The AAA+ protein ATAD3 has displacement loop binding properties and is involved in mitochondrial nucleoid organization.

Many copies of mammalian mitochondrial DNA contain a short triple-stranded region, or displacement loop (D-loop), in the major noncoding region. In the 35 years since their discovery, no function has been assigned to mitochondrial D-loops. We purified mitochondrial nucleoprotein complexes from rat liver and identified a previously uncharacterized protein, ATAD3p. Localization studies suggested that human ATAD3 is a component of many, but not all, mitochondrial nucleoids. Gene silencing of ATAD3 by RNA interference altered the structure of mitochondrial nucleoids and led to the dissociation of mitochondrial DNA fragments held together by protein, specifically, ones containing the D-loop region. In vitro, a recombinant fragment of ATAD3p bound to supercoiled DNA molecules that contained a synthetic D-loop, with a marked preference over partially relaxed molecules with a D-loop or supercoiled DNA circles. These results suggest that mitochondrial D-loops serve to recruit ATAD3p for the purpose of forming or segregating mitochondrial nucleoids.

Inflammation confers dual effects on nociceptive processing in chronic neuropathic pain model.

BACKGROUND: Although inflammation induces pain, immune cells also produce mediators that can effectively counteract it. To further elucidate the role of the immune response, we analyzed the relationship of pain behavior, several inflammatory signals, and opioid peptides using partial sciatic nerve ligation in mice at different levels of immunocompromise. METHODS: Sciatic nerves of C57BL/6C, nonobese diabetic (NOD), or nonobese diabetic-severe combined immune deficiency (NOD-SCID) mice were partially ligated. Responses to mechanical and radiant heat stimuli were observed. Inflammation was detected by immunohistochemistry and flow cytometry. Inflammatory cytokines and opioid peptides were analyzed using real-time polymerase chain reaction and enzyme-linked immunosorbent assay or immunostaining. RESULTS: Inflammation in immunocompromised mice was subordinate when compared with that seen in C57BL/6C mice. In addition, immunocompromised mice had less pain hypersensitivity at early stages. Whereas proinflammatory tumor necrosis factor-α (TNF-α), interleukin 1ß (IL-1ß), interleukin 6 (IL-6), and interferon-γ (IFN-γ), as well as antiinflammatory interleukin 1 receptor antagonist (IL-1Ra), interleukin 4 (IL-4), interleukin 10 (IL-10), and interleukin 13 (IL-13) cytokine expression and protein were increased in C57BL/6C mice, they were lower in immunocompromised mice. Although enkephalin, dynorphin, and ß-endorphin messenger RNA expression also increased in C57BL/6C mice, peaking on day 14, this result was not observed in immunocompromised mice. CONCLUSION: The contribution of inflammation to nerve injury is complex with biphasic modulation. During the early phase, a wide range of proinflammatory cytokines are released, leading to enhanced pain. In contrast, the analgesic effect of opioid peptides and antiinflammatory cytokines was more predominate in the later phases of injury, leading to attenuated pain responses.

Hemeoxygenase-1 upregulation is critical for sirtinol-mediated attenuation of lung injury after trauma-hemorrhage in a rodent model.

