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Biomedical subjects

S Craft

Publications and source records attributed to S Craft.

59 records · Page 4Linked to original sources
PubMed1986

Identification of the crossover site during FLP-mediated recombination in the Saccharomyces cerevisiae plasmid 2 microns circle.

The FLP protein of the Saccharomyces cerevisiae plasmid 2 microns circle catalyzes site-specific recombination between two repeated segments present on the plasmid. In this paper we present results of experiments we performed to define more precisely the features of the FLP recognition target site, which we propose to designate FRT, and to determine the actual recombination crossover point in vivo. We found that essential sequences for the recombination event are limited to an 8-base-pair core sequence and two 13-base-pair repeated units immediately flanking it. This is the region identified as the FLP binding site in vitro and at which FLP protein promotes specific single-strand cleavages (B. J. Andrews, G. A. Proteau, L. G. Beatty, and P. D. Sadowski, Cell 40:795-803, 1985; J. F. Senecoff, R. C. Bruckner, and M. M. Cox, Proc. Natl. Acad. Sci. USA 82:7270-7274, 1985). Mutations within the core domain can be suppressed by the presence of the identical mutation in the chromatid with which it recombines. However, mutations outside the core are not similarly suppressed. We found that strand exchange during FLP recombination occurs most of the time within the core region, proceeding through a heteroduplex intermediate. Finally, we found that most FLP-mediated events are reciprocal exchanges and that FLP-catalyzed gene conversions occur at low frequency. The low level of gene conversion associated with FLP recombination suggests that it proceeds by a breakage-joining reaction and that the two events are concerted.

Base Sequence↗
PubMed1977

Motor conduction of the anterior interosseous nerve.

Motor conduction examinations of the left anterior interosseous nerve were performed on 25 healthy women. The purposes of this study were to determine the optimal position for placement of the active recording electrode, and to report normal motor conduction values for the anterior interosseous nerve. The anterior interosseous nerve (branch of the median nerve) was stimulated proximal to the elbow and the evoked responses were recorded from three sites over the flexor pollicis longus. The optimal site for placement of the active recording electrode was over the lateral distal one-third of the anterior surface of the forearm at a point representing the distal 38% of the length of the forearm. A latency of 4.0 msec and an amplitude of 2.5 mv may serve as the limits of normal values for motor conduction of the anterior interosseous nerve and for action potentials of the flexor pollicis longus muscle, respectively.

Action Potentials↗
PubMedDate not supplied

Memory improvement following induced hyperinsulinemia in Alzheimer's disease.

Dementia of the Alzheimer type (DAT) is accompanied by disruption in glucose regulation and utilization that may contribute to its characteristic memory impairment. Increasing glucose availability by raising plasma glucose improves memory in patients with DAT. Such memory improvement is associated with a secondary elevation in plasma insulin levels, raising the question of whether improvement is due to changes in insulin levels, independent of hyperglycemia. Distributions of insulin receptors in the hippocampus and insulin-mediated increases in glucose utilization in entorhinal cortex provide potential mechanisms for such improvement. We show that raising plasma insulin through intravenous infusion while keeping plasma glucose at a fasting baseline level produces striking memory enhancement for patients with DAT. Previous findings of hyperglycemic memory enhancement were also replicated. Patients with DAT also showed abnormal plasma levels of glucoregulatory hormones and metabolites at baseline and during metabolic manipulations. Our findings suggest that neuroendocrine factors play an important role in the pathophysiology of DAT.

Aged↗
PubMedDate not supplied

Enduring psychiatric and neuropsychologic sequelae in the post-encephalitis patient.

Initial presentations of encephalitis are sometimes misdiagnosed as psychoses due to the predominance of psychiatric symptoms and frequently negative neurological work-ups. It is likely that many of these errors are never discovered. The patient described herein is an exception. Her symptoms, diagnosis, and treatment have now been followed for nearly two years and suggest not only that the initial diagnosis was in error but also that both psychiatric and organic symptoms can endure as sequelae of encephalitis. Questions regarding optimal treatment and reasons for clinical improvement are addressed.

Adult↗