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Biomedical subjects

S Witte

Publications and source records attributed to S Witte.

At least 55 records · Page 3Linked to original sources
PubMed1983

The measurement of density and its significance in blood rheology.

When viscoelasticity is measured with an oscillating capillary rheometer, the density of the fluid under study is an influencing factor (inertia). In the particular case of blood rheology hematocrit is also of interest. It can be measured more exactly on the basis of the density of blood and blood plasma than by conventional methods using a hematocrit centrifuge or Coulter counter, as these give too high readings when there is an increased tendency towards erythrocyte aggregation and reduced erythrocyte flexibility. Due to the double significance of blood density for blood viscoelasticity, an oscillating capillary rheometer and a new type of density-measuring device were attached to a computer in such a way that simultaneous evaluation is possible. The density-measuring device is a U-tube that is set into oscillation electronically. The duration of the oscillation is an indication of the density of the fluid in the U-tube.

Blood Physiological Phenomena↗
PubMed1983

The endoendothelial lining as studied by a fluorescent labeling technique in situ.

The microcirculatory blood vessels of the exposed rat mesentery were observed by intravital microscopy using incident fluorescence excitation and transmitting bright field illumination. Fibrinogen conjugated with the fluorescent dye Fluorescein-Isothiocyanate and injected intravenously was found to accumulate at the vessel wall mostly at the inner lining of venules. The accumulation did not occur in an uniform manner, but appeared as circumscribed streaks, nets and bands in some areas whereas other parts of the microcirculation remained free of any fibrinogen wall adherence. Heparin pretreatment did not influence the phenomena. Blocking the fibrinolytic activity of the blood increased the fibrinogen deposition. Fibronectin labeled with a second fluorescent dye, Rhodamin B-Isothiocyanate, could be differentiated from fibrinogen in the same animal. Both proteins accumulated at the same places of the vessels inner lining. Since albumin and gamma globulin did not show any affinities to the vessel wall, we postulate receptors for fibrinogen and fibronectin at the endoendothelial surface of the microcirculatory endothelial cells.

Animals↗
PubMed1983

The endoendothelial lining as studied by a fluorescent labeling technique in situ.

The microcirculatory blood vessels of the exposed rat mesentery were observed by intravital microscopy using incident fluorescence excitation and transmitting bright field illumination. Fibrinogen conjugated with the fluorescent dye Fluorescein-Isothiocyanate and injected intravenously was found to accumulate at the vessel wall mostly at the inner lining of venules. The accumulation did not occur in an uniform manner, but appeared as circumscribed streaks, nets and bands in some areas whereas other parts of the microcirculation remained free of any fibrinogen wall adherence. Heparin pretreatment did not influence the phenomena. Blocking the fibrinolytic activity of the blood increased the fibrinogen deposition. Fibronectin labeled with a second fluorescent dye, Rhodamin B-Isothiocyanate, could be differentiated from fibrinogen in the same animal. Both proteins accumulated at the same places of the vessels inner lining. Since albumin and gamma globulin did not show any affinities to the vessel wall, we postulate receptors for fibrinogen and fibronectin at the endoendothelial surface of the microcirculatory endothelial cells.

Adsorption↗
PubMed1983

[Intra- and extravascular distribution of coagulation proteins. Interaction with the vascular wall].

Blood proteins specific for the clotting process show the same distribution behavior into the extra vascular space like other plasma proteins. They participate in the macromolecular transport through the vessel wall into the interstitial space and the lymph fluid. The reported results were obtained by vital microscopic investigations of mesenteric vessels of rats using different quantitative techniques with labeled proteins. Fluorescein labeled fibrinogen, antithrombin III, and plasminogen in this technique behave differently according to their molecular weight differences. In humans the extravascular distribution of clotting factors was studied using the model of cantharides skin blister. Some clotting factors were found to be diminished to a different degree pointing to clotting phenomena during transport. - In contrast to most other plasma proteins fluorescein labeled fibrinogen is found to have an affinity to blood vessels, as can be shown using the vital microscopic technique and rat mesenteric vessels. With this, one can detect areas at the interendothelial cell borders of small veins where the fibrinogen turnover primarily takes place. Similar affinities have been detected with fibronectin and a polypeptide from F VIII digest. The results are interpreted as a morphological hint at the functional connection between blood coagulation and the permeability of vessels for macromolecules.

