The neurotransmitter dopamine inhibits angiogenesis induced by vascular permeability factor/vascular endothelial growth factor

Angiogenesis has an essential role in many important pathological and physiological settings. It has been shown that vascular permeability factor/vascular endothelial growth factor (VPF/VEGF), a potent cytokine expressed by most malignant tumors, has critical roles in vasculogenesis and both physiological and pathological angiogenesis. We report here that at non-toxic levels, the neurotransmitter dopamine strongly and selectively inhibited the vascular permeabilizing and angiogenic activities of VPF/VEGF. Dopamine acted through D2 dopamine receptors to induce endocytosis of VEGF receptor 2, which is critical for promoting angiogenesis, thereby preventing VPF/VEGF binding, receptor phosphorylation and subsequent signaling steps. The action of dopamine was specific for VPF/VEGF and did not affect other mediators of microvascular permeability or endothelial-cell proliferation or migration. These results reveal a new link between the nervous system and angiogenesis and indicate that dopamine and other D2 receptors, already in clinical use for other purposes, might have value in anti-angiogenesis therapy.

A 3-D FEM analysis of single and multiple screw-root dental implant fixed in a mandible

Replacement of single tooth using a threaded titanium screw root coated with hydroxyapatite (HA) for faster bone apposition to implant site is common. Uncoated pure titanium is also used for osseointegration. Usually bone fixation of implant takes four to six months in either case. Quite often, a good number of teeth in a mandible or maxilla are replaced. Usually it is often said that bones appear to be well designed from the point of view of structural engineering. The "maximum-minimum law" claimed by Roux is a rational concept that states that bone provides maximum strength with a minimum of construction material. According to this proposition, stress distribution in bone will be almost uniform under a set of loading conditions. This was found to be true in the case of normal human mandibular bone as examined by some Japanese scientists. The present authors are interested in examining the stress distribution during multiple single tooth replacements using 3D-FEM technique to ascertain how the stress pattern changes with such implantation of three screws in a row in the human mandible, as we are in the process of clinical trial of hydroxyapatite coated and uncoated titanium implant. This will be of considerable interest to the dental surgeons, who prompted us to address this problem. Our results depicted the mean values of various stress in cortical and cancellous bone while applying the maximum masticatory load of 50 N in each teeth. The generated stress level is within the safe range of stress for bones. However, such screws cannot be applied to osteoporotic or other diseased mandible where bone strength may be quite low.

Stress analysis of an artificial temporal mandibular joint

To design a temporal mandibular joint (TMJ), the designer should pay attention to the range of movement in the joint, the strength of the joint, and the size of the implant should conform, so that it does not hamper facial configuration. As a number of designs are available, in this study we have considered one of the most common and widely used implants for analysis. The main objective of this study is to examine the stress-strain behavior at the implant and what is happening at the implant bone interface. We have also examined whether implant material can be replaced by UHMWPE (ultra high molecular weight polyethylene) instead of titanium or Co-Cr-Mo alloy. Whether the change of positions of the screw used for fixation has any effect or not, we have modeled it considering actual shape and size, then divided it into number finite elements by using a FEM package. An appropriate surgical construct was modeled and loaded and studied for different parameters. We have shown that the metallic prostheses are good from a stress-strain point of view and UHMWPE cannot be used as such.

Hippocampal neurons exhibit both persistent Ca2+ influx and impairment of Ca2+ sequestration/extrusion mechanisms following excitotoxic glutamate exposure

Exposure of neurons to glutamate is an essential element of neuronal function, producing transient elevations in free intracellular calcium ([Ca2+]i) that are required for normal physiological processes. However, prolonged elevations in [Ca2+]i have been observed following glutamate excitotoxicity and have been implicated in the pathophysiology of delayed neuronal cell death. In the current study, we utilized indo-1 and fura-2ff Ca2+ imaging techniques to determine if glutamate-induced prolonged elevations in [Ca2+]i were due to persistent influx of extracellular Ca2+ or from impairment of neuronal Ca2+ extrusion/sequestration mechanisms. By experimentally removing Ca2+ from the extracellular solution following glutamate exposure, influx of Ca2+ into the neurons was severely attenuated. We observed that brief glutamate exposures (<5 min, 50 microM glutamate) resulted in a Ca2+ influx that continued after the removal of glutamate. The Ca2+ influx was reversible, and the cell was able to effectively restore [Ca2+]i to resting levels. Longer, excitotoxic glutamate exposures (> or = 5 min) generated a Ca2+ influx that continued for the duration of the recording period (>1 h). This persistent Ca2+ influx was not primarily mediated through traditionally recognized Ca2+ channels such as glutamate receptor-operated channels or voltage-gated Ca2+ channels. In addition to the persistent Ca2+ influx, longer glutamate exposures also produced a lasting disruption of Ca2+ extrusion/sequestration mechanisms, impairing the ability of the neuron to restore resting [Ca2+]i. These data suggest that glutamate-induced protracted [Ca2+]i elevations result from at least two independent, simultaneously occurring alterations in neuronal Ca2+ physiology, including a persistent Ca2+ influx and damage to Ca2+ regulation mechanisms.

