Nanoparticles as smart treatment-delivery systems in plants: assessment of different techniques of microscopy for their visualization in plant tissues

BacKGROUND AND AIMS: The great potential of using nanodevices as delivery systems to specific targets in living organisms was first explored for medical uses. In plants, the same principles can be applied for a broad range of uses, in particular to tackle infections. Nanoparticles tagged to agrochemicals or other substances could reduce the damage to other plant tissues and the amount of chemicals released into the environment. To explore the benefits of applying nanotechnology to agriculture, the first stage is to work out the correct penetration and transport of the nanoparticles into plants. This research is aimed (a) to put forward a number of tools for the detection and analysis of core-shell magnetic nanoparticles introduced into plants and (b) to assess the use of such magnetic nanoparticles for their concentration in selected plant tissues by magnetic field gradients. METHODS: Cucurbita pepo plants were cultivated in vitro and treated with carbon-coated Fe nanoparticles. Different microscopy techniques were used for the detection and analysis of these magnetic nanoparticles, ranging from conventional light microscopy to confocal and electron microscopy. KEY RESULTS: Penetration and translocation of magnetic nanoparticles in whole living plants and into plant cells were determined. The magnetic character allowed nanoparticles to be positioned in the desired plant tissue by applying a magnetic field gradient there; also the graphitic shell made good visualization possible using different microscopy techniques. CONCLUSIONS: The results open a wide range of possibilities for using magnetic nanoparticles in general plant research and agronomy. The nanoparticles can be charged with different substances, introduced within the plants and, if necessary, concentrated into localized areas by using magnets. Also simple or more complex microscopical techniques can be used in localization studies.     

Fabrication and Characterization of a Conformal Skin-like Electronic System for Quantitative,Cutaneous Wound Management

Recent advances in the development of electronic technologies and biomedical devices offer opportunities for non-invasive, quantitative assessment of cutaneous wound healing on the skin. Existing methods, however, still rely on visual inspections through various microscopic tools and devices that normally include high-cost, sophisticated systems and require well trained personnel for operation and data analysis. Here, we describe methods and protocols to fabricate a conformal, skin-like electronics system that enables conformal lamination to the skin surface near the wound tissues, which provides recording of high fidelity electrical signals such as skin temperature and thermal conductivity. The methods of device fabrication provide details of step-by-step preparation of the microelectronic system that is completely enclosed with elastomeric silicone materials to offer electrical isolation. The experimental study presents multifunctional, biocompatible, waterproof, reusable, and flexible/stretchable characteristics of the device for clinical applications. Protocols of clinical testing provide an overview and sequential process of cleaning, testing setup, system operation, and data acquisition with the skin-like electronics, gently mounted on hypersensitive, cutaneous wound and contralateral tissues on patients.     

基因治疗在慢性难愈创面的应用进展

众多疾病和创伤都会带来损伤创面的难愈问题,慢性难愈创面的长期存在不仅增加了局部感染的机会,而且大大影响了局部组织的结构和功能。基因治疗作为一种新的生物治疗方法,其相关理论和技术近来日臻完善,为慢性难愈创面的治疗提供了新的技术途径,有望带来突破性的治疗效果。     

The Effects of Sericin Cream on Wound Healing in Rats

Sericin has good hydrophilic properties, compatibility, and biodegradation, it can be used as a wound-healing agent. We evaluated the effects of sericin on wound healing and wound size reduction using rats by generating two full-thickness skin wounds on the dorsum. Group 1 animals were treated with Betadine^® on left-side (control) wounds and, with 8% sericin cream on right-side (treated) wounds. Group 2, cream base (formula control) and 8% sericin cream (treated) were topically applied to left-, and right-side wounds respectively. Sericin-treated wounds had much smaller inflammatory reactions, and wound-size reduction was much greater than in the control throughout the inspection period. Mean time in days for 90% healing from sericin-treated wounds was also much less than for cream base-treated wounds. Histological examination after 15 d of treatment with 8% sericin cream revealed complete healing, no ulceration, and an increase in collagen as compared to cream base-treated wounds, which showed some ulceration and acute inflammatory exudative materials.     

