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Biomedical subjects

M Bozzi

Publications and source records attributed to M Bozzi.

At least 19 recordsLinked to original sources
PubMed2001

Spectroscopic and molecular dynamics simulation studies of the interaction of insulin with glucose.

The interaction between monomeric insulin and monosaccharides has been investigated through circular dichroism, fluorescence spectroscopy and two dimensional nuclear magnetic resonance. CD spectra indicate that D-glucose interacts with monomeric insulin whereas D-galactose, D-mannose and 2-deoxy-D-glucose have a lower effect. Fluorescence emission was quenched at sugar concentrations of 5-10 mM. Titration with the different sugars produces a quenching of the tyrosine spectrum from which a binding free energy value for the insulin-sugar complexes has been evaluated. Transfer nuclear Overhauser enhancement NMR experiments indicate the existence of dipolar interactions at short interatomic distances between C-1 proton of D-glucose in the beta form and the monomeric insulin. Further, NMR total correlation spectra experiments revealed that the hormone is in the monomeric form and that upon addition of glucose no aggregation occurs. The interaction does not involve relevant changes in the secondary structure of insulin suggesting that the interaction occur at the side chain level. Molecular dynamics simulations and modeling studies, based on the dynamic fluctuations of potential binding moiety sidechains, argued from results of NMR spectroscopy, provide additional informations to locate the putative binding sites of D-glucose to insulin.

Binding Sites↗
PubMed2001

Unfolding and inactivation of monomeric superoxide dismutase from E. coli by SDS.

The inactivation and the unfolding of the naturally monomeric Cu, Zn, superoxide dismutase from E. coli upon addition of sodium dodecylsulphate have been studied. In contrast to the bovine enzyme, CD, EPR, NMR spectroscopy and pulsed low resolution NMR measurements found an unfolding transition followed by inactivation of the enzyme. During this transition the active site becomes accessible to the bulk water. The unfolding is reversible and both, the tridimensional structure of the protein and the active site, can be restored upon dialysis. In addition, unfolding occurs without loss of metals in the solution.

Animals↗
PubMed2001

A synthetic peptide corresponding to the 550-585 region of alpha-dystroglycan binds beta-dystroglycan as revealed by NMR spectroscopy.

We have probed the binding of a synthetic peptide corresponding to the region 550-585 of the alpha subunit of dystroglycan with a recombinant protein fragment corresponding to the N-terminal extracellular region of beta-dystroglycan (654-750), using NMR in solution. In a 30:1 molar ratio, the peptide binds to the recombinant protein fragment in the fast/intermediate exchange regime. By monitoring the peptide intra-residue HN-Halpha peak volumes of the 2D TOCSY NMR spectra, both in the absence and in the presence of the recombinant fragment, we determined the differential binding affinities of each amino acid. We found that the residues in the region 550-565 (SWVQFNSNSQLMYGLP) are more influenced by the presence of the protein, whereas the C-terminal portion is marginally involved. These NMR results have been confirmed by solid-phase binding assays.

Amino Acid Motifs↗
PubMed2001

Plasticity of secondary structure in the N-terminal region of beta-dystroglycan.

The secondary structure content of the N-terminal extracellular domain of beta-dystroglycan (a recombinant fragment extending from positions 654 to 750) has been quantitatively determined by means of CD and FTIR spectroscopies. The elements of secondary structure, namely an 8-10 residue long alpha-helix (10%) and two beta-strands (24%) have been assigned to specific amino acid sequences by means of a GOR constrained prediction method. The remaining 66% of the whole sequence is classified as turns or unordered. The temperature dependence of CD and FTIR spectra has been investigated in detail. A reversible, non-cooperative thermal transition is observed with both CD and FTIR spectroscopies up to 95 degrees C. The profile of the transition is typical of the unfolding of isolated peptides and corresponds to the progressive loss of the secondary structure elements of the protein with no evidence for collapsing phenomena, typical of globular proteins, upon heating.

Amino Acid Sequence↗
PubMed2000

Investigation of the active site of Escherichia coli Cu,Zn superoxide dismutase reveals the absence of the copper-coordinated water molecule. is the water molecule really necessary for the enzymatic mechanism?

The active site of the Cu,Zn superoxide dismutase from Escherichia coli in the oxidized Cu(II) state has been studied by nuclear magnetic relaxation dispersion (NMRD), optical and nuclear magnetic resonance spectroscopy. The orientation of some metal ligands is different with respect to all the other Cu,Zn superoxide dismutases. Moreover, NMRD measurements demonstrate the lack of a copper-coordinated water molecule. In spite of these differences the enzymatic activity is still high. Azide also binds copper with normal affinity and induces modifications in the active site comparable to those previously observed in the eukaryotic enzymes. Our results suggest that, in this enzyme, the copper-coordinated water molecule appears not necessary for the enzymatic reaction. A role for the copper-coordinated water molecule is discussed in the light of recent crystallographic studies.

