Triggering for Submaximal Exercise Level in Gastric Exercise Tonometry: Serial Lactate,Heart Rate,or Respiratory Quotient?

Gastric exercise tonometry is a functional diagnostic test in chronic gastrointestinal ischemia. As maximal exercise can cause false-positive tests, exercise buildup should be controlled to remain submaximal. We evaluated three parameters for monitoring and adjusting exercise levels (heart rate [HR], respiratory quotient [RQ], and serial lactate measurements) in 178 tests in both healthy volunteers and patients suspected of gastrointestinal ischemia. Exercise levels above submaximal occurred in 20% of HR-, 2% of RQ-, and 5% of lactate-monitored tests (P<0.05 for HR vs. RQ and lactate). Low levels were seen in 5% of HR-, 10% of RQ-, and 41% of lactate-monitored tests (P<0.01 for lactate vs. HR and RQ). High levels resulted in 43% false-positive tonometry results compared to 19% of all tests (P<0.001); low levels did not result in more false negatives (5% vs. 6%). Although RQ monitoring yielded the greatest proportion of optimal exercise tests, serial lactate monitoring is our method of choice, combining optimal diagnostic accuracy, low cost, and simplicity.     

Non-occlusive mesenteric ischaemia: a common disorder in gastroenterology and intensive care

Non-occlusive mesenteric ischaemia is characterized by gastrointestinal ischaemia with normal vessels. In gastroenterology it is recognized as rare disease occasionally causing acute bowel infarction or ischaemic colitis. From intensive care literature this disorder is recognized as an early phenomenon during circulatory stress. This early mucosal ischaemia then leads to increased permeability, bacterial translocation, and further mucosal hypoperfusion. The damage is produced mainly during reperfusion following ischaemia with fresh inflow of oxygen and outflow of waste products into the systemic circulation.The mechanisms underlying non-occlusive mesenteric ischaemia include macrovascular vasoconstriction, hypoperfusion of the tips of the villi and shunting. It is very common in critically ill and perioperative patients, but also occurs in pancreatitis, renal failure and sepsis.Treatment options include aggressive fluid resuscitation and careful choice of vasoactive drugs. Control of reperfusion damage and new endothelin-antagonists are potentially useful new treatment options.     

Vegetable oil based versus wood based stanol ester mixtures: effects on serum lipids and hemostatic factors in non-hypercholesterolemic subjects

A pine wood based stanol ester mixture-composed of sitostanol (92%) and campestanol (8%) effectively lowers cholesterol absorption and consequently LDL-cholesterol concentrations. It has been postulated that the less absorbable plant sterols reduce cholesterol absorption more effectively. As sitostanol is absorbed less than campestanol, we decided to examine if a vegetable oil based stanol ester mixture with 68% sitostanol and 32% campestanol is less effective than the wood based stanol ester mixture. For this, 112 non-hypercholesterolemic men and women consumed for 4 weeks a rapeseed oil (LEAR) based margarine and shortening. For the next 8 weeks, 42 subjects continued with these products, while the other subjects received products with a vegetable oil (n=36) or a pine wood based stanol ester mixture (n=34). Consumption of 3.8 g vegetable oil based stanols (2.6 g sitostanol plus 1.2 g campestanol) lowered LDL cholesterol 14.6+/-8.0% (-0.37 mmol/l; vs. the control group; P<0.001; 95% CI for the difference, -0.22 to -0. 51 mmol/l). Four grams pine wood based stanols (3.7 g sitostanol plus 0.3 g campestanol) showed a comparable decrease of 12.8+/-11.2% (-0.34 mmol/l; P<0.001; 95% CI-0.18 to-0.51 mmol/l). Decreases in LDL cholesterol were not different between the two experimental groups (P=0.793), while apoE genotype did not have a major impact on this hypocholesterolemic response. Serum HDL cholesterol and triacylglycerol concentrations were not changed. The decreases in apo B in both experimental groups differed significantly (P<0.001) from changes in the control group. Coagulation and fibrinolytic parameters were not affected. We therefore conclude that vegetable oil and wood based stanol ester mixtures, with a different sitostanol/campestanol ratio, have similar LDL cholesterol lowering effects in a non-hypercholesterolemic population.     

