Cellulose nanocrystal iridescence: a new model.

A homogeneous aqueous dispersion of cellulose nanocrystals (CNs) that is left to evaporate in a Petri dish self-organizes into smectic liquid crystals that are actually liquid multilamellar structures. As evaporation proceeds, the liquid multilamellar structures solidify to become a solid multilamellar film. Each solid lamella is in the submicrometer range, and its iridescence is easily explained by classical light interference. A careful inspection of each solid lamella revealed long, oriented arrays of colloids. Interestingly, the array orientation is generally the same for each superposed layer. This is exceptional because the stratification appears first in the liquid, and the solid colloids are formed in each stratum at the very end of the process. Our findings are supported by optical, atomic force, and electron microscope observations and by laser diffraction observations. The multilamellar solid film model is easier to engineer than the helical model currently used to explain the iridescence and optical activities of CN solid films. This new understanding should promote the industrial production of colorful CN coatings and inks as a green alternative for decades to come.

Hybrid dysgenesis in Drosophila melanogaster.

Several dysgenic traits may occur within the Drosophila melanogaster species as a result of crosses between different strains. Crossing two mutually interacting categories, named inducer and reactive, may lead, among other abnormalities, to a specific kind of female sterility that has proved useful for investigating the genetic factors involved in the interaction. The reactive state appears to result from a cytoplasmic state ultimately controlled by a chromosomal polygenic system. The inducer character is determined by a chromosomal factor that exhibits all characteristics of a transposable element. Overall, the data contribute to clarification of mutator activities in D. melanogaster and open new opportunities to investigate unusual genetic mechanisms.

Injectable chitosan-platelet-rich plasma implants to promote tissue regeneration: in vitro properties, in vivo residence, degradation, cell recruitment and vascularization.

The purpose of this study was to develop freeze-dried chitosan formulations that can be solubilized in platelet-rich plasma (PRP) to form injectable implants for tissue repair. A systematic approach to adjust formulation parameters, including chitosan number average molar mass (Mn ), chitosan concentration and lyoprotectant concentration, was undertaken to identify compositions that would rapidly (< 1 min) and completely solubilize in PRP, would have paste-like handling properties upon solubilization and coagulate rapidly (< 5 min) to form solid chitosan-PRP hybrid implants that are stable and homogenous. Freeze-dried cakes containing calcium chloride, as well as distinct chitosan Mn , chitosan concentration and lyoprotectant concentration, were prepared. PRP was used to solubilize the freeze-dried cakes and assess in vitro and in vivo performance, the latter as dorsal subcutaneous injections into New Zealand White rabbits. Freeze-dried polymer formulations containing low and medium chitosan Mn and concentrations were rapidly and completely solubilized in PRP. The paste-like chitosan-PRP mixtures coagulated quickly to form solid chitosan-PRP hybrids, which retracted much less than PRP-only controls. Homogeneous dispersion of chitosan within the hybrid clots was strongly dependent on chitosan Mn , and occurred only with medium Mn chitosan. Chitosan-PRP hybrid clots were resident subcutaneously in vivo until at least 2 weeks while PRP controls were quickly degraded in one day. Compared to PRP alone, chitosan-PRP hybrids had much greater capacity to induce local cell recruitment accompanied by angiogenesis, suggesting a strong potential for their use in regenerative medicine. Copyright © 2017 John Wiley & Sons, Ltd.

Alpha- and beta-adrenergic mediation of changes in metabolism and Na/K exchange in rat brown fat.

