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M Zanatta

Publications and source records attributed to M Zanatta.

9 recordsLinked to original sources
PubMed2005

Bone microarchitecture evaluated by histomorphometry.

The increasing use of densitometric devices for assessing bone fragility has progressively strengthened the assumption that mass is the most important property determining bone mechanical competence. Nevertheless, structure and microarchitecture are relevant aspects of bone strength. The study of microarchitecture is based on the measure of width, number, and separation of trabeculae as well as on their spatial organization. There are several methods to assess bone architecture, particularly at the trabecular level. In particular, histomorphometry, based on the use of optical microscopy and on the principles of quantitative histology and stereology, evaluates microarchitecture two-dimensionally, even if these measures appear well correlated to the three-dimensional structure and properties of bone. In addition, new computerized methods allow the acquisition of more sophisticated measurements by means of a digitizer have been introduced to integrate the use of the microscope. These methods supply information on trabecular width as well as on its distribution and on the organization of the trabeculae in the marrow space. Microarchitecture seems to be a determinant of bone fragility independent of bone density and it is important for understanding the mechanisms of bone fragility as well as the action of the drugs used to prevent osteoporotic fractures. Several in vivo studies (on animals and humans) can provide an additional interpretation for the anti-fracture effect of such drugs. For instance, bisphosphonates and parathyroid hormone seem to preserve or even improve microarchitecture. The challenge for the future will be to evaluate bone quality in vivo with the same or better resolution and accuracy than the invasive methods used today.

Animals↗
PubMed2005

Histomorphometric analysis of glucocorticoid-induced osteoporosis.

Bone histomorphometry or quantitative histology consists of counting or measuring tissue components: cells, extracellular constituents and microarchitecture. Bone histomorphometry is the only method that allows the measurement of mineralization rate and the study of bone formation at three levels: cell, remodeling unit and tissue levels. It is a useful tool to explain the pathogenesis and cellular mechanisms of different metabolic bone diseases such as glucocorticoid-induced osteoporosis (GIO). Glucocorticoids (GC) affect calcium and bone metabolism at every level, but the main effect is the osteoblastic dysfunction. Concerning the bone formation, some histomorphometric studies have shown a depressed osteoblastic activity at a cell, bone remodeling unit, and tissue levels. In addition, there is evidence of a shortening of the period in which the osteoblasts work actively forming the bone matrix. This latter effect seems to occur after high cumulative doses of GC. With regard to the resorption, the results are still debated, but histomorphometric parameters seem to be increased in the majority of studies, at least in the first period of the GC treatment. From a structural point of view, GC seem to induce a thinning of the trabeculae without their perforation, which occurs only after high cumulative doses. Anti-resorptive treatments, such as bisphosphonates, are able to counteract the negative effects of GC on bone. In particular, along with their active working period, they prolong the lifespan of osteoblasts and osteocytes. In addition, the anti-resorptive treatments seem to extend the time for secondary mineralization through a reduction of the Activation Frequency. The latter is an intriguing mechanism of bisphosphonates in GIO that needs further ad hoc investigations.

Animals↗
PubMed1997

Bone marrow relaxation times in Gaucher disease before and after enzyme replacement therapy.

The aim of this work was to monitor the effectiveness of enzyme replacement therapy on the basis of the changes in T1 relaxation times in Gaucher patients. A total of 26 patients underwent MR before enzyme replacement therapy; of them, 18 have been followed-up. A total of 22 age-matched controls underwent the same MR study. Scans were focused on the femoral neck, and T1 relaxation times were measured by means of a mixed spin-echo inversion recovery sequence. The T1 relaxation times in Gaucher patients were significantly longer than normal (p < 0.05). After enzyme replacement therapy, T1 relaxation times gradually became closer to those of control subjects, and there was also a significant decrease (p < 0.01) with respect to values before therapy, probably due to an increase in the fat/water ratio. Evaluation of T1 relaxation time may supply a useful indication of Gaucher disease regression after enzyme replacement therapy particularly in those cases in which a normal skeletal appearance corresponds to prolonged T1 relaxation times.

