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Biomedical subjects

G Bosco

Publications and source records attributed to G Bosco.

At least 73 records · Page 4Linked to original sources
PubMed1994

[Anesthesiological problems in magnetic resonance].

A prospective study was carried out on 68 patients examined with Magnetic Resonance Imaging (MRI) under general anesthesia. Mean patients age was 10 years (range: 9 days to 77 years). MRI was performed with a 1.5 T superconductive magnet and different anatomical regions were studied: the brain in 63 cases, the lumbar spine in 3, the cervical spine in 1 and finally the upper abdomen in 1 patient. The patients 0-10 years old were anesthetized with isoflurane, while those 11-77 years old were given i.v. propofol and isoflurane. Severe complications occurred in 2 patients only (3%): a 3-year-old child presented respiratory depression and a 21-year-old man had a bronchospasm. Minor complications occurred in 5 more patients. Image quality was excellent in 75% of cases, while few movement artifacts were observed in the extant 25%. To conclude, isoflurane anesthesia is a safe, effective and efficient type of sedation for the patients to be submitted to MRI which can be used also on an outpatient basis.

Adolescent↗
PubMed1994

Non-N-methyl-D-aspartate receptors mediate neocerebellar excitation at accessory oculomotor nuclei synapses of the rat.

The nature of the receptor which mediates cerebellar-evoked monosynaptic excitations recorded from the accessory oculomotor nuclei (AON), i.e. the nucleus of posterior commissure, the nucleus of Darkschewitsch and the interstitial nucleus of Cajal, was studied in adult rats. Effects of exogenously applied excitatory amino acid (EAA) agonists N-methyl-D-aspartate (NMDA) and quisqualate (QUIS) and of selective NMDA receptor antagonist 2-amino-5-phosphonovaleric acid (2APV) and non-NMDA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX) were examined on both amino acid induced and synaptic excitation. Microiontophoretic application of NMDA and QUIS in the AON of the rat increases the neuronal discharge in a dose-dependent manner. These findings suggest that in the rat cells belonging to AON bear both NMDA and non-NMDA receptors. This result was confirmed by the fact that applications of 2APV selectively antagonized NMDA-induced responses without affecting those to QUIS, while DNQX blocked specifically the excitatory responses to QUIS and did not affect NMDA-mediated excitations. We did not observe any difference, between rats anesthetized with urethane and those anesthetized with halothane, with respect to capability of EAA agonists NMDA and QUIS to increase the AON cells activity and of EAA receptor antagonists 2APV and DNQX to abolish the NMDA-induced and the QUIS-induced effects, respectively. In addition, monosynaptic excitations induced by the stimulation of cerebellar lateral nucleus were abolished by microiontophoretic application of DNQX, but not of 2APV. This finding indicates that neocerebellar inputs activate specifically non-NMDA receptors of AON neurons.

Action Potentials↗
PubMed1993

Cerebellar influences on accessory oculomotor nuclei of the rat: a neuroanatomical, immunohistochemical, and electrophysiological study.

With the aim to evaluate a possible neocerebellar control on eye movements, the projections from the cerebellar lateral nucleus (LN) to the accessory oculomotor nuclei (i.e., the nucleus of posterior commissure, the nucleus of Darkschewitsch, and the interstitial nucleus of Cajal), the putative neurotransmitters subserving this pathway, and the nature of the synaptic influences exerted by these projections were studied in adult rats. We used the orthograde transport of horseradish peroxidase conjugated with wheat germ agglutinin (WGA-HRP) to identify the mesencephalic areas where cerebellofugal fibers terminate, and retrograde labeling with the fluorescent dye fluoro-gold to estimate the incidence of cerebellar neurons projecting to the accessory oculomotor nuclei. Orthograde labeling showed that only a small contingent of cerebellofugal fibers reaches the contralateral accessory oculomotor nuclei. The retrogradely labeled cells were located primarily in the small-celled part of LN. By immunohistochemistry, we observed that all the cells retrogradely labeled from the accessory oculomotor area were also stained by using glutamate or aspartate antisera, but none of them were double-stained with a GABA antiserum. Electrical stimulation of the contralateral LN elicited changes in firing rate of a significant fraction of cells belonging to the accessory oculomotor nuclei (36.4% in the nucleus of posterior commissure, 47.1% in the nucleus of Darkschewitsch, and 44.6% in the interstitial nucleus of Cajal). In 57.8% of the cases, the responses were excitations, most of which had latencies and response characteristics compatible with a monosynaptic linkage. The remaining 42.2% of the cases were inhibitions with latencies ranging between 5 and 22 ms. Extracellular field potential recordings within the contralateral accessory oculomotor nuclei were interpreted as arising from impulses propagating along excitatory axons projecting in a bundle from the cerebellum. Stimulation of LN area in rats following intranuclear injection of kainic acid was not capable of evoking short latency excitations, so these responses can be considered to depend on the activation of LN efferents. The LN projection on accessory oculomotor nuclei could be part of the final precise control exerted by the neocerebellum on those brain structures concerned with movements of the eyes.

