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Biomedical subjects

C Koch

Publications and source records attributed to C Koch.

At least 343 records · Page 19Linked to original sources
PubMed1989

[Sonography of the thyroid gland in children].

The total volume of the thyroid gland is 1.2/1.0 ccm in male/female newborns; it increases with age up to 7.4 ccm in boys and 7.5 ccm in girls (13-16 years). The relation of total thyroid volume and body surface area is without a significant sex difference 4.5/4.8 ccm/sqm in newborn and about 4.8 ccm/sqm in children aged more than 9 years. Thyroid disorders to be discussed are a cyst, a nodule with an echo-free centre, connatal athyreosis and goitre.

Adolescent↗
PubMed1989

[Ultrasonic evaluation of multicystic ovaries in childhood].

High resolution real-time ultrasound showed multicystic pattern of the ovaries in 30 prepubertal infants. In three neonates the cystic abdominal tumour was known since the 33/34 gestational week; the sonographic diagnosis of ovarian cyst was confirmed by the pathologist. The ultrasound study was carried out in 10 patients with suspected idiopathic precocious puberty, whereas in 17 patients, almost 2/3 of the remaining 27 girls, the multicystic ovaries were a fortuitous finding. The maximal diameter of the cysts was 8 mm in multicystic ovaries, one solitary cyst was 13 mm. The follow-up study of 13 patients demonstrated a change in the sonographic pattern. The multicystic structure of the prepubertal ovary is a common finding and must be interpreted as normal.

Adolescent↗
PubMed1989

The Escherichia coli protein, Fis: specific binding to the ends of phage Mu DNA and modulation of phage growth.

We show, using gel retardation, that crude Escherichia coli cell extracts contain a protein which binds specifically to DNA fragments carrying either end of the phage Mu genome. We have identified this protein as Fis, a factor involved in several site-specific recombinational switches. Furthermore, we show that induction of a Mucts62 prophage in a fis lysogen occurs at a lower temperature than that of a wild-type strain, and that spontaneous induction of Mucts62 is increased in the fis mutant. DNasel footprinting using either crude extracts or purified Fis indicate that binding on the left end of Mu occurs at a site which overlaps a weak transposase binding site. Thus, Fis may modulate Mu growth by influencing the binding of transposase, or other proteins, to the transposase binding site(s), in a way similar to its influence on Xis binding in phage lambda.

Autoradiography↗
PubMed1989

Purification of chicken C3 and a structural and functional characterization.

A major plasma protein from chicken, analogous to mammalian complement component C3, was purified by the removal of plasminogen, precipitation with polyethyleneglycol, and ion-exchange chromatography. Purification was guided by a rabbit antiserum specific to chicken C3. The yield of native C3 was 27%, and purity and functional activity was assessed by SDS-PAGE, immunoprecipitation techniques, and the ability of the purified C3 to restore the haemolytic activity of C3-depleted chicken serum. Monoclonal antibodies were raised against purified chicken C3. These antibodies were characterized and used to prepare an immunosorbent column to deplete chicken plasma specifically of C3. Chicken C3 has a mol.wt of 185,000-195,000 and a two-chain structure with an alpha chain (118,000) and beta chain (68,000). Complement activation leads to changes in the electrophoretic mobility of chicken C3 and to a decrease in mol.wt to 144,000 corresponding to the release of a 15,000 C3a and a 34,000 C3d/C3dg fragment. Chicken C3 exists in multiple molecular forms with pI values of 6.4-6.6. A genetic polymorphism of chicken C3 based on electrophoretic mobility has not yet been detected after analysis of more than 500 individuals. The function of chicken C3 is dependent on a reactive thioester because treatment of purified chicken C3 with methylamine causes functional inactivation of C3.

Animals↗
PubMed1989

Hereditary, complete deficiency of complement factor H associated with recurrent meningococcal disease.

