bluuebunny/crossref_metadata_2025 huggingface dataset:
Epidermal growth factor stimulates urokinase‐type plasminogen activator expression in human gingival fibroblasts. Possible modulation by genistein and curcumin
Authors: Smith Patricio C. , Santibañez Juan F. , Morales Juan P. , Martinez Jorge
Published: October 2004

Background:  Regulation of the extracellular matrix turnover is a crucial process in wound healing and the progress of periodontal disease. It has been proposed that urokinase‐type plasminogen activator (uPA), under the control of growth factors or cytokines, provides the proteolytic potential to the accomplishment of these cellular events. Epidermal growth factor (EGF) is one of the growth factors that has been shown to be active in uPA regulation.

Methods:  In this study, we have assessed the effect of EGF on uPA expression in primary cultures of human gingival fibroblasts. We also studied the signaling pathways involved in this process and the role of the dietary phytoestrogens curcumin and genistein as potential modulators of this response.

Results:  Human gingival fibroblasts expressed a basal uPA activity, which was inhibited by genistein, but not by curcumin. After treatment with 10 ng/ml EGF, uPA production was strongly stimulated. Exposure to genistein and curcumin inhibited EGF‐stimulated urokinase production, although only genistein showed a statistically significant inhibitory response. Using more specific inhibitors, we found that the mitogen‐activated extracellular kinase and c‐Jun N‐terminal kinase (JNK) inhibitors PD98059 and SP600125 also blocked the EGF‐dependent stimulatory effect. On the other hand, SB203580, inhibitor of the p38 member of mitogen‐activated protein kinase family, did not alter this response. In accordance to these findings, EGF stimulated a potent activation of JNK and a mild activation of extracellular signal‐regulated kinases 1/2. Finally, EGF stimulated the phosphorylation of its receptor and tyrphostin (AG1478), curcumin and genistein were able to inhibit this stimulatory effect.

Conclusions:  These results indicate that EGF constitutes a strong stimuli on uPA expression in human gingival fibroblasts. Our data also shows that EGF‐stimulated uPA production involves the activation of the extracellular signal‐regulated kinases 1/2 and JNK signaling pathways and might be modulated by the natural phytoestrogens curcumin and genistein.
Effects of alendronate on restoration of biomechanical properties of periodontium in replanted rat molars
Authors: Shibata T. , Komatsu K. , Shimada A. , Shimoda S. , Oida S. , Kawasaki K. , Chiba M.
Published: October 2004

Objective:  We examined the effect of the pretreatment of roots with alendronate on the restoration of the support function of the healing periodontal ligament in replanted rat molars.

Methods:  The left maxillary first molars were extracted, placed in 0.9% NaCl containing 1 mm alendronate (alendronate group) or 0.9% NaCl (control group) for 5 min, and were replanted into their sockets. Groups of animals were killed at 7, 14, and 21 days after replantation. Normal control rats were also killed on the same days. The force required to extract the replanted or normal tooth from its socket was measured, and a load–deformation curve was developed and analyzed. Micro‐computed tomography and histologic analyses were also made.

Results:  The mechanical properties of the healing periodontal ligament in the alendronate group were gradually restored from 7 to 21 days. However, fractures of the roots and bones during mechanical testing occurred in most of the replanted teeth in the control group at 21 days. The rates of restoration of the mechanical strength, extensibility, stiffness, and toughness for the alendronate group at 21 days were 67, 98, 74, and 68% of the normal controls, respectively. Micro‐computed tomography and histologic observations revealed that bone‐like structures within the pulp and ankylosis between the roots and socket bones occurred commonly in the control group, but were uncommon in the alendronate group.

Conclusions:  Our findings suggest that the pretreatment with alendronate inhibits the formation of abnormal mineralized tissues and results in better restoration of the support function of the healing periodontal ligament in replanted teeth.
Prevotella intermedia lipopolysaccharide stimulates release of nitric oxide by inducing expression of inducible nitric oxide synthase
Authors: Kim Sung‐Jo , Ha Mi‐Suk , Choi Eun‐Young , Choi Jeom‐Il , Choi In‐Soon
Published: October 2004

Objectives:  The purpose of this study was to examine the effects of lipopolysaccharide from Prevotella intermedia, a major cause of inflammatory periodontal disease, on the production of nitric oxide (NO) and expression of inducible nitric oxide synthase (iNOS) in the murine macrophage cell line RAW264.7. We also attempted to throw light on the signaling mechanisms involved in P. intermedia lipopolysaccharide‐induced NO production.

Material and methods:  Lipopolysaccharide from P. intermedia ATCC 25611 was prepared by the standard hot phenol–water method. NO production was assayed by measuring the accumulation of nitrite in culture supernatants. Western blot analysis of iNOS and analysis of reverse transcription‐polymerase chain reaction (RT‐PCR) products were carried out.

Results:  We found that P. intermedia lipopolysaccharide can induce iNOS expression and stimulate the release of NO without additional stimuli and demonstrated an important role of the transcription factor nuclear factor‐κB (NF‐κB) and microtubule polymerization in NO production. The production of NO required l‐arginine but not activation of protein kinase C or protein tyrosine kinase.

