The presence of a non-B-Z-structure enhances an enzyme's reactivity at its recognition site

Alternating (CG) sequences form an unusual conformation in the presence of cobalt hexamine. The oligomer, BZ-IV, containing a (CG)4 run (BZ-IV sequence: 5'TCGACGCGCGCGATCAGTCA- 3') was inserted at the Sal I site of the Escherichia coli pGEM-5zf(+) plasmid producing the plasmid pCW001. Hinf I digestion of pCW001 produced a 367 base pair (bp) fragment containing the BZ-IV insert. For controls, the 452 bp Hinf I fragment from the pCW001 plasmid and the 347 bp Hinf I fragment from the pGEM plasmid were used. Digestion studies were performed using the restriction enzymes Bgl I, EcoRV, Hha I, Mbo I, Not I, Pst I, and Taq I and methylation studies were performed using dam methylase. Data were obtained by beta scanning or ethidium bromide staining the polyacrylamide gels of the digestion or methylation products. The results show that in the presence of 100 uM cobalt hexamine, in which BZ-IV takes on a non-B-Z-structure, the enzyme's ability to react and cleave its recognition site is enhanced.

Heteroduplex analysis of VDJ amplified segments from rearranged IgH genes for clonality assessments in B-cell non-Hodgkin's lymphoma. A comparison between different strategies.

BACKGROUND AND OBJECTIVE: The main difficulty of PCR-based clonality studies for B-cell lymphoproliferative disorders (B-LPD) is discrimination between monoclonal and polyclonal PCR products, especially when there is a high background of polyclonal B cells in the tumor sample. Actually, PCR-based methods for clonality assessment require additional analysis of the PCR products in order to discern between monoclonal and polyclonal samples. Heteroduplex analysis represents an attractive approach since it is easy to perform and avoids the use of radioactive substrates or expensive equipment. DESIGN AND METHODS: We studied the sensitivity and specificity of heteroduplex PCR analysis for monoclonal detection in samples from 90 B-cell non Hodgkin's lymphoma (B-NHL) patients and in 28 individuals without neoplastic B-cell disorders (negative controls). Furthermore, in 42 B-NHL and in the same 28 negative controls, we compared heteroduplex analysis vs the classical PCR technique. We also compared ethidium bromide (EtBr) vs. silver nitrate (AgNO(3)) staining as well as agarose vs. polyacrylamide gel electrophoresis (PAGE). RESULTS: Using two pair consensus primers sited at VH (FR3 and FR2) and at JH, 91% of B-NHL samples displayed monoclonal products after heteroduplex PCR analysis using PAGE and AgNO(3) staining. Moreover, no polyclonal sample showed a monoclonal PCR product. By contrast, false positive results were obtained when using agarose (5/28) and PAGE without heteroduplex analysis: 2/28 and 8/28 with EtBr and AgNO(3) staining, respectively. In addition, false negative results only appeared with EtBr staining: 13/42 in agarose, 4/42 in PAGE without heteroduplex analysis and 7/42 in PAGE after heteroduplex analysis. INTERPRETATION AND CONCLUSIONS: We conclude that AgNO(3) stained PAGE after heteroduplex analysis is the most suitable strategy for detecting monoclonal rearrangements in B-NHL samples because it does not produce false-positive results and the risk of false-negative results is very low.

The effects of PVP(FE(III)) catalyst and polymer molecular weight on gene delivery via biodegradable crosslinked polyethylenimine

Human gene therapy has faced many setbacks due to the immunogenicity and oncogenity of viruses. Safe and efficient alternative gene delivery vehicles are needed to implement gene therapy in clinical practice. Polymeric vectors are an attractive option due to their availability, simple chemistry, and low toxicity and immunogenicity. Our group has previously reported biodegradable polyethylenimines (PEI) that show high transfection efficiency and low toxicity by cross-linking 800 Da PEI with diacrylate cross-linkers using Michael addition. However, the synthesis was difficult to control, inconsistent, and resulted in polymers with a narrow range of molecular weights. In the present work, we utilized a heterogenous PVP(Fe(III)) catalyst to provide a more controllable PEI crosslinking reaction and wider range of biodegradable PEIs. The biodegradable PEIs reported here have molecular weights ranging from 1.2 kDa to 48 kDa, are nontoxic in MDA-MB-231 cells, and show low toxicity in HeLa cells. At their respective optimal polymer:DNA ratios, these biodegradable PEIs demonstrated about 2-5-fold higher transfection efficiency and 2-7-fold higher cellular uptake, compared unmodified 25 kDa PEI. The biodegradable PEIs show similar DNA condensation properties as unmodified PEI but more readily unpackage DNA, based on ethidium bromide exclusion and heparan sulfate competitive displacement assays, which could contribute to their improved transfection efficiency. Overall, the synthesis reported here provides a more robust, controlled reaction to produce cross-linked biodegradable PEIs that show enhanced gene delivery, low toxicity, and high cellular uptake and can potentially be used for future in vivo studies.

