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Biomedical subjects

M Girolami

Publications and source records attributed to M Girolami.

At least 19 recordsLinked to original sources
PubMed2001

A variational method for learning sparse and overcomplete representations.

An expectation-maximization algorithm for learning sparse and overcomplete data representations is presented. The proposed algorithm exploits a variational approximation to a range of heavy-tailed distributions whose limit is the Laplacian. A rigorous lower bound on the sparse prior distribution is derived, which enables the analytic marginalization of a lower bound on the data likelihood. This lower bound enables the development of an expectation-maximization algorithm for learning the overcomplete basis vectors and inferring the most probable basis coefficients.

Journal Article↗
PubMed2001

Gemcitabine as single agent therapy in advanced non small cell lung cancer and quality of life in the elderly.

BACKGROUND: The aim of this study is to test the efficacy of gemcitabine as single agent therapy in advanced non-small cell lung cancer in the elderly by the evaluation of the clinical response, the survival increase and the quality of life. METHODS: Nineteen patients (age >65 years) with a PS >2, bearing an advanced non-small cell lung cancer (IIIb-IV) not treated with chemotherapy before, were charged between December 1996 and December 1998. Sixteen patients were treated with gemcitabine at the dose of 1000 mg/mq 1-8-15 every 28 days. CT scan, X-rays and skeletal scintigraphy were used in the evaluation of the therapeutic response. The toxicity was estimated by following WHO indexes. The quality of life and the modification of the specific symptoms were estimated by particular tests (Spitzer Index, IADL, EORTC-LC13). RESULTS: One complete response (6%), 4 partial responses (25%), 7 cases of illness stabilization (43%), 4 cases of illness progression, were shown. One year of survival was found in 43% of cases with a 14 week of therapeutic response and a global survival ratio of 12.4 weeks. Only 2 cases (12.5) of medium grade G3-leucopenia were found. All patients improved their quality of life (IADL and Spitzer indexes) with reduction of symptoms, (EORTC-LC13) and increase of self-agin and relationships. CONCLUSIONS: The effectiveness of gemcitabine as single agent therapy as not yet been tested due to the scanty number of patients, nevertheless it must be considered in relation to the improvement of the patient s quality of life.

Aged↗
PubMed2000

The mobility of the proximal tibio-fibular joint. A Roentgen Stereophotogrammetric Analysis on six cadaver specimens.

In six cadaver specimens the mobility of the proximal fibula in relation to the tibia was investigated during plantar/dorsiflexion of the ankle, using Roentgen Stereophotogrammetric Analysis (RSA). The role of the ankle joint, and of the calcaneofibular and talofibular ligaments was also evaluated. The greatest movements were observed along the mediolateral and anterior-posterior axes, resulting in an anterolateral displacement of the fibula head during dorsiflexion and in a postero-medial displacement during plantarflexion. This study demonstrated a limited mobility of the proximal tibiofibular joint. Moreover, the ligament cutting and the presence of constraints in the ankle region did not show any effect on the fibular movement.

Analysis of Variance↗
PubMed1999

Independent component analysis using an extended infomax algorithm for mixed subgaussian and supergaussian sources.

An extension of the infomax algorithm of Bell and Sejnowski (1995) is presented that is able blindly to separate mixed signals with sub- and supergaussian source distributions. This was achieved by using a simple type of learning rule first derived by Girolami (1997) by choosing negentropy as a projection pursuit index. Parameterized probability distributions that have sub- and supergaussian regimes were used to derive a general learning rule that preserves the simple architecture proposed by Bell and Sejnowski (1995), is optimized using the natural gradient by Amari (1998), and uses the stability analysis of Cardoso and Laheld (1996) to switch between sub- and supergaussian regimes. We demonstrate that the extended infomax algorithm is able to separate 20 sources with a variety of source distributions easily. Applied to high-dimensional data from electroencephalographic recordings, it is effective at separating artifacts such as eye blinks and line noise from weaker electrical signals that arise from sources in the brain.

Algorithms↗
PubMed1998

An alternative perspective on adaptive independent component analysis algorithms

This article develops an extended independent component analysis algorithm for mixtures of arbitrary subgaussian and supergaussian sources. The gaussian mixture model of Pearson is employed in deriving a closed-form generic score function for strictly subgaussian sources. This is combined with the score function for a unimodal supergaussian density to provide a computationally simple yet powerful algorithm for performing independent component analysis on arbitrary mixtures of nongaussian sources.

Journal Article↗
PubMed1994

Surgical repair of achilles tendon ruptures using polypropylene braid augmentation.

Surgical repair in fresh rupture of the Achilles tendon should be considered in active patients and athletes to restore their preinjury level of activity. Fifteen cases of Achilles tendon rupture underwent surgical repair using interpositional augmentation. This technique provides an immediate mechanical strength of the repair, avoiding the need for a postoperative plaster cast and allowing immediate motion of the ankle. No wound infection, scar adherence of the skin to the tendon, or rerupture of the tendon is present in this series. All patients were subjectively satisfied with the results and returned to their preinjury level of activity. Objectively, isokinetic assessment revealed no significant difference, as per t-test evaluation (P < .05), between the operated leg and the controlateral one.

