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Biomedical subjects

M Colombo

Publications and source records attributed to M Colombo.

At least 145 records · Page 8Linked to original sources
PubMed1995

Behavioral and biochemical evidence of opioidergic involvement in cocaine sensitization.

Chronic administration of cocaine produces sensitization to its behavioral effects in humans and experimental animals. In the present study, rats treated with cocaine (10 mg/kg, i.p.) once daily for 10 days showed an enhancement in the acute drug stimulation of locomotor activity and stereotypy. Biochemical analysis in the nucleus accumbens of chronic cocaine-treated animals indicated that sensitization of D1 dopamine (DA) receptors had also developed. In fact, stimulation of adenylyl cyclase activity by DA was increased in nucleus accumbens membranes from sensitized rats. Our findings suggest that a novel postsynaptic mechanism, i.e., an increased DA-D1 receptor function, may play a role in the sensitization. A causal relationship between the two events is supported by the observation that neither motor behavioral sensitization nor DA-dependent adenylyl cyclase hyperactivity developed when the opiate antagonist naltrexone (2 mg/kg, s.c.) was given daily for 10 days before cocaine. When given alone, naltrexone was inactive in all respects, which rules out any unspecific action and suggests that its effects may be due to competition at receptors with endogenous opioids mobilized by cocaine. This was indirectly supported by the finding that desensitization of opioid inhibition of adenylyl cyclase developed in nucleus accumbens membranes of cocaine-sensitized rats. Chronic blockade of opioid receptors by naltrexone also counteracted the reinforcing properties of cocaine; conditioned place preference, clearly displayed by cocaine-treated animals, was antagonized in a dose-related manner. Overall, these results confirm that endogenous opioid peptides play an important role in cocaine addiction.

Adenylyl Cyclases↗
PubMed1995

Some novel 5-hydroxytryptamine1A (5-HT1A) receptor agonists reduce gastric acid and pepsin secretion, reduce experimental gastric mucosal injury and enhance gastric mucus in rats.

The present studies examined the actions of a series of novel arylpiperazine 5-hydroxytryptamine1A (5-HT1A) agonists, developed originally for anxiolytic efficacy, in several models of gastric secretion and experimental gastric mucosal injury. These models included conscious gastric acid secretion, pylorus ligation (gastric acid and pepsin secretion), stress-induced gastric mucosal injury, ethanol-induced gastric mucosal damage and gastric adherent mucus levels. 2-(4-[4-(4-Nitropyrazol-1- yl)butyl]-1-piperazinyl)pyrimidine (E4414) and 2-(4-[4-(4-chloropyrazol-1-yl)butyl]-1-piperazinyl)pyrimidine dihydrochloride (E4424) significantly inhibited gastric acid secretion in conscious as well as in pylorus-ligated rats. Both compounds also significantly reduced pepsin secretion in pylorus-ligated animals. E4414 and E4424 significantly reduced both stress-induced and ethanol-induced gastric mucosal injury, and both compounds significantly maintained gastric adherent mucus levels in rats subjected to stress. The antisecretory and gastroprotective actions of E4414 and E4424 were of significantly greater magnitude than those of the reference 5-HT1A agonists, buspirone and 8-hydroxy-2-(di-n- propylamino)tetralin. These results suggest that some novel 5-HT1A agonists exert gastroprotection not only through reduction of aggressive elements in the gut (acid and pepsin secretion) but also through enhancement of defensive gastrointestinal factors such as adherent mucus.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1994

Adjuvant effect of low-dose interleukin-2 on antibody response to influenza virus vaccination in healthy elderly subjects.

It is well known that immune efficiency is frequently deteriorated in elderly people. The age-diminished antibody response to T-cell dependent antigens, such as influenza virus antigens, may explain the low protection offered by influenza vaccination in the elderly population. To investigate the possibility of increasing the antibody response to influenza virus vaccinations, we have conducted a nursing home-based study on the efficacy of IL-2. Seventy-five institutionalized elderly subjects (82 +/- 8 years) were enrolled in the study in the course of winter season 1991-1992. Thirty-nine subjects were treated with three subcutaneous daily injections of interleukin-2 (IL-2, 1 x 10(6) I.U./day) before vaccination and their antibody response was compared to that of 36 aged people receiving the vaccine only. An increased antibody response against influenza virus was present in vaccine plus IL-2 treated subjects (P < 0.001) but not in subjects treated with vaccine only. The number of protected subjects 45 days after vaccination was increased only in the IL-2-treated group (P = 0.045). The low-dose of IL-2 administered and the short-term treatment allowed a good tolerance to the IL-2 injection. In conclusion, the low-dose IL-2 treatment represents an effective means of inducing antibody response to influenza virus antigens in elderly subjects without appreciable toxicity.

