Biomedical subjects

L Giovannelli

Publications and source records attributed to L Giovannelli.

47 records · Page 3Linked to original sources

PubMed1988

Purinergic modulation of cortical acetylcholine release is decreased in aging rats.

The effect of adenosine, N-ethylcarboxamide adenosine (NECA), and caffeine on acetylcholine (ACh) release was investigated in cortical slices prepared from 3 and 22-24-month-old rats. The slices were perfused with Krebs solution and electrically stimulated at 0.2, 1, and 5 Hz stimulation frequency. In old rats, ACh released by stimulation at 1 and 5 Hz was about half as large as in adult rats. In 22-24-month-old rats, the potency of adenosine was strongly reduced, and a similar significant inhibition of ACh release was obtained with concentrations of 1 microM adenosine in adult and 300 microM in old rats. Conversely, NECA, which has no effect on ACh release in adult rats, brought about a 40% decrease in old rats. Caffeine at 50 microM concentration enhanced, and at 500 microM inhibited, the evoked ACh release in adult rats, but was inactive in old rats. The possibility is envisaged that aging may modify purinergic modulation of ACh release by inducing conformational changes in purinergic receptors or changing adenosine metabolism.

Acetylcholine↗

PubMed1986

Electropherotyping of human rotaviruses: an epidemiological survey of rotavirus infections in Sicily.

An electrophoretic analysis of rotavirus RNA segments was carried out on 522 faecal specimens, obtained from children hospitalized in Sicily in the period 1981/85. One hundred and one viral isolates could be characterized with respect to the electrophoretic pattern of their genomic RNAs. This analysis revealed that in 1981/82 different electropherotypes cocirculated in the infant population. In 1983 one of the patterns became prevalent; in 1984/85 only one electropherotype was detected, both in Palermo and Catania specimens. The serotyping showed that all viral strains with the prevalent electropherotype were subgroup II and serotype 1. These results contrast with the extensive genome variability of rotavirus strains observed in urban areas.

Child↗

PubMed1986

Effect of adenosine, adenosine derivatives, and caffeine on acetylcholine release from brain synaptosomes: interaction with muscarinic autoregulatory mechanisms.

Synaptosomes, prepared from rat cerebral cortex and hippocampus, were preincubated with [methyl-3H]choline. The effect of adenosine, cyclohexyladenosine, N-ethylcarboxamide adenosine, 2'-deoxyadenosine, and oxotremorine on K+-evoked 3H efflux was investigated. High-voltage electrophoretic separation showed that in the presence of physostigmine, the K+-evoked 3H efflux from hippocampal synaptosomes was 90% [3H]acetylcholine and 10% [3H]choline. Adenosine (30 microM) and oxotremorine (100 microM) both decreased [3H]acetylcholine release from hippocampal synaptosomes. The effect was inversely proportional to the KCl concentration and disappeared at a KCl concentration of 50 mM. Cyclohexyladenosine was approximately 3,000 times more active than adenosine, whereas N-ethylcarboxamide adenosine and 2'-deoxyadenosine were inactive. This indicates that A1 adenosine receptors were involved in the inhibitory effect. Caffeine antagonized the adenosine effect, and at a concentration of 100 microM, it stimulated [3H]acetylcholine efflux. The inhibitory effect of oxotremorine was as great in cortical as in hippocampal synaptosomes. In contrast, adenosine was much less active in cortical than in hippocampal synaptosomes. When inhibitory concentrations of adenosine and oxotremorine were added together into the incubation medium, the effect of adenosine on [3H]acetylcholine release was consistently reduced. An interaction between muscarinic and A1 adenosine presynaptic receptors at a common site modulating acetylcholine release can be assumed.

Acetylcholine↗

PubMed1986

Effect of oxiracetam and piracetam on central cholinergic mechanisms and active-avoidance acquisition.

Oxiracetam at 100 and 300 mg/kg i.p. dose levels increased acetylcholine (ACh) utilization in the rat cerebral cortex and hippocampus. ACh utilization was assessed by measuring, with a gas chromatographic method, the decrease in ACh level after inhibiting its synthesis by 15 micrograms intracerebroventricularly (i.c.v.) injection of hemicholinium (HC-3). ACh steady state levels were not affected. Piracetam (300 mg/kg i.p.) also increased ACh utilization in the hippocampus. Repeated daily administration of oxiracetam 100 mg/kg i.p. caused a 31% increase in high-affinity choline uptake (HACU) in the hippocampus. A single administration of 300 mg/kg i.p. of oxiracetam and piracetam also increased HACU rate in the hippocampus. However, the effect of piracetam was over within 3 h, while 3 h after its administration oxiracetam still caused a 40% increase in HACU rate. Oxiracetam (100 mg/kg i.p.) significantly antagonized the impairment in the acquisition of an active-avoidance conditioned response (pole climbing) associated with the inhibition of ACh synthesis by HC-3. These results indicate that oxiracetam enhances the activity of the septohippocampal cholinergic pathways, and to a lesser extent, of the cortical cholinergic network.

