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Biomedical subjects

R Mongiorgi

Publications and source records attributed to R Mongiorgi.

At least 37 records · Page 2Linked to original sources
PubMed1993

Osteoporosis by ovariectomy: calcitonin effect in an experimental model on the rat.

The authors evaluate the efficacy of the aminosuberic derivative of eel calcitonin (eCT) in preventing post-ovariectomy osteoporosis in adult rats. The drug is administered in a dose of 0.5 U.I./day for four months starting from the moment of the ovariectomy. The results show that the treatment is efficacious in preventing bone mass loss due to ovariectomy and that the action of the drug does not bring about alterations in the normal crystalline structure of the bone.

Alkaline Phosphatase↗
PubMed1993

Scanning electron microscopy, chemical and histologic analysis in human periarthritic shoulder biopsy.

In the present study biopsies were analyzed, taken from the left shoulder of a patient who, according to the radiological diagnosis, was suffering from calcific periarthritis. In both optical and electronic microscopy the mineralogical observations showed crystalline aggregations, while the chemical analysis, carried out with an Edax EDS spectrophotometer, confirmed the presence of Ca and P in them, in the ratio typical of biological apatites. The histological observations clearly indicate a change in the metabolism of the tissues present. In the samples observed the damage to the muscular tissues is easily seen while the connective tissue, though apparently less compromised, shows the presence of numerous calcifications whose damage cannot be revealed solely through histologic observations. The authors, linking the structural histologic alterations observed to the presence of hydroxyapatite granules as well as to the patient's painful symptoms, believe all these observations are the result of a chronic process.

Adult↗
PubMed1992

SEM and chemical micro-analysis in a failed total knee prosthesis.

Authors performed SEM and EDS analyses in a cemented removed knee prosthesis demonstrating the average values of mineral elements in the bone surrounding the prosthesis. The composition of the metallic prosthesis surface in different microareas was also studied.

Alloys↗
PubMed1992

Calcium oxalate smear layer: mineralogical and crystallographic study.

Different methods to reduce dentine hypersensitivity have been tested by means of oxalate treatments. Natural material (20 teeth) and commercial oxalates have been employed. As a result the dentinal tubules are filled by small crystals preventing dental disease. Permeability measurements have been performed in order to quantify results. The composition of the synthetic smear layer produced after oxalate treatment have been investigated by powder diffraction method suggesting calcium oxalate formation.

Calcium Oxalate↗
PubMed1991

Further observations on pineal brain sand formation and evolution in man.

Acervuli obtained from fragments of the human pineal glands of subjects of both sexes and age ranging from 23 to 87 years were analyzed by light microscopy after histochemical stains and by EDS-microanalysis. It was found that the sub-units and acervuli are positive to P.A.S., Alcian Blue pH 2.5, Gomori-Bargmann procedures for the presence of proteins, glycoproteins, proteoglycans and of the neurosecretory material in different layers of the sub-units and acervuli. We suppose that the increase of Mg++ in the sub-unit from the core to the periphery is responsible for the inhibition of following hydroxyapatite deposition and for growth. We suggest that the presence of glycoproteins and proteoglycans can represent the aggregation factor for bindings between disulphide bonds and calcium.

Adult↗
PubMed1991

Oxalate solution and collagen-oxalate solution as protective liners for dentine.

The aim of the present study was to evaluate under scanning electron microscopy the ability of different chemically reactive solutions to form a protective layer on dentine. The materials selected were an oxalate solution, a collagen-oxalate solution, a collagen-oxalate solution plus glutaraldehyde and a saline control solution. Small dentine fragments, obtained from extracted human teeth, were treated with the various chemical solution for 60 seconds. All samples were then examined in a Jeol scanning electron microscope. The preliminary observations suggest that dentine may be covered by a mixture of oxalate crystals and collagen producing a homogeneous layer of reactive agents.

Collagen↗
PubMed1991

Scanning electron microscopy and dentinal permeability analysis of smear layer.

The aim of the present study was to evaluate the surface morphology and the permeability of dentine after different acid treatments: polyacrylic acid, maleic acid, phosphoric acid and saline solution as control. Dentine permeability was expressed as hydraulic conductance. All the acid treatments removed the smear layer and increased the dentine permeability.

Acid Etching, Dental↗
PubMed1991

Microleakage in composite resin restorations.

The aim of the present study was to evaluate the marginal microleakage of the newest generation of composite resin restorative materials. Class V restorations were prepared in human extracted teeth. Different combinations of restorative materials were used. All the materials tested showed marginal microleakage along the dentinal walls, suggesting that the adhesion value is not sufficient to counteract the composite shrinkage and to reduce the marginal space.

Adult↗
PubMed1991

Oxalate desensitising treatment of dentinal surface.

It is well known that a typical painful feeling is caused by impact of different agents and by thermodynamic conditions upon the dentine layer of the tooth. Therefore the action by artificial solutions should be tested to study how the induced modifications might inhibit the pain. The aim of the present study is to evaluate by scanning electron microscopy (SEM) the morphology of dentine surface after different chemical treatments. Oxalate solutions are able to produce a layer of large crystals, while acid solutions remove the smear layer and open the dentinal tubules.

Dentin↗
PubMed1991

Dental composite resin porosity and effect on water absorption.

