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Biomedical subjects

B Rothman

Publications and source records attributed to B Rothman.

11 recordsLinked to original sources
PubMed1997

The effect of in vitro modeling conditions on the surface reactions of bioactive glass.

Using one parametric variation in solution composition, this paper documents that the surface reactions on bioactive glass (BG) 45S5 are exquisitely dependent upon the modeling conditions. The solutions used were 0.05 M tris hydroxymethyl aminomethane/HCl (tris buffer), tris buffer complemented with plasma electrolyte and/or serum, and serum. The reacted surfaces were analyzed using Fourier transform infrared (FTIR), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDXA), and Rutherford backscattering spectroscopy (RBS). Post-immersion solutions were analyzed for changes in Ca and PO4 concentrations. After a short immersion (3 h), a crystalline, carbonated hydroxyapatite (c-HA) layer formed only in tris. Reaction surfaces of different structure, morphology, and composition were observed after various short and longer term immersions in all other solutions. They comprised two layers with the layer in contact with the bulk consisting mainly of Si; the outer layer, composed of Si, Ca, and P, was amorphous, and had a Ca/P ratio of about 1. Serum proteins adsorbed on the BG surfaces at the early stages of the solution-mediated BG reactions. Formation of a crystalline c-HA layer was delayed up to three or more days in solution with plasma ions. In the presence of serum, only amorphous surfaces composed of Si, Ca, and P were observed for any time up to seven days of immersion. The present data suggest that serum proteins adsorb in tandem with the occurrence of solution-mediated reactions leading to formation of a silica-gel. Amorphous Ca-P phases accumulate in the Si-rich matrix. Furthermore, the present data, in conjunction with the data published before, suggest that physicochemical and cell-mediated reactions occur in parallel to form the glass-tissue interfacial layer.

Biocompatible Materials↗
PubMed1991

Cytokine regulation of C3 and C5 production by human corneal fibroblasts.

Recent investigations have suggested that cytokines play important roles during inflammation and host defense, primarily by regulating the diverse functions of immunologic cells (e.g. lymphocytes and monocytes). However, much less is known about the capacity of cytokines to also regulate the functions of resident tissue cells. We hypothesize that during inflammation, cytokines (e.g. monokines and lymphokines) directly regulate the expression of inflammatory precursors and mediators, such as the third and fifth complement components, by resident ocular cells and are therefore important in the local regulation of ocular inflammation. To test this hypothesis we developed an in vitro culture system utilizing isolated human corneal fibroblasts and examined the effects of specific cytokines, i.e. interleukins and interferons, on the production of the third and fifth components of the complement system. Human corneal fibroblasts were cultured in the presence of varying concentrations (1-500 U ml-1) of interleukin 1 alpha, interleukin 1 beta, interleukin 2, interferon alpha and interferon gamma for 48 hr at 37 degrees C, 5% CO2. The supernatants were then evaluated for antigen levels for the third and fifth components of complement using specific enzyme-linked immunospecific assays. These studies revealed that both interleukin 1 alpha and interleukin 1 beta induced seven to tenfold increases in the levels of the third component. Similarly interferon alpha and interferon gamma stimulated an approximate four and ninefold dose-dependent increase, respectively, in the production of the third component. Analysis of the effect of interleukin 2 on third component production demonstrated that higher concentrations (100 U ml-1) were required to induce a fivefold increase in the production of the third component.(ABSTRACT TRUNCATED AT 250 WORDS)

Cells, Cultured↗
PubMed1990

Heating of the scrotum by high-field-strength MR imaging.

