Clinical application of NMP22 and urinary cytology in patients with hematuria or a history of urothelial carcinoma

For evaluation of the clinical application of immunoassay for nuclear matrix protein 22 (NMP22 immunoassay) and urinary cytology for early diagnosis and detection of bladder cancer in patients with hematuria and/or a previous history of bladder cancer, 209 urine samples obtained from 137 patients presenting episodes of hematuria or a history of bladder cancer were assayed for NMP22 levels and/or prepared for cytology examination. Biopsy was performed when any visible tumor was identified during cystoscopy examination. The median NMP22 concentrations measured in samples taken from patients with active bladder cancer, from patients with a history of bladder cancer but no active disease, from patients with hematuria, and from healthy volunteers were 18.95, 5.45, 6.39, and 3.75 U/ml, respectively. The urinary NMP22 level recorded for patients with urothelial carcinoma was significantly higher than that noted for individuals without active disease. The sensitivity of the NMP22 assay and of urinary cytology in diagnosing bladder cancer was 69% and 67%, respectively. In contrast, the specificity of these two diagnostic modalities reached 72% and 93%, respectively. The NMP22 assay is slightly more sensitive but less specific than urinary cytology in detecting bladder cancer. This study indicates that determination of urinary NMP22 levels is a useful and noninvasive tool for the detection of bladder cancer because of its high sensitivity. The urinary NMP22 assay may be used as a first-line routine screening method; however, it cannot replace the use of urinary cytology because of its lower specificity.

Recurrent asystoles associated with vasovagal reaction during venipuncture

A 17-year-old high school student presented with a history of habitual faintings. On 24-hour Holter monitoring, cardiac asystoles were recorded, the longest lasting approximately 7 or 8 seconds during venipuncture procedures. The asystole associated with venipuncture demonstrated the cardioinhibitory effects of vasovagal reaction with blood-injury phobia. He also had a positive response during head-up tilt test showing hypotension and relative bradycardia after intravenous isoproterenol injection. After administration of oral beta blocker, he did not show further or recurrent cardiac asystole during blood injury procedure on electrocardiographic examination. Venipuncture is the most common invasive medical procedure performed in hospital settings. While venipuncture is considered to be reasonably safe, serious complication may occur even when only a small volume of blood is withdrawn. Therefore, medical personnel should be prepared to provide appropriate care.

Up-regulated CNTF plays a protective role for retrograde degeneration in the axotomized rat retina

Using reverse transcription-polymerase chain reaction and in situ hybridization, we investigated the expression and cellular localization of ciliary neurotrophic factor receptor alpha (CNTFRalpha) in the rat retina following optic nerve transection (ONT). Following ONT, a signal for CNTFRalpha mRNA appeared in a layer-specific and time-dependent manner. In the ganglion cell layer, the signal showed a peak value 1 day after ONT, and then gradually decreased. In the inner nuclear layer the signal reached a peak value at 14 days of about 500% of control level, but then decreased at 4 weeks. Our findings suggest that CNTF might play a protective role for the retrograde degeneration of retinal cells induced by ganglion cell death in the rat retina following ONT.

Interaction of the retinoblastoma protein (pRb) with the catalytic subunit of DNA polymerase delta (p125)

The retinoblastoma gene product (pRb) interacts with many cellular proteins to function in the control of cell division, differentiation, and apoptosis. Several pRb binding proteins complex with pRb through an amino acid sequence called the LXCXE motif. The catalytic subunit of DNA polymerase delta (p125) contains a LXCXE motif. To further study the biochemical function of this polymerase, we sought to determine if p125 interacts with pRb. Experiments using GST-pRb fusion proteins showed that p125 from breast epithelial (MCF10A) cell extracts associates with pRb. In addition, GST-p125 fusion proteins bound pRb from the same cell extracts. The pRb that associated with GST-p125 was largely unphosphorylated. Coimmunoprecipitation experiments using cell cycle synchronized cells revealed that p125 and pRb form a complex predominantly during G1 phase, the phase during which pRb is mostly unphosphorylated. In vitro phosphorylation of GST-pRb by the cyclin dependent kinases reduced the ability of p125 to associate with GST-pRh. Addition of the LXCXE containing protein SV40 large T antigen to GST-pRb blocks the ability of p125 to associate with pRb, suggesting that it may be through a LXCXE sequence by which p125 interacts with pRb. Finally, in vitro polymerase assays demonstrate that GST-pRb fusion protein stimulates DNA polymerase delta activity.

