PubMed Health⌕ Search

Biomedical subjects

R Ranaldi

Publications and source records attributed to R Ranaldi.

At least 55 records · Page 3Linked to original sources
PubMed1995

The D1 agonist SKF 38393 attenuates amphetamine-produced enhancement of responding for conditioned reward in rats.

The present study investigated the hypothesis that the D1 subtype of DA receptors is critically involved in reward-related learning. The effects of SKF 38393, a D1-specific agonist, on amphetamine-produced enhancement of responding for conditioned reward were tested. We exposed 69 male Wistar rats to an experimental design consisting of three phases. The preexposure phase consisted of five sessions during which the rats were exposed to an operant chamber containing two levers. One lever produced a lights-off stimulus (3 s) and the other a tone stimulus (3 s). This was followed by four conditioning sessions during which the levers were removed and the rats were exposed to pairings of the lights-off stimulus with food. This phase was followed by two test sessions during which the levers were present and the number of responses made on each lever was calculated as a ratio of the number of responses made during the preexposure phase. A group receiving saline during the test sessions showed a higher ratio of responding for the lights off stimulus than the tone stimulus, demonstrating that the lights-off stimulus had become a conditioned reward. Amphetamine [2.0 mg/kg, intraperitoneally (i.p.), 5 min before the test] enhanced responding specifically on the lever producing the conditioned reward. Groups receiving SKF 38393 (5.0, 10.0, and 20.0 mg/kg, i.p., 5 min before the test) failed to show significantly greater responding for the lights-off stimulus than the tone, indicating a reduction or elimination of the conditioned reward effect. Moreover, SKF 38393 dose dependently reduced the amphetamine-produced enhancement of responding for conditioned reward.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1995

Adenoma-carcinoma sequence of colorectum. Prevalence of K-ras gene mutation in adenomas with increasing degree of dysplasia and aneuploidy.

One hundred and fifty colorectal adenomas were investigated in order to detect the presence of K-ras gene mutation. The adenomas were classified according to the severity of the histological lesion (mild, moderate, or severe dysplasia and carcinomatous transformation) and to the degree of aneuploidy. K-ras mutation was found in 30.8% of cases, mostly consisting of a point mutation of codon 12. K-ras mutation was more frequently found in adenomas > 1 cm and in the villous type. No correlation was otherwise demonstrable with the ploidy pattern of the lesion.

Adenoma↗
PubMed1994

The effects of systemic and intracerebral injections of D1 and D2 agonists on brain stimulation reward.

That dopamine (DA) plays a role in reward-related learning is well documented but the mechanisms through which it acts are not well understood. The present set of experiments investigated the role of DA receptor subtypes within DA-innervated forebrain regions in brain stimulation reward (BSR). Thirty-two rats were implanted with electrodes in the ventral tegmental area (VTA) and cannulae aimed at the caudal nucleus accumbens (NAcc), the caudate-putamen (CP) or cortex. Rate-frequency functions were determined by logarithmically decreasing the number of cathodal pulses in a stimulation train from a value that sustained maximal responding to one that did not sustain responding (thresholds). After BSR thresholds stabilized rats received treatments with DA agonists and their effects on thresholds were analyzed. Systemic treatments consisted of injections of (+)-amphetamine (1.0 mg/kg, i.p., 10 min before testing), the D2 agonist quinpirole (1.0 mg/kg, i.p., 10 min before testing), the novel D1 agonist A-77636 (3.0 mg/kg, s.c., 90 min before testing) or their vehicle (distilled H(2)0). Central treatments consisted of microinjections of quinpirole (0.3-10.0 micrograms/0.5 microliter) directly into the caudal NAcc, CP or cortex or A-77636 (30 micrograms/0.5 microliter) into the caudal NAcc or CP. Results showed that all three agonists, when injected systemically, significantly reduced the threshold frequency required for VTA BSR, indicating a potentiative effect on reward. Central injections of quinpirole in the caudal NAcc, CP or cortex produced significant increases in BSR thresholds indicative of reduced rewarding efficacy of stimulation. Central injections of A-77636 into the caudal NAcc, but not the CP, were associated with a reduction in VTA BSR thresholds, suggesting an increase in reward. These results suggest that stimulation of D1 or D2 receptors enhances the rewarding effect of brain stimulation. In the case of the systemic quinpirole enhancement of reward, the present results suggest that this may not occur in the caudal NAcc, CP or cortex. Finally, the present results suggest that D1 receptor stimulation in the caudal NAcc can facilitate reward-related learning.

Adamantane↗
PubMed1994

Rostral-caudal differences in effects of nucleus accumbens amphetamine on VTA ICSS.

