Calcium Profile Research Articles

Impairment of mitochondrial calcium handling in a mtSOD1 cell culture model of motoneuron disease

BackgroundAmyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by the selective loss of motor neurons (MN) in the brain stem and spinal cord. Intracellular disruptions of cytosolic and mitochondrial calcium have been associated with selective MN degeneration, but the underlying mechanisms are not well understood. The present evidence supports a hypothesis that mitochondria are a target of mutant SOD1-mediated toxicity in familial amyotrophic lateral sclerosis (fALS) and intracellular alterations of cytosolic and mitochondrial calcium might aggravate the course of this neurodegenerative disease. In this study, we used a fluorescence charged cool device (CCD) imaging system to separate and simultaneously monitor cytosolic and mitochondrial calcium concentrations in individual cells in an established cellular model of ALS.ResultsTo gain insights into the molecular mechanisms of SOD1G93A associated motor neuron disease, we simultaneously monitored cytosolic and mitochondrial calcium concentrations in individual cells. Voltage – dependent cytosolic Ca2+ elevations and mitochondria – controlled calcium release mechanisms were monitored after loading cells with fluorescent dyes fura-2 and rhod-2. Interestingly, comparable voltage-dependent cytosolic Ca2+ elevations in WT (SH-SY5YWT) and G93A (SH-SY5YG93A) expressing cells were observed. In contrast, mitochondrial intracellular Ca2+ release responses evoked by bath application of the mitochondrial toxin FCCP were significantly smaller in G93A expressing cells, suggesting impaired calcium stores. Pharmacological experiments further supported the concept that the presence of G93A severely disrupts mitochondrial Ca2+ regulation.ConclusionIn this study, by fluorescence measurement of cytosolic calcium and using simultaneous [Ca2+]i and [Ca2+]mito measurements, we are able to separate and simultaneously monitor cytosolic and mitochondrial calcium concentrations in individual cells an established cellular model of ALS. The primary goals of this paper are (1) method development, and (2) screening for deficits in mutant cells on the single cell level. On the technological level, our method promises to serve as a valuable tool to identify mitochondrial and Ca2+-related defects during G93A-mediated MN degeneration. In addition, our experiments support a model where a specialized interplay between cytosolic calcium profiles and mitochondrial mechanisms contribute to the selective degeneration of neurons in ALS.

Partial Migration of Fishes as Exemplified by the Estuarine‐Dependent White Perch

AbstractPartial migration defines the phenomenon of coexisting groups exhibiting migratory and resident behavior within the same population. In avian ecology, partial migration is a fundamental behavior that underlies the evolution of migration in general. Among fish taxa, the terminology and theory associated with partial migration has predominantly been used to describe salmon ecophenotypes, but the behavior is more widespread. Here, we ecophenotypes, but the behavior is more widespread. Here, we document partial migration for the estuarine‐dependent white perch (Morone americana), in the Patuxent River estuary (Chesapeake Bay, Maryland), wherein a portion of the population resides in freshwater natal habitats and another portion migrates down‐estuary into brackish water (salinities>3) habitats. Life‐time migration histories were examined using otolith strontium:calcium profile analysis. Alternative life history tactics, initiated during the juvenile period in response to individual physiological condition, persisted over the lifetime of the individual and had population‐level consequences, including differences in growth rate and productivity. Based upon a review of recent literature, we argue that pratical migration is more widespread among fishes than previously recognized, and such population structure has important implications for population dynamics and persistence.

MCell Model of Presynaptic Calcium Dynamics Predicts the Structural Correlates of Short-term Synaptic Plasticity

