PubMed Health⌕ Search

Biomedical subjects

M Reuter

Publications and source records attributed to M Reuter.

At least 19 recordsLinked to original sources
PubMed1992

Detection of colorectal carcinomas by intraoperative RIS in addition to preoperative RIS: surgical and immunohistochemical findings.

The immunoscintigraphic detection of tumour foci less than 1 cm in diameter fails even with single photon emission tomography (SPET) owing to low contrast against background activity. In an attempt to improve detection of macroscopically invisible tumour spread, intraoperative scintimetry (IOSM) with a hand-held gamma-probe was performed in addition to SPET 24-30 and 41-48 h after injection of the technetium-99m carcinoembryonic antigen (CEA MoA) on 12 patients with colorectal carcinoma and 3 patients with different neoplastic and inflammatory diseases. Tumour specimens were measured in vitro in a gamma well counter. For comparison, the presence and amount of CEA in the tumour cells were evaluated immunohistochemically. After modification, the gamma-probe originally designed for iodine-131 was 20 times more sensitive; activities of 99mTc located close to the collimator hole were measured with absolute sensitivity of 100 cps = 2.5 kBq 99mTc. The unfavourably high background activity affected both the in vitro and in vivo analysis: SPET results had been considered positive in 8 of 15 cases. In vitro tumour/non-tumour (t/nt) ratios greater than 2.0 were found in 4 cases. In vivo IOSM resulted in t/nt ratios greater than 2.0 in only 3 patients. In most cases, there was no coincidence of elevated t/nt ratios from the different methods. A correlation was derived between positive immunoscintimetric in vitro findings and immunohistochemically proven interstitial localization of CEA in tumor cells. In conclusion, the measurement technique of IOSM seems adequate, but clinical success will depend on a more specific enrichment of MoA in tumour tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Transcatheter embolization of tumors of the muscular and skeletal systems].

The value of transcatheter embolisation of tumours of the musculoskeletal system is discussed on the basis of 26 cases. All procedures were performed following diagnostic angiography (DSA). By preoperative vascular occlusion it was possible to prevent major blood loss during surgery, provided the operation was carried out within three days of embolisation. Reduction in size of some large inoperable metastases before radio-iodine therapy is another indication for embolisation. As a palliative measure, vascular occlusion can be used for reducing otherwise untreatable skeletal pain and for the management of arteriovenous malformations. Bleeding from a tumour can be controlled by vascular occlusion. Our results indicate that transcatheter embolisation is an effective and reliable technique.

Adolescent↗
PubMed1992

Sensory receptors in the head of Stenostomum leucops. I. Presumptive photoreceptors.

General body sensitivity to light is present in Stenostomum leucops, expressed as increased activity and locomotion of resting animals by exposure to light. The sensory structures involved have not been identified so far. The head of S. leucops bears sensory cells in the ciliary pits, along the epithelium and in connection to the brain lobes. Two types of presumptive photoreceptor, quite distinct from eyespots, are found. The first type, a pair of ciliary lamellate bodies, is found on both sides of the worm between the ciliary pits and the anterior brain lobes. Both cells contain an internally ciliated vacuole. The sparse lamellae are derived from membranes of more than 20 milia, most of them consisting of a typical 9 + 2 axoneme pattern. The cells are connected to brain ganglia by nerve fibres, but there are no connections to the surface. No pigment cups are observed, either. The second type, two cells with light-refracting bodies, is observed more posteriorly, near the dorsal surface and in close nerve connection to the posterior brain lobes. Both cells contain numerous (20-30) refractile, round or ovoid granules of various sizes. They form a cup-shaped structure to one side of the cell, the concave surface directing forward. The granules resemble lipid spheres under the electron microscope. In addition to comparable similarities with presumed photoreceptors in other platyhelminths, the photoreceptive function of the ciliary lamellate bodies and light-refracting bodies was tested using tritiated thymidine ([3H]T) vitamin-A autoradiography. No specific labelling, however, was observed in these cells nor in other sensory cells in S. leucops.

Animals↗
PubMed1991

Activation of restriction endonuclease EcoRII does not depend on the cleavage of stimulator DNA.

