CR、DR的工作原理及选择应用

数字化是当前医学影像技术发展的主流,合理地选择CR、DR符合医院的发展要求,对CR、DR的工作原理、配置构成及基本技术参数进行分析,对目前医疗单位的放射设备的选择采购有一定的参考意义。     

Handling of asymmetrical dimethylarginine and symmetrical dimethylarginine by the rat kidney under basal conditions and during endotoxaemia.

BACKGROUND: Asymmetrical dimethylarginine (ADMA) is capable of inhibiting nitric oxide synthase enzymes, whereas symmetrical dimethylarginine (SDMA) competes with arginine transport. The potential role of inflammation in the metabolism of ADMA has been elucidated in an in vitro model using tumour necrosis factor-alpha, resulting in a decreased activity of the ADMA-degrading enzyme dimethylarginine dimethylaminohydrolase (DDAH). The kidney probably plays a crucial role in the metabolism of ADMA by both urinary excretion and degradation by DDAH. We aimed to further elucidate the role of the kidney in a rat model under basal conditions and during endotoxaemia. METHODS: Twenty-five male Wistar rats weighing 275-300 g were used for this study. The combination of arteriovenous concentration differences and kidney blood flow allowed calculation of net organ fluxes. Blood flow was measured using radiolabelled microspheres according to the reference sample method. Concentrations of ADMA, SDMA and arginine were measured by high-performance liquid chromatography. RESULTS: The kidney showed net uptake of both ADMA and SDMA and fractional extraction rates were 35% and 31%, respectively. Endotoxaemia resulted in a lower systemic ADMA concentration (P = 0.01), which was not explained by an increased net renal uptake. Systemic SDMA concentrations increased during endotoxaemia (P = 0.007), which was accompanied by increased creatinine concentrations. CONCLUSIONS: The rat kidney plays a crucial role in the regulation of concentrations of dimethylarginines, as both ADMA and SDMA were eliminated from the systemic circulation in substantial amounts. Furthermore, evidence for the role of endotoxaemia in the metabolism of dimethylarginines was obtained as plasma levels of ADMA were significantly lower in endotoxaemic rats.     

HLA-DR, DQ genotypes of celiac disease patients and healthy subjects from the West of Ireland

Celiac disease (CD) has one of the strongest class II HLA associations of any human illness. We used DNA-RFLP typing to study the class II HLA genotypes of celiac disease patients from the West of Ireland, the geographic area with the highest rate of celiac disease in the world. We confirmed the high frequency of HLA-DR3 in this population, and we were also able to demonstrate the additional risk of developing celiac disease imparted by HLA-DR7. This was done by clearly distinguishing DR7, DQ2 haplotypes from DR7, DQ9 haplotypes, and by "subtraction analysis" of haplotype frequencies. As reported in other populations, most of the patients without DR3 were heterozygous for DR7 and DR11 or 12 (DR5), or had DR4. We used PCR-RFLP and direct sequencing of amplified DNA to examine HLA-DR4 subtypes. The frequency of HLA-DR4 was markedly decreased in patients compared with controls (p=0.000001) and there was a significant alteration of DR4 subtypes of the patients compared with controls (p=0.0227). Moreover, all of the CD patients (5 of 5) with DR4 had a haplotype associated with the DQB1*0302 allele compared with only 11 of 23 control subjects with DR4. Our results in this population with exceptionally high risk of CD strongly support the DQ heterodimer hypothesis and suggest that the recently described sequence difference between the DQB1*02 alleles of DR3 and DR7 may contribute to a synergistic increased risk when these haplotypes are inherited together. In addition, our findings suggest a role for HLA-DQ in DR4-associated CD.     

再生障碍性贫血患者细胞因子水平观察

为进一步探讨细胞免疫对ＡＡ发病的影响，阐明细胞因子在ＡＡ患者中变化的基础与临床意义，采用酶联免疫试剂盒ＥＬＩＳＡ法对３８例ＡＡ患者及２０例正常人外周血单个核细胞（ＰＢＭＮＣ）培养上清诱生Ｇ－ＣＳＦ，ＩＬ－６，ＴＮＦα，ＩＦＮα及ＩＬ－８水平进行测定，同时采用改良ＡＰＡＡＰ法观察外周血Ｔ细胞亚群及ＨＬＡ－ＤＲ抗原表达，结果ＡＡ患者ＰＢＭＮＣ培养上清中Ｇ－ＣＳＦ阳性率减低，ＩＬ－６，ＴＮＦαＩＦＮα及     

Does cyclosporine influence the results of cadaver retransplantation?

