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排序方式: 共有136条查询结果,搜索用时 15 毫秒
1.
Treatment of cardiac myocytes with 8-(4-chlorophenylthio)-adenosine 3'',5''-cyclic monophosphate, forskolin or cholera toxin does not stimulate cellular or heparin-releasable lipoprotein lipase activities.
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Incubation of isolated cardiac myocytes with 500 microM-8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate (CPT-cAMP) or 100 microM-forskolin for 2 1/2 h did not increase the heparin-induced release of lipoprotein lipase (LPL) into the medium. When LPL activity in cardiac myocytes was depleted by treatment of rats with cycloheximide (2 mg/kg; 2.5 h) and inclusion of the protein-synthesis inhibitor in the isolation solutions, incubation with CPT-cAMP or forskolin did not influence the rate of repletion of LPL activity in cells or the recovery of heparin-releasable LPL activity. Although the administration of cholera toxin (0.5 mg/kg; 16-17 h) to rats increased LPL activity in a low-speed supernatant fraction from heparin-perfused hearts, LPL activity was not increased in cardiac myocytes from cholera-toxin-treated rat hearts, and the heparin-induced release of LPL was unchanged. Incubation of cultured ventricular myocytes with 1 microgram of cholera toxin/ml or 500 microM-CPT-cAMP for 24 h did not increase cellular LPL activity or LPL released into the culture medium after a 40 min incubation with heparin. Therefore interventions that stimulate adenylate cyclase activity (forskolin, cholera toxin) or incubation with CPT-cAMP do not increase cellular LPL activity or promote the translocation of LPL to a heparin-releasable fraction in cardiac myocytes. 相似文献
2.
Patricia A. Lampe Ellen B. Cornbrooks Anna Juhasz Eugene M. Johnson James L. Franklin 《Developmental neurobiology》1995,26(2):205-212
Rat sympathetic neurons undergo programmed cell death (PCD) in vitro and in vivo when they are deprived of nerve growth factor (NGF). Chronic depolarization of these neurons in cell culture with elevated concentrations of extracellular potassium ([K+]o) prevents this death. The effect of prolonged depolarization on neuronal survival is thought to be mediated by a rise of intracellular calcium concentration ([Ca2+]i) caused by Ca2+ influx through voltage-gated channels. In this report we investigate the effects of chronic treatment of rat sympathetic neurons with thapsigargin, an inhibitor of intracellular Ca2+ sequestration. In medium containing a normal concentration of extracellular Ca2+ ([Ca2+]o), thapsigargin caused a sustained rise of intracellular Ca2+ concentration and partially blocked death of NGF-deprived cells. Elevating [Ca2+]o in the presence of thapsigargin further increased [Ca2+]i, suggesting that the sustained rise of [Ca2+]i was caused by a thapsigargin-induced Ca2+ influx. This treatment potentiated the effect of thapsigargin on survival. The dihydropyridine Ca2+ channel antagonist, nifedipine, blocked both a sustained elevation of [Ca2+]i and enhanced survival caused by depolarization with elevated [K+]o, suggesting that these effects are mediated by Ca2+ influx through L-type channels. Nifedipine did not block the sustained rise of [Ca2+]i or enhanced survival caused by thapsigargin treatment, indicating that these effects were not mediated by influx of Ca2+ through L-type channels. These results provide additional evidence that increased [Ca2+]i can suppress neuronal PCD and identify a novel method for chronically raising neuronal [Ca2+]i for investigation of this and other Ca2+-dependent phenomena. © 1995 John Wiley & Sons, Inc. 相似文献
3.
The temperature-sensitive (ts) phenotype of a cold-passaged (cp) live attenuated respiratory syncytial virus vaccine candidate, designated cpts530, results from a single amino acid substitution in the L protein.
