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Biomedical subjects

R Piccoli

Publications and source records attributed to R Piccoli.

At least 19 recordsLinked to original sources
PubMed2006

Vaginoscopic versus traditional office hysteroscopy: a randomized controlled study.

BACKGROUND: A randomized, controlled study was performed to compare vaginoscopic versus traditional (speculum with or without tenaculum) hysteroscopy in terms of pain score and procedure time. METHODS: Three hundred patients were randomized in two groups: Group A, diagnostic hysteroscopy with vaginoscopic approach (150 patients) and Group B, diagnostic hysteroscopy with traditional approach (150 patients). All procedures were performed using a semi-rigid 3.5-mm minihysteroscope with a 0 degrees grade optic. Patients of each group were divided into three subgroups according to their reproductive status: fertile nulliparous (FN), fertile multiparous (FM) and post-menopausal (MEN) women. Women were asked to rate their degree of pain during four phases of the procedure: introduction of hysteroscope (Group A) or speculum (Group B) into the vagina (Phase I) and progression through cervical canal up to internal uterine orifice (IUO) (Phase II), inspection of uterine cavity (Phase III) and performing of endometrial biopsy (Phase IV). A total pain score was calculated for each group. For each patient, the duration of hysteroscopy was recorded from the introduction to the extraction of the scope (Group A) or of the speculum (Group B). RESULTS: Although the median total pain scores were 2 in each group, the 95% confidence interval for vaginoscopic hysteroscopy (1.86-2.01) was significantly (P < 0.05) lower than that for traditional hysteroscopy (2.10-2.26). Comparison between the corresponding phases of the procedure showed the only significant difference during Phase I of the procedure [Group A: 1 (95% CI 1.0-1.18) versus Group B: 2 (95% CI 2.3-2.8); P < 0.05]. No significant differences in terms of duration of the procedure were observed between the two approaches. CONCLUSIONS: When surgeons using vaginoscopic hysteroscopy with a semi-rigid minihysteroscope were compared with those using traditional approach and the same instrumentation, the operating times and the patients' pain scores were similar.

Adult↗
PubMed2004

A human, compact, fully functional anti-ErbB2 antibody as a novel antitumour agent.

A new human, compact antibody was engineered by fusion of a human, antitumour ErbB2-directed scFv with a human IgG1 Fc domain. Overexpression of the ErbB2 receptor is related to tumour aggressiveness and poor prognosis. This new immunoagent meets all criteria for a potential anticancer drug: it is human, hence poorly or not immunogenic; it binds selectively and with high affinity to target cells, on which it exerts an effective and selective antiproliferative action, including both antibody-dependent and complement-dependent cytotoxicity; it effectively inhibits tumour growth in vivo. Its compact molecular size should provide for an efficient tissue penetration, yet suitable to a prolonged serum half-life.

Animals↗
PubMed2004

Highly selective toxic and proapoptotic effects of two dimeric ribonucleases on thyroid cancer cells compared to the effects of doxorubicin.

The lack of selectivity of conventional antitumour drugs against cancer cells is responsible for their high toxicity. The development of new tumour-specific drugs is therefore highly needed. We tested the cytotoxic effects and the nature of cell death induced by a naturally dimeric bovine RNase and a newly engineered dimeric human RNase upon three genetically well-defined normal and malignant thyroid cell systems. RNases effects were compared with those of doxorubicin, a conventional antineoplastic drug. Our results show significant and selective proapoptotic effects exerted on tumour cells by both RNases, the strength of their cytotoxic and apoptotic activity being directly related to the degree of cell malignancy. No toxic effects were observed upon normal cells. Doxorubicin showed, instead, cytotoxic and apoptotic effects also against normal cells. The in vitro results were corroborated by the antitumour action of both dimeric RNases towards a malignant human thyroid tumour grown in nude mice. These results indicate a selective action of dimeric RNases against cancer cells and suggest the potential application of these molecules or their derivatives to the treatment of aggressive subtypes of thyroid cancer.

Animals↗
PubMed2003

Crystal structure of the dimeric unswapped form of bovine seminal ribonuclease.

Bovine seminal ribonuclease is a unique case of protein dimorphism, since it exists in two dimeric forms, with different biological and kinetic behavior, which interconvert into one another through three-dimensional swapping. Here we report the crystal structure, at 2.2 A resolution, of the unswapped form of bovine seminal ribonuclease. Besides completing the structural definition of bovine seminal ribonuclease conformational dimorphism, this study provides the structural basis to explain the dependence of the enzyme cooperative effects on its swapping state.

