Search

We investigate the synthesis of coordination polymers (CPs) comprising silver cations, 4,4′-bipyridine and the charge-balancing perhalogenated acetate anions trifluoroacetate (CF3COO–), trichloroacetate (CCl3COO–), tribromoacetate (CBr3COO–) or triiodoacetate (CI3COO–). The syntheses involved anion exchange using the starting CP silver 4,4′-bipyridine acetate. Multianalytical characterization was conducted using powder X-ray diffraction, single crystal X-ray diffraction, optical microscopy and thermogravimetric analysis. Our findings revealed that CPs were formed with CF3COO–or CCl3COO–as the charge-balancing anion and exhibited notable stability. In contrast, reactions with CBr3COO–and CI3COO–showed that the starting anion undergoes decomposition to bromide, iodide or triiodide before being incorporated into the resulting material. This study sheds light on the interactions between perhalogenated anions and CPs and the potential for the use of CPs in the removal of perhalogenated “forever chemicals.”

Pertechnetate, the most stable form of the radionuclide 99Tc in aerobic aqueous systems, is a hazardous anion present in nuclear waste. Its high mobility in water makes the remediation of the anion challenging. In the past decade, significant effort has been placed into finding materials capable of adsorbing this species. Here, we present the synthesis and high-resolution crystal structure of the coordination polymer [Ag(2,4′-bipyridine)]NO3, which is capable of sequestering perrhenate─a pertechnetate surrogate─through anion exchange to form another new coordination polymer, [Ag(2,4′-bipyridine)]ReO4. Both the beginning and end structures were solved by single-crystal X-ray diffraction and the adsorption reaction was monitored through inductively coupled plasma-optical emission spectroscopy and UV–vis spectroscopy. The exchange reaction follows a pseudo-second-order mechanism and the maximum adsorption capacity is 764 mg ReO4/g [Ag(2,4′-bipyridine)]NO3, one of the highest recorded for a coordination polymer or metal–organic framework. A solvent-mediated recrystallization mechanism was determined by monitoring the ion-exchange reaction by scanning electron microscopy–energy-dispersive spectroscopy and powder X-ray diffraction.

Metal halide perovskites, such as methylammonium lead bromide, have recently attracted considerable attention due to their interesting and useful photoelectric properties. Here, two types of methylammonium lead bromide magic-sized clusters (MSCs), passivated with oleylamine and oleic acid, were synthesized using ligand-assisted reprecipitation (LARP) and heated LARP (HLARP) methods. The optical properties of these MSCs were characterized using UV–vis electronic absorption and photoluminescence (PL) spectroscopies. The HLARP synthesis resulted in a two-fold increase in the PL quantum yield of the MSCs to 76%. The stability of the MSCs was tested using time-dependent PL spectroscopy. LARP MSCs in solution degraded completely after 14 days under ambient conditions, while HLARP MSCs lasted for 26 days. To stabilize them, the MSCs were added to a non-coordinating matrix, paraffin. Both MSCs showed significantly improved resistance to water with the addition of paraffin. Solid LARP MSCs lost all luminescence with and without the addition of paraffin by about 3 h. Solid HLARP MSCs without paraffin started to aggregate after 3 h, but paraffin stabilized HLARP MSC films were stable for 8 days. This improved stability in solid state form allowed for accurate, nonaggregated analysis using Raman spectroscopy, X-ray diffraction, and transmission electron microscopy. Raman spectroscopy revealed that the HLARP MSCs show an additional peak at 147 cm–1compared to LARP MSCs, which is attributed to methylammonium. X-ray diffraction and transmission electron microscopy confirm that MSCs have a quasi-crystalline orthorhombic structure.

We report the structures of six anionic, isomorphous metal–organic frameworks [Ln(bpdc)2–][NH2(CH3)2+], where Ln = La, Ce, Nd, Eu, Gd, Er, and bpdc2–= biphenyl-4,4′-dicarboxylate = –O2C(C6H4)2CO2–. The Ln(III) metal centers exhibit eight-coordinate binding to six different bpdc2–ligands (four of which are μ-2 bridging and two are bidentate) and the framework is charge-balanced by a dimethylammonium cation. The materials all possess the same 3D structure and crystallize in the orthorhombic space group Pbcn. All exhibit thermal stability up to ca. 300 °C and decompose to Ln2O3after 800 °C. The Eu-based structure exhibits strong fluorescence in the 612–620 nm range. These materials significantly expand the known chemistry and luminescence of the less studied f-block metal–organic frameworks.