壳聚糖/聚乙二醇琥珀酸酯薄膜的制备及其与肌成纤维细胞的相容性

目的：制备防粘连壳聚糖/聚乙二醇琥珀酸酯薄膜并观察其与肌成纤维细胞的相容性。方法：实验于2006-05/11在南方医科大学附属珠江医院中心实验室完成。实验材料：在透析后的壳聚糖与聚乙二醇琥珀酸酯或聚乙二醇共混后置入冻干机冻干制得壳聚糖/聚乙二醇琥珀酸酯薄膜或壳聚糖/聚乙二醇膜，并将新生2～5d的SD大鼠骨骼肌成纤维细胞种植于膜片上。实验评估：①MTT法测定肌成纤维细胞接种在不同膜片上的吸光度值，计算相对贴附率。相对贴附率=不同膜的A490nm/培养板的A490nm×100%。②MTT法测定肌成纤维细胞在不同膜片上的生长1，5d后的吸光度值。③相差显微镜下观察肌成纤维细胞的生长形貌。结果：①肌成纤维细胞在不同膜片上的贴附率：肌成纤维细胞在壳聚糖/聚乙二醇琥珀酸酯薄膜上能良好黏附、增殖，而在壳聚糖/聚乙二醇膜、壳聚糖膜上黏附性差。联合培养12h，5d后MTT法结果显示，壳聚糖/聚乙二醇琥珀酸酯组的A值分别为0.074±0.009，0.141±0.031，分别为壳聚糖组的6.17倍和6.13倍（P〈0.05）。②肌成纤维细胞的生长特性：肌成纤维细胞在壳聚糖/聚乙二醇琥珀酸酯膜上的活性最高，增殖能力最强，增长速度最快，其次为壳聚糖/聚乙二醇膜，但两者差异无显著性意义（P〉0.05），而细胞在壳聚糖膜上的增殖能力较低，膜上细胞数目较少，与其他组比较差异有显著性意义（P〈0.05）。③肌成纤维细胞与不同膜片联合培养1，5d时的生长形貌：壳聚糖膜上细胞未贴壁生长，为透明的圆球形，呈游离状态，未能很好舒展，且有些皱缩，生长活力也不旺盛;细胞与壳聚糖/聚乙二醇膜、壳聚糖/聚乙二醇琥珀酸酯膜片联合培养的生长情况要明显好于壳聚糖膜，细胞相互融合成片，多呈长梭形，细胞间隙狭窄，紧密排列成束，成指纹状结构且聚集生长的趋势也更明显。结论：将接支琥珀酰基的聚乙二醇与壳聚糖共混组成的网状系统改进了膜片的力学性能，提高了膜片的柔韧性，使其成膜性更好;壳聚糖/聚乙二醇琥珀酸酯薄膜具有良好的生物相容性，肌成纤维细胞在壳聚糖/聚乙二醇琥珀酸酯薄膜上的黏附及生长情况明显好于壳聚糖薄膜。     

Bilateral sagittal split osteotomy in a mandible previously reconstructed with a non-vascularized bone graft

We report a bilateral sagittal split osteotomy (BSSO) in a reconstructed mandible. A 28-year-old woman underwent a segmental mandibulectomy due to a multicystic ameloblastoma in the left jaw. After primary plate reconstruction, final reconstruction was performed with a left posterior iliac crest cortico-cancellous autograft. Due to a pre-existing Class II malocclusion, the patient was analyzed for combined orthodontic–surgical treatment. Subsequently, after 1 year of orthodontic treatment, the BSSO was planned. The sagittal split was performed in the remaining right mandible and on the left side in the iliac crest cortico-cancellous autograft. Ten months later, oral rehabilitation was completed with implant placement in the neomandible. Follow-up showed a Class I occlusion, with good function. The patient was very satisfied with the functional and aesthetic results. This case shows that a BSSO can be performed in a reconstructed mandible, without side effects and with good functional and aesthetic results.     