Facilitation and depression at synapses can be regulated by the ultra-structure of the synapse. We used the MCell program to perform realistic 3D Monte Carlo simulations of the molecular interactions that regulate transmitter release in a model CA3-CA1 hippocampal synapse. The relatively simple geometry of a hippocampal synapse compared to Calyx of Held allows a quantitative analysis of activity-dependent local calcium profiles at the active zone. Experimentally measurable synaptic variables such as the release probability and the global calcium response were used by the model to predict the structural parameters of the synapse. Tight spatial coupling between voltage gated calcium channels (VGCCs) and the neurotransmitter release complex promoted fast and temporally precise signalling at synapses. This coupling, however, limited the range of facilitation. Since more VGCCs were necessary to maintain release probability for longer coupling distances (up to a few hundred nanometers) it produced an augmented ‘global’ calcium response in the bouton. The resulting elevated residual calcium could open intracellular calcium stores, cause calcium buffers to saturate and trigger an overall increase in paired pulse ratio. These results were robust to the choice of model parameters and remain valid for a wide variety of neurons. In addition we simulated calcium florescence signals that can be directly compared to measurements with calcium dyes. This model may be extended to explore the molecular mechanisms involved in short-term synaptic plasticity observed in behavioural experiments.

Calcium as a versatile plant signal transducer under soil water stress

The complexity of calcium profiles observed in plant cells has led to the realization that specific patterns of calcium propagation (now termed calcium signatures) encode specific information and relay it to downstream elements (effectors) for translation into corresponding cellular responses in higher plants. The concept of calcium signatures is now well established and the tight control of the temporal and spatial characteristics of cytosolic calcium alterations is considered to be responsible for the specificity of various cellular responses, in particular to environment-induced stresses. To date, three major classes of plant calcium sensors responsible for drought-stress signal transduction during soil water deficit have been identified. Valuable pieces of the calcium signal-specificity puzzle are being put together and are illustrated here for the calcium-mediated signal-transduction cascades that operate in the responses of higher plants to soil environmental deficits.

Reversal-free Ca II H profiles: a challenge for solar chromosphere modeling in quiet inter-network

Aims. We study chromospheric emission to understand the temperature stratification in the solar chromosphere. Methods. We observed the intensity profile of the Ca II H line in a quiet Sun region close to the disk center at the German Vacuum Tower Telescope. We analyze over 10 5 line profiles from inter-network regions. For comparison with the observed profiles, we synthesize spectra for a variety of model atmospheres with a non local thermodynamic equilibrium (NLTE) radiative transfer code. Results. A fraction of about 25% of the observed Ca II H line profiles do not show a measurable emission peak in H 2v and H 2r wavelength bands (reversal-free). All of the chosen model atmospheres with a temperature rise fail to reproduce such profiles. On the other hand, the synthetic calcium profile of a model atmosphere that has a monotonic decline of the temperature with height shows a reversal-free profile that has much lower intensities than any observed line profile. Conclusions. The observed reversal-free profiles indicate the existence of cool patches in the interior of chromospheric network cells, at least for short time intervals. Our finding is not only in conflict with a full-time hot chromosphere, but also with a very cool chromosphere as found in some dynamic simulations.

Active Dendritic Conductances Dynamically Regulate GABA Release from Thalamic Interneurons

Inhibitory interneurons in the dorsal lateral geniculate nucleus (dLGN) process visual information by precisely controlling spike timing and by refining the receptive fields of thalamocortical (TC) neurons. Previous studies indicate that dLGN interneurons inhibit TC neurons by releasing GABA from both axons and dendrites. However, the mechanisms controlling GABA release are poorly understood. Here, using simultaneous whole-cell recordings from interneurons and TC neurons and two-photon calcium imaging, we find that synchronous activation of multiple retinal ganglion cells (RGCs) triggers sodium spikes that propagate throughout interneuron axons and dendrites, and calcium spikes that invade dendrites but not axons. These distinct modes of interneuron firing can trigger both a rapid and a sustained component of inhibition onto TC neurons. Our studies suggest that active conductances make LGN interneurons flexible circuit-elements that can shift their spatial and temporal properties of GABA release in response to coincident activation of functionally related subsets of RGCs.

