Biomedical subjects

R Sneed

Publications and source records attributed to R Sneed.

5 recordsLinked to original sources

PubMed1995

In vivo cancer diagnosis of the esophagus using differential normalized fluorescence (DNF) indices.

BACKGROUND AND OBJECTIVE: We report the use of new diagnostic parameters based on the differential normalized fluorescence (DNF) signals for malignant tumor diagnosis. STUDY DESIGN/MATERIALS AND METHODS: Over 200 measurements of endogenous fluorescence from normal and malignant esophageal tissues were performed during routine endoscopy in 48 patients. A pulsed nitrogen-pumped dye laser was used to provide in situ excitation at 410 nm. Direct collection of the fluorescence signal emitted by the tissue was achieved using an intensified photodiode array detector equipped with a fiberoptic probe. RESULTS: The fluorescence signals were normalized with respect to the total fluorescence signal area. The cancer diagnosis indices were defined by the difference between the normalized fluorescence signal of a tumor and the mean value of a reference set of normal tissues. The results of the DNF approach were compared with endoscopic examinations and histopathology interpretations of the biopsy samples. Excellent correlation in the classification of normal and malignant tumors for the samples was found. CONCLUSION: The data indicated that the DNF approach has a significant potential to provide a direct, real-time, and in-situ technique for cancer diagnosis of the esophagus without requiring biopsy of the tumors and time-consuming histopathology tests.

Adenocarcinoma↗

PubMed1993

Natural killer cells induce activated murine B cells to secrete Ig.

We previously demonstrated that dextran-conjugated anti-IgD antibodies (alpha delta-dex) induce proliferation of small, B cell-enriched murine spleen cells (Be cells), and in the presence of IL-2, stimulate Ig secretion in vitro. We have shown that alpha delta-dex-stimulated B cells provide an in vitro model for studying B cell activation by T cell-independent type 2 (TI-2) Ag, as exemplified by the bacterial polysaccharides. We now show that highly purified resting B cells, obtained by electronic cell sorting (Bsp cells), fail to secrete Ig in the presence of alpha delta-dex + IL-2. The alpha delta-dex + IL-2-induced Ig secretory response of Bsp cells is restored upon addition of splenic non-B, non-T cells or a pure population of in vitro-generated NK cells. Similarly, pretreatment of Be cells with anti-AsGm-1 plus complement inhibits Ig secretion in response to alpha delta-dex + IL-2. An IL-2-induced NK cell supernatant (NKSN) is equally potent at stimulating Ig secretion by alpha delta-dex-activated Bsp cells, indicating that cell contact between Bsp and activated NK cells is not required for this effect. IL-2 stimulates not only NK cells, but B cells as well, since addition of anti-IL-2 + anti-IL-2R antibodies to Bsp cell cultures, in the presence of alpha delta-dex + NKSN, inhibits Ig secretion. These data describe a novel animal model for NK cell-induced B cell maturation to Ig secretion and suggest a pathway for Ig production in response to T1-2 Ag.

Animals↗

PubMed1993

Comparative in vitro analysis of proliferation, Ig secretion, and Ig class switching by murine marginal zone and follicular B cells.

We have previously demonstrated that activation of murine B cells by dextran-conjugated anti-IgD antibodies may serve as a polyclonal, in vitro model system for studying immune responses to T cell-independent type 2 (TI-2) Ag, as exemplified by the bacterial polysaccharides. Because in vivo Ig responses to TI-2 Ag are mediated primarily by B cells resident in the splenic marginal zone, we wished to determine whether this reflected an intrinsic difference in the responsiveness of marginal zone B cells (MZB) compared with follicular B cells (FB) to this class of Ag. In this report we demonstrate that highly purified MZB, isolated by electronic cell sorting, exhibit a lower proliferative response in vitro in response to unconjugated anti-Ig antibody as well as to dextran- or Sepharose-conjugated anti-IgM or anti-IgD antibodies, whereas they proliferate equal to or better than FB when stimulated by other B cell mitogens including LPS, Salmonella typhimurium mitogen, or anti-CD3-activated CD4+ Th2 cell clone. Despite the different proliferative responses of MZB and FB induced by anti-Ig, Ag receptor cross-linkage stimulates comparable increases in intracellular free calcium concentrations in both of these B cell populations. Furthermore, MZB secrete Ig and undergo Ig isotype switching to a comparable degree, relative to FB, in response to both T cell-dependent and T cell-independent stimuli. This suggests that the compartmentalization of TI-2 responses to the splenic marginal zone rather than the follicular zone reflects something other than the intrinsic responsiveness of the B cells from these two sites.

Animals↗

PubMed1983

Gastric antisecretory 9H-xanthen-9-amines.

A series of 9H-xanthen-9-amines possessing a wide variety of nitrogen substituents at C-9 was prepared for evaluation of gastric antisecretory activity. These substituents included the acetamidine, imidate, pyrimidine, thiazoline, quinuclidine, 2-hydrazinopyridine, aminopiperidine, aminoalkylimidazole, and aminoalkylpyridine moieties. The majority of compounds in this series inhibited gastric acid secretion when tested orally in the pylorus-ligated rat. Potency was increased by intraduodenal administration and diminished by incubation with gastric juice, suggesting partial degradation of the compounds in the gastric environment. A representative example, 3-(9H-xanthen-9-ylamino)-1-ethylpiperidine, exhibited similar activity in dogs, although no free compound could be detected in the blood. It is therefore hypothesized that this compound is either rapidly bound to tissue and/or metabolized to an active species.

Animals↗

PubMedDate not supplied

The Alabama automated defibrillation pilot program.

The Alabama Chapter of the American College of Emergency Physicians is now sponsoring a pilot program using EMT-Basic equipped with semi-automatic ("smart") defibrillators for the treatment of cardiac arrest patients in the field. This article outlines the rationale for the program along with present status of results.

Alabama↗