低浓度高渗盐水治疗重型颅脑损伤术后颅内高压的临床效果分析

目的:探讨低浓度的高渗盐水对重型颅脑损伤患者手术后颅内高压的治疗效果。方法:选取2014年8月至2017年8月本院收治的104例行去骨瓣减压术后出现颅内高压的重型颅脑损伤患者为研究对象,按照随机数表法将其分为实验组、观察组,每组各52例。在持续监测颅内压(ICP)的情况下,实验组、观察组分别给予233.3 m L的3%HS、29.9 m L的23.4%HS,比较两组治疗前后的ICP、平均动脉压(MAP)、中心静脉压(CVP)、血钠(Na+)、钾(K+)、渗透压、肌酐(Cr)、尿素氮(BUN)水平的变化及半年的预后情况。结果:两组治疗后30 min时ICP显著低于治疗前,而MAP明显高于治疗前(P 0.05);实验组治疗后240 min、300 min时ICP显著低于观察组,120 min、240 min、300 min、360 min时MAP均显著高于观察组(P 0.05);两组治疗前后的CVP比较差异无统计学意义(P0.05)。两组治疗后3 d、6 d血Na+均显著高于治疗前,治疗后1 d、3 d、6 d的渗透压均显著高于治疗前(P 0.05),两组治疗前后的血K+、Cr、BUN比较差异无统计学意义(P0.05);两组治疗前后的同期各血生化指标比较差异无统计学意义(P0.05)。实验组治疗半年后死亡6例(11.5%),预后不良14例(26.9%),预后良好32例(61.5%),观察组死亡8例(15.4%),预后不良20例(38.5%),预后良好24例(46.2%),两组比较差异无统计学意义(P0.05)。结论:3%和23.4%两种浓度的HS均能安全迅速降低重型颅脑损伤患者的ICP,且均有明显的扩容效果,但低浓度HS作用持续时间更长。     

20％吡拉西坦在颅内肿瘤术后颅内高压患者中应用效果观察

目的:探讨20％吡拉西坦注射液治疗颅内肿瘤术后高颅内压临床疗效和安全性.方法:选择2009年4月～2012年4月在我院神经外科住院治疗的136例颅内肿瘤术后高颅内压患者为研究对象,随机将其分为对照和实验组,对照组患者给予20％甘露醇快速静脉滴注治疗,而实验组患者则给予20％吡拉西坦快速静脉滴注治疗,比较两组患者临床疗效和不良反应发生情况.结果:实验组患者的治疗总有效率(95.59％)明显高于对照组的(85.29％),差异有显著性(P＜0.05),且对照组和实验组患者在不良反应发生率方面差异无显著性(P＞0.05).结论:20％吡拉西坦注射液治疗颅内肿瘤术后高颅内压临床疗效确切,降颅压疗效好,安全可靠,不良反应少.     

无创颅内压监测在创伤性急性弥漫性脑肿胀治疗中的临床应用研究

目的:探讨无创颅内压监测(Intracranial pressure,ICP)监测对救治创伤性急性弥漫性脑肿胀(Posttraumatic acute diffuse brains welling,PADBS)患者的辅助作用,为无创ICP检测的临床应用提供参考依据。方法:收集2011年1月至2016年1月我院神经外科收治的114例PADBS患者的临床资料进行回顾性分析,依据纳入与排除标准共取得病例组53例,对照组61例,分别给予采用无创颅内压监测和有创颅内压监测,根据患者资料进行组间比较及生存分析。结果:病例组与对照组不同分型颅内压检测值比较无统计学差异(P0.05);患者48h内进行大骨瓣开颅手术时间的生存分析,病例组中位手术时间为35.6个月,对照组中位DFS为33.5个月,两组患者检测进行手术时间的生存曲线无统计学差异(P0.05);有创ICP检测患者继发性出血率为3.2%,脑脊液感染病况为7.9%;两组患者预后情况差异并无统计学意义(P0.05)。无创ICP检测患者住院天数短于有创ICP检测患者(P0.05)。结论:无创ICP应用于PADBS治疗的临床价值与有创ICP相当,但无创ICP更便捷、创伤小,有利于对患者进行持续性检测。     

