Aberrant Expression of Cardiac Troponin-T in Lung Cancer Tissues in Association With Pathological Severity

Background

Cardiac troponin-T (TNNT2) is exclusively present in cardiac muscle. Measurement of TNNT2 is used for diagnosing acute coronary syndrome. However, its expression may not be limited in myocardium. This study aimed at evaluating the expression of TNNT2 in neoplastic tissues.

Methods and Results

We used paraffin-embedded blocks of 68 patients with lung cancer (age, 68 ± 11 years old; early-stage, 33; advance-stage, 35) at Miyazaki University Hospital, Japan between January 1, 2017, and March 31, 2019. We stained the slide sections with primary monoclonal antibody against TNNT2 protein, and assessed the frequency of positive staining, and its association with pathological severity. In addition, we examined whether TNNT2 gene is detected in lung cancer tissues of four patients using reverse transcription-polymerase chain reaction. Immunoreactivity for TNNT2 protein was present in the cytoplasm and nucleus of lung cancer cells. The frequency was 37% (25 of 68) in all patients and was irrespective of histologic type (six of 13, squamous cell carcinoma; 18 of 50, adenocarcinoma; 0 of 4, neuroendocrine cell carcinoma; 1 of 1, large cell carcinoma). The prevalence increased with pathological staging [9% (3 of 33) at early-stage (Stage 0–I); 63% (22 of 35) at advance-stage (Stage II–IV and recurrence)]. In addition, frequency of positive staining for TNNT2 increased with pleural (χ² = 5.877, P = 0.015) and vascular (χ² = 2.449, P = 0.118) invasions but decreased with lymphatic invasion (χ² = 3.288, P = 0.070) in specimens performed surgical resection. Furthermore, TNNT2 mRNA was detected in the resected squamous cell carcinoma and adenocarcinoma tissues.

Conclusions

Our data suggest the aberrant expression of TNNT2 in lung cancer and its prevalence increases with pathological severity.

Molecular regulation of antioxidant ability in the hippocampus of EL mice

We recently found that the antioxidant ability was remarkably decreased in the hippocampus (Hipp) of EL at 8 weeks of age utilizing ESR spectroscopy. In this study, in addition to evaluating the extracellular glutamate concentration, we tried to determine whether or not changes in the expression of cystine/glutamate exchanger (xCT) and glutamate transporter take place in the Hipp of EL. EL mice and DDY mice at 5, 10, and 20 weeks of age were used for Exp. I and II, respectively. Exp. I: During the interictal state, dialysate was collected from the ventral Hipp using a microdialysis technique, and an extracellular concentration of glutamate ([Glu](o)) was measured with HPLC-ECD. Exp. II: The hippocampal expression of the glutamate transporter and xCT was estimated by Western blots. Exp. I: The level of [Glu](o) at 10 weeks of age was remarkably higher at other ages of EL mice, while [Glu](o) of DDY was unchanged as a result of age. Exp. II: The excitatory amino acid carrier-1 (EAAC-1) and xCT of EL mice at 10 weeks of age decreased more than those of DDY. GLAST and GLT-1 of EL mice at 5 weeks of age decreased more than those of DDY at the same age. No differences were found between EL and DDY for GLAST and GLT-1 at other ages. According to previous studies, the decreased endogenous antioxidant potential observed at 10 weeks of age is a very likely explanation for ictogenesis. The decreased xCT expression at 10 weeks of age could provide the molecular mechanism to explain the depletion of the endogenous antioxidant ability of EL mice during ictogenesis. In addition to the depletion of antioxidant ability, decreased EAAC-1 at this period could be one reason for the collapse of the molecular action of inhibition. These molecular findings support the idea that the elevation of [Glu](o) at 10 weeks of age triggers ictogenesis.

