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Biomedical subjects

D Hu

Publications and source records attributed to D Hu.

At least 163 records · Page 9Linked to original sources
PubMed1994

Retrograde conduction properties after catheter radiofrequency ablation of atrioventricular accessory pathways.

UNLABELLED: A total of 208 atrioventricular (AV) accessory pathways in 200 patients were abolished by catheter radiofrequency current ablation. The antegrade AV conduction was normal after the ablation. Approximately 66% of the patients experienced retrograde AV conduction dissociation, which is independent of the age, gender and antegrade conduction properties of accessory pathways (manifest or concealed). Retrograde conduction dissociation is more prevalent than decremental conduction in patients with left free (80% vs. 17%, P < 0.001) or right free (78.6% vs. 21.4%, P < 0.01) wall pathways. Eleven patients (5.5%) showed recurrence after an average of 213 days follow-up. The recurrence of right free wall pathways (21.4%) is much more common than that of left free wall (2.5%) and posteroseptal (4.8%) pathways. The recurrence in those with decremental conduction after the initial successful ablation is higher than that of patients with retrograde AV dissociation (8.8% vs. 3.8%, P < 0.01), and most of them required a second ablation session. CONCLUSION: most of the patients, especially those with free wall accessory pathways, will have retrograde conduction dissociation after the successful radiofrequency catheter ablation. Electrophysiological studies should be carefully performed on patients with decremental retrograde conduction after the ablation.

Adolescent↗
PubMed1994

Predictors of early and late recurrence of atrioventricular accessory pathway conduction after apparently successful radiofrequency catheter ablation.

The correlation between electrophysiologic parameters and recurrence in 239 patients who underwent successful catheter ablation for an accessory pathway mediated tachycardia was analysed. Pathway conduction recurred in 15 patients (6.3%) after a mean follow-up of 7.3 months. Recurrence was most common in patients with right free wall pathways (17.1%). Accessory pathway conduction resumed in 18.9% of patients with decremental ventriculo-atrial (VA) conduction post-ablation compared with those patients without VA conduction (3.4%) (P < 0.001). Recurrence was common also in patients with repeated return of accessory pathway conduction during the ablation procedure (40% vs. 1.3%, P < 0.01). The patients in whom these observations are made should be monitored closely for recurrence of accessory pathway conduction post-ablation.

Adult↗
PubMed1994

Postlicensure effectiveness of the Haemophilus influenzae type b polysaccharide-Neisseria meningitidis outer-membrane protein complex conjugate vaccine among Navajo children.

The incidence of invasive Haemophilus influenzae type b (Hib) infection was decreased significantly among Navajo children since the licensure of Hib conjugate vaccines, even though two lots of Hib (polyribosylribitol phosphate)-meningococcal B outer-membrane protein conjugate vaccine (PRP-OMP) widely used among the Navajo were later found to be of low immunogenicity. We measured the effectiveness of all Hib conjugate vaccines combined, PRP-OMP alone, and the PRP-OMP lots with lower-than-expected immunogenicity among Navajo infants and children. This was a matched case-control study using active, laboratory-based surveillance for the ascertainment of Navajo children 2 1/2 to 59 months of age with invasive Hib infection; 45 patients with infection and 180 control subjects were enrolled. The effectiveness of one, two, and three doses, respectively, of all Hib conjugate vaccines combined was 96% (95% confidence interval (CI) 65%, 99%), 99% (95% CI, 69%, 100%), and 99% (95% CI - 57%, 100%). The effectiveness of one or more doses of PRP-OMP was 95% (95% CI, 66%, 99%). The effectiveness of a single dose of the lots of lower-than-expected immunogenicity was 89% (95% CI, -8%, 99%). The Hib conjugate vaccine coverage increased from 49% during 1991 to 94% during 1992; no control subjects younger than 18 months of age were enrolled during 1993. The occurrence of invasive Hib infections in this population after licensure of Hib conjugate vaccines was the result of gradual vaccine uptake, not poor vaccine effectiveness. The use of PRP-OMP has been highly effective despite concerns about the immunogenicity of several lots.

Bacterial Outer Membrane Proteins↗
PubMed1994

Epidural analgesia in labor and cesarean delivery for dystocia.

