Stenting for Venous Sinus Stenosis in Patients With Idiopathic Intracranial Hypertension: An Updated Systematic Review and Meta-Analysis of the Literature.

BACKGROUND AND OBJECTIVES: Although venous sinus stenting (VSS) improves cerebrospinal fluid reabsorption and decreases intracranial pressure in patients with idiopathic intracranial hypertension (IIH), the underlying pathophysiology of IIH is not well understood. We present a review and meta-analysis of the literature on VSS for IIH treatment, focusing on the rates of restenosis and symptom recurrence. METHODS: We performed a systematic review of PubMed and Embase databases between January 1, 2011, and December 31, 2021. Articles including ≥5 patients with IIH and venous sinus stenosis treated with VSS and post-treatment rates of restenosis (de novo stenosis at a different anatomic location along the dural sinuses or restenosis within or adjacent to the stent) were selected. Demographic, procedural, and outcomes data were collected and analyzed. Mean values for variables collected were pooled, and a mean value was calculated with a 95% CI. RESULTS: Twenty-four articles were included, comprising 694 patients and 781 VSS cases. The mean age was 33.9 (CI, 31.5-36.2) years. The mean body mass index was 35.3 (CI, 32.9-37.7) kg/m 2 . Before VSS, 98.8% (CI, 96.8%-100.0%) of patients experienced headaches, 87.7% (CI, 80.6%-95.5%) had visual acuity issues, 78.7% (CI, 69.9%-88.5%) had papilledema, 58.3% (CI, 46.0%-73.9%) had tinnitus, and 98.8% (96.4%-100.0%) had symptoms refractory to previous therapies. After VSS, 77.7% (CI, 71.1%-84.95%) experienced symptom improvement and 22.3% (CI, 15.1%-29.0%) had persistent or worsened symptoms. Pooled restenosis rate was 17.7% (CI, 14.9%-20.9%). CONCLUSION: VSS is effective in alleviating IIH signs and symptoms, but the associated high rates of restenosis and persistent symptoms highlight the need for further investigation of this procedure and other adjunctive treatments for IIH.

NKG2C+ NK Cells for Immunotherapy of Glioblastoma Multiforme.

In glioblastoma, non-classical human leucocyte antigen E (HLA-E) and HLA-G are frequently overexpressed. HLA-E loaded with peptides derived from HLA class I and from HLA-G contributes to inhibition of natural killer (NK) cells with expression of the inhibitory receptor CD94/NKG2A. We investigated whether NK cells expressing the activating CD94/NKG2C receptor counterpart were able to exert anti-glioma effects. NKG2C+ subsets were preferentially expanded by a feeder cell line engineered to express an artificial disulfide-stabilized trimeric HLA-E ligand (HLA-E*spG). NK cells expanded by a feeder cell line, which facilitates outgrowth of conventional NKG2A+, and fresh NK cells, were included for comparison. Expansion via the HLA-E*spG feeder cells selectively increased the fraction of NKG2C+ NK cells, which displayed a higher frequency of KIR2DL2/L3/S2 and CD16 when compared to expanded NKG2A+ NK cells. NKG2C+ NK cells exhibited increased cytotoxicity against K562 and KIR:HLA-matched and -mismatched primary glioblastoma multiforme (GBM) cells when compared to NKG2A+ NK cells and corresponding fresh NK cells. Cytotoxic responses of NKG2C+ NK cells were even more pronounced when utilizing target cells engineered with HLA-E*spG. These findings support the notion that NKG2C+ NK cells have potential therapeutic value for treating gliomas.

Cavß3 Regulates Ca2+ Signaling and Insulin Expression in Pancreatic ß-Cells in a Cell-Autonomous Manner.

