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Biomedical subjects

C Mittermayer

Publications and source records attributed to C Mittermayer.

At least 109 records · Page 6Linked to original sources
PubMed1987

Melanocytic neuroendocrine carcinoma of the thymus.

A neuroendocrine carcinoma of the thymus with an ectopic adrenocorticotropic hormone (ACTH) syndrome and melanocytic differentiation is described. ACTH, neuron-specific enolase (NSE) and S-100 protein were identified in the tumor by immunocytochemistry. Neurosecretory granules and melanosomes could be demonstrated in different cell populations by electronmicroscopy. The clinicopathologic findings are presented. The literature is briefly discussed.

Adrenocorticotropic Hormone↗
PubMed1987

[Special aspects of right colon cancer].

752 patients with colon carcinoma of the years 1966-1985 were studied retrospectively. 189 tumors were located in the right and 563 in the left colon. There was no difference in the 5-year survival rate, Dukes classification and operative mortality in both groups. Considering the higher median of tumor diameter, the three months longer diagnostic delay and the twice higher rate of undifferentiated carcinomas the prognosis of the right sided tumors is relatively better. In our opinion the cause of this more efficient local tumor defence is the better blood and lymph supply of the right colon and mucosal mechanisms. Expression of this better tumor defence is the distinct tumor colitis in the right colon. Improvement of the right colon carcinoma prognosis is to be expected of earlier tumor diagnosis. Routine endoscopic evaluation of hemoccult positive subjects is most helpful.

Adult↗
PubMed1987

Results of a comparative in vitro study of Duromedics and Björk-Shiley monostrut mitral heart valve prostheses.

Two different mechanical heart valves with annulus diameters 21-29 mm, (five Björk-Shiley monostrut tilting disc valves and five Duromedics bileaflet valves) have been tested in pulsatile flow in the mitral position of a mock circulation. Reflux, pressure, and orifice area have been measured while cardiac output was varied between 2 and 6 1 min-1. Insufficiency, mean orifice area, discharge coefficient, and performance and efficiency indices have been calculated. Mean values of insufficiency for the Björk-Shiley monostrut valves varied between 4.8 and 17.2% while the corresponding values for the Duromedics valves were in the range 6.1-17.3%. Mean values for orifice areas of the Björk-Shiley monostrut valves increased with the larger valve sizes from 101.1 to 210.2 mm2; for the Duromedics valves the area range was 134.5-262.9 mm2. Because of the larger orifice areas the values of discharge coefficient and performance index for the Duromedic valves were higher than those for the Björk-Shiley monostrut valves. As the insufficiency of the two mechanical valves was similar, and the orifice area of the bileaflet valves was greater than that of the tilting disc valves, Duromedics valves gave higher valves for the efficiency index, which varied between 0.31 and 0.39; for Björk-Shiley monostrut valves the index varied between 0.24 and 0.28 under the same test conditions. This hydrodynamic in vitro comparison of mechanical heart valves showed that the Duromedics bileaflet valves were superior to the Björk-Shiley tilting disc valves.

Biomedical Engineering↗
PubMed1987

Closure of the pericardium using expanded polytetrafluoroethylene GORE-TEX-Surgical Membrane: clinical experience.

Complete closure of the pericardium after cardiac operation would have the advantage of avoiding injury of the heart and great vessels should repeat sternotomy prove to be necessary. In such situations, various pericardial closure techniques have been described. Synthetic materials produced severe scarring, while xenografts appeared to be satisfactory, although fibrous reactions and aseptic cystic formations have been reported recently. Between 1985 and 1986 we closed the pericardium with GORE-TEX-Surgical Membrane in a selected series of 72 patients aging 1 month to 76 years, median 24 years. Overall hospital mortality was 3/72 cases. In no instance was there a relationship between death occurrence and pericardial closure through Surgical Membrane. There were 5 cases each of low cardiac output and rethoracotomy because of bleeding. No cardiac tamponade occurred. Two patients had to be reoperated three and four weeks after primary repair. Surgical Membrane was explanted. Electron microscopy examination showed no cellular ingrowth in the low porosity membrane. No immunocompetent cellular compounds were present on either side of the graft. Follow-up interval averaged 13 months. No complication related to pericardial closure has occurred until now. The Surgical Membrane has the advantages of easy availability, of lack of reactions both between its surface and the underlying epicardium and with the rest of the pericardium. We believe its routine use should be encouraged mainly in patients with high probability of reoperation.

Adolescent↗
PubMed1987

Age-dependent variation of T1 and T2 relaxation times of adenocarcinoma in mice.