The effects of amphetamine along the rostrocaudal axis of the nucleus accumbens (NAcc) on ventral tegmental area (VTA) intracranial self-stimulation (ICSS) were studied. Eighteen rats were trained to lever press for ICSS in the VTA. Rate-frequency functions were determined by logarithmically decreasing the frequency of cathodal pulses in a stimulation train from a value that induced maximal responding to one that induced no responding (thresholds). After ICSS thresholds stabilized, (+)-amphetamine (20.0 micrograms/0.5 microliter) or its vehicle, distilled H2O (0.5 microliter), were injected directly into the rostral NAcc (n = 6) or the caudal NAcc (n = 8) or the caudate-putamen (CP) (n = 5) just dorsal to the caudal NAcc. Results showed that amphetamine in the caudal NAcc significantly decreased ICSS thresholds without affecting asymptomatic rates of responding, indicating a potentiation of the rewarding efficacy of VTA stimulation. Amphetamine in the rostral NAcc or CP produced smaller, non-significant, decreases in ICSS thresholds. Further analyses revealed a significant positive correlation (r13 = 0.51, P < 0.05) between the site of injection along the rostrocaudal axis of the NAcc and the size of the amphetamine-produced potentiation of VTA stimulation reward. Others have reported topographical differences, including dopamine terminal density and D1 receptor density, in the NAcc. The present results indicate that these anatomical and neurochemical differences appear to be correlated with behavioural differences.

Amphetamine↗
PubMed1994

Centrocytic-like lymphoma associated with localized amyloidosis of the large intestine.

A case of low-grade centrocytic-like (CCL) B-cell lymphoma involving the large intestine, the regional lymph nodes and the spleen is reported. In the large intestine the lymphomatous infiltrate was restricted to sites of intense antigenic stimulation (diverticula, appendix, ileo-caecal valve) and was associated with marked plasma cell differentiation and massive amyloid deposits. The immunophenotype was CD20, CD21, CD45RA/MB1/MT2, CD68, CD45 related/Ki-B3 and HLA-DR positive, and MB2, DBA.44 reactive regarding the CCL cell lymphoma subpopulation; and IgG-lambda positive regarding its plasma cell fraction.

Aged↗
PubMed1994

Automating the generation and collection of rate-frequency functions in a curve-shift brain stimulation reward paradigm.

The electrical self-stimulation paradigm has proven to be very useful in research aimed at delineating the neural substrates involved in reward-related learning. Of the procedures currently employed the curve-shift method is among the more useful since it distinguishes between treatment effects on reward and performance. This method involves generating and plotting rate-frequency functions and quantifying the effects of experimental manipulations on reward by measuring the degree of lateral shift in these functions. We have designed a computerized system that automatically generates and collects descending rate-frequency functions from self-stimulating rats. The 3 main units of this system consisted of a 6809 micro-controller, a programmable timer logic board and a constant current source. The micro-controller and programmable timer operated on custom written software that monitored lever pressing in the operant chambers and controlled stimulation parameters to generate and record rate-frequency functions. The present report describes this system and presents some typical data collected from rats self-stimulating on ventral tegmental electrodes before and after the administration of intra-accumbens vehicle (0.5 microliter distilled H2O), (+)-amphetamine (20.0 micrograms/0.5 microliter), quinpirole (10.0 micrograms/0.5 microliter) and systemic quinpirole (1.0 mg/kg), all dopamine agonists. Stimulation consisting of 300-ms trains of cathodal rectangular pulses (0.1 ms) was available in 50-s trials. The number of pulses per train was decreased logarithmically from a value that sustained maximal responding to one that would not sustain responding. Self-stimulation thresholds were obtained by fitting the Gompertz growth model to the data and calculating the point of maximal acceleration of the sigmoidal curve. It was found that the present system generated and collected rate-frequency functions similar to those that have been obtained manually in previous experiments. The data showed that the system was sensitive to both central and systemic pharmacological manipulations by producing lateral and vertical shifts of the rate-frequency functions, indications of reward and motor effects, respectively. It was concluded that the present design was useful in conducting entire self-stimulation sessions that required minimal monitoring by the experimenter.

Amplifiers, Electronic↗
PubMed1994

Gastric dysplasia: a ten-year follow-up study.

The results of a ten-year follow-up study on gastric dysplasia (GD) are reported. A total of 260 cases were diagnosed, 125 of which had an adequate follow-up, 81 Low Grade Dysplasia (LGD) and 44 High Grade Dysplasia (HGD). Patients with LGD were younger than patients with HGD, while no significant difference in the mean age was found between HGD and carcinoma. LGD regressed in 49.4% of cases, persisted in 18.5% and progressed in 32.1%. HGD regressed in 4.6%, persisted in 13.6% and progressed in 81.8%. In some cases dysplasia reappeared after a long-time interval of apparent regression. In 58 cases progression to cancer was observed: in 35 cases dysplasia was associated with carcinoma (8 LGD and 27 HGD), while in 23 cases dysplasia evolved into carcinoma (14 LGD and 9 HGD). There was a good correlation between the accuracy in following up the patients and the chance of diagnosing the carcinoma at an early stage. The importance of gastric dysplasia as a marker for carcinoma, its precancerous nature and the treatment of the patients are discussed.