Animals↗
PubMed2001

Second generation antitumour human RNase: significance of its structural and functional features for the mechanism of antitumour action.

A second generation mutant of dimeric human pancreas RNase (HHP2-RNase), was obtained by a single residue mutation (Glu(111)-->Gly) of the previously described dimeric human pancreas RNase variant (HHP-RNase). HHP2-RNase was found to be a highly specific antitumour agent, with an enhanced cytotoxic activity compared with HHP-RNase. The structural and functional requisites of the antitumour action of HHP2-RNase were investigated and compared with those of other dimeric antitumour RNases. The stability of the dimeric structure, i.e. the resistance of human dimeric RNase variants to reductive cleavage of the two intersubunit disulphide bonds that bridge the subunits, was determined to be an essential feature of antitumour dimeric RNases. The stability of the dimeric structure is in turn responsible for the resistance to inhibition by the cytosolic RNase inhibitor (cRI). Both the stability of the dimeric structure and the resistance to cRI inhibition appeared to be highly enhanced by an RNase substrate. This suggests a possible role for RNA in the amplification of the antitumour potential of dimeric RNases.

Antineoplastic Agents↗
PubMed2000

Thermodynamic stability of the two isoforms of bovine seminal ribonuclease.

Bovine seminal ribonuclease (BS-RNase) is a dimeric protein with two identical subunits linked by two disulfide bridges, each subunit showing 80% of sequence identity with pancreatic RNase A. BS-RNase exists in two different quaternary conformations in solution: the MxM form, in which each subunit exchanges its alpha-helical N-terminal segment with its partner, and the M=M form with no exchange. By differential scanning microcalorimetry (DSC), the denaturation of the two dimeric forms of BS-RNase was found to be more complex than a simple two-state process. Monomeric derivatives of the dimeric protein follow instead a simple two-state mechanism, but are distinctly less stable than RNase A. The three-state N if I if D denaturation process of the two quaternary isoforms was interpreted by identifying in the dimers a central highly structured core, enclosing the covalently bonded subunit interface, which unfolds only after the periphery (mainly the N-terminal peptide) unfolds. Circular dichroism spectra of the two forms in the far-ultraviolet region show large differences between the secondary structure of the isoforms and that of the native BS-RNase mixture at equilibrium. This has been attributed to the presence in the equilibrium mixture of intermediate forms with displaced and disordered N-terminal alpha-helical segments.

Animals↗
PubMed2000

Trypsin sheds light on the singular case of seminal RNase, a dimer with two quaternary conformations.

Dimeric seminal RNase presents the singular case of a dimer with access at equilibrium to two conformations: one in which the subunits exchange, or swap, their NH(2)-terminal arms; the other with no exchange. Thus a continuous unfolding/refolding of structural elements into two alternative conformations takes place in the native protein at equilibrium. The phenomenon was investigated by kinetic and mass spectrometric analyses of the effects of trypsin on the native protein, on its isolated quaternary forms, as well as on a monomeric derivative of the protein and on homologous dimeric RNase A. The kinetics of tryptic action on the protein forms and on the protein derivatives, as well as the location of the tryptic cleavage sites, and their chronological sequence, led to the identification of relevant interconversion intermediates, to the description of a model for the interconversion process, and to a hypothesis for the unique phenomenon of the dual quaternary conformation of seminal RNase.

Animals↗
PubMed1999

A dimeric mutant of human pancreatic ribonuclease with selective cytotoxicity toward malignant cells.

Monomeric human pancreatic RNase, devoid of any biological activity other than its RNA degrading ability, was engineered into a dimeric protein with a cytotoxic action on mouse and human tumor cells, but lacking any appreciable toxicity on mouse and human normal cells. This dimeric variant of human pancreas RNase selectively sensitizes to apoptotic death cells derived from a human thyroid tumor. Because of its selectivity for tumor cells, and because of its human origin, this protein represents a potentially very attractive, novel tool for anticancer therapy.

3T3 Cells↗
PubMed1999

The role of nutrition in prevention of complications in insulin-dependent diabetes mellitus.

Nutrition management is an integral part of overall diabetic treatment that includes insulin, physical activity, emotional support and guidance. The aim of the present study was to evaluate a dietary approach in line with the recommended dietary allowances in terms of protein, total and saturated fat, carbohydrates as well as fibre and polyunsaturated fatty acid. A correct dietary approach may help to prevent and to reduce to a minimum any risk of hyperglycaemia, hypoglycaemia and important long-term complications such as obesity, hyperlipidaemia and hypertension, and at the same time normal growth development.

