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PubMed1992

Mean corpuscular volume of heterozygotes for beta-thalassemia correlates with the severity of mutations.

The relationship between the degree of microcytosis and the type of mutation carried by beta-thalassemia heterozygotes was investigated. In 113 individuals, 18 different mutations were identified, correlated with mean corpuscular volume (MCV) values, and analyzed statistically. Overall, there was a wide range of MCV (56.3-87.3 fL). In almost all cases, carriers of beta(0) mutations had an MCV below 67 fL, whereas all but a few beta(+) heterozygotes had MCVs above this cutpoint. Mean MCV of beta(0) carriers was statistically significantly lower than those of beta(+) heterozygotes. The various beta(+) mutations were associated with significant differences in mean MCV values. In contrast, all the beta(0) (null) mutations had virtually identical ranges of MCV. The results indicate that degree of reduction in MCV is directly related to the severity of the mutation. Deviations, in four cases, were associated with concurrent alpha gene rearrangements, whereas in three other cases, the MCV was not significantly affected by concurrent alpha rearrangements. The MCV of beta-thalassemia heterozygotes is a valuable parameter in planning strategies for rapid identification of mutations in populations with great mutational diversity. Its use can be particularly advantageous in the setting of prenatal diagnosis. The pattern of mean corpuscular hemoglobin (MCH) values was similar to the MCV pattern. However, our results suggest that MCH may be preferred for carrier detection in population screening.

Erythrocyte Indices↗

PubMed1991

[Conventional surgical furcation therapy. Closed and open scaling].

Epidemiological studies in the sixties indicated that in patients older than 45 years periodontal disease was the major cause of tooth-loss, particularly in molars. However, improved prevention and enhanced dental awareness have now reduced both the incidence of periodontal disease and tooth-loss. Unfortunately, periodontal disease and tooth-loss still progress rapidly in a small group of patients. The currently used diagnostic parameters do not allow the early identification of this small group. Despite controlled periodontal treatment, loss of molars has remained twice as high as overall tooth loss. When all patients are divided into different perio-subgroups, molar loss tends to identify patients with a high periodontal risk. This conclusion can be drawn from the fact that furcation treatment is usually clinically successful, although calculus removal is insufficient. Early diagnosis of molar furcation involvement may help identify the small group of patients in which periodontitis may develop. The local morphological patterns may also contribute to rapid progression of the disease resulting eventually in loss of the molars. In such cases resective therapy is proposed instead of the usual open or closed scaling procedures.

Adult↗

PubMed1990

[Impact of high resolution computerized tomography on the clinical assessment of pulmonary interstitial diseases].

Our purpose is to define the morphological patterns of interstitial lung disease on CT and to evaluate the diagnostic impact of high-resolution technique (HRCT). Sixty-six consecutive patients with proven interstitial lung disease were considered in our study. The basic morphological patterns include: a) large reticular pattern (10-25 mm); b) small reticular pattern (2-3 mm); c) intermediate reticular pattern (5-10 mm) with cystic dilatation of distal airspaces; d) nodular pattern; e) high-density parenchymal areas. Topography of the involved areas (peripheral, middle and axial compartments), and lesion distribution with reference to the secondary pulmonary lobule (centrilobular, perilobular, panlobular, bronchovasal) are additional diagnostic criteria. The identification and correlation of these three parameters proved very useful in limiting the range of diagnostic possibilities to interstitial disease, obviously considering clinical data. In our series a correct CT diagnosis was obtained in 57 of 66 cases (86.36%). In 24 of them (36.34%) diagnosis corrected a previous erroneous or generic clinical suspicion. Our data suggest that HRCT is indicated in interstitial lund disease when neither clinical nor radiographic findings allow a specific diagnosis to be made.

Diagnostic Errors↗

PubMed1978

Diagnostic value of quantitative electromyography. Its scope and limitations.

