Decrease in subunit aggregation of phosphoribosylpyrophosphate synthetase: a mechanism for decreased nucleotide concentrations in pyruvate kinase-deficient human erythrocytes

Pyruvate kinase (PK)-deficient RBCs have several unexplained metabolic abnormalities, such as decreased concentrations of total adenine nucleotides (AMP, ADP, and ATP) and total (oxidized and reduced) nicotinamide adenine dinucleotide (NAD). Because 5-phosphoribosyl-1- pyrophosphate (PRPP) is an intermediate in the synthesis of adenine nucleotides and NAD, we investigated PRPP synthetase (PRPPS), the enzyme responsible for PRPP synthesis. This enzyme is regulated, in part, by changes in its state of subunit aggregation. The proportion of aggregated PRPPS can be altered in vitro by ATP and 2,3- diphosphoglycerate (DPG). Because PK-deficient RBCs have decreased ATP and increased DPG concentrations, we examined the state of subunit aggregation of PRPPS in RBCs from normal and PK-deficient subjects, using gel permeation chromatography. Young normal RBCs have more aggregated PRPPS than do older RBCs. In contrast, due to their decreased ATP and increased DPG concentrations, PK-deficient RBCs contain less aggregated PRPPS than do RBCs of comparable age without PK deficiency. These data suggest that PRPPS should be less active in vivo in PK-deficient RBCs. This may play a key role in mediating the decreases in total adenine nucleotide and total NAD concentrations in these RBCs.     

Adhesion of sickle neutrophils and erythrocytes to fibronectin

The pathophysiology of vaso-occlusive crisis in sickle cell disease involves interactions among blood cells, plasma proteins, and vessel wall components. The initial goal of this work was to quantify the adhesion of sickle red blood cells (RBCs) to fibronectin immobilized on glass under both static and dynamic shear stress conditions. High-power microscopic inspection of static assay plates showed striking numbers of adherent neutrophils as well as RBCs. Sickle neutrophils and RBCs were significantly more adherent to fibronectin than the corresponding normal cells in static adhesion assays. Adhesion of both sickle neutrophils and sickle RBCs in dynamic adhesion assays was promoted by a period of static incubation preceding initiation of shear stress conditions. Adherent neutrophils remained attached at shear stresses up to 51 dyne/cm2; most adherent RBCs were attached at shear stresses up to 13 dyne/cm2, but detached at a shear stress of 20 dyne/cm2. Sickle neutrophil adhesion was enhanced significantly by autologous plasma. Elevated levels of plasma interleukin-6 (IL-6; but not IL-1 or IL-8) were found in 6 of 9 sickle cell disease samples examined, and elevated levels of tumor necrosis factor were found in 2 of 9 samples. Plasma IL- 6 levels correlated positively with both the number of sickle neutrophils adherent to fibronectin and the ability of sickle plasma to enhance adhesion of normal neutrophils to fibronectin. These data suggest possible roles for neutrophil activation and for fibronectin in mediating sickle neutrophil and RBC adhesion.     

人体液中喷布洛尔及其代谢物的GC/MS分析

用气相色谱一质谱联用(GC-MSD)系统分析方法检出了人尿中喷布洛尔的6个羟化代谢物,用Scp-Pak柱提取的方法检出了人血浆中的原型药物。并从分子结构上对此药物的代谢途径进行了研究。尿中提取和血中提取的回收率分别为90.83.%和85.88%,Gc-MSD的检测限为5pg。本方法适用于运动员兴奋剂的系统检查。     

Refrigerated storage of lyophilized and rehydrated, lyophilized human red cells

Human red cells (RBCs) were collected in CPDA-1 and then freeze-dried in lyoprotective solution. The lyophilized RBCs were then stored at -20 degrees C for 7 days. At the end of the storage period, the lyophilized RBCs were rehydrated and washed in dextrose saline. The washed, reconstituted, lyophilized RBCs were resuspended in final wash solutions of ADSOL, CPDA-1, or a special additive solution containing glucose, citrate, phosphate, adenine, and mannitol, and then they were stored at 4 degrees C for an additional 7 days. The main purpose of this study was to determine whether human RBCs can be lyophilized in such a manner that normal metabolic, rheologic, and cellular properties are maintained during rehydration and subsequent storage in standard blood bank preservative solutions. Our results show that reconstituted, lyophilized RBCs maintained levels of ATP, 2,3 DPG, lactate, and cellular properties that are equal to or better than those in control nonlyophilized RBCs stored for a comparable period in CPDA-1. Reconstituted, lyophilized RBCs stored at 4 degrees C after rehydration also show better maintenance of ATP, 2,3 DPG, and lactate than do control RBCs stored in the same preservative solutions for comparable periods.     

Bile duct stones: percutaneous transhepatic removal

Percutaneous transhepatic intervention for transduodenal removal of biliary stones was performed 38 times in 34 patients with obstructive jaundice, biliary colic, and cholangitis. The technique entailed the percutaneous transhepatic placement of a modified Dormia basket in the common duct with the flexible tip in the duodenum. The stones were passed into the duodenum and were crushed, or were crushed in the common duct and passed as fragments into the duodenum. In addition to the snare procedure, monooctanoin was used 18 times to dissolve remaining fragments of stone and sludge that could not be snared and passed into the duodenum. The average time for completion of the procedure was 10 days. There were no deaths from the procedure. The complication rate was 21%--probably no greater than would occur with surgery in a similar patient population. The procedure can be performed when endoscopic retrograde cholangiopancreatography and sphincterotomy with stone removal is technically impossible or refused, and in patients who have previously undergone choledochojejunostomy.     

Scientific abstracts at the society for adolescent medicine meetings:: A 3-decade comparison

Purpose: The purpose of this study was to review abstracts accepted for presentation at the annual national meeting of the Society for Adolescent Medicine (SAM) over the past 3 decades for subject content and research design.

Methods: Retrospective review was conducted of research abstracts for 3 years, selected at random, for the 1990s and then matched at 10-year intervals for the previous 2 decades. The major categories for subject content were: medical, psychosocial, health services, and miscellaneous; for research design categories were: retrospective, observational, experimental, and miscellaneous. Subsequent publication was also assessed.

Results: The most notable change over the 3 decades in subject content was a shift from medical topics (58% to 19%) to psychosocial topics [20% to 52% (p < .001)] of abstracts, the latter largely accounted for by increases in topics pertaining to high-risk behaviors. There was a substantial decrease in abstracts concerning medical aspects of chronic illness (p < .001), well-adolescent care, growth and development, and psychosocial aspects of chronic illness (p < .02). Regarding research design, the proportion of retrospective studies decreased over the 3 decades (p < .02); the most prevalent design was observational, with an increase in studies using established databases (p < .02). Less than 15% represented an experimental design. Studies using qualitative analysis appeared for the first time in the 1990s. The percentage of presentations which eventuated in published reports increased from 35% to 63% over the 3 decades (p < .02).

Conclusion: A significant shift occurred in subject con- tent of scientific abstracts from a medical to a psychosocial emphasis. The proportion of retrospective designs decreased, and qualitative analyses emerged. The likelihood of later publication of the studies increased.