Double- and triple-barreled ion-sensitive microelectrodes were used to measure changes in extracellular K+ and Na+ concentrations ([K+]o, [Na+]o) in brown fat. Redox states of different respiratory enzymes were measured simultaneously in order to correlate ion movements with metabolic activity. Trains of stimuli applied to the efferent nerves evoked two distinct increases in [K+]o. A first, small, rapid increase occurred within 10 s and accompanied a first, rapid membrane depolarization. A second, slow increase of [K+]o occurred several minutes after stimulation and accompanied a second, slow depolarization. A few seconds after stimulation onset, while the membrane was repolarizing and shifts in redox states indicated increases in lipolysis and respiration, [K+]o decreased. The [K+]o decrease was accompanied by an increase in [Na+]o, and could be partly blocked by ouabain. Phentolamine, an alpha-antagonist that blocks the first depolarization, also blocked the first, rapid [K+]o increase and part of the subsequent decrease. Propranolol, a beta-antagonist, had little effect on the first depolarization and the first increase in [K+]o, but blocked part of the subsequent [K+]o decrease and the second, slow [K+]o increase. The changes in [K+]o were almost completely abolished in the presence of both antagonists. It is concluded that brown adipocytes take up K+ and simultaneously lose Na+ in response to the interaction of noradrenaline with alpha- and beta-receptors, and this indicates a very early stimulation of the Na+ pump.

Some extrachromosomal circular DNAs from Drosophila embryos are homologous to tandemly repeated genes.

In Drosophila melanogaster embryos we have identified three classes of extrachromosomal circular DNA molecules homologous to the three main families of tandemly repeated genes, 5 S, rDNA and histone. 5 S genes are present in circular multimeric molecules containing up to 16 copies of the 375(+/- 7) base-pair repeated unit. Circular molecules homologous to rDNA are also multimeric molecules, which contain up to ten copies of the 240 base-pair tandemly repeated sequence of the non-transcribed spacer. The two major genomic classes of histone units (4800 and 5000 bases) are found only as monomeric circular molecules. No circular intermediate of the I transposable element was detected in embryos laid by F1 dysgenic females produced by the I-R system of hybrid dysgenesis. As far as we know, it is the first time that genes have been identified among extrachromosomal circular molecules independently of any specific amplification phenomenon.

Non-Mendelian Female Sterility in DROSOPHILA MELANOGASTER: Principal Characteristics of Chromosomes from Inducer and Reactive Origin after Chromosomal Contamination.

Strains of Drosophila melanogaster can be divided into two main classes, inducer and reactive, in relation to non-Mendelian female sterility. The genetic element responsible for the inducer condition (I factor) is chromosomal and may be linked to any inducer-strain chromosome. Each chromosome carrying the I factor (i(+) chromosome) can produce females showing more-or-less reduced fertility when it is introduced by paternal gametes into a reactive oocyte. As long as i(+) chromosomes are transmitted through heterozygous males with reactive originating chromosomes (r chromosomes), I factor strictly follows Mendelian segregation. In contrast, in heterozygous i(+)/r females, a varying proportion of r chromosomes may acquire I factor independently of classical genetic recombination, by a process called chromosomal contamination. This paper reports investigation of the characteristics of the three kinds of chromosomes produced by females in which contamination occurs. It appears that the contaminated reactive chromosomes have irreversibly acquired I factor and behave like i(+) chromosomes, while the i(+) chromosomes used as contaminating elements and the reactive originating chromosomes that have not been contaminated have not undergone any change.

Non-mendelian female sterility in Drosophila melanogaster: hereditary transmission of I factor.

Systematic crosses between various strains of Drosophila melanogaster lead in some cases to partly sterile F1 females. Two main classes of strains, inducer and reactive, may be recognized on the basis of the fertility of F1 female progeny. Females which may show incomplete sterilty (SF female) arise only when reactive females are crossed with inducer males, other crosses, including the reciprocal, producing only fertile F1 females. SF sterility appears as the result of an interaction between two factors, R brought into the initial cross by the reactive mother and maternally inherited, and I brought by the inducer father. The present paper reports on the hereditary transmission of I factor. It is shown that when transmitted through heterozygous males, bearing chromosomes of both inducer and reactive origin, I factor may be strictly linked to any one of the three major chromosomes of inducer strains. Such chromosomes carrying I factor were called inducer chromosomes. When transmitted through heterozygous females, this Mendelian behavior fails to hold, and non-inducer chromosomes coming from reactive strains may become inducer independently of the production of recombined gametes. This phenomenon was called chromosomal contamination. This contamination occurs even between nonhomologous chromosomes.