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K Juhasz S S Whitehead P T Bui J M Biggs J E Crowe C A Boulanger P L Collins B R Murphy 《Journal of virology》1997,71(8):5814-5819
cpts530, a candidate live-virus vaccine, is an attenuated strain of human respiratory syncytial virus (RSV). It was derived by subjecting a cold-passaged (cp) strain of RSV to a single round of chemical mutagenesis. cpts530 is a temperature-sensitive (ts) mutant that is attenuated in mice and chimpanzees, and its ts phenotype exhibits a high level of stability during replication in both species. In the present study, the complete nucleotide sequence of cpts530 RSV was determined. The five mutations known to be present in the parent cpRSV were retained in its cpts530 derivative, and one additional nucleotide change was identified at nucleotide (nt) 10060, which resulted in a phenylalanine-to-leucine change at amino acid 521 in the large polymerase (L) protein. To determine if this single amino acid substitution was indeed responsible for the ts phenotype of cpts530, it was introduced alone or in combination with the cp mutations into the full-length cDNA clone of the wild-type A2 RSV. Analysis of infectious viruses recovered from mutant cDNAs indicated that this single mutation specified complete restriction of plaque formation of recombinant cp530 in HEp-2 cell monolayer cultures at 40 degrees C, and the level of temperature sensitivity was not influenced by the presence of the five cpRSV mutations. These findings identify the phenylalanine-to-leucine change at amino acid 521 in the L protein as the mutation that specifies the ts phenotype of cpts530. Furthermore, these findings illustrate the feasibility of using the cDNA-based recovery system to analyze and construct defined attenuated vaccine viruses. 相似文献
4.
To reveal a potential modulating effect of vasoactive pharmacological agents on the prostanoid production of the venous wall, prostacyclin and thromboxane release from venous tissue slices was studied. Aortic and caval vein samples from 20 rats as well as from 21 cats were studied. Prostacyclin and thromboxane productions were determined by radioimmunoassay as 6-keto-PGF1 alpha and TxB2 released into the incubation medium. Venous tissue produced significantly less prostacyclin per unit weight than arterial tissue in rats (30.7 +/- 4.6 vs. 52.1 +/- 8.2 pg/mg/min), while in cats an opposite situation was found (16.6 +/- 3.2 vs. 7.06 +/- 1.9 pg/mg/min). Thromboxane production of venous tissue was consequently higher than corresponding values for aortic tissue (3.72 +/- 0.46 vs. 1.54 +/- 0.14 in rats and 3.4 +/- 0.6 vs. 1.33 +/- 0.19 in cats, all values in pg/mg/min). Norepinephrine and dopamine significantly increased both the prostacyclin and the thromboxane release from venous tissue, while isoproterenol had no effect. Vasopressin significantly increased thromboxane release and decreased the ratio of prostacyclin vs. thromboxane production (from 10.4 +/- 1.6 to 7.5 +/- 1.6, in acetylsalicylic acid pretreated cats). Angiotensin and thrombin had no significant effects. Bradykinin (0.5 microgram/ml) significantly augmented prostacyclin release from venous tissue (14.4 +/- 2.6 from 10.9 +/- 2.4 pg/mg/min) and decreased thromboxane release (0.65 +/- 0.18 from 1.35 +/- 0.22 pg/mg/min). Methionine-enkephalin (5 micrograms/ml) significantly reduced the thromboxane release from venous tissue slices. The presented material demonstrates that several vasoactive agents modulate the vasoactive prostanoid release of the venous wall. In some cases, the prostacyclin and the thromboxane productions are influenced separately, which in turn will have its impact on smooth muscle activity and thrombocyte aggregation. 相似文献
5.
