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Biomedical subjects

G Mathis

Publications and source records attributed to G Mathis.

At least 55 records · Page 3Linked to original sources
PubMed1996

Incidence of extramural venous invasion in colorectal carcinoma: findings with a new technique.

In reported studies of extramural venous invasion (EVI) by colorectal carcinoma (CRC) in which conventional preparations involving a sectioning plane perpendicular to the tumor were used, an incidence as high as 36% has been found for unselected surgical material from patients operated on for cure. However, with this preparation technique, not all of the veins that exit the bowel wall roughly at right angles can be examined adequately. We investigated whether preparation of the adjacent vascular connective tissue with tangential sectioning might not result in different EVI rates. A total of 100 unselected surgical specimens of the bowel bearing 103 CRCs were prepared using a previously undescribed method, and EVI was found in 54.1% of the cases considered to have been treated curatively. To assess EVI fully, a complete study of all the vessels draining the tumor would be required yet the conventional preparation technique is associated with the distinct possibility of sampling error, because only a few vessels in each block are sectioned in the longitudinal axis. This sampling error might well be the explanation for the considerably higher incidence of EVI in our cases than in the reports in the literature. In all patients with EVI, the possibility of hematogenous metastases exists, and this has a significant bearing on the question of selecting patients for adjuvant chemotherapy.

Carcinoma↗
PubMed1995

Ultrasound imaging of pneumonia.

One hundred forty-three consecutive patients with clinically and radiologically confirmed pneumonia were examined by ultrasound. In 127 cases (88.8%), a consolidation could be visualised in the sonogram. Eight patients (5.6%) had a pleural effusion only. The remaining eight (5.6%) had no pathological findings. The characteristic features of pneumonia were a hypoechoic consolidation with numerous small hyperechoic structures (112 patients, 88.1%) and a blurred margin. In eight cases abscess formation could be detected and treated by ultrasound-guided drainage. We conclude that sonography can visualise pneumonic consolidations in a high percentage, and gives additional information concerning the diagnosis, follow-up and treatment of pneumonia.

Adolescent↗
PubMed1995

Probing molecular interactions with homogeneous techniques based on rare earth cryptates and fluorescence energy transfer.

A homogeneous assay method based on the long-lived fluorescence of rare earth cryptates and amplification by nonradiative energy transfer has been developed for immunoassays. The principles of the assay allow a double discrimination of the emitted signal through spectral and temporal selectivity. The cage structure of the complex, ion pairing around europium, as well as double-wavelength detection, fully shield the assay from perturbations of media. Events based on short-range interactions involving biomolecules are of tremendous importance in many domains of biology, either for analytical purposes or for molecular mechanism studies. Therefore, the principles and the reagents used to devise this homogeneous assay were adapted to various models representative of molecular and cellular processes and were chosen from the signaling pathways involved in cellular communication and expression: epidermal growth factor (EGF) receptor-ligand interaction, EGF receptor kinase activity, Jun/Fos protein-protein interaction, and DNA hybridization. Evaluation of the homogeneous assays yielded results compatible with those from comparison assays and demonstrates the versatility and wide range of applicability of this methodology.

Bridged Bicyclo Compounds↗
PubMed1993

Pulmonary infarction: sonographic appearance with pathologic correlation.

OBJECTIVE: Peripheral pulmonary lesions are detectable by ultrasound, the aim of this study was to compare sonograms of pulmonary infarctions with their pathological reports. SUBJECTIVE: A total of 26 lung infarcts in 15 non-fixed autopsy lungs of patients showing necroscopically pulmonary embolism were examined sonographically in a water-bath no later than 5 h after autopsy with a 5- or 7.5-MHz sector scanner. Five of these patients were suspected of pulmonary embolism and underwent sonographic examinations shortly before their death. RESULTS: Ultrasound showed mainly wedge-shaped (n = 18), hypoechoic areas. Their location, form and size corresponded exactly with pathological findings. Fresh infarcts were homogeneous and more hypoechoic. Older infarcts were well demarcated and showed a hyperechoic reflex in the center corresponding to the bronchiole; this was a sign of segmental involvement. In two cases it was possible to differentiate thromboembolically congested afferent blood vessel directed to the hilus. Ultrasound images from five living patients were similar to the image of the autopsy lung. CONCLUSION: In accordance with clinical studies these observations suggest that transthoracic sonography can be an efficient technique in the detection of pulmonary infarction, as well in an early reperfusionable stage as in distinguished infarct formation.