The restriction endonuclease EcoRII is unable to cleave DNA molecules when recognition sites are very far apart. The enzyme, however can be activated in the presence of DNA molecules with a high frequency of EcoRII sites or by oligonucleotides containing recognition sites: Addition of the activator molecules stimulates cleavage of the refractory substrate. We now show that endonucleolysis of the stimulator molecules is not a necessary prerequisite of enzyme activation. A total EcoRII digest of pBR322 DNA or oligonucleotide duplexes with simulated EcoRII ends (containing the 5' phosphate group), as well as oligonucleotide duplexes containing modified bases within the EcoRII site, making them resistant to cleavage, are all capable of enzyme activation. For activation EcoRII requires the interaction with at least two recognition sites. The two sites may be on the same DNA molecule, on different oligonucleotide duplexes, or on one DNA molecule and one oligonucleotide duplex. The efficiency of functional intramolecular cooperation decreases with increasing distance between the sites. Intermolecular site interaction is inversely related to the size of the stimulator oligonucleotide duplex. The data are in agreement with a model whereby EcoRII simultaneously interacts with two recognition sites in the active complex, but cleavage of the site serving as an allosteric activator is not necessary.

Allosteric Site↗
PubMed1991

[Radiotherapy of solitary and multiple eosinophilic granulomas of bone (stage I)].

Between 1957 and 1990 15 patients with solitary (stage Ia by Greenberger) and 2 patients with multiple (stage Ib) eosinophilic granuloma of the bone were treated by radiotherapy in 18 locations after previous surgery. The doses applied varied from 6 Gy to 42 Gy (median for patients under 18 years: 8 Gy, for patients over 18 years: 30 Gy). Median follow-up was 9 years (range, 0.3-33 years). Local control rate and survival were 100%. Three patients with granuloma developed a second granuloma within 13 years after primary diagnosis (two bone manifestations, one cutaneous manifestation). Long-term follow-up of patients with solitary eosinophilic granuloma is necessary.

Adolescent↗
PubMed1990

An improved method for the detection of Dcm methylation in DNA molecules.

The intrinsic insensitivity of EcoRII recognition sites in RF DNAs of phage M13 and vector M13mp18 towards this restriction endonuclease can be overcome by adding site-specific oligodeoxyribonucleotide duplexes to the restriction sample. Since Dcm- DNA but not Dcm(+)-methylated DNA becomes susceptible under these conditions, this procedure constitutes an improvement of the Dcm methylation assay.

Bacteriophages↗
PubMed1990

Cloning of the resistant EcoRII recognition site of phage T7 into an EcoRII-sensitive plasmid makes the site susceptible to the restriction enzyme.

The recognition sequence 5'-CC(A/T)GG for EcoRII in the bacteriophage T7 genome is refractory to this restriction endonuclease, despite not bearing the specific (protective) methylation. Following the integration of this site as part of a 219 bp fragment (in which the recognition sequence is flanked by about 100 bp of T7 origin) into the EcoRII-sensitive vector pUC18, the T7 site becomes susceptible to cleavage, too. The same is true of recombinant pBR322 plasmids containing the T7-derived recognition site. The results show that the flanking sequences are not immediately responsible for the refractory behaviour of EcoRII sites and are in agreement with data according to which EcoRII requires the coordinated presence of at least two recognition sites in its DNA substrate.

Cloning, Molecular↗
PubMed1990

Immunocytochemical localization of histamine in flatworms.

Specific antibodies against histamine were used to demonstrate the occurrence and cellular distribution of histamine-like immunoreactivity in three species of flatworms (phylum Platyhelminthes). In the parasitic cestode Diphyllobothrium dendriticum, histamine-reactivity was found in neurons of the main nerve cords, and in cells lining the central and peripheral excretory ducts. In the free-living microturbellarian Microstomum lineare and in the planarian Polycelis nigra, histamine-immunoreactivity was restricted to cells and fibres of the nervous system. The occurrence of histamine or a related substance in the nervous system of flatworms, which represent primary bilateria, indicates the importance of this neuroactive substance in the animal kingdom.

Animals↗
PubMed1989

Oligonucleotide duplexes containing CC(A/T)GG stimulate cleavage of refractory DNA by restriction endonuclease EcoRII.

Some DNA species are resistant towards the restriction endonuclease EcoRII despite the presence of unmodified recognition sites. We show that 14 base-pair oligonucleotide duplexes containing the EcoRII recognition site 5'-CC(A/T)GG are cleaved by this enzyme and are able to stimulate EcoRII cleavage of such resistant DNA molecules (e.g. DNA of bacterial virus T3). A direct correlation between the concentration of oligonucleotide duplex molecules and the degree of EcoRII digestion of the primarily resistant DNA is observed. This indicates a stoichiometric rather than a catalytic mode of enzyme activation. An excess of DNA devoid of EcoRII sites ('non-site' DNA, e.g. MvaI-digested T7 DNA) does not interfere with the activity of EcoRII.

Base Sequence↗
PubMed1989

Development and differentiation of neuronal subsets in asexually reproducing Microstomum lineare. Immunocytochemistry of 5-HT, RF-amide and SCPB.