BACKGROUND: Hemeoxygenase-1 induction in response to adverse circulatory conditions is protective. Our recent study has shown that administration of sirtinol attenuates hepatic injury in male Sprague-Dawley rats after trauma-hemorrhage; however, the mechanism by which sirtinol produces the salutary effects remains unknown. We hypothesized that sirtinol administration in male Sprague-Dawley rats after trauma-hemorrhage decreases cytokine production and protects against lung injury through a hemeoxygenase-1 related pathway. METHODS: Male Sprague-Dawley rats (n = 8 per group) underwent trauma-hemorrhage (mean arterial blood pressure 40 mm Hg for 90 min, then resuscitation). A single dose of sirtinol (1 mg/kg of body weight) with or without a hemeoxygenase enzyme inhibitor (chromium-mesoporphyrin) or vehicle was administered IV during resuscitation. Twenty-four hours thereafter, myeloperoxidase activity (a marker of neutrophil sequestration) and tumor necrosis factor alpha, interleukin-6, and interleukin-10 levels in the lung, protein concentrations in bronchoalveolar lavage fluid and tissue histology were measured. Lung hemeoxygenase-1 protein level was also determined. RESULTS: In the sirtinol-treated rats subjected to trauma-hemorrhage, there were significant improvements in lung myeloperoxidase activity (4.68 +/- 0.31 vs 9.36 +/- 1.03 U/mg protein, P < 0.05), tumor necrosis factor alpha levels (710.7 +/- 28 vs 1288 +/- 40.69 pg/mg protein, P < 0.05), interleukin-6 levels (343.6 +/- 18.41 vs 592.7 +/- 22.3 pg/mg protein, P < 0.05), and protein concentrations (303.8 +/- 24.54 vs 569.6 +/- 34.82 microg/mL, P < 0.05) and lesser damage in histology. There was no statistically significant difference in interleukin-10 levels in the lung between sirtinol-treated trauma-hemorrhaged rats and vehicle-treated trauma-hemorrhaged rats (842.5 +/- 54.18 vs 756.2 +/- 41.34 pg/mg protein, respectively). Lung hemeoxygenase-1 protein levels were increased in rats receiving sirtinol treatment as compared with vehicle-treated trauma-hemorrhaged rats (5.18 +/- 0.25 vs 2.70 +/- 0.16, P < 0.05). Administration of the hemeoxygenase inhibitor chromium-mesoporphyrin prevented the sirtinol-induced attenuation of shock-induced lung damage. CONCLUSION: The salutary effects of sirtinol administration on attenuation of lung inflammation after trauma-hemorrhage are mediated via upregulation of hemeoxygenase-1 expression.

Adenylate cyclase inhibition attenuates neuropathic pain but lacks pre-emptive effects in rats.

PURPOSE: There is evidence that cyclic adenosine monophosphate (cAMP) transduction is involved in nociceptive processing. We previously showed that intrathecal injection of an adenylate cyclase inhibitor attenuated tactile allodynia caused by partial sciatic nerve ligation (PSNL) in rats. The present study investigates the pre-emptive effects of spinal cAMP transduction on nociceptive processing in a chronic neuropathic pain model. METHODS: Intrathecal catheterization and PSNL were performed in male Sprague-Dawley rats. Nociceptive responses to mechanical and thermal stimuli were evaluated at the hindpaw at 2 hr and at 3, 7, and 14 days after PSNL. The pre-emptive effects of the intrathecal adenylate cyclase inhibitor, SQ22536 (0.7 mumol x L(-1), 30 min before or after nerve ligation) were assessed. Also, the spatial and temporal expression profiles and immunoreactivity in the spinal cord of the cAMP response element binding protein (CREB) and its phosphorylated proteins (CREB-IR and p-CREB-IR) were analyzed. RESULTS: Compared with the rats treated with the vehicle, allodynia and hyperalgesia were significantly attenuated at 1-3 days by the intrathecal injection of SQ22536 performed either before or after ligation. The expression of CREB was significantly higher after ligation (P < 0.05), but differences were not observed between groups. Intrathecal injection of SQ22536, either before or after ligation, partially reduced p-CREB-IR protein expression in comparison with the vehicle control, especially after the first 3 days (P < 0.05). CONCLUSION: Our results show a possible association between the increase in p-CREB and PSNL-induced neuropathic pain. However, a pre-emptive effect of adenylate cyclase inhibitor administered before surgery was not observed.

Mammalian mitochondrial nucleoids: organizing an independently minded genome.

Mitochondrial DNA is arranged in nucleoprotein complexes, or nucleoids. Nucleoid proteins include not only factors involved in replication and transcription but also structural proteins required for mitochondrial DNA maintenance. Although several nucleoid proteins have been identified and characterized in yeast over the course of the past decade, little was known of mammalian mitochondrial nucleoids until recently. Two publications in the past year have expanded considerably the pool of putative mammalian mitochondrial nucleoid proteins; and analysis of one of the candidates, ATAD3p, suggests that mitochondrial nucleoid formation and division are orchestrated, not random, events.

Lack of interleukin-17 leads to a modulated micro-environment and amelioration of mechanical hypersensitivity after peripheral nerve injury in mice.