Non-Mendelian Female Sterility in DROSOPHILA MELANOGASTER: Characterization of the Noninducer Chromosomes of Inducer Strains.

In relation to non-Mendelian female sterility, Drosophila melanogaster strains can be divided into two main classes, inducer and reactive. The genetic element responsible for the inducer condition (I factor) is chromosomal and may be linked to any inducer-strain chromosome. Each chromosome carrying the I factor (i(+) chromosome) can, when introduced by the paternal gamete into a reactive oocyte, give rise to females (denoted SF) showing more-or-less reduced fertility. As long as i(+) chromosomes are transmitted through heterozygous males with reactive originating chromosomes (r chromosomes), I factor follows Mendelian segregation patterns. In contrast, in heterozygous i(+)/r females, a varying proportion of r chromosomes may irreversibly acquire I factor, independently of classical genetic recombination, by a process called chromosomal contamination. The contaminated reactive chromosomes behave as i(+) chromosomes.-In the present paper, evidence is given that the Luminy inducer strain displays a polymorphism for two kinds of second chromosomes. Some of them are i(+), while others, denoted i(o), are unable to induce any SF sterility when introduced by paternal gametes into reactive oocytes. They are also unable to induce contamination of r chromosomes, but, like r chromosomes, they may be contaminated by i(+) chromosomes in SF or RSF females. The study of the segregation of i(+) and i(o) second chromosomes in the progeny of heterozygous Luminy males and females leads to the conclusion that on chromosome 2 of the Luminy stock the I factor is at a single locus. -X, second and third i(o) chromosomes have been found in several inducer strains. Since these chromosomes can be maintained with i(+) chromosomes in inducer strains in spite of their ability to be contaminated in RSF females, it can be concluded that chromosomal contamination does not take place in females of inducer strains. This implies that contamination occurs only in cells having cytoplasm in a reactive state.

Constraining the Sheffield dynamic global vegetation model using stream-flow measurements in the United Kingdom.

The biospheric water and carbon cycles are intimately coupled, so simulating carbon fluxes by vegetation also requires modelling of the water fluxes, with each component influencing the other. Observations of river streamflow integrate information at the catchment scale and are widely available over a long period; they therefore provide an important source of information for validating or calibrating vegetation models. In this paper, we analyse the performance of the Sheffield dynamic global vegetation model (SDGVM) for predicting river streamflow and quantifying how this information helps to constrain carbon flux predictions. The SDGVM is run for 29 large catchments in the United Kingdom. Annual streamflow estimates are compared with long time-series observations. In 23 out of the 29 catchments, the bias between model and observations is less than 50 mm, equivalent to less than 10% of precipitation. In the remaining catchments, larger errors are because of combinations of unpredictable causes, in particular various human activities and measurement issues and, in two cases, unidentified causes. In one of the catchments, we assess to what extent a knowledge of annual streamflow can constrain model parameters and in turn constrain estimates of gross primary production (GPP). For this purpose, we assume the model parameters are uncertain and constrain them by the streamflow observations using the generalized likelihood uncertainty estimation method. Comparing the probability density function of GPP with and without constraint shows that streamflow effectively constrains GPP, mainly by setting a low probability to GPP values below about 1100 g C-1 m2 yr-1 . In other words, streamflow observations allow the rejection of low values of GPP, so that the potential range of possible GPP values is almost halved.

Brown adipose tissue metabolism in streptozotocin-diabetic rats.

