The effect of temperature on conduction velocity in human muscle fibers

The effects of variation of intramuscular temperature (T) on conduction velocity (CV) of the action potential along single human muscle fibers of the biceps brachii was studied in situ in 15 normal volunteers (mean age 39 years, range 21–62 years). Cooling was obtained by direct application of ice over a rectangular skin region including the stimulating and recording area. The intramuscular T was monitored by a needle thermocouple (copperconstantane). In all the 24 muscle fibers studied, a linear relationship was observed between CV and T. The slopes of the regression lines, ranging between 0.190 and 0.079 m/s, were positively correlated with the starting CV at 36°C ranging between 2.2 and 5.2 m/s. If conduction changes are expressed as a percentage of the basal CV at 36°C, the CV/T coefficient is the same for all the fibers and independent of the individual CV: 3.4% of CV/°C.     

Honey: Single food stuff comprises many drugs

Honey is a natural food item produced by honey bees. Ancient civilizations considered honey as a God gifted prestigious product. Therefore, a huge literature is available regarding honey importance in almost all religions. Physically, honey is a viscous and jelly material having no specific color. Chemically, honey is a complex blend of many organic and inorganic compounds such as sugars, proteins, organic acids, pigments, minerals, and many other elements. Honey use as a therapeutic agent is as old as human civilization itself. Prior to the appearance of present day drugs, honey was conventionally used for treating many diseases. At this instant, the modern research has proven the medicinal importance of honey. It has broad spectrum anti-biotic, anti-viral and anti-fungal activities. Honey prevents and kills microbes through different mechanism such as elevated pH and enzyme activities. Till now, no synthetic compound that works as anti-bacterial, anti-viral and anti-fungal drugs has been reported in honey yet it works against bacteria, viruses and fungi while no anti-protozoal activity has been reported. Potent anti-oxidant, anti-inflammatory and anti-cancerous activities of honey have been reported. Honey is not only significant as anti-inflammatory drug that relieve inflammation but also protect liver by degenerative effects of synthetic anti-inflammatory drugs. This article reviews physico-chemical properties, traditional use of honey as medicine and mechanism of action of honey in the light of modern scientific medicinal knowledge.     

A biophysical and computational study unraveling the molecular interaction mechanism of a new Janus kinase inhibitor Tofacitinib with bovine serum albumin

The interaction of a recently certified kinase inhibitor Tofacitinib (TFB) with bovine serum albumin (BSA) has been studied, by spectroscopic and molecular docking studies. Spectrofluorimetric measurements at 3 different temperatures (288, 298, and 310 K) showed that TFB quench the intrinsic fluorescence of BSA upon forming a nonfluorescent complex. The intrinsic fluorescence data showed that TFB binds to BSA with binding constant (K _b) of approximately 10⁴M⁻¹, affirming a significant affinity of TFB with BSA. The decrease in Stern‐Volmer quenching constant with increasing temperature exhibited the static mechanism of quenching. Negative value of ΔG (−6.94 ± 0.32 kcal·mol⁻¹), ΔH (−7.87 ± 0.52 kcal·mol⁻¹), and ΔS (−3.14 ± 0.42 cal·mol⁻¹·K⁻¹) at all 3 temperatures declared the reaction between BSA and TFB to be spontaneous and exothermic. Far‐UV circular dichroism spectroscopy results demonstrated an increase in helical content of BSA in the presence of TFB. Moreover, dynamic light scattering measurements showed that TFB resulted into a decrease in the hydrodynamic radii (from 3.6 ± 0.053 to 2.9 ± 0.02 nm) of BSA. Molecular docking studies confirmed that TFB binds near site II on BSA, hydrogen bonding, and hydrophobic interaction were involved in the BSA‐TFB complex formation. The present study characterizing the BSA‐TFB interaction could be significant towards gaining an insight into the drug pharmacokinetics and pharmacodynamics and also in the direction of rational drug designing with better competence, against emerging immune‐mediated diseases, ie, alopecia and rheumatoid arthritis.     