Conclusions:  The present study clearly shows that P. intermedia lipopolysaccharide fully induced iNOS expression and NO production in RAW264.7 cells in the absence of other stimuli. The ability of P. intermedia lipopolysaccharide to promote the production of NO may be important in the pathogenesis of inflammatory periodontal disease.
The interleukin‐10 knockout mouse is highly susceptible to Porphyromonas gingivalis‐induced alveolar bone loss
Authors: Sasaki Hajime , Okamatsu Yoshimasa , Kawai Toshihisa , Kent Ralph , Taubman Martin , Stashenko Philip
Published: October 2004

Objective:  Interleukin‐10 is an anti‐inflammatory cytokine that reduces periapical bone loss, but its role in periodontal bone loss is unclear. In the present study, we tested the hypothesis that endogenous interleukin‐10 is a potent suppressor of Porphyromonas gingivalis‐induced alveolar bone loss in vivo.

Methods:  Interleukin‐10 knockout (–/–) and wild‐type mice were inoculated intraorally with P. gingivalis. Non‐infected animals served as negative controls. Alveolar bone loss, gingival cytokine levels, and gingival gene expression were assessed using morphometric analysis, enzyme‐linked immunosorbent assay (ELISA), and semiquantitative reverse transcription polymerase chain reaction (RT–PCR), respectively.

Results:  P. gingivalis‐infected interleukin‐10–/– mice exhibited severe alveolar bone loss compared to non‐infected interleukin‐10–/– and wild‐type mice by day 42. Surprisingly, bone resorptive cytokines interleukin‐1α and tumor necrosis factor alpha (TNF‐α) were not up‐regulated in gingival tissues by P. gingivalis‐infection. Although interleukin‐1β was marginally increased, blockade of both interleukin‐1 isoforms or interleukin‐1 receptor type I with neutralizing antisera failed to reduce alveolar bone loss in interleukin‐10–/– mice, indicating the operation of an interleukin‐1‐independent mechanism. No strong correlations between bone loss and other cytokines was observed, although interferon gamma (IFNγ), interleukin‐6, interleukin‐4, and prostaglandin E2 were modestly up‐regulated in infected interleukin‐10–/– mice. P. gingivalis infection reduced the expression of cell markers in gingival tissue on days 7 and 14 in both interleukin‐10–/– and wild‐type animals, suggestive of bacteria‐induced cytotoxicity or apoptosis. This was followed by up‐regulated expression of receptor activator of nuclear factor kappa B ligand (RANKL) and CD40 ligand (CD40L on days 28 and 70 in infected interleukin‐10–/– mice only.

Conclusion:  The interleukin‐10–/– mouse is highly susceptible to bone loss induced by the periodontal pathogen P. gingivalis, which is mediated via an interleukin‐1‐independent pathway.
Periodontal pathogens in atheromatous plaques. A controlled clinical and laboratory trial
Authors: Cairo F. , Gaeta C. , Dorigo W. , Oggioni M. R. , Pratesi C. , Pini Prato G. P. , Pozzi G.
Published: October 2004

Objective:  A possible relationship between periodontitis and cardiovascular disease has been suggested. The aims of this controlled clinical study were: (i) to ascertain the presence of periodontal bacteria DNA [Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis (formerly Bacteroides forsythus)] in carotid atheromatous plaques and (ii) to assess the concomitant presence of the same periodontal bacteria DNA, if any, in periodontal pockets and in carotid atheroma in the same patient.

Methods:  A total of 52 patients scheduled for carotid endarderectomy were enrolled in this study. The test group consisted of 26 dentate patients; the control group included 26 edentulous patients. A complete periodontal examination, including radiographic orthopanoramic and subgingival plaque sample, was performed in the test population. Oral and X‐ray examinations were performed in the control group. Atheromatous plaques were harvested during surgical procedure for each dentate and edentulous patient and then sent to the microbiological laboratory. Subgingival plaque samples and carotid specimens were examined using the polymerase chain reaction (PCR) technique by means of specific primers for periodontal bacteria. Amplification of extracted DNA was tested using human beta‐globin specific‐primers.

Results:  Out of 52 endarterectomy samples, 12 (seven dentate, five edentulous patients) were excluded as negative to DNA amplification. In subgingival plaque samples of 19 test patients, T. forsythensis (79%), F. nucleatum (63%), P. intermedia (53%), P. gingivalis (37%) and A. actinomycetemcomitans (5%) were found. No periodontal bacteria DNA was detected by PCR in any of the carotid samples in either patient group.

Conclusion:  The presence of periodontal bacteria DNA in atheromatous plaques could not be confirmed by this study and thus no correlation could be established between species associated with periodontal disease and putative bacteria contributing to atheromatous plaques.
The stimulatory effect of mu‐ and delta‐opioid receptors on bovine pinealocyte melatonin synthesis
Authors: Chuchuen Uayart , Ebadi Manuchair , Govitrapong Piyarat
Published: October 2004

