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F Mora

Publications and source records attributed to F Mora.

197 records · Page 11Linked to original sources
PubMedDate not supplied

Peptides and self-stimulation of the medial prefrontal cortex in the rat: effects of intracerebral microinjections of substance P and cholecystokinin.

The effects of intracerebral microinjections of substance P and cholecystokinin on self-stimulation of the medial prefrontal cortex of the rat were studied. Intracerebroventricular administration of substance P at doses of 2.5, 5, 10 and 20 micrograms produced a dose-related decrease in self-stimulation of the medial prefrontal cortex; spontaneous motor activity, measured as a control, was not affected. Unilateral microinjections into the medial prefrontal cortex of substance P at doses of 10 and 20 micrograms produced a decrease of self-stimulation of the ipsilateral side, but self-stimulation of the contralateral cortex, used as a control, was not affected. On the contrary, cholecystokinin in both intracerebroventricular administration at doses of 100, 200 and 400 ng, or intracortical microinjections into the medial prefrontal cortex at doses of 200, 400 and 800 ng, had no effect on self-stimulation of this cortical area. These results suggest that substance P, but not cholecystokinin, could be part of the neurochemical substrate underlying self-stimulation of the medial prefrontal cortex in the rat.

Animals↗
PubMedDate not supplied

Release of amino acid neurotransmitters in different cortical areas of conscious adult and aged rats.

The aim of the present study was to investigate whether or not the levels of amino acid neurotransmitters change during the normal process of aging in the cerebral cortex. In vivo push-pull perfusions were performed in four different areas of the cortex of young (3-4 months) and aged (24-26 months) rats: medial prefrontal cortex, sulcal prefrontal cortex, parieto-temporal cortex and occipital cortex. Extracellular levels of Asp, Glu, Ser, Gln, and Gly were analyzed by HPLC-fluorimetric detection. Aspartate, glutamate, and serine showed no differences between young and aged animals in any of the four cortical areas studied. However, in the aged rats, the levels of glutamine, a precursor of acidic amino acid neurotransmitters, were significantly increased in medial prefrontal cortex, sulcal prefrontal cortex, and parieto-temporal cortex. No changes in glutamine were detected in occipital cortex. These results suggest that the extracellular levels of Asp and Glu in the cerebral cortex do not change during the normal process of aging possibly due to functional compensations made by intact neurons and/or astrocytes. In addition, the increase of glutamine in some areas of the cerebral cortex could be indicative of glial (astrocytes) proliferation as a result of neuronal degeneration during the normal process of aging.

Aging↗
PubMedDate not supplied

Aging, prefrontal cortex, and amino acid neurotransmitters: differential effects produced by electrical stimulation.

The purpose of the present study was to investigate the effects of electrical stimulation on the in vivo release of amino acid neurotransmitters in the prefrontal cortex of young (3-4 months) and aged (27-30 months) rats. In vivo push-pull perfusions were performed in the conscious animal. The levels of aspartate, glutamate, and glycine were analyzed by HPLC-fluorimetric detection. Electrical stimulation of the medial prefrontal cortex at the intensity of 0.3 mA produced a significant increase in the levels of aspartate, glutamate, and glycine in young but not aged rats. However, at the intensity of 0.6 mA, a significant delayed increase of these same amino acids was produced in the aged rats. These results support the existence of a differential effect of electrical stimulation on amino acid neurotransmitters in the prefrontal cortex of young and aged rats.

Aging↗
PubMedDate not supplied

Prefrontal cortex and neostriatum self-stimulation in the rat: differential effects produced by apomorphine.

In a dose-response experiment, the effects of intraperitoneal injections of the dopamine receptor agonist, apomorphine (0.075, 0.15, 0.3, 0.6 and 1.2 mg/kg) were studied on self-stimulation elicited from electrodes implanted in the medial and sulcal prefrontal cortex and caudate-putamen in the rat. From the medial and sulcal prefrontal cortex electrodes, apomorphine produced a dose-related decrease of self-stimulation rate which was consistent across animals. From the caudate-putamen electrodes, on the contrary, apomorphine produced a facilitatory effect in the majority of the animals at one or more doses, however, at other doses a decreased self-stimulation rate was observed. The clear and consistent effects of apomorphine on self-stimulation of the prefrontal cortex, together with other experimental evidence in the same line, suggest that dopamine is mediating self-stimulation of this cortical area.

