Genome-wide microsatellites in amaranth: development, characterization, and cross-species transferability

Amaranth (Amaranthus spp.) belonging to Amaranthaceae, is known as "the crop of the future" because of its incredible nutritional quality. Amaranthus spp. (> 70) have a huge diversity in terms of their plant morphology, production and nutritional quality; however, these species are not well characterized at molecular level due to unavailability of robust and reproducible molecular markers, which is essential for crop improvement programs. In the present study, 13,051 genome-wide microsatellite motifs were identified and subsequently utilized for marker development using A. hypochondriacus (L.) genome (JPXE01.1). Out of those, 1538 motifs were found with flanking sequences suitable for primer designing. Among designed primers, 225 were utilized for validation of which 119 (52.89%) primers were amplified. Cross-species transferability and evolutionary relatedness among ten species of Amaranthus (A. hypochondriacus, A. caudatus, A. retroflexus, A. cruentus, A. tricolor, A. lividus, A. hybridus, A. viridis, A. edulis, and A. dubius) were also studied using 45 microsatellite motifs. The maximum (86.67%) and minimum (28.89%) cross-species transferability were observed in A. caudatus and A. dubius, respectively, that indicated high variability present across the Amaranthus spp. Total 97 alleles were detected among 10 species of Amaranthus. The averages of major allele frequency, gene diversity, heterozygosity and PIC were 0.733, 0.347, 0.06, and 0.291, respectively. Nei's genetic dissimilarity coefficients ranged from 0.0625 (between A. tricolor and A. hybridus) to 0.7918 (between A. viridis and A. lividus). The phylogenetic tree grouped ten species into three major clusters. Genome-wide development of microsatellite markers and their transferability revealed relationships among amaranth species which ultimately can be useful for species identification, DNA fingerprinting, and QTLs/gene(s) identification.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-02930-5.

Novel fluoride rechargeable dental composites containing MgAl and CaAl layered double hydroxide (LDH)

OBJECTIVE

This study aims to incorporate 2:1 MgAl and 2:1 CaAl layered double hydroxides (LDHs) in experimental dental-composites to render them fluoride rechargeable. The effect of LDH on fluoride absorption and release, and their physico-mechanical properties are investigated.

METHODS

2:1 CaAl and 2:1 MgAl LDH-composite discs prepared with 0, 10 and 30wt% LDH were charged with fluoride (48h) and transferred to deionized water (DW)/artificial saliva (AS). Fluoride release/re-release was measured every 24h (ion-selective electrodes) with DW/AS replaced daily, and samples re-charged (5min) with fluoride every 2 days. Five absorption-release cycles were conducted over 10 days. CaAl and MgAl LDH rod-shaped specimens (dry and hydrated; 0, 10 and 30wt%) were studied for flexural strength and modulus. CaAl and MgAl LDH-composite discs (0, 10, 30 and 45wt% LDH) were prepared to study water uptake (over 7 weeks), water desorption (3 weeks), diffusion coefficients, solubility and cation release (ICP-OES).

RESULTS

CaAl LDH and MgAl LDH-composites significantly increased the amount of fluoride released in both media (P<0.05). In AS, the mean release after every recharge was greater for MgAl LDH-composites compared to CaAl LDH-composites (P<0.05). After every recharge, the fluoride release was greater than the previous release cycle (P<0.05) for all LDH-composites. Physico-mechanical properties of the LDH-composites demonstrated similar values to those reported in literature. The solubility and cation release showed a linear increase with LDH loading.

SIGNIFICANCE

LDH-composites repeatedly absorbed/released fluoride and maintained desired physico-mechanical properties. A sustained low-level fluoride release with LDH-composites could lead to a potential breakthrough in preventing early stage carious-lesions.

Layered Double Hydroxide Fluoride Release in Dental Applications: A Systematic Review

This systematic review appraises studies conducted with layered double hydroxides (LDHs) for fluoride release in dentistry. LDH has been used as antacids, water purification in removing excess fluoride in drinking water and drug delivery. It has great potential for controlled fluoride release in dentistry, e.g., varnishes, fissure sealants and muco-adhesive strips, etc. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement was followed with two reviewers performing a literature search using four databases: PubMed, Web of Science, Science Direct and Ovid Medline with no date restrictions. Studies including any LDH for ion/drug release in dentistry were included, while assessing the application of LDH and the value of the methodology, e.g., ion release protocol and the LDH production process. Results: A total of 258 articles were identified and four met the inclusion criteria. Based on two in vitro studies and one clinical study, LDH was previously studied in dental materials, such as dental composites and buccal muco-adhesive strips for fluoride release, with the latter studied in a clinical environment. The fourth study analysed LDH powder alone (without being incorporated into dental materials). It demonstrated fluoride release and the uptake of volatile sulphur compounds (VSC), which may reduce halitosis (malodour). Conclusion: LDHs incorporated in dental materials have been previously evaluated for fluoride release and proven to be clinically safe. LDHs have the potential to sustain a controlled release of fluoride (or other cariostatic ions) in the oral environment to prevent caries. However, further analyses of LDH compositions, and clinical research investigating any other cariostatic effects, are required.

Development of a novel bioactive glass for air-abrasion to selectively remove orthodontic adhesives

OBJECTIVES

To develop a novel, bioactive glass for removing residual orthodontic adhesive via air-abrasion, following bracket debonding, and to evaluate its effectiveness against a proprietary bioactive glass 45S5(Sylc™)-air-abrasion, and a slow-speed tungsten carbide (TC) bur.

