补中益气汤联合生物反馈电刺激在产后盆底功能障碍患者的应用研究

目的:研究探讨补中益气汤联合生物反馈电刺激对产后盆底功能障碍患者的临床治疗效果及对其盆底肌肉张力的影响。方法:选择我院就诊的90例产后盆底功能障碍气虚证患者(2017年11月～2018年10月),按照随机数字表法划分为30例/组的A组、B组、C组,A组实施常规盆底肌锻炼,B组采用盆底治疗仪实施生物反馈电刺激治疗,C组实施生物反馈电刺激联合中药补中益气汤治疗,比较三组的疗效、盆底肌力评分、阴道最大收缩压、盆腔器官脱垂、尿失禁、性生活质量评分。结果:(1)组间临床疗效、证候疗效比较,C组的临床总有效率、证候改善总有效率均高于A组、B组(P0.05),而A组与B组之间比较均无统计学差异(P0.05)。(2)治疗后,C组的盆底肌力评分、阴道最大收缩压、性生活质量评分均高于A组、B组(P0.05),A组与B组之间比较均无统计学差异(P0.05)。(3)C组的盆腔器官脱垂、尿失禁等发生率均低于A组、B组(P0.05),而A组与B组比较均无统计学差异(P0.05)。结论:生物反馈电刺激联合补中益气汤治疗可有效改善产后盆底功能障碍患者的盆底肌力和阴道压力,达到良好的临床疗效,有利于预防盆腔器官脱垂、尿失禁的发生,改善其性生活质量。     

盆底电刺激对大鼠盆底肌肌肉、神经发育的形态学影响研究

目的:探讨与研究盆底电刺激对大鼠盆底肌肌肉、神经发育的形态学影响.方法:36只Wistar产后健康雌性大鼠分为对照组、模型组与刺激组,每组12只.模型组与刺激组都建立了压力性尿失禁模型,对照组不给予任何处理.建模后刺激组给予盆底电刺激,每3 d一次,持续治疗12d;模型组在建模后不给予任何治疗处理.结果:模型组与刺激组...     

髋部肌锻炼联合盆底电刺激生物反馈对盆底功能障碍性疾病患者盆底功能及应激反应的影响

摘要 目的：探讨髋部肌锻炼联合盆底电刺激生物反馈对盆底功能障碍性疾病（PFD）患者盆底功能及应激反应的影响。方法：选取2021年1月-2022年12月在我院接受治疗的120例PFD患者作为研究对象,按随机数字表法分为对照组和观察组,每组各60例。对照组患者进行髋部肌锻炼,观察组患者在对照组的基础上联合盆底电刺激生物反馈治疗,观察分析两组患者盆底功能以及应激反应的变化。结果：两组治疗后观察组临床总有效率显著高于对照组（P＜0.05）;两组患者治疗后PFDI-20、PISQ-12及PFIQ-7评分显著优于治疗前,且观察组上述指标明显优于对照组（P＜0.05）;治疗后两组患者前盆底肌电位、动态肌张力、静态肌张力及收缩力较治疗前显著改善,且观察组相较于对照组上述指标显著提升（P＜0.05）;治疗后两组患者去甲肾上腺素（NE）、前列腺素（PGE₂）、皮质醇（COR）水平明显提高,且观察组明显优于对照组（P＜0.05）。结论：髋部肌锻炼联合盆底电刺激生物反馈使肌肉功能得到锻炼,提高了盆底肌张力水平,促进盆底功能的恢复和应激反应的提高,明显提高患者的生活质量。     

