Biomedical subjects
Publications and source records attributed to R Piccoli.
A study of the presence of opioids in invertebrates was carried out on 11 species of marine organisms, ranging from sponges to tunicates. Delipidized acid-acetone extracts from whole organisms or dissected organs were assayed by receptor binding assays and radioimmuno assays. The extracts from all species tested were found to contain substances capable of competing in both assays with opioid peptides.
Dimers of bovine pancreatic RNase A give nonhyperbolic saturation curves for the substrate of the second, rate-limiting step of the reaction. Under the same conditions, the monomeric native enzyme shows Michaelis-Menten kinetics. Naturally dimeric bovine seminal RNase, which has been found to give nonhyperbolic saturation curves, loses this property upon monomerization. It is proposed that when RNase monomers are arranged in a quaternary structure, they assume a conformation which enables them to be modulated in their catalytic activities. A correlation is suggested between this effect and the quaternary structure proposed for both of these dimeric ribonucleases, in which composite active sites are generated by the mutual exchange of the NH2-terminal ends of the two monomers.
The fine structure of bovine semen RNAase was studied with proton NMR spectroscopy making use of the four-protein system constituted by dimeric bovine semen RNAase, its catalytically active monomeric bis-(S-carboxymethyl-31,32) derivative, the naturally monomeric RNAase A from the pancrease of the same species, and dimerized RNAase A. Only four histidine C-2 H resonances were observed in the aromatic spectrum of bovine semen RNAase, which belong to the four histidine residues present in the sequence of bovine semen RNAase subunits at positions identical with those of the histidines of RNAase A. This is indicative of identical environments for the individual histidine residues in both subunits. These resonances were assigned (i) by comparing their titration curves with the corresponding curves obtained with RNAase A and with monomeric bovine semen RNAase and (ii) by evaluating the effects on their titration curves of nucleotide binding. Very similar NMR parameters were measured for His-105 and also for His-119 of seminal and pancreatic RNAase, while His-12 was found to have different environments in the two proteins. The distinctive NMR features of His-48 in bovine semen RNAase confirmed the role of the hinge regions of the subunits in maintaining the dimeric structure of the protein. While monomerization of the seminal enzyme reduced the differences between the histidine C-2 H resonances of RNAase A and bovine semen RNAase, dimerization of RNAase A did not affect the NMR spectrum of this protein, thus indicating as unlikely the possibility that the quaternary structure of bovine semen RNAase resembles that of dimerized RNAase A.
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The possibility of accidents and diseases connected with manual handling of patients can be considered as one of the major risks in hospital environments for nursing, non-nursing and technical staff. Health surveillance of exposed workers has revealed numerous cases of back disorders with consequent temporary or permanent limitations of working activity. This involves not only heavy costs for the hospital but also a reduction in the quality of the assistance due to the difficulty in replacing or increasing staff. For these reasons the hospitals of the Local Health and Social Services Unit 18 of the Regione Veneto drew up a plan of interventions in order to address this problem and reduce exposure to manual handling of patients. Details of the costs borne by the hospital due to this risk factor are reported; after the implementation of the improvement plan (health surveillance, introduction of aids, training of staff) it is shown how a reduction in costs was achieved, thus demonstrating the efficacy of the measures taken (reduction of 39.2% in days of staff absence due to back disorders).
The complications of percutaneous endoscopic gastrostomy (PEG) placement or replacement or of home management of gastrostomy, must be taken in account in patients with hydrocephalus and ventriculoperitoneal shunt. In this report we describe four children with spastic quadriplegia and ventriculoperitoneal shunt who had a median follow-up of 15 months (range 4-32 months) after PEG placement. Intravenous antibiotic prophylaxis was always used during routine procedures and no shunt infection was observed. In a patient, during accidental PEG dislodgement, peritoneal infection developed that required temporary diversion of the catheter. A second dislodgement, in the same individual, determined a large amount of serous peritoneal fluid that needed to be evacuated but no shunt infection or malfunction. In nobody of our patients, the shunt, located in the upper left abdomen, interfered with gastrostomy placement. Our experience confirms that PEG is not contraindicated in patients with ventriculoperitoneal shunt, provided that the risks of catheter infection are known and prevented.
INTRODUCTION: Undernutrition and growth retardation are often observed in children with severe neurological disabilities. Our experience of feeding gastrostomy in children and adolescents with central nervous system (CNS) disease and dysphagia is reported. PATIENTS AND METHODS: A gastrostomy feeding tube was placed in 11 children who had severe impairment of swallowing and clinically evident food aspiration. Percutaneous endoscopic technique was preferred, unless operative placement was suggested by unfavourable anatomical conditions or concomitant abdominal surgery. Commercial formulas or natural food were used at home and the children were regularly followed-up at the outpatient clinic. RESULTS: Median age at the gastrostomy placement and median follow-up lenght were 5.9 years (range 1.8-16.7 years) and 15 months (3-66 months) respectively. Four of 11 patients had moderate (weight/height (W/H) ratio = 80%) and 3 severe (W/H ratio < 70%) malnutrition. Ten of 11 subject were exclusively gastrostomy fed. After 3 months of enteral nutrition a weight gain was observed in all patients as well as a significant increase of mean W/H ratio (81.2% vs. 87.2%, p = .002). Nutritional improvement was confirmed at follow-up, despite caloric intakes lower (< 50%) than recommended for age and weight. Micronutrients and vitamins were supplemented on the basis of calculated intakes. CONCLUSIONS: In children with severe CNS disease and dysphagia, long-term gastrostomy feeding is a safe and useful method that allows adequate nutritional and micronutrient intakes and prevents the risk of dystrophy.
The antitumor action of bovine seminal ribonuclease was evaluated with a quantitative assay based on the production of tumor foci in the spleens of mice injected with plasmacytoma cells. The antitumor action depended on the integrity of the catalytic site, and on the dimeric structure of the enzyme. A working hypothesis is proposed, based on these results, and on previous results obtained studying the antitumor action of seminal RNAase in vitro on cell cultures. According to this hypothesis, the antitumor action is based on the ability of seminal RNAase to interact at specific receptor sites on the tumor cell membrane, as well as on its RNA degrading ability.
Fast and high yielding procedures for the isolation of bovine seminal RNAase are described. Homogeneous enzyme is prepared from seminal plasma in high yields in a single chromatographic step. Higher amounts (hundreds of mg) are easily prepared from seminal vesicles, a more available source of enzyme. Both procedures can be used also for the direct isolation of the isoenzymes of bovine seminal RNAase. An ultrarapid (1 hour) procedure is described for the preparation of mg amounts of pure enzyme, or of the individual isoenzymes, from seminal plasma.