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G Meyer

Publications and source records attributed to G Meyer.

At least 361 records · Page 20Linked to original sources
PubMed1986

Direct projections from the reticular formation of the medulla oblongata to the anterior cingulate cortex in the mouse and the rat.

After injections of horseradish peroxidase into the anterior cingulate cortex of the mouse and the rat, labeled neurons were observed in different nuclei of the reticular formation of the rostral medulla oblongata: ventral part of the nucleus gigantocellularis, nucleus paragigantocellularis and nucleus lateralis reticularis. Other labeled neurons lay scattered outside the nuclear boundaries, often close to the ventral-most border of the medulla. The projection to the cingulate cortex is sparse, with rarely more than 3 cells per case, but constant. Injections into other cortical areas (visual, motor and somatosensory cortex) did not produce labeling in the medullary reticular formation.

Afferent Pathways↗
PubMed1986

Two-dimensional gel analysis of repetitive nuclear DNA sequences in the genome of Physarum polycephalum. Developmental regulation of the ribosomal gene number.

The composition of repetitive sequences in restriction patterns of nuclear DNA of Physarum polycephalum was determined by high-resolution gel analysis. Three types of repeated DNA fragments in the size range of (0.2-2) X 10(3) base pairs could be identified as discrete spots on the gels and distinguished by their abundance and above-average base composition of either guanine and cytosine (G + C) or adenine and thymidine (A + T). On comparing the DNA composition from exponentially growing plasmodia with that of starved plasmodia, which have become competent to sporulate and have lost 80% of their nuclei, no change was detected among the (A + T)-rich repeat fractions, whereas several of the (G + C)-rich fractions revealed fewer copies in the DNA prepared from starved cells. As shown by hybridization under saturating conditions, the reduction of several (G + C)-rich repeated sequences in the restricted nuclear DNA in sporulation-competent cells can be explained by a 64% elimination of the extrachromosomal nucleolar ribosomal DNA sequences.

Autoradiography↗
PubMed1986

The commissural interconnections of the inferior colliculus in the albino mouse.

In the inferior colliculus of the mouse, 4 cell types project across the collicular commissure: small to medium sized spiny cells, small to medium sized spineless cells, medium sized sparsely spinous neurons and large cells. The axons of large cells give rise to a great number of ipsi- and contralateral collaterals terminating in nests of fine varicose fibers. The anterograde transport of HRP revealed that following injections into the central nucleus, the axonal terminals are arranged in a fixed, ipsi- and contralateral banding pattern across the central, pericentral and external nucleus irrespective of the location of the injection. On the contrary, the position of projecting cells varies with the location of the injection, though the area emitting commissural fibers is not completely homotopic to the injection site but subordinated to the axonal banding pattern.

Animals↗
PubMed1986

Polyomavirus-transformed FR 3T3 rat cells are able to form metastases in syngeneic rats.

A series of polyomavirus-transformed FR 3T3 rat cell lines were tested for their tumorigenic and metastatic properties after subcutaneous inoculation of syngeneic Fisher rats. All of them grew into tumors, which appeared with variable latency periods; the TD50 varied from cell line to cell line. Eight of the 18 transformants that were inoculated gave rise to metastases, always localized in the lung. The capacity to form metastases, though at a low frequency, was also conferred on FR 3T3 cells upon transformation with a recombinant plasmid encoding only the middle-T protein. Fibroblast-like cells were predominantly observed upon histological examination of the metastases. Culture cell lines were derived from independent tumors and metastases induced by two transformants with low and high metastatic potentials, respectively. Metastasis-derived cell lines exhibited metastatic potentials similar to those of the respective original transformants. All the tumor- and metastasis-derived cell lines synthesized the same early viral polypeptides as the respective original transformants; in contrast, the viral DNA integrations evolved during tumor and metastasis formation.

Animals↗
PubMed1986

The olfactory tubercle of the cat. I. Morphological components.

