| 1. |
- Ayer-LeLievre, C, et al.
(författare)
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Nerve growth factor mRNA and protein in the testis and epididymis of mouse and rat.
- 1988
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 85:8, s. 2628-32
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Tidskriftsartikel (refereegranskat)abstract
- In situ hybridization using beta-nerve growth factor (NGF) DNA probes was used to demonstrate NGF mRNA in spermatocytes and early spermatids of adult mouse. NGF mRNA-containing cells were also identified in the epithelium of convoluted ducts in mouse corpus epididymidis. Blot-hybridization analysis of RNA prepared from mouse testis and epididymis as well as from rat epididymis confirmed the presence of a 1.3-kilobase (kb) NGF mRNA in these tissues. In the rat testis, however, only a 1.5-kb NGF mRNA was found, corresponding in size to a minor NGF mRNA detected in the rat brain, heart, and epididymis. By using affinity-purified anti-NGF antibodies, NGF-like immunoreactivity was observed in germ cells of rat and mouse testis and in the lumen of epididymis. Extracts of both mouse epididymis and testis stimulated fiber outgrowth in cultured sympathetic ganglia, and the effect was blocked by antibodies to mouse NGF. A two-site enzyme immunoassay showed the presence of 10 and 70 ng of NGF per g of tissue in the mouse testis and epididymis, respectively. Furthermore, RNA blot analysis showed the presence of mRNA for the NGF receptor in mouse testis. These results suggest a nonneurotrophic role for NGF in the male reproductive system, possibly in survival maturation and/or motility of spermatozoa.
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| 2. |
- Baker, Thomas C., et al.
(författare)
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Adaptation of antennal neurons in moths is associated with cessation of pheromone-mediated upwind flight
- 1988
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 85:24, s. 9826-9830
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Tidskriftsartikel (refereegranskat)abstract
- A wind-borne plume of sex pheromone from a female moth or a synthetic source has a fine, filamentous structure that creates steep and rapid fluctuations in concentration from a male moth flying up the plume's axis. The firing rates from single antennal neurons on Agrotis segetum antennae decreased to nearly zero within seconds after the antennae were placed in a pheromone plume 70 cm downwind of a high-concentration source known from previous studies to cause in-flight arrestment of upwind progress. In a separate experiment, the fluctuating output from chilled neurons on Grapholita molesta antennae became attenuated in response to repetitive, experimentally delivered pheromone pulses. The attenuation was correlated with a previously reported higher percentage of in-flight arrestment exhibited by moths flying at cooler compared to warmer temperatures. These results indicate that two peripheral processes related to excessive concentration, complete adaptation of antennal neurons, or merely the attenuation of fluctuations in burst frequency, are important determinants of when upwind progress by a moth flying in a pheromone plume stops and changes to station keeping. Also, adaptation and attenuation may affect the sensation of blend quality by preferentially affecting cells sensitive to the most abundant components in airborne pheromone blends.
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| 3. |
- Bjorck, L., et al.
(författare)
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A deletion in a rat major histocompatibility complex class I gene is linked to the absence of β2-microglobulin-containing serum molecules
- 1986
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 83:15, s. 5630-5633
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Tidskriftsartikel (refereegranskat)abstract
- Class I major histocompatibility antigens are composed of a heavy chain that is noncovalently associated with β2-microglobulin (β2m). Most class I molecules are membrane bound, but mouse and rat cDNA clones and genes without a functional code for the transmembrane amino acids have been identified. The membrane-associated class I molecules are important in the control of cell-mediated cytotoxicity, while the function of the soluble molecules remains unclear. Previous studies have shown that β2m circulates in rat serum in three different molecular weight classes. The first is free β2m (M(r), 12,000), the second is about M(r) 70,000, and the third is roughly M(r) 200,000. In an inbred subline of immunodeficient, diabetesprone BioBreeding rats (BioBreeding/Hagedorn), previous work detected two restriction fragment polymorphisms in class I major histocompatibility complex genes, one of them a gene deletion on a 7-kilobase BamHI fragment and the other on a 2-kilobase BamHI fragment. In these rats we have found that the third serum β2m-binding size class is absent. Analysis of F1 and F2 individuals following cross-breeding between Bio-Breeding/Hagedorn rats and genetically related (nondiabetic) control BioBreeding w-subline rats demonstrated that the large-size serum peak of β2m was associated with the presence of the class I restriction fragments.
