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Biomedical subjects

J W Osborne

Publications and source records attributed to J W Osborne.

At least 73 records · Page 4Linked to original sources
PubMed1983

The relationship between the compensatory response in the stomach and colon and the extent of small bowel resection in the rat.

The proximal and distal extent of the compensatory response in the gastrointestinal tract of the young adult rat to resection of 10-80 percent of the combined ileum and jejunum was investigated. Thirty days after intestinal resection and subsequent end-to-end anastomosis, rats were injected with tritiated thymidine and sacrificed one hour later. The incorporation of label into colonic crypts or stomach glands was used as an index of the compensatory proliferative response. Although no compensatory response was observed in stomach glands, a significant compensatory proliferative response was found in descending colon after resections involving removal of greater than 60% of the combined ileum and jejunum. These observations imply that the compensatory proliferative response to resection is caused, at least in part, by a humoral mechanism. However, this does not exclude a role for luminal factors, intestinal blood flow, and paracrine effector substances as secondary modifiers of the compensation. The observations that resection of the small bowel can have significant effects distally on cell proliferation in the colon may be important to the planning of combination therapies which involve bowel resection in both animal models and in man.

Adaptation, Physiological↗
PubMed1983

Mercury toxicity and dental amalgam.

There is adequate evidence that dental amalgam restorations, during and after placement, results in the release of Hg into the patient's body. Whether the Hg released from amalgam is due to placement procedures, surface abrasion, or later corrosion breakdown, there is evidence that a low level Hg release continues for years. It is generally agreed that if amalgam was introduced today as a restorative material, they would never pass F.D.A. approval. With new and more accurate techniques of measuring Hg levels, especially in tissue and blood, additional studies are necessary to relate blood-Hg levels with dental amalgam restorations. Studies must relate existing restorations as well as the placement of new restorations to body-Hg levels. It is possible that we have accepted a potentially dangerous material as being safe.

Dental Amalgam↗
PubMed1982

Scintigraphy and distribution of labeled antibodies in rats with tumors.

Radioiodinated antitumor (Ab-gamma globulins), non-tumor-specific Ab, and R131ISA were used for imaging radiation-induced intestinal tumors in rats. Each agent detected tumors larger than 2 g, but labeled Ab were most efficient in detecting small tumors. Tissue distribution studies showed that while 'purified' Ab localized specifically in tumors, 'unpurified' Ab concentrated in the tumor by a mechanism not considered immunological. Localization was variable and the concentration of antitumor Ab reached useful levels only in a small number of cases. The use of high specific activity purified Ab unexpectedly decreased the concentrations of label observed in the tumors when compared with the use of the same activity of low specific activity purified Ab. These results indicated the presence of circulating tumor antigens which were capable of binding the injected Ab. Subsequently, these findings have been substantiated. Thus the animal-to-animal variability could be explained on the basis of differing degrees of interaction of injected Ab with circulating tumor antigens. The usefulness of labeled purified or monospecific antitumor antibodies for tumor imaging and therapy would thus be influenced by the extent of such interactions.

Adenocarcinoma, Mucinous↗
PubMed1982

Isolation of rat intestinal crypt cells.

A technique is presented which yields single cells and intact crypts in suspension from unfixed rat intestinal mucosal epithelium. Everted lengths of intestine were digested by 27 mM sodium citrate in phosphate-buffered saline (pH = 7.3) at 37 degrees C. Mucosal cells were dislodged by vibratory stress (hand vortexing) following incubation for prescribed intervals at 37 degrees C in 1.5 mM ethylenediamine tetraacetic acid (EDTA) and 0.5 mM dithiothreitol (dtt). Alkaline phosphatase determinations, phase microscopy, and in vivo and in vitro evaluations of tritiated thymidine ([3H]TdR) incorporation were performed on isolated intestinal cells. Data indicate that cells were sequentially derived from villus tip to crypt base as judged by cellular morphology, alkaline phosphatase activity/mg protein and radioactivity per microgram protein. Upon completion of the intestinal cell isolation assay, scanning electron microscopy of the remaining intestine revealed that approximately 95% of the crypt openings were vacant; the villi were totally denuded; the supporting structures, including the lamina propria, appeared intact. In vitro radiolabelling of intestinal cell fractions enriched with crypts revealed a linear incorporation of [3H]TdR from 0-60 min which was strongly influenced by the presence of foetal calf serum (FCS). Measurements of the compensatory response of the mucosa to resection of 70% of the small bowel indicated that the mucosal cell separation is capable of detecting alterations in crypt cell proliferation. Previously, such alterations were monitored by other methods utilizing microdissection procedures or stathmokinetic agents.