Direct binding of hepatitis B virus X protein and retinoid X receptor contributes to phosphoenolpyruvate carboxykinase gene transactivation

The X gene product of the human hepatitis B virus (HBx), a major factor responsible for hepatitis and hepatocellular carcinoma, modulates transactivation by a variety of transcription factors. Herein, expression of the phosphoenolpyruvate carboxykinase (PEPCK) gene was found to be regulated transcriptionally by HBx through two distinct promoter regions. The cAMP response element (CRE)-1 site within the proximal promoter region mediated the HBx-induced transactivation of the PEPCK gene through C/EBP alpha and ATF-2. A retinoid X receptor (RXR) response element within the distal promoter region also contributed to the HBx-induced transactivation. Consistent with these results, HBx directly interacted with RXR, and the interaction interfaces were localized to the transactivation domain of HBx and the ligand binding domain of RXR.

Expression of brain/kidney protein in Müller cells of rat retina following transient ischemia

We have investigated the expression and cellular localization of brain/kidney (B/K) protein in the rat retina following transient ischemia. In the normal retina, strong B/K immunoreactivity was localized to some ganglion cells. In addition, a few radial Muller cell processes showed B/K immunoreactivity. Following ischemia and reperfusion, most B/K-labeled ganglion cells were lost, whereas between 1 day and 2 weeks post-lesion B/K immunoreactivity appeared in many more Muller cell processes with increasing intensity. Quantitative evaluation by immunoblotting confirmed that B/K expression then decreased progressively, to 35% of control values at four weeks post-lesion. Our findings suggest that Muller cells are involved in the pathophysiology of retinal ischemia through the expression of B/K following transient ischemia.

Characterization of the 5'-flanking region of the gene encoding the 50 kDa subunit of human DNA polymerase delta

DNA polymerase delta consists of at least four subunits: p125, p68, p50, and p12 [Liu et al., J. Biol. Chem. 275 (2000) 18739-18744]. We have isolated genomic DNA clones covering the gene for the human DNA polymerase delta 50 kDa subunit (POLD2) and its 5'-flanking sequence. The POLD2 gene is composed of 11 exons and is distributed over 10 kb of genomic DNA. All exon-intron splice junctions conformed to the GT/AG consensus sequence. The 5'-flanking region of human POLD2 is G+C-rich and does not have a typical TATA box. A computer-based search for potential transcription factor binding sites revealed the existence of a number of motifs including those for AP1, AP2, Sp1, NF-1 and CREB. The functional activity of the regulatory region of the human POLD2 gene was demonstrated by its ability to drive the expression of a chloramphenicol acetyltransferase reporter gene in COS-7 cells.

The life readiness program: a physical rehabilitation program for patients on hemodialysis

Patients with end-stage renal disease (ESRD) undergoing hemodialysis (HD) are typically sedentary and functionally limited as a consequence of their condition. The purpose of this study is to test the effect of a lifestyle physical rehabilitation program (The Life Readiness Program) on physical function in patients with ESRD undergoing HD. Physical function was measured by the Kidney Disease Quality of Life Short Form (KDQOL-SF) physical function score (range, 0 to 100). Eighty-two patients were randomly assigned to a 6-month rehabilitation program (intervention; n = 39) or to standard clinical management alone (control; n = 43). The groups were frequency matched by age, sex, ethnicity, and diabetes as the cause of ESRD. General linear modeling of the change in physical function score was used for multivariate analysis. Physical function scores were not different between groups at baseline. Change in physical function score increased significantly in the intervention group compared with the control group when data were adjusted for the matching variables and adequacy of dialysis (3.2, -3.6; P = 0.04). Additionally, the control group reported more problems with work or daily functions because of emotional problems (P: </= 0.05). In this brief 6-month intervention, The Life Readiness Program showed the therapeutic benefit of a lifestyle rehabilitation program on functional outcomes and health-related quality of life for patients with ESRD undergoing hemodialysis.

