A Reversible Hydrogen-Bond Isomerization Triggered by an Abrupt Spin Crossover near Room Temperature.

The spin crossover salt [Fe(bpp)2 ](isonicNO)2 ⋅ 2.4 H2 O (1⋅2.4 H2 O) (bpp=2,6-bis(pyrazol-3-yl)pyridine; isonicNO=isonicotinate N-oxide anion) exhibits a very abrupt spin crossover at T1/2 =274.4 K. This triggers a supramolecular linkage (H-bond) isomerization that responds reversibly towards light irradiation or temperature change. Isotopic effects in the thermomagnetic behavior reveal the importance of hydrogen bonds in defining the magnetic state. Further, the title compound can be reversibly dehydrated to afford 1, a material that also exhibits spin crossover coupled to H-bond isomerization, leading to strong kinetic effects in the thermomagnetic properties.

Comparison of acid-base and electrolyte changes following administration of 6% hydroxyethyl starch 130/0.42 in a saline and a polyionic solution in anaesthetized dogs.

OBJECTIVE: To evaluate the effects of a 6% hydroxyethyl starch (130/0.42) in either a buffered, electrolyte-balanced (HES-BAL) or saline (HES-SAL) carrier solution on electrolyte concentrations and acid-base parameters in healthy anaesthetized dogs. STUDY DESIGN: Prospective randomised clinical study. ANIMALS: A group of 40 client-owned dogs undergoing general anaesthesia for elective surgical procedures or diagnostic imaging. METHODS: During anaesthesia, dogs were intravenously administered 15 mL kg-1 of either HES-SAL (n = 20) or HES-BAL (n = 20) over 30-40 minutes. Jugular blood samples were analysed before (T0) and 5 minutes (T5), 1 hour (T60) and 3 hours (T180) after fluid administration. Sodium, potassium, chloride, ionised calcium, phosphate, albumin, pH, venous pCO2, base excess (BE), bicarbonate and anion gap were determined and strong ion difference (SID) and total quantity of weak nonvolatile acids were calculated for each time point. RESULTS: Chloride was significantly increased at T5, T60 and T180 compared with T0 after HES-SAL, and was significantly greater after HES-SAL than after HES-BAL at T5 (p = 0.042). Ionised calcium was significantly decreased at T5 compared with T0 after HES-SAL, and was significantly lower after HES-SAL than after HES-BAL at T5 (p < 0.001). Bicarbonate was significantly lower after HES-SAL than after HES-BAL at T5 (p = 0.004) and T60 (p = 0.032). BE was significantly lower after HES-SAL than after HES-BAL at T5 (p < 0.001) and T60 (p = 0.007). SID was significantly decreased after HES-SAL at T5 and T60 compared with T0, and was significantly lower after HES-SAL than after HES-BAL at T5 (p = 0.027). Mean electrolyte and acid-base parameters remained within or marginally outside of reference intervals. CONCLUSIONS AND CLINICAL RELEVANCE: Changes in both groups were minor and short-lived with either fluid in healthy individuals, but might become clinically relevant with higher fluid doses or in critically ill dogs.

Comparison of the effects of 7.2% hypertonic saline and 20% mannitol on whole blood coagulation and platelet function in dogs with suspected intracranial hypertension - a pilot study.

