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Biomedical subjects

M Bacci

Publications and source records attributed to M Bacci.

At least 19 recordsLinked to original sources
PubMed2006

Susceptibility of the ant-cultivated fungus Leucoagaricus gongylophorus (Agaricales: Basidiomycota) towards microfungi.

The aim of this study was to select virulent strains of microfungi against Leucoagaricus gongylophorus, a symbiotic fungus cultivated by leaf-cutting ants. The results from in vitro assays showed that microfungal strains had a variable and significant impact on the colony development of L. gongylophorus. Specifically, Trichoderma harzianum, Escovopsis weberi CBS 810.71 and E. weberi A088 were more effective, inhibiting the L. gongylophorus colonies by 75, 68 and 67%, respectively (P < 0.05) after 15 days. Strain E. weberi A086 and Acremonium kiliense were less effective: 43 and 26%, respectively (P < 0.05). In spite of the current negative perspective of a microbiological control approach for these ants, the present work discusses the possibility of using mycopathogenic fungi for the control of these insects, and points out the importance of encouraging more studies in this area.

Animals↗
PubMed2005

Starch metabolism in Leucoagaricus gongylophorus, the symbiotic fungus of leaf-cutting ants.

Leucoagaricus gongylophorus, the symbiotic fungus of the leaf-cutting ants, degrades starch, this degradation being supposed to occur in the plant material which leafcutters forage to the nests, generating most of the glucose which the ants utilize for food. In the present investigation, we show that laboratory cultures of L. gongylophorus produce extracellular alpha-amylase and maltase which degrade starch to glucose, reinforcing that the ants can obtain glucose from starch through the symbiotic fungus. Glucose was found to repress alpha-amylase and, more severely, maltase activity, thus repressing starch degradation by L. gongylophorus, so that we hypothesize that: (1) glucose down-regulation of starch degradation also occurs in the Atta sexdens fungus garden; (2) glucose consumption from the fungus garden by A. sexdens stimulates degradation of starch from plant material by L. gongylophorus, which may represent a mechanism by which leafcutters can control enzyme production by the symbiotic fungus. Since glucose is found in the fungus garden inside the nests, down-regulation of starch degradation by glucose is supposed to occur in the nest and play a part in the control of fungal enzyme production by leafcutters.

Agaricales↗
PubMed2005

Exposure to human blood inactivates swine endothelial ecto-5'-nucleotidase.

Ecto-5'-nucleotidase (E5'N) is an extracellular enzyme forming anti-inflammatory and immunosuppressive adenosine. We evaluated whether confrontation of pig heart and endothelial cells with human blood changes the activity of E5'N. Pig hearts were perfused ex vivo with fresh human blood for 4 h. Pig aortic endothelial cells (PAEC) were incubated in vitro with human plasma for 3 h. Ex vivo perfusion of pig heart with fresh human blood resulted in a decrease in E5'N activity to 62% and 61% of initial in wild-type and transgenic pig hearts, respectively. PAEC activity of E5'N decreased to 71% and 50% of initial after 3 h exposure to heat-inactivated and active complement human plasma, respectively, while it remained constant in controls. Pig heart activity of E5'N decreased following exposure to human blood, which may affect adenosine production and exacerbate hyperacute and vascular rejection.

5'-Nucleotidase↗
PubMed2004

Low variation in ribosomal DNA and internal transcribed spacers of the symbiotic fungi of leaf-cutting ants (Attini: Formicidae).

Leaf-cutting ants of the genera Atta and Acromyrmex (tribe Attini) are symbiotic with basidiomycete fungi of the genus Leucoagaricus (tribe Leucocoprineae), which they cultivate on vegetable matter inside their nests. We determined the variation of the 28S, 18S, and 5.8S ribosomal DNA (rDNA) gene loci and the rapidly evolving internal transcribed spacers 1 and 2 (ITS1 and ITS2) of 15 sympatric and allopatric fungi associated with colonies of 11 species of leafcutter ants living up to 2,600 km apart in Brazil. We found that the fungal rDNA and ITS sequences from different species of ants were identical (or nearly identical) to each other, whereas 10 GenBank Leucoagaricus species showed higher ITS variation. Our findings suggest that Atta and Acromyrmex leafcutters living in geographic sites that are very distant from each other cultivate a single fungal species made up of closely related lineages of Leucoagaricus gongylophorus. We discuss the strikingly high similarity in the ITS1 and ITS2 regions of the Atta and Acromyrmex symbiotic L. gongylophorus studied by us, in contrast to the lower similarity displayed by their non-symbiotic counterparts. We suggest that the similarity of our L. gongylophorus isolates is an indication of the recent association of the fungus with these ants, and propose that both the intense lateral transmission of fungal material within leafcutter nests and the selection of more adapted fungal strains are involved in the homogenization of the symbiotic fungal stock.

