The lowest effective intensity of prophylactic anticoagulation for patients with atrial fibrillation.

BACKGROUND: Stroke prevention trials in patients with atrial fibrillation (AF) mainly studied the use of warfarin in Caucasians, and the international normalized ratio (INR) was targeted in the range of 2-4. The result may not necessarily be applicable to other ethnic groups. This study aimed to determine the optimal intensity of anticoagulation for stroke prevention in Chinese patients. METHODS: We performed a retrospective study on all Chinese patients with AF taking warfarin for stroke prevention in our hospital from January 1, 2000, to June 30, 2002. Patients with a mechanical heart valve were excluded. We systematically studied their indication of using warfarin, duration of therapy and all INR results. Only those patients whose indications of using warfarin were consistent with the ACC/AHA/ESC Executive Summary were included. Thrombo-embolic episodes, sudden death, major bleeding, intracranial haemorrhage and the INR at the time of the event were recorded. The INR range was divided into six categories: <1.5, 1.5-1.9, 2.0-2.5, 2.6-3.0, 3.1-3.5, >3.5. The number of events was recorded for each category, and this formed the numerator. The denominator was the summation of time each patient stayed in each category of INR. The event rate was then calculated for each INR category. RESULTS: 555 patients were included in the analysis, they constituted 893 patient-years. The INR was kept below 2.6 in 84.9% of the time and between 1.5 and 1.9 in 35% of the time. The overall event rate in our patients was 6.0%, of which 3.9% were due to thrombo-embolic events and 2.1% were due to serious bleeding. The overall event rate was lowest in the INR range from 1.5 to 1.9. which is not significantly different from that of INR 2.0-2.5 and 2.6-3.0. The overall event rate was 3.6% in INR 1.5-3.0 which was significantly lower than 15.1% in INR <1.5 and 20.5% in INR >3.0 (p < 0.01). CONCLUSIONS: Our retrospective cohort showed that a lower INR range of 1.5-3.0 was safe and effective for stroke prevention in Chinese patients treated in a single hospital.

Epileptic seizure after stroke in Chinese patients.

This was a hospital-based cohort study aiming at determining the occurrence rate of post-stroke seizures and the associated risk factors. From 27 July 1996 to 16 June 1998, the first 1000 consecutive patients in the acute stroke registry were retrospectively reviewed for one year after acute stroke to identify seizure occurrence. The demographic data, seizure onset time, seizure type, drug treatment, response to medication, electroencephalogram findings and cranial computed tomogram findings were collected. Thirty-four patients (3.4%) developed seizure within one year after acute stroke. Univariate analysis revealed that male, age greater than 65 years, total anterior circulation infarction, partial anterior circulation infarction, cortical location and large lesion were significantly associated with post-stroke seizure while multivariate analysis showed that only male (adjusted OR 3.21, p<0.01) and cortical location (adjusted OR 3.83, p<0.05) were significant independent risk factors. Fifty-six percent of early seizures were partial type whereas 72% of late seizures were generalized tonic-clonic type of undetermined onset. Seizures occurred in 3.4% of patients within one year after the onset of stroke. This percentage of seizure occurrence and associated risk factors were similar to other studies. However, intracerebral and subarachnoid haemorrhage were not shown to be risk factors in our study.

Production of carboxylic acids from hydrolyzed corn meal by immobilized cell fermentation in a fibrous-bed bioreactor.

Corn meal hydrolyzed with amylases was used as the carbon source for producing acetic, propionic, and butyric acids via anaerobic fermentations. In this study, corn meal, containing 75% (w/w) starch, 20% (w/w) fibers, and 1.5% (w/w) protein, was first hydrolyzed using amylases at 60 degrees C. The hydrolysis yielded approximately 100% recovery of starch converted to glucose and 17.9% recovery of protein. The resulting corn meal hydrolyzate was then used, after sterilization, for fermentation studies. A co-culture of Lactococcus lactis and Clostridium formicoaceticum was used to produce acetic acid from glucose. Propionibacterium acidipropionici was used for propionic acid fermentation, and Clostridium tyrobutylicum was used for butyric acid production. These cells were immobilized on a spirally wound fibrous matrix packed in a fibrous-bed bioreactor (FBB) developed for multi-phase biological reactions or fermentation. The bioreactor was connected to a stirred-tank fermentor that provided pH and temperature controls via medium circulation. The fermentation system was operated at the recycle batch mode. Temperature and pH were controlled at 37 degrees C and 7.6, respectively, for acetic acid fermentation, 32 degrees C and 6.0, respectively, for propionic acid fermentation, and 37 degrees C and 6.0, respectively, for butyric acid production. The fermentation demonstrated a yield of approximately 100% and a volumetric productivity of approximately 1 g/(1 h) for acetic acid production. The propionic acid fermentation achieved an approximately 60% yield and a productivity of 2.12 g/(1 h), whereas the butyric acid fermentation obtained an approximately 50% yield and a productivity of 6.78 g/(1 h). These results were comparable to, or better than those fermentations using chemically defined media containing glucose as the substrate, suggesting that these carboxylic acids can be efficiently produced from direct fermentation of corn meal hydrolyzate. The corn fiber present as suspended solids in the corn meal hydrolyzate did not cause operating problem to the immobilized cell bioreactor as is usually encountered by conventional immobilized cell bioreactor systems. It is concluded that the FBB technology is suitable for producing value-added biochemicals directly from agricultural residues or commodities such as corn meal.