MATERIALS AND METHODS

Three glasses were prepared and their bioactivity was proved. One novel glass (QMAT3) was selected due to its appropriate hardness, lower than that of enamel/45S5(Sylc™). Sixty extracted human premolars were randomly assigned to adhesive removal using: (a) QMAT3-air-abrasion, (b) 45S5(Sylc™)-air-abrasion, and (c) TC bur, which were further subdivided (n = 10) based on the adhesive used (Transbond XT™ or Fuji Ortho LC™). Enamel roughness was assessed using scanning electron microscopy (SEM) and non-contact profilometry before bracket bonding, after removing residual adhesive following bracket debonding and after polishing.

RESULTS

QMAT3 formed apatite faster (6 h) than 45S5(Sylc™) (24 h) in Tris solution. QMAT3-air-abrasion gave the lowest enamel roughness (Ra) after removing the adhesives. SEM images showed a pitted, roughened enamel surface in the TC bur group and to a lesser extent with 45S5(Sylc™), while a virtually smooth surface without any damage was observed in the QMAT3-air-abrasion group. The time taken for adhesive removal with QMAT3 was comparable to 45S5(Sylc™) but was twice as long with the TC bur.

CONCLUSIONS

QMAT3-air-abrasion is a promising technique for selective removal of adhesives without inducing tangible enamel damage.

CLINICAL RELEVANCE

A novel bioactive glass has been developed as an alternative to the use of TC burs for orthodontic adhesive removal.

The properties of experimental resin-modified glass-ionomer luting cements (RMGICs) containing novel monomers

OBJECTIVES

To investigate working and setting times, compressive fracture strength (CFS), compressive modulus (CM), three-point flexure strength (TFS) and tensile flexure modulus (TFM) of commercial, control and experimental RMGICs.

METHODS

RelyX Luting (RX, 3M-ESPE) and Fuji Plus (FP, GC), two control home liquids and eight new liquid compositions (F1-F4 and R1-R4) comprising different percentages of the monomer HPM (hydroxypropyl-methacrylate) and/or THFM (tetrahydrofurfuryl-methacrylate) with the original monomer HEMA (2-hydroxyethyl-methacrylate) were used in this study. The polymerization was initiated chemically (using benzene sulfonic acid sodium-salt in FP powder and potassium persulfate/ascorbic acid in RX powder). Home and experimental liquids were mixed with the corresponding commercial powder. An oscillating rheometer was used to measure the working and setting times (n=6). 20 cylinders per material (6.0±0.1mm height, 4.0±0.1mm diameter) were fabricated for CFS and CM testing, 20bars per material (25.0±0.1mm length, 2.0±0.1mm width, 2.0±0.1mm thickness) were made for TFS and TFM testing.

RESULTS

All RX compositions showed longer setting times (p≤0.0001) and lower CFS values compared to their FP counterparts (p≤0.0001). The TFS testing showed that commercial and home RMGICs behaved as brittle materials with linear load/deflection curve while experimental materials showed plastic ductile deformation before fracture. F3, F4 and F2 showed significantly higher CFS values compared to the corresponding home material (p≤0.0001).

SIGNIFICANCE

All new experimental compositions demonstrated working and setting times that are clinically acceptable. The new experimental FP compositions containing THFM (especially F3 and F4) demonstrated improved mechanical properties compared to their corresponding home material.

Genetic analysis of first lactation production traits in Kankrej cattle

Aim:

The aim was to estimate genetic factors affecting the first lactation milk production traits in Kankrej cattle of North Gujarat.

Materials and Methods:

The 475 first lactation records of Kankrej cows that were maintained at the Livestock Research Station, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar, Gujarat, over a period of 35 years from 1980 to 2014 were studied. The least squares maximum likelihood program was used to estimate genetic parameters of first lactation traits. Heritability was estimated through paternal half-sib analysis in adjusted data.

Results:

The heritability estimate for production traits was 0.40±0.17, 0.45±0.17, 0.35±0.18, and 0.20±0.14 for standard 300 days milk yield (F300Y), total lactation milk yield (FLY), wet average (FWA), and lactation length (FLL), respectively, in the first parity. All the genetic and phenotypic correlations among different production efficiency traits were high and positive. Genetic correlations between F300Y and FLY, FLL, and FWA were 0.80±0.20, 0.59±0.16, and 0.81±0.32, where as the phenotypic correlations were 0.969, 0.688, and 0.868, respectively. Genetic correlations of FLY with FLL and FWA were 0.60±0.13 and 0.79±0.20, whereas the phenotypic correlations were 0.777 and 0.817, respectively. Genetic and phenotypic correlation between FLL and FWA was 0.63±0.28 and 0.31, respectively.

Conclusion:

The heritability estimate of all first parity lactation traits waslow to medium (0.20-0.45) indicated the scope for further improvement in this trait through selection as well as managemental practice. Higher genetic and phenotypic correlation between thefirst lactation milk production traits gives theidea that genetic gain due to selection for one trait also givesmorecorrelated response of selection for other traits which is economically advantageous.

Development of experimental resin modified glass ionomer cements (RMGICs) with reduced water uptake and dimensional change

OBJECTIVE

To investigate water uptake, desorption, diffusion coefficient, solubility and dimensional changes of four experimental RMGICs in deionized water (DW) and artificial saliva (AS), and compare with two commercial RMGICs and control home liquids based on the two commercial materials used.

