Biomedical subjects
Publications and source records attributed to J W Osborne.
Two composite resin materials were clinically evaluated after 12 years in vivo. Although the Class III restorations did not have the benefit of acid etching and bevels, all 32 restorations in the nine patients who were located were intact, and none needed to be replaced. Stain was the most prominent problem, both at the margins and on the surface of the restorations. Neither wear or marginal integrity appeared to be a problem.
The migratory pattern and attrition of 75Se-labelled S. mansoni challenge cercariae in CF1 mice immunized 0, 1, 3, or 5 times with 12kR- or 48kR-irradiated cercariae were investigated by compressed organ autoradiography. Mice were percutaneously inoculated with 500-1000 cercariae for each immunization and with a known count of approximately 90 cercariae at a different site for challenge. The skin, lungs, liver, other organs, and carcass were processed for autoradiography. Hepatic and mesenteric perfusions for worm collection were also sampled from day 19 through 34. In naive mice, 25% of challenge cercariae died in the skin. Skin attrition of challenge cercariae in mice immunized with 12kR-irradiated cercariae was 43% with 1 immunization, 54% with 3, and 58% with 5, whereas in mice immunized with 48kR-irradiated cercariae, skin attrition was 48% with 1, 63% with 3, and 76% with 5 immunizations. In all immunized mice, a high percentage of migrating schistosomula died in the skin within 24 hours of a challenge infection. Utilizing autoradiography, it was found that the silver foci created by single labelled worms were difficult to differentiate from those of paired worms. This study documents the induction of acquired resistance against a challenge infection in the skin by vaccination with highly irradiated cercariae, with the degree of attenuation of immunizing cercariae and the number of immunizations being closely related to the attrition rate in the skin. Finally, we discuss the contradictory views concerning the site of attrition of challenge cercariae.
The effect of dentinal bonding of composite resins was compared with that of enamel bonding. Two operators placed 192 composite resin restorations using enamel bonding or dentinal bonding on the two types of resin chosen for the study. Patients were recalled at the end of one year and two years. The restorations were evaluated clinically in the following categories: color match, cavo-surface discoloration, anatomical form, marginal adaptation, and recurrent caries. It was concluded for the evaluations that dentin bonding is not as effective as enamel bonding in protecting the composite restoration against cavo-surface discoloration and deterioration in marginal adaptation.
An experiment was performed to test the effectiveness of pentoxifylline in reducing late radiation injury. One hundred and four C3H mice were randomized into eight groups of 13 mice each, and the right hind limbs were irradiated with 4000, 5000, 6000, or 7000 cGy in ten fractions. Each group was treated with once daily injections of either pentoxifylline or saline for 30+ weeks. An additional ten mice received daily injections of pentoxifylline or saline, but no irradiation. The pentoxifylline animals demonstrated significantly less late injury than the saline treated animals. The most obvious differences were observed in the 5000 and 6000 cGy groups. There were seven radiation related deaths in the saline treated control groups, but only one radiation related death in the pentoxifylline treated groups. Whereas 42% (20/48) of the saline treated animals had a late injury score of 3.0 or greater, only 8% (4/51) of the pentoxifylline treated animals had a late skin score as high as 3.0. Pentoxifylline had no effect on the acute radiation injury scores. The drug was well tolerated with no toxic effects noted. Pentoxifylline is a methyl xanthine derivative that is used to treat vascular occlusive disease in humans. It improves perfusion through small capillaries by improving the deformability of red blood cells, inhibiting platelet aggregation, and stimulating the release of prostacyclin. This study shows that the prophylactic administration of pentoxifylline can modify late radiation induced injury in the mouse extremity. It may have value in the prevention or treatment of late radiation induced injury in humans, and it could be a useful tool to help define the mechanisms of late radiation injury in specific organs.
The widely held belief that 50% of the iron in human milk is absorbed is based on studies that have used an extrinsic radioactive iron tag. To determine the validity of an extrinsic tag, it is necessary to label the milk intrinsically with one isotope and to compare absorption of this isotope with absorption of another isotope added as the extrinsic tag. We chose the baboon as a model and infused 59Fe intravenously. In each of three attempts we failed to label the milk intrinsically.