Complement factor H (beta-1H globulin) is an important regulatory protein which inhibits the spontaneous complement activation via the alternative pathway. We describe a 15-year-old girl without any detectable factor H in plasma. She has had two episodes of meningococcal disease, but is otherwise completely healthy. Secondary to the factor-H deficiency, the levels of factor B, properdin, C3, and C5-C9 were strongly reduced due to spontaneous in vivo activation of the alternative complement pathway. Plasma C3dg was strongly elevated in spite of the factor-H deficiency; apparently erythrocyte CR1 substitutes for factor H in C3 degradation. Neither C3 nor complement lesions were demonstrable on her erythrocytes which did, however, show increased, spontaneous haemolysis in vitro in citrate plasma, but not in serum. The patient is a single child and her parents, who are unrelated and healthy, had half-normal levels of factor H. This reduction of factor H is sufficient to cause increased, spontaneous activation of the alternative pathway.

Antibodies, Bacterial↗
PubMed1989

Novel primary thymic defect with T lymphocytes expressing gamma delta T cell receptor.

Flow cytometric analysis of the peripheral blood mononuclear cells in a six year old girl with a primary cellular immune deficiency showed a normal fraction of CD3 positive T cells. Most (70%) of the CD3 positive cells, however, expressed the gamma delta and not the alpha beta T cell receptor. Immunoprecipitation and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that most of the gamma delta T cell receptors existed as disulphide-linked heterodimers. Proliferative responses to mitogens were severely reduced, but specific antibody responses after vaccination could be detected. A thymic biopsy specimen showed severe abnormalities of both the thymic lymphoid and epithelial component with abortive medullary differentiation and almost an entire lack of Hassall's corpuscles. This patient represents a case of primary immune deficiency syndrome not previously described. Thymic deficiency associated with a high proportion of T cells expressing the gamma delta T cell receptor has been described in nude mice, and it is suggested that the immune deficiency of this patient may represent a human analogue.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1989

Computing motion in the primate's visual system.

Computing motion on the basis of the time-varying image intensity is a difficult problem for both artificial and biological vision systems. We will show how one well-known gradient-based computer algorithm for estimating visual motion can be implemented within the primate's visual system. This relaxation algorithm computes the optical flow field by minimizing a variational functional of a form commonly encountered in early vision, and is performed in two steps. In the first stage, local motion is computed, while in the second stage spatial integration occurs. Neurons in the second stage represent the optical flow field via a population-coding scheme, such that the vector sum of all neurons at each location codes for the direction and magnitude of the velocity at that location. The resulting network maps onto the magnocellular pathway of the primate visual system, in particular onto cells in the primary visual cortex (V1) as well as onto cells in the middle temporal area (MT). Our algorithm mimics a number of psychophysical phenomena and illusions (perception of coherent plaids, motion capture, motion coherence) as well as electrophysiological recordings. Thus, a single unifying principle 'the final optical flow should be as smooth as possible' (except at isolated motion discontinuities) explains a large number of phenomena and links single-cell behavior with perception and computational theory.

Algorithms↗
PubMed1989

Complement deficiencies in selected groups of patients with meningococcal disease.

We have examined 125 individuals who have earlier had meningococcal (mgc) disease. They belonged to one or more of the following groups: (1) 2 or more cases of mgc disease in the same family; (2) individuals with 2 episodes of mgc disease or with 1 episode of mgc disease and 1 or more episodes of purulent meningitis of another aetiology; and (3) infections with Neisseria meningitidis belonging to serogroups that are uncommon as causes of disease and presumably low-virulent (W-135, 29E, X, Y). Among these we found 15 complement (C)-deficient individuals (12%). The prevalence of C deficiency in the groups above was 7%, 41% and 19%, respectively. The first group (family cases), is very heterogeneous and may be further subdivided into 2 groups: families whose members fell ill within an interval of 30 days (in these the prevalence of C deficiency was 2%), and families in which the interval between mgc disease cases exceeded 30 days (in those the prevalence of C deficiency was 14%). We found a predominance of defects of the initiation pathways, with properdin deficiency being the most common.

