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T Herrmann

Publications and source records attributed to T Herrmann.

At least 109 records · Page 6Linked to original sources
PubMed1991

Spatial problem-solving in a wheel-shaped maze: quantitative and qualitative analyses of the behavioural changes following damage to the hippocampus in the rat.

The behaviour of sham-operated rats and rats with damage to the dorsal hippocampus was compared in a complex spatial problem-solving task using a 'hub-spoke-rim' wheel type maze. Compared to the classical Olton 8-arm radial maze and Morris water maze, this apparatus presents the animal with a series of possible alternative routes both direct and indirect to the goal (food). The task included 3 main stages: exploration, feeding and testing, as do the classic problem-solving tasks. During exploration, hippocampal rats were found to be more active than sham rats. Nevertheless, they displayed habituation and a relatively efficient circumnavigation, though, in both cases, different from those of sham rats. During test trials, hippocampal rats were characterized as being less accurate, making more errors than sham rats. Nevertheless, both groups increased their accuracy of first choices over trials. The qualitative analyses of test trial performance indicated that hippocampal rats were less accurate in terms of the initial error's deviation from the goal, and less efficient in terms of corrective behaviour than sham rats which used either the periphery or the spokes to attain economically the goal. Surprisingly, hippocampal rats were not limited to a taxon type orientation but learned to use the periphery, a tendency which developed over time. Seemingly, for sham rats, the problem-solving process took the form of updating information during transit. For hippocampal rats, the use of periphery reflected both an ability to discriminate its usefulness in reaching the goal via a taxis type behaviour, and some sparing of ability to generalize the closeness and the location of the goal. These results, especially the strategic correction patterns, are discussed in the light of Sutherland and Rudy's 'configurational association theory'.

Animals↗
PubMed1991

Staphylococcal enterotoxin-dependent lysis of MHC class II negative target cells by cytolytic T lymphocytes.

The enterotoxins of Staphylococcus aureus (SE) are extremely potent activators of human and mouse T lymphocytes. In general, T cell responses to SE are MHC class II dependent (presumably reflecting the ability of SE to bind directly to MHC class II molecules) and restricted to responding cells expressing certain T cell receptor beta-chain variable (TCR V beta) domains. Recently we demonstrated that CD8+ CTL expressing appropriate TCR V beta could recognize SE presented on MHC class II-bearing target cells. We now show that MHC class II expression is not strictly required for T cell recognition of SE. Both human and mouse MHC class II negative target cells could be recognized (i.e., lysed) in a SE-dependent fashion by CD8+ mouse CTL clones and polyclonal populations, provided that the CTL expressed appropriate TCR V beta elements. SE-dependent lysis of MHC class II negative targets by CTL was inhibited by mAb directed against CD3 or LFA-1, suggesting that SE recognition was TCR and cell contact dependent. Furthermore, different SE were recognized preferentially by CTL on MHC class II+ vs MHC class II- targets. Taken together, our data raise the possibility that SE binding structures distinct from MHC class II molecules may exist.

Animals↗
PubMed1991

Human major histocompatibility complex class II-negative colon carcinoma cells present staphylococcal superantigens to cytotoxic T lymphocytes: evidence for a novel enterotoxin receptor.

The staphylococcal enterotoxins (SE) bind to major histocompatibility complex (MHC) class II molecules on target cells and activate T cells expressing particular T cell receptor V beta sequences. In this report we demonstrate that SE bind to the MHC class II- SW620, Colo320DM and WiDr human colon carcinoma cell lines and direct cytotoxic T lymphocytes (CTL) to mediate strong target cell killing. Flow cytometry analysis, immunoprecipitation and Northern blotting experiments failed to demonstrate any surface expression of HLA-DR, HLA-DP and HLA-DQ isotypes on the SW620 colon carcinoma cell line, whereas abundant expression of these isotypes was seen on Raji cells, SEB and SEC1 were efficiently presented at picomolar concentration by the MHC class II- colon carcinoma cells and MHC class II+ Raji cells, whereas SEA and SED were preferentially presented on the MHC class II+ Raji cells. An anti-HLA-DR monoclonal antibody inhibited SEB-induced CTL targeting to Raji, but did not influence the killing of SW620 cells. Our data suggests the existence of functionally active SE-binding structures on human colon carcinoma cells which are distinct from the conventional MHC class II molecules. The possibility that these putative new SE receptors play a role in the enterotoxin action of SE must be considered.

