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Biomedical subjects

H Ritter

Publications and source records attributed to H Ritter.

At least 55 records · Page 3Linked to original sources
PubMed1991

Genetic polymorphism of inter-alpha-trypsin-inhibitor (ITI): formal genetic and linkage analyses.

The polymorphism of inter-alpha-trypsin-inhibitor, ITI, was demonstrated by isoelectric focusing in agarose gels (pH 5-8) followed by protein blotting and immunoassay. Segregation in 239 families with 677 children is consistent with the formal hypothesis that there are two common codominant alleles, ITI*1, ITI*2, and one rare codominant allele, ITI*3, at an autosomal locus ITI. Allele frequencies were calculated as ITI*1 = 0.600, ITI*2 = 0.393, ITI*3 = 0.007. Linkage analysis with 36 markers is presented. Slightly positive lod scores were obtained for PGM3 (zeta = 1.35, theta = 0.10) and AK1 (zeta = 1.34, theta = 0.10).

Alleles↗
PubMed1991

Two different multi-locus probes MZ1.3 and (CAC)5 show nearly the same RFLP pattern.

The RFLP patterns revealed by 2 different multi-locus probes MZ1.3 and (CAC)5 were compared using 4 different restriction enzymes AluI, MboI, HaeIII, HinfI. Irrespective of the restriction enzyme the fingerprints obtained with MZ1.3 and (CAC)5 were almost identical. The MZ1.3 RFLP pattern showed some extra bands which were absent in the (CAC)5 fingerprint.

Amino Acid Sequence↗
PubMed1991

On the statistics of the "genetic fingerprint".

In analogy to the polygene determined morphological features, the DNA-fingerprint is also not suitable for statistical processing. Statements about the individuality are merely speculative. Frequencies of genes cannot be found, since it is impossible to determine which combinations of bands belong to one gene locus. Hence the DNA fingerprint enables the recognition of exclusions from paternity; it does not, however, allow a statistical analysis, no matter which method be employed.

Chromosome Banding↗
PubMed1990

Genetic studies on human thyroxine-binding globulin (TBG).

An enzyme immunoassay technique combined with Western blotting is described to demonstrate thyroxine-binding globulin (TBG) by isoelectric focusing in thin-layer polyacrylamide gels with 8 mol/l urea. Quantitative evaluation was by laser densitometry. No genetic charge variants of TBG were encountered in a sample of 840 unrelated individuals from southwestern Germany. There was no correlation between structural and quantitative variations in the TBG protein. Results from a family with quantitative TBG deficiency strongly support the postulated X-linked mode of inheritance. The method described can be considered as an additional diagnostic tool in thyroid evaluation.

Electrophoresis, Polyacrylamide Gel↗
PubMed1990

Self-organizing maps for internal representations.

One of the biological mechanisms that has so far been poorly understood is the ability of the brain to form representations of primary sensory experiences at increasingly higher levels of abstraction. At many lower perceptual levels, sensory information first becomes represented in topographically ordered sensory maps. In these maps neurons become tuned in a regular manner to simple stimulus features, such as amplitude, frequency, or direction of sound. In this paper it is shown that a model, originally devised by Kohonen for the understanding of the self-organized formation of such "lower-level maps," can also explain the formation of more abstract maps, such as adaptive maps for use in motor control, or maps in which, during a learning stage, the neurons become tuned in an orderly fashion to aspects of the semantic meaning of words. The actual presence of such maps in the brain is speculative at present, but many maps of simpler type have been found. It is argued that the process of the adaptive formation of maps may offer a way to a more unified understanding of many aspects of information processing in the brain.

Animals↗
PubMed1990

A principle for the formation of the spatial structure of cortical feature maps.

Orientation-selective cells in the striate cortex of higher animals are organized as a hierarchical topographic map of two stimulus features: (i) position in visual space and (ii) orientation. We show that the observed structure of the topographic map can arise from a principle of continuous mapping. For the realization of this principle we use a mathematical model that can be interpreted as an adaptive process changing a set of synaptic weights, or synaptic connection strengths, between two layers of cells. The patterns of orientation preference and selectivity generated by the model are similar to the patterns seen in the visual cortex of macaque monkey and cat and correspond to a neural projection that maps a more than two-dimensional feature space onto a two-dimensional cortical surface under the constraint that shape and position of the receptive fields of the neurons very smoothly over the cortical surface.

Animals↗
PubMed1989

Linkage analyses of human peptidase C (PEPC), human factor H (HF), and coagulation factor XIIIB (F13B).

