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Biomedical subjects

I Koch

Publications and source records attributed to I Koch.

At least 37 records · Page 2Linked to original sources
PubMed1992

Analysis of protein sheet topologies by graph theoretical methods.

In order to find rules for the secondary structure prediction of proteins which describe the (sequentially) long-range interactions in sheet structures methods of applied graph theory were used. The so called beta graph which describes the sheet topology was defined for every protein in the Brookhaven Data Bank containing beta sheets. The resemblance of proteins at that topological level is discussed, and four notations and graphic representations of sheets which describe the sequential and topological neighborhoods of the strands were derived. This description level supports the usage of data structures which allow the implementation of efficient algorithms for the analysis and comparison of beta structures in proteins. A computer program for the representation and retrieval of bibliographic data and beta sheet structures was implemented. Some examples for substructure search illustrate the usefulness of the program. Two graphic catalogues were compiled: one contains all beta graphs of PDB proteins and the other all occurring different greek key descriptions.

Computer Simulation↗
PubMed1990

Knowledge-based prediction of protein structures.

We propose a knowledge-based approach to the prediction of protein structures in cases where there is no sequence-homology to proteins with known spatial structure. Using methods from Artificial Intelligence we attempt to take into account long-range interactions within the prediction process. This allows not only the assignment of secondary but also of supersecondary structure elements. In particular, the patterns used as conditions of prediction rules are generated by learning methods from information contained in the Protein Data Base. Patterns on higher levels of the protein structure hierarchy are used as constraints to reduce the combinatorial search space. These patterns may also be used to search for specified structure motifs by interactive retrieval.

Artificial Intelligence↗
PubMed1990

[Morphologic examination of ovaries and liver after repeated administration of cyclophosphamide in therapeutic low doses to immature experimental rodents in various stages of individual maturity].

Liver and ovarian tissue samples of the immature healthy Wistar rats were examined histologically after administration of the repeated low doses of cyclophosphamide. The youngest experimental group was at the age of 7/14 days. Morphologic examination involved histochemical, histoenzymatic, morphometric and ultrastructural techniques. The observed changes in the liver tissue were minimal and totally reversible at time of animals maturity. Pathomorphological changes in ovaries were more evident and complex, concerning all structures of the gland. The dominant features of the damage included the disturbances of the physiological morphological maturation and the widespread hyperluteinization of all structures. In spite of the morphological changes, the activity of the hydroxysteroid dehydrogenases in ovaries remained unchanged.

Animals↗
PubMed1990

Tumour-related expression of a translation-elongation factor-like protein.

We have identified a tumour-related 43 kd cytoplasmic protein (LC/p43) using a monoclonal antibody against the total proteins of human hepatoma cell line PLC/PRF/5. LC/p43 is preferentially expressed in a variety of tumours of human and animal origin, whereas no expression was detected in several normal adult tissues tested. LC/p43 expression was induced in rodent fibroblasts upon transfection with several viral oncogenes. Expression in non-transformed peripheral blood lymphocytes could be induced by treatment with phytohaemagglutinin (PHA) and subsequent culture with interleukin II, whereas retinoic acid treatment of transformed cells caused a drastic reduction of the antigen in the cells. Sequence analysis of three tryptic peptides of LC/p43 revealed 50-70% homology to different domains of the eukaryotic and prokaryotic translation-elongation factors EF1-alpha and EF-Tu, respectively.

Amino Acid Sequence↗
PubMed1989

Expression of a hepatitis B virus transcript containing fused mitochondrial-like domains in human hepatoma cells.

We describe in this report a unique cDNA clone isolated from a cDNA library of the human hepatoma cell line PLC/PRF/5. The clone which was isolated by using a hepatitis B virus (HBV) hybridization probe consists of HBV DNA sequences flanked by cellular sequences on either side. 5' flanking sequences are homologous to a nuclear integrate of the mitochondrial gene URF4 (1) and are in antisense orientation with respect to the viral DNA. The 3' sequences are homologous to the flanking sequences in the previously described genomic PLC/PRF/5 clones pAL10.5 and pAL10.7 (2), or clones AL26 and AL26a, respectively (3). Nucleotide sequencing and hybridization data suggest that the mRNA from which the cDNA was derived was spliced and could have been transcribed from one of the above-mentioned integrates. Consensus promoter sequences located on the antisense strand of the mitochondrial URF4 and predicted to lie 5' to the HBV sequences might have allowed the expression of the transcript.

Base Sequence↗
PubMed1988

[Comparison of sonographic and roentgenologic findings in the paranasal sinuses in children].

Sonography of maxillary sinuses was performed in 362 asymptomatic children with chronic airway diseases, using a 7.5 MHz sector scanner. Pathologic findings were detected in 78 (21.5%) children. Occipito-frontal radiographs of the sinuses were performed in 40 (11%) randomly chosen children and the findings were later compared with those of sonography. An overall agreement in terms of "normal-abnormal" findings was present in 94% of the 80 sinuses examined. In sinuses judged as "normal" or "abnormal" in either of the methods, findings were corresponding as "normal" in 40 of 45 (89%) and as "abnormal" in 35 of 40 (87%) sinuses. A differentiated assessment of pathologic findings showed an agreement in only 19 of 40 (48%) sinuses. Thus, an overall agreement of differentiated findings was present in 59 of 80 (74%) sinuses. Sonography was superior to radiography especially in differentiating the sinus content in secretion, swelling of the mucosa, polyps, cysts and air. In conclusion, sonography offers an accurate screening method for assessment of paranasal sinuses in children.

