bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intra‐ and Interchain Disulfide Bond Generation in S100b Protein
Authors: Mely Yves , Gérard Dominique 
Published: October 2006

Abstract: Disulfide‐bridged S100b protein formation, air‐catalyzed and induced by thiol/disulfide exchange, was studied under various ionic conditions. As native, physiological disulfide‐bridged proteins are obtained easily from their reduced counterparts under appropriate redox conditions, this work was performed to determine whether this was the case for disulfide‐bridged S100b proteins, reported to have neurite extension activity. In nondenaturating native medium, no disulfide‐bridged species could be generated from reduced proteins in any of the ion‐induced conformations tested (no ions, Ca2+, Zn2+, or K+) under widely different redox conditions. Only mixed disulfides accumulated, in certain cases.In contrast, intrasubunit monomeric and intersubunit dimeric disulfide‐bridged species were readily and efficiently generated under denaturating conditions. A brief characterization of these oxidized species suggested that they differed widely in structure from their reduced counterparts and that they probably did not bind Ca2+. Taken together, these data question the physiological relevance of these disulfide‐bridged S100b protein species.
Comparative Effect of Transient Global Ischemia on Extracellular Levels of Glutamate, Glycine, and γ‐Aminobutyric Acid in Vulnerable and Nonvulnerable Brain Regions in the Rat
Authors: Globus Mordecai Y.‐T. , Busto Raul , Martinez Elena , Valdés Isabel , Dietrich W. Dalton , Ginsberg Myron D. 
Published: October 2006

AbstractWe evaluated whether regional differences in the magnitude of glutamate, γ‐aminobutyric acid (GABA), and glycine release could explain why some regions are vulnerable to ischemia whereas others are spared. By means of the microdialysis technique, the temporal profile of ischemia‐induced changes in extracellular levels of glutamate, GABA, and glycine was compared in regions that demonstrate differing susceptibilities to a 10‐ and 20‐min ischemic insult (dorsal hippocampus, anterior thalamus, somatosensory cortex, and dorsolateral striatum). The degree of ischemia (as established by local cerebral blood flow reduction) and the magnitude of histopathoiogical neuronal damage were also evaluated in these regions. The blood flow reduction was severe and uniform in all regions; however, the histopathoiogical outcome illustrated a different pattern. Whereas the CA1 sector of the hippocampus was severely damaged, the thalamus and cortex were relatively spared from both 10 and 20 min of ischemia. Striatal neurons were resistant to a 10‐min insult but severely damaged after 20 min of ischemia. Ischemia‐induced increases in glutamate and GABA content were of a similar magnitude and temporal profile in all four brain regions. A uniform increase in extracellular glycine levels was also observed in all four brain structures. The postischemic response, however, was different Glycine levels remained twofold higher than baseline in the hippocampus but fell to baseline in the cortex and thalamus after both 10‐ and 20‐min insults. In the striatum, glycine levels returned to baseline after 10 min of ischemia but remained relatively high after a 20‐min insult Although ischemic neuronal damage was not related to glutamate release, it correlated with the „excitotoxic index,” whose value was derived from the following equation: [glutamate] X [glycine]/[GABA]. No significant changes were observed in the excitotoxic index during ischemia. However, a significant increase in the index was observed in vulnerable brain regions during the early and late recirculation periods. These results suggest that the imbalance between excitation and inhibition, reflected by changes in the excitotoxic index, may account for regional vulnerability to ischemia.
The Susceptibility of Cerebral Endothelial Cells to Astroglial Induction of Blood‐Brain Barrier Enzymes Depends on Their Proliferative State
Authors: Meyer Jörg , Rauh Jürgen , Galla Hans‐Joachim 
Published: October 2006