We report the first example of linker modification for an N-donor Ag-based cationic material while maintaining and in some cases increasing the anion exchange capacity. Cationic silver(I) pyrazine nitrate selectively traps harmful oxo-anions from water such as permanganate, perrhenate and a variety of α,ω-alkanedicarboxylates. We chose these anions as initial examples of exchange for potential water purification. The host–guest interaction between the cationic layers of π-stacked silver pyrazine polymers and the incoming/outgoing interlamellar anions allows for the exchange. The exchange capacity over 24 h reached 435 and 818 mg/g for permanganate and perrhenate, respectively, a record for a crystalline metal–organic material and over five times the exchange capacity compared to commercial resin. The material also undergoes organic exchange as an analog for pharmaceutical waste, some of which have a carboxylate functionality at the neutral pH range typical of natural water sources. Both the as-synthesized and exchanged materials are characterized by a variety of analytical techniques.

An in-depth study of the class of cationic materials [Ag(4,4′-bipy)+][X–] (where X–= CH3CO2–, NO3–, BF4–, ClO4–, and MnO4–) has led to key insights on the relationship between anion hydration energy, material structure, solubility, and stability. Since these materials show promise for their potential as water remediation tools, understanding their properties in detail is of significant importance. The structure of the starting and ending materials is the main driving force behind the resultant stability and solubility and can be successfully used to predict the ion exchange capabilities. The solubility trend was determined to be, from most soluble to least soluble, X–= CH3CO2–> NO3–∼ BF4–> ClO4–> MnO4–. Kinetics and thermal stability also follow predictable trends but involve additional factors. For instance, the kinetics of NO3–to MnO4–exchange was much slower than expected based on that seen for NO3–to ClO4–. Powder X-ray diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the materials. Solubility was determined by inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis. Ion exchange was analyzed with ion chromatography (IC) and ultraviolet–visible spectroscopy (UV–vis), and thermal stability was determined with thermogravimetric analysis (TGA).

We present the rapid synthesis of a series of metal–organic framework (MOF) thin films on indium tin oxide (ITO) glass. ITO was first electrodeposited with either copper or zinc microcrystalline films (Cu-ITO and Zn-ITO, respectively) from simple aqueous/ethanol salt solutions. These metallic deposits served as the metal cation source during their partial anodic dissolution and the initial nucleation sites during electrochemical MOF (EMOF) film growth. Four different EMOF films were prepared by this method. HKUST-1 and the two-dimensional (2D) cationic framework [Cu(C10H8N2)2+]Br2(CBBr) were each grown on Cu-ITO. Zn6(OH)3(BTC)3(H20)3·7H2O (Zn-BTC, BTC = benzene tricarboxylate) and the 2D framework [Zn(BPDC)(H2O)]·H2O (Zn-BPDC, BPDC = 2,2′-bipyridine-5,5′-dicarboxylate) were each grown on Zn-ITO. Physical characterization was carried out using grazing incidence X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Our results show these films were well adhered, homogeneous, self-closing, and of relatively low surface roughness in each case. The ability to vary the dimensionality, metal node, linker, and charge of the EMOF on a conductive transparent substrate opens up a wide range of possible compositions, properties, and applications.

Abstract The most striking feature of ataxia telangiectasia (AT) cells is their profound sensitivity to ionising radiation. A deficiency in the rejoining of radiation induced DNA breaks has been suggested [...]

Four new and one previously reported silver 4,4′-vinylenedipyridine (Vpe) coordination polymers were tested as anion exchange materials to assess their potential for pollutant sequestration and compared to analogous silver 4,4′-bipyridine (bipy) coordination polymers. The materials were synthesized using nitrate, tetrafluoroborate, perchlorate, perrhenate, or chromate as the anion to produce cationic coordination polymers with solubilities ranging from 0.0137(7) to 0.21(5) mM. These values are much lower than silver bipy coordination polymers [0.045(3) to 5.5(5) mM] and agree with thermochemical calculations. [Ag(Vpe)+][BF4–], [Ag2(Vpe)2.52+][CrO42–]·5H2O, and [Ag(Vpe)+][ReO4–]·2H2O structures are reported. Perrhenate and chromate ions in an equimolar solution were fully adsorbed by [Ag(Vpe)+][NO3–]·3H2O [620(2) and 137.1(6) mg/g, respectively] as well as by [Ag(Vpe)+][BF4–] [661.8(3) and 190(3) mg/g, respectively] via anion exchange. DFT calculations show that torsional energetics play a significant role in the formation thermodynamics by reducing the energy cost by as much as 4.8 kJ/mol when bipy is replaced with Vpe in silver-based coordination polymers. The results obtained with the flat Vpe ligand highlight the potential role of coordination polymers in practical anion exchange.