Adolescent↗
PubMed1988

[Effect of the diagnosis and prevention of exercise-induced bronchial obstruction on sports participation by asthmatic school children].

To assess the sport activities and the previous management of asthmatic children with an exercise-induced bronchial obstruction (EIB), we studied 124 children, aged 8-17 years, with a history of EIB, which was confirmed in a free-running exercise test. Participation in school sports was regular in 38% of the children, irregular in 45% and absent in 17%. Participation in sports outside the school was even lower: In 26% regularly, 18% irregularly and absent in 56%. 17% of all children were not active in any sport. EIB had previously been diagnosed in 38 (31%) children, and 20 (16%) of these had received an appropriate prophylactic medication. Children who received prophylaxis participated significantly more often in school sports (p less than 0.01) and in other sports (p less than 0.05), compared with those who had been diagnosed but had not received prophylaxis. After exercise, peak expiratory flow decreased by a mean of 41% of the preexercise values, but following a prophylactic administration of 0.2 mg Salbutamol-aerosol it decreased only by 2%. A complete protection of EIB was achieved in 94% of the children and the mean %-protection was 95%. The protective effect of 2 mg DNCG-aerosol in 21 children was significantly lower (53%, p less than 0.05) than that of salbutamol and a complete protection was achieved in only 71% (p less than 0.025) of the children.

Airway Resistance↗
PubMed1987

Defective monocyte oxidative metabolism in a child with non-pneumonic legionellosis.

A case of non-pneumonic legionellosis with gastrointestinal manifestations is described in a 13-year-old boy without premorbidity. A selective defect in monocyte oxidative metabolism was found and consistently demonstrated throughout the following year. We suggest that the observed monocyte deficiency may have facilitated the development of legionnaires disease and that otherwise normal monocyte function may have contributed to the favourable course of disease.

Adolescent↗
PubMed1984

[Serum conversion rate following oral poliomyelitis immunization in Mali, Africa 1982].

118 infants under 3 years of age were thrice orally immunised against poliomyelitis at 2 months interval. Before the vaccination 26% were triple negative and 24% triple positive. 44% had neutralising polio antibodies type 1, 53% type 2 and 52% type 3. At the end of the vaccinations 59% of the vaccinees were triple positive and only 3.4% triple negative. 82% had polio antibodies type 1, 85% antibodies type 2 and 76% antibodies type 3. At the start of the trial 54% of the vaccinees excreted enteroviruses. Only in 12% young infants had enterovirus in anal swabs and seroconverted well. In view of the prevalence of paralytic poliomyelitis in tiny babies an early oral polio immunisation in the tropics is highly recommended.

Antibodies, Viral↗
PubMed1983

Classification of scattering objects by regular arrays of scatterers using Fourier analysis.

For a class of scattering objects the mean separation between the scatterers is determined. Over a range of frequencies, ultrasonic back-scattered pressure signals are recorded. It is suggested to derive the mean spacing of an unknown scattering object by employing Fourier analysis and comparing the signal with signals from known regular arrays of scatterers. In a computer simulation it is shown that this approach determines the mean spacing very well for random arrays consisting of three-dimensional spherical scatterers.

Fourier Analysis↗
PubMed1983

[Objectification of the training effect of sports therapy for wheelchair users].

The effects of an additional six-weeks training program were investigated ergometrically and in practice in 10 paraplegics. In order to develop stamina, strength and coordinative abilities, the load components were varied by increasing training frequency, expanding load range and increasing stimuli density. It was possible to show a significant increase in the general physical capacity. The performance parameters of paraplegics were compared with those of wheelchair-bound sports competitors and able-bodied persons. It was possible to improve the capacity of skeletal muscles and bring it closer to that of competitive athletes and able-bodied persons. Trained paraplegics as well as competitive athletes both display to the same extent a conspicuously poorer cardiovascular capacity in relation to able-bodied persons. The reason for this is believed to lie in the extensive muscular and vascular deficiency due to the particular disablement and the poorer venous return resulting from the latter. It points to a reduced overall blood volume and a relatively small heart volume. These investigations are being continued. The findings of sports medicine necessarily require that continuous training take place with relatively high intensity for the purpose of producing a circulatory effect. On the other hand, a basic stamina training must ensure that the indicated capacity reserves of skeletal muscles are developed. The multifaceted possibilities for training within the framework of sport for the disabled are presented.

Adolescent↗
PubMed1983

[Selected morphological features of the rat liver 2-97 days of life].

Examination of rat liver (Wistar strain) led us to distinguish 3 periods of its morphological development. The differences concerned the development hepatocyte cytoplasm and trabecular liver structure. The particularly essential period was observed between 21-42 days after birth; when cytoplasm capacity had the highest rate.

Aging↗
PubMed1979

[Immunity against poliomyelitis in the German Federal Republic (author's transl)].

The immunity of the populations of several countries of the GFR against poliovirus 1, 2 and 3 was investigated in 11 laboratories. Sera of 4707 persons aged 0 to 30 years were assessed for neutralising antibodies (serum dilution 1:4) against the 3 types of poliovirus. 34.5% of the 4707 investigated sera had no neutralising antibodies at least against one type of the poliovirus, 4.7% showed no antibodies against all 3 types of the virus. Especially children aged 0 to 4 years were protected incompletely against the 3 types of poliovirus. In comparison with similar investigations of 1969 and 1972 no decisive change of immunity of the population of the GFR against poliomyelitis has occurred.

Adolescent↗