The guinea pig as a model for predicting photoallergic contact dermatitis

This report describes modifications in the techniques used for both the induction and elicitation of photoallergic contact dermatitis (PACD) in the guinea pig. These changes have improved the reliability of this animal as the model of choice for screening chemicals or products for (heir tendency to produce PACD.
The induction period consists of 15 exposures of the test substance to shoulder skin that has been abraded with a nylon brush rotating at 13,000 rpm. One hour later, the KM site is irradiated with broadband UVA from a source having some irradiance below 320 nm (UVA/b). The animals receive 450 J/cm² of UVA during the three-week induction period. The elicitation (challenge) test is repeated fur two consecutive days. Each day, the test material, if a liquid, is applied to two sties even 30 lo 60 min for 6 h; then one of the sites receives 20 J/cm² of UVA.
These photo-induction and photo-elicitation procedures have demonstrated that low-level concentrations (0.25% range) of 6-melhyl coumarin or musk ambrette will both induce and elicit PACD in the guinea pig. This report adds more evidence that the induction of PACD in the guinea pig is dependent on broadband UVA.     

Leukocytes, Platelets, and Surface Microstructure of Spontaneously Degenerated Porcine Bioprosthetic Valves

The microstructure of 33 spontaneously degenerated porcine bioprosthetic valves was assessed by scanning electron microscopy in order to gather insight regarding the degenerative process. Twenty-four mitral and 9 aortic valves were removed from 32 patients. The duration of insertion was 7.7 +/- 2.4 years (mean +/- SD). All valves showed denudation of endothelial cells and exposure of the subendothelial fibrous tissue. Fibroblastlike cells were occasionally seen. Platelet deposits were observed on 22 of 33 valves (67%). Leukocytes were observed on the surface of 27 of 33 valves (82%). Mononuclear leukocytes were the most common category of cells (66%). Crystalline material was present on the surface of some leukocytes, suggesting that they may serve as a nidus for calcification. Transmission electron microscopy showed leukocytes in the process of phagocytizing collagen fibers. Macrophages, by exerting their scavenger function seem to contribute to destruction of the collagen framework of the valves. Whether the observed lymphocytes and plasma cells reflect an immunological involvement is unclear.     

Induction of delayed hypersensitivity to nitrogen mustard in the guinea-pig

The acquisition of allergic contact dermatitis limits the therapeutic usefulness of topical nitrogen mustard in man. A reproducible experimental model for this syndrome has been provided in the guinea-pig. Guinea-pigs were sensitized to nitrogen mustard (HN₂) by means of the repeated epicutaneous administration of sensitizer to a skin site, and the injection into that site of complete Freund's adjuvant. Application of dimethyl sulphoxide before HN₂ to the sensitization or challenge site facilitated the sensitization and challenge procedures. Positive challenge could be elicited by the intradermal injection of a non-toxic amount of HN₂. The methodology extends to the study of a variety of other sensitizers and potential sensitizers.     

In vitro production of erythropoietin by mouse fetal liver

Mouse fetal liver tissue has been cultured and shown to produce and release into the culture medium an erythropoietically active substance for up to 30 days of culture. Since this substance can be completely neutralized by an antiserum to erythropoietin and shows a dose-- response relationship in the plethoric mouse assay, it is suggested that the culture medium contains erythropoietin, a hormone important in the regulation of erythropoiesis. Using this procedure, we have obtained the equivalent of about 20.7 unites of erythropoietin from five T-flasks (75 sq cm) over the 30-day culture period.     

Intra-arterial Tissue Adhesives for Medical Splenectomy in Dogs

Transcatheter intra-arterial tissue adhesives are effective agents for producing medical splenectomy in dogs. Because of the rapid polymerization of the tissue adhesive, localized occlusion of the splenic artery mimicking a surgical ligation can be achieved leaving the intrasplenic vessels patent. Splenic infarction without evidence of infection was accomplished.     

Acute and Subchronic Toxicity of 2,4-Dichlorophenol in CD-1 Mice

Acute and Subchronic Toxicity of 2,4-Dichlorophenol in CD-IMice. BORZELLECA, J. F., HAYES, J. R., CONDIE, L. W., AND EGLE,J. L. JR. (1985) Fundam. Appl. Toxicol. 5, 478–486. Theacute oral LD50 of 2,4-dichlorophenol (2,4-DCP) employing cornoil as vehicle was determined to be 1352 mg/kg for female and1276 mg/kg for male CD-I mice. CD-I mice of both sexes wereexposed to 2,4-DCP in drinking water containing 10% Emulphorfor 90 days at concentrations of 0.2, 0.6, and 2.0 mg/ml providingtheoretical daily doses of 50, 150, and 500 mg/kg. These concentrationsresulted in mean daily doses of 50, 143, and 491 mg/kg for femalesand 40, 114, and 383 mg/kg for males. In both sexes, fluid consumptionwas lower in the vehicle control group (10% Emulphor) and inthe 2,4-DCP treated groups than in the naive controls (deionizedwater). There were no biologically significant differences inbody weight gain between females or males in the vehicle controland experimental groups. No differences were found in terminalorgan weights or organ weight ratios in either sex. Hematologicaldifferences were observed in males only and included an increasein leukocytes (high dose) and an increase in polymorphonuclears(low dose). Clinical chemistry parameters were altered in femalesonly and included a decrease in creatinine (low dose), an increasein BUN/creatinine ratio (mid dose), and an increase in ALP (highdose). In an assessment of the hepatic microsomal mixed functionoxidase system, no significant differences were found in thecomponents of the system, component activity, the kinetics ofethylmorphine N-demethylase, or the metabolism of testosterone.Administration of 2,4-DCP to CD-I mice of both sexes for 90days at mean doses of 40 to 491 mg/kg/day in drinking waterdid not elicit either consistent compound-related or dose-dependentsignificant toxicological effects     

Improved control of image optical density with low-dose digital and conventional radiography in bedside imaging

The technical and diagnostic performance of simultaneously acquired low-dose (44% of standard dose) storage-phosphor digital radiographs (system resolution = 0.2 mm, 10 bits) were compared with those of standard-dose conventional bedside radiographs of the chest in 32 patients. The mean optical density (OD) of the lungs (800 measurements) was closer to the ideal density with digital radiography (1.45 OD +/- 0.20 [standard deviation] vs 1.75 OD +/- 0.53) and was less often outside the usable range (2.5% vs 42.5%). Receiver operating characteristic analysis for detection of simulated nodules and monitoring devices (nine readers, 4,608 observations) showed that digital radiography was superior to conventional radiography (P less than .05) for four of the nine readers and equivalent to conventional radiography for five readers. The authors concluded that digital radiography produces more consistent and ideal image density and performs at least as well as conventional radiography under phantom test conditions.     

用四阶导数光谱法测定A-OT-Fu小鼠代谢物的血药浓度

本文采用四阶导数光谱测定了小鼠口服A-OT-Fu淀粉液后的主要代谢产物TFu和5-Fu的血药浓度—时间曲线。当TFu和5-Fu浓度为5～50μg/ml时,浓度与252nm和289 nm对零轴间的振幅有良好的线性关系。在本测试条件下TFu和5-Fu的回收率约95%以上,实验结果表明,TFu和5-Fu达到最高血药浓度的时间分别为1和2 h。