Molecular mechanisms in the brain are assumed to cause the symptoms and severity of neuropsychiatric disorders. This review concerns the elusive nature of relationships between the severity of depressive disorders and neuromolecular processes studied by positron emission tomography (PET). Recent PET studies of human depression have focused on serotonergic, dopaminergic, muscarinic, nicotinic, and GABAergic receptors, as well as central processes dependent on monoamine oxidase, phosphodiesterase type 4, amyloid plaques, neurofibrillar tangles, and P-glycoprotein. We find that reliable causal links between neuromolecular mechanisms and relief from depressive disorders have yet to be convincingly demonstrated. This situation may contribute to the currently limited use of PET for exploring the neuropathways that are currently viewed as being responsible for beneficial effects of antidepressant treatment regimes.
depressive disorders; symptom severity; negative emotions; positron emission tomography; brain imaging; neurobiology; neurotransmitters; reliability
A recent publication described finding GB virus C (GBV-C) RNA in four of twenty two dromedary camel sera, and sequence analysis found that these viruses were phylogenetically clustered within human GBV-C isolates. Since all other GB viruses to date form monophyletic groups according to their host species, the close relationship between the sequences generated from camel sera and human GBV-C isolates seemed implausible, leading us to conduct an independent analysis of the sequences. Our investigation found three lines of evidence arguing against GBV-C infection in dromedary camels. First, strong evidence of artifactual sequence generation was identified for some of the sequences. Secondly, the sequence diversity within individual camel sera was ten- to one-hundred fifty two-fold greater than that described for GBV-C within a human host. Finally, GBV-C sequences generated from each camel shared near complete identity with human isolates previously described by the same laboratory. Taken together, these data strongly suggest laboratory contamination. We suggest that additional validation experiments are needed before it is possible to conclude that camels are permissive for GBV-C infection.
GB virus; Flavirirus; Dromedary Camel
The object of this study was to evaluate a novel surgical technique in the treatment of adult degenerative scoliosis and present our early experience with the minimally invasive lateral approach for anterior longitudinal ligament release to provide lumbar lordosis and examine its impact on sagittal balance. Methods. All patients with adult spinal deformity (ASD) treated with the minimally invasive lateral retroperitoneal transpsoas interbody fusion (MIS LIF) for release of the anterior longitudinal ligament were examined. Patient demographics, clinical data, spinopelvic parameters, and outcome measures were recorded. Results. Seven patients underwent release of the anterior longitudinal ligament (ALR) to improve sagittal imbalance. All cases were split into anterior and posterior stages, with mean estimated blood loss of 125 cc and 530 cc, respectively. Average hospital stay was 8.3 days, and mean follow-up time was 9.1 months. Comparing pre- and postoperative 36′′ standing X-rays, the authors discovered a mean increase in global lumbar lordosis of 24 degrees, increase in segmental lumbar lordosis of 17 degrees per level of ALL released, decrease in pelvic tilt of 7 degrees, and decrease in sagittal vertical axis of 4.9 cm. At the last followup, there was a mean improvement in VAS and ODI scores of 26.2% and 18.3%. Conclusions. In the authors' early experience, release of the anterior longitudinal ligament using the minimally invasive lateral retroperitoneal transpsoas approach may be a feasible alternative in correcting sagittal deformity.
The production of thromboxane A2 (TXA2) and prostacyclin (prostaglandin I2, PGI2) is known to be increased in patients with atherosclerosis. In this study, we evaluated the influence of gender on TXA2 and PGI2 production and their association with the progression of atherosclerosis in apolipoprotein E-null (ApoE−/−) mice maintained on a high fat diet for 3 months. En face analyses of aortas showed marked increases in plaque formation in female ApoE−/− mice. Quantification of the hematoxylin/eosin (H & E) stained cross sections of the aortic arch revealed 3 to 4-fold higher plaque thickness in female ApoE−/− mice. Analyses of 24-h urine samples for 11-dehydro TXB2 and 2, 3-dinor-6-keto PGF1α indicated that female ApoE−/− mice produce up to 15-fold more TXA2 and 50% less PGI2 than the age matched males. Interestingly, the serum cholesterol levels in ApoE−/− females were 20% lower than males on the high fat regimen. No gender-associated changes in the number of T lymphocytes, mast cells and macrophages were evident in the lesion areas of ApoE−/− mice. The results suggest that the markedly elevated TXA2 production and reduced PGI2 production are gender-related proatherogenic risk factors in female ApoE−/− mice.
