转谷氨酰胺酶对牛乳酪蛋白功能性质的影响

采用微生物转谷氨酰胺酶 (TG)对牛乳中的酪蛋白进行了酶法改性 ,并对改性后牛乳中酪蛋白功能性质如溶解性、起泡性、泡沫稳定性和持水性进行了研究 .结果表明 ,牛乳经TG作用后 ,其酪蛋白功能性质发生了较大变化 ,酪蛋白的起泡性、泡沫稳定性和持水性都有不同程度的增加 ,而溶解性略有下降 .实验中考察了TG作用的时间、温度、剂量等因素对酪蛋白功能性质的影响 ,结果显示 ,要获得综合性能优良的酪蛋白 ,TG最佳的作用条件为 :pH 7.0 ,5 0℃ ,6 0min ,酶的添加量0 .1～ 0 .2U/mL .     

小麦麸皮蛋白质的提取与应用

采用碱法将麸皮中蛋白质提取出来，测定麸皮蛋白的乳化性、乳化稳定性、持水性等功能特性，将其应用于乳化型碎肉制品中，获得与添加大豆分离蛋白相似的出品率和品质。以水解度（ＤＨ）１％～６％的酶法改性，使麸皮蛋白的持水性有较大的提高，但却使其乳化性下降，在碎肉制品的应用效果不佳。     

利用Maillard反应制备大豆蛋白-葡聚糖共价复合物

研究了大豆酸沉蛋白和葡聚糖共价键合制备反应及其产物乳化性能的变化.在干热条件下,两种大分子通过Maillard反应进行共价键合并通过聚丙烯酰胺凝胶电泳验证了大分子复合物的存在. 结果表明产物具有比大豆酸沉蛋白更高的对油/水乳状液的乳化能力,复合物在pH 3.0和pH 10.0时均能保持较好的乳化活性,并且在高温、高盐条件下乳化活性变化很小.     

功能性食品添加剂 N-乙酰-D-葡糖胺的理化性质

N-乙酰-D-葡糖胺是一种具有多种生理活性和功能性质的重要氨基糖 .实验研究了NAG的一些重要理化性质和加工稳定性 ,为NAG在食品中的应用提供理论依据 .结果表明 ,NAG易溶于水 ,微溶于乙醇 ;NAG晶体在 1 2 0℃、6h下保留率大于 98% ,性质稳定 ;在 1 0 0℃、6h、pH 3 .0～8.5的条件下 ,NAG水溶液稳定性好 ,pH超过 8.5则保留率大大降低 ,并伴有颜色变化 ;NAG在牛奶杀菌条件下性质稳定 ;NAG不具有吸湿性和保湿性     

脱脂小麦胚芽的蛋白酶法水解及其蛋白水解物的功能性质

研究了不同蛋白酶对脱脂小麦胚芽的水解特性.实验发现,碱性蛋白酶和复合风味酶可溶出脱脂小麦胚芽中蛋白质的80%,而木瓜蛋白酶、中性蛋白酶和复合蛋白酶则相对较低.对采用碱性蛋白酶得到的脱脂小麦胚芽蛋白水解物(DWGP)的功能性质进行了研究,pH值为6.0时氮溶指数约为70%,中性条件下乳化活性、乳化稳定性及乳化能力分别为64%,57%及62%.在pH值为7和70℃,持水性为232%.DWGP可作为一种潜在的功能性蛋白资源应用于食品中.     

苹果纤维对面粉持水性能力及蛋糕品质的影响

将苹果渣和苹果纤维添加至焙烤蛋糕的面粉中,测定了蛋糕粉湿面筋含量和浆料粘度的变化。探讨了对蛋糕的比容及老化的影响,结果表明:苹果渣和苹果纤维会引起面粉持水性的改变。苹果纤维同面粉混合后的总持水性,常温下为两者的线性之和;纤维的添加能导致湿面筋含量的下降,下降幅度同纤维的含量有关。表观粘度系湿面筋的形成能力与纤维持水性两者的综合效应。该结果有助于进一步研究纤维同小麦面筋之间的相互作用并为蛋糕品质的改善提供了实验依据。     

猪苓多糖超声提取工艺条件优化

采用超声提取方法研究了猪苓茵核多糖提取的优化工艺条件.结果表明,在超声功率为100W时,其最佳提取条件为60℃,料液比为1 g:30 mL,pH值为7.0,提取时间为40 min,P.umbellatus LBZ多糖的量为20.3 mg/g.与常规的沸水浴提取法比较,超声提取能显著提高猪苓多糖含量、缩短提取时间、减小料液比和降低提取温度.     