Th17 Cells Exhibit a Distinct Calcium Profile from Th1 and Th2 Cells and Have Th1-Like Motility and NF-AT Nuclear Localization

Helper T cell subsets have evolved to respond to different pathogens, and upon activation secrete distinct sets of cytokines. The discovery and identification of Th17 cells, which develop via a unique lineage from Th1 and Th2 cells, have provided new insights into aspects of immune regulation and host defense that were previously unclear. A key early signaling event upon Ag recognition is elevation of intracellular free Ca(2+), and cytokine expression can be differentially induced depending on the duration, amplitude, and pattern of Ca(2+) signaling. Th1 and Th2 cells can be distinguished by their Ca(2+) profiles, and we provide in this study the first report regarding Ca(2+) signaling in Th17 cells. Th17 cells have a distinct Ca(2+) signaling profile from Th1 and Th2 cells with intermediate sustained Ca(2+) levels and increased oscillations compared with Th2 cells. Elevated intracellular Ca(2+) has been shown to inhibit T cell motility, and we observed that Th17 cells, like Th1 cells, are less motile than Th2 cells. Analysis of NF-AT nuclear localization revealed that Th1 and Th17 cells have significantly higher levels at later time points compared with Th2 cells. Thus, these findings show that Th17 cells, in addition to their distinct cytokine response from Th1 and Th2 cells, display unique patterns of intracellular Ca(2+) signaling and Th1-like motility behavior and nuclear localization of NF-AT.

Lactose intolerance in prostate cancer patients: Incidence and associated factors

Objective. Osteoporosis is common in prostate cancer (CaP) patients both before and after institution of androgen deprivation therapy and is associated with significant morbidity. Lactose intolerance (LI) can affect bone mass but has not been studied in this group of patients. The objective of this study was to compare the incidence of LI in CaP patients with that in the general population and to identify factors affecting lactose intolerance in CaP patients. Material and methods. Fifty-five men with CaP planned for bilateral orchidectomy were enrolled in the study and their baseline characteristics including age, weight, height, body mass index (BMI), prostate-specific antigen, serum calcium profile, lactose tolerance status, physical activity, alcohol intake and smoking, bone mineral density and calcium intake were registered. The data on lactose tolerance in these patients were compared with those of 81 age-matched controls (data taken from the available database). Results. The incidence of LI in CaP patients was significantly less than that in the control group (36.2% and 58.3%, respectively, p=0.027). A significantly greater number of CaP patients in the lactose-tolerant group had a calcium intake of >1500 mg/day (p=0.03) and that of milk >500 ml/day (p=0.05) than those in the intolerant group. Age >70 years, BMI <25 kg/m2, height >163 cm, lower physical activity and co-abuse of alcohol and smoking significantly correlated with the presence of LI (p≤0.05). Patients with serum calcium <9 mg/dl had higher fasting breath H2 levels and a higher proportion had a BMI >25 kg/m2 and weight >65 kg. Conclusions. The incidence of LI in CaP patients is less than that in the general population despite a higher incidence of osteoporosis, indicating a complex etiology of CaP-related osteoporosis. Certain physical characteristics and personal habits are important in determining lactose-tolerant status.

Experimental investigation and numerical modeling of chloride penetration and calcium dissolution in saturated concrete

Chloride penetration and calcium dissolution have been investigated for a saturated concrete after exposure to a 0.5 mol/L NaCl solution for a period of up to 3150 days. Simultaneous ion transport model (SiTraM) that allows the transport of chloride and calcium ions to be simultaneously simulated in a hydrated cement system has been used to verify the experimental results. Self-compacting concrete (SCC) with a water to cement ratio of 0.3 resulted in a limited chloride penetration depth while the calcium dissolution was also reduced within the near surface zone. Increased unit water content for normal concrete resulted in higher chloride penetration depth and larger dissolution front of Ca(OH) 2 regardless of having the same water to cement ratio. It was revealed that the SiTraM can predict the profiles of chloride and calcium for self-compacting concrete. It was also found that the primary factor to control chloride penetration front and the dissolution front of Ca(OH) 2 was the pore structure characteristic of concrete.

A Kinetic Model for Calcium Dynamics in RAW 264.7 Cells: 1. Mechanisms, Parameters, and Subpopulational Variability

