皮肤光老化皱纹形成机制及维A酸类药物的拮抗作用

日光中长波紫外线 (UVA)长期反复照射是户外工作者暴露部位皮肤光老化及相关皮肤肿瘤多发的重要因素 ,皱纹形成是皮肤光老化的最重要特征 ,研究其作用机制对紫外线辐射损伤的防护有重要意义。基质金属蛋白酶 (matrixmetal loproteinases,MMPs)家族在各种生理、病理条件下细胞外基质降解和重塑中起着关键作用。我们研究了皮肤光老化皱纹形成与真皮成纤维细胞MMPs及MMPs组织抑制剂 (tissueinhibitorofmatrixmetallo proteinases,TIMPs)表达的关系 ,并同时观察了维A酸类药物的拮抗作用。一、材料与方法1 真皮成纤维细胞培养 :标本为健康…     

Perforated colorectal neoplasms: correlation of clinical, contrast enema, and CT examinations

Results of clinical, contrast enema (CE), and computed tomographic (CT) examinations in 39 patients with perforated colorectal neoplasms were retrospectively reviewed. Twenty patients were toxemic at initial presentation, but in only four patients was the diagnosis of perforated colorectal neoplasm initially suspected clinically. CE study was performed in 22 patients and enabled the diagnosis of perforated neoplasm in 11 cases, neoplasm alone in eight, and neither neoplasm nor perforation in three. CT was performed in 38 patients and enabled the diagnosis of perforated neoplasm in 36; pericolic phlegmon but no mass lesion was evident in two. In 16 patients, CT also demonstrated metastatic disease. Because of its reliability in establishing the diagnosis and staging the extent of the inflammatory and neoplastic disease, CT is indicated in cases of suspected or proved perforated colorectal neoplasm and in cases in which CE study findings are indeterminate or suggestive of perforated neoplasm.     

Atropine effects on delayed discrimination performance of rats

The effects of atropine sulfate (ATS) and atropine methyl nitrate (ATM) on the conditional discrimination behavior of rats were investigated in eight-hour experimental sessions. Responding of rats was reinforced on either a lighted or a darkened lever depending on whether lights over both levers had been on during the preceding sample portion of the trial. Zero-delay and four-second-delay trials were randomly interspersed. Quality of performance was analyzed using the A' sensitivity measure of signal detection theory. Both drugs reduced both sensitivity and the percentage of trials on which responding occurred (percent response) below saline treatment levels. The two drugs did not reliably differ from each other in their effects on sensitivity during the zero-delay condition, but reliable differences between the two drugs emerged during the four-second-delay condition at doses above 0.8 mg/kg. Percent response recovered more rapidly for animals treated with ATS than responding occurred (percent response) below saline treatment levels. The two drugs did not reliably differ from each other in their effects on sensitivity during the zero-delay condition, but reliable differences between the two drugs emerged during the four-second-delay condition at doses above 0.8 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of chronic stress on plasma corticosterone, ACTH and prolactin

Rats were placed in a stressful environment for 24 hr per day and levels of plasma hormones were measured after varying numbers of days in the environment. Rats were habituated to operant chambers placed in sound-attenuated enclosures. Food pellets were available by lever press on a FR1 schedule. After 3 days of habituation, rats in the “stressed” group were trained to pull a ceiling chain to avoid or escape shock. Following training, stress trials, consisting of a consecutive sequence of 5 sec each of a warning light, warning tone and 0.16, 0.32, 0.65, 1.3 and 2.6 mA of footshock, occurred approximately once per 5 min around-the-clock. For the first day, the sequence was terminated when the ceiling chain was pulled. On subsequent days, 90% of all shock presentations could be avoided or escaped by chain pull; the remaining 10% of trials were inescapable and the entire sequence was presented. Control rats lived in identical chambers without presentation of shock. Rats were sacrificed after 1, 2, 3, 4, 7 or 14 days in this environment and levels of plasma corticosterone, ACTH and prolactin were determined. Levels of plasma corticosterone were elevated during the first 7 days in the stressful environment, but returned to control values by day 14. Levels of plasma ACTH and prolactin were similar in stressed and control rats at all time points measured. These data suggest that stress-induced changes in glucocorticoids but not in ACTH or prolactin might mediate some of the physiological changes that occur as the result of chronic stress.     

