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1.
We studied in the rat the effects of the drug etretinate (Tigason), given at three doses 3, 10, and 30 mg/kg body wt for 1 mo, on the concentrations of Na, K, Ca, Mg, Fe, S, P, Cu, and Zn in the plasma, brain, thymus, heart, liver, lung, kidney, testicle, muscle, and bone. The elements were simultaneously determined in tissues after nitric acid dissolution by inductively coupled plasma emission spectrometry using a JY 48 instrument. At the dose of 3 mg/kg, etretinate did not induce any statistically significant modifications of the element distribution. At the dose of 10 mg/kg, the main observed modifications were in plasma an increase of copper (+38%) and a decrease of zinc (-25%). At the highest dose of 30 mg/kg, some variations of the concentrations of elements in tissues were observed. But, on no account did retinoids induce an alteration of the mineral composition of bone, despite obvious macroscopic bone alterations. 相似文献
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Litman GW; Rast JP; Shamblott MJ; Haire RN; Hulst M; Roess W; Litman RT; Hinds- Frey KR; Zilch A; Amemiya CT 《Molecular biology and evolution》1993,10(1):60-72
Immunoglobulins are encoded by a large multigene system that undergoes
somatic rearrangement and additional genetic change during the development
of immunoglobulin-producing cells. Inducible antibody and antibody-like
responses are found in all vertebrates. However, immunoglobulin possessing
disulfide-bonded heavy and light chains and domain-type organization has
been described only in representatives of the jawed vertebrates. High
degrees of nucleotide and predicted amino acid sequence identity are
evident when the segmental elements that constitute the immunoglobulin gene
loci in phylogenetically divergent vertebrates are compared. However, the
organization of gene loci and the manner in which the independent elements
recombine (and diversify) vary markedly among different taxa. One striking
pattern of gene organization is the "cluster type" that appears to be
restricted to the chondrichthyes (cartilaginous fishes) and limits
segmental rearrangement to closely linked elements. This type of gene
organization is associated with both heavy- and light-chain gene loci. In
some cases, the clusters are "joined" or "partially joined" in the germ
line, in effect predetermining or partially predetermining, respectively,
the encoded specificities (the assumption being that these are expressed)
of the individual loci. By relating the sequences of transcribed gene
products to their respective germ-line genes, it is evident that, in some
cases, joined-type genes are expressed. This raises a question about the
existence and/or nature of allelic exclusion in these species. The
extensive variation in gene organization found throughout the vertebrate
species may relate directly to the role of intersegmental
(V<==>D<==>J) distances in the commitment of the individual
antibody-producing cell to a particular genetic specificity. Thus, the
evolution of this locus, perhaps more so than that of others, may reflect
the interrelationships between genetic organization and function.
相似文献
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In a preliminary paper [Therapie 34, 397 (1979), we showed that cysteine enhances bismuth digestive absorption in rats. In this paper, we have studied in rats the effects of various thiol compounds (mercaptopropionic acid, penicillamine, cysteine, homocysteine, 2-mercaptoethylamine, mercaptoethane) and nonthiol compounds (methionine, serine, alanine) orally administered on the absorption and elimination of bismuth also given orally. Bismuth was measured in blood and urine by electrothermal atomic absorption spectrophotometry.All of the thiol substances, and particularly cysteine, homocysteine, and mercaptopropionic acid, have considerably enhanced bismuth absorption and elimination: whereas, nonthiol substances have had no effect. Moreover, the acute toxicity of bismuth was enhanced when bismuth was given as a complex with cysteine (LD50 = 156± 20 mg/kg).Studies by nmr spectroscopy of interactions between bismuth and these organic compounds have shown that bismuth induces an important chemical shift of the protons of the alpha carbon of the sulfhydrile group. Mainly, studies of 13C and 15N have confirmed this fact. The selectivity of such a complexation, in our pH conditions, may be tentatively explained on the ground of hard and soft acid and base (HSAB) theory.We have suggested that an increase in the concentration of thiol compounds in the gas-trointestinal tract arising from food, or more probably from microorganism synthesis, could be an explanation for human encephalopathies. 相似文献
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Thyroid hormones are involved in copper and zinc distribution in rat tissues. We examined the influence of thyroparathyroidectomy
(TPTY) and of a replacement therapy by T4 on Cu and Zn organ distribution. MT levels were also measured both in basal conditions
and after induction by cadmium. The results confirm that a lack of T4 modified Cu and Zn in serum and tissues. In serum, TPTY
increased Cu (+15%) and ceruloplasmin (+18%), and decreased Zn (−18%). In tissues, Cu was altered in liver (+13%), kidney
(−24%), heart (−16%) duodenum (−18%), and Zn in liver (+25%) and kidney (−10%). The soluble fractions (100,000 g supernatant)
were mainly affected in liver and kidney, and the subcellular fractions in heart and duodenum. MT levels were modified in
basal conditions only in liver (+57%) and kidney (−36%). T4 administration partially prevented the effect of TPTY on both
elements and MT concentrations. Therefore, no evidence is provided for a direct role of T4 in the metabolism of MT in a way
comparable to the effects of glucocorticoids. However, MT could mediate the consequences of TPTY on metal distribution in
certain organs, such as liver and kidney. 相似文献
9.
P Allain D Chaleil D Maingot F Larra 《Comptes rendus des séances de la Société de biologie et de ses filiales》1976,170(1):31-36
Freeze-dried Bacillus Calmette Guerin (B.C.G.) of Institut Pasteur was given by intravenous route to mice at 1,2 and 4 mg/kg before and after gamma irradiation of animals by 1 000 rad. B.C.G. 1 mg/kg injected the day or the day after irradiation has a protective effect (mortality reduced from 77% for controls to 58% and 50% for treated mice). B.C.G. given before irradiation in single or double doses increased mortality. 相似文献
10.
Anne Lorrain Heidi Pethybridge Nicolas Cassar Aurore Receveur Valrie Allain Nathalie Bodin Laurent Bopp C. Anela Choy Leanne Duffy Brian Fry Nicolas Goi Brittany S. Graham Alistair J. Hobday John M. Logan Frederic Mnard Christophe E. Menkes Robert J. Olson Dan E. Pagendam David Point Andrew T. Revill Christopher J. Somes Jock W. Young 《Global Change Biology》2020,26(2):458-470
Considerable uncertainty remains over how increasing atmospheric CO2 and anthropogenic climate changes are affecting open‐ocean marine ecosystems from phytoplankton to top predators. Biological time series data are thus urgently needed for the world's oceans. Here, we use the carbon stable isotope composition of tuna to provide a first insight into the existence of global trends in complex ecosystem dynamics and changes in the oceanic carbon cycle. From 2000 to 2015, considerable declines in δ13C values of 0.8‰–2.5‰ were observed across three tuna species sampled globally, with more substantial changes in the Pacific Ocean compared to the Atlantic and Indian Oceans. Tuna recorded not only the Suess effect, that is, fossil fuel‐derived and isotopically light carbon being incorporated into marine ecosystems, but also recorded profound changes at the base of marine food webs. We suggest a global shift in phytoplankton community structure, for example, a reduction in 13C‐rich phytoplankton such as diatoms, and/or a change in phytoplankton physiology during this period, although this does not rule out other concomitant changes at higher levels in the food webs. Our study establishes tuna δ13C values as a candidate essential ocean variable to assess complex ecosystem responses to climate change at regional to global scales and over decadal timescales. Finally, this time series will be invaluable in calibrating and validating global earth system models to project changes in marine biota. 相似文献