选择性头部降温对胎羊缺血性脑损伤纹状体神经元凋亡和星形胶质细胞增殖的影响

目的研究选择性头部降温对缺血性脑损伤胎羊纹状体神经元凋亡和星形胶质细胞增殖的影响。方法胎羊于妊娠117~124d时通过双侧颈动脉阻塞30min造成双侧脑缺血损伤,损伤后将胎羊随机分为:损伤组(n=10)、2h低温组(损伤后2h开始亚低温治疗,n=7)和6h低温组(损伤后6h开始亚低温治疗,n=8),另设正常对照组(n=5)。通过冷循环水进行选择性头部降温,取脑组织用免疫组化法检测胎羊纹状体caspase-3(半胱天冬氨酸酶-3),GFAP(胶质纤维酸性蛋白)和PCNA(增殖细胞核抗原)的表达。结果①纹状体神经元凋亡:正常对照组中,caspase-3表达极少(11.00±13.77),损伤组caspase-3免疫阳性细胞为177.70±48.69,明显增加(P=0.000),损伤后2h治疗组(54.14±39.44,P=0.000)和损伤后6h治疗组(122.43±52.36,P=0.017)均能减少caspase-3免疫阳性细胞。②纹状体星形胶质细胞增殖:与正常对照组(163.40±21.98)相比,缺血性脑损伤组的GFAP免疫阳性细胞明显增多(433.25±66.69,P=0.000),损伤后2h开始亚低温治疗(219.50±35.31,P=0.000)和损伤后6h开始亚低温治疗(272.50±86.20,P=0.000)均能减少GFAP免疫阳性细胞。③纹状体PCNA阳性细胞的表达:在正常对照组中,PCNA免疫阳性细胞较少,为153.40±12.46,缺血性脑损伤组的PCNA免疫阳性细胞明显增多(353.70±45.60,P=0.000),损伤后2h开始亚低温治疗(187.14±26.26,P=0.000)和损伤后6h开始亚低温治疗(230.25±67.46,P=0.000)均能减少PCNA免疫阳性细胞。结论亚低温可以抑制纹状体神经元的凋亡和星形胶质细胞的增殖,该作用可能为选择性头部降温的脑保护作用机制之一。     

Minactivin expression in human monocyte and macrophage populations

Adherent monolayer cultures of human blood monocytes, peritoneal macrophages, bone marrow macrophages, and colonic mucosa macrophages were examined for their ability to produce and secrete minactivin, a specific inactivator of urokinase-type plasminogen activator. All except colonic mucosa macrophages produced and secreted appreciable amounts of minactivin, but only blood monocytes were stimulated by muramyl dipeptide (adjuvant peptide) to increase production. The minactivin from each of these populations could be shown to preferentially inhibit urokinase-type plasminogen activator and not trypsin, plasmin, or "tissue"-type plasminogen activator (HPA66). A plasminogen-activating enzyme present in monocyte cultures appeared unaffected by the presence of minactivin and could be shown to be regulated independently by dexamethasone.     

Current thinking on chronic renal allograft rejection: issues, concerns, and recommendations from a 1997 roundtable discussion

Chronic rejection accounts for most renal allograft losses after the first year posttransplantation. On March 24 and 25, 1997, a roundtable of five transplant surgeons, two nephrologists, and one pathologist assembled in Dallas, Texas, to review critical issues surrounding chronic renal allograft rejection. This article summarizes the presentations and relevant discussions of this meeting regarding the cause of chronic rejection, clinical diagnoses, risk factors, future prospects for intervention strategies, and general recommendations for the transplant community. Growing evidence indicates that chronic rejection is the aggregate sum of irreversible immunologic and nonimmunologic injuries to the renal graft over time. A history of acute rejection episodes and inadequate immunosuppression, likely attributable to inconsistent cyclosporine exposure or poor patient compliance, are among the most recognizable immunologic risk factors for chronic rejection. Donor organ quality, delayed graft function, and other donor and recipient variables leading to reduced nephron mass are nonimmunologic factors that contribute to the progressive deterioration of renal graft function. Clinical management of renal transplant recipients should incorporate both immunologic- and nonimmunologic-based intervention strategies aimed at minimizing risk factors to thwart the progression of chronic rejection and improve long-term allograft and patient survival.     

Are vitamin B12 and folate deficiency clinically important after roux-en-Y gastric bypass?

Although iron, vltamm B₁₂, and folate deficiency have been well documented after gastric bypass operations performed for morbid obesity, there is surprisingly little information on either the natural course or the treatment of these deficiencies in Roux-en-Y gastric bypass (RYGB) patients Durmg a l0-year period, a complete blood count and serum levels of iron, total iron-binding capacity, vltamin B₁₂, and folate were obtained in 348 patients preoperatively and postoperatively at 6-month intervals for the first 2 years, then annually thereafter The principal objectives of this study were to determine how readily patients who developed metabolic deficiencies after Roux-en-Y gastric bypass responded to postoperative supplements of the deficient micronutrient and to learn whether the risk of developmg these deficiencies decreases over time Hemoglobin and hematocrit levels were slgnificantly decreased at all postoperative intervals in comparison to preoperative values Moreover, at each successive interval through 5 years, hemoglobin and hematocrit were decreased signifiantly compared to the preceding interval Folate levels were significantly increased compared to preoperative levels at all time intervals Iron and vltamin B₁₂ levels were lower than preoperative measurements and remained relatively stable postoperatively Half of the low hemoglobin levels were not associated with iron deficiency Taking multivltamin supplements resulted in a lower incidence of folate deficiency but did not prevent iron or vitamin B₁₂ deficiency Oral supplementation of iron and vitamin B₁₂ corrected defiaencies in 43% and 81% of cases, respectively Folate deficiency was almost always corrected with multivitamins alone No patient had symptoms that could be attributed to either vitamin B₁₂ or folate deficiency Conversely, many patients had symptoms of iron deficiency and anenua Lack of symptoms of vitamin B₁₂ and folate deficiency suggests that these deficiencies are not clinically important after RYGB Conversely, iron deficiency and anemia are potentially serious problems after RYGB, particularly in younger women Hence we recommend prophylactic oral iron supplements to premenopausal women who undergo RYGB