Studies on stibanate resistant Leishmania donovani isolates of Indian origin

Studies with 26 clones of L. donovani promastigotes derived from three different Indian isolates indicated that wild type parasites are mixture of stibanate sensitive and resistant cells. Both forms of the parasite were resistant to the drug. Infection with resistant parasites appears to be the primary reason of high rate of pentavalent antimony unresponsiveness among Indian kala-azar patients. It was observed that the resistant parasites originated as a result of irregular and often incomplete treatment of kala-azar patients with pentavalent antimonials.

Role of protein kinase Czeta in Ras-mediated transcriptional activation of vascular permeability factor/vascular endothelial growth factor expression

Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF), a multifunctional cytokine, is regulated by different factors including degree of cell differentiation, hypoxia, and certain oncogenes namely, ras and src. The up-regulation of VPF/VEGF expression by Ras has been found to be through both transcription and mRNA stability. The present study investigates a novel pathway whereby Ras promotes the transcription of VPF/VEGF by activating protein kinase Czeta (PKCzeta). The Ras-mediated overexpression of VPF/VEGF was also found to be inhibited by using the antisense or the dominant-negative mutant of PKCzeta. In co-transfection assays, by overexpressing oncogenic Ha-Ras (12 V) and PKCzeta, there was an additive effect up to 4-fold in activation of Sp1-mediated VPF/VEGF transcription. It has been shown through electrophoretic mobility shift assay that Ras promoted the PKCzeta-induced binding of Sp1 to the VPF/VEGF promoter. In the presence of PDK-1, a major activating kinase for PKC, the Ras-mediated activation of VPF/VEGF promoter through PKCzeta was further increased, suggesting that PKCzeta can serve as an effector for both Ras and PDK-1. In other experiments, with the use of a dominant-negative mutant of phosphatidylinositol 3-kinase, the activation of VPF/VEGF promoter through Ras, PDK-1, and PKCzeta was completely repressed, indicating phosphatidylinositol 3-kinase as an important component of this pathway. Taken together, these data elucidate the signaling mechanism of Ras-mediated VPF/VEGF transcriptional activation through PKCzeta and also provide insight into PKCzeta and Sp1-dependent transcriptional regulation of VPF/VEGF.

MitoTracker labeling in primary neuronal and astrocytic cultures: influence of mitochondrial membrane potential and oxidants

MitoTracker dyes are fluorescent mitochondrial markers that covalently bind free sulfhydryls. The impact of alterations in mitochondrial membrane potential (Delta Psi(m)) and oxidant stress on MitoTracker staining in mitochondria in cultured neurons and astrocytes has been investigated. p-(Trifluoromethoxy) phenyl-hydrazone (FCCP) significantly decreased MitoTracker loading, except with MitoTracker Green in neurons and MitoTracker Red in astrocytes. Treatment with FCCP after loading increased fluorescence intensity and caused a relocalization of the dyes. The magnitude of these effects was contingent on which MitoTracker, cell type and dye concentration were used. H(2)O(2) pretreatment led to a consistent increase in neuronal MitoTracker Orange and Red and astrocytic MitoTracker Green and Orange fluorescence intensity. H(2)O(2) exposure following loading increased MitoTracker Red fluorescence in astrocytes. In rat brain mitochondria, high concentrations of MitoTracker dyes uncoupled respiration in state 4 and inhibited maximal respiration. Thus, loading and mitochondrial localization of the MitoTracker dyes can be influenced by loss of Delta Psi(m) and increased oxidant burden. These dyes can also directly inhibit respiration. Care must be taken in interpreting data collected using MitoTrackers dyes as these dyes have several potential limitations. Although MitoTrackers may have some value in identifying the location of mitochondria within cultured neurons and astrocytes, their sensitivity to Delta Psi(m) and oxidation negates their use as markers of mitochondrial dynamics in healthy cultures.

