bluuebunny/crossref_metadata_2025 huggingface dataset:
Reaction of gaseous mercury with molecular iodine, atomic iodine, and iodine oxide radicals — Kinetics, product studies, and atmospheric implications
Authors: Raofie Farhad , Snider Graydon , Ariya Parisa A
Published: July 2008

Mercury is present in the Earth’s atmosphere mainly in elemental form. The chemical transformation of mercury in the atmosphere may influence its bioaccumulation in the human food chain as well as its global cycling. We carried out the first kinetic and product studies of the reactions of gaseous mercury with molecular iodine, atomic iodine, and iodine oxide radicals at tropospheric pressure (~740 Torr) and 296 ± 2 K in air and in N2 (1 Torr = 133.322 4 Pa; 0 °C = 273.15 K). Atomic iodine was formed using UV photolysis of CH2I2. IO radicals were formed by the UV photolysis of CH2I2 in the presence of ozone The reaction kinetics were studied using absolute rate techniques with gas chromatographic and mass spectroscopic detection (GC–MS). The measured rate coefficient for the reaction of Hg0 with I2 was ≤ (1.27 ± 0.58) × 10–19 cm3 molecule–1 s–1. The reaction products were analyzed in the gas phase from the suspended aerosols and from deposits on the walls of the reaction chambers using six complementary methods involving chemical ionization and electron impact mass spectrometry, GC–MS, a MALDI-TOF mass spectrometer, a cold vapor atomic fluorescence spectrometer (CVAFS), and a high-resolution transmission electron microscope (HRTEM) coupled to an energy dispersive spectrometer (EDS). The major reaction products identified were HgI2, HgO, and HgIO or HgOI. The implications of the results are discussed with regards to both the chemistry of atmospheric mercury and its potential implications in the biogeochemical cycling of mercury.Key words: mercury, molecular iodine, atomic iodine, iodine oxide radicals kinetics, product study, atmospheric chemistry.
Biotransformation of caffeic acid by Momordica charantia peroxidase
Authors: Wan Xiang , Liu Haili , Huang Xuefeng , Luo Jianguang , Kong Lingyi
Published: July 2008

Biotransformation of caffeic acid with H2O2/Momordica charantia peroxidase at pH 5.0, 25 °C in the presence of acetone has resulted in the isolation of three caffeic acid trimers 1–3, five caffeic acid dimers 4–8, and one monomer 9. Among them, seven (1–7) are new compounds, and two (8 and 9) are known compounds, including one compound (9), which was obtained by biotransformation for the first time. The structures were established by 2D NMR techniques, such as HSQC, HMBC, and NOESY measurements. The possible mechanism for the formation of the products is also discussed. This is the first time that caffeic acid trimers have been obtained through the biotransformation of catalyzed by peroxidase in vitro. Compound 5 has shown much stronger anti-oxidative activity than the other caffeic acid polymers obtained.Key words: Momordica charantia peroxidase, caffeic acid, polymers of caffeic acid, biotransformation, antioxidant activity.
Protection of waterborne pathogens by higher organisms in drinking water: a review
Authors: Bichai Françoise , Payment Pierre , Barbeau Benoit
Published: July 2008

Higher organisms are ubiquitous in surface waters, and some species can proliferate in granular filters of water treatment plants and colonize distribution systems. Meanwhile, some waterborne pathogens are known to maintain viability inside amoebae or nematodes. The well-documented case of Legionella replication within amoebae is only one example of a bacterial pathogen that can be amplified inside the vacuoles of protozoa and then benefit from the protection of a resistant structure that favours its transport and persistence through water systems. Yet the role of most zooplankton organisms (rotifers, copepods, cladocerans) in pathogen transmission through drinking water remains poorly understood, since their capacity to digest waterborne pathogens has not been well characterized to date. This review aims at (i) evaluating the scientific observations of diverse associations between superior organisms and pathogenic microorganisms in a drinking water perspective and (ii) identifying the missing data that impede the establishment of cause-and-effect relationships that would permit a better appreciation of the sanitary risk arising from such associations. Additional studies are needed to (i) document the occurrence of invertebrate-associated pathogens in relevant field conditions, such as distribution systems; (ii) assess the fate of microorganisms ingested by higher organisms in terms of viability and (or) infectivity; and (iii) study the impact of internalization by zooplankton on pathogen resistance to water disinfection processes, including advanced treatments such as UV disinfection.
Bacteriocin ST91KM, produced by Streptococcus gallolyticus subsp. macedonicus ST91KM, is a narrow-spectrum peptide active against bacteria associated with mastitis in dairy cattle
Authors: Pieterse Reneé , Todorov Svetoslav D. , Dicks Leon M.T.
Published: July 2008

Streptococcus gallolyticus subsp. macedonicus ST91KM produces a bacteriocin (macedocin ST91KM) active against Streptococcus agalactiae , Streptococcus dysgalactiae subsp. dysgalactiae , Streptococcus uberis , Staphylococcus aureus , and Staphylococcus epidermidis . Macedocin ST91KM is, according to tricine-SDS PAGE, between 2.0 and 2.5 kDa in size. Antimicrobial activity remained unchanged after 2 h of incubation at pH 2.0–10.0 and after 100 min at 100 °C. The peptide was inactivated after 20 min at 121 °C and when treated with proteolytic enzymes. Treatment with α-amylase had no effect on activity, suggesting that the mode of action does not depend on glycosylation. Amplification of the genome of strain ST91KM with primers designed from the macedocin precursor gene (mcdA) produced 2 fragments (approximately 375 and 220 bp) instead of one 150-bp fragment, as recorded for macedocin produced by Streptococcus gallolyticus subsp. macedonicus ACA-DC 198. Strain ACA-DC 198 was not available. However, DNA amplified from strain LMG 18488 (ACA-DC 206), genetically closely related to strain ACA-DC 198, revealed 99% homology to the mcdA of strain ACA-DC 198 (accession No. DQ835394). Macedocin ST91KM may thus be a second putative bacteriocin described for Streptococcus gallolyticus subsp. macedonicus.
Characterization of antibiotic resistance genes linked to class 1 and 2 integrons in strains of Salmonella spp. isolated from swine
Authors: San Martín Betty , Lapierre Lisette , Cornejo Javiera , Bucarey Sergio
Published: July 2008