ApoE−/− mice; Atherosclerosis; Gender difference; Thromboxane A2; Prostaglandin I2
Androgen ablation therapy represents the first line of therapeutic intervention in men with advanced or recurrent prostate tumors. However, the incomplete efficacy and lack of durable response to this clinical strategy highlights an urgent need for alternative treatment options to improve patient outcomes. Targeting the molecular chaperone heat shock protein 90 (Hsp90) represents a potential avenue for therapeutic intervention as its inhibition results in the coordinate blockade of multiple oncogenic signaling pathways in cancer cells. Moreover, Hsp90 is essential for the stability and function of numerous client proteins, a number of which have been causally implicated in the pathogenesis of prostate cancer, including the androgen receptor (AR). Here, we examined the preclinical activity of ganetespib, a small molecule inhibitor of Hsp90, in a panel of prostate cancer cell lines. Ganetespib potently decreased viability in all lines, irrespective of their androgen sensitivity or receptor status, and more effectively than the ansamycin inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG). Interestingly, while ganetespib exposure decreased AR expression and activation, the constitutively active V7 truncated isoform of the receptor was unaffected by Hsp90 inhibition. Mechanistically, ganetespib exerted concomitant effects on mitogenic and survival pathways, as well as direct modulation of cell cycle regulators, to induce growth arrest and apoptosis. Further, ganetespib displayed robust antitumor efficacy in both AR-negative and positive xenografts, including those derived from the 22Rv1 prostate cancer cell line that co-expresses full-length and variant receptors. Together these data suggest that further investigation of ganetespib as a new therapeutic treatment for prostate cancer patients is warranted.
Hsp90 inhibition; ganetespib; androgen receptor; prostate cancer; cancer therapy
Little is known about the effects of manganese (Mn) exposure over neurodevelopment and whether these early insults result in effects lasting into adulthood. To determine if early Mn exposure produces lasting neurobehavioral and neurochemical effects, we treated neonate rats with oral Mn (0, 25, or 50 mg Mn/kg/d over PND 1–21) and evaluated 1) behavioral performance in the open arena in the absence (PND 97) and presence (PND 98) of a d-amphetamine challenge, 2) brain dopamine D1 and D2-like receptors and dopamine transporter densities in the prefrontal cortex, striatum, and nucleus accumbens (PND 107), and 3) astrocyte marker glial fibrillary acidic protein (GFAP) levels in these same brain regions (PND 24 and 107). We found that pre-weaning Mn exposure did not alter locomotor activity or behavior disinhibition in adult rats, though Mn-exposed animals did exhibit an enhanced locomotor response to d-amphetamine challenge. Pre-weaning Mn exposure led to increased D1 and D2 receptor levels in the nucleus accumbens and prefrontal cortex, respectively, compared to controls. We also found increased GFAP expression in the prefrontal cortex in Mn-exposed PND 24 weanlings, and increased GFAP levels in prefrontal cortex, medial striatum and nucleus accumbens of adult (PND 107) rats exposed to pre-weaning Mn, indicating an effect of Mn exposure on astrogliosis that persisted and/or progressed to other brain regions in adult animals. These data show that pre-weaning Mn exposure leads to lasting molecular and functional impacts in multiple brain regions of adult animals, long after brain Mn levels returned to normal.
neonate exposure; lasting effects; dopamine; rat; astrocyte; D1; D2; DAT; GFAP
The neurotoxic amino acid, domoic acid (DA), is naturally produced by marine phytoplankton and presents a significant threat to the health of marine mammals, seabirds and humans via transfer of the toxin through the foodweb. In humans, acute exposure causes a neurotoxic illness known as amnesic shellfish poisoning characterized by seizures, memory loss, coma and death. Regular monitoring for high DA levels in edible shellfish tissues has been effective in protecting human consumers from acute DA exposure. However, chronic low-level DA exposure remains a concern, particularly in coastal and tribal communities that subsistence harvest shellfish known to contain low levels of the toxin. Domoic acid exposure via consumption of planktivorous fish also has a profound health impact on California sea lions (Zalophus californianus) affecting hundreds of animals yearly. Due to increasing algal toxin exposure threats globally, there is a critical need for reliable diagnostic tests for assessing chronic DA exposure in humans and wildlife. Here we report the discovery of a novel DA-specific antibody response that is a signature of chronic low-level exposure identified initially in a zebrafish exposure model and confirmed in naturally exposed wild sea lions. Additionally, we found that chronic exposure in zebrafish caused increased neurologic sensitivity to DA, revealing that repetitive exposure to DA well below the threshold for acute behavioral toxicity has underlying neurotoxic consequences. The discovery that chronic exposure to low levels of a small, water-soluble single amino acid triggers a detectable antibody response is surprising and has profound implications for the development of diagnostic tests for exposure to other pervasive environmental toxins.