Abstract:  Mammalian pinealocytes synthesize and secrete melatonin. The synthesis of melatonin is regulated by several biogenic amine, amino acid and peptide transmitters. In our previous study, the delta‐ and mu‐opioid receptors have been identified and characterized in bovine pinealocytes. In order to elaborate the function of different types of opioid receptors in regulating melatonin synthesis, we used a selective mu‐opioid receptor agonist, Tyr‐[d‐Ala2, N‐methyl‐phe4, glycol5] (DAMGO), a selective delta‐opioid receptor agonist, Enkephalin [d‐Pen2, d‐Pen5], (DPDPE) and a selective kappa‐opioid receptor agonist, ((+)‐(5α, 7α, 8β)‐N‐methyl‐N‐[7‐ (1‐pyrrolidinyl)‐1‐oxaspiro [4,5] dec‐8‐yl]‐benzene acetamide) (U69593) to investigate the activity of N‐acetyltransferase (NAT) activity and melatonin secretion. The results of the present study show that both DAMGO and DPDPE stimulated NAT activity and increased the level of melatonin in cultured bovine pinealocytes. These stimulatory effects were blocked by naloxone, an opioid receptor antagonist. However, the kappa‐opioid receptor agonist U69593 was unable to alter either the activity of NAT or the level of melatonin. In order to clarify the mechanism of how the activation of mu‐ and delta‐opioid receptors in bovine pinealocytes leads to an increase in NAT activity, cyclic AMP levels were measured after bovine pinealocytes were treated with morphine, DAMGO and DPDPE. The results indicated that these stimulatory effects acted via induction of cAMP production. This study reveals that the stimulatory effect of opioid receptor on melatonin synthesis is mediated via the activation of adenylate cyclase system.
Comparison of target innervation by sympathetic axons in adult wild type and heterozygous mice for nerve growth factor or its receptor trkA
Authors: Ghasemlou Nader , Krol Karmen M. , MacDonald Devon R. , Kawaja Michael D.
Published: October 2004

Abstract:  Nerve growth factor (NGF), a neurotrophin required for the survival and maintenance of postganglionic sympathetic neurons, mediates its trophic effects by activation of its high‐affinity receptor trkA. Null mutant mice lacking either NGF or trkA have profound sympathetic deficits, thus revealing the vital importance of NGF synthesis in target tissues and trkA expression by sympathetic neurons. In this study, we sought to assess whether sympathetic neurons of the superior cervical ganglion (SCG) display alterations in their neurochemical phenotype in adult mice carrying one mutated allele for either NGF or trkA, and whether such differences result in altered patterns of innervation to the submandibular salivary gland and pineal gland. In comparison with adult siblings, levels of trkA protein in the SCG were reduced in age‐matched NGF+/− and trkA+/− mice. While NGF+/− mice also had significantly fewer sympathetic axons innervating both the submandibular salivary gland and pineal gland, densities of sympathetic axons in both tissues reached normal levels in trkA+/− mice. These findings reveal that while levels of trkA are reduced in SCG neurons of adult NGF+/− and trkA+/− mice (compared with their wild type counterparts), sympathetic axons are capable of achieving normal patterns of target innervation in trkA+/− mice but not in NGF+/− mice. As NGF protein levels are not depleted in the submandibular salivary gland and pineal gland of NGF+/− mice, a loss of sympathetic neurons [Nat Neurosci 1999; 2:699–705], in combination with reduced levels of trkA protein, may account for perturbed patterns of sympathetic innervation to peripheral tissues.
Melatonin protects against ionizing radiation‐induced oxidative damage in corpus cavernosum and urinary bladder in rats
Authors: Şener Göksel , Atasoy Beste M. , Ersoy Yasemin , Arbak Serap , Şengöz Meriç , Yeğen Berrak Ç.
Published: October 2004

Abstract:  The objective of this study was to examine the potential radioprotective properties of pharmacological doses of melatonin on corpus cavernosum and bladder tissues of whole‐body irradiated (IR) rats. A total of 32 male Sprague–Dawley rats were exposed to irradiation performed with a LINAC which produced 6 MV photons at a focus 100 cm distant from the skin. Under ketamine anesthesia, each rat received a single whole‐body dose of 800 cGy. Immediately before and after IR, rats were treated with either saline or melatonin (20 and 10 mg/kg, i.p.) and decapitated at 12 hr after exposure to irradiation. Another group of rats was followed for 72 hr after IR, where melatonin injections were repeated once daily. Tissue levels of malondialdehyde (MDA), an index of lipid peroxidation, and glutathione (GSH), a key antioxidant, were estimated in corpus cavernosum and urinary bladder. Tissues were also examined microscopically. The results demonstrate that both 12 and 72 hr following IR, tissue levels of MDA were elevated (P < 0.001), while GSH levels were reduced (P < 0.01) in both tissues. On the other hand, melatonin reversed these changes significantly (P < 0.05–0.01), concomitant with the improvement in histological appearances. Our results show that whole‐body irradiation causes oxidative damage in the tissues of the genitourinary system. As melatonin administration reversed oxidative organ injury, as assessed by biochemical and histopathological findings, it is suggested that supplementing cancer patients with adjuvant therapy of melatonin may have some benefit for successful radiotherapy.
Prophylactic use of melatonin protects against focal cerebral ischemia in mice: role of endothelin converting enzyme‐1
Authors: Kilic Ertugrul , Kilic Ülkan , Reiter Russel J. , Bassetti Claudio L. , Hermann Dirk M.
Published: October 2004