Published studies assessing the effect of epidural analgesia in nulliparous labor on the frequency of cesarean delivery for dystocia are reviewed. There are at least four retrospective studies and two prospective studies that suggest that epidural analgesia may increase the risk of cesarean delivery for dystocia in first labors. The potential for epidural to increase the frequency of cesarean delivery for dystocia is likely influenced by multiple variables including parity, cervical dilatation at epidural placement, technique of epidural placement, management of epidural during labor, and the obstetrical management of labor after placement of epidural analgesia. Two studies suggest that delaying placement of the epidural until 5 cm of cervical dilatation or greater may reduce the risk of cesarean birth. Epidural is safe and may be a superior labor analgesic when compared with narcotics. However, patients should be informed that epidural analgesia may increase the risk of cesarean birth in first labors.

Analgesia, Epidural↗
PubMed1994

[A community cohort study on risk factors of strokes in Shanghai: a Cox regression analysis on 15,885 subjects].

Baseline investigation on 15,885 subjects who were over thirty-five years old had been launched since July 1987. All of them were selected from eighteen neighbourhoods of three districts in Shanghai by using multiple stage cluster sampling procedure. All of them were followed up till the end of 1989. Each new case of stroke was randomly matched with about twenty controls by age and sex. The total 2,682 controls together with 127 new cases of strokes were analyzed by using Cox regression model for risk factors. The population attributable risk proportion (PARP) of factors was also estimated.

Acute Disease↗
PubMed1993

Catheter ablation of atrioventricular accessory pathways by radiofrequency current.

Tachycardias mediated by atrioventricular accessory pathways, which are refractory to antiarrhythmic drug therapy have been treated both by surgery and by catheter ablation with high energy direct current shock. These procedures have variable success rates and substantial associated morbidity and mortality. Radiofrequency ablation, a newer, low-energy technique is potentially safer and more effective. Of 110 patients with 117 accessory pathways, 101 were located on the left side and 16 on the right. Accessory pathway conduction was abolished permanently in 101 (91.8%) patients. VA conduction dissociation and VA decremental conduction were found in 88 and 13 successful patients, respectively. Four (3.9%) patients with decremental VA conduction suffered arrhythmia recurrence after a mean of 8 months follow-up. Complications developed in two patients including right femoral vein thrombosis and left ventricular insufficiency. There were no deaths from the procedure. We conclude that radiofrequency current ablation is a safe and effective interventional modality for patients with symptomatic tachycardias mediated by atrioventricular accessory pathways.

Adolescent↗
PubMed1993

Interaction of indoleacrylic acid with Trp aporepressor from Escherichia coli.

Trans-beta-Indoleacrylic acid (IAA) binds with moderately high affinity to the dimeric protein, trp aporepressor from Escherichia coli. IAA is itself nonfluorescent, and, upon binding, IAA quenches approximately 95% of the intrinsic tryptophan fluorescence of the protein. Since there is an overlap between the absorbance of IAA and the emission of tryptophan, this quenching appears to be due to resonance energy transfer. To adequately fit binding isotherms, it was necessary to use a model in which the binding of IAA to one subunit is able to quench fluorescence from both subunits of the protein. This model also assumes that binding to the two subunits occurs independently. Binding data were obtained as a function of the concentration of trp aporepressor, over the range of 1 x 10(-8) to 5 x 10(-5) M, in order to test the possibility that protein subunit association or dissociation occurs. When analyzed in terms of the above model, no significant protein concentration dependence is seen for the IAA association constant, indicating that either (i) the protein does not undergo changes in oligomerization over this concentration range or that (ii) different states of aggregation bind IAA with similar affinity. The affinity of IAA was found to increase at higher ionic strength and at lower pH. Also, evidence is presented for a photoinduced change in the configuration of IAA.

Bacterial Proteins↗
PubMed1993

Prolonged regional nerve blockade by controlled release of local anesthetic from a biodegradable polymer matrix.

