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81.
82.
BACKGROUND: We have been studying an unusual mouse-the BALB/cWt (Wt) male-in which the Y chromosome is susceptible to high rates of mitotic non-disjunction, particularly at the first two cleavage divisions. As these are the same divisions that human embryos generated through assisted reproductive technology must complete in an artificial setting, analysis of the Wt Y chromosome allows us to examine the effect of fertilization and culture in vitro on mammalian chromosome segregation. METHODS: We performed standard mouse IVF, cultured embryos in 5% CO2 in air or in a lowered oxygen atmosphere, and used fluorescence in-situ hybridization to examine the sex chromosome constitutions of 2-, 4-, 8- and 16-cell stage Wt Y-bearing embryos. RESULTS: We observed a significant increase in mosaic sex chromosome aneuploidy at each embryonic stage in embryos cultured in 5% CO2 in air, but under lowered oxygen conditions mosaicism returned to control (in-vivo) levels. CONCLUSIONS: Our results demonstrate that slight alterations in in-vitro conditions may have a considerable impact on the genetic quality of assisted reproductive technology-derived embryos and suggest that the genetic quality of embryos should be a fundamental concern in the development of new culture systems for clinical use. 相似文献
83.
Strychnine sulfate was used to reduce the amount of retrograde amnesia induced by electroconvulsive shock (ECS). Male Swiss-Webster mice were trained on the step-down passive avoidance task, given ECS and then injected intraperitoneally with either 0.1 mg/kg strychnine or saline. The animals were tested in the apparatus one to twenty-four hours later. Mice given ECS alone displayed partial memory for the training (by responding with longer latencies) if tested within two hours after training, but did not display retention twenty-four hours later. Animals given strychnine following ECS had significantly longer step-down latencies at twenty-four hours than did the saline or no injection controls. Further experiments replicated the basic results, and also showed that strychnine injections delayed two hours after the training trial attenuated ECS-induced retrograde amnesia, but that a three hour injection delay was ineffective. The results were interpreted in terms of changes in short-term and long-term memory. 相似文献
84.
Does the availability of either B cells or CD4+ cells limit germinal centre formation? 总被引:3,自引:0,他引:3 下载免费PDF全文
To determine whether the availability of either B cells or T cells regulates the number and size of germinal centres observed following antigenic challenge, irradiated PVG rats were reconstituted with limiting numbers of thoracic duct B cells (with excess T cells) or with limiting numbers of thoracic duct CD4+ cells (with sufficient B cells). Germinal centre formation was measured histologically in the spleens of reconstituted rats 7 days after immunization with 2 x 10(9) sheep erythrocytes (at the height of the germinal centre reaction). Although reconstitution with B cells and antigen alone, or with thymocytes and antigen alone, produced no germinal centres, saturating numbers of germinal centres on the order observed for normal, non-irradiated rats were observed in irradiated rats reconstituted with only 10(7) B cells and 5 x 10(6) CD4+ cells. Germinal centres in the spleens of minimally reconstituted rats were also comparable in size to those observed in normal rats. Reconstitution with either 4 x 10(7) thoracic duct lymphocytes (including 2 x 10(7) B cells, as well as CD8+ and CD4+ cells) or with 4 x 10(7) thoracic duct lymphocytes and 2 x 10(8) thymocytes also led to saturating numbers of germinal centres. It is concluded therefore that (i) CD4+ cells are sufficient for the T-cell contribution required for germinal centre formation, and (ii) some factor other than the availability of B cells or CD4+ cells normally limits germinal centre formation. 相似文献
85.
The aim of this study was to identify any relationships between various patient factors such as age, gender and concurrent medication that may affect plasma cortisol or dexamethasone (DEX) concentrations. Multiple regression analysis was used to formulate an equation to predict plasma DEX levels to identify factors that may influence DEX bioavailability. Pre- and post-DST cortisol levels did not increase with age, but DEX levels were higher in elderly depressed patients. Neither gender nor psychotropic medication affected plasma cortisol or DEX levels. There was no indication that pre-DST cortisol levels influenced plasma DEX levels to account for the lower DEX values in non-suppressors. Age was the only significant factor found in this study to influence DEX levels and it could be argued that the dose of DEX should be lowered when administering the DST to elderly patients to reduce plasma DEX variability. 相似文献
86.