Linkage data on human peptidase C (PEPC), human factor H (HF), and coagulation factor XIIIB (F13B) are presented. The results confirm linkage between HF and F13B (lod = 5.32 at theta = 0.10 in males), and give strong evidence for linkage between PEPC and HF (lod = 5.14 at theta = 0.10 in males) and between PEPC and F13B (lod = 3.55 at theta = 0.10 in males). The claim that PEPA is linked with HF must be withdrawn.

Complement C3b Inactivator Proteins↗
PubMed1989

Linkage analysis in granular corneal dystrophy (Groenouw I), Schnyder's crystalline corneal dystrophy, and Reis-Bücklers' corneal dystrophy.

Tight linkage was excluded for 8 markers in 37 blood relatives from 3 families, 29 of whom had granular corneal dystrophy (Groenouw I). Inconclusive results were obtained for linkage with four marker loci. The highest positive LOD score was 0.57 for linkage between glutamic pyruvic transaminase and granular corneal dystrophy. Tight linkage was excluded for glyoxalase-1 in eight individuals from one family with Schnyder's crystalline corneal dystrophy. Results were inconclusive for another six markers. Positive LOD scores were obtained for linkage with adenylate-kinase 1 and the ABO blood group, with values of 1.16 and 0.67, respectively. Among six blood relatives with Reis-Bücklers' corneal dystrophy, the highest positive LOD score was 1.17 for linkage with mitochondrial malic enzyme. For another six markers informative for linkage analysis, the results were inconsistent.

Blood Group Antigens↗
PubMed1989

Electrophoretic and isoelectric focusing studies in Brazilian Indians: data on four systems.

Three-hundred ninety-nine individuals living in seven populations of two Brazilian Indian tribes (Macushi and Içana River Indians) were tested for the phosphoglucomutase 1 (PGM1), properdin factor B (BF), haptoglobin (HP), and alpha-1-antitrypsin (PI) systems. We observed significant internal heterogeneity in the two tribes for the PGM1 alleles and in the Macushi for the HP markers. Frequencies in three of the four systems (the exception being BF) also show clear differences in the Macushi and Içana River Indians. Compared with other ethnic groups, South American Indians generally present high frequencies of PGM1*1B, BF*S, HP*1S, and PI*M3. On the other hand, PGM1*1A, PI*M1, and PI*M2 are reduced, and HP*1F is absent or rare. This is the first report about HP subtypes among American Indians.

Brazil↗
PubMed1988

Human factor H (beta 1H-globulin): linkage analysis.

Linkage data on human factor H (HF) and 22 other human genetic markers are presented. Close linkage at theta less than 0.10 can be ruled out for a series of marker systems (Rh, PGM1, ACP1, Jk, Tf, Gc, MNSs, ME2, HLA, GLO1, ORM, Gt, PI, Hp, GPT). Strong evidence for linkage was obtained for peptidase A (PEPA) with lods greater than 3.0 at theta = 0.10 in males and at theta = 0.20 for the sexes combined. From this result the HF locus can be provisionally assigned to chromosome 18.

Complement C3b Inactivator Proteins↗
PubMed1988

Formal genetics of esterase D (EC 3.1.1.1): evidence for a sex-phenotype association.

The formal genetics of esterase D (EC 3.1.1.1) was studied in family data and mother/child pairs. A general agreement with mendelian expectations was found. However, a significant sex-phenotype association was detected in families from northwestern Portugal as well as in mother/child pairs and family data from southwestern Germany.

Carboxylesterase↗
PubMed1986

[Results of percutaneous transluminal dilatation of cerebral vascular stenoses].

The present paper is a review of 37 successful catheter dilatations of supra-aortic vascular stenoses. There were sixteen patients with a total of 21 stenoses of the internal carotid, vertebral artery or common carotid artery and sixteen patients with subclavian stenoses. Amongst the patients with stenoses of the cerebral vessels, there were ten with multiple lesions and six with a single stenosis. Three patients had successful dilatations of bilateral stenoses. The indications, technique, and complications of catheter dilatation of lesions of the cerebral vessels are described and discussed.

Adult↗
PubMed1986

[Local streptokinase administration in massive pulmonary embolism].

Five patients with acute massive pulmonary embolism were treated with streptokinase administered via the pulmonary artery as close as possible to the embolus. Streptokinase (Awelysin) was infused at a loading dose of 250,000 IU followed by a maintenance dose of 100,000 IU/hour under haemodynamic and angiographic control. In four of five patients (two patients with cardiogenic shock) the clinical signs, pulmonary artery pressure and the angiographic findings improved or they normalised within 5-12 hours. In one patient with recurrent embolisation over three weeks the clinical condition improved gradually, although the angiographic findings improved only slightly. The results demonstrate that local thrombolysis of acute massive pulmonary embolism is a highly effective form of treatment.

Acute Disease↗