Achilles Tendon↗
PubMed1992

Kinematic and isokinetic evaluation of patients with flat foot.

In recent years research into joint physiology and biomechanics of movement has employed high-technology instruments to quantify the parameters which determine whether the behavior of a joint or kinematic chain is normal or pathologic. Motion analysis, featuring evaluation of both kinematics and the foot-ground reaction, enables us to measure the temporal and quantitative events of normal and pathologic gaits. The use of motion analysis in the study of flat foot has confirmed the ability to discriminate between "normal" and pathologic. Analysis of these themes has enabled us to follow the temporal evolution of the quantitative parameters both before and after treatment, which can be either surgical or conservative. Evaluation of the kinematic changes and the foot-ground reaction also provides information about the quality and effectiveness of the corrective treatment. For instance, the change in the subtalar alignment following application of an endo-orthotic implant can be targeted for validation by motion analysis. All of the joints comprised in the kinematic chain of the lower limb work together to achieve a symmetrical, rhythmic, and most of all harmonic gait.

Adolescent↗
PubMed1991

Human Achilles tendon: morphological and morphometric variations as a function of age.

Aging of human Achilles tendon results in changes in both cellular and fibrous components. Cells flatten and become less numerous. Their thin and long cytoplasmatic projections tend to shorten and diminish in number. Tendon fibers lose their typical undulating appearance and become quite straight. Collagen fibril diameter, small and uniform in the neonatal period, becomes large and extremely variable from adolescence onwards. Age related morphometric changes include a decrease in the average, maximum diameter and density of collagen fibrils and an increase of fibril concentration. In our opinion these morphological and morphometric variations are strictly related to functional requirements.

Achilles Tendon↗
PubMed1991

[Evaluation of the splenic function in patients with abdominal injuries undergoing splenectomy with autograft].

Splenectomy, required for splenic injuries in which conservative management is unsuitable, causes a fall of the immunological defenses, increasing the risk of sepsis. Immunological functions of the spleen can be maintained by autotransplant of splenic tissue. This is confirmed in our experience by a comparative study of haematological, immunological and scintigraphic features in 14 patients. Autotransplantation was performed in 8 cases, while the remaining 6 cases were treated with simple splenectomy.

Adolescent↗
PubMed1989

Biological osteosynthesis in osteochondral lesions of the talus.

Osteochondral lesions of the dome of the talus whether medial or lateral are rare. Surgical treatment is required when there is a loose body, or when the lesion is symptomatic and resistant to nonsurgical treatment. Usually, the degenerated fragment is removed, followed by curettage and multiple perforations of the subchondral bed, but different methods may be used to reinsert the osteocartilaginous fragment. Having been satisfied with our first studies conducted both on animals and man, we began to reinsert the osteochondral fragment by using resorbable means of synthesis. The purpose of this study is to report our experiences with 3 such cases at a minimum follow-up of one year.

Adolescent↗
PubMed1985

Modified Jones operation in the treatment of pes cavovarus.

The authors describe their technique and results in the treatment of pes cavovarus by transposition of extensor hallucis brevis to the first metatarsal (Jones operation) in association with arthrodesis of the interphalangeal joint of the hallux. In cases of structural deformity it is also combined with osteotomy of the base of the first metatarsal.

Adolescent↗
PubMed1985

The surgical treatment of infantile flat foot. A new expanding endo-orthotic implant.

In the correction of flat foot in children, the fundamental requirement is to restore the normal relationship between the talus and calcaneus. To achieve this, the authors have devised an expanding orthotic implant which is inserted into the sinus tarsi. They discuss the indications and describe the surgical technique and the special instruments devised for fitting the device. The case material and first results after not less than 18 months follow-up are reported.

Adolescent↗
PubMed1983

The treatment of supracondylar fractures of the humerus in children by closed reduction and fixation with percutaneous Kirschner wires.

The results are reported of 50 consecutive cases of supracondylar fracture of the humerus in children treated by closed reduction and fixation by two parallel percutaneous Kirschner wires. A classification based on clinical and radiological findings is proposed. This is orientated both to treatment and prognosis. The technique of fixation is described and the results of four years experience of this method are reported. The long term results confirm the validity of the method, which has undoubted advantages over traditional methods. Early treatment is essential in cases with neurological or vascular complications.

Bone Nails↗
PubMed1981

[Radiophages and aseptic microsequestration of bone].

Using thorotrastosis for a model we showed that corpuscular radiating substances after entering the vascular space are also being accumulated in the RES (radiophages) of the bone marrow. Redistribution of these substances over the years leads first to mobile and later to immobile deposits of radiophages. This results in a reduction of bone marrow mass in the affected areas as well as myelosclerosis and sometimes in the development of so-called embryonic bone formation (a potentially presarcomatous lesion) and later in the formation of aseptic microsequesters of preexisting spongiosa spicules. Reference is also made to the infrequently observed phagocytosis of osteoblasts and osteocytes.

Aged↗