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Biomedical subjects

G Mathis

Publications and source records attributed to G Mathis.

At least 37 records · Page 2Linked to original sources
PubMed2000

Embolism of a metallic clip: an unusual complication following laparoscopic cholecystectomy.

A 32-year-old woman underwent laparoscopic cholecystectomy during which there was severe bleeding from the bed of the gallbladder. As application of metallic clips to control the bleeding was not successful, the operation was converted to an open laparotomy. Cholecystectomy was successfully completed without further complications, and the post-operative course was uneventful and the patient was discharged. Eighteen months later, the patient complained of dyspnea. Plain radiograph and computed tomography of the thorax showed a metallic clip in the branch of the pulmonary artery supplying the posterior basal segment of the inferior lobe of the left lung. There was no connection between the patient's symptoms and the clip embolism. Nevertheless, clip migration or embolism could cause severe complications. Therefore, metallic clips should not be used to stop bleeding from the gallbladder bed.

Adult↗
PubMed2000

High throughput screening for human interferon-gamma production inhibitor using homogenous time-resolved fluorescence.

An immunoassay for interferon-gamma (IFN-gamma) using homogeneous time-resolved fluorescence (HTRF) has been developed. In this assay, IFN-gamma can be detected by simply adding a mixture of three reagents-biotinylated polyclonal antibody, europium cryptate (fluorescence donor, EuK)-labeled monoclonal antibody, and crosslinked allophycocyanin (fluorescence acceptor, XL665) conjugated with streptavidin-and then measuring the time-resolved fluorescence. The detection limit of IFN-gamma by the proposed method is about 625 pg/ml. We applied the method to the detection of IFN-gamma secreted from NK3.3 cells and employed it in high throughput screening for IFN-gamma production inhibitors. With this screening format, IFN-gamma can be measured by directly adding the above reagents to microplate wells where NK3.3 cells are being cultured and stimulated with interleukin-12. This "in situ" immunoassay requires only pipetting reagents, with no need to transfer the culture supernatant to another microplate or wash the plate. Therefore, this screening format makes possible full automation of cell-based immunoassay, thus reducing cost and experimental time while increasing accuracy and throughput.

Antibodies, Monoclonal↗
PubMed1999

Ultrasound-guided diagnostic and therapeutic interventions in peripheral pulmonary masses.

The value of ultrasound guided transthoracic biopsy and abscess drainage was assessed in 155 patients with thoracic consolidations adjacent to the chest wall. Biopsies were performed with 18- or 19-gauge tissue core biopsy needles. Correct diagnosis was achieved in 91% (92% in neoplasmas, 87% in non-neoplastic consolidations). Ultrasound guided percutaneous lung abscess drainage was successful in 13 cases. Six patients developed complications: one small pneumothorax, two pneumothoraces requiring a chest tube, two mild and one moderate hemoptyses. Ultrasound guided transthoracic biopsy is an accurate, safe and well-tolerated procedure. It provides adequate specimens for routine histologic examination and also permits successful drainage of pulmonary abscesses.

Adult↗
PubMed1999

Chest ultrasound in diagnosis of pulmonary embolism in comparison to helical CT.

UNLABELLED: To many people die because of undiagnosed pulmonary embolism. Common pulmonary embolism is the most unexpected mortal event in necropsy, antemortem correctly diagnosed in 18-39%. The diagnostic value of chest ultrasound (CUS) has been investigated. METHODS: 117 (68 women, 49 men) patients with clinical suspicion of pulmonary embolism underwent chest sonography and spiral computed tomography (CT). Final diagnosis has been made by CT respective with echo-cardiography, venous duplex sonography and fibrin dimer tests. RESULTS: Finally, 70 patients suffered from pulmonary embolism. The chest sonograms showed averaged 1.5 x 2.8 cm (0.5-8.5) large triangular or rounded hypoechoic lesions, mean 2.6 pro patient, similar in form and size as in CT. Fresh reperfusionable infarcts were homogenous and hypoechoic. Older infarcts were well demarcated, mainly wedge shaped. A hyperechoic reflex in the center corresponds to the bronchiole: a sign of segmental involvement. The sensitivity of chest ultrasound was 94%, the specificity 87%, positive predictive value 92%, negative predictive value 91%, accuracy 91%. Overall 61 patients had PE in CT, in 47 (67%) cases a direct emboli detection was possible. 14 patients had peripheral lung consolidations without detectable emboli, but fibrin-dimer tests were positive in all cases, there was deep vein thrombosis diagnosed and they showed signs of PE in echocardiography. Spiral CT showed a sensitivity of 85%, a specificity and a positive predictive value of 100%, a negative predictive value of 83% and an accuracy of 92%. CONCLUSION: CUS can improve diagnosis of pulmonary embolism. Sonography also reveals small infarcts which remain undetected with other imaging procedure such as helical CT.

