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Biomedical subjects

G Berger

Publications and source records attributed to G Berger.

At least 55 records · Page 3Linked to original sources
PubMed2000

Computerized ultrasound B-scan characterization of breast nodules.

The ability of computerized parameters to discriminate benign from malignant breast nodules from digitized ultrasonic acquisitions has been assessed. The images of 75 lesions, including 19 lesions proved to be malignant at histology and 56 found to be benign, were digitized and characterized by morphometric and texture parameters. The texture parameters, derived from first-order statistics, run-length matrices and co-occurrence matrices, were computed in the entire lesion and in a ring-shape region surrounding the contour of the lesion. The strongest features were found to be issued from the second region. Further investigations confirmed that the discriminant information was contained in the external part of the lesion and, to a lesser extent, in the neighboring tissue. A linear discriminant analysis using three features yielded a sensitivity of 94.7% for a specificity of 80.4% and the "leave-one-out" technique confirmed the results. Comparison with the classifications given by radiologists let us assume that information revealed by texture features is able to help the physician in reducing the number of unnecessary biopsies.

Breast Diseases↗
PubMed2000

Acute sinusitis: a histopathological and immunohistochemical study.

OBJECTIVE: To provide data on the histopathological and immunohistochemical characteristics of acute sinusitis in humans. STUDY DESIGN: A nonrandomized, retrospective, controlled, qualitative and quantitative study. METHODS: Inflamed sinus mucosal tissues were removed during functional endoscopic sinus surgery from 11 patients with acute sinusitis, of whom 6 had complications with extension of inflammation to the orbit (4) or the meninges (2), 3 had recurrent sinusitis, and 2 had acute exacerbation of chronic sinusitis Normal sinus mucosal tissues were retrieved from four patients with various nasal tumors and served as controls All specimens underwent routine histological processing. Representative sections from each region were stained with hematoxylin and eosin, periodic acid-Schiff, and toluidine blue. Immunohistochemical staining for T and B lymphocytes was also applied. A two-phase examination was designed: low-magnification microscopic assessment (x40) to yield the typical pathological features and high-magnification assessment (x400) to count various inflammatory cells. RESULTS: The lamina propria displayed the most significant changes with edema, extensive infiltration of neutrophils and mononuclear cells, formation of microabscesses, thrombophlebitis, and necrotic foci, whereas the involvement of the epithelial layer in the inflammatory reaction was relatively modest. Immunohistochemistry revealed an increase in the population of T and B lymphocytes. The former were diffusely scattered, whereas the latter also formed distinct clusters: around small venules, adjacent to seromucous glands, and under the epithelium. CONCLUSIONS: The inflammatory reaction of the lamina propria exceeded that of the epithelial layer. It is assumed that the clusters of B lymphocytes around blood vessels may point to the fact that these cells were recruited from the blood during acute sinusitis.

Acute Disease↗
PubMed2000

Histopathology of the inferior turbinate with compensatory hypertrophy in patients with deviated nasal septum.

OBJECTIVE: To measure the dimensions, composition, and possible structural and/or histopathological changes of the compensatory hypertrophic inferior turbinate in patients with deviated nasal septum. STUDY DESIGN: A prospective, nonrandomized, and morphometric study. METHODS: Nineteen patients with deviated nasal septum and compensatory hypertrophy of the inferior turbinate in the contralateral nasal cavity underwent surgery for correction of nasal obstruction. Patients' specimens were compared with those of a control group consisting of 10 inferior turbinates removed at autopsy. Quantitative measurements of the inferior turbinate histological sections were carried out and included the width of the layers and morphometric calculations of the relative proportions of the soft tissue constituents. Also, qualitative study was performed to detect pathological changes. RESULTS: Of all layers, the inferior turbinate bone underwent a twofold increase in thickness and manifested the most significant expansion (P < or =.001), whereas the contribution of the mucosal layers to the inferior turbinate hypertrophy was modest. The morphometric analysis revealed a larger proportion of venous sinusoids in hypertrophic turbinates, but the difference was small and statistically insignificant. Qualitative assessment disclosed normal mucosal architecture in all inferior turbinates with compensatory hypertrophy. Eleven remained intact, while eight disclosed mild to moderate pathological changes. CONCLUSIONS: The data gathered in the present study are of importance to the decision-making process regarding turbinate surgery. The significant bone expansion and the relative minor role played by the mucosal hypertrophy would support the decision to excise the inferior turbinate bone at the time of septoplasty.

Adolescent↗
PubMed2000

In vitro measurement of the frequency-dependent attenuation in cancellous bone between 0.2 and 2 MHz.

