卡尔曼滤波分光光度法测定复方维生素B片四组分含量

复方维生素B片中的主要成分维生素B₁,B₂,B₆及烟酰胺各具有一定的不稳定性,且配方比例差较大,因而给多组分同时测定带来一定的困难。本文研究了应用卡尔曼滤波分光光度法同时测定复方维生素B片中的主要成分的可行性,并在处理由于分子间的相互作用引起的吸收度偏离Beer-Lambert定律的现象作了探索,得到较满意的结果。维生素B₁,B₂,B₆及烟酰胺的回收率分别是:100.2±0.90%(CV),100.3±1.7%(CV),101.1±3.3%(CV),99.90±0.65%(CV)。较已有的报道结果均好,表明方法可行。     

Preparation of packed red cells suitable for intravascular transfusion in utero

Intra-cardiac transfusion in utero is a recent development in the treatment of erythroblastosis foetalis. As with intra-umbilical cord transfusion, the procedure has been described as having a high risk of complication characterized by bradycardia and cardiac-arrest. Intra-coronary hyperkalemia was suspected as being a major contributing factor towards the complications experienced, particularly by the intra-cardiac delivery. The procedure is warranted, however, in cases where intra-umbilical cord transfusion is not possible. Therefore, studies comparing various methods of preparing packed cells for intravascular transfusion were initiated. The plasma potassium levels of gravity sedimented packed cells and saline washed red cells resuspended in either Ringer's lactate, pooled donor plasma or saline were measured. Products of saline washed/resuspended packed red cells transfused within 2 hours of preparation were found to have low potassium levels while exposing the fetus to minimal risk of transfusion transmitted infection and were therefore selected to be the most suitable product. Using this product, a significant decrease in the incidence of severe bradycardia resulting in cardiac-arrest, following intravascular transfusion (32 procedures) was observed.     

Life-threatening, antiglobulin test-negative, acute autoimmune hemolytic anemia due to a non-complement-activating IgG1 kappa cold antibody with Pra specificity

A 21-year-old man with fulminant cold autoantibody hemolytic anemia (CAHA) was hospitalized with hemoglobinemia, hemoglobinuria, hemoglobin concentration of 3.3 gm per dL, a negative direct antiglobulin test (DAT) with polyspecific and anti-C3d reagents, a negative Donath-Landsteiner test, and a cold agglutinin titer of 80. He failed to respond to corticosteroids, multiple plasma exchanges, and cyclophosphamide; he required 54 transfusions in 10 days to maintain a hemoglobin concentration of 6.0 to 10.0 g per dL. He improved dramatically after a splenectomy was performed. The wide-thermal-amplitude cold agglutinin proved to be an IgG1 kappa antibody with Pra specificity. The patient's serum exhibited normal complement activation. When the DAT was carried out at 0 to 4 degrees C, the result was strongly positive for IgG; the indirect antiglobulin test at 0 to 4 degrees C was positive with the patient's serum diluted 1 in 640. Within 6 months, he was in complete remission and receiving no therapy. As compared with eight patients with CAHA that was exclusively IgG-mediated, this patient is remarkable for his requirement for many transfusions and for DATs that were consistently negative for C3d.     

精氨酸对恶性肿瘤及宿主蛋白质代谢的影响

Ｓｐｒａｇｕｅ－Ｄａｗｌｅｙ大鼠经皮下接种Ｗａｌｋｅｒ２５６癌肉瘤细胞后以１％精氨酸溶液代替饮用水饲喂大鼠分别进行肿瘤、肝脏、肌肉和整体的蛋白质代谢分析。精氨酸治疗后肿瘤体积和重量显著减少，肿瘤蛋白质合成率、分段生长率均显著减少，而肿瘤蛋白质分段降解率则无明显改变。精氨酸也影响宿主蛋白质代谢。肝脏蛋白质合成率以及整体蛋白质分段合成率也明显减少，但肌肉蛋白质合成则无明显改变。结果表明，补充精氨酸可减少肿瘤蛋白质的合成和抑制肿瘤的生长，同时也使宿主蛋白质代谢发生改变。     

The effects of 50 Hz magnetic fields on opioid peptide mediated inhibition of guinea pig ileum

Strips of guinea pig ileum were mounted in a tissue bath within the poles of a magnet capable of generating a 50 Hz field of intensity up to 1 mT. In the absence of magnetic field the preparations were stimulated transmurally at tetanic frequency (10 Hz). The post-tetanic inhibition was antagonised by naloxone. When this inhibitory phase was repeated in the presence of a magnetic field of 0.5 mT there was a small but significant increase in the inhibition when compared with paired controls.     