The aim of this study was to characterize the antibiotic resistance profiles, the integron-associated resistance determinants, and the potential ability of transferring these determinants by conjugation in Salmonella enterica isolated from swine. Fifty-four strains of Salmonella spp. were isolated from healthy swine. The percentages of resistance, determined by the plate dilution method were as follows: oxytetracycline (41%), streptomycin (39%), sulphamethoxazol+trimethoprim (19%), enrofloxacin–ciprofloxacin (13%), and amoxicillin (0%). The most important resistance serovars were Salmonella Branderburg, Salmonella Derby, Salmonella Typhimurium, and Salmonella Heidelberg. The oxytetracycline-resistant strains amplified the genes tetA (36%), tetB (64%); and the strains resistant to streptomycin and trimethoprim amplified the genes aadA1 (100%) and dfrA1 (100%), respectively. None of the fluoroquinolone-resistant strains amplified the gene qnr. Ten strains amplified the class 1 integron harboring the cassette aadA1. Six strains amplified the class 2 integron harboring the cassettes dfrA1, sat1, and aadA1. The conjugation assays showed that 2 strains transferred the tetA and aadA1 genes and the class 1 integron to a recipient strain. Taken together, the results obtained in this study show a high percentage of resistance in and the presence of integrons in strains of S. enterica isolated from swine. This information should support the implementation of regulations for the prudent use of antimicrobial agents in food-producing animals.
Leadership: Current Theories, Research, and Future Directions
Authors: Avolio Bruce J. , Walumbwa Fred O. , Weber Todd J.
Published: July 2008

This review examines recent theoretical and empirical developments in the leadership literature, beginning with topics that are currently receiving attention in terms of research, theory, and practice. We begin by examining authentic leadership and its development, followed by work that takes a cognitive science approach. We then examine new-genre leadership theories, complexity leadership, and leadership that is shared, collective, or distributed. We examine the role of relationships through our review of leader member exchange and the emerging work on followership. Finally, we examine work that has been done on substitutes for leadership, servant leadership, spirituality and leadership, cross-cultural leadership, and e-leadership. This structure has the benefit of creating a future focus as well as providing an interesting way to examine the development of the field. Each section ends with an identification of issues to be addressed in the future, in addition to the overall integration of the literature we provide at the end of the article.
Microinjection of muscimol into the periaqueductal gray suppresses cardiovascular and neuroendocrine response to air jet stress in conscious rats
Authors: de Menezes Rodrigo C. A. , Zaretsky Dmitry V. , Sarkar Sumit , Fontes Marco A. P. , DiMicco Joseph A.
Published: July 2008

Microinjection of the neuronal inhibitor muscimol into the dorsomedial hypothalamus (DMH) suppresses increases in heart rate (HR), mean arterial pressure (MAP), and circulating levels of adrenocorticotropic hormone (ACTH) evoked in air jet stress in conscious rats. Similar injection of muscimol into the caudal region of the lateral/dorsolateral periaqueductal gray (l/dlPAG) reduces autonomic responses evoked from the DMH, leading to the suggestion that neurons in the l/dlPAG may represent a descending relay for DMH-induced increases in HR and MAP. Here, we examined the role of neuronal activity in the caudal l/dlPAG on the increases in MAP, HR, and plasma ACTH seen in air jet stress in rats. Microinjection of muscimol into the caudal l/dlPAG reduced stress-induced increases in HR and MAP, while identical injections into sites just dorsal or into the rostral l/dlPAG had no effect. Microinjection of a combination of the glutamate receptor antagonists 2-amino-5-phosphonopentanoate (AP5) and 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione (NBQX) into the caudal l/dlPAG decreased stress-induced increases in HR alone only at the end of the 20-min stress period but significantly accelerated return to baseline. Surprisingly, microinjection of muscimol into the caudal l/dlPAG also reduced the stress-induced increase in plasma ACTH by 51%. Compared with unstressed control rats, rats exposed to air jet stress exhibited ∼3 times the number of Fos-positive neurons in the l/dlPAG. These findings suggest that neurons in the l/dlPAG are activated in air jet stress and that this activity contributes to increases in HR, MAP, and plasma ACTH.
Uncoupling of ER-mitochondrial calcium communication by transforming growth factor-β
Authors: Pacher Pál , Sharma Kumar , Csordás György , Zhu Yanqing , Hajnóczky György
Published: July 2008

