2,370 research outputs found
Differential Regulation of Inducible Nitric Oxide Synthase Production in Bovine and Caprine Macrophages
Inducible nitric oxide synthase (iNOS) regulation in human and murine macrophages in vitro differs considerably. In this study, expression of macrophage iNOS in ruminants was addressed. Nitric oxide (NO) output by cattle and goat macrophages was as different as that by human and mouse macrophages. Bovine macrophages activated by heated Salmonella dublin or lipopolysaccharide (LPS) expressed high levels of iNOS mRNA, protein, and enzyme activity. Analogously cultured caprine macrophages did not respond to these and other activators by NO generation and iNOS expression. The lack of response was not due to general unresponsiveness to stimuli. Caprine iNOS mRNA was induced by stimulation of caprine macrophages with LPS, as shown by reverse transcription polymerase chain reaction. The level of mRNA expression in activated goat macrophages was lower than in resting bovine macrophages. A caprine 372-bp iNOS mRNA fragment that was sequenced closely resembled the bovine counterpart. This points to species-specific iNOS gene regulation
Differential Regulation of Inducible Nitric Oxide Synthase Production in Bovine and Caprine Macrophages
Inducible nitric oxide synthase (iNOS) regulation in human and murine macrophages in vitro differs considerably. In this study, expression of macrophage iNOS in ruminants was addressed. Nitric oxide (NO) output by cattle and goat macrophages was as different as that by human and mouse macrophages. Bovine macrophages activated by heated Salmonella dublin or lipopolysaccharide (LPS) expressed high levels of iNOS mRNA, protein, and enzyme activity. Analogously cultured caprine macrophages did not respond to these and other activators by NO generation and iNOS expression. The lack of response was not due to general unresponsiveness to stimuli. Caprine iNOS mRNA was induced by stimulation of caprine macrophages with LPS, as shown by reverse transcription polymerase chain reaction. The level of mRNA expression in activated goat macrophages was lower than in resting bovine macrophages. A caprine 372-bp iNOS mRNA fragment that was sequenced closely resembled the bovine counterpart. This points to species-specific iNOS gene regulatio
First insights into structure-function relationships of alkylglycerol monooxygenase
Alkylglycerol monooxygenase is a tetrahydrobiopterin-dependent enzyme that cleaves the O-alkyl-bond of alkylglycerols. It is an exceptionally unstable, hydrophobic membrane protein which has never been purified in active form. Recently, we were able to identify the sequence of alkylglycerol monooxygenase. TMEM195, the gene coding for alkylglycerol monooxygenase, belongs to the fatty acid hydroxylases, a family of integral membrane enzymes which have an 8-histidine motif crucial for catalysis. Mutation of each of these residues resulted in a complete loss of activity. We now extended the mutational analysis to another 25 residues and identified three further residues conserved throughout all members of the fatty acid hydroxylases which are essential for alkylglycerol monooxygenase activity. Furthermore, mutation of a specific glutamate resulted in an 18-fold decreased affinity of the protein to tetrahydrobiopterin, strongly indicating a potential important role in cofactor interaction. A glutamate residue in a comparable amino acid surrounding had already been shown to be responsible for tetrahydrobiopterin binding in the aromatic amino acid hydroxylases. Ab initio modelling of the enzyme yielded a structural model for the central part of alkylglycerol monooxygenase where all essential residues identified by mutational analysis are in close spatial vicinity, thereby defining the potential catalytic site of this enzym
Social Preferences and the Efficiency of Bilateral Exchange
Under what conditions do social preferences, such as altruism or a concern for fair outcomes, generate efficient trade? I analyze theoretically a simple bilateral exchange game: Each player sequentially takes an action that reduces his own material payoff but increases the other playerâs. Each playerâs preferences may depend on both his/her own material payoff and the other playerâs. I identify necessary conditions and sufficient conditions on the playersâ preferences for the outcome of their interaction to be Pareto efficient. The results have implications for interpreting the rotten kid theorem, gift exchange in the laboratory, and gift exchange in the field
Urinary neopterin concentrations vs total neopterins for clinical utility
Fuchs D, Milstien S, KrÀmer A, et al. Urinary neopterin concentrations vs total neopterins for clinical utility. Clinical Chemistry. 1989;35(12):2305-2307.Neopterin measurements are especially useful as an early marker in (e.g.) allograft rejections and in patients infected with human immunodeficiency virus type 1 (HIV-1). An increased concentration of total neopterins (neopterin + dihydroneopterin) is also a significant marker in patients with HIV-1 infection. In this study we compared concentrations of neopterin and total neopterins in urine samples from 77 homosexual men with and 73 without established HIV-1 infection. HIV- 1-seropositive homosexual men had higher concentrations of neopterin and total neopterins (and 7,8-dihydroneopterin) in their urine than did those who were HIV-1-seronegative, and there was a close correlation between neopterin and total neopterins. Both neopterin variables correlated inversely with CD4 + T-cell counts and CD4 +/CD8 + T-cell ratios but not with CD8+ T-cell counts in the HIV-1-seropositive men. Our data indicate that measurements of neopterin and total neopterins are of almost equal potential for clinical diagnosis. However, when measuring total neopterins, which includes oxidation of 7,8- dihydroneopterin to neopterin, more strict requirements of sample collection and handling are necessary to avoid degradation of the 7,8- dihydro derivative
Insights from a Murine Aortic Transplantation Model
Transplant vasculopathy (TV) represents a major obstacle to long-term graft
survival and correlates with severity of ischemia reperfusion injury (IRI).
