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Biomedical subjects

A Magnani

Publications and source records attributed to A Magnani.

At least 19 recordsLinked to original sources
PubMed2004

Micropatterned hyaluronan surfaces promote lymphatic endothelial cell alignment and orient their growth.

The implant of a biocompatible device capable of guiding lymphatic vessel regeneration in patients who underwent removal of lymph nodes might contribute to restoring an efficient lymphatic drainage and help to prevent the occurrence of lymphedema. The aim of this study was to evaluate whether a microstructured surface could provide a guidance for the growth of cultured lymphatic endothelial cells. The presence of microstructures on a surface permits the control of cell adhesion, migration, proliferation, and differentiation. We report here that lymphatic endothelial cells align on microstructures of alternating hyaluronan and aminosylanized glass stripes obtained by photoimmobilization. Cells consistently spread and proliferate only on aminosylanized glass. They orient parallel to the longitudinal axis of the stripe. A pattern of alternating stripes of aminosylanized glass uniformly covered by elongated cells and of hyaluronan devoid of cells eventuallyforms. The presence of alpha(v)-integrins along cell borders of cells in search of contact with each other and at the leading edge of migrating cells, sites where new focal adhesions are presumably formed, indicates that integrin-mediated adhesion to the substrate guides cell migration along the microstructure. Micropatterned surfaces of hyaluronan thus proved to adequately orient the growth of cells allowing the regeneration of lymphatic endothelium in the desired direction.

Animals↗
PubMed2003

The use of hyaluronan and its sulphated derivative patterned with micrometric scale on glass substrate in melanocyte cell behaviour.

Surface microfabrication techniques were widely utilised for the spatial control of in vitro cell behaviour. A photo-immobilisation procedure was utilised to create micropatterned surfaces: four different stripe patterns (100, 50, 25 and 10 microm) of hyaluronan (Hyal) and its sulphated derivative (HyalS) on silanised glass substrate were obtained.The morphological analysis showed that the surface topography showed regular stripes of 100, 50, 25 and 10 microm wide and ranging from 300 nm up to 1 microm in thickness. They reproduced the exact photo-mask pattern: glass stripes alternating with polysaccharide ones. On the contrary, Hyal microstructures showed just a topographic pattern as the glass stripes appeared to be covered by a thin layer of the macromolecule by TOF-SIMS. Cell adhesion studies demonstrated that melanocytes adhered and oriented within the first 2h of culture on HyalS microdomains and not on Hyal microstructures where they spread on glass substrate around the patterned area. Double photo-immobilised samples characterised by a 100 microm stripe pattern of Hyal or HyalS on the top of a continuous layer of the two polysaccharides were also created in order to investigate the effect of the topography on cell behaviour. The obtained results demonstrated that melanocytes adhered on HyalS stripes while on the Hyal micropatterned surfaces they spread on silanised glass substrate around the structured area, resulting in the exclusion of the topographic pattern.

Animals↗
PubMed2002

Effect of subclinical hypothyroidism and obesity on whole-body and regional bone mineral content.

OBJECTIVE: The present investigation was aimed to evaluate the effect of subclinical hypothyroidism and obesity on bone mineral content (BMC) in different body segments. METHODS: Thirty-two premenopausal women (age: 37 +/- 9.9 years), with a wide range in body mass index (BMI), were studied. Subclinical hypothyroidism was defined by a basal TSH > or = 4 microU/l and/or a TRH-stimulated peak > or = 30 microU/l. For each subject, weight, height, BMI (weight/height(2)) and the waist/hip ratio were measured. Total BMC, total bone mineral density (BMD), leg BMC, leg BMD, trunk BMC, trunk BMD, arm BMC and arm BMD were determined using dual-energy X-ray absorptiometry. Thyroid function (basal and TRH-stimulated TSH, free T(3) and free T(4)) were determined from fasting blood samples for all subjects. RESULTS: Anova was conducted within all the groups to observe the effect of thyroid status and/or obesity on BMC and BMD. There was no statistical difference for age. Total BMC was affected by obesity (p < 0.05) but not by thyroid status, BMD of the legs was significantly influenced both by thyroid function and obesity (p < 0.01); total BMD was affected by hypothyroid status (p < 0.05). A direct relationship between leg BMD and TSH was demonstrated. CONCLUSION: Subclinical thyroid hypofunction and obesity seem to affect BMD differently in the body segments. An influence of gravitational force seems necessary in order to make evident the effect of subclinical hypothyroidism on bone. A condition of subclinical hypothyroidism should be considered when evaluating subjects for osteoporosis, since a BMD measured at the femoral neck may induce underestimation of initial osteoporosis.