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| 4. |
- Kirsebom, Leif A, et al.
(författare)
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Involvement of ribosomal protein L7/L12 in control of translational accuracy
- 1985
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 82:3, s. 717-721
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Tidskriftsartikel (refereegranskat)abstract
- The effects of two mutations, which map at the rplL locus and both give a changed 50S ribosomal protein L7/L12, were studied. Both mutations are associated with an increased misreading of all three nonsense codons in vivo and ribosomes from the mutants give an increased misreading of the phenylalanine codon UUU by tRNALeu in vitro. The rplL-associated misreading in vitro is not limited to a particular type of mRNA or tRNA. Results from a translational proofreading assay, using mutant ribosomes, suggest that protein L7/L12 is involved in the control of translational accuracy by contributing to the efficiency of a translational proofreading step(s).
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| 5. |
- Lopez-Rivas, Abelardo, et al.
(författare)
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Ca2+-mobilizing actions of platelet-derived growth factor differ from those of bombesin and vasopressin in Swiss 3T3 mouse cells
- 1987
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : The National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 84:16, s. 5768-5772
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Tidskriftsartikel (refereegranskat)abstract
- Addition of the mitogenic peptides bombesin and vasopressin to quiescent Swiss 3T3 mouse cells increased the cytosolic Ca2+ concentration without any measurable delay. In contrast, there was a significant lag period (16 +/- 1.2 s) before platelet-derived growth factor (PDGF) increased cytosolic Ca2+ concentration. This lag was not diminished at high concentrations of either porcine or human PDGF. Similar results were obtained in 3T3 cells loaded with quin-2 or fura-2. The differences in the effects of bombesin, vasopressin, and PDGF on Ca2+ movements were also substantiated by measurements of 45Ca2+ efflux and of cellular 45Ca2+ content. Activation of protein kinase C by phorbol esters inhibited Ca2+ mobilization induced by either bombesin or vasopressin. In contrast, phorbol esters had no effect on PDGF-induced cytosolic Ca2+ concentration increase or acceleration of 45Ca2+ efflux. Finally, bombesin and vasopressin caused a rapid increase in the production of inositol 1,4,5-trisphosphate and inositol 1,3,4-trisphosphate, whereas PDGF, even at a saturating concentration, exerted only a small effect. These results indicate that the signal transduction pathways activated by PDGF that lead to Ca2+ mobilization can be distinguished from those utilized by bombesin and vasopressin.
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| 6. |
- Méndez, Enrique, et al.
(författare)
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Human protein HC and its IgA complex are inhibitors of neutrophil chemotaxis
- 1986
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 83:5, s. 1472-1475
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Tidskriftsartikel (refereegranskat)abstract
- Protein HC, a heterogeneously charged low molecular weight glycoprotein, and its IgA complex were isolated from human plasma and urine. Plasma from individuals with monoclonal IgA populations was used as starting material for the isolation of the protein HC-IgA complex to obtain homogeneous complex populations. Neither low molecular weight protein HC nor its IgA complex in the concentrations 30 and 600 mg/liter influenced the random migration of normal human neutrophils. The chemotactic response of neutrophils to endotoxin-activated serum was, however, attenuated in a dose-dependent way by both low molecular weight protein HC and protein HC-IgA complex. Concentrations of protein HC and its IgA complex producing significant inhibition of the chemotactic response were found to occur in plasma from healthy and diseased individuals as well as in synovial fluid from patients with rheumatoid arthritis. These results suggest that protein HC and its IgA complex play physiological roles in the regulation of the inflammatory response.
