The Effect of Intermittent Noise on Cardiovascular Functioning During Vigilance Task Performance

This study was designed to investigate the effect of presentations of intermittent noise differing in predictability on cardiovascular functioning during task performance. Under a quiet condition and three conditions of intermittent noise, measures of blood pressure, heart rate (interbeat interval), and heart rate variability (variance, successive difference mean square, and the 0.1 Hz component of sinus arrhythmia) were obtained while subjects were occupied with a 55-min vigilance task. The results indicated that intermittent noise significantly increased diastolic and mean blood pressure. In addition, 0.1 Hz measures differed between the group working under quiet conditions and the groups working under noise. Although heart rate increased in all groups during the task, it increased significantly more in groups receiving unpredictable noise bursts. For the variables that were significantly affected by the noise presentations there was no evidence of response habituation over the task period. The results are discussed in relation to the effort required to maintain performance levels during noise, and attention is drawn to the implications of the present findings for cardiovascular health under conditions of chronic intermittent noise.     

Novel HMBS founder mutation and significant intronic polymorphism in Spanish patients with acute intermittent porphyria

Acute intermittent porphyria (AIP) is an autosomal dominant disorder of heme biosynthesis, caused by a partial deficiency of hydroxymethylbilane synthase (HMBS). Knowledge of the nature of the HMBS mutations causing AIP in Spanish families is very limited. Here we report a novel 669_698del of the HMBS gene in twenty‐two individuals from five independent Spanish AIP families, settled in Murcia (southeastern region of Spain). All mutation carriers shared a common disease associated haplotype indicating an ancestral founder effect. Identification of the 669_698del founder mutation allowed rapid and simple molecular diagnosis of AIP in families from this region in Spain. In addition, 771 + 58C>T in intron 12 on the non‐669_698del allele was identified in six AIP patients, which promoted homozygous AIP misdiagnosis.     

An investigation of biological response induced by intermittent noise (trapezoidal noise)

Summary Audiometrically normal, male students (aged 18–22, 6–12 persons) were exposed to intermittent and steady-state noise (480 min, pink noise), after which Temporary Threshold Shift (TTS) and urinary 17 OHCS levels were measured. The rise-decay time of an exposed noise (trapezoidal noise, cf. Fig. 1) was ca. 500 ms and its duration was 6.5 s. Peak levels of intermittent noises were 80 dB (A) and 90 dB (A). Exposure conditions examined were (1) control; (2) peak level of 90 dB (A) with an exposure time of 2 min; (3) peak 90 dB (A), exposure 1 min; (4) peak 90 dB (A), exposure 24 s; (5) peak 90 dB (A), exposure 12 s; (6) Peak 80 dB (A), exposure 2 min; (7) peak 80 dB (A), exposure 1 min; (8) peak 80 dB (A), exposure 24 s; (9) peak 80 dB (A), exposure 12 s; (10) steady-state noise of 90 dB (A); (11) steady-state noise of 80 dB (A). The coefficient of regression of TTS growth induced by exposures 1, 2, 3, 6, 7, or 8 did not have significance, but that by exposure 4, 5, 9, 10, or 11 was significant. When the TTS₂ of the noise exposure for 480 min was studied by the on-fraction rule based on these regression equations, the TTS of exposures 4 and 5 (on-fraction 25%, 50%) was found to be same as 29% and 40% of the TTS of exposure 10. There was a significant difference between the 8-h urinary 17 OHCS levels induced by exposures 6 and 7 and those induced by control conditions. However, there was no significant difference between urinary 17 OHCS levels induced by other noise exposures (8, 9, and 11) and that induced by control conditions. The coefficient of regression between the 8-h urinary 17 OHCS levels and the logarithm of the on-fraction was significant.     

