PubMed HealthSearch

Biomedical subjects

J R Glover

Publications and source records attributed to J R Glover.

At least 19 recordsLinked to original sources

Peroxisome biogenesis in yeast.

Eukaryotic cells have evolved a complex set of intracellular organelles, each of which possesses a specific complement of enzymes and performs unique metabolic functions. This compartmentalization of cellular functions provides a level of metabolic control not available to prokaryotes. However, it presents the eukaryotic cell with the problem of targeting proteins to their specific location(s). Proteins must be efficiently transported from their site of synthesis in the cytosol to their specific organelle(s). Such a process may require translocation across one or more hydrophobic membrane barriers and/or asymmetric integration into specific membranes. Proteins carry cis-acting amino acid sequences that serve to act as recognition motifs for protein sorting and for the cellular translocation machinery. Sequences that target proteins to the endoplasmic reticulum/secretory pathway, mitochondria, and chloroplasts are often present as cleavable amino-terminal extensions. In contrast, most peroxisomal proteins are synthesized at their mature size and are translocated to the organelle without any post-translational modification. This review will summarize what is known about how yeast solve the problem of specifically importing proteins into peroxisomes and will suggest future directions for investigations into peroxisome biogenesis in yeast.

Amino Acid Sequence

Endoscopic ultrasound for localisation of islet cell tumours.

In a prospective study endoscopic ultrasound localisation of pancreatic endocrine tumours was attempted in 21 patients with clinically suspected islet cell tumours. Most patients were referred after the failure of conventional imaging methods. Endoscopic ultrasound correctly identified the site of 12 of 15 insulinomas, one glucagonoma, and a diffuse pancreatic abnormality in a patient with multiple endocrine adenopathy. There were two true negative examinations and one technical failure. The sensitivity of endoscopic ultrasound was much greater than that of computed tomography or conventional transabdominal ultrasonography.

Adenoma, Islet Cell

The Peterborough lorry explosion, 22 March 1989: an analysis of the hospital response.

As a result of the lorry explosion on the Fengate Industrial Estate, Peterborough on 22nd March 1989, 82 casualties arrived at Peterborough District Hospital. Despite the fact that casualties arrived at the A&E Department in large numbers before the Major Accident Plan could be implemented, all of the casualties had been assessed and either admitted or sent home within 3 h of the explosion. In the process several valuable lessons were learned, and their implications are discussed in this paper.

Disaster Planning

Context-based automated detection of epileptogenic sharp transients in the EEG: elimination of false positives.

This paper describes a knowledge-based system for the elimination of false positives in the automated detection of epileptogenic sharp transients in the EEG. The system makes comprehensive use of spatial and temporal context information available on 16 channels of EEG, EKG, EMG, and EOG. A knowledge-based implementation is used because of the ease with which it allows the contextual rules to be expressed and refined. The resulting system is shown to be capable of rejecting a wide variety of artifacts commonly found in EEG recordings, artifacts that cause numerous false positive detections in systems making less comprehensive use of context.

Artificial Intelligence

Phase lock of electrical slow waves and spike bursts in cat duodenum.

The phase relationship between slow waves and spike bursts was studied in vitro in the cat duodenum. Electrodes were arranged radially about the duodenum. Records were read for T1, the time between the slow-wave "valley" and the first spike, and T2, the time between successive valleys. The distributions of the ratio T1/T2 showed very small differences, not uniquely attributable to radial electrode position. The distribution of T1/T2 indicated that spike bursts began 58.8% of the way through a slow-wave cycle, measured from the valley. Also, electrodes were arranged longitudinally and records were read to determine deltaSW, the slow-wave delay time between adjacent electrode positions, and deltaS, the spike burst delay time between adjacent electrode positions. The correlation of deltaS and deltaSW suggested a linear relation, and a regression resulted in a good linear description. These results are consistent with an assumed phase lock of spike bursts to slow waves.

Animals

Stochastic model of contractions at a point in the duodenum.

Contractions at one point in the human duodenum were studied as a time series. Manometric records were made over long time periods from the duodenum in fed human subjects. A 5-s grid was superimposed on the time axis of the records. Each 5-s interval was treated as a slow-wave cycle within which either a contraction or a no-contraction could occur. The resulting series of alternating runs of contractions and no-contractions was tested for the existence of trends. Trends were found indicating possible temporal dependence. A Markov-type model was used to try to generate data similar to the real data. Success was achieved by a model that assumed a probability of contraction dependent on the three previous slow-wave cycles. The frequency distributions obtained from the real and generated data were compared using Chi-square goodness-of-fit tests and found to be statistically similar. The correlations in time found for the contractions might be due to a time dependency in the controls for contraction over four successive slow-wave periods, 20 s in humans.

Animals

Distributions of spike bursts in cat duodenum.

The histograms of spike bursts over short distances were examined in the isolated cat duodenum with multiple electrodes arranged circumferentially and longitudinally. At a single cross section of the duodenum, spike bursts occurred simultaneously in any single slow-wave cycle, but all eight monitored sites in the circumference participated simulatenously only in a bout 25% of the spike-burst cycles. There also were wide variations in the incidence of spike bursts at different locations in a planar cross section. In a longitudinal section, net level of activity over short distances varied widely. Also, spike bursts were out of phase in the longitudinal axis, appearing to spread caudad; 80% of spike burst groups involved less than an average of 5.5 consecutive electrode sites (spaced at 5-mm intervals). Since spike bursts seem to be correlated with ring contractions of the circular muscle, the fact that they appear sequentially in time along the duodenum indicates that such contractions must always be peristaltic. An estimated 80% of such contractions sweep less than about 3 cm. Records of spike bursts from a single electrode do not accurately reflect activity beyond that one point site.

Animals