和肽素、正五聚蛋白3对稳定性冠心病患者冠脉狭窄程度的评估价值

该文评估了和肽素(CPP)、正五聚蛋白3(PTX3)、脑钠肽(BNP)、磷酸二酯酶9A(PDE9A)与稳定性冠心病患者冠脉狭窄程度的相关性。选取58例经冠脉造影检查证实为稳定性冠心病的患者,其中,冠脉狭窄≥70%组患者30例(I组),冠脉狭窄70%组患者28例(II组),两组病史情况无显著差异。采用ELISA法测定血浆CPP、PTX3、BNP、PDE9A浓度,运用二元Logistic回归分析CPP、PTX3、BNP、PDE9A与冠脉狭窄程度是否≥70%之间的相关性,通过ROC曲线分析CPP、PTX3、BNP、PDE9A对冠脉狭窄的预测价值。研究结果表明,I组患者血浆中CPP、PTX3的水平明显高于II组(P0.05),而I、II两组的BNP、PDE9A血浆水平无统计学差异(P0.05)。二元Logistic回归分析发现,血浆中CPP、PTX3的水平高低与冠脉狭窄程度是否达到70%具有相关性(P0.05)。ROC曲线分析表明,CPP(1.07 ng/m L)预测冠脉狭窄≥70%的敏感度为63.3%,特异性为64.3%;PTX3(20.56ng/m L)预测冠脉狭窄≥70%的敏感度为63.3%,特异性为67.9%。综上可得,血浆中CPP、PTX3的水平对稳定性冠心病患者冠脉狭窄是否≥70%具有一定评估价值;而血浆中PDE9A、BNP的水平与稳定性冠心病患者冠脉狭窄是否≥70%是否具有评估价值依据不足。     

呼气末正压通气对骨肿瘤患者呼吸功能及血流动力学的影响

目的:探讨呼气末正压通气(Positive end expiratory pressure,PEEP)对全麻状态下行骨肿瘤手术的患者血流动力学的影响。方法:选取2013年1月至2014年1月在我院接受手术治疗的骨肿瘤患者30例,随机分成对照组(PEEP 0 cm H2O,n=15)和研究组(PEEP 8 cm H2O,n=15)。所有患者行常规麻醉诱导后机械通气。观察并比较两组患者不同时间点的气道峰压(Ppeak)、气道平台压(Ppla)、Pa O2和Pa CO2等呼吸功能指标,以及心率(HR)、平均动脉压(MAP)和中心静脉压(CVP)等血流动力学指标的变化。结果:两组组内比较,Pa O2值下降(P0.05);研究组Ppeak和Ppla显著增加(P0.01),对照组无显著差异(P0.05)。与对照组相比较,研究组患者相同时间点的Pa O2值、Ppeak及Ppla明显增加,差异具有统计学意义(P0.05)。两组组内比较,HR、MAP及CVP值的差异均无统计学意义(P0.05);与对照组相比较,研究组患者相同时间点的CVP值上升,HR和MAP值下降,但差异无统计学意义(P0.05)。结论:PEEP通气对全麻下骨肿瘤手术患者的呼吸功能具有改善作用,且加用PEEP对患者血流动力学参数的影响不明显,可在临床推广应用。     

神经电生理在颅内动脉瘤夹闭术中联合颅内压、脑灌注压监测的应用效果研究

摘要 目的：探讨神经电生理在颅内动脉瘤夹闭术中联合颅内压（ICP）、脑灌注压（CPP）监测的应用效果。方法：选取2018年12月～2020年1月我院进行开颅手术治疗的颅内动脉瘤患者60例,采用简单随机化分组方法分为两组,每组30例。对照组实施颅内动脉瘤夹闭手术,观察组在对照组基础上,术中应用神经电生理、ICP、CPP监测。比较两组动脉瘤夹闭情况,术后第1 d新发神经功能缺损情况,术前、术后1 d、术后3个月格拉斯哥昏迷评分（GCS）、美国国立卫生研究院脑卒中量表（NIHSS）评分及术后3个月预后优良率。结果：两组动脉瘤均完全夹闭,观察组术后第1 d新发神经功能缺损率6.67%（2/30）低于对照组的26.67%（8/30）（P＜0.05）;术后1 d观察组GCS评分高于对照组,NIHSS评分低于对照组（P＜0.05）;排除失访病例后,观察组术后3个月GOS分级、mRS分级优良率分别为88.89%、88.89%,与对照组的88.00%、84.00%比较,差异无统计学意义（P＞0.05）。结论：采用神经电生理联合ICP、CPP监测,能够实时掌握颅内动脉瘤夹闭术患者脑组织血流情况,根据监测结果及时采取相应干预措施,可预防不可逆的脑缺血改变,改善术后早期患者意识状态,减少术后早期神经功能缺损的发生。     

