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Considerable Resistance (considerable + resistance)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Long-Lasting Resistance to Extinction of Response Reinstatement Induced by Ethanol-Related Stimuli: Role of Genetic Ethanol Preference

ALCOHOLISM, Issue 10 2001
Roberto Ciccocioppo
Background: The conditioning of ethanol's reinforcing effects with specific environmental stimuli is thought to be a critical factor in long-lasting relapse risk associated with alcoholism. To study the significance of such learning factors in the addictive potential of ethanol, this experiment was designed (1) to characterize the effects of stimuli associated with alcohol availability on the reinstatement of responding at a previously ethanol-paired lever in rats with genetically determined ethanol preference versus nonpreference and (2) to examine the persistence of the motivating effects of these stimuli over time. Methods: Male alcohol-preferring (P) and alcohol-nonpreferring (NP) rats were trained to operantly self-administer ethanol (10% w/v) or water on a fixed-ratio 1 schedule in a 30-min daily session. Ethanol and water sessions were scheduled in random sequence across training days. Ethanol availability was signaled by an olfactory discriminative stimulus (banana extract, S+), and each lever press was paired with brief presentation of the conditioning chamber's house light (CS+). The discriminative stimulus signaling water availability (i.e., nonreward) consisted of anise odor (S,), and lever-responses during water sessions were paired with a brief white noise generation (CS,). The rats then were placed on extinction conditions during which ethanol and water, as well as the corresponding stimuli, were withheld. The effects of noncontingent exposure to the S+ versus S, paired with response-contingent presentation of the CS+ versus CS, on responding at the previously active lever were then determined in 30-min reinstatement sessions. To study the resistance to extinction of the effects of the ethanol-associated stimuli, additional tests were conducted at 3-day intervals for a total of 50 days. Results: The number of ethanol-reinforced responses during self-administration training was significantly greater in P than in NP rats (p < 0.01). After extinction, a significant recovery of responding was observed in both groups of rats under the stimulus conditions associated with ethanol (S+/CS+) but not those associated with water (S,/CS,). However, the response reinstatement was significantly greater in P than NP rats (p < 0.01). In addition, the results revealed a considerable resistance to extinction to the effects of the ethanol-associated stimuli. Throughout the 50-day test period, responding remained significantly above extinction levels in both P and NP rats (p < 0.01), but with an overall greater number of responses in P than NP rats (p < 0.05). Conclusions: The results support the hypothesis that conditioning factors contribute importantly to compulsive ethanol seeking and long-lasting vulnerability to relapse. In addition, the results suggest that genetic predisposition toward heightened ethanol intake extends to greater susceptibility to the motivating effects of ethanol-related environmental stimuli. [source]

European Nature Conservation and Restoration Policy,Problems and Perspectives

RESTORATION ECOLOGY, Issue 4 2009
Jozef Keulartz
Abstract The implementation of Natura 2000 has met with considerable resistance from farmers, fishermen, foresters, and other local residents in most European Union Member States. In response to the rural protest, the majority of governments have gradually abandoned their centralist, top-down approach and increasingly switched over to methods of participatory and interactive policy-making. However, this "democratisation" of European nature conservation policy is not without its problems and pitfalls. The inclusion of an ever-growing group of stakeholders with different and often diverging interests, ideas, views, and values will more often than not lead to conflicts over the future of nature and the landscape. The causes and consequences of these conflicts need to be examined to improve the policy process. [source]

ORIGINAL RESEARCH,SURGERY: Penile Prosthesis Implantation in Cases of Fibrosis: Ultrasound-Guided Cavernotomy and Sheathed Trochar Excavation

THE JOURNAL OF SEXUAL MEDICINE, Issue 3 2007
Osama Shaeer MD
ABSTRACT Introduction., Implantation of a penile prosthesis into fibrosed corpora cavernosa is a difficult and risky procedure. Specialized instruments that assist safer and more efficient excavation include Otis Urethrotome and various cavernotomes, all of which operate underneath the tunica albuginea, out of sight. The blind use of such instruments can result in perforation of the tunica albuginea or injury to the urethra. Aim., This work describes the utility of ultrasonography for adding visual monitoring to any of the above-mentioned instruments, maintaining them in the mid-corpus cavernosum position to avoid perforation, and describes the application of alternative sheathed, sharp instruments that allow fast, efficient, and visually monitored drilling into fibrous tissue. Main Outcome Measures., Clinical outcome data were examined. Methods., Surgery was performed on five cases with extensive fibrosis of the penis. Initial blunt dilatation by Hegar dilators faced considerable resistance. An ultrasound probe was applied to the ventral aspect of the penis. A laparoscopy sheath was advanced under ultrasound guidance up to the fibrous tissue. A sharp laparoscopy trochar was inserted through the sheath. Its tip was oriented in the mid-corpus cavernosum by longitudinal and transverse sonography sections, as it drilled into the fibrous tissue. Laparoscopy scissors were used in the same fashion to cut fibrous tissue lumps. After full excavation, penile prosthesis was implanted. Results., All implants survived adequately. No complications occurred following implantation. Operative time ranged from 50 to 60 minutes. No difficulty was encountered at excavation. Conclusion., Ultrasound guidance can be a handy adjunct to any of the available techniques developed for excavating the fibrosed corpora cavernosa, with a possible decrease in difficulty and complication rate of the procedure. Utility of sheathed, sharp instruments guided by sonography is an alternative to the cavernotomes, allowing fast and efficient drilling into fibrous tissue. Shaeer O. Penile prosthesis implantation in cases of fibrosis: Ultrasound-guided cavernotomy and sheathed trochar excavation. J Sex Med 2007;4:809,814. [source]

CCAAT/enhancer binding protein-, promotes the survival of intravascular rat pancreatic tumor cells via antiapoptotic effects

CANCER SCIENCE, Issue 11 2007
Yasuhito Shimizu
A transcriptional factor, CCAAT/enhancer binding protein-, (C/EBP-,), regulates a variety of cell functions in normal and neoplastic cells. Although the involvement of C/EBP-, in metastasis has been demonstrated clinicopathologically in several types of human cancer, the mechanism by which it functions during the multistep process of metastasis remains largely unknown. We investigated the role of C/EBP-, in the intravascular step of hematogenous metastasis in a rat pancreatic tumor cell line, AR42J-B13, as this step profoundly affects metastatic efficiency. C/EBP-,-transfected AR42J-B13 (,B13) cells acquired considerable resistance against serum toxicity, which was primarily mediated by apoptosis in vitro. Upregulated expression of Bcl-2 and Bcl-xL was seen in ,B13 cells. Enhanced early survival of intraportally injected ,B13 cells in the BALB/c nu/nu male mice liver, detected by the mRNA of a vector-specific gene, was observed. Nick-end labeling analysis of the tumor-injected liver revealed significantly lower rates of apoptosis among intravascular ,B13 tumor cells than among empty vector-transfected AR42J-B13 (mB13) cells. Finally, intrasplenically injected ,B13 cells established a larger number of colonies in the liver than did the mB13 cells. These findings suggest that C/EBP-, may enhance hematogenous metastasis and its antiapoptotic effects may promote the survival of intravascular tumor cells. (Cancer Sci 2007; 98: 1706,1713) [source]