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| 7. |
- Ny, Tor, et al.
(författare)
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Cloning and sequence of a cDNA coding for the human beta-migrating endothelial-cell-type plasminogen activator inhibitor.
- 1986
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 83:18, s. 6776-80
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Tidskriftsartikel (refereegranskat)abstract
- A lambda gt11 expression library containing cDNA inserts prepared from human placental mRNA was screened immunologically using an antibody probe developed against the beta-migrating plasminogen activator inhibitor (beta-PAI) purified from cultured bovine aortic endothelial cells. Thirty-four positive clones were isolated after screening 7 X 10(5) phages. Three clones (lambda 1.2, lambda 3, and lambda 9.2) were randomly picked and further characterized. These contained inserts 1.9, 3.0, and 1.9 kilobases (kb) long, respectively. Escherichia coli lysogenic for lambda 9.2, but not for lambda gt11, produced a fusion protein of 180 kDa that was recognized by affinity-purified antibodies against the bovine aortic endothelial cell beta-PAI and had beta-PAI activity when analyzed by reverse fibrin autography. The largest cDNA insert was sequenced and shown to be 2944 base pairs (bp) long. It has a large 3' untranslated region [1788 bp, excluding the poly(A) tail] and contains the entire coding region of the mature protein but lacks the initiation codon and part of the signal peptide coding region at the 5' terminus. The two clones carrying the 1.9-kb cDNA inserts were partially sequenced and shown to be identical to the 3.0-kb cDNA except that they were truncated, lacking much of the 3' untranslated region. Blot hybridization analysis of electrophoretically fractionated RNA from the human fibrosarcoma cell line HT-1080 was performed using the 3.0-kb cDNA as hybridization probe. Two distinct transcripts, 2.2 and 3.0 kb, were detected, suggesting that the 1.9-kb cDNA may have been copied from the shorter RNA transcript. The amino acid sequence deduced from the cDNA was aligned with the NH2-terminal sequence of the human beta-PAI. Based on this alignment, the mature human beta-PAI is 379 amino acids long and contains an NH2-terminal valine. The deduced amino acid sequence has extensive (30%) homology with alpha 1-antitrypsin and antithrombin III, indicating that the beta-PAI is a member of the serine proteinase inhibitor (serpin) superfamily.
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| 8. |
- Riesbeck, K., et al.
(författare)
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Fluorinated 4-quinolones induce hyperproduction of interleukin 2
- 1989
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 86:8, s. 2809-2813
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Tidskriftsartikel (refereegranskat)abstract
- The fluorinated 4-quinolones are a 'new' group of antibiotics with a broad antibacterial spectrum. They are already widely used in clinical practice. Previous studies have shown that these drugs increase the uptake of [3H]-thymidine into DNA of mitogen-stimulated lymphocytes but inhibit cell growth and immunoglobulin secretion. This study shows that the 4-quinolones strongly (up to 100 times) increase the recovery of interleukin 2 (IL-2) in culture supernatants of phytohemagglutinin (PHA)-stimulated normal human lymphocytes and also prolong the kinetics of IL-2 production. The effect was significant at clinically achievable concentrations (5 μg/ml). In addition to hyperproduction of IL-2, the level of RNA hybridizing with a human IL-2 cDNA probe was also intensely elevated (16-32 times) in PHA-stimulated lymphocytes cultured with ciprofloxacin (80 μg/ml). The mechanism responsible for 4-quinolone-mediated effects on T cells is at present unclear, but evidence is presented that suggests the effect is not exerted at the level of protein kinase C activation. Ciprofloxacin at 80 μg/ml also decreased the expression of IL-2 receptors measured by immunofluorescence with CD 25 antibodies and a radiolabeled IL-2 binding assay. At the same concentration of ciprofloxacin, there was a very low expression of the transferrin receptor and the cell size increased very little in human lymphocytes after PHA stimulation. The enhanced IL-2 production by 4-quinolones may contribute to side effects reported when these drugs are used for treatment of patients.
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| 9. |
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