Wilkie SE Newbold RJ Deery E Walker CE Stinton I Ramamurthy V Hurley JB Bhattacharya SS Warren MJ Hunt DM 《Human molecular genetics》2000,9(20):3065-3073
Three different mutations in codon 838 of GUCY2D, the gene for retinal guanylate cyclase 1, have been linked to autosomal dominant cone-rod dystrophy at the CORD6 locus. To examine the relationship between enzyme activity and disease severity, the three disease-causing substitutions (R838C, R838H and R838S) and four artificial mutations (R838A, R838E, R838L and R838K) were generated. Assay of GCAP1-stimulated cyclase activity in vitro shows that, compared with wild-type, R838E, R838L and R838K possess only low activity, whereas R838A, R838C, R838H and R838S have activity equal or superior to wild-type at low Ca(2+) concentrations. These four latter mutants showed a higher apparent affinity for GCAP1 than did wild-type. The Ca(2+) sensitivity of the GCAP1 activation was also altered with marked residual activity at high Ca(2+), the effect increasing: wild-type < R838C < R838H < R838A < R838S. Within the photoreceptor, this would result in a failure to inactivate cyclase activity at high physiological Ca(2+ )concentrations. Amongst the three disease-associated mutations, the effect correlates directly with disease severity. The wild-type and R838H mutant displayed a difference in pH sensitivity, with the mutant showing a higher specific activity with pH > 6.0. Site 838 is in the dimerization domain that forms a coiled-coil in the active protein. A computer-aided structure prediction of this region indicates that R838 in the wild-type breaks the structure at four helical turns, and there is an increasing tendency for the structure to continue for further turns in the order R838C < R838H,S,K < R838E < R838A < R838L. 相似文献
87.
The cellular receptor of subgroup B avian leukosis virus (ALVB) is encoded by a gene at the tumour virus B (TVB) locus. TVB alleles encode specific receptors permitting infection by exogenous ALVB or avian leukosis virus subgroup D (ALVD) as well as endogenous avian leukosis virus subgroup E (ALVE), and thus susceptibility is dominant to resistance. Two single nucleotide polymorphisms at the TVB locus have been reported distinguishing three TVB alleles (TVB*S1, TVB*S3 and TVB*R). We have developed a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay using the two single nucleotide polymorphisms to define three observed allelic haplotypes and to identify the six possible TVB genotypes consisting of the three haplotypes in defined laboratory strains of chickens. One additional potential allelic haplotype and four genotypes were also briefly discussed. Chickens from parents heterozygous for different TVB alleles were challenged with Rous sarcoma viruses of subgroup ALVB and ALVE to induce wing-web tumours. Tumour incidences were evaluated between chickens of the genotypes determined with this newly developed PCR-RFLP assay. Importantly, chickens typed with this assay as TVB*S3/*S3 were resistant to infection by ALVE only, and those TVB*R/*R were resistant to both ALVE and ALVB. Furthermore, a vast majority of chickens with the susceptible TVB*S1/- genotypes developed a tumour. This PCR-RFLP assay enables a relatively rapid assessment of all six anticipated TVB genotypes in experimental strains of chickens undergoing segregation for TVB*S1, TVB*S3, and TVB*R alleles. This non-infectious assay should be further evaluated for the capacity to select and breed commercial chickens for genetic resistance to infections by ALVB, ALVD and ALVE. 相似文献
88.