Calcium (Ca 2+) is an important second messenger and has been the subject of numerous experimental measurements and mechanistic studies in intracellular signaling. Calcium profile can also serve as a useful cellular phenotype. Kinetic models of calcium dynamics provide quantitative insights into the calcium signaling networks. We report here the development of a complex kinetic model for calcium dynamics in RAW 264.7 cells stimulated by the C5a ligand. The model is developed using the vast number of measurements of in vivo calcium dynamics carried out in the Alliance for Cellular Signaling (AfCS) Laboratories. Ligand binding, phospholipase C- β (PLC- β) activation, inositol 1,4,5-trisphosphate (IP 3) receptor (IP 3R) dynamics, and calcium exchange with mitochondria and extracellular matrix have all been incorporated into the model. The experimental data include data from both native and knockdown cell lines. Subpopulational variability in measurements is addressed by allowing nonkinetic parameters to vary across datasets. The model predicts temporal response of Ca 2+ concentration for various doses of C5a under different initial conditions. The optimized parameters for IP 3R dynamics are in agreement with the legacy data. Further, the half-maximal effect concentration of C5a and the predicted dose response are comparable to those seen in AfCS measurements. Sensitivity analysis shows that the model is robust to parametric perturbations.

The Calponin Homology Domain of Vav1 Associates with Calmodulin and Is Prerequisite to T Cell Antigen Receptor-induced Calcium Release in Jurkat T Lymphocytes

Vav1 is a guanine nucleotide exchange factor that is expressed specifically in hematopoietic cells and plays important roles in T cell development and activation. Vav1 consists of multiple structural domains so as to facilitate both its guanine nucleotide exchange activity and scaffold function following T cell antigen receptor (TCR) engagement. Previous studies demonstrated that the calponin homology (CH) domain of Vav1 is required for TCR-stimulated calcium mobilization and thus downstream activation of nuclear factor of activated T cells. However, it remained obscure how Vav1 functions in regulating calcium flux. In an effort to explore molecules interacting with Vav1, we found that calmodulin bound to Vav1 in a calcium-dependent and TCR activation-independent manner. The binding site was mapped to the CH domain of Vav1. Reconstitution of vav1-null Jurkat T cells (J.Vav1) with CH-deleted Vav1 exhibited a severe deficiency in calcium release to the same extent as that of Jurkat cells treated with the calmodulin inhibitor or J.Vav1 cells. The defect persisted even when phospholipase-Cgamma1 was fully activated, indicating a prerequisite role of Vav1 CH domain in calcium signaling. The results suggest that Vav1 and calmodulin function cooperatively to potentiate TCR-induced calcium release. This study unveiled a mechanism by which the Vav1 CH domain is involved in calcium signaling and provides insight into our understanding of the role of Vav1 in T cell activation.

Cycling of calcite in hard water lakes of different trophic states

Based on oxygen (O2), pH, calcium (Ca2+), and carbonate (CO32‐) sediment pore‐water concentration profiles, we compare the benthic dissolution of autochthonous calcite in oligotrophic Lake Lucerne and eutrophic Lake Sempach. Despite their difference in trophic state, the two lakes have similar benthic O2 regimes because L. Sempach is artificially oxygenated. This peculiarity enabled the study of the direct effect of trophic state on benthic calcite dissolution. Although areal benthic O2 fluxes did not differ, O2 penetrated deeper into the sediment of the oligotrophic L. Lucerne, where most organic matter (OM, 96%) was degraded aerobically, whereas in L. Sempach, aerobic and anaerobic decomposition contributed about equal amounts to the biogenic carbon dioxide production. Release rates of bicarbonate from L. Sempach sediments exceeded those of L. Lucerne nearly twofold. The HCO3− : Ca2+ ratio of benthic fluxes was 3.7 in L. Lucerne compared to 10.3 in L. Sempach, suggesting that in L. Sempach most of the released HCO3− did not originate from calcite dissolution. Furthermore, benthic calcite dissolution in L. Lucerne exceeded that in L. Sempach by two‐fold, despite lower pH values in the pore water of L. Sempach. Differences in benthic microbial decomposition of OM and redissolution of calcite crystals are explained by the longer residence time of OM and calcite in the oxic sediment layer of the oligotrophic lake and the larger weight‐specific surface area of its smaller autochthonous calcite crystals. We suggest that trophic state and O2 supply to the sediment are key parameters controlling the cycling of calcite and organic carbon in lakes.