PICCO在老年髋关节手术麻醉及血流动力学优化中的应用

目的:探讨脉搏指示持续心输出量(pulse induced contour crdic output,PICCO)技术在老年髋关节手术麻醉及血流动力学优化中的临床应用。方法:将106例老年髋关节手术患者随机分成2组,每组各53例。常规组放置中心静脉导管和动脉导管,PICCO组放置PICCO,检测平均动脉压(mean arterial pressure,MAP)、中心静脉压(central venous pressure,CVP)、心率(heart rate,HR)、心指数(cardiac index,CI)、血管外肺水指数(extravascular lung water index,ELWI)、胸腔内血容量指数(intrathoracic blood volume index,ITBI)及肺血管通透性指数(pulmonary vascular permeability index,PVPI)等血流动力学参数。记录PICCO组术中各指标的变化,比较分析两组术后前3天液体输入量,术后并发症发生情况。结果:与T0时点比较,PICCO组T1时点的MAP、CVP、CI、ITBI明显降低,HR明显升高(P0.05);T2时点MAP、CVP、CI较T1明显升高,HR明显下降(P0.05);PICCO组T2时刻各血流动力学指标均明显优于常规组(P0.05)。PICCO组术后前3天的液体入量明显少于常规组(P0.05);ELWI与PVPI、ITBI、液体入量均呈高度正相关(P0.05)。且PICCO组术后肺部感染及心血管并发症的发生率也较常规组明显降低(P0.05)。结论:PICCO监测可准确反映血流动力学状态参数,指导临床麻醉和围术期液体管理,减少术中术后不良并发症,改善患者预后。     

CT灌注成像技术用于重型颅脑损伤患者脑室型颅内压探头植入的临床价值评估

目的:探讨CT灌注成像技术用于重型颅脑损伤患者脑室型颅内压(Intracranial Pressure, ICP)探头植入的临床价值。方法:选取60例重型颅脑损伤患者,均行患侧开颅去骨瓣减压和颅内压监测探头置入术。其中,行普通型颅内压监测探头置入术28例,脑室型颅内压监测探头置入术32例。比较两组术后甘露醇应用剂量和应用时间,术后局部脑血流参数区域脑血流量(regional Cerebral Blood Flow, r CBF)、相对脑血容量(relative Cerebral Blood Volume, r CBV)、平均通过时间(Mean Transit Time, MTT)、对比剂达峰时间(time to peak, TTP)恢复情况。结果:脑室型颅内压监测组患者术后应用甘露醇的剂量和天数较普通颅内压监测组明显缩短(P0.05),术后3个月随访提示脑室型ICP监测组预后良好比例较普通型ICP组显著增加(P0.05)。并且螺旋CT灌注成像结果提示脑室型颅内压监测组患者术后局部脑血流参数r CBF、r CBV、MTT、TTP恢复情况明显优于普通型颅内压监测组(P0.05)。结论:重型颅脑损伤患者应用脑室型颅内监测探头改变了脱水剂在临床应用中的治疗模式,通过螺旋CT灌注成像检测患者损伤部位的r CBF、r CBV、MTT和TTP可评估脑损伤的程度以及预后,对重型颅脑损伤的临床治疗和改善患者预后具有重要意义。     

