Direct observation of finite size effects in chains of antiferromagnetically coupled spins.

Finite spin chains made of few magnetic ions are the ultimate-size structures that can be engineered to perform spin manipulations for quantum information devices. Their spin structure is expected to show finite size effects and its knowledge is of great importance both for fundamental physics and applications. Until now a direct and quantitative measurement of the spatial distribution of the magnetization of such small structures has not been achieved even with the most advanced microscopic techniques. Here we present measurements of the spin density distribution of a finite chain of eight spin-3/2 ions using polarized neutron diffraction. The data reveal edge effects that are a consequence of the finite size and of the parity of the chain and indicate a noncollinear spin arrangement. This is in contrast with the uniform spin distribution observed in the parent closed chain and the collinear arrangement in odd-open chains.

Indolyl-3-butyric acid-induced Arabidopsis stomatal opening mediated by 3',5'-cyclic guanosine-monophosphate.

It has been pharmacologically suggested that 3',5'-cyclic guanosine-monophosphate (cGMP) mediates indolyl-3-butyric acid (IBA)-induced stomatal opening. In Arabidopsis thaliana (L.) Heynh., such investigations compared the wild type (Columbia and Ws ecotypes) to mutants knockout for either GTP-binding protein (G protein) α subunit 1 (gpa1-4), putative G protein-coupled receptor 1 (gcr1-5), calcineurin B-like isoform 1 (cbl1) or 9 (cbl9), or the NADPH oxidases AtrbohD and AtrbohF (atrbohD/F). Stomatal opening to IBA or the permeant cGMP analogue, 8-bromo-cGMP (8-Br-cGMP) was abolished in the atrbohD/F mutant. The IBA response was fully or partially suppressed, respectively, in the gcr1-5 mutant, or the gpa1-4 and cbl1 mutants. In the cbl9 mutant, the response to IBA or 8-Br-cGMP, respectively, was partially or fully suppressed. Phenylarsine oxide (PAO) affected the IBA response, which the cbl1 mutant overlapped or the gpa1-4 and cbl9 mutants increased up to 100% inhibition. 6-anilino-5,8-quinolinedione, mas17, the (Rp)-diastereomer of 8-bromo-3',5'-cyclic guanosine monophosphorothioate (Rp-8-Br-cGMPS), nicotinamide, ruthenium red (RRed), 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), cyclosporine A (CsA) and FK506 converged to affect the IBA response, which the gpa1-4 and cbl9 mutants overlapped or the cbl1 mutant and PAO increased up to 100% inhibition. Rp-8-Br-cGMPS, nicotinamide, RRed, BAPTA, CsA or FK506 paralled the cbl9 and atrbohD/F mutants to abolish the 8-Br-cGMP response. Based on so far revealed features of these mutants and pharmacological compounds, these results confirmed cGMP as a Ca(2+)-mobilizing second messenger for apoplastic auxin whose perception and transduction would implicate a seven-transmembrane receptor - G protein - guanylyl cyclase unit at the guard cell plasma membrane.

(E)-5-[hydroxyimino(phenyl)methyl]-1-methyl-3-4-dihydro-2H-pyrrolium trifluoromethanesulfonate.

The cation of the title compound, C12H15N2O+*CF3SO3-, exists as an E-configured hydroxyimino derivative conjugated with a nearly planar iminium system. The twist angle between the phenyl ring and the oxime group is 72.2 (2) degrees. An O--H...O hydrogen bond links the oxime group of the cation to the anion.

Pharmacological evidence for the implication of both cyclic GMP-dependent and -independent transduction pathways within auxin-induced stomatal opening in Commelina communis (L.).