Tolerability of atorvastatin in a population aged ≥65 years: A retrospective pooled analysis of results from fifty randomized clinical trials

Objective: The aim of this study was to compare the safety profile of atorvastatin calcium at 4 doses with that of placebo in elderly patients (age, ≥65 years). Methods: A single pooled database (Pfizer Atorvastatin Clinical Program Database) of 50 published and unpublished completed clinical trials was analyzed retrospectively. Tolerability data from male and female study participants aged ≥65 years at the time of study enrollment were extracted from this database and grouped based on treatment: atorvastatin 10, 20, 40, or 80 mg/d, or placebo. Analyses included comparisons of treatment-related and serious adverse events (AEs) of the musculoskeletal, hepatic, and renal systems. Descriptive statistics were employed. No inferential statistical analyses were performed. Results: A total of 5924 patients were included in the pooled analysis (range of mean age, 71–74 years; white race, 5437 [91.8%]; female sex, 2506 [42.3%]; treatment with atorvastatin 10 mg/d, n = 2042; atorvastatin 20 mg/d, n = 667; atorvastatin 40 mg/d, n = 522; atorvastatin 80 mg/d, n = 1698; and placebo, n = 995). The overall AE profiles appeared similar with all atorvastatin doses and placebo. The proportions of patients experiencing at least 1 treatment-related AE were 16.1%, 10.2%, 11.3%, 15.0%, and 15.3% in the atorvastatin 10−, 20−, 40−, and 80-mg/d, and placebo groups, respectively. The rates of discontinuation due to treatment-associated AEs appeared comparable between all doses of atorvastatin and placebo (2.1% vs 1.7%). Serious AEs were rare (≤1.0%) and seldom led to withdrawal. The prevalence of treatment-associated myalgia was low in all treatment groups (≤1.8%). None of the patients experienced persistent creatine kinase elevations >10-fold the upper limit of normal (× ULN), and no cases of myopathy or rhabdomyolysis were reported. The rates of patients with persistent elevation >3 × ULN) of hepatic aminotransferases were 0.1%, 0%, 0.2%, 0.5%, and 0.2% in the atorvastatin 10−, 20−, 40−, and 80-mg/d, and placebo groups, respectively. Although the prevalences of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) elevations appeared slightly higher in the 80-mg/d group (3.2% vs ≤0.9% in all other groups), specific musculoskeletal and hepatic AEs were rare (≤3.0%). Conclusions: This pooled analysis of 50 published and unpublished studies in elderly patients found that the overall prevalences of AEs did not appear to increase with dose and appeared comparable to that observed with placebo. Although the prevalences of ALT/AST elevations appeared slightly higher in the 80-mg/d group (3.2% vs ≤0.9% in all other groups), specific musculoskeletal and hepatic AEs were rare (≤3.0%). The rates of discontinuation appeared comparable between all 4 doses of atorvastatin and placebo. The results of this analysis support the favorable safety profile of atorvastatin across the full dose range in patients aged ≥65 years.

Risk Factors for Development of Posttransplant Diabetes Mellitus in Renal Transplant Recipients

Diabetes mellitus appearing after kidney transplantation—posttransplant diabetes mellitus (PTDM)—is a common complication associated with poor graft and patient survival. The purpose of the current study was to determine the risk factors for developing PTDM in 204 renal transplant recipients who had been followed for at least 30 months. Posttransplant diabetes mellitus was diagnosed according to the American Diabetic Association/WHO criteria, or a requirement for insulin, an oral hypoglycemic agent, or both. Analyses of possible risk factors for PTDM included demographic features, dialysis and posttransplantation duration, smoking, body mass index, medications, co-morbid diseases, HLA mismatches, as well as laboratory metrics of serum creatinine, albumin, calcium, phosphorus, C-reactive protein, parathyroid hormone, and lipid profiles. Twenty-six patients displayed PTDM. Univariate analysis showed that older age, greater body mass index, presence of hepatitis C virus (HCV) infection, and smoking at the time of renal transplantation were associated with PTDM development. In a multivariate analysis, HCV infection, smoking, and patient age at the time of transplantation were independent risk factors for PTDM. In conclusion, the presence of HCV infection or a smoking habit in addition to older age at the time of transplantation were the main predictors for developing PTDM. Patients should be closely followed regarding their smoking habit and weight gain as modifiable risk factors for PTDM.

