Multiplicity conversion based on intramolecular triplet-to-singlet energy transfer

The ability to convert between molecular spin states is of utmost importance in materials chemistry. Förster-type energy transfer is based on dipole-dipole interactions and can therefore theoretically be used to convert between molecular spin states. Here, a molecular dyad that is capable of transferring energy from an excited triplet state to an excited singlet state is presented. The rate of conversion between these states was shown to be 36 times faster than the rate of emission from the isolated triplet state. This dyad provides the first solid proof that Förster-type triplet-to-singlet energy transfer is possible, revealing a method to increase the rate of light extraction from excited triplet states.

Understanding Optimum Fluoride Intake from Population-Level Evidence

Policy on fluoride intake involves balancing caries against dental fluorosis in populations. The origin of this balance lies with Dean’s research on fluoride concentration in water supplies, caries, and fluorosis. Dean identified cut points in the Index of Dental Fluorosis of 0.4 and 0.6 as critical. These equate to 1.3 and 1.6 mg fluoride (F)/L. However, 1.0 mg F/L, initially called a permissible level, was adopted for fluoridation programs. McClure, in 1943, derived an “optimum” fluoride intake based on this permissible concentration. It was not until 1944 that Dean referred to this concentration as the “optimal” concentration. These were critical steps that have informed health authorities through to today. Several countries have derived toxicological estimates of an adequate and an upper level of intake of fluoride as an important nutrient. The US Institute of Medicine (IOM) in 1997 estimated an Adequate Intake (AI) of 0.05 mg F/kg bodyweight (bw)/d and a Tolerable Upper Intake Level (UL) of 0.10 mg F/kg bw/d. These have been widely promulgated. However, a conundrum has existed with estimates of actual fluoride intake that exceed the UL without the expected adverse fluorosis effects being observed. Both the AI and UL need review. Fluoride intake at an individual level should be interpreted to inform more nuanced guidelines for individual behavior. An “optimum” intake should be based on community perceptions of caries and fluorosis, while the ultimate test for fluoride intake is monitoring caries and fluorosis in populations.

Influence of Mono- and Bivalent Cations in 4A-Zeolites on the Adsorptive Separation of Ethene and Propene from Crack-Gases

Adsorption of ethane/ethene, propane/propene and methane, ethane/ethene, propene mixtures was examined on 4A-zeolites K0·08Na0·92A, Ba0·2Na0·8A, Mg0·2Na0·8A and NaA by measurement of breakthrough curves. Separation of the alkenes and alkanes, especially dynamic capacities, the purity of the desorbates and yields of olefins, confirm the accepted transport mechanism of small alkenes in 4A-zeolites. It is possible to vary the blocking cations and the adsorption centres in the large cavities to obtain favourable conditions for a common separation of ethene and propene from crack-gases.

Expression, purification, crystallization and preliminary X-ray structure analysis of wild-type and L(M196)H-mutant Rhodobacter sphaeroides reaction centres

The electron and proton transport mediated by protein-bound cofactors in photosynthesis have been investigated by various methods in order to determine the energetics, the dynamics and the pathway of this process. In purple bacteria, primary photosynthetic charge separation and the build-up of a proton gradient across the periplasmic membrane are catalyzed by the photosynthetic reaction centre (RC). Here, the purification, crystallization and preliminary X-ray analysis of wild-type and L(M196)H-mutant RCs of Rhodobacter sphaeroides are presented, enabling study of the influence of the protein environment of the primary electron donor on the spectral properties and photochemical activity of the RC.

A functional variant of the serotonin transporter gene (SLC6A4) moderates impulsive choice in attention-deficit/hyperactivity disorder boys and siblings

BACKGROUND

Impulsive drive for immediate reward (IDIR) and delay aversion are dissociable elements of the preference for immediate over delayed rewards seen in attention-deficit/hyperactivity disorder (ADHD). We hypothesized that IDIR would be associated with dopamine regulating genes and delay aversion would be associated with serotonin-regulating genes.

