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91.
Abstract We previously demonstrated that epidermal growth factor (EGF) induces a several-fold increase in ornithine decarboxylase (ODC) activity and the steady-state level of ODC mRNA in cultured SV40-transformed human keratinocytes (1). Pretreatment of cell cultures with ultraviolet B (UVB) radiation resulted in a reduction of EGF-induced ODC activity. To determine whether UVB inhibits the accumulation of ODC mRNA by EGF, cells were pretreated with 20 mJ/cm2 UVB or sham-irradiated and then incubated with 100 ng/ml EGF. Northern blot analysis revealed that UVB irradiation entirely blocked the EGF induction of ODC mRNA. Since the binding of EGF to its plasma membrane receptor is the first step in initiating a biological response, the effect of UVB on EGF binding was evaluated. UVB treatment of cultured keratinocytes resulted in an immediate and dose-dependent reduction of EGF binding. Scatchard analysis revealed thai the reduction of EGF binding was due to a 52% decrease in the number of available receptors, from 6.2 × 104/cell to 3.0 × 104/cell. However, UVB decreased the EGF-binding affinity very little (Kd = 0.60 nM in control and Kd=0.75 nM in UVB-treated Z114 cells). In addition, UVB did not alter the rate of EGF internalization. These data suggest that UVB blocks the signal transduction pathway of EGF that is involved in regulation of ODC gene expression. Immunoblot analysis of extracts from irradiated cells showed that UVB induced tyro-sine phosphorylation of EGFR and that the quantity of EGFR protein was unaffected by UVB treatment. Phosphorylation of EGFR may be responsible for decreased binding of EGF to its receptor. 相似文献
92.
Janet L. Stringer Faruk Erden 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1990,105(3):391-401
Using a reverberatory epilepiform discharge of hippocampal-parahippocampal circuits termed maximal dentate activation, this study investigated whether the local release of nitric oxide within these circuits functions as an antiepileptic agent. Two nitric oxide synthase inhibitors (l-nitro-arginine methyl ester and 7-nitro-indazole) and a guanylate cyclase inhibitor (methylene blue) were tested, and none had a significant effect on the time to onset or duration of maximal dentate activation. A membrane-permeable analogue of cyclic guanosine monophosphate (cGMP), 8-bromo-cGMP, caused an increase in the time to onset and a decrease in the duration of maximal dentate activation. The number of neurons expressing NADPH diaphorase activity (a marker for nitric oxide synthase) was also examined after repeated elicitation of maximal dentate activation. After 18 seizures there was a significant, but transient, decrease in the number of hilar/subgranular neurons that were NADPH diaphorase-positive. The decrease was only seen at 1 h after the last seizure. There was no induction of NADPH diaphorase activity. These results are not consistent with the hypothesis that, in hippocampal-parahippocampal circuits in vivo, nitric oxide is released in response to neuronal activity and then acts to terminate the neuronal activity. 相似文献
93.
To examine the involvement of D2 dopamine receptors in the neural mechanism of reinforcement, raclopride tartrate, a D2 specific dopamine antagonist with a relatively fast central action, was injected into 32 rats. The D2 antagonist reduced bar-pressing responses reinforced with electrical stimulation of the ventral tegmental area (ED50=0.079 mol/kg) and those reinforced with food (ED50=0.58 mol/kg) in 18–30 min after IP injection. The reduction in response rates could not be attributed to an interference with motor functions. An increase in the frequency of brain-stimulation pulses and a change in the schedule of food reinforcement, which respectively increased the baseline rate of responding, did not alter the effectiveness of raclopride. SCH 23390, a D1-specific dopamine antagonist, was sensitive to similar manipulation of reinforcement. These results seem to suggest that D1 and D2 antagonists may be acting at different locations in the neural mechanism underlying the reinforcement of operant behaviour. 相似文献
94.
Weller A Leguisamo AC Towns L Ramboz S Bagiella E Hofer M Hen R Brunner D 《Developmental psychobiology》2003,42(2):194-205
The influence of the pre- and postweaning maternal environment on the offspring's phenotype was examined in 5-HT1A and 5-HT1B receptor knockout mice (KO1A and KO1B, respectively). We have previously shown that, when born to and raised by homozygous dams of the same genotype, adult KO1A are more anxious than wild-type (WT) mice, and adult KO1B are hyperactive and slightly less anxious than WT mice. We extend our studies here to the behavioral results of the offspring's own genotype, when the dam's genotype is constant, and the effects of the dam's genotype when the offspring's genotype is constant. In Experiments 1 and 2, KO1A-/- pups produced less ultrasonic vocalizations (USV) than controls in an isolation test on postnatal Day 7 when born to and reared by KO1A dams, either -/- or +/-. Heterozygous F1 pups reared by KO1A-/- dams produced more USV and were less anxious in the plus-maze at 2 to 3 months of age than F1 pups born to and reared by WT dams (Experiment 3). F1 pups reared by KO1B-/- dams produced less USV and were more anxious in the plus-maze than F1 pups reared by WT dams (Experiment 4). The results support a role for maternal effects that may comprise direct effects such as the dam's behavior and nutritional care of the pup, and possibly more complex indirect effects through the establishment of idiosyncratic dam-pup dyadic interactions. We recommend that breeding techniques that rely on same genotype (mutant-mutant or WT-WT) breeding pairs not be used to generate offspring when the focus of research is the study of gene function, but rather when familial effects need to be studied. 相似文献
95.