允许性高碳酸血症在腹腔镜直肠癌手术中的应用及对循环的影响

目的:研究允许性高碳酸血症在腹腔镜直肠癌手术中的应用效果、最佳适宜范围及对患者循环功能的影响。方法:选取沧州市中心医院拟择期行腹腔镜直肠癌手术的患者90例,随机分为试验1组、2组和对照组3组,每组30例。试验1组血二氧化碳分压(partial pressure of carbon dioxide,PaCO_2)维持在56～65 mm Hg,试验2组PaCO_2维持在46～55 mm Hg,对照组PaCO_2维持在35～45 mm Hg。观察并比较三组患者气腹时间、机械通气时间、手术时间、拔管时间、苏醒时间,气腹前10 min(T_1)、气腹后1 h(T_2)、气腹后2 h(T_3)、放气后15 min(T_4)时间点的平均动脉压、心率、气道峰压,计算动态肺顺应性、氧合指数,记录皮下气肿、呕吐、烦躁及术后认知功能障碍等并发症的发生情况。结果:三组患者手术时间、气腹时间、机械通气时间、拔管时间和苏醒时间比较差异无统计学意义(P0.05)。与对照组相比,试验组T_2、T_3时心率(heart rate,HR)、血氧分压(partial pressure of oxygen,PaO_2)、肺动态顺应性(lung dynamic compliance,Cdyn)均明显升高,P_(max)明显下降(P0.05);与T_1相比,试验组T_2、T_3时HR、气道峰压(Pmax)、PaO_2均升高,Cdyn下降(P0.05);与试验2组比较,试验1组HR、P_(max)明显更低,PaO_2、Cdyn明显更高(P0.05),但三组氧合指数(oxy-genation Index,OI)比较差异无统计学意义(P0.05)。与对照组相比,试验组T_2、T_3时动脉血二氧化碳分压(partial pressure of car-bon dioxide,PaCO_2)、Qs/Qt均升高,氢离子浓度指数(hydrogen ion concentration,pH)、平均动脉压(mean arterial pressure,MAP)下降;与T_1相比,试验组T_2、T_3时PaCO_2、Qs/Qt均升高,pH、MAP下降;与试验2组比较,试验1组PaCO_2、PaCO_2明显更低,pH明显更高(P0.05),但三组MAP比较差异无统计学意义(P0.05)。手术开始30 min和1 h,试验组中心静脉压(central venous pressure,CVP)、心输出量(cardiac output,CO)以及心脏指数(cardiac index,CI)较对照组更低,而试验1组较试验2组明显更低(P0.05)。三组并发症的改善情况比较差异无统计学意义(x~2=0.1973,P=0.9954)。治疗后,试验组MMSE评分较治疗前明显降低,且试验组明显高于对照组,而试验1组又显著高于试验2组(P0.05)。结论:允许性高碳酸血症在长时间腹腔镜直肠癌手术中在保障氧合同时降低气道压改善肺的顺应性,可一定程度上减少术后认知功能障碍的发生,有一定的脑保护作用。     

重度心力衰竭患者血清RDW、CPP、NT-proANP的临床意义及其与预后相关性分析

摘要 目的：探讨重度心力衰竭患者血清红细胞分布宽度（RDW）、和肽素（CPP）、氨基末端 A 型利钠肽（NT-proANP）的临床意义及其与预后相关性。方法：选取我院2020年1月与到2022年12月收治的98例心力衰竭患者作为研究对象,将所有患者应用Killip分级进行分组,Ⅰ级16例,Ⅱ级23例,Ⅲ级例21,Ⅳ级38例,并选取同期来我院体检的50名健康志愿者作为对照组,对比五组患者血清RDW、CPP、NT-proANP表达水平,分析RDW、CPP、NT-proANP与重度心力衰竭的相关性。随后将Ⅲ级与Ⅳ级重度心力衰竭的59例患者依照其预后情况分为死亡组（n=21）和存活组（n=38）,对比两组患者临床一般情况与血清RDW、CPP、NT-proANP表达水平,并分析血清RDW、CPP、NT-proANP对重度心力衰竭的预后预测价值。结果：五组受检者血清RDW、CPP、NT-proANP水平对比差异显著,Ⅳ级组明显高于Ⅲ级、Ⅱ级、Ⅰ级和对照组（P＜0.05）;Spearman相关分析结果显示：血清RDW、CPP、NT-proANP与重度心力衰竭呈正相关（P＜0.05）;曲线下面积(AUC)从依次为RDW (0.688)、CPP（0.667）、NT-proANP（0.656）、三者联合（0.671）。RDW诊断灵敏度为67.61 %,特异度为66.85 %,CPP诊断灵敏度为60.03 %,特异度为67.53%,NT-proANP诊断灵敏度为61.24 %,特异度为66.53 %,三者联合诊断灵敏度为74.58 %,特异度为86.32 %;存活组与死亡组患者Killip分级、合并陈旧性心肌梗死、RDW、CPP、NT-proANP水平对比差异显著（P＜0.05）;logistic回归分析结果表明：RDW、CPP、NT-proANP为重度心力衰竭预后的独立预测指标（P＜0.05）。结论：血清RDW、CPP、NT-proANP与重度心力衰竭具有明显相关性,其对于重度心力衰竭的诊断临界值分别为17.58 %、1772.62 pg/mL、1.12 nmol/mL。同时三者为重度心力衰竭预后不良的独立影响因素。     

