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Biomedical subjects

G Orsini

Publications and source records attributed to G Orsini.

At least 91 records · Page 5Linked to original sources
PubMed1975

The renaturation of reduced polyalanyl-chymotrypsinogen and chymotrypsinogen.

Chymotrypsinogen has been successfully renatured in solution, after reduction of its 5 disulfide bonds in 6 M guanidine-HCl. This has been made possible by the study of the renaturation of a model derivative, polyalanyl-chymotrypsinogen. The reduced derivative is shown to refold and reoxodize spontaneously, with a 30-40% yield, into molecules which are monomeric and fully susceptible to activation by trypsin. Chymotrypsinogen can also be renatured but only in the presence of reagents allowing disulfide interchange and of moderate concentrations of guanidine-HCl or urea. These results illustrate how the kinetic trapping of incorrectly folded molecules by wrong S-S bonds and aggregation can be overcome, thus allowing the correct refolding of the protein.

Alanine↗
PubMed1975

Renaturation of acid-denatured rabbit muscle aldolase. Existence and properties of a stable monomeric intermediate.

The effects of temperature, pH and the substrate, fructose 1,6-bisphosphate, upon the kinetics and yield of renaturation of acid-denatured rabbit muscle aldolase have been investigated. The results are discussed in terms of a sequential set of events leading from the unfolded polypeptide chain to the renatured oligomeric enzyme. One of the intermediate molecular species in this sequence has been characterized as a folded monomer with a sedimentation coefficient of 3.1 S. This monomer is shown to be much more heat-labile than the tetramer under identical conditions, thus demonstrating stabilization of the tertiary structure of the polypeptide chain by the quaternary interactions between protomers.

Animals↗
PubMed1975

A controlled study of the hypoglycemic and insulinopoietic effect of glipizide and glibenclamide in non-diabetic human subjects.

The authors studied in 12 non-diabetic women the effect on blood glucose and IRI of 2.5 mg of N-(4-[2-5-methylpyrazine-2-carboxamido)-ethyl]-benzenesulphonyl)-N'-cyclohexyl-urea (glipizide) and N-4[2-5(-chloro-2-methoxy-benzamido)-ethyl]-phenylsulphonyl-N'-cyclohexyl-urea (glibenclamide) given orally as a single dose according to a single blind crossover experimental design. After glipidide the effect on blood glucose was prompter and Immuno Reactive Insulin (IRI) levels higher. These results are in agreement with kinetic studies showing rapid and practically complete absorption of the product from the gastrointestinal tract. This fact together with the fast excretion of the drug and metabolites renders delayed hypoglycemic reactions very unlikely after administration of glipizide.

Adult↗
PubMedDate not supplied

Recombinant bacterial cells as efficient biocatalysts for the production of nucleosides.

The preparation of nucleosides as well as their base-modified analogues using purified nucleoside phosphorylase enzymes or, more conveniently, using whole bacterial cells is described. The development of genetically modified strains of Escherichia coli, able to over-produce Uridine-phosphorylase and Purine-nucleoside-phosphorylase in the same cells, improves the specific biocatalytic activity and the consequent industrial scale approach.

Escherichia coli↗
PubMedDate not supplied

Preoperative evaluation of ferritinemia in primary epithelial ovarian cancer.