It has been previously suggested that auxin-induced stomatal opening results from at least two transduction pathways, one of which involves cyclic GMP (cGMP) as the mediator within a Ca(2+) signalling cascade. This hypothesis was investigated further in epidermal peels of Commelina communis by comparing the effects of potential inhibitors of plant Ca(2+)-dependent enzymes on the stomatal opening responses to the auxin indolyl-3-butyric acid (IBA) and to the cGMP membrane-permeable derivative 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP). In the 30-50 &mgr;M range, the potential plant calmodulin (CaM) antagonist N-(aminohexyl)-5-chloro-1-naphthalenesulphonamide (W-7) positively interacted with IBA but not with 8-Br-cGMP to open the stomata. The CaM antagonists W-7 (in the 10-20 &mgr;M range) and N-(aminohexyl)-1-naphthalenesulphonamide (40 &mgr;M), the potential inhibitors of plant protein kinases 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (20 and 200 &mgr;M) and K-252a (0.6 &mgr;M), and cyclosporine A and FK506, potential inhibitors of plant homologs of Ca(2+)-CaM complex (Ca(2+)/CaM)-dependent protein phosphatase 2B, prevented the IBA and 8-Br-cGMP responses by about 70% and 100%, respectively. Together, these results provide indirect pharmacological evidence that, in addition to the cGMP-dependent pathway, the auxin signal is transduced through at least one cGMP-independent pathway.

High-resolution neutron structure of nicotinamide adenine dinucleotide.

The structure of the free-acid form of the coenzyme NAD(+) was determined at 100 K from a single-crystal neutron experiment. NAD(+) is the oxidized form of the coenzyme redox pair NAD(+)/NADH and plays an important role in the catalysis of biological processes. The molecule crystallizes in space group P1 with one NAD(+) and four water molecules per unit cell. The structure is compared with the previous X-ray models of NAD(+) [Reddy et al. (1981), J. Am. Chem. Soc. 103, 907-914; Parthasarathy & Fridey (1984b), Science, 226, 969-971; Guillot et al. (2000), Acta Cryst. C56, 726-728]. The crystal packing and the hydrogen-bond pattern are discussed as well as four short C-H.O contacts involving the pyridine and adenine rings. The structure displays stereochemical distortions owing to the hydrogen bonding and crystal-packing constraints, reflecting the adaptability of the NAD(+) molecule in various chemical environments.

Structure of the X-phase of 38% brominated betaine calcium chloride dihydrate.

The structures of the high- and low-temperature phases of 38% brominated BCCD [betaine (trimethylammonioacetate) calcium chloride dihydrate], the latter being known as the X-phase, have been determined by single-crystal neutron diffraction at 295 and 20 K, respectively. The symmetry of the X-phase is described by the P2(1)2(1)2(1) space group. The distortion with respect to the high-temperature Pnma phase is characterized by anti-symmetric displacements of the betaine molecules as well as of the Ca octahedra. On the basis of a symmetry-mode analysis, we propose an interpretation of the direct phase transition that occurs around 80 K between these two phases.

Induction of Stomatal Closure by Vanadate or a Light/Dark Transition Involves Ca2+-Calmodulin-Dependent Protein Phosphorylations.

Previous studies indicate that a continual source of adenosine 5[prime]-triphosphate is required for both opening and closing of stomata. However, vanadate (Na3VO4 at 500 [mu]M) as well as a light/dark transition induced stomatal closing in epidermal peels of Commelina communis L., showing that the stoppage or even the decrease of the activity of the plasma membrane H+-adenosine 5[prime]-triphosphatase is sufficient to induce stomatal closure. Furthermore, stomatal closing in response to Na3VO4 or a light/dark transition was suppressed by inhibitors of metabolism (10 [mu]M carbonyl cyanide m-chlorophenylhydrazone) and of protein kinases (20 [mu]M 1-[5-iodonaphthalene-1-sulfonyl]-1H-hexa-hydro-1,4-diaz-epine), calmodulin antagonists (20 [mu]M N-[6-aminohexyl]-5-chloro-1-naphthalenesulfonamide), and the anion channel blocker 5-nitro-2,3-phenylpropyllamino benzoic acid (50 [mu]M). These data suggest that the slow, outward rectifying anion channel, whose opening would be related to the membrane potential, and at least one step requiring a protein phosphorylation by a Ca2+-calmodulin-dependent protein kinase of the myosin light chain kinase type might be implicated in the induction of stomatal closing by vanadate or a light/dark transition.

Choledochal cyst associated with rare hand malformation.

We report on an 8-year-old boy with choledochal cyst associated with most unusual hand malformation. Review of the literature and possible etiopathogenesis are discussed.

Syndrome of infantile osteopetrosis and Hirschsprung disease in seven children born to four consanguineous unions in two families.

Two cases of Hirschsprung disease associated with infantile osteopetrosis are reported in 2 consanguineous families living in the same area. Both died early.

ABO and Rh(D) blood group distribution and their implication for feto-maternal incompatibility among the Palestinian population.

