Biomedical subjects
Publications and source records attributed to E De Santis.
We analysed the surface of a Ti alloy femoral stem in a cementless total hip replacement with early failure. A specific protocol consisting of non destructive and destructive tests was used in the evaluation of the retrieved stem. The tests confirmed that implant fretting due to bone abrasion constitutes an early phase of loosening.
We investigated the mechanism by which particulate wear debris of polyethylene may induce bone resorption using an in vivo model. Two uncemented total hip prostheses, in which the socket was directly in contact with acetabular bone, were selected because there was massive bone loss around the implant. A thick synovium-like layer was found at the polyethylene-bone interface during revision operations. Samples were examined by transmitted and polarised light microscopy, and by transmission electron microscopy. This study demonstrates that polyethylene wear products alone can cause massive osteolysis by triggering the formation of foreign body granuloma at the bone-implant interface.
The ultrastructural appearance of two chondroblastoma were examined by scanning and transmission electron microscopy. The polygonal basal cells, with a scanty pericellular matrix, show a poorly developed endoplasmic reticulum and many Golgi bodies. The highly differentiated chondroid cells are assembled in isogenous clusters and show intracytoplasmic inclusions of glycogen and lipids, numerous mitochondria and superficial secretion vesicles arising from a well developed rough endoplasmic reticulum. Clusters of crystals, in close contact with the matrix collagen fibres are found near to the tumour cells. These ultrastructural characteristics, together with the basal undifferentiated cells that proliferate and differentiate into cartilaginous tissue, distinguish this neoplasm from chondroma, mesenchymal chondrosarcoma and chondromyxoid fibroma and confirm its chondroid origin.
We have examined the organic components of the nidus of an osteoid osteoma in 4 patients using scanning electron microscopy. Different organisation of the osteoblastic cells and of the fibrous structures of the osteoid matrix in different zones was demonstrated. These findings indicated a greater degree of immaturity in the centre, as compared with the peripheral area where the process of differentiation was more evident.
The ultrastructural localization of calpastatin, the endogenous inhibitor of the neutral calcium-dependent proteases (calpains), was investigated in rabbit skeletal muscle fibers using a polyclonal antibody against the 34 kDa form of the inhibitor isolated from rabbit. Quantitative studies by pre- and postembedding immunogold techniques revealed that the distribution pattern of the specific immunoreactivity included: 1) the sarcolemma with the adjacent cytoplasm (about 1 micron wide); 2) the myofibrils; 3) the mitochondria and 4) the nuclei (condensed as well as extended chromatin). Other cell substructures, such as lysosomes and the intermyofibrillar cytoplasm, were substantially devoid of immunoreactivity. Furthermore, in accordance to previous light microscope immunohistochemical experiments, an extracellular (endomysial) localization of specific immunoreactivity was confirmed. These results favour the view, which is also supported by a series of biochemical evidences, that calpastatin in rabbit skeletal muscle is present in cell structures also containing calpains and/or their putative substrates. The above multiple patterns of distribution also suggest that the muscular calpain-calpastatin system in skeletal muscle fibers may play different physiological roles in the various subcellular compartments.
The analgesic efficacy and tolerability of ST-679 (administered in a single oral dose of 1200 mg) was evaluated in a double-blind parallel-group study, as compared with paracetamol (administered in a single oral dose of 1000 mg) on 40 patients with pain following orthopedic or traumatological surgery. ST-679 was shown to possess better analgesic qualities with respect to paracetamol, in that the effect establishes itself more quickly and, moreover, both the maximum analgesic activity performed as well as the constant level on which such activity tends to stabilize is greater. No adverse reaction was recorded for either treatment, but ST-679 demonstrated a better tolerability with regard to paracetamol.