Voltage-gated Ca2+ (Cav) channels consist of a pore-forming Cavα1 subunit and auxiliary Cavα2-δ and Cavß subunits. In fibroblasts, Cavß3, independent of its role as a Cav subunit, reduces the sensitivity to low concentrations of inositol-1,4,5-trisphosphate (IP3). Similarly, Cavß3 could affect cytosolic calcium concentration ([Ca2 +]) in pancreatic ß-cells. In this study, we deleted the Cavß3-encoding gene Cacnb3 in insulin-secreting rat ß-(Ins-1) cells using CRISPR/Cas9. These cells were used as controls to investigate the role of Cavß3 on Ca2+ signaling, glucose-induced insulin secretion (GIIS), Cav channel activity, and gene expression in wild-type cells in which Cavß3 and the IP3 receptor were coimmunoprecipitated. Transcript and protein profiling revealed significantly increased levels of insulin transcription factor Mafa, CaMKIV, proprotein convertase subtilisin/kexin type-1, and nitric oxide synthase-1 in Cavß3-knockout cells. In the absence of Cavß3, Cav currents were not altered. In contrast, CREB activity, the amount of MAFA protein and GIIS, the extent of IP3-dependent Ca2+ release and the frequency of Ca2+ oscillations were increased. These processes were decreased by the Cavß3 protein in a concentration-dependent manner. Our study shows that Cavß3 interacts with the IP3 receptor in isolated ß-cells, controls IP3-dependent Ca2+-signaling independently of Cav channel functions, and thereby regulates insulin expression and its glucose-dependent release in a cell-autonomous manner.

Increased Pericardial Adipose Tissue in Smokers.

BACKGROUND: Pericardial adipose tissue (PAT), a visceral fat depot directly located to the heart, is associated with atherosclerotic and inflammatory processes. The extent of PAT is related to the prevalence of coronary heart disease and might be used for cardiovascular risk prediction. This study aimed to determine the effect of smoking on the extent of PAT. METHODS: We retrospectively examined 1217 asymptomatic patients (490 females, age 58.3 ± 8.3 years, smoker n = 573, non-smoker n = 644) with a multislice CT scanner and determined the PAT volume. Coronary risk factors were determined at inclusion, and a multivariate analysis was performed to evaluate the influence of smoking on PAT independent from accompanying risk factors. RESULTS: The mean PAT volume was 215 ± 107 mL in all patients. The PAT volume in smokers was significantly higher compared to PAT volume in non-smokers (231 ± 104 mL vs. 201 ± 99 mL, p = 0.03). Patients without cardiovascular risk factors showed a significantly lower PAT volume (153 ± 155 mL, p < 0.05) compared to patients with more than 1 risk factor. Odds ratio was 2.92 [2.31, 3.61; p < 0.001] for elevated PAT in smokers. CONCLUSION: PAT as an individual marker of atherosclerotic activity and inflammatory burden was elevated in smokers. The finding was independent from metabolic risk factors and might therefore illustrate the increased inflammatory activity in smokers in comparison to non-smokers.

Assessment of Rod Material Types in Spine Surgery Outcomes: A Systematic Review.

BACKGROUND: Lumbar spine fusion surgery is traditionally performed with rigid fixation. Because the rigidity is often supraphysiologic, semirigid rods were developed. To the best of our knowledge, a comprehensive evaluation of rod material type on surgical outcomes has yet to be conducted. METHODS: A systematic review based on PRISMA guidelines was conducted across 3 electronic databases. After examination for inclusion and exclusion criteria, data were extracted from the studies. RESULTS: Seventeen studies, including 1399 patients, were included in this review. The mean rigid rod fusion rate is 92.2% and 95.5% for semirigid rods (P = 0.129). The mean improvement in back pain was 60.6% in rigid rods and 71.6% in semirigid rods. The improvement in leg pain was 81.9% and 77.2%, respectively. There were no differences in visual analog scale back pain score (P = 0.098), visual analog scale leg pain score (P = 0.136), or in functional improvement between rigid and semirigid rods (P = 0.143). There was no difference (P = 0.209) in the reoperation rate between rigid rods (13.1%) and semirigid rods (6.5%). There was a comparable incidence of adjacent segment disease (3%), screw fracture (1.7%), and wound infection (1.9%) between rod material types. CONCLUSIONS: There is a moderate level of evidence supporting that surgical intervention results in high fusion rates regardless of rod material type. Surgical intervention improves back pain, leg pain, and function, with neither material type showing clear superiority. There are comparable rates of reoperation, development of adjacent segment disease, development of mechanical complications, and incidence of infection in both rigid and semirigid rods. Further studies regarding rod material type are warranted.