补中益气汤联合低频脉冲电刺激促进产后盆底功能障碍的效果及血清松弛素、CTGF和MMP-1水平的影响

摘要 目的：探讨补中益气汤联合低频脉冲电刺激促进产后盆底功能障碍的效果及血清松弛素（RLX）、结缔组织生长因子（CTGF）和基质金属蛋白酶-1（MMP-1）水平的影响。方法：选取我院2022年4月到2023年4月收治的150例产后盆底功能障碍患者作为研究对象，分为观察组与对照组，各组均75例。对照组患者采取低频脉冲电刺激治疗，观察组患者采取补中益气汤联合低频脉冲电刺激治疗，对比两组患者的临床疗效，治疗前后盆底表面肌电变化情况，并分别在治疗前后应用盆腔脏器官脱垂-尿失禁性功能问卷（PISQ-12）、国际尿控协会盆腔脏器脱垂定量分析量表（POP-Q）、尿失禁问卷表简表（ICI-Q-SF）评估两组患者的性功能、盆腔脱垂程度及尿失禁情况，并对比治疗前后血清RLX、CTGF和MMP-1表达水平。结果：观察组总有效率93.33%明显高于对照组78.67%（P＜0.05）；两组患者治疗前耐力收缩（Ⅱ类肌）、持续收缩和快速收缩（Ⅰ类肌）、前静息电位、后静息电位肌电水平对比无差异（P＞0.05），治疗后观察组快速收缩（Ⅰ类肌）高于对照组（P＜0.05），静息电位与后静息电位低于对照组（P＜0.05）；两组患者治疗前PISQ-12、POP-Q和ICI-Q-SF评分对比无明显差异（P＞0.05），治疗后两组患者PISQ-12、ICI-Q-SF评分升高，观察组较对照组高，POP-Q评分均降低，观察组较对照组低（P＜0.05）；两组患者治疗前RLX、CTGF和MMP-1表达水平对比无差异（P＞0.05），治疗后两组患者RLX、CTGF和MMP-1表达水平均降低，且观察组低于对照组（P＜0.05）。结论：补中益气汤联合低频脉冲电刺激可提升产后盆底功能障碍的临床疗效，改善盆底肌表面肌电变化，改善患者性功能、盆腔脱垂程度及尿失禁情况，且能够降低血清松弛素、CTGF和MMP-1表达水平。     

Characterization of the kinetic and thermodynamic landscape of RNA folding using a novel application of isothermal titration calorimetry

A novel isothermal titration calorimetry (ITC) method was applied to investigate RNA helical packing driven by the GAAA tetraloop–receptor interaction in magnesium and potassium solutions. Both the kinetics and thermodynamics were obtained in individual ITC experiments, and analysis of the kinetic data over a range of temperatures provided Arrhenius activation energies (ΔH^‡) and Eyring transition state entropies (ΔS^‡). The resulting rich dataset reveals strongly contrasting kinetic and thermodynamic profiles for this RNA folding system when stabilized by potassium versus magnesium. In potassium, association is highly exothermic (ΔH_25°C = −41.6 ± 1.2 kcal/mol in 150 mM KCl) and the transition state is enthalpically barrierless (ΔH^‡ = −0.6 ± 0.5). These parameters are sigificantly positively shifted in magnesium (ΔH_25°C = −20.5 ± 2.1 kcal/mol, ΔH^‡ = 7.3 ± 2.2 kcal/mol in 0.5 mM MgCl₂). Mixed salt solutions approximating physiological conditions exhibit an intermediate thermodynamic character. The cation-dependent thermodynamic landscape may reflect either a salt-dependent unbound receptor conformation, or alternatively and more generally, it may reflect a small per-cation enthalpic penalty associated with folding-coupled magnesium uptake.     

悬吊训练疗法联合生物反馈电刺激对产后压力性尿失禁患者盆底功能和尿流动力学的影响

摘要 目的：观察悬吊训练疗法联合生物反馈电刺激对产后压力性尿失禁（PSUI）患者盆底功能和尿流动力学的影响。方法：选择2019年7月~2021年8月期间我院接收的PSUI患者96例,符合要求的患者根据信封抽签法分为对照组（48例）和研究组（48例）。对照组患者接受悬吊训练疗法,研究组患者接受悬吊训练疗法联合生物反馈电刺激,对比两组疗效、盆底功能指标和尿流动力学指标,观察两组尿垫试验漏尿量、国际尿失禁咨询委员会尿失禁问卷简表（ICI-Q-SF）问卷评分。结果：研究组的临床总有效率高于对照组（P<0.05）。治疗1个月后,两组24 h尿垫试验漏尿量和ICI-Q-SF问卷评分降低,且研究组低于对照组（P<0.05）。研究组治疗1个月后盆底肌力改善效果优于对照组（P<0.05）。两组治疗1个月后最大尿道闭合压力（MUCP）、功能尿道长度（LES）、腹压漏尿点压（ALPP）、与最大尿流率（Qmax）升高,且研究组高于对照组（P<0.05）。结论：PSUI患者经悬吊训练疗法联合生物反馈电刺激干预,可有效改善临床症状,促进盆底功能和尿流动力学恢复,效果显著。     

