It is generally accepted that gases such as CO2 cross cell membranes by dissolving in the membrane lipid. No role for channels or pores in gas transport has ever been demonstrated. Here we ask whether expression of the water channel aquaporin-1 (AQP1) enhances the CO2 permeability of Xenopus oocytes. We expressed AQP1 in Xenopus oocytes by injecting AQP1 cRNA, and we assessed CO2permeability by using microelectrodes to monitor the changes in intracellular pH (pHi) produced by adding 1.5% CO2/10 mM[Formula: see text] to (or removing it from) the extracellular solution. Oocytes normally have an undetectably low level of carbonic anhydrase (CA), which eliminates the CO2 hydration reaction as a rate-limiting step. We found that expressing AQP1 (vs. injecting water) had no measurable effect on the rate of CO2-induced pHi changes in such low-CA oocytes: adding CO2 caused pHi to fall at a mean initial rate of 11.3 × 10−4 pH units/s in control oocytes and 13.3 × 10−4 pH units/s in oocytes expressing AQP1. When we injected oocytes with water, and a few days later with CA, the CO2-induced pHi changes in these water/CA oocytes were more than fourfold faster than in water-injected oocytes (acidification rate, 53 × 10−4 pH units/s). Ethoxzolamide (ETX; 10 μM), a membrane-permeant CA inhibitor, greatly slowed the pHi changes (16.5 × 10−4 pH units/s). When we injected oocytes with AQP1 cRNA and then CA, the CO2-induced pHi changes in these AQP1/CA oocytes were ∼40% faster than in the water/CA oocytes (75 × 10−4 pH units/s), and ETX reduced the rates substantially (14.7 × 10−4 pH units/s). Thus, in the presence of CA, AQP1 expression significantly increases the CO2 permeability of oocyte membranes. Possible explanations include 1) AQP1 expression alters the lipid composition of the cell membrane, 2) AQP1 expression causes overexpression of a native gas channel, and/or 3) AQP1 acts as a channel through which CO2 can permeate. Even if AQP1 should mediate a CO2 flux, it would remain to be determined whether this CO2movement is quantitatively important.

No abstract

An endogenous dopaminergic neurotoxin, N-methyl(R)salsolinol, was found to induce apoptosis in human dopaminergic SH-SY5Y cells by step-wise activation of apoptotic cascade; collapse in mitochondrial membrane potential, DCm, activation of caspases, and fragmentation of DNA. Recently, accumulation of gylceraldehyde-3-phosphate dehydrogenase (GAPDH) in nuclei was proposed to play an important role in apoptosis. In this paper, involvement of GAPDH in apoptosis induced by N-methyl(R)salsolinol was studied. The isoquinoline reduced DCm within 3 h, as detected by a¯uorescence indicator, JC-1, then after 16 h incubation, GAPDH accumulated in nuclei by detection with immunostaining. To clarify the role of GAPDH in apoptotic process, a stable cell line of Bcl-2 overexpressed SH-SY5Y cells was established. Overexpression of Bcl-2 prevented the decline in DCm and also apoptotic DNA damage induced by N-methyl(R)salsolinol. In Bcl-2 transfected cells, nuclear translocation of GAPDH was also completely suppressed. In addition, a novel antiparkinsonian drug, rasagiline, prevented nuclear accumulation of GAPDH induced by N-methyl(R)salsolinol in control cells. These results suggest that GAPDH may accumulate in nuclei as a consequence of signal transduction, which is antagonized by anti-apoptotic Bcl-2 protein family and rasagiline. The results are discussed in concern to intracellular mechanism underlying anti-apoptotic function of rasagiline analogues.

The effects of land cover and surface slope on lidar-derived elevation data were examined for a watershed in the piedmont of North Carolina. Lidar data were collected over the study area in a winter (leaf-off) overflight. Survey-grade elevation points (1,225) for six different land cover classes were used as reference points. Root mean squared error (RMSE) for land cover classes ranged from 14.5 cm to 36.1 cm. Land cover with taller canopy vegetation exhibited the largest errors. The largest mean error (36.1 cm RMSE) was in the scrub-shrub cover class. Over the small slope range (0°to 10°) in this study area, there was little evidence for an increase in elevation error with increased slopes. However, for low grass land cover, elevation errors do increase in a consistent manner with increasing slope. Slope errors increased with increasing surface slope, under-predicting true slope on surface slopes Ͼ2°. On average, the lidarderived elevation under-predicted true elevation regardless of land cover category. The under-prediction was significant, and ranged up to Ϫ23.6 cm under pine land cover.