On the evidence of 951 cases of the 10,500 investigated with the aid of quantitative electromyography the author shows the value of the method for diagnosing muscle activity. Statistical analysis was applied to check the diagnostic value of EMG parameters separately and jointly in the identification of the pathology and its classification as either neurogenic or myogenic. Also surveyed are the sources of the discrepancies between the electromyographic and the histopathological results in very early and very advanced cases. Examples are given that show electromyographic findings as nosologically non-specific and the method as inferior to the morphological in this respect. On the other hand the method is stressed as one that permits it to (a) tell a malignant and rapid process from a slow one, (b) obtain evidence of repair and (c) prove generalization of processes considered to be local or the progressive character of processes considered to be non-progressive. The author also refers to the added scope given to electromyography by such developments as automatic recording, SFEMG, and determination of motor unit territory with the aid of multielectrodes.

Electrodes↗

PubMed1987

[The frequency parameters of electrogastromyograms].

The changes in the frequency parameters of the basic electrical gastric rhythm were studied with the application of cutaneous electrodes in men. The study has demonstrated that the frequency parameters of the basic electrical gastric rhythm are dependent on the organ's functional state. The frequency parameters can be used for the identification of the gastric functional state both in healthy and sick subjects.

Adolescent↗

PubMed1985

[Permeability of the erythrocyte membrane for sodium in hypertension and symptomatic hypertension].

Sodium permeability of erythrocyte membranes was examined, using the recording of maximum rates of sodium-lithium countertransport, in patients with essential hypertension of stages II and III by the WHO classification, renal arterial hypertension, Itsenko-Cushing disease, pheochromocytoma, Conn's syndrome and in subjects with normal arterial pressure who made up a control group. Hypertensive patients demonstrated a more than 60% increase in erythrocyte membrane permeability, as compared to normotensive controls. In patients with pheochromocytoma, the permeability values were almost 40% as low as the control ones. No changes in sodium erythrocyte membrane permeability could be demonstrated in patients with renal hypertension, Itsenko-Cushing disease and Conn's syndrome. It is believed that the erythrocyte membrane permeability parameters can be used for the identification of essential hypertension in the differential diagnosis of hypertensions.

Adrenal Gland Neoplasms↗

PubMed2003

Dynamic causal modelling.

In this paper we present an approach to the identification of nonlinear input-state-output systems. By using a bilinear approximation to the dynamics of interactions among states, the parameters of the implicit causal model reduce to three sets. These comprise (1) parameters that mediate the influence of extrinsic inputs on the states, (2) parameters that mediate intrinsic coupling among the states, and (3) [bilinear] parameters that allow the inputs to modulate that coupling. Identification proceeds in a Bayesian framework given known, deterministic inputs and the observed responses of the system. We developed this approach for the analysis of effective connectivity using experimentally designed inputs and fMRI responses. In this context, the coupling parameters correspond to effective connectivity and the bilinear parameters reflect the changes in connectivity induced by inputs. The ensuing framework allows one to characterise fMRI experiments, conceptually, as an experimental manipulation of integration among brain regions (by contextual or trial-free inputs, like time or attentional set) that is revealed using evoked responses (to perturbations or trial-bound inputs, like stimuli). As with previous analyses of effective connectivity, the focus is on experimentally induced changes in coupling (cf., psychophysiologic interactions). However, unlike previous approaches in neuroimaging, the causal model ascribes responses to designed deterministic inputs, as opposed to treating inputs as unknown and stochastic.

Arousal↗

PubMed2004

Quantitative ultrasound measurements of the calcaneus in the prediction of lumbar spine degeneration.