Animals↗
PubMedDate not supplied

In vivo neurochemical analysis, by push-pull perfusion, of the mesocortical dopaminergic system of the rat during self-stimulation.

The region immediately adjacent to a self-stimulation site in the medial prefrontal cortex of the unanesthetized rat was prelabeled with 0.5 mu Ci 14C-dopamine (DA) injected through an indwelling guide cannula. Then successive 5 min push-pull perfusions of the site with an artificial CSF were carried out at a rate of 25 microliter/min so that a washout curve of declining radioactivity was generated under control conditions. When square wave 100 Hz pulses were delivered to the contiguous self-stimulation site, the release of 14C-DA was enhanced either during the actual interval of electrical stimulation or in the perfusion sample collected immediately thereafter. In parallel experiments, however, self-stimulation by the rat of its ventral tegmental area failed to alter the kinetics of 14C-DA release from the cortex when homologous loci were perfused. Analyses by thin-layer chromatography of the perfusates for their content of catechol metabolities revealed that the homovanillic acid fraction declined during stimulation, whereas the level of DOPAC remained relatively elevated. Evidence was also obtained for the new synthesis and subsequent release of norepinephrine during the stimulation of the cortex of the rat. These results suggest that endogenous dopamine, because of the notable alterations in its release and metabolism, plays an important synaptic role in the mediation of self-stimulation behavior at the level of the cerebral cortex.

3,4-Dihydroxyphenylacetic Acid↗
PubMedDate not supplied

Differential effects produced by an anticholinergic on the neuroleptic inhibition of motor behaviour and self-stimulation of the prefrontal cortex in the rat.

A specific dopamine receptor blocker, spiroperidol (0.016, 0.032, 0.064 and 0.128 mg/kg) alone or in combined treatment with the centrally acting anticholinergic, dexetimide (0.5, 1.0 mg/kg) was given intraperitoneally to rats pressing a lever for brain self-stimulation through electrodes implanted in the medial prefrontal cortex. The same treatment was also given to rats in which the spontaneous motor behaviour was measured. Spiroperidol produced a dose-related inhibtion of both self-stimulation and spontaneous motor activity. Dexetimide, given to spiroperidol treated rats, was able to antagonize the motor impairment produced by spiroperidol, but prefrontal cortex self-stimulation remained decreased. These data support the suggested role for dopamine in self-stimulation of the prefrontal cortex in the rat.

Animals↗
PubMedDate not supplied

An electrophysiological and behavioural study of self-stimulation in the orbitofrontal cortex of the rhesus monkey.

It was found that neurons in the posterior orbitofrontal cortex, area 13, of the rhesus monkey were activated from self-stimulation electrodes (in 142 of 168 possible instances), and that neurons in the anterior orbitofrontal areas were much less likely to be activated from the self-stimulation electrodes (in only 28 of 177 possible instances). This activation of neurons in the posterior orbitofrontal cortex was found mainly from self-stimulation sites in the nucleus accumbens septi, lateral hypothalamus, and the orbitofrontal cortex itself. In a second investigation the orbitofrontal cortex was mapped for self-stimulation, and it was found that self-stimulation occurred in the posterior orbitofrontal area. These results implicate the posterior or caudal orbitofrontal cortex, mainly area 13, but not the more anterior orbitofrontal areas, in self-stimulation.

Amygdala↗
PubMedDate not supplied

Selective release of glutamine and glutamic acid produced by perfusion of GLP-1 (7-36) amide in the basal ganglia of the conscious rat.

Glucagon-like peptide 1 (GLP-1)(7-36) amide, a member of the family of glucagon and related peptides, synthesized by intestinal L cells, has a well-defined distribution in rat brain. In addition, specific GLP-1(7-36) amide receptors have also been localized in some regions of the brain, which suggests that this novel gut-brain peptide has a role in brain function. Accordingly, we investigated the effects of this peptide on the release of amino acid neurotransmitters in the basal ganglia of conscious rats after its perfusion through a concentric "push-pull" cannula system with an artificial cerebrospinal fluid. To obtain stable basal levels of amino acids, the basal ganglia were perfused with an artificial cerebrospinal fluid for 2 h at a flow rate of 20 microliters/min and then with GLP-1(7-36) amide for 10 min, followed by 40 min poststimulation perfusion. GLP-1(7-36) amide produced an immediate increase (p less than 0.01) of the extracellular levels of glutamine and glutamic acid in the basal ganglia. By contrast, this peptide has no effect on the levels of aspartic acid, glycine, and serine. Because glutamine is a metabolic precursor of glutamic acid and is synthesized almost exclusively in astrocytes, these findings suggest a stimulatory effect of GLP-1(7-36) amide on astrocytes and/or neurons of the rat basal ganglia.