Abstract:  Melatonin has previously been shown to be neuroprotective in rodent models of ischemic stroke. Herein, we tested whether this antioxidant may also be suitable for prophylactic use against stroke. To clarify this issue, melatonin was administrated orally for 9 wk (4 mg/kg/day) in mice and its effects on subsequent injury development after 90 min of intraluminal middle cerebral artery (MCA) occlusion were tested. To evaluate its neuroprotective properties, the protective actions of prophylactic melatonin were compared with both acute melatonin (4 mg/kg, i.p.) administration and with a diluent (sham)‐treated control condition. MCA occlusion resulted in reproducible ischemia, as revealed by laser Doppler flowmetry; this was followed by a rapid restoration of blood flow immediately after reperfusion onset. Laser Doppler flow values after reperfusion onset were moderately elevated by melatonin, both when the indole was given prophylactically and when acutely administrated after stroke. In control animals, reproducible brain infarcts were observed 24 hr after reperfusion onset. Treatment with melatonin significantly reduced the infarct size by ∼30–35%, independent of whether the indole was given prophylactically before or acutely after ischemia. To test whether brain protection involved vascular mechanisms, as suggested earlier, the effects of melatonin on endothelin converting enzyme‐1 (ECE‐1) levels were studied using Western blots. Interestingly, delivery of melatonin was accompanied by a marked inhibition of ECE‐1 levels, which was similarly seen after both acute and chronic melatonin treatment. Our data suggest that melatonin, given at pharmacological doses, may be suitable as a prophylaxis against stroke. Tissue protection may involve an inhibition of ECE‐1, which improves vasodilation, after ischemia.
Protective effect of melatonin on 3‐nitropropionic acid‐induced oxidative stress in synaptosomes in an animal model of Huntington's disease
Authors: Túnez Isaac , Montilla Pedro , Del Carmen Muñoz M. , Feijóo Montserrat , Salcedo Manuel
Published: October 2004

Abstract:  The effect of melatonin (1 mg/kg BW i.p./day) on the oxidative changes produced by 3‐nitropropionic acid (20 mg/kg BW/day for 4 days) in rat striatal and cortical synaptosomes was investigated. The effects of 3‐nitropropionic acid were evaluated as changes in the quantity of lipid peroxidation products, protein carbonyl groups and superoxide dismutase and succinate dehydrogenase activities. 3‐Nitropropionic acid caused a rise in lipid peroxidation levels and protein carbonyls content whereas it induced a reduction in the activity of succinate dehydrogenase and triggered an enhancement in superoxide dismutase activity. These changes were prevented by previous administration of melatonin. Our results reveal: (i) 3‐nitropropionic acid induces a status of oxidative stress in some brain regions of the Wistar rat; (ii) melatonin prevents the deleterious effects induced by the acid. In conclusion, the results show the ability of melatonin to modify the neural response to 3‐nitropropionic acid with the protective mechanism likely involving the antioxidative processes of melatonin.
Melatonin protects against pancreaticobiliary inflammation and associated remote organ injury in rats: role of neutrophils
Authors: Barlas Afşar , Çevik Hülya , Arbak Serap , Bangir Dilek , Şener Göksel , Yeğen Cumhur , Yeğen Berrak Ç.
Published: October 2004

Abstract:  Although the role of oxidative stress in acute pancreatitis (AP) has been studied in several animal models, little data are available regarding AP induced by pancreatic duct obstruction. We characterized the protective effects of melatonin on pancreaticobiliary inflammation and associated remote organ injury. In Sprague–Dawley rats, either the common pancreaticobiliary duct (PBDL; n = 28) or bile duct (BDL; n = 28) was ligated or a sham operation was applied (n = 14). Either melatonin (10 mg/kg) or vehicle (saline; 1 mL/kg) was administered intraperitoneally (i.p.) immediately before the surgery and twice a day until the rats were decapitated at 6 or 72 h. The pancreas, liver, kidneys and lungs were removed and tissue samples were stored for the determination of malondialdehyde (MDA) and glutathione (GSH) levels and myelopreoxidase activity. The results demonstrate that pathogenesis of acute obstructive pancreatitis involves not only the oxidative damage of the pancreatic and hepatic tissues, as assessed by increased MDA and reduced GSH levels, but the lungs and kidneys are also challenged by oxidant injury. Similarly, hepatic oxidative injury caused by cholestasis was also accompanied by pulmonary, renal and even pancreatic damage. The biochemical findings were also verified histologically. Melatonin, probably because of its free‐radical scavenging and antioxidant activity, which involves an inhibitory effect on tissue neutrophil infiltration, protected all the affected tissues.
The influence of fatigue on damage from eccentric contractions in the gastrocnemius muscle of the cat
Authors: Morgan D. L. , Gregory J. E. , Proske U.
Published: October 2004

Eccentric exercise is unique in that it can lead to muscle damage and soreness. Concentric exercise is not accompanied by evidence of damage. There are reports in the literature that muscle fatigue is a factor determining the amount of damage from eccentric exercise. Our theory for the damage process predicts that susceptibility for damage is independent of fatigue. Experiments were carried out to test this prediction as well as to seek other evidence in support of our theory. Comparisons were made between the effects of eccentric and concentric contractions. The nerve supply to the medial gastrocnemius muscle of the anaesthetized cat was divided into three equal portions in terms of the tension they generated. In the first experiment a muscle portion was fatigued by giving it 200 shortening contractions over 12 mm at a shortening speed of 50 mm s−1. This led to a mean fall in isometric tension (37 ± 4%) without a significant shift in the optimum length for peak active tension. Giving the fatigued muscle 10 eccentric contractions, active stretches over 6 mm at 50 mm s−1, beginning from the muscle's optimum length led to a further fall in tension (11%± 7%) and a significant shift in optimum length (3.7 mm ± 0.6 mm) in the direction of longer muscle lengths. The shift in optimum was taken as an indicator of muscle damage. This shift was not significantly different from that seen after eccentric contractions carried out on an unfatigued muscle. After a series of eccentric or concentric contractions, tension at the end of a ramp shortening of 6 mm at 10 mm s−1 fell more than isometric tension, and by near equal amounts for the two kinds of contractions. In an unfatigued muscle, if tension was altered by changing the rate of stimulation, the fall in shortening tension was greater than after either concentric or eccentric contractions. These observations were seen to be consistent with predictions of the proposed mechanism for the damage process.
Histamine innervation and activation of septohippocampal GABAergic neurones: involvement of local ACh release
Authors: Xu Changqing , Michelsen Kimmo A. , Wu Min , Morozova Elena , Panula Pertti , Alreja Meenakshi
Published: October 2004