Our goal was to evaluate the frequency dependence of the ultrasonic attenuation coefficient in cancellous bone. Estimates were obtained in immersion, using a substitution method in the through-transmit mode, by scanning 14 human bone specimens (calcaneus). Measurements were performed with three pairs of focused transducers with a center frequency of 0.5, 1.0, and 2.25 MHz, respectively in order to cover an extended frequency bandwidth (0.2-1.7 MHz). When the experimental attenuation coefficient values were modeled with a nonlinear power fit alpha(f)=alpha0 +alpha(I)f(n), the attenuation coefficient was found to increase as f(1.09+/-0.3) over the measurement bandwidth. However, a substantial variation of the exponent n (0.4-2.2) within specimens and also between specimens was observed. The acoustical parameters were compared to bone mineral density. A highly significant relationship was noted between alpha1 and BMD (r2= 0.75, p< 10(-4)). No correlation was found between n and BMD. Several attenuation mechanisms are discussed as well as the potential impact these results may have in in vivo quantitative measurements.

Acoustics↗
PubMed2000

Analysis of the axial transmission technique for the assessment of skeletal status.

Ultrasonic wave propagation in human cortical bone has been investigated in vitro using the so-called axial transmission technique. This technique, which relies on velocity measurement of the first arriving signal, has been used in earlier investigations to study bone status during fracture healing or osteoporosis. Two quasi-point-source elements, one transmitter and one receiver (central frequency 0.5 MHz), were used to generate a wide ultrasonic beam, part of which strikes the sample surface at the longitudinal critical angle, and to receive the signals reflected from the sample surface. The analysis of the field reflected from a fluid-solid interface for an incident spherical wave predicts the existence of a lateral wave propagating along the sample surface at a velocity close to the longitudinal velocity, in addition to the ordinary reflected wave and vibration modes. The transducer-sample and the transmitter-receiver distances were chosen such that the lateral wave is the first arriving signal. Validation of the measuring technique was performed on test materials and was followed by experiments on human cortical bones. Experimental results (arrival time and velocity) strongly suggest that the first detected signal corresponds to the lateral wave predicted by theory.

Bone Density↗
PubMed2000

Frequency dependence of ultrasonic backscattering in cancellous bone: autocorrelation model and experimental results.

The goal of this study is to model the frequency dependence of the ultrasonic backscatter coefficient in cancellous bone. A twofold theoretical approach has been adopted: the analytical theoretical model of Faran for spherical and cylindrical elastic scatterers, and the scattering model for weakly scattering medium in which the backscatter coefficient is related to the autocorrelation function of the propagating medium. The ultrasonic backscatter coefficient was measured in 19 bone specimens (human calcaneae) in the frequency range of 0.4-1.2 MHz. The autocorrelation function was computed from the three-dimensional (3D) microarchitecture measured using synchrotron radiation microtomography. Good agreement was found between the frequency dependence of the experimental (f3.38+/-0.31) and autocorrelation modeled (f3.48+/-0.26) backscatter coefficients. The results based on Faran theory (cylindrical Faran model: f2.89+/-0.06 and spherical Faran model: f3.91+/-0.04) show qualitative agreement with experimental data. The good prediction obtained by modeling the backscatter coefficient using the autocorrelation function of the medium opens interesting prospects for the investigation of the influence of bone microarchitecture on ultrasonic scattering.

Aged↗
PubMed2000

Multiparametric attenuation and backscatter images for characterization of carotid plaque.

The goal of this study was to develop methods for quantitative ultrasound imagery suitable for noninvasive assessment of carotid plaque composition prior to the selection of the technique for revascularization. Using two broadband transducers (5-12 MHz and 12-28 MHz), backscattered radio frequency signals were acquired from entire lengths of 15 carotid endarterectomy specimens. Spectral analysis methods with correction for system response and beam diffraction were applied to radio frequency signals from local volumes of plaque having a 2 mm slice thickness, 1 mm width and axial depth of 480 microm and 240 microm at 10 MHz and 20 MHz, respectively. From these spectra, local values of four ultrasound parameters (integrated backscatter, frequency dependence of backscatter, integrated attenuation and slope of attenuation) were estimated and used to construct quantitative images. To combine information from these different parameter images, a two-step approach was followed. First, in 59 independent quantitative images of highly stenotic plaque, the average parameter values in a central five-by-three pixel region were correlated with plaque composition as assessed by histology to investigate the relationship between parameter values, frequency bandwidth and plaque composition. Discriminant analysis of parameter values vs. plaque composition was made to find a set of predictive equations to classify sets of measurements. Correct classification was obtained for 100% of calcified, 75% of intraplaque hemorrhage and 71% of lipidic plaques of the input data set. Second, each set of pixels from different parameter images was classified using the predictive equations, and a single, local tissue composition image was constructed. Examples of tissue composition images are presented in comparison with corresponding histologic sections. Both agreement and disagreement between image pairs are discussed.