电针阴部神经刺激疗法联合Kegel盆底康复训练对产后压力性尿失禁患者盆底肌力、尿流动力学和生活质量的影响

摘要 目的：探讨电针阴部神经刺激疗法联合Kegel盆底康复训练对产后压力性尿失禁（SUI）患者盆底肌力、尿流动力学和生活质量的影响。方法：选取2019年6月~2021年11月期间于我院就诊的产后SUI患者109例,按照入院就诊奇偶顺序分为两组,其中对照组54例,接受Kegel盆底康复训练,研究组55例,接受电针阴部神经刺激疗法联合Kegel盆底康复训练。对比两组疗效、漏尿量、尿失禁程度、盆底肌力、尿流动力学和生活质量。结果：研究组的临床总有效率高于对照组（P<0.05）。两组治疗后盆底肌肌力各指标（手测肌力和Ⅰ类肌纤维最大值、Ⅱ类肌纤维平均值）均升高,且研究组高于对照组（P<0.05）。两组治疗后漏尿量、尿失禁程度评分均下降,且研究组低于对照组（P<0.05）。两组治疗后尿流动力学相关指标[腹压漏尿点压（AL-PP）、最大尿流率（Qmax）和最大尿道闭合压力（MUCP）]均升高,且研究组高于对照组（P<0.05）。两组治疗后尿失禁生活质量量表（I-QOL）各维度（限制性行为、心理影响、社交活动受限）评分及总分均升高,且研究组高于对照组（P<0.05）。结论：电针阴部神经刺激疗法联合Kegel盆底康复训练可有效改善产后SUI患者的盆底肌肌力和尿失禁情况,减少漏尿量,同时可促进尿流动力学恢复,进而提高患者的生活质量。     

Intercellular synchronization of diffusively coupled Ca2+ oscillators

We examine the synchrony in the dynamics of localized [Ca^2 +]_i oscillations among a group of cells exhibiting such complex Ca^2 + oscillations, connected in the form of long chain, via diffusing coupling where cytosolic Ca^2 + and inositol 1,4,5-triphosphate are coupling molecules. Based on our numerical results, we could able to identify three regimes, namely desynchronized, transition and synchronized regimes in the (T − k_e) (time period-coupling constant) and (A − k_e) (amplitude-coupling constant) spaces which are supported by phase plots (Δϕ verses time) and recurrence plots, respectively. We further show the increase of synchronization among the cells as the number of coupling molecules increases in the (T − k_e) and (A − k_e) spaces.     

基于经会阴实时三维超声评估生物反馈电刺激联合盆底肌锻炼治疗产后盆底功能障碍的临床疗效

摘要 目的：探讨经会阴实时三维超声评估生物反馈电刺激联合盆底肌锻炼治疗产后盆底功能障碍的临床疗效。方法：选择2020年9月至2022年9月我院收治的96例产后盆底功能障碍患者,根据随机数字表法将患者分为两组,对照组（48例）采用盆底肌锻炼治疗,研究组（48例）采用生物反馈电刺激联合盆底肌锻炼治疗。治疗前后采用经会阴实时三维超声检查,对比两组治疗前后的盆底功能障碍调查表（PFDI-20）、盆底障碍影响简易问卷7（PFIQ-7）评分、静息和Valsalva动作状态下的肛提肌超声参数。分析肛提肌超声参数与PFDI-20、PFIQ-7评分的相关性。结果：两组治疗后PFDI-20、PFIQ-7评分,静息和Valsalva动作状态下肛提肌裂孔前后径、肛提肌裂孔左右径、肛提肌裂孔面积较治疗前降低（P＜0.05）,静息时肛提肌厚度较治疗前增加（P＜0.05）。研究组治疗后PFDI-20、PFIQ-7评分,静息和Valsalva动作状态下肛提肌裂孔前后径、肛提肌裂孔左右径、肛提肌裂孔面积低于对照组（P＜0.05）,静息时肛提肌厚度大于对照组（P＜0.05）。静息和Valsalva状态下肛提肌裂孔前后径、肛提肌裂孔左右径、肛提肌裂孔面积与PFDI-20、PFIQ-7评分呈正相关（P＜0.05）,静息状态肛提肌厚度与PFDI-20、PFIQ-7评分呈负相关（P＜0.05）。结论：经生物反馈电刺激联合盆底肌锻炼治疗后肛提肌裂孔大小较治疗前降低,肛提肌厚度较治疗前增加,且与PFDI-20、PFIQ-7评分改善有关,经会阴实时三维超声可客观、有效评价产后盆底功能障碍患者的治疗效果。     

