Jay D. Turner

Ca2+ oscillation frequency decoding in cardiac cell hypertrophy: Role of calcineurin/NFAT as Ca2+ signal integrators

The role of Ca2+ signaling in triggering hypertrophy was investigated in neonatal rat cardiomyocytes in vitro. We show that an increase in cell size and sarcomere reorganization were elicited by receptor agonists such as Angiotensin II, aldosterone, and norepinephrine and by a small rise in medium KCl concentration, a treatment devoid of direct effects on receptor functions. All these treatments increased the frequency of spontaneous [Ca2+] transients, caused nuclear translocation of transfected NFAT(GFP), and increased the expression of a NFAT-sensitive reporter gene. There was no increase in Ca2+ spark frequency in the whole cell or in the perinuclear region under these conditions. Hypertrophy and NFAT translocation but not the increased frequency of [Ca2+] transients were inhibited by the calcineurin inhibitor cyclosporine A. Hypertrophy by the different stimuli was insensitive to inhibition of myofilament contraction. We concluded that calcineurin–NFAT can act as integrators of the contractile Ca2+ signal, and that they can decode alterations in the frequency even of rapid Ca2+ oscillations.

Uncoupling Protein-2 Modulates Myocardial Excitation-Contraction Coupling

Rationale: Uncoupling protein (UCP)2 is a mitochondrial inner membrane protein that is expressed in mammalian myocardium under normal conditions and upregulated in pathological states such as heart failure. UCP2 is thought to protect cardiomyocytes against oxidative stress by dissipating the mitochondrial proton gradient and mitochondrial membrane potential (&Dgr;&PSgr;m), thereby reducing mitochondrial reactive oxygen species generation. However, in apparent conflict with its uncoupling role, UCP2 has also been proposed to be essential for mitochondrial Ca2+ uptake, which could have a protective action by stimulating mitochondrial ATP production. Objective: The goal of this study was to better understand the role of myocardial UCP2 by examining the effects of UCP2 on bioenergetics, Ca2+ homeostasis, and excitation–contraction coupling in neonatal cardiomyocytes. Methods and Results: Adenoviral-mediated expression of UCP2 caused a mild depression of &Dgr;&PSgr;m and increased the basal rate of oxygen consumption but did not affect total cellular ATP levels. Mitochondrial Ca2+ uptake was examined in permeabilized cells loaded with the mitochondria-selective Ca2+ probe, rhod-2. UCP2 overexpression markedly inhibited mitochondrial Ca2+ uptake. Pretreatment with the UCP2-specific inhibitor genipin largely reversed the effects UCP2 expression on mitochondrial Ca2+ handling, bioenergetics, and oxygen utilization. Electrically evoked cytosolic Ca2+ transients and spontaneous cytosolic Ca2+ sparks were examined using fluo-based probes and confocal microscopy in line scan mode. UCP2 overexpression significantly prolonged the decay phase of [Ca2+]c transients in electrically paced cells, increased [Ca2+]c spark activity and increased the probability that Ca2+ sparks propagated into Ca2+ waves. This dysregulation results from a loss of the ability of mitochondria to suppress local Ca2+–induced Ca2+ release activity of the sarcoplasmic reticulum. Conclusion: Increases in UCP2 expression that lower &Dgr;&PSgr;m and contribute to protection against oxidative stress, also have deleterious effects on beat-to-beat [Ca2+]c handling and excitation-contraction coupling, which may contribute to the progression of heart disease.

Radiographic outcomes of anterior column realignment for adult sagittal plane deformity: a multicenter analysis.

