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Biomedical subjects

A Larsen

Publications and source records attributed to A Larsen.

At least 19 recordsLinked to original sources
PubMed1992

Cloning of the low-affinity murine granulocyte-macrophage colony-stimulating factor receptor and reconstitution of a high-affinity receptor complex.

A cDNA clone (clone 71) that encodes a low-affinity receptor for murine granulocyte-macrophage colony-stimulating factor (GM-CSF) has been isolated by direct expression. This molecule is the homologue of the human GM-CSF receptor alpha subunit, although homology between these molecules is surprisingly low (less than 35% amino acid identity). The cDNA encodes a polypeptide of 387 amino acids, which contains the conserved features of the hematopoietin receptor superfamily. When expressed in COS-7 cells, this clone encodes a protein that binds radiolabeled murine GM-CSF with low affinity. Coexpression of clone 71 with a cDNA corresponding to a low-affinity interleukin 3 (IL-3) receptor (AIC2A) did not alter the affinity of binding of either GM-CSF or IL-3. However, coexpression of clone 71 with the IL-3 receptor-related cDNA AIC2B generated high-affinity binding sites for murine GM-CSF but not murine IL-3. These studies show that clone 71 and AIC2B are capable of forming an alpha beta complex capable of binding murine GM-CSF with high affinity, while AIC2A appears not to be a component of the murine GM-CSF receptor.

Amino Acid Sequence↗
PubMed1992

The human pseudoautosomal GM-CSF receptor alpha subunit gene is autosomal in mouse.

The gene encoding the granulocyte macrophage colony stimulating factor receptor alpha subunit (CSF2RA) has previously been mapped to the pseudoautosomal region of the human sex chromosomes. In contrast, we report that the murine locus, Csf2ra, maps to an autosome in the laboratory mouse. By in situ hybridization and genetic mapping, Csf2ra maps at telomeric band D2 of mouse chromosome 19. This first instance of a pseudoautosomal locus in human being autosomal in mouse, indicates incomplete conservation between the human and mouse X chromosomes and suggests that the genetic content of the pseudoautosomal region may differ between species of eutherian mammals due to chromosomal rearrangements.

Animals↗
PubMed1992

On sensation, perception and thought: a reply to Rönnberg.

A traditional partition of cognitive phenomena into sensation, perception and thought is reintroduced in response to recent arguments (Rönnberg, 1990) for conditions that must be met in order to distinguish between perception and cognition. The suggested division seems grossly compatible with Rönnberg's basic aim and receives support from several different lines of inquiry, including single cell recordings in the brain, neuropsychology, computational studies of vision and experimental psychology.

Cognition↗
PubMed1991

[Surgical treatment of ileus in the radiation-injured intestine].

Between the years 1977 to 1990, ten patients were operated for ileus due to intestinal damage induced by radiotherapy. The patients had received an average radiation dose of 50.2 GY. Average lapse of time between radiotherapy and operation for ileus was 15.5 months. The operation procedures included were five lysis of adhesions, four by-pass operations, three small intestine resections, one large intestine resection, three transversostomies and one ileostomy. Three patients suffered postoperative complications; one got bronchopneumonia, one suffered prolonged paralytic ileus and one suffered anastomotic leakage, sepsis and fistula formation. Five of the patients have died from their malignant illness. For the five remaining patients the observation time varies from six months to 13 years.

Adult↗
PubMed1991

Interleukin 4 alone or in combination with interleukin 1 stimulates 3T3 fibroblasts to produce colony-stimulating factors.

Colony-stimulating activity (CSA) can be produced by fibroblasts when stimulated by interleukin 1 (IL-1). We show that like IL-1, interleukin 4 (IL-4) can stimulate 3T3 fibroblasts to produce CSA. Biological and molecular analyses show that a significant portion of the CSA is colony-stimulating factor 1 (CSF-1) and granulocyte colony-stimulating factor (G-CSF). CSF-1 production in cells stimulated with a combination of both IL-1 and IL-4 was greater than that observed when cells were stimulated with either cytokine alone. However, the data show a synergistic induction of the expression of high levels of G-CSF mRNA and protein in cells incubated in the presence of both IL-1 and IL-4. The concentration of G-CSF in supernatants from cells stimulated with both IL-1 and IL-4 was at least tenfold higher than that measured in supernatants harvested from cells stimulated with either IL-1 or IL-4 alone. Previous investigations have shown that IL-4 had direct effects on hematopoietic progenitor cell growth. The studies described herein indicate that IL-4 is also involved in the regulation of hematopoiesis in an indirect manner, that is, by playing a role in the regulation of hematopoietic growth factor production.