Is computed tomography cystography indicated in children with pelvic fractures?

PURPOSE: Pelvic fracture evaluation with abdominopelvic computed tomography (CT) and formal CT cystography for rule out of urine bladder injury have been commonly employed in pediatric trauma patients. The additional delayed imaging required to obtain optimal CT cystography is, however, associated with increased doses of ionizing radiation to pelvic organs and represent a significant risk in the pediatric population for future carcinogenic risk. We hypothesized that avoidance of routine CT cystography among pediatric pelvic fracture victims would not result in an appreciable rate of missed bladder injuries and would aid in mitigating the radiation exposure risk associated with these additional images. METHODS: A retrospective cohort study involving blunt trauma pelvic fractures among pediatric trauma patients (age<14) between the years 1997 and 2016 was conducted utilizing the Israeli National Trauma Registry. Statistical analysis was performed using SAS statistical software version 9.4 via the tests of Chi-square test and two-sided Fisher's exact test. A p value of less than 0.05 was considered statistically significant. RESULTS: A total of 1072 children were identified from the registry for inclusion. Mean age of patients was 7.7 years (range 0-14) and 713 (66.5%) were male. Overall mortality in this population was 4.1% (44/1072). Only 2.1% (23) of pediatric patients with pelvic fractures had bladder injury identified, with just 9 children having intraperitoneal bladder rupture (0.8% of all the patients). CONCLUSION: The vast majority of blunt pediatric trauma victims with pelvic fractures do not have urine bladder injuries. Based on our study results we do not recommend the routine utilization of CT cystography in this unique population.

Predictive value of coronary calcifications for future cardiac events in asymptomatic patients: underestimation of risk in asymptomatic smokers.

Coronary calcification (CAC) is an established marker for coronary atherosclerosis and has a highly specific predictive value for cardiovascular events. This study aimed to determine the predictive value in the specific group of asymptomatic smokers in comparison to non-smokers. We included 1432 asymptomatic individuals (575 women, 857 men, age 59.2 ± 7.7 years.) in this study. Coronary calcification was calculated by multi-slice computed tomography following a standardized protocol including calcium score (CS). Coronary risk factors were determined at inclusion. After mean observation time of 76.3 ± 8.5 months the patients were contacted and evaluated for cardiovascular events (myocardial infarction, cardiac death and revascularisation). Mean CS was 231 ± 175 in smokers and 239 ± 188 in non-smokers. Cardiovascular events were found in 14.9% of our patients and there were significantly more events in smokers (119 events, 8.3%) than in non-smokers (94 events, 6.6%, p = 0.001). CS > 400 showed a hazard ratio for future cardiac events of 5.1 (95% CI 4.3-7.6) in smokers and 4.4 (95% CI 3.4-6.2) in non-smokers, p = 0.01. Also in smokers determination of CAC is a valuable predictor of future cardiovascular events. In our study smokers showed throughout all score groups a significantly higher risk compared to non-smokers with equal CS. Therefore, CS may underestimate the risk for future cardiac events in smokers compared to non-smokers.

Abdominal stab wound injury in children: Do we need a different approach?