Biological monitoring of occupational exposure to N,N-dimethylformamide--the effects of co-exposure to toluene or dermal exposure

OBJECTIVES

The objective of this study is to assess the exposure and intake dose of N,N-dimethylformamide (DMF) and the correlation between them, according to the type of exposure for the workers in the DMF industry.

METHODS

We monitored 345 workers occupationally exposed to DMF, from 15 workshops in the synthetic fiber, fiber coating, synthetic leather and paint manufacturing industries. Ambient monitoring was carried out with personal samplers to monitor the external exposure. Biological monitoring was done to determine the internal dose by analyzing N-methylformamide (NMF) in end-shift urine. Work procedure and exposure type of each DMF workshop was carefully surveyed, to classify workers by exposure type according to work details. Workers were classified into three groups (Group A: continuous and direct exposure through inhalation and skin; Group B: intermittent and short-term exposure through inhalation and skin; Group C: continuous and indirect exposure mostly through inhalation).

RESULTS

Geometric mean of DMF concentration in air was 2.62 (GSD 5.30) ppm and that of NMF in urine was 14.50 (GSD 3.89) mg/l. In the case of continuous absorption through inhalation and dermal exposure (Group A), the value of NMF in urine corresponding to 10 ppm of DMF was 45.3 mg/l (r = 0.524, n = 178), 39.1 mg/g creatinine (r = 0.424), while it was 37.7 mg/l (r = 0.788, n = 37), 24.2 mg/g creatinine (r = 0.743) in the case of absorption mostly through inhalation (Group C). Creatinine correction reduced the correlation between two parameters.

CONCLUSION

The NMF in urine corresponding to 10 ppm DMF, of the dermal and inhalation exposure group was 39.1 mg/g creatinine (r = 0.424, n = 178), while that of the inhalation exposure-only group was 24.2 mg/g creatinine (r = 0.743, n = 37). Co-exposure with toluene reduced the NMF excretion in urine.

Identification of phosphorylated form of cAMP/calcium response element binding protein expression in the brain stem nuclei at early stage of vestibular compensation in rats

The present study was aimed at evaluating the time-dependent expressions of phosphorylated forms in the cAMP/calcium response element binding protein (pCREB) known to be one of transcription factors for immediate early genes in the brain stem nuclei of Sprague-Dalwey rats. Animals received surgical ablation of right peripheral vestibular labyrinth through a ventral approach. Immunohistochemical staining and digital image analysis systems were used to observe pCREB expressions in neuronal cells of the brain stem nuclei. The number of pCREB labeling neurons were increased with time, and peaked in the vestibular nuclear complex (VNC) bilaterally 1 h after unilateral labyrinthectomy (UL). In addition, high levels of phosphorylated CREB-like immunoreactivity (pCREB-LI) were also observed in bilateral cerebellum, olivary nuclear complex, and medullary nuclei. There was a rapid reduction of pCREB-LI in contralateral VNC but a slow reduction in the ipsilateral side 2 h after UL, causing an asymmetric number of pCREB labeling neurons between bilateral VNC (P<0.05). Thereafter pCREB-LI in bilateral VNC decreased to a very low level and returned to basal level 24 h after UL. These results suggest that the activation of the cAMP/calcium response element binding protein plays a role in the initial events of vestibular compensation in rats.