High folate intake may increase the risk of cancer, especially in the elderly. The present study examined the effects of ageing and dietary folate on uracil misincorporation into DNA, which has a mutagenic effect, in the mouse colon and liver. Old (18 months; n 42) and young (4 months; n 42) male C57BL/6 mice were pair-fed with four different amino acid-defined diets for 20 weeks: folate deplete (0 mg/kg diet); folate replete (2 mg/kg diet); folate supplemented (8 mg/kg diet); folate deplete (0 mg/kg diet) with thymidine supplementation (1·8 g/kg diet). Thymidylate synthesis from uracil requires folate, but synthesis from thymidine is folate independent. Liver folate concentrations were determined by the Lactobacillus casei assay. Uracil misincorporation into DNA was measured by a GC/MS method. Liver folate concentrations demonstrated a stepwise increase across the spectrum of dietary folate levels in both old (P=0·003) and young (P<0·001) mice. Uracil content in colonic DNA was paradoxically increased in parallel with increasing dietary folate among the young mice (P trend=0·033), but differences were not observed in the old mice. The mean values of uracil in liver DNA, in contrast, decreased with increasing dietary folate among the old mice, but it did not reach a statistically significant level (P<0·1). Compared with the folate-deplete group, thymidine supplementation reduced uracil misincorporation into the liver DNA of aged mice (P=0·026). The present study suggests that the effects of folate and thymidine supplementation on uracil misincorporation into DNA differ depending on age and tissue. Further studies are needed to clarify the significance of increased uracil misincorporation into colonic DNA of folate-supplemented young mice.
Folate; Uracil; Thymidine; Colon; Liver; Mice
Lipo-chitooligosaccharides (LCOs), signal compounds produced by N2-fixing rhizobacteria after isoflavone induction, initiate nodule formation in host legumes. Given LCOs' structural similarity to pathogen-response-eliciting chitin oligomers, foliar application of LCOs was tested for ability to induce stress-related genes under optimal growth conditions. In order to study the effects of LCO foliar spray under stressed conditions, soybean (Glycine max) seedlings grown at optimal temperature were transferred to sub-optimal temperature. After a 5-day acclimation period, the first trifoliate leaves were sprayed with 10−7 M LCO (NodBj-V (C18∶1, MeFuc)) purified from genistein-induced Bradyrhizobium japonicum culture, and harvested at 0 and 48 h following treatment. Microarray analysis was performed using Affymetrix GeneChip® Soybean Genome Arrays. Compared to the control at 48 h after LCO treatment, a total of 147 genes were differentially expressed as a result of LCO treatment, including a number of stress-related genes and transcription factors. In addition, during the 48 h time period following foliar spray application, over a thousand genes exhibited differential expression, including hundreds of those specific to the LCO-treated plants. Our results indicated that the dynamic soybean foliar transcriptome was highly responsive to LCO treatment. Quantitative real-time PCR (qPCR) validated the microarray data.
Systemic chemotherapy using two-drug platinum-based regimens for the treatment of advanced stage non-small cell lung cancer (NSCLC) has largely reached a plateau of effectiveness. Accordingly, efforts to improve survival and quality of life outcomes have more recently focused on the use of molecularly targeted agents, either alone or in combination with standard of care therapies such as taxanes. The molecular chaperone heat shock protein 90 (Hsp90) represents an attractive candidate for therapeutic intervention, as its inhibition results in the simultaneous blockade of multiple oncogenic signaling cascades. Ganetespib is a non-ansamycin inhibitor of Hsp90 currently under clinical evaluation in a number of human malignancies, including NSCLC. Here we show that ganetespib potentiates the cytotoxic activity of the taxanes paclitaxel and docetaxel in NSCLC models. The combination of ganetespib with paclitaxel, docetaxel or another microtubule-targeted agent vincristine resulted in synergistic antiproliferative effects in the H1975 cell line in vitro. These benefits translated to improved efficacy in H1975 xenografts in vivo, with significantly enhanced tumor growth inhibition observed in combination with paclitaxel and tumor regressions seen with docetaxel. Notably, concurrent exposure to ganetespib and docetaxel improved antitumor activity in 5 of 6 NSCLC xenograft models examined. Our data suggest that the improved therapeutic indices are likely to be mechanistically multifactorial, including loss of pro-survival signaling and direct cell cycle effects resulting from Hsp90 modulation by ganetespib. Taken together, these findings provide preclinical evidence for the use of this combination to treat patients with advanced NSCLC.
