Infrared-spectrometric determination of D2O in biological fluids

The determination of D₂O in biological fluids by means of infrared spectrometry was reinvestigated. When the temperature of a solution, containing D₂O in the range from natural abundance to 5 ml·1^–1 increases, its absorbance decreases and the wavenumber of maximum absorption shifts to a higher value. Both changes are linearly related to the change in temperature. Storage for 17 d in either glass or polyethylene tubes does not affect the D₂O concentration. Purification of biological fluids by vacuum-sublimation removes all substances which also absorb at the O-D vibration band and the recovery of D₂O from plasma and urine is complete. The partition ratio of D₂O between plasma water and red cell water equals unity, and the same holds for plasma water and urine water over a wide range of urine flows and osmolalities. The arterial and urinary disappearance curves of D₂O, measured over several days, both permit the calculation of the total amount of body water (V ^bw), the daily water turn-over (F) and the half-time of water in the body (t _1/2), but the data derived from arterial disappearance curves are more precise. In 16 male mongrel dogs (25–32 kg body mass) the following results were obtained:V ^bw=626±28 ml·kg^–1,F=12.0±3.2% andt _1/2=6.21±1.78 d.     

Effects of indomethacin on renal hemodynamics and on water and sodium excretion by the isolated dog kidney

Summary Blood-perfused isolated dog kidneys demonstrate steady increases in blood flow and in water and sodium excretion which could be attributed to the accumulation of renal prostaglandins in the perfusing blood. This hypothesis was tested by adding indomethacin, a potent inhibitor of prostaglandins synthesis, to the perfusing blood.Indomethacin completely prevented the vasodilation observed in control kidneys, without affecting glomerular filtration rate. Urine volume was not modified but sodium excretion was enhanced while the steady free water clearance increment observed in the control kidneys was depressed by indomethacin. The sum of sodium and free water clearances which, in the absence of antidiuretic hormone, constitutes an index of the part of the filtered load of solutes which escapes proximal tubular reabsorption, was not modified by indomethacin. Finally, indomethacin partially maintained the osmotic cortico-papillary gradient which was abolished after 2 hrs perfusion in control kidneys.These data suggest that prostaglandins accumulation in the blood is probably the major cause of the vasodilation taking place in isolated blood-perfused kidneys. This vasodilation does not account for decreased proximal reabsorption but partially explains the ADH-resistant diabetes insipidus developing in the isolated kidney. Moreover, indomethacin inhibits sodium reabsorption in the ascending limb of Henle's loop and increases water transport in the collecting duct.     

Morphometric study of the ductus arteriosus during human development

During prenatal life, the ductus arteriosus connects the left pulmonary artery and the descending aorta. Morphometric features (length, external diameter, volume) of the ductus arteriosus in 131 human fetuses (65 males, 66 females) were studied by means of anatomical, digital and statistical methods. Regression analysis was used to investigate the growth of the ductus arteriosus during gestation. The values of the length of the ductus arteriosus ranged from 3.95 mm for the 15 week gestational group to 12.20 mm for the 34th week of gestation. The length of the ductus arteriosus related to fetal age (x) increased according to the linear function y = -3.0726 + 0.4381x. The mean values of the diameter of the ductus arteriosus ranged from 1.34 to 3.49mm for the 15 and 34 week gestational groups, respectively. The growth of the ductus arteriosus diameter followed in accordance with the linear function y = 0.2072 + 0.0935x. The mean values of the ductus arteriosus volume ranged from 5.08 mm3 for the 15 week group to 117.30 mm3 of the 34 week gestation group. The volume growth increased according to the function y = 0.0007x3.3782. Positive correlation coefficients between arterial parameters and fetal age were statistically significant (P < or = 0.01) and reached the following values: r1 = 0.98 for Length, r2 = 0.90 for diameter and r3 = 0.94 for volume. Despite the increase in absolute diameter, the relative diameter of the ductus arteriosus (ductus arteriosus-to-aortic bulb diameter ratio) decreased from 0.80 to 0.48.     

Learning in escape/avoidance tasks in female rats does not vary with reproductive condition

To determine whether the development of novel stimulus-response associations by the mother during the periparturient period is attributable to a general facilitation of learning produced by the hormonal milieu during that period, learning ability under various reproductive conditions was assessed in two tasks unrelated to the periparturitional situation. The two tasks, selected because they equalized the various groups for motivation and performance variables, were acquisition of a water-maze escape (including two reversals), and acquisition and retention of an unsignalled shuttlebox shock avoidance. The groups tested in the water maze were a midpregnant group, an immediately prepartum group, and an immediately postpartum group. In the shuttlebox, the same conditions (different rats) were compared, together with a nonpregnant estrus condition, and a nonpregnant diestrus condition. The results of both experiments indicate that although learning occurred, the characteristics of acquisition and retention were not influenced by reproductive condition.     