生物反馈电刺激联合Kegel训练对产后盆底功能障碍性疾病患者盆底功能电生理指标和生活质量的影响

目的:观察生物反馈电刺激联合Kegel训练对产后盆底功能障碍性疾病(PFD)患者盆底功能电生理指标和生活质量的影响。方法:研究对象为2018年3月~2020年12月我院收治的80例产后PFD患者。采用双色球随机分组法将患者分为对照组(n=40)和研究组(n=40)。对照组给予Kegel训练,研究组给予生物反馈电刺激联合Kegel训练,两组均治疗8周。对比两组治疗8周后的疗效和尿失禁、盆底器官脱垂程度的改善情况。对比两组治疗前、治疗8周后的盆底功能电生理指标、日常生活质量和性生活质量。结果:治疗8周后,研究组的临床总有效率较对照组高(P<0.05)。治疗8周后,研究组I类肌纤维疲劳度、Ⅱ类肌纤维疲劳度、快肌最大肌电值及阴道动态压力均优于对照组(P<0.05)。研究组治疗8周后尿失禁、盆底器官脱垂程度的改善情况优于对照组(P<0.05)。治疗8周后,研究组盆底功能影响问卷简表(PIFQ-7)评分、盆腔器官脱垂-尿失禁性功能问卷(PISQ-12)评分均低于对照组(P<0.05)。结论:产后PFD患者采用生物反馈电刺激联合Kegel训练治疗疗效明确,可促进尿失禁、盆底器官脱垂程度情况及盆底功能改善,提高患者日常生活质量和性生活质量。     

Predicting translational diffusion of evolutionary conserved RNA structures by the nucleotide number

Ribonucleic acids are highly conserved essential parts of cellular life. RNA function is determined to a large extent by its hydrodynamic behaviour. The presented study proposes a strategy to predict the hydrodynamic behaviour of RNA single strands on the basis of the polymer size. By atom-level shell-modelling of high-resolution structures, hydrodynamic radius and diffusion coefficient of evolutionary conserved RNA single strands (ssRNA) were calculated. The diffusion coefficients D of 17–174 nucleotides (nt) containing ssRNA depended on the number of nucleotides N with D = 4.56 × 10⁻¹⁰ N^−0.39 m² s⁻¹. The hydrodynamic radius R_H depended on N with R_H = 5.00 × 10⁻¹⁰ N^0.38 m. An average ratio of the radius of gyration and the hydrodynamic radius of 0.98 ± 0.08 was calculated in solution. The empirical law was tested by in solution measured hydrodynamic radii and radii of gyration and was found to be highly consistent with experimental data of evolutionary conserved ssRNA. Furthermore, the hydrodynamic behaviour of several evolutionary unevolved ribonucleic acids could be predicted. Based on atom-level shell-modelling of high-resolution structures and experimental hydrodynamic data, empirical models are proposed, which enable to predict the translational diffusion coefficient and molecular size of short RNA single strands solely on the basis of the polymer size.     