METHODS

Two commercial RMGICs, RelyX Luting (RX, 3M ESPE) and Fuji Plus (FP, GC), two control home liquids and four new liquid compositions (F1, F2, R1, R2) comprising different percentages of the monomer THFM (tetrahydrofurfuryl-methacrylate) with the original monomer HEMA (2-hydroxyethyl-methacrylate) were used in this study. Home and experimental liquids were mixed with the corresponding commercial powder. Disk-shaped specimens (16mm diameter 1mm thickness) were immersed in DW/AS at 37°C (n=6) and weighed at regular time intervals. Percentage weight change with time was recorded. At 24 weeks, disks were desorbed in an oven at 37°C to minimum weight.

RESULTS

All new compositions showed lower water uptake and dimensional (volume) changes than the commercial products in both DW and AS. On desorption, FP showed higher weight loss compared to materials in the same group in both solutions (p<0.0001), with the exception of F2 in DW (p=0.283). RX had higher weight loss compared to R1 and R2 in DW and AS (p<0.0001). Fickian diffusion was confirmed for all materials immersed in DW and AS.

SIGNIFICANCE

The experimental compositions in this study have shown promising results when tested in both DW and AS with lower water uptakes and volume changes than commercial materials. This may lead to wider applications than current commercial materials.

An apparatus for spatially resolved, temperature dependent reflectance measurements for identifying thermochromism in combinatorial thin film libraries

A metrology and data analysis protocol is described for high throughput determination of thermochromic metal-insulator phase diagrams for lightly substituted VO2 thin films. The technique exploits the abrupt change in near infrared optical properties, measured in reflection, as an indicator of the temperature- or impurity-driven metal-insulator transition. Transition metal impurities were introduced in a complementary combinatorial synthesis process for producing thin film libraries with the general composition space V(1-x-y)M(x)M'(y)O2, with M and M' being transition metals and x and y varying continuously across the library. The measurement apparatus acquires reflectance spectra in the visible or near infrared at arbitrarily many library locations, each with a unique film composition, at temperatures of 1 °C-85 °C. Data collection is rapid and automated; the measurement protocol is computer controlled to automate the collection of thousands of reflectance spectra, representing hundreds of film compositions at tens of different temperatures. A straightforward analysis algorithm is implemented to extract key information from the thousands of spectra such as near infrared thermochromic transition temperatures and regions of no thermochromic transition; similarly, reflectance to the visible spectrum generates key information for materials selection of smart window materials. The thermochromic transition for 160 unique compositions on a thin film library with the general formula V(1-x-y)M(x)M'(y)O2 can be measured and described in a single 20 h experiment. The resulting impurity composition-temperature phase diagrams will contribute to the understanding of metal-insulator transitions in doped VO2 systems and to the development of thermochromic smart windows.

Metal contamination of soil and translocation in vegetables growing under industrial wastewater irrigated agricultural field of Vadodara, Gujarat, India

The present investigation was carried out to evaluate metals concentration in ten vegetable crops growing in mixed industrial effluent irrigated agricultural field near Vadodara, Gujarat, India. Differential accumulation and translocation of various metals in selected vegetables plant species was observed. A higher concentration of metals were found in order of Fe>Mn>Zn>Cd>Cu>Pb>Cr>As in soil irrigated with industrial effluent than soil irrigated with tube well water; however, the concentration of As, Cr and Pb found below detection limit in tube well water irrigated soil. Metal accumulation in root and top of vegetables varied significantly both in relations to metal concentration in the soil and the plant genotype. Among ten vegetable species studied five vegetable species, i.e. Spinach, Radish, Tomato, Chili and Cabbage growing in mixed industrial effluent irrigated agricultural field showed high accumulation and translocation of toxic metals (As, Cd, Cr, Pb and Ni) in their edible parts, thus, their cultivation are unsafe with respect to possible transfer in food chain and health hazards. However, it is suggested that vegetable crops restricting toxic metal in non-edible port may be recommended for cultivation in such metal contaminated agricultural field.

The relationship between Shore hardness of elastomeric dental materials and Young's modulus

OBJECTIVES

Hardness of elastomers can be directly related to Young's modulus, a relationship that was investigated in detail by Gent in a paper in 1958. The aim of this study was to test this relationship for 13 dental elastomers (12 silicone and 1 polyether) using the equation derived by Gent and one from BS 903 (1950) that accounts for departures at low values.

METHODS

The dental elastomers were subjected to tensile testing and Shore A scale hardness measurements. Young's moduli were calculated from the hardness values using the Gent equation and the BS 903 equation. These calculated values were then compared with values derived experimentally from the tensile tests.

RESULTS

Hardness values were in the range 30.2 (+/-0.5)-62.9 (+/-0.8) with the corresponding calculated modulus values in the range 1.1-4.1MPa and 0.9-4.3MPa for the Gent and modified equations, respectively. Young's modulus values derived from the tensile data were in the range 0.8 (+/-0.3)-4.1 (+/-0.3)MPa, showing good agreement with those calculated from the hardness values. Providing viscoelastic creep is minimal during the duration of the test, there is a reasonably well-defined relationship between Shore hardness and Young's modulus in the hardness range studied.