AbstractPrimary cultures of brain capillary endothelial cells (BCECs) were used to investigate the induction of blood‐brain barrier (BBB) characteristics in vitro. Enzymatic activities of γ‐glutamyltranspeptidase (γ‐GT) and alkaline phos‐phatase (ALP) were taken as indicators for the expression of the BBB phenotype. We were able to show that a coculture system with a direct cell‐cell contact between astroglial cells and BCECs is the necessary precondition for an increase of these enzyme activities that are lost in pure BCEC cultures. Coculture with both astrocytes and C6‐glioma cells reestablishes the BBB phenotype whereas conditioned media as well as an astrocyte‐derived extracellular matrix were ineffective. The susceptibility of the BCECs to an astroglial stimulus depends on the proliferative state of the BCECs. Cells in an early highly proliferate culture phase were stimulated to express an enzymatic activity level similar to the in vivo situation. Confluent BCEC monolayers were not induced at all. With the ALP we observed a spatial induction within a BCEC colony. Astrocyte‐induced ALP activity was first observed at an outer belt of BCEC colonies in direct contact with the astrocyte layer. However, this signal is transferred to the center of the colony with time in culture. We conclude that direct contact of BCECs with astroglial cells is necessary for the induction of the BBB phenotype in cultured BCECs and that this signal may be transferred from induced to noninduced BCECs.
Extracellular Glutamate Is Increased in Thalamus During Thiamine Deficiency‐Induced Lesions and Is Blocked by MK‐801
Authors: Langlais Philip J. , Zhang Shu Xing 
Published: October 2006

AbstractThe current study measured extracellular fluid (ECF) levels of excitatory amino acids before and during the onset of thiamine deficiency‐induced pathologic lesions. Male Sprague‐Dawley rats were treated with daily pyrithiamine (0.25 mg/kg i.p.) and a thiamine‐deficient diet (PTD). Microdialysates were simultaneously collected from probes inserted acutely via guide cannulae into right paracentral and ventrolateral nuclei of thalamus and left hippocampus of PTD and pair‐fed controls. Hourly samples were collected from unanesthetized and freely moving animals. Basal levels obtained at a prelesion stage (day 12 of PTD treatment) were unchanged from levels in pairfed controls. In samples collected 4–5 h after onset of seizures (day 14 of PTD), the levels of glutamate were elevated an average 640% of basal levels in medial thalamus and 200% in hippocampus. Glutamine levels declined, taurine and glycine were elevated, and aspartate, GABA, and alanine were unchanged during this period. Within 7 h after seizure onset glutamine was undetectable in both areas, whereas glutamate had declined to ∼200% in thalamus and 70% in hippocampus. No significant change in glutamate, aspartate, or other amino acids was observed in dialysates collected from probes located in undamaged dorsal‐lateral regions of thalamus. Number of neurons within ventrolateral nucleus of thalamus was significantly greater in PTD animals in which the probe was dialyzed compared with nondialyzed, suggesting that removal of excitatory amino acids was protective. No significant pathologic damage was evident in hippocampus. Pretreatment with MK‐801 completely blocked the rise of ECF glutamate and significantly reduced the pathologic damage within thalamus of PTD rats and produced a significant decrease in ECF glutamate in control rats.
The Dark Side of Information and Market Efficiency in E‐Markets*
Authors: Grover Varun , Lim Jaejoo , Ayyagari Ramakrishna 
Published: October 2006

ABSTRACTPrice dispersion reflects the differences in prices for identical products. While in physical markets such dispersion is prevalent due to high search costs, many researchers argue that search costs and price dispersion will be much lower in electronic markets (e‐markets). Empirical evidence does not support this contention, and researchers have studied search costs, market factors, and service‐quality factors to explain this dispersion. Previous research has largely assumed that more information is better. By ignoring the dark side of information, we argue that only a partial understanding of price dispersion is possible. In this article, information overload and equivocality are studied as two dark attributes of information that lead sellers to different pricing decisions in e‐markets. Hypotheses relating these attributes to price dispersion are supported through analysis of 161 product markets. This work opens up new avenues in the study of e‐markets and discusses the implications of these findings for research and practice on consumer and seller decisions.
Comparison of Human Immunodeficiency Virus Type 1-Specific Inhibitory Activities in Saliva and Other Human Mucosal Fluids
Authors: Kazmi Shamim H. , Naglik Julian R. , Sweet Simon P. , Evans Robert W. , O'Shea Siobhan , Banatvala Jangu E. , Challacombe Stephen J. 
Published: October 2006

