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Biomedical subjects

R S Jones

Publications and source records attributed to R S Jones.

At least 19 recordsLinked to original sources
PubMed1992

A Drosophila model for xeroderma pigmentosum and Cockayne's syndrome: haywire encodes the fly homolog of ERCC3, a human excision repair gene.

The haywire gene of Drosophila encodes a protein with 66% identity to the product of the human ERCC3 gene, associated with xeroderma pigmentosum B (XP-B) and Cockayne's syndrome (CS). XP is a human autosomal recessive disease characterized by extreme sensitivity to ultraviolet irradiation and marked susceptibility to skin cancer. In addition, XP and CS patients often exhibit a variety of defects, ranging from central nervous system disorders to hypogonadism. Phenotypes of haywire mutants mimic some of the effects of XP. Many haywire alleles are recessive lethal, viable alleles cause ultraviolet sensitivity, and files expressing marginal levels of haywire display motor defects and reduced life span. Progeny of females carrying a maternal effect allele show central nervous system defects.

Amino Acid Sequence↗
PubMed1992

Beneficial effects of prewarming the donor liver for rat liver transplantation.

Cold preservation of donor liver can injure the microcirculation enough to impair the function and survival of the transplanted liver. In this study, prewarming the donor liver to 10 degrees C to 12 degrees C after cold storage prior to implantation significantly increased survival rates in rats 1 week after surgery. Following 6, 8, or 9 hours of cold storage in chilled normal saline, prewarming increased survival rates from 40% to 78.6%, from 0% to 35.7%, and from 0% to 14.3%, respectively. The results suggest that pretreatment of the donor liver with warmth following cold storage and before implantation will improve the survival rate of liver transplanted rats.

Animals↗
PubMed1992

A simple method for bile duct anastomosis and interval bile collection in the liver-transplanted rat.

A mini T-tube is introduced for the bile duct anastomosis of rat liver transplantation as well as interval bile collection. The validity of the T-tube was evaluated in 14 liver-transplanted rats and compared to 14 rats using traditional stent for bile duct anastomosis. Changes of biliary tree after the T-tube anastomosis were examined by T-tube cholangiography on sample rats at 4 days and at 4 months after liver grafting. Additionally, bile volumes and rates of bile salt secretion were compared in the continuously flowing cannula and the chronic T-tube fistula in normal rats. The results show that the mini T-tube facilitates bile duct anastomosis and study of bile secretion after liver transplantation in rats without increase in surgical difficulty or interference of biliary enterohepatic circulation.

Anastomosis, Surgical↗
PubMed1992

Gentle teaching and applied behavior analysis: a critical review.

In recent years, there has been a growing controversy surrounding gentle teaching. This paper explores the nature of this controversy with particular reference to the relationship between gentle teaching and applied behavior analysis. Advantages and disadvantages of this approach are discussed, and it is suggested that gentle teaching and applied behavior analysis need not be regarded as mutually exclusive approaches to working with persons with mental retardation.

Aggression↗
PubMed1991

Development of a functional innervation of the iris dilator muscle by sympathetic nerve fibres in the rat.

These studies using both in situ and in vitro preparations were designed to determine the time of onset of a functional sympathetic innervation to the dilator muscle of the rat iris during postnatal development. The preganglionic nerve trunk to the superior cervical ganglion was stimulated and measurements made of pupil diameter. Alternatively, intracellular recordings were made from the dilator muscle cells and the response to stimulation of the intramural nerves was measured. During the second postnatal week, a decrease in the resting pupil diameter under low lighting conditions was observed, reflecting the normal developmental increase in size of the iris. On account of the small size of the iris in rats up to 10 days postnatal, the in vivo experiments were a reliable test of a functional innervation only in older animals. In all cases, stimulation of the preganglionic nerve trunk in situ caused dilatation of the pupil. Stimulation of the sympathetic nerves in vitro, in preparations of iris taken from rats of various ages, evoked a slow depolarisation mediated via alpha adrenoceptors. Such responses could be recorded in irides from rats as young as 3 days postnatal. Spontaneous activity was recorded in irides towards the end of the second postnatal week just prior to the time of normal eye opening, and may reflect the onset of photomechanical coupling. We conclude that the sympathetic nerves within the iris are capable of evoking membrane potential changes in the dilator muscle cells in the early postnatal period, well before the nerve plexus in the iris is fully differentiated.

Animals↗
PubMed1991

Laparoscopic cholecystectomy. Treatment of choice for symptomatic cholelithiasis.

Our initial experience with laparoscopic cholecystectomy (LC) for symptomatic cholelithiasis has involved 152 patients. Patient age ranged from 17 to 83 years; most were female (78%). Their average weight was 170 pounds (range, 75 to 365 lbs.). Twenty-two per cent had a single gallstone, while 9% had two to three stones and 64% had more than three stones. Exclusion criteria initially included upper abdominal scarring, severe acute cholecystitis, choledocholithiasis, and inability to tolerate general anesthesia. The first two of these are now only relative contraindications with increased experience. Thirteen of the one hundred fifty-two procedures (8.5%) required conversion to an open operation. Average time of operation was 138 minutes. Intraoperative cholangiography was attempted in 78% of cases and was completed successfully in 66% of those attempted. There have been no deaths. The complication rate has been low: 4% major, 0% life-threatening, and 7.2% minor complications. Postoperative analgesic requirements are remarkably low: 36% of patients required no narcotics after leaving the recovery room. Eighty-seven per cent of patients successfully undergoing LC were discharged by the first postoperative day. Most patients resumed normal activities within 1 week after discharge. Laparoscopic cholecystectomy offers the majority of patients with symptomatic cholelithiasis an improved treatment option, resulting in significantly less postoperative pain, hospitalization, and recuperation time.

