Biomedical subjects

G Berger

Publications and source records attributed to G Berger.

At least 91 records · Page 5Linked to original sources

PubMed1997

Solubility of compositions in the system CaTi(x)Zr4-(x)(PO4)6 with x = 0-4.

In vitro solubility tests of granulated materials and coatings were carried out on some compositions in the system CaTi(x)Zr4-(x)(PO4)6 with x = 0-4, in order to find a biocompatible material which is less soluble than hydroxyapatite (HA) and can also be used as bone substitution material. The granulated materials were leached out by using circulating equipment in which the solvent flows in circulation. The coatings were tested under conditions where the sample containers undergo a circular movement. The results show better chemical stability of nearly all tested compounds compared with HA for both granulated materials and coatings.

Biocompatible Materials↗

PubMed1997

Parametric (integrated backscatter and attenuation) images constructed using backscattered radio frequency signals (25-56 MHz) from human aortae in vitro.

Quantitative ultrasonic tissue characterization using backscattered high-frequency intravascular ultrasound could provide a basis for the objective identification of lesions in vivo. Representation of local measurements of quantitative ultrasonic parameters in a conventional image format should facilitate their interpretation and thus increase their clinical utility. Toward this goal, the apparent integrated backscatter, the slope of attenuation (25-56 MHz) and the value of the attenuation on the linear fit at 37.5 MHz were measured using the backscattered radio frequency signals from in vitro human aortae. Local estimations of these ultrasonic parameters from both normal and atherosclerotic aortic segments were displayed in a B-scan format. The morphological features of these parametric images corresponded well to features of histological images of the same regions. The attenuation from 25-56 MHz of seven segments of the medial layer (both with and without overlying atheroma) were measured using the multinarrow-band backscatter method. The average attenuation in the media at 24 degrees C +/- 3 degrees C was 45 +/- 16 dB/cm at 25 MHz and 102 +/- 13 dB/cm at 50 MHz. This work represents progress toward the development of quantitative imaging methods for intravascular applications.

Aorta, Thoracic↗

PubMed1997

Correlation of ultrasonic attenuation (30 to 50 MHz and constituents of atherosclerotic plaque.

The ultrasonic integrated attenuation and the slope of attenuation (30-50 MHz) were measured in vitro at 20 degrees +/- 2 degrees C using radio frequency signals backscattered from human aortae. Ultrasonic measurements and histologic classifications were made in a total of 124 local regions from 58 independent segments of aortae. Values of the integrated attenuation were significantly higher in collagen-lipidic (142 +/- 51 dB cm-1, n = 18), and lipidic regions (139 +/- 53 dB cm-1, n = 11) compared to regions of normal media (97 +/- 20 dB cm-1, n = 44) and dense collagen (107 +/- 33 dB cm-1, n = 43). The most elevated integrated attenuation values were observed in calcified regions (245 +/- 93 dB cm-1, n = 8). The slope of attenuation was significantly higher in lipidic than in normal media (p = 0.002), dense collagen (p = 0.0007) or collagenlipidic (p = 0.04) regions. The correlation between attenuation and local tissue composition was used to establish ranges of values of integrated attenuation that are most likely to indicate specific tissue types. Images of the local tissue type were constructed. Comparison of these quantitative images with the corresponding histologic sections demonstrates that attenuation measurements offer promise for the in vivo characterization of plaque structure and composition.

Aorta, Thoracic↗

PubMed1997

In vitro assessment of the relationship between acoustic properties and bone mass density of the calcaneus by comparison of ultrasound parametric imaging and quantitative computed tomography.