Antigens, Bacterial↗
PubMed1991

Role of the medial and lateral septum in a variable goal spatial problem solving task.

Rats with lesions to the medial (MS) or lateral septal (LS) nuclei were compared to normal controls (CNT) in the acquisition of a spatial working memory task. In this task, animals were first allowed to explore the unbaited three-table apparatus before being fed on one of the two possible goal tables. Animals were then tested on their ability to return to the table where they just had been fed. Only rats with medial septal damage were clearly impaired on this problem, an impairment that dissipated over days. In contrast, the performance of LS rats was not significantly different from controls. During the second phase of the experiment, the same animals received either atropine sulphate (50 mg/kg, IP), atropine methylnitrate (50 mg/kg, IP), or an equivalent volume of saline. Atropine sulphate produced a sharp decrease in performance by all subjects. Meanwhile, atropine methylnitrate produced a mild temporary deficit only in LS rats. Overall, these results confirm that the medial septum plays a crucial role in the acquisition of problem solving. In addition, these results also suggest that the lateral septum may play a possible role in some form of spatial behavior easily disrupted by atropine methylnitrate.

Animals↗
PubMed1991

Mismatch between radionuclide and contrast angiography in the assessment of the perfusion of a transplanted kidney.

When early complications occur after a kidney transplant, radionuclide angiography may be useful in determining a possible vascular origin. The authors describe the case of a patient with anuria continuing 24 hours after transplantation. Radionuclide angiography showed a defect at the site of the renal graft, suggestive of arterial or venous thrombosis. Contrast angiography was performed immediately but showed no vascular abnormality; neither did radionuclide angiography performed the next day. The authors concluded that a spasm at the site of the renal artery anastomosis, overcome by contrast angiography, could explain this phenomenon.

Adult↗
PubMed1991

[Radiogenic pneumopathy--synopsis of roentgen image and electron microscopy findings].

Radiation-induced pneumapathia is one of the most frequent complications after radiotherapy to the chest and occurs especially after radiation of bronchial carcinoma (frequency 40-70%, using 50 Gy). The broad ranges of reported frequency indicate differences in defining the degree of radiation-induced damage (clinical picture, plain film, and lung function parameters). This study is to compare plain film findings with electromicroscopy in order to correlate radiological signs with the underlying histo-morphological process.

Animals↗
PubMed1991

The hydroxyproline content in the lung tissue of young pigs after fractionated irradiation with photons or neutrons.

The radiation response of normal lung tissue was studied in 99 young pigs. Five fractions of Co-60-photons and of neutrons with an average energy of 6.2 MeV were applied during overall treatment times of five and 35 days respectively. The irradiation field comprised the whole of the right lung. At eight to ten weeks and at eight to 13 months animals were sacrificed and the removed lungs were investigated histopathologically and biochemically. Radiation induced fibrosis was evaluated by determining the ratio of hydroxyproline concentration of irradiated and non-irradiated lung in the same animal. Above a threshold there was a significant increase of the hydroxyproline ratio with increasing doses. Histopathological findings and hydroxyproline ratio were in close agreement. RBE values between 3.8 and 4.5 were calculated in accordance with the results using the other criteria of lung damage in our studies on pigs.

Animals↗
PubMed1990

Septum and medial frontal cortex contribution to spatial problem-solving.

