Cell-bound autologous immunoglobulin in erythrocyte subpopulations from patients with sickle cell disease

Previously, we have demonstrated a parallel between most-dense (bouyant density) sickle erythrocyte subpopulations and most-dense aged normal red cells in the organization of membrane components in the intact cell. The present study has addressed the possibility that a corresponding similarity may exist between most-dense sickled red cell subpopulations and aged normal erythrocytes in the development of membrane protein components that function as receptors for autologous immunoglobulin (Ig). Autologous IgG retained by density-fractionated erythrocytes has been estimated by a nonequilibrium 125I-protein A (Staphylococcus aureus) binding assay. Results show that most-dense sickle cell fractions contain more (2.7-fold and 1.8-fold, P less than .005) cell-bound IgG in comparison to younger sickle erythrocyte fractions sedimenting at low density. Parallel findings were obtained after similar analyses of normal (homozygous-A) erythrocyte fractions. Detection of the presence of specific IgG was also carried out by direct binding of fluorescein isothiocyanate-conjugated anti-human IgG to density-separated red cell fractions followed by analyses of the fluorescent cell populations by flow cytometry. Results showed significantly higher levels of IgG bound to most-dense (12.1% +/- 2.5% and 8.8% +/- 0.5%-) sickle red cell subpopulations (P less than .005) in comparison to younger sickle erythrocyte fractions sedimenting at low densities (3.8% +/- 0.32% and 4.7% +/- 1.6% IgG-positive red cell subpopulation). These results indicate that some of the same membrane changes that occur at about 120 days in normal red cells are also apparent in the chronologically younger (life span in vivo, ten to 40 days) sickle erythrocyte. The increased retention of IgG by most-dense irreversibly sickled cell-enriched fractions in comparison to least- dense reversibly sickled cells or pre-irreversibly sickled erythrocyte fractions, suggests that alterations in the topography of the sickle cell membrane during the transformation in vivo to the most-dense irreversibly sickled cell morphology may produce the unmasking of cryptic antigenic sites. In addition, these findings may indicate that opsonization of specific erythrocyte subpopulations may play a role in the pathophysiology of sickle cell disease.     

Identification of high-affinity (Kd 0.35 mumol/L) and low-affinity (Kd 7.9 mumol/L) platelet binding sites for ADP and competition by ADP analogues

Steady-state binding of ADP to blood platelets and isolated membranes has not previously been obtained because of complications arising from metabolism of the ligand and dilution due to its secretion from storage granules. In the present studies, competition binding isotherms (n = 9) using paraformaldehyde-fixed platelets showed that [2-3 H]ADP bound to two sites with a small amount (approximately 5% of total) of nonspecific binding: 410,000 +/- 40,000 sites of low affinity (Kd 7.9 +/- 2.0 mumol/L) and 160,000 +/- 20,000 sites of high affinity (Kd 0.35 +/- 0.04 mumol/L) corresponding to the ADP concentration required for activation in fresh platelets (0.1-0.5 mumol/L). All agonists and antagonists examined were able to compete with ADP at the high-affinity site. The strong platelet agonists 2-methylthio ADP and 2-(3- aminopropylthio)ADP competed with ADP at the high-affinity site with dissociation constant values of 7 mumol/L and 200 mumol/L, respectively. The partial agonist 2',3'-dialdehyde ADP and the weak agonist GDP also competed at the high-affinity site with Kd values of 5 mumol/L and 49 mumol/L, respectively. The sequence of binding affinities of other adenine nucleotides at the high-affinity site corresponded to their relative activities as known antagonists of platelet activation by ADP; namely, ADP(Kd 0.35 mumol/L) approximately equal to ATP (Kd 0.45 mumol/L) much greater than AMP (Kd 360 mumol/L). Adenosine and 2-chloroadenosine did not compete with ADP. ADP binding to the high-affinity site was inhibited by p-mercuribenzene sulfonate (Ki 250 mumol/L) but only very weakly by 5'-p- fluorosulfonylbenzoyladenosine (Ki 1 mmol/L). All the above nucleotides also competed with ADP at the low-affinity sites but, because of the high concentrations of competing nucleotide required, dissociation constants at this site were obtained only for ATP (21 mumol/L), 2-MeS ADP (200 mumol/L) and 2',3'-dialdehyde ADP (270 mumol/L). 8-Bromo ADP competed strongly with ADP at the high-affinity site (Kd 0.40 mumol/L) but weakly if at all at the low-affinity site. 8-Bromo ADP inhibited platelet activation induced by ADP (EC50 approximately 100 mumol/L) but not by collagen, thrombin, or ionophore A23187.(ABSTRACT TRUNCATED AT 400 WORDS)     

氯已定预处理对两步法自酸蚀粘接剂牙本质粘接界面稳定性的影响

目的：探讨氯已定预处理对两步法自酸蚀粘接剂的牙本质粘接界面稳定性的影响.方法：40颗离体人磨牙沿垂直于牙长轴的方向切割,暴露冠中部牙本质作为粘接面,牙本质试件随机分为两组,一组在粘接处理前涂布0.2％氯已定为实验组,一组无预处理为对照组,两组经两步法自酸蚀粘接剂SE Bond处理后,堆积复合树脂制备成粘接试件.每组随机抽取2个试件借助微拉曼光谱仪分析粘接剂的双键转化率,剩余的18个试件随机分为两个亚组,分别于即刻和冷热循环5000次后检测微拉伸粘接强度和界面的纳米渗漏情况.结果：0.2％氯已定预处理对SE Bond的树脂双键转化率无显著性影响（P＞0.05）.即刻测试时,对照组和实验组间的微拉伸粘接强度和纳米渗漏差异无统计学意义（PP ＞0.05）.冷热循环老化处理后,实验组的微拉伸粘接强度显著高于对照组,纳米渗漏程度显著低于对照组（P＜0.05）.结论：0.2％氯已定预处理不会干扰SE Bond的树脂聚合,且可提高其与牙本质粘接界面的稳定性.     