SIGNIFICANCE

Simple, non-destructive hardness measurements can be used to determine Young's modulus values. Such values are needed in any calculations of stress distributions in soft lining materials, e.g. by FEA.

Tablet formulation studies on an oxcarbazepine-beta cyclodextrin binary system

Oxcarbazepine is a poorly water-soluble (0.083 mg/ml) anti-epileptic drug according to the BCS system (class II) and its dissolution is rate-limiting step for its absorption. The objective of this work was to develop tablet formulations of oxcarbazepine-beta-cyclodextrin (OX-beta-CD) binary systems. Three types of binary systems--physical mixtures, kneaded systems, and coevaporated systems--were studied. Phase solubility studies indicated 1:1 M complexation of oxcarbazepine with beta-cyclodextrin. Drug-beta-CD binary systems were prepared at 1:1 molar ratios and used in formulation studies. The dissolution properties of OX-beta-CD KS (kneaded system, 100.10% drug release in 15 min) were superior than those of the other binary system and pure oxcarbazepine. The tablet formulations containing drug-beta-CD binary systems prepared by wet granulation and direct compression showed superior dissolution properties when compared with the formulations of the corresponding pure drug formulations. Tablet formulations containing drug-beta-CD binary systems prepared by the kneading method showed good dissolution properties (100% drug release in 15 min in direct compression method and 99.9% drug release in 20 min in wet granulation method). Overall, the dissolution properties of tablet formulations prepared by the direct compression method were superior to those of tablets prepared by the wet granulation method. Accelerated stability studies on some selected tablet formulations were also conducted by keeping the samples at 40 +/- 2 degrees C and 75% relative humidity. There were no statistical differences in the percentage of drug dissolved at 15 and 20 min between fresh and stored samples at the different time points (P < 0.05). Drug content also remained within acceptable limits. Thus, drug-beta-CD binary systems are useful in developing tablet formulations of oxcarbazepine with improved dissolution properties.

Controlled Release of Chlorhexidine Diacetate from a Porous Methacrylate System: Supercritical Fluid Assisted Foaming and Impregnation

The release of chlorhexidine diacetate (CX) from a self-curing polymeric system based on poly(ethylmethacrylate) and tetrahydrofurfurylmethacrylate (PEM/THFM) was developed in this study. Supercritical fluid assisted impregnation and foaming was employed for preparing porous CX-PEM/THFM drug release system. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) show that the crystallinity of CX significantly decreased after supercritical processing, whilst Raman spectroscopy suggested a hydrogen bonding interaction between the CX and PEM in the product. A UV-Vis dissolution study revealed that the drug release rate is almost as seven times faster in the SCF processed drug delivery system than conventional cured samples.

Dimensional changes of alginate dental impression materials

The weight loss and corresponding dimensional changes of two dental alginate impression materials have been studied. The weight loss kinetics indicate this to be a diffusion controlled process, but with a boundary condition at the surface of the concentration decreasing exponentially with time. This is in marked contrast to most desorption processes, where the surface concentration becomes instantaneously zero. The appropriate theory has been developed for an exponential boundary condition, and its predictions compared with experimental data; the agreement was satisfactory. The diffusion coefficients for two thicknesses of the same material were not identical as predicted by theory; the possible reasons for this are discussed.

NMR Imaging of the Diffusion of Water at 310 K into Semi-IPNs of PEM and Poly(HEMA-co-THFMA) with and without Chlorhexidine Diacetate

Magnetic resonance imaging has been used to monitor the diffusion of water at 310 K into a series of semi-IPNs of poly(ethyl methacrylate), PEM, and copolymers of 2-hydroxyethyl methacrylate, HEMA, and tetrahydrofurfuryl methacrylate, THFMA. The diffusion was found to be well described by a Fickian kinetic model in the early stages of the water sorption process, and the diffusion coefficients were found to be slightly smaller than those for the copolymers of HEMA and THFMA, P(HEMA-co-THFMA), containing the same mole fraction of HEMA in the matrix. A second stage sorption process was identified in the later stage of water sorption by the PEM/PTHFMA semi-IPN and for the systems containing a P(HEMA-co-THFMA) component with a mole fraction HEMA of 0.6 or less. This was characterized by the presence of water near the surface of the cylinders with a longer NMR T(2) relaxation time, which would be characteristic of mobile water, such as water present in large pores or surface fissures. The presence of the drug chlorhexidine in the polymer matrixes at a concentration of 5.625 wt % was found not to modify the properties significantly, but the diffusion coefficients for the water sorption were systematically smaller when the drug was present.

A polymeric system for the intra-oral delivery of an anti-fungal agent

Oral candidal infections are often persistent and intractable and thus the aim of this study was to develop a polymeric sustained release device to improve the topical treatment of these infections. A self curing system based on poly(ethyl methacrylate) and tetrahydrofurfuryl methacrylate (PEM/THFM) was used with chlorhexidine diacetate (CX) added at levels between 0 and 12% w/w. Water uptake by the device was assessed gravimetrically and CX release measured by UV spectrometry. Anti candidal activity was established by culturing azole sensitive and resistant strains of Candida albicans in the presence of the polymeric delivery device with and without CX. Candidal growth was measured by turbidimetry or surviving colony-forming unit (CFU) formation. There was an initial high release of CX over 24 h followed by a slow diffusion up to 7 days. CX inhibited candidal growth and survival markedly in vitro, with the test samples showing less than 0.5 x 10(-7) CFU/ml compared to controls (3-4 x 10(-7) CFU/ml). These results indicate the potential of a chlorhexidine containing PEM/THFM polymeric system in the treatment of persistent candidal infections.