The authors report the results of scanning electron microscopy examination of samples of articular surface taken from 15 arthritic femoral heads removed during hip replacement. The specimens were collected from areas of the femoral head where different degrees of degenerative changes were identified, and processed with the normal techniques for scanning electron microscopy. A definition was made of the mechanisms leading to articular cartilage wear, the most obvious sign of cartilage degeneration. The earlier stages were characterized by the appearance of clefts in the surface layer, which merged and formed scales that flaked off, giving rise to superficial abrasions. The evolution of the degenerative process led to a deepening of the clefts, reaching the intermediate and deep layers and creating further scales of cartilage tissue, oblique or perpendicular to the surface. The elimination of these formations causes more or less marked wear that can extend down to the subchondral bone (ulcers and ground surfaces). As well as information on the condition of the articular surfaces, scanning electron microscopy may also provide details on the morphology and structure of the chondrocytes and the fibrillar network in the sagittal sections, showing the regressive phenomena associated with arthritis.
Calpastatin, the endogenous inhibitor of calcium-activated neutral proteases (calpains; EC 3.4.22.17), was studied in the rabbit vastus lateralis muscle by means of immunochemical and immunohistochemical techniques. Immunoaffinity chromatography using an antibody raised against the 34-kDa monomer of the 68-kDa dimeric inhibitor allowed us to isolate three main proteins (130-, 100- and 80-kDa). These proteins strongly inhibited calpain activity in muscle homogenate (I50 at about 50 micrograms/ml). Immunohistochemical experiments showed that calpastatin-related immunoreactivity was present in all fibre types (oxidative, glycolytic, oxidative-glycolytic) at both surface and cytoplasmic level. However, a few (20%) of the slow-twitch, oxidative fibres (5% of the total fibres), did not contain the cytoplasmic inhibitor. Specific immunoreactivity for calpastatin was also associated with the interstitial connective tissue. These results suggest that (i) calpastatin in skeletal muscle, as in other tissues, is present as a mixture of proteins of various molecular weights and (ii) the inhibitor may act not only in the cytoplasm but also at the surface or extracellular level.
Eleven cases of chordoma, localized at sacrum (3 cases), lumbar spine (6 cases), cervical spine (2 cases), are reported. Authors describe clinical and pathological findings of the tumor and underline peculiarity of spinal localization and difficulty of diagnosis, often delayed, particularly in sacral spine localizations. Radiotherapy and chemotherapy give poor results while surgery can be employed in the treatment on account of the slow evolution and of the not very frequent aptitude of the tumor to give metastases. However peculiar localization into the sacral spine allows to remove the whole tumor if only it is localized below the 2nd sacral vertebra; authors present such a case treated by means of subtotal resection of sacrum and coccyx. In proximal sacral localizations and in other spinal localizations, surgery is a palliative procedure and can only slow down the evolution of the tumor; recurrence is a rule, even in association with radiotherapy. However surgical treatment must be often performed because of myeloradicular involvement.
The authors report the results of automated percutaneous diskectomy in the treatment of the herniated disk. During an 18-month period this procedure was used on 39 patients with both evident radicular pathology that had not regressed even after 4-6 weeks of medical and physical therapy as well as clear disk herniation revealed by diagnostic imaging. The level of the herniated disk was L4-L5 in 30 cases. L5-S1 in 7 cases, and L3-L4 in 2 cases. The clinical diagnosis was confirmed by CAT scan in 20 cases, by both CAT scan and x-ray of the spinal region in 14 cases, and by x-ray only in 5 cases. The patients were reviewed 2, 6, and 12 months after surgery. The results were classified according to Watters' criteria based on both the relief of pain and the resumption of everyday work activity. The satisfactory results (excellent and good) totaled 59% at the 6-month follow-up, with no substantial variation at the 1-year follow-up. Hemilaminectomy was performed in 12 cases with unsatisfactory results, confirming the diagnosis of disk herniation in 10 cases (extruded in 9 cases and protruded in 1 case). Diskectomy is a non-invasive, atraumatic method which is indicated for both protruded (non-sequestrated) and subumbilical hernias and allows rapid functional recovery. The rate of success can be increased with more accurate selection of patients based on imaging diagnosis (CAT scan and MRI).