Interleukin-17 (IL-17) is involved in a wide range of inflammatory disorders and in recruitment of inflammatory cells to injury sites. A recent study of IL-17 knock-out mice revealed that IL-17 contributes to neuroinflammation and neuropathic pain after peripheral nerve injury. Surprisingly, little is known of micro-environment modulation by IL-17 in injured sites and in pathologically related neuroinflammation and chronic neuropathic pain. Therefore, we investigated nociceptive sensitization, immune cell infiltration, myeloperoxidase (MPO) activity, and expression of multiple cytokines and opioid peptides in damaged nerves of wild-type (IL-17(+/+)) and IL-17 knock-out (IL-17(-/-)) mice after partial sciatic nerve ligation. Our results demonstrated that the IL-17(-/-) mice had less behavioral hypersensitivity after partial sciatic nerve ligation, and inflammatory cell infiltration and pro-inflammatory cytokine (tumor necrosis factor-α, IL-6, and interferon-γ) levels in damaged nerves were significantly decreased, with the levels of anti-inflammatory cytokines IL-10 and IL-13, and expressions of enkephalin, ß-endorphin, and dynorphin were also decreased compared to those in wild-type control mice. In conclusion, we provided evidence that IL-17 modulates the micro-environment at the level of the peripheral injured nerve site and regulates progression of behavioral hypersensitivity in a murine chronic neuropathic pain model. The attenuated behavioral hypersensitivity in IL-17(-/-) mice could be a result of decreased inflammatory cell infiltration to the injured site, resulting in modulation of the pro- and anti-inflammatory cytokine milieu within the injured nerve. Therefore, IL-17 may be a critical component for neuropathic pain pathogenesis and a novel target for therapeutic intervention for this and other chronic pain states.

Peritoneal administration of Met-RANTES attenuates inflammatory and nociceptive responses in a murine neuropathic pain model.

UNLABELLED: The C-C motif chemokine ligand 5 (CCL5; also known as regulated on activation, normal T expressed and secreted, or RANTES) is a member of the CC family of chemokines that specifically attract and activate leukocytes to sites of inflammation. Although CCL5 has been implicated in the processing of pain, its detailed mechanisms of action are still unknown. In this study, we investigated the potential of the Met-RANTES, a selective CCL5 receptor antagonist, via peritoneal administration to modulate the recruitment of inflammatory cells in injured sites and attenuate nociceptive responses in a neuropathic pain model in mice. Nociceptive sensitization, immune cell infiltration, multiple cytokine secretion, and opioid peptide expression in damaged nerves were studied. Our results indicated that Met-RANTES-treated mice had less behavioral hypersensitivity after partial sciatic nerve ligation. Macrophage infiltration, pro-inflammatory cytokine (TNFα, IL-1ß, IL-6, and IFNγ) protein secretion, and enkephalin, ß-endorphin, and dynorphin mRNA expression in damaged nerves following partial sciatic nerve ligation were significantly decreased, and anti-inflammatory cytokine (IL-10) protein was significantly increased in Met-RANTES-treated mice. These results suggest that CCL5 is capable of regulating the microenvironment that controls behavioral hypersensitivity at the level of the peripheral injured site in a murine chronic neuropathic pain model. PERSPECTIVE: The present study identifies the potent pro-inflammatory potential of CCL5 and verifies the possible role of selective CCL5 receptor inhibitor in a murine neuropathic pain model.

Spatial and temporal analysis of nociception-related spinal cord matrix metalloproteinase expression in a murine neuropathic pain model.

BACKGROUND: Although the mammalian central nervous system contains numerous matrix metalloproteinases (MMPs), the significance of each MMP relative to nociception remains obscure. Working from the hypothesis that MMPs may be involved in activity-dependent reorganization during neuronal modulation, we explored the role of each MMP following neuropathological injury by establishing MMP expression profiles in a murine model for neuropathic pain. METHODS: Sciatic nerves of adult male C57BL/6C mice were partially ligated, and their responses to mechanical and radiant heat stimulations were observed at 1, 3, 7, and 14 days. The expression of several nociception-related MMPs (MMP-2, MMP-9, MMP-12, MMP-17, and MMP-24) in the spinal cord was detected by immunohistochemical analysis, Western blotting, and real-time polymerase chain reaction. In addition, the potential of GM6001, a general inhibitor of MMP peritoneal administration, to modulate nociceptive pain responses in a chronic neuropathic pain model in mice was also investigated. RESULTS: MMP-2, 9, 17, and 24, but not MMP-12, were expressed in the murine spinal cord. MMP-9 was constitutively expressed in neurons and microglial cells, immediately upregulated after nerve injury, and returned to baseline levels at day 3. Expression of MMP-2, MMP-17, and MMP-24 gradually increased after nerve injury. Morphologically, MMP-2-positive cells were glial-like cells. MMP-17 and MMP-24 expression was widespread in gray matter, neurons, and microglial cells, and concentrated in the marginal zone of the dorsal horn and in small capillaries. Peritoneal administration of GM6001 resulted in significantly attenuated thermal hyperalgesia and tactile allodynia induced by nerve injury. CONCLUSION: Expression of several nociception-related MMPs was differentially regulated both temporally and spatially following nerve injury. These results suggest that neuronal remodeling requires concerted expression of particular MMPs in specific temporal and spatial patterns, which may be necessary for neuronal plasticity and/or recovery.