大豆11S球蛋白在空气-水界面上的吸附动力学

采用轴对称滴形分析法研究了大豆11S球蛋白在空气-水界面上的吸附动力学，主要检测了不同浓度和pH值条件下表面压力随吸附时间的变化。实验表明，大豆11S球蛋白在空气-水界面上的吸附随初始体相蛋白质质量分数的增加而加快，受pH值的影响尤其明显。当pH=3．0时，1S1球蛋白快速吸附到空气-水界面上；而当pH=5．0时，吸附明显下降。在吸附的初始阶段，扩散控制吸附动力学；而当表面压力较高时，蛋白质分子在界面上的展开和重排控制吸附动力学。     

1990年我院部分科研成果简介

1 婴儿食品加工工艺与设备的研究传统的婴儿食品加工工艺,过程复杂,能耗大,产品成本高。该研究提出了以挤出膨化工艺生产婴儿断奶食品,研制了JSP-65型食品膨化机,使大豆、谷物混合料在挤出膨化机里一步同时完成大豆去毒,淀粉α化。本工艺流程短,设备投资省,生产的膨化代乳粉色泽、口感、复水性好,有利于消化吸收,是一种新型的方便乳儿食品,为婴儿食品生产提供了新的技术途径,有明显的社会效益和经济效益,便于推广应用。     

超滤处理对大豆肽体外免疫功能的影响

考察了不同pH值（4.0、7.0、9.0）条件下采用不同截留相对分子质量（MWCO）的8000复合膜（醋酸纤维＋聚砜）和5000 PES（聚醚砜）的超滤膜对大豆肽处理前后对小鼠体外免疫功能的影响。通过体外培养白细胞实验,比较了大豆肽超滤处理前后对小鼠腹腔巨噬细胞吞噬功能和脾细胞增殖能力的影响。结果表明,所有大豆肽均能提高小鼠腹腔巨噬细胞的吞噬能力,促进小鼠脾淋巴细胞增殖,而经过超滤处理后的大豆肽免疫功能有所提高,且以pH4.0条件下MWCO为5000超滤膜处理后所得的大豆肽活性最强。     

Vasopressor hormone response following mesenteric traction during major abdominal surgery

Background : We investigated the vasopressor hormone response following mesenteric traction (MT) with hypotension due to prostacyclin (PGI₂) release in patients undergoing abdominal surgery with a combined general and epidural anesthesia. Methods : In a prospective, randomized, placebo-controlled study we administered 400 mg ibuprofen (i.v.) in 42 patients scheduled for abdominal surgery. General anesthesia was combined with epidural anesthesia (T4-L1). Before as well as 5, 15, 30, 45, and 90 min after MT we recorded plasma osmolality, hemodynamics and measured 6-keto-PGFlα (stabile metabolite of PGI₂), TXB₂ (stabile metabolite of thromboxane A₂) active renin, and arginine vasopressin (AVP) plasma concentrations by radioimmunoassay. Catecholamine levels were assessed by high-pressure liquid chromatography (HPLC) with electrochemical detection. Results : Following MT, arterial hypotension occurred along with a substantial PGI₂ release. This was completely abolished by ibuprofen administration. Although plasma levels of 6-keto-PGF_1α (1133 (708) vs. 60 (3) ng/L, median (median absolute deviation), P=0.0001, placebo vs. ibuprofen) remained significantly elevated, blood pressure was restored within 30 min after MT in the placebo group. At the same point in time plasma concentrations of TXB² (164 (87) vs. 58 (1) ng/L, P=0.0001), epinephrine (46 (33) vs. 14 (6) ng/L, P=0.001), AVP (41 ± (18) vs. 12 (7) ng/L, P=0.0004), and active renin (27 (12) vs. 12 (4) ng/L, P = 0.001) were significantly higher in placebo-treated patients. Conclusion : Under combined general and epidural anesthesia arterial hypotension following MT due to endogenous PGI₂ release is associated with enhanced release of AVP, active renin, epinephrine and thromboxane A₂, presumably contributing to hemodynamic stability within 30 min after MT.     