实时三维盆底超声对产后压力性尿失禁患者疗效评估作用及与尿动力学的相关性分析

摘要 目的：探讨实时三维盆底超声对产后压力性尿失禁（SUI）患者疗效评估作用及与尿动力学的相关性。方法：选择2020年4月至2022年12月石家庄市人民医院收治的139例产后SUI患者,均接受盆底生物反馈电刺激联合盆底肌锻炼治疗。治疗前后分别进行实时三维盆底超声检查和尿动力学检查。比较治疗前后实时三维盆底超声参数、尿动力学指标差异。Pearson法分析实时三维盆底超声参数与尿动力学指标的相关性。结果：实时三维盆底超声图像特征显示：治疗前盆膈裂孔内的结构疏松,回声变弱,盆腔器官结缔组织疏松,间隙增宽,盆膈裂孔面积、尿道旋转角、膀胱尿道后角以及膀胱颈移动度较大;治疗后盆膈裂孔两侧耻骨直肠肌对称,耻骨内脏肌呈带状高回声,盆膈裂孔面积、尿道旋转角、膀胱尿道后角以及膀胱颈移动度较治疗前降低。产后SUI患者治疗后静息状态和Valsalva状态下盆膈裂孔面积、尿道旋转角、膀胱尿道后角、膀胱颈移动度均较治疗前降低（P＜0.05）,腹压漏尿点压、最大逼尿肌压力均较治疗前增加（P＜0.05）。产后SUI患者静息状态和Valsalva状态下盆膈裂孔面积、尿道旋转角、膀胱尿道后角、膀胱颈移动度与最大逼尿肌压力、腹压漏尿点压呈负相关（P＜0.05）,与最大膀胱容量和残余尿量无关（P＞0.05）。结论：产后SUI患者经盆底生物反馈电刺激联合盆底肌锻炼治疗后实时三维盆底超声参数较治疗前降低,与尿动力学改善有关。临床可通过实时三维盆底超声检查,对产后SUI患者进行临床疗效评价,以指导临床治疗。     

Dystrophin、MGF及M-Cad在难产大鼠模型盆底肌肉中的表达意义研究

摘要 目的：研究模拟难产大鼠模型盆底肌肉中Dystrophin、MGF及M-Cad的表达,并探讨其表达与压力性尿失禁的相关性。方法：选择未生产过的雌性SD大鼠40只,按照随机数字表法均分为对照组、模型1组、模型2组和模型3组,对照组大鼠正常喂养,模型1组大鼠行阴道扩张手术,模型2组大鼠切除双侧坐骨神经,模型3组大鼠既行阴道扩张术又切除双侧坐骨神经。喂养1月后,称重后处死各组大鼠,并分离盆底肌肉,称重后通过定量PCR法（qPCR）检测Dystrophin、MGF及M-Cad mRNA的表达。结果：与对照组大鼠相比,难产大鼠模型组（模型1组、模型2组和模型3组）体重和盆底肌肉重量无显著变化（P>0.05）,漏尿点压力和最大膀胱容量均显著下降（P<0.05）,盆底肌肉Dystrophin、MGF及M-Cad mRNA表达均显著下降（P<0.05）。Pearson相关性分析：大鼠盆底肌肉Dystrophin、MGF及M-Cad mRNA表达水平与漏尿点压力均呈密切正相关（Dystrophin：r=0.725,P=0.002;MGF：r=0.702,P=0.018;M-Cad：r=0.838,P<0.001）;鼠盆底肌肉Dystrophin、MGF及M-Cad mRNA表达水平与最大膀胱容量也均呈密切正相关（Dystrophin：r=0.733,P=0.001;MGF：r=0.682,P=0.025;M-Cad：r=0.819,P<0.001）。结论：模拟难产大鼠模型盆底肌肉Dystrophin、MGF及M-Cad的表达降低,并且提示其表达降低可能与压力性尿失禁有关。     

Microscopic Modeling of País Grape Seed Extract Absorption in the Small Intestine