BACKGROUND: Penetrating stab wounds in children are relatively rare and no clear recommendations for the optimal evaluation have been devised. An acceptable traditional approach to the patient with an abdominal stab wound who does not require urgent surgery is selective nonoperative management and serial exams. The use of routine computed tomography remains an actively utilized investigation for these patients at many institutions. PURPOSE: We hypothesize that the approach to pediatric stab wound victims should be distinctly different than that of adult counterparts in order to minimize radiation exposure. METHODS: A retrospective cohort study involving abdominal stab wounds among pediatric trauma patients (age < 14) compared with adults between the years 1997 and 2016 was conducted utilizing the Israeli National Trauma Registry. RESULTS: A total of 92 children and 4444 adults were identified from the registry for inclusion. Among the children 20 (21.7%) patients had intraabdominal injury compared to 1730 (38.9%) among adult counterparts. Four children were hemodynamically unstable, two of them were referred directly to operating room and two others were treated without surgery. Among the remaining 88 children there was no observed mortality. CONCLUSIONS: The majority of pediatric stab wounds trauma victims have minor abdominal injuries. We do not recommend the routine utilization of abdominal CT scan in the evaluation of abdominal stab wounds. Observation with serial exams and minimization of radiation exposure from CT are warranted in this unique population. TYPE OF STUDY: Retrospective comparative study. LEVEL OF EVIDENCE: 3.

Baboon induced pluripotent stem cell generation by piggyBac transposition of reprogramming factors.

Clinical application of regenerative therapies using embryonic or induced pluripotent stem cells is within reach. Progress made during recent years has encouraged researchers to address remaining open questions in order to finally translate experimental cell replacement therapies into application in patients. To achieve this, studies in translationally relevant animal models are required to make the final step to the clinic. In this context, the baboon (Papio anubis) may represent a valuable nonhuman primate (NHP) model to test cell replacement therapies because of its close evolutionary relationship to humans and its large body size. In this study, we describe the reprogramming of adult baboon skin fibroblasts using the piggyBac transposon system. Via transposon-mediated overexpression of six reprogramming factors, we generated five baboon induced pluripotent stem cell (iPSC) lines. The iPSC lines were characterized with respect to alkaline phosphatase activity, pluripotency factor expression analysis, teratoma formation potential, and karyotype. Furthermore, after initial cocultivation with mouse embryonic fibroblasts, we were able to adapt iPSC lines to feeder-free conditions. In conclusion, we established a robust and efficient protocol for iPSC generation from adult baboon fibroblasts.

The Role of Gait Analysis in the Evaluation of Patients with Cervical Myelopathy: A Literature Review Study.

BACKGROUND: Gait analysis represents one of the newest methodologies used in the clinical evaluation of patients with cervical myelopathy (CM). OBJECTIVE: To describe the role of gait analysis in the clinical evaluation of patients with CM, as well as its potential role in the evaluation of the functional outcome of any surgical intervention. METHODS: A literature review was performed in the PubMed, OVID, and Google Scholar medical databases, from January 1995 to August 2016, using the terms "analysis," "anterior," "cervical myelopathy," "gait," "posterior," and "surgery." Clinical series comparing the gait patterns of patients with CM with healthy controls, as well as series evaluating gait and walk changes before and after surgical decompression, were reviewed. Case studies were excluded. RESULTS: Nine prospective and 3 retrospective studies were found. Most of the retrieved studies showed the presence of characteristic, abnormal gait patterns among patients with CM, consisting of decreased gait speed, cadence, step length, stride length, and single-limb support time. In addition, patients with CM routinely present increased step and stride time, double-limb support time, and step width, and they have altered knee and ankle joint range of motion, compared with healthy controls. Moreover, gait and walk analysis may provide accurate functional assessment of the functional outcome of patients with CM undergoing surgical decompression. CONCLUSIONS: Gait analysis may well be a valuable and objective tool along with other parameters in the evaluation of functionality in patients with CM, as well as in the assessment of the outcome of any surgical intervention in these patients.

Glasgow Coma Scale Score in Survivors of Explosion With Possible Traumatic Brain Injury in Need of Neurosurgical Intervention.