The migratory pattern in naive mice of Schistosoma mansoni cercariae X-irradiated with OkR, 12kR, or 48rR has been investigated with compressed organ autoradiography. Three groups of 69 mice each were infected with 75Se-labelled cercariae. The skin at the site of infection, as well as the entire lungs and liver were removed from infected mice daily from 1-21d, on 24d, and on 28d; tissues were then processed for autoradiography. Autoradiographic analysis of migratory patterns showed that the schistosomula derived from nonattenuated cercariae passed quickly from the skin to the lungs and at a moderate rate from the lungs to the liver. Schistosomula derived from 12kR-irradiated cercariae were delayed in passing from the skin to the lungs and from the lungs to the liver, so that many remained in the lungs and died there, while only a few died in the skin or liver. Schistosomula derived from 48kR-irradiated cercariae remained mainly in the skin, rarely reached the lungs and were never found in the liver. This study indicates that immunization with 48kR-irradiated cercariae will cause no significant lesions in the lungs or liver.
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During intraoperative radiation therapy for carcinoma of the head of the pancreas in humans, a portion of duodenum is often at risk for radiation-induced complications because of its fixed anatomical position within the treatment field. This study was undertaken to determine the feasibility of using the rat as a model to determine the radiotolerance of normal mammalian duodenum. The procedures used to exteriorize and irradiate a selected segment of duodenum are described. Histopathologic changes in 5-cm segments of midduodenum were studied 14 and 28 days after 0, 30, 40, or 50 Gy X-radiation. Complete denudation of the epithelium and thickening of the muscularis and serosal layers occurred in all irradiated segments by day 14. By day 28, even though crypt and villus architectures were atypical, large areas of epithelial regeneration were seen in rats receiving 30 Gy. In contrast, complete denudation of the epithelium were still evident along most of the length of the irradiated segments in rats receiving 40 or 50 Gy. Serosal fibrosis was prominent in all irradiated animals, regardless of dose. These results indicate that radiation doses above 30 Gy carry high risks of complications. The rat is considered a suitable animal model.
The present study assessed the influence of shortening the overall treatment time (accelerated fractionation) on radiation injury of the small intestine. A rat model which allowed repeated irradiation of a localized segment of small intestine was developed. Young adult male Sprague-Dawley rats were orchiectomized, and a loop of the distal ileum was transposed to the left part of the scrotum. The intestinal segment was irradiated with a total dose of 56 Gy, given in 20 fractions, the total treatment time being either 26, 12, or 7 days (i.e. 1, 2, or 3 fractions per day). Radiation injury was assessed by histopathologic examination at 6 hr and at 2 weeks after the last irradiation. The surgical procedure was without complications. Shortening the overall treatment time by giving more than one radiation dose per day resulted in markedly increased injury both at 6 hr and at 2 weeks. It is concluded that accelerated fractionation results in increased radiation injury of the intestine when compared with standard fractionation. Because there may be a relationship between early and late effects in the intestine, our results also indicate that increased late radiation enteropathy may result from accelerated fractionation.
Since the original development by Bowen in the 60's, composite resins have evolved into a widely used and successful restorative material. Although they exhibit certain inadequacies as a dental restorative material, improvements constantly are being made. Due to the aesthetic nature of the material, coupled with its potential for mechanical and chemical bonding to tooth structure, composite resins will become more broadly used in the future.
Fourteen dental amalgam alloys were used in this study. After 1 year, amalgam restorations were evaluated for fracture at the margins. The clinical results indicated that Dispersalloy, Indiloy, a high-copper blend by Syntex, Cluster, and Unison had the least marginal failure. This was followed by Premalloy, Cupralloy, Tytin, Cupralloy ESP, and Contour. Velvalloy and Sybraloy and Orosphere II were the third major grouping with Summalloy having the most fracture at the margins. Different batches of the same alloy performed similarly. The correlation between creep and ridit means (fracture at the margins) was not found to be statistically significant.