BACKGROUND: Hyperosmolar therapy with either mannitol or hypertonic saline (HTS) is commonly used in the treatment of intracranial hypertension (ICH). In vitro data indicate that both mannitol and HTS affect coagulation and platelet function in dogs. The aim of this study was to compare the effects of 20% mannitol and 7.2% HTS on whole blood coagulation using rotational thromboelastometry (ROTEM®) and platelet function using a platelet function analyzer (PFA®) in dogs with suspected ICH. Thirty client-owned dogs with suspected ICH needing osmotherapy were randomized to receive either 20% mannitol (5 ml/kg IV over 15 min) or 7.2% HTS (4 ml/kg IV over 5 min). ROTEM® (EXTEM® and FIBTEM® assays) and PFA® analyses (collagen/ADP cartridges) were performed before (T0), as well as 5 (T5), 60 (T60) and 120 (T120) minutes after administration of HTS or mannitol. Data at T5, T60 and T120 were analyzed as a percentage of values at T0 for comparison between groups, and as absolute values for comparison between time points, respectively. RESULTS: No significant difference was found between the groups for the percentage change of any parameter at any time point except for FIBTEM® clotting time. Within each group, no significant difference was found between time points for any parameter except for FIBTEM® clotting time in the HTS group, and EXTEM® and FIBTEM® maximum clot firmness in the mannitol group. Median ROTEM® values lay within institutional reference intervals in both groups at all time points, whereas median PFA® values were above the reference intervals at T5 (both groups) and T60 (HTS group). CONCLUSIONS: Using currently recommended doses, mannitol and HTS do not differ in their effects on whole blood coagulation and platelet function in dogs with suspected ICH. Moreover, no relevant impairment of whole blood coagulation was found following treatment with either solution, whereas a short-lived impairment of platelet function was found after both solutions.

Oxidative Addition of Disulfides, Alkyl Sulfides, and Diphosphides to an Aluminum(I) Center.

The aluminum(I) compound NacNacAl (1) reacts with diphenyl disulfide and diethyl sulfide to form the respective four-coordinate bis(phenyl sulfide) complex NacNacAl(SPh)2 (2) and alkyl thiolate aluminum complex NacNacAlEt(SEt) (3). As well, reaction of 1 with tetraphenyl diphosphine furnishes the bis(diphenyl phosphido) complex NacNacAl(PPh2)2 (4). Production of 3 and 4 are the first examples of C(sp(3))-S and R2P-PR2 activation by a main-group element complex. All three complexes were characterized by multinuclear NMR spectroscopy and X-ray crystal structure analysis. Furthermore, a variable-temperature NMR spectroscopic study was undertaken on 4 to study its dynamic behavior in solution.

Life expectancy and causes of death in Bernese mountain dogs in Switzerland.

BACKGROUND: New regulations by the Swiss Federal Food Safety and Veterinary Office provide for the monitoring of breed health by Swiss breeding clubs. In collaboration with the Swiss Bernese Mountain Dog Club, the purpose of this study was to investigate the causes of death in purebred dogs registered by the club and born in 2001 and 2002. RESULTS: Of a total of 1290 Bernese mountain dogs (BMDs) born in 2001 and 2002 in Switzerland, data was collected from owners and veterinarians using a questionnaire designed for this study from 389 dogs (30.2 %). By the end of the study, 381/389 dogs (97.9 %) had died. The median life expectancy of all dogs was 8.4 years (IQR, 6.9-9.7). Female dogs had a significantly longer median survival (8.8 years; IQR, 7.1-10.3) than male dogs (7.7 years; IQR, 6.6-9.3) (P < 0.00). The cause of death was unknown in 89/381 dogs (23.4 %). For the remaining dogs, the most frequent causes of death were neoplasia (222/381, 58.3 %), degenerative joint disease (16/381, 4.2 %), spinal disorders (13/381, 3.4 %), renal injury (12/381, 3.1 %), and gastric or mesenteric volvulus (7/381, 1.8 %). However, large numbers of dogs were diagnosed with neoplasia without histopathologic or cytologic confirmation. Dogs with neoplasms had a shorter median survival than dogs with other disorders. The shortest median survival (6.8 years) was found for dogs with renal injury. CONCLUSIONS: Findings of this study confirm a high prevalence of neoplasia and associated low life expectancy in BMDs. The results underline a need for more widespread precise diagnostics and further research on malignant tumours in this breed to improve overall breed health.

In vitro effects of 6 % hydroxyethyl starch 130/0.42 solution on feline whole blood coagulation measured by rotational thromboelastometry.