Adult↗
PubMed1999

[Ultrasound-guided transthoracic puncture].

The diagnosis of peripheral lung foci may prove difficult. In addition to transthoracic puncture under X-ray fluoroscopy or CT control, ultrasound-guided puncture was shown to be a useful alternative. A prerequisite, however, is that the lesion should extend up to the pleura. This overview covers 97 original papers, of which 26 mainly consisted of lung punctures in a total of 1876 patients. The accuracy in carcinomas and metastases was 70 to 97%, on average markedly higher than 90%. Benign lesions are histologically more difficult to distinguish; here the accuracy is 70%. Partly due to pre-selection the method has a very low rate of complications. The rate of pneumothorax is 2.6%, those requiring drainage are about 1%. Haemoptyses occur 1-2% of the punctures, most commonly in cases of chronic pneumonia; colour-coded Duplex sonography is especially recommended in these cases because of the strong and regular vascularisation. The rate of complication increases in direct proportion to needle thickness. The possibilities of ultrasound-guided lung abscess drainage are also discussed. An intrathoracic lesion that is accessible to ultrasound imaging should be punctured today under ultrasound guidance, as this procedure is minimally stressful for the patient, is accurate, has a low rate of complications and is also cost effective.

Drainage↗
PubMed1999

[Transthoracic sonography in the diagnosis of pulmonary embolism].

In many cases of pulmonary diseases extending up to the pleura, ultrasound helps to identify the etiology of the lesion. There are several sonomorphological criteria to differentiate peripheral pulmonary consolidations. Clinical studies and the sonographic appearance with pathologic correlation showed pulmonary infarctions in location, form and size exactly corresponding with pathological findings. Fresh reperfusable infarcts were homogenous and hypoechoic. Older infarcts were well demarcated, mainly wedge shaped. Triangular pleural based lesions, more roughly structured, were observed with a hyperechoic reflex in the center corresponding to the bronchiole: a sign of segmental involvement. The sensitivity of transthoracic ultrasound in diagnosis of pulmonary embolism was 86 to 94%, the specificity 67 to 87%, positive predictive value 55 to 92%, negative predictive value 91%, accuracy 73 to 91%. In massive central lung embolism, both fresh and old infarctions are found. An imminent larger embolism can be predicted, for instance,in a deep vein thrombosis. With one ultrasound system, we can "kill three birds with one stone": source, way and outcome of pulmonary embolism by bedside examination.

Humans↗
PubMed1998

Polypyrrole DNA chip on a silicon device: example of hepatitis C virus genotyping.

We describe in this article an oligonucleotide array constructed on a silicon device bearing a matrix of addressable 50-microns microelectrodes. Each electrode was covered by a conducting polymer (polypyrrole) grafted by an oligonucleotide (ODN). The DNA chip was prepared by successive electrochemically addressed copolymerizations of 5' pyrrole-labeled ODN and pyrrole. Following hybridization of the biotinylated amplified sample on the chip bearing a series of probes, detection was carried out by fluorescence microscopy through an R-phycoerythrin label. This technology was successfully applied to the genotyping of hepatitis C virus in blood samples. Results show good sensitivity and a high degree of dimensional resolution.

Biotechnology↗
PubMed1998

Conducting polymers on microelectronic devices as tools for biological analyses.

In the field of biological analysis, the need for multiparametric analysis has prompted the development of supports bearing a series of biomolecules linked to a support in a precise location (addressed). To reach a high information density, miniaturization of this kind of support has to be carried out. We describe in this paper an approach involving the use of electro-conducting polymers such as polypyrrole. This technology is based on an electro-directed copolymerization of pyrrole and oligodeoxynucleotides (ODN) linked to a pyrrole residue. The process allows the grafting of the selected ODN at the surface of the successively addressed microelectrodes. In this way, the syntheses are carried out on 50 microm electrodes on passive chips or on active (multiplexed) chips bearing 48 or 128 gold microelectrodes, respectively. The detection of biological targets recognized by the biochip is carried out by using fluorescent tracers. This technology, involving prepurified materials precisely addressed, allows better reproducibility of the biochip preparation and, then, an easy interpretation of the fluorescence results. The versatility of this technology is illustrated by ODN or peptide copolymerizations leading to DNA chips or peptide chips, respectively. This would open the field for other biological interaction studies.

