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Biomedical subjects

S Shumway

Publications and source records attributed to S Shumway.

10 recordsLinked to original sources
PubMed1997

Coronary artery bypass after single lung transplant: a case report.

Chronic obstructive pulmonary disease (COPD) is the most common indication for adult single lung transplantation. These patients commonly have one or more risk factors for coronary artery disease. Traditionally previous lung transplantation has been considered a contraindication to coronary artery bypass grafting (CABG). This report describes a case of CABG 3 yr after single lung transplantation and briefly discusses the risks of cardiac surgery in lung transplant patients.

Contraindications↗
PubMed1996

Efficiency of the flexor tendon pulley system in human cadaver hands.

The efficiency of the flexor tendon system was examined in a human cadaver model. Pulleys were randomly sectioned, and the results were evaluated on the basis of the tendon excursion, force generated at the fingertip, and the work (force multiplied by distance) involved, as compared to the intact pulley system. When a single minor pulley (A1 or A5) was cut, there was no statistical difference in work efficiency or excursion efficiency from controls. Cutting all minor pulleys (A1, A3, A5) lead to a significant loss in excursion efficiency. The intact three pulley systems of A2, A3, and A4 were near normal and statistically better than A2 and A4 together for work efficiency. Cutting one of the major pulleys (A2, A4) resulted in significant changes in efficiency, but what was unexpected was to find an 85% loss of both work and excursion efficiency for the loss of A4 but only an excursion difference of 94% for the loss of A2. Our findings demonstrated that in this model, with the influence of the skin removed, A4 absence produced the largest biomechanically measured efficiency changes and that a combination of A2, A3, and A4 was necessary to preserve both work and excursion efficiency.

Biomechanical Phenomena↗
PubMed1994

Mechanical comparison of 10 suture materials before and after in vivo incubation.

The material properties of ten 2-O suture materials were evaluated tensiometrically at time = 0 and again after 6 weeks incubation in rats. All suture material was incubated and tested without knots. Specialized machinery was used with a custom securing apparatus to pull suture material apart at constant speed. Stress-strain curves were derived, and from these strength, toughness, strain at rupture, and elastic modulus were determined. Sutures tested included Vicryl [poly(glycolide-lactide)], Dexon (polyglycolic acid), Ethibond (polyester), silk, plain gut, chromic gut, Maxon (polyglyconate), PDS (polydioxanone), nylon, and Prolene (polypropylene). Elastic modulus was greatest for braided, least for monofilament, and intermediate for gut sutures, regardless of chemical composition (ANOVA, P = 0.0001). Strength, strain, and toughness decreased in all of the sutures over time in vivo with the exception of braided polyester (Ethibond), which remained stable. Silk demonstrated the least strength and toughness while PDS and Maxon were the strongest and toughest at time = 0. Vicryl, Dexon, and gut sutures were absorbed to the point that they could not be tested after 6 weeks in vivo. Performance tables are provided for all sutures.

Animals↗
PubMed1994

Dynamic analysis of profundus tendon function.

A method for analysis of hand function is reported through evaluation and characterization of flexor digitorum profundus (FDP) tendon mechanics. A testing platform is used that allows for the dynamic evaluation of intact cadaver hand mechanics under normal and pathologic conditions using simultaneous measurements of tendon load, tendon excursion, grip strength, pinch strength, and joint angle. This study of FDP tendons in normal fresh cadaver hands demonstrates that FDP tendon excursion increases as the number and size of joints flexed increases. Extensor counterweighting 500 g, increases FDP tendon load and work but not excursion requirements, and FDP loads of up to 75 N are required for single finger grip strengths of 4 kg force. These loads do not result in permanent (plastic) deformation of either the tendon or the restraining soft tissues. Detailed descriptions of the platform and the mechanical tests performed are provided.

Adult↗
PubMed1993

Endogenous versus toxin-induced diabetes in rats: a mechanical comparison of two skin wound-healing models.