ABO and Rh(D) blood group distribution was evaluated among Palestinian women in the southern area of the West Bank and east Jerusalem. Eleven per cent of women were Rh(D) negative. The review of the last 12,169 deliveries at Makassed Hospital showed that 4.8% of Rh(D)-negative mothers gave birth to Rh(D)-positive infants with haemolytic disease of the newborn. Thirty per cent of A or B infants born to O Rh(D)-positive mothers had a positive direct antiglobulin test with the presence of allo-immune A or B antibody in infant serum. ABO incompatibility was a major reason for phototherapy during the 1st week of life. Results and possibilities for prevention are discussed.

Syndactyly type IV/hexadactyly of feet associated with unilateral absence of the tibia.

We report on a newborn girl with syndactyly type IV, hexadactyly of feet, and right tibial hemimelia. She has 5 other relatives with identical anomalies of the hands and feet transmitted as an autosomal dominant trait. Syndactyly type IV is rare as is absence of the tibia. We suggest the possibility that syndactyly type IV may be a more complex entity, including lower limb malformations, and transmitted as autosomal dominant with variable expressivity.

Accidental kerosene ingestion: a 3-year prospective study.

Accidental kerosene ingestion continues to cause morbidity and mortality in third world countries, where kerosene is still used for cooking, heating and cleaning. In this prospective study, 78 children aged from 10 months to 5 years were managed at Makassed Hospital in Jerusalem for kerosene ingestion. Respiratory distress developed in 60 (76.90%) children. Two who required mechanical ventilation died. Vomiting, which occurred in 49 cases, did not seem to increase the risk of respiratory complications, suggesting that aspiration occurs with the initial ingestion. Chest X-ray changes were noted in 60% of the children on admission. Pleural effusions occurred in three cases over 24 hours after the incident. CNS manifestations, most likely caused by anoxia, were seen in 27% of the children, but in only two were they severe in the form of convulsions, and both died. Fever occurred in about 50% of the children during their stay in hospital. Severe gastric dilatation developed in the four most severely ill children, two of whom died. The quantity of kerosene ingested by them was estimated to be large.

Scorpion sting in children in the Jerusalem area: a review of 54 cases.

Fifty-four children from the Jerusalem area were studied prospectively following scorpion envenoming. Their ages ranged from 11 months to 10 years. Severe symptoms (convulsions, brain oedema, shock, respiratory distress and myocarditis) were encountered in 19. Respiratory distress was the main feature in 17 of the children, in two cases owing to pulmonary oedema and in a third because of adult respiratory distress syndrome and myocarditis; mechanical ventilation was required in three cases. The severity of the symptoms and signs was not related to sex, age, weight, interval between scorpion sting and admission or to the type of offending scorpion; it was most likely dependent upon the susceptibility of the individual and/or the dose of venom injected by the scorpion. Intravenous antivenom quickly reversed the symptoms, and no side-effects were seen in the patients studied. The two patients who died had not received the antivenom intravenously. We recommend that specific antivenom should be given intravenously in all children who show significant symptoms. Furthermore, a longer period of observation is necessary following scorpion sting in this age group.

Light- and sugar-mediated control of direct de novo flower differentiation from tobacco thin cell layers.

The nature of organs neoformed from tobacco (Nicotiana tabacum cv Samsun) thin cell layers is influenced by the quantity of light supplied and on the sequence of this supply. It is observed that glucose exhibits similar effects. In the presence of glucose at 167 millimolar, continuous light of 50 watts per square meter is required for optimal flower differentiation in vitro. However, 50 watts per square meter irradiance limited to 6 days is sufficient to trigger flower formation in 80% of the explants provided that light is applied from day 6 to day 11 of culture. This critical phase may correspond to the initiation phase during which soluble sugars are mainly needed as carbon energy source rather than as osmoregulators. Under continuous or precise sequential sugar deprivations, either no organogenesis occurs, or abnormal structures or buds are formed. Therefore, light per se is not sufficient to induce flower differentiation. Conversely, a specific quantitative combination of glucose and sucrose almost substitutes for the light requirement for differentiation of anthers and pistils. These observations suggest that, during the sequence of events leading to flower differentiation, light acts on energy-dependent sugar uptake and metabolism and on the increase of reducing potential of chloroplasts.