Densidade óssea de frangos de corte alimentados com diferentes níveis de aminoácidos e cálcio durante a fase final de criação

Two experiments were carried out aiming at evaluating the effects of different dietary amino acid and calcium profiles on bone characteristics of two chicken strains (Avian Farms and Cobb) from 42 to 49 days of age. At the end of each experiment, two chickens of each replication were sacrificed and their tibiae were collected for analysis of bone characteristics: bone measurements (weight, length and thickness of the compact and spongy layers) and bone density (bone density). A total of 540 birds were used in each experiment, divided into fully randomized blocks with a 3 x 2 factorial scheme, that is, three amino acid profiles (methionine, lysine and threonine – 100, 125 and 150% of NRC recommendations, 1994) and two calcium levels (75 and 100% of NRC recommendations, 1994), with 30 birds per replication. There were not interactions between the two factors. The amino acid or calcium levels did not affect bone density and tibia variables in both strains.

The 14-year Performance of a Compacted Clay Liner used as Part of a Composite Liner System for a Leachate Lagoon

The migration of contaminants through a 2.9 m thick compacted clay liner (CCL) for a landfill leachate lagoon is examined 14 years after construction. The clay liner formed the lower portion of the composite liner system but the geomembrane (GM) was found to have defects that had allowed leachate to migrate between the GM and CCL. Chloride, sodium, potassium, calcium and magnesium pore water profiles through the CCL are examined. It is shown that chloride migrated approximately 1.7 m into the CCL during the 14 years of the lagoon operation, sodium approximately 1.2 m, and potassium 0.7 m. Diffusion and sorption data from laboratory diffusion testing are utilized in combination with a finite layer contaminant transport model to predict field contaminant migration profiles through the composite liner system and to establish the time of ‘failure’ of the geomembrane at sometime between 0 and 6 years after installation. Relatively high sorptive uptake of potassium by the CCL soil is observed from batch testing and diffusion testing with field data suggesting an even larger amount of sorption. It is hypothesized that organic sludge matter at the base of the lagoon is responsible for potassium uptake from the leachate. This field case highlights the importance of the compacted clay liner as part of the composite liner system in acting as a diffusion barrier during the lifetime of the lagoon as well as using relatively non-conservative contaminants such as chloride and sodium to estimate geomembrane ‘failure’ times

FETUIN-A AND OTHER RISK FACTORS IN HD PATIENTS WITH CARDIAC CALCIFICATIONS

Introduction: Cardiac calcifications are a frequent finding in HD. Fetuin-A and MGLA protein are able to keep in solution calcium phosphate. Aim: To evaluate the risk factors of cardiac calcifications and the role of fetuin-A levels in HD pts. Methods: 120 pts on HD, age 59.1±13.1 years, HD age 63.5±61.8 months, M/F 77/43, were submitted to evaluation of a cardiac calcification score with fast Multilayer Computerized Tomography. Calcium phosphate metabolism, lipid and inflammatory parameters, among which PINI, Fetuin-A and PCR and Hb were measured. Results: More than 80% pts had frankly pathologic Score values. Fetuin-A was much lower than normal 0.328±0.11 g/L; NV 0,519±0.15 g/L. Multiregression analysis showed selected age p<0.0001, serum Chol<0.0001, Ca <0.003, Triglycerides <0.033 and HDL <0.059 as variables predictive of log calcium Score, while Fetuin-A was excluded. In addition the coronary calcium Score was correlated to calcitriol IV administration p<0.001. Prealbumin was correlated to Fetuin-A in the MRA, while CPR and PINI were among the excluded variables. In addition Fetuin-A was predictive of Hb concentration. Conclusion: Low serum Fetuin-A levels not seems induce cardiac calcifications, which were mainly linked to age, serum calcium and lipid profile. Fetuin-A seem to be linked to inflammatory and nutritional parameters known to affect Hb concentration and atherogenesis.

