Rabbit rectus femoris muscle for ischemia-reperfusion studies: an improved model.

The rabbit rectus femoris muscle was evaluated as a potential model for skeletal muscle reperfusion injury studies. Six white New Zealand rabbits were used. On one randomly selected hind limb, ischemia was induced by direct clamping of the rectus femoris muscle's vascular pedicle.

Characterization of a Class of Sigmoid Functions with Applications to Neural Networks.

We study two classes of sigmoids: the simple sigmoids, defined to be odd, asymptotically bounded, completely monotone functions in one variable, and the hyperbolic sigmoids, a proper subset of simple sigmoids and a natural generalization of the hyperbolic tangent. We obtain a complete characterization for the inverses of hyperbolic sigmoids using Euler's incomplete beta functions, and describe composition rules that illustrate how such functions may be synthesized from others. These results are applied to two problems.

Revascularization of the ischemic diabetic foot using popliteal artery inflow.

Between March 1988 and June 1994, 35 popliteal to distal artery vein bypasses were done in 32 diabetic patients. There were 16 males and 16 females with an average age of 60 years. Eighteen patients (56%) had insulin dependent diabetes mellitus.

Perfluorocarbon emulsion prevents eicoasanoid release in skeletal muscle ischemia and reperfusion.

Eicosanoids play an important role in mediating deleterious effects following skeletal muscle ischemia-reperfusion injury. It has previously been shown that oxygenated perfluorocarbon emulsion (O2 Fluosol-DA 20%) decreases the amount of muscle necrosis and neutrophil sequestration when given during the reperfusion phase following skeletal muscle ischemia. As thromboxane is known to alter the endothelial cytoskeleton, thereby favoring diapedesis of neutrophils, the effects of O2 Fluosol-DA 20% on thromboxane release in a canine gracilis muscle model were investigated.

Nucleosomal peptide epitopes for nephritis-inducing T helper cells of murine lupus.

Nucleosome-specific T helper (Th) cells provide major histocompatibility complex class II-restricted, cognate help to nephritogenic antinuclear autoantibody-producing B cells in lupus. However, the lupus Th cells do not respond when components of the nucleosome, such as free DNA or histones, are individually presented by antigen-presenting cells. Thus critical peptide epitopes for the pathogenic Th cells are probably protected during uptake and processing of the native nucleosome particle as a whole.

Selection of patients for cardiac evaluation before peripheral vascular operations.

Purpose: This study evaluated the value of preoperative cardiac screening with dipyridamole thallium scintigraphy and radionuclide ventriculography in vascular surgery patients.

Methods: From July 1, 1989, to Dec. 31, 1991, we routinely (irrespective of the patient's cardiac history or symptomatology) performed dipyridamole thallium scintigraphy (DTS) and radionuclide ventriculography (RVG) in 394 patients being considered for an elective vascular operation.

Effects of the lazaroid U74389G (21 aminosteroid) on skeletal muscle reperfusion injury in rabbits.

The purpose of this experiment was to evaluate the effects of the aminosteroid U74389G on skeletal muscle reperfusion injury in rabbits. In 24 white New Zealand rabbits (weighing 7.0-8.

The aortic polytetrafluoroethylene graft: further experience.

Objectives: We analysed our results with the use of aortic polytetrafluoroethylene PTFE grafts over the last 7.5 years. A historical comparison was also made between the results with non-stretch PTFE (NS-PTFE) (1987-91) and stretch PTFE (S-PTFE) grafts (1991-94).

Impaired mitochondrial metabolism and reduced amphibolic Krebs cycle activity in diabetic rat hepatocytes.

Oxidation of [2,3(14)C] and [1,4(14)C] succinate carbons in the mitochondrial Krebs cycle (KC) was used as a probe to investigate the effect of insulin and diabetes on mitochondrial metabolism in isolated rat hepatocytes. The data presented show that mitochondrial oxidation of succinate carbons and their incorporation into protein and lipid was markedly lower in diabetic and insulin treated diabetic rat hepatocytes. Unlike controls, diabetic rat hepatocytes were unresponsive to in vitro insulin addition.

Lupus: key pathogenic mechanisms and contributing factors.

