Ischemia-reperfusion (I/R)-induced microvascular injury is characterized by capillary "no-reflow" and reflow-associated events, termed "reflow paradox," including leukocyte-endothelium interaction and increase in microvascular permeability. The major objectives of this study were 1) to elucidate the significance of reflow paradox after 4 h of tourniquet-induced ischemia in striated muscle and 2) to determine the role of reactive oxygen metabolites in the pathogenesis of reflow paradox-dependent microcirculatory alterations. By use of in vivo fluorescence microscopy in a striated muscle preparation of hamsters, leukocyte-endothelium interaction in postcapillary venules and macromolecular extravasation from capillaries and venules were quantified before ischemia and after 30 min, 2 h, and 24 h of reperfusion. I/R elicited marked enhancement (P < 0.01) of leukocyte rolling during initial reperfusion and a 20-fold increase of leukocyte adherence (P < 0.01) lasting for the entire postischemic reperfusion period (n = 7). These phenomena were accompanied by significant leakage (P < 0.01) of macromolecules from capillaries and in particular from postcapillary venules (n = 9). Both superoxide dismutase (SOD, 20 mg/kg body wt, n = 7) and allopurinol (50 mg/kg body wt, n = 7) were effective in attenuating I/R-induced leukocyte rolling and adherence. In addition, microvascular leakage was significantly reduced by allopurinol (n = 9) and completely abolished by SOD (n = 9) (P < 0.01). These results support the concept that reactive oxygen metabolites contribute to I/R-induced reflow paradox, resulting in leukocyte accumulation, adherence, and increase in microvascular permeability.
"No reflow" has been implicated as prominent phenomenon in microvascular injury associated with ischemia-reperfusion (I/R). The objectives of this study were 1) to elucidate the significance of no reflow in microvascular I/R injury of striated muscle and 2) to determine whether reactive oxygen metabolites play a role in the development of postischemic no reflow. By use of the hamster dorsal skinfold preparation and intravital microscopy, microvascular perfusion of capillaries and postcapillary venules of striated muscle was quantitatively assessed before and 30 min, 2 h, and 24 h after 4 h of tourniquet-induced ischemia. I/R was characterized by a significant reduction (P < 0.01) in functional capillary density to 35% of baseline values during initial reperfusion, with incomplete recovery after 24 h (n = 9). In addition, capillary perfusion was found to be extremely heterogeneous, and wall shear rate in postcapillary venules was significantly decreased (P < 0.01). Treatment with either superoxide dismutase (SOD; n = 9) or allopurinol (n = 9) resulted in maintenance of capillary density of 60% of baseline (P < 0.05). Furthermore, I/R-induced capillary perfusion inhomogeneities and decrease of wall shear rate in venules were attenuated significantly (P < 0.01) by SOD and allopurinol. Thus part of capillary perfusion disturbances during I/R in striated muscle may be caused by increased postcapillary vascular resistance, probably mediated by reactive oxygen metabolites. However, the fact that in SOD- and allopurinol-treated animals 40% of the capillaries were still found to be nonperfused indicates that mechanisms other than oxygen radicals play an important role in the development of postischemic no reflow.
Familial amyloidotic polyneuropathy (FAP) caused by amyloidogenic transthyretin (ATTR) mutations is the most common form of hereditary amyloidosis. We investigated the diagnostic value of the bone scanning agent technetium-99m 3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) in this disease. Eight patients (four males, four females; age 54.4+/-8.3 years, range 43-67 years) with ATTR-FAP proven by immunohistochemistry and molecular analysis and a control group comprising ten oncological out-patients (five males, five females; age 53.4+/-8.5 years, range 34-66 years) without evidence of bony metastases were studied using 99mTc-DPD. Whole body tracer retention was 80.1%+/-10.3% (range 65.1%-94.8%) in FAP patients and 55.7%+/-8.1% (range 40.2%-66.7%) in controls at 3 h p.i. (P<0.001), and cardiac uptake was 7.3%+/-2.2% (range 4.2%-10.1%) in FAP patients and 3.1%+/-0.5% (range 2.3%-4.0%) in controls (P<0.001). The heart/whole body uptake ratio was 8.9%+/-1.7% (range 6.5%-11.0%) in FAP patients and 5.6%+/-0.5% (range 5.1%-6.8%) in controls (P<0.001). The three FAP patients with the highest cardiac tracer uptake had cardiomyopathy or arrhythmia. 99mTc-DPD scintigraphy is proposed as a simple and valuable diagnostic aid to evaluate the severity of the disease and the risk of concomitant heart problems.
This prospective, observational study of a cohort of thyroid cancer patients in Germany focusses on the "real-world" practice in the management of thyroid cancer patients. This report includes data from 2376 patients with primary differentiated thyroid carcinoma first diagnosed in the year 1996. The study reveals considerable differences in actual practice concerning surgery and radioiodine treatment. The results indicate that consensus is lacking with respect to the multimodality treatment approach for differentiated thyroid carcinoma. Our analysis represents the most current and comprehensive national assessment of presenting patient characteristics, diagnostic tests, treatment and complications for thyroid cancer.
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