We report an infant with multiple congenital anomalies, including craniosynostosis, tetralogy of Fallot variant, and limb anomalies associated with a maternal deletion of 15q15-22.1. Only two other patients have been reported with a similar deletion, but the deletion was paternal in both cases. We review our patient's findings and compare them to previously reported individuals with similar 15q abnormalities. Our patient allows an expansion of phenotype associated with mid-15q deletions to include severe craniosynostosis, congenital heart disease, and limb anomalies. This will assist in prenatal counseling and predicting postnatal outcome for other affected individuals. The specific breakpoints in our patient and the other patients with similar deletions may also assist in determining a critical region for suture formation. 相似文献
96.
97.
HIV seroincidence among patients at clinics for sexually transmitted diseases in nine cities in the United States 总被引:1,自引:0,他引:1
Weinstock H Dale M Gwinn M Satten GA Kothe D Mei J Royalty J Linley L Fridlund C Parekh B Rawal BD Busch MP Janssen RS 《Journal of acquired immune deficiency syndromes (1999)》2002,29(5):478-483
Although the numbers of newly reported diagnoses of AIDS decreased in the 1990s, it is not clear whether they reflect a decreasing number of new HIV infections. Direct measurement of HIV incidence through follow-up cohort studies is difficult and costly. We estimated HIV incidence and trends in incidence among men who have sex with men (MSM) and heterosexual men and women at clinics for sexually transmitted diseases (STDs) by using a recently developed serologic testing algorithm that requires only a single blood specimen. Cross-sectional anonymous serosurveys were conducted at 13 STD clinics in nine cities in the United States from 1991 through 1997. Before anonymous HIV testing, demographic and clinical information was abstracted. Of 129,774 specimens tested, 362 (0.28%) were from persons estimated to be recently infected. Incidence among MSM was 7.1% (95% confidence interval (CI): 4.8-10.3), 14 times higher than that among heterosexuals, which was 0.5% (CI: 0.4- 0.7). Incidence among MSM and heterosexuals remained unchanged during the time studied. Decreasing rates of new AIDS diagnoses in the 1990s do not reflect stable rates of new HIV infections among MSM and heterosexual patients attending these clinics. 相似文献
98.
Summary Influenza A2/Singapore and A2/Hong Kong virus strains formed plaques in monolayers of monkey kidney and dog kidney cells. Using a serum-free overlay containing Earle's balanced salt solution with 1% lactalbumin hydrolysate, 1.4 g/1 sodium bicarbonate and 0.6% agarose, plaque formation occurred in 4–7 days. By incorporating compound in the overlay, plaque inhibition was demonstrated by Amantadine, Rimantadine and the isoquinoline derivatives designated Pfizer UK-2054, UK-2617, UK-2762 and UK-2888. 相似文献
99.
Developmental Progression in Children's Knowledge of AIDS: Implications for Education and Attitudinal Change 总被引:1,自引:1,他引:1
Osborne Mary L.; Kistner Janet A.; Helgemo Benjamin 《Journal of pediatric psychology》1993,18(2):177-192
The effectiveness of curricula designed to enhance a child'sunderstanding of AIDS may hinge partially upon incorporatinginformation adjusted to the child's developmental status. Accordingly,we examined the developmental progression of children's understandingof illness transmission in general and AIDS in particular, aswell as explored the relation between a child's knowledge ofAIDS and his/her attitudes toward persons with AIDS. Knowledgeof AIDS was manipulated through use of a brief educational intervention.Results support a developmental progression in knowledge aboutAIDS that is consistent with progressions related to illnessesin general. Knowledge enhancement was associated with positivechanges in attitude. 相似文献
100.
Margaret?Holmes-RovnerEmail author Sue?Stableford Angela?Fagerlin John?T?Wei Rodney?L?Dunn Janet?Ohene-Frempong Karen?Kelly-Blake David?R?Rovner 《BMC medical informatics and decision making》2005,5(1):16