Animals↗
PubMed1989

N-acetylcysteine in cystic fibrosis and Pseudomonas aeruginosa infection: clinical score, spirometry and ciliary motility.

The effect of peroral N-acetylcysteine (NAC) in patients with cystic fibrosis (CF) and chronic pulmonary Pseudomonas aeruginosa infection was studied in 52 patients in a double-blind, placebo-controlled, cross-over trial of two, 3 month durations. Active treatment consisted of NAC, 200 mg x 3 daily (patients weighing less than 30 kg) or 400 mg x 2 daily (greater than 30 kg). The effect was evaluated by a subjective clinical score, weight, sputum bacteriology, blood leucocyte count, sedimentation rate, titres of specific antimicrobial antibodies, lung function parameters and measurement of nasal ciliary function in vitro. 31 patients completed the study. No significant differences in lung function or subjective clinical scores were seen between NAC and placebo for the study group as a whole. Patients with peak expiratory flow rate (PEFR) below 70% of predicted normal values showed a satisfactory significant increase in PEFR, forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) during NAC treatment. No effect of NAC on ciliary activity was observed.

Acetylcysteine↗
PubMed1988

Seminal pepsinogen C is not identical with, but is very similar to gastric pepsinogen C.

Human seminal pepsinogen C has been purified and compared with gastric pepsinogen C. The two zymogens cannot be distinguished by amino acid compositions and sequences of the first 28 N-terminal amino acid residues are identical. Apparent immunological identity is observed with polyclonal antisera. Monoclonal antibodies toward seminal pepsinogen C have been produced. One is able to recognize a non-carbohydrate antigenic determinant only present in seminal pepsinogen C.

Amino Acids↗
PubMed1988

Computational neuroscience.

The ultimate aim of computational neuroscience is to explain how electrical and chemical signals are used in the brain to represent and process information. This goal is not new, but much has changed in the last decade. More is known now about the brain because of advances in neuroscience, more computing power is available for performing realistic simulations of neural systems, and new insights are available from the study of simplifying models of large networks of neurons. Brain models are being used to connect the microscopic level accessible by molecular and cellular techniques with the systems level accessible by the study of behavior.

Animals↗
PubMed1988

Serum antibodies to Aspergillus fumigatus catalase in patients with cystic fibrosis.

Seven to ten percent of patients with cystic fibrosis had serum antibodies to the catalase antigen of Aspergillus fumigatus in three cross-sectional surveys between 1977 and 1984. A total of 208 patients participated at least once, and the cumulated frequency of catalase antibodies in 94 patients included in all three surveys was 16%. The titre range was 1 to 16. The prevalence rate of Aspergillus fumigatus in sputum was 50% for a 2.5-year observation period. Catalase antibodies were strongly associated with the occurrence of Aspergillus fumigatus in sputum (p = 0.003), and the microorganism was more numerous in colonized patients with catalase antibodies than in those without such antibodies (p = 0.004). Patients with Aspergillus fumigatus in sputum and a positive catalase antibody test tended to have an adverse development as regards lung function compared to both carriers without antibodies and non-carriers. The observed differences could not, however, be related to different rates of chronic Pseudomonas aeruginosa infection.

Adolescent↗
PubMed1988

Escherichia coli host factor for site-specific DNA inversion: cloning and characterization of the fis gene.

The Escherichia coli (Es. coli) protein Fis (factor for inversion stimulation) stimulates site-specific DNA inversion of the G segment in phage Mu by binding to a recombinational enhancer. By using synthetic oligonucleotides deduced from the amino-terminal amino acid sequence, we have cloned the gene (termed fis) encoding this specific DNA-binding protein. The DNA sequence shows that the Fis protein is basic and contains 98 amino acids. A helix-turn-helix sequence motif characteristic of many DNA-binding proteins is located at the carboxyl-terminal end of the protein. By marker exchange, we have constructed an insertion mutation of fis. Fis is nonessential for Es. coli growth; however, inversion of the G segment of a Mu prophage was not detected in the fis mutant. The fis gene is located between 71 and 72 min on the Es. coli genetic map.

