Biodegradable polymeric nanospheres formed by temperature-induced phase transition in a mixture of poly(lactide-co-glycolide) and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer

The mixture of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer(F-127) and PLGA (poly(lactide-co-gycolide)) forms a liquid state above their phase transition temperatures, and the phase-separated state is induced by decreasing the temperature below the phase transition temperature. On the basis of the temperature-induced phase transition behavior in the mixture of F-127 and PLGA, a novel method for the preparation of drug-loaded PLGA nanospheres was designed and characterized by measuring the loading amount, the encapsulation efficiency, and the drug release pattern. Paclitaxel, used as a potent anticancer drug, was selected as a model drug.     

Ethylene is a positive regulator for GA<Subscript>3</Subscript>-induced male sex in<Emphasis Type="Italic"> Anemia phyllitidis</Emphasis> gametophytes

Effects of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) on the development and expression of male sex were tested using the model of the three-zonal structure of 12-day-old (15-celled) Anemia phyllitidis gametophyte. ACC at 10 M concentration enhanced the number of antheridia induced by gibberellic acid. Cytomorphological measurements showed that this effect was limited to only the antheridial region of gametophytes and depended on transverse expansion of antheridial mother cells. Time-course cytophotometrical measurements showed that this promotive effect of ACC was preceded by reorganization of nuclear chromatin and induction of DNA synthesis in nuclei in the antheridial region cells of fern gametophytes.Abbreviations ACC: 1-Aminocyclopropane-1-carboxylic acid. - CPA: Cell profile area. - GA: Gibberellin. - GA₃: Gibberellic acid. - NPA: Nuclear profile area. - TE: Tris-EDTA buffer.Communicated by D. Bartels     

Chronic Exposure of NG108-15 Cells to Amyloid β Peptide (Aβ1–42) Abolishes Calcium Influx via N-Type Calcium Channels

We investigated whether amyloid--peptide (A_1–42) has an effect on the elevations of the intracellular concentration of Ca²⁺ ions ([Ca²⁺]_i) induced by depolarizations of NG108-15 cells and on related Ca²⁺ channels. A_1–42 (10-1000 nM) had no immediate effect on depolarization-induced [Ca²⁺]_i elevations. [Ca²⁺]_i increases were slightly diminished in cells grown in the presence of 100 or 1000 nM A_1–42. Nifedipine (1 M) reduced these elevations equally in cells grown in the absence or presence of A_1–42. In contrast, the ability of -conotoxin GVIA to diminish the depolarization-induced [Ca²⁺]_i responses became lost in cells grown in the presence of 100 nM A_1–42. This indicates that the influx of calcium through the N-type Ca²⁺ channels was compromised by the chronic exposure of cells to a submicromolar concentration of A_1–42, presumably because of impairement of their function or diminished expression. This may be important in the pathogeny of Alzheimer's dementia in view of the pivotal role of N-type Ca²⁺ channels in neurotransmitter release.     

Metabolic Changes in Rat Brain After Prolonged Ethanol Consumption Measured by 1H and 31P MRS Experiments

SUMMARY 1. In vivo ¹H and ³¹P magnetic resonance spectroscopy techniques were applied to reveal biochemical changes in the rat brain caused by prolonged ethanol consumption.2. Three models of ethanol intoxication were used.3. ¹H MRS showed a significant decrease in the concentration of myo-inositol in the brain of rats fed with 20% ethanol for 8 weeks. This change is consistent with perturbances in astrocytes. On the other hand, N-acetyl aspartate and choline content did not differ from controls.4. ³¹P MRS did not reveal any significant changes in the high-energy phosphates or intracellular free Mg²⁺ content in the brain of rats after 14 weeks of 20% ethanol drinking. The intracellular pH was diminished.5. By means of a ³¹P saturation transfer technique, a significant decrease was observed for the pseudo first-order rate constant k _for of the creatine kinase reaction in the brain of rats administered 30% ethanol for 3 weeks using a gastric tube.6. The ¹H MRS results may indicate that myo-inositol loss, reflecting a disorder in astrocytes, might be one of the first changes associated with alcoholism, which could be detected in the brain by means of in vivo ¹H MRS.7. The results from ³¹P MRS experiments suggest that alcoholism is associated with decreased brain energy metabolism.8. ³¹P saturation transfer, which provides insight into the turnover of high-energy phosphates, could be a more suitable technique for studying the brain energetics in chronic pathological states than conventional ³¹P MRS.     

Evaluation of the usefulness of various PCR method variations and nucleic acid hybridization for CMV infection in immunosuppressed patients

In diagnosis of CMV infection various laboratory methods are used. The methods based on detection of viral nucleic acids have been introduced routinely in many laboratories. The aim of this study was to compare nucleic acid hybridisation method and various variants of PCR methods with respect to their ability to detect CMV DNA. The studied material comprised 60 blood samples from 19 patients including 13 renal transplant recipients and 6 with acute leukaemia. The samples were subjected to hybridisation (Murex Hybrid Capture System CMV DNA) and PCR carried out in 3 variants: with one pair of primers (single PCR), nested PCR and Digene SHARP System with detection of PCR product using a genetic probe in ELISA system. The sensitivity of the variants ranged from 10(0) particles of viral DNA in nested PCR to 10(2) in single PCR. The producer claimed the sensitivity of the hybridisation test to be 3 x 10(5) and it seems to be sufficient for detection of CMV infection. The obtained results show that sensitivity of hybridisation was comparable to that of single PCR and the possibility of obtaining quantitative results makes it superior, on efficacy of antiviral therapy, especially in monitoring CMV infection in immunossuppressed patients and in following the efficacy of antiviral treatment.     