Importance: Head injury following explosions is common. Rapid identification of patients with severe traumatic brain injury (TBI) in need of neurosurgical intervention is complicated in a situation where multiple casualties are admitted following an explosion. Objective: To evaluate whether Glasgow Coma Scale (GCS) score or the Simplified Motor Score at presentation would identify patients with severe TBI in need of neurosurgical intervention. Design, Setting, and Participants: Analysis of clinical data recorded in the Israel National Trauma Registry of 1081 patients treated following terrorist bombings in the civilian setting between 1998 and 2005. Primary analysis of the data was conducted in 2009, and analysis was completed in 2015. Main Outcomes and Measures: Proportion of patients with TBI in need of neurosurgical intervention per GCS score or Simplified Motor Score. Results: Of 1081 patients (median age, 29 years [range, 0-90 years]; 38.9% women), 198 (18.3%) were diagnosed as having TBI (48 mild and 150 severe). Severe TBI was diagnosed in 48 of 877 patients (5%) with a GCS score of 15 and in 99 of 171 patients (58%) with GCS scores of 3 to 14 (P < .001). In 65 patients with abnormal GCS (38%), no head injury was recorded. Nine of 877 patients (1%) with a GCS score of 15 were in need of a neurosurgical operation, and fewer than 51 of the 171 patients (30%) with GCS scores of 3 to 14 had a neurosurgical operation (P < .001). No difference was found between the proportion of patients in need of neurosurgery with GCS scores of 3 to 8 and those with GCS scores of 9 to 14 (30% vs 27%; P = .83). When the Simplified Motor Score and GCS were compared with respect to their ability to identify patients in need of neurosurgical interventions, no difference was found between the 2 scores. Conclusions and Relevance: Following an explosion in the civilian setting, 65 patients (38%) with GCS scores of 3 to 14 did not experience severe TBI. The proportion of patients with severe TBI and severe TBI in need of a neurosurgical intervention were similar in patients presenting with GCS scores of 3 to 8 and GCS scores of 9 to 14. In this study, GCS and Simplified Motor Score did not help identify patients with severe TBI in need of a neurosurgical intervention.

Transient receptor potential A1 channels regulate epithelial cell barriers formed by MDCK cells.

Transient receptor potential A1 channels are well-known as chemosensors in neuronal cells. However, recent studies also point to non-neuronal functions in epithelia. Here, we show that TRPA1 channels are expressed in epithelial MDCK II cells and contribute to Ca(2+) influx and whole-cell currents after stimulation with AITC. Stimulation of TRPA1 channels induced an immediate reduction of the transepithelial resistance of MDCK II cell layers that was blocked by the TRPA1 antagonist HC-030031. The present data provide strong evidence for a new role of TRPA1 channels in regulating the tightness of epithelial cell barriers.

Characterization of post-translational modifications in full-length human BMP-1 confirms the presence of a rare vicinal disulfide linkage in the catalytic domain and highlights novel features of the EGF domain.

UNLABELLED: Bone morphogenetic protein 1 (BMP-1) is an essential metalloproteinase to trigger extracellular matrix assembly and organogenesis. Previous structural studies on the refolded catalytic domain of BMP-1 produced in E. coli have suggested the existence of a rare vicinal disulfide linkage near the active site. To confirm that this was not an artifact of the refolding procedure, the full-length human BMP-1 produced in mammalian cells was investigated via sequence-dependent enzyme cleavage under native conditions followed by high mass accuracy and high resolution LC-MS/MS analysis to interrogate the post-translational modifications. Ten disulfide linkages of BMP-1, including the vicinal disulfide linkage C185-C186 could be unambiguously identified. Further, around 50% of this vicinal disulfide bond was found to be modified by N-ethylmaleimide (NEM), a cysteine protease inhibitor supplied when the BMP-1-containing medium was collected, suggesting that this bond was highly unstable. In the absence of NEM, BMP-1 has a higher tendency to form aggregates, but after aggregate removal, C185 and C186 are almost quantitatively engaged in the vicinal disulfide bond and BMP-1 activity remains unchanged. In addition, three consensus N-glycosylation sites at N142, N363, and N599 could be identified together with a previously unknown O-glycosylation site and an Asn-hydroxylation. SIGNIFICANCE: An in-depth characterization of post-translational modifications of the full-length human BMP-1 produced in mammalian cells by MS was performed. A rare vicinal disulfide bond in the catalytic domain could be confirmed for the first time by mass spectrometry along with nine other proposed disulfide linkages of mature BMP-1. This vicinal disulfide bond can transiently open to form covalent adducts with the cysteine protease inhibitor (NEM) supplied in cell medium during protein harvesting. Further, we report a previously unknown O-glycosylation site and Asn-hydroxylation site, indicating a novel feature of BMP-1 in the EGF domain. The study clearly outlines the benefit of in-depth characterization of overexpressed proteins to deduce important protein modifications.