BACKGROUND: The artificial colloid, hydroxyethyl starch (HES), is recommended for intravascular volume expansion and colloid-osmotic pressure enhancement in dogs and cats. A well-known side effect of HES solutions in humans and dogs is coagulopathy. However, HES-associated coagulopathy has thus far not been investigated in cats. The goal of this study was to assess the in vitro effects of 6 % HES 130/0.42 on feline whole blood samples using rotational thromboelastometry (ROTEM). A further goal was to develop feline reference intervals for ROTEM at our institution. In this in vitro experimental study, blood samples of 24 adult healthy cats were collected by atraumatic jugular phlebotomy following intramuscular sedation. Baseline ROTEM analyses (using ex-tem, in-tem and fib-tem assays) were performed in duplicate. Additionally, ROTEM analyses were performed on blood samples after dilution with either Ringer's acetate (RA) or 6 % HES 130/0.42 (HES) in a 1:6 dilution (i.e. 1 part solution and 6 parts blood). RESULTS: Coefficients of variation of duplicate measures were below 12 % in all ex-tem assays, 3 of 4 in-tem assays but only 1 of 3 fib-tem assays. Reference intervals were similar albeit somewhat narrower than those previously published. Dilution with both solutions lead to significantly prolonged CT (in-tem), CFT (ex-tem and in-tem), and reduced MCF (ex-tem, in-tem, and fib-tem) and alpha (ex-tem and in-tem). Compared to RA, dilution with HES caused a significant prolongation of CT in fib-tem (P = 0.016), CFT in ex-tem (P = 0.017) and in-tem (P = 0.019), as well as a reduction in MCF in in-tem (P = 0.032) and fib-tem (P = 0.020), and alpha in ex-tem (P = 0.014). However, only a single parameter (CFT in ex-tem) was outside of the established reference interval after dilution with HES. CONCLUSIONS: In vitro hemodilution of feline blood with RA and HES causes a small but significant impairment of whole blood coagulation, with HES leading to a significantly greater effect on coagulation than RA. Further studies are necessary to evaluate the in vivo effects and the clinical significance of these findings.

Insights into the crystallisation process from anhydrous, hydrated and solvated crystal forms of diatrizoic acid.

Diatrizoic acid (DTA), a clinically used X-ray contrast agent, crystallises in two hydrated, three anhydrous and nine solvated solid forms, all of which have been characterised by X-ray crystallography. Single-crystal neutron structures of DTA dihydrate and monosodium DTA tetrahydrate have been determined. All of the solid-state structures have been analysed using partial atomic charges and hardness algorithm (PACHA) calculations. Even though in general all DTA crystal forms reveal similar intermolecular interactions, the overall crystal packing differs considerably from form to form. The water of the dihydrate is encapsulated between a pair of host molecules, which calculations reveal to be an extraordinarily stable motif. DTA presents functionalities that enable hydrogen and halogen bonding, and whilst an extended hydrogen-bonding network is realised in all crystal forms, halogen bonding is not present in the hydrated crystal forms. This is due to the formation of a hydrogen-bonding network based on individual enclosed water squares, which is not amenable to the concomitant formation of halogen bonds. The main interaction in the solvates involves the carboxylic acid, which corroborates the hypothesis that this strong interaction is the last one to be broken during the crystal desolvation and nucleation process.

Cross-Conjugated Systems Based On An (E)-Hexa-3-en-1,5-diyne-3,4-diyl Skeleton: Spectroscopic and Spectroelectrochemical Investigations.

A series of cross-conjugated compounds based on an (E)-4,4'-(hexa-3-en-1,5-diyne-3,4-diyl)bis(N,N-bis(4-methoxyphenyl)aniline) skeleton (1-6) have been synthesized. The linear optical absorption properties can be tuned by modification of the substituents at the 1 and 5 positions of the hexa-3-en-1,5-diynyl backbone (1: Si(CH(CH3)2)3, 2: C6H4C≡CSi(CH3)3, 3: C6H4COOCH3, 4: C6H4CF3, 5: C6H4C≡N, 6: C6H4C≡CC5H4N), although attempts to introduce electron-donating (C6H4CH3, C6H4OCH3, C6H4Si(CH3)3) substituents at these positions were hampered by the ensuing decreased stability of the compounds. Spectroelectrochemical investigations of selected examples, supported by DFT-based computational studies, have shown that one- and two-electron oxidation of the 1,2-bis(triarylamine)ethene fragment also results in electronic changes to the perpendicular π-system in the hexa-3-en-1,5-diynyl branch of the molecule. These properties suggest that (E)-hexa-3-en-1,5-diynyl-based compounds could have applications in molecular sensing and molecular electronics.

