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Biomedical subjects

F Marino

Publications and source records attributed to F Marino.

At least 91 records · Page 5Linked to original sources
PubMed1995

N-methyl-D-aspartate receptors modulate neurotransmitter release and peristalsis in the guinea pig isolated colon.

To assess the role of NMDA receptors in modulating neurotransmitter release in the myenteric plexus, we studied the effects of L-glutamic acid and NMDA on endogenous acetylcholine and noradrenaline overflow (assayed by HPLC) from the guinea pig isolated distal colon. L-Glutamic acid and NMDA enhanced electrically evoked acetylcholine and noradrenaline overflow and these effects were reversed by selective NMDA receptor antagonists. The possible functional significance of these findings was studied by measuring the efficiency of the colonic peristaltic reflex in the presence of NMDA receptor agonists. NMDA inhibited propulsion velocity at all concentrations tested, this effect being antagonized by (+/-)-2-amino-5-phosphonopentanoic acid and virtually abolished in sympathetically denervated animals. In conclusion, the inhibitory effect of NMDA on peristalsis, being almost entirely dependent on the integrity of sympathetic pathways, could be, at least in part, due to NMDA-induced noradrenaline release.

2-Amino-5-phosphonovalerate↗
PubMed1994

Pesticide residue levels in Argentinian pasteurised milk.

Pasteurised milk--120 samples--was analysed (in Santa Fe City, Argentina) to determine organochlorinated pesticides. Almost all samples showed the presence of such residues; the compounds more frequently detected being: heptachlor and its epoxide (98%) and hexachlorocyclohexane .HCH. alpha and gamma isomers. Residues of aldrin and dieldrin; chlordane (alpha and gamma); endosulfan (I and II); DDT (o,p-DDT, p,p'-DDE, o,p-DDD, p,p'-DDD) as well as hexachlorocyclobenzene (HCB) were also found. Despite their presence high concentrations are sporadic, the mean values being less than FAO/OMS tolerance limits. Relations between maxima concentrations and seasons were not found.

Animals↗
PubMed1994

Effect of desipramine-induced blockade of neuronal uptake mechanisms on adrenoceptor-mediated responses in the guinea-pig colon.

In order to clarify whether adrenoceptors in the guinea-pig distal colon are under sympathetic control, we assessed possible variations in the sensitivity to adrenoceptor agonists after blockade of neuronal catecholamine uptake mechanisms by desipramine (DMI). First, experiments were carried out to investigate the effects of DMI added in the organ bath on propulsion velocity, endogenous and [3H] prelabelled acetylcholine overflow, electrically evoked noradrenaline overflow and longitudinal smooth muscle tone. Secondly, we studied the effects of adrenoceptor agonists on the above parameters in untreated animals and in animals chronically treated with DMI. DMI added in the organ bath at concentrations equal to or higher than 30 nM inhibited all the parameters under study. Thus, when evaluating the effect of DMI on concentration-response curves to adrenoceptor agonists, concentrations which were per se inactive were used. DMI added in the organ bath at concentrations up to 30 nM potentiated the inhibitory effects of exogenous noradrenaline on propulsion velocity and acetylcholine overflow, but it did not affect the concentration-response curve to exogenous noradrenaline on longitudinal smooth muscle tone. Furthermore, 30 nM DMI inhibited propulsion velocity during sympathetic nerve stimulation. In preparations obtained from animals chronically treated with DMI, no significant change of propulsion velocity, endogenous and [3H] prelabelled acetylcholine overflow was found with respect to untreated animals. Nevertheless, in such preparations subsensitivity to isoprenaline (acting mainly on muscular beta-adrenoceptors) and clonidine (acting on neuronal alpha 2-adrenoceptors) and super-sensitivity to phenylephrine were observed. Electrically evoked noradrenaline overflow was enhanced, in a frequency-dependent way, by yohimbine and inhibited by clonidine.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1994

Social support and social structure: a descriptive epidemiology.