Animals↗
PubMed1991

Alternative forms of the human G-CSF receptor function in growth signal transduction.

Two forms of the human granulocyte colony-stimulating factor (G-CSF) receptor (HuG-CSFR), differing only at the carboxyl terminus, were recently identified by cDNA cloning. In this report we show that transfection and subsequent expression of either cDNA clone in the interleukin-3 (IL-3)-dependent murine cell line BAF/BO3 converts the cells to G-CSF-responsiveness. The transfected cells bound HuG-CSF in a manner indistinguishable from the native receptors. Expression of a mutant form of the HuG-CSFR, with a deletion in the cytoplasmic domain, in BAF/BO3 cells failed to convert the cells to HuG-CSF-responsiveness. In a similar manner, expression of these two HuG-CSFRs in the interleukin-6 (IL-6)-dependent murine hybridoma B9 resulted in the ability of these cells to grow in HuG-CSF [corrected]. These results strongly suggest that sequences in the first 96 amino acids of the cytoplasmic domain of the HuG-CSFR are required for signal transduction in response to ligand binding.

Animals↗
PubMed1990

Expression cloning of a human granulocyte colony-stimulating factor receptor: a structural mosaic of hematopoietin receptor, immunoglobulin, and fibronectin domains.

We report the isolation from a placental library, of two cDNAs that can encode high affinity receptors for granulocyte colony-stimulating factor (G-CSF) when expressed in COS-7 cells. The cDNAs are predicted to encode integral membrane proteins of 759 and 812 amino acids in length. The predicted extracellular and membrane spanning sequences of the two clones are identical, as are the first 96 amino acids of their respective cytoplasmic regions. Different COOH termini of 34 or 87 residues are predicted for the two cDNAs, due apparently to alternate splicing. The receptor with the longer cytoplasmic domain is the closest human homologue of the murine G-CSF receptor recently described by Fukunaga et al. (Fukunaga, R., E. Ishizaka-Ikeda, Y. Seto, and S. Nagata. 1990. Cell. 61:341). A hybridization probe derived from the placental G-CSF receptor cDNA detects a approximately 3-kb transcript in RNAs isolated from placenta and a number of lymphoid and myeloid cells. The extracellular region of the G-CSF receptors is composed of four distinct types of structural domains, previously recognized in other cell surface proteins. In addition to the two domains of the HP receptor family-defining region (Patthy, L. 1990. Cell. 61:13) it incorporates one NH2-terminal Ig-like domain, and three additional repeats of fibronectin type III-like domains. The presence of both an NH2-terminal Ig-like domain and multiple membrane-proximal FN3-like domains suggests that the G-CSF receptor may be derived from an ancestral NCAM-like molecule and that the G-CSF receptor may function in some adhesion or recognition events at the cell surface in addition to the binding of G-CSF.

Amino Acid Sequence↗
PubMed1990

Contact allergy to the fungicide benomyl?

Benomyl is a widely used fungicide. Contact allergy to benomyl has been reported in a few cases. We describe a group of 62 workers, exposed to benomyl. None had contact dermatitis from benomyl. It appears that benomyl at most is a weak sensitizer. We suggest that earlier-reported allergy may represent cross-reactions and/or that the development of contact allergy to benomyl requires previous exposure to other chemically related pesticides.

Adult↗
PubMed1979

Peripheral neuropathy and myopathy. An experimental study of rats on alcohol and variable dietary thiamine.

The effects of variable dietary thiamine concentrations (deficient, normal, surplus) on the development of alcoholic neuromyopathy in rats exposed for 36 weeks to 10-25% (v/v) ethanol or water (control group) as the sole drinking fluid were studied by histological and electrophysiological methods. Abnormalities in the structure of the sciatic nerve (phagocytosis, myelin abnormalities, increase in nonspecific cholinesterase activity) and tibial muscles (angular atrophic fibers, group atrophy, fibre necrosis) developed more frequently in animals on diets deficient in thiamine than in animals on diets with normal or surplus thiamine, and more frequently in animals drinking alcohol and water than in those drinking water alone. No differences were observed between the different groups in the number of perivascular sympathetic nerves, in the motor nerve conduction velocities and in the muscle fibrillation potentials. Thus, thiamine deficiency, established as a significant reduction of red blood cell transketolase activity, seems to have a deleterious effect on the peripheral nerves and muscles. The effect is enhanced by the simultaneous consumption of ethyl alcohol.