The role of shoreland development and commercial cranberry farming in a lake in Wisconsin, USA

Musky Bay in Lac Courte Oreilles, Wisconsin, USA, is currently eutrophic. This large, shallow bay of an oligotrophic lake possesses the densest aquatic plant growth and a floating algal mat. Paleoecological reconstructions encompassing the last 130 years, were based on multiproxy analyses of sediment cores from three coring sites, two within the bay and one in the lake itself. These data were compared to historical records of the construction and expansion of two commercial cranberry bogs and shoreline residential homes to identify temporal and causal relations of eutrophication. The proxies investigated included: minor and trace elements; biogenic silica; and the diatom community. Post-depositional diagenesis of organic carbon, nitrogen, and phosphorus in the upper 30 cm of the core obscured records of historical ambient nutrient concentrations in the bay obviating their usefulness for this purpose. In contrast, calcium, magnesium, and potassium concentration profiles appeared to reflect runoff of soil amendments applied to the cranberry bogs and aerial fertilizer spraying over the eastern bog adjacent to Musky Bay. The increase in aluminum content since about 1930 coincided with the historical trend in shoreland development and construction of the original commercial cranberry farm. The biogenic silica profile recorded a steady increase of nutrients to Musky Bay over the last several decades. Stratigraphic changes in the diatom community indicated that nutrient input began to increase in the 1940s and accelerated in the mid-1990s with the onset of a noxious floating algal mat. The diatom community indicates the bay has possessed a significant macrophyte community for at least the last 200 years, but increased nutrient input was manifested by a change in the composition, and an increase in the density of the epiphytic diatom community. Cranberry farming appeared to be the major source of nutrients because the diatom community changes occurred prior to the significant increase in residential housing.

Continuous Ambulatory Peritoneal Dialysis Patients Show High Prevalence of Carotid Artery Calcification which is Associated with a Higher Left Ventricular Mass Index

This study examined intima-media thickness and arterial plaque occurrence in the carotid and brachial arteries in continuous ambulatory peritoneal dialysis (CAPD) patients. The study compared 25 CAPD patients with 25 normotensive age- and sex-matched controls. Intima-media thickness and presence of plaque in carotid and brachial artery were measured three times using high-resolution B-mode echocardiography. Left ventricular mass was calculated using the Penn Convection equation. Blood samples were obtained to assess levels of phosphorus, total calcium, serum albumin, C-reactive protein, and lipid profiles. Compared to the control group, CAPD patients had greater mean carotid and brachial intima-media thickness, and a higher proportion of subjects with calcified plaques. The left ventricular mass index was higher in CAPD patients with carotid artery calcified plaques compared to CAPD patients without carotid artery calcified plaques. CAPD patients with such plaque were significantly associated with diabetes mellitus, higher C-reactive protein levels and a lower 2-yr survival rate. The present study showed an high prevalence of carotid calcification in CAPD patients and those with such calcification had a greater incidence of diabetes mellitus, higher C-reactive protein levels and left ventricular mass index, and a lower survival rate.

The Kinetic Profile of Intracellular Calcium Predicts Long-Term Potentiation and Long-Term Depression

Efficiency of synaptic transmission within the neocortex is regulated throughout life by experience and activity. Periods of correlated or uncorrelated presynaptic and postsynaptic activity lead to enduring changes in synaptic efficiency [long-term potentiation (LTP) and long-term depression (LTD), respectively]. The initial plasticity triggering event is thought to be a precipitous rise in postsynaptic intracellular calcium, with higher levels inducing LTP and more moderate levels inducing LTD. We used a pairing protocol in visual cortical brain slices from young guinea pigs with whole-cell recording and calcium imaging to compare the kinetic profiles of calcium signals generated in response to individual pairings along with the cumulative calcium wave and plasticity outcome. The identical pairing protocol applied to layer 2/3 pyramidal neurons results in different plasticity outcomes between cells. These differences are not attributable to variations in the conditioning protocol, cellular properties, inter-animal variability, animal age, differences in spike timing between the synaptic response and spikes, washout of plasticity factors, recruitment of inhibition, or activation of different afferents. The different plasticity outcomes are reliably predicted by individual intracellular calcium transients in the dendrites after the first few pairings. In addition to the differences in the individual calcium transients, the cumulative calcium wave that spreads to the soma also has a different profile for cells that undergo LTP versus LTD. We conclude that there are biological differences between like-type cells in the dendritic calcium signals generated by coincident synaptic input and spiking that determine the sign of the plasticity response after brief associations.