AIMS AND BACKGROUND: High ferritin serum levels have been reported in patients suffering from various malignancies. The aim of this study was to evaluate the role of ferritinemia in the preoperative diagnosis of ovarian carcinoma. METHODS: Between March 1993 and September 1996, 60 patients suffering from ovarian carcinoma were surgically treated at our Department. Their ferritin serum levels were measured preoperatively by a solid-phase, two-site chemiluminescent immunometric assay and compared with those of a group of 60 healthy, age-matched, non pregnant controls. RESULTS: The mean serum concentration of ferritin was 54.7 +/- 7.8 ng/ml (range, 14-135) in healthy controls and 112.3 +/- 21.2 ng/ml (range, 9-947) in patients with ovarian carcinoma. The difference was statistically significant (P = 0.005, X2 test = 7.951). Serum ferritin was elevated preoperatively (cutoff > or = 120 ng/ml) in 18/60 patients with malignancy (sensitivity 30%), whereas the CA 125 levels were above the cutoff in 53/60 patients (sensitivity 88.3%). Only 2/60 women of the control group had ferritin titers > 120 ng/ml (specificity 96.7%). The ferritin levels increased with advancing disease stage; no significant correlation was found between ferritin concentration and neoplastic histology and grading. The mean serum iron levels were also measured preoperatively in patients with ovarian carcinoma and healthy controls. They were 57.2 +/- 3.8 and 66.3 +/- 2.61 micrograms/dl, respectively, and the difference was not significant (P = 0.655, X2 test = 0.200). CONCLUSIONS: The present study underlines that although ferritin shows an elevated specificity, its low sensitivity does not suggest any true usefulness as a tumor marker in epithelial ovarian cancer.

Adult↗
PubMedDate not supplied

Adult mesenchymal stem cells in dental research: a new approach for tissue engineering.

Many adult tissues contain a population of stem cells that have the ability to regenerate after trauma, disease or aging. Recently, there has been great interest in mesenchymal stem cells and their roles in maintaining the physiological structure of tissues. The studies on stem cells are thought to be very important and, in fact, it has been shown that this cell population can be expanded ex vivo to regenerate tissues not only of the mesenchymal lineage, such as intervertebral disc cartilage, bone and tooth-associated tissues, but also other types of tissues. Several studies have focused on the identification of odontogenic progenitors from oral tissues, and it has been shown that the mesenchymal stem cells obtained from periodontal ligament and dental pulp could have similar morphological and phenotypical features of the bone marrow mesenchymal cells. In fact a population of homogeneous human mesenchymal stem cells derived from periodontal ligament and dental pulp, and proliferating in culture with a well-spread morphology, can be recovered and characterized. Since these cells are considered as candidates for regenerative medicine, the knowledge of the cell differentiation mechanisms is imperative for the development of predictable techniques in implant dentistry, oral surgery and maxillo-facial reconstruction. Thus, future research efforts might be focused on the potential use of this cell population in tissue engineering. Further studies will be carried out to elucidate the molecular mechanisms involved in their maintenance and differentiation in vitro and in vivo.

Adult Stem Cells↗
PubMedDate not supplied

Bone reactions to anorganic bovine bone (Bio-Oss) used in sinus augmentation procedures: a histologic long-term report of 20 cases in humans.

Many materials are used for sinus augmentation procedures. Anorganic bovine bone (Bio-Oss) has been reported to be osteoconductive, and no inflammatory responses have been observed with the use of this biomaterial. One of the main questions pertaining to Bio-Oss concerns its biodegradation and substitution by host bone. Some investigators have observed rapid replacement by host bone, while other researchers observed slow resorptive activity or no resorption at all. The aim of the present study was to conduct a long-term histologic analysis of retrieved specimens in humans where Bio-Oss was used in sinus augmentation procedures. Specimens were retrieved from 20 patients after varying periods from 6 months to 4 years and were processed to obtain thin ground sections. Bio-Oss particles were surrounded for the most part by mature, compact bone. In some Haversian canals it was possible to observe small capillaries, mesenchymal cells, and osteoblasts in conjunction with new bone. No gaps were present at the interface between the Bio-Oss particles and newly formed bone. In specimens retrieved after 18 months and 4 years, it was also possible to observe the presence of osteoclasts in the process of resorbing the Bio-Oss particles and neighboring newly formed bone. Bio-Oss appears to be highly biocompatible and osteoconductive, is slowly resorbed in humans, and can be used with success as a bone substitute in maxillary sinus augmentation procedures.