Alkaline Phosphatase↗
PubMed1982

Fracture at the margins of amalgam as predicted by creep, zinc content, and gamma-2 content.

Fracture at the margins of amalgams as predicted by an equation suggested by Mahler using creep, zinc content, and gamma-2 content was tested on the three-year clinical results of 12 alloys. The results tend to agree with Mahler's results when gamma-2 and non-gamma-2 alloys are used in the same equation. This appears, however, to be an effect of combining two distinctly different types of alloys. It is suggested that, when non-gamma-2, low creep alloys are evaluated, the equation suggested by Mahler would be inappropriate. In addition, for non-gamma-2 alloys, the prediction using creep values does not appear to be appropriate.

Chemical Phenomena↗
PubMed1982

In vitro corrosion and in vivo marginal fracture of dental amalgams.

The relationship between in vitro corrosion and in vivo marginal fracture of dental amalgams has been studied. The potentiodynamic cyclic polarization technique has been used to determine the in vitro corrosion index. The marginal fracture data have been obtained from previous clinical studies reported by three independent research groups. A linear regression analysis has been employed to determine the degree of correlation between in vitro and in vivo data. Depending on the method of corrosion index measurement and the source of clinical data, correlation coefficients (r) ranging from 0.82 to 0.94 (p less than .01) have been obtained.

Corrosion↗
PubMed1982

Schistosoma mansoni: is acquired immunity induced by highly x-irradiated cercariae dependent on the size of the challenging dose?

A high degree of immunity, as shown by a 91% reduction of the number of worms recovered was found in five groups of mice that were immunized five times with highly X-irradiated cercariae and then challenged with 10, 20, 50, 100, or 500 normal Schistosoma mansoni cercariae. The results indicated that there were no significant differences in worm reduction in immunized mice challenged with different numbers of cercariae; consequently the immunity induced by this immunization method did not appear to be challenge-dose-dependent. However, the results also showed that when immunized mice were challenged with 500, 100, 50, 20, and 10 cercariae, 0, 13, 26, 56, and 68%, respectively, of the experimental animals were free of worms. Thus, the percentage of worm-negative cases increased as the number of challenge cercariae decreased. When viewed in this manner, the acquired immunity may be considered challenge-dose-dependent as well. If this method of vaccination is used for schistosomiasis control, we may anticipate that in both hypo- and hyperendemic areas, the intensity of infection and the severity of the disease will be reduced owing to a reduction in worms burdens, and in hypoendemic areas, there will be a number of worm-free cases.

Animals↗
PubMed1981

Failure at the margin of amalgams as affected by cavity width, tooth position, and alloy selection.

The effects of alloy, cavity width, and tooth position on failure rate at the margins of 429 two-year-old Class II amalgams were analyzed. Interpretation of the results from a factorial design indicated that: (1) There were significant differences among alloys; (2) conservative preparations exhibit less breakdown than wider preparations; and (3) there was less failure in lower premolars than in other posterior teeth.

Dental Alloys↗
PubMed1980

A three-year clinical assessment of a composite resin and its radiopaque counterpart.

Two composite resin materials, one containing a radiopaque filler, gave similar clinical results over the 3 year test period. There was a color shift toward a darker restoration, and a marginal stain occurred. Loss of marginal integrity was slight, and only three restorations showed wear or loss of material. There were no recurrent caries. It should be reemphasized that the major advantage of the radiopaque material is the capability of radiographic evaluation. Voids, caries, improper contours, and overhangs may be detected with this material.

Barium↗
PubMed1980

Two independent evaluations of ten amalgam alloys.

Two independent research groups evaluated marginal failure and conducted creep tests on 10 commercial amalgam alloys. Correlation data determined that both laboratory tests and clinical results were essentially the same between the two studies. The 2-year clinical results indicate that five alloys, Cupralloy, Dispersalloy, Indiloy, Phasealloy, and Tytin give best results. Creep correlated with the rate of marginal failure within a study when all alloys were assessed; however, for the seven gamma-2-free alloys, there was no significant relationship between in vivo and in vitro data. Since creep tests did not predict marginal failure of the gamma-2-free alloys, the results of clinical studies should be the guide to selection of the better amalgam alloys.

Copper↗