The development of immunoreactivity (IR) in the nervous system of asexually reproducing Microstomum lineare has been studied by a combination of simultaneous and double immunostaining with antisera to 5-HT and RF-amide, as well as with monoclonal antibodies to SCPB (molluscan small cardioactive peptide). Immunoreactivity appears in a distinct sequential order. 5-HT antigenicity in the postpharyngeal commissure indicates the initiation of the development of a new zooid. The development of a new brain and pharyngeal plexus always starts in connection to the parental nerve cords. Significantly different developmental patterns are observed for the IR to 5-HT and RF-amide, whereas IR to SCPB has the same localization as that to RF-amide, but appears both weaker and later during the development. Influences of the immunoreactive substances on the asexual reproduction and the feeding behaviour are discussed.

Animals↗
PubMed1989

[Current indications for angiography of tumors of the muscular and skeletal systems].

CT and MRI have greatly influenced the indications for angiography as a diagnostic method for tumours of the muscular and skeletal systems. 59 patients with bone and soft tissue tumours were examined by arteriography (DSA) and the indications for arteriography were compared with CT (32 cases) and MRI (15 cases). Particular attention was paid to the presence of vessel encasement. Arteriography is the definitive method for demonstrating vascular involvement. Tomographic methods demonstrate the topographic relationships of the tumour and neuro-vascular structures. Angiography can also be used as an interventional measure pre-operatively or for palliative embolisation.

Adolescent↗
PubMed1989

"Neuroendocrine cells" in flatworms--progenitors to metazoan neurons?

The integrative mechanisms in phylum Platyhelminthes are of considerable phylogenetic interest since ancestral flatworms are believed to be progenitors to all "higher" metazoans. The phylum consists of free-living and parasitic worms. In this group of early bilateral animals, the nervous system is condensed and consists of a bilobed brain and longitudinal nerve cords. Endocrine glands and a circulatory system are still lacking. The present review deals mainly with microturbellarians and parasitic worms. Three main types of neurons, all containing vesicles, occur in the worms: neurons containing dense-core vesicles, peptidergic neurons and sensory neurons. All types of neurons react positively to antisera towards invertebrate and vertebrate neuropeptides. Neurons containing dense-core vesicles are the most frequent type. The dense-core vesicles occur both in the cell soma and in their long processes. Neurons of this type form synaptocrine and paracrine release sites. We ask: Is the neuron containing dcv an archaic type of neuron in which the characteristics of the stem cells for neurons have been preserved?

Animals↗
PubMed1988

EcoRII can be activated to cleave refractory DNA recognition sites.

EcoRII restriction sites [5'-CC(A/T)GG] in phage T3 and T7 DNA are refractory to cleavage by EcoRII, but become sensitive to cleavage in the presence of DNAs which contain an abundance of EcoRII sensitive sites (e.g. pBR322 or lambda DNA). Studies using fragments of pBR322 containing different numbers of EcoRII sites show that the susceptibility to EcoRII cleavage is proportional to the number of sites in the individual fragment. We postulate that EcoRII is the prototype of restriction endonucleases which require at least 2 simultaneously bound substrate sites for their activation. EcoRII sites are refractory when they occur at relatively low frequency in the DNA. The restriction enzyme can be activated by DNA with a higher frequency of sites.

DNA Restriction Enzymes↗
PubMed1988

[Computed tomography of bronchiectasis].

Twenty-six patients with suspected bronchiectasis were examined by bronchography and CT and the CT appearances of normal and abnormal bronchi are described. Like bronchography, CT will distinguish between cylindrical and cystic bronchiectasis. Lobar and segmental localisation can be reliably achieved by both methods; there was agreement between these methods in 109 out of 114 lobes and in 391 out 468 segments. In our experience the sensitivity of CT in the diagnosis of bronchiectasis is 93% and specificity is 96%. It is possible to obtain the necessary information, i.e. the existence and localisation of bronchiectasis by means of CT.

Adult↗
PubMed1988

[Image intensifying split radiography].

This is a report on the testing of a novel system of radiography of the thorax consisting of a combination of moving-slit radiography with a slot-type image intensifier (proximity focussed linear image intensifier), being thus a variant of rotational scanography (or a swinging slot x-ray machine), the image scale being 1:1. The system was compared with conventional x-ray film/foil technique using a group of 115 patients. Special features of the new system are a very low irradiation exposure dose and a 100 x 100 mm size image. It is shown that the imaging method is highly efficient in respect of the examined nine classes of findings and that the image quality of large-size thorax x-ray films is very nearly attained. The low exposure dose, low running cost and advantages in storing and indexing can serve as counter-arguments against the well-known reserved attitude in respect of a medium-size format. The system opens good future possibilities especially with regard to follow-up and monitoring of selected patient groups (e.g. blood donors, medical personnel).

Heart Diseases↗