Adolescent↗
PubMed1998

Chimeric anti-angiogenin antibody cAb 26-2F inhibits the formation of human breast cancer xenografts in athymic mice.

Angiogenin (Ang), an inducer of neovascularization, is secreted by several types of human tumor cells and appears critical for their growth. The murine anti-Ang monoclonal antibody (mAb) 26-2F neutralizes the activities of Ang and dramatically prevents the establishment and metastatic dissemination of human tumor cell xenografts in athymic mice. However, for use clinically, the well-documented problem of the human anti-globulin antibody response known to occur with murine antibodies requires resolution. As a result, chimeric as well as totally humanized antibodies are currently being evaluated as therapeutic agents for the treatment of several pathological conditions, including malignancy. Therefore, we have constructed a chimeric mouse/human antibody based on the structure of mAb 26-2F. Complementary DNAs from the light and heavy chain variable regions of mAb 26-2F were cloned, sequenced, and genetically engineered by PCR for subcloning into expression vectors that contain human constant region sequences. Transfection of these vectors into nonproducing mouse myeloma cells resulted in the secretion of fully assembled tetrameric molecules. The chimeric antibody (cAb 26-2F) binds to Ang and inhibits its ribonucleolytic and angiogenic activities as potently as mAb 26-2F. Furthermore, the capacities of cAb 26-2F and its murine counterpart to suppress the formation of human breast cancer tumors in athymic mice are indistinguishable. Thus cAb 26-2F, with its retained neutralization capability and likely decreased immunogenicity, may be of use clinically for the treatment of human cancer and related disorders where pathological angiogenesis is a component.

Amino Acid Sequence↗
PubMed1998

Selective and asymmetric action of trypsin on the dimeric forms of seminal RNase.

Dimeric seminal RNase (BS-RNase) is an equilibrium mixture of conformationally different quaternary structures, one characterized by the interchange between subunits of their N-terminal ends (the MXM form); the other with no interchange (the M=M form). Controlled tryptic digestion of each isolated quaternary form generates, as limit digest products, folded and enzymatically active molecules, very resistant to further tryptic degradation. Electrospray mass spectrometric analyses and N-terminal sequence determinations indicate that trypsin can discriminate between the conformationally different quaternary structures of seminal RNase, and exerts a differential and asymmetric action on the two dimeric forms, depending on the original quaternary conformation of each form. The two digestion products from the MXM and the M=M dimeric forms have different structures, which are reminiscent of the original quaternary conformation of the dimers: one with interchange, the other with no interchange, of the N-terminal ends. The surprising resistance of these tryptic products to further tryptic action is explained by the persistence in each digestion product of the original intersubunit interface.

Animals↗
PubMed1998

Improvement of Pap smear sensitivity using a visual adjunctive procedure: a co-operative Italian study on speculoscopy (GISPE).

The present study evaluates whether speculoscopy, a magnified chemiluminescence examination, combined with Pap smear can improve the detection of cervical lesions, as compared with Pap smear alone. The investigation was a prospective practice-based research carried out as a multicentre cohort study throughout the Italian territory. The participants were 3,300 asymptomatic women age > or = 18 years undergoing routine pelvic and cytological screening. All participants were subjected to Pap smear, speculoscopy and colposcopy investigations in succession. The 646 women with positive colposcopy underwent biopsy. Of the 267 women with positive histology 25 were high-grade intraephitelial lesions (HGSIL) and 242 were low-grade intraephitelial lesions (LGSIL). The histological findings were correlated with the results of Pap smear and speculoscopy alone and combined (PPS). Pap smear alone detected 76% of HGSIL, speculoscopy alone identified 84% of HGSIL, and PPS indicated 100% HGSIL. Of the 242 women with LGSIL, Pap smear alone detected 37% of the cases, speculoscopy alone detected 54% of the cases, and PPS identified 91% of the cases. Together, the two tests missed 9% of the LGSIL. The combination PPS was found to increase sensitivity from 40% to 92%, but to lower specificity from 94% to 23%. Speculoscopy combined with Pap smear can yield a higher percentage of women with biopsy-confirmed cervical pathology than the use of Pap smear as a sole screening test. This is particularly true of patients with LGSIL. The mechanisms of pathological detection and the use of speculoscopy should be investigated further.

Adolescent↗
PubMed1998

Recommended dietary allowances (RDA) in the dietary management of children and adolescents with IDDM: an unfeasible target or an achievable cornerstone?