Carotid Artery Diseases↗
PubMed2000

Evaluation of error bounds on calcaneal speed of sound caused by surrounding soft tissue.

For absorptiometry measurements, soft tissue may have an impact on quantitative ultrasound (QUS) measurements. In the present study, we focused primarily on the quantification of measurement error on speed of sound (SOS) caused by surrounding soft tissue. The relevant soft tissue parameters affecting the inherent SOS inaccuracies are thickness and sound velocity. To meet our goal, SOS measurements were taken at the right heel using a QUS imaging device in 21 healthy subjects. Site-matched measurements of soft tissue thickness (STT) and bone width were performed using magnetic resonance imaging of the heel. Several bone velocities were calculated either by accounting for bone width (SOSBW) only or by taking into account the exact path lengths of all major components traversed by ultrasound &lapr;V(b)). Given that soft tissue composition is difficult to determine in vivo, we chose to estimate lower and upper error bounds on bone velocity (V(b lower) and V(b upper)) by spanning the full range of available values in the literature. The mean BW was 30.7 +/- 2.7 mm and the mean medial and external STTs were 8.8 +/- 1.7 and 8.5 +/- 1.5 mm, respectively. Accounting for true BW only resulted in no significant difference between SOS (1533 +/- 37) and SOSBW (1531 +/- 33). By contrast, accounting for both true BW and surrounding soft tissue resulted in an increase in the calculated bone velocity and statistically significant differences between SOS and V(b upper) (1568 +/- 36) and V(b lower) (1542 +/- 34). Root mean square errors between SOS and the calculated velocities were 0.34, 2. 32, and 0.70% for SOSBW, V(b upper), and V(b lower), respectively. We report here measurement errors caused by soft tissue to be 3 to 20 times higher than the SOS short-term precision (SOS coefficient of variation of 0.1%). Our results suggest that inaccuracies in SOS measurement caused by overlying soft tissue cannot be neglected. Overlying soft tissues may influence outcomes of longitudinal studies, especially if variations in tissue thickness and composition occur during the longitudinal follow-up. A practical way of minimizing the measurement error could be to perform an adequate correction for the overlying soft tissue. However, ideally, this should require knowing both the thickness and sound velocity in soft tissue. One might preferably conduct experimental investigations that directly control soft tissue thickness and composition to resolve this problem.

Adult↗
PubMed1999

Histopathologic changes of the soft palate after laser-assisted uvulopalatoplasty.

OBJECTIVE: To assess late histopathologic changes of the soft palate after laser-assisted uvulopalatoplasty in patients with snoring and mild obstructive sleep apnea. DESIGN: A nonrandomized, histopathologic controlled study. SUBJECTS AND INTERVENTIONS: Palatal surgical specimens were removed from 10 patients with snoring and obstructive sleep apnea in whom laser-assisted uvulopalatoplasty was not successful and who subsequently underwent uvulopalatopharyngoplasty. The mean interval between the last laser treatment and uvulopalatopharyngoplasty was 24 months. The patients' specimens were compared with those of a control group consisting of 12 palates and uvulae excised during uvulopalatopharyngoplasty. RESULTS: After laser-assisted uvulopalatoplasty, all soft palates displayed marked and progressive pathologic changes that increased with every additional treatment and extended far beyond the point of laser beam application. The loose connective tissue present in the lamina propria was replaced by diffuse fibrosis, which also extended to the central layer, on the expanse of seromucous glands and muscle fibers. Other changes included ulceration of the oral epithelium and a patchy inflammatory reaction. CONCLUSIONS: Extensive thermal-induced changes, involving the 3 layers of the organ, were found. They are compatible with clinical observations reported elsewhere and are probably responsible for the worsening of the obstructive sleep apnea status and the sensation of the pharyngeal dryness that developed months after the laser-assisted uvulopalatoplasty. Although it has immediate benefits, the procedure is still relatively new and all its implications are as yet unknown.

Adult↗
PubMed1999

Ultrasound measurement on the calcaneus: influence of immersion time and rotation of the foot.