Hypertonic Saline for Brain Relaxation and Intracranial Pressure in Patients Undergoing Neurosurgical Procedures: A Meta-Analysis of Randomized Controlled Trials

Background

A wealth of evidence from randomized controlled trials (RCTs) has indicated that hypertonic saline (HS) is at least as effective as, if not better than, mannitol in the treatment of increased intracranial pressure(ICP). However, there is little known about the effects of HS in patients during neurosurgery. Thus, this meta-analysis was performed to compare the intraoperative effects of HS with mannitol in patients undergoing craniotomy.

Methods

According to the research strategy, we searched PUBMED, EMBASE and Cochrane Central Register of Controlled Trials. Other sources such as the internet-based clinical trial registries and conference proceedings were also searched. After literature searching, two investigators independently performed literature screening, quality assessment of the included trials and data extraction. The outcomes included intraoperative brain relaxation, intraoperative ICP, total volume of fluid required, diuresis, hemodynamic parameters, electrolyte level, mortality or dependence and adverse events.

Results

Seven RCTs with 468 participants were included. The quality of the included trials was acceptable. HS could significantly increase the odds of satisfactory intraoperative brain relaxation (OR: 2.25, 95% CI: 1.32–3.81; P = 0.003) and decrease the mean difference (MD) of maximal ICP (MD: −2.51mmHg, 95% CI: −3.39—1.93mmHg; P<0.00001) in comparison with mannitol with no significant heterogeneity among the study results. Compared with HS, mannitol had a more prominent diuretic effect. And patients treated with HS had significantly higher serum sodium than mannitol-treated patients.

Conclusions

Considering that robust outcome measures are absent because brain relaxation and ICP can be influenced by several factors except for the hyperosmotic agents, the results of present meta-analysis should be interpreted with cautions. Well-designed RCTs in the future are needed to further test the present results, identify the impact of HS on the clinically relevant outcomes and explore the potential mechanisms of HS.     

NKCC activity restores muscle water during hyperosmotic challenge independent of insulin,ERK, and p38 MAPK

In isosmotic conditions, insulin stimulation of PI 3-K/Akt and p38 MAPK pathways in skeletal muscle inhibits Na(+)-K(+)-2Cl(-) cotransporter (NKCC) activity induced by the ERK1,2 MAPK pathway. Whether these signaling cascades contribute to NKCC regulation during osmotic challenge is unknown. Increasing osmolarity by 20 mosM with either glucose or mannitol induced NKCC-mediated (86)Rb uptake and water transport into rat soleus and plantaris skeletal muscle in vitro. This NKCC activity restored intracellular water. In contrast to mannitol, hyperosmolar glucose increased ERK1,2 and p38 MAPK phosphorylation. Glucose, but not mannitol, impaired insulin-stimulated phosphorylation of Akt and p38 MAPK in the plantaris and soleus muscles, respectively. Hyperosmolarity-induced NKCC activation was insensitive to insulin action and pharmacological inhibition of ERK1,2 and p38 MAPK pathways. Paradoxically, cAMP-producing agents, which stimulate NKCC activity in isosmotic conditions, suppressed hyperosmolar glucose- and mannitol-induced NKCC activity and prevented restoration of muscle cell volume in hyperosmotic media. These results indicate that NKCC activity helps restore muscle cell volume during hyperglycemia. Moreover, hyperosmolarity activates NKCC regulatory pathways that are insensitive to insulin inhibition.     