Animals↗
PubMed1993

[An esophagoaortic fistula due to a foreign body].

Starting from a case of aortoesophageal fistula caused by a foreign body, some aspects of the treatment of upper gastrointestinal hemorrhage of uncertain etiology are discussed. The time between bleeding and perforation often notes it possible to perform resolutive diagnostic tests (aortography, esophagoscopy, CT).

Adult↗
PubMed1993

Myocardial antioxidant defenses during cardiopulmonary bypass.

In 31 male patients undergoing coronary bypass surgery who underwent different periods of cardioplegic hypothermic arrest, the activities of glutathione peroxidase, glutathione reductase, glutathione transferase, copper/zinc-containing and manganese-containing superoxide dismutases, and catalase were studied in the right atrial myocardium, before and 5 minutes after aortic cross-clamping. The levels of thiobarbituric acid reactive substances (TBARS) and nonproteic thiol compounds (NP-SH) were also assessed. Prolonged ischemia followed by reperfusion induced activation of the major myocardial antioxidant enzymes with marked NP-SH depression and TBARS increase, despite cold crystalloid cardioplegic protection. These changes were significantly related to the duration of the ischemic arrest, suggesting: (1) that reperfusion free radical generation is dependent on the severity of the previous ischemic period; and (2) the occurrence of myocardial oxidative stress during cardiopulmonary bypass.

Adult↗
PubMed1993

Broad directional tuning in spinal projections to the cerebellum.

1. Spinocerebellar neurons that project in the dorsal spinocerebellar tract (DSCT) receive mono- and polysynaptic inputs from specific sensory receptors in the hindlimb, and they project mossy fiber terminals to the cerebellar vermis. We examined the functional organization of these neurons and found that it relates to whole-limb parameters like limb posture and direction of limb movement. 2. We recorded the activity of 444 DSCT units during passive perturbations of the hind foot in anesthetized cats. The movements were either confined a single joint (the ankle; 234 cells) or involved the entire hindlimb (210 cells). The cells exhibited opposite responses for opposite directions of whole-limb movement, but a variety of response patterns for opposite directions of movement at one joint. We interpret the result to imply that the population encodes information about the whole limb rather than single joints. 3. Most of the 78 neurons recorded during passive limb placements (63%) responded to changes in limb length and also changes in limb orientation. In fact, the activity of most of the cells was broadly tuned with respect to the direction of passive limb movements generated by moving the hind foot in the sagittal plane. Changes in unit activity could be described by a cosine tuning function with respect to foot positions (72% of responses) and directions of foot movement (50%). 4. The similarity of this behavior to that of neurons in the motor cortex and cerebellar nuclei recorded during voluntary movements is consistent with a common neural code to represent the sensorimotor parameters of limb movement.

Animals↗
PubMed1993

[The diagnostic and therapeutic utility of adenosine triphosphate in supraventricular tachyarrhythmias in childhood].

The diagnostic and therapeutic utility of adenosine triphosphate (ATP) in pediatric age was investigated in fifteen children aged 4 days-16 years (mean age 6.4 years) observed for paroxysmal (Group A-9 pts) or incessant (Group B-6 pts) tachycardia. Twelve patients underwent transesophageal electrophysiological study. ATP was given as an intravenous bolus (0.075-0.5 mg/Kg). In Group A patients, ATP resulted in termination of spontaneous or induced tachycardia, and in all cases interruption in anterograde limb of the re-entry circuit occurred. In Group B patients, ATP induced transient atrioventricular block with persistence of atrial tachycardia, suggesting the atrial origin of the arrhythmia. No adverse haemodynamic effects were observed in any patient. We conclude that in pediatric age ATP must be considered the drug of first choice for junctional reciprocating tachycardias because of its efficacy, short mid-life and insignificant side-effects. Furthermore, it represents an effective diagnostic test for differentiating between junctional reciprocating tachycardias and atrial ectopic tachycardias.

Adenosine Triphosphate↗
PubMed1992

Effects of TRH-T on spinal motoneurones in man.

