PARTICIPATION OF PROSTANOIDS IN CHEMICAL ACTIVATION OF THE PERICARDIAL PRESSOR REFLEX IN DOGS

1. Experiments were performed on anaesthetized, open-chest dogs to determine the reflex effects on systemic blood pressure and heart rate produced by stimulation of the parietal pericardium with bradykinin, prostacyclin, prostaglandin E₂ (PGE₂), prostaglandin D₂ (PGD₂) and arachidonic acid. 2. Pericardial application of bradykinin (1 μg) consistently elicited reflex increases in blood pressure and heart rate, whereas application of prostanoids or arachidonic acid in doses up to 10 μg failed to produce any cardiovascular responses. 3. Indomethacin, applied either directly to the parietal pericardium (1 μg/ml) or given intravenously (5 mg/kg) caused a long lasting reduction of the reflex responses to bradykinin. The reflex effects of bradykinin could be temporarily restored by treatment of the pericardium with either prostacyclin (0.1 μg/min) or PGE₂ (0.1 μg/min). PGD₂ (0.1-1 μg/min) did not influence the bradykinin induced pericardial reflex. 4. Superfusion of arachidonic acid (3 μg/min) over the pericardium amplified the reflex effects of bradykinin when given before, but not when given after indomethacin treatment. 5. The results indicate that locally formed prostanoids, specifically prostacyclin and PGE₂, can facilitate activation of the pericardial pressor reflex by bradykinin. The findings may be relevant to the changes in cardiovascular activity occurring during pericardial inflammation.     

Analysis of micronuclei in blue mussels and fish from the Baltic and North Seas

Micronuclei (MN) were analyzed in erythrocytes of flounder (Platichthys flesus) and wrasse (Symphodus melops) and in gill cells of blue mussels (Mytilus edulis). The organisms were collected from three study stations in the Baltic Sea and from seven stations in the North Sea (Karmsund area, Norway) 4 times. The statistically significant differences obtained were related to the season, sex of the fish, and sampling locality. Higher MN frequencies were found in fish and mussels collected from the most polluted study stations in the North Sea. The same tendency could be described in the Baltic Sea; however, it was masked by the recent oil spill from the Butinge oil terminal. Our results showing higher MN frequencies in presumably what were the most polluted study locations suggest that MN tests in fish and mussels may be used for the detection of genotoxic effects in a marine environment. The endpoint is well characterized and can be easily recognized, and the technique is convenient to use in field samplings following standard procedures and protocols.     

SPECT imaging of cerebral arteriovenous angiomas. A preliminary report

BACKGROUND AND PURPOSE: The purpose of this study was to demonstrate scintigraphic evaluation of cerebral perfusion in patients with intracranial hemangiomas. MATERIAL AND METHOD: The examination was carried out in 12 patients aged from 12 to 67 years. In all the patients cerebral angiomas were previously diagnosed and all of them were qualified for intravascular embolization. Brain scintigraphy was performed after IV injection of 99mTcECD and included the dynamic phase with images obtained every 2 seconds for 1.5 minutes and SPECT imaging. The semiquantitative analysis of regional cerebral blood flow was based on the comparison between activity in two symmetrical regions of interest. Cerebral angiography combined with intravascular embolization followed the scintigraphic examination. RESULTS: Based on angiograms, the size of the nidus was estimated at 1.0 to 9.0 cm. In 8 patients the dynamic study showed an increased tracer accumulation in the region of angioma. On SPECT images the nidus was visualized as focally decreased perfusion in all cases. A decreased tracer accumulation in the area adjacent to the nidus was detected in 8 patients. The ratio of activity in the region of angioma to activity in normally perfused tissue calculated using the semiquantitative analysis was 52% to 89%. CONCLUSIONS: SPECT images and dynamic phase of cerebral perfusion scintigraphy allow perfusion changes caused by the presence of intracranial angiomas to be identified.     

