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81.
Reports in the literature suggest that the primary sensory neurons of the olfactory system may provide a direct route of entry for agents into the central nervous system (CNS). To investigate whether cadmium, a heavy metal which is normally excluded from the CNS by the blood-brain barrier, can enter the CNS via the olfactory system, rats were exposed either intranasally (unilaterally) or ip to 109Cd (1 mumol Cd labeled with 1 microCi 109Cd). Rats were allowed to survive 7 days, at which point they were euthanized and the kidneys, livers, right and left forebrains, right and left olfactory bulbs, and right and left olfactory epithelia were removed. Tissues were placed in scintillation vials and radioactivity counted. In rats exposed by intranasal instillation, Cd levels were significantly elevated in the kidney, liver and ipsilateral olfactory bulb and epithelium, but not in the contralateral bulb and epithelium or forebrain areas. With the ip exposure, Cd levels were only elevated in the kidney and liver. In a second study the protocol was repeated (without ip exposure), but the olfactory bulbs and epithelium were washed in EDTA before counting. Cd was still present in the bulbs after washing, suggesting that the metal was internal and not bound to the external membrane. In the final experiment, both time course and dose effect of this phenomenon were explored. Rats were exposed either intransally to 1 mumol Cd labeled with 109Cd (1 microCi) and then sacrificed after 1, 3, 7, or 14 days or were exposed to 0.01, 0.1, or 1.0 mumol Cd labeled with 1 microCi 109Cd and sacrificed after 7 days.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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M H Teicher A L Gallitano H A Gelbard H K Evans E R Marsh R G Booth R J Baldessarini 《Brain research. Developmental brain research》1991,63(1-2):229-235
Synthesis-modulating dopamine (DA) autoreceptor function was studied in vivo using gamma-butyrolactone (GBL) to block propagation along DA axons. DA synthesis was measured by the accumulation of L-3,4-dihydroxyphenylalanine (L-DOPA) after inhibition of aromatic L-amino acid decarboxylase. GBL treatment markedly increased DOPA accumulation in both the striatum and prefrontal cortex of developing rats. The selective DA partial D1 agonist SKF-38393 inhibited this GBL-induced rise in DA synthesis in both the striatum and prefrontal cortex of 15- and 22-day-old rats, but not in adults. The effects of SKF-38393 in developing rats were mimicked by the non-catechol D1 partial agonist CY-208-243, and were blocked by the D1 antagonist SCH-23390, suggesting receptor mediation. The mixed D2/D3 agonist quinpirole attenuated DA synthesis in striatum of both two-week-old and adult rats, but failed to inhibit the GBL-induced increase in DA synthesis in the developing prefrontal cortex. These findings suggest that synthesis-modulating D1-like receptor function may emerge transiently in the developing mammalian forebrain. In the adult striatum these functions appear to be subsumed by D2-like receptors, whereas all synthesis-modulating DA receptor function in prefrontal cortex appears to be essentially lost with maturation. 相似文献
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Drug-dependent patients in general hospitals behave in ways that are difficult for medical and surgical staff to manage. Common problems include drug-seeking, states of intoxication and withdrawal, poor compliance, and behavior that is disruptive or dangerous to others. The authors describe an approach to these problematic behaviors based upon early recognition, a clinical perspective, and administrative action. Institutional initiatives are needed to overcome the practical and conceptual obstacles to effective management of these patients. 相似文献
85.
Galega officinalis L (goatsrue), a plant introduced from Europe and found in abundance in northern Utah, was tested for toxicity in ewes (Ovis aries). Clinical signs of poisoning induced by doses as small as 0.8 g of dried plant/kg body weight/day included dyspnea, anoxia, and foaming nasal discharge. Pathologic signs in animals that died following overdose of the plant included severe hydrothorax, generalized lung congestion, foamy exudate in bronchioles and trachea, epicardial and endocardial petechiation, and pericardial effusion in severely affected ewes. Microscopic lesions included a severe diffuse alveolar and interlobular edema. No significant alterations in blood constituents were observed in treated animals. Ewes administered the plant on several consecutive days developed an apparent adaptation to the toxin of the plant and were thereby able subsequently to tolerate levels 5-10 times the pre-treatment lethal dose with no discernible adverse clinical or pathological effects. 相似文献
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Antenatal administration of glucocorticoids is often used to facilitate fetal lung maturation in cases of prematurity; however, the effects of betamethasone on maternal immune function have not been established. Therefore maternal immune function was assessed with the use of in vitro techniques. Transient and incomplete suppression of the proliferative response to the T-cell mitogen phytohemagglutinin was demonstrated as early as 24 hours after administration of betamethasone. The magnitude and duration of suppression showed a corresponding increase with advancing gestational age, but these effects were not cumulative and were always short-lived (less than 72 hours). No such suppression of the B-cell mitogen lipopolysaccharide was detected. The nonspecific cellular resistance to infection of maternal monocytes was determined through coincubation with the facultative intracellular pathogen Listeria monocytogenes. Increased phagocytic activity with a normal bactericidal effect was measured in the cell preparations obtained from recipients versus nonrecipients of betamethasone. Taken together, these findings clearly show that both specific and nonspecific immune function are intact in the preterm gravid woman after administration of betamethasone and should allay concerns over its use for reasons of infection control alone. 相似文献