Constituents of red yeast rice, a traditional Chinese food and medicine

Detailed analyses were undertaken of the natural constituents of red yeast rice, a traditional Chinese medicine and food known for centuries to improve blood circulation. Preparation of red yeast rice following ancient methods by fermenting the fungal strain Monascus purpureus Went on moist and sterile rice indicated the presence of a group of metabolites belonging to the monacolin family of polyketides, together with fatty acids, and trace elements. The presence of these compounds may explain in part the cholesterol-lowering ability associated with this traditional Chinese food.

Lobar intracerebral hemorrhage model in pigs: rapid edema development in perihematomal white matter

BACKGROUND AND PURPOSE

The mechanisms underlying brain injury from intracerebral hemorrhage (ICH) are complex and poorly understood. To comprehensively examine pathophysiological and pathochemical alterations after ICH and to examine the effects of hematoma removal on these processes, we developed a physiologically controlled, reproducible, large-animal model of ICH in pigs (weight, 6 to 8 kg).

METHODS

We produced lobar hematomas by pressure- controlled infusions of 1.7 mL of autologous blood into the right frontal hemispheric white matter over 15 minutes. We froze brains in situ at 1, 3, 5, and 8 hours after hematoma induction and cut coronal sections of hematoma assessment, morphological brain examination, and immunohistochemical and water content determinations.

RESULTS

At 1 hour after blood infusion, "translucent" white matter areas were present directly adjacent to the hematoma. These markedly edematous regions had a greater than 10% increase in water content (>85%) compared with the contralateral white matter (73%), and this increased water content persisted through 8 hours. In addition, these areas were strongly immunoreactive for serum proteins. Intravascular Evans blue dye failed to penetrate into the brain tissue at all time points, demonstrating that this serum protein accumulation and edema development were not due to increased blood-brain barrier permeability.

CONCLUSIONS

Experimental lobar ICH in pigs models a prominent pathological feature of human ICH, ie, early perihematomal edema. Our findings suggest that serum proteins, originating from the hematoma, accumulate in adjacent white matter and result in rapid and prolonged edema after ICH. This interstitial edema likely corresponds to the low densities on CT scans and the hyperintensities on T2-weighted MR images that surround intracerebral hematomas acutely after human ICH.

Role of blood clot formation on early edema development after experimental intracerebral hemorrhage

BACKGROUND AND PURPOSE

Blood "toxicity" is hypothesized to induce edema and brain tissue injury following intracerebral hemorrhage (ICH). Lobar ICH in pigs produces rapidly developing, marked perihematomal edema (>10% increase in water content) associated with clot-derived plasma protein accumulation. Coagulation cascade activation and, specifically, thrombin itself contribute to edema development during the first 24 hours after gray matter ICH in rats. In the present study, we sought to determine whether blood clot formation is necessary for edema development by comparing intracerebral infusions of heparinized and unheparinized blood in pig (white matter) and in rat (gray matter). We also examined heparin's effect on thrombin-induced gray matter edema.

METHODS

In pigs, we infused autologous blood (with or without heparin) into the cerebral white matter to produce lobar hematomas and froze the brains in situ at 1, 4, or 24 hours after ICH. We determined hematomal and perihematomal edema volumes on coronal sections by computer-assisted morphometry. In rats, we infused either blood or thrombin (with or without heparin) into the basal ganglia and measured water, sodium, and potassium contents at 24 hours after ICH.

RESULTS

In pigs, unheparinized blood induced rapid (at 1 hour) and prolonged (24 hours) perihematomal edema (average volume, 1.29+/-0. 20 mL; n=6). No perihematomal edema was present following heparinized blood infusions (n=6). In rats, unheparinized blood produced significantly greater edema than heparinized blood infusions. As with whole blood, thrombin-induced gray matter edema at 24 hours was significantly reduced by coinjection of heparin.

CONCLUSIONS

After ICH, blood clot formation is required for rapid and prolonged edema development in perihematomal white and gray matter. Thrombin also contributes to prolonged edema in gray matter.

Attenuation of thrombin-induced brain edema by cerebral thrombin preconditioning

BACKGROUND AND PURPOSE

Edema formation after intracerebral hemorrhage has been linked to thrombin toxicity induced by the clot. However, thrombin at low concentrations actually protects neurons and astrocytes in culture from hypoglycemic and ischemic cell death. It is also known that a brief episode of brain ischemia increases neuronal tolerance to a subsequent severe ischemic episode. The objective of this study was to investigate whether pretreatment of the brain with low-dose thrombin induces tolerance to a subsequent large dose of thrombin injected into brain parenchyma.