The regional distribution of white matter (WM) abnormalities in schizophrenia remains poorly understood, and reported disease effects on the brain vary widely between studies. In an effort to identify commonalities across studies, we perform what we believe is the first ever large-scale coordinated study of WM microstructural differences in schizophrenia. Our analysis consisted of 2359 healthy controls and 1963 schizophrenia patients from 29 independent international studies; we harmonized the processing and statistical analyses of diffusion tensor imaging (DTI) data across sites and meta-analyzed effects across studies. Significant reductions in fractional anisotropy (FA) in schizophrenia patients were widespread, and detected in 20 of 25 regions of interest within a WM skeleton representing all major WM fasciculi. Effect sizes varied by region, peaking at (d=0.42) for the entire WM skeleton, driven more by peripheral areas as opposed to the core WM where regions of interest were defined. The anterior corona radiata (d=0.40) and corpus callosum (d=0.39), specifically its body (d=0.39) and genu (d=0.37), showed greatest effects. Significant decreases, to lesser degrees, were observed in almost all regions analyzed. Larger effect sizes were observed for FA than diffusivity measures; significantly higher mean and radial diffusivity was observed for schizophrenia patients compared with controls. No significant effects of age at onset of schizophrenia or medication dosage were detected. As the largest coordinated analysis of WM differences in a psychiatric disorder to date, the present study provides a robust profile of widespread WM abnormalities in schizophrenia patients worldwide. Interactive three-dimensional visualization of the results is available at www.enigma-viewer.org.

To identify common variants contributing to normal variation in two specific domains of cognitive functioning, we conducted a genome-wide association study (GWAS) of executive functioning and information processing speed in non-demented older adults from the CHARGE (Cohorts for Heart and Aging Research in Genomic Epidemiology) consortium. Neuropsychological testing was available for 5429–32?070 subjects of European ancestry aged 45 years or older, free of dementia and clinical stroke at the time of cognitive testing from 20 cohorts in the discovery phase. We analyzed performance on the Trail Making Test parts A and B, the Letter Digit Substitution Test (LDST), the Digit Symbol Substitution Task (DSST), semantic and phonemic fluency tests, and the Stroop Color and Word Test. Replication was sought in 1311-21860 subjects from 20 independent cohorts. A significant association was observed in the discovery cohorts for the single-nucleotide polymorphism (SNP) rs17518584 (discovery P-value=3.12 × 10-8) and in the joint discovery and replication meta-analysis (P-value=3.28 × 10-9after adjustment for age, gender and education) in an intron of the gene cell adhesion molecule 2 (CADM2) for performance on the LDST/DSST. Rs17518584 is located about 170?kb upstream of the transcription start site of the major transcript for the CADM2gene, but is within an intron of a variant transcript that includes an alternative first exon. The variant is associated with expression of CADM2in the cingulate cortex (P-value=4 × 10-4). The protein encoded by CADM2is involved in glutamate signaling (P-value=7.22 × 10-15), gamma-aminobutyric acid (GABA) transport (P-value=1.36 × 10-11) and neuron cell-cell adhesion (P-value=1.48 × 10-13). Our findings suggest that genetic variation in the CADM2gene is associated with individual differences in information processing speed.

M4Ag44(p-MBA)30molecular nanoparticles, where M is an alkali metal, have recently been shown to have exceptional stability, which confers unique traits to this molecule. In particular, the synthesis is straightforward, produces a truly single-sized molecular product, and has a quantitative yield. Here we describe in detail the results of experimental and theoretical studies on the synthesis, structure, stability, and electronic and optical properties of M4Ag44(p-MBA)30, including ESI-MS, NMR, optical absorption, IR, TGA, and other measurements as well as DFT and TDDFT calculations. This work deepens our understanding of this important Ag molecule, which should facilitate its use in a wide range of fundamental studies and applications.

Cationic layers: Copper hydroxide ethanedisulfonate consists of cationic sheets (see structure of a [Cu4(OH)6]2+layer; Cu green, O red, H white) with ethanedisulfonate as extraframework counteranion. This material shows excellent anion exchange properties for both organics and metal oxo anion pollutants, with over five times higher adsorption capacity for permanganate than hydrotalcite.

We have discovered a facile and inexpensive approach to fabricate “nanospider” TiO2thin films with not only an amazing morphology but highly efficient water splitting to produce hydrogen. Our method employs benzene-swollen poly(ethylene glycol) as a sacrificial organic polymer to template the semiconductor thin film. The synthesized TiO2thin films are highly crystalline with optimized particle and channel size to enhance the liquid-semiconductor junction interaction. This enhanced contact area leads to more than twice the water splitting performance than conventional P25 thin films. In addition, the nanospider thin films also outperform P25 films in the photodegradation of toxic organics.

Effects of genetically modified herbicide–tolerant (GMHT) and conventional crop management on invertebrate trophic groups (herbivores, detritivores, pollinators, predators and parasitoids) were compared in beet, maize and spring oilseed rape sites throughout the UK. These trophic groups were influenced by season, crop species and GMHT management. Many groups increased twofold to fivefold in abundance between early and late summer, and differed up to 10–fold between crop species. GMHT management superimposed relatively small (less than twofold), but consistent, shifts in plant and insect abundance, the extent and direction of these effects being dependent on the relative efficacies of comparable conventional herbicide regimes. In general, the biomass of weeds was reduced under GMHT management in beet and spring oilseed rape and increased in maize compared with conventional treatments. This change in resource availability had knock–on effects on higher trophic levels except in spring oilseed rape where herbivore resource was greatest. Herbivores, pollinators and natural enemies changed in abundance in the same directions as their resources, and detritivores increased in abundance under GMHT management across all crops. The result of the later herbicide application in GMHT treatments was a shift in resource from the herbivore food web to the detritivore food web. The Farm Scale Evaluations have demonstrated over 3 years and throughout the UK that herbivores, detritivores and many of their predators and parasitoids in arable systems are sensitive to the changes in weed communities that result from the introduction of new herbicide regimes.