Absorptiometry, Photon↗
PubMed2001

Solution structure of hyaluronic acid oligomers by experimental and theoretical NMR, and molecular dynamics simulation.

The conformational properties of hyaluronic acid (HA) oligomers in aqueous solution were investigated by combining high-resolution NMR experimental results, theoretical simulation of NMR two-dimensional (2D) spectra by Complete Relaxation Matrix Analysis (CORMA), and molecular dynamics calculations. New experimental findings recorded for the tetra- and hexasaccharides enabled the stiffness of the HA and its viscoelastic properties to be interpreted. In particular, rotating frame nuclear Overhauser effect spectroscopy spectra provided new information about the arrangement of the glycosidic linkage. From (13)C NMR relaxation the rotational correlation time (tau(c)) were determined. The tau(c) were employed in the calculation of geometrical constraints, by using the MARDIGRAS algorithm. Restrained simulated annealing and 1 ns of unrestrained molecular dynamic simulations were performed on the hexasaccharide in a box of 1215 water molecules. The beta(1 --> 3) and beta(1 --> 4) glycosidic links were found to be rigid. The lack of rotational degree of freedom is due to direct and/or water-mediated interresidue hydrogen bonding. Both single or tandem water bridges were found between carboxylate group and N-acetil group. The carboxylate group of glucuronic acid is not involved in a direct link with the amide group of N-acetyl glucosamine and this facilitated bonding between the residue and the water molecules.

Biopolymers↗
PubMed2000

Cu(II) and Zn(II) complexes with hyaluronic acid and its sulphated derivative. Effect on the motility of vascular endothelial cells.

With the aim of improving the compatibility of biomaterials to be used for the construction of cardiovascular prosthesis, we have designed bioactive macromolecules resulting from chemical modifications of hyaluronic acid (Hyal). The stability constants of Cu(II) and Zn(II) complexes with the sulphated derivative of hyaluronic acid (HyalS3.5) were evaluated. Two different complexes have been found for each metal ion, CuL, Cu(OH)2L and ZnL, Zn(OH)2L (L means the disaccharide unit of the ligands) in aqueous solution at 37 degrees C. The dihydroxo Cu(II) complex was present in high percentage at pH=7.4. On the contrary, the Zn(II) ion was present with a relatively low percentage of both complexes. The ability to stimulate endothelial cell adhesion and migration was evaluated for Hyal, HyalS3.5 and their complexes with Cu(II) and Zn(II) ions. The results revealed that Hyal and [Cu(OH)2HyalS3.5](4.5)- induced cell adhesion, while [ZnHyalS3.5](2.5)- and [Zn(OH)2HyalS3.5](4.5)- inhibited the process. The chemotactic activity of increasing concentrations of the above complexes was also evaluated, demonstrating that [Cu(OH)2HyalS3.5](4.5)- complex at 1 microM concentration was the most active in inducing cell migration. These results have been also strengthened by analysing adherent cell migration in agarose. In conclusion, sulphated hyaluronic acid coordinated to Cu(II) seems to be a promising matrix molecule for the construction of cardiovascular prosthesis.

Animals↗
PubMed2000

Immobilisation of sulphated hyaluronan for improved biocompatibility.

Hyaluronan (Hyal) was modified by the insertion of sulphate to hydroxyl groups. A series of heparin-like compounds with controllable properties was obtained. The physicochemical and biological behaviours of all these sulphated hyaluronan acids (HyalSx) and their complexes with heavy metal ions (Cu2+ and Zn2+) were investigated. HyalS, derivatives showed a good anticoagulant activity and low platelet aggregation which increased with increasing degree of sulphation. Moreover HyalSx and their Cu2+ complexes were demonstrated to favour the growth of human endothelial cells. However, the utilisation of HyalSx as a material is hindered by its high solubility in physiological solution. Our approach to improve its stability was directed to the synthesis of new HyalSx-based hydrogels and on the preparation of new biocompatible polymeric surfaces obtained through covalent photoimmobilisation of HyalSx. The reaction of primary ovine chondrocytes and B10D2 endothelial cells was studied on both matrices in terms of cell number, F-actin and CD44 receptor immunostaining. Analysis of cell movement showed that the cells respond to HyalSx showing good adhesion and spreading. These results suggest that HyalSx containing materials could be used as biomaterials to aid cartilage repair and vessel endothelisation.