Desenvolvimento de sistema automatizado para o monitoramento da degradação de resíduos de brometo de etídio

Tese (doutorado)—Universidade de Brasília, Instituto de Química, Programa de Pós-Graduação em Química, 2015.

Investigation of H19/RsaI Polymorphism in Children With Low Birth Weight in Pernambuco, Brazil

Background: H19 is a strong candidate gene for influencing birth weight variation and is exclusively imprinted maternally. In an attempt to understand the relationship of this gene polymorphism with low birth weight children, we investigated association of H19/RsaI polymorphism with low birth weight and normal birth weight in children and their mothers. Objectives: The aim of our study was to establish the association between H19 gene polymorphism and LW in children born in Pernambuco, state of Brazil. Patients and Methods: It were selected 89 children, 40 low birth weight (LW) and 49 normal birth weight (NW) and 71 mothers (40 mothers of newborns NW and 31 mothers of newborns LW) attended at Dom Malan Hospital, Petrolina, Pernambuco - Brazil. Peripheral blood samples were collected from patients and genomic DNA was extracted and detected by electrophoresis agarose gel, stained by Blue Green Loading Dye. DNA PCR amplification was done using the primers H1 (sense) and H3 (antisense). PCR products were digested with RsaI and electrophoresed on agarose gel stained by ethidium bromide. Statistical analyses were performed using the program BioEstat version 5.0. Results: The RsaI polymorphism in the H19 gene showed that genotype frequencies did not differ statistically between low birth weight (AA = 12.5%, AB = 45%, BB = 42.5%) and control (AA = 8.6% AB = 36.73%, BB= 55.10% groups) and the allele frequencies were not significantly different (P = 0.2897). We also did not observe any association between maternal H19 allele polymorphism and low birth weight newborns (P =0.7799) or normal birth weight children (P = 0.8976). Conclusions: The small size of sample may be the explanation for these results; future studies with more patients are needed to confirm the effect of H19/RsaI polymorphism on birth weight of LW newborns.

Effect of external high pressures on the clay mineral sodium montmorillonite intercalated with methylated octadecylammonium bromide surfactants

Raman microprobe spectra of the clay mineral Wyoming SWy-2-sodium montmorillonite intercalated with the surfactants, methyltrioctadecylammonium bromide (TOMA) dimethyldiotadecylammonium bromide (DODMA) and octadecyl-trimethylammonium bromide (ODTMA), have been measured in the CH2 stretching region at external pressures up to ~40 kbar with the aid of a diamond-anvil cell. In the case of the intercalated clays containing TOMA and DODMA, the Raman data afford evidence for gauche to trans conformational changes in the orientation of the CH2 chains in the surfactants with increasing pressure. These conformational changes are reversed completely upon the release of pressure.

Exploiting the 1,2,3-triazolium motif in anion-templated formation of a bromide-selective rotaxane host assembly

Stimulated by the efficacy of copper (I) catalysed Huisgen-type 1,3-dipolar cycloaddition of terminal alkynes and organic azides to generate 1,4-disubstituted 1,2,3-triazole derivatives, the importance of ‘click’ chemistry in the synthesis of organic and biological molecular systems is ever increasing.[1] The mild reaction conditions have also led to this reaction gaining favour in the construction of interlocked molecular architectures.[2-4] In the majority of cases however, the triazole group simply serves as a covalent linkage with no function in the resulting organic molecular framework. More recently a renewed interest has been shown in the transition metal coordination chemistry of triazole ligands.[3, 5, 6] In addition novel aryl macrocyclic and acyclic triazole based oligomers have been shown to recognise halide anions via cooperative triazole C5-H….anion hydrogen bonds.[7] In light of this it is surprising the potential anion binding affinity of the positively charged triazolium motif has not, with one notable exception,[8] been investigated. With the objective of manipulating the unique topological cavities of mechanically bonded molecules for anion recognition purposes, we have developed general methods of using anions to template the formation of interpenetrated and interlocked structures.[9-13] Herein we report the first examples of exploiting the 1,2,3-triazolium group in the anion templated formation of pseudorotaxane and rotaxane assemblies. In an unprecedented discovery the bromide anion is shown to be a superior templating reagent to chloride in the synthesis of a novel triazolium axle containing [2]rotaxane. Furthermore the resulting rotaxane interlocked host system exhibits the rare selectivity preference for bromide over chloride...