PurposeAnterior column reconstruction (ACR) is a minimally invasive technique for the treatment of sagittal plane deformity. ACR uses a lateral transpsoas approach with ALL release and the application of an interbody device to achieve correction. Here, we present 1-year radiographic results from a multicenter study of adult spinal deformity (ASD) patients.MethodsA multicenter database was queried from 2005 to 2013 for ASD patients treated with ACR. Demographics, surgical data, and radiographic measurements were collected and retrospectively analyzed. Radiographic time points included preoperative (pre-op), postoperative (post-op; first visit prior to 3xa0months), and last follow-up (last FU; minimum of 1xa0year). Sagittal radiographic measurements included regional lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), T1 spinopelvic inclination (T1SPi), and segmental lordosis (disc angle).ResultsMean patient age was 67.4xa0years (range 46.5–80.0) and 11 patients (32.4xa0%) were male. Twenty patients (58.8xa0%) had previous lumbar surgery. All patients had a minimal of one-level ACR with ALL release (mean 1.7; range 1–4). Mean number of lateral interbody fusion (LLIF) levels without ALL release per patient was 0.7 (range 0–3). Thirty-three patients (97.1xa0%) received supplemental posterior fixation and 1 patient (2.9xa0%) had lateral fixation only. In 26 patients (76.5xa0%), supplemental posterior fixation was performed using an open approach, and 7 patients (20.6xa0%) were treated with percutaneous placement. Mean of number of levels fused was 7.1 (range 2–16). There was a significant improvement in LL (pxa0<xa00.001), PI-LL mismatch (pxa0<xa00.001), and PT (pxa0=xa00.03) from pre-op to post-op, and pre-op to last FU. There was no change in T1SPi, SS, or PI. Segmental lordosis improved at ACR levels from mean of −2.2° pre-op to −16.0° post-op (pxa0<xa00.01) and −16.3° at last FU (pxa0<xa00.001). The addition of posterior column osteotomy increased the change in segmental lordosis with ACR by 72.7xa0% (pxa0<xa00.001). LLIF without ALL release led to significant improvement in segmental lordosis from pre-op (−2.4°) to post-op (−7.1°; pxa0<xa00.01) but not from pre-op to last FU (−5.7°; pxa0=xa00.06).ConclusionACR successfully restores lumbar lordosis in ASD patients with sagittal imbalance. ACR results in greater segmental correction than is achieved with LLIF alone. Supplementing with posterior osteotomies allows for even greater correction. The ability to achieve the desired radiographic goals is expected to improve as technical nuances are refined and patient selection is optimized.

Erythropoietin for the Treatment of Subarachnoid Hemorrhage: A Review

OBJECTIVEnSubarachnoid hemorrhage (SAH) has a worldwide incidence of approximately 10.5 cases per 100,000 person-years and constitutes 3% of all strokes. Erythropoietin (EPO) has recently been proposed for the treatment of a variety of brain diseases, including SAH, because of its neuroprotective effects. Hence, the current evidence in the published literature was reviewed to determine the potential utility of EPO in the treatment of SAH.nnnMETHODSnA careful retrospective review of the literature was performed to determine the potential benefit of employing EPO in the treatment of SAH and its sequelae.nnnRESULTSnCareful literature review revelaed that the use of EPO may not necessarily reduce the incidence of vasospasm after SAH, but it may reduce the severity and its eventual outcome.nnnCONCLUSIONnGiven the recent trial results, a dose-escalation study and subsequent randomized trial should be considered.

Calcineurin activation by slow calcium release from intracellular stores suppresses protein kinase C regulation of L-type calcium channels in L6 cells

L-type Ca(2+) channel activity was assayed in L6 cells as the rate of nifedipine-sensitive Ba(2+) influx in a depolarizing medium. In the absence of extracellular Ca(2+), activation of protein kinase C (PKC) with phorbol-12-myristate-13-acetate (PMA) or thymeleatoxin (TMX) inhibited Ba(2+) influx by 38%. Thapsigargin (Tg), a selective inhibitor of the Ca(2+)-ATPase in the sarcoplasmic reticulum, evoked a rise in the cytosolic Ca(2+) concentration ([Ca(2+)](i)) in a Ca(2+)-free medium from 30 to approximately 80 nM. This [Ca(2+)](i) increase declined slowly, giving rise to a modest elevation of [Ca(2+)](i) that persisted for >5 min. The inhibitory effects of PMA and TMX on channel activity were abolished when tested in Tg-treated cells in a Ca(2+)-free medium. However, when the Ca(2+) ionophore, ionomycin, was applied with Tg, PMA and TMX retained their inhibitory effect on L-type Ca(2+) channel activity, suggesting that a lower amplitude and prolonged release of Ca(2+) stores is necessary for abrogating PKC-mediated inhibition of LCC. Cyclosporin A (5 microM) and ascomycin (5 microM), inhibitors of the Ca(2+)/calmodulin-dependent protein phosphatase, calcineurin, fully restored the inhibitory effect of PMA and TMX on channel activity. Addition of 1mM CaCl(2) to the Tg-treated cells increased [Ca(2+)](i) to approximately 165 nM and also restored the inhibitory effects of PMA and TMX. These results indicate that a small, relatively prolonged [Ca(2+)](i) increase elicited by passive depletion of internal Ca(2+) stores led to activation of calcineurin, giving rise to an increase in protein phosphatase activity that counteracted the inhibitory effects of PKC on channel activity. A larger increase in [Ca(2+)](i) via store-dependent Ca(2+) entry enhanced the activity of PKC sufficiently to overcome the protein phosphatase activity of calcineurin. This study is the first to demonstrate that the regulation of L-type Ca(2+) channels in a myocyte model involves a balance between the differential Ca(2+) sensitivities and opposing actions of PKC and calcineurin.

