Biomedical subjects

C Preda

Publications and source records attributed to C Preda.

12 recordsLinked to original sources

PubMed2006

Functional data analysis for gait curves study in Parkinson's disease.

In Parkinson's disease, precise analysis of gait disorders remains essential for the diagnostic or the evaluation of treatments. During a gait analysis session, a series of successive dynamic gait trials are recorded and data involves a set of continuous curves for each patient. An important aspect of such data is the infinite dimension of the space data belong. Therefore, classical multivariate statistical analysis are inadequate. Recent methods known as functional data analysis allow to deal with this kind of data. In this paper, we present a functional data analysis approach for solving two problems encountered in clinical practice: (1) for a given patient, assessing the reliability of the gait curves corresponding to the different trials (2) performing intra individual curves comparisons for assessing the effect of a therapy. In a first step, each discretized curve was interpolated using cubic B-splines bases in order to ensure the continuous character of data. A cluster analysis was performed on the smoothed curves to assess the reliability and to identify a subset of representative curves for a given patient. Intra individual curves comparisons were carried out in the following way: (1) functional principal component analysis was performed to describe the temporal structure of data and to derive a finite number of reliable principal components. (2) These principal components were used in a linear discriminant analysis to point out the differences between the curves. This procedure was applied to compare the gait curves of 12 parkinsonian patients under 4 therapeutic conditions. This study allowed us to develop objective criteria for measuring the improvements in a subject's gait and comparing the effect of different treatments. The methods presented in this paper could be used in other medical domains when data consist in continuous curves.

France↗

PubMed2006

[Partial lease squares approach to functional analysis].

We extend the partial least squares (PLS) approach to functional data represented in our models by sample paths of stochastic process with continuous time. Due to the infinite dimension, when functional data are used as a predictor for linear regression and classification models, the estimation problem is an ill-posed one. In this context, PLS offers a simple and efficient alternative to the methods based on the principal components of the stochastic process. We compare the results given by the PLS approach and other linear models using several datasets from economy, industry and medical fields.

Biometry↗

PubMed1999

Microgravity cultivation of cells and tissues.

In vitro studies of cells and tissues in microgravity, either simulated by cultivation conditions on earth or actual, during spaceflight, are expected to help identify mechanisms underlying gravity sensing and transduction in biological organisms. In this paper, we review rotating bioreactor studies of engineered skeletal and cardiovascular tissues carried out in unit gravity, a four month long cartilage tissue engineering study carried out aboard the Mir Space Station, and the ongoing laboratory development and testing of a system for cell and tissue cultivation aboard the International Space Station.

Animals↗

PubMed1998

Partial cross-validation of low correlation for scores on the Test of Visual-Motor Integration and the Beery-Buktenica Developmental Test of Visual-Motor Integration.

The aim of this study was to further investigate the correlation between a well established test, the Beery-Buktenica Developmental Test of Visual-Motor Integration and a new copying test, the Test of Visual-Motor Integration. For scores on the tests of 71 children from a public school in Italy, the correlation is .34, which is consistent with earlier evidence and indicates that the Test of Visual-Motor Integration is not a substitute for the Beery-Buktenica Developmental Test of Visual-Motor Integration.

Child↗

PubMed1997

Test of visual-motor integration:: construct validity in a comparison with the Beery-Buktenica Developmental Test of Visual-Motor Integration.

The 1996 Test of Visual-Motor Integration manual states that an adjusted correlation of .95 was obtained between this test and the Beery-Buktenica Developmental Test of Visual-Motor Integration for 49 children with an average age of 9 years and that the adjusted .95 suggests equivalency of the tests. In the present study, for 103 children whose average age was 9 years, there was a correlation of .33 between the tests. Scores on the Beery-Buktenica test correlated more strongly than the Test of Visual-Motor Integration with both chronological age and academic achievement. Standard scorers for the latter test were high compared to those of the Beery-Buktenica test and the Comprehensive Test of Basic Skills. Interscorer agreement was significantly lower, and more time was required to score the protocols. This study indicates that the 1996 version is not a substitute for the Beery-Buktenica test.

Achievement↗

PubMed1991

Hormonal treatment in prostate cancer.