Susceptibility to selected coagulase-negative chemotherapeutic agents of methicillin resistant staphylococci isolated from clinical materials in 1997-1998

The study was aimed at assessment of the sensitivity of methicillin-resistant coagulase-negative staphylococci isolated from clinical material in 1997/1998 to selected chemotherapeutic agents. The investigated material comprised 96 methicillin-resistant coagulase-negative staphylococci from hospital and ambulatory infections isolated during the period from April 1997 to May 1998. Species affiliation was determined by classical identification methods and commercial diagnostic tests for identification of staphylococci. Methicillin resistance was determined by agar disk-diffusion method and screening. Sensitivity to chemotherapeutics was determined by agar disk-diffusion method and agar dilution methods. All the investigated strains were sensitive to nitrofurantoin, furazolidone and vancomycin. To teicoplanin--the second glycopeptide antibiotic--84% strains were sensitive, whereas the percentages of resistant and moderately sensitive strains amounted to 5.2% and 10.4%, respectively. 85% and 82% of coagulase-negative staphylococcal strains were sensitive to fusidic acid and mupirocin. Considerable differences were noted with respect to sensitivity to aminoglycoside group antibiotics. About 35% of strains were sensitive to gentamicin, and 90% sensitive to netilmicin. Ca. 40% of coagulase-negative staphylococci were resistant both to cotrimoxazole and trimethoprim, which, in view of 98% resistance to the second component of cotrimoxazole, may be associated with the activity of only one of the components of the drug--trimethoprim.     

Preliminary estimates of the potential for carbon mitigation in European soils through no-till farming

In this paper we estimate the European potential for carbon mitigation of no-till farming using results from European tillage experiments. Our calculations suggest some potential in terms of (a) reduced agricultural fossil fuel emissions, and (b) increased soil carbon sequestration. We estimate that 100% conversion to no-till farming would be likely to sequester about 23 Tg C y^–1 in the European Union or about 43 Tg C y^–1 in the wider Europe (excluding the former Soviet Union). In addition, up to 3.2 Tg C y^–1 could be saved in agricultural fossil fuel emissions. Compared to estimates of the potential for carbon sequestration of other carbon mitigation options, no-till agriculture shows nearly twice the potential of scenarios whereby soils are amended with organic materials. Our calculations suggest that 100% conversion to no-till agriculture in Europe could mitigate all fossil fuel-carbon emissions from agriculture in Europe. However, this is equivalent to only about 4.1% of total anthropogenic CO₂-carbon produced annually in Europe (excluding the former Soviet Union) which in turn is equivalent to about 0.8% of global annual anthropogenic CO₂-carbon emissions.     

创伤性脑损伤与肠道菌群关系研究进展

创伤性脑损伤是一种高致死率的疾病，严重危害人类生命健康。肠脑轴是大脑和胃肠道系统之间主要的双向通讯途径。近年来，创伤性脑损伤与肠道菌群的相互作用关系逐渐被揭示。肠道菌群通过肠脑轴参与了创伤性脑损伤后急性病理损伤的调节过程并发挥重要作用。本文综述了创伤性脑损伤的发生、对人类健康的巨大影响，肠脑轴的含义及其在颅脑损伤中的病理调节机制，并在此基础上提出可能的治疗手段，包括粪便微生物菌群移植、使用益生菌、刺激迷走神经、摄入多酚类物质以及靶向免疫调节策略，以期为临床治疗创伤性脑损伤提供新的思路。     

Effects of fine‐scale genetic structure on male mating success in gynodioecious Beta vulgaris ssp. maritima

Plant mating systems are known to influence population genetic structure because pollen and seed dispersal are often spatially restricted. However, the reciprocal outcomes of population structure on the dynamics of polymorphic mating systems have received little attention. In gynodioecious sea beet (Beta vulgaris ssp. maritima), three sexual types co‐occur: females carrying a cytoplasmic male sterility (CMS) gene, hermaphrodites carrying a non‐CMS cytoplasm and restored hermaphrodites that carry CMS genes and nuclear restorer alleles. This study investigated the effects of fine‐scale genetic structure on male reproductive success of the two hermaphroditic forms. Our study population was strongly structured and characterized by contrasting local sex‐ratios. Pollen flow was constrained over short distances and depended on local plant density. Interestingly, restored hermaphrodites sired significantly more seedlings than non‐CMS hermaphrodites, despite the previous observation that the former produce pollen of lower quality than the latter. This result was explained by the higher frequency of females in the local vicinity of restored (CMS) hermaphrodites as compared to non‐CMS hermaphrodites. Population structure thus strongly influences individual fitness and may locally counteract the expected effects of selection, suggesting that understanding fine scale population processes is central to predicting the evolution of gender polymorphism in angiosperms.