Alcoholism↗
PubMed1979

Ribosomal proteins of the dimorphic fungus, Mucor racemosus.

Ribosomal proteins of the dimorphic fungus Mucor racemosus were isolated and characterized by 2-dimensional gel electrophoresis. Proteins from ribosomes of the yeast and mycelial phase were compared, and were found to be qualitatively indistinguishable. The only consistent difference in the patterns of proteins was in a protein of the 40S subunit, S-6. This protein was phosphorylated in yeast and hyphae forms, but not in asexual sporangiospores. Studies on protein S-6 showed that it contained 3 phosphate residues per molecule of protein when maximally phosphorylated. In this form 3 different tryptic peptides were shown to contain a single phosphoserine. The S-6 protein also existed in forms containing 1 or 2 phosphates per molecule, depending on growth conditions.

Amino Acid Sequence↗
PubMed1979

Disopyramide plasma levels in cardiac patients on maintenance therapy.

The antiarrhythmic agent disopyramide, in a dosage of 200 mg/8 h, was given to 7 cardiac patients. The drug was fairly rapidly absorbed, and the mean peak plasma concentration (3.5 microgram/ml) was measured 1 h after administration of the first dose. The mean biological half-life (7.8 h) was slightly prolonged compared to that reported in normal volunteer subjects. Mean steady state plasma concentrations within the therapeutic range were attained 24--32 h after the start of medication. The fluctuations in the plasma levels were in the order or 30 percent; however, a wide spread of the values was observed. The drug was well tolerated.

Adult↗
PubMed1979

The haemostatic effect of purse-string suture in transvesical prostatectomy: a controlled clinical trial.

In a series of 64 consecutive cases of transvesical prostatectomies it is shown that the use of a purse-string suture at the bladder neck significantly reduces the postoperative blood loss. A follow-up 3 months after operation has shown that the suture did not increase the number of either bladder neck stenoses, urinary incontinences, urinary infections or secondary lithiases.

Aged↗
PubMed1979

Interobserver variation in the evaluation of radiologic changes of rheumatoid arthritis.

The variation between four radiologists in the evaluation of hand, wrist, and foot radiographs of rheumatoid arthritis was examined. The recognition of individual radiologic changes varied considerably as judged by the findings of the different observers. Erosion and joint space narrowing were interpreted more uniformly than soft tissue swelling and osteoporosis. When the radiographs were graded from 0 to 5 using standard reference radiographs, more than 90% of them were graded uniformly or with a difference of only one grade. The investigation has shown that when applying grading of rheumatoid arthritis according to standard reference radiographs, the interobserver variation is considerably less than when pure individual radiological changes of rheumatoid arhtritis are considered.

Adult↗
PubMed1978

Myopathy associated with chronic alcohol drinking. Histological and electrophysiological study.

Muscles of the lower legs of rats given 25% ethanol in water ad libitum for up to 9.5 months were studied using histological, histochemical and electrophysiological techniques. Ethyl alcohol was substituted for about 20% of the total calorific input of the animals. The observations were compared with the structure of the gastrocnemius muscle of five alcoholics with clinical neuropathy. Fibrillation potentials and angulated atrophic fibers were observed in the muscles of animals on alcohol for 9.5 months. No fiber type grouping was present. There was also phagocytosis of the muscle fibers and changes in their internal structure, as reflected by the distribution of NADH-diaphorase. The observed muscle changes in the alcoholics and those in the experimental animals on alcohol differed mainly quantitatively, the only exception being the presence of fiber type grouping in the biopsies from the alcoholics.

Alcoholism↗
PubMed1978

Size scaling in visual pattern recognition.

Human visual recognition on the basis of shape but regardless of size was investigated by reaction time methods. For successive matching of random figures, reaction time increased linearly with the linear size ratio of stimulus pairs. For single-character classification, reaction time increased with divergence between cued size format and stimulus format such that for character nonrepetitions, the increment in latency was approximately proportional to the logarithm of the linear size ratio of the two formats. However, when reactions to character repetitions were faster than those to nonrepetitions, the repetition reaction time function was similar to that for successive matching of random figures. The results suggested two processes of size scaling: mental-image transformation and perceptual-scale transformation. Image transformation accounted for matching performance based on visual short-term memory, whereas scale transformation accounted for size invariance in recognition based on comparison against visual representations in long-term memory.

Adult↗