Two alloalleles of Xenopus laevis hairy2 gene--evolution of duplicated gene function from a developmental perspective

Gene duplication is a fundamental source of a new gene in the process of evolution. A duplicated gene is able to accept many kinds of mutations that could lead to loss of function or novel phenotypic diversity. Alternatively, the duplicated genes complementarily lose part of their functions to play original roles as a set of genes, a process called subfunctionalization. Pseudotetraploid frog Xenopus laevis has four sets of genes, and it is generally thought that the alloalleles in X. laevis have mutually indistinguishable functions. In this paper, we report differences and similarities between Xhairy2a and Xhairy2b in the neural crest, floor plate, and prechordal plate. Knockdown studies showed that Xhairy2a seems not to function in the neural crest, although both of them are required in the floor plate and the prechordal plate. Temporal expression pattern analysis revealed that Xhairy2a is a maternal factor having lower zygotic expression than Xhairy2b, while Xhairy2b is not loaded in the egg but has high zygotic expression. Spatial expression pattern analysis demonstrated that future floor plate expression is shared by both alloalleles, but Xhairy2b expression in the neural crest is much higher than Xhairy2a expression, consistent with the results of individual knockdown experiments. Therefore, our data suggest that subfunctionalization occurs in Xhairy2.

In vivo activation of N-methyl-D-aspartate receptors generates free radicals and reduces antioxidant ability in the rat hippocampus: experimental protocol of in vivo ESR spectroscopy and microdialysis for redox status evaluation

The pathological mechanisms of various CNS diseases are closely related to glutamate neuronal excitotoxicity following NMDA receptor activation. To verify this relationship, in vivo microdialysis in the hippocampus of rats was applied to ESR spectroscopy during NMDA perfusion. Microdialysis co-perfusion of 0.1 mM NMDA dissolved in 150 mM POBN for 60 min revealed six-line carbon-centered radical ESR spectra. The hfc values were aN=15.7 G and aHbeta=2.5 G, corresponding to the values produced from the generation of lipid radicals. The antioxidant activity during the freely moving state was examined utilizing the principle that systemically applied nitroxide radicals are reduced and lose their paramagnetism by antioxidant activity in the brain. ESR analysis of sequential changes in the signal amplitude of nitroxide radicals in both the NMDA group and the control group revealed an exponential decay. The half-life of the nitroxide radical was significantly longer in the NMDA group than in the control group. The homeostasis of a steady redox balance was destroyed by acute NMDA infusion, which resulted in the generation of lipid radicals and the reduction of antioxidant ability in the hippocampus. The redox imbalance induced by the activation of NMDA-R was recovered by the inhibition of PLA2 and NOS. These results indicated that NMDA-R activation caused the shift to oxidized condition of the redox state, which subsequently leads to neuron death in the hippocampus in the model of glutamate-associated neuronal disease.

Age-dependent changes in the hippocampal antioxidant ability of EL mice

Electron spin resonance (ESR) spectroscopy combined with in vivo microdialysis was used to analyze the antioxidant ability in the hippocampus of mice in an interictal state of EL mice utilizing decay ratio of an exogenously applied nitroxide radical (3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (PCAM)). In EL mice with a history of frequent seizures, the half-life of the electron paramagnetism of PCAM in the hippocampus was prolonged. These results revealed decreased antioxidant ability, suggesting vulnerability against oxidative stress. Our data suggest that epileptogenesis in EL mice with chronic seizures is associated with functional failure due to the oxidized redox state and revealed that the decreased hippocampal antioxidant ability is related to the regional vulnerability to oxidative stress in the limbic system of EL mice during epileptogenesis.

In vivo EPR estimation of bilateral hippocampal antioxidant ability of rats with epileptogenesis induced by amygdalar FeCl3 microinjection

PURPOSE

To measure the neural antioxidant function in the hippocampus of rats with epileptogenesis induced by microinjection of FeCl3 into the amygdala using the decay rate of the nitroxide radical as estimated by L-band electron paramagnetic resonance (EPR) spectroscopy.