Adjuvants, Immunologic↗
PubMed1994

Determination of plasma choline by high-performance liquid chromatography with a postcolumn enzyme reactor and electrochemical detection.

A method for the determination of choline in human plasma is described, involving rapid purification of plasma samples and analysis by high-performance liquid chromatography using an on-column enzyme reactor with electrochemical detection. The linearity of the method was tested at choline levels from 3.5 to 28.6 microM in plasma. The recovery was 86% and was independent of the analyte concentration. The inter-assay precision (as coefficient of variation) and accuracy (as the deviation of the concentration found from the theoretical value) were always below 12% in the whole concentration range. The method was applied to the determination of plasma choline levels in eight healthy volunteers after intramuscular administration of L-alpha-glycerophosphorylcholine (1 g) or a placebo. Mean plasma choline levels in the placebo group ranged from 10.6 to 12.0 microM. After drug administration, the plasma choline level reached 35.1 microM in 30 min, then decreased gradually. Plasma choline levels became comparable in the treated and placebo groups 6-8 h after administration.

Adult↗
PubMed1994

Transmission of hepatitis A to patients with hemophilia by factor VIII concentrates treated with organic solvent and detergent to inactivate viruses. The Italian Collaborative Group.

OBJECTIVE: To determine whether an outbreak of hepatitis A virus (HAV) infection that occurred in 52 patients with hemophilia in Italy was acquired through infusion of contaminated factor VIII or through environmental enteric transmission. DESIGN: A case-control study and a molecular analysis of HAV sequences from implicated lots of factor VIII and from infected patients. PATIENTS: The first 29 patients with hemophilia and jaundice in whom hepatitis A developed were compared with one to three matched controls with hemophilia but no jaundice. MEASUREMENTS: Type of concentrate and batches infused, number of doses, contacts with persons who had jaundice or hepatitis A, travel abroad to countries reported to have a high attack rate for hepatitis A, and consumption of raw shellfish. Hepatitis A viral sequences sought by polymerase chain reaction in lots of factor VIII and in serial serum samples from two patients with hemophilia in whom hepatitis A developed. Amplification by polymerase chain reaction of cDNA transcribed with reverse transcriptase from matched sets of factor VIII and recipient serum samples. Determination of nucleotide sequence of amplified hepatitis A virus genome. MAIN RESULTS: Case patients were neither more nor less likely than controls to have traveled to high-risk countries, consumed raw shellfish, or had contact with persons with jaundice. Case patients were more likely than controls to have received a factor VIII concentrate treated with a solvent-detergent mixture to inactivate viruses (odds ratio, infinity; 95% CI, 4.5 to infinity) and to have had larger infusions of the concentrate during the presumed HAV incubation period (odds ratio, 8.54; CI, 2.78 to 27.5). Hepatitis A viral sequences were found in 5 of 12 tested lots of factor VIII. Genomic sequences of HAV obtained for two matched sets of factor VIII and recipient serum samples were identical within each set but different for the two sets. CONCLUSION: Hepatitis A was transmitted by a factor VIII concentrate treated by a virucidal method (solvent-detergent) that ineffectively inactivates nonenveloped viruses.

Adolescent↗
PubMed1994

Burch colposuspension versus modified Marshall-Marchetti-Krantz urethropexy for primary genuine stress urinary incontinence: a prospective, randomized clinical trial.

OBJECTIVE: Our purpose was to compare the effects of the Burch colposuspension with those of the modified Marshall-Marchetti-Krantz urethropexy. STUDY DESIGN: Eighty women underwent the two types of operation. A full urodynamic investigation was repeated 6 months after surgery. RESULTS: Clinical follow-up continued for 2 to 7 years. Differences in subjective and objective cure rates were not statistically significant (respectively, 92% and 80% for the Burch colposuspension and 85 and 65% for the modified Marshall-Marchetti-Krantz urethropexy). The latter induced a longer hospital stay (7.4 vs 6.3 days, p = 0.001), a later resumption of spontaneous voiding (13.8 vs 8.5 days, p = 0.002), and was associated with considerable complications (one case of blood replacement for retropubic hematoma, one case of severe voiding difficulty, one case of further treatment for stress incontinence, and three cases of symptomatic de novo detrusor instability). CONCLUSION: For its high cure rate, short time to resumption of spontaneous voiding, short hospital stay, and low associated morbidity, the Burch colposuspension should remain the procedure of choice for stress incontinence.

