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Biomedical subjects

R Simoni

Publications and source records attributed to R Simoni.

17 recordsLinked to original sources
PubMed2002

Vibrational and thermal study on the in vitro and in vivo degradation of a bioabsorbable periodontal membrane: Vicryl Periodontal Mesh (Polyglactin 910).

Fourier transform Raman (FT-Raman), attenuated total reflection/Fourier transform infrared (ATR/FT-IR) spectra and differential scanning calorimetry (DSC) measurements were performed on a biodegradable periodontal membrane, the Vicryl periodontal mesh, in order to study its in vitro and in vivo degradation mechanism and kinetics. The hydrolitic in vitro degradation was investigated in two aqueous media: a saline phosphate buffer (SPB, pH=7.4) and a 0.01 M NaOH solution. Moreover, a membrane implanted in vivo for 4 weeks for treatment of contiguous vertical bony defects, was examined. Vibrational and thermal measurements show that the Vicryl membrane presents a semicrystalline structure. It degrades faster in the NaOH solution than in the SPB and degradation occurs heterogeneously with a progressive increase in the percentage of crystallinity and shortening of the polymeric chains both in vitro and in vivo. The trends of % weight loss and IR I627/I1415 intensity ratio (identified as a marker of crystallinity) are discussed in comparison with the DSC results. The IR I627/I1415 intensity ratio and Xc% allow to determine the % weight loss undergone by the membrane degraded in vivo. The result obtained shows that the Vicryl membrane degrades faster in vivo than in vitro with the formation of oligomers which are more easily absorbed by the surrounding tissues than they are soluble in the degradation media examined.

Journal Article↗
PubMed2002

Vibrational and thermal study on the in vitro and in vivo degradation of a poly(lactic acid)-based bioabsorbable periodontal membrane.

Fourier transform Raman (FT-Raman), attenuated total reflection/Fourier transform infrared (ATR/FT-IR) spectra and differential scanning calorimetry (DSC) measurements were performed on a poly(lactic acid)-based biodegradable periodontal membrane in order to study its in vitro and in vivo degradation mechanism and kinetics. For this purpose, the hydrolitic in vitro degradation of the membrane was investigated in two aqueous media: saline phosphate buffer (SPB, pH=7.4) and 0.01 M NaOH solution. Moreover, a membrane implanted in vivo for four weeks for treatment of contiguous vertical bony defects, was examined. Vibrational and thermal measurements show that the membrane has a prevalently amorphous structure and is composed of low molecular weight polymeric chains. The degradation is faster in NaOH solution than in SPB and occurs heterogeneously without any significative increase in crystallinity. The DSC and spectroscopic measurements are discussed in comparison with the trend of % weight loss and show a progressive decrease in molecular weight. Regarding the Raman analysis, the I(875)/I(1452) intensity ratio was identified as a marker of the degree of degradation. Regarding the in vivo degradation, the presence, spectroscopically revealed, of a biological component entrapped in the membrane proves the good integration of the membrane with the surrounding tissues. The membrane seems to degrade faster in vivo than in vitro. A comparison with the degradation mechanism and kinetics of a periodontal membrane previously studied, Vicryl periodontal mesh, is made.

Journal Article↗
PubMed2001

Influence of environment on piroxicam polymorphism: vibrational spectroscopic study.

FTIR and FT-Raman spectroscopies were used to evaluate the mechanism of transformation of piroxicam into its different forms (alpha, beta, and monohydrate), depending on the environment. These vibrational techniques allowed us to identify the forms of piroxicam that crystallize from different solvents at different cooling rates and the conformation of the drug in some of its derivatives: piroxicam hydrochloride, piroxicam thallium and sodium salt hemihydrates, and piroxicam sodium salt. The usefulness of Raman spectroscopy in characterizing piroxicam:beta-cyclodextrin (PbetaCD) inclusion compounds was described. The Raman spectrum of 1:2 PbetaCD was discussed in comparison with that of the corresponding piroxicam sodium salt containing inclusion compound (1:2 PNabetaCD) in order to study the influence of the piroxicam derivative used on the structure of the inclusion compound. The Raman results showed that in both of the inclusion compounds the piroxicam mainly assumes the zwitterionic structure typical of a monohydrate; therefore, the kind of derivative used does not affect the conformation of the drug in its inclusion compound. The effect of the method of synthesis utilized (freeze-drying or freeze-thaw cycling) to obtain 1:2.5 PbetaCD was investigated. The inclusion compound obtained by freeze-thaw cycling proved to be more crystalline and to contain a higher amount of the beta form than the freeze-dried inclusion compound. Raman spectroscopy proved to be a useful technique for evaluating the effectiveness of the manufacturing process in relation to the pharmaceutical properties of the drug and to the nondestructive and noninvasive on-line quality control of the industrial products.