The aims of this study were: 1) to characterize the solubility and water absorption of different composite resins used as dental restorative materials; 2) to analyse their surface morphology using S.E.M. The resins tested were a mixture of glycidyl methacrylate (Bis-GMA) and TEGMA filled with silane-coated particles of inorganic fillers, and Bis-GMA and urethane resin. Cylindrical samples of composite resin were polymerized and stored in distilled water and weighed after different times. SEM analysis demonstrated voids and porous in several samples. The present study shows that dental restorative composite loose a small percentage of their components during storage time and that the type of resin, the nature of fillers and the methods of polymerization greatly influence water uptake and solubility of dental composite resin materials. These findings could explain the loss of anatomic form and the occlusal degradation of dental composites in "in vivo" conditions.

Absorption↗
PubMed1991

Influence of the fluoride ion in the stability of bone hydroxyapatite achieved in patients after the fluo-calcic therapy.

It has been proposed that fluoride ion might actively enter into the basic structural framework of the bone, within its main constituent, the hydroxyapatite (HA), by substituting systematically the OH- ion in the crystal chemical formula Ca5[(PO4)3OH]. Accurate compositional studies have become necessary in order to explain an eventual stabilizing effect. Loss in weight (TG) and chemical reaction (DTG) while varying the temperature have been carried out for the first time on specimens under normal conditions and after fluo-calcic treatment, in parallel with accurate chemical compositional determinations by atomic absorption analysis. Our investigation shows that the new structure present after treatment is mechanically stable and proves more resistant to osteolytic processes.

Bone Neoplasms↗
PubMed1990

Cutaneous necrosis and calcinosis following electroencephalography.

The authors report 2 children who developed circumscribed dystrophic calcifications at the site of electrode placement after electroencephalographic examination. Deep cutaneous necrosis was a prominent clinical feature. A biopsy showed focal dermal calcification confirmed by a diffractometer analysis of a calcific granule. Cutaneous calcinosis is a possible risk of the usage of an electrode paste containing calcium chloride. Prolonged exposure and damaged skin seem to be prerequisites for this uncommon but harmful condition.

Calcinosis↗
PubMed1990

A preliminary study of human pineal gland concretions: structural and chemical analysis.

Acervuli and fragments of pineal gland obtained from 33 subjects of both sexes and age ranging from 1 to 87 years, (30 autopsy and 3 biopsy specimens) were analyzed by light microscopy, transmission and scanning electron microscopy, X-ray diffraction and X-ray energy dispersive microanalysis. It was found that primary mineralization occurs in an organic matrix formed by pinealocytes and that hydroxyapatite also takes place in mineral deposition. From our analysis, the formation of acervuli appears to be age and sex independent and can be possibly related to the secretory activity of the gland.

Adolescent↗
PubMed1990

Bone mineral alterations and Mg content in aging.

The authors propose to determine whether the quantity of bone mass reduction linked to aging is accompanied by qualitative modifications of the mineral structure. To this end, 18 samples of cancellous bone from the femoral heads of two groups of patients (Groups A & B), were examined. Group A was made up of 8 old osteopenic patients suffering from fracture of the femur neck (age 62-84). Group B consisted of 10 young non-osteopenic subjects (age 34-53). Through chemical analysis a statistically significant percentage increase in Mg++ was noted in Group A and, by X-Ray diffraction, significant presence of beta-TCP. Mineral structure alterations occur in the process of aging of the skeletal tissue.

Adult↗
PubMed1990

Determination of the mineral elements in the pollen of some Gymnospermae.

In this work the principal elements (K, Ca, Fe, Mg, Cu, Zn, Mn, Na) constituting the mineral component of the pollen in some Gymnospermae, have been determined. This type of investigation has few matches in literature despite the importance some mineral elements have in germinating the pollen granule. The pollen samples, appropriately treated, were analysed in atomic absorption spectrophotometry and biometrically characterized under the optical microscope. Examination of the analytical data allows verification of the great influence deriving from soil characteristics and, within the families, a specific role of the type. The morphobiometric parameters show that a link exists between small and medium granules and with thin walls and minimum concentration values of Na, Fe, Cu, Zn and Mn.

Minerals↗
PubMed1990

Evaluation of the relative rates of bone mineral content loss in postmenopause due to both estrogen deficiency and ageing.

To evaluate the relative rates of bone mineral content loss in postmenopause due to both estrogen deficiency and ageing, three groups of women were studied by computerized bone densitometry at the radius mid-point and at the distal point, modified according to the Abwrey technique. All women were in apparent good health and never had estrogen therapy. In the first group there were 64 women aged between 30 and 50 who were ovariectomized between 25 and 35 years of age. The second group was made up of 309 women between 50 and 55 years. In the third group there were 136 women aged 30-50 with normal ovaric function. The ordinary functions of linear polynomial regression were used to describe the variations in density with age. The percentage of postmenopausal bone loss was determined by calculating the BMC value at the start of the menopause and again twenty years later, according to the linear regression equation of postmenopausal period of each group of women in the study. The women who had natural menopause showed an average bone loss per year of 1.63% at the mid radius and 1.0% at the distal point. The ovariectomized women had an average loss of 0.85% at the mid point and 0.66% at the distal point. No significant decrease of bone mass was found before menopause. From a comparison between the two groups of women with analogous periods of menopause, it comes out that, during the first 20 years of natural menopause, estrogen deficiency is responsible for 52.5%-66.4% of the bone mineral loss, the remaining amount being attributable to other causes, connected with ageing. Estrogen deficiency is therefore, the principal factor causing bone mineral loss in natural menopause.

Adult↗