Guimezanes A Barrett-Wilt GA Gulden-Thompson P Shabanowitz J Engelhard VH Hunt DF Schmitt-Verhulst AM Engelhardt VH 《European journal of immunology》2001,31(2):421-432
We studied the molecular basis for CD8 independence of in vivo generated (BM3.3) versus CD8 dependence of in vitro sensitized (KB5.C20/Des) alloreactive H-2K(b)-specific cytotoxic T lymphocytes (CTL). Using microcapillary high-performance liquid chromatography fractionation of H-2K(b) eluates, mass spectrometry and CTL reconstitution assays, we determined that BM3.3 and KB5.C20 recognize, respectively, a single peptide (pBM1) expressed on 8,000 H-2K(b) molecules per allogeneic cell, and three distinct peptides (pKB1, 2, 3), each expressed on around 200 H-2K(b) molecules per allogeneic cell. CD8 (in)dependence was intrinsic to the respective TCR/H-2K(b)-peptide interactions. KB5.C20 and BM3.3 TCR illustrate the correlation that appears to exist between CD8 dependence/low affinity and in vitro sensitization as opposed to low dependency on CD8 and high TCR affinity observed after in vivo sensitization. The results suggest that CD8-dependent alloreactive CTL obtained in vitro with high frequency correspond to low-affinity TCR from the MHC-biased TCR repertoire unpurged by negative selection and have implications for cellular immunotherapeutic approaches. 相似文献
89.
C M Thumwood N H Hunt W B Cowden I A Clark 《British journal of experimental pathology》1989,70(3):293-303
A/J and CBA/H mice infected with Plasmodium berghei ANKA, a murine model of cerebral malaria, were used to see whether antioxidants influenced the outcome of this disease. Untreated, infected mice died 7 to 9 days after infection, often with cerebral symptoms. Haemorrhages, mononuclear infiltration and oedema were present in the central nervous system (CNS). Feeding a diet containing 0.75% (w/w) butylated hydroxyanisole (BHA) greatly altered the course of this disease. Death was delayed by up to 2 weeks and mice appeared healthy at parasitaemias that would have caused cerebral symptoms and death had they been on a conventional diet. BHA-fed mice showed few or no cerebral symptoms at a time at which control mice were clearly affected, and greatly reduced haemorrhages, mononuclear infiltration and oedema when the CNS was examined. Similar, but more consistent, protective effects were seen after administration of BHA by repeated injections or in osmotic pumps. The combination of superoxide dismutase and catalase, coupled to polyethylene glycol, when administered intravenously also protected mice against death from cerebral complications. Permeability of the blood-brain barrier was monitored by the use of 125I-labelled bovine serum albumin, 51Cr-labelled erythrocytes and the dye Evans blue, all of which are normally excluded from the CNS. Infected mice on control diet showed an increase in Evans blue staining and 125I and 51Cr retention in the CNS tissue itself. Feeding the diet containing BHA reduced these indices of increased blood-brain barrier permeability. In view of the potent radical scavenging activity of BHA in many other systems it is likely, but unproven, that this is its main role here. The protective effect of superoxide dismutase and catalase lends support to the idea that reactive oxygen species are involved in the pathology of experimental cerebral malaria. 相似文献
90.
Familial correlations from genes and shared environment for urine, plasma, and intraerythrocytic sodium 总被引:1,自引:0,他引:1
S C Hunt M M Dadone R R Williams L L Wu J B Smith H Kuida K O Ash 《American journal of medical genetics》1987,27(2):249-255
Spouse-spouse, sib-sib, and parent-offspring correlations were calculated for urinary, plasma, and intracellular sodium levels on over 1,900 persons aged 3-86 years in 98 Utah kindreds. For 36 hours prior to their clinic visit, 31% of the sample was salt-loaded with salt tablets, while the rest followed their normal diet. For those on their normal diet, urine creatine-, age-, and sex-adjusted urinary sodium excretion from a timed 12-hour overnight sample showed similar and significant correlations between spouses (r = .29), sibs less than 20 years old (r = .38), and parent-offspring pairs for offspring less than 20 years old (r = .29). This contrasted with the lower correlations between sibs 20 years of age and older (r = .10) and parent-offspring pairs for offspring 20 years of age and older (r = .13), presumed to live in different households. Adult plasma sodium sib-sib (r = .13) and parent-offspring (r = .15) correlations were similar to the urinary sodium correlations, while the spouse-spouse (r = .48), the sib-sib (r = .64), and the parent-offspring (r = .63) correlations for those presumed to live in the same household nearly doubled. Intracellular sodium correlations for the adult sibs (r = .32) and offspring (r = .36) were over twice as large as for urinary or plasma sodium, although the spouse-spouse correlation (r = .37) remained large also.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献