On the basis of morphology and arrangement of cell types, the olfactory tubercle (OT) of the cat is divided into two main components: a cortical part and the cap/hilus regions in which cortical characteristics are not recognizable. The cortical part undergoes a gradual transformation from a more cortex-like structure in the lateral half of the OT - possibly related to the presence of olfactory fibers - to a more striatum-like organization in the medial half. Cell bridges extend between the polymorph layer of the cortical part and the striatum and especially the n. accumbens. The cap regions form 8 or 9 superficial grooves running in a rostro-caudal direction. They contain dwarf and small pyramidal-like neurons and lie immediately ventral to the granule islands of Calleja. Dwarf and small pyramidal-like neurons give rise to an ascending axonal plexus which may contact large neurons in the hilus regions dorsal to the Calleja islands and in part also neurons of the ventral pallidum, the dendrites of which enter the lateral hilus zones. The proportion of dwarf cells to granule cells in the cap regions gradually reverses from lateral, where dwarf cells dominate, to medial, where the caps contain almost exclusively granule cells. No interconnections are observed between the two components of the OT.

Animals↗
PubMed1986

The olfactory tubercle of the cat. II. Immunohistochemical compartmentation.

In this study immunohistochemistry is used to investigate the distribution of opioid peptides, substance P (SP), neuropeptide Y (NPY) and acetylcholine (ChAT) in the olfactory tubercle (OT) of the cat. On the basis of our histochemical findings we divide the OT into two parts: the cortical part and the cap regions, the latter containing the granule cell islands. The cortical part shows an intensely ir-punctate staining pattern (opioid and SP), similar to that observed in the striatum, to which it is connected via plexus bridges. The pyramidal neurons representing the main cell type of the cortical part are ir-negative. NPY-ir neurons invade the OT via the plexus bridges from the striatum and are restricted to the cortical part. A different staining pattern exists in the cap regions: dwarf and small pyramidal-like cells display opioid- and SP-like immunoreactivity and therefore are clearly separated from the cortical part. The intensely stained axonal plexus of the cap-region neurons occupies the hilus regions dorsal to the granule islands. In addition, dendrites of large pallidal neurons densely enmeshed in opioid- and SP-ir fibers (woolly fibers) enter the OT from the dorsally located ventral pallidum, pass through the hilus, traverse the granule islands and reach the dwarf cell layer, where the ir-axons apparently terminate. The granule islands do not receive ir-terminals and the granule cells are ir-negative, except some SP-positive granules in the medial islands. Within the hilus regions some large neurons are ChAT-positive, but the majority is ir-negative. The hilus neurons are regarded as the main target of the cap region efferent system. The findings of this study parallel and confirm our morphological observations (Meyer and Wahle 1986).

Acetylcholine↗
PubMed1986

Localization of NPY-immunoreactivity in the cat's visual cortex.

Using a polyclonal antiserum against neuropeptide Y (NPY; J.M. Allen et al. 1983a) immunohistochemistry was carried out using the PAP method. Neurones displaying NPY-like immunoreactivity are seen mainly in cortical layers V/VI, adjacent white matter and corona radiata. Only few neurones occur in superficial layers II/III. Neurones are multipolar to bitufted with spineless dendrites; somata are either round (layers V, II/III) or spindle-like (layer VI, white matter) with diameters between 16 and 20 microns. Axons were identified by their initial smoother profiles, which are smaller in diameter than principal dendrites, by their typical branching pattern and the occurrence of terminal portions. It was found, that the degree of axonal ramification in proximal parts of axons is rather poor. Most NPY-neurones seem to project intracortically or even locally, except neurones in layers VI and the white matter. The latter neurones have ascending axonal branches terminating in layer VI and V, thus contributing to the dense NPY-plexus in these layers, whereas some layer VI neurones have axonal branches descending into the white matter. The axonal plexus in upper cortical layers is most probably fed by the ascending axons of layer V neurones, passing layer IVc in a strictly vertical direction. Fine smooth fibers of unknown origin which ascend from the white matter in a vertical direction through the grey matter also contribute to the plexus in layer II/III. In semithin sectioned material three terminal types were identified. Firstly, en passant boutons on immunonegative pyramidal neurones, secondly, perisomatically arranged, basket-like terminals, bending around unstained non-pyramidal neurones, and thirdly, about 60 microns long vertically oriented rows of boutons exclusively on apical dendrites of layer II/III pyramidal neurones. Due to the unconspicious axonal pattern and the frequently observed basket-like terminal form, we conclude that most NPY-ir neurones can be regarded as a class of unspecific local field basket cells; the origin of the vertically arranged bouton rows has been yet to determined.