The effect of thyrotropin-releasing hormone tartrate (TRH-T) on the decrease in H Max/M Max ratio, an index of the spinal motoneurone pool, induced by haloperidol, was studied in 15 healthy volunteers. In all subjects, the H response was examined by an electromyographic apparatus. The values were expressed as H Max/M Max ratio, that gives an index of excitability of the spinal motoneurone pool. It was found that the mean H Max/M Max ratio value significantly decreased after haloperidol administration, but this effect was completely reversed by the injection of TRH-T. This finding suggests that the peptide may modulate motoneurone functions.

Adult↗
PubMed1991

The cerebellopontine system: an electrophysiological study in the rat.

We examined the effects of electric stimulation of the cerebellar lateral nucleus (LN) in the rat on the activity of single pontocerebellar neurons in the basilar pontine nuclei (BPN) and the reticulotegmental nucleus (RtTg). We found that about half of the cells of these nuclei that were influenced by LN stimulation were inhibited. A significant fraction of both excitatory and inhibitory responses had latencies of less than 4 ms and were able to follow high frequency stimulation, compatible with a monosynaptic linkage. Extracellular field potential recordings within the BPN and RtTg were interpreted as arising from impulses propagating along inhibitory axons projecting in a bundle from the cerebellum to these pontine structures. Microiontophoretic administration of GABA antagonists bicuculline or picrotoxin abolished or attenuated most inhibitory effects. Therefore, we conclude that LN-induced inhibition is most likely mediated by cerebellopontine GABAergic fibers. The functional significance of this cerebellopontine inhibitory circuit is discussed.

Animals↗
PubMed1990

Effect of ischaemia-reperfusion on glutathione peroxidase, glutathione reductase and glutathione transferase activities in human heart protected by hypothermic cardioplegia.

The activities of glutathione peroxidase (GSH-px), glutathione reductase (GSSG-rx) and glutathione transferase (GST) were measured in myocardial specimens obtained from right atria of patients subjected to different period of ischaemic arrest (aortic clamping ranging from 10 min to 90 min) followed by 60 min. of reperfusion, during open heart surgery 41-90 min. period of aortic clamping induced a significant increase of GSH-px activity with both H2O2 (p less than 0.05) and cumene hydroperoxide (p less than 0.025) as substrates when compared with baseline levels. Aortic clamping and reperfusion, however did not significantly change the myocardial activities of glutathione transferase and glutathione reductase. It is suggested that the increase of GSH-px in ischaemic-reperfused human hearts may render the myocardium less susceptible to oxidative attack particularly during the reoxygenation period when the level of active oxygen species is greatly elevated.

Female↗
PubMed1990

[Aortic valve replacement in a case of Takayasu's disease with polydistributed localization].

We report a case of a 49 year-old woman suffering from severe aortic regurgitation due to Takayasu's disease involving the ascending and abdominal aorta and the brachial arteries. The patient was managed successfully with aortic valve replacement. Considering the Literature data, the pathogenesis of the aortic insufficiency and the main surgical and anaesthesiologic problems related to the Takayasu's disease are discussed.

Adult↗
PubMed1989

Mitral valve prolapse in Turner syndrome.

We have evaluated 46 patients with Turner syndrome by clinical examination, M-mode and two-dimensional echocardiography, dynamic exercise testing and 24 h Holter monitoring. Twelve patients (26.1%) had mitral valve prolapse and 7 patients (15.2%) had isolated non stenotic bicuspid aortic valve. Aortic root dilation was present in 2 patients (4.3%). Our data indicate that incidence of mitral valve prolapse is significantly higher in Turner syndrome than in the general population (P less than 0.025).

Adolescent↗
PubMed1989

[Blood platelet count and bubble oxygenators. Changes induced by the oral administration of dipyridamole].

The changes in thrombocythemia in patients subjected to extracorporeal circulation (ECC) and pretreated with dipyridamole per os have been examined and compared with a control group in whom the drug was not used; in all patients a circuit with bubble oxygenator was employed. Measurements were carried out before sternotomy, 10' and 60' after ECG, 1 h after the start of intensive therapy and on the 1st surgical day. The variations in thrombocythemia were assessed in consideration of the thrombocythemia/Ht ratio, so as to eliminate the dilution variable. On the basis of the results obtained, it is considered that preoperative treatment with dipyridamole is effective in limiting the fall in thrombocythemia during ECC. The effect of the drug is prevalent in the initial stage of ECC, probably reducing platelet aggregation to non-biological surfaces of the circuit.

Administration, Oral↗