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91.
92.
The mechanism whereby cardiotoxic doses of isoproterenol (ISO) induces early permeability alteration of the sarcolemmal membrane is unknown; both beta-receptor overstimulation and direct toxic effect of ISO oxidation products have been implicated. There has been no morphologic observation, furthermore, on the structural basis of permeability alteration during this process. The purpose of the present study was to compare the morphology of cardiocyte injury induced by ISO and oxidized ISO (ISO-O2) and to visualize perturbation of the sarcolemma correlating with the leaky membrane. The authors studied the left ventricular myocardium of rats 10 and 60 minutes after subcutaneous administration of 85 mg/kg ISO and isolated perfused rat hearts exposed for 10 minutes either to ISO or ISO-O2 in a dose of 100 mg/l (10(-4) M) to determine the permeability of the sarcolemmal membrane using the extracellular diffusion tracer horseradish peroxidase (HRP) by light and thin section electron microscopy, the morphology of the sarcolemmal membrane by means of freeze-fracture electron microscopy, and the density of intramembrane particles (IMP) in the sarcolemmal membrane by planimetry using freeze-fracture electron microscopy. In in vivo rat hearts both 10 and 60 minutes after ISO and in vitro (isolated perfused) rat hearts exposed to either ISO or ISO-O2 for 10 minutes, HRP labeled the sarcoplasm of focally located cardiocytes implicating leakiness of the sarcolemmal membrane. HRP positive cardiocytes (with the exception of the in vivo 10 minute group) showed characteristic features of contraction band necrosis (both on light and thin-section electron microscopy) in all groups. Freeze-fracture electron microscopy of sarcolemmal protoplasmic (P) membrane faces revealed two populations of cardiocytes in all groups. P-membrane faces in one population of cardiocytes appeared as in the control. In the other population of cardiocytes, P-membrane faces showed irregular tears. Planimetry demonstrated a significant decrease of IMP numerical densities in P-membrane faces with tears in the in vivo 10 minute group and both with or without tears in the in vivo 60 minutes group and the in vitro groups compared with the control values. Furthermore, with the exception of the 10 minute in vivo group, IMP densities significantly decreased in sarcolemmal membranes with tears compared with those without tears in all experimental groups. These observations are consistent with the view that catecholamine induced myocardial injury is, at least partly, related to the direct toxic effect of catecholamine oxidation products on the sarcolemmal membrane.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
93.
Tumour angiogenesis: vascular growth and survival   总被引:3,自引:0,他引:3  
Angiogenesis starts at the edge of a malignant epithelial tumour concurrently with tumour cell invasion and stromatogenesis, i.e. the formation of specific connective tissue stroma amenable to easy penetration by endothelial and tumour cells. However, as the tumour continues its growth, the edge becomes the inner tumour area, and a new invading tumour front is formed by the multiplying malignant cells which outflank the initial edge. This process, which repeats itself again and again, forms the "relay race" model of tumour vascular growth and regression. At the heart of the tumour unfavourable environmental conditions prevail -- hypoxia, acidity, lack of nutrients, failure of waste removal, and apoptosis rather than proliferation. Blood vessels and tumour cells are greatly decreased, but do not vanish, as tumour cells are shifting to anaerobic glycolysis, and blood vessels are turning into anti-apoptotic pathways -- vascular survival ability (VSA). Thus, assessing vascular density (VD) by simply counting "hot spots" at the edge of a tumour, where conditions are most favourable, is futile; it may reflect tumour angiogenic activity (TAA), but is not representative of genuine tumour vasculature. By combining vessel counts at the invading tumour front with those of the inner tumour areas a complete picture of tumour VD can be achieved. The thus formed four patterns of vascularization, designated as "edvin" (edge vsinner tumour area), are: edvin 1: low TAA/low VSA; edvin 4: high TAA/high VSA; edvin 2: low TAA/high VSA; and edvin 3: high TAA/low VSA. It is expected that this scheme will prove useful in the field of chemoradiotherapy and anti-angiogenic treatment.  相似文献   
94.
95.
Oncostatin M: development of a pleiotropic cytokine   总被引:4,自引:0,他引:4  
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96.
Effects of the solvents on bond strength of resin bonded porcelain   总被引:1,自引:0,他引:1  
Clinical trials of porcelain veneers for chairside colour modifications may require the use of a trial resin with various colours of tints. The bond strength effects of four different solvents used for removal of trial resin from etched porcelain specimens were investigated. Fifty-six porcelain specimens were fabricated, flattened by a metallurgically standard method, etched with hydrofluoric acid and silane treated. The specimens were divided into four groups at random. The trial resin material was cleaned with different solvents prior to bonding of a dual cure resin composite button. After bonding the specimens were stored in water at 37 degrees C for 7 days. Shear bond strength results were as follows: acetone (control) group, 12.9+/-2.9 MPa; ethanol group, 15.1+/-4.6 MPa; methanol group, 11.5+/-2.9 MPa; methylene chloride group, 11.3+/-2.4 MPa. No significant differences were measured (ANOVA, P>0.05). The results indicated that the resin-porcelain bond strengths were not affected by the type of solvent used to remove trial resin. This procedure is recommended for clinical cases when resin composite is used for the try-in of etched porcelain bonded restorations.  相似文献   
97.
