Effect of Lower Body Negative Pressure on the Heart Rate Variability

The R-R intervals were measured in 25 female volunteers aged 21–34 years after exposure to lower body negative pressure (LBNP). A number of advantages of information entropy (h) as an index of cardiovascular performance were revealed. With h used as a controlled variable, it was possible to ensure individual targeted changes in the functional state (FS) during LBNP. It was found that an individual exposure to LBNP caused regular changes in h and FS. Equations for targeted changes in human FS were derived.__________Translated from Fiziologiya Cheloveka, Vol. 31, No. 4, 2005, pp. 61–64.Original Russian Text Copyright © 2005 by Gerasimov, Ignatov.     

Mitochondrial Respiration in Drosophila Ovaries after a Full Cycle of Oogenesis under Simulated Microgravity

Studies of the function of the female reproductive system in zero gravity are urgent for the future exploration of deep space. Female reproductive cells, oocytes, are rich in mitochondria, which allow oocytes to produce embryos. The rate of cellular respiration was determined to assess the functional state of the mitochondrial apparatus in Drosophila melanogaster ovaries in which the full cycle of oogenesis took place under simulated microgravity. Since cellular respiration depends on the state of the cytoskeleton, the contents of the main cytoskeletal proteins were determined by Western blotting. To modulate the structure of the cytoskeleton, essential phospholipids were administered per os at a dosage of 500 mg/kg in medium. The results of this study show that after a full cycle of oogenesis under simulated microgravity, the rate of cellular respiration in the fruit fly ovaries increases, apparently due to complex II of the respiratory chain. At the same time, we did not find any changes in the area of oocytes or in the content of proteins in the respiratory chain. However, changes were found in the relative contents of proteins of the actin cytoskeleton. There were no changes of essential phospholipids and no increase in the rate of cellular respiration of the ovaries after exposure to simulated microgravity. However, in the control, the administration of essential phospholipids led to a decrease in the efficiency of oxygen consumption in the flies’ ovaries due to complexes IV–V.     

Negative Pressure Artificial Respiration: Use in Treatment of Respiratory Failure of the Newborn

Ninety-one infants with respiratory failure secondary to primary pulmonary disease and with a birth weight of 1000 g. or over have been managed in a negative-pressure respirator (Air-Shields) over a three-year period. Of these the failure in 87 was due to respiratory distress syndrome (RDS) and in four it resulted from massive meconium aspiration. Respiratory failure was indicated initially by arterial blood gas tensions (while breathing 100% O₂) of Po₂ <40 mm. Hg, pH <7.10 and Pco₂ >75 mm. Hg in the initial 47 cases; these levels were subsequently raised to Po₂ < 50 mm. Hg, pH <7.20 and Pco₂ >70 mm. Hg for the remainder. Fifty-four (59.3%) of the infants survived the use of the respirator and 47 of these (51.6%) were subsequently discharged alive and well. Mean time in hours to normalization of blood gas values while on the respirator were as follows: for Po₂, 10.5; for pH, 11.6; and for Pco₂, 22.6. These values indicate that the respirator is more efficient in promoting oxygenation (raising Po₂) than ventilation (lowering Pco₂). They also suggest that the observed acidosis is in large part secondary to the hypoxia rather than the result of co₂ retention. For the survivors the average time of total respirator dependency before commencement of weaning was 53.7 hours. All the infants were managed without the use of endotracheal tubes although the use of the respirator and/or administration of 100% oxygen were either continuous or intermittent for periods of up to two weeks. There have been no instances of so-called respirator lung disease in the survivors or in those who died, which suggests that the use of high oxygen concentration by itself is not the major factor in the pathogenesis of this complication.     

微重力及模拟微重力对植物生长的影响

重力对地球上生物的生长、发育、代谢及繁殖等具有重要影响.植物细胞的重力敏感性已被众多研究所证明,在空间微重力环境或地面模拟微重力环境下,植物表现特殊的微重力反应.微重力或模拟微重力会对植物体生长产生一系列的影响.综述微重力及模拟微重力对植物生长的影响,并对近期这一领域的研究进行了概括.     