METHODS

The rat brain was preconditioned with 1 U thrombin by direct infusion into the right caudate nucleus. After thrombin pretreatment, the effects of a large dose (5 U) of thrombin on brain edema formation were studied at different intervals. We examined whether heat-shock protein (HSP) 27, HSP32, and HSP70 were induced by Western blot analysis, immunocytochemistry, and immunofluorescent double staining.

RESULTS

Thrombin pretreatment significantly attenuated the brain edema that normally follows the infusion of a large dose of thrombin (79.2+/-0.4 versus 84.0+/-0.3; P<0.01). This effect was abolished by the thrombin inhibitor hirudin. Time course studies showed that the maximal effect of thrombin preconditioning (TPC) on brain edema formation was 7 days after pretreatment. This time course corresponded to marked upregulation of HSP27 in the ipsilateral brain. TPC also induced HSP32, but this effect occurred earlier than the effect on edema formation. TPC had no effect on HSP70. Immunocytochemistry and immunofluorescent double labeling showed that HSP27 and HSP32 were expressed in astrocytes after TPC.

CONCLUSIONS

OFF phenomenon of thrombin-induced tolerance of the brain to edema formation may be related to HSP27 induction.

Three SNARE complexes cooperate to mediate membrane fusion

Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins of the syntaxin, SNAP-25, and VAMP families mediate intracellular membrane fusion through the formation of helical bundles that span opposing membranes. Soluble SNARE domains that lack their integral membrane anchors inhibit membrane fusion by forming nonfunctional complexes with endogenous SNARE proteins. In this study we investigate the dependence of membrane fusion on the concentration of a soluble SNARE coil domain derived from VAMP2. The increase in the inhibition of fusion observed with increasing concentration of inhibitor is best fit to a function that suggests three SNARE complexes cooperate to mediate fusion of a single vesicle. These three complexes likely contribute part of a protein and lipidic fusion pore.

Mechanisms of edema formation after intracerebral hemorrhage: effects of extravasated red blood cells on blood flow and blood-brain barrier integrity

BACKGROUND AND PURPOSE

Red blood cell (RBC) lysis contributes to brain edema formation after intracerebral hemorrhage (ICH), and RBC hemolysate (oxyhemoglobin) has been implicated to be a spasminogen in subarachnoid hemorrhage. Whether cerebral ischemia contributes to brain edema formation after ICH remains unclear, however. The aims of this study were to test whether extravasation of RBCs induces cerebral ischemia and/or blood-brain barrier disruption in a rat ICH model characterized by perihematomal brain edema.

METHODS

In this study, 87 pentobarbital-anesthetized Sprague-Dawley rats were used. In each animal, saline, packed RBCs, or lysed RBCs were injected into the right caudate nucleus. Sham injections served as controls. Regional cerebral blood flow, brain water and ion contents, blood-brain barrier integrity, and plasma volume were measured.

RESULTS

Intraparenchymal infusion of lysed RBCs caused severe brain edema by the first day but did not induce ischemic cerebral blood flows. In contrast, blood-brain barrier permeability increased during the first day after infusion of lysed RBCs (a 3-fold increase) and 3 days after infusion of packed RBCs (a 4-fold increase).

CONCLUSIONS

These results suggest that ischemia is not present at 24 or 72 hours after hematoma induction by injection of intact or lysed RBCs. RBC constituents that appear after delayed lysis, however, increase blood-brain barrier permeability, which contributes to edema formation.

Complement activation in the brain after experimental intracerebral hemorrhage

OBJECT

Brain edema formation following intracerebral hemorrhage (ICH) appears to be partly related to erythrocyte lysis and hemoglobin release. Erythrocyte lysis may be mediated by the complement cascade, which then triggers parenchymal injury. In this study the authors examine whether the complement cascade is activated after ICH and whether inhibition of complement attenuates brain edema around the hematoma.

METHODS

This study was divided into three parts. In the first part, 100 microl of autologous blood was infused into the rats' right basal ganglia, and the animals were killed at 24 and 72 hours after intracerebral infusion. Their brains were tested for complement factors C9, C3d, and clusterin (a naturally occurring complement inhibitor) by using immunohistochemical analysis. In the second part of the study, the rats were killed at 24 or 72 hours after injection of 100 microl of blood. The C9 and clusterin proteins were quantitated using Western blot analysis. In the third part, the rats received either 100 microl of blood or 100 microl of blood plus 10 microg of N-acetylheparin (a complement activation inhibitor). Then they were killed 24 or 72 hours later for measurement of brain water and ion contents. It was demonstrated on Western blot analysis that there had been a sixfold increase in C9 around the hematoma 24 hours after the infusion of 100 microl of autologous blood. Marked perihematomal C9 immunoreactivity was detected at 72 hours. Clusterin also increased after ICH and was expressed in neurons 72 hours later. The addition of N-acetylheparin significantly reduced brain edema formation in the ipsilateral basal ganglia at 24 hours (78.5 +/- 0.5% compared with 81.6 +/- 0.8% in control animals, p < 0.001) and at 72 hours (80.9 +/- 2.2% compared with 83.6 +/- 0.9% in control animals, p < 0.05) after ICH.