Younger patients (< or = 50 years of age) develop lung cancer. Many series report 5-10% of all cases occurring in younger patients. Outcome, inspite of treatment, is universally poor. Females and adenocarcinomas are over-represented and the aetiology for such an early-age presentation is unclear. The aims of this retrospective study were to review the clinical characteristics, treatment details and outcome of patients aged 50 years or younger diagnosed with lung cancer (small cell and non-small cell). Over a period of 34 months, 497 lung cancer patients were treated at the Liverpool Hospital Cancer Therapy Centre. Thirty-seven (7.4%) patients aged less than or equal to 50 years were identified. The median age at diagnosis was 44 years (range 32-49 years) in 20 females and 17 males. Adenocarcinoma was the predominant histological subtype (32%). No referred patient had stage I/II disease. Almost 90% of patients were smokers. Median survival following diagnosis was 12 months (range, 9 days-68 months) with 70% having died by the close of study. The clinical characteristics and outcome of young patients in our study were comparable to other similar series.  相似文献   
98.
BACKGROUND: Pelvic discontinuity is a distinct form of bone loss, occurring in association with total hip arthroplasty, in which the superior aspect of the pelvis is separated from the inferior aspect because of bone loss or a fracture through the acetabulum. The purpose of this study was to describe the population of patients who are at risk for this condition, to identify the characteristic radiographic features associated with it, and to report the results of revision total hip arthroplasty for the treatment of pelvic discontinuity. METHODS: The cases of all twenty-seven patients (thirty-one hips) who were identified as having a pelvic discontinuity at the time of a reoperation for a failed hip arthroplasty at one institution were reviewed retrospectively, and demographic information was collected. The preoperative radiographs and the operative notes were reviewed, and the postoperative results and complications were recorded. RESULTS: Pelvic discontinuity was identified in association with thirty-one (0.9 percent) of 3505 acetabular revisions. The mean age of the patients was sixty-one years (range, thirty-eight to eighty years). Twenty-eight hips were in women, and three were in men. Women (p < 0.001) and patients who had rheumatoid arthritis (p = 0.003) had a significantly increased risk of pelvic discontinuity. The radiographic findings included a visible fracture line through the anterior and posterior columns, medial translation of the inferior aspect of the hemipelvis relative to the superior aspect (seen as a break in Kohler's line), and rotation of the inferior aspect of the hemipelvis relative to the superior aspect (seen as asymmetry of the obturator rings) on a true anteroposterior radiograph. Two patients died within two years after the revision, and two had a resection arthroplasty for the treatment of the pelvic discontinuity; thus, twenty-seven hips were reconstructed and were eligible for follow-up at least two years after the operation. A number of different methods were used for reconstruction, but the results were best in patients who did not have severe segmental acetabular bone loss (type IVa [a satisfactory result in three of three hips]) and poorer in those who had severe segmental or combined segmental and cavitary bone loss (type IVb [a satisfactory result in ten of nineteen hips]) and in those who previously had been treated with irradiation to the pelvis (type IVc [a satisfactory result in three of five hips]). Nine of the twenty-seven hips needed another operation: four, because of aseptic loosening of the acetabular component; four, because of recurrent dislocation; and one, because of deep infection. Excluding three hips that were revised early because of infection or dislocation, a mechanically stable construct (that is, a stable socket and a possibly or definitely healed discontinuity) was obtained in seventeen of twenty-four hips. CONCLUSIONS: Pelvic discontinuity is uncommon, and treatment is associated with a high rate of complications. For hips with type-IVa bone loss and selected hips with type-IVb defects, in which a socket inserted without cement can be satisfactorily supported by native bone, we prefer to use a posterior column plate to stabilize the pelvis and a porous-coated socket inserted without cement. For most hips with type-IVb and type-IVc bone loss, we prefer to use particulate bone graft or a single structural bone graft protected with an antiprotrusion cage.  相似文献   
99.
Evidence suggests that a process analogous to long-term potentiation (LTP) may underlie the enhanced behavioural responses attending chronic administration of amphetamine and cocaine in animals (behavioural sensitization). Augmented excitatory amino acid (EAA)-mediated transmission at the level of midbrain dopamine neurons has been implicated as a change critical to the development of sensitization. Here we provide an initial demonstration that EAA synapses on dopamine neurons can undergo plasticity. Tetanic stimulation of the subthalamic nucleus induced a long-lasting increase (39.2 +/- 10.4%) in the amplitude of excitatory postsynaptic potentials recorded in dopamine neurons of the substantia nigra. This LTP, which did not occur in the presence of NMDA antagonists, may constitute the mechanism that lies at the heart of sensitization.  相似文献   
100.
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