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Biomedical subjects

G Berger

Publications and source records attributed to G Berger.

At least 145 records · Page 8Linked to original sources
PubMed1990

[Reproducibility of ultrasound criteria for characterizing carotid artery stenoses].

Comparisons with intraoperative findings suggest that Duplex scanning may be of value in predicting the morphology of carotid artery stenoses. Such studies, however, are based on the results obtained by experienced investigators. To clarify whether sonographic criteria can be standardized, 6 investigators from different hospitals each documented 30 carotid artery stenoses of greater than or equal to 40% diameter reduction which could be imaged in at least 2 planes. Three sonographic criteria (plaque surface, echo density, echo structure), each with 8 categories, were assessed from the image documentations by the 6 as well as by 2 independent further investigators. Depending on the experience and on the device used 29-81% of all stenoses greater than or equal to 40% examined in the different laboratories could be included in the study. The +/- 1 category concordance between the different investigators averaged 50-60% for all sonographic criteria independent from the degree of stenosis and from the image quality. Because of lack of sufficient reproducibility the subjective assessment of sonographic criteria is found to be not suitable for use in multicentre studies.

Brain Ischemia↗
PubMed1990

Global breast attenuation:control group and benign breast diseases.

This paper deals with the estimation of the slope of attenuation in human breast tissue. The measurement is done in the reflection mode with a short time Fourier analysis. All important factors such as diffraction effect, tissue depth and specular reflectors are taken into account. A population of 49 normal women shows large inter-individual variations of the attenuation coefficient. A multiple linear regression allows correlation of this variation with the duration of the woman's genital life and pregnancies. A preliminary study is done on 10 benign diffuse breast diseases and shows a weak correlation with the type of the breast: normal or pathological. The utility of the quantification is discussed for one case of large fibrocystic disease.

Adult↗
PubMed1989

Storage and degradation of secretory proteins in adenomatous and secondary hyperplastic parathyroid cells. An immunoelectron microscope study.

Parathyroid hormone (PTH) and chromogranin A/secretory protein-I (SP-I) have been localized on immunoelectron microscopy in double-fixed tissues from adenomatous and secondary hyperplastic parathyroid glands. Storage organelles, identified on the basis of their consistent labelling, included tow morphologically distinct varieties of granules/vesicles; the mature granules and the progranules. The former consisted of dense, mostly rounded, medium to large-sized bodies which were strongly labelled and predominant in the proximity of the cell membrane. The other variety of body included a spectrum of small pale vesicles/granules which were mainly located in the Golgi area. Because their morphology and their labelling pattern varied other bodies were assumed to be engaged in degradation or cleavage of the secretory proteins. These bodies comprised crinophagic structures, that is to say multivesicular bodies and large Golgi-related vesicles, as well as a number of atypical solid bodies. Whereas most of the granulated cells stored a mature or a maturing population of vesicles/granules, the process of maturation appeared to be either absent or incomplete in a number of cells from some glands. The major defects were frequently associated with an unusual labelling pattern of the Golgi area and selectively affected groups of cells from all the transitional oxyphil cell adenomas. The minor defects concerned individual cells of different types present in both categories of glands. The present data suggest that in hyperfunctioning glands, the type of hormone processing depends on the capacity of each cell in progranule maturation and that the maturation capacity may decrease dramatically in adenomatous or chronically hyperstimulated cells of the transitional oxyphil type.

Adenoma↗
PubMed1989

Nature of spontaneous tympanic membrane perforation in acute otitis media in children.

The study was undertaken to define the characteristics of spontaneous eardrum perforation in acute otitis media. Eighty (29.5 per cent) out of 271 children with acute otitis media had eardrums which perforated. An increased incidence of perforation was associated with a previous history of otitis media. All perforations were small and limited exclusively to the pars tensa. In 85 per cent of the patients, the perforation was located in the anterior-inferior quadrant. It had smooth margins enabling free drainage of pus-and was associated with a favourable clinical course. In the remaining 15 per cent of the cases, the perforation was located in the posterior-superior quadrant. It had a nipple-like shape with a tiny opening that did not allow pus to drain sufficiently from the middle ear. The perforation closed in 94 per cent of the patients within one month. The healing process was gradual and following perforation closure, there was evidence of middle ear effusion for some time before normal aeration was regained.

Acute Disease↗
PubMed1989

[Neuroborreliosis: progressive encephalomyelitis with cerebral vasculitis].

Encephaloborreliosis is described in a 16 year old patient. Besides the progressive encephalopathy this case presents symptoms and findings of a cerebral vasculitis. During and after antibiotic treatment all clinical symptoms and pathological changes in the cerebrospinal fluid almost completely disappeared.

Adolescent↗
PubMed1989

[The significance of Ilmaplant as a bone substitute with reference to prostaglandin biosynthesis in bones. An animal experiment-clinical study].