Anticoagulants↗
PubMed2000

Effect of subclinical hypothyroidism on body fluid compartments.

OBJECTIVE: The present study was aimed to assess the effects of subclinical hypothyroidism on body composition (BC). SUBJECTS: Thirty-one women (age: 37 +/- 9.9 years) with a wide range of body mass index (BMI) were studied. Subclinical hypothyroidism was defined by a basal TSH > or = 4 mU/L and/or TRH stimulated peak > or = 30 mU/L. MEASUREMENTS: For each subject, weight, height, BMI, multifrequency bioelectrical impedance spectroscopy (BIS) and D2O and NaBr dilution tests were performed to assessed total body water (TBW) and extracellular water (ECW). Thyroid function (basal and TRH stimulated TSH, free T3, and free T4) were determined from fasting blood samples for all subjects. Total body dual energy X-ray absorptiometry (DXA) were used to measure fat mass (FM) and lean mass (Lean). RESULTS: The results of BIS were compared with the TBW and ECW estimated by the dilution techniques on the same individuals. The correlation was R2 = 0.65 for impedance at 5 kHz and ECW by NaBr and R2 = 0.72 for impedance at 100 kHz and TBW by D2O. Intracellular water (ICW) was calculated as differences between TBW and ECW measured by dilution methods. Percent of ECW and ICW were related to BMI (ANOVA, p < 0.001). No difference in TBW, body water distribution and body composition related to thyroid function was demonstrated. CONCLUSIONS: In our patients affected with subclinical hypothyroidism, with or without obesity, only obesity appeared related to TBW, ECW and ICW; the subclinical hypothyroidism, on the contrary, had no effect on compartments of body fluids. Bioimpedance is a valid tool to assess body fluid distribution in subclinical hypothyroidism.

Absorptiometry, Photon↗
PubMed2000

In vitro study of blood-contacting properties and effect on bacterial adhesion of a polymeric surface with immobilized heparin and sulphated hyaluronic acid.

The blood-contacting properties and the effect on bacterial adhesion of a material based on polyurethane and poly(amido-amine) (PUPA), both in its native form and with the anticoagulant molecules heparin or sulphated hyaluronic acid (HyalS3.5) electrostatically bonded to its surface, were evaluated and compared in vitro. The presence of the biological molecules on the surface was revealed by a dye test and ATR/FTIR analysis. Bound heparin was found to maintain its physiological action, in terms of thrombin inactivation, as well as did free heparin. Moreover, it reduced the degree of platelet adhesion. On the contrary, bound HyalS3.5 lost its anticoagulant activity, though it reduced platelet adhesion. The number of platelets on both modified surfaces was low. Their shape distribution, as determined by SEM, did not differ significantly on the two modified surfaces or with respect to the bare PUPA surface. HyalS3.5 and heparin also inhibited adhesion of Staphylococcus epidermidis to the material. A possible relationship between the platelet and bacterial adhesion is ascribed to the mediating role of plasma proteins.

Anticoagulants↗
PubMed1999

New biliary endoprosthesis less liable to block in biliary infections: description and in vitro studies.

OBJECTIVE: To test in vitro stents made from a new biomaterial that is less liable to encourage adhesion of bacteria that may lead to blockage of the stent. DESIGN: Laboratory experiment. SETTING: University hospital, Italy. MATERIAL: 15 polyethylene biliary endoprostheses that had been removed endoscopically a mean of 151 days (range 55416) after insertion. PUPA, a biomaterial that contains polyamidoamine cross-linked to polyurethane chains. This can bind large quantities of heparin and HyalSx (hyaluronic acid at a different stage of sulphation) in a stable fashion. MAIN OUTCOME MEASURES: Incidence of blockage and growth of pathogens in the polyethylene biliary prostheses. Adhesion of pathogens to PUPA in vitro on electron microscopy. RESULTS: 12 of 15 polyethylene prostheses were blocked by brown concretions composed of calcium bilirubinate, palmitate, and little cholesterol. All concretions grew more than one pathogen, and the growth always included Escherichia coli. Of the 5 PUPA stents tested, only 1 had bacteria sticking to their surfaces. CONCLUSION: These results confirm previous studies that showed that HyalSx appreciably inhibited the adhesion of bacteria and is therefore a suitable material for the manufacture of biliary stents.