FoxM1 is Vital in the Wnt/β-catenin Signaling Pathogenesis of Gliomas

nteraction benesis and raise The Wnt/ -catenin signaling pathway (8) is a key re way in stem cells and has been implicated in vario cies such as colorectal cancer and glioma (6, 7, 10 subunit of the cadherin protein complex, mediates scriptional response. When maintained in its const phorylated state, -catenin is destabilized and r cytosolic space (2). With Wnt-induced depho -catenin can be transported to the nucleus where by DNA bound transcription factors such as T-ce and lymphoid enhancer-binding factor (LEF) to tions of target genes (9). Similarly, forkhead bo (FoxM1), a protein involved in cell cycle progressio family of human proto-oncogenes (5), is overexpr human cancers, including intestinal (11) and glial t In a recent issue of Cancer Cell, an intersection betw critical regulatory pathways is elucidated (12). The M.D. Anderson Cancer Center, describe the relati FoxM1, -catenin, TCF4, and Wnt signaling as part cascade essential to gliomagenesis (12). Specifically, pates in -catenin nuclear localization and also asse scriptional activation complex in the Wnt signaling Using both Western blot analysis (Figure 1E) and seq fluorescence imaging, the authors demonstrate that of Wnt3a leads to -catenin nuclear accumulation i pendent fashion. Additionally, overexpression of Fox increased amounts of nuclear -catenin with simul tions in cytoplasmic -catenin, further supporting a in the translocation of -catenin from the cytosol t Nuclear translocation of -catenin was eliminated w FoxM1 in FoxM1 immortalized stem cells. Interestingly

Anterior Column Realignment has Similar Results to Pedicle Subtraction Osteotomy in Treating Adults with Sagittal Plane Deformity

OBJECTIVEnAnterior column realignment (ACR) is a minimally invasive surgical technique used for the correction of adult sagittal plane deformity. ACR is performed via a minimally invasive lateral transpsoas approach with anterior longitudinal ligament release and hyperlordotic cage placement. The objective of this study was to compare radiographic outcomes and complications in patients treated by ACR or Pedicle subtraction osteotomy (PSO).nnnMETHODSnPatients who underwent ACR were matched with patients from a retrospective PSO dataset, by pelvic incidence, lumbar lordosis, and thoracic kyphosis. Inclusion criteria included pelvic incidence and lumbar lordosis mismatch > 10°, pelvic tilt > 25°, and/or C7 sagittal vertical axis >5 cm, and minimum 1-year follow-up.nnnRESULTSnAll (nxa0= 17) patients who underwent ACR underwent second-stage open posterior instrumented fusion. There were no differences in baseline demographic or radiographic parameters. Both groups were found to have significant improvement from preoperative to final follow-up for lumbar lordosis, T1 spinopelvic inclination, and T1 pelvic angle. Pelvic tilt did not improve with PSO (31° to 28°) at final follow-up but did improve in ACR group (34° to 25°). No differences were identified at 3-month or final follow-up for lumbar lordosis (51° vs. 47°), pelvic tilt (25° vs. 28°), and T1 pelvic angle (23° vs. 24°). The group undergoing PSO achieved greater T1 spinopelvic inclination correction (8° vs. 1.9°). Patients who underwent ACR had significantly less estimated blood loss than patients who underwent PSO (1.6 vs. 3.6 L, respectively), but no difference in the overall major complication rates was found (35.3% vs. 41.2%, respectively).nnnCONCLUSIONSnACR achieved similar radiographic results as PSO in a matched cohort with significantly less estimated blood loss and similar overall complication rate.