NCBE (SLC4A10) is a member of the SLC4 family of bicarbonate transporters, several of which play important roles in intracellular-pH regulation and transepithelial transport. Here we characterize a new antibody that was generated in rabbit against a fusion protein consisting of maltose-binding protein and the first 135 amino acids (aa) of the N-terminus of human NCBE. Western blotting-both of purified peptides representing the initial ~120aa of the transporters and of full-length transporters expressed in Xenopus oocytes-demonstrated that the antibody is specific for NCBE versus the two most closely related proteins, NDCBE (SLC4A8) and NBCn1 (SLC4A7). Western blotting of tissue in four regions of adult mouse brain indicates that NCBE is expressed most abundantly in cerebral cortex (CX), cerebellum (CB) and hippocampus (HC), and less so in subcortex (SCX). NCBE protein was present in CX, CB, and HC microdissected to avoid choroid plexus. Immunocytochemistry shows that NCBE is present at the basolateral membrane of E18 fetal and adult choroid plexus. NCBE protein is present by western blot and immunocytochemistry in cultured and freshly dissociated HC neurons but not astrocytes. By western blot, nearly all NCBE in mouse and rat brain is highly N-glycosylated (~150 kDa). PNGase F reduces the MW of natural NCBE in mouse brain or human NCBE expressed in oocytes to approximately the predicted MW of the unglycosylated protein. In oocytes, mutating any one of the three consensus N-glycosylation sites reduces glycosylation of the other two, and the triple mutant exhibits negligible functional expression.

Objectives: To assess the reliability and validity of a depression screening tool — the PHQ‐9©Pfizer Inc. modified for use with Aboriginal and Torres Strait Islander people. We also sought to determine the prevalence of depression in a sample of Indigenous people with ischaemic heart disease (IHD). Methods: The modified PHQ‐9 was administered to a sample of Indigenous people with IHD by an Aboriginal Health Worker (AHW). Tool results were then compared with the results of a psychiatric diagnostic interview conducted by a medical practitioner. Thirty four IHD patients attending an Aboriginal Community Controlled Health Service (ACCHS) in Darwin in 2006 and 2007 participated in the study. The modified PHQ‐9's sensitivity, specificity, positive and negative predictive value were calculated for major and minor depression. Chronbach's alpha of the screening test was calculated to measure internal consistency. The prevalence of depression in the study group was also determined. Results: The prevalence of major depression in the sample was 15.4% (95% CI 7.2%‐29.7%). When assessing for major depression the modified PHQ‐9 was 80% sensitive (95% CI 66.4‐93.6%) and 71.4% (95% CI 56.0‐86.8%) specific. A ‘mini’ version of the modified PHQ‐9 demonstrated 100% sensitivity (95% CI 100%‐100%) and 12.5% specificity (95% CI 7.0% ‐25.7%) Chronbach's alpha was 0.8. Conclusion: The modified PHQ‐9 and the mini‐tool, showed promise in this setting. Further investigation with a larger number of Aboriginal and Torres Strait Islander participants is warranted. Implications: This study has implications both for the Medicare funded Aboriginal Adult Health Checks and for program planning for Aboriginal IHD patients.

A series of aliphatic propargylamine derivatives has been synthesized. Some of them possess highly potent, irreversible, selective, inhibitory activity toward monoamine oxidase B (MAO-B). The potency of the inhibitors is related to chain length and substitution of a hydrogen on the terminal carbon of the aliphatic chain. MAO inhibitory activity as assessed in vitro increased as the aliphatic carbon chain length increased. Substitution of a hydrogen by hydroxyl, carboxyl, or carbethoxyl groups at the aliphatic chain terminal or replacement of the methyl group on the nitrogen atom by an ethyl group considerably reduced the inhibitory activity. Stereospecific effects were observed with the R-(-)-enantiomer being 20-fold more active than the S-(+)-enantiomer. Inhibitors with relatively short carbon chain lengths (i.e. four to six carbons) were found to be more potent than those with longer chains in inhibiting brain MAO-B activity in vivo especially after oral administration. Chronic administration of low doses of the aliphatic propargylamines caused a slight cumulative inhibition of MAO-A activity in the mouse brain. These MAO-B inhibitors appear to be nontoxic, and they do not possess an amphetamine-like moiety in their structure as is the case for deprenyl. We expect that these aliphatic propargylamines may be useful in the treatment in certain neuropsychiatric disorders.

No abstract