Animals↗
PubMedDate not supplied

Dopamine and temperature regulation in the primate: effects of apomorphine and pimozide.

The purpose of this study was to determine the effects of a specific dopamine-receptor agonist (apomorphine) and antagonist (pimozide) on temperature regulation in the primate. Using 4 rhesus monkeys and 2 patas monkeys as subjects, increasing doses of apomorphine (0.05, 0.1, 0.2, 0.4, 0.6 mg/kg) injected subcutaneously produced a dose-dependent hypothermia associated with sharp elevations in tail-skin and ear pinna temperatures. Apomorphine also produced dose-related behavioral responses including salivation, hypermotility, hypersensitivity, pupil dilation and erection, suggesting a central site of action. Pre-treatment with pimozide (0.5 mg/kg, SC) blocked the apomorphine-induced hypothermia, but the subcutaneous injection of pimozide alone had no effect on body temperatures. In the patas monkey, the decline in colonic temperature following the injection of apomorphine (0.4 mg/kg) was not associated with a change in metabolic rate or heart rate. In 2 animals, mean colonic temperature fell 1.7, 0.67, and 0.3 degrees C following the injection of apomorphine ((0.4 mg/kg) in 15, 25, and 35 degrees C environments, respectively. These data suggest that the apomorphine-induced hypothermia was mediated by an increase in heat dissipation rather than a decline in heat production. The site of this drug remains to be elucidated.

Apomorphine↗
PubMedDate not supplied

Microcomputer-based coronary care unit central station.

A four-bed central station that can be connected to any commercial intensive-care bedside monitor was developed. The system is based on a personal computer (IBM-AT compatible) as a local unit and on a microcontroller Intel 8031 as a remote unit. Four ECG signals are low-pass filtered, multiplexed, sampled at 256-Hz per channel, 8-bit A/D converted, preprocessed, and converted to a serial format RS-232 by the remote unit. The real-time display of the signals is at the standard speed of 25 and 50 mm/sec. Heartrate, alarms, trend plots, and general patient data are shown on an Olivetti M280 and EGA 13'' color monitor as the local unit. The communication speed was set at 57.6 Kbaud full duplex. Additionally, to reach standard monitoring sweep rates using a 13'' screen with 640 x 350 pixels, an ECG data-compression algorithm was implemented in the remote unit. This unit can support up to eight input channels and can work with any personal computer, via RS-232, with the appropriate software. It also allows other signal preprocessing software that could be developed, such as QRS detection or ST segment quantification, to be loaded into its random access memory and to be run under PC command. The development of this system demonstrated the use of a widespread piece of commercial equipment, the PC, in a very specific application, CCU monitoring, assuring low-cost system implementation. This feature is particularly attractive in upgrading existing CCU units in less developed countries.

Biomedical Engineering↗
PubMedDate not supplied

Duration of effects of phenylbutazone on serum total thyroxine and free thyroxine concentrations in horses.

The objectives of this study were to determine if phenylbutazone decreased serum thyroxine (TT4) and free thyroxine (FT4) concentrations using radioimmunoassay and equilibrium dialysis techniques in horses, and, if so, an additional objective was to determine the duration of this decreased concentration once phenylbutazone administration was discontinued. Serum TT4 and FT4 concentrations were determined before and after administration of 4.4 mg/kg of phenylbutazone i.v. bid for 5 days. Treatment with phenylbutazone caused a significant decrease in TT4 and FT4 concentrations (P < .05). Serum TT4 concentration significantly decreased after day 4 of treatment and remained significantly below baseline value for 10 days after discontinuing phenylbutazone administration; it returned to a value not different from the baseline value by the 11th day. Serum FT4 concentration significantly decreased after day 4 of treatment and remained significantly below the baseline value for only 1 day after phenylbutazone administration was discontinued; it returned to a value not different from the baseline value by the 3rd day after discontinuation of phenylbutazone. These results indicate that serum TT4 and FT4 should not be used to evaluate thyroid function in horses receiving phenylbutazone. In addition, results should be interpreted cautiously when phenylbutazone has been administered within 2 days (for FT4) or within 10 days (for TT4) of sample collection.