CONCLUSIONS

It was found that ICH causes complement activation in the brain. Activation of complement and the formation of membrane attack complex contributes to brain edema formation after ICH. Blocking the complement cascade could be an important step in the therapy for ICH.

Blood-brain barrier function in intracerebral hemorrhage

In this paper, we review current knowledge on blood-brain barrier (BBB) dysfunction following intracerebral hemorrhage (ICH). BBB disruption is a hallmark of ICH-induced brain injury. Such disruption contributes to edema formation, the influx of leukocytes, and the entry of potentially neuroactive agents into the perihematomal brain, all of which may contribute to brain injury. A range of factors have been implicated in inducing BBB disruption, including inflammatory mediators (e.g., cytokines and chemokines), thrombin, hemoglobin breakdown products, oxidative stress, complement, and matrix metalloproteinases. While there is interaction between some of these mediators, it is probable that prevention of ICH-induced BBB disruption will involve blocking multiple pathways or blocking a common end pathway (e.g., by stabilizing tight junction structure). While the effects of ICH on BBB passive permeability have been extensively examined, effects on other 'barrier' properties (metabolic and transport functions) have been less well-studied. However, recent data suggests that ICH can affect transport and that this may help protect the BBB and the brain. Indeed, it is possible in small bleeds that BBB disruption may be beneficial, and it is only in the presence of larger bleeds that disruption has detrimental effects.

Selective alterations in glutamate and GABA receptor subunit mRNA expression in dysplastic neurons and giant cells of cortical tubers

The molecular pharmacologic basis of epileptogenesis in cortical tubers in the tuberous sclerosis complex is unknown. Altered transcription of genes encoding glutamatergic and gamma-aminobutyric acid (GABA)-ergic receptors and uptake sites may contribute to seizure initiation and may occur selectively in dysplastic neurons and giant cells. Arrays containing GABA A (GABAAR), GluR, NMDA receptor (NR) subunits, GAD65, the vesicular GABA transporter (VGAT), and the neuronal glutamate transporter (EAAC1) cDNAs were probed with amplified poly (A) mRNA from tubers or normal neocortex to identify changes in gene expression. Increased levels of EAAC1, and NR2B and 2D subunit mRNAs and diminished levels of GAD65, VGAT, GluR1, and GABAAR alpha1 and alpha2 were observed in tubers. Ligand-binding experiments in frozen tuber homogenates demonstrated an increase in functional NR2B-containing receptors. Arrays were then probed with poly (A) mRNA from single, microdissected dysplastic neurons, giant cells, or normal neurons (n = 30 each). Enhanced expression of GluR 3, 4, and 6 and NR2B and 2C subunit mRNAs was noted in the dysplastic neurons, whereas only the NR2D mRNA was upregulated in giant cells. GABAAR alpha1 and alpha2 mRNA levels were reduced in both dysplastic neurons and giant cells compared to control neurons. Differential expression of GluR, NR, and GABAAR mRNAs in tubers reflects cell-specific changes in gene transcription that argue for a distinct molecular phenotype of dysplastic neurons and giant cells and suggests that dysplastic neurons and giant cells make differential contributions to epileptogenesis in the tuberous sclerosis complex.

Ultra-early clot aspiration after lysis with tissue plasminogen activator in a porcine model of intracerebral hemorrhage: edema reduction and blood-brain barrier protection

OBJECT

Ultra-early hematoma evacuation (< 4 hours) after intracerebral hemorrhage (ICH) may reduce mass effect and edema development and improve outcome. To test this hypothesis, the authors induced lobar hematomas in pigs.

METHODS

The authors infused 2.5 ml of blood into the frontal cerebral white matter in pigs weighing 8 to 10 kg. In the treatment group, clots were lysed with tissue plasminogen activator ([tPA], 0.3 mg) and aspirated at 3.5 hours after hematoma induction. Brains were frozen in situ at 24 hours post-ICH and hematomal and perihematomal edema volumes were determined on coronal sections by using computer-assisted morphometry. Hematoma evacuation rapidly reduced elevated cerebral tissue pressure from 12.2+/-1.3 to 2.8+/-0.8 mm Hg. At 24 hours, prior clot removal markedly reduced hematoma volumes (0.40+/-0.10 compared with 1.26+/-0.13 cm3, p < 0.005) and perihematomal edema volumes (0.28+/-0.05 compared with 1.46+/-0.24 cm3, p < 0.005), compared with unevacuated control lesions. Furthermore, no Evans blue dye staining of perihematomal edematous white matter was present in brains in which the hematomas had been evacuated, compared with untreated controls.