This in vitro study aimed to add new experimental evidence to clarify the relation between acoustic properties of bone and bone mineral density (BMD) of the human calcaneus. Parametric images of normalized broadband ultrasonic attenuation (nBUA) and ultrasound bone velocity (UBV) were compared with quantitative computed tomography (QCT) images of the calcaneus. The experimental protocol was designed to control the different potential sources of error in acoustic measurements, including the shape and thickness of the samples, intervening soft tissues and cortical bone, boundary effects, and variation in location of the regions of interest (ROIs) analyzed by ultrasound and X-ray. The present study was based on bone specimens from calcaneus removed from 15 cadavers (six male and nine female donors ranging from 69 to 89 years of age). Immersion ultrasonic measurements were performed in the through-thickness direction at normal incidence using a pair of focused broad-band 0.5-MHz transducers. QCT of the specimens was performed using standard 10-mm-thick slices with the Cann-Genant calibration standard. Identical, site-matched ROIs were selected for quantitative analysis on the three images. The pattern of acoustic parameters was similar to that of BMD with QCT. The relationships between nBUA and BMD (r2 = 0.75), between UBV and BMD (r2 = 0.88) and between nBUA and UBV (r2 = 0.84) were highly significant (p < 10(-4). From this study, it appears that ultrasound parameters as measured with current transmission techniques reflect mainly bone quantity and only reflect microarchitecture to a small extent and that BUA and UBV reflect the same bone property.

Acoustic Stimulation↗

PubMed1997

Revision myringoplasty.

This retrospective study was undertaken to review the short- and long-term results of 70 revision and 16 re-revision myringoplasty operations. Of the former, 43 cases (61.4 per cent) had initial success, six weeks following surgery. The leading causes of immediate failure (27 cases) were associated with a complete no-take of the graft, infection with graft necrosis and poor anterior adaptation of the graft in decreasing order. Six out of the 43 patients developed late re-perforations during the follow-up period, thus reducing the success rate of revision myringoplasty to 52.8 per cent. Late re-perforations were attributed to insidious atrophy of the tympanic membrane or episodes of acute otitis media. Sixteen patients underwent re-revision myringoplasty and their success rate was 62.5 per cent. The overall success rate of revision and re-revision myringoplasty was 54.7 per cent. It has been concluded that results of revision myringoplasty were independent of patients' age, location and size of perforation and the seniority of the surgeon.

Adolescent↗

PubMed1997

Patterns of hearing loss in non-explosive blast injury of the ear.

A prospective study of hearing loss in 120 cases with non-explosive blast injury of the ear, gathered over a six-year period, is presented. Thirty-three (27.5 per cent) patients had normal hearing, 57 (47.5 per cent) conductive hearing loss, 29 (24.2 per cent) mixed loss and one (0.8 per cent) had pure sensorineural loss. The severity of conductive hearing loss correlated with the size of the eardrum perforation; only a marginal difference was found between water and air pressure injuries, with respect to this type of hearing loss. Of all locations, perforations involving the posterior-inferior quadrant of the eardrum were associated with the largest air-bone gap. Audiometric assessment revealed that none of the patients suffered ossicular chain damage. Three patterns of sensorineural hearing loss were identified: a dip at a single frequency, two separate dips, and abnormality of bone conduction in several adjacent high frequencies. Involvement of several frequencies was associated with a more severe hearing loss than a dip in a single frequency. Healing of the perforation was always accompanied by closure of the air-bone gap, while the recovery of the sensorineural hearing loss was less favourable.

Adolescent↗

PubMed1997

Immunolocalization of the multi-sarco/endoplasmic reticulum Ca2+ ATPase system in human platelets.