不同禁水时间老龄大鼠下丘脑大细胞分泌神经元的免疫电镜观察

电镜观察了不同禁水时间老龄大鼠下丘脑视上核和室旁核分泌神经元，即加压素和催产素神经元及胶质细胞的超微结构变化，结果显示，禁水6与12h后，上述两核团中的分泌神经元胞体增大，胞质中粗面内质网（RER）排列紧密且规则，高尔基（Golgi)器的未成熟分泌颗粒及神经分泌颗粒增多，轴突内神经分泌颗粒少见，胶质细胞成份减少，突起回缩；相邻两神经元胞膜直接接触，质膜并列现象及突触增多，而在禁水24h后，神经元胞体内的神经分泌颗粒有减少，轴突中的神经分泌颗粒却增多并聚集成膨大区域，以上结果提示老龄大鼠视上核和室旁核的分泌神经元在禁水时其合成激素的功能是活跃的，而且催产素神经元的结构变化与加压素神经元结构变化是相似的，胶质细胞的结构变化为神经元质膜并列及突触的形式提供了有利条件。     

壳聚糖改性丝素合金膜的制备及其相关性质研究

以无毒氧化葡萄糖醛作交联剂 ,采用溶液共混交联法制备壳聚糖改性丝素合金膜。用 FTIR、DSC表征其结构 ,测定其等电点、力学性能、不同 p H条件下的溶胀率和对模型药物 5 - Fu的渗透性。结果表明 :改性丝素合金膜中丝素和壳聚糖分子间存在着强烈的氢键相互作用及良好的相容性。改性膜的等电点对应的 p H值是 5 .35 ,而丝素膜的等电点是 4 .5。改性膜的力学性能优于单组分膜 ,当壳聚糖含量为 4 0 %～ 6 0 %时 ,具有最大的抗张强度和拉伸率 ,分别为 71.4～ 72 .7MPa和 2 .96～ 3.82 %。改性丝素合金膜对 5 - Fu的渗透量与壳聚糖的含量和时间成正相关关系 ,渗透系数随 p H值增大 (5→ 9)先逐渐减小然后略有增大 ,在 p H=7时最小。     

冠状动脉血管直径测量方法的研究

心脏是人体生命活动的重要器官，能否正常工作主要是由心血管系和心传导系决定。冠状动脉是给心脏供血的唯一途径，心肌能否得到足够的营养、保持连续有节奏地运动，完全取决于冠状动脉是否能不断地供给其营养。冠状动脉直径的测量以及血管直径参数对于反映心脏功能和疾病的诊断具有重要意义。文中提出一种新型的、简便的血管直径测量方法，利用计算得到的血管直径，我们就可以判别心血管狭窄位置。     

Electrical self-stimulation of single and multiple loci: long term observations

Rats with chronic hypothalamic electrodes were allowed continuous access to self-stimulation, food and water in a 3 lever chamber. A prolonged burst of self-stimulation, with little food and water intake, was followed by bursts of activity on all 3 levers. A 12 hr light-dark cycle imposed a diurnal periodicity on all behaviors except in animals self-stimulating at the highest daily rates where self-stimulation was equal in dark and light. Under constant light conditions there was a 30 min daily shift in the peak periodicity of all behaviors. Increasing the current by 10 μA led to another continuous self-stimulation session for one day, with a subsequent decline and stabilization after three days. Reduction of the current to its original setting abolished self-stimulation for one day, but within 5 days rates returned to control values. Animals with electrodes in the septal, anterior and posterior hypothalamic areas allowed continuous access to self-stimulation on all 3 electrodes displayed similar behavior in that after a long initial self-stimulation session alternating on all 3 electrodes, periodic bursts of activity occurred on all three electrodes. The diurnal periodicity of self-stimulation seemed to be determined by the current intensity. The similarity of self-stimulation to normal drive mechanisms is discussed.     

Impaired temperature regulation in rats after anosmia induced peripherally or centrally

Bilateral olfactory bulbectomy or destruction of the olfactory epithelium of rats resulted in elevated body temperature in room temperature, and lowered water/food ratio in 30 degrees ambient temperature. The results suggest the involvement of the olfactory system in the thermoregulation.     

Rhythmic patterns of food and water intake in the dog: preliminary study (author's transl)]

The spontaneous rhythmic patterns of food and water intake in the dog during periods of 24 hr have been studied under three experimental conditions: natural light, continuous light and artificial light with day and night sequences. Under natural light there is a rhythmic pattern in the frequency of food intake and the amount of food consumed. During the night, periods of food consumption are numerous and the amount of food ingested is significant. During the day both the number of periods of food intake and the amount of food consumed is less. Similar results were obtained under continuous light. Under artificial light, with day and night sequences, there is a tendency to equalize the amount of food consumed through the 24 hr. This produced a displacement of frequency curves. In these three situations there seems to be an important relationship between the amount of food consumed and the time intervals following periods of food intake. Generally, similar results were obtained for water intake.