Synthesis and characterization of phosphoryl-choline-capped poly(ε-caprolactone)-poly(ethylene oxide) di-block co-polymers and its surface modification on polyurethanes

By sequential ring-opening polymerization of ethylene oxide and ε-caprolactone, poly(ethylene oxide) (PEO)-poly(ε-caprolactone) (PCL) di-block co-polymers with a phosphoryl choline (PC)-terminated group were synthesized. Using FT-IR, NMR, DSC and SEC, the products were characterized and the results proved the successful synthesis of functionalized di-block co-polymer. After blending the products with polyurethane (PU) and casting the result as film, the PEO segments migrated to the surface of the blend and the PCL segments acted as an anchor to fix the co-polymer on PU matrix, while the PEO segments provided PU the hydrophibility to prevent the fibrinogen adsorption on PU. This specific di-block co-polymer and the method of processing are hoped to be applied in the biomedical field to improve the biocompatibility of polymer materials.     

Role of folic acid supplementation and/ or its absence during pregnancy on implantation of embryos – An experimental study of Wistar rats

Introduction

The present study was undertaken to know the effect of folic acid (FA) supplementation and FA absence diet during pregnancy on the number of implantation as well as their endometrial changes.

In vitro effects of folic acid on γ-glutamyltransferase and glutathione reductase activities in malignant lung and thymus tumors

In vitro effects of folic acid (10⁻⁵, 10⁻⁴, and 10⁻³ M) on activities of γ-glutamyltransferase and glutathione reductase, the enzymes involved in glutathione metabolism, were studied in tissue samples obtained after surgical treatment of the lungs and thymus. Folic acid did not change γ-glutamyltransferase activity in lung cancer tissue, but in thymoma tissue this substance in a concentration of 10⁻³ M inhibited it by 16%. Folic acid had no effects on glutathione reductase activity in benign tumors and normal lung and thymus tissues, but increased this activity in thymoma and lung cancer tissues. Activation of glutathione reductase was probably related to binding of folic acid in the allosteric center of the enzyme, which probably induced conformational changes in the catalytic center, acceleration of electron transport from NADPH₂ to oxidized glutathione via flavin adenine nucleotide, and intense production of reduced glutathione. Translated fromByulleten', Eksperimental'noi Biologii i Meditsiny, Vol. 130, No. 10, pp. 422–425, October, 2000     

Functionalization of poly-L-lactic-co-ε-caprolactone: effects of surface modification on endothelial cell proliferation and hemocompatibility

A copolymer of L-lactic acid and ε-caprolactone (PLLACL) was synthesized with the aim of preparing a bioartificial, small-diameter and partially resorbable vascular graft. The material was submitted to surface functionalizations (i.e. chemical modification by means of hydrolytic 'etching' and plasma discharge) to promote endothelial cell (EC) adhesion and growth avoiding platelet adhesion or coagulation factor absorption. Furthermore, the behaviour of human microvascular endothelial cells (HMVEC) seeded on the untreated and treated copolymer is described, as well as the platelet adhesion and the modifications of coagulation factors determined by the copolymer itself. PLLACL in its native state provided little support for EC adhesion. Improved EC adherence was obtained when functional groups were provided on the polymer surface by surface chemical hydrolysis. HMVEC seeded and cultured on the polymer surface did not show any ultrastructural alteration, thus demonstrating the absence of the polymer cytotoxicity. Moreover, SEM analysis performed on cold plasma modified specimens showed the presence of a subconfluent monolayer of EC, with an elongated spread morphology. Both the untreated and treated copolymers induced only slight variations of platelet number, but determined the activated partial thromboplastin time (APTT) increase, due to factor XI reduction. Finally,a prototype of partially biodegradable vascular prosthesis was prepared with NaOH/HCl-treated copolymer. Pre-cultured HMVEC seeding of the prosthesis by means of a rotation device resulted in an almost completely coverage of the graft inner surface.     

Construction of nano-silver coating on pure titanium surface and its antibacterial effect on staphylococcus aureus北大核心