Electronic supplementary material
The online version of this article (doi:10.1007/s10637-011-9790-6) contains supplementary material, which is available to authorized users.
Hsp90 inhibition; Ganetespib; Taxanes; Non-small cell lung cancer; Cancer therapy
We compared six kinetic models with and without the requirement of arterial cannulation for estimating the binding potential of [N-methyl-11C]mirtazapine in the living human brain.
Distribution volumes of [N-methyl-11C]mirtazapine in brain regions were estimated using single- and two-tissue compartment models as well as a graphical plasma input model. The two-tissue compartment model provided a direct estimate of the binding potentials of [N-methyl-11C]mirtazapine in brain regions, while binding potentials of the single-tissue compartment model and the graphical plasma input model were estimated indirectly from ratios of distribution volumes in brain regions. We obtained also direct estimates of binding potentials using a graphical reference tissue model and two nonlinear reference tissue models.
The two-tissue compartment model required several fits with different initial guesses for avoiding negative values of parameters. Despite the extra fits, estimates of distribution volumes and binding potentials of [N-methyl-11C]mirtazapine obtained by the two-tissue compartment model were far more variable than those produced by the other methods. The graphical plasma input method and the graphical reference tissue method provided estimates of the binding potential that correlated closely, but differed in magnitude. The single-tissue compartment model provided relatively low estimates of binding potentials with curves that failed to fit the data as well as the three other methods that used the entire series of positron emission tomography data. The reference tissue method and the simplified reference tissue method provided similar, consistent estimates of binding potentials. However, certain assumptions of the simplified reference tissue method may not be fulfilled by the radioligand.
The reference tissue method is appropriate for estimating the binding potential of [N-methyl-11C]mirtazapine in regions of the human brain so that the binding potential of [N-methyl-11C]mirtazapine can be estimated without arterial cannulation.
[11C]mirtazapine; antidepressant; PET; kinetic models; distribution volume; binding potential; human brain
Dysregulation of myelin sulfatides is a risk factor for cognitive decline with age. Vitamin K is present in high concentrations in the brain and has been implicated in the regulation of sulfatide metabolism. Our objective was to investigate the age-related interrelation between dietary vitamin K and sulfatides in myelin fractions isolated from the brain regions of Fischer 344 male rats fed one of two dietary forms of vitamin K: phylloquinone or its hydrogenated form, dihydrophylloquinone for 28 days. Both dietary forms of vitamin K were converted to menaquinone-4 in the brain. The efficiency of dietary dihydrophylloquinone conversion to menaquinone-4 compared to dietary phylloquinone was lower in the striatum and cortex, and was similar to those in the hippocampus. There were significant positive correlations between sulfatides and menaquinone-4 in the hippocampus (phylloquinone-supplemented diet -12mo and 24mo; dihydrophylloquinone -supplemented diet - 12mo) and cortex (phylloquinone-supplemented diet -12mo and 24 mo). No significant correlations were observed in the striatum. Furthermore, sulfatides in the hippocampus were significantly positively correlated with MK-4 in serum. This is the first attempt to establish and characterize a novel animal model that exploits the inability of dietary dihydrophylloquinone to convert to brain menaquinone-4 to study the dietary effects of vitamin K on brain sulfatide in brain regions controlling motor and cognitive functions. Our findings suggest that this animal model may be useful for investigation of the effect of the dietary vitamin K on sulfatide metabolism, myelin structure, and behavior functions.
Myelin; Phylloquinone; Vitamin K; Menaquinone-4; Sulfatides; Diet
Research on the role of environmental lead exposure in the complex etiology of premature birth has yielded inconsistent results. We assessed the trimester-specific effect of prenatal lead exposure on gestational age and risk of premature delivery.
We used linear and logistic regression to identify critical windows of susceptibility to lead exposure upon gestational length.
In single-trimester models, decreases in gestational length were most strongly associated with first and second trimester blood lead. In adjusted logistic regression models a one-standard deviation increase in second trimester blood lead was associated with an odds ratio of prematurity of 1.75 (95%CI: 1.02, 3.02).