Despite their production potential and ability to survive on marginal resources in extreme conditions, dromedaries have not been exploited as an important food source. Camels have not been specifically selected for milk production, and genetic improvement has been negligible. High individual variation in milk production both within the population and within breeds provides a good base for selection and genetic progress. In this paper, we discuss the possibilities and constraints of selective breeding for milk production in camels, and include a summary of the use of embryo transfer at the world's first camel dairy farm. Embryo transfer is an integral part of the breeding strategy at the camel dairy farm because it increases selection intensity and decreases the generation interval. Using high milk-producing camels as donors and low producing camels as recipients, 146 embryos were recovered (6.1 ± 1.0 embryos/donor; range: 0–18). Embryos were transferred non-surgically into 111 recipients (83 single and 28 twin embryo transfers). Pregnancy rate at 21 days and 5 months was 55% (61/111) and 45% (50/111), respectively. Finally, a total of 46 recipients delivered a live calf. These results document the utility of embryo transfer using high milk producing dromedaries as donors. 相似文献
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7.
Miklos Szucs Peter Osvath Attila Jakab Daniel Varga Balazs Varga Bela Juhasz 《Reproductive biology》2019,19(1):38-44
The relationship between overweight and male fertility is well studied, still the correlation of obesity and decreased sperm quality is a subject to debate. The widely used conventional spermatological examinations alone seem to be inadequate to assess fertilization potential. Hyaluronan Binding Assay (HBA®) is one of the available validated tests that allows the functional examination of sperm. Data of 72 male patients (mean age 33.9 (24–43) years) from infertile couples were analysed. Body Mass Index (BMI) determination, conventional semen analysis and HBA were performed. Additionally, a relatively new Hyaluronan Bound Matured Sperm Count (HB-MaSC) -index, first introduced by the authors in 2015, was calculated. This index reflects fertilization potential of sperm more precisely. With the increase of BMI, sperm count decreased significantly until about 25?kg/m2, above 25?kg/m2 no further decrease was observed, although sperm count remained permanently low. Greater body weight (in the 70–90?kg range) was observed to have a significant negative effect only on the progressive sperm motility. In addition to sperm concentration and motility, sperm fertilization potential is also negatively affected by obesity, but is irrespective of body weight, as evaluated using BMI + HB-MaSC linear regression analyses adjusted for age and weight. This correlation between male BMI and sperm fertilization potential – as opposed to the conventional correlations with sperm concentration or motility – appears to provide more helpful information in the identification of real capability for fertilization. 相似文献
8.
Jana Holubova Ondrej Stanek Attila Juhasz Illiassou Hamidou Soumana Peter Makovicky Peter Sebo 《PLoS pathogens》2022,18(4)
Pulmonary infections caused by Bordetella pertussis used to be the prime cause of infant mortality in the pre-vaccine era and mouse models of pertussis pneumonia served in characterization of B. pertussis virulence mechanisms. However, the biologically most relevant catarrhal disease stage and B. pertussis transmission has not been adequately reproduced in adult mice due to limited proliferation of the human-adapted pathogen on murine nasopharyngeal mucosa. We used immunodeficient C57BL/6J MyD88 KO mice to achieve B. pertussis proliferation to human-like high counts of 108 viable bacteria per nasal cavity to elicit rhinosinusitis accompanied by robust shedding and transmission of B. pertussis bacteria to adult co-housed MyD88 KO mice. Experiments with a comprehensive set of B. pertussis mutants revealed that pertussis toxin, adenylate cyclase toxin-hemolysin, the T3SS effector BteA/BopC and several other known virulence factors were dispensable for nasal cavity infection and B. pertussis transmission in the immunocompromised MyD88 KO mice. In contrast, mutants lacking the filamentous hemagglutinin (FhaB) or fimbriae (Fim) adhesins infected the nasal cavity poorly, shed at low levels and failed to productively infect co-housed MyD88 KO or C57BL/6J mice. FhaB and fimbriae thus appear to play a critical role in B. pertussis transmission. The here-described novel murine model of B. pertussis-induced nasal catarrh opens the way to genetic dissection of host mechanisms involved in B. pertussis shedding and to validation of key bacterial transmission factors that ought to be targeted by future pertussis vaccines. 相似文献
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