Prostate cancer is one of the most current diseases in elderly men and contributes greatly to the increase in mortality, morbidity and cost of health care. An adequate therapeutical approach requires a whole set of methods for establishing a correct histologic diagnosis and evaluating the local and general spread of the disease. As most of the neoplastic cells in the prostate are at least partly androgen-dependent, the goal of the hormonal therapy is to deprive them of androgenic hormones and their derivatives. On this purpose, the most important means of the hormonal therapy, starting with the traditional ones (orchidectomy, hypophysectomy, adrenalectomy, androgens administration) and ending with the latest achievements (anti-androgens, antiestrogens, LH--RH analogous) are scrutinized, making specific recommendations as to their indications, way of administration and effectiveness.

Adenocarcinoma↗

PubMedDate not supplied

[The use of echography in the diagnosis of autoimmune thyropathies].

Ultrasonography is a first line method in thyroid imaging. The aim of this study was to evaluate the usefulness of thyroid ultrasonography in the diagnosis of thyroid autoimmune diseases (TAD): Graves' disease (GD) and autoimmune thyroiditis (AT)--Hashimoto's and atrophic thyroiditis. Ultrasonography was performed with a 7.5 MHz transducer in 1033 consecutive patients. The excluding criteria was nodular goiter, irrespective of its function. Thyroid volume was calculated using the formula of a rotating ellipsoid. Hypoechogenicity was appreciated using a qualitative scale: 1 = absent, 2 = mild, 3 = moderate, 4 = marked. In patients with TAD thyroid hypoechogenicity was significantly higher than in normal subjects (2.5 +/- 1 in GD and 2.7 +/- 1 in AT, vs. 1.2 +/- 0.6 in normal subjects, p < 0.0001). The specificity of the test in identifying TAD was 91.4%, the sensitivity was 68.6% for GD and 80.8% for AT, positive predictive value was 91.5%, and negative predictive value 91.5%. Ultrasonography is useful in identifying patients with probable autoimmune thyroid diseases, being useful in epidemiological studies and having an important contribution in confirmation of the diagnosis.

Adult↗

PubMedDate not supplied

[The etiopathogenetic hypotheses in polycystic ovary].

First described in 1935, polycystic ovary syndrome (PCOS) is a frequent endocrine disease (6% in female population). However its pathogenicity is not yet completely understood. The possible etio-pathogenic mechanisms include: neuroendocrine disorders (hypothalamic, as a result of congenital androgenism or of disorders of neurotransmitters or pituitary, with excess of LH), ovarian disorders (enhanced sensibility at LH, local growth factors, hyperactivity of Cit P450cl7 alpha enzymes), adrenal disorders, insulin resistance, genetic determinism, puberty onset. The authors discuss in detail this hypothesis and these possible importance.

Adrenal Cortex↗

PubMedDate not supplied

[A comparative study of the bacterial dental plaque formation on fixed dentures with different surface characteristics].

The accumulation of dental plaque on fixed prostheses made of various biomaterials is influenced by the roughness of the surface. For the investigation of this aspects it was necessary of a method rapid, facile and cheaper in comparison with bacterial culturing and identification which is laborious and expansive. In this study we followed the accumulation of dental plaque on biomaterials like chrome-cobalt and gaudent polished and unpolished, at different periods of time (3 and 14 days). We observed that after 3 days the aspect is predominant coccoid and after 14 days is predominant bacillary. On unpolished crowns the width of dental plaque is greater and on gaudent crowns the plaque is structural organised around of filamentous organisms.

Dental Plaque↗

PubMedDate not supplied

[Thyroxine therapy in benign thyroid nodules].