Humans↗
PubMed1993

Sonographic observation of pulmonary infarction and early infarctions by pulmonary embolism.

Fifty-eight consecutive patients with clinical symptoms of pulmonary embolism/infarction were examined by ultrasound as the first imaging modality. The diagnosis was confirmed in 35 patients by ventilation-perfusion scintigraphy; 13 underwent pulmonary angiography for verification of clinical diagnosis. Seven patients died, necropsy was performed and the diagnosis of pulmonary embolism was confirmed in six cases; three patients were submitted to transthoracic lung biopsy. Intercostal space and an additional small pleural effusion in 48% of the examined patients served as a sonic window for the 5 MHz sector scanner. In 42 of the 54 cases with a final diagnosis of pulmonary embolism/infarction a total of 69, hypoechoic, lesions with a pleural basis were detected. These were conspicuous, predominantly triangular, of a mean size 4.6 x 3.7 cm (range 9 x 8 to 2 x 1.5). A hyperechoic structure with reverberation artefacts suggestive of air was frequently visible in the centre: a sign of segmental involvement. The ultrasound examination yielded a true positive result in 41 cases. The overall sensitivity was 98% and the specificity 66%. The prevalence of pulmonary embolism was 83% and the diagnostic accuracy 90%. This suggests that chest sonography can be an efficient technique in the detection of pulmonary infarction.

Adult↗
PubMed1993

Epithelial misplacement after biopsy of colorectal adenomas.

The question has been raised as to whether the removal of biopsy material from colorectal adenomas can lead to misplacement of tumour fragments into the deeper layers of the bowel wall. We carried out an analysis of histological sections obtained from 21 patients in whom, between 2 and 21 days before removal of their adenoma, forceps biopsy (n = 18), or polypectomy (n = 3) had been performed. The initial histological picture a few days after biopsy is of an ulcer covered by a suppurative exudate and abundant mucus-containing small, free-lying groups of tumour cells. After an average of 7 days, we found misplacement of these groups of cells into the submucosa where, during the course of reparative processes, they became embedded within a capillary-rich granulation tissue. Subsequently, fibrosis of the submucosa develops with persistent mucus pools. Our results thus show that removal of biopsy material from adenomas can result in misplacement of tumour particles into the submucosa. These changes were observed in flat or broad-based tumours, and epithelial misplacement appears to be detectable within only a short period after biopsy. For the differential diagnosis, it is important to distinguish these changes from invasive carcinoma.

Adenoma↗
PubMed1993

Rare earth cryptates and homogeneous fluoroimmunoassays with human sera.

The rare earth cryptates are used as long-lived fluorescent labels. They are formed by inclusion of a europium ion in the intramolecular cavity of a macropolycyclic ligand containing bipyridine groups as light absorbers. The use of fluoride ions in the measuring medium allows a total shielding of the label fluorescence. Here, I have established the conditions under which the signal of these cryptates can be amplified through the use of nonradiative energy transfer, and applied these conditions to homogeneous immunoassays by using allophycocyanin as the acceptor. Because only a low proportion of the cryptate label is involved in the transfer amplification, and because allophycocyanin emission occurs between the europium emission lines, time-resolved measurement of europium and allophycocyanin emission allows real-time correction of the optical properties of the assay medium. These features have allowed the development of a rapid homogeneous immunoassay of prolactin that can detect as little as 0.3 microgram/L (3rd International Standard 84/500).

Chelating Agents↗
PubMed1993

Europium(III) trisbipyridine cryptate label for time-resolved fluorescence detection of polymerase chain reaction products fixed on a solid support.

We report a method for the nonradioactive detection of specific amplified target DNA, based on a new long-lived fluorescent label, europium(III) trisbipyridine cryptate [TBP-(Eu3+)]. After a polymerase chain reaction with a set of nested primers, microtiter affinity-collected hybrids were recognized by a TBP(Eu3+)-labeled antibody. The particular structure of the label containing the energy transfer units (bipyridine moieties) enables direct fluorescence measurement on the solid phase. Moreover, its stability and long lifetime contribute to the enhancement of the signal-to-noise ratio. The usefulness of this new label is illustrated by the detection of human papillomavirus type 16 DNA in clinical smears.

