Grafting an RGD motif onto an epidermal growth factor-like module: chemical synthesis and functional characterization of the chimeric molecule

Abstract: A novel protein was engineered by inserting the GRGDS motif of fibronectin within the 14-residue loop of the EGF-like module from human complement protease C1r. The resulting chimeric EGF-RGD module (52 residues, three disulfide bridges) was assembled by automated solid-phase synthesis using the t-Boc strategy. Using reduced/oxidized glutathione, the EGF-RGD module was folded as efficiently as the natural C1r-EGF module, resulting in formation of the appropriate disulfide bridge pattern as shown by mass spectrometry and N-terminal sequence analyses of thermolytic fragments. Circular dichroism and NMR measurements provided further indication that introduction of the GRGDS motif had no significant effect on the folding. Using Chinese Hamster Ovary (CHO) cells bearing the integrin receptors specific for fibronectin and vitronectin, EGF-RGD was shown to induce cell adhesion via the introduced GRGDS motif. Cell binding was inhibited specifically and efficiently by the synthetic peptide GRGDSP and by fibronectin, and to a much lesser extent by vitronectin, whereas the monoclonal antibody PB1 directed to the α5 subunit of α5β1 integrin had no effect. The ability of EGF-RGD to trigger significant cell spreading and intracellular signaling was also demonstrated using immunofluorescence and confocal microscopy.     

小儿清热止咳颗粒药效作用研究

为确定小儿清热止咳颗粒的药效分别进行了七组动物实验。结果表明：小儿清热止咳颗粒对大肠杆菌内毒素引起的家兔发热有显著抑制作用;体外对金葡球菌、乙链球菌、绿脓杆菌、大肠埃希氏菌、痢疾杆菌有明显抑制作用;对金葡球菌攻击小鼠无明显保护作用;能明显降低浓氨水所致小鼠咳嗽次数;能明显促进小鼠气管分泌酚红及促进大鼠排痰,对组胺引起离体豚鼠气管平滑肌痉挛有明显的解痉作用。     

Environmental dew point and skin and lip weathering

Xerosis represents a physiological response of the stratum corneum (SC) to environmental threats. The influence of the environmental dew point (DP) is not fully understood. This parameter is the air temperature at which the relative humidity is maximum. This study aimed to assess the relationship between the environmental DP and the water‐holding capacity of the skin and lower lip vermilion. For comparison, SC property was evaluated after occlusive application of cooled and uncooled hydrogel pads. Electrometric measurements using a dermal phase meter (DPM) device were performed on the back of the hands, the cheeks and the lower lip of 40 healthy menopausal women. Assessments were performed in the outdoor conditions during winter and spring. The same measurements were recorded after hydrogel pads, at room temperature or cooled to 4 °C, were placed for 15 min on the test sites. The environmental DP was recorded at each evaluation time. The SC water‐holding capacity was discretely influenced by the DP. In the open‐air environmental conditions, a positive linear relationship was found on the cheeks between the DP and DPM values. The relationship was weaker on the lips. Conversely, a consistent increase in DPM values was recorded immediately after removal of the cooled and uncooled hydrogel pads. The observations made in the open‐air testing conditions are consistent with the predicted events following the Arrhenius law. By contrast, the combination of cooling and occlusion by the hydrogel pads is responsible for the reverse effect on the SC.     

Influence of vagal cooling on cardiac output in normal and beta-blocked exercising dogs

