Cane toad (Rhinella marina) vitamin A, vitamin E, and carotenoid kinetics.

Many amphibian species are threatened with extinction. Understanding their vitamin A (retinol), E (alpha-tocopherol), and carotenoid requirements is vital, as normal levels of these nutrients have a known connection to breeding success with abnormal levels leading to disease. This research examined vitamins A, E, and carotenoids (apocarotenoid, beta-carotene; beta-cryptoxanthin, lutein, zeaxanthin, and esters) concentration kinetics in the liver and plasma of 65 (57.8) cane toads (Rhinella marina) over 4 months supplemented with commercially available invertebrates in human care. Cane toads were opportunistically collected as part of a population control program for use as an amphibian model species. Toads were randomly assigned to one of two diets: treatment 1 was brown house crickets (Acheta domesticus) consuming Mazuri® Hi Calcium Gut Loading Diet without vitamin A or E supplement, plus fresh raw vegetables (carrot/sweet potato); Treatment 2 was the same diet except no vegetables. Ten toads were euthanized on Day 0 to analyze baseline free-ranging liver and plasma metabolites. Six toads consuming each treatment were euthanized on Days 22, 50, and 81, and n = 7 on Day 119 for analysis. Regardless of dietary treatment, most liver and blood metabolites were substantially higher at time 0 than all time points thereafter (p < .05); Ex: liver vitamin A at time 0 was 87.7 ± 16.12 µg/g while Day 119 for treatments 1 and 2 were 11.6 ± 1.19 and 8.2 ± 0.74, respectively. Few statistically significant differences between diets at the same time point were noted (p < .05). The results from this study indicate that additional or alternative diet supplementation may be needed for cane toads (and potentially other amphibians) to mimic their free-ranging diets.

Folate awareness and the prevalence of neural tube defects in South Australia, 1966-2007.

OBJECTIVES: To ascertain changes in: women's knowledge of the role of folic acid in the prevention of neural tube defects (NTDs); intake of folic acid among pregnant women; and prevalence of NTDs in South Australia. DESIGN, SETTING AND PARTICIPANTS: Computer-assisted telephone interviews of South Australian households from 1994 to 2007 over a period encompassing a statewide folate promotion campaign (1994-1995), continuing folate promotion, as well as the introduction of voluntary folate fortification of foods (1996); ascertainment of the total prevalence of NTDs from births and terminations of pregnancy from 1966 to 2007. MAIN OUTCOME MEASURES: Changes in women's knowledge of the role of folic acid in the prevention of NTDs; changes in the prevalence of NTDs. RESULTS: From 1994 to 2006 and 2007, knowledge about the role of folic acid increased from 25% to 77% (P < 0.001) and knowledge that folic acid needs to be taken in the periconceptional period increased from 12% to 39% (P < 0.001). The proportion of pregnant women who increased their periconceptional intake of folate rose from 61% in 1998 to 81% in 2006 and 2007 (P < 0.001), with significant increases in the consumption of fortified cereals (from 15% to 29%) and folic acid tablets (from 37% to 64%). The total prevalence of NTDs fell from 2.06 per 1000 births in 1986-1990 to 1.23 per 1000 births in 2002-2007 (relative risk, 0.60; 95% CI, 0.48-0.74; P < 0.001). CONCLUSIONS: Folate promotion and voluntary fortification of certain foods with folic acid were associated with increased awareness of the role of periconceptional folic acid, increased folate consumption and a reduction in the prevalence of NTDs in South Australia by 40% (95% CI, 26%-52%).

Glutamate-mediated excitotoxicity and neurodegeneration in Alzheimer's disease.

Alzheimer's disease (AD) is the most common form of dementia, accounting for 60-70% of cases in subjects over 65 years of age. Several postulates have been put forward that relate AD neuropathology to intellectual and functional impairment. These range from free-radical-induced damage, through cholinergic dysfunction, to beta-amyloid-induced toxicity. However, therapeutic strategies aimed at improving the cognitive symptoms of patients via choline supplementation, cholinergic stimulation or beta-amyloid vaccination, have largely failed. A growing body of evidence suggests that perturbations in systems using the excitatory amino acid L-glutamate (L-Glu) may underlie the pathogenic mechanisms of (e.g.) hypoxia-ischemia, epilepsy, and chronic neurodegenerative disorders such as Huntington's disease and AD. Almost all neurons in the CNS carry the N-methyl-D-aspartate (NMDA) subtype of ionotropic L-glutamate receptors, which can mediate post-synaptic Ca2+ influx. Excitotoxicity resulting from excessive activation of NMDA receptors may enhance the localized vulnerability of neurons in a manner consistent with AD neuropathology, as a consequence of an altered regional distribution of NMDA receptor subtypes. This review discusses mechanisms for the involvement of the NMDA receptor complex and its interaction with polyamines in the pathogenesis of AD. NMDA receptor antagonists have potential for the therapeutic amelioration of AD.

Quantitation of NMDA receptor NR2 mRNA transcripts in human brain by competitive RT-PCR.

The NMDA-selective ionotropic receptor constitutes one of the three principal classes of L-glutamate receptors within the mammalian brain. It plays key roles in neuronal differentiation and synapse consolidation, activity-dependent forms of synaptic plasticity, and excitatory amino acid-mediated neuronal toxicity [Lab. Invest., 68 (1993) 372-387]. NMDA receptors exist as multimeric complexes comprising proteins from two families, NR1 and NR2(A-D) [J. Biol. Chem., 271 (1996) 15669-15674]. Studies on recombinant receptors have revealed that while homomeric NR2 receptors are non-functional, co-expression of an NR1 with an NR2 subunit modulates the efficacy of the resulting channel [Nature, 357 (1992) 70-74]. The RT-PCR assay we describe here was developed to allow quantitation of all hNR2 transcripts in a single-tube PCR assay. Each hNR2 isoform is quantified on the basis of standard curves in which a known amount of synthetic ribonucleic acid competitor is co-amplified against total RNA. The protocol has been applied to the quantitation of hNR2 mRNA levels in autopsy brain. Used in conjunction with a method for the quantitation of hNR1 transcripts [Brain Res. Protoc., in press], a complete analysis of NMDA receptor mRNA expression can be obtained.