The effects of management of genetically modified herbicide–tolerant (GMHT) crops on adjacent field margins were assessed for 59 maize, 66 beet and 67 spring oilseed rape sites. Fields were split into halves, one being sown with a GMHT crop and the other with the equivalent conventional non–GMHT crop. Margin vegetation was recorded in three components of the field margins. Most differences were in the tilled area, with fewer smaller effects mirroring them in the verge and boundary. In spring oilseed rape fields, the cover, flowering and seeding of plants were 25, 44 and 39 lower, respectively, in the GMHT uncropped tilled margins. Similarly, for beet, flowering and seeding were 34 and 39 lower, respectively, in the GMHT margins. For maize, the effect was reversed, with plant cover and flowering 28 and 67 greater, respectively, in the GMHT half. Effects on butterflies mirrored these vegetation effects, with 24 fewer butterflies in margins of GMHT spring oilseed rape. The likely cause is the lower nectar supply in GMHT tilled margins and crop edges. Few large treatment differences were found for bees, gastropods or other invertebrates. Scorching of vegetation by herbicide–spray drift was on average 1.6 on verges beside conventional crops and 3.7 beside GMHT crops, the difference being significant for all three crops.

The effects of the management of genetically modified herbicide–tolerant (GMHT) crops on the abundances of aerial and epigeal arthropods were assessed in 66 beet, 68 maize and 67 spring oilseed rape sites as part of the Farm Scale Evaluations of GMHT crops. Most higher taxa were insensitive to differences between GMHT and conventional weed management, but significant effects were found on the abundance of at least one group within each taxon studied. Numbers of butterflies in beet and spring oilseed rape and of Heteroptera and bees in beet were smaller under the relevant GMHT crop management, whereas the abundance of Collembola was consistently greater in all GMHT crops. Generally, these effects were specific to each crop type, reflected the phenology and ecology of the arthropod taxa, were indirect and related to herbicide management. These results apply generally to agriculture across Britain, and could be used in mathematical models to predict the possible long–term effects of the widespread adoption of GMHT technology. The results for bees and butterflies relate to foraging preferences and might or might not translate into effects on population densities, depending on whether adoption leads to forage reductions over large areas. These species, and the detritivore Collembola, may be useful indicator species for future studies of GMHT management.

The effects of herbicide management of genetically modified herbicide–tolerant (GMHT) beet, maize and spring oilseed rape on the abundance and diversity of soil–surface–active invertebrates were assessed. Most effects did not differ between years, environmental zones or initial seedbanks or between sugar and fodder beet. This suggests that the results may be treated as generally applicable to agricultural situations throughout the UK for these crops. The direction of the effects was evenly balanced between increases and decreases in counts in the GMHT compared with the conventional treatment. Most effects involving a greater capture in the GMHT treatments occurred in maize, whereas most effects involving a smaller capture were in beet and spring oilseed rape. Differences between GMHT and conventional crop herbicide management had a significant effect on the capture of most surface–active invertebrate species and higher taxa tested in at least one crop, and these differences reflected the phenology and ecology of the invertebrates. Counts of carabids that feed on weed seeds were smaller in GMHT beet and spring oilseed rape but larger in GMHT maize. In contrast, collembolan detritivore counts were significantly larger under GMHT crop management.

We compared the effects of the management of genetically modified herbicide–tolerant (GMHT) and conventional beet, maize and spring oilseed rape on 12 weed species. We sampled the seedbank before and after cropping. During the season we counted plants and measured seed rain and biomass. Ratios of densities were used to calculate emergence, survival, reproduction and seedbank change. Treatments significantly affected the biomass of six species in beet, eight in maize and five in spring oilseed rape. The effects were generally consistent, with biomass lower in GMHT beet and spring oilseed rape and higher in GMHT maize. With few exceptions, emergence was higher in GMHT crops. Subsequent survival was significantly lowered for eight species in beet and six in spring oilseed rape in the GMHT treatments. It was increased for five species in maize and one in spring oilseed rape. Significant effects on seedbank change were found for four species. However, for many species in beet and spring oilseed rape (19 out of 24 cases), seed densities were lower in the seedbank after GMHT cropping. These differences compounded over time would result in large decreases in population densities of arable weeds. In maize, populations may increase.