Summary To study the relative influence of parasympathetic and sympathetic innervation on the early adaptation of cardiac output (CO) to exercise, we determined the time constant and amplitude of the CO change in dogs following a stepwise increase in treadmill velocity. The animals were studied during control conditions, beta-blockade, vagal blockade and combined beta-blockade and vagal blockade. To measure CO, an electromagnetic flow probe was implanted around the ascending aorta. Vagal activity was blocked with coolers, implanted around the cervical vagosympathetic trunks.The time constant during beta-blockade (12.1 s) was not different from the control situation (11.4 s), but during vagal cooling it increased significantly (16.2 s), and with combined vagal cooling and beta-blockade it rose to 20.7 s. Thus the increase in cardiac output with exercise is accelerated most by the loss of vagal tone and to a lesser degree by sympathetic activation.The amplitude of the change in CO during control was 112%. Heart rate (HR) rose by 74% and stroke volume (SV) by 22%. Beta-blockade lowered the initial CO but did not alter the percentage increase. Vagal cooling, with or without beta-blockade, caused an increased initial HR but did not influence basal CO because of a concomitant reduction in SV. Exercise now increased HR less (21% and 30%, respectively) and SV more (52% and 52%) but the increase in CO did not change significantly (87% and 97%).Both the high percentage increase in CO (87%) and the time constant during combined beta-blockade and vagal blockade (20.7 s), which is far less than previously found in dogs with surgically denervated hearts (29.5 s), suggest the existence of a non-vagal, non-beta-adrenergic innervation of the heart.     

The projection of the nucleus reticularis tegmenti pontis and adjacent regions of the pontine nuclei to the central cerebellar nuclei in the cat

The projection of the nucleus reticularis tegmenti pontis (NRTP) and the pontine nuclei (NP) to the central cerebellar nuclei (CCN) was investigated by means of anterograde transport of tritiated leucine. Although termination was found in all the CCN, it was most pronounced in the lateral nucleus and the lateral aspect of the posterior interposed nucleus. The extreme lateral aspect of the anterior interposed nucleus and the caudal part of the fastigial nucleus received a projection of modest intensity. Termination in the infracerebellar nucleus and group Y is likely to be present but could not be confirmed with certainty from the light microscopical material. The contribution from the NP was small and originated from the dorsolateral and dorsal paramedian subdivisions of the NP. Within the NRTP the total area giving rise to projections to the CCN was extensive, and the origin of the projections to the individual CCN overlapped considerably. The projection of the NRTP to the ventrocaudal part of the lateral nucleus was found in conjunction with a projection to the ventrolateral part of the posterior interposed nucleus. Both projections seemed to branch off the fiber bundle terminating in the ventral paraflocculus. Similar correlations could be established in the projection of the NRTP to the dorsal paraflocculus and crus II of the ansiform lobule with other parts of the lateral and posterior interposed nuclei. It was concluded that the transverse, lobular organization of mossy fibers, which differs fundamentally from the longitudinal, modular organization of climbing fibers, is maintained in the collateral projection to the CCN. The results are further discussed in relation to the corticonuclear projection and the engagement of the NRTP and different parts of the CCN in pontocerebellar circuits.     

Global cerebral ischemia and subsequent selective hypothermia

Summary A new method of external selective brain cooling is described, showing its effectiveness in reducing neuronal damage following global cerebral ischemia in cat. The cooling apparatus consists of a specially fitted kind of water jacket in which the animal's head was laid. In a preliminary study it was verified that the device effectively reduces brain temperature without the risk of cardiac arrhythmias due to lowering of core temperature. In the main study cardiac arrest was induced in 23 adult cats, followed after 15 min by cardiopulmonary resuscitation (CPR). Eight cats could not be revived; of the 15 remaining animals, 7 were assigned to the control group (normothermia) and 8 to the treatment group (cerebral hypothermia). The latter received external brain cooling for 30 min, starting as soon as CPR was begun. Four hours after cardiac arrest all animals were transcardiacally perfused with glutardialdehyde. The brains were stored in fixative and subsequently processed for histopathological and morphometrical evaluation by light microscopy. Analysis of the resulting data showed that animals in the treatment group had a significantly higher percentage of undamaged neurons than animals in the control group, both in the cingulate gyrus (38% vs 10%) and in the parietal cortex (39% vs 14%). The treatment group also had more undamaged neurons in the hippocampus and fewer severely damaged neurons in all three regions, but these differences, though suggestive, were not statistically significant.     