A Teaspoon Pump for Pumping Blood with High Hydraulic Efficiency and Low Hemolysis Potential

Abstract: Virtually all blood pumps contain some kind of rubbing, sliding, closely moving machinery surfaces that are exposed to the blood being pumped. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The original teaspoon pump design prevented the rubbing, sliding machinery surfaces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to "slip around" the rotating impeller so that the blood itself never rotated fast enough to develop adequate pressure. An improved teaspoon blood pump has been designed and tested and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating "swinging" hose as the pump impeller. The fluid enters the pump through the center of the swinging hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that is comparable to a flexible garden hose. If the free end of the hose were swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impeller itself did not "rotate"; therefore, no rotating shaft seal or internal bearings are required.     

Microspheres Based Detoxification System: A New Method in Convective Blood Purification

Abstract: A variety of protein-bound or hydrophobic substances, accumulating as a result of pathologic conditions such as exogenous or endogenous intoxications, are removed poorly by conventional detoxification methods because of low accessibility (hemodialysis), insufficient adsorption capabilities (hemosorption), low efficiency (peritoneal dialysis), or economic limitations (high-volume plasmapheresis). Combining advantages of existing methods with microspheric technology, a module-based system was designed. Major operating parameters of the latter can be modified to allow for adjustment to individual clinical situations. An extracorporeal blood circuit including a plasmafilter is combined with a secondary high-velocity plasma circuit driven by a centrifugal pump. Different microspheric adsorbers can be combined in one circuit or applied in sequence. Thus, a prolonged treatment can be tailored using specially designed selective adsorber materials. Comparing this system with existing methods (high-flux hemodialysis, molecular adsorbent recycling system), results from our in vitro studies and animal experiments demonstrate the superior efficiency of substance removal.     

Tissue perfusion in relation to cardiac output during continuous positive-pressure ventilation and administration of propranolol or verapamil

Background : Our objective was to determine whether administration of propranolol or verapamil modifies the hemodynamic adaptation to continuous positive-pressure ventilation (CPPV), in particular the regional distribution of cardiac output (CO).
Methods : General hemodynamics and regional blood flows assessed by microsphere technique (15 (μm) were recorded in 16 anesthetized pigs during spontaneous breathing (SB) and CPPV with 8 cm H₂O end-expiratory pressure (CPPV8) before and after intravenous administration of propranolol (0.3 mg · kg⁻¹ followed by 0.15 mg · kg⁻¹ · h⁻¹, n=8) or verapamil (0.1 mg · kg⁻¹ followed by 0.3 mg · kg⁻¹ · h⁻¹, n=8).
Results : CPPV8 depressed CO by 25% without shifts in its relative distribution with the exception of a noteworthy increase in adrenal perfusion. Propranolol increased arterial blood pressure, and due to a fall in heart rate, CO dropped by 25%. The kidneys and, to a lesser extent, the splanchic region and central nervous system received increased fractions of the remaining CO at the expense of skeletal muscle flow. Similar patterns were seen during SB and CPPV8 such that the combination of propranolol and CPPV8 depressed CO by 50%. The circulatory effects of verapamil were less evident but myocardial perfusion tended to increase.
Conclusions : The combination of propranolol or verapamil with CPPV does not result in any specific hemodynamic interaction in anesthetized pigs, except that the combined effect of propranolol and CPPV may severely reduce CO.     

