Catecholamine uptake, accumulation, and release in acute porphyria

Hypertension and tachycardia are well known features of acute porphyria and have been shown to be related to increased circulating catecholamines. The mechanism by which circulating catecholamines are increased was studied using the isolated perfused rat heart and human platelets as a model of adrenergic neuronal function. It was found that neither delta-aminolevulinate (ALA) nor porphobilinogen (PBG) blocked uptake or caused release in the isolated perfused rat heart. Platelets from six patients with acute prophyria, three in remission and three latent, with matching normal controls were studied with regard to their uptake of [(3)H]norepinephrine in the presence of ALA or PBG. It was found that ALA and PBG significantly reduced uptake and accumulation of [(3)H]-norepinephrine in patients with acute porphyria; however, no similar reduction in uptake and accumulation was observed in the platelets of normal controls. Therefore, it appears that there is a latent defect in the catecholamine uptake and (or) accumulation of platelets of patients with acute prophyria which only manifests itself in the presence of ALA or PBG. If platelet uptake serves as a model of adrenergic neuron uptake, this suggests that elevated circulating catecholamine levels during acute attacks of acute porphyria are caused at least partially by blockade of re-uptake into the sympathetic neurons.     

The presence of genital mycoplasmas in women of reproductive age

Although 5-HT1 and 5-HT2 receptor activity is known to influence copulation, the effects of 5-HT3 receptor-selective drugs on sexual activity have yet to be systematically studied. The following experiments investigated the effects of the 5-HT3-selective antagonists MDL 72222, ondansetron and ICS 205-930 on female sexual behaviour; male rats were studied using ondansetron and granisetron. These compounds influenced neither male nor female copulatory behaviours, suggesting that 5-HT3 receptors contribute little to the modulation of sexual activity. 5-HT3 receptor antagonists block certain opioid-induced behaviours and opioids selectively inhibit sexual behaviours; therefore, the ability of ondansetron and ICS 205-930 to modify morphine-attenuated copulatory activity was also tested. While morphine inhibited copulation, 5-HT3 antagonists failed to reverse the effects.     

The use of salbutamol in obstetrics

Sympathomimetic amines have been used with the aim of abolishing uterine contractions. On the basis of results from an in vivo technique for testing the specificity and affinity of the beta2-receptor stimulating agents, salbutamol was used for a clinical trial. Five case histories were selected in order to illustrate the possibility of utilizing salbutamol in emergency cases with the aim of achieving uterine relaxation during the period of time between the admission of the patient and the commencement of delivery by, for example, caesarean section.     

The effect of the molluscicide N-tritylmorpholine on transmission of Fasciola hepatica

Field trials were carried out in north Devon to investigate the relationship between molluscicide treatment of pastures and control of liver fluke infection in sheep. Seven tracer lambs per plot were used to estimate the infectivity of 17 pairs of 0.20 hectare plots. One plot in each pair was treated with the molluscicide Frescon (N-tritylmorpholine). There was a highly significant difference (P less than 0.001) between the numbers of Fasciola hepatica recovered from lambs grazed on treated and untreated plots in the period after molluscicide treatment. The overall degree of snail control achieved by one application of molluscicide to 17 plots was about 90 per cent and this was matched by a comparable degree of liver fluke control. There was considerable variation between the plots and there was no simple correlation between snail numbers and liver fluke numbers (r = -0.03). The use of molluscicides is discussed in relation to the biotic potential of Lymnaea truncatula and environmental factors which limit its population growth.     

Inhibition of N-linked glycosylation results in retention of intracellular apo[a] in hepatoma cells, although nonglycosylated and immature forms of apolipoprotein[a] are competent to associate with apolipoprotein B-100 in vitro

