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M Marchi

Publications and source records attributed to M Marchi.

At least 55 records · Page 3Linked to original sources
PubMed1993

Enhancement of glycine release from human brain cortex synaptosomes by acetylcholine acting at M4 muscarinic receptors.

Synaptosomes prepared from fresh specimens of human cerebral cortex were labeled with [3H]glycine ([3H]Gly) and distributed in parallel superfusion chambers. Exposure to 15 mM KCl evoked a tritium overflow which was largely prevented by 10 mM Mg++, suggesting a consistent component of Ca(++)-dependent [3H]Gly release. Acetylcholine (ACh; 1-100 microM), added during K(+)-depolarization, increased the release of tritium in a concentration-dependent manner (maximal effect, 60%; EC50 = 7 microM). Oxotremorine (1-100 microM) mimicked ACh. The effect of 10 microM ACh was insensitive to the nicotinic antagonist mecamylamine (100 microM), but it was blocked by the muscarinic antagonist atropine (0.1 microM). Three muscarinic receptor antagonists, pirenzepine, AF-DX 116 (11-[12-[diethylamino-methyl]-1-piperidinyl]acetyl-5-11-dihydro -6H-pyrido-[2-3-b][1,4]benzodiazepine-6-one) and himbacine, endowed with relative selectivity for various muscarinic receptor subtypes, prevented with differential affinities the effect of 10 microM ACh. Himbacine was the most potent antagonist of ACh, its pA2 (8.34) being 20- or 50-fold higher than that of pirenzepine (7.27) or AF-DX 116 (6.65). It is concluded that: 1) ACh can increase the release of Gly in human cerebral cortex; 2) the interaction occurs through muscarinic receptors which resemble most the M4 subtype; and 3) considering that Gly is required to activate the N-methyl-D-aspartate glutamate receptor, the ACh-evoked Gly release may represent a linkage between cholinergic and glutamatergic transmission, two systems strongly implicated in cognitive processes.

Acetylcholine↗
PubMed1992

Effects of oxiracetam on neurotransmitter release from rat hippocampus slices and synaptosomes.

The effects of the nootropic drug oxiracetam on the K(+)-evoked overflow of [3H]D-aspartic acid ([3H]D-ASP), [3H]acetylcholine ([3H]ACh), [3H] gamma-aminobutyric acid ([3H]GABA), [3H]noradrenaline ([3H]NA) and [3H]5-hydroxytryptamine ([3H]5-HT) have been studied in superfused rat hippocampal slices. The overflow of [3H]D-ASP was enhanced by low concentrations of oxiracetam (0.01-1 microM) but not by high concentrations (10-100 microM) which showed some tendency to inhibit it. Similarly, low concentrations of oxiracetam increased, although less effectively, the depolarization-evoked overflow of [3H]ACh, whereas higher concentrations were without effect. At the concentrations active on [3H]D-ASP and [3H]ACh overflow oxiracetam did not affect that of [3H]GABA, [3H]NA or [3H]5-HT. The oxiracetam effects present in slices could not be observed in hippocampal synaptosomes. Thus oxiracetam may selectively increase the release of glutamate and acetylcholine in hippocampus by a mechanism which appears not to be sited in the releasing nerve terminals.

Acetylcholine↗
PubMed1992

Dopamine release and dopaminergic inhibition of acetylcholine release in rat striatal slices after nigro-striatal hemitransection and parenteral ganglioside administration.

Hemitransection of the nigro-striatal bundle in adult rats reduced [3H]dopamine ([3H]DA) uptake into striatal slices from the lesioned side to about 20% of that in the contralateral side 5 days after surgery. Spontaneous recovery of [3H]DA uptake was observed at days 8 and 15 post-lesion (42 and 67% of the unoperated side, respectively). After a short treatment (3 days) with the GM1 ganglioside inner ester (AGF2, 30 mg/kg i.p., daily, starting on day 2 after surgery) [3H]DA uptake amounted to 52% of that in the unoperated side. The electrically evoked fractional overflow of [3H]DA was increased by 500% in slices prepared from the lesioned side 5 days after injury, largely due to the reduced re-uptake by the DA axon terminals. The increase on day 5 was only about 350% in AGF2-treated animals. The DA D2 receptor antagonist, (-)-sulpiride, potentiated the stimulus-evoked overflow of [14C]acetylcholine in slices from the unoperated side prelabelled with [14C]choline. The effect of (-)-sulpiride was much reduced (by about 80%) in the lesioned striata at days 5 and 8 after surgery. Partial recovery was seen at day 15. The lesion did not modify the (-)-sulpiride effect in animals treated with AGF2 from the 2nd to the 5th day post-lesion. Thus early ganglioside administration slows the loss of endogenous dopaminergic control of acetylcholine release caused by partial hemitransection of the nigro-striatal bundle.

Acetylcholine↗
PubMed1992

[Surveillance in public health: the methodological problems in identifying risk factors].