Assessing Cerebral Autoregulation via Oscillatory Lower Body Negative Pressure and Projection Pursuit Regression

The process by which cerebral perfusion is maintained constant over a wide range of systemic pressures is known as “cerebral autoregulation.” Effective dampening of flow against pressure changes occurs over periods as short as ~15 sec and becomes progressively greater over longer time periods. Thus, slower changes in blood pressure are effectively blunted and faster changes or fluctuations pass through to cerebral blood flow relatively unaffected. The primary difficulty in characterizing the frequency dependence of cerebral autoregulation is the lack of prominent spontaneous fluctuations in arterial pressure around the frequencies of interest (less than ~0.07 Hz or ~15 sec). Oscillatory lower body negative pressure (OLBNP) can be employed to generate oscillations in central venous return that result in arterial pressure fluctuations at the frequency of OLBNP. Moreover, Projection Pursuit Regression (PPR) provides a nonparametric method to characterize nonlinear relations inherent in the system without a priori assumptions and reveals the characteristic non-linearity of cerebral autoregulation. OLBNP generates larger fluctuations in arterial pressure as the frequency of negative pressure oscillations become slower; however, fluctuations in cerebral blood flow become progressively lesser. Hence, the PPR shows an increasingly more prominent autoregulatory region at OLBNP frequencies of 0.05 Hz and below (20 sec cycles). The goal of this approach it to allow laboratory-based determination of the characteristic nonlinear relationship between pressure and cerebral flow and could provide unique insight to integrated cerebrovascular control as well as to physiological alterations underlying impaired cerebral autoregulation (e.g., after traumatic brain injury, stroke, etc.).     

Negative Pressure Artificial Respiration: Use in Treatment of Respiratory Distress Syndrome of the Newborn

Forty-five newborn infants in respiratory failure with respiratory distress syndrome were treated with intermittent negative pressure ventilation (INPV). There was a survival rate of 38% (17/45).All infants were initially treated without nasotracheal intubation. However, 24 of these developed a Paco₂ greater than 70 mm. Hg and were subsequently intubated. Intubation was followed by a decrease in the degree of hypercarbia in each instance and simultaneous increase in Pao₂.Complications encountered during ventilation were: emphysema (one patient), aspiration pneumonia (two patients), septicemia (two patients), misplaced nasotracheal tube (one patient).Follow-up of the 17 surviving patients for periods of four to 36 months disclosed two patients with post-intubation hoarseness. One infant initially had spastic quadriplegia with EEG abnormalities, both of which cleared by 5 months of age. In the remaining 14 infants, the results of physical, neurological and psychological examinations have remained within normal limits.     

Increase in the Strength of Synchronization between the Baroreflex Waves of Blood Pressure and Heart Rate Due to the Lower Body Negative Pressure Effect

Human Physiology - The lower body negative pressure (LBNP) effect has been studied in terms of phase synchronization between spontaneous oscillations of blood pressure (BP) and heart rate (HR). The...     

模拟微重力条件对植物幼苗生长的影响

与正常重力下生长的植物幼苗对照相比 ,在竖直平面内经回转器连续做 12 0h圆周回转的草莓和香石竹幼苗的生长状况发生如下变化 :(1)株高和叶片数有所增加 ;(2 )草莓的叶绿素含量降低 47.5 % ,香石竹叶绿素含量增加 4.3% ;(3)回转后两种幼苗的叶绿素的主要吸收峰位不变 ,而每个峰位吸收强度有所增加 ;(4 )两种幼苗的叶片快速荧光动力学参数 ,回转后除CA/F0 外 ,Fv/F0 、Fv/Fm 和T1/ 2 均有提高 ;(5 )对照和处理的叶绿体的两个光系统间的激发能分配有差异 ,但未影响处理的叶绿体的光合功能     

麦默通微创手术结合导管冲洗负压引流治疗乳房脓肿的临床效果观察

目的：探讨麦默通微创手术结合导管冲洗负压引流治疗乳房脓肿的临床效果。方法：选择2007年10月~2012年9月在我院治疗的180例乳房脓肿患者,全部在超声定位引导下行麦默通微创手术结合导管冲洗负压引流治疗,并观察其临床效果。结果：180例乳房脓肿患者完全恢复,住院天数6~10天,无1例并发乳瘘。常规病理结果均符合临床诊断。1~2年随访中,临床检查及乳腺B超检查均未发现复发迹象。结论：麦默通微创手术结合导管冲洗负压引流技术治疗乳房脓肿,切口隐蔽,操作简便,治疗彻底,可减少由于反复穿刺引起的感染,尤其适用于脓腔直径较大、位置较深、细针反复穿刺无效或复发者;术后换药冲洗简单易行,换药次数降低,明显减轻了患者痛苦;拔管后切口无需缝合,瘢痕小,并能维持乳房良好形态,提高了病人术后的生活质量,符合当今女性的审美要求。     