Aged↗
PubMed1993

Microinjections of flupenthixol into the caudate-putamen but not the nucleus accumbens, amygdala or frontal cortex of rats produce intra-session declines in food-rewarded operant responding.

Results of recent studies suggest that dopamine (DA) transmission in the caudate-putamen may be involved in food reward-related learning. The purpose of the present study was to evaluate this hypothesis by injecting the DA antagonist cis-flupenthixol (25 micrograms in 0.5 microliters) into the dorsal caudate-putamen of rats (n = 19) trained to lever press for food presented according to a variable interval 30-s schedule. Additional groups received non-reward (n = 8), systemic cis-flupenthixol (0.01, 0.1 mg/kg i.p.; ns = 8), dorsal caudate-putamen injections of the inactive isomer trans-flupenthixol (n = 10), frontal cortical (dorsal to the caudate-putamen site) injections of cis-flupenthixol (n = 6), or cis- or trans-flupenthixol injected into the nucleus accumbens (ns = 9, 8) or amygdala (ns = 6, 5). Rats were tested in 30-min sessions and response rates were recorded every 5 min. As expected, non-reward produced a gradual decline in responding. A similar pattern was seen in the groups receiving systemic (0.1 mg/kg) or dorsal caudate-putamen injections of cis-flupenthixol. No significant effect was seen following systemic (0.01 mg/kg), cortical or amygdala cis-flupenthixol or dorsal caudate-putamen or amygdala trans-flupenthixol. Accumbens cis-flupenthixol reduced rates but did not produce a gradual decline in responding; however, accumbens trans-flupenthixol led to a time-dependent elevation in response rates making interpretation of the accumbens results difficult. It was concluded that dopaminergic projections to the dorsal caudate-putamen may play a critical role in mediating the effects of food-reward on operant responding.

Amygdala↗
PubMed1993

Dopamine D1 and D2 antagonists attenuate amphetamine-produced enhancement of responding for conditioned reward in rats.

It has been suggested that the dopamine D1 receptor may play an important role in reward. The present study was undertaken to investigate the roles of dopamine D1 and D2 receptor subtypes in responding for conditioned reward. This was done by examining the effects of the D1 antagonist SCH 23390 and the D2 antagonists pimozide and metoclopramide on amphetamine-produced enhancement of responding for conditioned reward. The procedure consisted of three distinct phases. During the pre-exposure phase the rats were exposed to an operant chamber containing two levers. One lever produced a lights-off stimulus (3 s) and the other a tone stimulus (3 s). This was followed by four conditioning sessions during which the levers were removed and the rats were exposed to pairings of the lights-off stimulus with food. This phase was followed by two test sessions during which the levers were present and the number of responses made on each was calculated as a ratio of the number of responses made during the pre-exposure phase. A group receiving the vehicle during the test sessions showed a greater ratio of responding for the lights-off stimulus than the tone stimulus, indicating that the lights-off stimulus had become a conditioned reward. Amphetamine (0.1, 1.0, 2.0 and 5.0 mg/kg, IP, 5 min prior to test) specifically enhanced responding on the lever producing conditioned reward. SCH 23390 (5.0 and 10.0 micrograms/kg, SC, 2 h before test) and pimozide (0.1 and 0.2 mg/kg, IP, 4 h before test) dose-dependently shifted the peak in the amphetamine dose-response function to the right, indicating an attenuation of conditioned reward.(ABSTRACT TRUNCATED AT 250 WORDS)

Amphetamine↗
PubMed1993

Microinjections of flupenthixol into the caudate putamen of rats produce intrasession declines in food-rewarded operant responding.