Pathophysiological basis of therapy of raised intracranial pressure in acute liver failure

In acute liver failure (ALF) patients that have raised increased intracranial pressure (ICP), mortality remains unacceptably high. There has been an explosion in the knowledge about the pathophysiological basis of raised ICP but treatment modalities are limited. Current therapy is aimed at reducing the circulating ammonia levels and attempts to reduce brain swelling which are only moderately effective. More recently, cerebral hyperemia has been suggested as being of major importance in the pathogenesis of increased ICP providing a new look at interventions such as hyperventilation, N-acetylcysteine, thiopentone sodium and propofol. More recently studies have focused upon the role of systemic inflammatory response in the pathogenesis of increased ICP and support the use of antibiotics prophylactically. The application of moderate hypothermia to treat uncontrolled intracranial hypertension seems promising and its exact place will be decided in a large trial being planned in USA and Europe. Early data from studies in an animal model suggests that albumin dialysis is a promising new tool to treat intracranial hypertension in patients with ALF. The recent advance in our understanding of the pathophysiological basis of intracranial hypertension has provided the platform for the discovery of new treatments.     

A mathematical model of intracranial pressure dynamics for brain hypothermia treatment

Brain hypothermia treatment is used as a neuroprotectant to decompress the elevated intracranial pressure (ICP) in acute neuropatients. However, a quantitative relationship between decompression and brain hypothermia is still unclear, this makes medical treatment difficult and ineffective. The objective of this paper is to develop a general mathematical model integrating hemodynamics and biothermal dynamics to enable a quantitative prediction of transient responses of elevated ICP to ambient cooling temperature. The model consists of a lumped-parameter compartmental representation of the body, and is based on two mechanisms of temperature dependence encountered in hypothermia, i.e. the van't Hoff's effect of metabolism and the Arrhenius' effect of capillary filtration. Model parameters are taken from the literature. The model is verified by comparing the simulation results to population-averaged data and clinical evidence of brain hypothermia treatment. It is possible to assign special model inputs to mimic clinical maneuvers, and to adjust model parameters to simulate pathophysiological states of intracranial hypertension. Characteristics of elevated ICP are quantitatively estimated by using linear approximation of step response with respect to ambient cooling temperature. Gain of about 4.9 mmHg degrees C(-1), dead time of about 1.0 h and a time constant of about 9.8h are estimated for the hypothermic decompression. Based on the estimated characteristics, a feedback control of elevated ICP is introduced in a simulated intracranial hypertension of vasogenic brain edema. Simulation results suggest the possibility of an automatic control of the elevated ICP in brain hypothermia treatment.     

Hypertonic Saline Reduces Vascular Leakage in a Mouse Model of Severe Dengue

Dengue (DEN) is a mosquito-borne viral disease and represents a serious public health threat and an economical burden throughout the tropics. Dengue clinical manifestations range from mild acute febrile illness to severe DEN hemorrhagic fever/DEN shock syndrome (DHF/DSS). Currently, resuscitation with large volumes of isotonic fluid remains the gold standard of care for DEN patients who develop vascular leakage and shock. Here, we investigated the ability of small volume of hypertonic saline (HTS) suspensions to control vascular permeability in a mouse model of severe DEN associated with vascular leakage. Several HTS treatment regimens were considered and our results indicated that a single bolus of 7.5% NaCl at 4 mL per kg of body weight administered at the onset of detectable vascular leakage rapidly and significantly reduced vascular leak for several days after injection. This transient reduction of vascular leakage correlated with reduced intestine and liver damage with restoration of the hepatic functions, and resulted in delayed death of the infected animals. Mechanistically, we showed that HTS did not directly impact on the viral titers but resulted in lower immune cells counts and decreased systemic levels of soluble mediators involved in vascular permeability. In addition, we demonstrated that neutrophils do not play a critical role in DEN-associated vascular leakage and that the therapeutic effect of HTS is not mediated by its impact on the neutrophil counts. Together our data indicate that HTS treatment can transiently but rapidly reduce dengue-associated vascular leakage, and support the findings of a recent clinical trial which evaluated the efficacy of a hypertonic suspension to impact on vascular permeability in DSS children.     