Growth and Development in Arabidopsis thaliana through an Entire Life Cycle under Simulated Microgravity Conditions on a Clinostat

Arabidopsis thaliana ecotype Columbia and Landsberg erecta were studied. Horizontal clinorotation affected little germination of seeds, growth and development of rosette leaves and roots during early vegetative growth stage, and the onset of the bolting of inflorescence axis and flower formation in reproductive growth stage, although it suppressed elongation of inflorescence axes. The clinorotation substantially reduced the numbers of siliques and seeds in Landsberg erecta, and completely inhibited seed production in Columbia. Seeds produced in Landsberg erecta on the clinostat were capable of germinating and developing rosette leaves normally on the ground. On the other hand, growth of pin-formed mutant (pin/pin) of Arabidopsis ecotype Enkheim, which has a unique structure of inflorescence axis with no flower and extremely low levels of auxin polar transport activity, was inhibited and the seedlings frequently died during vegetative stage on the clinostat. Seed formation and inflorescence growth of the seedlings with normal shape (pin/+ or +/+) were also suppressed on the clinostat. These results suggest that the growth and development of Arabidopsis, especially in reproductive growth stage, is suppressed under simulated microgravity conditions on a clinostat. To complete the life cycle probably seems to be quite difficult, although it is possible in some ecotypes. Received 18 June 1999/ Accepted in revised form 27 August 1999     

VSD负压引流技术结合游离植皮治疗大面积皮肤缺损的 临床疗效研究

目的：研究VSD负压引流技术结合游离植皮治疗大面积皮肤缺损临床疗效。方法：选择2012年4月至2013年10月入我院接受治疗的大面积皮肤缺损患者65例,将其随机分为观察组（35例）与对照组（30例）。观察组患者术前先采用VSD治疗,游离植皮术后继续给予VSD治疗;对照组患者采取打压植皮或传统打包加压治疗。观察和比较两组患者的皮片成活时间、皮片成活率、术后住院治疗时间、换药次数、疼痛评分及家属满意度。结果：观察组患者的皮片成活时间短于对照组、皮片成活率高于对照组、住院时间短于对照组,换药次数少于对照组,两组之间的差异具有统计学意义（P〈0．05）。此外,观察组患者的疼痛视觉模拟评分明显低于对照组,患者家属的满意度评分明显高于对照组,差异具有统计学意义（P〈0．05）。结论：相对于传统的打压植皮或传统打包加压的技术而言,VSD负压引流技术结合游离植皮在治疗大面积皮肤缺损的临床疗效更好,值得在临床上推广使用。     

失重/模拟失重对内皮细胞的影响实验研究进展

血管内皮作为血管壁的衬里,参与调节组织器官的局部血流和机体其它生理进程,在维持血管完整性和内环境稳定中发挥关键作用。内皮细胞对包括重力在内的机械应力刺激极为敏感,重力变化可对其形态和功能构成不同程度的影响。研究发现,失重/模拟失重通过诱导内皮细胞细胞骨架重塑、质膜caveolae重布,使其合成分泌血管活性物质、炎性介质的能力以及细胞表面粘附分子表达发生改变,这些分子变化又对内皮细胞的生长、增殖、凋亡、迁移和血管生成等具有精细调控作用。本文综合评述了失重/模拟失重对内皮细胞功能的影响,同时围绕文献报道中一些尚存争议的观点进行了适当讨论。     

模拟微重力效应对果蝇运动及睡眠的影响

本研究旨在探讨利用模拟微重力效应研究微重力对果蝇运动及睡眠影响的可行性.通过研制能够在模拟微重力环境下实时监测果蝇行为的随机定位仪,监测短时间(3 d)模拟微重力处理过程中,及长时间(10 d、20 d、30 d)处理后雄蝇运动和睡眠的变化;选取受影响较显著的短时间处理组,研究模拟微重力效应对生物钟核心基因(period (per)、timeless(tim)、clock (clk)、cycle (cyc)、cryptochrome (cry))、神经递质多巴胺(dopamine,DA)和5-羟色胺(5-hydroxytryptamine,5-HT)关键合成酶(多巴脱羧酶、酪氨酸羟化酶、色氨酸羟化酶)的编码基因ddc、pale和trh表达水平及DA和5-HT含量的影响.结果显示:短时间暴露下,雄蝇夜晚的运动量增加、单位时间运动次数增加、睡眠时间和次数减少、生物钟基因tim、clk、cyc、cry及神经递质合成相关编码基因ddc、pale和trh的表达水平均显著上升;长时间处理后对雄蝇运动和睡眠的影响较小.本研究认为利用模拟微重力效应研究微重力对果蝇运动及睡眠的影响是可行的,相关研究结果对航天医学研究具有借鉴意义.     