Isoprene-styrene copolymer elastomer and tetrahydrofurfuryl methacrylate mixtures for soft prosthetic applications

Novel elastomer/methacrylate systems have been developed for potential soft prosthetic applications. Mixtures of varying compositions of an isoprene-styrene copolymer elastomer and tetrahydrofurfuryl methacrylate (SIS/THFMA) formed one-gel systems and were heat cured with a peroxide initiator. The blends were characterised in terms of sorption in deionised water and simulated body fluids (SBF), tensile properties and viscoelastic parameters of storage modulus and tan delta, as well as glass transition temperatures using dynamic mechanical analysis (DMA). DMA data gave two distinct peaks in tan delta, a lower temperature transition due to the isoprene phase in SIS and one at high temperature thought to be a combination of THFMA and the styrene phase in SIS. The tensile data showed a clear phase inversion within the mid range compositions changing from plastic to elastomeric behaviour. The sorption studies in deionised water showed a two stage uptake with an initial Fickian region that was linear to t 1/2 followed by a droplet growth/clustering system. The slope of the linear region was dependent on the composition ratio. The extent of overall uptake was osmotically dependent as all materials equilibrated at a much lower uptake in SBF. The diffusion coefficients were found to be concentration dependent.

Release of recombinant human bone morphogenetic protein-2 from heterocyclic methacrylate polymer systems

The release of recombinant human bone morphogenetic protein-2 (rhBMP-2) from three room temperature polymerising methacrylate systems has been studied. These all contained poly(ethyl methacrylate) powder, but the monomer liquids comprised, respectively, tetrahydrofurfuryl methacrylate (THFM), 90/10 THFM/hydroxyethyl methacrylate (HEMA), and 70/30 THFM/ HEMA. In all cases, rhBMP-2 was released, but the addition of 10% HEMA accelerated release (a nine-fold increase in diffusion coefficient); a further increase to 30% HEMA had no additional effect. For most of the release process, a diffusion process operated, although the early stages were not well defined. At the end of the 15 day period, the release, respectively, for the PEM/THFM, PEM:90/10 THFM/HEMA and PEM:70/30 THFM/HEMA systems was 596, 878 and 923 ng (i.e. up to 92% of the rhBMP-2 added).

Mycobacterium tuberculosis mycothione reductase: pH dependence of the kinetic parameters and kinetic isotope effects

The recent identification of the enzyme in Mycobacterium tuberculosis that catalyzes the NADPH-dependent reduction of the unique low molecular weight disulfide mycothione, mycothione reductase, has led us to examine the mechanism of catalysis in greater detail. The pH dependence of the kinetic parameters V and V/K for NADPH, NADH, and an active analogue of mycothione disulfide, des-myo-inositol mycothione disulfide, has been determined. An analysis of the pH profiles has allowed the tentative assignment of catalytically significant residues crucial to the mechanism of disulfide reduction, namely, the His444-Glu449 ion pair and Cys39. Solvent kinetic isotope effects were observed on V and V/K(DIMSSM), yielding values of 1.7 +/- 0.2 and 1.4 +/- 0.2, respectively, but not on V/K(NADPH). Proton inventory studies (V versus mole fraction of D(2)O) were linear, indicative of a single proton transfer in a solvent isotopically sensitive step. Steady-state primary deuterium kinetic isotope effects on V have been determined using NADPH and NADH, yielding values of 1.27 +/- 0.03 and 1.66 +/- 0.14, respectively. The pre-steady-state primary deuterium kinetic isotope effect on enzyme reduction has values of 1.82 +/- 0.04 and 1.59 +/- 0.06 for NADPH and NADH, respectively. The steady-state primary deuterium kinetic isotope effect using NADH coincide with that obtained under single turnover conditions, suggesting the complete expression of the intrinsic primary kinetic isotope effect. Rapid reaction studies on the reductive half-reaction using NADPH and NADH yielded maximal rates of 129 +/- 2 and 20 +/- 1 s(-1), respectively, while similar studies of the oxidation of the two-electron reduced enzyme by mycothiol disulfide yielded a maximum rate of 190 +/- 10 s(-1). These data suggest a unique flavoprotein disulfide mechanism in which the rate of the oxidative half-reaction is slightly faster than the rate of the reductive half-reaction.

Mechanisms of unresponsiveness associated with pretransplant blood transfusion-cyclosporine-induced mixed lymphocyte chimerism