MATERIALS AND METHODS

Region-selected intensity determination (RSID) was used for the estimation of the nitroxide decay ratio. It is possible to estimate the in vivo hippocampal antioxidant ability using the half-life of the EPR signal of the blood-brain barrier-permeable nitroxide radical. Rats were microinjected with aqueous FeCl3 into the right amygdaloid body. Recording from chronically implanted depth electrodes showed the development of spike discharges with recurrent seizures arising from amygdalar regions with propagation into both hippocampi. Rats with unilateral aqueous FeCl3 lesions were injected systemically with the nitroxide radical and then had EPR for RSID estimation at 5, 15, and 30 days after the iron salt injection.

RESULTS

The in vivo antioxidant ability of the dorsal hippocampus was significantly decreased bilaterally in animals with FeCl3-induced seizures when compared to the control.

CONCLUSION

Neural antioxidant function in the hippocampi of rats with chronic seizures induced by amygdalar FeCl3 was decreased early and both ipsilaterally and bilaterally.

Functional role for redox in the epileptogenesis: molecular regulation of glutamate in the hippocampus of FeCl3-induced limbic epilepsy model

We used western blotting to measure the quantity of glutamate and gamma-aminobutyric acid (GABA) transporters proteins within hippocampal tissue obtained from rats who had undergone epileptogenesis. Chronic seizures were induced by amygdalar injection of FeCl(3). We found that the glial glutamate transporters GLAST and GLT-1 were down-regulated at 60 days after initiation of chronic and recurrent seizures. However, the neuronal glutamate transporter EAAC-1 and the GABA transporter GAT-3 were increased. We performed in vivo microdialysis in freely moving animals to estimate in vivo redox state. We found that the hippocampal tissues were oxidized, resulting in even further impairment of glutamate transport. Our data show that epileptogenesis in rats resulting in chronic and recurrent seizures is associated with collapse of glutamate regulation caused by both the molecular down-regulation of glial glutamate transporters combined with the functional failure due to oxidation.

Protective role of pentobarbital pretreatment for NMDA-R activated lipid peroxidation is derived from the synergistic effect on endogenous anti-oxidant in the hippocampus of rats

We have attempted to explore the neuroprotective effectiveness of PBT by measuring anti-oxidant ability in the hippocampus of rats in a freely moving state. Anti-oxidant ability was examined utilizing the principle that blood-brain barrier-permeable nitroxide radicals (PCAM) injected i.p. lose their paramagnetism in an exponential decay correlated with anti-oxidant ability in the brain. The half-life of PCAM was used as the indicator of the hippocampal anti-oxidant ability. While the half-life was statistically prolonged when infused with 0.1mM NMDA without PBT, the half-life was almost the same as in the control when infused with NMDA under anesthesia with PBT. In addition, the half-life under only PBT anesthesia was the shortest of all the groups. Our findings, therefore, suggested that PBT anesthesia not only suppresses NMDA-R activated free radical generation but also synergistically enhances the increased basal endogenous anti-oxidant ability in the hippocampus.

Effect of levetiracetam on molecular regulation of hippocampal glutamate and GABA transporters in rats with chronic seizures induced by amygdalar FeCl3 injection