A cross-sectional study was conducted to evaluate the possible use of a low-cost radiation-free technique in the prediction of degenerative changes in the lumbar spine. Although an inverse correlation between osteoporosis and degenerative changes in the lumbar spine has been reported, no previous studies have asked whether there is a correlation between calcaneal quantitative ultrasound results and degenerative findings in the lumbar spine. In 117 patients with low back pain or pain in the lower limb, ultrasonographic parameters (speed of sound, broadband ultrasound attenuation, stiffness) of the calcaneus were correlated with evidence of degenerative changes and stenosis on magnetic resonance scans of the lumbar spine. Linear and logistic regression, as well as receiver operator characteristic curve analyses, were used to evaluate the correlation. Lumbar spine stenosis was associated with elevated calcaneal ultrasonographic parameters, particularly speed of sound. For the identification of a narrowing of the lumbar spinal canal below 100 mm(2) of dural sac cross-sectional area, speed of sound showed 89% sensitivity and 75% specificity in males older than 60 years. In male patients, we also found a significant positive correlation between ultrasonographic parameters and scores on a degenerative scale that primarily reflects intervertebral disc degeneration ( P=0.019 for speed of sound; P=0.039 for stiffness). In conclusion, calcaneal quantitative ultrasound is frequently used in elderly patients with low back pain as a diagnostic test for osteoporosis. The incidental finding of high values on ultrasonographic parameters in these subjects, particularly in males, is highly correlated with lumbar spine degeneration and stenosis, and can help to identify those symptomatic patients needing more extensive diagnostic testing.

Adult↗

PubMedDate not supplied

Localization of a fluorescent object in highly scattering media via frequency response analysis of near infrared-time resolved spectroscopy spectra.

Frequency response analysis via pulse testing for engineering systems and near infrared (NIR) time resolved spectroscopy (TRS) for biological system characterization involve identical principles: the system of interest is disturbed by an input pulse and the output response is observed. Since a sharp pulse, such as the Dirac delta function, contains the information of multimodulation frequencies (theoretically from 0 to infinity in frequency) a narrow pulse TRS input can produce a wide range frequency response for identifying any system of interest. Currently used NIR-TRS spectral analyses either fit the spectra with a known theoretical solution or use photon mean time-of-flight. Transforming the system time domain representation to the frequency domain generates five system parameters that can be valuable for process identification utility: steady state gain, time constant, system order, and magnitude ratio and phase shift over a wide frequency range. Optical contrast agents or fluorescent agents can be used to enhance the capability of optical instruments in detecting biological heterogeneities. In this article, magnitude ratio, phase shift, and other system parameters derived from the transfer function of systems with both a fluorescent absorber and a regular absorber are correlated with the position of the absorber. This technique is important in that ultimately it can be used to enhance optical medical imaging.

Artifacts↗

PubMed1986

Pitch identification of simultaneous dichotic two-tone complexes.

The optimum processor theory of Goldstein can, in principle, account for pitch perception phenomena involving simultaneous dichotic complex tones. The frequency-coding noise function, which is the only free parameter of the model, was estimated with pitch identification data of two simultaneous two-tone complexes presented to different ears. This "sigma" function was found to have a shape similar to that of the function derived from data on identification performance for single pitches. The sigmas in the simultaneous pitch identification experiment are larger by an amount that differs from subject to subject. By using different methods of data analysis it was found that the pitch estimation processes for the two tones are independent for most subjects. This allows a simple extension of Goldstein's optimum processor theory.

Dichotic Listening Tests↗

PubMed1997

Stimulus variability and spoken word recognition. II. The effects of age and hearing impairment.

Three experiments were conducted to investigate the effects of variations in talker characteristics, speaking rate, and overall amplitude on perceptual identification in normal-hearing young (NHY), normal-hearing elderly (NHE), and hearing-impaired elderly (HIE) listeners. The three dimensions were selected because variations in voice characteristics and speaking rate affect features of speech signals that are important for word recognition while overall amplitude changes do not alter stimulus parameters that have direct effects on phonetic identification. Thus, the studies were designed to examine how variations in both phonetically relevant and irrelevant stimulus dimensions affect speech processing in a number of different populations. Age differences, as indicated by greater effects of variability for the NHE compared with the NHY listeners, were observed for mixed-talker and mixed-amplitude word lists. Effects of age-related hearing impairment, as indicated by reduced scores for the HIE compared with the NHE group, were observed for variations in speaking rate and talker characteristics. Considered together, the findings suggest that age-related changes in perceptual normalization and selective attention may contribute to the reduced speech understanding that is often reported for older adults.