The concentration profiles and the absorbed fraction (F) of the País grape seed extract in the human small intestine were obtained using a microscopic model simulation that accounts for the extracts'' dissolution and absorption. To apply this model, the physical and chemical parameters of the grape seed extract solubility (C_s), density (ρ), global mass transfer coefficient between the intestinal and blood content (k) (effective permeability), and diffusion coefficient (D) were experimentally evaluated. The diffusion coefficient (D = 3.45 × 10⁻⁶ ± 5 × 10⁻⁸ cm²/s) was approximately on the same order of magnitude as the coefficients of the relevant constituents. These results were chemically validated to discover that only the compounds with low molecular weights diffused across the membrane (mainly the (+)-catechin and (−)-epicatechin compounds). The model demonstrated that for the País grape seed extract, the dissolution process would proceed at a faster rate than the convective process. In addition, the absorbed fraction was elevated (F = 85.3%). The global mass transfer coefficient (k = 1.53 × 10⁻⁴ ± 5 × 10⁻⁶ cm/s) was a critical parameter in the absorption process, and minor changes drastically modified the prediction of the extract absorption. The simulation and experimental results show that the grape seed extract possesses the qualities of a potential phytodrug.KEY WORDS: dose absorption, mathematical modeling, País grape seed extract, simulation     

In vitro propagation of female Ephedra foliata Boiss. & Kotschy ex Boiss.: an endemic and threatened Gymnosperm of the Thar Desert

Ephedra foliata Boiss. & Kotschy ex Boiss., (family – Ephedraceae), is an ecologically and economically important threatened Gymnosperm of the Indian Thar Desert. A method for micropropagation of E. foliata using nodal explant of mature female plant has been developed. Maximum bud-break (90 %) of the explant was obtained on MS medium supplemented with 1.5 mg l⁻¹ of benzyl adenine (BA) + additives. Explant produces 5.3 ± 0.40 shoots from single node with 3.25 ± 0.29 cm length. The multiplication of shoots in culture was affected by salt composition of media, types and concentrations of plant growth regulators (PGR’s) and their interactions, time of transfer of the cultures. Maximum number of shoots (26.3 ± 0.82 per culture vessel) were regenerated on MS medium modified by reducing the concentration of nitrates to half supplemented with 200 mg l⁻¹ ammonium sulphate {(NH₄) ₂SO₄} (MMS3) + BA (0.25 mg l⁻¹), Kinetin (Kin; 0.25 mg l⁻¹), Indole-3-acetic acid (IAA; 0.1 mg l⁻¹) and additives. The in vitro produced shoots rooted under ex vitro on soilrite moistened with one-fourth strength of MS macro salts in screw cap bottles by treating the shoot base (s) with 500 mg l⁻¹ of Indole-3-butyric acid (IBA) for 5 min. The micropropagated plants were hardened in the green house. The described protocol can be applicable for (i) large scale plant production (ii) establishment of plants in natural habitat and (iii) germplasm conservation of this endemic Gymnosperm of arid regions.     

Salivary extracellular heat shock protein 70 (eHSP70) levels increase after 59 min of intense exercise and correlate with resting salivary secretory immunoglobulin A (SIgA) levels at rest

This study aimed to identify the response of a salivary stress protein, extracellular heat shock protein (eHSP70), to intense exercise and to investigate the relationship between salivary eHSP70 and salivary immunoglobulin A (SIgA) levels in response to exercise. Sixteen healthy sedentary young males (means ± SD 23.8 ± 1.5 years, 172.2 ± 6.4 cm, 68.3 ± 7.4 kg) performed 59 min of cycling exercise at 75 % VO2_max. Saliva and whole blood samples were collected before (Pre), immediately after (Post), and at 1, 2, 3, and 4 h after completion of the exercise (1, 2, 3, and 4 h). The salivary eHSP70 and SIgA levels were measured by enzyme-linked imunosorbent assay (ELISA), and the secretion rates were computed by multiplying the concentration by the saliva flow rate. White blood cells were analyzed using an automated cell counter with a direct-current detection system. The salivary eHSP70 secretion rates were 1.11 ± 0.86, 1.51 ± 1.47, 1.57 ± 1.32, 2.21 ± 2.04, 3.36 ± 2.72, and 6.89 ± 4.02 ng · min⁻¹ at Pre, Post, and 1, 2, 3, and 4 h, respectively. The salivary eHSP70 secretion rate was significantly higher at 4 h than that at Pre, Post, 1, and 3 h (p < 0.05). The SIgA secretion rates were 26.9 ± 12.6, 20.3 ± 10.4, 19.6 ± 11.0, 21.8 ± 12.8, 21.5 ± 11.9, and 21.9 ± 11.7 μg · min⁻¹ at Pre, Post, 1, 2, 3, and 4 h, respectively. The salivary SIgA secretion rate was significantly lower between 1 and 4 h than that at Pre (p < 0.05). There was a positive correlation between salivary eHSP70 and SIgA in both concentration and secretion rates before exercise (p < 0.05). The absolute number of white blood cells significantly increased after exercise, with a maximum at 2 h (p < 0.05). The neutrophil/lymphocyte ratio was significantly increased from 1 to 4 h when compared with that in the Pre samples (p < 0.05). The present study revealed that salivary eHSP70 significantly increased at 4 h after the 59 min of intense exercise in sedentary male subjects. Exercise stress can induce elevated salivary eHSP70 level and upregulate oral immune function partially.     