We compared the seedbanks, seed rains, plant densities and biomasses of weeds under two contrasting systems of management in beet, maize and spring oilseed rape. Weed seedbank and plant density were measured at the same locations in two subsequent seasons. About 60 fields were sown with each crop. Each field was split, one half being sown with a conventional variety managed according to the farmer's normal practice, the other half being sown with a genetically modified herbicide–tolerant (GMHT) variety, with weeds controlled by a broad–spectrum herbicide. In beet and rape, plant densities shortly after sowing were higher in the GMHT treatment. Following weed control in conventional beet, plant densities were approximately one–fifth of those in GMHT beet. In both beet and rape, this effect was reversed after the first application of broad–spectrum herbicide, so that late–season plant densities were lower in the GMHT treatments. Biomass and seed rain in GMHT crops were between one–third and one–sixth of those in conventional treatments. The effects of differing weed–seed returns in these two crops persisted in the seedbank: densities following the GMHT treatment were about 20 lower than those following the conventional treatment. The effect of growing maize was quite different. Weed density was higher throughout the season in the GMHT treatment. Late–season biomass was 82 higher and seed rain was 87 higher than in the conventional treatment. The difference was not subsequently detectable in the seedbank because the total seed return was low after both treatments. In all three crops, weed diversity was little affected by the treatment, except for transient effects immediately following herbicide application.

The Farm Scale Evaluations of genetically modified herbicide–tolerant crops (GMHT) were conducted in the UK from 2000 to 2002 on beet (sugar and fodder), spring oilseed rape and forage maize. The management of the crops studied is described and compared with current conventional commercial practice. The distribution of field sites adequately represented the areas currently growing these crops, and the sample contained sites operated at a range of management intensities, including low intensity. Herbicide inputs were audited, and the active ingredients used and the rates and the timings of applications compared well with current practice for both GMHT and conventional crops. Inputs on sugar beet were lower than, and inputs on spring oilseed rape and forage maize were consistent with, national averages. Regression analysis of herbicide–application strategies and weed emergence showed that inputs applied by farmers increased with weed densities in beet and forage maize. GMHT crops generally received only one herbicide active ingredient per crop, later and fewer herbicide sprays and less active ingredient (for beet and maize) than the conventional treatments. The audit of inputs found no evidence of bias.

Some genes in mammals and flowering plants are subject to parental imprinting, a process by which differential epigenetic marks are imposed on male and female gametes so that one set of alleles is silenced on chromosomes contributed by the mother while another is silenced on paternal chromosomes. Therefore, each genome contributes a different set of active alleles to the offspring, which develop abnormally if the parental genome balance is disturbed. In Arabidopsis, seeds inheriting extra maternal genomes show distinctive phenotypes such as low weight and inhibition of mitosis in the endosperm, while extra paternal genomes result in reciprocal phenotypes such as high weight and endosperm overproliferation. DNA methylation is known to be an essential component of the parental imprinting mechanism in mammals, but there is less evidence for this in plants. For the present study, seed development was examined in crosses using a transgenic Arabidopsis line with reduced DNA methylation. Crosses between hypomethylated and wild-type diploid plants produced similar seed phenotypes to crosses between plants with normal methylation but different ploidies. This is consistent with a model in which hypomethylation of one parental genome prevents silencing of alleles that would normally be active only when inherited from the other parent - thus phenocopying the effects of extra genomes. These results suggest an important role for methylation in parent-of-origin effects, and by inference parental imprinting, in plants. The phenotype of biparentally hypomethylated seeds is less extreme than the reciprocal phenotypes of uniparentally hypomethylated seeds. The observation that development is less severely affected if gametes of both sexes (rather than just one) are 'neutralized' with respect to parent-of-origin effects supports the hypothesis that parental imprinting is not necessary to regulate development.

Abstract: Blomstrand osteochondrodysplasia (BOCD) is a rare, autosomal recessive, lethal skeletal dysplasia characterized by generalized osteosclerosis and advanced skeletal maturation. The histopathological characteristics of three novel cases (two isolated cases and a sib-pair) of BOCD are presented and correlated with the clinical and radiographical findings, and the relevant literature is reviewed. The results of our study confirm the existence of two separate types of BOCD, which we propose naming type I: the severe, ’classical’ form, and type II: a less severe form.

We report the high-capacity and selective uptake of Cr(VI) from water using the coordination polymer silver bipyridine acetate (SBA, [Ag(4,4′-bipy)][CH3CO2]·3H2O). Cr capture involves the release of acetate, and we have structurally characterized two of the product phases that form: silver bipyridine chromate (SBC, SLUG-56, [Ag(4,4′-bipy)][CrO4]0.5·3.5H2O) and silver bipyridine dichromate (SBDC, SLUG-57, [Ag(4,4′-bipy)][Cr2O7]0.5·H2O). SBA maintains a high Cr uptake capacity over a wide range of pH values (2–10), reaching a maximum of 143 mg Cr/g at pH 4. This Cr uptake capacity is one of the highest among coordination polymers. SBA offers the additional benefits of a one-step, room temperature, aqueous synthesis and its release of a non-toxic anion following Cr(VI) capture, acetate. Furthermore, SBA capture of Cr(VI) remains >97% in the presence of a 50-fold molar excess of sulfate, nitrate, or carbonate. We also investigated the Cr(VI) sequestration abilities of silver 1,2-bis(4-pyridyl)ethane nitrate (SEN, [Ag(4,4′-bpe)][NO3]) and structurally characterized the silver 1,2-bis(4-pyridyl)ethane chromate (SEC, SLUG-58, [Ag(4,4′-bpe)][CrO4]0.5) product. SEN was, however, a less effective Cr(VI) sequestering material than SBA.