A diet in line with RDAs is seldom achieved by IDDM patients. High post-prandial glucose levels are often attributed to food excess rather than to inadequate insulin doses. Lower dietary CHO with greater fat (in particular SFA) and protein are progressively scheduled instead of increasing insulin units. We studied 194 IDDM patients (1-23 yr) on a diet conforming to RDAs with a restriction of sucrose and without a quantitative approach and exchange lists of food for one year. The diet consisted of a high intake of starchy foods and vegetables and a restricted amount of animal products. HbA1c mean values of the year were used as an indicator of metabolic control. The mean daily insulin dose was 0.53 U/kg in patients with diabetes duration (DD) < 2 yr and 0.81 U/kg in those with DD > 2 yr. Mean annual HbA1c was 7.1 +/- 0.9%. The prevalence of obesity was low (5.7%). Adolescent females were more obese than males. A dietary approach in line with RDA requirements, that may help prevent any complications related to an inappropriate diet pattern, coupled with a dynamic insulin adjustment, is the first-line intervention to prevent complications in IDDM patients.

Adolescent↗
PubMed1996

BS-RNase tetramers: an example of domain-swapped oligomers.

In the ribonuclease superfamily, dimericity is a unique feature of bovine seminal RNase (BS-RNase). In about two-thirds of native BS-RNase molecules, the two subunits interchange their N-terminal tails, thus generating domain-swapped dimers (MxM), which mostly responsible for enzyme biological activities and allostericity. Higher molecular weight BS-RNase oligomers can also be prepared [Libonati, M. (1969) Ital. J. Biochem. 18, 407-417.]. This paper reports on BS-RNase tetrameric derivatives which were isolated and enzymatically characterized. The data collected and the analysis of the crystal packing of MxM dimers suggested a structural model for tetramer assembly, in which the four subunits are enchained by multiple domain-swapping events.

Binding Sites↗
PubMed1996

Effects of protein RNase inhibitor and substrate on the quaternary structures of bovine seminal RNase.

The effect of the protein RNase inhibitor (PRI) on the activity of bovine seminal RNase (BS-RNase) was investigated using the isolated quaternary forms, MxM and M=M, of the enzyme reported earlier [Piccoli, R., et al., (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 1870-1874]. We found that the inhibitor does not interact with the intact isolated forms but has dramatic, differential effects on the two forms when the assays are performed under reducing conditions. These conditions, which are essential for full activity of the inhibitor, and are typical of its cytosolic localization, also promote monomerization of the M=M form, while under identical conditions the MxM form becomes a noncovalent dimer (NCD). The sensitivity of BS-RNase or that of the isolated quaternary forms under reducing conditions thus appears to be related to differential monomerization of the two forms of the enzyme; monomer being sensitive to PRI. The present study also shows that the interconversion between the two forms in equilibrium occurs at much higher rates in a reducing environment and that PRI further affects the interconversion and alters the equilibrium favoring monomerization of the protein. An opposite effect on the equilibrium between the forms is played by the substrate, which is found to stabilize the NCD form of the protein with a shift in the equilibrium between the two forms towards the dimer. These results are analyzed in the light of the antitumor action of the enzyme which is exerted in the cytosol, i.e., in the compartment housing the PRI and the ribosomal RNA, the molecular target of the enzyme.

Animals↗
PubMed1995

Key extracellular and intracellular steps in the antitumor action of seminal ribonuclease.

Bovine seminal ribonuclease (RNase) is a cytotoxin with a selective action toward tumor cells. We report here the results of an investigation that elucidate key extracellular and intracellular steps of the mechanism of its antitumor action. Seminal RNase is found to bind specifically to a large number of binding sites on the extracellular matrix of target cells, whereas other homologous RNases, including a monomeric derivative of the protein, do not bind. The key role of the pericellular matrix is confirmed by the finding that malignant cells grown in suspension bind negligible amounts of protein, and are resistant to its toxic effects, whereas the same cells, grown in monolayers, bind high amounts of seminal RNase and are killed by the protein. Seminal RNase is internalized by malignant cells, where it degrades rRNA and inhibits protein synthesis. These effects are not detectable when catalytically inactivated enzyme, or a catalytically active, monomeric derivative of the enzymes, are employed. The enzyme is bound and internalized also by the corresponding non-malignant cells, but no effects are detectable on RNA stability and on protein synthesis in these cells. This might be attributed to a different intracellular management in normal cells of the cytotoxic protein.

Animals↗