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1.
Evaluation of chemotherapy in experimental toxocarosis by determination of specific immune complexes 总被引:1,自引:0,他引:1
Parasitism by the larval phase of Toxocara canis is a chronic process in which the larvae survive in the tissues, resulting in the constant stimulation of the immune system. As a result, the detection of specific antibodies may not reflect the active state of the parasite. We have studied the dynamics of the production of specific immune complexes by ELISA with the monoclonal antibody TC-1 in rabbits inoculated with single and multiple doses of T. canis eggs. We also compared this with the production of specific antibodies and their possible modification after treatment with mebendazole. The specific antibodies against excretory-secretory antigen were detected with peaks at 10 and 12 weeks depending on the dose and remained positive during the entire experiment (62 weeks). Treatment caused an increase in the level of detectable antibodies dropping to similar levels to the controls. Specific immune complexes were detected only in multiple doses, and were then positive during the entire experiment. From the beginning of treatment the values of immune complexes fell quickly, remaining at undetectable levels during the rest of the experiment. For this reason the detection of specific immune complexes is a valid technique for monitoring the efficiency of treatment. 相似文献
2.
Summary A complete ribosomal DNA (rDNA) repeat unit has been cloned from the genome of Pisum sativum (garden pea) and used to construct a map containing a total of 58 cleavage sites for 23 different restriction enzymes. Regions encoding 18s and 25s ribosomal RNA (rRNA) were identified by R-loop analysis. A 180 bp sequence element is repeated eight times in the intergenic nontranscribed spacer (NTS) region, as defined by eight evenly spaced RsaI cleavage sites. Sequence heterogeneity among these elements (subrepeats) is indicated by the presence of an NcoI site within the five RsaI subrepeats distal to the 25s rRNA gene but not in the three subrepeats proximal to this gene, and also by the presence of an additional RsaI cleavage site in one subrepeat.The approximately 4000 copies of the rDNA repeat in the pea nuclear genome show considerable heterogeneity with respect to the length of the NTS region, and differences are also frequently observed between different genotypes. In both cases the length variation appears to be due primarily to differences in the number of subrepeat elements.Comparison of rDNA restriction maps for two pea genotypes separated for hundreds or perhaps thousands of generations reveals that they contain many rDNA identical repeat units. This data is consistent with the view that new rDNA variants are fixed only infrequently in the evolution of a species.Differences also exist between the rDNA repeats of a single genotype with respect to the degree of base modification at certain restriction sites. A large number of sites known to exist in the pea rDNA clone are not cleaved at all in genomic rDNA, or are cleaved in only some copies of the rDNA repeat. We believe these examples of incomplete cleavage results mostly from methylation, although it is difficult to rule out the possibility of sequence variation in all cases. Most putative modifications are best interpreted in terms of cytosine methylation in CG and CXG sequences, but at least one example is more consistent with adenine methylation.We also have constructed a more detailed restriction map of the wheat rDNA clone pTA71 and present a comparison of this map to our map of pea, pumpkin, and wheat in order to assess the amount of useful evolutionary information that can be obtained by comparison of such maps. 相似文献
3.
Nielsen J; Peixoto AA; Piccin A; Costa R; Kyriacou CP; Chalmers D 《Molecular biology and evolution》1994,11(6):839-853
The region of the clock gene period (per) that encodes a repetitive tract
of threonine-glycine (Thr-Gly) pairs has been compared between Dipteran
species both within and outside the Drosophilidae. All the non-
Drosophilidae sequences in this region are short and present a remarkably
stable picture compared to the Drosophilidae, in which the region is much
larger and extremely variable, both in size and composition. The
accelerated evolution in the repetitive region of the Drosophilidae appears
to be mainly due to an expansion of two ancestral repeats, one encoding a
Thr-Gly dipeptide and the other a pentapeptide rich in serine, glycine, and
asparagine or threonine. In some drosophilids the expansion involves a
duplication of the pentapeptide sequence, but in Drosophila pseudoobscura
both the dipeptide and the pentapeptide repeats are present in larger
numbers. In the nondrosophilids, however, the pentapeptide sequence is
represented by one copy and the dipeptide by two copies. These observations
fulfill some of the predictions of recent theoretical models that have
simulated the evolution of repetitive sequences.
相似文献
4.
Evolutionary origin of human and primate malarias: evidence from the circumsporozoite protein gene 总被引:8,自引:1,他引:7
We have analyzed the conserved regions of the gene coding for the
circumsporozoite protein (CSP) in 12 species of Plasmodium, the malaria
parasite. The closest evolutionary relative of P. falciparum, the agent of
malignant human malaria, is P. reichenowi, a chimpanzee parasite. This is
consistent with the hypothesis that P. falciparum is an ancient human
parasite, associated with humans since the divergence of the hominids from
their closest hominoid relatives. Three other human Plasmodium species are
each genetically indistinguishable from species parasitic to nonhuman
primates; that is, for the DNA sequences included in our analysis, the
differences between species are not greater than the differences between
strains of the human species. The human P. malariae is indistinguishable
from P. brasilianum, and P. vivax is indistinguishable from P. simium; P.
brasilianum and P. simium are parasitic to New World monkeys. The human P.
vivax-like is indistinguishable from P. simiovale, a parasite of Old World
macaques. We conjecture that P. malariae, P. vivax, and P. vivax-like are
evolutionarily recent human parasites, the first two at least acquired only
within the last several thousand years, and perhaps within the last few
hundred years, after the expansion of human populations in South America
following the European colonizations. We estimate the rate of evolution of
the conserved regions of the CSP gene as 2.46 x 10(-9) per site per year.