Female↗
PubMed1994

Responses of inferior temporal cortex and hippocampal neurons during delayed matching to sample in monkeys (Macaca fascicularis).

Single-unit activity was recorded from inferior temporal (IT) cortex and the hippocampus in 2 macaques trained on auditory-visual and visual-visual delayed matching-to-sample tasks. The main purpose of the study was to compare the response properties of delay neurons between the 2 areas. The authors noted that (a) IT cortex delay activity was usually selective to a particular stimulus, whereas hippocampal delay activity was usually nonselective; (b) the level of delay activity was generally larger in the hippocampus than in IT cortex; and (c) unlike IT cortex delay activity, hippocampal delay activity tended to increase in magnitude as the delay progressed. The authors also examined the functional significance of delay activity and noted a higher probability of encountering a delay neuron when the monkeys were performing 75%-100% correct as compared with 50%-75% correct. The significance of these findings for visual recognition memory is discussed.

Animals↗
PubMed1994

Effects of auditory and visual interference on auditory-visual delayed matching to sample in monkeys (Macaca fascicularis).

Two monkeys were trained on an auditory-visual (AV) delayed matching-to-sample (DMS) task with auditory cues serving as sample stimuli and visual cues serving as comparison stimuli. To determine whether the monkeys were remembering auditory or visual information during the delay period, auditory and visual interference were presented following the sample stimulus. Auditory interference had little effect on AV DMS performance. In contrast, visual interference severely impaired AV DMS performance, indicating that the monkeys were remembering visual information during the delay period. This finding may reflect a predisposition of monkeys toward remembering information via their dominant visual modality.

Animals↗
PubMed1994

Cometabolic degradation of acifluorfen by a mixed microbial culture.

Laboratory experiments were conducted to study the degradation of acifluorfen 5-[2-chloro-4-(trifluoromethyl)-phenoxyl]-2-nitrobenzoic acid by a mixed microbial population. Concentrations of acifluorfen up to 100 mg/l had no inhibitory effect on the growth of microbial culture. The microorganisms degraded acifluorfen through a cometabolic process in presence of 2-nitrobenzoate. The degradation rate of acifluorfen, determined by liquid chromatography analysis in batch cultures incubated under oxygen-limited conditions were compared. The degradation was slower under oxygen than oxygen-limited conditions. Aminoacifluorfen was produced in both conditions.

Acetates↗
PubMed1994

Pefloxacin in the treatment of severe infections in gynecological cancer patients.

Infections often complicate the medical or surgical treatment of hospitalized cancer patients. In these cases, a broad-spectrum antibiotic treatment is necessary before the microbiological results are available. The aim of the present study is to verify the efficacy of pefloxacin as empirical antibiotic therapy in controlling infectious complications induced by surgery, chemotherapy or radiotherapy in female patients with gynecological cancer. To this purpose, 58 hospitalized patients with gynecologic malignancy and severe infectious complications were treated with intravenous pefloxacin at the dosage regimen of 400 mg every 12 hours. In all, 49 (or 91%) of the 54 evaluable patients were cured. The mean duration of successful treatment was 5.9 +/- 2.1 days (ranging 4-13 days). No side effects or clinical laboratory abnormalities requiring reduction or discontinuation of therapy were observed. We conclude that pefloxacin may be considered a first choice, broad-spectrum, single antibiotic for use in the empirical therapy of infections in gynecological cancer patients.

Adult↗
PubMed1994

The anticonvulsant FCE 26743 is a selective and short-acting MAO-B inhibitor devoid of inducing properties towards cytochrome P450-dependent testosterone hydroxylation in mice and rats.