Down syndrome: sonographic sign for diagnosis in the second-trimester fetus

In an expanded series of patients a sonographic sign was found to correlate well with the diagnosis of Down syndrome in second-trimester fetuses. The sign is characterized by soft-tissue thickening at the back of the fetal occiput. Sonographic evaluation for this sign was done in 2,121 consecutive fetuses between 15 and 20 gestational weeks of age at the time of genetic amniocentesis. The mothers were 35 years old or older or were otherwise at increased risk for fetal trisomies. Ten fetuses had Down syndrome by karyotype and four of these (40%) had thickened soft tissues (6 mm or more) at the back of the neck or occiput. When these data are combined with those in series previously reported by the authors, similarly collected consecutively, total second-trimester fetuses studied equals 3,825. Nine of the 21 (42%) Down syndrome fetuses by karyotype from this 3,825 had the positive sonographic sign described.     

Dramatically different phenotypes in mouse models of human Tay-Sachs and Sandhoff diseases

We have generated mouse models of human Tay-Sachs and Sandhoff diseases by targeted disruption of the Hexa (alpha subunit) or Hexb (beta subunit) genes, respectively, encoding lysosomal beta-hexosaminidase A (structure, alpha) and B (structure, beta beta). Both mutant mice accumulate GM2 ganglioside in brain, much more so in Hexb -/- mice, and the latter also accumulate glycolipid GA2. Hexa -/- mice suffer no obvious behavioral or neurological deficit, while Hexb -/- mice develop a fatal neurodegenerative disease, with spasticity, muscle weakness, rigidity, tremor and ataxia. The Hexb -/- but not the Hexa -/- mice have massive depletion of spinal cord axons as an apparent consequence of neuronal storage of GM2. We propose that Hexa -/- mice escape disease through partial catabolism of accumulated GM2 via GA2 (asialo- GM2) through the combined action of sialidase and beta-hexosaminidase B.      

The structural basis for complement receptor type 2 (CR2, CD21)-mediated alternative pathway activation of complement: studies with CR2 deletion mutants and vaccinia virus complement-control protein-CR2 chimeras

The role of complement receptor 2 (CR2) short consensus repeats (SCR) in binding of hydrolyzed C3 (iC3) to form an alternative pathway (AP) convertase, and promoting C3 fragment deposition following AP activation, was examined. We used (1) K562 cells transfected with CR2 constructs, where the C3d-binding site of CR2 (SCR1+2) was replaced with the four-SCR vaccinia virus complement control protein (VCP), or truncation mutants thereof, and (2) COS cells transfected with wild-type (wt) CR2, or deletion mutants thereof. AP activation required iC3 binding in both systems. Thus, the VCP-CR2 chimera had an iC3 binding efficiency of 11.4 %, compared to wtCR2, and a relative AP activity of 5.5 %, the truncation mutants being inactive. Of the CR2 mutants, only EK (DeltaSCR10 - 11) had AP activity similar to wtCR2. NN (DeltaSCR6 - 8) and NOP (DeltaSCR6-mid14) had reduced AP activity, but near normal iC3 binding. XB (DeltaSCR3 - 6) and PP (DeltaSCR3-mid14) were inactive in both assays. We conclude that, whilst iC3 binding to CR2 via SCR1 - 4 is essential for AP activation, the efficiency of C3 deposition also depends on the midportion of CR2.     

State-dependent fear extinction with two benzodiazepine tranquilizers

Four experiments with rats were run to investigate whether fear extinction conducted under the influence of a benzodiazepine transfers to the undrugged state. Fear was conditioned by pairing an experimental chamber with footshock and was assessed by observing freezing, a characteristic response of the rat to stimuli associated with shock. In Experiment 1, extinction of the chamber cues under chlordiazepoxide (librium) or diazepam (valium) was compared with extinction under a placebo; both drugs interfered with extinction in a dose-dependent manner as indicated by freezing during an undrugged test. Further results with chlordiazepoxide suggested that the effect depended on the drug's specific combination with extinction and that it occurred even though the extinction procedure otherwise eliminated fear completely (Experiment 2). Repeated preexposure to the drug, and the development of partial tolerance to its sedative effects, did not weaken the interference effect (Experiment 3). Other evidence suggested that the drug signaled or retrieved extinction instead of disrupting learning or consolidation (Experiment 4). The results are consistent with research suggesting that extinguished fear can be "renewed" if the exteroceptive contextual stimuli are changed after extinction. Extinction combined with either unique exteroceptive or interoceptive cues may be specific to its context.