Recent studies indicate that the histaminergic system, which is critical for wakefulness, also influences learning and memory by interacting with cholinergic systems in the brain. Histamine‐containing neurones of the tuberomammillary nucleus densely innervate the cholinergic and GABAergic nucleus of the medial septum/diagonal band of Broca (MSDB) which projects to the hippocampus and sustains hippocampal theta rhythm and associated learning and memory functions. Here we demonstrate that histamine, acting via H1 and/or H2 receptor subtypes, utilizes direct and indirect mechanisms to excite septohippocampal GABA‐type neurones in a reversible, reproducible and concentration‐dependent manner. The indirect mechanism involves local ACh release, is potentiated by acetylcholinesterase inhibitors and blocked by atropine methylbromide and 4‐DAMP mustard, an M3 muscarinic receptor selective antagonist. This indirect effect, presumably, results from a direct histamine‐induced activation of septohippocampal cholinergic neurones and a subsequent indirect activation of the septohippocampal GABAergic neurones. In double‐immunolabelling studies, histamine fibres were found in the vicinity of both septohippocampal cholinergic and GABAergic cell types. These findings have significance for Alzheimer's disease and other neurodegenerative disorders involving a loss of septohippocampal cholinergic neurones as such a loss would also obtund histamine effects on septohippocampal cholinergic and GABAergic functions and further compromise hippocampal arousal and associated cognitive functions.
Histidine‐stimulated divalent metal uptake in human erythrocytes and in the erythroleukaemic cell line HEL.92.1.7
Authors: Oakley F. , Horn N. M. , Thomas A. L.
Published: October 2004

The uptake of 65Zn by human erythrocytes was investigated in the presence of high (40 mm) and low (5 mm) concentrations of histidine and 0–500 μm cobalt, nickel, manganese and zinc. Varying concentrations of metal mono‐ and bis‐histidine complexes will be formed and the inhibition of 65Zn uptake could be correlated with the calculated complex concentrations to investigate competition between metals. For each metal, the calculated concentrations of bis‐histidine complex giving 50% inhibition of 65Zn uptake were similar at both 5 mm and 40 mm histidine. Manganese–bis‐histidine appeared to have a much higher affinity for the binding site than the other metal–bis‐histidine complexes, which had similar affinities to each other. Studies of the inhibition of histidine‐stimulated 54Mn uptake by the addition of manganese confirmed that manganese–bis‐histidine does act as a substrate for the transporter in a similar fashion to the other metals studied. In addition, human erythroleukaemic cells (HEL cells) were used as a model for erythroid precursor cells. l‐histidine, but not d‐histidine, stimulated 65Zn uptake in a saturable fashion. The other metals competed with zinc in a similar manner to that seen in erythrocytes, and the affinity for manganese–bis‐histidine was much greater than for the bis‐histidine complexes of the other three metals. Both the capacity for metal transport per cell, and the affinity of the transporter for the metal–bis‐histidine complexes, were much greater in the HEL cells than in the erythrocyte. It is suggested that histidine‐stimulated metal transport may play a role in the supply of metals to maturing erythroid cells.
Effects of angiotensin II on the pericyte‐containing microvasculature of the rat retina
Authors: Kawamura Hajime , Kobayashi Masato , Li Qing , Yamanishi Shigeki , Katsumura Kozo , Minami Masahiro , Wu David M. , Puro Donald G.
Published: October 2004

The aim of this study was to identify the mechanisms by which angiotensin II alters the physiology of the pericyte‐containing microvasculature of the retina. Despite evidence that this vasoactive signal regulates capillary perfusion by inducing abluminal pericytes to contract and thereby microvascular lumens to constrict, little is known about the events linking angiotensin exposure with pericyte contraction. Here, using microvessels freshly isolated from the adult rat retina, we monitored pericyte currents via perforated‐patch pipettes, measured pericyte calcium levels with fura‐2 and visualized pericyte contractions and lumen constrictions by time‐lapse photography. We found that angiotensin activates nonspecific cation (NSC) and calcium‐activated chloride channels; the opening of these channels induces a depolarization that is sufficient to activate the voltage‐dependent calcium channels (VDCCs) expressed in the retinal microvasculature. Associated with these changes in ion channel activity, intracellular calcium levels rise, pericytes contract and microvascular lumens narrow. Our experiments revealed that an influx of calcium through the NSC channels is an essential step linking the activation of AT1 angiotensin receptors with pericyte contraction. Although not required in order for angiotensin to induce pericytes to contract, calcium entry via VDCCs serves to enhance the contractile response of these cells. In addition to activating nonspecific cation, calcium‐activated chloride and voltage‐dependent calcium channels, angiotensin II also causes the functional uncoupling of pericytes from their microvascular neighbours. This inhibition of gap junction‐mediated intercellular communication suggests a previously unappreciated complexity in the spatiotemporal dynamics of the microvascular response to angiotensin II.
Modulation of cytosolic and intra‐sarcoplasmic reticulum calcium waves by calsequestrin in rat cardiac myocytes
Authors: Kubalova Zuzana , Györke Inna , Terentyeva Radmila , Viatchenko‐Karpinski Serge , Terentyev Dmitry , Williams Simon C. , Györke Sandor
Published: October 2004