2,4-Dinitrophenol↗
PubMed1992

[Sonography in salmonella enterocolitis].

27 patients suffering from salmonella enterocolitis--24 proven by stool cultures, 3 confirmed serologically--were examined for ultrasound findings. In 81% the left side gut wall was concentrically thickened up to 7 mm (5-11). Further sonographic findings were: Less demarcated gut wall layers in 33%, hypoechoic gut wall in 48%, polypoid mucosa thickening in 33%. In individual cases enlarged mesenteric lymph nodes, splenomegaly, and ascites were seen. Sonographic changes correlated well with clinical results in respect of the intensity of the illness.

Adolescent↗
PubMed1991

Europium(III) cryptate: a fluorescent label for the detection of DNA hybrids on solid support.

We report here a new detection method for DNA hybrids on dot blots. The process utilizes DNA or oligonucleotide probes labeled with biotin, followed by recognition with a conjugate of streptavidin and europium cryptate, a time-resolved fluorescent label. Unlike the other lanthanide chelates, this label is an organic molecule embedding a europium ion into an intramolecular cavity. This structure has a better stability in diluted assay media, a good sensitivity even on solid support, and an elevated fluorescence lifetime which allows elimination of most of the background generated by other species present in the assay medium. This procedure is quantitative and detects down to 2 amol of a model DNA, which is similar to other nonisotopic (especially colorimetric) methods. The main advantages of this method are easy automation, quantitation, and rapidity of measurements.

Bacterial Proteins↗
PubMed1990

[Lung infarcts detected with ultrasonography].

33 patients with clinical signs of pulmonary infarction were investigated by intercostal chest sonography. 40 preponderant triangular sharply outlined echo-poor lesions were detected with an airdense reflex in the centre of the area as a sign of segmental involvement. Sonomorphology of pulmonary infarction is compared to pneumonias (n = 22) and carcinomas (n = 20). The sensitivity of chest sonography in pulmonary infarction is 96%, whereas the diagnostic accuracy is 82%.

Diagnosis, Differential↗
PubMed1990

Uncoupling of DNA excision repair and nucleosomal unfolding in poly(ADP-ribose)-depleted mammalian cells.

The repair of DNA damage in eukaryotic cells is closely coupled with local changes of chromatin structure such that newly synthesized repair patches transiently appear in 'free' DNA domains with increased accessibility to enzymatic and chemical probes. We have isolated these domains from mammalian cells repairing bulky DNA adducts. During the first 3 h of repair, excision of adducts occurred exclusively in free DNA and was closely linked with the appearance of newly synthesized repair patches. Following depletion of chromatin-bound poly(ADP-ribose), the repositioning of repair patches into these domains was completely blocked, although overall repair patch synthesis was unaltered. Concomitantly, DNA adducts were no longer excised and tended to accumulate in free DNA domains. Our results suggest a tight coupling of the excision step with the formation of free DNA domains by a mechanism involving poly ADP-ribosylation of chromatin proteins.

Acetoxyacetylaminofluorene↗
PubMed1990

The poly-ADP-ribosylation system of higher eukaryotes: a protein shuttle mechanism in chromatin?

The role of poly ADP-ribosylation in DNA excision repair was studied in experimental models of various complexities. In intact cells in vivo, the unfolding of chromatin during DNA excision repair apparently requires the presence of a functional poly-ADP-ribosylation system. In vitro studies involving a reconstituted poly-ADP-ribosylation system show that the enzyme poly(ADP-ribose)polymerase has the capacity to shuttle core histones on a core DNA fragment of 146 bp. Under these conditions, the polymerase operates in a strictly processive mode. Furthermore, the polymerase adapts to different shuttling targets by producing very distinct polymer patterns. We conclude that the eukaryotic poly-ADP-ribosylation system has the capacity to regulate DNA-protein interactions and this may be an essential part of the unfolding mechanism of chromatin during excision repair in vivo.

Animals↗