Transforming growth factor-β (TGF-β) has been implicated as a key factor in mediating many cellular processes germane to disease pathogenesis, including diabetic vascular complications. TGF-β alters cytosolic [Ca2+] ([Ca2+]c) signals, which in some cases may result from the downregulation of the IP3 receptor Ca2+ channels (IP3R). Ca2+ released by IP3Rs is effectively transferred from endoplasmic reticulum (ER) to the mitochondria to stimulate ATP production and to allow feedback control of the Ca2+ mobilization. To assess the effect of TGF-β on the ER-mitochondrial Ca2+ transfer, we first studied the [Ca2+]c and mitochondrial matrix Ca2+ ([Ca2+]m) signals in single preglomerular afferent arteriolar smooth muscle cells (PGASMC). TGF-β pretreatment (24 h) decreased both the [Ca2+]c and [Ca2+]m responses evoked by angiotensin II or endothelin. Strikingly, the [Ca2+]m signal was more depressed than the [Ca2+]c signal and was delayed. In permeabilized cells, TGF-β pretreatment attenuated the rate but not the magnitude of the IP3-induced [Ca2+]c rise, yet caused massive depression of the [Ca2+]m responses. ER Ca2+ storage and mitochondrial uptake of added Ca2+ were not affected by TGF-β. Also, TGF-β had no effect on mitochondrial distribution and on the ER-mitochondrial contacts assessed by two-photon NAD(P)H imaging and electron microscopy. Downregulation of both IP3R1 and IP3R3 was found in TGF-β-treated PGASMC. Thus, TGF-β causes uncoupling of mitochondria from the ER Ca2+ release. The sole source of this would be suppression of the IP3R-mediated Ca2+ efflux, indicating that the ER-mitochondrial Ca2+ transfer depends on the maximal rate of Ca2+ release. The impaired ER-mitochondrial coupling may contribute to the vascular pathophysiology associated with TGF-β production.
Lesions of the Cerebellar Nodulus and Uvula Impair Downward Pursuit
Authors: Walker Mark F. , Tian Jing , Shan Xiaoyan , Tamargo Rafael J. , Ying Howard , Zee David S.
Published: July 2008

We studied sinusoidal (SIN) and step-ramp (SR) pursuit in two rhesus monkeys, before and after surgical lesions of the cerebellar nodulus and uvula (Nod/Uv). Eye movements were recorded using the magnetic field scleral search coil method. Pursuit targets were generated by an LCD projector and back-projected onto a tangent screen in an otherwise dark room. After the Nod/Uv lesions, both monkeys showed a reduced eye velocity during downward pursuit (SIN: 42% decrease in M1, 91% decrease in M2; SR: 37% decrease in M1, 85% decrease in M2). For SR, the decrease was seen only for the closed-loop response; initial eye acceleration did not change ( P > 0.05). Upward pursuit gains increased for SIN (M1: 9%, M2: 11%); they decreased for SR (M1: 27%, M2: 18%), but to a lesser degree than for downward pursuit. Horizontal pursuit was little changed in M1 but was reduced in one direction in M2, the animal with the larger lesion. The deficit in downward tracking was limited to foveal pursuit; ocular following of random-dot stimuli was retained, even when the target subtended only several degrees. Our findings support a critical role for the Nod/Uv in vertical pursuit, particularly for sustained downward pursuit. Finally, in both monkeys, the lesion increased spontaneous upward ocular drift in the dark (mean prelesion, 1.43°/s; postlesion, 5.92°/s), suggesting a role for the Nod/Uv in holding the eyes still and in the genesis of downbeat nystagmus.
Nephron deficit is not required for progressive proteinuria development in the Munich Wistar Frömter rat
Authors: Schulz Angela , Hänsch Jonna , Kuhn Kristina , Schlesener Maria , Kossmehl Peter , Nyengaard Jens R. , Wendt Norbert , Huber Matthias , Kreutz Reinhold
Published: July 2008

The Munich Wistar Frömter (MWF) rat represents a genetic model with an inherited nephron deficit and exhibits mild hypertension and progressive albuminuria, which is more pronounced in males than females. Previously, we demonstrated in a consomic strain that replacement of a quantitative trait locus on chromosome 6 normalized the nephron deficit and suppressed albuminuria development, suggesting a link between the two findings. Here we tested the role of a second major locus linked to albuminuria in MWF on chromosome 8 and generated the consomic strain MWF-8SHRby transfer of chromosome 8 from spontaneously hypertensive rats (SHR) into MWF. The early onset of albuminuria at 8 wk of age in MWF (>50-fold increase compared with SHR) was significantly suppressed in consomic animals, and the development of marked proteinuria at 32 wk significantly diminished. Total nephron number in consomic rats (23,771 ± 1,352) and MWF (27,028 ± 1,322) were similar and significantly lower (−36%) compared with SHR (36,979 ± 1,352, P < 0.0001). The development of mild albuminuria in female MWF was also significantly diminished in MWF-8SHR. Thus, the development of overt and mild albuminuria in male and female MWF rats is not a mandatory consequence of the inherited nephron deficit. The locus on chromosome 8 appears of interest, because its exchange between MWF and SHR protects against the development of albuminuria in MWF-8SHRanimals despite their inherited nephron deficit and higher systolic blood pressure.
Use of 31P Magnetic Resonance Spectroscopy to Study the Effect of Cortical Magnesium and Energy Metabolism after Subarachnoid Hemorrhage
Authors: Yang Heping , Tang Xiangqi , Tan Lihua , Zeng Liuwang , Hu Zhiping
Published: July 2008

Background: Flow metabolism coupling ensures adequate cerebral oxygenation. When subarachnoid hemorrhage (SAH) occurs, the flow metabolism coupling lost its balance and results in cerebral ischemia and infarction second to cortical magnesium and energy metabolism alternation. During chronic vasospasm, change in cortical energy metabolism is coupled with change in cerebral blood flow after SAH. Methods: What kind of noninvasive technique can be used to directly investigate the biochemical environment in the SAH brain? Studies showed that 31P magnetic resonance spectroscopy (31P MRS) is ideally suited to evaluate the pathophysiology of SAH, especially for cortical magnesium and energy metabolism. Results: The results showed that cortical magnesium and energy metabolism were significantly decreased in both animal models and human beings after SAH by using 31P MRS, which is associated with the severity and outcome of SAH, especially after aneurysmal SAH. Conclusion: 31P MRS data, combined with other MRI sequences, provide a comprehensive assessment of both structural and functional deficits and a guidance on clinical therapy for SAH.
Mood Disorders after Stroke: Diagnostic Validation of the Poststroke Depression Rating Scale
Authors: Quaranta Davide , Marra Camillo , Gainotti Guido
Published: July 2008