The anti-aggregation effects of ondansetron on platelets involve IP3 signaling and MAP kinase pathway, but not 5-HT3-dependent pathway.

Ondansetron is a 5-HT3 receptor antagonist with potent antiemetic, analgesic, and antiphlogistic effects. Literature concerning 5-HT3 antagonists on platelets is limited. In this report we examined the pharmacological effects of ondansetron on human washed platelets. Platelet aggregation induced by thrombin (0.1 U/mL), collagen (2 µg/mL), arachidonic acid (0.5mM), ADP (10 µM), or U46619 (2 µM) was observed. The effects of ondansetron on platelet aggregation and ATP release were investigated at different concentrations. Cytosolic Ca(2+) influx concentration, TXB2, IP3, and the levels of cAMP and cGMP were monitored, and flow cytometric analysis and immunoblotting were performed to investigate downstream signaling components. Our results showed that ondansetron, in a concentration-dependent manner, inhibited agonist-induced platelet aggregation. At 75 µM, ondansetron significantly attenuated intracellular Ca(2+) mobilization, thromboxane B2 formation, and ATP release by human washed platelets activated by thrombin, collagen, or U46619, whereas it only partially attenuated arachidonic acid-driven platelet activation. Administration of ondansetron resulted in attenuated IP3 production in the washed platelets stimulated by thrombin, as determined by reduced IP1 levels, as well as diminished p38 and ERK2 phosphorylation in response to thrombin. No effect of ondansetron on the levels of either cAMP or cGMP in washed platelets was observed. Furthermore, ondansetron-mediated inhibition of platelet aggregation was not impacted by SR 57227A, the 5-HT3 agonist. Thus, rather than involving the 5-HT3-dependent pathway, the negative effect of ondansetron on platelet aggregation is instead manifested through the attenuation of agonist-induced IP3 production and MAPK (p38 and ERK2) phosphorylation that results in suppressed intracellular Ca(2+) mobilization, TXB2 formation, and ATP release.

Absence of C-C motif chemokine ligand 5 in mice leads to decreased local macrophage recruitment and behavioral hypersensitivity in a murine neuropathic pain model.

Accumulated evidence suggests that the C-C motif chemokine ligand 5 (CCL5) modulates migration of inflammatory cells in several pathological conditions. This study tested the hypothesis that lack of CCL5 would modulate the recruitment of inflammatory cells to painful, inflamed sites and could attenuate pain in a murine chronic neuropathic pain model. Nociceptive sensitization, immune cell infiltration, multiple cytokine expression, and opioid peptide expression in damaged nerves were studied in wild-type (CCL5 +/+) and CCL5-deficient (CCL5 -/-) mice after partial sciatic nerve ligation (PSNL). Results indicated that CCL5 -/- mice had less behavioral hypersensitivity after PSNL. Macrophage infiltration and proinflammatory cytokines (tumor necrosis factor-α, interleukin [IL]-1ß, IL-6, and interferon-γ) in damaged nerves following PSNL were significantly decreased in CCL5 -/- mice. Conversely, several antiinflammatory cytokine (IL-4 and IL-10) proteins were significantly increased in CCL5 -/- animals and the expression of enkephalin, ß-endorphin, and dynorphin mRNA was significantly lower than in wild-type control mice. These results represent the first evidence that CCL5 is capable of regulating the pathway that controls hyperalgesia at the level of the peripheral injured site in a murine chronic neuropathic pain model. We demonstrated that lack of CCL5 modulated cell infiltration and the proinflammatory milieu within the injured nerve. Attenuated behavioral hypersensitivity in CCL5 -/- mice observed in the current study could be a result of decreased macrophage infiltration, mobilization, and functional ability at injured sites. Collectively, the present study results suggest that CCL5 receptor antagonists may ultimately provide a novel class of analgesics for therapeutic intervention in chronic neuropathic pain.