ABSTRACTSeveral human mucosal fluids are known to possess an innate ability to inhibit human immunodeficiency virus type 1 (HIV-1) infection and replication in vitro. This study compared the HIV-1 inhibitory activities of several mucosal fluids, whole, submandibular/sublingual (sm/sl), and parotid saliva, breast milk, colostrum, seminal plasma, and cervicovaginal secretions, from HIV-1-seronegative donors by using a 3-day microtiter infection assay. A wide range of HIV-1 inhibitory activity was exhibited in all mucosal fluids tested, with some donors exhibiting high levels of activity while others showed significantly lower levels. Colostrum, whole milk, and whole saliva possessed the highest levels of anti-HIV-1 activity, seminal fluid, cervicovaginal secretions, and sm/sl exhibited moderate levels, and parotid saliva consistently demonstrated the lowest levels of HIV-1 inhibition. Fast protein liquid chromatography gel filtration studies revealed the presence of at least three distinct peaks of inhibitory activity against HIV-1 in saliva and breast milk. Incubation of unfractionated and fractionated whole saliva with antibodies raised against human lactoferrin (hLf), secretory leukocyte protease inhibitor (SLPI), and, to a lesser extent, MG2 (high-molecular-weight mucinous glycoprotein) reduced the HIV-1 inhibitory activity significantly. The results suggest that hLf and SLPI are two key components responsible for HIV-1 inhibitory activity in different mucosal secretions. The variation in HIV inhibitory activity between the fluids and between individuals suggests that there may be major differences in susceptibility to HIV infection depending both on the individual and on the mucosal fluid involved.
High Levels of Serum Thromboxane B2 Are Generated during Human Pulmonary Dirofilariosis
Authors: Morchón R. , López-Belmonte J. , Rodríguez-Barbero A. , Simón F. 
Published: October 2006

ABSTRACT

The canine parasite
Dirofilaria immitis
can infect humans. Patients with pulmonary dirofilariosis develop significantly higher thromboxane B2 levels than healthy individuals living in areas where dirofilariosis is endemic and in areas where dirofilariosis is not endemic. The possible role of
Wolbachia
bacteria in the appearance of this eicosanoid is discussed.
The Intracellular Siderophore Ferricrocin Is Involved in Iron Storage, Oxidative-Stress Resistance, Germination, and Sexual Development in
Aspergillus nidulans
Authors: Eisendle Martin , Schrettl Markus , Kragl Claudia , Müller Daniela , Illmer Paul , Haas Hubertus 
Published: October 2006

ABSTRACT

Iron is required by most organisms, but an excess of this metal is potentially toxic. Consequently, uptake and intracellular storage of iron are tightly controlled. The filamentous fungus
A. nidulans
lacks the iron storage compound ferritin but possesses an intracellular siderophore, which is accumulated in a highly regulated manner as iron-free desferri-ferricrocin or iron-containing ferricrocin via transcriptional regulation of the nonribosomal peptide synthetase SidC. Biosynthesis of desferri-ferricrocin was low during iron-replete conditions but up-regulated by both iron starvation and intracellular iron excess, the latter caused by either a shift from iron-depleted to high-iron conditions or deregulation of iron uptake. Consequently, ferricrocin constituted only about 5% of the total iron content under iron-replete conditions but up to 64% during conditions of intracellular excess. In contrast, during iron starvation, desferri-ferricrocin was accumulated, which appears to represent a proactive strategy to prevent iron toxicity. Accumulation of the intracellular siderophore was also up-regulated by oxidative stress, which underscores the intertwining of iron metabolism and oxidative stress. Lack of the intracellular siderophore causes pleiotropic effects, as SidC deficiency results in (i) less-efficient utilization of iron, indicated by reduced growth under iron-depleted conditions and a higher iron demand under iron-replete conditions, (ii) delayed germination under iron-depleted conditions, (iii) increased sensitivity of conidia to oxidative stress, and (iv) elimination of cleistothecia formation in homothallic conditions.
Gis4, a New Component of the Ion Homeostasis System in the Yeast
Saccharomyces cerevisiae
Authors: Ye Tian , García-Salcedo Raúl , Ramos José , Hohmann Stefan 
Published: October 2006

ABSTRACT

Gis4 is a new component of the system required for acquisition of salt tolerance in
Saccharomyces cerevisiae
. The
gis4
Δ mutant is sensitive to Na
+
and Li
+
ions but not to osmotic stress. Genetic evidence suggests that Gis4 mediates its function in salt tolerance, at least partly, together with the Snf1 protein kinase and in parallel with the calcineurin protein phosphatase. When exposed to salt stress, mutants lacking
gis4
Δ display a defect in maintaining low intracellular levels of Na
+
and Li
+
ions and exporting those ions from the cell. This defect is due to diminished expression of the
ENA1
gene, which encodes the Na
+
and Li
+
export pump. The protein sequence of Gis4 is poorly conserved and does not reveal any hints to its molecular function. Gis4 is enriched at the cell surface, probably due to C-terminal farnesylation. The CAAX box at the C terminus is required for cell surface localization but does not seem to be strictly essential for the function of Gis4 in salt tolerance. Gis4 and Snf1 seem to share functions in the control of ion homeostasis and
ENA1
expression but not in glucose derepression, the best known role of Snf1. Together with additional evidence that links Gis4 genetically and physically to Snf1, it appears that Gis4 may function in a pathway in which Snf1 plays a specific role in controlling ion homeostasis. Hence, it appears that the conserved Snf1 kinase plays roles in different pathways controlling nutrient as well as stress response.
In vitro antagonism of endophytic Fusarium oxysporum isolates against the burrowing nematode Radopholus similis
Authors: Niere Bjoern , Athman Shahasi , Viljoen Altus , Gold Clifford , Dubois Thomas , Ragama Philip , Coyne Daniel , Labuschagne Nico 
Published: October 2006