Multiple pretransplant blood transfusions while under limited daily cyclosporine cover (PTBT-CsA) induce extensive rat renal allograft survival and antigen-specific non-responsiveness. The underlying mechanisms of this extensive allograft survival are not yet fully understood. We hypothesized that one of the potential contributing mechanisms to tolerance induction in PTBT-CsA-treated kidney recipients is the development of stable mixed chimerism, putatively due to the proliferation of stem cells capable of haematopoiesis in the transfused blood. BN rats served as whole blood and kidney donors. LEW rats served as recipients of the PTBT-CsA protocol and BN kidney transplants. Three weekly transfusions were given under concomitant limited CsA cover. Following these multiple primary sensitizations, antigen-specific splenic cellular responsiveness in vivo was normal in comparison with naive animals. However, these experimental splenocytes were non-specifically suppressed against third-party allodeterminants. At 100 days post-transplantation (T100) following tolerance induction to kidney allografts (secondary challenge), in vivo adoptive transfer experiments demonstrated the existence of potent splenic suppressor cells. In vitro suppressor cell assays confirmed that these cells were non-specific suppressor cells. However, following chimerism stabilization at T130, splenic antigen-specific suppressor cells became exclusively expressed in the tolerant animals, replacing the non-specific suppressor cells. At this time, splenic microchimerism was at peak levels and remained stable from T100 to T130. In conclusion, these findings demonstrate that sequential mechanisms of suppressor cell network expression are induced within a chimeric environment by blood-CsA immune modulation. Stable mixed lymphocyte chimerism and related immunomodulatory mechanisms may, therefore, play an important tolerogenic role in blood-CsA-induced non-responsiveness and in the beneficial effect of blood transfusion.

Nuclear magnetic imaging of an osmotic water uptake and delivery process

The water absorption of NH4F-doped silicone cylinders was studied by spin-echo Fourier nuclear magnetic resonance imaging, in conjunction with gravimetric (mass uptake) and ionic concentration (release of NH4F) measurements. The addition of NH4F greatly increases the water uptake as the inclusions are surrounded by droplets of water when wetted by water diffusing in the polymer. These droplets then expand due to the osmotic pressure difference between the internal droplet and external solution; this expansion is opposed by an elastic restraining force. The rate of ingress into the polymer will depend on the relative chemical potential of water associated with the polymer and the droplet, as well as the diffusion coefficient. Later stages of the absorption process are dominated by the droplets. The dilution of the droplets (from water diffusing into the droplets) slowly reduces the chemical potential driving the process. Hence, the later stages occur without any notable concentration gradient but a slight chemical potential gradient. If the droplet expansion exceeds that which can be restrained by the material, failure around the droplet occurs resulting in the release of the salt and the solution within the droplet.

The effect of two hydrophilic monomers on the water uptake of a heterocyclic methacrylate system

The room temperature polymerising system poly(ethyl methacrylate) (PEM)/tetrahydrofurfuryl methcrylate (THFM) has been modified by replacing some of the THFM by hydroxyethyl methacrylate (HEMA) and hydroxypropyl methacrylate (HPM), respectively. In both cases, the equilibrium uptake of the parent system is reduced substantially, in spite of the hydrophilic nature of these monomers. The effect is less with HPM. Corresponding to these decreases in uptake are substantial increases in the diffusion coefficients. This points to changes from a cluster-dominated process, to a more continuum-based process in the dual monomer systems. Addition of chicken serum albumin to these systems increases water uptake. At higher levels of HEMA addition, there is a substantial increase in polymerisation exotherm.

Replantation of the penis: a patient report

Replantation of the penis is an unusual case in this country and it is unlikely that most plastic and reconstructive surgeons or urologists will see one during their career. A successful repair of a self-inflicted amputation of the penis is presented. The unique anatomy of the penis pertinent to replantation is reviewed, and current concepts and recommendations in performing replantation of the penis are presented.

The epidemiology, anatomy, physiology, and treatment of erectile dysfunction in chronic renal failure patients

Erectile dysfunction (ED) is an associated morbidity for men with chronic renal failure. An understanding of the epidemiology, anatomy, physiology, and treatment options for ED can greatly improve the quality of life for men with chronic renal failure. There are psychological and physiological causes for erectile dysfunction. Once the key features leading to the patient's loss of potency have been identified, appropriate treatment plans can be instituted, often with successful outcomes. The purpose of this article is to assist the nephrology interdisciplinary team in the management of ED by reviewing possible causes, available studies, and treatment options for their patients.

Expression, purification, and characterization of Mycobacterium tuberculosis mycothione reductase

Mycothione reductase from the human pathogen Mycobacterium tuberculosis has been cloned, expressed in Mycobacterium smegmatis, and purified 145-fold to homogeneity in 43% yield. Amino acid sequence alignment of mycothione reductase with the functionally homologous glutathione and trypanothione reductase indicates conservation of the catalytically important redox-active disulfide, histidine-glutamate ion pair, and regions involved in binding both the FAD cofactor and the substrate NADPH. The homogeneous 50 kDa subunit enzyme exists as a homodimer and is NADPH-dependent and highly specific for the structurally unique low-molecular mass disulfide, mycothione, exhibiting Michaelis constants of 8 and 73 microM for NADPH and mycothione, respectively. HPLC analysis indicated the presence of 1 mol of bound FAD per monomer as the cofactor exhibiting an absorption spectrum with a lambda(max) at 462 nm with an extinction coefficient of 11 300 M(-)(1) cm(-)(1). The reductive titration of the enzyme with NADH indicates the presence of a charge-transfer complex of one of the presumptive catalytic thiolates and FAD absorbing at ca. 530 nm. Reaction with serially truncated mycothione and other disulfides and pyridine nucleotide analogues indicates a strict minimal disulfide substrate requirement for the glucosamine moiety of mycothione. The enzyme exhibits bi-bi ping-pong kinetics with both disulfide and quinone substrates. Transhydrogenase activity is observed using NADH and thio-NADP(+), confirming the kinetic mechanism. We suggest mycothione reductase as the newest member of the class I flavoprotein disulfide reductase family of oxidoreductases.