Effect of Acetate and Carbonate Buffers on the Photolysis of Riboflavin in Aqueous Solution: A Kinetic Study

The photolysis of riboflavin (RF) in the presence of acetate buffer (pH 3.8–5.6) and carbonate buffer (pH 9.2–10.8) has been studied using a multicomponent spectrophotometric method for the simultaneous assay of RF and its photoproducts. Acetate and carbonate buffers have been found to catalyze the photolysis reaction of RF. The apparent first-order rate constants for the acetate-catalyzed reaction range from 0.20 to 2.86 × 10⁻⁴ s⁻¹ and for the carbonate-catalyzed reaction from 3.33 to 15.89 × 10⁻⁴ s⁻¹. The second-order rate constants for the interaction of RF with the acetate and the carbonate ions range from 2.04 to 4.33 × 10⁻⁴ M⁻¹ s⁻¹ and from 3.71 to 11.80 × 10⁻⁴ M⁻¹ s⁻¹, respectively. The k-pH profile for the acetate-catalyzed reaction is bell shaped and for the carbonate-catalyzed reaction a steep curve. Both HCO₃⁻ and CO₃^2 − ions are involved in the catalysis of the photolysis reaction in alkaline solution. The rate constants for the HCO₃⁻ and CO₃^2 − ions catalyzed reactions are 0.72 and 1.38 × 10⁻³ M⁻¹ s⁻¹, respectively, indicating a major role of CO₃^2 − ions in the catalysis reaction. The loss of RF fluorescence in acetate buffer suggests an interaction between RF and acetate ions to promote the photolysis reaction. The optimum stability of RF solutions is observed in the pH range 5–6, which is suitable for pharmaceutical preparations.KEY WORDS: acetate effect, carbonate effect, photolysis, riboflavin, spectrophotometric assay     

Relative Bioavailability of Chlorothiazide from Mucoadhesive Compacts in Pigs

The relative bioavailability of chlorothiazide from mucoadhesive polymeric compacts is compared to commercial oral suspension in pigs. A single-dose randomized study was conducted in 12 healthy pigs that are 9–10 weeks old. After overnight fasting, pigs were divided into two groups of six animals. To the first group, a reference product containing 50 mg of chlorothiazide suspension, and in the second group, test product (mucoadhesive compacts) chlorothiazide (50 mg) was administered with 75 mL of water via gastric tubes. Blood samples were collected between 0 to 24 h using catheters inserted into the jugular vein. Plasma was separated by protein precipitation, and chlorothiazide concentrations were determined using a high-performance liquid chromatography method. The mean T_max and the C_max of chlorothiazide following the administration of oral suspension and mucoadhesive compacts were 0.58 ± 0.20 h and 682.97 ± 415.69 ng/mL and 2.17 ± 0.98 h and 99.42 ± 124.08 ng/mL, respectively. The K_el and T_1/2 of chlorothiazide were found to be 1.06 ± 0.28 h⁻¹ and 0.70 ± 0.21 h from suspension and 0.95 ± 1.11 h⁻¹ and 2.05 ± 1.90 h from the compacts, respectively. The T_max of mucoadhesive compacts were significantly longer (p < 0.05; 2.17 h) than the reference products (0.58 h), whereas the C_max of compacts were significantly lower (99 ng/mL) than the reference product (683 ng/mL; p < 0.05). The area under the curve (AUC) of compacts accounts only 50.15% (404.32 ± 449.93 ng h/mL) of the reference product’s AUC (806.27 ± 395.97 ng h/mL). The relative bioavailability of the compacts was lower than that of the suspension, and this may be due to the narrow window of absorption for chlorothiazide.Key words: bioavailability, chlorothiazide, mucoadhesive compacts, pigs     