Impact of heat exposure and moderate,intermittent exercise on cytolytic cells

This study examined the impact of heat exposure and moderate, intermittent exercise on the CD16⁺ and CD56⁺ cell counts and cytolytic activity. Eleven healthy male subjects [mean (SD): age = 27.1(3.0) years, peak oxygen intake, VO_2maxO_{2 peak} = 47.6 (6.2) ml · kg^–1 · min^–1] were assigned to each of four different experimental conditions according to a randomized-block design. While in a climatic chamber maintained at a comfortable temperature (23°C) or heated (40°C, 30% relative humidity, r.h.), subjects performed either two 30-min bouts of cycle-ergometer exercise at 50% VO_2maxO_{2 peak} (separated by a 45-min recovery interval), or remained seated for 3 h. Blood samples were analyzed for CD16⁺ and CD56⁺ cell counts, cytolytic activity and the concentrations of various exercise stress hormones (norepinephrine, epinephrine and cortisol). Heat exposure alone had no significant effect on cytolytic cells. The (CD16⁺ and CD56⁺) cell count increased significantly (P < 0.0001) during each exercise bout under both environmental conditions, but returned to baseline levels 15–45 min following each exercise bout. Total cytolytic activity (determined by a standard ⁵¹Cr release assay using K562 cells) followed a similar pattern, but cytolytic activity per CD16⁺ or CD56⁺ cell was not significantly modified by exercise. Our findings show a strong association between hemodynamic factors and recruitment of cytolytic cells into the peripheral circulation. Alterations in cytolytic activity of the whole blood during and following moderate exercise seem to be the result of changes in CD16⁺ and CD56⁺ cell counts.     

Physiological response in the forearm during and after isometric intermittent handgrip

Summary The aim of the present paper was to study the development of fatigue during isometric intermittent handgrip exercise. Using a handgrip dynamometer, four combinations of contraction-relaxation periods were studied (10+10, 10+5, 10+2s and continuous contraction) at three contraction intensities (10, 25 and 40% maximum voluntary contraction, MVC). Local blood flow (BF) in the forearm (venous occlusion plethysmography) was followed before, during and after the exercise period. Electromyography (EMG) (frequency analysis) and the perceived effort and pain were recorded during the exercise period. Forearm BF is insufficient even at isometric contractions of low intensity (10% MVC). The results indicate that vasodilating metabolites play an active role for BF in low-intensity isometric contractions. It is shown that maximal BF in the forearm during relaxation periods (25–30 ml min^–1 · 100 ml^–1) is already reached at 25% MVC. Only intermittent exercise at 10% MVC and (10+5s) and (10+10s) at 25% MVC was considered acceptable with regard to local fatigue, which was defined as a switch of local BF to the post-exercise period, a decrease in the number of zero-crossings (EMG) and marked increases in subjective ratings.     

Blood lactate during submaximal exercises

Summary Values of oxygen consumption, carbon dioxide production, ventilation and blood lactate concentration were determined in eight active male subjects during the minute following submaximal square-wave exercise on a treadmill under two sets of conditions. Square-wave exercise was (1) integrated in a series of intermittent incremental exercises of 4-min duration separated by 1-min rest periods; (2) isolated, of 4- and 12-min duration, and of intensity corresponding to each of the intermittent incremental periods of exercise. For square-wave exercise of the same duration (4 min) and intensity, no significant differences in the above-mentioned parameters were noted between intermittent incremental exercise and isolated exercise. Only at high work rate (>92% maximal oxygen uptake), were blood lactate levels in three subjects slightly higher after 12-min of isolated exercise than after the 4-min periods of isolated exercise. Examination of these results suggests that (1) 80–90% of the blood lactate concentration observed under our experimental conditions results from the accumulation of lactate in the blood during the period of oxygen deficit; (2) therefore the blood lactate concentration/exercise intensity relationship, for the most part, appears to represent the lactate accumulated early in the periods of intermittent incremental exercise.     

间歇性外斜视手术治疗的临床观察

目的：对５６例间歇性外科视术后患者进行追踪观察,探讨手术年龄与双眼视觉恢复率的关系。方法：手术前后用三棱镜遮盖法,同视机检查斜视度,ＡＣ／Ａ比值及视网膜对应情况,术后进行同视机训练。结果：４－７岁双眼视觉恢复率最高,与８～１３岁组之间差异有高度显著性（Ｐ〈０．０１）,８～１３岁组与１４～１７岁组差异有显著性（Ｐ〈０．０５）,１４～１７岁组与１８岁以上组之间差异无显著性（Ｐ〉０．０５）。结论：对间歇     