Turgor-sensitive sucrose and amino acid transport into developing seeds of Pisum sativum. Effect of a high sucrose or mannitol concentration in experiments with empty ovules

Sugar and amino acid transport into empty ovules of Pisum sativum L. cv. Marzia was examined. In fruits containing 4–6 developing seeds, the embryo was removed from four ovules. After this surgical treatment, each empty seed coat was filled with a solution (pH 5.5) containing a low (0, 50 or 200 m M ), medium (350, 400 or 500 m M ) or high (0.7 or 1 M ) concentration of sucrose and/or mannitol. In pulse-labelling experiments with sucrose and α-aminoisobutyric acid (AIB), transport of sucrose and AIB into an empty ovule filled with a solution containing a high sucrose concentration was the same as transport into an ovule filled with a mannitol solution of similar osmolarity, demonstrating that a high sucrose concentration in the seed coat apoplast affects phloem transport of sucrose and AIB into the seed coat only by the osmotic effect. The osmolarity of a given solution filling the seed coat cavity appeared to be important for phloem transport of sucrose and AIB into empty ovules.
In our experiments, 350 m M appeared to be the optimal concentration for sucrose and AIB transport into the cavity within an empty ovule, giving results comparable with transport into intact ovules. A lower osmolarity of the solution induced less transport. Very high sucrose or mannitol concentrations caused a strong inhibition of sucrose and AIB unloading from the seed coat, so that transport into the empty ovules was inhibited. A low (strongly negative) but not too low osmotic potential of the solution in the seed coat apoplast seems necessary to maintain a normal rate of phloem transport into developing seeds. Apparently, the "sink strength" of developing seeds is turgor-sensitive.     

Effects of moderate physical training on blood pressure variability and hemodynamic pattern in mildly hypertensive subjects.

The objective of our study was to compare the cardiovascular effects of moderate exercise training in healthy young (NTS, n=18, 22.9+/-0.44 years) and in hypertensive human subjects (HTS, n=30, 23+/-1.1). The VO(2max) did not significantly differ between groups. HTS of systolic blood pressure (SBP) 148+/-3.6 mmHg and diastolic blood pressure(DBP) 88+/-2.2 mmHg, and NTS of SBP: 128.8 +/- 4 mmHg and DBP: 72 +/- 2.9 mmHg were submitted to moderate dynamic exercise training, at about 50% VO(2max) 3 times per week for one hour, over 3 months. VO(2max) was measured by Astrand's test. Arterial blood pressure was measured with Finapres technique, the stroke volume, cardiac output and arm blood flow were assessed by impedance reography. Variability of SBP and pulse interval values (PI) were estimated by computing the variance and power spectra according to FFT algorithm. After training period significant improvements in VO(2max) were observed in NTS- by 1.92 +/-0.76 and in HTS by 3+/-0.68 ml/kg/min). In HTS significantly decreased: SBP by 19 +/-2.9 mmHg, in DBP by 10.7+/-2 mmHg total peripheral resistance (TPR) by 0.28 +/-0.05 TPR units. The pretraining value of low frequency component power spectra SBP (LF(SPB)) was significantly greater in HTS, compared to NTS. PI variance was lower in HTS, compared to NTS. After physical training, in HTS PI variance increased suggesting a decrease in frequency modulated sympathetic activity and increase in vagal modulation of heart rate in mild hypertension. A major finding of the study is the significant decrease of resting low frequency component SBP power spectrum after training in HTS. The value of LF(SPB) in trained hypertensive subjects normalized to the resting level of LF(SPB) in NTS. Our findings suggest that antihypertensive hemodynamic effects of moderate dynamic physical training are associated with readjustment of the autonomic cardiovascular control system.