The aim of this study was to evaluate the influence of immersion time and rotation of the heel around the leg axis on the reproducibility of measurements using an ultrasound bone imaging scanner (UBIS) with a temperature-controlled water bath. Measurements were obtained in 10 men, 11 premenopausal women and 10 postmenopausal women. The right foot of all subjects was scanned 12 times with an interval of 3 min between each scan. The first 10 measurements, performed to study the effect of immersion time, were taken without intermediate repositioning. Measurements 11 and 12 were also taken without removing the foot, but the calcaneus position was varied by an angle of +/-2.5 degrees with respect to the reference position used during the first 10 measurements. Prolonged immersion of the heel led to a decrease in the variations of quantitative ultrasound (QUS) parameters between successive measurements. Following rapid variations with immersion time, the QUS parameters reached a plateau. The effect of immersion time on measurement error remained significant until the first two or three scans for broadband ultrasound attenuation (BUA) and until the sixth or seventh scans for speed of sound (SOS). The variation in BUA was more pronounced (p<0.05) for the group of postmenopausal women (20. 7% change in BUA between the first and tenth scans; p<0.005) than for the group of premenopausal women (6.8% change in BUA between the first and tenth scans; p<0.005). The variations in SOS were similar in the two groups (0.8% variation; p<0.005). The impact of immersion time was smaller for men than for women [2.5%, (p<0.01) and 0.4% (p<0.005) of the change between the first and tenth scans for BUA and SOS respectively]. On the whole, the measurement errors due to rotation of the heel were lower than those caused by immersion time. The variations were significant only in men and premenopausal women. Both immersion time and rotation of the heel may play a role in the precision of QUS and should be carefully standardized, particularly for longitudinal studies. In addition, following these results we have adopted a standardized protocol to derive the technique reproducibility in groups of premenopausal and postmenopausal women. The coefficients of variation were 1.1% for BUA and 0.1% for SOS in premenopausal women, and 1.4% for BUA and 0.13% for SOS in postmenopausal women.

Adult↗
PubMed1999

Diversity within natural progenies of the grapevine dieback fungus Eutypa lata.

The diversity within 16 natural progenies of the grapevine dieback fungus, Eutypa lata, was investigated by sampling single-ascospore isolates mainly in France and using random amplified polymorphic DNA (RAPD) markers, vegetative compatibility (VC), and pathogenicity testing. The combination of RAPD and VC data identified each isolate as a unique genotype within each progeny. Only three RAPD haplotypes did not cluster within the expected groups, i.e. the ascospore families. Within each set of clustering haplotypes, Mendelian 1:1 ratios for absence and presence were observed for RAPD markers, indicating that each progeny was the result of a biparental cross. Only one mycelium was obtained when isolation was performed from the discolored wood sustaining the perithecial stroma. This mycelium was identified as a likely parent of the corresponding progeny by RAPD analysis. The level of diversity measured by the average distance between haplotypes calculated from RAPD data, the percentage of vegetatively compatible pairs and the range of pathogenicity appeared similar between all but one progeny, indicating that crosses occurred within a random-mating population. All the results were consistent with the hypothesis that E. lata is a random-mating species having a high degree of genetic diversity.

Ascomycota↗
PubMed1999

Diagnostics and surgical treatment strategy for rectal cavernous hemangiomas based on three case examples.

A 20-year-old man with a congenital vascular malformation extending from the anal canal into the distal sigmoid had had recurrent perianal blood loss as a neonate. A hemangioma was diagnosed for the first time in 1978. The patient received regular and frequent gastroenterological treatment until admission. Decisive for the indication for surgery was the patient's need for blood infusions and shorter bleeding intervals in June 1998. Surgical therapy consisted of deep anterior rectosigmoid resection with coloanal pouch anastomosis. In a second case of a 27-year-old woman a sigmoid hemangioma was diagnosed in conjunction with emergency sigmoid resectioning. Because of recurrent hemorrhages a coloanal pouch was also established here in a second step. The third case involved a 19-year-old woman with a 12-year history of repeated perianal hemorrhages. After sigmoid discontinuity resection we carried out proctectomy with descendostoma creation due to renewed severe intractable perianal bleeding. The histological examination revealed a rectal hemangioma that had caused the repeated perianal hemorrhages. Surgical reconstruction was then achieved by coloanal pouch anastomosis. In view of the good functional and perioperative results, current surgical therapy should aim at preserving continuity and continence by coloanal pouch anastomosis.

Adult↗
PubMed1999

Tissue engineering of biphasic joint cartilage transplants.