Defects of both diet-induced thermogenesis and cold tolerance have been reported for streptozotocin-diabetic rats. Since brown adipose tissue (BAT) is a major effector of both diet- and cold-induced thermogenesis in the rat, the possible cause of these defects was investigated by comparing BAT metabolism under basal conditions and during activation by nerve stimulation, norepinephrine (NE), or octanoate addition in both streptozotocin-diabetic rats and in controls. The following metabolic indices were measured in rat interscapular BAT (IBAT): 1) tissue composition, 2) heat production rate as measured by direct microcalorimetry, 3) redox state of flavoproteins linked to the acyl-coenzyme A dehydrogenase pathway as measured by reflection spectrometry, 4) redox state of NAD(P) as measured by surface-emitted fluorescence, and 5) fatty acid activation and beta-oxidation activities in IBAT homogenate. In streptozotocin-diabetic rats, IBAT was atrophied (DNA content unmodified, protein and lipid content decreased). The basal and NE-stimulated total heat production rates showed a 75% and 56% decrease, respectively. The specific activity of fatty acid beta-oxidation as measured by flavoprotein redox state or enzymatically was decreased by 52% and 59%, respectively. The basal redox level of NAD(P) was about 3 times higher than in the controls and NE stimulation resulted in oxidation in contrast to the reduction observed in control tissues. These results show that the metabolic capacity of IBAT from streptozotocin-diabetic rats is decreased and further suggest that the reduced capacity for beta-oxidation contributes significantly to the metabolic alteration.

Determination of hydramethylnon residues in grass by liquid chromatography with confirmation by liquid chromatography/mass spectrometry.

An improved method for determination of hydramethylnon residues in pasture grass is described. The method uses (1) the hydrochloride salt of hydramethylnon to improve its water solubility and (2) an acid-methanol precipitation to remove chlorophylls while leaving the analyte in solution. The liquid chromatographic method has a validated sensitivity of 0.05 ppm with controls showing < 0.004 ppm. The overall average recovery from 0.05 to 0.50 ppm was 98%, with a standard deviation of 11%. Samples showing a positive response (0.05 ppm or higher) and requiring mass spectrometric confirmation are directly amenable to liquid chromatography/mass spectrometry without additional sample preparation.

Capillary electrophoresis determinative and LC-MS confirmatory method for screening selected imidazolinone herbicides from soil.

Residues of imazapyr, imazamox, imazapic, imazethapyr, imazaquin, and imazamethabenz (meta and para) are extracted from soil with 0.5 N sodium hydroxide. The pH is adjusted to 2.0-2.2, and the resulting precipitate is filtered. Compounds are trapped onto a tC18 solid-phase extraction (SPE) cartridge, then eluted from the cartridge and passed through a strong anion exchange (SAX) SPE cartridge onto a benzenesulfonic acid strong cation exchange (SCX) cartridge using ethyl acetate. After eluting the analytes from the SCX cartridge using saturated potassium chloride in methanol, the solution is evaporated and redissolved in 1% formic acid in water. The sample is then desalted using a tC18 SPE cartridge and eluted with methanol. After evaporating the methanol to dryness, the compounds are partitioned from acidic solution (pH 3.5) into methylene chloride. The methylene chloride is evaporated to dryness and the residues are then dissolved in Milli-Q water (Millipore, Bedford, MA, U.S.A.) in preparation for analysis by capillary electrophoresis. Results are calculated by direct comparison of the sample peak heights to the peak heights of bracketing standards. The validated sensitivity of the method (LOQ, limit of quantitation) is 2.0 ppb for each compound. Confirmation for individual residues greater than 2.0 ppb is provided by liquid chromatography-electrospray ionization mass spectrometry (LC-ESMS) of the final extract.

[Preventive use of antibiotics in surgery: a review]. / Antibiotikaprophylaxe in der Chirurgie: eine Ubersicht.

As a rule, prophylactic antibiotics should only be given pre- or perioperatively as a single shot. Cephalosporins of the first and second generation are still quite effective and appear to be the most widely used drugs for this purpose. In some cases a second drug, like i.e. metronidazole, can be added. For each surgical specialty, the most appropriate prophylactic regimen is discussed.

[Antibiotic therapy in ambulatory surgery]. / Zur Antibiotikatherapie in der ambulanten Chirurgie.