Thermodynamic and kinetic basis for recognition and repair of 8-oxoguanine in DNA by human 8-oxoguanine-DNA glycosylase

We have used a stepwise increase in ligand complexity approach to estimate the relative contributions of the nucleotide units of DNA containing 7,8-dihydro-8-oxoguanine (oxoG) to its total affinity for human 8-oxoguanine DNA glycosylase (OGG1) and construct thermodynamic models of the enzyme interaction with cognate and non-cognate DNA. Non-specific OGG1 interactions with 10–13 nt pairs within its DNA-binding cleft provides approximately 5 orders of magnitude of its affinity for DNA (ΔG° approximately −6.7 kcal/mol). The relative contribution of the oxoG unit of DNA (ΔG° approximately −3.3 kcal/mol) together with other specific interactions (ΔG° approximately −0.7 kcal/mol) provide approximately 3 orders of magnitude of the affinity. Formation of the Michaelis complex of OGG1 with the cognate DNA cannot account for the major part of the enzyme specificity, which lies in the k_cat term instead; the rate increases by 6–7 orders of magnitude for cognate DNA as compared with non-cognate one. The k_cat values for substrates of different sequences correlate with the DNA twist, while the K_M values correlate with ΔG° of the DNA fragments surrounding the lesion (position from −6 to +6). The functions for predicting the K_M and k_cat values for different sequences containing oxoG were found.     

Heat and exercise acclimation increases intracellular levels of Hsp72 and inhibits exercise-induced increase in intracellular and plasma Hsp72 in humans

In order to verify the effects of heat and exercise acclimation (HA) on resting and exercise-induced expression of plasma and leukocyte heat shock protein 72 (Hsp72) in humans, nine healthy young male volunteers (25.0 ± 0.7 years; 80.5 ± 2.0 kg; 180 ± 2 cm, mean ± SE) exercised for 60 min in a hot, dry environment (40 ± 0°C and 45 ± 0% relative humidity) for 11 days. The protocol consisted of running on a treadmill using a controlled hyperthermia technique in which the work rate was adjusted to elevate the rectal temperature by 1°C in 30 min and maintain it elevated for another 30 min. Before and after the HA, the volunteers performed a heat stress test (HST) at 50% of their individual maximal power output for 90 min in the same environment. Blood was drawn before (REST), immediately after (POST) and 1 h after (1 h POST) HST, and plasma and leukocytes were separated and stored. Subjects showed expected adaptations to HA: reduced exercise rectal and mean skin temperatures and heart rate, and augmented sweat rate and exercise tolerance. In HST1, plasma Hsp72 increased from REST to POST and then returned to resting values 1 h POST (REST: 1.11 ± 0.07, POST: 1.48 ± 0.10, 1 h POST: 1.22 ± 0.11 ng mL⁻¹; p < 0.05). In HST2, there was no change in plasma Hsp72 (REST: 0.94 ± 0.08, POST: 1.20 ± 0.15, 1 h POST: 1.17 ± 0.16 ng mL⁻¹; p > 0.05). HA increased resting levels of intracellular Hsp72 (HST1: 1 ± 0.02 and HST2: 4.2 ± 1.2 density units, p < 0.05). Exercise-induced increased intracellular Hsp72 expression was observed on HST1 (HST1: REST, 1 ± 0.02 vs. POST, 2.9 ± 0.9 density units, mean ± SE, p < 0.05) but was inhibited on HST2 (HST2: REST, 4.2 ± 1.2 vs. POST, 4.4 ± 1.1 density units, p > 0.05). Regression analysis showed that the lower the pre-exercise expression of intracellular Hsp72, the higher the exercise-induced increase (R = −0.85, p < 0.05). In conclusion, HA increased resting leukocyte Hsp72 levels and inhibited exercise-induced expression. This intracellular adaptation probably induces thermotolerance. In addition, the non-increase in plasma Hsp72 after HA may be related to lower stress at the cellular level in the acclimated individuals.