Waves of Ca2+‐induced Ca2+ release occur in various cell types and are involved in the pathology of certain forms of cardiac arrhythmia. These arrhythmias include catecholaminergic polymorphic ventricular tachycardia (CPVT), certain cases of which are associated with mutations in the cardiac calsequestrin gene (CASQ2). To explore the mechanisms of Ca2+ wave generation and unravel the underlying causes of CPVT, we investigated the effects of adenoviral‐mediated changes in CASQ2 protein levels on the properties of cytosolic and sarcoplasmic reticulum (SR) Ca2+ waves in permeabilized rat ventricular myocytes. The free [Ca2+] inside the sarcoplasmic reticulum ([Ca2+]SR) was monitored by fluo‐5N entrapped into the SR, and cytosolic Ca2+ was imaged using fluo‐3. Overexpression of CASQ2 resulted in significant increases in the amplitude of Ca2+ waves and interwave intervals, whereas reduced CASQ2 levels caused drastic reductions in the amplitude and period of Ca2+ waves. CASQ2 abundance had no impact on resting diastolic [Ca2+]SR or on the amplitude of the [Ca2+]SR depletion signal during the Ca2+ wave. However, the recovery dynamics of [Ca2+]SR following Ca2+ release were dramatically altered as the rate of [Ca2+]SR recovery increased ∼3‐fold in CASQ2‐overexpressing myocytes and decreased to 30% of control in CASQ2‐underexpressing myocytes. There was a direct linear relationship between Ca2+ wave period and the half‐time of basal [Ca2+]SR recovery following Ca2+ release. Loading the SR with the low affinity exogenous Ca2+ buffer citrate exerted effects quantitatively similar to those observed on overexpressing CASQ2. We conclude that free intra‐SR [Ca2+] is a critical determinant of cardiac Ca2+ wave generation. Our data indicate that reduced intra‐SR Ca2+ binding activity promotes the generation of Ca2+ waves by accelerating the dynamics of attaining a threshold free [Ca2+]SR required for Ca2+ wave initiation, potentially accounting for arrythmogenesis in CPVT linked to mutations in CASQ2.
Chronic decentralization potentiates neurovascular transmission in the isolated rat tail artery, mimicking the effects of spinal transection
Authors: Yeoh Melanie , McLachlan Elspeth M. , Brock James A.
Published: October 2004

Spinal cord transection produces a marked increase in the response of the isolated rat tail artery to sympathetic nerve stimulation, possibly as a result of a decrease in ongoing sympathetic activity. We have tested the effects of removing ongoing nerve activity on neurovascular transmission by cutting the preganglionic input to postganglionic neurones supplying the tail artery (decentralization). Isometric contractions to nerve stimulation were compared between decentralized arteries and those from age‐matched and sham‐operated controls. Nerve‐evoked responses of decentralized arteries were much larger than those of control arteries at 2 and 7 weeks post operatively. The extent of blockade of nerve‐evoked contraction by α‐adrenoceptor antagonists prazosin (10 nm) or idazoxan (0.1 μm) was reduced. Decentralized arteries were transiently supersensitive to the α1‐adrenoceptor agonist phenylephrine and the α2‐adrenoceptor agonist clonidine; the unchanged sensitivity to methoxamine and phenylephrine after 2 weeks indicated no effect on the neuronal noradrenaline uptake transporter. Decentralized arteries were hypersensitive to α,β methylene‐ATP, but the P2‐purinoceptor antagonist suramin (0.1 mm) did not reduce nerve‐evoked contractions. Enlarged responses to 60 mm K+ after both 2 and 7 weeks were correlated with the response of the arteries to nerve stimulation, suggesting that increased postjunctional reactivity contributes to the enhanced contraction. Comparison between data from decentralized arteries and our previous data from spinalized animals showed that the two lesions similarly potentiate nerve‐evoked contractions and have similar but not identical postjunctional effects. The enhanced vascular responses following a reduction in tonic nerve activity may contribute to the hypertensive episodes of autonomic dysreflexia in spinally injured patients.
The effects of hypoxia on the modulation of human TREK‐1 potassium channels
Authors: Caley Alex J. , Gruss Marco , Franks Nicholas P.
Published: October 2004

Two‐pore‐domain potassium channels are a family of ion channels that are widely believed to play an important role in maintaining and regulating neuronal excitability. It has been shown that they can be modulated by an extraordinarily diverse range of endogenous and exogenous factors. One particular member of the family, TREK‐1 (also known as KCNK2), is activated by increasing temperature, membrane stretch and internal acidosis, but is also sensitive to the presence of certain polyunsaturated fatty acids (such as arachidonic acid), neuroprotectants (such as riluzole) and volatile and gaseous general anaesthetics (such as halothane and nitrous oxide). It has recently been reported that TREK‐1 channels are also affected by oxygen concentrations, and that at the levels of hypoxia that occur in the normal human brain, the channels greatly change their properties and, for example, lose their ability to be modulated by arachidonic acid and internal acidosis. These reports seriously challenge the idea that TREK‐1 is a target for general anaesthetics and neuroprotectants. However, in this report we show that TREK‐1 is not oxygen sensitive, and its ability to be activated by anaesthetics, arachidonic acid and internal acidosis remains unaltered under conditions of hypoxia. We further show that the protocol used by previous workers to prepare hypoxic solutions of arachidonic acid results in the removal of the compound from solution.
DOE FE Distributed Generation Program
Authors: Williams Mark C. , Utz Bruce R. , Moore Kevin M.
Published: October 2004