3He ion-beam analysis of water uptake and drug delivery

3He ion-beam analysis utilises a micronuclear reaction analysis (of deuterium and carbon) and microparticle induced X-ray emission (in this case silicon and chlorine), to determine an elemental map of the surface of a sample. This study used D(2)O to model the behaviour of water in poly(tetrahydrofurfuryl methacrylate-polyethyl methacrylate) and chlorhexidine diacetate doped silicone elastomers. The poly(tetrahydrofurfuryl methacrylate-polyethyl methacrylate) systems demonstrated an initial Fickian absorption process (diffusion coefficient 1.1 x 10(-11) m(2)s(-1)) which indicated the 2-stage nature of the polymer's absorption kinetics. The doped silicone samples demonstrated an osmotic mechanism for the controlled release of drugs, with correlation between the D(2)O and the chlorhexidine diacetate inclusions increasing during the experiment. The technique proved valuable in the analysis of delivery polymers and will undoubtedly have further applications in the development of drug delivery systems.

Water sorption behaviour of polymeric systems based on tetrahydrofurfuryl methacrylate

Earlier research has described the water absorption behaviour, drug release and biological properties of a room temperature polymerizing system based on poly(ethyl methacrylate) (PEM) powder and tetrahydrofurfuryl methacrylate (THFM) monomer. This work has been extended, with respect to water sorption behaviour, by replacing the monomer to various extents with hydroxyethyl methacrylate (HEMA), and poly(ethyl methacrylate) by ethyl methacrylate (EM)-THFM copolymers. Replacing the THFM with HEMA, and gelling with PEM, increased the diffusion coefficient progressively. The replacement of PEM by EM-THFM copolymers, when gelled with THFM monomer, substantially reduced equilibrium water uptake, and increased diffusion coefficients. However, with HEMA monomer, equilibrium uptake was unaffected, but the diffusion coefficient decreased with increasing THFM content of the copolymer. This is due to a complex interaction of THFM cross-linking the copolymer, and the effect of EM on the water uptake. Heat polymerizing the PEM-THFM system reduced equilibrium uptake and the diffusion coefficient, compared with the room temperature polymerizing system; this could reflect molecular weight differences.

The water uptake of poly(tetrahydrofurfuryl methacrylate)

Poly(tetrahydrofurfuryl methacrylate) possesses some unique characteristics with respect to its biocompatibility and behaviour in water. The water uptake is high (>70%) and very slow (over 3 yr), but the material remains rigid throughout the process. The mechanism behind the uptake is in two stages; an initial Fickian stage, then as the matrix approaches saturation (about 3 wt%) a second clustering mechanism takes over. The rate of uptake of the second stage of the uptake is controlled by creep (or stress relaxation), and the chemical potential driving the uptake from clustering of the furfuryl rings of the polymer. If clustering or the creep is prevented (by appropriate co-polymerisation) the polymer behaves in an ideal, Fickian manner.

Fluoride ion release from two methacrylate polymer systems

The release of fluoride ions from two room-temperature polymerising systems containing sodium and potassium fluoride, respectively, has been studied. The polymer systems comprised poly(ethyl methacrylate) powder (PEM), with tetrahydrofurfuryl methacrylate (THFM), and n-butyl methacrylate (nBM), respectively. The water uptake of these systems was drastically increased by the presence of fluorides, the increase being much higher with the PEM/THFM system. In both cases, uptake was a monotonic function of the molarity of the fluoride added. The uptake process was in general non-Fickian. However, for all systems, the fluoride release process was Fickian, and diffusion coefficients could be calculated. The amount of fluoride released, and the diffusion coefficients obtained, appeared unrelated to the extent of water uptake of the parent polymers.

Enterococcus faecalis glutathione reductase: purification, characterization and expression under normal and hyperbaric O2 conditions

Glutathione reductase is found ubiquitously in eukaryotes and Gram-negative bacteria, and plays a significant role in bacterial defense against oxidative stress. Glutathione reductase from the Gram-positive bacterium Enterococcus faecalis was purified to homogeneity using anion exchange, hydrophobic interaction, and affinity chromatography. The homogeneous 49-kDa enzyme contained 1 mol bound FAD per subunit. The determined N-terminal amino acid sequence of the E. faecalis enzyme displays significant identity with glutathione reductases from other Gram-negative and Gram-positive bacteria, as well as yeast and human erythrocyte reductases. The kinetic mechanism is ping-pong, and the determined kinetic parameters exhibited by the E. faecalis glutathione reductase are similar to those found for glutathione reductases from yeast, Escherichia coli, and human erythrocyte. A two-fold increased expression of glutathione reductase activity and a three-fold induction of glutathione peroxidase activity were observed under hyperbaric O2 growth conditions without a corresponding change in the total glutathione and soluble thiol content. The difference in the expression of the enzyme, and its cognate substrate's intracellular concentration, under these conditions suggest that the gene encoding glutathione reductase is responsive to oxygen concentration, but that the genes encoding the glutathione synthesizing enzymes are not linked to an oxygen-sensitive promoter.