We recently identified a multi-SERCA (sarco/endoplasmic reticulum Ca2+ ATPase) system in haemopoietic cells comprising the SERCA 2b, SERCA 3 and a new monoclonal anti-Ca2+ ATPase antibody (PL/IM 430) recognizable SERCA isoforms. We have now investigated the subcellular localization of these enzymes in human platelets by Western blotting of subcellular membrane fractions and by immunoelectron microscopy. We precisely defined the recognition specificity of the polyclonal anti-SERCA 2b, anti-SERCA 3, anti-SERCA 1 antibodies as well as of the monoclonal antibody PL/IM 430 by testing their recognition of the tryptic fragments of the SERCA isoforms. The analysis of fragmented membranes enriched in plasma membrane and intracellular membrane components by Western blotting showed that the SERCA 2b and the SERCA 3 isoforms were found in both the plasma membrane and the intracellular membrane fractions, whereas the PL/IM 430 recognizable SERCA isoform was restricted to membranes associated with the plasma membrane fraction. The immunoelectron microscopical study of the SERCA isoforms in resting platelets showed that: (i) the SERCA 2b isoform was expressed in membranes associated with the plasma membrane and open canalicular system, some alpha-granules and in unidentified membranes; (ii) the SERCA 3 isoform was found associated with plasma and intracellular membranes; and (iii) the PL/IM 430 recognizable SERCA isoform was observed only in structures associated with the cytoplasmic face of the plasma membranes, as confirmed by flow cytometry. Finally, since the PL/IM 430 antibody was raised against intracellular membranes, we looked for a potential membrane redistribution during the isolation procedure used for the preparation of the immunizing membranes. Neuraminidase treatment indeed induced a translocation of the PL/IM 430 recognizable SERCA isoform from plasma to intracellular membranes. Thus, the multi-SERCA system in platelets: (i) is distributed over different platelet membranes, (ii) presents a sub-compartmental organization with some overlapping, and (iii) is partly associated with motile membranes, reflecting an unrecognized level of complexity of Ca2+ stores in these cells.

Antibodies, Monoclonal↗

PubMed1997

Assessment of articular cartilage and subchondral bone: subtle and progressive changes in experimental osteoarthritis using 50 MHz echography in vitro.

The main objectives of this work were to demonstrate the potential of 50 MHz echography for assessing initial and progressive morphological and structural changes of articular cartilage and bone developed in an experimental model of osteoarthritis (OA). Degenerative lesions were induced in rat knees by the unilateral intra-articular injection of a 3 mg dose of mono-iodo-acetic acid. To assess the lesion progression, the animals (n = 30) were sacrificed at different time intervals up to 8 weeks after the injection. Three-dimensional echographic data were acquired in vitro on patellar cartilage and bone at various stages of the remodeling process using a scanning ultrasound microscope. Changes involving the OA cartilage characteristics are discussed relative to those of the contralateral control joint which received a placebo. Images of control cartilage showed a smooth hyperechoic articular surface and an echoic matrix. The cartilage thickness was 266 +/- 44 microns (mean +/- SD) in the central region of the tissue. The precision of ultrasonic thickness measurements was better than 1.3%. First changes in cartilage internal structure and subchondral bone appeared on ultrasound images 3 days after the injection and were even more evident by day 7. They resulted in a slight thinning of the cartilage, a 30% increase of its internal structure echogenicity, and the appearance of echoic zones in subchondral bone. Histologic findings confirmed chondrocyte depletion and degeneration, decrease of matrix proteoglycans, and fibrovascular connective tissue proliferation at the subchondral plate. Progressive and severe lesions at both bone and cartilage surface and internal structure were assessed and correlated to histologic features. These results show that high resolution echography is sensitive to subtle and progressive osteochondral remodeling. This technique has the potential to be used for intra-articular quantitative imaging and assessment of early changes in bone and cartilage structure associated with natural human disease.

Animals↗

PubMed1997

Liposome-encapsulated superparamagnetic iron oxide particles as markers in an MRI-guided search for tumor-specific drug carriers.

Three different types of liposomes containing superparamagnetic iron oxide particles (SPIOs) as the contrast agent were tested for intratumoral enrichment by magnetic resonance imaging (MRI). The liposome-encapsulated SPIOs were investigated in comparison with AMI-227, dextran-coated SPIOs in two different dosages using the CC531 adenocarcinoma in the liver of WAG/RIJ rats as a model. Reduction of the relative signal intensity (SI) in the tumor in T2-weighted MR images was assumed as a measure of the liposome enrichment in the tumor or adjacent tissue. The samples were tested at dosages with isomolar iron content and at dosages producing the same MR relaxivity R2. For reverse phase evaporation vesicles and small unilamellar vesicles behavior differed remarkably according to the applied dosage. A steady, strong reduction in SI, starting immediately after injection and extending up to 48 h, was observed for small unilamellar vesicles sterically stabilized with polyethylene glycol.