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The aim of this investigation was to study crypt fission, a process which may be instrumental in regulating crypt number in the intestine. Young Holtzman rats were killed at various times after parturition and samples of the small intestine and colon were removed and processed. A microdissection technique was used to separate crypts from other structures. Crypts were scored as normal or fissioning. The percentage of crypts in fission (PCF) reached peak values of 25% and 52% in the small bowel and colon, respectively, at 21 days post-parturition. From this time onward, the PCF dropped until the adult value of approximately 7% was reached in each site. During this same period, the number of crypts increased from 1.9 X 10(6) to 3.3 X 10(6) in the small bowel and 2.2 X 10(5) to 6.5 X 10(5) in the colon. Thus an inverse relationship between the percentage of crypts in fission and crypt number was found. Distribution of fissure heights in fissioning crypts did not change as the animal aged. The majority of the fissures were found in the lower 1/4 of the fissioning crypts. This suggests that as soon as the fissure extends beyond the stem cell zone, division into two crypts soon occurs.
The growth parameters and radiosensitivity of normal rat intestinal epithelial cells, IEC-17, were studied. The cells were cultured by standard methods and exposed to an array of doses (1-12 Gy) of 250 kVp X rays. The survival curves generated exhibited no initial shoulder and were bimodal. The Do of the first component was about 0.2 Gy and the second component. 5.0 Gy. The ability of this cell line to repair sublethal lesions was examined by fractionation studies; repair was completed within 60 min after the first dose. When Chinese hamster ovary (CHO) cells were grown under the same conditions used for the IEC-17 cells and then irradiated with single doses, a typical survival curve with a Do of 1.4 Gy was obtained. The survival curves obtained for the IEC-17 cell line are consistent with the response of a morphologically distinct single population containing two functionally separate types of cells.
In order to determine if the rat colon is capable of adaptation when placed in another location within the intestinal tract and/or subject to different luminal contents, a 3 cm segment of transverse colon was transposed into the ileum. Sixteen days later, the animals were injected with tritiated thymidine (1 microCi/g body weight) and killed one hour later. Autoradiographs were analyzed for number of cells per crypt column, number of labeled cells per crypt column, position of labeled cells in the crypt column, and formation of Paneth cells or villi in the transposed colon. Proliferative activity of the epithelium was measured by isolating whole crypts and determining disintegrations per minute per crypt. Except for alterations in the positions of labeled cells, as determined by crypt profiles, no changes from normal were observed in any of the parameters measured. Hence, unlike the small bowel, the colon is refractory to the influences of a new environment.
Vaccination of Chinese bovines (cattle and buffaloes) against schistosomiasis japonica with 36 kR gamma-irradiated schistosomula was done for laboratory challenge and for field trials in China. Altogether, 61 bovines were used. All experimental animals were vaccinated 2-3 times with 10,000 irradiated schistosomula per time. For the laboratory challenge, all experimental and control cattle were challenged with 500 normal cercariae and each buffalo, with 2,000 cercariae. The laboratory-challenged bovines were killed after 54-57 days of challenge; the bovines for the field trial in the lightly endemic area, after 5 months in the field; and the bovines for the field trial in the heavily endemic area, after 58-63 days. When the animals were killed, the number of mature worms in the vaccinated (experimental) and non-vaccinated (control) animals was recorded and the percentage of worm reduction in each group was calculated. The first group, consisting of three vaccinated and three non-vaccinated cattle, was given a laboratory challenge; the worm reduction was 71.6%. The second group, consisting of two vaccinated and three non-vaccinated buffaloes, was also given a laboratory challenge; the worm reduction was 74.4%. The third group, consisting of seven vaccinated and eight non-vaccinated buffaloes, was utilized in a field trial in a lightly endemic area; the worm reduction was 75.6%. The fourth group, consisting of eight vaccinated and nine non-vaccinated cattle, and the fifth group, consisting of nine vaccinated and nine non-vaccinated buffaloes, were pastured in a heavily endemic area. The worm reduction was 65.1% in the fourth group and 75.7% in the fifth group.(ABSTRACT TRUNCATED AT 250 WORDS)
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