Laser Resistance of Endotracheal Tubes II: ObservedTemperature Rise and Theoretical Explanation

An infrared camera was used to measure the temperature rise which takes place in endotracheal tubes exposed to a 20 W CO₂ laser beam. It was seen that a metallic tube was heated up within 1 s to temperatures of 200–300°C which was very destructive to the PVC conduits inside the tube. A compound tube, on the other hand, reached temperatures of only 60°C at its inner surface after an exposure of 20 s. The experimental results can be explained by a physical model which uses the heat conduction and the heat capacities of both tubes. Whereas heat conduction in the metal tube is isotropic, heat conduction in the compound tube is anisotropic with a high conductivity along the outer surface and a low conductivity to the inside. This anisotropy and the cooling mechanism in the compound tube due to vaporising water are the reason for the high laser resistance of the tube. Paper received 13 June 1997; accepted after revision 16 February 1998.     

The role of α<Subscript>1</Subscript>-and β-adrenoceptors in initiation and development of thermoregulatory reactions during fast and slow cooling

Ionophoretic application of α₁-and β-adrenoceptor blockers into the skin produces no effect on the parameters of thermal homeostasis under thermoneutral conditions. α₁-Adrenoblocker verapamil inhibits cold shivering during fast and slow cold exposure; it elevates the temperature threshold and moderates the vasoconstrictor response during rapid cooling. These changes are accompanied by a compensatory decrease in the threshold and stimulation of non-shivering thermogenesis. Application of non-selective β-blocker propranolol had no effect on the temperature thresholds of the thermoregulatory reactions, but augmented the maximum amplitude of shivering during both cooling protocols, thereby compensating the decrease in non-shivering thermogenesis. In the whole organism, block of one type adrenoceptors during cold exposure is accompanied by activation of the compensatory mechanisms mediated by adrenoceptors of the other type. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 145, No. 3, pp. 259–262, March, 2008     

静脉输冷液治疗过热家兔和狗的效果

将家兔和狗暴露于热环境,使动物肛温升至42.5℃(家兔)和43.0℃(狗)。实验动物分成4组,正常对照组(室温20～25℃),过热对照组(不治疗),输液对照组(静脉输32±0.3℃生理盐水)和输冷液组(家兔和狗分别静脉输1.2±0.34℃和2.0±0.1℃生理盐水)。实验结果表明,肛温的最大下降值,输冷液兔组为2.43℃,输冷液狗组为2.81℃,输液对照兔组为0.5℃,过热对照兔组肛温不下降,过热对照狗组下降1.1℃。输冷液动物的活存率显著比过热对照组和输液对照高。热损伤病理改变,输冷液组显著比过热对照组和输液对照组轻。     

有机膦酸羧酸型水质稳定剂的研究——Ⅰ.2-膦酸丁烷-1,2,4-三羧酸的缓蚀阻垢作用

用旋转挂片失重法、腐蚀电化学测试方法,评定有机膦酸羧酸型水质稳定剂2-膦酸丁烷-1,2,4-三羧酸(PBTCA)在中性水介质中对碳钢的缓蚀性能,并采用近代表面分析手段,对PBTCA在碳钢表面上形成保护膜的元素三维成分分布、原子结合状态及成膜机理进行了研究。结果表明,PBTCA与Zn~(2+)具有明显的缓蚀协同效应,络合沉淀膜Zn(Ca)(Ⅱ)-PBTCA-Fe(Ⅲ)能有效地抑制碳钢腐蚀。静态、动态阻垢实验的结果表明,PBTCA具有优异的抑制钙垢沉积的作用。显微摄影术、X-射线衍射仪对钙垢从空白溶液中及含PBTCA水溶液中沉积后的晶体形貌及结构的比较,证明了PBTCA对CaCO_3、CaSO_4·2H_2O晶体成核过程的干扰及其晶格歪曲作用。实验结果说明PBTCA是一种有开发和应用前途的兼具缓蚀阻垢性能的有效的水质稳定剂。