Donor administration of the nitric oxide synthases (NOS) co-factor
tetrahydrobiopterin has been shown to prevent IRI. Herein, we analysed whether
tetrahydrobiopterin is also involved in TV development. Using a fully
allogeneic mismatched (BALB/c to C57BL/6) murine aortic transplantation model
grafts subjected to long cold ischemia time developed severe TV with intimal
hyperplasia (α-smooth muscle actin positive cells in the neointima) and
endothelial activation (increased P-selectin expression). Donor pretreatment
with tetrahydrobiopterin significantly minimised these changes resulting in
only marginal TV development. Severe TV observed in the non-treated group was
associated with increased protein oxidation and increased occurrence of
endothelial NOS monomers in the aortic grafts already during graft
procurement. Tetrahydrobiopterin supplementation of the donor prevented all
these early oxidative changes in the graft. Non-treated allogeneic grafts
without cold ischemia time and syngeneic grafts did not develop any TV. We
identified early protein oxidation and impaired endothelial NOS homodimer
formation as plausible mechanistic explanation for the crucial role of IRI in
triggering TV in transplanted aortic grafts. Therefore, targeting endothelial
NOS in the donor represents a promising strategy to minimise TV
Catalytic residues and a predicted structure of tetrahydrobiopterin-dependent alkylglycerol mono-oxygenase
Alkylglycerol mono-oxygenase (EC 1.14.16.5) forms a third, distinct, class among tetrahydrobiopterin-dependent enzymes in addition to aromatic amino acid hydroxylases and nitric oxide synthases. Its protein sequence contains the fatty acid hydroxylase motif, a signature indicative of a di-iron centre, which contains eight conserved histidine residues. Membrane enzymes containing this motif, including alkylglycerol mono-oxygenase, are especially labile and so far have not been purified to homogeneity in active form. To obtain a first insight into structureâfunction relationships of this enzyme, we performed site-directed mutagenesis of 26 selected amino acid residues and expressed wild-type and mutant proteins containing a C-terminal Myc tag together with fatty aldehyde dehydrogenase in Chinese-hamster ovary cells. Among all of the acidic residues within the eight-histidine motif, only mutation of Glu137 to alanine led to an 18-fold increase in the MichaelisâMenten constant for tetrahydrobiopterin, suggesting a role in tetrahydrobiopterin interaction. A ninth additional histidine residue essential for activity was also identified. Nine membrane domains were predicted by four programs: ESKW, TMHMM, MEMSAT and Phobius. Prediction of a part of the structure using the Rosetta membrane ab initio method led to a plausible suggestion for a structure of the catalytic site of alkylglycerol mono-oxygenase
The GW Vir instability strip in the light of new observations of PG 1159 stars. Discovery of pulsations in the central star of Abell 72 and variability of RX J0122.9-7521
We present the results of new time series photometric observations of 29
pre-white dwarf stars of PG 1159 spectral type, carried out in the years
2014-2022. For the majority of stars, a median noise level in Fourier amplitude
spectra of 0.5-1.0 mmag was achieved. This allowed the detection of pulsations
in the central star of planetary nebula Abell 72, consistent with g-modes
excited in GW Vir stars, and variability in RX J0122.9-7521 that could be due
to pulsations, binarity or rotation. For the remaining stars from the sample
that were not observed to vary, we placed upper limits for variability. After
combination with literature data, our results place the fraction of pulsating
PG 1159 stars within the GW Vir instability strip at 36%. An updated list of
all known PG 1159 stars is provided, containing astrometric measurements from
the recent Gaia DR3 data, as well as information on physical parameters,
variability, and nitrogen content. Those data are used to calculate
luminosities for all PG 1159 stars to place the whole sample on the theoretical
Hertzsprung-Russell diagram for the first time in that way. The pulsating stars
are discussed as a group, and arguments are given that the traditional
separation of GW Vir pulsators in "DOV" and "PNNV" stars is misleading and
should not be used.Comment: Accepted for publication in ApJ
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