BACKGROUND: Nano-silver is a new antibacterial material developed based on nano-technology. It is characterized as stable physical and chemical properties, and good electrical, optical, and catalytic performance, but its antibacterial response to Staphylococcus aureus is controversial. OBJECTIVE: To explore the preparation methods of nano-silver coating on pure titanium surface and to explore its antibacterial effect on Staphylococcus aureus. METHODS: (1) Preparation of nano-silver coating on the surface of pure titanium: Hydroxyapatite and silver powder as research objects were fully mixed at a ratio of 20:1. The mixture was ball-milled to ensure the formation of nanosized particles. The mixture of hydroxyapatite and silver powder was put into a stirrer for continuous stirring to ensure the uniform distribution. The mixture was then placed in an ethanol solution followed by insertion of a titanium plate (anode) and a stainless steel plate (cathode). The precipitated powder was obtained on the titanium surface at a voltage of 20 V, and the pure titanium surface with nano-silver coating was prepared after heat treatment in a tube resistance furnace. (2) Observation of antibacterial properties: A minimal inhibitory concentration test was used to determine the antibacterial concentration of the nano-silver coating on the pure titanium surface when shaken with Staphylococcus aureus. A scanning electron microscope was used to observe the structure of Staphylococcus aureus on the pure titanium surface with nano-silver coatings of different mass concentrations. RESULTS AND CONCLUSION: Nano-silver/hydroxyapatite composite coating and hydroxyapatite coating were relatively uniform. The nano-silver/hydroxyapatite composite coating was white in color but slightly yellowish. The hydroxyapatite coating was white in color. The coating surface was rough and bonded firmly. No peeling of the coating was observed under gross observation. The antibacterial ability of the nano-silver group at 37°C static culture and at 37 ° shaking culture was significantly higher than that of the hydroxy-apatite group (P < 0.05). The absorbance value of Staphylococcus aureus at 600 nm in the nano-silver group was lower than that of hydroxyapatite group at 7, 10, 30 hours after intervention (P < 0.05). The layer cells on the nano-silver coating become lighter in color compared with those on the hydroxyapatite coating and there were cells that ruptured and died. The number of Staphylococcus aureus on the nano-silver coating was reduced, and a large number of vacuoles were found. These findings indicate that the 20:1 mixture of hydroxyapatite and silver at micron level can be used to prepare nano-silver coating through ball milling, water bath, ultrasound and heat treatment. The prepared coating can exert excellent antibacterial effects on Staphylococcus aureus. © 2018, Journal of Clinical Rehabilitative Tissue Engineering Research. All rights reserved.     

Antineoplastic activity of γ-linolenic acid extract from Spirulina platensis on HepG2 cells and its inhibition effect on platelet aggregation

Spirulina platensis (SP) is well recognised for its abundant unsaturated fatty acids, especially γ-linolenic acid (GLA). In this study, GLA was extracted from SP. Antineoplastic and antithrombotic activities of GLA were evaluated by measuring the concentrations of reactive oxygen species (ROS) and malondialdehyde, as well as inducing apoptosis in HepG2 human hepatoma cells and diphosphatase-induced platelet aggregation inhibition assay, respectively. The study suggests that the GLA extraction from SP using ethanol achieved a higher extraction yield of 8.3 g kg^?1 ± 0.17 g kg^?1 (GLA/dry biomass) and inhibited cell proliferation in a dose- and time-dependent manner. GLA extract (250 µM) strongly induced ROS generation and lipid peroxidation as well as apoptosis. The extract also caused a concentration-dependent antithrombotic effect on platelet aggregation in vitro. Thus, the GLA extract from SP can be applied in health care and functional foods.     

Physiological studies on trematodes — surface area — body weight relationship in Cotylophoron Cotylophoron and Gastrothylax Crumenifer

Summary 1. The surface area body weight relationship in C. cotylophoron and G. crumenifer has been determined.2. The relationship between surface area and body weight in C. cotylophoron was found to be governed by Y=14.67 (W ₁)^0.70 and Y=6.99 (W ₂)^0.68 and in G. crumenifer Y=7.50 (W ₁)^0.70 and Y=4.30 (W ₂)^0.76, where Y represents the surface area in sq. mm, W ₁ and W ₂ for dry and fresh weights in mg respectively.

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Zusammenfassung 1. Bei C. cotylophoron und G. crumenifer wird das Verhältnis der Oberfläche zum Körpergewicht bestimmt.2. Die Beziehung zwischen Körperoberfläche und Körpergewicht liegt bei C. cotylophoron bei etwa Y=14,67 (W ₁)^0,70 und Y=6,99 (W ₂)^0,68 und bei G. crumenifer Y=7,50 (W ₁)^0,70 und Y=4,30 (W ₂)^0,76, wo die Oberflächen in mm², W ₁ und W ₂ das Trocken- und Frischgewicht in mm angeben.

     

Cytomegalovirus — its cellular immunology and biology

The biology of persistent virus infections presents many intriguing questions, which extend well beyond classical virology into molecular and cell biology and immunology. Here, Patrick Sissons and his colleagues review the current state of knowledge of the biology and immunology of one particular medically important persistent human virus — human cytomegalovirus (HCMV) and they discuss insights into the normal and pathological virus-host relationship provided by recent work both on HCMV itself, and on its murine counterpart mouse cytomegalovirus (MCMV).     

Do multivitamin or folic acid supplements reduce the risk for congenital heart defects? Evidence and gaps

Congenital heart defects are among the most common congenital anomalies and are the leading cause of infant death due to congenital anomalies. Except for a few known measures, effective primary prevention is not yet feasible for most heart anomalies. Recent reports have associated the use of multivitamin supplements around the time of conception and during early pregnancy with a reduced risk for heart defects in the offspring. We review and discuss the evidence and suggest a framework for further investigation in this area.     