The I3 cDNA isolated from a library made from 2–4 mm (immature) anthers of Brassica napus shows microspore-specific expression. Homologous transcripts are detected in buds and anthers of male-fertile plants, but not in green tissues, roots, or in cytoplasmic male-sterile buds. High expression of the transcript is limited to microspores entering and undergoing mitosis. The predicted peptide sequence of the cDNA shows an unusual repeated alanine/proline motif at the C-terminus, which may be of importance in the native protein structure.

Abstract: Recent studies in mice have provided strong evidence for a modifier gene that is capable of effecting the expression of the mouse equivalent of familial adenomatous polyposis (FAP). A candidate gene has been proposed, namely secretory phospholipase A2 (sPLA2). Increased tumor number in mice was correlated with low levels of sPLA2 expression and the presence of truncating mutations within the sPLA2 gene. In an attempt to determine whether any genetic alterations in the sPLA2 gene were associated with the expression of FAP in man, we investigated the genetic structure of sPLA2 in 97 polyposis coli patients presenting with various disease phenotypes, and its expression in 8 FAP patients displaying markedly different disease characteristics. In the current study no inactivating mutations in the sPLA2 gene were identified, suggesting that human sPLA2 is not associated with phenotypic variation in FAP.

1. Thin slices (0.2‐0.3 mm) of rabbit renal cortex have been incubated in isosmotic oxygenated acetate media at 25 degrees C with or without ouabain (10(‐3) M), amiloride (2 x 10(‐3) M) or iodoacetamide (10(‐3) M). 2. Slices in normal isosmotic 146 mM‐sodium‐132 mM‐acetate media swelled as reported previously (Cooke & Macknight, 1984). This swelling was not prevented by amiloride or by metabolic inhibition. 3. Slices in isosmotic 132 mM‐choline‐132 mM‐acetate media gained much less water and were little affected by ouabain, amiloride or metabolic inhibition. Choline was able to substitute neither for sodium nor for potassium in activating preparations of renal cortical Na+‐K+‐ATPase in chloride or in acetate media. 4. Slices in isosmotic 20 mM‐sodium‐132 mM‐acetate medium swelled nearly as much as did slices in normal sodium acetate medium. However, this swelling was impaired markedly by amiloride, by ouabain and by metabolic inhibition. 5. There was a direct correlation between medium sodium concentration and slice water content as sodium was increased from 1.25 to 30 mM in 132 mM‐acetate media. However, up to a sodium concentration of 10 mM, amiloride (2 x 10(‐3) M) completely prevented this increase in water content. 6. Increasing medium amiloride concentration from 10(‐5) to 10(‐3) M progressively inhibited cellular swelling in 10 mM‐sodium‐132 mM‐acetate medium. It is concluded that, under these experimental conditions, the dominant pathway for hydrogen ion extrusion from the cells was via amiloride‐sensitive sodium‐hydrogen exchange. 7. The results are discussed in terms of a model which explains cellular swelling in acetate media in terms of (a) non‐ionic diffusion of acetic acid across plasma membranes impermeable to the acetate anion, (b) removal from the cells of the hydrogen ion gained with the acetate by amiloride‐sensitive sodium‐hydrogen counter‐transport and (c) subsequent extrusion of sodium from the cell accompanied by potassium uptake via the ouabain‐sensitive Na+‐K+‐ATPase. 8. The results provide evidence for ion movements across the luminal plasma membrane of proximal tubular cells in rabbit renal cortical slices.

Failure to achieve local control in the treatment of pelvic and retroperitoneal tumours results in a high rate of recurrences. The objective of intraoperative hyperthermia (IOHT) is to enhance the effect of intraoperative radiation therapy and to increase local tumour control. The tolerance of peripheral nerves to heat may limit the heat dose that can be applied to tumours. Histopathologic and histomorphometric changes of canine sciatic nerve after 60-min IOHT were studied in three groups of five dogs each for temperatures of 43, 44 and 45°C. IOHT was performed using a water-circulating hyperthermia device with a multichannel thermometry system on surgically exposed sciatic nerve. Histopathologic and histomorphometric studies were done immediately, 3 weeks and 12 months after IOHT. Histologic changes observed immediately after treatment were minimal but at 3 weeks following 60-min 45°C IOHT both axon and myelin loss and an increase in endoneurial fibrous tissue were observed. Twelve months after treatment a statistically significant decrease in axon, myelin and small vessel percentages as well as an increase in endoneurial and epineural connective tissue were observed for dog treated to 45°C. Dog treated to 44°C for 60 min had similar statistically significant but less severe changes. Twelve months after 43°C IOHT for 60 min, nerve fibres appeared normal and endoneurial connective tissue was only increased mildly around small and medium-sized vessels. These results suggest that temperatures to the peripheral nerve >44°C for 60 min are likely to cause significant histopathologic changes that can be found 12 months after treatment. A hypothesis of the mechanism of heat injury to peripheral nerves was developed.