Enhancement of the glutamatergic excitatory synaptic transmission efficacy in the FeCl3 induced epilepsy model is associated with changes in the levels of glutamate and GABA transporter proteins. This study examined the effect of levetiracetam (LEV) on glutamate overflow and glutamate/GABA transporters expression in rats with epileptogenesis induced by the amygdalar injection of 1.0 microl of 100 mM FeCl3 (epileptic rat) and in control rats receiving amygdalar acidic saline injection (non-epileptic rat). In amygdalar acidic saline injected rats, 40 mM KCl-evoked glutamate overflow was significantly suppressed by both 32 and 100 microM LEV co-perfusion. In unilateral amygdalar FeCl3 injected rats, 32 microM LEV was ineffective, but the 100 microM LEV statistically suppressed glutamate overflow. Western blotting was employed to determine the hippocampal expression of glutamate/GABA transporters in epileptic or non-epileptic rats. The rats were treated for 14 days with 54 mg/kg LEV or vehicle intraperitoneally injection. Following 14 days of treatment, the ipsilateral hippocampus was removed for a Western blot analysis. In non-epileptic rats, the expression increased for all of the glutamate and GABA transporters (GLAST, GLT-1, EAAC-1, GAT-1 and GAT-3) while the glutamate transporter regulating protein (GTRAP3-18) decreased in comparison to those of normal rats that were treated with the vehicle. In epileptic rats receiving LEV, the EAAC-1 and GAT-3 levels increased while GTRAP3-18 (89%) decreased in comparison to those of the epileptic rats treated with the vehicle. GTRAP3-18 inhibitor regulates glutamate-binding affinity to EAAC-1. The anti-epileptic action of LEV may be partially due to a reduction of glutamate-induced excitotoxicity and an enhancement of the GABAergic inhibition as observed with the inhibitory effect on the 40 mM KCl-evoked glutamate overflow. These conclusions are supported by the increase in the expression of glial glutamate transporters (GLAST and GLT-1), and the increase in the expression of EAAC-1 and GAT-3 associated with a decrease in GTRAP3-18. The increased expression of EAAC-1 and the decreased expression of GTRAP3-18 in association with the up-regulation of GAT-3 due to such continual LEV administration was thus found to enhance GABA synthesis and reverse the transport of GABA both in non-epileptic and epileptic rats. The suppression of glutamate excitation and the enhancement of GABA inhibition in the rats with continual LEV administration is a result of the up-regulation of glutamate and GABA transporters with the down-regulation of GTRAP3-18. These observations together demonstrated the critical molecular mechanism of the anti-epileptic activity of LEV.

An acute dysfunction of the glutamate transport activity has been shown to generate free radicals and suppress the anti-oxidant ability in the hippocampus of rats

In this study, we attempted to elucidate whether or not an acute inhibition of glutamate transports activity with l-trans-pyrrolidine-2,4-dicarboxylic acid (l-trans PDC) would cause neuroexcitoxicity in the hippocampus. We used in vivo microdialysis and X-band electron spin resonance (ESR) spectroscopy to measure the changes in the redox state during the perfusion of l-trans PDC. ESR signals from rats using l-trans PDC were characteristically a six-line spectra, for which the hfc was a(N)=1.57mT and a(H)=0.25mT; these hfc's were obtained from the lipoxygenase/linoleic acid system that was used for the generation of lipid radicals. The antioxidant effect was measured using an ESR analysis to monitor sequential changes in the signal amplitude of nitroxide radical in the dialysate of both l-trans PDC and control animals. The pattern showed exponential decay with median half-life of the nitroxide radical took significantly longer in the l-trans PDC group. Acute changes in the glutamate transport resulted in the generation of a lipid radical and a depletion in the anti-oxidant effect in the hippocampus. Our data indicate that a dysfunction of a glutamate transport resulted in the collapse of the redox state, which thus eventually led to neuronal necrosis in the hippocampus. This study provides clear evidence for the mechanisms associated with neuronal disorder in relation to glutamate.

Functional role of GABA transporters for kindling development in GLAST KO mice

Kindling-induced after discharge in electroencephalograms depends on the protein associated with glutamatergic and/or GABAergic neuronal transmission. In glutamate transporter knockout (GLAST KO) mice, the kindling phenomena in GLAST KO developed more slowly while the after discharge duration (ADD) was briefer than that of the control C57BL-6J mice. These findings indicate that either the excitatory function was suppressed or the inhibitory function was enhanced in GLAST KO kindling. To explain these phenomena, we used Western blotting to evaluate the alterations in the expression of hippocampal GABA transporter proteins, and the estimation of the effect on the process of epileptogenesis. Although no alterations were observed in the GAT-3 expression, the hippocampal GAT-1 expression was significantly suppressed in comparison to that of C57BL-6J mice. A decreased GAT-1 level in the hippocampus, which might be associated with the increased extracellular GABA level, may therefore inhibit both ADD and seizure propagation as shown by the amygdaloid kindling phenomenon observed in GLAST KO mice.