CONCLUSIONS

Hematomas were quickly and easily aspirated after treatment with tPA, resulting in significant reductions in mass effect. Hematoma aspiration after fibrinolysis with tPA enabled removal of the bulk of the hematoma (> 70%), markedly reduced perihematomal edema, and prevented the development of vasogenic edema. These findings in a large-animal model of ICH provide support for clinical trials that include the use of fibrinolytic agents and ultra-early stereotactically guided clot aspiration for treating ICH.

Attenuation of ischemic brain edema and cerebrovascular injury after ischemic preconditioning in the rat

Ischemic preconditioning (IPC) induces neuroprotection to subsequent severe ischemia, but its effect on the cerebrovasculature has not been studied extensively. This study evaluated the effects of IPC on brain edema formation and endothelial cell damage that follows subsequent permanent focal cerebral ischemia in the rat. Transient (15 minute) middle cerebral artery occlusion (MCAO) was used for IPC. Three days after IPC or a sham operation, permanent MCAO was induced. Twenty-four hours after permanent MCAO, neurologic deficit, infarction volume, and water and ion content were evaluated. Six hours post-ischemia, blood-brain barrier (BBB) permeability was examined using [3H]-inulin. Water, ion contents, and BBB permeability were assessed in three zones (core, intermediate, and outer) depending on their relation to the MCA territory. Heat shock protein 70 (HSP70) was also examined as a potential marker of vascular injury. The model of IPC significantly reduced brain infarction and neurologic deficit. Compared with a sham operation, IPC also significantly attenuated brain edema formation in the intermediate (sham and IPC water contents: 5.99+/-0.65 vs. 4.99+/-0.81 g/g dry weight; P < 0.01) and outer zones (5.02+/-0.48 vs. 4.37+/-0.42 g/g dry weight; P < 0.01) of the ipsilateral hemisphere but not in the core zone. Blood-brain barrier disruption assessed by [3H]-inulin was significantly attenuated in the IPC group and the number of blood vessels that displayed HSP70 immunoreactivity was also reduced. Thus, IPC significantly attenuates ischemic brain edema formation, BBB disruption, and, as assessed by HSP70, vascular injury. Understanding the mechanisms involved in IPC may provide insight into methods for preserving cerebrovascular function during ischemia.

Systemic complement depletion diminishes perihematomal brain edema in rats

BACKGROUND AND PURPOSE

The complement cascade is activated after experimental intracerebral hemorrhage (ICH). It remains unclear, however, whether depleting the complement system will improve injury resulting from ICH. This study investigated the effects of systemic complement depletion on brain edema formation after ICH.

METHODS

Fifty-six pentobarbital-anesthetized Sprague-Dawley rats were used. Treatment animals were complement-depleted with cobra venom factor (CVF) (intraperitoneally). Control rats received an equal volume of saline injection (intraperitoneally). In both treatment and control rats, autologous blood (100 microL) was infused stereotaxically into the right basal ganglia. Rats were killed 2, 24, or 72 hours later for brain water, ion, and tumor necrosis factor-alpha (TNF-alpha) measurements, for Western blot analysis, and for immunohistochemical studies. Brain edema was quantitated by wet/dry weight. TNF-alpha levels were measured by enzyme-linked immunosorbent assay. Western blot analysis was applied for C9 semiquantification. Immunohistochemistry was used to detect complement C3d, C5a, C9, and myeloperoxidase.

RESULTS

Perihematomal brain edema was reduced by systemic complement depletion at 24 hours (78.8+/-0.6% versus 81.5+/-0.8% in control, P:<0.01) and 72 hours (81.5+/-1.5% versus 83.6+/-0.9% in control, P:<0.05), while cerebellar water content was unaffected (78.2+/-0.3% versus 78.0+/-0. 1%). Complement depletion reduced TNF-alpha production 2 hours after ICH. Immunocytochemistry showed that complement depletion significantly reduced perihematomal C9 deposition, C3d production, and the number of C5a- and myeloperoxidase-positive cells.

CONCLUSIONS

Complement depletion by CVF attenuates brain edema in ICH, indicating that complement activation plays an important role in ICH-induced brain edema. Preventing complement activation may be effective in the treatment of ICH.

Attenuation of intracerebral hemorrhage and thrombin-induced brain edema by overexpression of interleukin-1 receptor antagonist

OBJECT

Adenovirus-mediated overexpression of interleukin-1 receptor antagonist (IL-1ra) attenuates the inflammatory reaction and brain injury that follows focal cerebral ischemia. Recently, an inflammatory reaction after intracerebral hemorrhage (ICH) was identified. In this study the authors examine the hypothesis that overexpression of IL-1ra reduces brain injury (specifically edema formation) after ICH.