Identification of clusters of health events as well as more general problems in public-health surveillance are being increasingly debated. The authors discuss the differences between the systematic (epidemiologic surveillance) and non-systematic (episodic identification of clusters and/or sentinel events) observations. In this regard the role played by statistical methods appears to be specially worthy of consideration, so as to define the capabilities of a given surveillance system in identifying increasing risks. To take into account the relationship between size of the risk to be evidenced and probability (= power) that the implemented test may be significant, specific tables have been developed displaying the relationship between 1st and 2nd type error, sample size and minimum detectable risk, under different exposure levels.

Humans↗
PubMed1992

Comparison of strategies for preventing abdominal-wall weakness after TRAM flap breast reconstruction.

To determine the best method for preserving abdominal-wall integrity after TRAM flap breast reconstruction, the records of 130 patients followed for at least 6 months (mean 18 months) were examined. Three strategies for management of the abdominal-wall repair were compared. In the first group (72 patients), the entire width of the rectus abdominis muscle was harvested with the flap, and the anterior rectus sheath was closed in one layer. In the second group (20 patients), only the medial two-thirds of the rectus abdominis muscle was removed from the abdomen. The muscle and fascial donor defects were closed in separate layers. In the third group (38 patients), only one-fifth of the muscle was preserved, and a two-layered fascial closure of the anterior rectus sheath was performed, emphasizing repair of the internal oblique fascia to the midline fascia deep to the linea alba. Reinforcing synthetic mesh was used (in 10 patients) if closure was difficult or sutures tended to pull through the fascia. The incidence of abdominal weakness and/or bulging was similar in the first two groups (33 and 40 percent, respectively), but significantly lower (8 percent) in the third group (p = 0.006).

Abdominal Muscles↗
PubMed1991

Cholinergic modulation of [3H]dopamine release from dendrosomes of rat substantia nigra.

Dendrosomes prepared from substantia nigra are able to take up and release [3H]dopamine in a CA(2+)-dependent manner. The Vmax values of [3H]dopamine uptake in substantia nigra dendrosomes was about 5 times lower than that in caudate putamen synaptosomes. The pattern of the K(+)-dependency of the [3H]dopamine release in substantia nigra dendrosomes was significantly different from that found in caudate putamen synaptosomes. The release of [3H]dopamine evoked by 15 mmol/l KCl from superfused dendrosomes was increased in a concentration-dependent manner by acetylcholine. The maximal potentiation produced by acetylcholine was about 40%. The potentiation of [3H]dopamine release by 10 mumol/l acetylcholine was insensitive to mecamylamine but antagonized by atropine and by pirenzepine. The effects of acetylcholine on the release of [3H]acetylcholine from substantia nigra nerve endings was also studied. Exogenous acetylcholine added to the superfusion medium decreased in a concentration-dependent manner the release of acetylcholine. This effect was not antagonized by mecamylamine or pirenzepine but fully antagonized by atropine. The data suggest the existence, in the substantia nigra of the rat, of two distinct muscarinic receptor subtypes regulating respectively dopamine release from dopamine dendrites and acetylcholine release from cholinergic nerve terminals.

Acetylcholine↗
PubMed1991

Immediate reconstruction: current status in cancer management.

Immediate elective repair of various defects caused by ablative surgery for treatment of cancer is becoming increasingly common. In comparison with delayed reconstruction, immediate reconstruction has the advantage of lower costs and, in most cases, reduced anesthesia risks. Immediate repair is also technically easier in many cases and may provide better results. Furthermore, it often provides patients with a strong psychological boost, allowing them to progress toward total recovery and minimizing the time they must live with disability and deformity. Experience has shown that immediate reconstruction does not increase the risk of cancer recurrence or metastasis. Elective immediate reconstruction has proven useful for defects of the breast, chest wall, mandible, nose, oral cavity, and extremities. Illustrative examples are provided so that the potential benefits of this approach can be more widely appreciated.

Breast Neoplasms↗
PubMed1991

Poisson approximation to a negative binomial process in the surveillance of rare health events.

The Poisson approximation to a negative binomial process is evaluated regarding the surveillance of rare health events in the framework of the "Sets" scheme. This scheme defines an alarm in terms of "distance" between consecutive events of interest. The system's parameters are determined by minimizing the expected delay for an alarm when a given increase in the event rate has occurred, subject to a restriction on the rate of false alarms. It is shown that the main consequence of the Poisson approximation lies in an increase of the false alarm probability with respect to the assigned one, whilst influence on the expected delay for a true alarm is lower. It is, however, found that over a large range of practical instances, the Poisson assumption provides a reasonable description of the negative binomial process.

Binomial Distribution↗
PubMed1990

Occurrence of transketolase abnormalities in extracts of foreskin fibroblasts from patients with Alzheimer's disease.