The U.S. Department of Energy’s (DOE) Office of Fossil Energy’s (FE) National Energy Technology Laboratory (NETL), in partnership with private industries, is leading the development and demonstration of high efficiency solid oxide fuel cells (SOFCs) and fuel cell turbine hybrid power generation systems for near term distributed generation (DG) markets with an emphasis on premium power and high reliability. NETL is partnering with Pacific Northwest National Laboratory (PNNL) in developing new directions in research under the Solid-State Energy Conversion Alliance (SECA) initiative for the development and commercialization of modular, low cost, and fuel flexible SOFC systems. The SECA initiative, through advanced materials, processing and system integration research and development, will bring the fuel cell cost to $400 per kilowatt (kW) for stationary and auxiliary power unit (APU) markets. The President of the U.S. has launched us into a new hydrogen economy. The logic of a hydrogen economy is compelling. The movement to a hydrogen economy will accomplish several strategic goals. The U.S. can use its own domestic resources—solar, wind, hydro, and coal. The U.S. uses 20 percent of the world’s oil but has only 3 percent of resources. Also, the U.S. can reduce green house gas emissions. Clear Skies and Climate Change initiatives aim to reduce carbon dioxide (CO2), nitrogen oxides (NOx), and sulfur dioxide (SO2) emissions. SOFCs have no emissions, so they figure significantly in these DOE strategies. In addition, DG—SOFCs, reforming, energy storage—has significant benefit for enhanced security and reliability. The use of fuel cells in cars is expected to bring about the hydrogen economy. However, commercialization of fuel cells is expected to proceed first through portable and stationary applications. This logic says to develop SOFCs for a wide range of stationary and APU applications, initially for conventional fuels, then switch to hydrogen. Like all fuel cells, the SOFC will operate even better on hydrogen than conventional fuels. The SOFC hybrid is a key part of the FutureGen plants. FutureGen is a major new Presidential initiative to produce hydrogen from coal. The highly efficient SOFC hybrid plant will produce electric power and other parts of the plant could produce hydrogen and sequester CO2. The hydrogen produced can be used in fuel cell cars and for SOFC DG applications.
Oxidation Induced Lifetime Limits of Chromia Forming Ferritic Interconnector Steels
Authors: Huczkowski P. , Christiansen N. , Shemet V. , Piron-Abellan J. , Singheiser L. , Quadakkers W. J.
Published: October 2004

For planar solid oxide fuel cell (SOFC) designs chromia forming ferritic steels are being considered as possible construction materials for the interconnections. In accordance with SOFC market requirements it is in many cases necessary to reduce the size of the fuel cell and thus the thickness of the interconnect. Therefore, long term, cyclic oxidation studies of ferritic interconnector steels were carried out at 800°C and 900°C in air thereby putting main emphasis on the effect of specimen thickness on the oxidation behaviour. It was observed that with decreasing sample thickness the life time of the mentioned alloys decreases due to breakaway phenomena. This effect is caused by the smaller chromium reservoir in the alloy in case of thinner components. The observed life time limits can be predicted with reasonable accuracy by a theoretical model, using oxide growth rate parameters, initial alloy Cr content and critical Cr content for protective chromia scale formation. It also has to be taken into account that the oxidation rates of the steels increase with decreasing specimen thickness.
Prevention of Vaginal SHIV Transmission in Rhesus Macaques Through Inhibition of CCR5
Authors: Lederman Michael M. , Veazey Ronald S. , Offord Robin , Mosier Donald E. , Dufour Jason , Mefford Megan , Piatak Michael , Lifson Jeffrey D. , Salkowitz Janelle R. , Rodriguez Benigno , Blauvelt Andrew , Hartley Oliver
Published: October 2004

Topical agents, such as microbicides, that can protect against human immunodeficiency virus (HIV) transmission are urgently needed. Using a chimeric simian/human immunodeficiency virus (SHIV SF162), which is tropic for the chemokine receptor CCR5, we report that topical application of high doses of PSC-RANTES, an amino terminus–modified analog of the chemokine RANTES, provided potent protection against vaginal challenge in rhesus macaques. These experimental findings have potentially important implications for understanding vaginal transmission of HIV and the design of strategies for its prevention.
Local Endemism Within the Western Ghats-Sri Lanka Biodiversity Hotspot
Authors: Bossuyt Franky , Meegaskumbura Madhava , Beenaerts Natalie , Gower David J. , Pethiyagoda Rohan , Roelants Kim , Mannaert An , Wilkinson Mark , Bahir Mohomed M. , Manamendra-Arachchi Kelum , Ng Peter K. L. , Schneider Christopher J. , Oommen Oommen V. , Milinkovitch Michel C.
Published: October 2004

The apparent biotic affinities between the mainland and the island in the Western Ghats–Sri Lanka biodiversity hotspot have been interpreted as the result of frequent migrations during recent periods of low sea level. We show, using molecular phylogenies of two invertebrate and four vertebrate groups, that biotic interchange between these areas has been much more limited than hitherto assumed. Despite several extended periods of land connection during the past 500,000 years, Sri Lanka has maintained a fauna that is largely distinct from that of the Indian mainland. Future conservation programs for the subcontinent should take into account such patterns of local endemism at the finest scale at which they may occur.
Cognitive Memory: Cellular and Network Machineries and Their Top-Down Control
Authors: Miyashita Yasushi
Published: October 2004