Potential increased risk of virus transmission due to exclusion of older donors because of concern over Creutzfeldt-Jakob disease. The National Heart, Lung, and Blood Institute Retrovirus Epidemiology Donor Study

BACKGROUND: Concern over the theoretical possibility of disease transmission via blood from donors who develop Creutzfeldt-Jakob disease has led to proposals to exclude older individuals from donating plasma for further manufacture into pooled plasma donations. The impact of extending this age-deferral policy to blood donors was examined with respect to the risk for known transmissible viruses. STUDY DESIGN AND METHODS: Demographic characteristics and confirmed prevalence rates (/10(5) first-time donations) and incidence rates (/10(5) person-years for repeat donors) for viral markers were compared for donors < 50 years old (n = 1,259,805 [85%]) and > or = 50 years old (n = 219,856 [15%]) and for donors < 60 years old (n = 1,409,176 [95%]) and > or = 60 years old (n = 70,485 [5%]). Incidence rates were combined with infectious window-period estimates for each virus, to calculate the risk of virus transmission per 10(6) donations. RESULTS: Unadjusted prevalence rates were significantly greater for younger than for older donor groups for human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg), and hepatitis C virus (HCV) (p < or = 0.05). Incidence rates (and transmission risk estimates) for HBsAg were significantly higher in the < 50 donor group than in the > or = 50 group (p < or = 0.05), and those for HIV, human T-lymphotropic virus, and HCV were not significantly higher (p > 0.05). Blanket removal of donors over the age of 50 would potentially lead to the following significant increases in the risk of infected units: HIV, 12 percent; HCV, 21 percent; and hepatitis B virus (HBsAg), 22 percent. CONCLUSION: Removal of donors over the age of 60 would not significantly affect the risk of infected units. Deferral of donors > or = 50 years of age from whole-blood donations for unfounded concerns about Creutzfeldt-Jakob disease could have adverse effects on both blood availability and safety.     

Blood group A immunodeterminants on human red cells differ in biologic activity and sensitivity to alpha-N-acetylgalactosaminidase

BACKGROUND: Epitopes of blood group A antigen can be enzymatically cleaved from red cells (RBCs), but the extent of cleavage required for normal survival in allogeneic blood transfusion recipients is unknown. Therefore, the cleavage rates were studied for A antigen epitope binding of 1) complement-activating anti-A, 2) Dolichos biflorus anti- A, lectin, and 3) hemagglutinating anti-A during incubation with a purified alpha-N-acetylgalactosaminidase, E.C. 3.2.1.49 (alpha- GalNAc'ase). STUDY DESIGN AND METHODS: Suspensions of group A RBCs were incubated with alpha-GalNAc'ase. Cells were removed at intervals, washed, and tested for loss of binding by monoclonal, polyclonal, and complement-activating anti-A, D. biflorus anti-A1 lectin, and Ulex europaeus anti-H lectin. RESULTS: A epitopes binding D. biflorus lectin were highly susceptible to alpha-GalNAc'ase; simultaneously with their loss, binding with U. europaeus lectin emerged. Loss of complement- mediated hemolysis was slower. A epitopes binding hemagglutinating anti- A were most resistant. Cleavage of A epitopes from membrane glycosphingolipids with short oligosaccharide chains was similarly resistant. Rates of cleavage from A1 and A2 RBCs were similar. CONCLUSION: RBC epitopes of blood group A differ in susceptibility to cleavage and biologic reactivity, which suggests that subsets mediating important biologic functions exist on functionally and topographically distinct membrane glycoconjugates.