Arachidonic acid incorporation and turnover is decreased in sympathetically denervated rat heart

Heart sympathetic denervation can accompany Parkinson's disease, but the effect of this denervation on cardiac lipid-mediated signaling is unknown. To address this issue, rats were sympathetically denervated with 6-hydroxydopamine (6-OHDA, 50 mg/kg ip) and infused with 170 muCi/kg of either [1-(14)C]palmitic acid ([1-(14)C]16:0) or [1-(14)C]arachidonic acid ([1-(14)C]20:4 n-6), and kinetic parameters were assessed using a steady-state radiotracer model. Heart norepinephrine and epinephrine levels were decreased 82 and 85%, respectively, in denervated rats, and this correlated with a 34% reduction in weight gain in treated rats. Fatty acid tracer uptake was not significantly different between groups for either tracer, although the dilution coefficient lambda was increased in [1-(14)C]20:4 n-6-infused rats, which indicates that less 20:4 n-6 was recycled in denervated rats. In [1-(14)C]16:0-infused rats, incorporation rate and turnover values of 16:0 in stable lipid compartments were unchanged, which is indicative of preservation of beta-oxidation. In [1-(14)C]20:4 n-6-infused rats, there were dramatic reductions in incorporation rate (60-84%) and turnover value (56-85%) in denervated rats that were dependent upon the lipid compartment. In addition, phospholipase A(2) activity was reduced 40% in treated rats, which is consistent with the reduction observed in 20:4 n-6 turnover. These results demonstrate marked reductions in 20:4 n-6 incorporation rate and turnover in sympathetic denervated rats and thereby suggest an effect on lipid-mediated signal transduction mediated by a reduction in phospholipase A(2) activity.     

Distribution of Thy-1-like immunoreactivity in normal, sympathetically denervated and grafted mouse irides

The distribution of Thy-1-like immunoreactivity was studied in whole-mounts of adult mouse iris and intraocular iris grafts 4 days and 4 weeks postoperatively. After fixation in picric acid/paraformaldehyde, the irides were incubated with a polyclonal rabbit anti-mouse brain Thy-1 antibody. In the adult mouse iris, a dense network of thin bundles and individual fibres was seen on the dilator plate and in the sphincter. Fluorescence paucities, resembling Schwann cell nuclei, were frequently seen along the bundles. Numerous mast cells, stained specifically with the Thy-1 antibody, were scattered over the entire surface of the iris. The ciliary body contained several brightly fluorescent bundles, and some circularly running individual fibres. In 4-day iris grafts, the Thy-1-like immunoreactivity had disappeared, except in mast cells. After 4 weeks in oculo, a regular plexus of thin fibres had reappeared in the iris grafts. Sympathetic denervation of adult irides did not seem to affect the Thy-1 immunoreactivity in terms of either fluorescence intensity or fibre distribution. The present data suggest a distribution of the glycoprotein Thy-1 along nerve fibres in the iris.     

Distribution of Thy-1-like immunoreactivity in normal,sympathetically denervated and grafted mouse irides

Summary The distribution of Thy-1-like immunoreactivity was studied in whole-mounts of adult mouse iris and intraocular iris grafts 4 days and 4 weeks postoperatively. After fixation in picric acid/paraformaldehyde, the irides were incubated with a polyclonal rabbit anti-mouse brain Thy-1 antibody. In the adult mouse iris, a dense network of thin bundles and individual fibres was seen on the dilator plate and in the sphincter. Fluorescence paucities, resembling Schwann cell nuclei, were frequently seen along the bundles. Numerous mast cells, stained specifically with the Thy-1 antibody, were scattered over the entire surface of the iris. The ciliary body contained several brightly fluorescent bundles, and some circularly running individual fibres. In 4-day iris grafts, the Thy-1-like immunoreactivity had disappeared, except in mast cells. After 4 weeks in oculo, a regular plexus of thin fibres had reappeared in the iris grafts. Sympathetic denervation of adult irides did not seem to affect the Thy-1 immunoreactivity in terms of either fluorescence intensity or fibre distribution. The present data suggest a distribution of the glycoprotein Thy-1 along nerve fibres in the iris.     

Studies on cold pressor response of subjects who suffered from frostbite at high altitude

Seven lowlander soldiers who had 1st to 3rd degree of frostbite and 8 lowlander soldiers who recovered from high altitude pulmonary oedema were tested for cold pressor response at 260 m, 26°C, 6.8°C and 4,085 m, 26°C, 6.8°C. 8 lowlander soldiers (Control subjects) of comparable age group were tested for their cold pressor response at 260 m, 26°C and 3,300 m, 26°C. Another group of control subjects from the laboratory were also tested at 2,121 m, 26°C. There was a highly significant decrease in cold pressor response of the frostbite subjects at 260 m, 26°C and a very significant increase at 260 m, 6.8°C as compared to non-frostbite subjects. The subjects who recovered from high altitude pulmonary oedema did not show significant differences as compared with the control subjects. The results suggest certain basic physiological differences in regulation of supply of blood to the extremities under condition of general and local cold exposure.     

