Compartmentation of glutamate metabolism in brain. Evidence for the existence of two different tricarboxylic acid cycles in brain

1. (14)C from [1-(14)C]glucose injected intraperitoneally into mice is incorporated into glutamate, aspartate and glutamine in the brain to a much greater extent than (14)C from [2-(14)C]glucose. This difference for [1-(14)C]glucose and [2-(14)C]glucose increases with time. The amount of (14)C in C-1 of glutamate increases steadily with time with both precursors. It is suggested that a large part of the glutamate and aspartate pools in brain are in close contact with intermediates of a fast-turning tricarboxylic acid cycle. 2. (14)C from [1-(14)C]acetate and [2-(14)C]acetate is incorporated to a much larger extent into glutamine than into glutamate. An examination of the time-course of (14)C incorporated into glutamine and glutamate reveals that glutamine is not formed from the glutamate pool, labelled extensively by glucose, but from a small glutamate pool. This small glutamate pool is not derived from an intermediate of a fast-turning tricarboxylic acid cycle. 3. It is proposed that two different tricarboxylic acid cycles exist in brain.     

Association of 25-Hydroxyvitamin D status and genetic variation in the vitamin D metabolic pathway with FEV1 in the Framingham Heart Study

Background

Vitamin D is associated with lung function in cross-sectional studies, and vitamin D inadequacy is hypothesized to play a role in the pathogenesis of chronic obstructive pulmonary disease. Further data are needed to clarify the relation between vitamin D status, genetic variation in vitamin D metabolic genes, and cross-sectional and longitudinal changes in lung function in healthy adults.

Methods

We estimated the association between serum 25-hydroxyvitamin D [25(OH)D] and cross-sectional forced expiratory volume in the first second (FEV₁) in Framingham Heart Study (FHS) Offspring and Third Generation participants and the association between serum 25(OH)D and longitudinal change in FEV₁ in Third Generation participants using linear mixed-effects models. Using a gene-based approach, we investigated the association between 241 SNPs in 6 select vitamin D metabolic genes in relation to longitudinal change in FEV₁ in Offspring participants and pursued replication of these findings in a meta-analyzed set of 4 independent cohorts.

Results

We found a positive cross-sectional association between 25(OH)D and FEV₁ in FHS Offspring and Third Generation participants (P = 0.004). There was little or no association between 25(OH)D and longitudinal change in FEV₁ in Third Generation participants (P = 0.97). In Offspring participants, the CYP2R1 gene, hypothesized to influence usual serum 25(OH)D status, was associated with longitudinal change in FEV₁ (gene-based P < 0.05). The most significantly associated SNP from CYP2R1 had a consistent direction of association with FEV₁ in the meta-analyzed set of replication cohorts, but the association did not reach statistical significance thresholds (P = 0.09).

Conclusions

Serum 25(OH)D status was associated with cross-sectional FEV₁, but not longitudinal change in FEV₁. The inconsistent associations may be driven by differences in the groups studied. CYP2R1 demonstrated a gene-based association with longitudinal change in FEV₁ and is a promising candidate gene for further studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-015-0238-y) contains supplementary material, which is available to authorized users.     

The electrophysiologic features of sudden death.

Sudden or instantaneous death is nearly always of cardiac origin. The most common mechanism is a severe electrical dysfunction, which is apparent on Holter monitoring tapes. Identifying patients at risk of sudden cardiac death is difficult, and Holter monitoring has proved to be limited in its diagnostic usefulness. However, in patients who have experienced cardiac arrest Holter monitoring has shown that the electrical abnormalities leading to death vary. These abnormalities usually take time to develop, and during this time the cerebral circulation is partially maintained. In this brief period, lasting less than 2 minutes, the individual may become aware that something is wrong and have time to react.     

Floral sex ratios and gynomonoecy in Aster (Asteraceae)

Gynomonoecy is the sexual system in which female and bisexual flowers occur on the same plant. This system has received little attention despite the considerable work on other plant sexual systems in the past few decades. Our study examines one hypothesized advantage of having two flower types on a plant, namely that this arrangement permits flexibility in allocation of resources to male and female reproductive functions. We examined 16 species of Aster (Asteraceae), a genus of gynomonoecious, perennial herbs. Plants in this genus produce heads consisting of a whorl of female flowers around a cluster of bisexual flowers. Among field-grown plants we found no evidence that plant size, date, position of heads, rainfall, or shade influenced the proportion of female flowers. A series of greenhouse experiments likewise revealed no large or consistent effects of light, nutrients, or position of heads on the proportion of ray flowers. While floral ratios proved very stable in the face of environmental and physiological variables, they exhibited significant variation among plants and among sibships in most species. We conclude that the presence of two flower types in gynomonoecious asters is not advantageous in permitting flexibility in allocation of resources to male and female functions. We believe that the advantage of the female flowers in aster heads lies either in reducing pollen-pistil interference or in attracting pollinators.     