Supramolecular Dimerization and [2 + 2] Photocycloaddition Reactions of Crown Ether Styryl Dyes Containing a Tethered Ammonium Group: Structure-Property Relationships.

Molecular self-assembly is an effective strategy for controlling the [2 + 2] photocycloaddition reaction of olefins. The geometrical properties of supramolecular assemblies are proven to have a critical effect on the efficiency and selectivity of this photoreaction both in the solid state and in solution, but the role of other factors remains poorly understood. Convenient supramolecular systems to study the structure-property relationships are pseudocyclic dimers spontaneously formed by styryl dyes containing a crown ether moiety and a remote ammonium group. New dyes of this type were synthesized to investigate the effects of structural and electronic factors on the quantitative characteristics of supramolecular dimerization and [2 + 2] photocycloaddition in solution. Variable structural parameters for the styryl dyes were the size and structure of macrocyclic moiety, the nature of heteroaromatic residue, and the length of the ammonioalkyl group attached to this residue. Quantum chemical calculations of the pseudocyclic dimers were performed in order to interpret the relationships between the structure of the ammonium dyes and the efficiency of the supramolecular photoreaction. One of the dimeric complexes was obtained in the crystalline state and studied by X-ray diffraction. The results obtained demonstrate that the photocycloaddition in the pseudocyclic dimers can be dramatically affected by the electronic structure of the styryl moieties, as dependent on the electron-donating ability of the substituents on the benzene ring, and by the conformational flexibility of the pseudocycle, which determines the mobility of the olefinic bonds. The significance of electronic factors is highlighted by the fact that the photocycloaddition quantum yield in geometrically similar dimeric structures varies from ≤10(-4) to 0.38. The latter value is unusually high for olefins in solution.

In vitro effects of 3% hypertonic saline and 20% mannitol on canine whole blood coagulation and platelet function.

BACKGROUND: Hyperosmolar therapy, using either mannitol or hypertonic saline (HTS), is considered the treatment of choice for intracranial hypertension. However, hyperosmolar agents may impair coagulation and platelet function, limiting their use in patients at risk for hemorrhage. Despite this, studies evaluating the effects of mannitol compared to other hyperosmolar agents in dogs are largely lacking. The aim of this study was to compare the in vitro effects on global hemostasis and platelet function of 20% mannitol and 3% HTS on canine blood. METHODS: Citrated whole blood from 15 healthy dogs was diluted with 0.9% saline, 20% mannitol and 3% HTS in ratios of 1:16 and 1:8. Rotational thromboelastometry (ROTEM) was used to assess clotting time (CT), clot formation time (CFT) and maximal clot firmness (MCF) following extrinsic activation (Ex-tem) and after platelet inhibition (Fib-tem). A platelet function analyzer (PFA-100) was used to assess closure time (Ct(PFA)). RESULTS: No significant differences were observed between untreated whole blood and samples diluted with saline. Samples diluted with both mannitol and HTS were hypocoagulable compared to untreated whole blood samples. At a dilution of 1:16, no significant differences were found between any measured parameter in samples diluted with saline compared to mannitol or HTS. At a 1:8 dilution, Ct(PFA) was prolonged in samples diluted with mannitol and HTS compared to saline, and Ct(PFA) was prolonged more with mannitol than HTS. Ex-tem CT was increased at a 1:8 dilution with mannitol compared to HTS. Ex-tem CFT was prolonged at a 1:8 dilution with both agents compared to saline, and was prolonged more with mannitol than HTS. Ex-tem MCF was reduced at a 1:8 dilution with both agents compared to saline. DISCUSSION AND CONCLUSIONS: Data in this study indicate that both mannitol and HTS affect canine platelet function and whole blood coagulation in vitro in a dose-dependent fashion. The most pronounced effects were observed after high dilutions with mannitol, which impaired platelet aggregation, clot formation time, clot strength, and fibrin formation significantly more than HTS. Further in vivo studies are necessary before recommendations can be made.

Structure of organic solids at low temperature and high pressure.

