Stringency of the 2-His–1-Asp Active-Site Motif in Prolyl 4-Hydroxylase

The non-heme iron(II) dioxygenase family of enzymes contain a common 2-His–1-carboxylate iron-binding motif. These enzymes catalyze a wide variety of oxidative reactions, such as the hydroxylation of aliphatic C–H bonds. Prolyl 4-hydroxylase (P4H) is an α-ketoglutarate-dependent iron(II) dioxygenase that catalyzes the post-translational hydroxylation of proline residues in protocollagen strands, stabilizing the ensuing triple helix. Human P4H residues His412, Asp414, and His483 have been identified as an iron-coordinating 2-His–1-carboxylate motif. Enzymes that catalyze oxidative halogenation do so by a mechanism similar to that of P4H. These halogenases retain the active-site histidine residues, but the carboxylate ligand is replaced with a halide ion. We replaced Asp414 of P4H with alanine (to mimic the active site of a halogenase) and with glycine. These substitutions do not, however, convert P4H into a halogenase. Moreover, the hydroxylase activity of D414A P4H cannot be rescued with small molecules. In addition, rearranging the two His and one Asp residues in the active site eliminates hydroxylase activity. Our results demonstrate a high stringency for the iron-binding residues in the P4H active site. We conclude that P4H, which catalyzes an especially demanding chemical transformation, is recalcitrant to change.     

Concurrent validity of the Microsoft Kinect for assessment of spatiotemporal gait variables

Spatiotemporal characteristics of gait such as step time and length are often associated with overall physical function in clinical populations, but can be difficult, time consuming and obtrusive to measure. This study assessed the concurrent validity of overground walking spatiotemporal data recorded using a criterion reference – a marker-based three-dimensional motion analysis (3DMA) system – and a low-cost, markerless alternative, the automated skeleton tracking output from the Microsoft Kinect™ (Kinect). Twenty-one healthy adults performed normal walking trials while being monitored using both systems. The outcome measures of gait speed, step length and time, stride length and time and peak foot swing velocity were derived using supervised automated analysis. To assess the agreement between the Kinect and 3DMA devices, Bland–Altman 95% bias and limits of agreement, percentage error, relative agreement (Pearson's correlation coefficients: r) overall agreement (concordance correlation coefficients: r_c) and landmark location linearity as a function of distance from the sensor were determined. Gait speed, step length and stride length from the two devices possessed excellent agreement (r and r_c values >0.90). Foot swing velocity possessed excellent relative (r=0.93) but only modest overall (r_c=0.54) agreement. Step time (r=0.82 and r_c=0.23) and stride time (r=0.69 and r_c=0.14) possessed excellent and modest relative agreement respectively but poor overall agreement. Landmark location linearity was excellent (R²=0.991). This widely available, low-cost and portable system could provide clinicians with significant advantages for assessing some spatiotemporal gait parameters. However, caution must be taken when choosing outcome variables as some commonly reported variables cannot be accurately measured.     

Assessment of Lower Limb Muscle Strength and Power Using Hand-Held and Fixed Dynamometry: A Reliability and Validity Study

Introduction

Hand-held dynamometry (HHD) has never previously been used to examine isometric muscle power. Rate of force development (RFD) is often used for muscle power assessment, however no consensus currently exists on the most appropriate method of calculation. The aim of this study was to examine the reliability of different algorithms for RFD calculation and to examine the intra-rater, inter-rater, and inter-device reliability of HHD as well as the concurrent validity of HHD for the assessment of isometric lower limb muscle strength and power.

Methods

30 healthy young adults (age: 23±5yrs, male: 15) were assessed on two sessions. Isometric muscle strength and power were measured using peak force and RFD respectively using two HHDs (Lafayette Model-01165 and Hoggan microFET2) and a criterion-reference KinCom dynamometer. Statistical analysis of reliability and validity comprised intraclass correlation coefficients (ICC), Pearson correlations, concordance correlations, standard error of measurement, and minimal detectable change.

Results

Comparison of RFD methods revealed that a peak 200ms moving window algorithm provided optimal reliability results. Intra-rater, inter-rater, and inter-device reliability analysis of peak force and RFD revealed mostly good to excellent reliability (coefficients ≥ 0.70) for all muscle groups. Concurrent validity analysis showed moderate to excellent relationships between HHD and fixed dynamometry for the hip and knee (ICCs ≥ 0.70) for both peak force and RFD, with mostly poor to good results shown for the ankle muscles (ICCs = 0.31–0.79).

Conclusions

Hand-held dynamometry has good to excellent reliability and validity for most measures of isometric lower limb strength and power in a healthy population, particularly for proximal muscle groups. To aid implementation we have created freely available software to extract these variables from data stored on the Lafayette device. Future research should examine the reliability and validity of these variables in clinical populations.     