Ligation of CD40 induces the expression of vascular endothelial growth factor by endothelial cells and monocytes and promotes angiogenesis in vivo

This study addresses a mechanism by which lymphocytes may promote vascular endothelial growth factor (VEGF) expression and angiogenesis in immune inflammation. Resting human umbilical endothelial cells (HUVECs) were found to express low levels of VEGF messenger RNA (mRNA) by reverse transcription polymerase chain reaction and ribonuclease protection assay with little or no change in expression following activation by cytokines, including tumor necrosis factor-alpha, interleukin (IL)-1, interferon gamma, or IL-4. In contrast, treatment of HUVECs and monocytes with soluble CD40 ligand (sCD40L) resulted in a marked dose-dependent induction of VEGF mRNA (approximately 4-fold), which peaked between 1 and 5 hours post-stimulation. Transient transfection of HUVECs was performed with a luciferase reporter construct under the control of the human VEGF promoter. Treatment of transfected HUVECs with sCD40L was found to enhance luciferase activity (approximately 4-fold) compared with controls, similar to the relative fold induction in mRNA expression in parallel cultures. Thus, CD40-dependent VEGF expression was a result of transcriptional control mechanisms. Treatment of HUVECs with sCD40L was also found to function in vitro to promote growth and proliferation in a VEGF-dependent manner, and CD40-dependent HUVEC growth was comparable to that found following treatment with recombinant human VEGF. Furthermore, subcutaneous injection of sCD40L in severe combined immunodeficient and nude mice induced VEGF expression and marked angiogenesis in vivo. Taken together, these findings are consistent with a function for CD40L-CD40 interactions in VEGF-induced angiogenesis and define a mechanistic link between the immune response and angiogenesis. (Blood. 2000;96:3801-3808)

Phosphorylation of the anti-HIV compound (S,S)-isodideoxyadenosine by human recombinant deoxycytidine kinase

(S,S)-Isodideoxyadenosine [(S,S)-isoddA] is an anti-HIV active compound discovered in our laboratory. However, its cellular mechanism of action, particularly the critical first stage of phosphorylation, is not understood. IsoddA is not phosphorylated by adenosine kinase. Also, because it is not a substrate for adenosine deaminase, it would not be activated by the pathway taken by ddA, i. e. via 5'-nucleotidase phosphorylation of ddI and conversion of ddIMP to ddAMP. However, we have discovered that human recombinant 2'-deoxycytidine kinase (dCK) phosphorylates (S,S)-isoddA. The enzyme kinetic data revealed that the extent of monophosphorylation of this L-related nucleoside was comparable to that found with ddA. (S,S)-IsoddATP is among the most potent inhibitors of HIV reverse transcriptase known, which suggests that the observed low efficiency of phosphorylation of this compound by dCK is a key factor that limits the capacity of human lymphocytes to make (S,S)-isoddA an exceptionally active anti-HIV agent.

Synthesis and accumulation of poly(3-hydroxybutyric acid) by Rhizobium sp

Forty-two Rhizobium strains obtained from different culture collections were evaluated quantitatively for poly(3-hydroxy-butyric acid) [PHB] production in shake flask culture. The majority of the strains produced the maximum amount of PHB during the late exponential or stationary phase of growth. Synthesis and accumulation of PHB in different species of Rhizobium were found to vary between 1-38% of their dry biomass. Growth and PHB production by the Rhizobium strain TAL-640 were greatly influenced by the C-source and D-mannitol was fundamental to both processes. The identity and purity of PHB isolated from TAL-640 have also been confirmed by UV-, IR- and 1H-NMR spectroscopic analyses.

Preliminary studies on the anti-inflammatory and analgesic activity of the methanolic fraction of the root extract of Tragia involucrata Linn

Tragia involucrata has been widely used in the traditional medicinal system for the treatment of a variety of diseases. The effect of methanolic extract of T. involucrata was studied in different experimental animal models and it was revealed that the extract possesses significant analgesic and anti-inflammatory activity.