Maternal whole blood lead levels measured during first and second trimesters yielded the most prominent inverse association with length of gestation and increased the risk of prematurity. .
The hypothesis of this study is that a folate-deficient diet (FD) has a greater effect on cholinergic system in the peripheral nervous system than in the brain, and that this effect escalates with age. It was tested by comparing choline and acetylcholine levels in male Sprague Dawley rats fed either control or folate-deficient diets for 10 weeks, starting at age 4 weeks (the young group) or 9 months (the adult group). FD consumption resulted in depletion of plasma folate in both age groups. In young folate-deficient rats, liver and lung choline levels were significantly lower than those in the respective controls. No other significant effects of FD on choline and acetylcholine metabolism were found in young rats. In adult rats, FD consumption markedly decreased choline levels in the liver, kidneys, and heart; furthermore, choline levels in the cortex and striatum were moderately elevated, although hippocampal choline levels were not affected. Acetylcholine levels were higher in the heart, cortex, and striatum but lower in the hippocampus in adult folate-deficient rats, as compared to controls. Higher acetylcholine levels in the striatum in adult folate-deficient rats were also associated with higher dopamine release in the striatal slices. Thus, both age groups showed higher cholinergic metabolic sensitivity to FD in the peripheral nervous system than in the brain. However, compensatory abilities appeared to be better in the young group, implicating the adult group as a preferred model for further investigation of folate-choline-acetylcholine interactions and their role in brain plasticity and cognitive functions.
Folic acid; choline; neurotransmitters; liver; hippocampal choline; rats
Older age, dietary folate and chronic alcohol consumption are important risk factors for the development of colon cancer. The present study examined the effects of ageing, folate and alcohol on genomic and p16-specific DNA methylation, and p16 expression in the murine colon. Old (aged 18 months; n 70) and young (aged 4 months; n 70) male C57BL/6 mice were pair-fed either a Lieber-DeCarli liquid diet with alcohol (18 % of energy), a Lieber-DeCarli diet with alcohol (18 %) and reduced folate (0·25 mg folate/l) or an isoenergetic control diet (0·5 mg folate/l) for 5 or 10 weeks. Genomic DNA methylation, p16 promoter methylation and p16 gene expression were analysed by liquid chromatography–MS, methylation-specific PCR and real-time RT-PCR, respectively. Genomic DNA methylation was lower in the colon of old mice compared with young mice (P<0·02) at 10 weeks. Alcohol consumption did not alter genomic DNA methylation in the old mouse colon, whereas it tended to decrease genomic DNA methylation in young mice (P = 0·08). p16 Promoter methylation and expression were higher in the old mouse colon compared with the corresponding young groups. There was a positive correlation between p16 promoter methylation and p16 expression in the old mouse colon (P<0·02). In young mice the combination of alcohol and reduced dietary folate led to significantly decreased p16 expression compared with the control group (P<0·02). In conclusion, ageing and chronic alcohol consumption alter genomic DNA methylation, p16 promoter methylation and p16 gene expression in the mouse colon, and dietary folate availability can further modify the relationship with alcohol in the young mouse.
Alcohol; DNA methylation; p16; Folate; Ageing; Colon
Surface treatment of biological tissue sections improves detection of peptides and proteins for mass spectrometry imaging. However, liquid surface treatments can result in diffusion of surface analytes and fragile tissue sections can be easily damaged by typical washing solvents. Here, we present a new surface washing procedure for mass spectrometry imaging. This procedure uses solvent wetted fiber-free paper to enable local washing of tissue sections for mass spectrometry imaging and tissue profiling experiments. In addition, the method allows fragile tissues that cannot be treated by conventional washing techniques to be analyzed by mass spectrometry imaging.