Sterility can occur in mammals if spermatogenic tissue is acutely or chronically heated to levels equal to or greater than body temperature. High-field-strength MR imaging has been shown to elevate tissue temperatures, particularly if high levels of RF radiation are used. To determine if MR imaging above the recommended level for RF radiation is associated with heating of the scrotum, scrotal skin temperatures were measured in eight subjects immediately before and after MR imaging of the scrotum with a 1.5-T, 64-MHz MR scanner at mean whole-body average specific absorption rates ranging from 0.56 to 0.84 W/kg (mean, 0.72 W/kg). The average imaging time was 23 min. A statistically significant (p less than .01) increase in average scrotal skin temperature was associated with MR imaging (before MR imaging, 30.8 degrees C; after MR imaging, 32.3 degrees C). The largest change in temperature was 3.0 degrees C, and the highest temperature measured was 34.1 degrees C. MR imaging at relatively high specific absorption rates produced a statistically significant increase in average scrotal skin temperature. However, the recorded temperatures were below the threshold known to affect spermatogenesis in mammals.

Adult↗
PubMed1980

Neuroethological studies of freely swimming Aplysia brasiliana.

Recently developed neurophysiological and behavioural techniques were used to study swimming in the marine gastropod Aplysia brasiliana. Aplysia swim by bilateral parapodial flapping with an anterior to posterior metachronal wave. Parapodial oscillations are measured from video records. Population recordings from nerves innervating the parapodia during normal swimming in intact Aplysia reveal synchronous phasic activity in large efferent units associated with parapodial opening. Isolated brain studies and stimulation of central pathways in intact animals suggest a central pattern generator. We conclude that the output of the neuronal oscillator that controls parapodial flapping radiates synchronously from each pedal ganglion. The putative command to swim originates within the cerebral ganglia.

Animals↗
PubMed1979

Lymphocyte adherence in multiple sclerosis.

It has been reported that peripheral blood lymphocytes from patients with multiple sclerosis (MS) adhere to measles-infected human epithelial cells in significantly greater numbers than do lymphocytes from healthy volunteers or patients with other neurologic diseases. We have confirmed this observation in three separate studies, and have investigated the relationship of lymphocyte adherence to the clinical state. Lymphocyte adherence determination values correlated with the degree of certainty of the clinical diagnosis of MS, and lymphocyte adherence values in individual patients increased during clinical exacerbations. Judicious use of this test may facilitate the diagnosis of MS.

Epithelium↗
PubMedDate not supplied

Ex vivo evaluation of ferromagnetism, heating, and artifacts of breast tissue expanders exposed to a 1.5-T MR system.

Three breast tissue expanders were evaluated for compatibility with MR imaging (1.5 Tesla). The metallic components of the breast tissue expanders were shown to be nonferromagnetic, heating < or = .2 degrees C and the artifacts varied. These results indicate that MR procedures may be performed safely in patients with these implants; however, artifacts may obscure implant leaks or breast lesions if located near and metal portion of the breast tissue expanders.

Artifacts↗
PubMedDate not supplied

A multicenter clinical trial of Gadolite Oral Suspension as a contrast agent for MRI.

The purpose of this study was to assess the effectiveness and safety of Gadolite Oral Suspension as a gastrointestinal (GI) contrast agent for MRI in a phase II and two phase III multicenter clinical trials. Gadolite was administered to 306 patients with known or suspected abdominal and/or pelvic disease. MRI with T1- and T2-weighted sequences was performed before and after ingestion. Efficacy was evaluated by having two masked readers rate the certainty of their MR diagnosis (0 = uncertain, 1 = probable, 2 = definite) on randomly presented pre- and post-Gadolite Oral Suspension enhanced images. Principal investigators also evaluated the images and established the final diagnosis. Vital signs, clinical chemistries, and adverse events were documented. Blood and urine samples were analyzed for gadolinium content to determine whether Gadolite Oral Suspension was absorbed systemically. Certainty in MR diagnosis increased significantly (P < .001) for both blinded readers between pre- and post-Gadolite images (.49-1.18 for reader 1: .46-1.53 for reader 2). Sensitivity, specificity, and accuracy also increased for both masked readers. No gadolinium was detected in blood or urine samples. There were no serious adverse events and no apparent drug-related trends in mean vital signs or laboratory values. Gadolite is a highly effective, safe, and well tolerated contrast agent for clinical use with MRI.

Administration, Oral↗