METHODS

Impulsive drive for immediate reward and delay aversion were measured in 459 male children and adolescents (328 ADHD and 131 unaffected siblings) with a laboratory choice task. The sample was genotyped for the 5HTT (SLC6A4) promoter serotonin-transporter-linked polymorphic region polymorphism and a DAT1 (SLC6A3) 40-base pair variable number tandem repeat located in the 3'-untranslated region of the gene.

RESULTS

There was no effect of dopamine transporter (DAT)1 on IDIR. As predicted, serotonin-transporter-linked polymorphic region s-allele carriers were more delay averse. This effect was driven by the s/l genotype in the ADHD group. These results were not altered by taking account of the rs25531 A/G single nucleotide polymorphism and were independent of age, IQ, and oppositional defiant disorder symptoms.

CONCLUSIONS

The results support the genetic distinctiveness of IDIR and delay aversion in ADHD and implicate serotonin function in delay aversion. Possible explanations of the heterosis effect in the ADHD cases are presented.

Unpredicted adverse reaction to omalizumab

Despite promising reports of the use of omalizumab as add-on therapy in patients with systemic mastocytosis and recurrent anaphylaxis during specific venom immunotherapy (VIT), unpredicted adverse effects may lead to therapy failure. We present the case of a patient with systemic mastocytosis and Hymenoptera venom allergy who was administered omalizumab as add-on therapy to improve VIT tolerability after repeated severe adverse reactions despite H1/H2-antihistamine prophylaxis. We describe an unexpected discontinuation of omalizumab following successful initiation of VIT in a patient with systemic mastocytosis, with subsequent lack of tolerability of VIT. An interesting aspect of this case is the correlation of basophil activation test results with both clinical tolerability and VIT intolerance.

Autism symptoms in Attention-Deficit/Hyperactivity Disorder: a familial trait which correlates with conduct, oppositional defiant, language and motor disorders

It is hypothesised that autism symptoms are present in Attention-Deficit/Hyperactivity Disorder (ADHD), are familial and index subtypes of ADHD. Autism symptoms were compared in 821 ADHD probands, 1050 siblings and 149 controls. Shared familiality of autism symptoms and ADHD was calculated using DeFries-Fulker analysis. Autism symptoms were higher in probands than siblings or controls, and higher in male siblings than male controls. Autism symptoms were familial, partly shared with familiality of ADHD in males. Latent class analysis using SCQ-score yielded five classes; Class 1(31%) had few autism symptoms and low comorbidity; Classes 2-4 were intermediate; Class 5(7%) had high autism symptoms and comorbidity. Thus autism symptoms in ADHD represent a familial trait associated with increased neurodevelopmental and oppositional/conduct disorders.

Identification of prognostic factors for chronicity in patients with low back pain: a review of screening instruments

Low back pain (LBP) is currently the most prevalent and costly musculoskeletal problem in modern societies. Screening instruments for the identification of prognostic factors in LBP may help to identify patients with an unfavourable outcome. In this systematic review screening instruments published between 1970 and 2007 were identified by a literature search. Nine different instruments were analysed and their different items grouped into ten structures. Finally, the predictive effectiveness of these structures was examined for the dependent variables including "work status", "functional limitation", and "pain". The strongest predictors for "work status" were psychosocial and occupational structures, whereas for "functional limitation" and "pain" psychological structures were dominating. Psychological and occupational factors show a high reliability for the prognosis of patients with LBP. Screening instruments for the identification of prognostic factors in patients with LBP should include these factors as a minimum core set.