Cyclodextrins↗
PubMed2000

Gemcitabine treatment in pretreated cutaneous T-cell lymphoma: experience in 44 patients.

PURPOSE: To evaluate the efficacy and toxicity of gemcitabine, a novel pyrimidine antimetabolite with a low-toxicity profile and activity in several solid tumors, in patients with relapsed or refractory cutaneous T-cell lymphomas. PATIENTS AND METHODS: Between May 1997 and February 1999, 44 previously treated patients with mycosis fungoides (MF; n = 30) and peripheral T-cell lymphoma unspecified (PTCLU) with exclusive skin involvement (n = 14) were enrolled onto a two-institution, phase II trial and treated with gemcitabine. This drug was given on days 1, 8, and 15 of a 28-day schedule at a dose of 1,200 mg/m(2) intravenously over 30 minutes for a total of three courses. RESULTS: Of the 44 patients, five (11. 5%) achieved complete responses (CRs), 26 (59%) partial responses (PRs), and the remaining 13 showed no benefit from the treatment. Two of the CRs were histologically confirmed. The CR and PR rates were the same for patients with MF and those with PTCLU, respectively. No difference in terms of overall response rate was observed between relapsed and refractory patients. The median durations of CR and PR were 15 months (range, 6 to 22 months) and 10 months (range, 2 to 15 months), respectively. Treatment was well tolerated; hematologic toxicity was mild, and no nausea/vomiting or organ toxicity was recorded. CONCLUSION: The results of the present phase II study show activity of gemcitabine as a single agent in patients with pretreated cutaneous T-cell lymphoma. Further studies that use gemcitabine alone or in combination with other drugs in earlier stages of the disease are needed.

Adult↗
PubMed1999

Hydroa vacciniforme persistent in a 60-year-old man.

Hydroa vacciniforme (HV) is an idiopathic photodermatosis with onset in childhood, a chronic-recurrent course, and spontaneous resolution in adolescence or early adulthood. We present a patient with typical HV in whom lesions began in childhood and continued until 60 years of age.

Chronic Disease↗
PubMed1998

Applications of Raman spectroscopy to ophthalmology: spectroscopic characterization of disposable soft contact lenses.

Disposable soft contact lenses based on HEMA-MAA hydrogels are examined using Raman and ATR/FTIR vibrational spectroscopies and thermal analysis. The main factors dealing with physical, chemical, and biological biocompatibility are evaluated in relation to those of long-wear soft contact lenses with the aim of individuating the most biocompatible lens. The Raman spectra of HEMA-MAA lenses show that some biocompatibility factors are affected by environmental conditions and, in particular, by changes in pH and ionic strength values.

Biocompatible Materials↗
PubMed1996

Minimally differentiated acute myeloid leukaemia revealed by specific cutaneous lesions.

Minimally differentiated acute myeloid leukaemia (AML-MO) is a poorly differentiated type of acute myeloid leukaemia. Its myeloid differentiation can only be demonstrated by the immunohistochemical or ultrastructural finding of cytoplasmic myeloperoxidase in bone marrow blasts and/or by the immunohistochemical expression of at least one lineage-specific myeloid antigen, with no reactivity for lymphoid antigens. We describe a man with a cutaneous nodular eruption that represented the first clinical manifestation of AML-MO. Histological examination showed extensive proliferation of blasts with scant basophilic cytoplasm. Immunohistochemically, these expressed neither myeloid nor lymphoid-specific antigens, whereas they were focally positive for CD45. The diagnosis of AML-MO was confirmed by immunophenotypic analysis of a bone marrow smear. A complete remission was achieved following parenteral steroid therapy. The disease relapsed some months later, and the patient died within a few weeks.

Acute Disease↗
PubMed1992

Raman spectroscopy in the study of biocompatibility.

This review deals with the application of Raman spectroscopy to the study of the biocompatibility of orthopaedic and ophthalmological materials and includes an introduction, a brief theory on the fundamental concepts of the technique, a description of the method and of the traditional and non-traditional instrumentation and a brief treatment of the surface properties of the different classes of materials. In the orthopaedic field, Raman studies on the structures of glasses, ceramic materials, carbon fibres and polymers before and after implantation are reviewed, particularly as far as structural modifications at the biomaterial-tissues interface are concerned. In the ophthalmological field, the chemical biocompatibility of hydrophobic and hydrophilic polymers for intraocular and intrastromal implants and for soft contact lenses is considered with respect to the presence of monomeric reactive centres in hydrophobic materials and the water amount in hydrophilic ones. The progress of the multichannel Raman technique for 'in-vivo' measurements is also described.

Biocompatible Materials↗
PubMed1991

Calcium phosphate materials containing alumina: Raman spectroscopical, histological, and ultrastructural study.