AbstractRadopholus similis is one of the key pests of banana worldwide. In this study, nine endophytic Fusarium oxysporum isolates were screened for the production of secondary metabolites antagonistic to R. similis in culture. Undiluted and diluted culture filtrates were tested against motile stages and eggs of R. similis. All isolates tested demonstrated in vitro antagonistic activity, causing paralysis of R. similis motile stages. The percentage of paralysed nematodes increased with increase in the length of exposure time to culture filtrates. After 24 h exposure in culture filtrates up to 100% of the treated nematodes were paralysed compared to 26.5% in the control treatments. Nematode mortality rates after 24 h exposure in culture filtrates ranged from 76.4% to 100%. Paralysis was reversible at lower filtrate concentrations. Radopholus similis males were more sensitive to culture filtrates than females. Culture filtrates of all isolates demonstrated inhibitory effects on hatching of R. similis eggs. The results demonstrate the potential for using endophytic F. oxysporum as biological control agents against R. similis and for toxic derivatives from their secondary metabolism to be used as potential nematicides.
Symptoms, findings, and methods of diagnosis in patients with acoustic neuroma
Authors: Mathew Gregory D. , Facer George W. , Suh Ku W. , Houser O. Wayne , O'Brien Peter C. 
Published: October 2006

AbstractThe records of 225 patients with surgically documented acoustic neuromas seen at the Mayo Clinic between 1966 and 1976 were studied. Included in this group were 4 patients who had von Recklinghausen's disease with bilateral ear involvement, 7 patients with recurrence of acoustic neuroma, and 8 patients who were referred because of recurrent acoustic neuroma. Symptoms, clinical findings, and results of audiologic, vestibular, and roentgenographic studies were analyzed. Nine patients had a history of sudden onset of hearing loss, and 11 had a history of vertigo. A correlation between the size of the lesion and the symptoms, physical findings, and roentgenographic accuracy was made in an attempt to gain further knowledge of the natural course of the pathologic processes involved.
Fibrous histiocytoma of the head and neck: A case report
Authors: Hutchinson James C. , Friedberg Stanton A. 
Published: October 2006

AbstractFibrous histiocytomas are soft tissue tumors of histiocytic origin. One percent prove to be malignant. Reliable histologic criteria of malignancy are few, if any, and the diagnosis of malignancy often must be made on clinical (metastases) rather than histologic grounds. Thirty‐five cases originating in various deep structures of the head and neck, excluding the orbit, have been reported in the literature since 1972. One additional case, a malignant tumor of the submandibular gland, is added herewith. Recurrence following initial surgery has been common and stems from inadequate excision of the primary lesion. Microscopic spread of this tumor from its primary site calls for radical rather than conservative surgical excision. At present, radiotherapy and chemotherapy appear to be of little value in the treatment of these tumors.
Hypermobility of the incudostapedial joint: A clinical entity?
Authors: Miller Gale W. , Keith Robert W. 
Published: October 2006

AbstractDuring exploratory tympanotomy for conductive deafness, the surgeon is occasionally perplexed to find no apparent cause for the air‐bone gap. This unexplained deafness has been called “inner ear conductive hearing loss” because of the apparent absence of pathology in the middle ear.The incudostapedial joint was studied in 68 vertically sectioned temporal bones and the anatomy is presented. Varying amounts of laxity is observed in the normal joint capsule at the time of surgery. A theory is suggested in which an elongated capsule allows incus motion without energy transmission to the stapes. It is proposed that hypermobility of the incudostapedial joint may exist and explain conductive hearing loss of undetermined etiology.
Carcinoid apudoma arising in a glomus jugulare tumor: Review of endocrine activity in glomus jugulare tumors
Authors: Farrior Jay B. , Hyams Vincent J. , Benke Roy H. , Farrior J. Brown 
Published: October 2006