Adolescent↗
PubMed1997

Intravenous pamidronate treatment in osteogenesis imperfecta.

Three children with osteogenesis imperfecta, severe osteopenia, and repeated fractures were treated with cyclic infusions of aminohydroxypropylidene bisphosphonate (pamidronate) for a period ranging from 22 to 29 months. A clear clinical response was shown, with a striking reduction of new fracture episodes and a marked improvement in the quality of the patients' lives. Bone mineral density increased significantly in two patients, and linear growth continued along the percentile at the start of treatment. There were no adverse effects of note during treatment, and further studies are warranted.

Bone Density↗
PubMed1994

Enzyme replacement treatment in type 1 and type 3 Gaucher's disease.

The development of intravenous enzyme-replacement treatment for Gaucher's disease has changed life expectancy in cases without neurological involvement (type 1). The effects in patients with neurological involvement are unknown. We treated 12 Italian patients, types 1 (9) and 3 (3), with intravenous alglucerase: 70-120 IU/kg per month for type 3 and 30-60 IU/kg per month for type 1. Maintenance infusions were biweekly in patients without neurological symptoms, whereas in one symptomatic type 3 patient, infusion was weekly. All patients improved; a resumption of growth in children with growth retardation was observed and spleen and liver reduced in size. In one type 3 patient, a bone callus formed during treatment and enabled the patient to walk. Laboratory tests showed rapid increase of haemoglobin in anaemic patients, and a slower response in patients with thrombocytopaenia. In 4 patients there was temporary hypocalcaemia immediately after the beginning of treatment. Neurological symptoms were present in 1 of the type 3 patients, and electroencephalogram was abnormal in another. After 2 years of treatment, the patient with symptoms showed an improvement of psychomotor skills and of IQ from 50 to 60. Genotype analysis showed a high frequency of the 1448C mutation (54.5%). The 9 patients carrying this allele came from Italian regions which in the past had been invaded from north Europe and Scandinavia. Enzyme replacement in Gaucher's type 1 can also be effective at low doses and even with a 2-week interval between infusions. This makes treatment cheaper, and reduces hospital stay for patients.

Adolescent↗
PubMed1994

Aminohydroxypropylidene-biphosphonate in the treatment of bone lesions in a case of Gaucher's disease type 3.

Gaucher disease is the most prevalent lysosomal storage disorder. It is characterized by an autosomal recessive inheritance of a deficiency of lysosomal acid glucocerebrosidase. Three clinical phenotypes are recognized: type 1 (non-neuronopathic), type 2 (acute neuronopathic), type 3 (subacute neuronopathic). Bone lesions are associated with type 1 and type 3 Gaucher disease. Skeletal involvement is secondary to the progressive accumulation of histiocytes and macrophages laden with glucosylceramide in bone marrow. Our patient was a female type 3 Gaucher patient who was referred to us at the age of 3 years with a neurological symptomatology and severe bone lesions (bilateral fracture of the femur heads, lytic process of the bone matrix of the femurs and distal flask deformity, kyphoskoliosis and chest deformity). The baby was constrained to a wheel-chair. The use of (3-amino-1-hydroxypropylidene)-1,1-biphosphonate (APD) was described in a case of Gaucher disease with very severe bone lesions. We used periodic iv infusions of APD (10 mg every 3 weeks) in our patient for a period of 20 months; after that, enzyme replacement therapy (alglucerase) was commenced. APD treatment showed normalization of bone density, formation of bone callus at the femural heads, positive calcium balance. The urinary Ca/Cr ratio and TRP were consistently normal during therapy. After 9 months of alglucerase therapy the patient was able to walk again. The data indicate that APD therapy can find an indication in Gaucher patients with severe bone involvement.

Bone Diseases↗