Computed tomographic angiography versus digital subtraction angiography for the postoperative detection of residual aneurysms: a single-institution series and meta-analysis

Background Computed tomographic angiography (CTA) has recently emerged as a non-invasive alternative to digital subtraction angiography (DSA) for the detection of residual cerebral aneurysms (RA). Objective To compare the diagnostic accuracy of CTA with the current ‘gold standard’, DSA, in the postoperative detection of RA. Methods Patient data from this single institution were prospectively gathered, and imaging results retrospectively blinded and analyzed. Between 2001 and 2005 eligible patients received microsurgical repair of cerebral aneurysms and were evaluated postoperatively by DSA and CTA. These single-institutional data were compiled with qualified studies published from 1997 to 2009, and a meta-analysis was performed. Results This institutional series reports sensitivity, specificity, positive (PPV) and negative predictive values (NPV) of 100%. Eleven studies met the inclusion criteria for the meta-analysis. A total of 427 patients with 513 aneurysms were included, with 61 RA detected by DSA and 40 detected by CTA. Unweighted analysis resulted in pooled sensitivity of 73.8%, specificity of 96.3%, PPV of 91.0% and NPV of 86.1%. Stratified analysis of studies using 16-slice CTA versus 2D DSA reported pooled sensitivity of 92.6%, specificity of 99.3%, PPV of 95.8%, and NPV of 97.8%. Conclusions This meta-analysis supports CTA as an acceptable modality for postoperative detection of RA, although DSA remains the gold standard. By implementing multidetector CTA technology in experienced centers, the sensitivity and specificity of CTA may approach that of traditional DSA for detecting RA. As a cost-effective, non-invasive modality, CTA is a promising alternative to DSA for initial and long-term evaluation of RA.

A Critical Analysis of Sagittal Plane Deformity Correction With Minimally Invasive Adult Spinal Deformity Surgery: A 2-Year Follow-Up Study