Adriamycin release from poly(lactide-coglycolide)-polyethylene glycol nanoparticles: synthesis, and in vitro characterization

The preparation, properties, and application in adriamycin delivery ofbiocompatible and biodegradable poly(lactide-co-glycolide)-polyethylene glycol (PLGA-PEG) nanoparticles are discussed. PLGA-PEG copolymers were synthesized by ring opening polymerization of the dl-lactide and glycolide in the presence of PEG1000. 1H-NMR and FT-IR spectrum were consistent with the structure of PLGA-PEG copolymers. The adriamycin-loaded nanoparticles could be prepared using a precipitation-solvent evaporation technique. The nanoparticles have been produced by a precipitation-solvent evaporation technique. The physical characteristics and drug loading efficiency of the PLGA-PEG nanoparticles were influenced by the composition of the PLGA-PEG copolymers used to prepare the nanoparticles. Particle sizes were between 65 and 100 nm for different compositions of PLGA-PEG copolymers. PLGA-PEG nanoparticles prepared from copolymers having relatively high PLGA/PEG ratios were smaller. Entrapment efficiency was 25%-33%. Adriamycin release from the nanoparticles at pH 7.4 showed an initial burst release and then sustained release phase. These results showed that PLGA-PEG nanoparticles could be an effective carrier for cancer therapy.     

Quantitative determination of the antitumor alkyl ether phospholipid edelfosine by reversed-phase liquid chromatography-electrospray mass spectrometry: application to cell uptake studies and characterization of drug delivery systems

Edelfosine is a synthetic alkyl ether phospholipid that represents a promising class of antitumor agents. However, analytical methods to measure these type compounds are scarce. The lack of a reliable methodology to quantify edelfosine is a major problem in ongoing and scheduled preclinical and clinical trials with this drug. We evaluated the applicability of high-performance liquid chromatography-mass spectrometry to determine edelfosine in biological samples and polymeric delivery systems. Sample pre-treatment involved polymer precipitation or cell lysis with methanol. HPLC separation was performed on an Alltima RPC(18) narrow-bore column and edelfosine quantification was done by electrospray ionization mass spectrometry (ESI-MS) using positive ion mode and selected ion monitoring. Assays were linear in the tested range of 0.3-10 microg/ml. The limit of quantification was 0.3 ng/sample in both matrices, namely biological samples and polymeric delivery systems. The interassay precision ranging from 0.79 to 1.49%, with relative errors of -6.7 and 12.8%. Mean extraction recovery was 95.6%. HPLC-ESI-MS is a reliable system for edelfosine analysis and quantification in samples from different sources, combining advantages of full automation (rapidity, ease of use, no need of extensive extraction procedures) with high analytical performance and throughput.     

The lactate conundrum in wound healing: Clinical and experimental findings indicate the requirement for a rapid point-of-care diagnostic

The increasing prevalence of chronic wounds has significant financial implications for nations with advanced healthcare provision. Although the diseases that predispose to hard‐to‐heal wounds are recognized, their etiology is less well understood, partly because practitioners in wound management lack specialized diagnostic support. Prognostic indicators for healing may be inherent to wound biochemistry but remain invisible under routine clinical investigation; lactate is an example of this. In this study, lactate concentration in exudate obtained from 20 patients undergoing wound management in hospital was variable but in some cases approached or exceeded 20 mM. In vitro viability studies indicated that fibroblasts and endothelial cells tolerated low levels of lactate (1–10 mM), but cell viability was severely compromised by high lactate concentrations (=20 mM). Scratched monolayer experiments revealed that cell migration was affected earlier than viability in response to increasing lactate dose, and this was shown by immunocytochemistry to be associated with cytoskeletal disruption. A prototype enzyme‐based colorimetric assay for lactate generating a color change that was rapid in the context of clinical practise, and capable of functioning within a gel vehicle, was developed with point‐of‐care dipstick applications in mind. A randomized single‐blinded trial involving 30 volunteers and using a color chart to calibrate the assay demonstrated that lactate concentration could be reliably estimated with 5 mM precision; this suggesting that “physiological” and “pathological” lactate concentration could be distinguished. The present data suggest that a dipstick‐type colorimetric assay could comprise a viable diagnostic tool for identifying patients at‐risk from high‐wound lactate. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 28: 917–924, 2012     

Calorimetric study on pH-responsive block copolymer grafted lipid bilayers: rational design and development of liposomes