METHODS

Adenoviruses expressing IL-1ra (Ad.RSVIL-1ra) or LacZ, a control protein (Ad.RSVlacZ), or saline were injected into the left lateral cerebral ventricle in rats. On the 5th day after virus injection, 100 microl of autologous blood or 5 U thrombin was infused into the right basal ganglia. Rats with ICH were killed 24 or 72 hours later for measurement of brain water and ion content. Thrombin-treated rats were killed 24 hours later for edema measurements and an assessment of polymorphonuclear leukocyte (PMNL) infiltration by myeloperoxidase (MPO) assay, as well as histological evaluation. Compared with saline-treated and Ad.RSVlacZ-transduced controls, Ad.RSVIL-1ra-transduced rats had significantly attenuated edema in the ipsilateral basal ganglia 3 days after ICH (81.5 +/- 0.3% compared with 83.4 +/- 0.4% and 83.3 +/- 0.5% in control animals). Thrombin-induced brain edema was also reduced in Ad.RSVIL-1ra-treated rats (81.3 +/- 0.4% compared with 83.2 +/- 0.4% and 82.5 +/- 0.4% in control rats). The reduction in thrombin-induced edema was associated with a reduction in PMNL infiltration into the basal ganglia, as assessed by MPO assay (49% reduction) and histological examination.

CONCLUSIONS

Overexpression of IL-1ra by using an adenovirus vector attenuated brain edema formation and thrombin-induced intracerebral inflammation following ICH. The reduction in ICH-induced edema with IL-1ra may result from reduction of thrombin-induced brain inflammation.

Three-dimensional solution structure of Callinectes sapidus metallothionein-1 determined by homonuclear and heteronuclear magnetic resonance spectroscopy

Metallothionein is a cysteine-rich metal-binding protein whose biosynthesis is closely regulated by the level of exposure of an organism to zinc, copper, cadmium, and other metal salts. The metallothionein from Callinectes sapidus is known to bind six divalent metal ions in two separate metal-binding clusters. Heteronuclear 1H-113Cd and homonuclear 1H-1H NMR correlation experiments have been used to establish that the two clusters reside in two distinct protein domains. The three-dimensional solution structure of the metallothionein has been determined using the distance and angle constraints derived from these two-dimensional NMR data sets and a distance geometry/simulated annealing protocol. There are no interdomain short distance (< or = 4.5 A) constraints observed in this protein, enabling the calculation of structures for the N-terminal, beta domain and the C-terminal, alpha domain separately. A total of 18 structures were obtained for each domain. The structures are based on a total of 364 experimental NMR restraints consisting of 277 approximate interproton distance restraints, 12 chi 1 and 51 phi angular restraints, and 24 metal-to-cysteine connectivities obtained from 1H-113Cd correlation experiments. The only element of regular secondary structure in either of the two domains is a short segment of helix in the C-terminal alpha domain between Lys42 and Thr48. The folding of the polypeptide backbone chain in each domain, however, gives rise to several type I beta turns. There are no type II beta turns.

Microglial activation and brain injury after intracerebral hemorrhage

Microglial activation and thrombin formation contribute to brain injury after intracerebral hemorrhage (ICH). Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1beta) are 2 major proinflammatory cytokines. In this study, we investigated whether thrombin stimulates TNF-alpha and IL-1beta secretion in vitro, and whether microglial inhibition reduces ICH-induced brain injury in vivo. There were 2 parts to this study. In the first part, cultured rat microglial cells were treated with vehicle, thrombin (5 and 10U/mL), or thrombin plus tuftsin (0.05 microg/mL), an inhibitor of microglia activation. Levels of TNF-alpha and IL-1beta in culture medium were measured by ELISA at 4, 8, and 24 h after thrombin treatment. In the second part of the study, rats received an intracerebral infusion of 100 microL autologous whole blood with or without 25 microg of tuftsin 1-3 fragment. Rats were killed at day 1 or day 3 for immunohistochemistry and brain water content measurement. We found that thrombin receptors were expressed in cultured microglia cells, and TNF-alpha and IL-1beta levels in the culture medium were increased after thrombin treatment. Tuftsin reduced thrombin-induced upregulation of TNF-alpha and IL-1beta. In vivo, microglia were activated after ICH, and intracerebral injection of tuftsin reduced brain edema in the ipsilateral basal ganglia (81.1 +/- 0.7% vs. 82.7 +/- 1.3% in vehicle-treated group; p < 0.05) after ICH. These results suggest a critical role of microglia activation in ICH-related brain injury.