Levobupivacaine differentially suppresses platelet aggregation by modulating calcium release in a dose-dependent manner.

OBJECTIVE: Levobupivacaine, an amide local anesthetic widely used in regional anesthesia, is reported in recent studies that it is a potent inhibitor of platelet functions. However, the concentrations of levobupivacaine were limitedly estimated in these reports. Additionally, the mechanisms by which it affects platelet function and blood coagulation is still not entirely known. The purpose of this study was to further investigate its effects on platelet function and the possible signaling mechanisms under various concentrations of levobupivacaine. METHODS: Blood samples collected from healthy volunteers were separated into whole blood, platelet-rich-plasma and washed platelets. The effect of levobupivacaine on platelet aggregation was studied using platelet function analyzer (PFA-100) and platelet aggregometer. Agonist-induced platelet adenosine triphosphate (ATP) release, cytosolic calcium mobilization, thromboxane B2 (TxB2) secretion and platelet P-selectin translocation under various concentrations of levobupivacaine were investigated. RESULTS: Our results indicated that levobupivacaine possessed negative effect on platelet aggregation. The closure times of (PFA-100) were lengthened and the agonist-induced platelet aggregation was significantly attenuated by levobupivacaine even at a low dose (50 µgml(-1)). Pretreatment with levobupivacaine produced significant changes in agonist-induced platelet P-selectin translocation, ATP release, thromboxane A2 (TxA2) production, and calcium mobilization in a dose-dependent manner. The p38 mitogen-activated protein kinases (MAPK), protein kinase C (PKC) δ subtype, cytosolic phospholipase A2 (cPLA2), and protein kinase B (PKB or Akt) were involved in collagen-induced platelet signaling, which would be responsible for antiplatelet effects of levobupivacaine. CONCLUSION: We explored possible targets of levobupivacaine on platelets aggregation signaling mechanisms. Our data revealed that p38 MAPK, PKC δ subtype, cPLA2, and Akt were pathways involved in collagen-induced platelet signaling, which might be responsible for antiplatelet effects of levobupivacaine. Our study did provide direct evidence bolstering the critical mechanisms of levobupivacaine within different contexts. Additionally, levobupivacaine imposed a negative effect on platelet aggregation through multiple signaling pathways.

An iatrogenic complication of radial artery cannulation.

Here, we report a potentially serious iatrogenic complication of arterial cannulation, and discuss the management and prevention of accidental arterial cannula transection. A 73-year-old man suffered from accidental cannula transection after removal of a radial arterial cannula. Three-dimensional computed tomography was used to confirm and locate the retained catheter. Surgical exploration was performed to remove the retained catheter, and the operation was completed smoothly without residual sequelae. Iatrogenic transection of arterial cannula is rarely reported. However, we should always be aware of the possibility of occurrence of this severe complication. We provide some recommendations for its management and ways to prevent its occurrence.

Clinical and molecular aspects of diseases of mitochondrial DNA instability.

Mitochondria within human cells contain vast numbers of mitochondrial DNA (mtDNA), which are small, circular, and double-stranded. The proper functions of mtDNA depend totally on specific proteins that are encoded by the nucleus and then imported into mitochondria. Thus instability of mtDNA can stem from the mtDNA itself, or secondarily from abnormalities in nuclear DNA. In this review, we will first introduce mtDNA, including its characteristics, replication, transcription, translation, and the proteins involved in its metabolism, in particular DNA polymerase gamma (POLG), DNA helicase Twinkle (Twinkle), and mitochondrial transcription factor A (TFAM). Secondly, we will stress the importance of mitochondrial nucleoid structures in the protection and facilitation of mtDNA metabolism, and report on the few known protein components of nucleoid, especially Twinkle, TFAM, and the recently discovered ATAD3. Based on this information, mtDNA instabilities will be categorized in accordance with their molecular etiologies, those that are caused by primary defects of mtDNA, and those by secondary effects from abnormalities in nuclear DNA. The former includes large defects or point mutations of mtDNA. The latter involves the nuclear genes of POLG1, Twinkle, ANT1, TK2, dGK, and TP. With the comprehensive categorization in this review, links are provided between the molecular and clinical aspects of mitochondrial DNA diseases. This report should help medical staff understand the complexity of these diseases and encourage them in further investigations. (