This study is focused on chimeric advanced drug delivery nanosystems and specifically on pH-sensitive liposomes, combining lipids and pH-responsive amphiphilic block copolymers. Chimeric liposomes composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and two different forms of block copolymers, i.e. poly(n-butylacrylate)-b-poly(acrylic acid) (PnBA-b-PAA) at 70 and 85% content of PAA at six different molar ratios, each form respectively. PAA block exhibits pH-responsiveness, because of the regulative group of –COOH. –COOH is protonated under acidic pH (pK_a ca. 4.2), while remains ionized under basic or neutral pH, leading to liposomes repulse and eventually stability. Lipid bilayers were prepared composed of DPPC and PnBA-b-PAA. Experiments were carried out using differential scanning calorimetry (DSC) in order to investigate their thermotropic properties. DSC indicated disappearance of pre-transition at all chimeric lipid bilayers and slight thermotropic changes of the main transition temperature. Chimeric liposomes have been prepared and their physicochemical characteristics have been explored by measuring the size, size distribution and ζ-potential, owned to the presence of pH-responsive polymer. At percentages containing medium to high amounts of the polymer, chimeric liposomes were found to retain their size during the stability studies. These results were well correlated with those indicated in the DSC measurements of lipid bilayers incorporating polymers in order to explain their physicochemical behavior. The incorporation of the appropriate amount of these novel pH-responsive block copolymers affects thus the cooperativity, the liposomal stabilization and imparts pH-responsiveness.     

The blood-brain barrier: Structure,function and therapeutic approaches to cross it

The blood-brain barrier (BBB) is constituted by a specialized vascular endothelium that interacts directly with astrocytes, neurons and pericytes. It protects the brain from the molecules of the systemic circulation but it has to be overcome for the proper treatment of brain cancer, psychiatric disorders or neurodegenerative diseases, which are dramatically increasing as the population ages. In the present work we have revised the current knowledge on the cellular structure of the BBB and the different procedures utilized currently and those proposed to cross it. Chemical modifications of the drugs, such as increasing their lipophilicity, turn them more prone to be internalized in the brain. Other mechanisms are the use of molecular tools to bind the drugs such as small immunoglobulins, liposomes or nanoparticles that will act as Trojan Horses favoring the drug delivery in brain. This fusion of the classical pharmacology with nanotechnology has opened a wide field to many different approaches with promising results to hypothesize that BBB will not be a major problem for the new generation of neuroactive drugs. The present review provides an overview of all state-of-the-art of the BBB structure and function, as well as of the classic strategies and these appeared in recent years to deliver drugs into the brain for the treatment of Central Nervous System (CNS) diseases.     

Floating drug delivery systems: A review

The purpose of writing this review on floating drug delivery systems (FDDS) was to compile the recent literature with special focus on the principal mechanism of floatation to achieve gastric retention. The recent developments of FDDS including the physiological and formulation variables affecting gastric retention, approaches to design single-unit and multiple-unit floating systems, and their classification and formulation aspects are covered in detail. This review also summarizes the in vitro techniques, in vivo studies to evaluate the performance and application of floating systems, and applications of these systems. These systems are useful to several problems encountered during the development of a pharmaceutical dosage form. Published: October 19, 2005     

Constant Pharmacologic Effect and Chronopharmacology: Theoretical Aspects

The theoretical drug infusion rates requisite to obtain a constant pharmacologic effect are determined taking into account chronopharmacologic phenomena. The introduction of chronopharmacology into pharmacokinetic theory leads to a clocktime-dependent infusion rate. The infusion modulation depends both on type of chronophenomenon, chronopharmacokinetics or chronestesy, and plasma clearance rate of the drug. In the presence of chronestesy of a biosystem the pharmacologic effect can be maintained constant only when plasma drug clearance is fast enough to allow an adequate modulation of the plasma drug concentration. Although the established equations proceed from theoretical concept they could be useful for programming drug delivery systems.     

Constant Pharmacologic Effect and Chronopharmacology: Theoretical Aspects

The theoretical drug infusion rates requisite to obtain a constant pharmacologic effect are determined taking into account chronopharmacologic phenomena. The introduction of chronopharmacology into pharmacokinetic theory leads to a clocktime-dependent infusion rate. The infusion modulation depends both on type of chronophenomenon, chronopharmacokinetics or chronestesy, and plasma clearance rate of the drug. In the presence of chronestesy of a biosystem the pharmacologic effect can be maintained constant only when plasma drug clearance is fast enough to allow an adequate modulation of the plasma drug concentration. Although the established equations proceed from theoretical concept they could be useful for programming drug delivery systems.     