Acetylcholine↗

PubMed1985

Phosphatidylserine increases acetylcholine release from cortical slices in aged rats.

Acetylcholine release was investigated in cortical slices superfused with choline-enriched Krebs solution containing physostigmine. Slices were prepared from 3 and 24 month old rats treated with either Tris buffer or sonicated suspensions of phosphatidylserine and phosphatidylcholine in Tris buffer. Slices were electrically stimulated at frequencies of 1, 2 and 5 Hz for 5 min periods preceded and followed by rest periods. ACh content of the superfusate was quantified by bioassay. In the 24 month old rats treated with Tris buffer, acetylcholine release, at all frequencies tested, was approximately 50% lower than that in the 3 month old rats. On the contrary, no significant decrease in ACh release was found in the 24 month old rats treated for 30 days with phosphatidylserine (15 mg/kg IP). The same treatment did not increase acetylcholine release in 3 month old rats. Acetylcholine release in 24 month old rats receiving a single administration of phosphatidylserine (15 mg/kg IP) or phosphatidylcholine (15 mg/kg IP) for 30 days was as low as in the 24 month old rats receiving the Tris buffer only. It is proposed that the chronic phosphatidylserine treatment may reduce the age-induced decrease in acetylcholine release by acting on the stimulus-secretion coupling mechanism.

Acetylcholine↗

PubMed1984

GM1 ganglioside facilitates the recovery of high-affinity choline uptake in the cerebral cortex of rats with a lesion of the nucleus basalis magnocellularis.

The effect of repeated administrations of GM1 monosialoganglioside on high-affinity choline uptake (HACU) was investigated in the cerebral cortex of rats with a unilateral electrolytic lesion of the nucleus basalis magnocellularis. In saline-treated rats, 4 days after lesion, a 38% and 14% decrease in HACU-activity was found in the ipsilateral frontal and parietal cortex, respectively. A spontaneous recovery of HACU activity occurred within the next 20 days. In rats receiving daily injections of GM1 from the day of operation, no significant decrease in HACU activity was found in the lesioned hemisphere 4 days after the lesion. In contrast a 25% increase in HACU activity in the frontal area of the opposite hemisphere was detected. No effect of GM1 treatment could be seen on days 10 or 20 after lesion. The possibility that GM1 may exert its stimulatory effect on HACU independently of the well-known effect of gangliosides on neuronal sprouting is discussed.

Animals↗

PubMed1984

[Comparison of diagnostic methods in rotavirus infection: immunofluorescence, ELISA and the latex agglutination test].

To examine the sensitivity and reliability of a latex agglutination test for detecting rotavirus in faecal samples, we have tested 145 stool specimens from pediatric patients with or without diarrhea, comparing such latex test to immunofluorescent antibody technique (IF) and ELISA. Among all samples positive by IF and ELISA, 52.9% were positive by latex test. This percentage was raised to 85.7% when only positive samples from patients with diarrhea were considered. We conclude that the latex test is an useful diagnostic tool in acute diarrhea because of its simplicity and of its sufficient sensitivity.

Child, Preschool↗

PubMed1983

[Immunofluorescence reaction for rotavirus analysis in fecal specimens].

Testing for rotavirus detection in faeces from infants with acute diarrhea can be carried out, with high sensitivity, by immunofluorescence on rhesus monkey kidney cell lines (MA-104). Preincubation of viral inoculum with trypsin enhances further the sensitivity. In the present study we tried to assess the optimal conditions for detection of viral antigens, by analyzing the expression of virus-specific proteins at different times of infection and the effects of trypsin presence during virus adsorption and replication. Maximal production of viral antigens was obtained by infecting the cells 4 hours after cell-seeding and incubating them for 18 hours afterwards. In experiments with simian rotavirus SA-11, pretreated with trypsin and then with a trypsin inhibitor, a marked reduction in the percentage of fluorescent cells was observed thus indicating a role of the enzyme both on the virus and on the cell layer.