Animals↗
PubMed1986

Methotrexate-vindesine association in head and neck cancer: modification of methotrexate's hydroxylation in presence of vindesine.

High-dose methotrexate (HD-MTX) infusions associated with vindesine (VDS) have been used in the treatment of head and neck cancer. In a previous study, VDS was shown to increase the apparent plasma clearance of MTX. We have studied the MTX hydroxylation process in the presence of VDS. Different routes of administration have been tested (IV pushes and 24-h or 36-h infusions). A radioimmunoassay has been developed to measure 7-OH-MTX. The defined protocols enabled us to show that VDS influences not only the pharmacokinetic behavior of methotrexate but also its hydroxylation, which is decreased in presence of VDS.

Adult↗
PubMed1986

Role of the blood-brain barrier in the establishment of the immune response against polyoma virus-induced cerebral tumours in hamsters.

The existence of an immunological blood-brain barrier (BBB) is well established but its role in cerebral tumour immunology is less well defined. Attempting to clarify this problem we tested the graft rejection of polyoma virus-induced central nervous (CNS) tumours in hamsters after systemic or intracerebral immunization with polyoma virus. Animals were immunized by intracerebral or subcutaneous inoculations of polyoma virus before tumours were induced by intracerebral or intramuscular graft of polyoma-transformed hamster neuroglial cells. The growth of cerebral and muscular tumours was significantly inhibited in animals immunized subcutaneously. In animals immunized intracerebrally the inhibition of growth was highly significant for cerebral tumours and only very slight for intramuscular tumours. These results suggest that the blood-brain barrier allowed immunocompetent effector cells to penetrate inside the CNS but prevented the locally elicited cell-mediated immune response from diffusing outside the CNS. The ability of the brain to develop a local immune response and the partial lack of circulation of immunocompetent cells to cross the BBB could be mainly responsible for the special immune status of the CNS and may greatly interfere with the establishment of an efficient immune response toward brain tumours.

Animals↗
PubMed1986

Surgical technique in operations on pulmonary metastases.

Two hundred and sixty-one patients underwent a total of 295 operations for pulmonary metastases between 1972 and 1984. Some characteristics are essential for the surgical strategy of operations on pulmonary metastases: Upon thoracotomy about 40% of the patients show more uni- or bilateral metastases than expected after the most careful preoperative diagnostic examinations. Approximately 25% of the patients exhibit preoperatively undiagnosed metastases on the contralateral side. Bilateral consecutive thoracotomy is associated with the risk of secondary inoperability. The median thoracotomy takes these characteristics more into consideration than all other routes as both pleural cavities, lung and mediastinum can be explored and treated at the same time. The necessary prerequisites for radical resections are obtained only in this way and potential cure should always be the aim of surgery for metastases. Simultaneous bilateral pulmonary resections require careful postoperative intensive care. The advantage for the patient is a one-stage operation and thus less subjective stress, a much shorter hospitalization and the chance to start necessary postoperative chemotherapy as soon as possible. The median thoracotomy allows all standard resection techniques. With 66%, the atypical and segmental resections were the techniques mainly used. The overall mortality was 3.3%.

Adult↗
PubMed1986

Late results of surgical treatment of pulmonary metastases.