Shibimijihwang-tang elevates intracellular ATP and choline content in the cerebral cortex of ovariectomized rats

Shibimijihwang-tang (SJT) has been used traditionally to improve systemic blood circulation and biological energy production in patients with circulatory and neuronal diseases. The object of this study is to determine the effect of SJT extract on the intracellular adenosine triphosphate (ATP) and choline content in the cerebral cortex of ovariectomized (OVX) rats. Bilateral ovaries of 8-week-old rats were removed. Rats were maintained for 12 weeks to deplete ovarian steroid hormones, followed by treatment with SJT at 500 mg/kg body weight per day for 12 weeks. High rate of body weight increase in the OVX rats was markedly reduced by treatment with SJT, but the change in body weight of normal rats was not affected by it. SJT also significantly reduced the decline of cerebral weight in the OVX rats (P<0.05). Tissue glucose content in the cerebral cortex of OVX rats was significantly increased by SJT treatment (P<0.05). A decline in cerebral ATP content in OVX rats was dramatically restored by SJT administration (P<0.01), but SJT did not change the cerebral ATP content in normal rats. Cerebral choline content also declined following ovariectomy. This reduction was significantly elevated by SJT treatment (P<0.05), but SJT did not affect the change in cerebral choline in normal rats. Taken together, these results demonstrate that SJT can reduce the decrease in brain weight, cerebral ATP and choline content caused by deprivation of ovarian steroid hormones. This suggests that pharmacological properties of SJT may play a role in improvement of reduced cerebral energy production and cholinergic neurotransmitter synthesis caused by deficiency of ovarian steroid hormones in the cerebroneuronal cells of postmenopausal women.

Flavin-containing monooxygenase isoform 2: developmental expression in fetal and neonatal rabbit lung

Mammalian flavin-containing monooxygenase functions in the oxygenation of numerous xenobiotics containing a soft nucleophile, usually a nitrogen or sulfur. A total of five distinct flavin monooxygenase (FMO) isoforms are expressed in mammals. Individual isoforms are expressed in a sex-, age-, and tissue-specific fashion. In this study, we document the early developmental appearance of the major isoform in rabbit lung, FMO2. FMO2 catalytic activity as well as protein and mRNA are not only present in fetal and neonatal lung but, in some instances, approach levels found in the adult. The expression pattern of FMO2 is similar to that of the two major constitutive cytochromes P450 found in rabbit lung, 2B4 and 4B1. The early developmental appearance of these monooxygenases indicate an important role in the protection of the fetus and neonate against toxic insult from foreign chemicals.

Fractionation and characterization of mushroom dietary fiber (nonstarch polysaccharides) as potential nutraceuticals from sclerotia of Pleurotus tuber-regium (Fries) singer

The nonstarch polysaccharides (NSPs) in the total dietary fiber (TDF) from the sclerotia of Pleurotus tuber-regium (tiger milk mushroom) were fractionated by the sequential use of chemical solvents. About half of the TDF was solubilized and two major alkali-soluble fractions (1 and 4 N sodium hydroxide) that contained 126 and 293 g/kg TDF were obtained. Sugar analysis and infrared spectroscopy indicated that the NSPs in these alkali-soluble fractions were mainly beta-glucans and chitin. These alkali-soluble NSPs were further purified by anion-exchange chromatography followed by gel permeation chromatographic separation. Methylation analysis revealed that these purified glucans were highly branched and contained a mixture of sugar linkages of beta-1,3, beta-1,6, and beta-1,4. The potential use of these sclerotial beta-glucans as nutraceuticals was discussed.

The effects of isolated lipoproteins and triglyceride, combined oxidized low density lipoprotein (LDL) plus triglyceride, and combined oxidized LDL plus high density lipoprotein on the contractile and relaxation response of rabbit cavernous smooth muscle

