Role of Liver X Receptor,Insulin and Peroxisome Proliferator Activated Receptor α on in Vivo Desaturase Modulation of Unsaturated Fatty Acid Biosynthesis

We examined the in vivo contribution of insulin, T090137 (T09), agonist of liver X receptor (LXR), fenofibrate, agonist of peroxisome proliferator activated receptor (PPAR-α) and sterol regulatory element binding protein-1c (SREBP-1c) on the unsaturated fatty acid synthesis controlled by Δ6 and Δ5 desaturases, compared with the effects on stearoylcoenzyme A desaturase-1. When possible they were checked at three levels: messenger RNA (mRNA), desaturase protein and enzymatic activity. In control rats, only fenofibrate increased the insulinemia that was maintained by the simultaneous administration of T09, but this increase has no specific effect on desaturase activity. T09 enhanced SREBP-1 in control animals and the mRNAs and activity of the three desaturases in control and type-1 diabetic rats, demonstrating a LXR/SREBP-1-mediated activation independent of insulin. However, simultaneous administration of insulin and T09 to diabetic rats led to a several-fold increase of the mRNAs of the desaturases, suggesting a strong synergic effect between insulin and LXR/retinoic X receptor (RXR). Moreover, this demonstrates the existence of an interaction between unsaturated fatty acids and cholesterol metabolism performed by the insulin/SREBP-1c system and LXR/RXR. PPAR-α also increased the expression and activity of the three desaturases independently of the insulinemia since it was equivalently evoked in streptozotocin diabetic rats. Besides, PPAR-α increased the palmitoylcoenzyme A elongase, evidencing a dual regulation in the fatty acid biosynthesis at the level of desaturases and elongases. The simultaneous administration of fenofibrate and T09 did not show additive effects on the mRNA expression and activity of the desaturases. Therefore, the results indicate a necessary sophisticated interaction of all these factors to produce the physiological effects.     

Influence of sodium profile in preventing complications during hemodialysis

Although a safe procedure, hemodialysis (HD) can cause numerous complications. The objective of this study was to evaluate the incidence of complications during dialysis, interdialytic weight gain, and the predialysis and postdialysis blood pressure in HD patients with and without variable sodium. Patients were observed during 12 HD sessions and those presenting with recurrent hypotension were selected for a step-wise model of variable sodium profiling. A total of 53 patients were evaluated; the mean-SD age was 53.7+/-16.3 years and 22 (41.5%) were male. Of these, 18 (34.0%) were selected to receive variable sodium profiling: the mean (SD) age was 59.9+/-12.6 years, and 10 (55.6%) were female. A significant decline in the occurrence of cramps (p<0.027), in the mean interdialytic weight gain (p<0.009), and a tendency to reduce the number of hypotensive episodes were detected in patients using variable sodium profiling. On the other hand, predialysis systolic blood pressure presented a significant increase (p<0.048). Using variable sodium, there was a statistically significant reduction in cramps and in the mean interdialytic weight gain. There was a significant increase in predialysis systolic pressure. Regarding hypotension episodes, only a tendency toward a reduction in the frequency of hypotension episodes could be detected.     

Friction Factor of Meandering Flows

An expression for the friction factor of rough turbulent meandering flows is suggested: flow cross section is rectangular, the plan shape of the meandering channel is sine-generated. This expression gives the value of the friction factor as a function of position (which is determined by, among other factors, the local channel curvature) and channel sinuosity. The validity of the present expression is tested against results of laboratory measurements. The measurements were carried out in two meandering channels, one typifying “small” sinuosity, the other “large” sinuosity. It is found that the vertically averaged flows in these two channels exhibit two distinctly different (“in-” and “out-going”) flow patterns, depending on whether the channel sinuosity is “large” or “small.” These two radically different flow pictures cannot be supplied by the vertically averaged equations of motion if they are solved for a constant friction factor. The present consideration of the friction factor as a function of position and channel sinuosity is found to yield the computed vertically averaged flows that are in agreement with the flow pictures measured for both large and small values of sinuosity.     