The effects of the potent anticonvulsant FCE 26743 ((S)-2-(4-3-fluorobenzyloxy)benzylamino)propionamide) on monoamine oxidase (MAO) activity were measured in-vitro and ex-vivo using rat tissue homogenates. In-vitro, FCE 26743 showed potent and selective inhibitory properties towards liver MAO-B, with IC50 values about 10(-7) M for MAO-B and higher than 10(-5) M for MAO-A. When determined ex-vivo in brain, the ED50 value for the inhibition of MAO-B was 1.1 mg kg-1 (p.o.) 1 h post-dosing, whereas MAO-A remained virtually unaffected after administration of 60 mg kg-1. Similar effects were seen in liver. Following oral administration of 5 mg kg-1 FCE 26743 to rats, brain MAO-B inhibition was 79% after 1 h and 13% after 24 h, indicating that FCE 26743 behaves as a short-acting MAO-B inhibitor. The ability of FCE 26743 to act as a MAO substrate was assessed in mice by measuring the urinary excretion of alaninamide, a potential metabolite of FCE 26743 which would result from the action of MAO. No alaninamide was detectable in the 0-8 h urines after administration of a 119 mg kg-1 dose, suggesting that FCE 26743 is not, or only to a small degree, a substrate of MAO. The effects of FCE 26743 on cytochrome P450 enzymes involved in testosterone hydroxylation were determined in rats after repeated administration. No induction of the cytochrome P450 system was noted.

Alanine↗
PubMed1994

A new method for identification of Trichomonas vaginalis by fluorescent DNA in situ hybridization.

The protozoan flagellate Trichomonas vaginalis is responsible for human trichomoniasis, one of the most widespread sexually transmitted diseases in the world. Several methods are currently used for laboratory diagnosis, including direct microscopic observation, cell culture, immunological techniques, and more recently, DNA probing and gene amplification. This report describes an in situ hybridization technique with specific DNA probes labeled with either biotin, rhodamine, or fluorescein for detection of T. vaginalis with fluorescence microscopy. Repetitive DNA sequences were evident in the nuclei of the protozoa as intensively fluorescent regions, giving a spotted pattern. No cross-reactivity between the probes and the DNAs of mammalian cells, yeasts, or bacteria was noted. This technique is potentially useful for the diagnosis of human trichomoniasis in clinical samples.

Animals↗
PubMed1994

Neural ensemble coding in inferior temporal cortex.

1. Isolated, single-neuron extracellular potentials were recorded sequentially in area TE of the inferior temporal cortex (IT) of two macaque monkeys (n = 58 and n = 41 neurons). Data were obtained while the animals were performing a paired-associate task. The task utilized five stimuli and eight stimulus pairings (4 correct and 4 incorrect). Data were evaluated as average spike rate during experimental epochs of 100 or 400 ms. Single-unit and population characteristics were measured using a form of linear discriminant analysis and information theoretic measures. To evaluate the significance of covariance on population code measures, additional data consisting of simultaneous recordings from < or = 8 isolated neurons (n = 37) were obtained from a third macaque monkey that was passively viewing visual stimuli. 2. On average, 43% of IT neurons were activated by any of the stimuli used (60% if those inhibited also are included). Yet the neurons were rather unique in the relative magnitude of their responses to each stimulus in the test set. These results suggest that information may be represented in IT by the pattern of activity across neurons and that the representation is not sparsely coded. It is further suggested that the representation scheme may have similarities to DNA or computer codes wherein a coding element is not a local parametric descriptor. This is a departure from the V1 representation, which appears to be both local and parametric. It is also different from theories of IT representation that suggest a constructive basis set or "alphabet". From this view, determination of stimulus discrimination capacity in IT should be evaluated by measures of population activity patterns. 3. Evaluation of small groups of simultaneously recorded neurons obtained during a fixation task suggests that little information about visual stimuli is conveyed by covariance of activity in IT when a 100-ms time scale is used as in this study. This finding is consistent with a prior report, by Gochin et al., which used a 1-ms time scale and failed to find neural activity coherence or oscillations dependent on stimuli. 4. Population-stimulus-discrimination capacity measures were influenced by the number of neurons and to some extent the number and type of stimuli. 5. Information conveyed by individual neurons (mutual information) averaged 0.26 bits. The distribution of information values was unimodal and is therefore more consistent with a distributed than a local coding scheme.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

High prevalence of silent gallstone disease in dialysis patients.

Gallstone disease was detected in 28% of 119 patients on regular dialysis treatment. The disease was silent in 82% of the patients. Stones were radiolucent in 88% of the cases, radioopaque in 8% and mixed in 4%. Among 49 variables considered, increasing age was the only variable that correlated significantly with increasing prevalence of gallstone disease. Since no relationships were found between gallstones and age or modes of dialysis, it is conceivable that some mechanism(s) linked with the preexisting chronic nephropathy might have been involved in the development of cholelithiasis. End-stage renal disease could be another so far unrecognized risk factor for cholelithiasis.

Adult↗