Adolescent↗
PubMed1990

The effect of ursodiol on the efficacy and safety of extracorporeal shock-wave lithotripsy of gallstones. The Dornier National Biliary Lithotripsy Study.

BACKGROUND: In the treatment of gallstones with extracorporeal shock-wave lithotripsy, the bile acid ursodiol is administered to dissolve the gallstone fragments. We designed our study to determine the value of administering this agent. METHODS: At 10 centers, 600 symptomatic patients with three or fewer radiolucent gallstones 5 to 30 mm in diameter, as visualized by oral cholecystography, were randomly assigned to receive ursodiol or placebo for six months, starting one week before lithotripsy. RESULTS: The stones were fragmented in 97 percent of all patients, and the fragments were less than or equal to 5 mm in diameter in 46.8 percent. On the basis of an intention-to-treat analysis of all 600 patients, 21 percent receiving ursodiol and 9 percent receiving placebo (P less than 0.0001) had gallbladders that were free of stones after six months. Among those with completely radiolucent solitary stones less than 20 mm in diameter, 35 percent of the patients receiving ursodiol and 18 percent of those receiving placebo (P less than 0.001) were free of stones after six months. Biliary pain, usually mild, occurred in 73 percent of all patients but in only 13 percent of those who were free of stones after three and six months (P less than 0.01). There were few adverse events. Only diarrhea occurred with a significantly different frequency in the two groups: 32.6 percent were affected in the ursodiol group, as compared with 24.7 percent in the placebo group (P less than 0.04). Severe biliary pain occurred in 1.5 percent of all patients, acute cholecystitis in 1.0 percent, and acute pancreatitis in 1.5 percent; endoscopic sphincterotomy was performed in 0.5 percent, and cholecystectomy in 2.5 percent. CONCLUSIONS: Extracorporeal shock-wave lithotripsy with ursodiol was more effective than lithotripsy alone for the treatment of symptomatic gallstones, and equally safe. Treatment was more effective for solitary than multiple stones, radiolucent than slightly calcified stones, and smaller than larger stones.

Blood Pressure↗
PubMed1990

Prolonged electrophysiological maturation of transplanted hippocampal neurons.

The CA1 region of the rat hippocampal formation was lesioned by transient forebrain ischemia and subsequently repopulated with dispersed fetal hippocampal neurons. Using the hippocampal slice preparation, 7-12 months post-transplantation, intracellular recordings were made during synaptic activation and extracellular calcium measurements were made during iontophoretic application of excitatory amino acids. The data indicate that the developmental period of the transplanted neurons is prolonged with respect to N-methyl-D-aspartate (NMDA) receptor-mediated responses and may be involved in maintaining calcium dependent developmental processes such as fiber outgrowth.

Animals↗
PubMed1990

The role of excitatory amino acid receptors in the propagation of epileptiform discharges from the entorhinal cortex to the dentate gyrus in vitro.

The relationship between epileptiform events in the medial entorhinal cortex (MEC) and the dentate gyrus was investigated using a slice preparation from rat brain. Simultaneous intracellular recordings were made from neurones in layer II of the MEC and neurones in the granule cell layer of the dentate gyrus (DGC). Epileptiform activity was induced by perfusion with Mg+(+)-free medium or GABAA-receptor blockers. Epileptiform discharges in MEC cells were reflected on a one-to-one basis and at a latency of 1-3 ms by depolarizing events in DGC. The latter rarely gave rise to action potentials. Bath perfusion of the N-methyl-D-aspartate (NMDA) receptor blocker, 2-aminophosphonovalerate (2-AP5) abolished the Mg+(+)-free induced events in MEC cells and the corresponding depolarizations in the DGC but local application of 2-AP5 to the dentate gyrus only reduced the depolarizations. The non-NMDA-receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), whether bath applied or applied locally to the DG, had little effect on the cortical events but strongly reduced the depolarizations of the DGC. The discharges induced in MEC cells by GABA-blockers were reduced by bath applied 2-AP5 but abolished by CNQX. These effects were mirrored in the dentate gyrus by a reduction in the depolarizing events by 2-AP5 and their abolition by CNQX. Local application of either antagonist to the dentate gyrus reduced but did not abolish the depolarizations. Thus, Mg+(+)-free induced events in MEC depend mainly on enhanced NMDA-receptor activity, while events induced by bicuculline are primarily dependant on non-NMDA receptors. The depolarizing events in the DGC which reflect the activity in the EC are mediated by both types of receptor, although non-NMDA receptors play a much greater role.

2-Amino-5-phosphonovalerate↗