Herb-drug,food-drug,nutrient-drug,and drug-drug interactions: mechanisms involved and their medical implications

Adverse drug reactions (ADRs) and iatrogenic diseases have been identified as significant factors responsible for patient morbidity and mortality. Significant studies on drug metabolism in humans have been published during the last few years, offering a deeper comprehension of the mechanisms underlying adverse drug reactions and interactions. More understanding of these mechanisms, and of recent advances in laboratory technology, can help to evaluate potential drug interactions when drugs are prescribed concurrently. Increasing knowledge of interindividual variation in drug breakdown capacity and recent findings concerning the influence of environment, diet, nutrients, and herbal products can be used to reduce ADRs and iatrogenic diseases. Reviewed data suggest that drug treatment should be increasingly custom tailored to suit the individual patient and that appropriately co-prescribed diet and herbal remedies, could increase drug efficacy and lessen drug toxicity. This review focuses mainly on recently published research material. The cytochrome p450 enzymes, their role in metabolism, and their mechanisms of action are reviewed, and their role in drug-drug interactions are discussed. Drug-food and drug-herb interactions have garnered attention. Interdisciplinary communication among medical herbalists, medical doctors, and dietetic experts needs to be improved and encouraged. Internet resources for obtaining current information regarding drug-drug, drug-herb, and drug-nutrient interactions are provided.     

Tenascin-C expression in human breast tumors

INTRODUCTION: Increased amounts of extracellular matrix proteins have been described in breast tumours, which are normally present in embryonal connective tissue, in adults however, these occur only in pathological conditions: one of which is tenascin. Within the tenascin family the most examined and most controversial member is tenascin-C. It has been suggested that tenascin-C decreases cell adhesion, promotes invasion and metastases, and may play role in pathological angiogenesis. MATERIAL AND METHODS: Authors investigated 62 primary breast carcinomas and in further 20 cases both the primary and the recurrent or second primary tumours were examined. In the latter group the main question was whether tenascin-C was of prognostic significance. The newly formed vessels were visualised using CD31 antibody. RESULTS AND CONCLUSIONS: Tenascin-C positivity in the tumour cells was shown in the 10 of the 62 primary carcinomas and in 7 from the second group of cases (20 patients). Of all cases examined, in five specimens tenascin-C positivity was present in normal ductal epithelial cells. In variable amount, in the stroma of invasive tumours, tenascin-C was present in every case. The presence of tenascin-C within tumour cells, at the periphery and also in the stroma of tumours, within the proliferating ducts, around tumour cell nests and in situ carcinomas, furthermore, in the epithelial cells of normal ducts suggests that tenascin-C may promote detachment and migration of carcinoma cells. There was no correlation, however, between tenascin-C expression and the occurrence of recurrences in this small group. Correlation was found between increased stromal tenascin-C expression and angiogenesis. Authors conclude that tenascin-C might have a role in angiogenesis.     

Hyponatremic encephalopathy--some experimental and clinical findings

Hyponatremia is a common electrolyte disturbance occurring in a broad spectrum of patients, from asymptomatic to critically ill. The disease is defined as a decrease in serum sodium concentration to a level below 136 mmol per liter. The brain damage from hyponatremia can be associated with either hyponatremic encephalopathy or improper therapy of symptomatic hyponatremia both in patients and in experimental models of hyponatremia in rats. This review covers the clinical symptoms of hyponatremia as well as the consequences of its correction. It also summarises the effects of experimental hyponatremia associated with vasopressin on some aspects of cerebral blood flow regulation and the morphology of cerebral tissue.     

Biological significance of the different erythropoietic factors secreted by normal human early erythroid cells

Evidence is accumulating that autocrine/paracrine regulatory mechanisms play an important role in regulating normal hematopoiesis. To support this, various growth factors, cytokines and chemokines are expressed and secreted by normal early and differentiated hematopoietic cells. In this review, we summarize recent advances in the identification and understanding of the role of autocrine/paracrine axes in normal human erythropoiesis. We will also address a biological significance of the secretion of (i) metalloproteinases which in addition to growth factors and cytokines are secreted by normal erythroid cells and (ii) membrane-derived microvesicles (MV), that are shed from the surface of maturating erythroblasts/reticulocytes, and as we postulate may also play a role in intercellular communication. We hypothesize that all these factors together play an important role in a crosstalk between erythroid cells and their environment. A better understanding of intercellular crosstalk operating in normal erythropoiesis and of the mechanisms regulating synthesis of these endogenously produced factors may allow us to develop more efficient therapeutic strategies to treat various erythropoietic disorders.