Foreskin fibroblast cell lines from healthy subjects and patients with Alzheimer's disease or other neurological disorders have been analyzed for transketolase, by means of isoelectrofocusing and specific immunostaining. The enzyme profile in 70% of Alzheimer cell cultures exhibits alterations which are not encountered in controls and in other neurological diseases examined. Enzyme abnormalities most frequently observed were the appearance of new transketolase forms having unusually high alkaline pI. Experiments carried out with intact cells and with cell extracts treated with and without phenylmethyl-sulphonyl fluoride, suggest that the peculiar transketolase abnormalities observed in Alzheimer fibroblasts are due to enhanced proteolysis occurring in these cells rather than to intrinsic enzyme lability.

Alzheimer Disease↗
PubMed1990

Muscarinic receptors mediate direct inhibition of GABA release from rat striatal nerve terminals.

The effects of acetylcholine (ACh) on the depolarization-evoked release of [3H]gamma-aminobutyric acid ([3H]GABA) have been investigated using synaptosomes prepared from rat corpus striatum and depolarized by superfusion with 9 mM KCl. Acetylcholine inhibited the [3H]GABA overflow in a concentration-dependent manner. The maximal effect was about 50%. The IC50 value (concentration producing half-maximal effect) amounted to 1 microM, in the absence of acetylcholinesterase inhibitors. The effect of ACh on the K(+)-evoked [3H]GABA release was counteracted by the muscarinic receptor antagonist atropine, but not by the nicotinic receptor antagonist mecamylamine or by the selective M1 antagonist pirenzepine. The data show that muscarinic receptors with low affinity for pirenzepine are localized on GABAergic nerve endings in rat corpus striatum where they may directly inhibit the release of GABA.

Acetylcholine↗
PubMed1990

Pirenzepine-insensitive muscarinic autoreceptors regulate acetylcholine release in human neocortex.

The release of [3H]acetylcholine ([3H]ACh) and its modulation mediated by autoreceptors were investigated in synaptosomes prepared from fresh human cerebral cortex prelabelled with [3H]choline ([3H]Ch) and depolarized in superfusion with 15 mM KCl. The K(+)-evoked release of tritium was almost totally accounted for by unmetabolized [3H]ACh and was largely calcium-dependent. Exogenous ACh decreased the depolarization-evoked release of [3H]ACh in a concentration-dependent manner (EC50 = 1.5 microM). The inhibitory effect of ACh on [3H]ACh release was counteracted by the non-selective muscarinic antagonist atropine. In contrast, the selective M1 receptor antagonist pirenzepine was ineffective. It is concluded that muscarinic autoreceptors regulating the release of ACh are present on cholinergic nerve terminals of human cerebral cortex and appear to belong to a pirenzepine-insensitive subtype.

Acetylcholine↗
PubMed1990

Endogenous aspartate release in the rat hippocampus is inhibited by M2 'cardiac' muscarinic receptors.

The release of endogenous aspartic acid elicited by depolarization of rat hippocampus synaptosomes with 15 mM KCl was totally calcium-dependent. Acetylcholine (ACh) added to the superfusion medium inhibited the K(+)-evoked release of aspartate in a concentration-dependent manner. The effect of ACh was mimicked by oxotremorine and carbachol. It was insensitive to the nicotinic receptor antagonist mecamylamine but blocked by the non-selective muscarinic receptor antagonist atropine. Further pharmacological characterization of the muscarinic receptor involved showed that the ACh effects was insensitive to the M1 selective muscarinic receptor antagonists pirenzepine and dicyclomine. However, the inhibition by ACh of aspartate release was counteracted by 11-[[2-[(diethylamino)methyl]-1-piperidinyl]acetyl]-5,11-dihydro-6H- pyrido-[2-3-b][1,4]benzodiazepine-6-one (AF-DX 116), a selective M2 'cardiac' receptor antagonist. The calcium dependence of the release of aspartate and its regulation through presynaptic receptors are suggestive of a transmitter role for this excitatory amino acid. Moreover, the similarities between the present results and those previously obtained with glutamate are compatible with the idea that aspartate and glutamate are co-released in the rat hippocampus.

Acetylcholine↗
PubMed1990

Chromosomal monitoring of chromium-exposed workers.

A cytogenetic analysis was carried out on peripheral blood lymphocytes of workers exposed to chromite in a ferrochromium plant, to evaluate the possible existence of genetic damage. A quantitatively limited increase in aberrant cell frequencies was detected in subjects working in the furnace sector. The data were analyzed by several statistical approaches.

Adult↗
PubMed1990

Early childhood eating behaviors and adolescent eating disorders.

Maladaptive eating patterns were traced longitudinally in a large random sample of children. Pickiness and concern with weight were more common in girls than in boys, and the prevalence of pickiness declined with age. No age or sex differences in family contention around meals nor in bingeing were shown. All problem behaviors showed significant stability over the 10-year span studied, beginning at ages 1 to 10. Certain eating and digestive problems in early childhood were predictive of symptoms of bulimia nervosa and anorexia nervosa in adolescence. Findings regarding prospective risks implicate pica and problem meals in early childhood for later bulimia nervosa; suggesting problems in self-control of eating behavior as well as eating-related family struggles. Risks in early childhood for subsequent symptoms of anorexia nervosa include picky eating and digestive problems.

Adolescent↗