This tutorial review looks at structural and supramolecular chemistry of molecular solids under extreme conditions, and introduces the instrumentation and facilities that enable single crystal diffraction studies on molecular crystals at both high pressure and low temperature. The equipment used for crystallography under extreme conditions is explored, particularly pressure cells such as the diamond anvil cell, and their mechanism of action, as well as the cryogenic apparatus which allows materials to be cooled to significantly low temperatures. The review also covers recent advances in the structural chemistry of molecular solids under extreme conditions with an emphasis on the use of single crystal crystallography in high pressure and low temperature environments to probe polymorphism and supramolecular interactions.

Biomechanical Evaluation of the Stabilizing Function of Three Atlantoaxial Implants Under Shear Loading: A Canine Cadaveric Study.

OBJECTIVE: To compare the biomechanical properties of a ventral transarticular lag screw fixation technique, a new dorsal atlantoaxial instability (AAI) clamp, and a new ventral AAI hook plate under sagittal shear loading after transection of the ligaments of the atlantoaxial joint. STUDY DESIGN: Cadaveric biomechanical study. ANIMALS: Canine cadavers (n = 10). MATERIALS AND METHODS: The occipitoatlantoaxial region of Beagles euthanatized for reasons unrelated to the study was prepared leaving only ligamentous structures and the joint capsules between the first 2 cervical vertebrae (C1 and C2). The atlanto-occipital joints were stabilized with 2 transarticular diverging positive threaded K-wires. The occipital bone and the caudal end of C2 were embedded in polymethylmethacrylate and loaded in shear to a force of 50 Newtons. The range of motion (ROM) and neutral zone (NZ) of the atlantoaxial joint were determined after 3 loading cycles with atlantoaxial ligaments intact, after ligament transection, and after fixation with each implant. The testing order of implants was randomly assigned. The implants tested last were subjected to failure testing. RESULTS: All stabilization procedures decreased the ROM and NZ of the atlantoaxial joint compared to transected ligament specimens. Only stabilization with transarticular lag screws and ventral plates produced a significant reduction of ROM compare to intact specimens. CONCLUSION: Fixation with transarticular lag screws and a ventral hook plate was biomechanically similar and provided more rigidity compared to dorsal clamp fixation. Further load cycling to failure tests and clinical studies are required before making clinical recommendations.

Assessment of Intramedullary Spinal Pressure in Small Breed Dogs With Thoracolumbar Disk Extrusion Undergoing Hemilaminectomy.

OBJECTIVE: To assess intramedullary spinal pressure (IMP) in small breed dogs with thoracolumbar disk extrusion. STUDY DESIGN: Prospective cohort study. ANIMALS: Small breed dogs (n = 14) with thoracolumbar disk extrusion undergoing hemilaminectomy and healthy chondrodystrophic laboratory dogs (control; n = 3) without spinal disease. METHODS: Diagnosis was based on clinical and neurological examinations and magnetic resonance imaging (MRI) and was confirmed intraoperatively. A standardized anesthesia protocol and surgical procedure were used to minimize factors that could influence IMP. Intramedullary pressure was measured through a minidurotomy at the site of spinal cord compression using a fiber optic catheter inserted perpendicular to the longitudinal axis of the spinal cord. Measurements were taken after hemilaminectomy and again after removal of extruded disk material. RESULTS: Affected dogs had significantly higher IMP compared to control dogs (P = .008) and IMP decreased significantly post-decompression compared with initial values (P < .001). No correlation was found between IMP and neurologic grade, degree of spinal cord compression on MRI, or signal intensity changes on MRI. CONCLUSION: Acute thoracolumbar disk extrusion is associated with increased IMP in small breed dogs and surgical decompression results in an immediate decrease of IMP.

Valvulopathy consistent with endocarditis in an Argentine boa (Boa constrictor occidentalis).

