled cyanide. The results support a model in which one CN- binds through the carbon atom to ferrous a3, supporting a low-spin (S = 0) configuration on the Fe; bridging by this cyanide to the CuB is weak or absent. Four 14N atoms, presumably donated by histidine residues of the protein, provide a strong equatorial ligand field about CuB; a second CN- is coordinated through the carbon atom to CuB in an axial position.

Binding Sites↗
PubMed1992

14,15N, 13C, 57Fe, and 1,2H Q-band ENDOR study of Fe-S proteins with clusters that have endogenous sulfur ligands.

The benefits of performing ENDOR experiments at higher microwave frequency are demonstrated in a Q-band (35 GHz) ENDOR investigation of a number of proteins with [nFe-mS] clusters, n = 2, 3, 4. Each protein displays several resonances in the frequency range of 0-20 MHz. In all instances, features are seen near v approximately 13 and 8 MHz that can be assigned, respectively, to "distant ENDOR" from 13C in natural-abundance (1.1%) and from 14N (the delta m1 = +/- 2 transitions); the nuclei involved in this phenomenon are remote from and have negligible hyperfine couplings to the cluster. In addition, a number of proteins show local 13C ENDOR signals with resolved hyperfine interactions; these are assigned to the beta carbons of cysteines bound to the cluster [A(13C) approximately 1.0 MHz]. Five proteins show resolved, local delta m1 = +/- 2 ENDOR signals from 14N with an isotropic hyperfine coupling, 0.4 less than or equal to A(14N) less than or equal to 1.0, similar to those seen in ESEEM studies; these most likely are associated with N-H...S hydrogen bonds to the cluster. Anabaena ferredoxin further shows a signal corresponding to A(14N) approximately 4 MHz. Quadrupole coupling constants are derived for both local and distant 14N signals. The interpretation of the data is supported by studies on 15N- and 13C-enriched ferredoxin (Fd) from Anabaena 7120, where the 15N signals can be clearly correlated with the corresponding 14N signals and where the 13C signals are strongly enhanced. Thus, the observation of 14N delta m1 = +/- 2 signals at Q-band provides a new technique for examining weak interactions with a cluster.(ABSTRACT TRUNCATED AT 250 WORDS)

Aconitate Hydratase↗
PubMed1992

Defibrillation energy requirements during moricizine and moricizine-lidocaine therapy.

Defibrillation energy requirements may be altered by antiarrhythmic agents. We investigated the effects of moricizine on the defibrillation threshold (DFT) in 18 pentobarbital-anesthetized pigs. The animals were randomized, in a blinded fashion, to moricizine or control (0.9% saline) treatment groups. Each group underwent three treatment phases: baseline, drug infusion (moricizine or saline), and drug infusion combined with lidocaine. Moricizine (2 mg/kg loading dose, 1.5 mg/kg/h infusion) and lidocaine (5 mg/kg loading dose, 4 mg/kg/h infusion) were dosed to achieve therapeutic concentrations. After 5 s of induced ventricular fibrillation, defibrillation was performed using a cardiac defibrillator interfaced with two epicardial electrode patches. DFTs were determined at baseline, during the drug phase, and during the combination of lidocaine with moricizine or saline. DFT values in the animals randomized to the control group were 15.2 +/- 4.2, 14.0 +/- 3.3, and 17.8 +/- 8.7 J at baseline, saline infusion, and saline combined with lidocaine, respectively. No significant differences were observed among the treatment phases. DFT values in the animals randomized to moricizine group were 12.1 +/- 2.8, 13.8 +/- 5.2, and 22.9 +/- 7.1 J at baseline, moricizine infusion, and moricizine combined with lidocaine, respectively. The DFT values during the lidocaine-moricizine combination treatment phase were significantly greater than baseline and moricizine alone (p < 0.002). The mean change in the DFT from baseline to moricizine (14% increase) was significantly different than the mean change in the DFT from baseline to saline (8% decrease) (p = 0.03). Lidocaine added to moricizine increased the DFT by 84%, which was significantly different from the 27% increase in the DFT when lidocaine was added to saline (p = 0.02). We conclude that moricizine minimally increases the DFT, but the combination of moricizine with lidocaine results in a synergistic rise in the DFT that may have detrimental clinical implications.

Animals↗
PubMed1992

[Compatibility of Chinese drugs radix Aconiti carmichaeli with rhizoma Pinelliae].