Animals↗
PubMed1981

Comparison of ftorafur with 5-fluorouracil in combination chemotherapy of advanced gastrointestinal carcinoma.

The aim of the study was to compare the combination 5-FU-carmustine with ftorafur-carmustine in the treatment of advanced gastrointestinal cancer. To this end, a prospective, multicenter, randomized trial was initiated. Part I of this trial showed that similar response rates can be obtained with 5-FU-carmustine and ftorafur-carmustine in 109 patients (32.7% versus 26.3%). However, median survival was better in patients treated with 5-FU-carmustine (307 days versus 163 days). Part II of the trial revealed that neither a higher dosage of ftorafur (2 g/m2/day X 5 days) nor the addition of vincristine to both regimens changed the previously obtained results significantly. Again, median survival was found to be better in patients treated with 5-FU combination chemotherapy (304 days versus 144 days). Both the 5-FU and the ftorafur combination were tolerated reasonably well. The results suggest that combination chemotherapy including 5-FU is superior to ftorafur at the applied dosages in terms of survival.

Adult↗
PubMed1981

[Transcapillary exchange of micro- and macro-molecules (author's transl)].

The permeability of the terminal vascular bed for micro- and macromolecules influences the hemorheological behaviour of the blood in various ways: 1. Water and water-soluble micromolecules leave the circulating blood at the arteriolar part of the microcirculation, thereby increasing the colloid osmotic pressure as well as the hematocrit downstream towards the capillaris and venules. 2. Water enters the blood from the tissue preferentially at the venules. This process may be disturbed easily by variations of the hydrostatic pressures with serious consequences for the streaming blood and for the tissue. 3. The permeability of macromolecules takes place mostly as the venous part of the capillaries. It depends on the molecular size and will be governed by the vessel wall itself. The coagulation system influences these processes. Together with the reabsorption of water from the tissue the protein movements through the capillary wall stabilize the hemorheological factors within the venules. The venules are the most vulnerable part of the circulation. 4. The movements of plasma proteins within the interstitial tissue are caused by concentration gradients. Finally the lymph collects the extravascular proteins. Within both compartments, th extravascular space and the lymph, various microrheological phenomena are to be expected.

Blood Coagulation↗
PubMed1980

The diagnostic significance of flow cytometric nuclear DNA measurement in gastroscopic diagnosis of the stomach.

Cell material obtained from 161 patients by gastroscopic aided brushing was compared cytologically and DNA flow cytometrically and evaluated by mathematical discriminant analysis. Whereas all but one of the cytologically confirmed malignant cases were also positive (malignant) in flow cytometry, the DNA determination failed in 6 of the 19 cytologically suspicious cases, having been classified as negative (benign) by cytometry. Out of all cytologically unequivocal malignant and suspected cases, 18% (7 cases) were false-negative in flow cytometry. The false-positive rate was 39% (47 cases). 5% of the material was classified as inadequate for diagnosis (8 cases) by flow cytometry. The false-negative rate of flow analysis in cytologically suspicious cases is apparently caused by a less pronounced increase of DNA content in the cell nuclei of these cases. Reactive gastric mucosa alterations such a inflammations, erosions or ulcers exhibited increased cell nuclear DNA. According to these results, DNA determination can be used as an automated diagnostic procedure for tumour detection only in combination with other measuring criteria.

Cytological Techniques↗
PubMed1979

Microphotometric techniques in intravital microcirculatory studies.

