In vivo validation of a thermodilution system designed to measure peripheral blood flow

A 5F triple-lumen thermodilution catheter was evaluated in a canine vena cava model to determine whether this catheter and the thermodilution technique provide valid in vivo determinations of blood flow. Our ultimate goal is to develop methods for studying limb blood flow in humans. Seven dogs were studied. Blood flow was provided and regulated by a calibrated roller pump. Flow rate determinations by thermodilution were made over a range of 0.5 to 5.01 1/minute. Excellent correlation (r = 0.98, r2 = 0.96, P less than 0.01) was found between actual flow and flow measured by thermodilution. The mean (+/- SD) coefficient of variation for the thermodilution method was 9.97 +/- 5.72 per cent over the flow range tested. The coefficient of variation tended to be higher at low flow rates. The thermodilution technique with this catheter provides valid in vivo determinations of blood flow through large vessels. This technology can be rationally applied to the study of limb blood flow in humans.     

An analysis of the coupling of an injection laser diode to a planar LiNbO3waveguide

Calculated butt coupling efficiency between a GaAlAs double heterostructure laser and a single-mode LiNbO3Ti-diffused optical waveguide is presented in this paper as a function of the transverse displacement, the angular alignment, the longitudinal separation between the laser and the waveguide end surfaces, the radiation field of the laser diode and its dependence on the laser diode structure, and the mode profile of the waveguide and its dependence on experimental diffusion parameters. The maximum efficiency is less than 40 percent because of the mismatch between the waveguide mode and the laser radiation, caused primarily by the experimental limitations in their structures. The effect of the reflection of the waveguide end surface on the laser oscillation has also been estimated.     

Comparative influence of steroid hormones and immunosuppressive agents on autoimmune expression in lacrimal glands of a female mouse model of Sj?gren's syndrome

PURPOSE: Previous research has demonstrated that testosterone therapy causes a profound suppression of autoimmune disease in lacrimal glands of female mouse models of Sj?gren's syndrome. The aim of the present study was to determine whether other anabolic androgens, nonandrogenic steroids, or immunosuppressive agents might duplicate this hormonal effect. For comparative purposes, we also evaluated the influence of these various pharmacologic compounds on the tear volume, the magnitude of lymphocyte infiltration in the submandibular gland, and the extent of mucosal and peripheral lymphadenopathy. METHODS: Female MRL/MpJ-lpr/lpr mice were administered vehicle, steroids, or immunosuppressive compounds for 21 days after the onset of disease. Lacrimal glands and tears, as well as submandibular glands, spleens, and superior cervical and mesenteric lymph nodes were collected immediately before or after treatment and then processed for analysis. RESULTS: Our results showed that: (1) the immunosuppressive impact of testosterone on lymphocyte infiltration in lacrimal tissue was reproduced by the administration of 19-nortestosterone or cyclophosphamide, but not by therapy with 17 beta-estradiol, danazol, the experimental steroid Org 4094, cyclosporine A or dexamethasone; (2) treatment with testosterone, 19-nortestosterone, cyclophosphamide, or dexamethasone significantly reduced the extent of inflammation in salivary glands; (3) exposure to cyclophosphamide markedly diminished the size of lymphatic and splenic tissues, whereas glucocorticoid treatment only decreased the weight of superior cervical lymph nodes; and (4) administration of 17 beta-estradiol, Org 4094, or dexamethasone led to a significant decrease in tear volume. CONCLUSIONS: Overall, these results demonstrate that androgen or cyclophosphamide therapy may successfully ameliorate autoimmune expression in lacrimal and salivary glands of a female mouse model of Sj?gren's syndrome.     

Automatic conversion of triangular finite element meshes to quadrilateral elements

A method is presented for the fully automatic conversion of a general finite element mesh containing triangular elements into a mesh composed of exclusively quadrilateral elements. The initial mesh may be constructed of entirely triangular elements or may consist of a mixture of triangular and quadrilateral elements. The technique used employs heuristic procedures and criteria to selectively combine adjacent triangular elements into quadrilaterals based on preestablished criteria for element quality. Additional procedures are included to eliminate isolated triangles. The methods operates completely without user intervention once the nodal co-ordinates and element connectivity of the original mesh are supplied.     

Review of Depression in the medically ill: An integrated approach.

Reviews the book, Depression in the medically ill: An integrated approach by G. Rodin, J. Craven, and C. Littlefield (see record 1991-97973-000). This book provides an in-depth coverage of current issues in the management of depression in the medically ill. The book is balanced in theoretical perspective and quite comprehensive in coverage of the empirical literature. The authors are well known to the area of depression and physical illness. The book is organized into three main sections dealing with 1) Clinical Presentation, 2) Etiology and Pathogenesis, and 3) Treatment. Numerous case examples are provided throughout to highlight different aspects of symptom presentation, diagnostic problems, and therapeutic management. Notably lacking from the review of prevalence studies is the work examining depression and chronic pain populations. In sum, Rodin et al. have drawn on a vast literature to provide a clear and coherent picture of the current state of knowledge and theory dealing with depression and medical illness. Their book joins a number of recent papers attempting to draw more attention to clinical issues in the management of depression in the medically ill. I would recommend the book to all clinicians who work with medically ill populations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relaxation in Powdered Metallic Antimony in Contact with Liquid 3He

The nuclear spin-lattice relaxation in finely powdered antimony metal immersed in liquid ³ He has been studied at low temperatures. For T < 75 mK, a new surface relaxation mechanism becomes significant. This surface relaxation is due to the modulation by the quantum zero-point motion of the dipole-dipole interaction between the Sb spins at the metal surface and the ³ He spins in the solid-like layer on the surface. Replacement of the liquid ³ He by ⁴ He restores the relaxation rates to the bulk value. This work helps explain anomalies found in previous relaxation studies on powdered Pt immersed in liquid ³ He.     

A Multi-Channel Pulse-Coded Multiplexing and Demodulating Telemetry System

A multiplexing, demodulating, and recording telemetry system designed to process multiple pulse-coded temperature channels is described. The system provides complete control of recording and multiplexing sequences and timing, and gives a single analog signal in response to each sample of pulse-coded data. It identifies all channels and indicates to a computer when a new data sample is to be processed. The system is self-calibrating to maintain accuracy over extended data collection periods, and is inexpensive.     

Quantitative31P nuclear magnetic resonance analysis of the phospholipids of erythrocyte membranes using detergent

³¹P Nuclear magnetic resonance (NMR) spectra of human erythrocyte lysates dissolved in sodium cholate were acquired. The narrow resonances of phospholipids were mostly well resolved, allowing identification and accurate quantitative analysis of phospholipid classes of the erythrocyte membranes. The ether-linked phosphatidylethanolamine components of the erythrocyte membranes were identified, based on the removal of plasmalogens by acidolysis and of diacyl phospholipid species by degradation using phospholipase A₁. It was also shown that the introduction of double bonds on the acyl chains of phosphatidylcholine shifted the³¹P NMR resonances to lower frequencies. Quantitative analyses of phospholipids from the spectra were based on their apparent molar concentrations. The recoveries of phospholipids from erythrocytes were significantly higher than those using conventional extraction procedures.