Aged↗
PubMed1998

Influence of Sulfation on Platelet Aggregation and Activation with Differentially Sulfated Hyaluronic Acids.

A number of sulfated hyaluronic acid derivatives (HyalS(2.5), HyalS(3), and HyalS(4)) were prepared by sulfation of the -OH groups present on hyaluronic acid and were generically termed HyalS(x). The anticoagulant properties of this series of compounds has previously been shown to be good in terms of their whole blood clotting inhibition and factor Xa and thrombin inactivation. The purpose of the present study was to investigate whether the use of these compounds would be beneficial to patients who would normally be given heparin, and to perform some preliminary investigations into their effects on platelets. The three compounds were thus studied by investigating their ability to inhibit von Willebrand factor-dependent platelet agglutination in comparison with unfractionated heparin. Agglutination was determined turbidometrically after the addition of ristocetin to stirred formaldehyde-fixed platelets and was demonstrated to be dependent on the presence of sulfate groups on the polysaccharide chain and correlated with the degree of HyalS(x) sulfation. Interactions possibly important in low shear environments were investigated by measuring the pharmacological action of the HyalS(x) on spontaneous platelet activation and aggregate formation by flow cytometry. The data indicate that platelet activation is not correlated with the number of sulfate or hydroxyl groups on HyalS(x), suggesting that activation occurs not via electrostatic interactions or H bonding, but via some other mechanism. A differentiation between low and high glycosaminoglycan sulfation densities is observed with respect to platelet aggregation, which is correlated with the number of sulfated groups per disaccharide unit. The ability of HyalS(x) to inhibit platelet aggregation induced by ADP and thrombin was measured by aggregometry. HyalS(4) resisted thrombin stimulation to a similar extent as heparin. All Hyal derivatives, however, were better at inhibiting ADP-induced aggregation than was heparin. We conclude, therefore, that clinical use of HyalS(x) in place of heparin may be beneficial because ristocetin-dependent agglutination, and therefore resistance to platelet aggregation in high shear environments, in addition to resistance to stimulation by ADP, has been shown to be superior to heparin. Spontaneous platelet activation and aggregation are induced at an overall low level, even at high HyalS(x) concentrations, and are comparable with that of heparin.

Journal Article↗
PubMed1996

Blood-interaction performance of differently sulphated hyaluronic acids.

Seven differently sulphated hyaluronic acid derivatives, having a general formula HyalSx where x can be 1, 2, 2.5, 3, 3.5, 3.8, 4, were synthetized. Coagulation tests i.e. whole blood clotting time and thrombin time were performed on these compounds and significant prolongations were observed from HyalS2.5 up to HyalS4. All that means the heparin like activity increases by increasing the sulphation degree of hyaluronic acid. The interaction of each of them with thrombin and FXa was studied in order to understand the mechanism of coagulation inactivation and the role of the sulphate position in the disaccharide unit to favour the protease inhibiting reaction. The bioactivity of HyalSx in terms of FXa and thrombin inactivation increases increasing with sulphation degree but the FXa inactivation seems to be mediated by ATIII, while the aspecific electrostatic interaction seems to play an important role in the inactivation of thrombin. Also the interaction with human serum albumin was studied by ATR/FT-IR technique and no changes of protein conformation was observed, as occurs in the case of heparin.

Adsorption↗
PubMed1995

Iron release, membrane protein oxidation and erythrocyte ageing.

The aerobic incubation of erythrocytes in phosphate buffer for 24-60 h (a model of rapid in vitro ageing) induced progressive iron release and methemoglobin formation. Membrane proteins showed electrophoretic alterations and increase in carbonyl groups (as documented by IR spectroscopy). None of these phenomena were seen when the erythrocytes were incubated under anaerobic conditions. The membranes from aerobically incubated cells bound a much higher amount of autologous IgG than those from anaerobically incubated ones, suggesting that the aerobic incubation gives rise to the senescent antigen. The addition of ferrozine during the aerobic incubation prevented both the IgG binding and the protein alterations seen in the IR spectra, suggesting an intracellular chelation of the released iron by ferrozine.

Animals↗
PubMed1995

Efficacy of low-dose GnRH analogue (Buserelin) in the treatment of hirsutism.