An attempt was made to contrast the effects of lesions to the medial frontal cortex and septum in two spatial tasks. In the fixed-goal (FG) task, the food was located on the same table throughout testing, and the start table was randomly varied from day to day. In the variable-goal (VG) task, the start table remained constant but the food was randomly distributed on one or the other of the two remaining tables. In both tasks, normal animals performed better than frontal and septal rats whose performance, however, improved over days in the FG, but not in the VG, task. In both tasks, significant improvement within days was found in medial frontal animals, but not in septal animals. Additional analyses revealed that septal animals had a general pattern of disrupted exploration and a tendency to use a response strategy (i.e. to repeat the same response both within and between days) which decreased over days in the FG task. In contrast, medial frontal animals did not demonstrate disrupted exploration nor any response tendency. It is concluded that both septal and medial frontal cortical damage produce a common spatial working memory impairment. However, there is some evidence to suggest that this common memory impairment could result from disruption of distinct mechanisms in septal and frontal animals. It is proposed that medial frontal lesions could affect some specific mechanism related either to attentional processes or to the ability to anticipate future events, whereas septal damage would interfere with the building of comprehensive and flexible spatial memories.

Animals↗
PubMed1990

Activation of MHC class I-restricted CD8+ CTL by microbial T cell mitogens. Dependence upon MHC class II expression of the target cells and V beta usage of the responder T cells.

The T cell response to microbial T cell mitogens (MTM) such as enterotoxins from Staphylococcus aureus (SE) and the soluble mitogen from Mycoplasma arthritidis, resemble the minor lymphocyte stimulatory locus (Mls) response in several aspects. An important feature of the Mls response is it restriction to CD4+ cells. This study demonstrates that in contrast to Mls, the MTM response includes both CD4+ and CD8+ subsets. Both CD4+ and CD8+ cells expanded in IL-2 after stimulation with SEB showed preferential expression of T cell receptors bearing V beta 8 domains. Mouse and human target cells could be lysed in the presence of MTM both by MTM-stimulated CD8+ lymphocytes and by MHC class I-restricted CTL clones of defined Ag specificity. MTM-induced lysis required the expression of MHC class II, but not class I Ag, on the target cells. Inhibition studies of SEB and Ag-dependent cytolysis by CTL clones underlined the crucial role of CD3 and LFA-1 in both instances, but showed CD8 dependence only for AG-dependent cytolysis. Together these findings suggest important differences between the putative MTM-mediated interaction of TCR with MHC molecules and the classical TCR/MHC interaction involved in MHC-restricted Ag recognition.

Animals↗
PubMed1990

High affinity IL-2 receptors on a Hodgkin's derived cell line.

Hodgkin and Sternberg Reed (H and SR) cells, the putative malignant cells of Hodgkin's disease carry regularly T-cell activation antigens, like CD30 and CD25 (low affinity IL-2 receptor). We have investigated the Hodgkin cell line L540, bearing characteristic markers of H and SR cells for its expression of the low affinity IL-2 receptor (IL-2R) and for IL-2. Expression of the low affinity IL-2R was found on mRNA level, by detection of specific 3.5 kb and 1.4 kb mRNA and on the protein level by immunoprecipitation of a 55,000 mol. wt molecule from detergent extracts of surface iodinated cells, however IL-2 specific mRNA was not detected. Scatchard plot analysis revealed the presence of 2 x 10(3) high affinity IL-2Rs. Crosslinking experiments directly demonstrated the high affinity IL-2R to consist of the 55,000 mol.wt light chain (L), and the 70/75,000 (H1/H2) heavy chains. IL-2 was rapidly internalized by these receptors, suggesting that they can be functional. The expression of functional IL-2Rs might be involved in induction or differentiation of Hodgkin's disease.

Fluorescent Antibody Technique↗
PubMed1990

[An occurrence of a neurogenic sarcoma in an irradiated field following the combined surgical-radiologic treatment of a childhood adenosarcoma of the kidney].

Malignant neoplasias in childhood generally are an increased risk for the patient to fall ill with a second tumor. Second tumors in former irradiation field are seldom, but are acknowledged radiogenically if histology is different to that of the first tumor and a sufficiently long period is between the two tumors. A patient is represented who had been operated and irradiated because of an adenosarcoma of the kidney at the age of seven and who has fallen ill with a neurogenic sarcoma in irradiation area more than 30 years later. The same patient had to suffer from radiogenic retardation during differentiation of lumbar apparatus of attitude and locomotion and on the other hand he became father of a healthy daughter at the age of 32.