两种血液净化方式治疗急性炎症反应综合征合并急性肾损伤

目的比较延长每日血液滤过(extended daily hemofiltration,EDHF)和间断血液透析(intermitent hemodialysis,IHD)治疗全身炎症反应综合征(systemic inflammatory response syndrome,SIRS)合并急性肾损伤(acute kidney injury,AKI)患者的疗效。方法前瞻性收集2010年1月至2013年5月SIRS合并AKI的患者40例,随机数字法分为2组,在常规治疗基础上,分别予以EDHF及IHD(连续诱导透析3 d,之后隔日透析)治疗,比较2组患者的转归(包括院内病死率,肾存活率,住院日及住院费用)。结果①EDHF组院内病死率为15%(3/20)、肾存活率为70%(14/20),IHD组院内病死率为25%(5/20)、肾存活率为45%(9/20),2组比较差异无统计学意义(P0.05);EDHF组平均住院日为(32.6±8.6)d,IHD组为(39.2±11.5)d,2组比较差异有统计学意义(P0.05);EDHF组平均住院费用为(28 338.7±8 165.4)元,IHD组平均住院费用为(28 912.9±7443.6)元,2组比较差异无统计学意义(P0.05)。②第5天EDHF组血肌酐为(243.5±92.8)μmol/L,血尿素氮为(15.6±4.0)mmol/L,IHD组血肌酐为(363.8±209.0)μmol/L,血尿素氮为(17.4±4.6)mmol/L,2组比较差异均有统计学意义(P均0.05)。结论对于SIRS合并AKI的患者,EDHF治疗的存活率及肾存活率有高于IHD治疗的趋势,EDHF治疗患者住院时间缩短,总治疗费用与IHD治疗相当。     

HIF-1α介导了间歇低氧对人肺腺癌A549细胞体外生物学行为的影响

目的:探讨缺氧诱导因子1α(HIF-1α)是否介导间歇低氧对人肺腺癌A549细胞体外活力、凋亡以及侵袭的影响。方法:采用体外转染方法将特异性针对HIF-1α的siRNA导入A549细胞,在间歇低氧条件下培养后通过real-time PCR和Western blot法检测HIF-1α及其下游Bcl-2、Bax、P53、P21、VEGF的mRNA和蛋白表达;通过MTT法和流式细胞术分别检测A549细胞的活力、凋亡及细胞周期;通过Transwell小室检测A549细胞的侵袭能力。结果:未转染HIF-1α-siRNA的A549细胞[间歇低氧空白对照组(IHC组)、间歇低氧空载体对照组(IHE组)及间歇低氧阴性对照组(IHN组)]经间歇低氧干预后的HIF-1α、Bcl-2及VEGF表达均明显高于常氧对照组(RA组),Bax及P21表达均明显低于RA组(P0.05),而转染HIF-1α-siRNA的A549细胞[间歇低氧siRNA组(IHS组)]较IHC组、IHE组及IHN组经间歇低氧干预后的HIF-1α、BCL-2及VEGF表达均明显下调,Bax及P21表达较均明显上调(P0.05);所有间歇低氧组A549细胞的P53表达均较RA组升高(P0.05),但各间歇低氧组之间无显著性差异。IHC组、IHE组及IHN组A549细胞经间歇低氧干预后较RA组的细胞活力增强,凋亡率下降,侵袭力增强(P0.05),而IHS组A549细胞经间歇低氧干预后细胞周期被阻滞于G1期,较未转染组的细胞活力下降,凋亡增加,侵袭能力下降(P0.05)。结论:间歇低氧可通过HIF-1α途径调控其下游基因表达进而促进A549细胞的活力和转移;通过RNA干扰技术造成HIF-1α基因沉默可以抑制间歇低氧引起的A549细胞生长和转移。     

间歇正压通气对极低出生体重儿有 创呼吸机脱机拔管的价值

探讨间歇正压通气对极低出生体重儿有创呼吸机脱机拔管的临床价值。方法　选择极低体重儿 ８０例,按照随机数字法分为两组,观察组患儿在拔除气管导管后立即使用婴儿呼吸机进行间歇正压通气,对照 组使用面罩氧,比较两组机械通气相关指标、治疗后血气分析结果及乳酸水平变化情况及治疗过程中发生的不 良反应。结果　观察组机械通气时间、拔管后呼吸暂停时间及拔管后发绀持续时间均显著短于对照组（Ｐ＜ ００５）,治疗后,观察组ｐＨ水平高于对照组（Ｐ＜００５）,ＰＣＯ２水平低于对照组（Ｐ＜００５）,ＰＯ２水平高于对照组 （Ｐ＜００５）,血乳酸水平低于对照组（Ｐ＜００５）,两组发生腹胀、胃潴留,呼吸道干燥及返流的差异无统计学意 义（Ｐ＞００５）。结论　鼻塞间歇正压通气能显著逆转缺氧及二氧化碳蓄积,利于顺利撤离有创呼吸机,且不增 加不良反应。