Induction of spontaneous recurrent epileptiform discharges causes long-term changes in intracellular calcium homeostatic mechanisms

Calcium and calcium-dependent systems have been long implicated in the induction of epilepsy. We have previously observed that intracellular calcium ([Ca2+]i) levels remain elevated in cells undergoing epileptogenesis in the hippocampal neuronal culture (HNC) model. In this study, we employed the hippocampal neuronal culture (HNC) model of in vitro 'epilepsy' which produces spontaneous recurrent epileptiform discharges (SREDs) for the life of the neurons in culture to investigate alterations in [Ca2+]i homeostatic mechanisms that may be associated with the 'epileptic' phenotype. [Ca2+]i imaging fluorescence microscopy was performed on control and 'epileptic' neurons with two different fluorescent dyes ranging from high to low affinities for [Ca2+]i. We measured baseline [Ca2+]i levels and the ability to restore resting [Ca2+]i levels after a brief 2-min exposure to the excitatory amino acid glutamate in control neurons and neurons with SREDs. Neurons manifesting SREDs had statistically significantly higher baseline [Ca2+]i levels that persisted for the life of the culture. In addition, the 'epileptic' phenotype was associated with an inability to rapidly restore [Ca2+]i levels to baseline following a glutamate induced [Ca2+]i load. The use of the low affinity dye Fura-FF demonstrated that the difference in restoring baseline [Ca2+]i levels was not due to saturation of the high affinity dye Indo-1, which was utilized for evaluating the [Ca2+]i kinetics at lower [Ca2+]i levels. Peak [Ca2+]i levels in response to glutamate were the same in both 'epileptic' and control neurons. While [Ca2+]i levels recovered in approximately 30 min in control cells, it took more than 90 min to reach baseline levels in cells manifesting SREDs. Alterations of [Ca2+]i homeostatic mechanisms observed with the 'epileptic' phenotype were shown to be independent of the presence of continuous SREDs and persisted for the life of the neurons in culture. Epileptogenesis was shown not to affect the degree or duration of glutamate induced neuronal depolarization in comparing control and 'epileptic' neurons. The results indicate that epileptogenesis in this in vitro model produced long-lasting alterations in [Ca2+]i regulation that may underlie the 'epileptic' phenotype and contribute to the persistent neuroplasticity changes associated with epilepsy.

Retinoic acid selectively inhibits the vascular permeabilizing effect of VPF/VEGF, an early step in the angiogenic cascade

All-trans-retinoic acid (RA) and other retinoids modulate cell growth and differentiation, generally favoring terminal cell differentiation and inhibiting carcinogenesis. Retinoids are also reported to inhibit angiogenesis and endothelial cell migration, actions that are also anti-carcinogenic. Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) is a multifunctional cytokine secreted by many tumors. It renders microvessels hyperpermeable to plasma and stimulates endothelial cell migration and division. To investigate further the mechanisms by which RA inhibits angiogenesis, we evaluated the effects of RA on VPF/VEGF-induced angiogenesis and microvascular permeability. RA selectively inhibited the angiogenic response induced by VPF/VEGF, but not that induced by fibroblast growth factor-2 (FGF-2), in the CAM assay. RA and two of its isomers also inhibited the vascular permeabilizing effect of VPF/VEGF but not that induced by histamine. The vascular permeabilization induced by VPF/VEGF and blocked by RA takes place within 1-15 min, too short a time frame for RA to act by modulating transcription through classic retinoid receptors. RA also inhibited VPF/VEGF-induced phosphorylation of PLC-gamma and synthesis of cGMP but actually increased VPF/VEGF binding to cultured endothelial cells. Taken together, these findings indicate that RA selectively blocks VPF/VEGF-induced microvascular permeability and angiogenesis and also identify VPF/VEGF as a major target of RA action. The selectivity of RA's action suggests that other, RA-independent pathways must exist for the angiogenesis induced by FGF-2 and the vascular permeabilizing effect of histamine.

Role of Nramp1 deletion in Chlamydia infection in mice

Elicited macrophages from 129sv mice with a functional deletion of the natural-resistance-associated macrophage protein 1 gene (Nramp1) were shown to be as susceptible as wild-type mice to infection with the Chlamydia trachomatis mouse pneumonitis and L3 serovars and to Chlamydia pneumoniae. Furthermore, the two groups of mice were shown to be similarly susceptible to an intranasal infection with these microorganisms. In conclusion, the Nramp1 gene does not appear to play a major role in the regulation of the susceptibility of mice to a chlamydial infection.