Early metabolic alterations in edematous perihematomal brain regions following experimental intracerebral hemorrhage

OBJECT

The authors previously demonstrated, in a large-animal intracerebral hemorrhage (ICH) model, that markedly edematous ("translucent") white matter regions (> 10% increases in water contents) containing high levels of clot-derived plasma proteins rapidly develop adjacent to hematomas. The goal of the present study was to determine the concentrations of high-energy phosphate, carbohydrate substrate, and lactate in these and other perihematomal white and gray matter regions during the early hours following experimental ICH.

METHODS

The authors infused autologous blood (1.7 ml) into frontal lobe white matter in a physiologically controlled model in pigs (weighing approximately 7 kg each) and froze their brains in situ at 1, 3, 5, or 8 hours postinfusion. Adenosine triphosphate (ATP), phosphocreatine (PCr), glycogen, glucose, lactate, and water contents were then measured in white and gray matter located ipsi- and contralateral to the hematomas, and metabolite concentrations in edematous brain regions were corrected for dilution. In markedly edematous white matter, glycogen and glucose concentrations increased two- to fivefold compared with control during 8 hours postinfusion. Similarly, PCr levels increased several-fold by 5 hours, whereas, except for a moderate decrease at 1 hour, ATP remained unchanged. Lactate was markedly increased (approximately 20 micromol/g) at all times. In gyral gray matter overlying the hematoma, water contents and glycogen levels were significantly increased at 5 and 8 hours, whereas lactate levels were increased two- to fourfold at all times.

CONCLUSIONS

These results, which demonstrate normal to increased high-energy phosphate and carbohydrate substrate concentrations in edematous perihematomal regions during the early hours following ICH, are qualitatively similar to findings in other brain injury models in which a reduction in metabolic rate develops. Because an energy deficit is not present, lactate accumulation in edematous white matter is not caused by stimulated anaerobic glycolysis. Instead, because glutamate concentrations in the blood entering the brain's extracellular space during ICH are several-fold higher than normal levels, the authors speculate, on the basis of work reported by Pellerin and Magistretti, that glutamate uptake by astrocytes leads to enhanced aerobic glycolysis and lactate is generated at a rate that exceeds utilization.

Neuronal nitric oxide synthase-derived nitric oxide inhibits neurogenesis in the adult dentate gyrus by down-regulating cyclic AMP response element binding protein phosphorylation

Neuronal nitric oxide synthase, the major nitric oxide synthase isoform in the mammalian brain, is implicated in some developmental processes, including neuronal survival, precursor proliferation and differentiation. However, reports about the role of neuronal nitric oxide synthase in neurogenesis in the adult dentate gyrus are conflicting. Here we show that 5-bromodeoxyuridine-labeled dividing progenitor cells in the dentate gyrus were significantly increased in mice receiving 7-nitroindazole, a selective neuronal nitric oxide synthase inhibitor, and in null mutant mice lacking neuronal nitric oxide synthase gene (nNOS-/-) 6 h and 4 weeks after 5-bromodeoxyuridine incorporation. The increase in 5-bromodeoxyuridine positive cells in 7-nitroindazole-treated mice was accompanied by activation of cyclic AMP response element binding protein phosphorylation in the dentate gyrus. Pretreatment with N-methyl-D-aspartate receptor antagonist MK-801 fully abolished the effects of 7-nitroindazole on neurogenesis and cyclic AMP response element binding protein phosphorylation. Furthermore, neuronal nitric oxide synthase inhibition significantly enhanced the survival of newborn cells and the number of 5-bromodeoxyuridine positive/NeuN positive cells in the dentate gyrus. These results indicate that neuronal nitric oxide synthase-derived nitric oxide suppresses neurogenesis in the adult dentate gyrus, in which N-methyl-D-aspartate receptor functions and cyclic AMP response element binding protein phosphorylation may be involved.

Deferoxamine reduces CSF free iron levels following intracerebral hemorrhage

Iron overload occurs in brain after intracerebral hemorrhage (ICH). Deferoxamine, an iron chelator, attenuates perihematomal edema and oxidative stress in brain after ICH. We investigated the effects of deferoxamine on cerebrospinal fluid (CSF) free iron and brain total iron following ICH. Rats received an infusion of 100-microL autologous whole blood into the right basal ganglia, then were treated with either deferoxamine (100 mg/kg, i.p., administered 2 hours after ICH and then at 12-hour intervals for up to 7 days) or vehicle. The rats were killed at different time points from 1 to 28 days for measurement of free and total iron. Behavioral tests were also performed. Free iron levels in normal rat CSF were very low (1.1 +/- 0.4 micromol). After ICH, CSF free iron levels were increased at all time points. Levels of brain total iron were also increased after ICH (p < 0.05). Deferoxamine given 2 hours after ICH reduced free iron in CSF at all time points. Deferoxamine also reduced ICH-induced neurological deficits (p < 0.05), but did not reduce total brain iron. In conclusion, CSF free iron levels increase after ICH and do not clear for at least 28 days. Deferoxamine reduces free iron levels and improves functional outcome in the rat, indicating that it may be a potential therapeutic agent for ICH patients.