Aging↗

PubMed1995

An inverse approach to determining myocardial material properties.

Passive myocardial material properties have been measured previously by subjecting test samples of myocardium to in vitro load-deformation analysis or, in the intact heart, by pressure-volume relationships. A new method for determining passive material properties, described in this paper, couples a p-version finite element model of the heart, a nonlinear optimization algorithm and a dense set of transmural measured strains that could be obtained in the intact heart by magnetic resonance imaging (MRI) radiofrequency tissue tagging. Unknown material parameters for a nonlinear, nonhomogeneous material law are determined by solving an inverse boundary value problem. An objective function relating the least-squares difference of model-predicted and measured strains is minimized with respect to the unknown material parameters using a novel optimization algorithm that utilizes forward finite element solutions to calculate derivatives of model-predicted strains with respect to the material parameters. Test cases incorporating several salient features of the inverse material identification problem for the heart are formulated to test the performance of the inverse algorithm in typical experimental conditions. Known true material parameters can be determined to within a small tolerance and random noise is shown not to affect the stability of the inverse solution appreciably. On the basis of these validation experiments, we conclude that the inverse material identification problem for the heart can be extended to solve for unknown material parameters that describe in vivo myocardial material behavior.

Algorithms↗

PubMed1992

Lack of prognostic value of histopathologic parameters in Hodgkin's disease, nodular sclerosis type. A study of 123 patients with limited stage disease who had undergone laparotomy and were treated with radiation therapy.

The value of histopathologic parameters in predicting the long-term overall survival probabilities was studied in a series of 123 patients with pathologic stage IA, IB, IIA, IIB, or IIIA Hodgkin's disease, nodular sclerosis type who were treated with curative radiation therapy. The parameters that were studied included the relative proportion of atypical vs reactive cells, amount of eosinophils, presence of necrosis, degree of mitotic activity, intensity of different types of mesenchymal reactions, classification in three subtypes (ie, lymphocyte predominance, mixed cellularity, and lymphocyte depletion) or in two grades (ie, grades 1 and 2), and identification of the syncytial variant. For each parameter, the association with clinical risk factors was also analyzed. The results of this study show that there are no pathologic features that carry a significant predictive value of the overall survival.

Adolescent↗

PubMed1971

Rapid identification of viruses by indirect immunofluorescence: isolation and identification of adenovirus types 4 and 7 and coxsackievirus type A21 in microcultures.

The indirect fluorescent-antibody test (IFAT), employing treated and standardized antiserum in a single pool, was earlier reported to have been used successfully for the preliminary identification of nine respiratory viruses in second to ninth passage multiplying in cells propagated on microscope slides. This report describes parameters affecting the isolation in first passage and the identification by IFAT of adenovirus types 4 and 7 and coxsackievirus type A21 present in stored clinical specimens inoculated into microcultures of WI-38 cells. Isolation frequency was comparable to that obtained in tube cultures, and identification by IFAT of viruses in microcultures could be accomplished in 3 to 4 hr after recognition of a cytopathogenic effect.

Adenoviridae↗

PubMed1986

[Precancerous stages of the oral mucosa--possible identification of obligatory precancerous conditions].

Macroscopically and microscopically precancerous lesions of the oral mucosa cannot be diagnosed with sufficient accuracy. Dysplasias represent a particular diagnostic difficulty. The reproducibility of grading of dysplasias may be increased by the quantification of morphological parameters using image analysis systems. However an unequivocal identification of obligatory precancerous lesions cannot be attained by this method. Measurement of the nuclear DNA content represents a non-morphological method for the identification of obligatory precancerous lesions. The diagnostic criterion of malignancy is aneuploidy. Structural or numerical chromosomal aberrations that are absent in benign tumours and normal cells typify aneuploidy. Aneuploidy is manifested by an atypical nuclear DNA distribution that can be identified objectively by suitable algorithms. Dysplasias of the squamous epithelium with aneuploid nuclear DNA contents are regarded as obligatory precancerous lesions. DNA measurements, computation of data and printout of a 'DNA diagnosis' are possible with a TV-image analysis system and an automated microscope within 30 min.