The aim of this study was to investigate the effects of isolated lipoproteins and triglyceride (TG), and the effects of combined oxidized low density lipoprotein (LDL) plus TG and the combined oxidized LDL plus high density lipoprotein (HDL) on the contractility and relaxation response of rabbit cavernous smooth muscle. Cavernous muscle strips from New Zealand White rabbits were studied in organ chambers for isometric tension measurement. The strips were exposed to HDL, LDL, oxidized LDL, TG, combined oxidized LDL plus TG and combined oxidized LDL plus HDL for 30 min. Both HDL and LDL did not affect contraction and relaxation responses of the cavernous muscles. The oxidized LDL did not affect norepinephrine (NE)-induced contractility of the strips, but significantly (p < 0.05) decreased the relaxation response to endothelium-dependent agonist, acetylcholine (Ach). Non-specific NO synthase inhibitor (L-NAME) completely inhibited the relaxation response to Ach, and L-arginine partially improved the diminished relaxation. TG did not significantly change the relaxation responses to Ach, but decreased the contractility of cavernous muscle to NE. Neither the combined oxidized LDL plus TG nor oxidized LDL plus HDL had significant synergistic or detoxication effects on the contractility and relaxation responses. In conclusion, oxidized LDL may have acute toxic effects on the endothelium-dependent, NO-mediated relaxation, but not on the contractility, of rabbit cavernous smooth muscle. TG may decrease contractility of the cavernous muscle. There may be neither synergistic nor detoxication effects on the contractility and relaxation response when TG or HDL is added to the oxidized LDL.

Regulation of protein function by native metastability

In common globular proteins, the native form is in its most stable state. In contrast, each native form exists in a metastable state in inhibitory serpins (serine protease inhibitors) and some viral membrane fusion proteins. Metastability in these proteins is critical to their biological functions. Mutational analyses and structural examination have previously revealed unusual interactions, such as side-chain overpacking, buried polar groups, and cavities as the structural basis of the native metastability. However, the mechanism by which these structural defects regulate protein functions has not been elucidated. We report here characterization of cavity-filling mutations of alpha(1)-antitrypsin, a prototype serpin. Conformational stability of the molecule increased linearly with the van der Waals volume of the side chains. Increasing conformational stability is correlated with decreasing inhibitory activity. Moreover, the activity loss appears to correlate with the decrease in the rate of the conformational switch during complex formation with a target protease. These results strongly suggest that the native metastability of proteins is indeed a structural design that regulates protein functions.

A systemic administration of NMDA induces immediate early gene pip92 in the hippocampus

In the mammalian CNS, aspartate and glutamate are major excitatory amino acids, and their receptors are believed to mediate a wide range of physiological and pathological processes, including neurotransmission, plasticity, excitotoxicity, and various forms of neurodegeneration. The immediate early gene pip92 has been identified in serum-stimulated BALB/c 3T3 fibroblasts, activated T lymphocytes treated with cycloheximide, and fibroblast growth factor-stimulated hippocampal cells during neuronal differentiation. In this study we have demonstrated that pip92 is expressed in the mouse brain after a single intraperitoneal injection of NMDA. The distribution of pip92 mRNA levels in the NMDA-treated mouse brain was investigated using in situ RT-PCR. The region-specific activation of pip92 in the CNS was observed 3 h after NMDA injection, and high levels of pip92 mRNA were detected in the hippocampal dentate gyrus and piriform cortex regions. In addition, the activation of pip92 by NMDA was mediated by activation of mitogen-activated protein kinases (MAPKs), such as c-Jun N-terminal kinase (JNK) and p38 kinase, but not extracellular signal-regulated kinase (ERK) in the mouse hippocampus and immortalized rat hippocampal progenitor cells. This study suggests that pip92 is likely to play an important role in neuronal cell death induced by excitotoxic NMDA injury in the CNS.

Identification of a fourth subunit of mammalian DNA polymerase delta

A 12-kDa and two 25-kDa polypeptides were isolated with highly purified calf thymus DNA polymerase delta by conventional chromatography. A 16-mer peptide sequence was obtained from the 12-kDa polypeptide which matched a new open reading frame from a human EST () encoding a hypothetical protein of unknown function. The protein was designated as p12. Human EST was identified as the putative human homologue of Schizosaccharomyces pombe Cdm1 by a tBlastn search of the EST data base using S. pombe Cdm1. The open reading frame of human EST encoded a polypeptide of 107 amino acids with a predicted molecular mass of 12.4 kDa, consistent with the experimental findings. p12 is 25% identical to S pombe Cdm1. Both of the 25-kDa polypeptide sequences matched the hypothetical KIAA0039 protein sequence, recently identified as the third subunit of pol delta. Western blotting of immunoaffinity purified calf thymus pol delta revealed the presence of p125, p50, p68 (the KIAA0039 product), and p12. With the identification of p12 mammalian pol delta can now be shown to consist of four subunits. These studies pave the way for more detailed analysis of the possible functions of the mammalian subunits of pol delta.