Animals↗
PubMed2004

Immediate effectiveness of the "new identity" reality orientation therapy (ROT) for people with dementia in a geriatric day hospital.

Techniques of reality orientation in dementia are widely used around the world and indifferent settings. Nevertheless, after the controversies for adverse effects and frustration,by the new millennium "a new era" is coming on where cognitive rehabilitation "has come of age" and a series of positive results appeared until the fulfillment in the global and person-centered approach. This renewed technique may no more be based only on cognitive psychology but it is necessary to apply a more complete psychosocial approach taking into account also emotional, behavioral and functional domains of the globally considered person. The aims of our study are: (1) To assess the global efficacy on cognitive and affective functions. (2) To detect cognitive subsystems more sensible to our three-phase stimulation program. We studied 34 outpatients, 13 men and 21 women, age range 67-88 years, referred to our Expertise Center, all but one affected by mild cognitive impairment(MCI), suffering from mild dementia (clinical dementia rating, CDR <1). After 20 sessions of formal and complementary activities, a comprehensive improvement of cognition, language,memory and affective functions was observed. Semantic fluency improved with high statistically significant difference. The immediate recall, free or cued, appeared more sensible to stimulation than the delayed one. A correlation between a mini mental state examination (MMSE) low basal score and higher performance after the program was also obtained.

Aged↗
PubMed2002

Occurrence of killer yeasts in leaf-cutting ant nests.

Killer activity was screened in 99 yeast strains isolated from the nests of the leaf-cutting ant Atta sexdens against 6 standard sensitive strains, as well as against each other. Among this yeast community killer activity was widespread since 77 strains (78%) were able to kill or inhibit the growth of at least one standard strain or nest strain. Toxin production was observed in representatives of all the studied genera including Aureobasidium, Rhodotorula, Tremella and Trichosporon, whose killer activity has not yet been described.

Animals↗
PubMed1998

Metabolism of plant polysaccharides by leucoagaricus gongylophorus, the symbiotic fungus of the leaf-cutting ant atta sexdens L

Atta sexdens L. ants feed on the fungus they cultivate on cut leaves inside their nests. The fungus, Leucoagaricus gongylophorus, metabolizes plant polysaccharides, such as xylan, starch, pectin, and cellulose, mediating assimilation of these compounds by the ants. This metabolic integration may be an important part of the ant-fungus symbiosis, and it involves primarily xylan and starch, both of which support rapid fungal growth. Cellulose seems to be less important for symbiont nutrition, since it is poorly degraded and assimilated by the fungus. Pectin is rapidly degraded but slowly assimilated by L. gongylophorus, and its degradation may occur so that the fungus can more easily access other polysaccharides in the leaves.

Journal Article↗
PubMed1996

[Diagnostic possibilities and limitations of the necropsy examination on cadavers exhumed because of sudden cardiac death].

After presenting five individual cases, the authors confirm the possibility of a diagnosis of sudden cardiac death where myocardial and/or coronary arteries lesions were present, by performing an exhumed body's autopsy even after a considerable amount of time after death. With regard to this procedure, performed only by experienced consultants specializing, a particularly accurate verification is necessary.

Aged↗
PubMed1995

Cellulose degradation by Leucocoprinus gongylophorus, the fungus cultured by the leaf-cutting ant Atta sexdens rubropilosa.

Leucocoprinus gongylophorus, the fungus cultured by the leaf-cutting ant Atta sexdens rubropilosa, is able to degrade efficiently cellulose, microcrystaline cellulose, carboximethylcellulose, and cellobiose. Analysis of the degradation products indicate that the fungus produce extracellular beta-glucosidase, exo- and endo-glucanase. The importance of cellulose degradation to the association of fungus and ant is discussed.