AbstractPrevious reports of endocrine activity of glomus jugulare tumors have been of pheochromocytomas but not carcinoid apudomas. This paper is to alert the otolaryngologist to the presence of carcinoid apudomas in glomus jugulare tumors. A patient with a long history of explosive diarrhea, facial flushing, and violent headaches, the symptom of carcinoid syndrome, was cured after removal of his large glomus jugulare tumor. The diagnosis of carcinoid syndrome is made with a good history and confirmed with a 24 hour urine collection for 5 Hydroxy indole acetic acid (5 HIAA). A series of patients treated at the Johns Hopkins Hospital for glomus jugulare tumors is reviewed for the presence of endocrine activity and the literature on endocrine active glomus jugulare tumors is presented. Preoperative evaluation for the presence of both pheochromocytoma and carcinoid apudoma is recommended for all patients with glomus jugulare tumors.
Intact acoustic reflexes in the presence of ossicular disruption
Authors: Jenkins Herman A. , Morgan Donald E. , Miller Robert H. 
Published: October 2006

AbstractThe potential usefulness of impedance studies is reviewed and a case of osteogenesis imperfecta, having bilateral ossicular discontinuity and intact acoustic reflexes, is presented. This seeming paradox was explainable on the basis of surgically confirmed, bilateral disruption of the stapes crura, central to the stapedial tendon insertion.
Local IgA‐Class antibodies against respiratory viruses in middle ear and nasopharyngeal secretions of children with secretory otitis media
Authors: Meurman Olli Henrik , Sarkkinen Hannu Kalevi , Puhakka Heikki Juhani , Virolainen Erkki Simo , Meurman Otto Henrik 
Published: October 2006

AbstractThe presence of antibodies against some important respiratory viruses in the middle ear and nasopharyngeal secretions of 52 children with secretory otitis media (SOM) was investigated in order to find out about the role of these viruses in the development of SOM.The method employed was a sensitive radioimmunoassay test.Antibodies to adeno, respiratory syncytial, and parainfluenza 3 viruses were detected in about 50%, 50% and 20% of the patients, respectively. In eight patients the middle ear secretion/nasopharyngeal secretion titer ratio of antibodies to one virus was selectively increased in comparison with the other viruses tested, indicating an active local production of specific antibodies in the middle ear.Further studies are required to determine the cause of such an active antibody synthesis and its possible role in the etiopathogenesis of SOM.
Tinnitus: Development of a neurophysiologic correlate
Authors: Sasaki Clarence T. , Babitz Lisa , Kauer John S. 
Published: October 2006

AbstractAlthough tinnitus severely afflicts 7.2 million Americans, the pathophysiology of this problem remains obscure because there presently exists no good animal model in which to study the phenomenon. We have examined changes in activity in the guinea pig auditory pathway using an autoradiographic method of functional brain mapping after short‐term and long‐term cochlear ablations which can, in humans, initiate the occurrence of tinnitus. With this method we have observed a reduction in activity in various nuclei in the auditory pathway between 4 hrs and 10 days after unilateral cochlear ablation. In contrast to these findings we have found a return of activity in these same nuclei if they are observed from 12 to 48 days following the lesion. These preliminary data suggest that this return of activity in the absence of sensory input may be a valid experimental analogue for tinnitus in humans. Such evidence for auditory plasticity may represent a significant first step toward understanding this common and profound otologic symptom.
Viability of skin flaps subjected to simultaneous chemical peel with occlusive taping
Authors: Hayes David K. , Stambaugh Kweon I. 
Published: October 2006

AbstractThis study was undertaken to determine whether the application of a standardized chemical peel with an occlusive tape dressing to an acutely raised skin flap (as in combining rhytidectomy with chemical peel) affects skin flap viability. Thirty‐six 4‐cm x 4.cm dorsal skin flaps were raised on guinea pigs and sutured back into place. Eighteen of these flaps were simultaneously treated with a single application of Baker's solution and a 24‐hour occlusive tape dressing. A mean of 3.1 cm2 of the non‐peeled flaps necrosed, compared with 6.3 cm2 of the peeled flaps, a statistically significant increase in tissue loss in flaps that were simultaneously chemically peeled. We conclude that application of Baker's solution with an occlusive tape dressing to an acutely raised skin flap impairs skin flap viability and may result in skin flap necrosis.