Stem cell properties of human periodontal ligament cells

BACKGROUND AND OBJECTIVE

Stem cells have been used for regenerative therapies in various fields. The proportion of cells that possess stem cell properties in human periodontal ligament (PDL) cells is not yet well understood. In this study, we quantitatively characterized human PDL cells to clarify their stem cell properties, including self-renewal, multipotency, and stem cell marker expression.

MATERIAL AND METHODS

PDL cells were obtained from extracted premolar or wisdom teeth, following which a proliferation assay for self-renewal, a differentiation assay for multipotency, immunostaining for STRO-1, and fluorescence-activated cell sorter (FACS) analysis for stem cell markers (including CD105, CD166, and STRO-1) were performed.

RESULTS

Approximately 30% of 400 PDL cells were found to possess replicative potential and formed single-cell colonies, and 30% of these colonies displayed positive staining for STRO-1, 20% differentiated into adipocytes and 30% differentiated into osteoblasts. FACS analysis revealed that PDL cells, including cell populations, expressed the stem cell markers CD105, CD166, and STRO-1.

CONCLUSION

The findings of this study indicated that PDL cells possess crucial stem cell properties, such as self-renewal and multipotency, and express the mesenchymal stem cell markers CD105, CD166, and STRO-1 on their cell surface, although there were some variations. Thus, PDL cells can be used for periodontal regenerative procedures.

Generation of lipid radicals in the hippocampus of neonatal rats after acute hypoxic-ischemic brain damage

Free radical-mediated lipid peroxidation has been strongly suggested to be the main cause of neuronal toxicity in the rat brain, including neonatal brain damage. The primary objective of this experiment was to see if the generation of free radicals occurred in the acute phase of ischemic-hypoxic insult in neonatal rats, by electron paramagnetic resonance (EPR) spectroscopy and in vivo brain microdialysis. A spin trap agent, alpha-(4-pyridyl-N-oxide)-N-tert-butylnitrone was perfused through a probe in the hippocampus before and after hypoxia and then an analysis was performed by EPR. From the EPR analysis of spin adduct in the dialysates, we obtained the EPR spectrum of six line spectra for which the hyperfine coupling constants corresponded to those of the EPR signal from the lipoxygenase/linoleic acid (LPX/LA), a lipid radical generating system, increased transiently just after hypoxia. The results of our in vivo study show the lipid peroxidation of the neuronal membrane to progress during neonatal ischemic-hypoxic insult. We hypothesize that an increased formation of lipid radicals may participate in the cascade of reactions leading to neuronal damage in the hippocampus following ischemic-hypoxic insult in neonatal rats.

In vivo Evaluation of the Effect of Zonisamide on the Hippocampal Redox State During Kainic Acid-Induced Seizure Status in Rats

The aim in this study is to observe the hippocampal redox state during kainic-acid (KA)-induced seizure status, and examine the effect of systemic preinjection of anticonvulsant zonisamide (ZNS) on the hippocampal redox. To perform under a freely moving state, in vivo microdialysis method was applied to electron paramagnetic resonance (EPR) spectroscopy. Half-life of 3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (PCAM), a five-membered ring nitroxide radical, was used for the indicator of the hippocampal antioxidant ability. The changes in EPR signal intensities of PCAM decreased exponentially in all rats used. The average half-lives of PCAM was significantly shorter in the rats pretreated with ZNS than that of control group, and while the average half-lives of PCAM in the perfusate was significantly longer in the rats KA-induced status epilepticus than that of control (P < 0.01). Those of PCAM in the ZNS-pretreated rats followed by KA-injection were almost the same as those of control. These findings indicate that the pretreatment of ZNS increased the antioxidant ability in the hippocampus during KA-induced seizure. This study is the first in vivo evaluation of the antioxidant ability of ZNS as neuroprotective role against the free radicals performed under the condition of freely moving rats during seizure status.