Carcinoma in Situ↗

PubMed2001

Magnetocardiographic intra-QRS fragmentation analysis in the identification of patients with sustained ventricular tachycardia after myocardial infarction.

The aim of this study was to investigate if magnetocardiographic (MCG) analysis of cardiac micropotentials within the QRS complex can identity patients prone to ventricular arrhythmias, and to compare it to MCG time-domain, late-field analysis. The study population consisted of 136 patients with remote MI, 53 with and 83 without a history of VT. After averaging and high pass filtering of multichannel MCG signals, time-domain parameters describing the end-QRS activity and fragmentation index M and score S describing the whole QRS complex were computed. Fragmentation and time-domain parameters differed between the VT and control groups: fragmentation index M was 12 +/- 3 versus 9 +/- 2 (P <0.001), fragmentation score S was 83 +/- 42 versus 56 +/- 21 (P < 0.001), and filtered QRS duration was 144 +/- 32 versus 114 +/- 19 ms (P < 0.001) in VT and control groups, respectively. A combination of fragmentation parameters yielded 87% sensitivity and 61% specificity in VT identification. Corresponding figures for a time-domain parameter combination were 81% and 72%. Sensitivity of time-domain analysis was 88% and specificity was 75% in a subgroup with anterior MI. In multivariate analysis, fragmentation and time-domain analyses discriminated VT patients from controls independently of the extent of coronary artery disease or left ventricular dysfunction. MCG in postinfarction patients reveals pathology associated with propensity to ventricular arrhythmias inside and not only at the end of the QRS complex. MCG seems most accurate in the anterior infarct location.

Aged↗

PubMedDate not supplied

Current management of hospitalized community acquired pneumonia in Portugal. Consensus statements of an expert panel.

The diagnosis and treatment of Community Acquired Pneumonia (CAP) are controversial issues, without evidence of solid consensus, reflected in the proliferation of Clinical Practice Guidelines proposing a wide range of recommendations. The aim of this study was the clinical validation of five of the most widely recognized Clinical Practice Guidelines (published by the British Thoracic Society, American Thoracic Society, Infectious Diseases Society of America, European Respiratory Society and Portuguese Society of Pulmonology), in line with the real situation in Portugal, as well as an assessment of the role of macrolides in the treatment of CAP. This study adopted the Delphi method to reach consensus from a panel of 20 Portuguese experts in the treatment of CAP, 16 of which participated actively in the study. A questionnaire with all the management options recommended by the five guidelines was distributed to the experts, who reported their degree of agreement with each recommendation on a 9-point Likert scale. The opinions of the specialist panel are reported, as well as the level of consensus and degree of sufficiency of each management option. The results of this study allowed the identification of the management options receiving a high level of acceptance among Portuguese physicians, as well as the estimation of epidemiological parameters, the definition of standards of care and the identification of the most relevant characteristics for the initial selection of antibiotics for empirical therapy. Erythromycin presents disadvantages in almost all characteristics, compared to advanced generation macrolides. Among these, azithromycin meets the panel of experts preferences as to antibiotic tolerability, administration schedule and costs better than clarithromycin.

Anti-Bacterial Agents↗

PubMed1990

[Defecometry: determination of objective parameters of defecation].

A method is presented for the identification and analysis of constipation due to difficult evacuation of rectal content. This condition--which has not been elucidated by former techniques--was identified in 5 out of the 19 constipated patients by this new method. Disturbed defecation was characterized by prolonged evacuation of the simulated stool and the greater work performed during this process. The cause of this phenomenon was the paradox movement of the pelvic floor, i.e. contraction instead of relaxation. The results' highlight: the excessive straining can induce a neuromuscular damage to the pelvic floor. The clinical importance of this method lies in the clarification of the principle, that the therapy of this condition must be initiated as early as possible.

Constipation↗