The results of cadaveric retransplantation in 55 recipients immunosuppressed with cyclosporine and prednisone were compared to 156 recipients of primary renal allografts. By 3 yr posttransplant, there is no significant difference in patient survival, but the yearly graft survival for primary (79%, 72%, 72%) as compared to retransplant (69%, 58%, 58%) recipients was significantly (p less than 0.05) better. There was no significant difference in rejection episodes or mean +/- SD serum creatinine (mg/dl) at 2 yr between primary (32%, 2.14 +/- 1.1) and retransplant (33%, 2.08 +/- 1.4) patients, respectively. Donor source, third kidneys, human leukocyte antigen AB and Dr matching, percent reactive antibody levels, and cause of first graft loss do not have significant impact on cyclosporine-treated retransplant outcome. However, retransplant patients who have lost a previous graft in less than 3 months continue to be at high risk for subsequent early graft loss. These results suggest that the combination of cyclosporine and prednisone is the preferred regimen for cadaveric retransplantation.     

Induction of erythroid differentiation in K562 cells and natural killer cell-mediated lysis: distinct effects at the level of recognition and lysis in relation to target cell proliferation

The erythroleukemic K562 cell line was induced to erythroid differentiation by a variety of agents, including hemin, bleomycin, and cytosine arabinoside. The sensitivity of induced cells to binding and lysis by non-sensitized peripheral blood mononuclear cells (MNC) in agarose was studied in relation to the target cell division rate. Differentiated K562 cells formed a lower proportion of conjugates with MNC, when compared with non-induced controls. The reduction correlated significantly with the level of differentiation, irrespective of the inducer and the proliferative status. The differentiation-induced alterations of lysis, however, were strongly influenced by the modification of target cell growth rate which was caused by the differentiating agent. These data suggest that target cell differentiation has distinct effects upon the steps of recognition and lysis by natural killer cells.     

Anonymous or identity-registered sperm donors? A study of Dutch recipients' choices

BACKGROUND: The aim of the present study was to gain insight into parents' own donor preferences within a system offering the choice between an anonymous and identity-registered donor. A comparison was made between recipients choosing for an anonymous donor (AD choosers) and those choosing for an identifiable donor (ID choosers) with regard to their sexual orientation, demographic characteristics, disclosure issues and infertility distress. METHODS: Data from 105 couples (61% heterosexual, 39% lesbian) were registered on a standardized form during implication counselling sessions previous to treatment. RESULTS: Sixty-three per cent of the heterosexual couples and 98% of the lesbian couples had chosen an ID donor. Major differences between ID and AD choosers were identified. Among the ID choosers secrecy towards the child was no option, whereas 83% of the AD choosers did not intend to inform their child. Compared with heterosexual ID choosers, AD choosers were more distressed about their infertility and had a lower educational level. CONCLUSION: Legislation imposing ID donors appears to be acceptable for the majority of this study population. For a vulnerable group of heterosexual couples, who remained secretive about the use of a donor, adaptation to the new system is not self-evident.     

High rate of false positives in blood donor screening for antibodies to hepatitis C virus

Summary Anti-hepatitis C virus antibody screening of blood donors in different countries revealed prevalences ranging from 0,4–1,4%. These results were obtained with an enzyme immunoassay based on a recombinant hepatitis C virus antigen. We applied a specific inhibition assay (neutralization assay) and a recombinant immunoblot assay to determine the specificity of positive reactions in the enzyme immunoassay.Of 2836 blood donor sera tested, 10 (0,35%) were reactive in the enzyme immunoassay, however, only 3 sera (0,1%) proved to be specifically anti-HCV positive in the inhibition assay. The recombinant immunoblot assay gave similar results. The prevalence of anti-hepatitis C virus antibodies among blood donors has been overestimated in recent publications. Furthermore the high rate of false positives in the enzyme immunoassay may explain reports claiming that only a minor part of EIA positive blood units transmitted the hepatitis C virus to recipients.The inhibition assay was also applied to sera of haemophiliacs and of patients with hepatopathy which had reacted positively in the anti-hepatitis C virus antibody enzyme immunoassay. The antihepatitis C virus specificity was confirmed for all sera from the haemophiliacs group (100%) and for 77% of the hepatopathy patients group. Thus, the anti-hepatitis C virus enzyme immunoassay has a high predictive value when it is used to screen groups with high risks of parenteral hepatitis C virus infection, however, its predictive value is very low when it is used for blood donor screening.Abbreviations EIA enzyme immunoassay - HCV hepatitis C virus - RIBA recombinant immunoblot assay - SOD superoxide dismutase     

Psychological screening and the success of donor insemination

In a previous case series, a psychologist‘s rating ofcouples’ emotional adjustment and readiness for donorinsemination was predictive of pregnancy rates. We attemptedto replicate this finding with an extended series of 120 consecutivecouples in which each spouse filled out questionnaires whenevaluated for donor insemination. The Stress and InfertilityQuestionnaire measured specific attitudes and anxieties aboutdonor insemination. The Brief Symptom Inventory assessed psychologicaldistress. The Dyadic Adjustment Scale measured marital happiness.A psychologist used these questionnaires to rate the couple‘soverall adjustment in regard to donor insemination. Those couplesrated as distressed had a session of psychological counselling.Outcome was reviewed at a mean of 20 months after evaluation,with categories of pregnancy, continuing donor insemination,failure to begin the programme, or dropped out. For the 120couples overall, psychological factors did not predict pregnancyoutcome. Younger age of the wife did predict higher pregnancyrates