The tolerance of peripheral nerves to heat may limit the heat dose which can be applied to tumours. This may be particularly important in intraoperative hyperthermia (IOHT) for pelvic and retroperitoneal tumours. Furthermore the effects of hyperthermia alone must be known before its effects can be assessed in combination with irradiation. In this study injury to sciatic nerves was evaluated in 30 beagle dogs for 1 year following IOHT. IOHT was performed using a water circulating hyperthermia device with multichannel thermometry system. Neurological and electrophysiological examinations were done before, during and after IOHT treatment. Electrophysiological examinations showed a significant decrease in sciatic nerve conduction velocity and potential amplitude immediately after 60 min of heating for all temperatures. The greatest decrease in conduction velocity was observed for a temperature of 45°C. Full recovery of nerve conduction velocity was observed 3 weeks following hyperthermia for all dogs except for those exposed to 45°C. Neurological findings correlated with electrophysiological results. All five dogs which had nerve exposed to 45°C for 60 min had severe neurological changes, with recovery taking place between 3 and 11 months after treatment. Based on these results it appears that temperatures to the peripheral nerve exceeding 44°C for 1 h are likely to cause significant, but not necessarily permanent, nerve injury.

Abstract: Phenotypic variability based on nonallelic heterogeneity is a characteristic feature of the dominantly inherited disease, familial adenomatous polyposis (FAP). A modifying locus, called Mom-1, which strongly influences disease expression has been mapped in the mouse model of FAP to the region of murine chromosome 4, which has synteny to human chromosome 1p35-36. In the present study, this chromosomal region was investigated by using 14 microsatellite markers within a large FAP kindred in which patients harbor the same germ-line mutation but show markedly different disease characteristics. The linkage program MLINK was used to determine whether any correlation exists between these markers and the development of extracolonic symptoms in polyposis coli patients. Depending on the mode of inheritance of the affected locus, a maximum lod score was observed for markers D1S211 and D1S197, reaching 2.08 and 1.77, respectively. The observed values obtained within one large FAP family are supportive of a phenotype-modifying locus within this chromosomal region.

Eternal vigilance and strict attention to detail are the ‘sine qua non’ of safe anaesthesia with the contemporaneous anaesthetic record being the documentation. As an alternative to the manifold and often inadequate forms currently in use, a new rapidly completed anaesthetic record incorporating a comprehensive checklist is presented. Guidelines of the Faculty of Anaesthetists, Royal Australasian College of Surgeons are met.It is argued that the chart improves safety not only by its direction to attention during the preoperative visit and equipment check, but also by its demand for the ongoing attention of the anaesthetist. Reservations are expressed about ‘black box’ recording by trend printout and a perspective for computerised and automated anaesthetic records is also discussed.

Perinatal hypoxic brain injury is a major cause of death and morbidity, in which the onset of injury can be prenatal, and the effects may be delayed. Selective neuronal necrosis, with isolated karyorrhectic nuclei in the pons, is a common pattern of injury in mature perinatal deaths. Other evidence implicates apoptosis in hypoxic brain injury. In this study the mode of cell death in hypoxic injury was investigated in 11 fresh stillbirths and 10 neonatal deaths. Sections of pons were stained using several methods including terminal deoxynucleotidyl transferase (TdT)‐mediated deoxyuridine triphosphate (dUTP) nick end labelling (TUNEL) and immunocytochemistry. Karyorrhectic nuclei were counted on adjacent haematoxylin and eosin sections. A high percentage of apoptotic cells was significantly associated with the presence of karyorrhexis in the pons, but there were five stillbirths in whom apoptosis in the pons was the sole evidence of hypoxic brain injury. PCNA positive neuronal nuclei were seen in 19 out of the 21 cases. The results suggest that both apoptosis and necrosis are occurring following hypoxic injury, so that the pattern of injury in the pons may be better termed ‘selective neuronal death’. Variations in severity and duration of the insult might explain the differences between cases. The presence of PCNA‐positive neurons may suggest DNA repair in these nuclei, which might be activated at an early stage of apoptosis. However the precise mechanism by which apoptosis is induced in hypoxic brain injury remains to be elucidated.