Results of recent studies suggest that dopamine (DA) transmission in the caudate putamen may be involved in food reward-related learning. The purpose of the present study was to evaluate the contribution of DA terminals in the dorsal caudate putamen to food-rewarded operant responding. Experiment 1, a study measuring circling behaviour in 18 rats receiving systemic amphetamine (1.5 mg/kg) and unilateral intracaudate putamen injections of cis-flupenthixol (0.0, 1.0, 10.0, and 25.0 micrograms in 0.5 microliters), a DA receptor antagonist, or its pharmacologically inactive isomer trans-flupenthixol (25.0 micrograms in 0.5 microliter), determined a behaviourally effective dose of cis-flupenthixol. Results showed that cis-flupenthixol dose dependently increased ipsiversive turning and trans-flupenthixol did not. In Experiment 2, an operant study, 36 rats were trained to press a lever for food on a variable interval 30-s schedule. Rats were then randomly assigned to four groups, three of which received one of the following bilateral intracaudate injections prior to three subsequent test sessions: saline (n = 6; 0.5 microliters), cis-flupenthixol (n = 10; 25.0 micrograms/0.5 microliter), and trans-flupenthixol (n = 10; 25.0 micrograms/0.5 microliters). Rats in the home cage control group (n = 10) received two bilateral intracaudate putamen injections of cis-flupenthixol (25.0 micrograms/0.5 microliters) in their home cages and a final injection of cis-flupenthixol prior to a test session. The results showed that cis-flupenthixol, but not trans-flupenthixol or saline, produced a time-dependent intrasession decline in operant responding. This pattern resembled that seen in extinction.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Lipid-rich adenoma of the thyroid.

A case of clear cell adenoma of the thyroid associated with an anaplastic spindle cell carcinoma is reported. Histochemical and ultrastructural examination showed abundant cytoplasmic lipid inclusions and frequent cytoplasmic vesicles, which both may have contributed to the clear cell change. The follicular cell origin was demonstrated by thyroglobulin positivity using immunohistochemistry. We believe that this adenomatous lesion shows close similarities with the lipid-rich cell adenoma first described by Schröder et al. in 1984.

Adenoma↗
PubMed1993

Tracheobronchopathia osteochondroplastica.

A 65 year old man presented with exacerbation of the chronic bronchitis from which he had been suffering for several years. A chest X-ray revealed disatelectatic pulmonary zones. Bronchoscopy showed numerous nodules, beginning at the mid-trachea and extending into the major bronchi. Histological examination of the biopsy specimens demonstrated well-differentiated cartilaginous tissue, consistent with tracheobronchopathia osteochondroplastica.

Aged↗
PubMed1992

Epithelial dysplasia of the gastric mucosa. A morphometric and ploidy pattern study.

60 cases of gastric dysplasia (20 mild, 20 moderate and 20 severe) were quantitatively studied and compared with cases of hyperplastic polyp (No 10), intestinal metaplasia (No 20), peptic ulcer (No 10) and invasive adenocarcinoma (No 20). In each case the area, the perimeter and the integrated optical density of 100 nuclei were measured in Feulgen stained tissue sections by means of a Leitz TAS. The stepwise discriminant analysis demonstrates that severe dysplasia and adenocarcinoma can be well distinguished from mild and moderate dysplasia. The ploidy pattern study demonstrates that the presence of severe dysplastic changes corresponds to a sharp increase in the degree of aneuploidy. In peptic ulcer, intermediate values between "benign" and "malignant" lesions were found.

Adenocarcinoma↗
PubMed1992

Quantitative study of the precancerous and malignant lesions in colorectal adenomas.

150 endoscopically removed colorectal adenomas are quantitatively studied. In 90 cases dysplastic glands constituted the entire lesion (30 mild, 30 moderate, 30 severe); in 60 cases foci of adenocarcinoma were present (30 intramucosal, 30 submucosal). In each case the area, the perimeter and the integrated optical density of 100 nuclei were measured from Feulgen-stained paraffin sections. The results show a continuous neoplastic progression in the trends of the morphometric parameters as well as in the ploidy pattern. The stepwise discriminant analysis defined the morphometric features of the atypical nuclei, which were present in small numbers also in mild dysplasia; they progressively increased in number, reaching the maximum in submucosal carcinoma.

Adenocarcinoma↗
PubMed1992

Endometrioid carcinoma arising in endometriosis. Case report.

Malignant transformation arising in endometriosis has been reported in some cases. Following Sampson's criteria, about 0.7%-1% of all cases of endometriosis undergo malignant transformation and the ovary is the most frequent site. A case is reported of a patient with endometriosis which, after 10 years, grew into ovarian endometrioid carcinoma. The relationship between endometriosis and cancer suggests a radical treatment of endometriosis and a careful assessment of postmenopausal woman presenting reactivation signs.

Adenocarcinoma↗
PubMed1990

Gastric duplication communicating with a pancreatic duct. Report of a case.

A case of gastric duplication communicating with the pancreatic duct system is reported. The clinical presentation consisted of abdominal pain with recurrent acute pancreatitis. The histopathological examination showed that the duplication was lined with normal pyloric mucosa. In the tubular structure, connecting the duplication to the pancreatic ducts, an increase in the number of serotonin-positive cells was found. The pancreas showed dilatation of the duct system and chronic pancreatitis.

Female↗