Child↗
PubMed1990

[Radiogenic effects on liver tissue].

In a review of literature the presented studies on radiogenic liver injuries are summarized. Whereas in the past the liver tissue was supposed to be radioresistant nearly completely, to newer knowledge this organ has to be classed with most radiosensitive tissues at all. The early picture of a liver injury in man is characterized by the veno-occlusive syndrome. Like in Budd-Chiari-Syndrome a congestion begins in the central veins and the centrolobular sinusoids, that has severest threatening consequences for the patients with extensive liver irradiation. The clinic picture is demonstrated. At present no suitable animal model exists for this disease yet. The presented pathological and electron microscopical findings do not allow any final estimation of the pathogenesis in this disease. The radiogenic late-effects are manifested in the liver in a centrolobular fibrosis, also starting from the Glisson's triangles, with cirrhotic reconstruction of liver architecture. The great compensatory power of the organ does not cause clinical pictures to be effected in radiotherapeutic practice with only partial liver irradiation in most cases. The dose-time-relation of the radiogenic hepatitis shows a very little alpha-/beta-value. With this the liver renders as typical late-effect tissue and should be spared effectively by choice of small single doses.

Animals↗
PubMed1990

[The functional efficiency of cardiac pacemakers as affected by ionizing radiation].

Influence of functions of cardiac pace-makers by ionizing radiation are represented, that is characterized in praxis relevant parameters as pulse duration and sensitivity in a special clear manner. For these parameters dose limits were defined in a phantom where tolerance ranges of pace-makers, guaranteed by producer, were over or underdosed. These dose values were different in dependence of installed electronic wiring diagrams. The radioresistance of pace-makers with Lewicki-wiring diagram (MCP 211 L) was higher than those with wiring diagram U 115. Measurings showed that the upper dose limits were greater than the known values with 60Co- and 9-MV-roentgen braking radiation and with that the complete programming and functional capacity of the pace-makers were conserved. The close cooperation of radiologists, physicists, cardiologists and technicians in the implantation clinic guarantees a good care for patients with pace-makers during radiotherapy without complications.

Humans↗
PubMed1990

[The determination of the RBE of neutrons based on the hydroxyproline concentration in the lung tissue of irradiated piglets].

To test the radiogenic reaction of normal lung tissue experiments were done in 99 young pigs altogether. The radiation field included the total right lobe of the lung, 5 fractions of photons or neutrons (mean energy 6.2 MeV) were applied in a total treatment of 5 or 35 days. After killing the animals and taking the lungs the examination of tissue samples and others has been done for contents of hydroxyproline (HP) that has been used to register radiogenic injuries where the relation of irradiated and non-irradiated half of the same animal was estimated as measuring value. Above a limit of 1.13 for the HP-quotient (estimated in non-irradiated controls) there was a significant correlation with dose. Between the results of HP-quotients and histopathological findings a very good correlation was found. Calculation of RBE was done from relation of the dose values of photons and neutrons on base of the same level of injuries. In the tested total dose limit (photons: 14.25-38 Gy, neutrons 3.0-8.5 Gy) RBE-values of 3.8-4.5 were reached that correlates well with other tested criteria of the study in young pigs.

Animals↗
PubMed1990

Spatial behaviour of normal and septal rats on alternate route maze problems.

The behaviour of normal rats and rats with lesions of the septum was compared on a variety of alternate route variations of the three-table problems. In all variations of the task, septal rats were impaired on test trial performance when they displayed stereotypic body turn responses and demonstrated a strong preference for the most direct route between tables both during exploration and testing in all conditions. Normal rats displayed a similar route choice tendency in the simplest situations but shifted route choice behaviour in the most complex configuration, when they chose the inner, but longer, path. The use of the inner path may have allowed delayed-choice, single-point reference orientation, or reduction in the number of available alternatives. It is concluded that normal rats form a cognitive representation that allows them to identify environmental factors likely to facilitate solution, whereas septal rats rely on "taxon"-type strategies that can combine guidances and orientational responses.

Animals↗