This study was designed to compare skin wound healing in three groups of Wistar rats: normal, genetically diabetic, and streptozotocin-induced diabetic. All diabetic animals received daily insulin. Full-thickness midline dorsal skin wounds were analyzed biomechanically for strength, toughness, and elasticity (Young's modulus) at 1 and 3 weeks after wounding. Wounds from normal controls were the strongest, toughest, and least compliant. Genetically diabetic rat wounds were the weakest and had the lowest elastic modulus. Wounds from the streptozotocin-induced rats were intermediate for all parameters measured (ANOVA, p = 0.001). Toxin-induced diabetes is less detrimental to skin wound healing than diabetes of endogenous origin. Whether this is due to basic differences in the models or to differences in duration of diabetes is unknown.

Animals↗
PubMed1989

Successful human double-lung transplantation after five and one-half hours of preservation.

Successful clinical double-lung transplantation after 5 1/2 hours of pulmonary ischemia is reported. Static hypothermic preservation with a high-volume, high flow rate-modified Collin's solution pulmonary artery flush was used. Excellent early and late pulmonary function demonstrates the efficacy of the technique that is described in detail. Lung transplantation remains limited by the lack of reliable methods of long-term storage of donor organs, but refinement of current techniques may soon allow its wider application.

Adult↗
PubMed1988

Surgical treatment for double-outlet right ventricle at the Brompton Hospital, 1973 to 1986.

Between January 1973 and February 1986, operations were performed on 120 consecutive patients having usual atrial arrangement (atrial situs solitus), concordant atrioventricular connection, and double-outlet right ventricle. The ages at operation ranged from 1 day to 44 years and the weights from 2.6 to 84 kg. Sixty-three patients had one or more palliative procedures. For those, the hospital mortality rate was 9.5%. Palliation was considered a definitive procedure in 13 patients. Ninety-three patients had a reparative operation, with a 26.9% early mortality rate. In the group who had complete correction, taken as a whole, the surgical outcome was significantly affected by the position of the ventricular septal defect and by the year of operation. The year of operation was the main factor that, by multivariate analysis, correlated significantly with the hospital mortality in those patients having a subaortic defect and spiraling great arteries (p less than 0.05). No difference was found among this group for those patients having the morphologic characteristics of tetralogy of Fallot. The change-over point from the Mustard to the arterial switch procedures was the event with the greatest effect on hospital mortality in patients with a subpulmonary ventricular septal defect (p less than 0.025). Two late deaths have occurred among the 21 patients who had palliative intervention only. Sixty of the 68 survivors with intracardiac repair have been followed up for a period of 2 to 184 months (median 44 months). There were five late deaths (8.3%). Eight patients underwent successful reoperation. All except three of the long-term survivors were in functional class I. Good early and long-term results can be anticipated for the intracardiac repair of double-outlet right ventricle when the ventricular septal defect is subaortic or doubly committed. The arterial switch operation has been demonstrated to be the optimal approach for double-outlet right ventricle with subpulmonary ventricular septal defect. Results in patients with noncommitted ventricular septal defect have remained poor.

Adolescent↗
PubMed1985

Nutrition and immunity: the immunoregulatory effect of n-6 essential fatty acids is mediated through prostaglandin E.

Suppression of cell-mediated immune responses by essential fatty acids (EFA) was demonstrated in mice maintained on a standard laboratory diet for rodents. Daily oral administration of EFA at doses ranging from 125 to 750 mg/kg body weight significantly suppressed local host-versus-graft and graft-versus-host reactions as measured by popliteal lymph node assay. Studies employing immune sera directed against E-type prostaglandin demonstrated that n-6 EFA-induced suppression was mediated through prostaglandin E1. In titration experiments the effect of n-6 EFA on the reactions was dose dependent with enhancement of the responses at low concentrations and suppression at high concentrations.

Alprostadil↗
PubMedDate not supplied

Hemodynamically significant suture line obstruction immediately after heart transplantation.

Mechanical complications after heart transplantation are uncommon. We describe a case of hemodynamically significant suture line obstruction that was recognized immediately after heart transplantation using transesophageal echocardiography. Transesophageal echocardiography has proved to be a powerful tool in recognizing mechanical complications in the early posttransplant period.

Adult↗