Immunoassay↗
PubMed1997

Homogeneous two-site immunometric assay kinetics as a theoretical tool for data analysis.

The easily accessible kinetics of a new homogeneous two-site fluorometric immunoassay for prolactin was studied, in order to determine its usefulness for assay data reduction and optimization. The combined use of a simple descriptive model fitted to experimental data and a mechanistic model to simulate the kinetics revealed that (i) the kinetics curve presented an early inflexion point. Its time of occurrence was constant as long as the antigen concentration was below the smallest antibody concentration and decreased to zero for higher concentrations. It may therefore be used as an indicator of hooked samples. (ii) The kinetics steepest slope was correlated with antigen concentration. Its use as a dose-response curve variable would allow higher concentrations to be assayed than with the classical end-point dose-response curve. The results suggest that control and exploitation of kinetic parameters could help to improve the rapidity, analytical range, and reliability of homogeneous two-site immunometric assays.

Animals↗
PubMed1997

Thoraxsonography--Part II: Peripheral pulmonary consolidation.

In many cases of pulmonary diseases extending up to the pleura, ultrasound (US) helps to identify the etiology of the lesion. There are several sonomorphological criteria to differentiate peripheral pulmonary consolidations. Pneumonic infiltration shows a hypoechoic inhomogeneous echo texture, with multiple air inlets and bronchoaerograms. Fluid bronchogram indicates an obstructive pneumonitis. Pulmonary infarctions are visible in different stages as triangular pleural-based lesions in most cases of pulmonary embolism. The diagnostic accuracy of chest sonography in pulmonary embolism was 85%-90%. US-guided transthoracic biopsy shows a diagnostic yield of > 90% in malignancies and 50%-83% of benign lesions. The overall complication rate is very low: 1%-2% hemoptysis, 2%-4% pneumothoraces and 1%-2% requiring chest tube drainage. Color Doppler US can demonstrate the vascular patterns and may help in the understanding of underlying pathophysiology. Sonographic examinations of the upper and central mediastinum provide good results in 90-95% of cases. Some anatomical limitations of transcutaneous US can be circumvented by endoluminal US.

Biopsy, Needle↗
PubMed1997

Thoraxsonography--Part I: Chest wall and pleura.

The fact that ultrasound (US) waves are reflected completely by the bony thorax and are erased from the aerated lung to a large extent led to the mistaken notion that sonography is not a very useful diagnostic tool for use in this region. On the other hand, since the beginning of US imaging, reports have been published regularly on pleuropulmonary sonographic diagnostic and therapeutic procedures. Rib fractures could be detected about twice as often by US than x-ray. With regard to determining the nodal status in neoplastic disease of the axilla and supraclavicular fossa, US is superior to palpation. In imaging pleural effusions, US is more accurate than chest film and is useful in determining the nature of the pleural effusion. Sonographic evidence of pleural nodules is a specific finding in patients with a malignant effusion. Chest sonography is a useful diagnostic tool for critically ill patients with chest diseases. Performed at the bedside, this technique can be particularly helpful when computed tomography is not available or when critically ill patients cannot be moved.

Humans↗
PubMed1997

[Ultrasound diagnosis of rib and sternum fractures].

PURPOSE: Lesions of the thoracic skeleton can sometimes be a problem in radiological diagnosis. Aim of the study was to investigate the value of ultrasound in the diagnosis of thoracic trauma in clinical practice. METHOD: Patients with thoracic trauma and suspected rib or sternal fracture were entered in the study. The results of the thoracic x-ray including a special target film and thoracic sonography were compared. RESULTS: 103 patients took part in the study (32 women, 71 men, average age 54.3 years). In x-ray the diagnosis of rib fracture was certain in 27 patients (30%). In US 56 patients (58%) had definitive signs of rib fracture. Because of multiple fractures in the same patients the total number of radiologically found rib fractures was 49, whereas 101 fractures could be detected by sonography. Also minimal pleural effusions could be found in 31 patients (32%) sonographically, only 18 of them were seen in x-ray. Larger effusions in six patients (6%) with serial rib fractures and haematothorax could all be diagnosed in x-ray and also US. The seven patients with suspected sternum fracture showed clear fracture signs in x-ray as well as US. CONCLUSIONS: Rib fractures could be found about twice as often US than x-ray. There was no difference in the diagnosis of sternal fracture. Detection of fluids (local haematoma and pleural effusion) is better via US than by x-ray. Therapeutical consequences may follow a quick bed-side diagnosis by US in a patient who needs intensive care. Other aspects after detection of a rib fracture US apart from thoracic contusion are psychological effects for the patients (usually they can cope better with their pain), the importance in the interpretation of the duration of incapacity to work and the additional information provided by expert opinions.