The paper pointed out the resorbable material Ilmaplant-R and the glass ceramic Ilmaplant-L which are used for bone substitution. X-ray, histomorphometric and total mineral contents study were carried out in the region of healing defects in the tibia of 60 male white wistar rats. The healing response of the two bioceramics was compared 12 weeks after implantation. The inductive properties of prostaglandins were discussed. The possibilities of clinical application of Ilmaplant-R were demonstrated on the basis of short-term results up to 12 months.

Animals↗
PubMed1988

Characterization of six nucleotide-binding sites on chloroplast coupling factor 1 and one site on its purified beta subunit.

By using gel filtration chromatography, following the technique of Hummel and Dreyer (Hummel, J., and Dreyer, W. (1962) Biochim. Biophys. Acta 63, 532-534), the adenine nucleotide-binding sites of isolated soluble chloroplast ATPase (CF1) and of the beta subunit were studied. CF1 possesses six adenine nucleotide-binding sites: two high affinity sites for ADP or ATP (KdH = 1-5 microM) in addition to one site where endogenous not-exchangeable ADP is bound, and three low affinity sites binding ADP or ATP with a dissociation constant (KdL = 15-20 microM) which is considerably increased in the presence of pyrophosphate. KdH is not modified by addition of pyrophosphate. The stability of nucleotide binding at the low affinity sites increases after heat activation of CF1. Removal of the delta or epsilon subunits on CF1 affects neither the number nor the binding parameters of the nucleotide-binding sites. The purified beta subunit possesses one easily exchangeable site/subunit. It is proposed that the low affinity sites on CF1 are the catalytic sites.

Adenosine Diphosphate↗
PubMed1988

AsnI: a novel class II restriction endonuclease from Arthrobacter sp., strain N-CM, recognizing 5'-AT/TAAT-3'.

A new class II restriction endonuclease, AsnI, with a novel sequence specificity was isolated from the Gram-positive eubacterium Arthrobacter species, strain N-CM. AsnI recognizes the unambiguously defined palindromic hexanucleotide (Formula: see text) consisting of A- and T-residues. The novel enzyme in the presence of Mg2+ cleaves specifically both strands as indicated by the arrows. The staggered cuts generate 5'-protruding ends with single-stranded 5'-TA-3' dinucleotide extensions. The novel enzyme may be a useful tool for cloning experiments by complementation of the few enzymes such as PstI and PvuI cutting only once in the Ampr-gene of plasmids pBR322 and pBR328.

Arthrobacter↗
PubMed1988

Electron microscope localisation of insulin-like immunoreactivity of conventionally processed human insulinomas.

Localisation of insulin-like immunoreactivity has been studied using the immunogold staining procedure on thin sections of 6 human insulinomas, conventionally processed for electron microscopy. The labelling was restricted to the secretory granules. Depending on their morphology, these either resembled B-cell granules of human adult pancreas or belonged to the atypical (non-diagnostic) group. Within the former group, those with a crystalloid core or an amorphous dense or moderately dense core were strongly immunoreactive, whereas others, filled with a pale material, were poorly labelled. Most granules of this type were stored together within the heavily granulated cells of 3 insulinomas, presenting the classical features of clinical and biological behaviour and a typical light microscopic staining pattern. In contrast, the non-diagnostic granules, characterized by their smaller size, a very dense core and a thin halo, were mainly found within the poorly granulated cells making up the other tumours, and showed a very uneven labelling. Strongly labelled granules were found in one insulinoma that also belonged to the classical type; these were stored together with a few diagnostic granules within the same cells. Only poorly labelled atypical granules were present in two cases revealing a number of unusual features; these included moderate elevation of insulinaemia, uncertain tumour histology, as well as weak immunostaining for insulin/proinsulin and variable argyrophilia of the tumour in paraffin sections. These findings suggest that human insulinomas differ not only in storage capacity but also in their degree of granule maturation. This may involve some deficiency of either the prohormone conversion or the subsequent processing of the cleavage products.

Adenoma, Islet Cell↗
PubMed1988

Calcitonin-like immunoreactivity of amyloid fibrils in medullary thyroid carcinomas. An immunoelectron microscope study.

Using 3 polyclonal antisera directed against synthetic human calcitonin, we investigated at the electron microscope level the intra-or-extra-cellular fibrillar/filamentous aggregates found in 4 amyloid-rich medullary thyroid carcinomas (MTC) and in a number of other endocrine polypeptide tumours with or without demonstrable amyloid deposition. The antisera were applied by the immunogold procedure on ultrathin sections of glutaraldehyde-fixed, usually osmium-postfixed, tissues. In MTC cases, a strong labelling was present over two types of aggregates: one composed of rigid, criss-crossing fibrils 7-10 nm in diameter, suggestive of amyloid, and the other consisting of loosely arranged fibrils, 4-7 nm in width, often wavy or poorly defined. In both cases, the labelling was closely associated with that part of the sectioned fibril exposed to the antiserum. Amorphous material was sometimes present adjacent to the later aggregates, but did not bind the calcitonin antibodies. In contrast, no labelling occurred over the amyloid deposits found in two non-calcitonin-producing endocrine tumours of the pancreas, nor over the cytoskeletal filaments stored in various endocrine polypeptide tumours. The specific value of the labelling for calcitonin-like immunoreactivity was assessed by control tests, such as absorption of the antiserum by excess calcitonin and comparative use of normal serum and antisera directed against human IgG and P component. No immunoreactivity of the MTC amyloid fibrils was found using antibodies directed against katacalcin and human prealbumin. We conclude that in tumour tissues conventionally processed for electron microscopy, MTC amyloid fibrils of varying morphology can be selectively and specifically labelled for calcitonin-like immunoreactivity.