Effect of titanium tetrafluoride and sodium fluoride on erosion progression in enamel and dentine in vitro

Our aim was to investigate the effect of TiF4 solutions on mineral loss on enamel and dentine in vitro. Samples were fluoridated 1 x 5 min per day with 1.64% w/v TiF4 or 2.2% w/v NaF solutions, each with a pH of 1.2, and then subjected to a cyclic de- and remineralization procedure for 5 days. Demineralization was performed for 6 x 10 min per day with citric acid (pH 2.3). In controls no fluoridation was performed. Mineral content was determined by longitudinal microradiography. Enamel mineral loss was markedly reduced by both fluoride solutions, but TiF4 was significantly more effective than NaF: cumulative mineral loss on day 3 was 61.7 +/- 15.0 microm in the NaF and 34.2 +/- 13.1 microm in the TiF4 group (p < or = 0.001) compared with 121.0 +/- 27.0 microm in the control group. Dentine mineral loss ceased after both TiF4 and NaF applications (cumulative mineral loss on day 5 in controls: 61.0 +/- 17.0 microm, in the TiF4 group: 15.4 +/- 13.4 microm and in the NaF group: 21.8 +/- 11.8 microm). Both TiF4 and NaF application reduced mineral loss both on enamel and dentine, which could open new possibilities for a symptomatic therapy of erosions.

Induction of immunity and inflammation by interleukin-12 family members

The interleukin (IL)-12 family is composed of three heterodimeric cytokines, IL-12 (p40p35), IL-23 (p40p19), and IL-27 (EBI3p28), and of monomeric and homodimeric p40. This review focuses on the three heterodimeric members of the IL-12 family. The p40 and p40-like (EBI3) subunits have homology to the IL-6R, the other subunits (p35, p19, and p28) are homologous to each other and to members of the IL-6 superfamily. On the basis of their structural similarity, it was expected that the members of the IL-12 family have overlapping pro-inflammatory and immunoregulatory functions. However, it was surprising that they also show very distinct activities. IL- 12 has a central role as a Th1-inducing and -maintaining cytokine, which is essential in cell-mediated immunity in nonviral infections and in tumor control. IL-23 recently emerged as an end-stage effector cytokine responsible for autoimmune chronic inflammation through induction of IL-17 and direct activation of macrophages. Very recently, IL-27 was found to exert not only a pro-inflammatory Thl-enhancing but also a significant anti-inflammatory function.

Synapses form in skeletal muscles lacking neuregulin receptors

The formation of the neuromuscular junction (NMJ) is directed by reciprocal interactions between motor neurons and muscle fibers. Neuregulin (NRG) and Agrin from motor nerve terminals are both implicated. Here, we demonstrate that NMJs can form in the absence of the NRG receptors ErbB2 and ErbB4 in mouse muscle. Postsynaptic differentiation is, however, induced by Agrin. We therefore conclude that NRG signaling to muscle is not required for NMJ formation. The effects of NRG signaling to muscle may be mediated indirectly through Schwann cells.

Association analysis of genes involved in cholesterol metabolism located within the linkage region on chromosome 10 and Alzheimer's disease

Epidemiological studies identified a higher risk of developing Alzheimer's disease (AD) among subjects with elevated cholesterol levels. This association may be caused by a modulation of the amyloid precursor protein (APP) processing in response to the cellular cholesterol content. High cholesterol levels may favor the amyloidogenic pathway by inhibition of the alpha-secretase probably leading to elevated beta-Amyloid (Abeta) production. The identification of a linkage peak on chromosome 10q using high Abeta as quantitative trait led us to examine polymorphisms of genes located on chromosome 10 involved in cholesterol metabolism, like Lipase A (LIPA), Cholesterol 25 hydroxylase (CH25H), and FLJ22476, a high density lipoprotein binding related protein. Using 286 patients with AD and 162 controls we analyzed several single nucleotide polymorphisms (SNPs) within LIPA, CH25H, and FLJ22476. None of the polymorphisms showed significant association with AD which contradicts recent findings on CH25H. From our results we conclude that the investigated genetic variations do not contribute to the genetic risk of AD.