The divergence between the P. falciparum and P. reichenowi lineages is
accordingly dated 8.9 Myr ago. The divergence between the three lineages
leading to the human parasites is very ancient, about 100 Myr old between
P. malariae and P. vivax (and P. vivax-like) and about 165 Myr old between
P. falciparum and the other two.
相似文献
5.
Photosynthetic enhancement studies performed at 619 nm (excitation of Systems I and II) and at 446 nm (mainly excitation of System I) revealed an 18% photosynthetic enhancement simultaneously with a 31% reduction in glycolate excretion. This observation supports the hypothesis that some glycolate may be consumed in an oxidation process associated with System I when System II is poorly excited and the supply of electrons from the water splitting process of photosynthesis is low. 相似文献
6.
7.
8.
Juan D. Toledo Horacio A. Garda Laura V. Cabaleiro Angela Cuellar Magali Pellon-Maison Maria R. Gonzalez-Baro Marina C. Gonzalez 《Molecular and cellular biochemistry》2013,377(1-2):197-205
Reverse cholesterol transport is a process of high antiatherogenic relevance in which apolipoprotein AI (apoA-I) plays an important role. The interaction of apoA-I with peripheral cells produces through mechanisms that are still poorly understood the mobilization of intracellular cholesterol depots toward plasma membrane. In macrophages, these mechanisms seem to be related to the modulation of the activity of acyl-CoA cholesterol acyltransferase (ACAT), the enzyme responsible for the intracellular cholesterol ester biosynthesis that is stored in lipid droplets. The activation of ACAT and the accumulation of lipid droplets play a key role in the transformation of macrophages into foam cells, leading to the formation of atheroma or atherosclerotic plaque. ApoA-I Helsinki (or ?K107) is a natural apoA-I variant with a lysine deletion in the central protein region, carriers of which have increased atherosclerosis risk. We herein show that treatment of cultured RAW macrophages or CHOK1 cells with ?K107, but not with wild-type apoA-I or a variant containing a similar deletion at the C-terminal region (?K226), lead to a marked increase (more than 10 times) in the intracellular ACAT1 protein level as detected by western blot analysis. However, we could only detect a slight increase in cholesteryl ester produced by ?K107 mainly when Chol loading was supplied by low-density lipoprotein (LDL). Although a similar choline-phospholipid efflux is evoked by these apoA-I variants, the change in phosphatidylcholine/sphyngomyelin distribution produced by wild-type apoA-I is not observed with either ?K107 or ?K226. 相似文献
9.
Hélène Hall Sandra Cuellar‐Baena Vladimir Denisov Deniz Kirik 《Journal of neurochemistry》2013,124(3):336-346
Choline acetyltransferase (ChAT) is the key enzyme for acetylcholine (ACh) synthesis and constitutes a reliable marker for the integrity of cholinergic neurons. Cortical ChAT activity is decreased in the brain of patients suffering from Alzheimer's and Parkinson's diseases. The standard method used to measure the activity of ChAT enzyme relies on a very sensitive radiometric assay, but can only be performed on post‐mortem tissue samples. Here, we demonstrate the possibility to monitor ACh synthesis in rat brain homogenates in real time using NMR spectroscopy. First, the experimental conditions of the radiometric assay were carefully adjusted to produce maximum ACh levels. This was important for translating the assay to NMR, which has a low intrinsic sensitivity. We then used 15N‐choline and a pulse sequence designed to filter proton polarization by nitrogen coupling before 1H‐NMR detection. ACh signal was resolved from choline signal and therefore it was possible to monitor ChAT‐mediated ACh synthesis selectively over time. We propose that the present approach using a labeled precursor to monitor the enzymatic synthesis of ACh in rat brain homogenates through real‐time NMR represents a useful tool to detect neurotransmitter synthesis. This method may be adapted to assess the state of the cholinergic system in the brain in vivo in a non‐invasive manner using NMR spectroscopic techniques. 相似文献
10.
The anabolic action of intermittent parathyroid hormone on cortical bone depends partly on its ability to induce nitric oxide‐mediated vasorelaxation in BALB/c mice 下载免费PDF全文
S Gohin A Carriero C Chenu AA Pitsillides TR Arnett M Marenzana 《Cell biochemistry and function》2016,34(2):52-62
There is strong evidence that vasodilatory nitric oxide (NO) donors have anabolic effects on bone in humans. Parathyroid hormone (PTH), the only osteoanabolic drug currently approved, is also a vasodilator. We investigated whether the NO synthase inhibitor L‐NAME might alter the effect of PTH on bone by blocking its vasodilatory effect. BALB/c mice received 28 daily injections of PTH[1–34] (80 µg/kg/day) or L‐NAME (30 mg/kg/day), alone or in combination. Hindlimb blood perfusion was measured by laser Doppler imaging. Bone architecture, turnover and mechanical properties in the femur were analysed respectively by micro‐CT, histomorphometry and three‐point bending. PTH increased hindlimb blood flow by >30% within 10 min of injection (P < 0.001). Co‐treatment with L‐NAME blocked the action of PTH on blood flow, whereas L‐NAME alone had no effect. PTH treatment increased femoral cortical bone volume and formation rate by 20% and 110%, respectively (P < 0.001). PTH had no effect on trabecular bone volume in the femoral metaphysis although trabecular thickness and number were increased and decreased by 25%, respectively. Co‐treatment with L‐NAME restricted the PTH‐stimulated increase in cortical bone formation but had no clear‐cut effects in trabecular bone. Co‐treatment with L‐NAME did not affect the mechanical strength in femurs induced by iPTH. These results suggest that NO‐mediated vasorelaxation plays partly a role in the anabolic action of PTH on cortical bone. © 2016 The Authors. Cell Biochemistry and Function published by John Wiley & Sons, Ltd. 相似文献