Background: Poststroke depression (PSD) is a common and invalidating condition, requiring a prompt diagnosis to provide appropriate treatment. The diagnosis of PSD is based on clinical evaluation, supported by psychiatric scales, predominantly constructed to assess ‘functional’ depressive disorders, which can miss important clinical information about PSD. This study evaluated the diagnostic accuracy of the Poststroke Depression Rating Scale (PSDRS), a diagnostic tool specifically devised to assess depression after stroke, in comparison to the Hamilton Depression Rating Scale (Ham-D). Methods: 143 patients were enrolled at their first-ever stroke; 46 subjects received a diagnosis of major depression-like disorder (MDL) and 53 a diagnosis of mood disorder with depressive manifestations (MDDM). Each patient underwent the PSDRS, Ham-D and Mini Mental State Examination. Areas under receiver-operating characteristic curves were calculated to evaluate diagnostic accuracy. Results: At their optimum cut-off points, the Ham-D and PSDRS showed good sensitivity and specificity for MDL or MDL + MDDM; the PSDRS had a higher positive predictive value for MDL in respect of the Ham-D (78 vs. 59%). Furthermore, the diagnostic accuracy of the PSDRS was higher in respect of the Ham-D in aphasic patients. Regression analyses showed that a longer latency from stroke onset predicted misdiagnosis on both PSDRS and Ham-D; the Ham-D was significantly influenced by cognitive impairment while the PSDRS was affected by age. Conclusions: The Ham-D and PSDRS are both reliable diagnostic tools for the diagnosis of PSD. The PSDRS showed a slightly superior positive predictive value for MDL, particularly in aphasic patients, and was not influenced by cognitive dysfunction, a common consequence of stroke affecting the diagnostic performance of the Ham-D. We suggest that the PSDRS could be a useful tool in clinical practice and in therapeutic trials.
Long-Term Survival after Ischemic Stroke in Postmenopausal Women Is Affected by an Interaction between Smoking and Genetic Variation in Nitric Oxide Synthases
Authors: Oksala N.K.J. , Oksala A. , Erkinjuntti T. , Pohjasvaara T. , Kunnas T. , Vataja R. , Kaste M. , Karhunen P.J.
Published: July 2008

Background: We aimed to study whether variations in vasoregulatory endothelial nitric oxide synthase (eNOS 4a/b) and tissue-injury-associated inducible nitric oxide synthase (iNOS R5/4) genes and smoking might explain gender differences in long-term survival after stroke. Methods: A total of 486 consecutive acute stroke patients, subjected to MRI, were followed up for a mean of 7.6 years. The eNOS 4a/b (n = 300) and iNOS R5/4 (n = 310) genotypes were determined by PCR. Of these patients, 213/300 (71.0%; eNOS 4a/b) and 223/310 (71.9%; iNOS R5/4) had died. Results: Despite the fact that women were older than men (72.3 vs. 69.5 years, p = 0.001) at recruitment, poor long-term survival was not sex-related, but instead predicted by age (p < 0.0001), cardiac failure (p = 0.004), smoking (p = 0.017), diabetes (p = 0.049), and variation in the eNOS gene locus (p = 0.033). Smoking and variations in both eNOS [hazard ratio (HR) = 1.53, p = 0.011] and iNOS loci (HR = 1.52, p = 0.073) were found to impact upon poor survival. We found a strong interaction between smoking, female sex, and the iNOS R5/4 genotype with the risk of death (HR = 3.23, CI = 1.51–6.90, p = 0.002). Compared with nonsmoking noncarriers, postmenopausal women who had been smokers and carried either the rare iNOS R5 allele (17.1%; HR = 4.23, CI = 1.84–9.75, p = 0.001) or the common eNOS 4b allele (71%; HR = 3.14, CI = 1.49–6.62, p = 0.003) were at a higher risk of death during the follow-up. These interactions were independent of each other, and were not found among men. Conclusions: The interaction between smoking and genetic variants of eNOS and iNOS predicts survival after stroke, especially among postmenopausal women.
Assessment of the Course and Division Patterns of the Middle Cerebral Artery M1 Segment
Authors: Vuillier Fabrice , Medeiros Elisabeth , Tatu Laurent , Cattin Françoise , Bonneville Jean-François , Moulin Thierry
Published: July 2008

Background and Purpose: The present study was undertaken to assess the ability of bedside transcranial color-coded sonography (TCCS) to define the course and the patterns of the division of the middle cerebral artery (MCA) M1 segment compared with 3D time-of-flight magnetic resonance angiography (MRA) at 3 T. Methods: Because MRA is considered as a reliable noninvasive technique to depict the normal anatomy of the intracranial artery, we prospectively defined the course and the patterns of division of 100 MCA M1 segments using bedside TCCS and compared the results with MRA findings. Results: In 68/85 cases (80%), the sonographer was able to define the division of the M1 segment, and classified these as bipode for 50/68 (73.5%), monopode for 16/68 (23.5%) and tripode for 2/68 (3%). A comparison of the TCCS and MRA findings showed a perfect correlation (100%) for the course of the M1 segment. As for the type of division, the correlation was good in 45/68 of cases (67%). TCCS had a sensitivity of 78%, a specificity of 67%, a positive predictive value of 87% and a negative predictive value of 52%, when used to determine whether the division was bipode or not. Conclusions: Our results show that bedside TCCS can now provide anatomical information on the M1 segment of the MCA.
Geographic Differences in Acute Stroke Care in Catalunya: Impact of a Regional Interhospital Network
Authors: Ribo Marc , Molina Carlos A. , Pedragosa Angels , Sanclemente Carme , Santamarina Estevo , Rubiera Marta , Delgado-Mederos Raquel , Maisterra Olga , Quintana Manuel , Alvarez-Sabin Jose
Published: July 2008