Apolipoprotein[a] (apo[a]) is a highly polymorphic glycoprotein that forms a covalent complex with apolipoprotein B-100 (apoB-100), producing a lipoprotein species referred to as lipoprotein[a] (Lp[a]). We have studied the effects of alterations in glycosylation of apo[a] on its intracellular processing and secretion as well as its ability to associate with low density lipoprotein (LDL) apoB-100. HepG2 cells transfected with a 6 kringle IV (6 K-IV) apo[a] minigene were treated with tunicamycin, an inhibitor of N-linked glycosylation, which eliminated apo[a]-B-100 complexes from the media. Tunicamycin treatment also reduced secretion of the 6 K-IV apo[a] protein from transfected McA-RH7777 cells by approximately 50%, but completely eliminated secretion of apo[a] species containing 9 and 17 K-IV repeats. Mixing experiments, performed with radiolabeled media (+/-tunicamycin) from transfected McA-RH7777 cells, demonstrated no alteration in the extent of association of apo[a] with human LDL. Similar mixing experiments using culture media from glycosylation-defective mutant chinese hamster ovary (CHO) cells transfected with the same apo[a] minigene showed identical results. Apo[a] secretion was demonstrated in all mutant cell lines in the absence of either N- or O-linked (or both) glycosylation. The mechanisms underlying the reduced secretion of apo[a] from transfected hepatoma cells were examined by pulse-chase radiolabeling and apo[a] immunoprecipitation. Tunicamycin treatment altered the efficiency of precursor apo[a] processing from the ER by increasing its ER retention time. The increased accumulation of precursor apo[a] in the ER was associated with alterations in the kinetics of association with two resident endoplasmic reticulum (ER) chaperone proteins, calnexin and BiP. These findings suggest that the glycosylation state and size of apo[a] appear to play a role in regulating its efficient exit from the endoplasmic reticulum. However, neither N- nor O-linked glycosylation of apo[a] exerts a major regulatory role in its covalent association with apoB-100.     

Deposition from Particle-Laden, Plane, Turbulent, Buoyant Jets

Laboratory and computational fluid dynamics (CFD) model studies with turbulent, plane, particle-laden buoyant jets discharged horizontally into a quiescent ambient fluid have demonstrated that the presence of particles has no significant influence upon the buoyant jet trajectories over a wide range of forcing conditions and source concentrations of 0.1% or less. Bed deposition distributions show a large initial maximum close to the source, indicative of a dominant, localized particle fall-out from the buoyant jet margins. Beyond this near-source region, the distributions show a gradual decrease in particle deposition with increasing distance from the source, as a result of particle fall-out from the spreading surface layer generated by the buoyant jet impinging on the free surface of the receiving waters. In both cases, the deposition distributions scale well with the nondimensional settling parameter ws/b01/3 and the source Froude number F0. CFD simulations show good agreement with the laboratory data, particularly for deposition distributions downstream of the source. Additionally, the simulations indicate clearly that the receiving water boundaries can produce significant secondary return flows through fluid displacement by the spreading surface gravity current and its subsequent reflection.     

有机朗肯循环中滚动活塞式膨胀机膨胀比最优化研究

针对容积式膨胀机出口压力与冷凝器内背压不同导致不可逆损失现象的存在,改进并设计了可变膨胀比的滚动活塞式膨胀机,并分析其工作原理。以R245fa为工质,研究了蒸发器内有机工质无过热、膨胀机无泄漏条件下,系统参数变化对膨胀机最佳膨胀比的影响。结果表明:膨胀机的最佳膨胀比受膨胀机效率的影响很小,而受发生温度和冷凝温度的影响较大,蒸发温度越高,最佳膨胀比越大,冷凝温度越高,最佳膨胀比越小,当系统某参数变化时,可以通过调节系统的其他参数使膨胀机处于最佳膨胀比下运行。为膨胀机膨胀比的设计和运行工况的选择提供参考依据。     

粗纺呢绒缩呢工艺的优化研究

粗纺缩呢工序是粗纺毛织物整理加工过程中的一项重要工序,对产品质量起着十分重要的作用。利用正交试验的方法,对纯毛麦尔登产品后整理的缩济用量、pH值、缩箱压力三因素进行正交试验,优选出最佳加工工艺参数为：缩剂用量4％,缩箱压力0．15MPa,pH值9．5。     

CFD-assisted scaling methodology and thermal-hydraulic experiment for a single spent fuel assembly

A computational fluid dynamics (CFDs)-assisted scaling methodology is proposed for a TN24P cask (Creer et al., 1987). In the proposed methodology, the height and the number of assemblies were scaled down based, respectively, on the integral scaling criteria by Ishii and Kataoka (1984) for a natural-circulation loop under single phase flow and on the concept of an insulator on the surface of the basket. The controlling scaling parameters for the TN24P cask (the scaling ratio of the heat flux, 1.6; the thickness and conductivity of the insulator, 9 mm and 0.05 W/m K, respectively) were estimated by comparing the results of a TN24P cask experiment (Creer et al., 1987) with those of a CFD simulation of a TN24P cask scaled down, using Fluent code. Based on the proposed scaling methodology and its scaling parameters, a thermal-hydraulic experiment with a half-height single assembly was carried out. The experiment was analyzed in comparison with a CFD simulation to validate the proposed CFD models in Fluent code. The results showed good agreement for the peak cladding temperature (215 °C from the experiment, 212 °C from the CFD). It is regarded that the proposed scaling methodology was reasonably validated as maintaining the similarity of the temperature gradient and the peak cladding temperature.