Inhibition of insulin-like growth factor-I-mediated cell signaling by the von Hippel-Lindau gene product in renal cancer

Insulin-like growth factor-I (IGF-I)-mediated signaling is thought to be involved in the regulation of multiple cellular functions in different tumors including renal cell carcinoma (RCC). Blocking IGF-I signaling by any of the several strategies abolishes or delays the progression of a variety of tumors in animal models. Herein, we demonstrate that in RCC cell lines, IGF-I-mediated signaling is found to be inhibited in the presence of wild type von Hippel-Lindau (VHL) tumor suppresser gene. Moreover, molecular modeling and biochemical approaches have revealed that beta-domain of the VHL gene product by interacting directly with protein kinase Cdelta inhibits its association with IGF-IR for downstream signaling. We also demonstrated that RCC has IGF-I-mediated invasive activity where protein kinase Cdelta is an important downstream molecule, and this invasiveness can be blocked by wild type VHL. These experiments thus elucidate a novel tumor suppresser function of VHL with its unique kinase inhibitory domain.

Effect of dothiepin on gastric ulceration mediated by lipid derived eicosanoids

Dothiepin, a tricyclic antidepressant, significantly inhibited the development of gastric ulcers induced by alcohol, aspirin, indomethacin and Shay's pyloric ligation. Antisecretory studies in pyloric ligated rats revealed that the drug at a dose of 100 mg/kg significantly reduced total acidity, gastric output and protein content. In another set of experiments, dothiepin significantly reduced gastric output, total acidity and protein content in pyloric ligated rats which received 50% alcohol (v/v) 30 minutes after the administration of dothiepin.

Detection of LDL receptor by ligand blotting with chylomicron remnants labelled with colloidal gold

The LDL receptor plays a pivotal role in the clearance of pro-atherogenic lipoproteins, and LDL receptor deficiency may be the underlying cause of several primary and secondary dyslipidaemic conditions. Intervention strategies are often targeted to increase hepatic LDL receptor expression. It is difficult to quantitate hepatic LDL receptor activity and to monitor changes post-therapy. In order to avoid liver biopsy, human skin fibroblasts or circulating mononuclear cells have often been used as surrogate markers for the hepatic receptor. Fibroblasts, and particularly mononuclear cells, are relatively easy to isolate and can be stored for extensive lengths of time without significant loss of LDL receptor expression. Leucocytes or fibroblasts are normally probed with isotopically or gold-labelled LDL. However, the specific activity of the LDL conjugate is usually too low to enable accurate quantitation of differences, or changes, in LDL receptor expression. In this study, we describe an enhanced colloidal gold-labelling procedure for the detection of LDL receptor binding activity. The binding of colloidal gold-labelled chylomicron remnants to human hepatocytes (HepG2 cells) was compared with that of gold-conjugated LDL. Labelled remnants bound specifically to a cell surface protein with a molecular weight of approximately 130 kDa. Binding was blocked in the presence of unlabelled remnants, LDL, or antiserum specific to the LDL receptor. The binding of gold-labelled remnants was substantially greater than that of gold-labelled LDL. Compared with gold-labelled LDL, we found a much clearer demarcation of remnant binding with hepatocytes incubated in the presence or absence of sterols. Our observations suggest that, because of the greater affinity of the LDL receptor for lipoproteins containing apolipoprotein E, changes in LDL receptor expression might be more readily identified using gold-labelled remnants. We conclude that gold-conjugated chylomicron remnants might provide a useful means of detecting subtle changes in LDL receptor expression.

Intracellular localization and processing of Pseudomonas aeruginosa ExoS in eukaryotic cells

ExoS is a type III cytotoxin of Pseudomonas aeruginosa, which modulates two eukaryotic signalling pathways. The N-terminus (residues 1-234) is a GTPase activating protein (GAP) for RhoGTPases, while the C-terminus (residues 232-453) encodes an ADP-ribosyltransferase. Utilizing a series of N-terminal deletion peptides of ExoS and an epitope-tagged full-length ExoS, two independent domains have been identified within the N-terminus of ExoS that are involved in intracellular localization and expression of GAP activity. N-terminal peptides of ExoS localized to the perinuclear region of CHO cells, and a membrane localization domain was localized between residues 36 and 78 of ExoS. The capacity to elicit CHO cell rounding and express GAP activity resided within residues 90-234 of ExoS, which showed that membrane localization was not required to elicit actin reorganization. ExoS was present in CHO cells as a full-length form, which fractionated with membranes, and as an N-terminally processed fragment, which localized to the cytosol. Thus, ExoS localizes in eukaryotic cells to the perinuclear region and is processed to a soluble fragment, which possesses both the GAP and ADP-ribosyltransferase activities.