BACKGROUND: Prolonged nerve blockade is potentially useful in the management of many acute and chronic pain problems. Aside from infusions via an indwelling catheter, most currently available nondestructive techniques for prolonging local anesthetic action cannot provide more than 1-2 days of blockade. Bioerodible polymer matrixes have been used to deliver a variety of drugs in patients and animals for periods lasting weeks to years. Previously, dibucaine and bupivacaine were incorporated into copolymers of 1,3 bis(p-carboxyphenoxy) propane-sebacic acid anhydride (1:4), and demonstrated sustained release in vitro following incubation of the drug-polymer matrixes in phosphate-buffered solution (pH 7.4, 37 degrees C). METHODS: In the present study, cylindrical pellets made from polymer matrixes incorporated with bupivacaine-HCl were implanted surgically along the sciatic nerves of rats. Neural block was assessed by direct observation of motor skills and by leg-withdrawal latency to a hot surface. Biochemical and histologic examinations were performed 2 weeks after implantation. RESULTS: Sensory and motor blockade was produced for periods ranging from 2 to 6 days. Contralateral control legs receiving polymer implants without drug showed no block. Blockade was reversible, and animals appeared to recover sensory and motor function normally. Biochemical indexes of nerve and muscle function were indistinguishable from contralateral controls. CONCLUSIONS: This biodegradable polymer system provides a promising new alternative for the delivery of local anesthetics to peripheral nerves to produce prolonged blockade for the management of acute and chronic pain.

Anesthetics, Local↗
PubMed1993

Studies on antibiotic 230 as a molluscicide.

In the course of studying molluscicidal effects of microorganisms, a microorganism belonging to Streptomycetaceae, Streptomyces griseolus (Strain 230) was isolated from soil and a certain microbial ingredient proved to have a molluscicidal activity. The effective substance was named antibiotic 230. As a result of several investigations on the antibiotic, the following chemical features were made clear. The chemical substance was an indol-carbazole-heterocyclic compound, the molecular weight 446 and the molecular formula C28H26N4O3. The antibiotic demonstrated a molluscicidal effect against Oncomelania snails and their eggs both in the laboratory and in the field. The compound had a wide bacteriostasis spectrum and a slight toxicity to fish in addition to the above, but it was non-toxic to plants.

Animals↗
PubMed1993

[Effects of capsaicin and electroacupuncture on the fluoride resistant acid phosphatase (FRAP) and acetylcholinesterase (AChE) activities in the dorsal root ganglion (DRG) neurons of rats: a histochemical observation].

UNLABELLED: 31 adult rats were divided into 4 groups: 1) Electroacupuncture group; 2) Capsaicin group (capsaicin was applied one the left sciatic nerve, the night on of the same body was used with vehicle as control); 3) Capaicin combined with electroacupuncture group; 4) Control group. Pain thresholds, both basal and after treatment were determined. Successive cryo-sections of DRG were cut and the neighbouring section of the same group were performed for AChE and FRAP examination. RESULTS: Little disparity in basal pain threshold was found among the four groups. The pain threshold became obviously higher after electroacupuncture, but only slightly higher after capsaicin treatment combined with electroacupuncture. In the electroacupuncture group, the number of DRG-B-type cell containing strong positive FRAP and AChE was obviously more than in the control group. In the capsaicin group, the number of DRG-B-type cell with FRAP and AChE activity was obviously reduced as compared with the untreated side of the same body. In the capsaicin and electroacupuncture group FRAP and AChE-activities in the DRG-B-type cells were slightly increased. The results showed that strong activities of FRAP and AChE were found in part of the DRG cells of normal rats, the two enzymes were found to coexist in the some B-type cells. The effect of electroacupuncture analgesia was depressed after capsaicin treatment, while the activities of the two enzymes and the number of positive cells appeared in the ganglion were reduced correspondingly. Nevertheless, under electroacupuncture analgesia AA the enzymes activities and the numbers of positive cells were increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholinesterase↗
PubMed1993

[HPLC--detection of hydroxyl radicals in striatum extracellular fluid in rats subjected to reperfusion after cerebral ischemia and the action of vitamin E].

The formation of hydroxyl radical in the extracellular fluid in striatum of rats subjected to 4-vessel occlusion during ischemia and reperfusion was measured by HPLC with UV detector using salicylic acid as a trapping agent. Hydroxyl radicals react with salicylic acid yielding 2,3- and 2,5-dihydroxybenzoic acids which can be separated by liquid chromatography. The striatum was perfused with artificial cerebrospinal fluid containing 0.5 mmol.L-1 salicylic acid at a flow rate of 2.5 microliters.min-1. The results indicate that the concentration of 2,5-dihydroxybenzoic acid in the perfusates was highest during 25 min reperfusion and no change was found during ischemia. Vit E at 30, 60 and 120 mg.kg-1 i.p. 20 min before ischemia was shown to dose dependently suppress the rise of 2,5-dihydroxybenzoic acid after reperfusion. The results suggest that the HPLC method is useful and reliable for the measurement of hydroxy radical in global ischemia in vivo.