The past 30 years of research on murine and human systemic lupus erythematosus has served to identify an array of immunological aberrations--some shared, some unique, some primary, others secondary-- that may underlie this disease. In integrating these findings, it appears that at least four distinct pathogenic events characterize lupus: (1) Anti-DNA Abs and immune complexes induce renal damage; (2) B-cells produce pathogenic anti-DNA antibodies; (3) Th cells drive lupus B-cells; and (4) Increased concentrations and abnormal presentation of nucleosomes. The purpose of this review is to examine the roles of these four events in the pathogenesis of lupus and to identify the different factors that can precipitate these pathogenic events.

Impaired mitochondrial protein synthesis in streptozotocin diabetic rat hepatocytes.

Diabetes is associated with decreased protein synthesis; however, there have been very few studies on the effects of insulin or diabetes on mitochondrial protein synthesis. We have recently shown that insulin has a direct stimulatory effect on mitochondrial protein synthesis in isolated rat hepatocytes. In this study we demonstrate that mitochondrial protein synthesis is severely curtailed in hepatocytes isolated from diabetic rats and is unresponsive to in vitro insulin addition.

A comparative evaluation of externally supported polytetrafluoroethylene axillobifemoral and axillounifemoral bypass grafts.

Purpose: We analyzed a current 78-month experience with externally supported (ringed) polytetrafluoroethylene (PTFE) axillobifemoral (AxBF) and axillounifemoral (AxUF) bypass grafts to address the controversy about whether the addition of a femorofemoral limb to an axillofemoral bypass graft improves the patency results.

Methods: Between January 1988 and June 1994, 36 AxBF and 22 AxUF externally supported PTFE ringed bypass grafts were performed at our institution. The age of the patients in the AxBF group was 67 +/- 11 years and 69 +/- 11 years in the AxUF group.

Should all in situ saphenous vein bypasses undergo permanent duplex surveillance?

Objective: To evaluate the need for color duplex surveillance (CDS) for pure in situ bypasses beyond 6 months.

Design: We reviewed our in situ surveillance data from August 1987 to April 1994. Lower-extremity revascularization was performed using 245 pure in situ greater saphenous vein bypasses in 219 patients.

Comparative efficacy and complications of vena caval filters.

Purpose: A variety of vena caval filters (VCFs) are available for usage. The choice of filter type depends on physician preference and certain patient variables. An evaluation of the different VCFs used in our institution was done to compare their efficacy and complication rates.

Interaction between CD40 and its ligand gp39 in the development of murine lupus nephritis.

We investigated the role of gp39-CD40 interaction in the development of glomerulonephritis in lupus mice. In contrast to normal mice, lupus mice had much higher percentages of intensely gp39+ T cells in their spleens even at the preautoimmune age of 1 mo, and the further increase in gp39 expression by anti-CD3 Ab stimulation was markedly greater in lupus T cells. The pathogenic autoantibody-inducing ability of Th clones and splenic Th cells from lupus mice could be blocked in vitro by anti-gp39 Ab.

Efficient classification for multiclass problems using modular neural networks.

The rate of convergence of net output error is very low when training feedforward neural networks for multiclass problems using the backpropagation algorithm. While backpropagation will reduce the Euclidean distance between the actual and desired output vectors, the differences between some of the components of these vectors increase in the first iteration. Furthermore, the magnitudes of subsequent weight changes in each iteration are very small, so that many iterations are required to compensate for the increased error in some components in the initial iterations.

Mechanisms of the pathogenic autoimmune response in lupus: prospects for specific immunotherapy.

A major step towards understanding the basic mechanism of systemic lupus erythematosus (SLE), the prototypic autoimmune disease that develops spontaneously, has been the identification of nucleosomes as a primary immunogen in this disease. The production of pathogenic autoantibodies in SLE results from an MHC class-II-restricted, cognate interaction between select populations of T helper cells and B cells that are specific for nucleosomal components. These observations pave the way for specific immunotherapy that blocks this pathogenic T and B cell interaction.

The management of the infected aortic prosthesis: a current decade of experience.

Purpose: Newer approaches to the patient with an infected aortic graft are available. We reviewed a recent 10-year experience with a more traditional approach to evaluate its outcome in the 1990s.

Methods: From January 1983 to January 1993, 27 patients with an aortic graft infection were treated at our institution.

Outcome of patients with abnormal ocular pneumoplethysmographic measurements undergoing coronary artery bypass grafting.

A total of 1780 patients without symptoms of cerebral ischemia undergoing coronary artery bypass grafting (CABG) were screened before surgery for carotid stenosis by pneumophlethysmography. An abnormal test was defined as a difference in ophthalmic artery pressures of > or = 5 mmHg or ophthalmic-brachial pressure index < or = 0.69.