Antigens, Viral↗

PubMedDate not supplied

Electropherotypes, subgroups and serotypes of human rotavirus strains causing gastroenteritis in infants and young children in Palermo, Italy, from 1985 to 1989.

During 1985-89, an epidemiological survey was conducted in Palermo, Sicily (Southern Italy) on group A human rotavirus (HRV) strains which cause gastroenteritis in infants and young children. Two hundred and thirty eight HRV strains were characterized for subgroup and serotype using monoclonal-antibody-based ELISA systems, and for electropherotype using polyacrylamide gel electrophoresis. Subgroup II strains were largely predominant, constituting 218/238 of the positive stool samples (91.6%). Among the serotypes, 192/238 strains (80.7%) were serotype 1 and 16 strains (6.7%) were serotype 4; serotype 2 circulated intermittently and serotype 3 was nearly absent (only one subgroup I strain was detected). Two electropherotypes, bbba and cbba, accounted for the largest proportion of the 345 HRV strains examined, 74 (21.4%) and 222 (64.3%) strains, respectively. Unexpected combinations of subgroup, serotype and electropherotype were detected in 5 subgroup I strains, of which 4 possessed a "long" RNA pattern (1 serotype 3 and 3 serotype 4 strains) and one a "short" RNA pattern (a serotype 4 strain). In addition, 4 group C HRV strains (atypical HRV or pararotaviruses) were detected on the basis of electropherotype. These findings emphasize the need for continuous surveillance of HRV infections in different geographic areas of the world in order to detect the appearance of new strains early and to adopt adequate strategies for vaccine preparation and administration.

Antibodies, Monoclonal↗

PubMedDate not supplied

Morphological, biochemical and behavioural changes induced by neurotoxic and inflammatory insults to the nucleus basalis.

Interest in the basal forebrain cholinergic system has greatly increased since neuropathological studies in humans provided evidence that this system is severely affected in Alzheimer's disease and other dementing disorders. In laboratory animals, disruption of the nucleus basalis cholinergic neurones has been produced by several neurotoxic insults in order to obtain a model reproducing the behavioural impairment related to the cholinergic deficits. The experiments reported in this review demonstrate that excitotoxic amino acids, beta-amyloid and lipopolysaccharide, injected directly in the nucleus basalis are toxic to the cholinergic neurones in the rat. The excitotoxin lesions of the nucleus basalis, although not selective, are a useful tool for producing experimental animals with cholinergic hypofunction and for investigating drugs able to ameliorate the cholinergic functions. Local injections of amyloid peptides in the rat nucleus basalis produced cholinergic hypofunction and some behavioural impairment. Finally, an intense glia reaction with a limited cholinergic hypofunction and no behavioural impairment was induced by a 4-week infusion of lipopolysaccharide in the nucleus basalis. In conclusion, all three models, in spite of their limitations, offer useful tools for the study of the pathogenetic mechanisms of Alzheimer's disease and for investigating potentially useful drugs.

Amyloid beta-Peptides↗

PubMedDate not supplied

Ecotoxicological evaluation of wastewater treatment plant effluent discharges: a case study in Prato (Tuscany, Italy).

Textile wastewaters, which contain numerous chemicals such as dyes, surfactants, solvents, organic and inorganic salts, can cause severe pollution problems for the receiving freshwaters. The ecotoxicity of wastewaters in Prato, where there are about 14,000 textile and related factories, was investigated from 1996-1999 by means of bioassays. 147 samples of reclaimed wastewater were collected at the outlets of 4 centralized wastewater treatment plants. The acute and chronic toxicity of the effluents was measured with bioassays using three different target organisms: green algae (Pseudokirchneriella subcapitata), crustaceans (Daphnia magna) and bioluminescent bacteria (Vibrio fischeri). Toxicity was expressed as Effective Concentration 50 (EC50) and Toxic Units (TU). The results indicated that the effluents did not have significant acute toxicity: only 2.74% (EC50<100%, TU>1) of the 146 samples tested with crustaceans and 6.52% (EC50<50%, TU>2) of the 78 tested with bioluminescent bacteria showed toxic effects. With algae, slight chronic toxicity was found in 49.33% (mean EC50 value=86.56%, mean TU=1.16) of the 140 samples tested. The highest relative response was found with the algal assay using Pseudokirchneriella subcapitata: 49.33% of 140 samples showed chronic toxicity at 96 hours (EC50<100%).

Ecosystem↗