Upregulation of ciliary neurotrophic factor in reactive Müller cells in the rat retina following optic nerve transection

We have investigated the expression and cellular localization of ciliary neurotrophic factor (CNTF) in the rat retina following optic nerve transection. In the normal retina, CNTF immunoreactivity was restricted to profiles in the ganglion cell layer. Following optic nerve transection, immunoreactivity appeared in Müller cell somata and processes and its intensity increased between three and seven days post-lesion. Quantitative evaluation by immunoblotting confirmed that CNTF expression increased continuously up to 7 days after optic nerve transection (to 430% of control levels), but decreased again to 250% of controls at 4 weeks post-lesion. Our findings suggest that CNTF supplied by Müller cells may play a protective role for axotomized ganglion cells in the rat retina.

Evidence that DNA polymerase delta isolated by immunoaffinity chromatography exhibits high-molecular weight characteristics and is associated with the KIAA0039 protein and RPA

DNA polymerase delta, the key enzyme for eukaryotic chromosomal replication, has been well characterized as consisting of a core enzyme of a 125 kDa catalytic subunit and a smaller 50 kDa subunit. However, less is known about the other proteins that may comprise additional subunits or participate in the macromolecular protein complex that is involved in chromosomal DNA replication. In this study, the properties of calf thymus pol delta preparations isolated by immunoaffinity chromatography were investigated. It is demonstrated for the first time using highly purified preparations that the pol delta heterodimer is associated with other polypeptides in high-molecular weight species that range from 260000 to >500000 in size, as determined by FPLC gel filtration. These preparations are associated with polypeptides of ca. 68-70, 34, 32, and 25 kDa. Similar findings were revealed with glycerol gradient ultracentrifugation. The p68 polypeptide was shown to be a PCNA binding protein by overlay methods with biotinylated PCNA. Protein sequencing of the p68, p34, and p25 polypeptide bands revealed sequences that correspond to the hypothetical protein KIAA0039. KIAA0039 displays a small but significant degree of homology to Schizosaccharomyces pombe Cdc27, which, like Saccharomyces cerevisiae Pol32p, has been described as the third subunit of yeast pol delta. These studies provide evidence that p68 is a subunit of pol delta. In addition, the p68-70 and p32 polypeptides were found to be derived from the 70 and 32 kDa subunits of RPA, respectively.

Inhibitory effect of serotonergic drugs on contractile response of the rat vas deferens to electrical nerve stimulation: in vivo study

PURPOSE

To evaluate, in vivo, the inhibitory effects of certain serotonergic drugs on the contractile response of the rat seminal tract to electrical stimulation of the hypogastric nerve.

MATERIALS AND METHODS

Twenty-five Sprague Dawley rats (250 to 300 gm. each) were equally divided into 5 groups based on experimental agent; normal saline, clomipramine, sertraline, paroxetine, and fluoxetine. The hypogastric nerve was electrically stimulated and the intraluminal pressure of the vas deferens was measured, both pretreatment and 30 minutes after intravenous injection of four different doses (0.1 to 20 x the therapeutic dose) of each agent. Variations of responses relative to the time after administration of each agent (at 10- and 20-fold concentration) were also observed.

RESULTS

All serotonergic drugs caused dose-dependent inhibition of elevation in intraluminal pressure of the vas deferens (p <0.05). The inhibitory effect of clomipramine was significantly better (p <0. 05) than that of fluoxetine at a 1-fold dose, while no significant differences were noted among clomipramine, sertraline and paroxetine. At doses of 10- and 20-fold, clomipramine had the strongest inhibitory effect, followed by sertraline and paroxetine, then fluoxetine (p <0.05). No differences were found in the inhibitory effects of the drugs studied, as a function of the time after injection.