Binding Sites↗
PubMed1997

A novel non-heme iron-binding ferritin related to the DNA-binding proteins of the Dps family in Listeria innocua.

A multimeric protein that behaves functionally as an authentic ferritin has been isolated from the Gram-positive bacterium Listeria innocua. The purified protein has a molecular mass of about 240,000 Da and is composed of a single type of subunit (18,000 Da). L. innocua ferritin is able to oxidize and sequester about 500 iron atoms inside the protein cage. The primary structure reveals a high similarity to the DNA-binding proteins designated Dps. Among the proven ferritins, the most similar sequences are those of mammalian L chains that appear to share with L. innocua ferritin the negatively charged amino acids corresponding to the iron nucleation site. In L. innocua ferritin, an additional aspartyl residue may provide a strong complexing capacity that renders the iron oxidation and incorporation processes extremely efficient. This study provides the first experimental evidence for the existence of a non-heme bacterial ferritin that is related to Dps proteins, a finding that lends support to the recent suggestion of a common evolutionary origin of these two protein families.

Amino Acid Sequence↗
PubMed1996

[Correlation between risk factors and bone mass in pre- and postmenopause. Epidemiologic study on osteoporosis (Part one)].

The recent development of highly accurate and precise osseous mass quantitative evaluation methodology, permits the conduction, in the sphere of osteoporosis, of epidemiologic investigations no longer limited solely to fracture complications but also based on the definition of osseous mass. Fractures being only complications, possible but not certain, of the advanced stages of the diseases, the studies based on their incidence allow one to underestimate the global entity of prevalence and incidence, besides building only a partially useful reference in view of primary and secondary prevention. The main points of our study are the following: 1) evaluation of the incidence of the primary risk factors for osteoporosis as they appear in the literature, on the bone mass values of examined subjects, utilizing tatic mineralometric data as a reference standard; 2) study of biohumoral data relative to phospho-calcium metabolism and to sexual function, to show the possibility of their use as early identifying markers of subjects at risk; references values represented by dynamic mineralometric data. The principal conclusions that emerged int he course of the study are the following. In regard to the evaluation of the principal risk factors, they prove to be correlated to the osseous mass values registered at the first control: physical activity (highly positive action). Favorable levels of correlation were also discovered for the variables of increased body weight (positive action) and increased age (negative action). In multivariate analysis, the R-square value (index of the variation fraction of osseous mass values due to the risk factors) has reached a total value of 0.65 (physical) activity: 0.46; physical activity + dietary calcium: 0.55; history + increased age: 0.58; history + smoking: 0.62; history + increased weight: 0.64; history + pre- or post-menopausal: (0.65). Such analysis furnishes useful indications on the modalities to employ in the anamnestic framing of the patients at risk for osteoporosis, and on the importance attributable to single risk factors.

Adult↗
PubMed1996

[Changes in phospho-calcium metabolic factors in function of the rate of bone turnover. Epidemiologic study of osteoporosis (part 2)].

BACKGROUND: The recent development of highly accurate and precise osseous mass quantitative evaluation methodology, permits the conduction, in the sphere of osteoporosis, of epidemiologic investigations no longer limited solely to fracture complications, but also based on the definition of osseous mass. Fractures being only complications, possible but not certain, of the advanced stages of the disease, the studies based on their incidence allow one to underestimate the global entity of prevalence and incidence, besides building only a partially useful reference in view of primary and secondary prevention. METHODS: The main points of our study are the following: 1) evaluation of the incidence of the primary risk factors for osteoporosis as they appear in the literature, on the bone mass values of examined subjects, utilizing static mineralometric data as a reference standard; 2) study of biohumoral data relative to phospho-calcium metabolism and to sexual function, to show the possibility of their use as early identifying markers of subjects at risk; reference values represented by dynamic mineralometric data. The principal conclusions that emerged in the course of the study are the following. RESULTS: In relation to the use of phospho-calcium metabolic biohumoral and hormonal variables, as a predictive function on the variations of bone turnover, the variables; osteocalcin, alkaline phosphatase, alkaline phosphatase bone isoenzyme, hydroxyprolinuria/ creatininuria, have resulted significantly different in the comparison between high and low turnover subjects. The degree of quantitative correlation of such variables with the entity of percentage decrement of bone mass has been modest. The overall value of R-square of the predictive model, besides the variables mentioned the value of bone mass at 1 degree control visit, was 0.38 (osteocalcin: 0.27; osteocalcin+hydroxyprolinuria/ creatininuria: 0.33; preceding variables+bone mass at 1st control: 0.36; preceding variables+alkaline phosphatase: 0.37; preceding variables+alkaline phosphatase bone isoenzyme: 0.38). CONCLUSIONS: The single value osteocalcin may furnish indications on the future variations of bone turnover and consequently on the early identification of the subjects at risk for osteoporosis at high turnover; the addition of the other variables indicated in our predictive model allows an increase of the possibilities of individualizing of these subjects.