Despite a very large and growing literature demonstrating the significance of social support for health and well-being, surprisingly little is known about the social distribution of this crucial resource. This paper presents data on the distribution of social support and support resources across social class, marital status, age and gender, with the aims of contributing toward an understanding of the impact of social structures on processes of social support, and of assessing the hypothesis that epidemiological variations in mental health arise partially from social support differences. The epidemiology of perceived social support was found to correspond closely to the epidemiology of psychological distress and disorder. The single exception involved gender, where a positive rather than negative relationship was observed, with women demonstrating the highest levels of both social support and psychological distress. The observed patterns of variation in social support link this significant adaptive resource to one's locations in the social structure and reinforce the conclusion that it represents a promising intervention target. The practical importance of these results, however, are not matched by theoretical significance. Except in the case of marital status, our findings largely discount the hypothesis that the social distribution of mental health is partially attributable to social support differences.

Adult↗
PubMed1993

Inhibition of endogenous acetylcholine release by blockade of voltage-dependent calcium channels in enteric neurons of the guinea-pig colon.

The effects on acetylcholine release from the guinea-pig colon of the N-type calcium channel blocker omega-conotoxin GVIA (omega-conotoxin), the L-type calcium channel blocker nifedipine and the putative blocker of T-type channels, flunarizine, have been investigated. Endogenous basal acetylcholine release and electrically (1 Hz, 1 ms, 450 mA)-evoked overflow in the presence of cholinesterase inhibitor were studied. omega-Conotoxin (1-10 nM) and nifedipine (0.03-3 microM) dose-dependently inhibited basal and electrically-evoked acetylcholine release. Maximal inhibition of basal or electrically-evoked acetylcholine release was about 40% for nifedipine and about 75% for omega-conotoxin. The potency of nifedipine was inversely related to the external calcium concentration: its EC50 value in low-calcium medium (0.5 mM) was as low as 12 nM. Flunarizine inhibited acetylcholine release only at concentrations higher than 0.2 microM. Our results are consistent with an involvement of N- and L-type calcium channels in the control of the endogenous acetylcholine release from the guinea-pig colon.

Acetylcholine↗
PubMed1993

Opioid pathways exert a tonic restraint in the guinea-pig isolated colon: changes after chronic sympathetic denervation.

We have studied the effects of naloxone on acetylcholine and noradrenaline release in the guinea-pig isolated distal colon, and have assessed the effect of naloxone on electrically-induced contractions of the longitudinal muscle and non-adrenergic, non-cholinergic (NANC) relaxations of the circular muscle coat. Naloxone dose-dependently increased resting and electrically-evoked acetylcholine release and electrically-evoked noradrenaline release. Naloxone was more potent in increasing resting acetylcholine release in colonic specimens obtained after chronic sympathetic denervation. Naloxone (1 microM) did not affect electrically-induced contractions of the longitudinal muscle, while it enhanced NANC relaxations of the circular muscle. The effects observed with naloxone in the present experiments suggest that opioid pathways exert a tonic restraint on neurotransmission in the guinea-pig colon. After suppression of the adrenergic inhibitory tone, the functional relevance of opioid pathways seems to be increased.

Acetylcholine↗
PubMed1992

Supersensitivity to morphine after chronic sympathetic denervation in guinea-pig colon.

The possible role of opioid systems in the adaptive changes which follow chronic sympathetic denervation in the guinea-pig colon has been studied by comparing the effects of the opioid agonist morphine in control animals and after chronic sympathetic denervation. Supersensitivity to the inhibitory effects of morphine on the peristaltic reflex was observed after chronic sympathetic denervation, while the potency against acetylcholine release was unmodified. Our results suggest that a modification of the opioid system occurs after sympathetic denervation in the guinea-pig colon. Supersensitivity to endogenous opioids at a site different from that regulating acetylcholine release could account for the counter-regulation of intestinal motility after chronic sympathetic denervation.

Acetylcholine↗
PubMed1988

Distribution of melanoma specific antibody (HMB-45) in benign and malignant melanocytic tumours. An immunohistochemical study on paraffin sections.

The distribution of a recently produced melanoma specific antibody (HMB-45) has been evaluated histochemically on paraffin sections in a large panel of melanocytic and non melanocytic tumours. Results have been compared with the presence of S-100 protein. HMB-45 was shown to be a highly specific antibody being present only in melanomas, junctional melanocytes and histogenetically related neoplasms such as melanocytic neuroectodermal tumour of infancy and, at low levels, on a proportion of peripheral nerve sheath tumours. The high specificity of HMB-45 antibody, coupled with the greater sensitivity of S-100, makes the combined use of these markers practical in the differential diagnosis of skin tumours and of metastatic lesions of uncertain primary site.