Adenocarcinoma↗

PubMed1997

[Prognostic factors in mesenteric infarct].

Between 1979 and 1995 we operated 141 (80 female/61 male) patients with acute mesenteric ischemia (AMI) in our department with a median age of 71.5 years. We found 107 arterial occlusions of the intestinal arteries, 16 patients with splanchnic vein thrombosis and 18 non-occlusive-AMI. We performed 46 bowel resections, 24 vascular interventions, 11 combinations of both and in 60 cases laparotomy alone. The mortality rate was 70.9% (75% in over 70 years old patients and 65% in under 70 years old patients). Acute mesenteric ischemia remains a disease with a high mortality between 60 and 80%. Prognostic factors include the time interval until surgical intervention, elevated WBC and serum-lactate level. The mortality rate is higher in elderly patients than in younger patients which is mainly due to delayed surgery in the elderly group. If surgery is performed early the survival rate increases independent of age. The most important prognostic factor and the only factor that can be influenced by the surgeon is the time interval between onset of symptoms and surgery. Therefore angiography or laparotomy should be performed as early as possible in cases of suspected AMI.

Adult↗

PubMed1997

Alcoholism and carcinoma change the intracellular pH and activate platelet Na+/H+-exchange in men.

The occurrence of carcinoma in chronic alcoholics exceeds that of the general population. Cytoplasmic alkalinization, due to the influence of different factors on the transmembrane Na+/H+ exchange (NHE), has been put forward as a triggering event in cell growth and division. In accordance with these findings, the carcinogenic potential of NHE deficient cell types is reported to be diminished. The aim of this study was to investigate whether the intracellular pH and the NHE activity is altered in chronic alcoholics. Seventy-two Caucasian males were assigned to one of four groups: non-alcoholics without carcinoma, chronic alcoholics without carcinoma, non-alcoholics with carcinoma and chronic alcoholics with carcinoma. Alcoholism was diagnosed according to DSM-III-R. The groups did not differ in relation to basic patient characteristics, such as age and blood pressure. Intracellular calcium, pH and NHE in platelets were determined by spectrofluorometry before and after thrombin stimulation. In chronic alcoholics with carcinoma, the intracellular pH was significantly more alkaline and the NHE activity was elevated. In contrast, a decrease in intracellular pH associated with an increased activity of NHE and a more acidic set point was found in chronic alcoholics without carcinoma. Basal and thrombin stimulated intracellular Ca2+ did not differ between groups except in chronic alcoholics with carcinoma in whom a thrombin-induced increase of Ca2+ due to liberation of Ca2+ from intracellular stores was demonstrated. In chronic alcoholics with carcinoma, cytoplasmic alkalinization was observed and this may be an indication of an increase in cell proliferation. The possibility that the increased incidence of carcinomas in chronic alcoholics is related to the increased activity of NHE and whether this may be prevented by NHE inhibitors requires further investigation.

Adult↗

PubMed1997

[Is routine tumor after-care after gastrectomy sensible?].

Only 22.3% of patients with recurrence after potentially curative gastrectomy are discovered in asymptomatic stages. Their prognosis is not different from those with symptomatic recurrence. Routine follow-up after gastrectomy can be abandoned.

Aftercare↗

PubMed1996

The cisternae decorating the red blood cell membrane in congenital dyserythropoietic anemia (type II) originate from the endoplasmic reticulum.

We studied 20 individuals from 17 unrelated families with congenital dyserythropoietic anemia (type II; CDAII). The clinical phenotype was mild to moderate. The inheritance pattern was invariably recessive. Coomassie blue stained gels after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) show that band 3 was thinner and migrated slightly faster than usual. In addition, staining showed two unknown minor bands (in the patients), but not in normal controls, the obligate carrier parents, or in patients with other anemic syndromes. These minor proteins were studied using partial digestion, amino acid sequencing, Western blotting, immunofluorescence, and immunogold electron microscopy. They were identified as the glucose-regulated protein GRP78 and calreticulin that are resident proteins of the endoplasmic reticulum (ER). Using specific antibody, we showed that protein disulfide isomerase (PDI), a third major protein of the ER, was also present on the SDS-PAGE of red blood cell (RBC) ghosts. Immunofluorescence colocalized PDI with the dense discontinuous ring decorating the RBC membrane. Immunogold electron microscopy showed that PDI was localized in the lumen of the cisternae, confirming that these originate from the smooth ER. From a practical point of view, screening the above minor proteins in RBC membranes appears to be a straightforward and reliable diagnostic test for CDAII.