Adult↗
PubMed1995

[Medium- and long-term effects of various treatment schedules with nasal S-calcitonin spray].

188 patients with high-turnover type post-menopausal osteoporosis were treated for 18 months with 4 different treatment regimens of S-calcitonin nasal spray. For a total of 18 months group 1 was given 100 IU/day, continuously; group 2, 100 IU/day daily for 30 days every other month ("ciclically"); group 3, 200 IU/day continuously, and group 4, 200 IU/day, ciclically. To monitor the effects of treatment, MOC of L2-L4, as well as serum osteocalcin and urinary hydroxyproline: creatinine levels were measured, on initiation of therapy, then at 9, 12 and 18 months, and finally at 6 and 12 months after completion of therapy. Analysis of the results yields the following major points: (A) The peak increase in bone mass occurs at 9 months the continuous therapy groups, and at 18 months in the cyclic therapy groups. In absolute values, the peak are higher in the continuous groups than in the cyclic groups. (B) The long-term increase in bone mass (measured at one year after completion of therapy) does not differ significantly between cyclic and continuous treatment groups at the same dosage. (C) During treatment, a dose-effect relationship exist when comparing dosages of 100 IU/day and 200 IU/day. However, this disappears by one year after completion of therapy. (D) There seems to be a "rebound effect" on osseous turnover after cessation of S-calcitonin therapy. The magnitude and rapidity of onset of this effect appear to correlate directly with the dosage of S-calcitonin administered.

Calcitonin↗
PubMed1991

Effects of metoxibutropate, ibuprofen and guaiacol on the gastrointestinal system.

In previous studies we have shown that ibuprofen, guaiacol and the guaiacol ester of ibuprofen (I.N.N. metoxibutropate) are able to inhibit in-vitro prostaglandin synthesis. In the present study we have evaluated the effect of ibuprofen, guaiacol and metoxibutropate on the gastrointestinal system. Oral treatment with equimolar increasing doses of the three drugs produced a progressive inhibition of prostaglandin biosynthesis in the intestinal tract, without any effect on the rate of intestinal propulsion. Further studies evaluated the gastric tolerance of a molar dose of ibuprofen causing ulceration in 50% of the animals. After single and repeated administration of guaiacol and of the guaiacol ester of ibuprofen, the percentage of animals with gastric damage was very low and the index of ulceration seemed rather moderate. Our results show that although guaiacol is able to inhibit prostaglandin biosynthesis like a classic NSAID, it does not induce gastric damage. For these reasons it is justified to combine guaiacol with ibuprofen in order to reduce gastric erosions induced by a classic antiinflammatory drug.

Animals↗
PubMed1990

[Argon laser in dermatology: indications suggested by a 4-year experience].

The Argon laser has been used in the treatment of port wine stains, telangiectasias, spider ectasias, ruby spots, venous lakes, pyogenic granulomas, tattoos, keloids, verrucous naevus, angiokeratomas, verrucous hemangiomas. The outcome results have been compared with those achievable using other treatments in order to give right indications to the use of the Argon laser. The comparison point out that Argon laser is the treatment of choice only in port wine stains, while in all the other diseases it doesn't give any advantage with regard to conventional therapies, less sophisticated, easier and sometime more effective.

Adolescent↗
PubMed1989

Verrucous hemangioma and angiokeratoma circumscriptum: clinical and histologic differential characteristics.

It is important, from a prognostic and therapeutic point of view, to make a correct diagnosis between verrucous hemangioma (VH) and angiokeratoma circumscriptum. The former needs a large and deep exeresis, while the latter responds to the common means of physical therapy. Two cases of verrucous hemangioma are reported that have allowed us to review the clinical and histologic differential characteristics of the two forms.

Adolescent↗
PubMed1985

Changes in sympathetic activity during high frequency T.E.N.S.

Recent studies have clarified some of the relationship between the autonomic nervous system and causalgic pain, but much is not known about the nature of pain. It is known that TENS may help to alleviate the chronic pain resulting from peripheral nerve lesions, and various beneficial results are usually ascribed to subjects who have pain. Our own study measured various parameters before and after TENS in healthy subjects, and these findings contrasted markedly with the results attributed to TENS in subjects suffering from pain. This raises interesting questions about the nature of TENS as a pain control.

Adult↗
PubMedDate not supplied

[HLA and keloids: antigenic frequency and therapeutic response].

Twenty keloid subjects were typed for class 1 (HLA-A, B and C) and class 2 (HLA-DR and DQ) histocompatibility antigens. Their frequencies were compared to those found in control populations. Of all the antigens belonging to class 1, B 21 was more prevalent in patients. The findings regarding class 2 antigens were noteworthy: in keloid patients there was a significant prevalence of DR 5 (RR = 3.54 and 7.93 respectively for the two control groups) and DQw 3 (RR = 16.8). The patients typed for HLA-antigens were treated with corticosteroid infiltrations. The responses to the treatments were no related to the histocompatibility antigens.

Adrenal Cortex Hormones↗