Sitagliptin plus granulocyte colony-stimulating factor in patients suffering from acute myocardial infarction: A double-blind, randomized placebo-controlled trial of efficacy and safety (SITAGRAMI trial).

OBJECTIVE: In animal models, G-CSF based progenitor cell mobilization combined with a DPP4 inhibitor leads to increased homing of bone marrow derived progenitor cells to the injured myocardium via the SDF1/CXCR4 axis resulting in improved ejection fraction and survival after acute myocardial infarction (AMI). RESEARCH DESIGN AND METHODS: After successful revascularization in AMI, 174 patients were randomized 1:1 in a multi-centre, prospective, placebo-controlled, parallel group, double blind, phase III efficacy and safety trial to treatment with G-CSF and Sitagliptin (GS) or placebo. Diabetic and non-diabetic patients were included in our trial. The primary efficacy endpoint hierarchically combined global left and right ventricular ejection fraction changes from baseline to 6 months of follow-up (ΔLVEF, ΔRVEF), as determined by cardiac MRI. RESULTS: At follow-up ΔLVEF as well as ΔRVEF did not differ between the GS and placebo group. Patients in the placebo group had a similar risk for a major adverse cardiac event within 12 months of follow-up as compared to patients under GS. CONCLUSION: Progenitor cell therapy comprising the use of G-CSF and Sitagliptin after successfully revascularized acute myocardial infarction fails to show a beneficial effect on cardiac function and clinical events after 12 months. (EudraCT: 2007-003,941-34; ClinicalTrials.gov: NCT00650143, funding: Heinz-Nixdorf foundation).

Distribution of coronary calcifications in patients with suspected coronary heart disease.

BACKGROUND: Coronary calcifications are a marker of coronary atherosclerosis. The role of coronary calcium scoring (CS) as part of the initial evaluation of patients with suspected coronary heart disease (CHD) is controversially discussed. The primary goal of this study was to characterize the coronary calcium distribution in this particular patient population. In a second step, we aimed to establish a possible clinical implication using CS for the diagnosis of CHD. METHODS: Calcium scoring procedure was performed by either using a multidetector or a dual-source computed tomographic scanner. All patients underwent invasive coronary angiography (ICA) as the current criterion standard for CHD detection. A total of 4,137 (2,780 men, mean age 60.5 ± 12.4 years) consecutive patients were included. RESULTS: Mean CS was 288 ± 446 (range 0-5,252). Overall coronary artery calcifications significantly increased with patients' age. In 2,048 patients (mean CS 101 ± 239, range 0-5252), significant CHD (≥50% stenosis) was excluded by ICA (1,939 patients without calcifications). In remaining 2,089 patients (51%, mean CS 607 ± 821, range 0-5,252), significant CHD was documented leading to intervention in 732 patients. A threshold of zero calcifications (existence of calcified tissue) had the best overall sensitivity and negative predictive value with 99%. Overall specificity with 34% and overall positive predictive value with 24% were rather low. CONCLUSION: Coronary calcium scoring is able to exclude significant CHD in patients with suspected CHD with a high negative predictive value and, therefore, possibly reduce the number of invasive diagnostic examinations. Because of the low specificity and positive predictive value, CS cannot be used to indicate ICA.