Agaricales↗
PubMed1993

Distribution of the iron-heme displacement as resulting from myoglobin conformational substrates: an AOM approach to the interpretation of the EPR spectra.

The electron paramagnetic resonance (EPR) low-temperature spectra of high spin ferric myoglobin samples in different solvent composition have been analyzed in terms of a distribution of the energy differences delta 1 and delta 2 for the iron low-lying electronic states. The widths of these distributions, which are found to be dependent on the solvent composition, have been correlated to the presence of a frozen ensemble of conformational substrates. A dedicated analysis based on the angular overlap method (AOM) has allowed us to work out a quantitative relationship between the delta 1 and delta 2 distributions and the spread of the iron-heme displacement; this being a structural parameter relevant for the biological functionality of the protein. The observed dependence of the iron-heme displacement distribution on the solvent composition is discussed.

Animals↗
PubMed1989

UV excitable fluorescence of lumirubin.

Solutions of bilirubin in different solvents show negligible fluorescence when they are excited with UV light. After irradiation, blue-violet fluorescence (400-450 nm) is observed, whose intensity and peak position depend on the irradiation time. The isolation of pure lumirubin led us to attribute this fluorescence specifically to this photoisomer, even if small contributions from other photoproducts cannot be ruled out. The emission peak of the pure lumirubin in aqueous solution (phosphate buffer) is at 415 nm while the main excitation peak is at 315 nm. Finally, an interpretation of the observed fluorescence is proposed on the basis of the similarity of the present results with previously reported experimental data.

Bilirubin↗
PubMed1986

Chain link fence impalements in a traffic accident.

The impalement of two occupants of a car on chain link fencing during a single-vehicle accident is described. The reexamination of the survivor after 10 months is presented. The Italian Penal Code requirements are discussed regarding the examination of injured persons from the medicolegal standpoint.

Accidents, Traffic↗
PubMed1984

Procarbazine hydrochlorate carcinogenesis in Osborne-Mendel rats.

3 mg/day procarbazine hydrochlorate, in a total dose of 300 mg, provoked tumours or raised their number in a variety of rat organs and tissues. 70.8% males and 92.5% females bore tumors against 16.6 and 33% of the controls. It is suggested that the lack of a specific target organ is due to the metabolic conversion of procarbazine to alkylating agents in the liver. The chemical structure, distribution of these agents within the organism and the different organ-specific enzyme activation and inhibition systems are probably responsible for the variable organotropism.

Animals↗
PubMed1983

Induction of lung tumors and lymphomas in BALB/c mice by metronidazole.

Metronidazole, which is widely used in the treatment of "Trichomonas vaginalis", "Entamoeba histolytica" and "Giardia lamblia" infections, was administered to BALB/c mice by stomach tube in an aqueous solution at a dose rate of 2 mg/day for 100 days (total 200 mg) to test its carcinogenicity. The treatment induced a significant increase in lung tumors in male mice (p less than 0.001) and provoked the appearance of lymphomas in females (p less than 0.001). Although there is insufficient evidence to pass judgement on the potential carcinogenicity of metronidazole in man, the results of this and other investigations reported in the literature have demonstrated that metronidazole develops carcinogenic activity in rats and mice.

Animals↗
PubMed1983

Emission spectra from copper proteins containing type-3 centres.

Aqueous solutions of copper-proteins containing type-3 centres (ceruloplasmin, tyrosinase, haemocyanin), excited within their absorption bands at 325-345 nm, show typical luminescence spectra. The emission bands peak at 415-445 nm and their decay time is no longer than 10 ns. A strong analogous fluorescence is obtained also by excitation of concentrated solutions of carboxylic acids and amino acids, which show again absorption bands around 330 nm. Such a fluorescence, although less intense, is also observed in copper(II) carboxylate solutions. In contrast, no fluorescence has been recorded in solutions of acetic anhydride and of polypeptides (valinomycin, gramicidin D), which do not have free carboxyl groups. We tentatively attribute this novel fluorescence in the investigated copper proteins to interactions between carboxyl groups of amino acids at, or near, the active site.

Animals↗