免疫复合物参与冻伤大鼠冻结-融化损伤的研究

目的：了解体液免疫在冻结性冻伤损伤病理生理过程中的作用,为冻结性冻伤的预防和治疗提供依据。方法：实验采用Wistar大鼠冻结性冻伤模型,在冻伤前及冻伤后4h、1d、3d和5d测量三种免疫球蛋白（IgG、IgA和IgM）、两种补体（C3和C4）和血清循环免疫复合物的含量;用免疫荧光标记技术检测骨骼肌中的组织免疫复合物含量;用免疫粘附法观察红细胞表面免疫复合物含量变化。结果：大鼠冻伤后血清IgG急剧下降,冻后4h下降至最低值。IgA在冻伤后1d达到最低。血清IgM浓度在冻伤后逐渐增高,冻后5d继续上升。血清循环免疫复合物浓度在冻后逐渐增高,冻后1d达峰值,为冻前的28、8倍（P〈0.01）。冻伤后1d大鼠骨骼肌开始出现免疫复合物沉积。红细胞表面免疫复合物含量明显高于冻前,冻后3d达到高峰（P〈0．01）。结论：研究结果表明,冻结性冻伤是一种免疫复合物相关性疾病,对此国内、外尚未见报道。     

Ventilatory response to sustained hypoxia in carotid body denervated rats

Hypoxia stimulates ventilation, but when it is sustained, a decline in the ventilatory response is seen. The mechanism responsible for this decline lies within the CNS, but still remains unknown. In this study, we attempted to elucidate the possible role of hypoxia-induced depression of respiratory neurons by comparing the ventilatory response to hypoxia in intact rats and those with denervated carotid bodies. A whole-body plethysmograph was used to measure tidal volume, frequency of breathing and minute ventilation (VE) in awake and anesthetized intact rats and rats after carotid body denervation during exposure to hypoxia (FIO2 0.1). Fifteen-minute hypoxia induced an initial increase of VE in intact rats (to 248% of control ventilation in awake and to 227% in anesthetized rats) followed by a consistent decline (to 207% and 196% of control VE, respectively). Rats with denervated carotid bodies responded with a smaller increase in VE (to 134% in awake and 114% in anesthetized animals), but without a secondary decline (145% and 129% of control VE in the 15th min of hypoxia). These results suggest that afferentation from the carotid bodies and/or the substantial increase in ventilation are crucial for the biphasicity of the ventilatory response to sustained hypoxia and that a central hypoxic depression cannot fully explain the secondary decline in VE.     

The response of Anisakis larvae to freezing

Anisakis third stage larvae utilize a variety of fish as intermediate hosts. Uncooked fish are rendered safe for human consumption by freezing. Larvae freeze by inoculative freezing from the surrounding medium but can survive freezing at temperatures down to -10 degrees C. This ability may be aided by the production of trehalose, which can act as a cryoprotectant, but does not involve recrystallization inhibition. Monitoring of fish freezing in commercial blast freezers and under conditions which simulate those of a domestic freezer, indicate that it can take a long time for all parts of the fish to reach a temperature that will kill the larvae. This, and the moderate freezing tolerance of larvae, emphasizes the need for fish to be frozen at a low enough temperature and for a sufficient time to ensure that fish are safe for consumption.     

Role of avoidance behavior in the response of Folsomia candida to above‐freezing cooling temperatures

Although avoidance behavior is thought to be one of the major strategies for arthropods to cope with cold, there is a general lack of data supporting its use. This study tested the suggestion that Collembola migrate deeper into the soil to avoid cooling temperatures during the transition from summer to winter. We released mature hemi‐edaphic Folsomia candida Willem (Collembola: Isotomidae) in large (5 301 cm³) and small (306 cm³) soil microcosms exposed to ambient temperatures ranging between 5 and 20 °C. Springtails released in the large microcosms for periods of 2, 3, and 4 weeks dispersed throughout the soil column but remained more abundant in the upper third layer of the soil column whether exposed to weekly decreasing temperatures or a constant ambient temperature of 20 °C. Both small (juvenile) and large (mature) springtails exposed to cooling were more abundant in the upper third than in the middle or lower third of the soil columns after 2, 3, or 4 weeks. Groups of F. candida released in small microcosms provided with a positive soil temperature gradient displayed the same vertical distribution, with 90% of individuals clustered in the top 4.5 cm of the 15‐cm column whether exposed to air temperatures of 5, 10, 15, or 20 °C. Results from the two types of microcosms demonstrated that the vertical distribution of springtails remains strongly biased to the upper soil layer regardless of the temperature of their environment and whether the temperature in the soil column was uniform or graduated. This supports our prediction that hemi‐edaphic species such as F. candida do not relocate to warmer deeper soil layers, but tend to remain in the surface soil layer where they can acclimate to the cooling temperature.