Limited resources prevent specialized care in community hospitals (CH) challenging geographical equity. We studied the impact of a regional interhospital network based on urgent transfer from 4 CH to a referral stroke center (RSC). Methods: During 2006, all stroke patients admitted to the 5 networked hospitals (4 CH, 1 RSC) were studied: clinical pathways and stroke interventions were recorded. Physicians at CH decided emergent transfer under their clinical judgment. Quality therapeutic measures where defined: urgent expert neurological evaluation, stroke unit admission and thrombolytic treatment. For patients receiving tissue plasminogen activator, demographic and outcome data were recorded: clinical improvement (decrease ≧4 National Institute of Health Stroke Scale points at discharge), total recovery (3-month modified Rankin Scale score ≧1). Results: From a total of 1,925 acute stroke patients, 1,587 were admitted to the RSC (1,396 primarily). Of 529 primarily admitted to CH, 191 (36.1%) were emergently transferred. Patients primarily admitted to the RSC were more frequently evaluated by a neurologist (100 vs. 34%; p < 0.001) and admitted to a stroke unit (22.7 vs. 11.7%; p < 0.001). However, the rate of thrombolytic treatment was similar (4.4 vs. 5.1%; p = 0.491). After initial assessment at the RSC, 92 (48.2%) transfers were considered unnecessary. Transferred patients accounted for 27/88 (30.7%) thrombolyses performed in the RSC. Baseline characteristics were similar, except a longer time to treatment (164 vs. 211 min; p = 0.004) and more frequent early ischemia CT signs among transferred patients (23 vs. 53%; p = 0.037). Clinical improvement (62 vs. 50%; p = 0.273) and symptomatic hemorrhagic transformation (6.8 vs. 3.8%; p = 0.596) were similar. However, among transferred patients, the degree of total recovery was lower (44 vs. 22%; p = 0.05). Conclusion: An interhospital network based on transfers to an RSC does not warrant geographical equity: equal access to best therapeutic interventions is only partially achieved at the expense of a high proportion of unnecessary transfers.
Frontal Activity during the Digit Symbol Substitution Test Determined by Multichannel Near-Infrared Spectroscopy
Authors: Nakahachi Takayuki , Ishii Ryouhei , Iwase Masao , Canuet Leonides , Takahashi Hidetoshi , Kurimoto Ryu , Ikezawa Kouji , Azechi Michiyo , Sekiyama Ryuji , Honaga Eiko , Uchiumi Chigusa , Iwakiri Masahiro , Motomura Naoyasu , Takeda Masatoshi
Published: July 2008

Backgrounds: The digit symbol substitution test (DSST) is a clinically useful and widely accepted tool for the detection of various psychiatric disorders. Investigating neural activity during the DSST is useful when considering the relationship between the poor performance on the DSST and neurocognitive deficits. However, obtaining reliable functional imaging of the neural mechanisms associated with this test is challenging due to motion artifacts. Aims: To circumvent this problem, we examined frontal lobe activity during the DSST using multichannel near-infrared spectroscopy, a noninvasive functional imaging technique that does not interfere with the DSST procedure. Methods: Twenty-five healthy volunteers were enrolled in this study. Changes in the concentration of oxygenated hemoglobin (oxyHb) during the DSST were determined bilaterally in 52 measurement points (channels) on the frontal area. Results: We found significant increases in oxyHb in more than 70% of the channels, with the intensity of the increase being more pronounced in the left hemisphere. Several channels showed significant positive correlations between changes in oxyHb and DSST performance. Some of the channels with a significant increase in oxyHb during the DSST did not show a correlation with the DSST performance. Conclusions: Our findings indicate that the DSST could prove useful as a frontal lobe stimulating task. Further examinations of DSST/near-infrared spectroscopy analyses of neural mechanisms in patients with psychiatric and neurological diseases are necessary to assess its effectiveness in clinical practice for the evaluation of neuropsychopathology.
Direct En Face Imaging of Secundum Atrial Septal Defects by Velocity-Encoded Cardiovascular Magnetic Resonance in Patients Evaluated for Possible Transcatheter Closure
Authors: Thomson Louise E.J. , Crowley Anna Lisa , Heitner John F. , Cawley Peter J. , Weinsaft Jonathan W. , Kim Han W. , Parker Michele , Judd Robert M. , Harrison J. Kevin , Kim Raymond J.
Published: July 2008

Background—

Atrial septal defect (ASD) flow can be measured indirectly by velocity-encoded cardiovascular magnetic resonance (veCMR) of the pulmonary artery and aorta. Imaging the secundum ASD en face could potentially enable direct flow measurement and provide valuable information about ASD size, shape, location, and proximity to other structures.