Bariatric Surgery in Some "Central and East-European (former Eastern bloc)"Countries - Current Status and Prediction for the Next Millennium

Background: Obesity is increasing globallly, including in the formerly "Eastern Bloc" countries. Methods: A survey was made of obesity and bariatric surgery. Results: In the 8 East and Central European countries studied, with total population 300 million, roughly 43% of the population was overweight (BMI 25-30), 23% obese (BMI > 30), with about 15 million people morbidly obese (BMI > 40). From 0-10 morbidly obese individuals/100,000/year undergo bariatric surgery. Conclusion: Most countries were found to provide inadequate treatment for obesity.The majority of the morbidly obese are not treated effectively. However, health-care awareness of obesity and bariatric surgeons are slowly increasing.     

Volatile anaesthetics reduce adhesion of blood platelets under low-flow conditions in the coronary system of isolated guinea pig hearts

Background : Inhibitory effects of volatile anaesthetics on platelet aggregation have been demonstrated in several studies. However, the influence of volatile anaesthetics on intracoronary platelet adhesion has not been elucidated so far.
Methods : Isolated hearts of guinea pigs were perfused with buffer in the absence or presence of volatile anaesthetics (0.5 and 1 MAC) at constant coronary flow rates of 5 ml/min for 25 min, then 1 ml/min for 30 min and again 5 ml/min for 10 min. Before, during and after low-flow perfusion, a bolus of human platelets was applied into the coronary system. To simulate thrombogenic conditions, 0.3 U/ml human thrombin was infused during low-flow perfusion and reperfusion. The number of platelets sequestered to the endothelium was calculated from the difference between coronary in- and output of platelets. The myocardial production of lactate and consumption of pyruvate and coronary perfusion pressure were also determined.
Results : At a flow rate of 5 ml/min only about 3% of the applied platelets did not emerge from the coronary system, in any group. In contrast, 13.1±1.2% (mean±SEM) of infused platelets became adherent in low-flow perfusion in the control group without anaesthetic. The adherence was reduced with each 1 MAC isoflurane (to 6.2±1.2%), sevoflurane (to 4.4±0.9%) or halothane (to 3.2±1.5%) (each P <0.05 vs. control). Volatile anaesthetic, 0.5 MAC, did not inhibit platelet adhesion to a statistically significant extent in any case. Perfusion pressure and metabolic parameters were not statistically different between the control and the hearts exposed to anaesthetics.
Conclusion : Volatile anaesthetics in a concentration of 1 MAC can reduce the adhesion of platelets in the coronary system under reduced flow conditions. This action does not arise from vasodilation or inhibition of ischaemic stress.     

Synergistic interaction between the effects of propofol and midazolam with fentanyl on phrenic nerve activity in rabbits

Background: It has been shown that the depressive effects of both propofol and midazolam on consciousness are synergistic with opioids, but the nature of their interactions on other physiological systems, e. g. respiration, has not been fully investigated. The present study examined the effect of propofol and midazolam alone and in combination with fentanyl on phrenic nerve activity (PNA) and whether such interactions are additive or synergistic. Methods: PNA was recorded in 27 anaesthetised and artificially ventilated rabbits. In three groups, propofol, fentanyl and midazolam were administered intravenously in incremental doses to construct dose-response curves for the depressant effects of each one on PNA. In another two groups, the effect of pretreatment with either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. on the effects of propofol and fentanyl respectively on PNA were studied. Results: Propofol and fentanyl caused a dose-dependent depression of PNA with complete abolition at the highest total doses of 16 mg · kg^?1 i. v. and 32 μg · kg^?1 i. v., respectively. In contrast, midazolam in incremental doses to a total of 0.8 mg · kg^?1 reduced mean PNA by 63%, but approximately 12% of PNA remained at a total dose as high as 6.4 mg · kg^?1. The mean ED₅₀s, calculated from dose-response curves, were 5.4 mg · kg^?1, 3.9 μg · kg^?1 and 0.4 mg · kg^?1 for propofol, fentanyl and midazolam, respectively. Initial doses of either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. acted synergistically with subsequent doses of either propofol or fentanyl to abolish PNA at total doses of 8 mg · kg^?1 and 8 μg · kg^?1, respectively. Conclusion: Fentanyl has a synergistic interaction with both propofol and midazolam on PNA and hence potentially on respiration.     