Levothyroxine (LT4) treatment in benign thyroid nodules is a controversial management. The favorable response varies between 10-60%, being, in some studies, comparable between treated and untreated groups. The aim of this study was to evaluate the response of uninodular goiter at the LT4 treatment, in comparison with untreated patients. The study group (S) included 53 patients diagnosed with nodular goiter, treated with LT4 for 1 year. 26 patients with nodular goiter, age and sex-matched, untreated, constituted the control group (C). All patients were from a minor iodine deficient area. The including criteria were euthyroidism, single nodule, solid (ultrasonography), cold (Scintigraphy), and benign (FNAB). After 1 year mean nodular volume had a significant decrement in both groups, higher in group S (35%: from 7.8 to 5.2 mL, p = 0.0098) than in group C (25%: from 8.4 to 5.9 mL, p = 0.026). Linear regression showed a slight correlation between the nodular decrement and the initial volume (r = 0.23): the responders percentage was higher in nodules with a volume < 5 ml than in those with volume > 5 ml (51.5% vs o 19.6%, p < 0.0001). The evolution of treated nodules seamed to be better than of the untreated ones, but the differences were only slightly significant. We believe that the evolution of thyroid nodules under LT4 treatment can be influenced by the iodine supply, since in most of the studies from minor iodine deficiency regions (Europe, South America) the response is better than in regions with sufficient iodine supply (North America). Knowing the potential side effects of LT4 therapy, this kind of management of benign thyroid nodules should be reserved to selected cases.

Adult↗

PubMedDate not supplied

[Endocrinological disorders in association with alopecia areata-a 27 patients study].

Alopecia areata is a dermatological disease, characterized by the loss of hair, which affect men, women and children and can evaluate alone or in association with a variety of other disorders. Between these endocrinological diseases, especial thyroid disorders, have a high incidence. Twenty-seven patients with alopecia areata (12 women and 15 men) aged between 3 and 46 years were endocrinologically investigated. Eighteen of them (66.6%) had endocrinological disorders. Thyroid diseases were present in 10 cases (37%): 4 cases with endemic goiter, 2 cases with nodular goiter and 4 cases with hypothyroidism (1 case with autoimmune thyroiditis, 1 case with nodular goiter, 1 case with cystic goiter and 1 case with hypothyroidism post thyroidectomy for thyroidal lymphoma). Twelve cases (44.4%) were found with tetania. The incidence of thyroid diseases in alopecia areata is higher then in general population (2%), as well as the incidence of tetania. These evidences suggest that it is necessary to make a screening of endocrinological disorders in patients with alopecia areata.

Adolescent↗

PubMedDate not supplied

[Contribution of ultrasonography in the evaluation of subacute thyroiditis].

Ultrasonography is a useful tool in diagnosing and monitoring thyroid pathology. The aim of this study was to evaluate the value of thyroid ultrasonography in the follow-up of subacute thyroiditis (SAT). The study group included 48 subjects with clinical and biological diagnosis of subacute thyroiditis. All patients were evaluated by ultrasonography and followed-up for a mean period of 12 months. The evaluation protocol included biological data (TSH, T4, erythrocyte sedimentation rate--ESR) and ultrasonography, performed at 1, 2, 3, 6, and 12 months. Initially, all patients had an enlarged thyroid volume (median = 30.5 ml, range 23-90) and a low echogenicity, with an inhomogeneous aspect in 54.1% cases. After a mean period of 3 months thyroid volume had a significant reduction (median volume = 20.2 ml, range 7-36, p < 0.0001). Echogenicity was also significantly improved, with a decrement, on a semi-quantitative scale of 4 degrees (1 = normal, 4 = intense hypoechogenicity), from 3.25 to 2.48 (p < 0.0001). Almost half of the patients (45.8%) presented persistent (although slighter) hypoechoic/inhomogeneous pattern. Ultrasonographic abnormalities were not correlated with the intensity of the inflammatory syndrome and/or the thyroid status. Recurrence appeared in 10 (20.8%) patients. All patients presented a new thyroid enlargement (from a median = 16.1 ml to 31.5 ml, p = 0.056) and an extension of hypoechoic regions. The risk of recurrence could not be correlated with thyroid function, inflammatory syndrome or ultrasonographic aspect. There were not significant differences between the subgroups of patients with and without recurrence concerning the initial thyroid volume (p = 0.889), echogenicity (p = 0.735), TSH (p = 0.321) or ESR (p = 0.1332). Thyroid ultrasonography is useful not only for the initial diagnosis but also for the follow-up of patients with subacute thyroiditis. Remission and recurrence can be appreciated and monitored by the ultrasonographic pattern of the thyroid.

Adult↗