Antibiotic therapy in outpatient surgical care is reviewed. In the first section some skin and soft-tissue infections are discussed, where antibiotics are likely to achieve clinical cure. In the second section we examine, where surgical treatment alone is essential for successful eradication of the infection. Wound management, where antibiotics are still controversial, is mentioned in the last section. Some pharmacological data on the discussed antibiotics are given.

Assessment of in vitro pharmacological effect of Neotropical Piperaceae in GABAergic bioassays in relation to plants traditionally used for folk illness by the Yanesha (Peru).

ETHNOPHARMACOLOGICAL RELEVANCE: A previous pilot ethnobotanical and ethnopharmacological study with the Q'echi׳ Maya identified the family Piperaceae, as an important taxonomic group traditionally used for the treatment of epileptic and culture-bound anxiety disorders and possessing activity in the GABA system. Following that lead, a botanical survey was conducted in Peru, where 47 species of Piperaceae were collected including 21 plants traditionally used for folk illnesses by the Yanesha of Peru, an indigenous Amazonian group. MATERIALS AND METHODS: Two high throughput bioassays were used to quantify the in vitro activity of botanical extracts on the GABA system. RESULTS: Plant extracts demonstrated moderate to high affinity to the γ-aminobutyric acid benzodiazepine (GABA-BZD) receptor. In addition, extracts demonstrated low to moderate activity in the inhibition of the GABA-transaminase, with select plants exhibiting significant activity. Plants indicated by the Yanesha showed comparable activity to the other Piperaceae plants collected. Piper cremii was the most active plant in the GABA-BZD receptor assay, and Drymaria cordata (Caryophyllaceae) in the GABA-T assay. CONCLUSION: The study provides evidence that there is a pharmacological basis behind the use of plants in the treatment of susto and mal aire in both Central and South America, and we propose that the possible mechanism of action includes an interaction with the GABA-T enzyme and/or the GABAA-BZD receptor.

[A partially inheritable aging influence on a non-Mendelian female sterility in Drosophila melanogaster]. / Mise en évidence d'une influence partiellement héritable de l'âge sur un phénomène de stérilité femelle à déterminisme non mendélien chez Drosophila melanogaster

Some crosses between strains of Drosophila melanogaster give rise to F1 females, which display a quite characteristic kind of incomplete sterility (S.F. females). The sterility appears to result from the interaction between two factors, "I" brought by the male parent, "R" by the female parent, neither of which behave like classical mendelian genes. In this paper, results are presented which demonstrate that the level of sterility of an S.F. female depends on the age of its maternal ancestors. Therefore, aging of a reproducing female induces variations in the "R" factor which are inherited and behave like "dauermodifikation".

Identification of short tandemly repeated sequences in extrachromosomal circular DNAs from Drosophila melanogaster embryos.

A sequence (scl) belonging to the recently identified dodeca satellite family was found to be a major family of extrachromosomal circular DNA molecules from Drosophila melanogaster embryos. The basic unit consists of the 11-bp repeat 5' ACTGGTCCCGT 3', is 63% G + C rich, and shares some similarity with the Escherichia coli chi sequence. This family accounts for only about 0.06% of the genome but very likely for a higher proportion of the circular DNA molecules. It is organized in the genome into at least five main clusters contained in DNA fragments larger than 20 kb and several minor clusters. These clusters are located in the heterochromatic pericentromeric regions. Two other families of simple repeated sequences, the 1.686 g/cm3 (5' AATAACATAG 3') and the 1.705 g/cm3 (5' AAGAG 3') satellite DNAs, were also found in circular DNAs, while another family, the 1.672 g/cm3 (5' AATAT 3'), was not detected. The representation of the simple repeated sequences in circular molecules is not correlated to their genomic representation. Among the seven families of sequences identified to date in extrachromosomal circular DNAs from embryos, the dodeca satellite, the 240-bp repeat of the rDNA intergenic spacer, and the 1.688 and 1.705 g/cm3 satellite DNAs are the most represented families, while the 5S genes, the histone genes, and the 1.686 g/cm3 satellite DNA are present in a lower amount.