In flowering plants, male meiosis occurs in the microsporocyte to produce four microspores, each of which develops into a pollen grain. Here we describe four mutant alleles of TETRASPORE (TES), a gene essential for microsporocyte cytokinesis in Arabidopsis thaliana. Following failure of male meiotic cytokinesis in tes mutants, all four microspore nuclei remain within the same cytoplasm, with some completing their developmental programmes to form functional pollen nuclei. Both of the mitotic divisions seen in normal pollen development take place in tes mutants, including the asymmetric division required for the differentiation of gametes; some tes grains perform multiple asymmetric divisions in the same cytoplasm. tes pollen shows a variety of abnormalities subsequent to the cytokinetic defect, including fusion of nuclei, formation of ectopic internal walls, and disruptions to external wall patterning. In addition, ovules fertilized by tes pollen often abort, possibly because of excess paternal genomes in the endosperm. Thus tes mutants not only reveal a gene specific to male meiosis, but aid investigation of a wide range of processes in pollen development and function.

Many flowering plants are polyploid, but crosses between individuals of different ploidies produce seeds that develop abnormally and usually abort. Often, seeds from interploidy crosses develop differently depending on whether the mother or father contributes more chromosome sets, suggesting that maternal and paternal genomes are not functionally equivalent. Here we present the first cytological investigation of seed development following interploidy crosses in Arabidopsis thaliana. We find that crosses between diploid and tetraploid plants in either direction, resulting in double the normal dose of maternal or paternal genomes in the seed, produce viable seeds containing triploid embryos. However, development of the seed and in particular the endosperm is abnormal, with maternal and paternal genomic excess producing complementary phenotypes. A double dose of maternal genomes with respect to paternal contribution inhibits endosperm development and ultimately produces a smaller embryo. In contrast, a double dose of paternal genomes promotes growth of the endosperm and embryo. Reciprocal crosses between diploids and hexaploids, resulting in a triple dose of maternal or paternal genomes, produce seeds that begin development with similar but more extreme phenotypes than those with a double dose, but these invariably abort. One explanation of our observations is that seeds with maternal or paternal excess contain different doses of maternally or paternally expressed imprinted loci affecting endosperm development.

Whole-body hyperthermia has potential as an adjuvant treatment with chemotherapy and radiation therapy for diseases such as lung cancer which require both local and systemic control. The acute toxicity of whole-body hyperthermia combined with whole-thorax irradiation was studied in dogs. Twentyeight dogs received three 2-h whole-body hyperthermia (WBH) treatments at 42.0°C deep rectal temperature. Twenty-four of these dogs were also randomized to receive radiation doses of 18, 22 5, 27, 31-5, 40.5 or 45 Gy. Irradiation was given in 1 a5 Gy fractions over 6 weeks. Three WBH treatmens were given to 28 dogs with all dogs surviving treatment. WBH was given on days 1, 22 and 40 of the 6-week interval. Thirty-one dogs received radiation doses of 18-49.5 Gy without WBH. Deep rectal temperature was maintained at 41.9 ±0.3°C over 2 h with an average of 20 min outside the chamber for irradiation. Two dogs required intervention with emergency medications during WBH treatment. One of the two dogs developed permanent neurological injury. Continuous physiological monitoring was necessary for successful WBH. WBH plus thoracic irradiation was well tolerated. All dogs survived all treatments. A significant but transient increase in peripheral blood leucocytes and a decrease in platelet counts occurred after each WBH treatment. The addition of thoracic irradiation up to 45 Gy in 1-5 Gy fractions did not appear to alter the acute toxicity of WBH with the exception of an increase in the protein content of lung lavage fluids. In conclusion, multiple WBH treatments of 2 h at a target temperature of 42°C in addition to thoracic irradiation up to 45 Gy in 1.5 Gy fractions was administered with only mild acute toxicities occurring. Core temperature could be maintained for up to 20 min outside of the WBH chamber which allowed irradiation to be given concurrently with hyperthermia at a core temperature of 42°C ±0.1 °C.

Antibiotic resistance to G418 has been transferred into Chinese hamster cell lines via a plasmid vector. The same plasmid, which also contained the Leu2 gene, has been used to transform Leu2- yeast (strain MCI6) to leucine prototrophy. Subsequent fusion between transformed yeast and untransformed hamster cells demonstrated that plasmid DNA could be transferred and its genes expressed within the mammalian cell genome. The fusion of transformed hamster cells with untransformed MC16 yeast cells demonstrated that DNA integrated within the mammalian cell genome could be transferred to correct the Leu2 deficiency and also confer G418 resistance on some yeast colonies.

Poly­[tin(II)‐μ‐phenyl­phospho­nato], [Sn(C6H5O3P)]n, was synthesized solvothermally at 423 K and crystallized in the monoclinic system, space group Cc. The inorganic layers consist of alternating pyramidal Sn and tetrahedral P centers, joined by doubly bridging O atoms. The corner‐sharing SnO3and PO3C6H5polyhedra define a corrugated layer of six‐membered rings. The layers are connected along the unique baxis by interdigitated phenyl rings of the phenyl­phospho­nate groups.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.