Methods and Results—

Forty-four patients referred for possible transcatheter ASD closure underwent a comprehensive standard evaluation, including transesophageal and/or intracardiac echocardiography and invasive oximetry. CMR was performed in parallel and included direct en face veCMR after an optimal double-oblique imaging plane was determined that accounted for ASD flow direction and cardiac-cycle interatrial septal motion. ASD flow measured by direct en face veCMR correlated better with invasive oximetry than indirect (pulmonary artery and aorta) veCMR (
r
=0.80 versus
r
=0.66). Additionally, 95% limits of agreement were narrower (�3.9 versus �5.1 L/min). En face veCMR determined that defects usually were eccentrically shaped (major/minor axis length >1.5) rather than circular, with 16% having extreme eccentricity (major/minor >2.0). Overall, ASD size by both veCMR and intracardiac echocardiography correlated with final device size; however, in small to medium defects (<3 cm
2
) and extremely eccentric defects, veCMR correlated better with final device size than did intracardiac echocardiography. Importantly, CMR identified additional information in 9 patients (20%) that altered clinical management. Specifically, en face veCMR detected additional defects (n=3), large ASD with insufficient rim tissue (n=2), and sinus venosus defect with anomalous pulmonary vein (n=1). Cine and/or morphological imaging detected interrupted inferior vena cava (n=2) and sinus of Valsalva aneurysm (n=1).

Conclusions—

En face veCMR with an optimized imaging plane can determine ASD flow, size, and morphology. CMR provided information incremental to comprehensive standard evaluation that altered clinical management in 20% of patients.
Magnetic Resonance–Derived 3-Dimensional Blood Flow Patterns in the Main Pulmonary Artery as a Marker of Pulmonary Hypertension and a Measure of Elevated Mean Pulmonary Arterial Pressure
Authors: Reiter Gert , Reiter Ursula , Kovacs Gabor , Kainz Bernhard , Schmidt Karin , Maier Robert , Olschewski Horst , Rienmueller Rainer
Published: July 2008

Background—

Pulmonary hypertension is a disease characterized by an elevation in pulmonary arterial pressure that is diagnosed invasively via right heart catheterization. Such pathological altered pressures in the pulmonary vascular system should lead to changes in blood flow patterns in the main pulmonary artery.

Methods and Results—

Forty-eight subjects (22 with manifest pulmonary hypertension, 13 with latent pulmonary hypertension, and 13 normal control subjects) underwent time-resolved 3D magnetic resonance phase-contrast imaging of the main pulmonary artery. Velocity fields that resulted from measurements were calculated, visualized, and analyzed with dedicated software. Main findings were as follows: (1) Manifest pulmonary hypertension coincides with the appearance of a vortex of blood flow in the main pulmonary artery (sensitivity and specificity of 1.00, 95% confidence intervals of 0.84 to 1.00 and 0.87 to 1.00, respectively), and (2) the relative period of existence of the vortex correlates significantly with mean pulmonary arterial pressure at rest (correlation coefficient of 0.94). To test the diagnostic performance of the vortex criterion, we furthermore investigated 55 patients in a blinded prospective study (22 with manifest pulmonary hypertension, 32 with latent pulmonary hypertension, and 1 healthy subject), which resulted in a sensitivity of 1.00 and specificity of 0.91 (95% confidence intervals of 0.84 to 1.00 and 0.76 to 0.98, respectively). Comparison of catheter-derived mean pulmonary artery pressure measurements and calculated mean pulmonary artery pressure values resulted in a standard deviation of differences of 3.6 mm Hg.

Conclusions—

Vortices of blood flow in the main pulmonary artery enable the identification of manifest pulmonary hypertension. Elevated mean pulmonary arterial pressures can be measured from the period of vortex existence.
Water-Mass Transformations in a Neutral Density Framework and the Key Role of Light Penetration
Authors: Iudicone Daniele , Madec Gurvan , McDougall Trevor J.
Published: July 2008

A new formulation is proposed for the evaluation of the dianeutral transport in the ocean. The method represents an extension of the classical diagnostic approach for estimating the water-mass formation from the buoyancy balance. The inclusion of internal sources such as the penetrative solar shortwave radiation (i.e., depth-dependent heat transfer) in the estimate of surface buoyancy fluxes has a significant impact in several oceanic regions, and the former simplified formulation can lead to a 100% error in the estimate of water-mass formation due to surface buoyancy fluxes. Furthermore, internal mixing can also be overestimated in inversions of in situ data when the shortwave radiation is not allowed to be penetrative.

The method examines the evolution equation of neutral density via the tendencies of potential temperature and salinity. The neutral density framework does not require the choice of a reference pressure and thus, unlike previous approaches that consider potential density, it is well suited for examining the whole open-ocean water column.

The methodology is easy to implement, particularly for ocean numerical models. The authors present here its application to a long simulation made with an ice–ocean global model, which allowed the method to be validated.
Elongation and Contraction of the Western Boundary Current Extension in a Shallow-Water Model: A Bifurcation Analysis
Authors: Primeau François , Newman David
Published: July 2008

The double-gyre circulation, formulated in terms of the quasigeostrophic equations, has a symmetry about the basin midlatitude (y → −y, ψ → −ψ), which is absent in a formulation based on the shallow-water equations. As a result, the shallow-water model does not have the pitchfork bifurcation structures that, in the case of the quasigeostrophic model, connect together multiple solution branches with elongated and contracted recirculation gyres. For the shallow-water model, solution branches with elongated recirculation gyres are disconnected, and a one-parameter bifurcation analysis is unable to detect their existence. The deeply penetrating jet solution branches do, however, continue to exist, and can be found using a bifurcation analysis couched in terms of two parameters. An effective pair of parameters is the viscosity and a parameter controlling the symmetry of the wind stress profile. A bifurcation analysis with these parameters reveals the existence of new solution branches that were not found in previous bifurcation analyses of the shallow-water model. The new solutions have a jet extension that penetrates farther eastward and that is more stable than the jet-up and jet-down solutions found in previous studies. Furthermore, the origin of the low-frequency variability at low viscosities is associated with a sequence of bifurcations originating from one of the new steady-state solution branches. In particular, the eigenmode analysis of the new branch reveals that a so-called gyre mode is at the origin of the model’s low-frequency variability at decadal time scales.
Wind Wave Growth at Short Fetch
Authors: Lamont-Smith T. , Waseda T.
Published: July 2008