The T1 and T2 values of adenocarcinoma EO 771 inoculated into the hind leg of mice are characterized and correlated with the histopathologic state of the tumor. Growth-dependent changes (indicated by a T1 of 630-910 msec and a T2 of 68-185 msec) can be separated into four characteristic phases. The increase in relaxation times in the early phases (A and B) is due to an increasing amount of viable tumor tissue relative to normal muscle tissue. In the later phases (C and D), a decline of the relaxation parameters is observed that is parallel to an increase in the fraction of necrotic tissue. By multiexponential analysis, two relaxation components (indicated by and, respectively) for T1 and T2 and the corresponding fractions alpha 1 and alpha 2 can be observed for both tumor and surrounding muscle tissue. A tissue criterion ("magnetic resonance fingerprint") is defined by a combination of these multiple parameters. This criterion allows separation of not only muscle and tumor tissue but also viable (early state) and necrotic (late state) tumor tissue.

Adenocarcinoma↗
PubMed1987

[Endothelial function and arteriosclerosis].

Elevated levels of plasma LDL have been correlated with morphological endothelial damages, e.g. reduced antithrombogenity of endothelial cells. Numerical and functional defects of endothelial cells probably influence the necessary separation of blood fractions from subendothelial tissues in a negative sense. In order to describe an imaginable endothelial dysfunction with respect to LDL transport we examined human umbilical venous endothelial cells (HUVEC) in culture under physiological flow conditions. HUVEC in culture after incubation with a LDL concentration of 100 micrograms/ml medium were exposed to defined levels of physiological shear stress, fixed with formalin and stained with oil-red-O. After documentation of oil-red-O staining with a photomicroscope, the amount of stain has been characterized semiquantitatively with the help of an image-analysis system (IBAS II/Zeiss). HUVEC not exposed to shear stress only showed a marginal oil-red-O staining at the cell surface. If they were exposed to shear stress of 0.5 dyn/cm2 they showed in orthogonal view an average increase of 1.3%, in cross-sectional view an average increase of 0.3%. HUVEC exposed to shear stress of 2.5 dyn/cm2 showed in orthogonal view an average increase of 4.6%, in cross-sectional view an average increase of 8.7%.

Arteriosclerosis↗
PubMed1987

[Comparative study of mechanical heart valves for implantation in mitral position].

For hydrodynamic comparison of mechanical heart valves, three tilting disc valves (Björk-Shiley SD, Björk-Shiley CCD, Björk-Shiley Monostrut) and two bileaflet valves (St. Jude Medical, Duromedics) with annulus diameter dA = 31 mm were perfused in a mock circulation in mitral position. Flow, pressure, and orifice area were measured during pulsatile flow. Insufficiency, maximal orifice area, mean orifice area, performance index and efficiency index were calculated. The tilting disc valves show distinctly lower orifice areas than the bileaflet valves. The mean value of maximal orifice area Amax of the Björk-Shiley prostheses varies between 227.82 +/- 7.77 mm2 and 243.21 +/- 6.21 mm2. The mean value of Amax of the Duromedics prosthesis is 295.45 +/- 7.76 mm2 and that of the St. Jude Medical prosthesis is 477.43 +/- 11.32 mm2. The calculated mean orifice areas A of the bileaflet valves are also higher than those of the tilting disc valves. The mean values of A are: Björk-Shiley SD: 183.55 +/- 10.03 mm2; Björk-Shiley CCD: 206.30 +/- 8.62 mm2; Björk-Shiley Monostrut: 210.12 +/- 4.74 mm2; St. Jude Medical: 398.69 +/- 19.55 mm2; Duromedics: 262.90 +/- 6.84 mm2. The performance index PI is qualitatively identical with the values of the mean orifice area A because in this study only heart valves of the same size were investigated. For calculation of insufficiency I the entire reflux volume VR including closing volume VS and leakage volume VL was used, thus, insufficiency was also determined in intact prostheses. The values of insufficiency of the mechanical valves investigated are higher for the bileaflet valves than for the tilting disc valves.(ABSTRACT TRUNCATED AT 250 WORDS)

Bioprosthesis↗
PubMed1986

Stress fibres (SF) in human endothelial cells (HEC) under shear stress.

Human umbilical veinous endothelial cells are cultured on artificial substrates precoated with extracellular matrix from bovine corneal endothelial cells. These cultural conditions help cells to keep an elevated maintenance level for otherwise unusual time intervals. Integrity of endothelial cell layers is of special interest for nondisturbed blood circulation. Therefore we look after mechanisms of cell--cell and cell--substrate--adherence. Here we focus on stress fibres, microfilaments, which seem to play an important part in cellular adherence phenomena. Since endothelial cells in vivo are constantly shear stressed by the blood stream we investigated cell--substrate interactions in vitro under dynamical conditions with the help of a modified cone--plate rheometer originally designed for hemorheology. It can be demonstrated in these shearing experiments that toxical substances influence the organization of stress fibres.

Actin Cytoskeleton↗
PubMed1986

[Precancerous stages of the oral mucosa--possible identification of obligatory precancerous conditions].