The effects of thrombin preconditioning on focal cerebral ischemia in rats

Our previous studies have shown that prior intracerebral infusion of a low dose of thrombin (thrombin preconditioning; TPC) reduces the brain edema that follows a subsequent intracerebral infusion of a high dose of thrombin or an intracerebral hemorrhage. In vitro studies have also demonstrated that low concentrations of thrombin protect neurons and astrocytes from hypoglycemia and oxidative stress-induced damage. This study, therefore, examines the hypothesis that TPC would offer protection from ischemic brain damage in vivo. This was a blinded design study. The rat brain was preconditioned with 1 U thrombin by direct infusion into the left caudate nucleus. Seven days after thrombin pretreatment, permanent middle cerebral artery occlusion (MCAO) was induced. Twenty-four hours post-ischemia, neurological deficit was evaluated and infarction volume, brain water and ion contents were measured. Compared to saline-treated rats, thrombin pretreatment significantly attenuated brain infarction in cortex (90+/-33 vs. 273+/-22 mm(3); P<0.05) and basal ganglia (56+/-17 vs. 119+/-12 mm(3); P<0.05) that followed 24 h of permanent MCAO. TPC also reduced the brain edema in cortex and basal ganglia by 50 and 53% (P<0.05). Neurological deficit was improved in thrombin pretreatment group (P<0.05). These effects of TPC were, in part, prevented by co-injection of hirudin, a thrombin inhibitor, indicating that the protection was indeed thrombin mediated. Cerebral TPC significantly reduces ischemic brain damage, perhaps by activation of the thrombin receptor. This finding provides a new mechanism by which to study ischemic tolerance.

Iron-induced oxidative brain injury after experimental intracerebral hemorrhage

We investigated the occurrence of DNA damage in brain after intracerebral hemorrhage (ICH) and the role of iron in such injury. Male Sprague-Dawley rats received an infusion of 100 microL autologous whole blood or 30 microL FeCl2 into the right basal ganglia and were sacrificed 1, 3, or 7 days later. 8-hydroxyl-2'-deoxyguanosine (8-OHdG) was analyzed by immunohistochemistry, while the number of apurinic/apyrimidinic abasic sites (AP sites) was also quantified. 8-OHdG and AP sites are two hallmarks of DNA oxidation. DNA damage was also examined using PANT and TUNEL labeling. Dinitrophenyl (DNP) was measured by Western blot to compare the time course of protein oxidative damage to that of DNA. DNA repair APE/Ref-1 and Ku-proteins were also measured by Western blot. Bipyridine, a ferrous iron chelator, was used to examine the role of iron in ICH-induced oxidative brain injury. An increase in 8-OHdG, AP sites, and DNP levels, and a decrease in APE/Ref-1 and Ku levels were observed. Abundant PANT-positive cells were also observed in the perihematomal area 3 days after ICH. Bipyridine attenuated ICH-induced changes in PANT and DNP. These results suggest that iron-induced oxidation causes DNA damage in brain after ICH and that iron is a therapeutic target for ICH.

Effects of carotenoids from Deinococcus radiodurans on protein oxidation

AIMS

To evaluate the antioxidant effect of carotenoids from Deinococcus radiodurans on protein.

METHODS AND RESULTS

Deinococcus radiodurans strain R1 (ATCC 13939) and its mutant strain R1DeltacrtB were used for this study. The total carotenoids (R1ex) from D. radiodurans were obtained by extraction with acetone/methanol (7 : 2, by vol), and their antioxidant activity was measured using the DPPH (2,2-diphenyl-1-picrylhydrazyl) system. The protein oxidation level, in vitro and in the cell, was measured using the DNPH (2,4-dinitrophenyl hydrazine) method. The carotenoid extract R1ex scavenged 40.2% DPPH radicals compared to beta-carotene (31.7%) at a concentration of 0.5 mg ml(-1). The intracellular level of protein oxidation in mutant R1DeltacrtB, which does not contain carotenoid, was 0.0212 mmol mg(-1) protein which is significantly greater than that in the wild type (0.0169 mmol mg(-1) protein) following the treatment with H(2)O(2). The purified major carotenoid product (deinoxanthin) from the wild type showed a greater inhibition of oxidative damage in bovine serum albumin than lycopene or lutein.

CONCLUSIONS

Carotenoids prevent protein oxidation and contribute to the resistance to cell damage in D. radiodurans.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our results provide the evidence that carotenoids can protect proteins in D. radiodurans against oxidative stress.