Amino Acid Sequence↗

PubMed1996

Evaluation of efficient chemoembolization mixtures by magnetic resonance imaging therapy monitoring: an experimental study on the VX2 tumor in the rabbit liver.

To find effective chemoembolization mixtures, we tested combinations of carboplatin with the embolizates Spherex and Gelfoam in comparison to a therapy with NaCl-solution, a treatment with the cytostatic drug only, and a therapy with each of the embolizates alone. The experiments were carried out using as a model the VX2 tumor in the liver of male chinchilla rabbits (five for each group). Carboplatin was revealed by the 3-(4,5-dimethylthiazole-2)-yl-2,5-diphenyltetrazolium bromide test to be a potent cytostatic drug for VX2 rabbit tumor cells. We used magnetic resonance imaging to examine the tumor volume and signal intensity enhancement up to 15 min after Gd-DTPA administration within the tumor and liver before and after the different therapies. These parameters allowed us to evaluate tumor growth and vitality as well as liver injury for the different therapy types. The results found by magnetic resonance imaging corresponded very well to those obtained by histological analysis of the tumors. The chemoembolization therapies were significantly more efficient than the other therapies, as indicated by the reduction of signal intensity enhancement after contrast agent administration within the tumor and by the histologically determined necrotic fraction after therapy. In addition, we found a significant decrease of the tumor volume and no significant live injury for a therapy with Carboplat and Gelfoam.

Animals↗

PubMed1996

Alpha-granule membrane mirrors the platelet plasma membrane and contains the glycoproteins Ib, IX, and V.

We have recently shown that several components from the platelet plasma membrane were also present at different rates in the alpha-granule membrane. This is the case for the glycoprotein (GP) IIb-IIIa (CD41), CD36, CD9, PECAM1, and Rap1b, while the GPIB-IX-V complex was considered to escape the rule. In this investigation, we studied the subcellular localization of GPIb, GPIX, and GPV in the resting platelets of normal subjects, patients with Bernard-Soulier syndrome, patients with Gray platelet syndrome, and human cultured megakaryocytes. Ultra-thin sections of the cells were labeled with antibodies directed against glycocalicin, GPIb, GPIX, and GPV. We have shown that a significant and reproducible labeling for the three GPs was associated with the alpha-granule membrane, accounting for approximately 10% of the total labeling. Furthermore, GPIb labeling appears Willebrand factor (vWF). After thrombin activation, vWF remained close to the limiting membrane of the open canalicular system (OCS), suggesting an early association of both receptor and ligand. Plasma membrane and alpha-granule labeling was virtually absent from the Bernard-Soulier platelets (characterized by a GPIb deficiency), thus proving the specificity of the reaction. In Gray platelets (storage granule deficiency syndrome), the small residual alpha-granules were also occasionally labeled for GPIb, GPIX, and GPIX. Cultured megakaryocytes that displayed the classical GPIb distribution, eg, demarcation and plasma membranes, exhibited also a discrete labeling associated to the alpha-granules. In conclusion, this study shows that, evenly for these three GPs, the alpha-granule membrane mirrors the plasma membrane composition. This might occur through an endocytotic process affecting each plasma membrane protein to a different extent and could have a physiologic relevance in further presentation of a receptor bound to its alpha-granule ligand to the platelet surface.

Bernard-Soulier Syndrome↗

PubMed1996

Broadband ultrasound attenuation imaging: a new imaging method in osteoporosis.