CONCLUSIONS

Clomipramine was the most potent drug for inhibition of elevation in intraluminal pressure of the rat vas deferens induced by electrical stimulation of the rat hypogastric nerve. The stronger inhibitory effect of clomipramine than the selective serotonin reuptake blockers suggests a possible peripheral action of clomipramine in addition to its central serotonergic action.

Congenital cytomegalovirus infection: three autopsy case reports

We report three autopsy cases of congenital cytomegalovirus (CMV) infection in fetuses with a review of literature. The clinical manifestations in these cases of congenital CMV infection include intrauterine fetal death, hydrops fetalis, and CMV pneumonia associated with cardiovascular defect. The pathological characteristics were as follows: 1) the kidney was the most frequently involved organ, followed by lung and liver, 2) CMV inclusions were found predominantly in epithelial cells and to a lesser degree in endothelial cells, 3) intrahepatic bile duct epithelial cells were frequently involved, and 4) inflammatory reaction around CMV inclusions was not prominent in the early stage of pregnancy. Diagnostic confirmation was obtained by in situ hybridization (ISH) using a biotinylated CMV-DNA probe, which demonstrated intranuclear inclusions and sometimes recognized cells that did not show intranuclear inclusion.

Transfer and/or breakup modes in the 6He+209Bi reaction near the coulomb barrier

Reaction products from the interaction of 6He with 209Bi have been measured at energies near the Coulomb barrier. A 4He group of remarkable intensity, which dominates the total reaction cross section, has been observed. The angular distribution of the group suggests that it results primarily from a direct nuclear process. It is likely that this transfer and/or breakup channel is the doorway state that accounts for the previously observed large sub-barrier fusion enhancement in this system.

Inhibitory action of thimerosal, a sulfhydryl oxidant, on sodium channels in rat sensory neurons

The effects of thimerosal, a sulfhydryl oxidizing agent, on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) sodium channels in rat dorsal root ganglion neurons were studied using the whole-cell patch clamp technique. Thimerosal blocked the two types of sodium channels in a dose-dependent manner. The inhibitory effect of thimerosal was much more pronounced in TTX-R sodium channels than TTX-S sodium channels. The effect of thimerosal was irreversible upon wash-out with thimerosal-free external solution. However, dithiothreitol, a reducing agent, partially reversed it. Thimerosal shifted the steady-state inactivation curves for both types of sodium channels in the hyperpolarizing direction. The voltage dependence of activation of both types of sodium channels was shifted in the depolarizing direction by thimerosal. The inactivation rate in both types of sodium channels increased after thimerosal treatment. All these effects of thimerosal would add up to cause a depression of sodium channel function leading to a diminished neuronal excitability.

Upregulation of phospholipase D in astrocytes in response to transient forebrain ischemia

Previous in vitro studies using cell cultures or brain slices have demonstrated that phospholipase D (PLD) in the nervous system is involved in the signaling mechanism in response to a variety of agonists. However, little is known about the pathophysiological role of PLD-mediated signaling in the adult brain. We examined the changes in the expression of a PLD isozyme, PLD1, in the adult rat hippocampus, using immunological approaches and an assay for PLD activity after transient forebrain ischemia (four-vessel occlusion model) that results in the selective delayed death of CA1 pyramidal cells and induces reactive astrocytes in the CA1 subfield. In the control hippocampus, PLD1 the level of immunoreactivity was very low. After ischemia, in parallel with the results of Western blot analysis and the PLD activity assay, immunohistochemical analysis of PLD1 demonstrated that the immunoreactive proteins peaked at 7-14 days and were most prominent in the CA1 and the dentate hilar region. The temporal and spatial patterns of immunoreactivity of both PLD1 and glial fibrillary acidic protein (GFAP) were very similar, indicating that reactive astrocytes express PLD1, confirmed by double staining for PLD1 and GFAP. These results demonstrate that reactive astrocytes upregulate PLD in vivo after injury in the adult rat hippocampus.