Effect of gelatine on the texture of yoghurt and of acid-heat-induced milk gels

 A penetrometry study was made of the effect of the addition of gelatine on the texture characteristics of yoghurts and acid-heat-induced milk gels. Detailed analysis of the various penetration profiles provided valuable information about the nature of the samples studied. Gelatine was compatible with the milk systems over a wide range of concentrations and it prevented syneresis. In yoghurts prepared with and without the addition of skim-milk powder, the addition of increasing concentrations of gelatine up to 1.5% gradually modified the mechanical characteristics of the final gels. In acid-heat-induced milk gels, whose mechanical characteristics depend on the final pH value, the addition of increasing quantities of gelatine up to 6.67% practically eliminated this dependence, and the effect of pH was only significant in the gels with 1.5% gelatine, which were structurally weaker. Received: 3 June 1998     

Characteristics of Retinitis Pigmentosa Associated with ADGRV1 and Comparison with USH2A in Patients from a Multicentric Usher Syndrome Study Treatrush

In contrast to USH2A, variants in ADGRV1 are a minor cause of Usher syndrome type 2, and the associated phenotype is less known. The purpose of the study was to characterize the retinal phenotype of 18 ADGRV1 patients (9 male, 9 female; median age 52 years) and compare it with that of 204 USH2A patients (111 male, 93 female; median age 43 years) in terms of nyctalopia onset, best corrected visual acuity (BCVA), fundus autofluorescence (FAF), and optical coherence tomography (OCT) features. There was no statistical difference in the median age at onset (30 and 18 years; Mann–Whitney U test, p = 0.13); the mean age when 50% of the patients reached legal blindness (≥1.0 log MAR) based on visual acuity (64 years for both groups; log-rank, p = 0.3); the risk of developing advanced retinal degeneration (patch or atrophy) with age (multiple logistic regression, p = 0.8); or the frequency of cystoid macular edema (31% vs. 26%, Fisher’s exact test, p = 0.4). ADGRV1 and USH2A retinopathy were indistinguishable in all major functional and structural characteristics, suggesting that the loss of function of the corresponding proteins produces similar effects in the retina. The results are important for counseling ADGRV1 patients, who represent the minor patient subgroup.     

耐候钢在2.0%NaCl中性溶液中的腐蚀过程

采用电化学阻抗谱技术研究了耐候钢Q400NQR1和09CuPCrNi在2.0％NaCl中性溶液中的腐蚀行为,建立了其腐蚀等效电路模型并分析了其相关电化学参数随时间的演化规律,结果表明,两种耐候钢的溶液腐蚀过程均可以分为四个阶段,即点蚀诱导期、点蚀发展期、腐蚀中期和腐蚀后期;Q400NQR1较09CuPCrNi具有较高的抗溶液腐蚀能力,前者在腐蚀的中期生成保护性较强的内层锈层,而后者形成的内层锈层难以稳定且易于出现均匀腐蚀的现象。     

COMPOSITION AND QUALITY OF THE GASOLINE OBTAINED FROM SYNGAS ON Cr2O3-ZnO/ZSM5 CATALYSTS

The kinetic equations for the formation of the lumps of the gasoline produced (C₅⁺ fraction), paraffins (C₅-C₈), xylenes (o-xylene, m-xylene and p-xylene) and aromatics (benzene, toluene, C₉-C₁₁) in the transformation of syngas on Cr₂O₃-ZnO/ZSM5 bifunctional catalyst have been established as a function of the concentration of both reactants (CO and H₂) and CO₂ byproduct. The effect of the operating conditions on the RON and on the molecular weight of the gasoline has been studied by experimentation in an integral fixed bed reactor in the range between 10 and 50atm and between 300 and 425°C. The octane index increases with Cr/Zn atomic ratio of the Cr₂O₃-ZnO metallic function, with Si/Al ratio of the HZSM5 zeolite, with space time and with the CO/H₂ molar ratio in the feed, in that order, whereas it passes through a maximum with pressure (at 20 atm) and with temperature (at 375°C). On the other hand, the molecular weight of the gasoline increases with the Cr/Zn atomic ratio, pressure, CO/H₂ molar ratio and space time, and decreases with the Si/Al ratio and temperature.