An Argentine boa (Boa constrictor occidentalis) of 5 yr 7 mo of age was presented for respiratory problems and regurgitation. Radiographs revealed evidence of cardiomegaly and pneumonia. Blood smear examination revealed the presence of intracytoplasmic inclusion bodies in peripheral lymphocytes, consistent with inclusion body disease. Cultures of a tracheal wash sample resulted in growth of Ochrobactrum intermedium and Pseudomonas putida. Echocardiographic examination revealed a large vegetative lesion on the right atrioventricular valve with valvular insufficiency, a mildly dilated right atrium, and pulmonary hypertension. Postmortem examination confirmed the presence of pneumonia and bacterial endocarditis with dystrophic mineralization of the right atrioventricular valve, associated with different bacteria than those cultured from the tracheal wash. The present case is the first report of endocarditis in a boa constrictor and contributes to the rare reports of cardiac disease in snakes.

Experimental and theoretical studies of quadrupolar oligothiophene-cored chromophores containing dimesitylboryl moieties as π-accepting end-groups: syntheses, structures, fluorescence, and one- and two-photon absorption.

Quadrupolar oligothiophene chromophores composed of four to five thiophene rings with two terminal (E)-dimesitylborylvinyl groups (4 V-5 V), and five thiophene rings with two terminal aryldimesitylboryl groups (5 B), as well as an analogue of 5 V with a central EDOT ring (5 VE), have been synthesized via Pd-catalyzed cross-coupling reactions in high yields (66-89%). Crystal structures of 4 V, 5 B, bithiophene 2 V, and five thiophene-derived intermediates are reported. Chromophores 4 V, 5 V, 5 B and 5 VE have photoluminescence quantum yields of 0.26-0.29, which are higher than those of the shorter analogues 1 V-3 V (0.01-0.20), and short fluorescence lifetimes (0.50-1.05 ns). Two-photon absorption (TPA) spectra have been measured for 2 V-5 V, 5 B and 5 VE in the range 750-920 nm. The measured TPA cross-sections for the series 2 V-5 V increase steadily with length up to a maximum of 1930 GM. We compare the TPA properties of 2 V-5 V with the related compounds 5 B and 5 VE, giving insight into the structure-property relationship for this class of chromophore. DFT and TD-DFT results, including calculated TPA spectra, complement the experimental findings and contribute to their interpretation. A comparison to other related thiophene and dimesitylboryl compounds indicates that our design strategy is promising for the synthesis of efficient dyes for two-photon-excited fluorescence applications.

Regiospecific formation and unusual optical properties of 2,5-bis(arylethynyl)rhodacyclopentadienes: a new class of luminescent organometallics.

A series of 2,5-bis(arylethynyl)rhodacyclopentadienes has been prepared by a rare example of regiospecific reductive coupling of 1,4-(p-R-phenyl)-1,3-butadiynes (R=H, Me, OMe, SMe, NMe2, CF3, CO2Me, CN, NO2, -C≡C-(p-C6H4-NHex2), -C≡C-(p-C6H4-CO2Oct)) at [RhX(PMe3)4] (1) (X=-C≡C-SiMe3 (a), -C≡C-(p-C6H4-NMe2) (b), -C≡C-C≡C-(p-C6H4-NPh2) (c) or -C≡C-{p-C6H4-C≡C-(p-C6H4 -N(C6H13)2)} (d) or Me (e)), giving the 2,5-bis(arylethynyl) isomer exclusively. The rhodacyclopentadienes bearing a methyl ligand in the equatorial plane (compound 1 e) have been converted into their chloro analogues by reaction with HCl etherate. The rhodacycles thus obtained are stable to air and moisture in the solid state and the acceptor-substituted compounds are even stable to air and moisture in solution. The photophysical properties of the rhodacyclopentadienes are highly unusual in that they exhibit, exclusively, fluorescence between 500-800 nm from the S1 state, with quantum yields of Φ=0.01-0.18 and short lifetimes (τ=0.45-8.20 ns). The triplet state formation (Φ(ISC) =0.57 for 2 a) is exceptionally slow, occurring on the nanosecond timescale. This is unexpected, because the Rh atom should normally facilitate intersystem crossing within femto- to picoseconds, leading to phosphorescence from the T1 state. This work therefore highlights that in some transition-metal complexes, the heavy atom can play a more subtle role in controlling the photophysical behavior than is commonly appreciated.

Synthesis, structure, and properties of supramolecular photoswitches based on ammonioalkyl derivatives of crown ether styryl dyes.

