Isolation of ultrapure supercoiled plasmid-DNA using preparative electrophoresis

A large-scale preparative polyacrylamide gel electrophoresis (PAGE) system for the isolation of high-purity supercoiled plasmid-DNA is described. This method should prove suitable for the isolation of large DNA molecules, either plasmid or linear DNA, that is required for the production of transgenic animals, for instance. The efficiency of the method is illustrated by the isolation of the gene for the green fluorescent protein, cloned into a mammalian expression vector and used for transfection of eukaryotic cells.     

Thoracic epidural anaesthesia for coronary artery bypass graft surgery. Effects on postoperative complications

We have performed a retrospective analysis of the peri-operative course of 218 consecutive patients who underwent routine coronary artery bypass graft surgery in this institution. All patients received a standardised general anaesthetic using target-controlled infusions of alfentanil and propofol. One hundred patients also received thoracic epidural anaesthesia with bupivacaine and clonidine, started before surgery and continued for 5 days after surgery. The remaining 118 patients received target-controlled infusion of alfentanil for analgesia for the first 24 h after surgery, followed by intravenous patient-controlled morphine analgesia for a further 48 h. Using computerised patient medical records, we analysed the frequency of respiratory, neurological, renal, gastrointestinal, haematological and cardiovascular complications in these two groups. New arrhythmias requiring treatment occurred in 18% of the thoracic epidural anaesthesia group of patients compared with 32% of the general anaesthesia group (p = 0.02). There was also a trend towards a reduced incidence of respiratory complications in the thoracic epidural anaesthesia group. The time to tracheal extubation was decreased in the epidural group, with the tracheas of 21% of the patients being extubated immediately after surgery compared with 2% in the general anaesthesia group (p < 0.001). There were no serious neurological problems resulting from the use of thoracic epidural analgesia.     

Couplages entre sources imprimées actives Analyse ďun réseau fini à deux dimensions de sources plates actives Application au balayage électronique

Three kinds of mutual coupling between active printed antennas, due to respectively space waves, surface waves and feed line, are evaluated and expressed with analytical forms which are in good agreement with experiments. There are two problems associated when using thicker substrate to broaden the microstrip antenna bandwidth : increase in surface waves and coaxial line coupling effects, and deterioration of the radiation pattern. The solution to the problem is to make use of substrates with very low relative permittivity to put a Lecher-line instead of a coaxial line. The different couplings between all radiating elements have been taken into account to calculate the active impedance of the individual element and the perturbation of radiation characteristics for a scanned beam array at reception.     

Standardized protocol interfaces

A traditional protocol implementation typically consists of at least two distinct parts, a sender and a receiver. Each part runs on a distinct machine, with the implementation provided by a local expert. At best, the two machines are of the same type and the protocol implementations are provided by the same person. More likely, however, the machines are not of the same type and the implementations of the two halves of the protocol are provided by two different people, working from an often loosely defined protocol specification. It seems almost unavoidable that the two implementations are not quite compatible. In this paper we consider an alternative technique. With this method, one of the two implementors can design, formally validate, and implement all the relevant protocol parts, including those parts that are to be executed remotely. Each communication channel is now terminated on the receiving side, by a single standard protocol interface, which can be called a universal asynchronous protocol interface, or UAPI. Though it is likely that the UAPI is most efficiently implemented in hardware, it can also trivially run as a software module, e.g. under a standard UNIX® operating system (in our case under 10th Edition Research Unix). This paper introduces the concept of a UAPI and explains how the sample software controller was constructed.     

Cytochromes P450 and drug resistance

Cytochromes P450 are the key enzymes for activating and inactivating many drugs, in particular anticancer drugs. Therefore, individual expression levels of cytochromes P450 may play a crucial role in drug safety and drug efficacy. Overexpression of cytochrome P450 may yield rapid turnover and elimination of drugs before the target site was reached and any pharmacological effect is observed. Therefore, it may be vital to know the individual cytochrome P450 status in order to select the appropriate drug before drug resistance occurs. Expression levels and activity of cytochromes P450 depend on many different factors. These factors include tissue and organ specific expression, sex- and age-dependent expression, genetic differences yielding polymorphic forms, competitive inhibition or induction of cytochromes P450 due to multiple drug interaction, nutrition and diet. Genetically engineered test cells defined for cytochromes P450 are available for studying drugs for metabolic activation and for identifying the metabolically competent cytochrome P450 isoform.     

Long-term outcomes of patients receiving percutaneous endoscopic gastrostomy tubes

OBJECTIVE: Percutaneous endoscopic gastrostomy (PEG) tube placement is the preferred method for long-term enteral feeding of patients who are unable to take food by mouth. Despite the widespread acceptance of the procedure, no large-scale study of the long-term outcomes of patients receiving PEG tubes has been reported. The objective of this study was to determine the survival of patients in whom PEG tubes are placed. DESIGN: Retrospective cohort study using data obtained from two computerized databases. SETTING: Department of Veterans Affairs hospitals. PATIENTS: Seven thousand three hundred sixty-nine patients who received a PEG tube in fiscal years 1990 through 1992. RESULTS: For the 7,369 patients, the mean age was 68.1 years and 98.6% were men. PEG tubes were most commonly places in patients with cerebrovascular disease (18.9%), other organic neurologic disease (28.6%), or head and neck cancer (15.7%). Although the complication rate of the procedure itself was low (4%), because of the severity of their underlying disease, 1,732 patients (23.5%) died during the hospitalization in which the PEG tube was placed. The median survival of the full cohort was 7.5 months. CONCLUSIONS: This study documents the widespread placement of PEG tubes in severely ill patients, half of whom are in the terminal phase of their illness. Further study is needed to determine whether these patients benefit from PEG tube placement in terms of their quality of life and survival.     

A Universal Transducer Interface for Capacitive and Resistive Sensor Elements

This paper presents a new universal transducer interface.This interface, which is read out by a microcontroller, servicesthe following sensor elements: capacitors, platinum resistors,thermistors, resistive bridges and potentiometers. The A/D conversionis based on a first-order oscillator. A combination of classicaland some new measurement techniques has been applied on a singlechip to obtain high accuracy, good long-term stability and areduction of the effects of interference and parasitic elements.The circuit has been fabricated in a 0.7 µm CMOSprocess. The main test results are: an accuracy of 10–15bits and a resolution up to 16 bits while the measurement timeis in the range 1–100ms. These results hold over the temperaturerange –20°C to 80°C. Calibrationof the electronic part is not required. The number of externalcomponents has been kept to a minimum.