Laminar xanthine oxidase, superoxide dismutase and catalase activities in the prodromal stage of black-walnut induced equine laminitis.

UNLABELLED: REASONS FOR STUDY: Xanthine oxidase (XO)-dependent production of superoxide anion and hydrogen peroxide, a characteristic of ischaemia-reperfusion injury, may contribute to the development of equine laminitis. OBJECTIVE: To determine the levels of XO and antioxidant enzymes (catalase, superoxide dismutase [SOD]) in the digital laminae of normal horses (CON) and horses in the developmental stage of laminitis using the black walnut extract (BWE) model. METHODS: Healthy horses (n = 12) were administered BWE (BWE group, n = 6), or water (CON group, n = 6) through a nasogastric tube. At the onset of leucopenia in the BWE-treated animals, all horses were anaesthetised, digital laminae and other samples collected rapidly and flash frozen, and the animals subjected to euthanasia. Extracts of the frozen tissues were assayed for the 2 conformational forms of xanthine: oxygen oxidoreductase (XOR), namely, xanthine dehydrogenase (XDH) and xanthine oxidase (XO), as well as the antioxidant enzymes, SOD and catalase. RESULTS: Extracts of liver, lungs and skin, but not digital laminae, from either CON or BWE-treated horses had endogenous SOD, whereas all had endogenous XO and catalase. The levels of XDH, XO and catalase were similar in extracts of laminae from CON and BWE-treated horses as was the ratio of XDH to XO in extracts. CONCLUSIONS AND POTENTIAL RELEVANCE: The absence of increased XO activity suggest against the involvement of this reactive oxygen intermediate-generating system in the development of laminar pathology in BWE-treated horses. Conversely, the absence of SOD from extracts of equine digital laminae, but not other tissues, suggests that the equine digital laminae are highly susceptible to damage by superoxide anion, produced, for example, by emigrant inflammatory leucocytes.

Rapid acquisition of multicellular drug resistance after a single exposure of mammary tumor cells to antitumor alkylating agents.

BACKGROUND: Clinical drug resistance is either intrinsic (de novo) or often acquired rapidly in conjunction with chemotherapy. By contrast, the selection of drug-resistant mutant cell lines in monolayer culture systems is usually a more protracted process. Sublines of mouse EMT-6 mammary tumor cells selected for resistance to various alkylating agents in vivo after serial passage into syngeneic mice manifest their resistance in vitro only when cultured as three-dimensional multicellular aggregates or spheroids. PURPOSE: We examined whether a single exposure of mouse EMT-6 or human MDA-MB-231 breast cancer cells to alkylating agents in vitro is sufficient for the induction of a resistance phenotype, which may be detected by re-applying the drugs to cells grown as three-dimensional aggregates. METHODS: Mouse EMT-6 and human MDA-MB-231 breast cancer cells cultured as three-dimensional aggregates were exposed to a single dose of alkylating agent for 1-5 days. Aggregates were dispersed, and cells were plated as monolayer cultures for up to 8 weeks to allow for recovery. Colony-forming ability was assessed after a subsequent alkylating-agent exposure of cells cultured as monolayers or three-dimensional aggregates. RESULTS: A single in vitro exposure to 12.5-microM cisplatin (CDDP) for 5 days or 25 microM 4-hydroperoxycyclophosphamide (4-O2H CTX) for 1 or 3 days without changing the medium was sufficient to induce transient but substantial resistance in EMT-6 cells as determined by clonogenic assays. Such resistance was not detected when monolayer cell cultures were used. The concentration of 4-O2H-CTX and the length of time the cells remained in three-dimensional culture after initial exposure to this drug was associated with the degree of subsequent drug resistance of cells grown as three-dimensional cultures. Furthermore, this acquired resistance after a single drug exposure was accompanied by changes in the three-dimensional architecture of the cell aggregates, which now formed much more compact multicellular spheroids. Similarly, a single exposure to 4-O2H-CTX was enough to bring about resistance in MDA-MB-231 cells detectable only in three-dimensional cultures, as well as the change in three-dimensional architecture. CONCLUSIONS: Rapid acquisition of resistance likely represents a physiologic mechanism of adaptation operative at the multicellular level rather than a stable genetic change and may be one of the reasons for the rapid development of drug resistance acquired by tumors in vivo. IMPLICATIONS: In vivo drug exposure may result in transient and low levels of drug resistance that may nevertheless be clinically relevant.

Comparing Preliminary and Final Neuroradiology Reports: What Factors Determine the Differences?