To find out whether the Chinese drug Radix Aconiti Carmichaeli is compatible with another Chinese drug Rhizoma Pinelliae in preparation, the two medicinal herbs were made into different forms of decoctions. Experiments with these decoctions were carried out to observe the action on isolated hearts of toads and the ECG and acute toxicity on mice. The results showed that in terms of toxicity there was no marked increase in the mixed decoction as compared with the other two decoctions prepared from Radix Aconiti Carmichaeli and Rhizoma Pinelliae separately.

Animals↗
PubMed1991

A specific acyl-ACP thioesterase implicated in medium-chain fatty acid production in immature cotyledons of Umbellularia californica.

Umbellularia californica (California Bay) seeds accumulate 10:0 and 12:0 as principal reserve fatty acyl groups. An in vitro fatty acid synthesis system from the developing cotyledons produces chiefly 10:0 and 12:0, in approximately the same proportions as the intact tissue. The kinetics of acyl thioester and free fatty acid formation in this system suggest that a medium-chain specific acyl-acyl-carrier protein (ACP) hydrolysis mechanism is responsible for the preponderance of medium-chain products. A crude extract of the developing cotyledons exhibits hydrolytic activity toward acyl-ACPs, with marked preference for 12:0-ACP and 18:1-ACP in the test series 6:0, 8:0, 10:0, 11:0, 12:0, 14:0, 16:0, and 18:1-ACPs. Partial purification of the 12:0-ACP hydrolytic activity has resulted in its separation from the 18:1-ACP hydrolase(s) and the 12:0-coenzyme A hydrolase(s) that are also present, thereby demonstrating its specificity for the 12-carbon acyl chain length and the ACP derivative. During cotyledon development, as the proportion of medium-chain to other fatty acyl groups increases, the extractable yield of this activity also increases substantially. Collectively these results suggest a role for this 12-ACP thioesterase in medium-chain production in vivo.

Coenzymes↗
PubMed1991

Developmental induction, purification, and further characterization of 12:0-ACP thioesterase from immature cotyledons of Umbellularia californica.

The fatty acyl content of developing cotyledons of Umbellularia californica (California Bay) changes from a long-chain composition to a predominance of 10:0 and 12:0 in just 4-5 days at the beginning of an approximately 100-day period of medium-chain deposition. This striking change occurs at the earliest appearance of 12:0-acyl-carrier protein (ACP) thioesterase activity. The coincidence of these rapid events is consistent with the hypothesis that the enzyme plays a major role in medium-chain biosynthesis. The 12:0-ACP thioesterase has been substantially purified; enzyme activity consistently comigrates in chromatographic and electrophoretic systems with a protein or pair of proteins having an apparent molecular weight of approximately 34 kDa. A native molecular weight of approximately 42 kDa has been estimated by gel filtration chromatography, suggesting that the enzyme is a monomer. Affinity chromatography on immobilized ACP is a critical step in the purification procedure, and resolves the 12:0-ACP and 18:1-ACP thioesterases sufficiently to confirm that the medium-chain enzyme has negligible action on 18:1-ACP.

Acyl Carrier Protein↗
PubMed1988

Methotrexate-induced resistance to dactinomycin in choriocarcinoma.

NaUCC-2, a choriocarcinoma cell line, was derived from a patient who had a very poor clinical response to combination chemotherapy. Methotrexate (MTX) might have inhibited the antitumor effect of dactinomycin. To investigate this point, in vitro studies were performed to determine the sensitivity and uptake of MTX and dactinomycin (administered individually and in combination) to NaUCC-2 and three other choriocarcinoma cell lines. Dihydrofolate reductase (DHFR) concentrations were studied as well. Although NaUCC-2 showed sensitivity to MTX and dactinomycin, which were comparable to the other cell lines when they were given separately, NaUCC-2 was unique in that the combination of MTX and dactinomycin was less lethal than dactinomycin given by itself. The uptake of MTX in NaUCC-2 was significantly higher than that in the other cell lines, and MTX also induced an increase in dactinomycin uptake in NaUCC-2. There was no significant difference in DHFR activity. Although additional studies are necessary to determine the mechanism responsible for this effect, these findings suggest that a mechanism other than drug uptake or DHFR activity must play a role in the drug resistance for choriocarcinoma. These findings also suggest that the most commonly used combination chemotherapy for choriocarcinoma, dactinomycin and MTX, may not always be the best method.

Adult↗