Amyloid↗
PubMed1988

[Regeneration of the liver under the influence of E. coli endotoxin].

Studies were conducted into regeneration of rat liver exposed to the action of E. coli endotoxin, following two-third resection. No accelerated regeneration was found to take place in the wake of two-third hepatectomy and following postoperative intraperitoneal administration of E. coli endotoxin. However, regeneration was accelerated with significance in response to preoperative administration of 0.1 mg/kg body weight of E. coli endotoxin (B 5:55 DIFCO).

Animals↗
PubMed1988

[Peri-implantation enzymes and mineralization in bone tissue after implantation of bioactive vitroceramic material--a method for biomaterial testing for hard tissue substitutes. 2. Results of studies of vitroceramics and their modification by the admixture of metal oxides].

The activities of the alkaline and the acid bone phosphatases as well as the concentrations of calcium and phosphorus were measured in the periimplantal tissue of the rat femur bone after implantation of the vitroceramic Ap 40, the metal oxide stabilized vitroceramics Ap 40 A and Ap 40 Z, as well titanium after 2, 10, and 15 weeks. The incorporation of the vitroceramic Ap 40 turns out like a primary bone fracture healing. The implants Ap 40 A and Ap 40 Z are a compromise with a higher stability and the osteogenesis induced effect is preserved, but is belated in contrast to Ap 40.

Acid Phosphatase↗
PubMed1987

Biochemical and proton NMR characterization of the isolated functional beta-subunit of coupling factor one from spinach chloroplasts.

Beta subunits have been dissociated from CF1 of spinach chloroplasts, purified by HPLC and characterized by two-dimensional electrophoresis and fluorescence emission. The solutions of isolated beta subunits are able to hydrolyze MgATP; this ATPase activity is an intrinsic property of the beta molecule. From proton NMR at 300 and 500 MHz, it is shown that the preparations are fully reproducible and that beta subunits remain monomeric with 75% aliphatic protons associated with rigid parts of the molecule. The other 25% give rise to separate resonances and belong to mobile side-chains and/or to flexible regions. The measurement of the transverse relaxation times T2 has permitted a detailed characterization of the molecular dynamics of the isolated beta subunits.

Chloroplasts↗
PubMed1987

Detection of Duchenne muscular dystrophy carriers: quantitative echography and creatine kinasemia.

Data obtained from simultaneous determinations of serum creatine-kinase levels and estimation of ultrasound attenuation values in muscles greatly improved the detection of obligate carriers of Duchenne muscular dystrophy than when only one of these methods was employed alone. Eleven carriers out of 19 had a high creatine-kinasemia level and nine carriers out of 19 had a high (abnormal) attenuation value. Because of the limited overlapping between the two parameters studied, we were able to recognize 17 obligate carriers out of the 19. This indicates that the parameters studied concern different features of the disease, and the practical and theoretical considerations are discussed. The techniques are discussed together with molecular genetic investigations.

Adult↗
PubMed1987

Optimal precision in ultrasound attenuation estimation and application to the detection of Duchenne muscular dystrophy carriers.

This paper deals with the measurement of the attenuation of ultrasound in muscle and its application to the detection of Duchenne Muscular Dystrophy (DMD) carriers. The precision obtained when measuring the attenuation is an important parameter to be considered. A statistical approach is taken on simulated data and compared to in vivo results. The results allow discussion for the minimum tissue volume needed for the estimation. Variations in muscle attenuation between normals were obtained from studies on 27 volunteers. These attenuation values were compared to those obtained from 19 carriers of DMD. Attenuation appears to be a potential clinical indicator of DMD carriers.

Biometry↗
PubMed1987

Diffraction correction for focused transducers in attenuation measurements in vivo.

Diffraction effects are a cause of error when estimating the frequency dependent attenuation of ultrasound in biological tissues in the reflection mode. Comparison of attenuation values estimated in vivo by different investigators using different types of transducers makes calibration and correction for diffraction necessary. In this paper, we present experimental results for in vivo calibration and correction for the diffraction effect for focused transducers. We also study numerically the diffraction filter in a time-frequency representation, and show that for a focused probe, there is a region in the time-frequency domain where the frequency slope of the diffraction filter does not vary with time. The main consequence for in vivo estimation is that for a given probe, it is possible to select both the distance between the region of interest and the probe, and the frequency limits, such that the attenuation thus estimated is unbiased by the diffraction effect. This result, obtained by numerical calculations, is confirmed by experimental calibration of a foam phantom and in vivo muscle.

Acoustics↗