The purpose of this study was to evaluate the usefulness in osteoporosis of a new ultrasound imaging device able to create a parametric image of broadband ultrasound attenuation (BUA) at the os calcis. Three regions of interest were located in the great tuberosity of the os calcis. Precision was evaluated in 37 patients. Calcaneal bone mineral density (BMD) and BUA were compared in 33 patients. In 236 patients (including 77 with osteoporotic fractures), BUA and lumbar and femoral BMD measurements were performed. The measurements were compared using correlation coefficients. Their clinical value was estimated by comparisons of the results between patients with fractures and age-matched controls, using comparisons of the means, areas under the ROC curves, and logistic regression. Precision was in a 1.4-3.3% range. Local BUA and BMD were highly correlated (r = 0.88). Significant correlations were found between BUA and lumbar (r = 0.56) and femur (r = 0.66) BMD. In multiple regression, years since menopause and weight were significant predictors of BUA. Patients with fractures had lower BUA and BMD than age-matched controls. BUA showed the largest difference between the two populations (13-16%). Areas under the ROC curves were similar for BUA and BMD. Logistic regression after adjustment for confounding factors showed that BUA discriminated between fracture and nonfracture subjects. Broadband ultrasound attenuation imaging improves the reproducibility of ultrasound measurements. It may be useful in osteoporosis, due to its good discriminating value.

Adult↗

PubMed1996

Familial non-syndromic conotruncal defects are not associated with a 22q11 microdeletion.

Molecular studies have shown microdeletions in region q11 of chromosome 22 in nearly all patients with DiGeorge, velocardiofacial and conotruncal anomaly face syndromes (DGS, VCFS and CTAFS, respectively) and in a high percentage of non-syndromic familial cases of conotruncal defects (CTD). CTD account for roughly a fourth to a third of all non-syndromic congenital heart defects (CHD), thus, 22q11 could harbor a major genetic factor of CHD. We searched for a 22q11 microdeletion in familial cases of non-syndromic CTD. Thirty-six cases of various isolated CTD, that is without history of hypocalcemia, immune deficiency, absent thymus, and dysmorphic appearance, were selected. With 48F8, a cosmid probe localized in the smallest deleted region of the DiGeorge critical region (DGCR), we found no deletions by fluorescence in situ hybridization in these 36 affected individuals of 16 families with recurrent CTD. Moreover, D22S264, a microsatellite localized at the distal part of the largest deleted region, was used to genotype the patients. Thirty-two patients out of 37 were heterozygous and hence not deleted at this locus, whereas 5 were uninformative. In conclusion, there are no large deletions in familial cases of various CTD, whether these defects are identical or not within a family. This result does not rule out other minor anomalies in this chromosomal region.

Adolescent↗

PubMed1996

Ultrasound parametric imaging of the calcaneus: in vivo results with a new device.

An ultrasound transmission scanning system was constructed to make in vivo parametric images of the acoustic properties of the heel. Broadband ultrasonic attenuation (BUA) images were obtained in transmit mode by using a pair of broadband focused transducers (center frequency 0.5 MHz, diameter 29 mm, focus 50 mm) immersed in a water bath at room temperature. With these characteristics, the theoretical beam width at the focus was approximately 5 mm. The total duration of the acquisition period was 3 minutes. Comparison of the BUA image and the radiograph of the calcaneus was possible in one case and showed that all the anatomical details could be identified. The images reported here demonstrate the wide range of BUA found in both the whole bone and within a ROI centered in the posterior part of the bone thus reinforcing the idea of tremendous heterogeneity of the acoustic properties of bone. This suggests that the accurate control of the position of the measurement site is of the utmost importance for between-subject comparison and for repetitive measurements. We proposed a new method, the likelihood image, as an efficient way of highlighting the regions of the image suspected to be subject to waveform distortion. It could be used to guide the selection of the optimal measurement site. Our results suggest that ultrasound parametric imaging has the potential for enhancing the current ultrasound technique by (1) allowing reproducible, repetitive measurements, (2) permitting the selection of similar optimal measurement sites in all subjects, and (3) avoiding accuracy errors due to waveform distortion.

Adult↗