Variable alumina quantities were added to two types of calcium phosphate materials-hydroxyapatite ceramics with Ca/P = 1.67 and calcium metaphosphate glass with Ca/P = 1--in order to increase their mechanical properties. Raman spectroscopy shows that alumina interacts with the phosphate group of these materials, while thermomechanical analysis shows that their elastic modulus has a value similar to that of bone. Histological sections demonstrate that the surface in close contact with ceramic materials shows a good integration between bone and biomaterial. All ceramic specimens are penetrated by well-stained, presumably glycoprotein, matrix, that consistently forms a thin network in close contact with the implant. After 6 weeks bone growing on both ceramic and glass shows signs of maturation with a lamellar structure and an apparently normal mineralization. In the case of the glass, inside this newly formed bone, were often observed two layers, the internal one showing a well defined lamellar structure.

Aluminum Oxide↗
PubMed1991

Is interferon alpha in cutaneous T-cell lymphoma a treatment of choice?

This study was designed to evaluate the therapeutic efficacy and toxicity of recombinant interferon alpha-2a (rIFN alfa-2a) given as initial systemic therapy in untreated mycosis fungoides and/or Sezary's syndrome patients, at a slowly escalating schedule up to the maximal tolerated dose. At the same time this schedule was administered in patients who had relapsed or were refractory to previous treatment; 28 newly diagnosed and 15 previously treated patients entered the study. IFN was given daily with dose escalation from 3 to 18 MU. The last follow-up in June 1990 indicates that 90% of previously untreated patients who obtained a complete remission remain in continuous complete remission after 18 to 40 months and that 75% of previously untreated patients who obtained partial remission remain in partial remission after 20-44 months. The event-free survival projected, calculated using the Kaplan and Meier product limit technique, was 21% of all patients at 54.7 months (40% in the previously untreated groups and 14% in the previously treated group: P = 0.12). In conclusion, interferon is very effective as a single agent in cutaneous T-cell lymphomas.

Adult↗
PubMed1990

Interferon alpha-2a in cutaneous T-cell lymphoma.

23 newly diagnosed patients affected by cutaneous T-cell lymphoma were treated with sub-cutaneous interferon alpha-2a to evaluate the therapeutic efficacy and the toxicity of this agent. IFN was administered daily with dose escalation from 3 to 18 million units for 12 weeks; thereafter, patients induced into complete (CR) or partial (PR) remission were given IFN at maximal tolerated dose 3 times weekly for 6 or 9 months. The objective tumor response was observed in 17 patients (74%): 8 (35%) were CR and 9 (39%) were PR. A 74-yr-old patient died because of neutropenia and sepsis at the end of induction phase, while receiving IFN at dose of 18 million units. Disease stage is the initial feature predictive of response to IFN therapy. The dose schedule of this study was well tolerated: only 3 patients developed liver toxicity, while leukopenia was evident in 6 patients. Only 2 CR patients have relapsed, 18 and 24 months from response; the remaining 6 CR patients are in continuous complete remission with a median follow-up of 41.8 months. 6 PR patients have progressed from 8 to 17 months after response, and in the 3 PR patients not yet progressed the response duration ranges from 20 to 24 months. In conclusion, interferon alpha-2a is a very effective agent in therapy of untreated cutaneous T-cell lymphoma with an overall response rate of 74%.

Adult↗
PubMed1985

Epithelioid sarcoma.

Epithelioid sarcoma is a rare malignant tumor of the soft tissues with particular clinical and anatomicopathological characteristics. Histologically it is characterized by the presence of particular epithelioid cells. After a description of a recently observed case, the authors present a synthesis of the literature on the subject, paying particular attention to the clinical and histological aspects which facilitate an early and correct diagnosis.

Adolescent↗
PubMedDate not supplied

Recombinant leukocyte interferon alfa-2a in the treatment of mycosis fungoides.

This study was designed to evaluate the efficacy and tolerability of recombinant leukocyte interferon alfa-2a (Hoffmann-LaRoche) as single agent in patients with histologically confirmed Mycosis Fungoides. The protocol consisted of a 12 week induction with subcutaneous interferon, escalating from 3 up to 18 million units daily, and a 6 or 9 month maintenance phase for complete or partial responses, respectively, with 18 million units 3 times weekly. 12 patients are evaluable: 5 are in complete remissions, 6 are partial remissions, and one had disease progression. Alfa-2a interferon was well tolerated: only 3 patients had WHO grade IV organ toxicity. Our study documents that recombinant leukocyte alfa 2a is a highly active agent in untreated patients with Mycosis Fungoides. Finally, the dose schedule chosen in this study allows alfa-2a interferon administration on an outpatient basis.

Adult↗