Amino Acid Sequence↗
PubMed1988

Association of arytenoid chondritis with equine lymphocyte antigens but no association with laryngeal hemiplegia, umbilical hernias and cryptorchidism.

Associations were sought between ELA A1-A10 and W11 antigens and the presence of laryngeal hemiplegia, arytenoid chondritis, umbilical hernias and cryptorchidism in Thoroughbreds and/or Quarter Horses. No significant associations were detected between laryngeal hemiplegia and any ELA antigen in Thoroughbreds. The association between arytenoid chondritis and A9 was significant with a relative risk (RR) of 15.6 and aetiologic fraction (EF) of 0.80 in Thoroughbreds. There were apparent associations based on RR between A4 and A5 in Quarter Horses with umbilical hernias (RR = 7.5 and 6.1 respectively); however, these were not statistically significant. No significant associations were detected with cryptorchidism in Quarter Horses when the control population included both sexes. When only unaffected males were used as the control group, there was an apparent increase in relative risk with A6 (from RR = 1.7 to 4.3); however this was not statistically significant. Cryptorchidism in Thoroughbreds showed an increased relative risk with A5 regardless of whether the control population included males and females (RR = 4.1) or only males (RR = 4.7) but the increases were not statistically significant.

Animals↗
PubMed1988

Glucose tolerance and insulin receptor binding to monocytes and erythrocytes in patients with cystic fibrosis.

Cystic fibrosis (CF) is the most frequent life threatening hereditary disease in the Western World with an incidence of approximately 1:2000. Due to increasing survival rates the high frequency of abnormal glucose tolerance has become an important problem. We compared insulin concentrations during oral glucose tolerance test and insulin receptor binding to both monocytes and erythrocytes from 9 patients with CF, with results from 10 healthy controls of similar body weight. The insulin: glucose ratio was increased in the fasting state (p less than 0.05) in patients with CF compared to controls, indicating an increased insulin resistance in CF-patients. The total insulin secretion during oral glucose tolerance test as judged by the area beneath the insulin curve was similar in the two groups, but insulin secretion was significantly delayed in patients with CF. Insulin receptor binding to monocytes and the number of receptors were significantly increased (p less than 0.01 and 0.02, respectively) in patients with CF whereas the dissociation constant was similar in patients with CF and controls. No difference was observed in insulin receptor binding to erythrocytes between the two groups. No correlations were found between insulin receptor binding to monocytes or erythrocytes and glucose tolerance or insulin concentrations.

Adolescent↗
PubMed1988

Increased IgG2 and IgG3 concentration is associated with advanced Pseudomonas aeruginosa infection and poor pulmonary function in cystic fibrosis.

The concentrations of IgG subclass immunoglobulins were determined by radial immunodiffusion in serum from 126 patients with cystic fibrosis (CF). The results were compared to values from age-matched healthy children and adults and correlated to patients age, duration of chronic Pseudomonas aeruginosa infection and lung function parameters. Fifty-two percent of the patients had an elevated concentration of at least one of the IgG subclasses; IgG1 28%, IgG2 16%, IgG3 18% and IgG4 48%. There was significant correlation between elevated serum levels of IgG2, and to a lesser extent IgG3, with decreased lung function (for FEV1; p = 0.0001, and p = 0.001 respectively) and high levels of antipseudomonas precipitins (p = 0.008, and p = 0.002). A similar correlation was not found for IgG1 and IgG4. IgG subclasses vary in their ability to promote phagocytosis and to activate complement and it is possible that individual differences in the IgG subclass pattern could explain the variable course of this disease.

Adolescent↗