Imaging Mass Spectrometry; Washing; Peptides and Proteins; MALDI; SIMS
Epidemiological studies in children have reported associations between elevated dietary manganese (Mn) exposure and neurobehavioral and neurocognitive deficits. To better understand the relationship between early Mn exposure and neurobehavioral deficits, we treated neonate rats with oral Mn doses of 0, 25, or 50 mg Mn/kg/d over postnatal day (PND) 1 – 21, and evaluated behavioral performance using open arena (PND 23), elevated plus maze (PND 23), and 8-arm radial maze (PND 33–46) paradigms. Brain dopamine D1 and D2-like receptors, and DAT transporter densities were determined on PND 24, and blood and brain Mn levels were measured to coincide with behavioral testing (PND 24, PND 36). Pre-weaning Mn exposure caused hyperactivity and behavioral disinhibition in the open arena, but no altered behavior in the elevated plus maze. Manganese-exposed males committed significantly more reference and marginally more working errors in the radial arm maze compared to controls. Fewer Mn exposed males achieved the radial maze learning criterion, and they required more session days to reach it compared to controls. Manganese-exposed animals also exhibited a greater frequency of stereotypic response strategy in searching for the baited arms in the maze. These behavioral and learning deficits were associated with altered expression of the dopamine D1 and D2 receptors and the dopamine transporter in prefrontal cortex, nucleus accumbens, and dorsal striatum. These data corroborate epidemiological studies in children, and suggest that exposure to Mn during neurodevelopment significantly alters dopaminergic synaptic environments in brain nuclei that mediate control of executive function behaviors, such as reactivity and cognitive flexibility.
Neonate; behavior; executive function; dopamine; rat; locomotor; D1; D2; DAT
We describe the construction and application of a new MALDI source for FT-ICR mass spectrometry imaging. The source includes a translational X-Y positioning stage with a 10 × 10 cm range of motion for analysis of large sample areas, a quadrupole for mass selection, and an external octopole ion trap with electrodes for the application of an axial potential gradient for controlled ion ejection. An off-line LC MALDI MS/MS run demonstrates the utility of the new source for data- and position-dependent experiments. A FT-ICR MS imaging experiment of a coronal rat brain section yields ∼200 unique peaks from m/z 400–1100 with corresponding mass-selected images. Mass spectra from every pixel are internally calibrated with respect to polymer calibrants collected from an adjacent slide.
Fourier transform; Ion cyclotron resonance; FTMS; Imaging mass spectrometry; INCAS
The eye lens presents a unique opportunity to explore roles for specific molecules in cell proliferation, differentiation and development because cells remain in place throughout life and, like red blood cells and keratinocytes, they go through the most extreme differentiation, including removal of nuclei and cessation of protein synthesis. Ubiquitination controls many critical cellular processes, most of which require specific lysines on ubiquitin (Ub). Of the 7 lysines (K) least is known about effects of modification of K6.
Methodology and Principal Findings
We replaced K6 with tryptophan (W) because K6 is the most readily modified K and W is the most structurally similar residue to biotin. The backbone of K6W-Ub is indistinguishable from that of Wt-Ub. K6W-Ub is effectively conjugated and deconjugated but the conjugates are not degraded via the ubiquitin proteasome pathways (UPP). Expression of K6W-ubiquitin in the lens and lens cells results in accumulation of intracellular aggregates and also slows cell proliferation and the differentiation program, including expression of lens specific proteins, differentiation of epithelial cells into fibers, achieving proper fiber cell morphology, and removal of nuclei. The latter is critical for transparency, but the mechanism by which cell nuclei are removed has remained an age old enigma. This was also solved by expressing K6W-Ub. p27kip, a UPP substrate accumulates in lenses which express K6W-Ub. This precludes phosphorylation of nuclear lamin by the mitotic kinase, a prerequisite for disassembly of the nuclear membrane. Thus the nucleus remains intact and DNAseIIβ neither gains entry to the nucleus nor degrades the DNA. These results could not be obtained using chemical proteasome inhibitors that cannot be directed to specific tissues.
Conclusions and Significance
K6W-Ub provides a novel, genetic means to study functions of the UPP because it can be targeted to specific cells and tissues. A fully functional UPP is required to execute most stages of lens differentiation, specifically removal of cell nuclei. In the absence of a functional UPP, small aggregate prone, cataractous lenses are formed.
Manganism is a disease with no cure. This study identifies a mammalian protein with manganese-sensitive trafficking. The findings provide an important, novel example of regulated sorting under physiological conditions particularly in that a lumenal, rather than cytoplasmic, sequence confers the regulation.
Manganese is an essential element that is also neurotoxic at elevated exposure. However, mechanisms regulating Mn homeostasis in mammalian cells are largely unknown. Because increases in cytosolic Mn induce rapid changes in the localization of proteins involved in regulating intracellular Mn concentrations in yeast, we were intrigued to discover that low concentrations of extracellular Mn induced rapid redistribution of the mammalian cis-Golgi glycoprotein Golgi phosphoprotein of 130 kDa (GPP130) to multivesicular bodies. GPP130 was subsequently degraded in lysosomes. The Mn-induced trafficking of GPP130 occurred from the Golgi via a Rab-7–dependent pathway and did not require its transit through the plasma membrane or early endosomes. Although the cytoplasmic domain of GPP130 was dispensable for its ability to respond to Mn, its lumenal stem domain was required and it had to be targeted to the cis-Golgi for the Mn response to occur. Remarkably, the stem domain was sufficient to confer Mn sensitivity to another cis-Golgi protein. Our results identify the stem domain of GPP130 as a novel Mn sensor in the Golgi lumen of mammalian cells.