Intravital microscopic techniques were developed in order to measure plasma proteins: (1) circulating in the streaming blood of microcirculatory vessels of the exposed rat mesentery, (2) permeating the vessel wall, and (3) moving through the perivascular interstitial tissue. By means of the ultramicrospectrophotometry, the absorbance of proteins containing aromatic amino acids at 280 nm is measured. Absolute amounts of proteins in the range of picograms are measured in a circular measuring field with a diameter of 17 micrometers. Problems of calibration and of unspecific light scattering are discussed. The scanning microfluorometry makes use of the fluorescent labelling of the plasma proteins. Interstitial tissue with a capillary vessel containing labelled proteins is measured at high speed. A motor-driven object stage synchronized with a measuring system uses scanning lines to traverse the tissue. The data are then processed by a computer. In this way we get continuous quantitative information about the dynamics of protein permeability, starting from time zero. The measuring of the fluorescence intensity and the speed of the fluorometric system are further improved by a computerized 10 kHz scanning device.

Animals↗
PubMed1979

Brush cytology of the papilla of Vater.

In every case of duodenal endoscopy we collect cell material from the papilla of Vater by means of a guided brush technique. The microscopic techniques used include phase contrast study of unfixed material and Papanicolaou stained smears. Normal epithelial cells of the papillary region differ from those of the duodenal epithelium and the epithelial cells of the common bile or pancreatic ducts collected by retrograde cannulation. A striking feature in the cytology of the papilla is the marked tendency for cellular atypias. Mostly these atypias have no correlation to histologic biopsy specimens although they persist in such cases during repeated examinations. Tumour cells from carcinoma of the papilla are found very regularly and consequently the cytodiagnosis of these tumours became of great practical value. Polypoid lesions of the papilla give also, a characteristic cell picture. From a cytological point of view the papillary region, where different kinds of epithelia come together, is of special pathogenetic importance.

Ampulla of Vater↗
PubMed1979

[Value and perspectives of endoscopic brush cytology in gastric lesions (author's transl)].

The techniques for cell collection are well established. Cells in good quality and sufficient quantities are obtained. The preparation of the sediment depends on the microscopic techniques to be used. The cytological tumor criteria are well established. The diagnostic efficiency is more than 90% of cases with proved malignancies. In comparison with the endoscopic biopsy the brush cytology has the following advantages: A stenosis can be reached by the brush much easier than by the forceps. The tumor detection is improved by cytology under optimal conditions for 10% of the cases. Quantitative microscopic techniques can be adapted. The most important perspective for a further improvement of gastric cytology lies in the development of methods for automation in tumor cell recognition. The present status of such techniques is presented.

Cytological Techniques↗
PubMed1978

[Practical experiences with the Hematrak (author's transl)].

This report is based on own practical experiences with the Hematrak during seven months of daily use in the hematologic routine in a general hospital. We describe briefly the operation of the instrument. The importance of the preparation of the slides is stressed. In this respect a device for automatic smear preparation is mentioned. To test the reliability of the instrument the differential counts of the instrument were compared with manual results and regression values calculated. The reproducibility was checked and calculated. The next point of interest was the number and kind of cells determined as "suspect" by the instrument. Finally we tested how pathologic cells were detected and determined by the instrument.

Autoanalysis↗
PubMed1978

[The influence of capillary permeability on the extravascular protein quantities as measured in situ (author's transl)].

The extravascular protein contents in the perivascular connective tissue of a rat's mesenterial plate was measured ultramicrospectrophotometrically in situ and in vivo after changing the hydrostatic and colloidosmotic pressures of the blood. We analized the perivascular area of the different microcirculatory vessels, arterioles, capillaries and venules. The perivascular protein contents, which corresponds besides arterioles to 40% and besides venules to 59% in comparison to the intravascular blood plasma, decreased in a comparison group under the osmotic influence of the perfusion liquid on the mesenterial plate. An injection of an isotonic saline solution is followed only by small fluctuations of the perivascular protein contents during one hour. After blood loss a transitional increase of extravascular protein at the perivenular area was observed indicating the mobilisation of protein depots. Around arterioles the extravascular protein contents did not change significantly. An intravenous injection of albumin solution was followed by a short-termed increase of tissue protein around the arterioles. Around the venules after 50 minutes the extravascular protein contents increased significantly. Within one hour after the changes of the permeability conditions the maximal induceable protein movements in the perivascular space were calculated as +/- 1.35 g% plasma protein concentration corresponding to a maximun protein exchange of +/- 3.1 mg ml(-1) tissue.

Animals↗