BACKGROUND AND PURPOSE: Trainees' interpretations of neuroradiologic studies are finalized by faculty neuroradiologists. We aimed to identify the factors that determine the degree to which the preliminary reports are modified. MATERIALS AND METHODS: The character length of the preliminary and final reports and the percentage character change between the 2 reports were determined for neuroradiology reports composed during November 2012 to October 2013. Examination time, critical finding flag, missed critical finding flag, trainee level, faculty experience, imaging technique, and native-versus-non-native speaker status of the reader were collected. Multivariable linear regression models were used to evaluate the association between mean percentage character change and the various factors. RESULTS: Of 34,661 reports, 2322 (6.7%) were read by radiology residents year 1; 4429 (12.8%), by radiology residents year 2; 3663 (10.6%), by radiology residents year 3; 2249 (6.5%), by radiology residents year 4; and 21,998 (63.5%), by fellows. The overall mean percentage character change was 14.8% (range, 0%-701.8%; median, 6.6%). Mean percentage character change increased for a missed critical finding (+41.6%, P < .0001), critical finding flag (+1.8%, P < .001), MR imaging studies (+3.6%, P < .001), and non-native trainees (+4.2%, P = .018). Compared with radiology residents year 1, radiology residents year 2 (-5.4%, P = .002), radiology residents year 3 (-5.9%, P = .002), radiology residents year 4 (-8.2%, P < .001), and fellows (-8.7%; P < .001) had a decreased mean percentage character change. Senior faculty had a lower mean percentage character change (-6.88%, P < .001). Examination time and non-native faculty did not affect mean percentage character change. CONCLUSIONS: A missed critical finding, critical finding flag, MR imaging technique, trainee level, faculty experience level, and non-native-trainee status are associated with a higher degree of modification of a preliminary report. Understanding the factors that influence the extent of report revisions could improve the quality of report generation and trainee education.

The influence of exercise-induced oxidative stress on binding and degradation of 125I-insulin by the receptors on erythrocytes.

In the present work we investigated the influence of oxidative stress induced by strenuous exercise on the affinity of a specific insulin receptors on human erythrocytes. 13 male members of the national basketball staff performed a maximal treadmill exercise test. In the blood samples collected before and directly after the test acid-base equilibrium parameters, lactic acid concentrations, glucose and insulin serum levels as well as 125I-insulin binding and degradation by receptor on erythrocytes were measured. As markers of oxidative stress, plasma thiobarbituric acid-reactive substance levels (TBARS) and red blood cells glutathione content (GSH) were determined. After the exercise test TBARS levels increased significantly and GSH concentrations decreased indicating that oxidative stress occurred. Binding of 125I-insulin to the receptors on erythrocytes decreased significantly during the test, while there was only insignificant reduction in 125I-insulin degradation. Correlation analysis and multiple linear regression revealed that changes in insulin degradation by receptors on erythrocytes during exhaustive exercise are determined by oxidative stress, probably via oxidation of sulfhydryl groups of certain enzymes. The affinity of receptors for insulin seems to depend mainly on glucose concentrations.

(N-Barbituryl)phenyl- and cyclohexylalkanoic acids and some of their derivatives as potential anti-inflammatory agents.

A series of p-(N-barbituryl)phenyl- and cyclohexylalkanoic acids and their esters were synthesized. The preliminary pharmacological screening using the carrageenin, xylene and cotton tests revealed strong anti-inflammatory activity of several compounds in some of the tests performed, compound (Ij) being active in all the tests.

New hexahydro[1,4]diazepine-7H-5,7-diones with potential neurotropic activity.

Fourteen new derivatives of hexahydro[1,4]diazepine-7H-5,7-dione were synthesized and tested for neurotropic activity. Some of them showed strong analgesic activity in the hot plate test.

Extent of vascularization as a prognostic indicator in thin (< 0.76 mm) malignant melanomas.

Angiogenesis in malignant melanoma (MM) was evaluated by comparing mean vessel number (MVN) in Spitz's nevi (SN), thick and thin MMs that metastasized, and thick and thin MMs with > or = 10-year survival. Vessels were identified with antibodies against factor VIII-related antigen (FVIII) and CD34 in 37 MMs (17 < or = 1.9 mm and 20 > or = 4.0 mm) with > or = 10-year follow-up and 10 SN from children (< or = 9 years old). Fields (x250) with the highest vessel density were counted by independent observers blinded to clinical outcome. There were no differences in MVN between SN versus MMs (P = 1.0), but the distribution of vessels was much more uniform in SN. Seven MM pairs (> or = 5.5 mm) and five pairs (< or = 0.75 mm) were matched by sex, age, site, stage, and primary treatment (paired t-test). In the pairs > or = 5.5 mm, there was no correlation with MVN with either metastasis or death (FVIII P = 0.98; CD34 P = 0.85). Among the thin paired lesions, high MVN (FVIII = 46, CD34 = 39) was significantly related not only to metastasis (FVIII P = 0.04, CD34 P = 0.03) but also to death (FVIII P = 0.04, CD34 P = 0.05). MVN does not separate SN versus MM nor predict outcome in thick (> or = 4.0 mm) MMs; however, high MVN (> or = 42 average) is predictive of metastasis and death in MMs < or = 0.75 mm. Larger matched studies are indicated to confirm this observation.

N-substituted urethanes as potential antiinflammatory agents.

Sixteen N-substituted urethanes were investigated as potential antiinflammatory agents. Most of them showed no stronger activity than phenylbutazone. The most active in the xylene hyperemia test were N,N'-dicarbethoxy-N,N'-dicyclohexyl-1,3-diaminopropane (XVI) and cyclohexyl piperidine-1-carboxylate (XIII). None of the studied compounds showed analgesic activity.