A brain-wide distributed network orchestrates cognitive memorizing and remembering of explicit memory (i.e., memory of facts and events). The network was initially identified in humans and is being systematically investigated in molecular/genetic, single-unit, lesion, and imaging studies in animals. The types of memory identified in humans are extended into animals as episodic-like (event) memory or semantic-like (fact) memory. The unique configurational association between environmental stimuli and behavioral context, which is likely the basis of episodic-like memory, depends on neural circuits in the medial temporal lobe, whereas memory traces representing repeated associations, which is likely the basis of semantic-like memory, are consolidated in the domain-specific regions in the temporal cortex. These regions are reactivated during remembering and contribute to the contents of a memory. Two types of retrieval signal reach the cortical representations. One runs from the frontal cortex for active (or effortful) retrieval (top-down signal), and the other spreads backward from the medial temporal lobe for automatic retrieval. By sending the top-down signal to the temporal cortex, frontal regions manipulate and organize to-be-remembered information, devise strategies for retrieval, and also monitor the outcome, with dissociated frontal regions making functionally separate contributions. The challenge is to understand the hierarchical interactions between these multiple cortical areas, not only with a correlational analysis but also with an interventional study demonstrating the causal necessity and the direction of the causality.
A Network of Superconducting Gravimeters Detects Submicrogal Coseismic Gravity Changes
Authors: Imanishi Yuichi , Sato Tadahiro , Higashi Toshihiro , Sun Wenke , Okubo Shuhei
Published: October 2004

With high-resolution continuous gravity recordings from a regional network of superconducting gravimeters, we have detected permanent changes in gravity acceleration associated with a recent large earthquake. Detected changes in gravity acceleration are smaller than 10
–8
meters seconds
–2
(1 micro-Galileo, about 10
–9
times the surface gravity acceleration) and agree with theoretical values calculated from a dislocation model. Superconducting gravimetry can contribute to the studies of secular gravity changes associated with tectonic processes.
Chronic Immune Activation Associated with Chronic Helminthic and Human Immunodeficiency Virus Infections: Role of Hyporesponsiveness and Anergy
Authors: Borkow Gadi , Bentwich Zvi
Published: October 2004

Chronic immune activation is one of the hallmarks of human immunodeficiency virus (HIV) infection. It is present also, with very similar characteristics, in very large human populations infested with helminthic infections. We have tried to review the studies addressing the changes in the immune profiles and responses of hosts infected with either one of these two chronic infections. Not surprisingly, several of the immune derangements and impairments seen in HIV infection, and considered by many to be the “specific” effects of HIV, can be found in helminth-infected but HIV-noninfected individuals and can thus be accounted for by the chronic immune activation itself. A less appreciated element in chronic immune activation is the immune suppression and anergy which it may generate. Both HIV and helminth infections represent this aspect in a very wide and illustrative way. Different degrees of anergy and immune hyporesponsiveness are present in these infections and probably have far-reaching effects on the ability of the host to cope with these and other infections. Furthermore, they may have important practical implications, especially with regard to protective vaccinations against AIDS, for populations chronically infected with helminths and therefore widely anergic. The current knowledge of the mechanisms responsible for the generation of anergy by chronic immune activation is thoroughly reviewed.
Immunopathogenesis of Oropharyngeal Candidiasis in Human Immunodeficiency Virus Infection
Authors: de Repentigny Louis , Lewandowski Daniel , Jolicoeur Paul
Published: October 2004

Oropharyngeal and esophageal candidiases remain significant causes of morbidity in human immunodeficiency virus (HIV)-infected patients, despite the dramatic ability of antiretroviral therapy to reconstitute immunity. Notable advances have been achieved in understanding, at the molecular level, the relationships between the progression of HIV infection, the acquisition, maintenance, and clonality of oral candidal populations, and the emergence of antifungal resistance. However, the critical immunological defects which are responsible for the onset and maintenance of mucosal candidiasis in patients with HIV infection have not been elucidated. The devastating impact of HIV infection on mucosal Langerhans' cell and CD4+cell populations is most probably central to the pathogenesis of mucosal candidiasis in HIV-infected patients. However, these defects may be partly compensated by preserved host defense mechanisms (calprotectin, keratinocytes, CD8+T cells, and phagocytes) which, individually or together, may limit Candida albicans proliferation to the superficial mucosa. The availability of CD4C/HIV transgenic mice expressing HIV-1 in immune cells has provided the opportunity to devise a novel model of mucosal candidiasis that closely mimics the clinical and pathological features of candidal infection in human HIV infection. These transgenic mice allow, for the first time, a precise cause-and-effect analysis of the immunopathogenesis of mucosal candidiasis in HIV infection under controlled conditions in a small laboratory animal.
Treatment of Infections Caused by Metronidazole-ResistantTrichomonas vaginalis
Authors: Cudmore Sarah L. , Delgaty Kiera L. , Hayward-McClelland Shannon F. , Petrin Dino P. , Garber Gary E.
Published: October 2004

Infections with the sexually transmitted protozoanTrichomonas vaginalisare usually treated with metronidazole, a 5-nitroimidazole drug derived from the antibiotic azomycin. Metronidazole treatment is generally efficient in eliminatingT. vaginalisinfection and has a low risk of serious side effects. However, studies have shown that at least 5% of clinical cases of trichomoniasis are caused by parasites resistant to the drug. The lack of approved alternative therapies forT. vaginalistreatment means that higher and sometimes toxic doses of metronidazole are the only option for patients with resistant disease. Clearly, studies of the treatment and prevention of refractory trichomoniasis are essential. This review describes the mechanisms of metronidazole resistance inT. vaginalisand provides a summary of trichomonicidal and vaccine candidate drugs.