115 cases of osteoid osteoma treated over more than 18 years is reported. In 1 case the nidus was manifested in 2 different sites after 14 years. The following is emphasized: the terminology for osteoid osteoma should be changed in reference to osteoblastoma; osteoid osteoma and osteoblastoma constitute different aspects of the same neoplasia; the number of observations of osteoid osteoma increases as there is greater knowledge on the varieties of the tumor; treatment, which is exclusively surgical, may be limited to excision of the nidus, in order to guarantee the best healing possible. Resection should be limited to observations where the nidus is masked by osteosclerosis.
Ewing's sarcoma presents diagnostic problems with several inflammatory processes (osteomyelitis, osteoperiostitis, eosinophilic granuloma) and other bone tumors. Clinical, radiographic and laboratory findings must be supported by a careful biopsy. Delimitation of reticulosarcoma and metastatic neuroblastoma is also extremely difficult from a histopathological point of view.
Diagnostic problems connected with reticulum cell sarcoma are analyzed. Clinical, radiological, biochemical and hematological investigations combined with an accurate pathologic study are essential in order to arrive at a precise diagnosis. Ewing's sarcoma and other osteolytic sarcomas are discussed in the differential diagnosis.
The authors analyse the results obtained in the treatment of Ewing's sarcoma by comparing the period previous to the use of chemotherapy with the more recent one involving the use of antiblastic drugs. Thirty-one patients with Ewing's sarcoma were divided into three groups according to the type of treatment used. The first group included 11 patients treated either by surgery or high dosage radiation (7000-8000 rads); the second group included 9 patients treated by radiation plus polychemotherapy; finally, the third group included 11 patients treated by surgery (excision in 5 localizations and segmental resection in the remaining 6), associated with polychemotherapy and low dosage radiotherapy. The results in the first group were discouraging as none of the patients survived five years; there was a low survival rate (33%) for the second group, partly due to the fact that there were 4 localizations in the pelvis, a site with a notoriously unfavourable prognosis; the third group had the highest percentage (55%) of long-term disease-free patients. Thus, in agreement with what is reported in the literature, the most radical surgery possible, associated with polychemotherapy and low-dose radiotherapy, currently seems to be the best treatment.
Eight cases are described of circumscribed heterotopic ossification in the soft tissues characterised by spontaneous onset, no history of trauma, and rapid course which have frequently led to a mistaken preoperative diagnosis of highly malignant tumour. The terminology differentiates it from myositis ossificans, which is a different entity. The authors emphasize the need for accurate evaluation of all the clinical and radiographic data in order to avoid an erroneous diagnosis of extraosseous osteogenic sarcoma or parosteal osteogenic sarcoma. In this regard, both radiography and histological examination demonstrate the so-called zoning pattern, namely a radiolucent central zone corresponding to the more immature area and consisting of fibrous tissue with active histiofibroblastic proliferations and a radiopaque peripheral area, where ossification is more mature the closer it gets to the periphery. Histological specimens obtained exclusively from the central area may lead even the most expert pathologists to a diagnosis of fibrosarcoma or osteogenic sarcoma. Finally, the pathogenetic aspects of the anomaly are discussed, as well as those concerned with the differential diagnosis from other types of heterotopic ossification.
Reticulosarcoma, nowadays usually referred to as non-Hodgkin's malignant lymphoma, is a particularly rare primary bone tumour. This study includes 12 cases observed over more than 15 years. The favourable clinical course of the tumour, and the use of complementary therapy justify a more extensive use of surgical treatment. Five cases were submitted to surgery plus complementary chemotherapy; two resections of the tibia, one of the humerus, one scapulectomy and one disarticulation of the hip. The remaining 7 cases were treated by radiation therapy. The overall prognosis of the disease is not very favourable (25% survival rate) although its slow progress gives a favourable clinical impression. Treatment may, however, influence the prognosis; much better results are obtained by radical surgery with complementary chemotherapy. In one resection of the tibial diaphysis and one radical scapulectomy there was no local recurrence or metastases at 3 and 4 years follow-up, whereas cases treated previously by less radical surgery and inadequate chemotherapy, although showing no local recurrence, did result in systemic diffusion of the disease.
Explore the source record for details and available documents.
Explore the source record for details and available documents.