Animals↗
PubMed1992

A highly sensitive enzyme-linked immunosorbent assay for Clostridium perfringens enterotoxin.

A highly sensitive enzyme-linked immunosorbent assay (ELISA) for quantitation of Clostridium perfringens enterotoxin (CPE) by a sandwich method with polystyrene beads was elaborated. The ELISA was very sensitive with a detection limit of 1 pg/ml of CPE. Clostridium perfringens culture fluid did not interfere with the assay. This ELISA may be useful for the mass screening for Cl. perfringens producing small amounts of CPE.

Biotechnology↗
PubMed1992

Comparison of the pharmacokinetics and electrocardiographic effects of sublingual and intravenous verapamil.

Using a dog model, a sublingual form of the free base of verapamil (SLV) was developed with the intent of avoiding stereoselective first-pass metabolism and the necessity of intravenous administration. Intravenous verapamil (IVV) 5 mg and SLV 40 mg or 60 mg were sequentially administered to seven healthy human volunteers. Electrocardiograms and serum concentrations were obtained before and periodically from 5 to 480 minutes after each dose. The time to peak serum concentration (mean +/- SD) was 77.6 +/- 38.1 minutes after SLV. Bioavailability of SLV was 58.2 +/- 36.9% compared to IVV. Verapamil half-lives after IVV and SLV were 2.83 +/- 0.93 and 2.28 +/- 0.45 hours (NS), respectively. In one subject, the time to peak effect was delayed and overall change in PR interval was minimum. In the remaining six subjects, the maximum percentage increases in PR interval after IVV and SLV were 20.6 +/- 6.4% and 14.8 +/- 5.5% (p less than 0.05), respectively. Times to peak increase in PR interval were 28.3 +/- 15.7 and 57.0 +/- 17.5 minutes after IVV and SLV (p less than 0.05), respectively. Analysis of plots of percentage change in PR interval versus serum concentration revealed a shift to the right and therefore, lesser effect of SLV than of IVV in six subjects. All seven subjects complained of oral numbness and bitter taste. In conclusion, SLV is inferior to IVV in terms of rate and extent of absorption and pharmacologic effect in delaying atrioventricular nodal conduction. Probably SLV has little clinical utility because of its slow onset and poor tolerance.

Administration, Oral↗
PubMed1991

[Effects of AMG-1 on energy metabolism and neuronal damage of ischemic brain in mice and rats].

The effect of AMG-1 [6(5-hydroxy-2-methylpyridylamino)-9 ribofranosylpurine] on mouse brain energy metabolism in complete brain ischemia induced by decapitation and on neurological deficit and histopathological changes after occlusion of the middle cerebral artery (MCAO) in rats were studied. The results indicate that AMG-1 has an effect of improving the status of energy metabolism in complete brain ischemia in mice. Lactate concentration was greatly reduced and the ATP and phosphocreatine levels were significantly elevated. Treatment with AMG-1 or nimodipine was performed before and after MCAO. The score of neurological deficit was significantly decreased as compared with the vehicle treated group. The extent of ischemic neuronal injury was determined by histopathological examination. AMG-1 and nimodipine seemed to attenuate the MCAO-induced neuronal damage. In as much as AMG-1 can improve the status of brain energy metabolism, neurological deficit and neuronal damage after ischemic insult, AMG-1 may have a beneficial effect for the treatment of cerebral ischemic damage.

Adenosine↗
PubMed1991

[A primary report on thrombolytic therapy of acute myocardial infarction in 40 cases].

Forty cases with acute myocardial infarction were treated by thrombolysis from June, 1989 through September, 1990. 32 males and 8 females. Age 44-76 (60 +/- 7.1) years. Coronary angiography was performed in 19 patients 10 days after intravenous thrombolysis on average. With intravenous thrombolysis the reperfusion rates were 69.2% (9/13) for streptokinase and 53.8% (7/13) for urokinase (Green Cross Company, Japan) according to the clinical criteria. No reperfusion was observed in 8 cases treated by China-made urokinase. The reperfusion rate of intracoronary thrombolysis was 85.7% (6/7). 5 cases had hemorrhagic complications, skin ecchymosis in 2 and mild gastrointestinal bleeding in 3, and no transfusion was necessary. No intracranial hemorrhage was noticed.

Adult↗