Distinctive effects of arachidonic acid and docosahexaenoic acid on neural stem /progenitor cells

Arachidonic acid (ARA) and docosahexaenoic acid (DHA), which are the dominant polyunsaturated fatty acids in the brain, have crucial roles in brain development and function. Recent studies have shown that ARA and DHA promote postnatal neurogenesis. However, the direct effects of ARA on neural stem/progenitor cells (NSPCs) and the effects of ARA and DHA on NSPCs at the neurogenic and subsequent gliogenic stages are still unknown. Here, we analyzed the effects of ARA and DHA on neurogenesis, specifically maintenance and differentiation, using neurosphere assays. We confirmed that primary neurospheres are neurogenic NSPCs and that tertiary neurospheres are gliogenic NSPCs. Regarding the effects of ARA and DHA on neurogenic NSPCs, ARA and DHA increased the number of neurospheres, whereas neither ARA nor DHA had a detectable effect on NSPCs in the differentiation condition. In gliogenic NSPCs, DHA increased the number of neurospheres, whereas ARA had no such effect. In contrast, ARA increased the number of astrocytes, whereas DHA increased the number of neurons in the differentiation condition. These results suggest that ARA promotes the maintenance of neurogenic NSPCs and might induce the glial differentiation of gliogenic NSPCs and that DHA promotes the maintenance of both neurogenic and gliogenic NSPCs and might lead to the neuronal differentiation of gliogenic NSPCs.     

Can reduced folic acid and vitamin B12 levels cause deficient DNA methylation producing mutations which initiate atherosclerosis?

Atherosclerosis of the vascular system has classically been attributed to elevated serum cholesterol concentrations. Recently, it has been found that reduced serum levels of folic acid, vitamin B12, and vitamin B6 are related to the etiology of atherosclerosis and coronary heart disease. These deficiencies lead to inadequate production of S-adenosyl-methionine, creating a condition of hypomethylation. It is hypothesized that this causes hypomethylation of the DNA in cells in the arterial intima resulting in mutation and proliferation of smooth-muscle cells which lead to the formation of atheroma. It is further hypothesized that such action can be reversed by supraphysiological doses of these three vitamins to reduce or remove existing atheroma. It is recommended that all patients suffering from atherosclerosis and having deficiencies of any of these three vitamins and/or an elevation of serum homocysteine receive supplementation to prevent worsening of their condition.     

Biocompatibility of fully biodegradable polylactic acid and its copolymers: Present and future applications北大核心

BACKGROUND: Polylactic acid and its copolymers have been widely used in biomedical fields because of their good biocompatibility and biodegradability, which have become a hotspot in the research of biomaterials. OBJECTIVE: To review the biocompatibility of fully degradable polylactic acid and its copolymers. METHODS: A computer-based online retrieval of PubMed and CNKI was performed to search relevant papers published from 2006 to 2016, with the key words of " polylactide, polylactic acid, copolymer, biodegradability, biocompatibility, animal” in English and Chinese, respectively. RESULTS AND CONCLUSION: Polylactic acid and its copolymers as polyester compounds are approved by the US Food and Drug Administration for use in the biomedical field because of their good biocompatibility mainly as drug delivery carriers and temporary implants. Moreover, their side effects in clinical application have attracted attentions. Polylactide copolymers can cause some adverse reactions when used in drug delivery systems, orthopedic and skin care, and other clinical medical fields. These copolymers are deemed to have no impact on the central nervous system, eyes, cardiovessels and other tissues and organs. They also have no virtually genotoxic and carcinogenic effects. Currently, the polylactide copolymer implant mainly results in local reactions in the surrounding tissues, and no systemic reactions have been found. © 2018, Journal of Clinical Rehabilitative Tissue Engineering Research. All rights reserved.     

Sleep and circadian rhythms in α-synucleinopathies—Perspectives for disease modification

The global north is facing an unprecedented rise in the prevalence of neurodegenerative diseases. The increasing incidence of Parkinson's disease is being referred to as a pandemic. The reason for the enormous increase is only partly understood. Lifestyle factors are known to play a role, but they alone cannot account for the surge. One factor that—although being recognized as important—has not been explored in detail so far is the influence of circadian rhythms. Sleep and circadian rhythm disruption are known as key factors in neurodegeneration, and their occurrence during early disease stages suggests a causal role in the pathogenesis. Isolated rapid eye movement (REM) sleep behavior disorder (iRBD) has been identified as a prodromal state of α-synucleinopathies, such as Parkinson's disease, Lewy body dementia, and multiple system atrophy offering a window for insights into the early development of these diseases. Even though REM sleep is the sleep state most pronounced, driven and modulated by the circadian timing system, specific circadian abnormalities have not been described in iRBD. Novel experimental and clinical approaches exploiting the molecular circuitry underlying circadian timekeeping hold promise to disentangle some of the pathophysiologic mechanisms of α-synucleinopathies. In this review, we summarize current knowledge on sleep and circadian rhythm disruptions in α-synucleinopathies with an emphasis on molecular aspects and therapeutic potentials. These insights might contribute to our understanding of the pathogenesis of neurodegenerative diseases and may allow therapeutic interventions addressing the disturbed circadian system at the early stage of disease.