Estimation of future glucose concentrations is a crucial task for diabetes management. Predicted glucose values can be used for early hypoglycemic/hyperglycemic alarms or for adjustment of insulin injections or insulin infusion rates of manual or automated pumps. Continuous glucose monitoring (CGM) technologies provide glucose readings at a high frequency and consequently detailed insight into the subject's glucose variations. The objective of this research is to develop reliable subject-specific glucose prediction models using CGM data.
Two separate patient databases collected under hospitalized (disturbance-free) and normal daily life conditions are used for validation of the proposed glucose prediction algorithm. Both databases consist of glucose concentration data collected at 5-min intervals using a CGM device. Using time-series analysis, low-order linear models are developed from patients' own CGM data. The time-series models are integrated with recursive identification and change detection methods, which enables dynamic adaptation of the model to inter-/intra-subject variability and glycemic disturbances. Prediction performance is evaluated in terms of glucose prediction error and Clarke Error Grid analysis (CG-EGA).
Prediction errors are significantly reduced with recursive identification of the models, and predictions are further improved with inclusion of a parameter change detection method. CG-EGA analysis results in accurate readings of 90% or more.
Subject-specific glucose prediction strategy has been developed. Including a change detection method to the recursive algorithm improves the prediction accuracy. The proposed modeling algorithm with small number of parameters is a good candidate for installation in portable devices for early hypoglycemic/hyperglycemic alarms and for closing the glucose regulation loop with an insulin pump.
Although adverse neuropsychological and neurological health effects are well known among workers with high manganese (Mn) exposures in mining, ore‐processing and ferroalloy production, the risks among welders with lower exposures are less well understood.
Confined space welding in construction of a new span of the San Francisco–Oakland Bay Bridge without adequate protection was studied using a multidisciplinary method to identify the dose–effect relationship between adverse health effects and Mn in air or whole blood. Bridge welders (n = 43) with little or no personal protection equipment and exposed to a welding fume containing Mn, were administered neurological, neuropsychological, neurophysiological and pulmonary tests. Outcome variables were analysed in relation to whole blood Mn (MnB) and a Cumulative Exposure Index (CEI) based on Mn‐air, duration and type of welding. Welders performed a mean of 16.5 months of welding on the bridge, were on average 43.8 years of age and had on average 12.6 years of education.
The mean time weighted average of Mn‐air ranged from 0.11–0.46 mg/m3 (55% >0.20 mg/m3). MnB >10 µg/l was found in 43% of the workers, but the concentrations of Mn in urine, lead in blood and copper and iron in plasma were normal. Forced expiratory volume at 1s: forced vital capacity ratios (FEV1/FVC) were found to be abnormal in 33.3% of the welders after about 1.5 years of welding at the bridge. Mean scores of bradykinesia and Unified Parkinson Disease Rating Scale exceeded 4 and 6, respectively. Computer assisted tremor analysis system hand tremor and body sway tests, and University of Pennsylvania Smell Identification Test showed impairment in 38.5/61.5, 51.4 and 88% of the welders, respectively. Significant inverse dose–effect relationships with CEI and/or MnB were found for IQ (p⩽0.05), executive function (p⩽0.03), sustaining concentration and sequencing (p⩽0.04), verbal learning (p⩽0.01), working (p⩽0.04) and immediate memory (p⩽0.02), even when adjusted for demographics and years of welding before Bay Bridge. Symptoms reported by the welders while working were: tremors (41.9%); numbness (60.5%); excessive fatigue (65.1%); sleep disturbance (79.1%); sexual dysfunction (58.1%); toxic hallucinations (18.6%); depression (53.5%); and anxiety (39.5%). Dose–effect associations between CEI and sexual function (p<0.05), fatigue (p<0.05), depression (p<0.01) and headache (p<0.05) were statistically significant.