Female↗
PubMed1997

[Can pleurisy be detected with ultrasound?].

PURPOSE: It was the aim of this study to examine whether chest sonography is a useful method for diagnosing infective pleuritis. We assessed the pleural surface, the presence of subpleural consolidations and of pleural effusions. METHOD: 47 consecutive patients with the clinical diagnosis of pleuritis were examined by means of a 7 MHz linear transducer. We studied the pleural surface, the presence of subpleural consolidations and of pleural effusions. RESULTS: Pathologic findings could be seen in 43 patients (91%). The smooth echogenic pleural line was interrupted and was rough in appearance in 42 patients (89%). Subpleural consolidations from 0.2 to 2 cm in size were observed in 30 cases (63.8%). In 11 (23.4%) of these lesions, colour Doppler signals could be demonstrated. Pleural effusions were visible either as localised pleural effusions (24 patients, 51%) or as basal effusions (11 cases, 23.4%). Aspiration of pleural fluid was performed twice. In one case the diagnosis of tuberculosis could be proven by fast acid stain, in another patient a pleural empyema was drained successfully under ultrasound guidance. In 5 patients therapeutic consequences resulted from sonographic findings. CONCLUSION: We conclude that chest sonography is a sensitive and cost effective imaging method for the diagnosis of pleuritis. Aspiration of pleural fluid for further diagnostic or therapeutic procedures can be safely performed.

Adult↗
PubMed1997

A descriptive model for the kinetics of a homogeneous fluorometric immunoassay.

A descriptive mathematical model was chosen to fit the antigen-antibody association kinetics of a new homogeneous immunometric assay for prolactin, involving time-resolved fluorescence detection (TRACE technology, Time Resolved Amplified Cryptate Emission). We paid special attention to the methodology and criteria applied, to yield a convenient and statistically valid model, designed to allow potential exploitation of kinetic information in the data processing of the assay. We compared specific parameterizations of an hyperbolic model, the Gompertz, and the monomolecular models on the basis of morphological considerations, a statistical analysis of fit, and an assessment of the parameters estimation quality, over a wide range of antigen concentrations. The monomolecular model gave the best fit, and the most precise and stable estimation of its parameters. The study of parameter properties confirmed this choice.

Antigens↗
PubMed1996

[Tubular differentiated stomach carcinoma of the (Ming) infiltrating type].

Gastric carcinoma of the infiltrative type (according to Ming) occasionally shows adenomatous differentiation only. Over the past 18 years, we have observed 23 cases of this tumour type, accounting for 3.6% of all surgically treated gastric carcinomas. Macroscopically they were classified as Borrmann IV or III, while histologically most of them were well differentiated. Histologically, these tumours retained the pre-existing structures of the stomach, most readily observable at the tunica muscularis propria; a pronounced desmoplasia was also characteristic, particularly in the submucosal and subserosal layers. In all cases the tumour tissue spread inside lymphatic vessels. All but 2 cases with metastatically involved lymph nodes, often small, showed infiltration of the lymph node sinus; in three quarters of cases the serosa was infiltrated by the tumour. Significant findings among the patients under observation for extended periods included bilateral ovarian metastases in 4 of 5 women examined and tumour recurrence at the anastomosis in 6 of 9 patients in whom Billroth II operation had been performed. The mean survival time of 16 patients was 14.9 months. Owing to the diffuse type of tumour growth, extensive surgery is recommended as in cases of signet ring cell cancer. The high incidence of small lymph node metastases from this type of tumour should also be taken in account preoperative staging. Preoperative diagnosis of this tumour subtype is difficult, because histological criteria alone do not allow clear identification. Close cooperation with clinical investigators is necessary, and intraoperative assessment of the tumour--including frozen section of necessary--in particular is of the utmost importance.

Adenocarcinoma↗