Wave wire data from the large wind wave tank of the Ocean Engineering Laboratory at the University of California, Santa Barbara, are analyzed, and comparisons are made with published data collected in four other wave tanks. The behavior of wind waves at various fetches (7–80 m) is very similar to the behavior observed in the other tanks. When the nondimensional frequency F* or nondimensional significant wave height H* is plotted against nondimensional fetch x*, a large scatter in the data points is found. Multivariate regression to the dimensional parameters shows that significant wave height Hsig is a function of U2x and frequency F is a function of U1.25x, where U is the wind speed and x is the horizontal distance, with the result that in general for wind waves at a particular fetch in a wave tank, approximately speaking, the wave frequency is inversely proportional to the square root of the wind speed and the wavelength is proportional to the wind speed. Similarly, the wave height is proportional to U1.5 and the orbital velocity is proportional to U. Comparison with field data indicates a transition from this fetch law to the conventional one [the Joint North Sea Wave Project (JONSWAP)] for longer fetch. Despite differences in the fetch relationship for the wave tank and the field data, the wave height and wave period satisfy Toba’s 3/2 power law. This law imposes a strong constraint on the evolution of wind wave energy and frequency; consequently, the energy and momentum retention rate are not independent. Both retention rates grow with wind speed and fetch at the short fetches present in the wave tank. The observed retention rates are completely different from those typically observed in the field, but the same constraint (Toba’s 3/2 law) holds true.
Length Scales of Eddy Generation and Nonlinear Evolution of the Seasonally Modulated South Pacific Subtropical Countercurrent
Authors: Qiu Bo , Scott Robert B. , Chen Shuiming
Published: July 2008

The dynamical processes behind the seasonal modulation of the two-dimensional eddy kinetic energy (EKE) wavenumber spectrum in the Subtropical Countercurrent region of the South Pacific are investigated with 14 yr of satellite altimeter data and climatological hydrographic data. The authors find a seasonally modulated generation of EKE via baroclinic instability in modes with larger meridional length scales. Subsequent nonlinear eddy–eddy interactions redistribute the EKE to larger total horizontal length scales, and larger zonal scales in particular. This is confirmed by diagnosing the spectral transfer of EKE in the surface geostrophic flow, which is found to drive an anisotropic inverse cascade, being redirected in the sense consistent with the β effect, as predicted by geostrophic turbulence theory on the β plane. Because of the seasonal renewal of meridionally elongated anomalies by baroclinic instability and possibly because of the barotropization process, however, the net outcome for the formation of surface zonal flows is observed to be limited.
The Role of Southern Ocean Surface Forcings and Mixing in the Global Conveyor
Authors: Iudicone Daniele , Madec Gurvan , Blanke Bruno , Speich Sabrina
Published: July 2008

Despite the renewed interest in the Southern Ocean, there are yet many unknowns because of the scarcity of measurements and the complexity of the thermohaline circulation. Hence the authors present here the analysis of the thermohaline circulation of the Southern Ocean of a steady-state simulation of a coupled ice–ocean model. The study aims to clarify the roles of surface fluxes and internal mixing, with focus on the mechanisms of the upper branch of the overturning. A quantitative dynamical analysis of the water-mass transformation has been performed using a new method. Surface fluxes, including the effect of the penetrative solar radiation, produce almost 40 Sv (1 Sv ≡ 106 m3 s−1) of Subantarctic Mode Water while about 5 Sv of the densest water masses (γ > 28.2) are formed by brine rejection on the shelves of Antarctica and in the Weddell Sea. Mixing transforms one-half of the Subantarctic Mode Water into intermediate water and Upper Circumpolar Deep Water while bottom water is produced by Lower Circumpolar Deep Water and North Atlantic Deep Water mixing with shelf water. The upwelling of part of the North Atlantic Deep Water inflow is due to internal processes, mainly downward propagation of the surface freshwater excess via vertical mixing at the base of the mixed layer. A complementary Lagrangian analysis of the thermohaline circulation will be presented in a companion paper.
A General Analytic Method for Assessing Sensitivity to Bias of Performance Measures for Dichotomous Forecasts
Authors: Brill Keith F.
Published: July 2008

Performance measures computed from the 2 × 2 contingency table of outcomes for dichotomous forecasts are sensitive to bias. The method presented here evaluates how the probability of detection (POD) must change as bias changes so that a performance measure improves at a given value of bias. A critical performance ratio (CPR) of the change of POD to the change in bias is derived for a number of performance measures. If a change in POD associated with a bias change satisfies the CPR condition, the performance measure will indicate an improved forecast. If a perfect measure of performance existed, it would always exhibit its optimal value at bias equal to one. Actual measures of performance are susceptible to bias, indicating a better forecast for bias values not equal to one. The CPR is specifically applied to assess the conditions for an improvement toward a more favorable value of several commonly used performance measures as bias increases or decreases through the value one. All performance measures evaluated are found to have quantifiable bias sensitivity. The CPR is applied to analyzing a performance requirement and bias sensitivity in a geometric model.
Clues That Aid in the Diagnosis of Nonaccidental Trauma Presenting as an Apparent Life-Threatening Event
Authors: Vellody Kishore , Freeto Jennifer P. , Gage Sandra L. , Collins Nicole , Gershan William M.
Published: July 2008

Background Apparent life-threatening events (ALTEs) can encompass many different diagnoses. Nonaccidental trauma (NAT) is one potential serious diagnosis.