Heterocyclic methacrylates for clinical applications-further studies of water sorption

The room temperature polymerizing system comprising poly(ethyl methacrylate)-tetra hydrofurfuryl methacrylate (PEM/THFMA) has potential in orthopaedic and dental applications, and earlier work has shown it to have unusual water absorption characteristics. This aspect has been studied in further detail, by studying the water absorption behaviour from some biological solutions, and the effect of the addition of an antibiotic (gentamicin). For comparison purposes, a parallel system whereby tetrahydrofuryl methacrylate was replaced by hydroxyethyl methacrylate (PEM/HEMA), was studied. In the case of PEM/THFMA, water uptake was substantially reduced when absorption was carried out from solutions (from about 30% in water to about 1.5% in solutions of higher concentrations), and the corresponding diffusion coefficient increased (by a factor of several hundred). The addition of gentamicin increased uptake, but the extent of increase also decreased in solutions. It was concluded that uptake was related to the osmolarity of the external solution, and also on the presence of osmotic sites within the polymer; hence the uptake process appears to be governed by chemical potential considerations. At the higher uptakes, there was evidence of water clusters. In marked contrast, the uptake by the PEM/HEMA system was independent of the osmolarity of the external solutions, presumably due to the hydrophilic nature of HEMA.

Duplication cyst of the pylorus--a rare cause of gastric outlet obstruction in the newborn

Duplication cysts of the pylorus are the rarest of alimentary tract duplications with very few reported cases. We present such a cyst in a neonate presenting with gastric outlet obstruction. We have also reviewed the literature and outlined the theories of origin, modes of presentation, diagnosis and the surgical procedures. Even though several modes of surgery have been described, it is best to individualize the surgical option in each case. The results depend on the nature and site of duplication, complications and the associated anomalies.

Use of regression analysis and flow cytometry for determining levels of mixed semiallogeneic immune chimerism

It has been shown that tolerance or specific immunologic nonresponsiveness in various lymphohemopoietic transplant models can be associated with the development of mixed lymphoid chimerism. As a specific example, composite tissue (limb) allografts were studied as a model for vascularized bone marrow transplantation (VBMT) and it was demonstrated that development of stable cellular immune chimerism is associated with long-term allograft survival. Recently, studies were initiated using a new parental to hybrid VBMT model, but the detection of donor cells is complicated, due to the fact that they share one parental allotypic determinant. Therefore, regression analysis with a flow cytometric immunofluorescent staining assay was evaluated for the assessment of cellular lymphoid chimerism in donor parental to hybrid (P-->F1) lymphohemopoietic transplant models. Standard curves consisting of known mixed populations of parental donor (Lewis, LEW) and hybrid host F1 (Lew x BN, LBN) lymphocytes were established. Standard curves were analyzed by linear regression statistics and excellent coefficients of determination (r > .881) were obtained for all standard curves. A highly statistically significant (p < .016) linear relationship between level of donor cell chimerism (independent variable) and percent stained (dependent variable) was determined. The technique was then evaluated using the parental to hybrid VBMT model. Levels of donor LEW lymphoid chimerism in all VBMT LBN recipients were successfully assessed by regression analysis and inverse prediction using distinct recipient allodeterminant markers. In conclusion, this technique was proven to be reliable and accurate for the detection of of chimerism in parental to F1 lymphohemopoietic allograft models.

Evaluation of accuracy and reproducibility of E test for susceptibility testing of Streptococcus pneumoniae to penicillin, cefotaxime, and ceftriaxone

We evaluated the reproducibility with which technologists perform and interpret the E test (AB Biodisk, North America, Inc., Piscataway, N.J.) for determining the susceptibility of Streptococcus pneumoniae to penicillin, cefotaxime, and ceftriaxone. Four technologists prepared E test assays to test 124 isolates of S. pneumoniae. Each technologist then interpreted the results of the E test blinded to the interpretation of the other technologists. In addition, E test results were compared with the reference method of broth microdilution. Intraobserver and interobserver agreement were assessed by use of the kappa statistic. Interpretation of the E test and broth microdilution results showed substantial to excellent agreement, with kappa values ranging from 0.878 to 0.987. Compared with broth microdilution, no very major errors and only four major errors were made with the E test. Most minor errors with penicillin and ceftriaxone occurred for isolates with intermediate or high-level resistance, whereas for cefotaxime the minor errors were more evenly distributed between susceptible and intermediate resistance and between intermediate and high-level resistance. These results indicate that there is good agreement between technologists for the interpretation of the E test when testing the susceptibility of S. pneumoniae to penicillin, cefotaxime, and ceftriaxone and that the results of the E test agree with those of broth microdilution.

Extrarenal Wilms' tumour--a case report and review of literature

Extra renal Wilm's tumour (EWT) is an exceedingly rare entity and needs to fulfill certain criteria. Of the 48 cases reported, only about 36 have been found to be convincingly proved. We present one more well proven case of EWT and have extensively reviewed the literature. The diagnostic, staging and management guidelines are discussed. Amongst the reported cases, the behaviour of the tumour appears to parallel that of similarly staged "intra renal" Wilm's tumour. Hence the staging and the management protocols of "intra renal" Wilm's tumour can well be applied to tumour of extra renal location albeit with some modifications.

Evaluation of three methods for the rapid identification of Staphylococcus aureus in blood cultures

A total of 445 blood cultures containing Gram-positive cocci in clusters were tested for the presence of Staphylococcus aureus with the Accuprobe, heat-stable thermonuclease, and latex agglutination using Staphaurex. The results show that the Accuprobe, thermonuclease, and Staphaurex correctly identified 95, 96, and 62 of the 100 specimens containing S. aureus. The corresponding specificity for the methods was 99.1%, 100%, and 98.5%, respectively.