The synthesis of new styryl dyes derived from 4-pyridine and 4-quinoline and having an ammonioalkyl N-substituent and benzocrown ether moieties of different sizes and with different sets of heteroatoms was developed. Spontaneous "head-to-tail" dimerization of these dyes via the formation of numerous hydrogen bonds between the terminal NH3(+) groups and crown ether moieties was detected in MeCN solutions. The stability constants of the dimeric complexes having pseudocyclic structure were studied by (1)H NMR titration. The most stable complexes (log Kd up to 8.2) were found in the case of dyes with the 18-crown-6 ether moiety, which is most complementary for binding a primary ammonium group. Stacking interaction of the conjugated systems in the dimeric complexes contributes to their stability to a much lesser extent. In dimeric complexes, the ethylene bonds of the dyes are preorganized for stereospecific [2 + 2] photocycloaddition (PCA) induced by visible light. PCA yields only rctt isomers of bis-crown-containing cyclobutane derivatives. The dyes were studied by X-ray diffraction; it was found that the dimeric arrangement is also retained in the crystalline state. The possibility of topochemical PCA of the dyes in single crystals without their destruction was demonstrated. The possibility of retro-PCA of the obtained cyclobutane derivatives to give the starting dyes was shown. The elucidated regularities of PCA can be used to fabricate optical data recording systems based on ammonioalkyl derivatives of crown ether styryl dyes.

A combined computational and spectroelectrochemical study of platinum-bridged bis-triarylamine systems.

The character of the electronic transitions in the ultraviolet-visible-near infrared (UV-vis-NIR) spectra of platinum-bis(alkynyl) bridged, bis-triarylamine mixed-valence systems trans-[Pt(C≡CC6H4NAr2)2 (PR3)2](n+) (R = ethyl, Ar = C6H4CH3-4 (1) or C6H4OCH3-4 (2); R = Ph, Ar = C6H4CH3-4 (3) or C6H4OCH3-4 (4), n = 0, 1, 2) has been determined from a combination of spectroscopic measurement and density functional theory calculations. The hybrid functional BLYP35 in combination with a suitable solvent model (i.e., conductor-like screening model (COSMO)) has been used to model the UV-vis-NIR and IR spectroscopic properties of [1-4](+), to confirm the description of [1-4](+) as examples of metal-bridged organic mixed-valence compounds, and to assign the principal features of the electronic spectra, including the triarylamine-based intervalence charge transfer transition located in the NIR region. The successful modeling of the charge distribution within the system demonstrates the utility of the BLYP35-COSMO protocol as a tool for use in the study of intramolecular charge transfer properties in mixed-valence complexes.

A frameshift mutation in the cubilin gene (CUBN) in Beagles with Imerslund-Gräsbeck syndrome (selective cobalamin malabsorption).

Mammals are unable to synthesize cobalamin or vitamin B12 and rely on the uptake of dietary cobalamin. The cubam receptor expressed on the intestinal endothelium is required for the uptake of cobalamin from the gut. Cubam is composed of two protein subunits, amnionless and cubilin, which are encoded by the AMN and CUBN genes respectively. Loss-of-function mutations in either the AMN or the CUBN gene lead to hereditary selective cobalamin malabsorption or Imerslund-Gräsbeck syndrome (IGS). We investigated Beagles with IGS and resequenced the whole genome of one affected Beagle at 15× coverage. The analysis of the AMN and CUBN candidate genes revealed a homozygous deletion of a single cytosine in exon 8 of the CUBN gene (c.786delC). This deletion leads to a frameshift and early premature stop codon (p.Asp262Glufs*47) and is, thus, predicted to represent a complete loss-of-function allele. We tested three IGS-affected and 89 control Beagles and found perfect association between the IGS phenotype and the CUBN:c.786delC variant. Given the known role of cubilin in cobalamin transport, which has been firmly established in humans and dogs, our data strongly suggest that the CUBN:c.786delC variant is causing IGS in the investigated Beagles.

Fluorotetrahydroquinolines from diethyl 2-fluoromalonate ester.

A short series of fluorotetrahydroquinolines was synthesised in two steps from diethyl fluoromalonate and appropriate ortho-nitrobenzyl bromide precursors.