Objective (1) To identify key elements in the history and physical exam in infants presenting with an ALTE that aid in the subsequent diagnosis of NAT; and (2) to evaluate the role of diagnostic studies in these infants in confirming the diagnosis of NAT.

Design/Methods A retrospective chart review analysis, over a 2-year period, of infants with an ALTE was performed. From this group, all children with a discharge diagnosis of child physical abuse, shaken infant syndrome, or NAT were included in the study.

Results 4 patients were found to be victims of NAT based on their clinical histories and physical examinations. Although confirmatory, ophthalmologic exams, skeletal surveys, and head CT scans had a lower sensitivity for NAT.

Conclusions NAT should be considered when an infant is admitted for evaluation of an ALTE.
Breast-Feeding Rates at an Inner-City Pediatric Practice
Authors: Furman Lydia , Combs Bridget C. , Alexander Ashley D. , O'riordan Mary Ann
Published: July 2008

Objective To determine rates of breast-feeding in the first 2 months of life at an inner-city pediatric practice.

Methods Using retrospective chart reviews, we examined all visits through 2 months of age for infants seen from April 1, 2007, to June 29, 2007, at the Pediatric Practice of Rainbow Babies and Children's Hospital, Cleveland, Ohio, which serves a low-income urban population. Rates of breast-feeding were analyzed by visit number and by infant age category.

Results We reviewed all 557 visits occurring between birth and 2 months of age for all 223 eligible infants. At visit 1 (median age 5 days), the rates of exclusive and any breast-feeding were 22.0% and 40.8%, respectively. By visit 3 (median age 43 days), the rates of exclusive and any breast-feeding were 10.6% and 24.5%, respectively.

Conclusions These inner-city breast-feeding rates are substantially below reported regional and national rates. Barriers to implementing urgently needed interventions are discussed.
Association Between the Frequency of Disposable Diaper Changing and Urinary Tract Infection in Infants
Authors: Sugimura Tetsu , Tananari Yoshifumi , Ozaki Yukiko , Maeno Yasuki , Tanaka Seiji , Ito Shinichi , Kawano Keiko , Masunaga Kumiko
Published: July 2008

Background Often diapers are not changed after infants pass urine.

Aim To define the association between the frequency of changing diapers and urinary tract infection (UTI) in infants.

Methods Urine samples were tested in 131 infants (aged from 2 months to 2.5 years) who had a temperature ≥38°C. The authors investigated the number of times diapers were changed daily. A total of 128 infants, excluding 3 cases, were divided into 2 groups: group A, without UTI (n = 96); group B, with UTI (n = 32). The number of times diapers were changed was compared between the groups.

Results In group A and group B, the number of times diapers were changed daily were 7.5 ± 1.4 and 4.7 ± 1.4, respectively. The number of times diapers were changed was significantly lower ( P < .0001) in group B than in group A.

Conclusions Among infants wearing disposable diapers, there is an increased risk of UTI as the frequency of changing diapers decreases.
Clinical Spectrum of Shiga Toxin–Producing Escherichia coli (STEC) in Adults and Children
Authors: Appleman Stephanie Simon , Ascher David , Park Choong
Published: July 2008

This report describes the clinical spectrum of disease among a series of pediatric and adult patients with symptoms of gastroenteritis that subsequently tested positive for Shiga toxin—producing Escherichia coli in their stool. All diarrheal stools (n = 1712) between July 2005 and November 2006 were tested with Premier EHEC (Meridian Bioscience, Cincinnati, OH). A total of 1.6% patients (27/1712) tested positive and 41% of patients had non-0157 E. coli, which can cause moderate disease requiring hospitalization. Cases of non-0157 E. coli would have been missed without testing for Shiga toxin. All bloody stools, and perhaps all stools, should be tested for Shiga toxin.
Time- and Dose-based Gene Expression Profiles Produced by a Bile-duct–damaging Chemical, 4,4′-methylene Dianiline, in Mouse Liver in an Acute Phase
Authors: Kwon Sun-Bom , Park Joon-Suk , Yi Jung-Yeon , Hwang Jae-Wong , Kim Mingoo , Lee Mi-Ock , Lee Byung-Hoon , Kim Hyung-Lae , Kim Ju Han , Chung Heekyoung , Kong Gu , Kang Kyung-Sun , Yoon Byung-IL
Published: July 2008

A toxicogenomics study was performed in the mouse liver after treatment of a bile-duct–damaging chemical, 4,4′-methylene dianiline (MDA), across multiple doses and sampling times in an acute phase using the AB Expression Array System. Imprinting control region (ICR) mice were given a single oral administration of a low (10 mg/kg b.w.) or high (100 mg/kg b.w.) dose of MDA. Mice were sacrificed six, twenty-four, and seventy-two hours after treatment for serum chemistry, histopathology, and mRNA preparation from liver samples. Treatment with MDA increased liver-toxicity–related enzymes in blood and induced bile-duct cell injury, followed by regeneration. To explore potential biomarker gene profiles, the altered genes were categorized into four expression patterns depending on dose and time. Numerous functionally defined and unclassified genes in each category were up- or down-regulated throughout the period from cellular injury to the recovery phase, verified by RT-PCR. Many genes associated with liver toxicity and diseases belonged to one of these categories. The chemokine-mediated Th1 pathway was implicated in the inflammatory process. The genes associated with oxidative stress, apoptosis, and cell-cycle regulation were also dynamically responsive to MDA treatment. The Wnt/β-catenin signaling pathway was likely responsible for the reconstitution process of the MDA-injured liver.