地中海沿岸沙丘微生境对幼苗出现时空格局的影响

实验样地设在地中海沿岸沙丘,选择了3个不同的微生境代表：(1)稳定沙丘上的开阔地片段,(2)稳定沙丘上的灌丛下区域,(3)不稳定沙丘的路径区域;从2001年11月至2002年4月的整个生长季节,每一个微生境出现的幼苗在4个日期被监测,并在每一个取样日把每一株幼苗鉴定、计数后,用剪刀把地上部分移去;研究调查了3种微生境幼苗出现的时空分布格局,并分析了雨量与幼苗出现数量的关系。结果发现：在地中海沿岸沙丘生态系统,幼苗出现在时间上具有明显的分布特征,大多数幼苗出现在第一观测期,整个生长季幼苗都不断出现,但幼苗出现的数目却逐渐下降;各功能群的幼苗占幼苗总数的比例分别为：1年生阔叶草47．4％,多年生阔叶草2．5％,豆科植物17,0％,菊科植物14．5％,1年生禾草为11．7％,多年生禾草为1．9％,十字花科植物3．7％,伞形科植物1,4％。在空间上,总幼苗密度、物种丰富度和物种多样性等显示出重要的微生境差异,开阔地区域具有最大的幼苗密度、物种丰富度和物种多样性;3个微生境的幼苗出现不是同步的,微生境影响种子萌发的时间分布格局,灌丛下种子萌发具有滞后现象;大多数功能群的幼苗密度分布基本上具有显著的微生境差异,主要物种的幼苗分布也具有显著的微生境差异。雨量和萌发的幼苗数量间未发现显著的关系。     

Activation of transgene expression in skeletal muscle by focused ultrasound

To correlate thermal dose from focused ultrasound (FUS) with gene expression and tissue injury, a temperature plateau strategy was employed. Plasmids encoding luciferase gene under the control of hsp70B promoter were transfected into the right gastrocnemius muscle in a rat via electroporation. One day after transfection, hind limbs were treated with 3.3-MHz focused ultrasound, using one of four different temperature plateaus with spatial-peak time-average focal temperatures (T_SPTA) of 46 °C, 48 °C, 51 °C and 62 °C. The treatment duration at the plateau temperature was varied from 0 to 30 s. Gene expression was analyzed in vivo one day following FUS treatment, and H&E staining was employed to assess tissue injury. Gene activation and tissue damage correlated closely with thermal dose. The highest level of gene activation was induced by FUS at T_SPTA = 51 °C for 20 s, which was found to be statistically equivalent to that produced by water-bath hyperthermia.     

The impact of Sharav weather conditions on airborne pollen in Jerusalem and Tel Aviv (Israel)

Pollen grains have been a major focus of research mostly in temperate regions due to their effects on human health, especially allergies and asthma. The current study investigates a subtropical region characterized by a Mediterranean climate where Sharav conditions are experienced during the spring and autumn. The aim of the current study was to investigate whether Sharav conditions impacted airborne pollen concentrations of allergenic Amaranthaceae, Poaceae, Morus, Pinus, and Quercus more than standard Warm days during the main pollen seasons in the years 2010–2014 in Tel Aviv and Jerusalem (Israel). Slight variation was observed between the main pollen seasons in Tel Aviv compared to Jerusalem resulting from differences in temperature and relative humidity percentages. Additionally, more Sharav conditions occurred in Jerusalem than in Tel Aviv during the study period. The highest pollen concentrations occurred during Sharav days for Amaranthaceae, Poaceae, and Pinus but not for Morus and Quercus. Therefore, individuals who are allergic to Amaranthaceae, Poaceae, and Pinus pollen, and exposed to high pollen concentrations during Sharav days, might suffer more allergy symptoms than on Warm days.     

Comparative studies of products obtained from solvolysis liquefaction of oil palm empty fruit bunch fibres using different solvents

Solvolysis of oil palm empty fruit bunches (EFB) fibres using different solvents (acetone, ethylene glycol (EG), ethanol, water and toluene) were carried out using an autoclave at 275°C for 60 min. The solvent efficiency in term of conversion yield was found to be: EG>water>ethanol>acetone>toluene. The liquid products and residue obtained were analyzed using Fourier transform infrared spectroscopy (FTIR) and gas chromatography/mass selectivity. The obtained results showed that the chemical properties of the oil product were significantly affected by the type of solvent used for the solvolysis process. The higher heating value (HHV) of oil products obtained using ethanol is ～29.42 MJ/kg, which is the highest among the oil products produced using different solvents. Water, ethanol and toluene yield major phenolic compounds. While EG favors the formation of alcohol compounds and acetone yields ketone and aldehyde compounds.     

High frequency of plant regeneration from hypocotyl explants of Brassica carinata A. Br.

An efficient tissue culture system for high frequency of plant regeneration from hypocotyl explants of Brassica carinata was developed via manipulation of culture medium and selection of explants. Explants grown on medium containing combinations of 2 mg l^-1 BA and 0.01 mg l^-1 NAA or 4 mg l^-1 kinetin and 0.01 mg l^-1 2,4-D regenerated shoots at 100% frequency. High frequency shoot regeneration occurred only from explants originating from 6 to 7-day-old but not younger or older seedlings. Explants showed higher regeneration capacity at the distal end than the proximal end, and the upper segment was more regenerative than the lower segment of hypocotyl. Regenerants were rooted on half-strength growth regulator-free medium, acclimatized and developed into normal, fertile plants.Abbreviations BA benzyladenine - 2-4-D 2,4-dichlorophenoxyacetic acid - NAA naphthaleneacetic acid - MS Murashige & Skoog