负压封闭引流技术治疗剖宫产术后切口愈合不良41例的分析

目的：探讨负压封闭引流技术在剖宫产术后切口愈合不良中的应用及疗效。方法：剖宫产术后切口愈合不良41例,其中脂肪液化35例,切口感染7例,应用负压封闭引流装置治疗3～7天后再行局部换药或二次手术缝合。结果：负压封闭引流治疗时间平均为4．15＋1．24天,之后采取换药治疗者15例,平均愈合时间14．6±3136天;采取二次手术缝合者26例,伤口均一期愈合。结论：负压封闭引流治疗剖宫产术后切口愈合不良,可明显促进肉芽组织生长,缩短创面愈合时间,同时为二次手术缝合创造条件。     

低强度激光照射对糖尿病大鼠创伤愈合的治疗效果研究

目的:低强度激光的生物效应已经得到广大科研工作者和临床医生的广泛关注,诸多研究证明低强度激光能够促进创伤组织的修复,但是其对于糖尿病创伤的组织愈合效果目前仍鲜有报道.本文旨在系统探索650 nm波长的低强度激光照射对糖尿病大鼠皮肤创伤愈合的作用效果.方法:3月龄雄性SD大鼠,腹腔注射50 mg/kg的链脲做菌素,3天后检测空腹血糖值,高于16.7mmol/L的大鼠用于实验.于48只大鼠(32只糖尿病+16只正常)的背部构建直径2 cm的圆形创伤切口,将大鼠随机分为对照组、糖尿病组、糖尿病激光治疗组,每组16只,激光组大鼠伤口每天暴露于650 nm激光下2h.每组分别于第5、12、19天处死4只大鼠,对其进行创伤愈合率和创伤表皮组织生物力学实验评估.结果:相比于对照组,糖尿病大鼠的伤口愈合速度在第5、12、19天均显著降低(P＜0.05),伤口完全愈合时间显著增加(P＜0.05),伤口抗张强度显著下降(P＜0.05).低强度激光刺激显著提高了第5、12、19天大鼠伤口的愈合速度(P＜0.05),显著降低了伤口的愈合时间(P＜0.05),显著提高了伤口抗张强度(P＜0.05).结论:650nm低强度激光能够显著加速糖尿病大鼠创伤的延迟愈合,使其愈合速度接近于正常状态的组织,该研究揭示了650nm波长下的低强度激光治疗具有良好的用于促进糖尿病患者伤口愈合临床应用前景.     

核因子-KB在腹部火器伤肠管穿透后肺组织细胞凋亡中的作用

目的：探讨腹部火器伤肠管穿透后核因子-κB在肺组织细胞凋亡中的作用,了解腹部火器伤肠管穿透后继发性肺损伤机制。方法：健康长白仔猪42头随机等分为对照组和伤后1h、2h、4h、8h、12h和24h组,实验组建立腹部火器伤肠管穿透模型后,用免疫组化图像分析法测定各组肺组织内NF-κB活性,同时用TUNEL测定肺组织细胞凋亡变化情况。结果：伤后各组肺组织内NF-κB活性明显高于对照组,并于伤后8h出现高峰。肺组织细胞凋亡指数伤后显著增高（P〈0.05）,并与NF-κB活性变化基本一致。结论：腹部火器伤肠管穿透后肺组织内NF-κB活性增强,肺细胞凋亡增多,从而继发导致肺损伤     

The mental health clinic: a new model

The role of psychiatrists into public mental health clinics has been hampered by a perceived restriction of the psychiatrist''s role to prescribing and sign-ing forms, limiting opportunities to engage in the kind of integrated care that attracted many physicians to this specialty. We propose a revision of the current model in a direction that maximizes the expertise of this specialist as well as other clinicians in the health care team. The basic unit would consist of a psychiatrist (with adequate background both in psychopharmacology and psychotherapy), an internist and four clinical psychotherapists, who may provide evidence-based treatment after the initial evaluation of the psychiatrist. Its functioning would emphasize repeated assessments, sequential combi-nation of treatments, and close coordination of team members. Re-invigorating the role of the psychiatrist in the context of a team in which role assign-ments are clear could result in better outcomes and enhanced recruitment of psychiatrists into the public sector.