Confined space welding was shown to be associated with neurological, neuropsychological and pulmonary adverse health effects. A careful enquiry of occupational histories is recommended for all welders presenting with neurological or pulmonary complaints, and a more stringent prevention strategy should be considered for Mn exposure due to inhalation of welding fume.
Manganese (Mn) is a redox-active element, and whereas its uptake, disposition, and toxicity in mammals may depend in part on its oxidation state, the proteins affecting manganese oxidation state and speciation in vivo are not well known. Studies have suggested that the oxidase protein ceruloplasmin (Cp) mediates iron and manganese oxidation and loading onto plasma transferrin (Tf), as well as cellular iron efflux. We hypothesized that ceruloplasmin may also affect the tissue distribution and eventual neurotoxicity of manganese. To test this, aceruloplasminemic versus wild-type mice were treated with a single i.p. 54Mn tracer dose, or elevated levels of manganese subchronically (0, 7.5, or 15 mg Mn/kg s.c., three doses per week for 4 weeks), and evaluated for transferrin-bound manganese, blood manganese partitioning, tissue manganese disposition, and levels of brain glutathione, thiobarbituric acid reactive substances (TBARS), and protein carbonyls as measures of oxidative stress, and open arena activity. Results show that ceruloplasmin does not play a role in the loading of manganese onto plasma transferrin in vivo, or in the partitioning of manganese between the plasma and cellular fractions of whole blood. Ceruloplasmin did, however, affect the retention of manganese in blood and its distribution to tissues, most notably kidney and to a lesser extent brain and lung. Results also indicate that ceruloplasmin interacted with chronic elevated manganese exposures to produce greater levels of brain oxidative stress. These results provide evidence that metal oxidase proteins play an important role in altering neurotoxicity arising from elevated manganese exposures.
manganese; ceruloplasmin; transferrin; oxidation state; neurotoxicity
High intake of fish oil with a low omega-6 (n-6)/omega-3 (n-3) polyunsaturated fatty acid (PUFA) ratio has been suggested to protect against many chronic diseases. However, the effect of different ratios of dietary n-6 and n-3 PUFA on lung tumorigenesis has not been investigated. In this study, we examined the effect of a 4 month dietary supplementation with corn oil (with a high n-6/n-3 ratio) and fish oil (with a low n-6/n-3 ratio) as compared with soybean oil (isocaloric control with the same n-6/n-3 ratio as the base diet) on tumor incidence and tumor prevalence in the A/J mouse model of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung carcinogenesis. We found that dietary supplementation had no effect on overall lung tumor incidence but fish oil supplementation was able to decrease lung tumor prevalence by 78% and 80%, compared to groups receiving soybean oil and corn oil supplementation, respectively. The inhibitory effect of fish oil on lung tumor prevalence was associated with increased expressions of cell cycle inhibitor p21Cip1 and lipoxygenase isoforms 15-LOX in the lungs. These data suggest that fish oil with a low ratio of n-6/n-3 PUFA could be beneficial in the prevention of lung carcinogenesis.
fish oil; omega-3 polyunsaturated fatty acids; lung cancer; lipoxygenase enzymes
Folate is required for biological methylation and nucleotide synthesis, aberrations of which are thought to be the mechanisms that enhance colorectal carcinogenesis produced by folate inadequacy. These functions of folate also depend on the availability of other B-vitamins that participate in “one-carbon metabolism,” including B2, B6 and B12. Our study therefore investigated whether combined dietary restriction of these vitamins amplifies aberrations in the epigenetic and genetic integrity of the p53 gene that is induced by folate depletion alone. Ninety-six mice were group pair-fed diets with different combinations of B-vitamin depletion over 10 weeks. DNA and RNA were extracted from epithelial cells isolated from the colon. Within the hypermutable region of p53 (exons 5–8), DNA strand breaks were induced within exons 6 and 8 by folate combined with B2, B6 and B12 restriction (p < 0.05); such effects were not significantly induced by mild folate depletion alone. Similarly, a minor degree of hypomethylation of exon 6 produced by isolated folate depletion was significantly amplified (p ≤ 0.05) by simultaneous depletion of all 4 B-vitamins. Furthermore, the expression of p53 and MDM2 were significantly decreased (p ≤ 0.05) by the combined depletion state but not by folate depletion alone. These data indicate that inadequacies of other 1-carbon vitamins may amplify aberrations of the p53 gene induced by folate depletion alone, implying that concurrent inadequacies in several of these vitamins may have added tumorigenic potential beyond that observed with isolated folate depletion.
B-vitamin; methylation; p53; strand breaks