Influence of dopexamine hydrochloride on haemodynamics and regulators of circulation in patients undergoing major abdominal surgery

Background: Catecholaminergic support is often used to improve haemodynamics in patients undergoing major abdominal surgery. Dopexamine is a synthetic vasoactive catecholamine with beneficial microcirculatory properties. Methods: The influence of perioperative administration of dopexamine on cardiorespiratory data and important regulators of macro- and microcirculation were studied in 30 patients undergoing Whipple pancreaticduodenectomy. The patients received randomized and blinded either 2 μg · kg^?1 · min^?1 of dopexamine (n=15) or placebo (n=15, control group). The infusion was started after induction of anaesthesia and continued until the morning of the first postoperative day. Endothelin-1 (ET-1), vasopressin, atrial natriuretic peptide (ANP), and catecholamine plasma levels were measured from arterial blood samples. Measurements were carried out after induction of anaesthesia, 2 h after onset of surgery, at the end of surgery, 2 h after surgery, and on the morning of the first postoperative day. Results: Cardiac index (CI) increased significantly in the dopexamine group (from 2.61±0.41 to 4.57±0.78 1 · min^?1 · m^?2) and remained elevated until the morning of the first postoperative day. Oxygen delivery index (DO₂I) and oxygen consumption index (VO₂I) were also significantly increased in the dopexamine group (DO₂I: from 416±91 to 717±110 ml/m² · m²; VO₂I: from 98±25 to 157±22 ml/m² · m²), being significantly higher than in the control group. pHi remained stable only in the dopexamine patients, indicating adequate splanchnic perfusion. Vasopressive regulators of circulation increased significantly only in the untreated control patients (vasopressin: from 4.37±1.1 to 35.9±12.1 pg/ml; ET-1: from 2.88±0.91 to 6.91±1.20 pg/ml). Conclusion: Patients undergoing major abdominal surgery may profit from prophylactic perioperative administration of dopexamine hydrochloride in the form of improved haemodynamics and oxygenation as well as beneficial influence on important regulators of organ blood flow.     

A comparison of the inhibitory effects of four volatile anaesthetics on the metabolism of chlorzoxazone, a substrate for CYP2E1, in rabbits

Background: Halothane inhibits in vitro and in vivo activity of cytochrome P-450 (CYP) 2E1. There are several fluorinated volatile anaesthetics besides halothane, and most of them are defluorinated by CYP2E1. It is unclear whether other fluorinated anaesthetics inhibit the in vivo activity of CYP2E1.
Methods: We compared the inhibitory effects of therapeutic concentrations of four inhalational anaesthetics, halothane, enflurane, isoflurane, and sevoflurane, on chlorzoxazone metabolism in rabbits receiving artificial ventilation.
Results: All four inhalational anaesthetics decreased arterial blood pressure and increased plasma chlorzoxazone concentration. However, no significant differences in the plasma chlorzoxazone concentration were found between the four anaesthetics. The estimated chlorzoxazone clearance increased after beginning inhalation with all four agents, but no significant difference in clearance was noted between agents.
Conclusions: At therapeutic concentrations, the in vivo inhibitory effect on chlorzoxazone metabolism was similar for all four inhalational anaesthetics examined, even though their chemical characteristics and extent of hepatic metabolism differ considerably.     

Systemic analgesia adapted to the children's condition

A concept of balanced analgesia using nonsteroidal anti-inflammatory drugs (NSAIDs), paracetamol (acetaminophen), opioids, and corticosteroids can also be used in patients with pre-existing illnesses. NSAIDs are the most effective treatment for acute pain of moderate intensity in children; however, these drugs should be avoided in patients at increased risk for serious side effects, e.g. patients with renal impairment, bleeding tendency, or extreme prematurity. NSAIDs can be given with minimal risks to the younger child with mild to moderate asthma, and, in these patients, the use of steroids can be encouraged; in addition to their antiemetic and analgesic action, a beneficial effect on asthma symptoms can be expected. In the non-intubated child with cerebral trauma, exaggerated sedation caused by opioids and increased bleeding tendency caused by NSAIDs must be avoided. In neonates and small infants, the oral administration of sucrose or glucose is helpful to minimize pain reaction during short uncomfortable interventions.