独岛枝芽胞杆菌MCCC 1A00493产生的4-乙烯基苯酚鉴定和作用南方根结线虫特性研究

【目的】根结线虫危害严重,难防难控,前期研究发现一株深海来源的独岛枝芽胞杆菌(Virgibacillus dokdonensis) MCCC 1A00493对南方根结线虫具有良好的体外拮抗效果,本研究分离鉴定菌株发酵液中杀线虫活性物质,对其作用线虫的多种模式进行研究,为菌株有效控制植物病原线虫的应用奠定理论基础。【方法】采用硅胶柱层析和半制备高效液相色谱对独岛枝芽胞杆菌发酵上清液中的杀线虫活性物质进行分离纯化,采用液相色谱质谱联用、核磁共振对纯化物进行结构鉴定;并对其趋避、诱杀、熏杀和卵孵化抑制活性进行检测。【结果】结构鉴定确定独岛枝芽胞杆菌MCCC 1A00493发酵液中分离的杀线虫活性物质为4-乙烯基苯酚。4-乙烯基苯酚对线虫具有触杀、熏杀、卵孵化抑制和高浓度驱避低浓度引诱活性,15μg/mL 4-乙烯基苯酚72 h触杀线虫校正死亡率为71.23%±9.06%;20 mg/mL 4-乙烯基苯酚24 h熏杀线虫死亡率达100%;100μg/mL4-乙烯基苯酚作用线虫卵10d后,卵孵化抑制率达66.2%;在琼脂平板上,10mg/mL的4-乙烯基苯酚对线虫有驱避作用,1 mg/mL的4-...     

The Analysis of Partial Diallel Crosses

The analysis of offsprings from the partial diallel crosses is presented. In considered type of crossing, p parental forms into H separate groups are devided. Single crosses among parental forms, from separate groups only, are performed. The analysis for experiments laid out in efficiency balanced block designs is given.     

Early oviposition experience affects patch residence time in a foraging parasitoid

Parasitoids learn olfactory and visual cues that are associated with their hosts, and use these cues to forage more efficiently. Classical conditioning theory predicts that encounters with high-quality hosts will lead to better learning of host-associated cues than encounters with low-quality hosts. We tested this prediction in a two-phase laboratory experiment with the parasitoid Trichogramma thalense Pinto & Oatman (Hymenoptera: Trichogrammatidae) and the host Anagasta kuehniella Zeller (Lepidoptera: Pyralidae).Host quality during the first exposure to hosts affected later foraging behavior for some experimental treatments, as predicted. We used a learning model, followed by patch-time optimization, to interpret our findings. We first simulated the parasitoids' host encounters during the experiment, and predicted their estimate of patch quality after each encounter. We then used dynamic optimization to predict the parasitoids' optimal patch residence times. The model reproduces the trends of the experimental results.     

The role of phosphorylation in the α-adrenergic-mediated inhibition of rat hepatic pyruvate kinase

Phenylephrine in the presence of 1-methyl-3-isobutylxanthine and propanolol caused a 40–50% inhibition of pyruvate kinase (type L) activity in isolated hepatocytes, which was accompanied by a 2–3-fold increase in the phosphate content of the enzyme. These changes were blocked by the α-adrenergic antagonist dihydroergocryptine and could not be accounted for by the slight increase in cyclic AMP-dependent protein kinase activity generated by the α-adrenergic agonist. It is concluded that a significant component of the inhibition of hepatic pyruvate kinase mediated by α-adrenergic agonists can be attributed to a cyclic AMP-independent alteration in the phosphorylation state of the enzyme.     

MV-mimicking micelles loaded with PEG-serine-ACP nanoparticles to achieve biomimetic intra/extra fibrillar mineralization of collagen in vitro

Since their discovery, matrix vesicles (MVs) containing minerals have received considerable attention for their role in the mineralization of bone, dentin and calcified cartilage. Additionally, MVs' association with collagen fibrils, which serve as the scaffold for calcification in the organic matrix, has been repeatedly highlighted. The primary purpose of the present study was to establish a MVs–mimicking model (PEG-S-ACP/micelle) in vitro for studying the exact mechanism of MVs-mediated extra/intra fibrillar mineralization of collagen in vivo. In this study, high-concentration serine was used to stabilize the amorphous calcium phosphate (S-ACP), which was subsequently mixed with polyethylene glycol (PEG) to form PEG-S-ACP nanoparticles. The nanoparticles were loaded in the polysorbate 80 micelle through a micelle self-assembly process in an aqueous environment. This MVs–mimicking model is referred to as the PEG-S-ACP/micelle model. By adjusting the pH and surface tension of the PEG-S-ACP/micelle, two forms of minerals (crystalline mineral nodules and ACP nanoparticles) were released to achieve the extrafibrillar and intrafibrillar mineralization, respectively. This in vitro mineralization process reproduced the mineral nodules mediating in vivo extrafibrillar mineralization and provided key insights into a possible mechanism of biomineralization by which in vivo intrafibrillar mineralization could be induced by ACP nanoparticles released from MVs. Also, the PEG-S-ACP/micelle model provides a promising methodology to prepare mineralized collagen scaffolds for repairing bone defects in bone tissue engineering.