Absorbable Implants↗
PubMedDate not supplied

Tissue reactions, fluids, and bacterial infiltration in implants retrieved at autopsy: a case report.

A 72-year-old patient underwent the placement of 2 screw-type implants. After 5 months the patient died of a massive stroke, and a block section of the portion of the mandible containing the implants was done. The specimen was treated to obtain thin ground sections. A 1- to 5-micron gap was present between the implant and the healing cover screw, and this space was filled by bacteria and calculus; bacteria were also present in the most apical portion of the hollow part of the implant. An inflammatory infiltrate was present in the connective peri-implant tissues. The spaces between all implant components (implant, abutment, and healing screw) can act as conduits and reservoirs for bacteria, which could cause inflammation of the peri-implant soft tissues. In conclusion, the histologic data from this autopsy case may help to confirm the penetration by fluids and bacteria into the internal portion of the implants, obtained from previous in vitro and in vivo studies.

Aged↗
PubMedDate not supplied

Surface analysis of machined versus sandblasted and acid-etched titanium implants.

Initially, implant surface analyses were performed on 10 machined implants and on 10 sandblasted and acid-etched implants. Subsequently, sandblasted and acid-etched implant cytotoxicity (using L929 mouse fibroblasts), morphologic differences between cells (osteoblast-like cells MG63) adhering to the machined implant surfaces, and cell anchorage to sandblasted and acid-etched implant surfaces were evaluated. Results indicated that acid etching with 1% hydrofluoric acid/30% nitric acid after sandblasting eliminated residual alumina particles. The average roughness (Ra) of sandblasted and acid-etched surfaces was about 2.15 microns. Cytotoxicity tests showed that sandblasted and acid-etched implants had non-cytotoxic cellular effects and appeared to be biocompatible. Scanning electron microscopic examination showed that the surface roughness produced by sandblasting and acid etching could affect cell adhesion mechanisms. Osteoblast-like cells adhering to the machined implants presented a very flat configuration, while the same cells adhering to the sandblasted and acid-etched surfaces showed an irregular morphology and many pseudopodi. These morphologic irregularities could improve initial cell anchorage, providing better osseointegration for sandblasted and acid-etched implants.

Acid Etching, Dental↗
PubMedDate not supplied

Residual and inflammatory radicular cysts. Clinical and pathological aspects of 2 cases.

Inflammatory odontogenic cysts include radicular cysts and its etiological variance, residual cysts. Among these lesions, the radicular cyst is the most frequent. It is caused by the growth of remnants of Malassez cells involved in the development of the dental organ. Clinically, radicular cysts are difficult to diagnose. Histologic diagnosis is of primary importance in order to definitely discriminate the different kinds of periapical lesions. In this paper, the clinical, radiographic, etio-physio-pathological and microscopic features of these pathological formations are described. A case of a large radicular cyst and a case of residual cyst are reported and the surgical treatment and histologic differential diagnosis are presented.

Adult↗
PubMedDate not supplied

[Stapled hemorrhoidectomy: critical observation on state of art].

The authors review pros and cons of stapled hemorrhoidectomy (SH). Postoperative primary lower than after hemorrhoidectomy, but no data are available on the long term recurrences in large prospective series. Severe postoperative complications have been reported and SH seems less effective in patients with 4th degree files. SH is a useful technique, provided that proper indication are strictly followed and the procedure is carried out by specialists.

Hemorrhoids↗
PubMedDate not supplied

[Cerebellar syndrome in a case of Kawasaki disease].

Kawasaky's disease is a multisystem widespread vasculitis. Besides the mucocutaneous patterns, symptoms related to various organs have been observed in the medical literature. Lethargy, irritability, meningism and cranial nerves paralysis occur in the acute phase of central nervous system involvement. The A.A. report a rare cerebellar syndrome caused by vasculitis in a seven years old girl's cerebellum. Surveillance of tardive complications must be undertaken in patients affected by Kawasaky's disease.

Cerebellar Diseases↗