Antibodies, Neoplasm↗
PubMed1987

[Non-specific solitary ulcer of the transverse colon (presentation of a case and review of the literature)].

In the light of findings emerging from a critical review of the literature, the Authors present a case of solitary non-specific ulcer of the transverse colon successfully treated by surgery. The various pathogenetic theories are examined, and the diagnostic work-up to which the patient must be subjected is discussed. The study concludes with a description of the choice of therapy.

Colonic Diseases↗
PubMed1987

[Malignant schwannoma of the ileum: an extremely rare disease entity (presentation of a case and review of the literature)].

The authors examine a case of malignant ileal schwannoma successfully treated in the Verona Surgical Clinic. They compare their experience with the data reported in the literature, confirming the extreme difficulty encountered in diagnosing the disease. Therapy is discussed, and the authors stress that, in the presence of an intestinal haemorrhage the origin of which traditional diagnostic investigations are unable to establish, one should always bear in mind the possibility of schwannoma despite its rarity.

Adult↗
PubMed1987

[Esophageal localization of granulosa cell tumor (presentation of a clinical case)].

The authors report on a case of granular cell tumour localized in the lower third of the thoracic oesophagus. The patient, a 49-year-old male, suffering from symptoms of dysphagia over the previous few months, was treated surgically by thoracotomy enucleation of the neoplasm. Despite its slow growth, this rare benign neoplasm, which probably originates in Schwann's sheath, is a candidate for endoscopic or surgical resection.

Diagnosis, Differential↗
PubMedDate not supplied

Preliminary studies of a dicarboxylic acid as an energy substrate in man.

Azelaic acid (Az), a straight saturated chain nine carbon dicarboxylic acid, was administered in saline form to six healthy male volunteers by iv route. Serum levels of Az and urinary amounts of both azelaic and pimelic (C7) acids were measured by an improved gas liquid chromatographic method. Stoichiometric analysis of Az metabolism was compared with that of glucose and palmitic acid. The respiratory quotient (RQ) as well as the ATP/CO2 ratio of Az were quite similar to that of palmitic acid. Therefore, Az oxidation is associated with a low cost of ATP synthesis in terms of carbon dioxide production. At the infusion rate used (7.5 g/hr) more than 50% of the administered dose was excreted in the urine. However, the remaining portion was cleared from the plasma in 200 min suggesting an uptake by body tissues which was also confirmed by indirect calorimetric analysis.

Adenosine Triphosphate↗
PubMedDate not supplied

Short-term infusion of azelaic acid vs intralipid in healthy subjects evaluated by indirect calorimetry.

Medium-chain dicarboxylic acids (MCDA) are usually considered byproducts of beta-oxidation when omega-oxidizable medium-chain monocarboxylic acids are accumulated, as in beta-oxidation impairment. However, evidence exists of a mitochondrial and cytoplasmatic peroxisomal carnitine independent beta-oxidation of these diacids. Our purpose was to evaluate whether MCDA could be used as source of calories. The metabolic response to intravenous administration of azelaic acid (AA) vs Intralipid (IL) was evaluated in six healthy overnight fasting male volunteers who received an infusion of 10 g of AA over 80 min and as a control 10 g of IL. AA reached a peak concentration at 80 min, (589 +/- 61 micrograms/ml) and was rapidly cleared from plasma (82 +/- 5 micrograms/ml at 240 min). Respiratory and metabolic parameters were evaluated by indirect calorimetry from the beginning of the infusion for 240 min. In both groups the CO2 production (VCO2) remained unchanged with no significant change from basal values. The O2 consumption (VO2 ml/min/m2) increased over basal values reaching a peak at the end of the infusion in both groups (AA from 119.4 +/- 16.9 to 143.0 +/- 27.6; IL from 124.7 +/- 16.8 to 152.3 +/- 29.5). Respiratory quotient (RQ) consequently decreased significantly (AA from 0.85 +/- 0.06 to 0.76 +/- 0.06; IL from 0.89 +/- 0.06 to 0.78 +/- 0.03) and calories derived from lipids increased. Metabolic rate (MR kcal/hr/m2) showed a slight increase (AA from 34.0 +/- 4.4 to 40.3 +/- 6.8; IL from 35.9 +/- 5.1 to 41.3 +/- 10.5). There was no significant difference between AA and IL treatment in all measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