Macroscopically and microscopically precancerous lesions of the oral mucosa cannot be diagnosed with sufficient accuracy. Dysplasias represent a particular diagnostic difficulty. The reproducibility of grading of dysplasias may be increased by the quantification of morphological parameters using image analysis systems. However an unequivocal identification of obligatory precancerous lesions cannot be attained by this method. Measurement of the nuclear DNA content represents a non-morphological method for the identification of obligatory precancerous lesions. The diagnostic criterion of malignancy is aneuploidy. Structural or numerical chromosomal aberrations that are absent in benign tumours and normal cells typify aneuploidy. Aneuploidy is manifested by an atypical nuclear DNA distribution that can be identified objectively by suitable algorithms. Dysplasias of the squamous epithelium with aneuploid nuclear DNA contents are regarded as obligatory precancerous lesions. DNA measurements, computation of data and printout of a 'DNA diagnosis' are possible with a TV-image analysis system and an automated microscope within 30 min.

Carcinoma in Situ↗
PubMed1986

[A new echocardiographic procedure for calculation of the accurate volume of the right atrium].

The right atrial (RA) volume can be determined angiographically from two perpendicular projections. Up to now volume calculations by means of two-dimensional echocardiography (2-DE) have only been attempted in a single plane, the apical four-chamber view. Our study reports a new method for RA volume calculation using two intersecting cross-sectional echocardiographic views. For this purpose silicone rubber casts of 20 human necropsy hearts were obtained and thin walled natural rubber moulds of the RA casts were prepared. Totally filled with and immersed in water, the mouls could be visualized in the apical four-chamber view and an additional echocardiographic plane, the latter corresponding to the subcostal view in vivo. In this view the vertical extension of RA could be estimated. Areas and length of RA were determined in the respective planes and RA volume was calculated by applying the formula: - Area X Length - to two intersecting planes. Finally, the latex moulds were filled with diluted contrast agent and the volume was determined angiographically using a biplane disc method. Real volume of RA was 112 +/- 23 ml (mean +/- 1 SD). Angiographically, an overestimation resulted: the calculated volume amounted to 119 +/- 24 ml, the mean difference was 7 +/- 2 ml (p less than 0.001). The regression equation was y = 1.04 X + 2.34, r = 0.995, SEE = 2.3 ml. Volume determination from the apical four-chamber view using a monoplane disc method resulted in a mean volume of 62 +/- 17 ml. The mean difference to the real RA volume was 50 +/- 17 ml, p less than 0.001.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Identification of endotoxin-positive cells in the rat lung during shock.

Following an intravenous administration into rats of a shock-inducing dose of endotoxin (2 mg) the lipopolysaccharide (LPS) was demonstrated immunohistochemically (light and electron microscopy) and determined quantitatively (radio-labelled LPS) in the lung tissue and in isolated alveolar macrophages. At different times after LPS injection morphological investigations of the pulmonary tissue and alveolar macrophages were carried out. One hour after endotoxin treatment 3% of the alveolar macrophages were already LPS-positive. The maximum extent of the immunoperoxidase reaction for endotoxin (100% cells involved) was observed on day 3, the vast majority (98%) of the alveolar macrophages being LPS-positive still on day 14. 0.9% of the injected radio-labelled LPS preparation was found to be associated with lung tissue on day 3. By this time 0.173 microgram LPS/10(6) alveolar macrophages was detected. During the time of ultrastructural investigation endotoxin appeared in the lung only within cells. By their high capacity for storing endotoxin and their numerical superiority the mononuclear phagocytes are the leading LPS-positive cells in the lung, although granulocytes, endothelial cells, and alveolar epithelial cells were sometimes also involved. The accumulation of a high percentage of activated macrophages in the lung seen in the late stage of shock could represent at least one of the main factors leading to damage of pulmonary tissue. The correlation between appearance of LPS-positive macrophages and histological signs of lung tissue injury in the present investigation is striking.

Animals↗
PubMed1984

Haemorrhagic tumour necrosis following endotoxin administration. I. Communication: morphological investigation on endotoxin-induced necrosis of the methylcholanthrene (Meth A) tumour in the mouse.

Endotoxin induced necrosis of the Meth A mouse tumour has been investigated using macroscopic, histological and ultrastructural examination methods. On the 8th day after tumour cell transplantation, the animals received a relatively non-toxic dose of the Salmonella abortus equi endotoxin intravenously. The natural history of the tumour necrosis took the following course: The earliest morphological changes could be seen with the electron microscope 90 min after administration of the endotoxin, and were seen as an interstitial oedema with separation of the tumour cells. Haemorrhagic necrosis of the tumour was complete 4 hours after injection, and could be easily recognized with the naked eye. Rejection of the necrotic malignant tumour was complete two weeks after LPS administration. Only minor residual scarring of the belly-wall remained. Haemorrhagic tumour necrosis due to endotoxin can be compared with the localized Shwartzman reaction and probably involves tumour necrotizing factor (TNF). For complete destruction of a tumour by haemorrhagic necrosis the size of the tumour is critical. Certain regression after endotoxin administration depends upon additional T-cell-mediated immunity (provided the tumour is immunogenic). In contrast to the haemorrhagic necrosis, BCG-induced tumour regression is accompanied by granulomatous inflammation, which may be responsible for destruction of the tumour.

Animals↗