INTRODUCTIONnSagittal plane realignment is important to achieve desirable clinical outcomes after adult spinal deformity (ASD) surgery. This study evaluates the impact of minimally invasive (MIS) techniques on sagittal plane alignment and clinical outcomes in ASD patients.nnnMETHODSnA retrospective, multi-center review of ASD patients (age ≥18 years, and with one of the following: coronal Cobb ≥20°, sagittal vertical axis [SVA] >5 cm, and/or pelvic tilt >25°), MIS surgery, and four or more levels instrumented. Patients were stratified by baseline SRS-Schwab global alignment modifier (GAM) into three groups: 0 (SVA <4 cm), + (SVA 4-9.5 cm), or ++ (SVA >9.5 cm). Radiographic and clinical outcomes measures were analyzed with a minimum of 2-year follow-up.nnnRESULTSnA total of 96 ASD patients were identified, and 63 met the studys inclusion criteria of circumferential MIS or posterior MIS only, with four or more levels instrumented (n: Group 0 = 37, Group + = 15, and Group ++ = 11). Group 0 was younger than ++ (56.8 vs. 69.6 years), with a higher proportion of females than Group + or ++ (83.8% vs. 66.7% and 54.5%, respectively). Baseline HRQoL was similar. Postoperatively, Groups 0 and + had improved Oswestry Disability Index (ODI) and numeric rating scale (NRS) back and leg scores. Group ++ only had improvement in NRS scores. At the latest follow-up, Groups 0 and ++ had similar sagittal measurements except for PT (21.6 vs. 23.6, p = .009). The + group had improvement in PI-LL (24.2 to 17; p = .015) and LL (30.9 to 38.3; p = .013). Eight of 27 (21.6%) Group 0 patients deteriorated (4 to Group +, 4 to Group ++). Three of 15 (20.0%) Group + patients deteriorated to Group ++, and 3 improved to Group 0. Six of 11 (54.5%) Group ++ patients improved (3 to Group + and 3 to Group 0).nnnCONCLUSIONSnMIS techniques successfully stabilized ASD patients with Group 0 and + deformities and improved HRQoL. This study suggests that severe sagittal imbalance is not adequately treated with MIS approaches.INTRODUCTIONnSagittal plane realignment is important to achieve desirable clinical outcomes after adult spinal deformity (ASD) surgery. This study evaluates the impact of minimally invasive (MIS) techniques on sagittal plane alignment and clinical outcomes in ASD patients.nnnMETHODSnA retrospective, multi-center review of ASD patients (age ⩾18 years, and with one of the following: coronal Cobb ⩾20°, sagittal vertical axis [SVA] >5 cm, and/or pelvic tilt >25°), MIS surgery, and four or more levels instrumented. Patients were stratified by baseline SRS-Schwab global alignment modifier (GAM) into three groups: 0 (SVA <4 cm), + (SVA 4-9.5 cm), or ++ (SVA >9.5 cm). Radiographic and clinical outcomes measures were analyzed with a minimum of 2-year follow-up.nnnRESULTSnA total of 96 ASD patients were identified, and 63 met the studys inclusion criteria of circumferential MIS or posterior MIS only, with four or more levels instrumented (n: Group 0 = 37, Group + = 15, and Group ++ = 11). Group 0 was younger than ++ (56.8 vs. 69.6 years), with a higher proportion of females than Group + or ++ (83.8% vs. 66.7% and 54.5%, respectively). Baseline HRQoL was similar. Postoperatively, Groups 0 and + had improved Oswestry Disability Index (ODI) and numeric rating scale (NRS) back and leg scores. Group ++ only had improvement in NRS scores. At the latest follow-up, Groups 0 and ++ had similar sagittal measurements except for PT (21.6 vs. 23.6, p =.009). The + group had improvement in PI-LL (24.2 to 17; p =.015) and LL (30.9 to 38.3; p =.013). Eight of 27 (21.6%) Group 0 patients deteriorated (4 to Group +, 4 to Group ++). Three of 15 (20.0%) Group + patients deteriorated to Group ++, and 3 improved to Group 0. Six of 11 (54.5%) Group ++ patients improved (3 to Group + and 3 to Group 0).nnnCONCLUSIONSnMIS techniques successfully stabilized ASD patients with Group 0 and + deformities and improved HRQoL. This study suggests that severe sagittal imbalance is not adequately treated with MIS approaches.

Fluctuations in Spinal Cord Perfusion During Adult Spinal Deformity Correction Identify Neurologic Changes: Proof of Concept

INTRODUCTIONnAdult spinal deformity (ASD) surgery carries the risk of spinal cord injury. Spinal cord ischemia is often implicated in the pathogenesis but has not been directly investigated. Here we present our index case as a proof of concept for a study evaluating the role of spinal cord perfusion (SCP) changes in ASD correction.nnnMETHODSnASD surgery was performed in the usual fashion with the addition of 1) SCP monitoring, using laser Doppler probe fixated to the dura at the level of the pedicle subtraction osteotomy (PSO) and 2) intrathecal pressure monitoring, using a lumbar drain. Somatosensory evoked potential (SSEP) and motor evoked potential (MEP) were monitored throughout the case.nnnRESULTSnAn 84-year-old male with kyphoscoliosis and progressive myelopathy causing diminished motor and sensory function was treated with T4 PSO and long segment reconstruction. At baseline, SSEP signals were detectable in all 4 extremities, MEP signals were present in the right foot only, intrathecal pressure was 4 mm Hg, and mean SCP was 21.2 perfusion units. The osteotomy was performed and reduced in 2 steps. After the first step of reduction, MEP signals appeared in the left leg and increased in amplitude in the right leg, and SCP simultaneously increased to 205.6. Further reduction led to MEP signal loss in both legs and decrease in SCP to 39.2. With partial reversal of the reduction, MEP signals returned in both legs and SCP improved to 76.0. Final reduction maneuvers were then performed in a delayed fashion before closure, with stable MEP signals and a final SCP of 42.9. SSEP signals, vital signs, and intrathecal pressure were stable throughout the case. Postoperatively the patient was neurologically stable.nnnCONCLUSIONSnThe present case provides the first direct evidence that fluctuations in SCP may contribute to neurologic changes during ASD surgery. Further investigation is under way to further elucidate the underlying mechanisms, with the ultimate goal of developing targeted strategies for spinal cord protection during these high-risk cases.