In isolated posttraumatic or idiopathic joint defects the chondral layers and adjacent subchondral spongy bone are usually destructed. For regeneration we suggest the in vitro formation of a cartilage-coated biomaterial carriers (biphases) in order to fill the correspondingjoint defects. In this study Biocoral, a natural coralline material made of calcium carbonate, and calcite, a synthetic calcium carbonate, were used as supports for the cultivation of bovine chondrocytes in a three-dimensional polymer fleece. The cell-polymer-structure was affixed to the biomaterial with a fibrin-cell-solution. The artificial cartilage formed a new matrix and fused with the underlying biomaterial. The results indicate a promising technical approach to anchor tissue engineered cartilage in joint defects.

Animals↗
PubMed1999

Fatigue strength of locking screws and prototypes used in small-diameter tibial nails: a biomechanical study.

BACKGROUND: One major problem with the use of small-diameter nails in the treatment of tibial fractures is the high rate of fatigue fractures of the locking screws. The objective of this study was to correlate such parameters as diameter of locking screws, influence of notch effect, and material with fatigue strength and fatigue limit. METHODS: In a biomechanical study, the mechanical properties of 11 different locking screws and screw designs to be used in solid tibial nails were tested under typical fatigue conditions. RESULTS: The results showed that an increase in the screw's diameter significantly increased the fatigue strength of the tested locking screws and prototypes (p < 0.0005). A 20% increase of diameter improved fatigue strength by 25 to 70%. Absence of thread at the location where the screw contacts the nail's aperture (where the main load is transmitted to the screw and where the screw, therefore, usually tends to break) may double the fatigue strength and fatigue limit by avoiding the negative notch effect of the screw's thread. It was further significant that titanium alloys had a higher fatigue strength compared with stainless steel alloys (p < 0.001). However, the fatigue strength of titanium implants is massively reduced by minimal damage to the surface. CONCLUSION: Optimizing the core diameter of the locking screws at the aperture of the solid tibial nail by using screws without a continuous thread generates a fatigue strength two to three times higher compared with screws with a continuous thread. Increasing fatigue strength of locking screws might decrease malunion in fractures stabilized by small-diameter nails.

Biomechanical Phenomena↗
PubMed1999

[Non-invasive imaging of atherosclerosis by MRI and ultrasonography].

The concept of the unstable, so-called "high risk" or vulnerable atheromatous plaque has been accepted for several years and its biological, mechanical and cellular features (collagen top, lipid core with macrophages, metalloproteinases...) have been determined. However, the means of investigating these lesions remain limited. A description of their composition has become essential as the prognosis of coronary, aortic and carotid artery disease is no longer evaluated only by morphometric data (degree of stenosis). MRI with T1 or T2 contrast sequences, density of spin, chemical shift, diffusion, magnetisation transfer or spectroscopy provides a non-invasive tool for their study. This method, based on the detection of magnetic atomic nuclei (such as proton H1, carbon 13, sodium 23, potassium 49) enables tissue characterisation by means of the variations in chemical environment and their consequences on the degree of magnetisation of the nuclei studied. High frequency ultrasound could also be used to this end by measuring the coefficients of attenuation and back-scattering. These methods, used clinically and in different animal models, should improve our understanding of the physiopathology, facilitate diagnosis and improve the prognostic accuracy in patients with atherosclerosis.

Arteriosclerosis↗
PubMed1998

P-Selectin and platelet clearance.

P-selectin is an adhesion receptor for leukocytes expressed by activated platelets and endothelial cells. To assess a possible role of P-selectin in platelet clearance, we adapted an in vivo biotinylation technique in mice. Wild-type and P-selectin-deficient mice were infused with N-hydroxysuccinimido biotin. The survival of biotinylated platelets was followed by flow cytometry after labeling with fluorescent streptavidin. Both wild-type and P-selectin-deficient platelets presented identical life spans of about 4.7 days, suggesting that P-selectin does not play a role in platelet turnover. When biotinylated platelets were isolated, activated with thrombin, and reinjected into mice, the rate of platelet clearance was unchanged. In contrast, storage of platelets at 4 degreesC caused a significant reduction in their life span in vivo but again no significant differences were observed between the two genotypes. The infused thrombin-activated platelets rapidly lost their surface P-selectin in circulation, and this loss was accompanied by the simultaneous appearance of a 100-kD P-selectin fragment in the plasma. This observation suggests that the platelet membrane P-selectin was shed by cleavage. In conclusion, this study shows that P-selectin, despite its binding to leukocytes, does not mediate platelet clearance. However, the generation of a soluble form of P-selectin on platelet activation may have biological implications in modulating leukocyte recruitment or thrombus growth.

Aging↗