Dynamic myocardial CT perfusion imaging for evaluation of myocardial ischemia as determined by MR imaging.

OBJECTIVES: The aim of this study was to determine the feasibility of computed tomography (CT)-based dynamic myocardial perfusion imaging for the assessment of myocardial ischemia and infarction compared with cardiac magnetic resonance (CMR). BACKGROUND: Sequential myocardial CT perfusion imaging has emerged as a novel imaging technique for the assessment of myocardial hypoperfusion. METHODS: We prospectively enrolled subjects with known coronary artery disease who underwent adenosine-mediated stress dynamic dual-source CT (100 kV, 320 mAs/rot) and CMR (3-T). Estimated myocardial blood flow (eMBF) and estimated myocardial blood volume (eMBV) were derived from CT images, using a model-based parametric deconvolution technique. The values were independently related to perfusion defects (ischemic and/or infarcted myocardial segments) as visually assessed during rest/stress and late gadolinium enhancement CMR. Conventional measures of diagnostic accuracy and differences in eMBF/eMBV were determined. RESULTS: Of 38 enrolled subjects, 31 (mean age 70.4 ± 9.3 years; 77% men) completed both CT and CMR protocols. The prevalence of ischemic and infarcted myocardial segments detected by CMR was moderate (11.6%, n = 56 and 12.6%, n = 61, respectively, of 484 analyzed segments, with 8.4% being transmural). The diagnostic accuracy of CT for the detection of any perfusion defect was good (eMBF threshold, 88 ml/mg/min; sensitivity, 77.8% [95% confidence interval (CI): 69% to 85%]; negative predictive value, 91.3% [95% CI: 86% to 94%]) with moderate positive predictive value (50.6% [95% CI: 43% to 58%] and specificity (75.41% [95% CI: 70% to 79%]). Higher diagnostic accuracy was observed for transmural perfusion defects (sensitivity 87.8%; 95% CI: 74% to 96%) and infarcted segments (sensitivity 85.3%; 95% CI: 74% to 93%). Although eMBF in high-quality examinations was lower but not different between ischemic and infarcted segments (72.3 ± 18.7 ml/100 ml/min vs. 73.1 ± 31.9 ml/100 ml/min, respectively, p > 0.05), eMBV was significantly lower in infarcted segments compared with ischemic segments (11.3 ± 3.3 ml/100 ml vs. 18.4 ± 2.8 ml/100 ml, respectively; p < 0.01). CONCLUSIONS: Compared with CMR, dynamic stress CT provides good diagnostic accuracy for the detection of myocardial perfusion defects and may differentiate ischemic and infarcted myocardium.

Rapid ammonia gas transport accounts for futile transmembrane cycling under NH3/NH4+ toxicity in plant roots.

Futile transmembrane NH3/NH4(+) cycling in plant root cells, characterized by extremely rapid fluxes and high efflux to influx ratios, has been successfully linked to NH3/NH4(+) toxicity. Surprisingly, the fundamental question of which species of the conjugate pair (NH3 or NH4(+)) participates in such fluxes is unresolved. Using flux analyses with the short-lived radioisotope (13)N and electrophysiological, respiratory, and histochemical measurements, we show that futile cycling in roots of barley (Hordeum vulgare) seedlings is predominately of the gaseous NH3 species, rather than the NH4(+) ion. Influx of (13)NH3/(13)NH4(+), which exceeded 200 µmol g(-1) h(-1), was not commensurate with membrane depolarization or increases in root respiration, suggesting electroneutral NH3 transport. Influx followed Michaelis-Menten kinetics for NH3 (but not NH4(+)), as a function of external concentration (Km = 152 µm, Vmax = 205 µmol g(-1) h(-1)). Efflux of (13)NH3/(13)NH4(+) responded with a nearly identical Km. Pharmacological characterization of influx and efflux suggests mediation by aquaporins. Our study fundamentally revises the futile-cycling model by demonstrating that NH3 is the major permeating species across both plasmalemma and tonoplast of root cells under toxicity conditions.