Long-term estrogen therapy and 5-HT(2A) receptor binding in postmenopausal women; a single photon emission tomography (SPET) study

Variation in estrogen level is reported by some to affect brain maturation and memory. The neurobiological basis for this may include modulation of the serotonergic system. No neuroimaging studies have directly examined the effect of extended estrogen therapy (ET), on the 5-HT(2A) receptor in human brain. We investigated the effect of long-term ET on cortical 5-HT(2A) receptor availability in postmenopausal women. In a cross-sectional study, we compared cortical 5-HT(2A) receptor availability in 17 postmenopausal ERT-naive women and 17 long-term oophorectomised estrogen-users, age- and IQ-matched using single photon emission tomography and the selective 5-HT(2A) receptor ligand (123)I-5-I-R91150. Also, we used the Revised Wechsler Memory Scale to relate memory function to 5-HT(2A) receptor availability. Never-users had significantly higher 5-HT(2A) receptor availability than estrogen-users in hippocampus (1.17 vs. 1.11, respectively, p=0.02), although this did not remain significant after correction for multiple comparisons. Hippocampal 5-HT(2A) receptor availability correlated negatively with verbal and general memory and delayed recall (r=-0.45, p=0.01; r=-0.40, p=0.02; r=-0.36, p=0.04). Right superior temporal 5-HT(2A) receptor availability correlated negatively with verbal memory (r=-0.36, p=0.04). In estrogen-users, receptor availability correlated negatively with verbal and general memory (r=-0.70, p=0.002; r=-0.69, p=0.002); and in never-users, receptor availability negatively correlated with attention and concentration (r=-0.54, p=0.02). Long-term ET may be associated with lower 5-HT(2A) receptor availability in hippocampus. This may reflect increased activity within the serotonergic pathway leading to down-regulation of post-synaptic receptor. Also, increased availability of the 5-HT(2A) receptor in hippocampus is associated with poorer memory function.     

Efficacy and safety of fixed-dose combinations of aclidinium bromide/formoterol fumarate: the 24-week,randomized, placebo-controlled AUGMENT COPD study

Background

Combining two long-acting bronchodilators with complementary mechanisms of action may provide treatment benefits to patients with chronic obstructive pulmonary disease (COPD) that are greater than those derived from either treatment alone. The efficacy and safety of a fixed-dose combination (FDC) of aclidinium bromide, a long-acting muscarinic antagonist, and formoterol fumarate, a long-acting β₂-agonist, in patients with moderate to severe COPD are presented.

Methods

In this 24-week double-blind study, 1692 patients with stable COPD were equally randomized to twice-daily treatment with FDC aclidinium 400 μg/formoterol 12 μg (ACL400/FOR12 FDC), FDC aclidinium 400 μg/formoterol 6 μg (ACL400/FOR6 FDC), aclidinium 400 μg, formoterol 12 μg, or placebo administered by a multidose dry powder inhaler (Genuair^®/Pressair^®)*. Coprimary endpoints were change from baseline to week 24 in 1-hour morning postdose FEV₁ (FDCs versus aclidinium) and change from baseline to week 24 in morning predose (trough) FEV₁ (FDCs versus formoterol). Secondary endpoints were change from baseline in St. George’s Respiratory Questionnaire (SGRQ) total score and improvement in Transition Dyspnea Index (TDI) focal score at week 24. Safety and tolerability were also assessed.

Results

At study end, improvements from baseline in 1-hour postdose FEV₁ were significantly greater in patients treated with ACL400/FOR12 FDC or ACL400/FOR6 FDC compared with aclidinium (108 mL and 87 mL, respectively; p < 0.0001). Improvements in trough FEV₁ were significantly greater in patients treated with ACL400/FOR12 FDC versus formoterol (45 mL; p = 0.0102), a numerical improvement of 26 mL in trough FEV₁ over formoterol was observed with ACL400/FOR6 FDC. Significant improvements in both SGRQ total and TDI focal scores were observed in the ACL400/FOR12 FDC group at study end (p < 0.0001), with differences over placebo exceeding the minimal clinically important difference of ≥4 points and ≥1 unit, respectively. All treatments were well tolerated, with safety profiles of the FDCs similar to those of the monotherapies.

Conclusions

Treatment with twice-daily aclidinium 400 μg/formoterol 12 μg FDC provided rapid and sustained bronchodilation that was greater than either monotherapy; clinically significant improvements in dyspnea and health status were evident compared with placebo. Aclidinium/formoterol FDC may be an effective and well tolerated new treatment option for patients with COPD.

Trial registration

Clinicaltrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01437397","term_id":"NCT01437397"}}NCT01437397.*Registered trademarks of Almirall S.A., Barcelona, Spain; for use within the US as Pressair^® and Genuair^® within all other licensed territories.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-014-0123-0) contains supplementary material, which is available to authorized users.     

Functional knock down of VCAM1 in mice mediated by endoplasmatic reticulum retained intrabodies

Functional knockdowns mediated by endoplasmatic reticulum-retained antibodies (ER intrabodies) are a promising tool for research because they allow functional interference on the protein level. We demonstrate for the first time that ER intrabodies can induce a knock-down phenotype in mice. Surface VCAM1 was suppressed in bone marrow of heterozygous and homozygous ER intrabody mice (iER-VCAM1 mice). iER-VCAM1 mice did not have a lethal phenotype, in contrast to the constitutive knockout of VCAM1, but adult mice exhibited physiological effects in the form of aberrant distribution of immature B-cells in blood and bone marrow. The capability to regulate knock-down strength may spark a new approach for the functional study of membrane and plasma proteins, which may especially be valuable for generating mouse models that more closely resemble disease states than classic knockouts do.     

Factors affecting the termination of cardiovascular actions of 10, 10-difluoro, 13-dehydroprostacyclin

Experiments were conducted to determine why 10,10-difluoro, 13-dehydroprostacyclin (DF₂-PGI₂) has a long vascular relexant activity but like PGI₂ hads a short duration of effect . DF₂-PGI₂ produced depressor responses in anesthetized dogs which were not affected by nephrectomy suggesting that the kidney was not responsible for the termination of action. DF₂-PGI₂ given intravenously or into the ascending oarta produced depressor responses of a similar magnitude but injection of the same doses into the hepatic portal circulation resulted in a large attenuation of responses. The data suggest hepatitic, but not pulmonary, metabolism of DF₂-PGI₂. Injection or infusion of PGI₂ and DF₂-PGI₂ into the hindlimb circulation caused vasodilation of a similar duration suggesting diffusion from tissue sites as another mechanims of termination of action.