The First Decade of Laparoscopic Pancreaticoduodenectomy in the United States: Costs and Outcomes Using the Nationwide Inpatient Sample

Background

Minimally invasive pancreaticoduodenectomy (PD) remains an uncommon procedure, and the safety and efficacy remain uncertain beyond single institution case series. The aim of this study is to compare outcomes and costs between laparoscopic (LPD) and open PD (OPD) using a large population-based database.

Methods

The Nationwide Inpatient Sample database (a sample of approximately 20 % of all hospital discharges) was analyzed to identify patients who underwent PD from 2000 to 2010. Patient demographics, comorbidities, hospital characteristics, inflation-adjusted total charges, and complications were evaluated using univariate and multivariate logistic regression. Hospitals were categorized as high-volume hospitals (HVH) if more than 20 PD (open and laparoscopic) were performed annually, while those performing fewer than 20 PD were classified as low-volume hospitals.

Results

Of the 15,574 PD identified, 681 cases were LPD (4.4 %). Compared to OPD, patients who underwent LPD were slightly older (65 vs. 67 years; p = 0.001) and were more commonly treated at HVH (56.6 vs. 66.1 %; p < 0.001). Higher rates of complications were observed in OPD than LPD (46 vs. 39.4 %; p = 0.001), though mortality rates were comparable (5 vs. 3.8 %, p = 0.27). Inflation-adjusted median hospital charges were similar between OPD and LPD ($87,577 vs. $81,833, p = 0.199). However, hospital stay was slightly longer in the OPD group compared to LPD group (12 vs. 11 days, p < 0.001). Stratifying outcomes by hospital volume, LPD at HVH resulted in shorter hospital stays (9 vs. 13 days, p < 0.001), which translated into significantly lower median hospital charges ($76,572 vs. $106,367, p < 0.001).

Conclusions

Contrary to fears regarding the potential for compromised outcomes early in the learning curve, LPD morbidity in its first decade is modestly reduced, while hospital costs are comparable to OPD. In high-volume pancreatic hospitals, LPD is associated with a reduction in length of stay and hospital costs.

     

Modern lineages of Mycobacterium tuberculosis in Addis Ababa,Ethiopia: implications for the tuberculosis control programe

Background

The genotyping of Mycobacterium tuberculosis strains is important to have unique insights into the dissemination dynamics and evolutionary genetics of this pathogen and for TB control as it allows the detection of suspected outbreaks and the tracing of transmission chains.

Objective

To characterize M. tuberculois isolates collected from newly diagnosed pulmonary TB patients in Addis Ababa

Methods

One hundred and ninety two sputum samples were cultured on Löwenstein-Jensen (LJ) slants and isolates were heat killed for molecular genotyping. The isolates were characterized using spoligotyping and were compared with the International SpoIDB4 database.

Result

T genotype constitutes the most predominant in our study (95, 49.5%) followed by the CAS genotype (42, 21.9%). Other genotypes found were Haarlem (H) (24, 12.5%), the LAM (3, 1.5%), the Beijing genotype (1, 0.5%); four (2.1%) isolates were designated as Unknown.

Conclusion

All the isolates belong to the modern lineage and there is high clustering in the genotype of isolates which indicated the presence of recent TB transmission. Therefore, the Tuberculosis Control Programme needs to do more in advocating and strengthening the health system for early detection and treatment of active TB cases as delay in treatment is the key factor in disease transmission.     

Liver remnant hypertrophy induction – How often do we really use it in the time of computer assisted surgery?

PurposeTo evaluate the significance of the hypertrophy concept in patients requiring extended liver resections for colorectal metastasis in the time of computer assisted surgery.MethodsRetrospective analysis of patient collective undergoing major liver surgery. 2D CT, 3D CAS with Fraunhofer MeVis Sofware. Portal vein embolisation (PVE) with the Amplazer Plug, portal vein ligation (PVL) as 1. Stage operative procedure.Results2D CT data identified 29 patients out of 319 (2002-2009) to be at risk for liver failure after resection. After 3D CAS analysis and virtual operation planning, only 7/29 were at true risk and were submitted to portal vein occlusion (PVO). Another 5 patients were submitted to the hypertrophy concept for intraoperative finding of insufficient parenchyma quality. In total, 12 patients underwent PVO (6 PVE/6 PVL). 9/12 patients went to stage 2 and were successfully operated. There was no difference in future remnant liver volume (FRLV) gain or waiting time to step 2 between the groups, though survival was better in the PVE group.ConclusionPVO is an effective approach if the patient's future remnant liver (FRL) is too small on 2D CT volumetry. 3D CAS has great impact on the analysis of FRL capacity and in augmenting resectability - in our experience only patients with insufficient FRLV on the virtual resection plan have to take the risk of PVO to maintain the chance of liver resection.