Identification and purification of cytolytic antibodies directed against O-acetylated sialic acid in childhood acute lymphoblastic leukemia

Sialic acids typically present as terminal sugars of oligo-saccharides are reported to be modified by O-acetylation at the C-9 position on lymphoblasts of childhood acute lymphoblastic leukemia (ALL) patients (Sinha et al., 1999a, Leukaemia, 13, 119-125). We now report high titers of IgG antibodies directed against O-acetylated derivatives of sialic acids (O-AcSA) in serum of ALL patients. These antibodies were purified using bovine submaxillary mucin (BSM) and the IgG distribution was confined to IgG(1)and IgG(2)subclasses; their binding was totally abolished with de-O-acetylation confirming their specificity towards O-AcSA determinants. Flow cytometry demonstrated binding of these antibody fractions to peripheral blood mononuclear cells (PBMC) of both T- and B-ALL patients having increased cell surface 9-O-AcSA determinants. Western blotting of membranes derived from PBMC of ALL patients confirmed binding of the antibody to O-acetylated sialoglycoconjugates corresponding to 144, 135, 120, 90, and 36 kDa whereas binding to PBMC from normal individuals corresponded to 144 and 36 kDa. Specificity of the antibody fraction towards 9-O-AcSA was substantiated by hemagglutination and hemagglutination-inhibition assays. The antibody purified from ALL serum selectively mediates complement dependent cytolysis of lymphoblasts expressing O-AcSAs and thereby possibly confers passive protection. The enhanced anti O-AcSA antibody levels allowed for development of a serodiagnostic assay (BSM-ELISA) specific for ALL. Minimal crossreactivity was observed with other hematological disorders like acute myeloid leukemia (n = 16), chronic myeloid leukemia (n = 6), chronic lymphocytic leukemia (n = 7) and non-Hodgkin's lymphoma (n = 3) as well as normal healthy individuals (n = 28). The BSM-ELISA therefore provides a simple, noninvasive alternative diagnostic approach for ALL and merits clinical consideration.

A connectionist model for convex-hull of a planar set

A neural network model is proposed for computation of the convex-hull of a finite planar set. The model is self-organizing in that it adapts itself to the hull-vertices of the convex-hull in an orderly fashion without any supervision. The proposed network consists of three layers of processors. The bottom layer computes the activation functions, the outputs of which are passed onto the middle layer. The middle layer is used for winner selection. These information are passed onto the topmost layer as well as fed back to the bottom layer. The network in the topmost layer self-organizes by labeling the hull-processors in an orderly fashion so that the final convex-hull is obtained from the topmost layer. Time complexities of the proposed model are analyzed and are compared with existing models of similar nature.

In vitro status epilepticus causes sustained elevation of intracellular calcium levels in hippocampal neurons

Calcium ions and calcium-dependent systems have been implicated in the pathophysiology of status epilepticus (SE). However, the dynamics of intracellular calcium ([Ca2+]i) levels during SE has not yet been studied. We have employed the hippocampal neuronal culture (HNC) model of in vitro SE that produces continuous epileptiform discharges to study spatial and dynamic changes in [Ca2+]i levels utilizing confocal laser scanning microscopy and the calcium binding dye, indo-1. During SE, the average [Ca2+]i levels increased from control levels of 150-200 nM to levels of 450-600 nM. This increased [Ca2+]i was maintained for the duration of SE. Following SE, [Ca2+]i levels gradually returned to basal values. The duration of SE was shown to affect the ability of the neuron to restore resting [Ca2+]i levels. Both N-methyl-D-aspartate (NMDA) receptor-gated and voltage-gated Ca2+ channels (VGCCs) contributed to the increased calcium entry during SE. Moreover, this elevation in [Ca2+]i occurred in both the nucleus and cytosol. These results provide the first dynamic measurement of [Ca2+]i during prolonged electrographic seizure discharges in an in vitro SE model and suggest that prolonged epileptiform discharges give rise to abnormal sustained increases in [Ca2+]i levels that may play a role in the neuronal cell damage and long-term plasticity changes associated with SE.