Activation state of the cortex could be changed by reinforcement of low-amplitude visual evoked potentials in rabbits.

Visually evoked potentials (VEP) were recorded chronically from occipital cortex in awake rabbits. The VEP typically consisted of a triphasic response (positive deflection P60--negative deflection N205--positive deflection P450) that was followed by a late negative shift starting about 750 ms after the eliciting flash. After computation of a discriminating amplitude value (200 or 250 microV) the VEP were divided for comparison in high- and low-amplitude groups. Significant differences between these groups existed in amplitudes and latencies of the early VEP components. High-amplitude VEP were followed by larger late negative shifts and had significantly (P less than 0.01) earlier second positive deflections. In these high-amplitude cases, the EEG-baseline was more negative than in the low-amplitude VEP. In addition, we found a more synchronized background EEG in the low-amplitude VEP group. We conclude that different VEP amplitudes depended on different activation states of the cortex which could be changed by reinforcement.     

A comparative cytopathologic and histologic study of atypia, dysplasia, and adenocarcinoma in Barrett's esophagus.

As a potentially premalignant condition, Barrett's esophagus has stimulated controversy over the need for surveillance of glandular dysplasia and early carcinoma. This prompted the authors to review their experience with endoscopic cytologic brushings and biopsies from patients with Barrett's esophagus. The authors reviewed 65 consecutive specimens from 42 patients with Barrett's esophagus in which both the concurrently obtained esophageal cytologic brushings and companion biopsy specimens were available. In addition, esophagogastrectomy specimens from 9 nine these patients were reviewed. Cytologic and histologic specimens were assigned to one of four diagnostic categories, based on specifically defined criteria: simple Barrett's esophagus with or without inflammatory atypia; dysplasia; adenocarcinoma; or suspicious for dysplasia or carcinoma. Simple Barrett's esophagus was diagnosed in 38 cytologic brushings and 44 biopsy specimens, dysplasia in 4 brushings and 7 biopsy specimens, and carcinoma in 14 brushings and 10 biopsy specimens. Nine brushings and three biopsy specimens were suspicious. In 13 cases, brushings revealed a higher grade lesion than did histology; in 5 cases, biopsy specimens showed a higher grade lesion. Agreement between the two occurred in 72% (47/65) of all specimens. Accuracy was confirmed in the histologic examinations of the resection specimens. The authors conclude that specific criteria, when consistently applied, allow accurate cytologic diagnoses of epithelial changes in Barrett's esophagus. The use of esophageal brush cytology and biopsy specimens provides two complementary techniques, which detect a greater number of serious lesions than either technique alone.     

配送中心:快速扩张的后盾

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Mycophenolate mofetil significantly reduces leukocyte graft infiltration after heterotopic cardiac transplantation in a rat model: comparative study with cyclosporine and FK 506.

BACKGROUND: The purpose of the study was to evaluate the effects of cyclosporine (CsA), FK 506 and mycophenolate mofetil (MMF) on graft-infiltrating leukocytes (CD4, CD8, CD11a, CD18) after cardiac transplantation in rats. METHODS: Three hundred forty animals were transplanted and randomly divided into 4 groups: CsA, 3 mg/kg/d (n = 74); MMF, 40 mg/kg/d (n = 96); FK 506, 0.3 mg/kg/d (n = 96); and a control group receiving no immunosuppressive therapy (n = 74). Three or 4 animals from each group were killed at intervals of 1 to 4 days up to Day 60. Immunohistochemistry was performed using monoclonal antibodies (MAb) against CD4, CD8, CD11a and CD18. Positively stained cells were analyzed in the perivascular space (PVS) of intra- and epicardial arteries. Statistical analysis was performed using area-under-the-curve assessment with an extended t-test. RESULTS: CsA and FK 506 reduced the presence graft-infiltrating leukocytes (CD4, CD8, CD11a, CD18) in the PVS of intra- and epicardial arteries when compared with control animals. MMF therapy resulted in a further significant reduction in infiltrating leukocytes when compared with the 2 calcineurin inhibitors. MMF had a faster onset of action than the calcineurin inhibitors. CsA and FK 506 required 12 to 20 additional days to achieve the reducing effect of graft infiltration seen in MMF-treated animals. CONCLUSION: MMF possesses potent infiltration-blocking properties and its application leads to a greater reduction of cellular infiltration in the course of transplant rejection when compared with calcineurin inhibitors.     

Metabolism of a glucuronide conjugate of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone in rats

 Besides 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), [4-(methylnitrosamino)-1-(3-pyridyl)but-1-yl]-β-O-d-glucosiduronic acid (NNAL-Glu) is another important metabolite of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) which has been detected in the urine of tobacco users and non-smokers heavily exposed to sidestream cigarette smoke. In order to evaluate the toxicological significance of NNAL-Glu formation and excretion, the metabolism of [5-³H]-NNAL-Glu was studied in rats. Five male F344 rats were administered 3.7 mg/kg [5-³H]-NNAL-Glu by i.v. injection and the metabolites in urine analysed by HPLC. More than 90% of the radioactivity was excreted in urine within the first 24 h. Unchanged NNAL-Glu accounted for 81.2±3.1% of the total radioactivity; the remaining part of the dose appears to be deconjugated resulting in the urinary excretion of NNAL (3.6±1.7%) and its α-hydroxylation (11.5±2.2%) and N-oxidation (3.6±1.6%) products. The presence of α-hydroxylation products of NNAL-Glu in urine suggests that this NNK metabolite may be activated in vivo to carcinogenic intermediates. Received: 25 April 1994 / Accepted: 29 June 1994     

Application of a CCD linear array camera in the quantification of tissue staining: NBT detection in ischaemic myocardium.

A method was developed to quantify the intensity of tissue staining using a CCD (charge-coupled device) camera. Reflection spectra of NBT-stained (nitro-blue tetrazolium-stained) and unstained myocardium were recorded via fibre optics coupled to a CCD camera, connected to a microcomputer. The calculation of the intensity of staining was based on evaluation of the NBT-related changes of the reflectance spectrum. In each of six anaesthetized sheep, global ischaemia was induced by cross-clamping of the aorta. The hearts were removed and incubated at 35 degrees C. At predetermined times two sections of ventricular myocardium were taken, one of which was then stained with NBT, the other being left unstained. Evaluation of the reflectance spectra from stained sections during the first phase of ischaemia showed a slight loss of NBT colour intensity followed by a more rapid loss of staining until the values of the unstained sections were reached. In contrast to the conventional visual evaluation, the method provides quantitative data on the intensity of staining, and allows use of the NBT technique for statistical evaluation of what happens over time, and the regional distribution of ischaemic injury of tissue. This method may also be applied to other staining techniques.