Thermogravimetric analysis of tetradecyltrimethylammonium bromide-modified beidellites

The surfaces of natural beidellite clay were modified with cationic surfactant, tetradecyltrimethylammonium bromide, at different concentrations. The organo-beidellites were analysed using thermogravimetric analysis which shows four thermal oxidation/decomposition steps. The first step of mass loss is observed from room temperature to 130 °C due to the dehydration of adsorbed water. The second step of mass loss between 130 and 400 °C is attributed to the oxidation step of the intercalated organic surfactant with the formation of charcoal. The third mass loss happens between 400 and 500 °C which is assigned to the loss of hydroxyl groups on the edge of clays and the further oxidation step of charcoal. The fourth step is ascribed to the loss of structural OH units as well as the final oxidation/decomposition step of charcoal which takes place between 500 and 700 °C. Thermogravimetric analysis has proven to be a useful tool for estimating loaded surfactant amount.

Ultraviolet bands of mercury bromide

The ultraviolet bands of mercury bromide have been excited in uncondensed discharge and photographed with a quartz Littrow spectrograph. The class II system, lying between\lambda 2900 å to 2700 å, suggested byWieland as due to the triatomic molecule, has been studied in detail and ascribed to the diatomic molecule. The bands in the regionlambda 2900 å to 2770å have been analysed into two systems which may form the two components of a2 II –2 \sigma electronic transition with a2 II interval equal to 969·4 cm–1.Another system most probably due to2 \sigma–2 \sigma has been observed in the region\lambda 2770 to 2720.

Alternatives to methyl bromide for Queensland strawberry production

Alternatives to methyl bromide for Queensland strawberry production.

Stress-optical dispersion in rubidium chloride and rubidium bromide crystals

The stress-optical coefficients C = (n3/2) (q11−q12) and C′ = (n3/2)q44 of RbCl and RbBr crystals have been measured at room temperature (26°C) over the wave length range 5750-2500 A.

Low-dose methyl bromide fumigation as a quarantine disinfestation treatment for nectarines against Queensland fruit fly (Diptera:Tephritidae)

White nectarines (Prunus persica var. nucipersica) were fumigated with methyl bromide (MB) at a nominal treatment dose of 18 g m-3 at 18°C for 5 h and 30 min as a quarantine disinfestation treatment against Bactrocera tryoni, the Queensland fruit fly. Three large scale trials were conducted against each of the four immature lifestages, eggs and first, second and third instars. There were no survivors from the estimated 43,614 eggs, 41,873 first instars, 41,345 second instars and 33,549 third instars treated, thereby resulting in an efficacy of GROTERDAN99.99% mortality at the 95% confidence level for each lifestage. Of the 12 trials reported herein, the highest concentration of MB, sampled from the chamber headspace analysed by gas chromatography, was 18.7 g m-3. The maximum chamber temperature from 5 min readings was 19.7°C and the maximum fruit core temperature was 19.5°C. The treatment time for all trials was exactly 5.5 h. Thus the recommended treatment dose to disinfest nectarines from B. tryoni is 19.0 g m-3 MB at 20.0°C for 5.5 h. Fruit quality trials were conducted on white nectarines at three combinations of treatment parameters: 15 g m-3 MB at 19°C for 5.25 h; 18 g m-3 MB at 19°C for 5.5 h and 21 g m-3 MB at 19°C for 5.5 h. The fruit were stored at 0, 4 and 8 days at 4°C and 8 days at 4°C followed by 4 d at 22°C. They were then were assessed for skin colour, flesh colour, skin defects, flesh defects, fruit weight loss, flesh firmness, total soluble solids, titratable acidity and rots. There was no significant difference between untreated control and MB treated fruits in any of the parameters measured. Thus the treatments did not have adverse effects on fruit quality.

Phase behavior of concentrated aqueous solutions of cetyltrimethylammonium bromide (CTAB) and sodium hydroxy naphthoate (SHN)

We have characterized the phase behavior of mixtures of the cationic surfactant cetyltrimethylammonium bromide (CTAB) and the organic salt 3-sodium-2-hydroxy naphthoate (SHN) over a wide range of surfactant concentrations using polarizing optical microscopy and X-ray diffraction. A variety of liquid crystalline phases, such as hexagonal, lamellar with and without curvature defects, and nematic, are observed in these mixtures. At high temperatures the curvature defects in the lamellar phase are annealed gradually on decreasing the water content. However, at lower temperatures these two lamellar structures are separated by an intermediate phase, where the bilayer defects appear to order into a lattice. The ternary phase diagram shows a high degree of symmetry about the line corresponding to equimolar CTAB/SHN composition, as in the case of mixtures of cationic and anionic surfactants.

Thermal expansion of caesium bromide

The temperature variation of the coefficient of thermal expansion of caesium bromide has been computed in quasiharmonic approximation and compared with the experimental results.