Animals↗
PubMedDate not supplied

Effects of amphetamine on the release of excitatory amino acid neurotransmitters in the basal ganglia of the conscious rat.

The effects of systemic injections of amphetamine sulfate on the release of aspartic acid, glutamic acid, and glutamine were studied using a push-pull perfusion system in the conscious rat. Amphetamine produced a dose-related increase of the extracellular levels of aspartic acid and glutamic acid. The mean time effect of amphetamine was 40 min, followed by a recovery to baseline levels. The mean percentage increase in amino acids released by the highest dose of amphetamine (5 mg/kg) was as follows: Asp, 334.6%; Glu, 224.5%; and Gln, 317.6%. All these effects were blocked by the dopamine D1-D2 receptor blocker haloperidol. It is suggested that dopamine, released by amphetamine, induces the release of amino acid neurotransmitters in the neostriatum. In addition, it is proposed that dopamine could mediate the neurotoxic effects produced by amphetamines through their secondary action on the release of excitatory amino acids.

Amino Acids↗
PubMedDate not supplied

Lack of a time-factor in alternating chemoradiotherapy for advanced head and neck squamous cell carcinoma.

PURPOSE: To assess wheiher a radiotherapy time factor exists also for patients affected by head and neck squamous cell carcinoma and receiving combined chemoradiotherapy. METHODS AND MATERIALS: From 1989 to 1997, of 121 patients affected by stage III or IV head and neck squamous cell carcinoma who underwent alternating chemotherapy and radiotherapy according to the Merlano regimen at our institution, 59 were selected for time factor analysis. Until 1995, if chemotherapy had to be delayed because of bone marrow toxicity, radiotherapy was also delayed accordingly. Since January 1996 in order to avoid treatment-free gaps, radiotherapy was delivered continuously until it was possible to resume chemotherapy. Potential predictive factors of local-regional control were included in univariate and multivariate models. The median follow-up is 26 months (5-121 months). RESULTS: As a result of change in treatment policy, mean radiotherapy duration was shorter for 25 patients treated after 1995 (group A, 8.4 weeks) than for those treated during 1995 or before (group B, 9.4 weeks) (t test, P = 0.0012). In contrast, as expected, mean chemotherapy duration remained relatively unchanged through the years (10.9 vs 10.7 weeks for groups B and A, respectively, t test, P = 0.77). At 2 years, the actuarial local-regional control rate was 53 +/- 7% for the whole population. The estimated rates of local-regional control at 2 years were 49 +/- 10% and 56 +/- 9% for patients belonging to groups A and B, respectively. At univariate and multivariate analyses, treatment group was not predictive of local-regional control. CONCLUSIONS: Our attempt to prospectively limit radiotherapy overall treatment time failed to improve outcome. The data, although obtained on a relatively limited number of patients, suggest that tumor cell repopulation during radiotherapy may not be clinically relevant when chemotherapy is part of the treatment for advanced head and neck squamous cell carcinoma.

Actuarial Analysis↗
PubMedDate not supplied

[Oropharyngeal functional evaluation in patients subjected to total laryngectomy with phonatory prosthesis. Manometric and isotopic study].

Our goal in this paper is to evaluate the motor function of the oropharinx using esophageal manometry and isotopic study, in patients that underwent total laryngectomy (TL) with phonatory prosthesis (PP), and with or without cricopharyngeal myotomy (CM). 50 por 100 of the laryngectomized patients showed oropharyngeal dysphagia, more frequent and stronger in patients without CM. Voice quality was considered good or medium in 12/20. With manometry we achieve that after TL there is an intense pressure reduction of the UES, higher in patients with CM, there aren't differences for other manometrics parameters. The oropharyngeal isotopic clearance is clearly disturbed in all patients, there aren't differences due to the type of surgery, neither the degree of dysphagia nor the CM. The association of a CM to PL plus PP is a surgical procedure that improves markedly the manometric and clinic results in these patients.

Adult↗