The aim of the present study was to evaluate the effect of low dose GnRH analogue (Buserelin) on gonadal steroid secretion and hair growth in hirsute women. The drug was administered as a nasal spray (200 micrograms tid) to reduce gonadal steroid secretion. Eight hirsute women were treated for six month with the gonadotropin-releasing hormone analog. All had subclinical polycystic ovary syndromes on the basis of ultrasound or hormonal data, together with ovary dysfunctions and irregular menses. None had adrenal or pituitary dysfunction. The score of hirsutism was evaluated according to Ferriman and Gallway; pituitary function was evaluated measuring the FSH and LH response to GnRH stimulation and gonadal steroid secretion by measuring estradiol, progesterone, total plasma testosterone, androstenedione and androstanediol. Sex hormone binding globulin, insulin, prolactin and DHEA-S were also measured. The suppression of ovarian steroid secretion was confirmed by reductions in total plasma testosterone, and rostenedione and androstanediol that were detectable after one month of treatment. FSH and LH responses to GnRH stimulation were inhibited consistent with pituitary desensitization. No significant side effects were observed and all patients completed the trial. The score of hirsutism was 24 +/- 5 before, 19.6 +/- 6 by the 3rd month and 16.8 +/- 5.1 by the 6th month of treatment (p < 0.001); the effect was still evident 1 and 6 months after the withdrawal of the therapy (14.8 +/- and 15.8 +/- 5 respectively; p < 0.001). Our findings indicate that Buserelin is useful in the treatment of non adrenal hirsutism when other forms of therapy are contraindicated or poorly tolerated by the patient.

Adolescent↗
PubMed1995

Effect of toluene extraction on Biomer surface: I. ESCA, ATR/FTIR, contact angle analysis and biological properties.

Biomer is a poly(ether-urethane-urea) block copolymer widely used as biomedical devices. Extraction process of this polymer has purified its surface of low molecular weight polyurethane chains and Santowhite Powder additive. ESCA and ATR/FTIR have suggested a homogenization of the polymer by enrichment of the first layers with poly(aminomethacrylate) additive after extraction. Therefore, the surface of the extracted Biomer exhibits a different wettability and biological response. The treatment causes a significant decrease in fibronectin adsorption and induces a reduction in Staphylococcus aureus adhesion.

Adsorption↗
PubMed1995

Mayer-Rokitansky-Küster-Hauser syndrome and ovarian cancer. Report of a case.

A case of ovarian cancer associated with the Mayer-Rokitansky-Küster-Hauser syndrome is reported. As far as we know, this is the second report of ovarian neoplasm associated with this syndrome. The need for gynecological control of ovarian and other possible pathologies of the genital tract in these women is discussed.

Abnormalities, Multiple↗
PubMed1994

Conformation of human plasma proteins at polymer surfaces: the effectiveness of surface heparinization.

Studies were made on the adsorption of two human plasma proteins, albumin (HSA) and fibrinogen (HFg), onto three different polymeric surfaces: commercial pellethane 2363-80AE (PU); pellethane crosslinked with a poly(amido-amine) (PUPA); and heparinized PUPA, using in situ ATR/FTIR spectroscopy (attenuated total reflection Fourier transform infrared spectroscopy). Conformational changes were found to occur on the two proteins upon adsorption onto bare PU and PUPA, and the protein unfolding on bare PU was also found to be time dependent. On the contrary, the two proteins do not change conformation when they are adsorbed onto the heparinized surface, emphasising the effectiveness of surface heparinization.

Adsorption↗
PubMed1993

Physico-chemical surface characterization of hyaluronic acid derivatives as a new class of biomaterials.

Three hyaluronic acid derivatives with different types and/or percentages of esterification, were analyzed by means of static contact angle measurements, SEM, ESCA, ATR/FT-IR, WAXS, DSC and TGA. The physico-chemical characterization of the three different samples, in both dry and wet state, was provided in terms of surface and bulk properties. ESCA and infrared analyses showed that the surface composition of all samples differs from that of the bulk. The hydrophilic-hydrophobic character of the samples changed according to the chemical composition as shown by ESCA and contact angle measurements. Both infrared and contact angle measurements reveal that surface restructuring occurred upon hydration for all the samples and the greater the hydrophilic character of the sample, the greater and faster the restructuring phenomenon. A clear picture of the different types of chemical groups has been established at different depth for the three materials.

Biocompatible Materials↗