模拟微重力环境因子对人参细胞生长和人参皂苷含量的影响

与在正常重力条件培养下的对照相比,经回转器水平回转处理的人参细胞鲜重和干重均增加,人参皂苷含量提高10％左右。在去Ca2 培养基上生长的人参愈伤组织细胞,经回转器水平回转3周后,人参皂苷含量约为正常重力条件下培养细胞的2倍。另外,在试验范围内,如果培养基中起始钙离子浓度越高,则其培养的人参细胞中人参皂苷含量越低。     

植物细胞电融合技术在空间实验中的应用

细胞电融合是实用性很强的生物技术,然而在地面上由于重力沉降和热对流的影响,杂种细胞融合得率较低,使得这项技术在生产上的应用潜力难以发挥。大量的实验表明,空间微重力环境是实现细胞电融合的重要途径。今后有望利用空间微重力条件获得有价值的杂合细胞,培育作物新品种,为开展空间生物加工和空间制药提供良好基础。     

Effect of Change in Spindle Structure on Proliferation Inhibition of Osteosarcoma Cells and Osteoblast under Simulated Microgravity during Incubation in Rotating Bioreactor

In order to study the effect of microgravity on the proliferation of mammalian osteosarcoma cells and osteoblasts, the changes in cell proliferation, spindle structure, expression of MAD2 or BUB1, and effect of MAD2 or BUB1 on the inhibition of cell proliferation is investigated by keeping mammalian osteosarcoma cells and osteoblasts under simulated microgravity in a rotating wall vessel (2D-RWVS) bioreactor. Experimental results indicate that the effect of microgravity on proliferation inhibition, incidence of multipolar spindles, and expression of MAD2 or BUB1 increases with the extension of treatment time. And multipolar cells enter mitosis after MAD2 or BUB1 is knocked down, which leads to the decrease in DNA content, and decrease the accumulation of cells within multipolar spindles. It can therefore be concluded that simulated microgravity can alter the structure of spindle microtubules, and stimulate the formation of multipolar spindles together with multicentrosomes, which causes the overexpression of SAC proteins to block the abnormal cells in metaphase, thereby inhibiting cell proliferation. By clarifying the relationship between cell proliferation inhibition, spindle structure and SAC changes under simulated microgravity, the molecular mechanism and morphology basis of proliferation inhibition induced by microgravity is revealed, which will give experiment and theoretical evidence for the mechanism of space bone loss and some other space medicine problems.     

Pressure Effects on the Respiration of Vertically Migrating Decapod Crustacea

SYNOPSIS. The respiration of five species of North Atlanticdecapods was measured under conditions of pressure and temperaturewhich allow calculation of the metabolism of these animals inthe oceans. The species were: Systellaspis debilis, Acanthephyrapurpurea, Oplophorus spinosus, Parapandalus richardi, and Sergestescrassus. Results indicate a tendency for metabolism to remainrelatively constant with depth, the decrease due to lower temperatureoffset by an increase due to rising pressure. This contrastswith previous work with epipelagic euphausids which tended tohave greatly reduced metabolism with increasing depth. Perhapsthe metabolic rate of the decapods must remain high enough forthem to remain effective predators throughout their depth range,by day as well as night.     

Wear Behavior of Plasma Oxidized CoCrMo Alloy under Dry and Simulated Body Fluid Conditions

In this study, CoCrMo alloy was oxidized in plasma environment at the temperatures of 600 ℃ to 800 ℃ for 1 h to 5 h with 100% 02 gas and its tribological behavior was investigated. After the plasma oxidizing process, the compound and diffusion layers were formed on the surface. XRD results show that Cr203, a-Co and ε-Co phases diffracted from the modified layers after plasma oxidizing. The untreated and treated CoCrMo samples were subjected to wear tests both in dry and simulated body fluid conditions, and normal loads of 2 N and 10 N were used. For the sliding wear test, alumina balls were used as counter materials. It was observed that the wear resistance of CoCrMo alloy was increased after the plasma oxidizing process. The lowest wear rate was obtained from the samples that were oxidized at 800 ℃ for 5 h. It was detected that both wear environment and load have significant effects on the wear behavior of this alloy, and the wear resistance of oxidized CoCrMo alloy is higher when oxide-based counterface is used. The wear rates of both untreated and plasma oxidized samples increase under high loads.