Evidence for microvascular thrombosis obtained by intravital fluorescence videomicroscopy

A pattern of enlarged capillaries densely packed with red cells and not filled by the intravital dye Na-fluorescein for 10-20 min is described. Probably it corresponds to microvascular thrombosis. Alternative explanations like prolonged stasis appear unlikely. Up to now the pattern has been detected in severe chronic venous incompetence, collagen vascular disease and essential thrombocytosis.     

Short-Ti inversion-recovery pulse sequence: analysis and initial experience in cancer imaging

Inversion recovery (IR), commonly considered a pulse sequence capable of producing T1-weighted images with excellent display of normal anatomy, is versatile: The null point and peak time provide a useful, succinct summary of the properties of IR and its capacity for producing both T1- and T2-weighted images. Shortening of the inversion time (TI) and creation of a short-TI inversion-recovery (STIR) pulse sequence increases sensitivity to malignancy and other abnormalities by making the effects of prolonged T1 and T2 on signal intensity additive and by nulling the signal from fat. The authors examined over 300 patients with various malignancies and compared STIR images with T1- and T2-weighted images obtained at 0.5 T. In 43 cases, signal-difference-to-noise ratios (SD/Ns) were calculated between tumor, fat, and muscle. In general, STIR images demonstrated tumor as a conspicuously high-intensity area in a background of muted, discernible anatomic detail. The good contrast achieved with STIR sequences between tumor and fat (SD/N = 18.1) and tumor and muscle (SD/N = 12.9) consolidated into a single image the information contained separately on T1- and T2-weighted images, which facilitates efficient detection and localization of malignancy.     

Ultrastructural morphology of early cellular changes in the synovium of primary synovial chondromatosis.

Synovial tissues taken from 13 cases of synovial chondromatosis (SC) were examined by light and electron microscopy. In three of the 13 cases, early cellular changes were observed by electron microscopy. Most of the foci were independently situated within an accumulation of fine, homogenous chondroid matrix in the sublining area of the synovium. Basal laminalike material was observed in these cells. Because this material was not apparent in the mature cartilage cells, the authors postulate that the basilaminar material affects cellular cytodifferentiation in SC during the initial phase of the disease. Ultrastructurally, these cells are morphologically similar to myofibroblasts. However, proliferation of paravascular cells with distinct basal laminae and activated secretory abilities was observed around some of the vessels. These paravascular cells may be the precursor cells of the prechondroblastic cells with basal laminalike material seen in SC.     

Formation of a tablet: a site and bond percolation phenomenon.

The concepts of percolation theory are used to elucidate the formation of a tablet by compression of particulate matter. The process of compaction can be considered as a combination of site and bond percolation phenomena. Because of effects of different particle size and shape of the particles in a powder bed and effects of brittle fracture and plastic flow, moisture content of the powder, and finite size of the tablet, no sharp percolation thresholds are expected. Thus, it is interesting to test the validity of the fundamental equation of percolation theory: the power law X = S(p - pc)q, where X is the system property, S is the scaling factor, p is the site occupation or bond formation probability, and q is the critical exponent. This model is, in certain cases, only rigorously valid close to the percolation threshold (range, [+/- 0.1 pc]). Combination of the Heckel equation with an equation derived earlier for the properties (X) of tensile strength (sigma t) and deformation hardness (P) yields a power law with q = 1, S'(sigma t) = sigma tmax/(1 - pc), and S(P) = Pmax/(1 - pc). With respect to the simplifying assumptions made, the power law agrees well with the experimental results obtained. Substantial improvements in the interpretation of the compression-compaction process are possible with these findings, and some interpretations differ from previous ones in earlier publications.