Surgical removal of one or several metastases with a potentially curative aim is possible in the case of isolated pulmonary metastases. The surgery is always part of an overall oncological concept. Between 1972 and 1984, surgery was indicated in 295 cases in 261 patients and 304 thoracotomies were performed. The procedure was classified as potentially curative in 76% of the cases. The 5-year survival probability in this patient group amounted to 38% for all organic tumors. The definitely best prognosis with 5-year survival rates of 42% is observed for caval metastatic carcinoma. Due to the excellent chemotherapeutical regimens, testicular teratomas reach the best individual result with a 3-year survival probability of 71%. Decisive for the long-term prognosis is the removal of all visible and palpable metastases. If radical resectability is possible, the number of metastases is only of secondary importance. Besides radicality, metastatic route and type of the primary tumor, duration of the disease-free interval and the size of the metastases are also of prognostic significance. Predominating resection procedures are the atypical and segment resection and the enucleation which yield the best survival rates.

Adolescent↗
PubMed1986

Intracellular potassium as a possible inducer of amino acid transport across hamster jejunal enterocytes.

Brush border membrane potentials (Vm), intracellular K+ activity (aiK) and alanine uptake were measured in different parts of villi in mid-jejunal tissue taken from hamsters fed different amounts of food at high and low environmental temperatures. Basal villus enterocytes (Y cells) were found to have lower values for Vm and aiK than upper villus enterocytes (O cells). Alanine uptake was confined to O cells. The position on the villus where values for Vm and aiK changed, and where alanine uptake could first be seen to take place, depended on the energy intake and environmental temperature at which hamsters were kept. Na+-dependent alanine uptake and Vm were both higher in O cells of hamsters fed 10 kcal day-1 at 30 degrees C (10 k/30 degrees C) compared with animals fed 30 kcal day-1 at an environmental temperature of 12 degrees C (30 k/12 degrees C hamsters). The rates at which enterocytes migrated along the crypt-villus axis, measured separately in thymidine-labelling experiments, were 6.9 and 16.1 micron h-1 for 10 k/30 degrees C and 30 k/12 degrees C hamsters respectively. Both Vm and aiK were estimated, from these measurements, to have increased significantly by the time enterocytes became 30 h old. Alanine uptake began 15 h later. Neither of these parameters were influenced by previous adaptation conditions. The close temporal and variable positional relationship found between changes in aiK and onset of transport suggests that early changes in electrolyte composition might initiate a second phase of development enabling the enterocyte to absorb nutrients. The possibility that other ions besides K+ might also be involved in this aspect of regulation is also discussed.

Alanine↗
PubMed1986

[Dependence on gambling].

The indicated symptomatology of pathological gambling makes clear that a reduction of the problematic nature of addiction to substance dependence - alcohol, illegal drugs and medicaments - is not valid. Beside the consumption of substance, gambling as well can produce the desired effect, cause pleasant sensations or avoid aversion and addictive behavior can develop. Biological, psychological and sociological theories of pathological gambling are presented, each of which does not serve as a convincing frame of arguments. On the contrary considerations have to be based on an interaction between individual, gambling and social surrounding field to do justice to complex reality. As a matter of fact the actual state of research leaves many questions unanswered. A completion or alternative to the professional methods of treatment consists in the self-help groups which have been founded by dependent gamblers in many cities during the last few years.

Gambling↗
PubMed1986

Retrosigmoid intracanalicular vestibular nerve section: an alternative surgical approach for Menière's disease.

Selective vestibular nerve section has been shown to be an extremely effective treatment for control of vertigo in Menière's disease. In recent years the retrolabyrinthine approach has popularized this form of treatment. An alternative to the retrolabyrinthine approach is presented. It consists of a retrosigmoid intracanalicular dissection, and approach used for acoustic neuroma surgery. A review of the surgical technique, the rationale for its selection over the retrolabyrinthine approach, and the initial results and operative complications during its first eighteen months of use are presented.

Humans↗
PubMed1986

[Occupational therapy in neurology--report of experiences from a university clinic].

Starting from particularities in rehabilitation of neurological patients and by means of special criterions, the authors report on their own experiences in organizing occupational therapy in the neurologic department of a Medical Academy. Beside the requisite of a "therapy maintaining and restoring function", problems of resistance to stress and condition of the patient play a substantial part. Operational therapy within the group-specific situation provides necessary social communication to the neurologic patient, too.

Attention↗