A metabolite of equine estrogens, 4-hydroxyequilenin, induces DNA damage and apoptosis in breast cancer cell lines

Estrogen replacement therapy has been correlated with an increased risk of developing breast or endometrial cancer. 4-Hydroxyequilenin (4-OHEN) is a catechol metabolite of equilenin which is a minor component of the estrogen replacement formulation marketed under the name of Premarin (Wyeth-Ayerst). Previously, we showed that 4-OHEN autoxidizes to quinoids which can consume reducing equivalents and molecular oxygen, are potent cytotoxins, and cause a variety of damage to DNA, including formation of bulky stable adducts, apurinic sites, and oxidation of the phosphate-sugar backbone and purine/pyrimidine bases [Bolton, J. L., Pisha, E., Zhang, F., and Qiu, S. (1998) Chem. Res. Toxicol. 11, 1113-1127]. All of these deleterious effects could contribute to the cytotoxic and genotoxic effects of equilenin in vivo. In the study presented here, we examined the relative toxicity of 4-OHEN in estrogen receptor (ER) positive cells (MCF-7 and S30) compared to that in breast cancer cells without the estrogen receptor (MDA-MB-231). The data showed that 4-OHEN was 4-fold more toxic to MCF-7 cells (LC(50) = 6.0 +/- 0. 2 microM) and 6-fold more toxic to S30 cells (LC(50) = 4.0 +/- 0.1 microM) than to MDA-MB-231 cells (LC(50) = 24 +/- 0.3 microM). Using the single-cell gel electrophoresis assay (comet assay) to assess DNA damage, we found that 4-OHEN causes concentration-dependent DNA single-strand cleavage in all three cell lines, and this effect could be enhanced by agents which catalyze redox cycling (NADH) or deplete cellular GSH (diethyl maleate). In addition, the ER(+) cell lines (MCF-7 and S30) were considerably more sensitive to induction of DNA damage by 4-OHEN than the ER(-) cells (MDA-MB-231). 4-OHEN also caused a concentration-dependent increase in the amount of mutagenic lesion 8-oxo-dG in the S30 cells as determined by LC/MS-MS. Cell morphology assays showed that 4-OHEN induces apoptosis in these cell lines. As observed with the toxicity assay and the comet assay, the ER(+) cells were more sensitive to induction of apoptosis by 4-OHEN than MDA-MB-231 cells. Finally, the endogenous catechol estrogen metabolite 4-hydroxyestrone (4-OHE) was considerably less effective at inducing DNA damage and apoptosis in breast cancer cell lines than 4-OHEN. Our data suggest that the cytotoxic effects of 4-OHEN may be related to its ability to induce DNA damage and apoptosis in hormone sensitive cells in vivo, and these effects may be potentiated by the estrogen receptor.

Endoplasmic reticulum stress upregulates protein tyrosine phosphatase 1B and impairs glucose uptake in cultured myotubes

AIMS/HYPOTHESIS

Endoplasmic reticulum (ER) stress has been recognised as a common pathway in the development of obesity-associated insulin resistance. Protein tyrosine phosphatase 1B (PTP1B) is a negative regulator of insulin signalling and is localised on the ER membrane. The aim of the study was to investigate the cross-talk between ER stress and PTP1B.

METHODS

Leptin-deficient obese (ob/ob), Ptp1b (also known as Ptpn1) knockout and C57BL/6J mice were subjected to a high-fat or normal-chow diet for 20 weeks. ER stress was induced in cultured myotubes by treatment with tunicamycin. Immunohistochemistry and western blotting were used to assess proteins involved in the ER stress response. Myotube glucose uptake was determined by measuring 2-deoxy[(3)H]glucose incorporation.

RESULTS

A high-fat diet induced ER stress and PTP1B expression in the muscle tissue of mice and these responses were attenuated by treatment with the ER chaperone tauroursodeoxycholic acid (TUDCA). Cultured myotubes exhibited increased levels of PTP1B in response to tunicamycin treatment. Silencing of Ptp1b with small interfering RNA (siRNA) or overexpression of Ptp1b with adenovirus construct failed to alter the levels of ER stress. Ptp1b knockout mice did not differ from the wild-type mice in the extent of tunicamycin-induced upregulation of glucose-regulated protein-78. However, tunicamycin-induced phosphorylation of eukaryotic initiation factor 2α and c-Jun NH(2)-terminal kinase-2 were significantly attenuated in the Ptp1b knockout mice. Treatment with TUDCA or silencing of PTP1B reversed tunicamycin-induced blunted myotube glucose uptake.

CONCLUSIONS/INTERPRETATION

Our data suggest that PTP1B is activated by ER stress and is required for full-range activation of ER stress pathways in mediating insulin resistance in the skeletal muscle.

Capsaicin-induced stimulation of the guinea-pig atrium. Involvement of a novel sensory transmitter or a direct action on myocytes?

The mechanism underlying the positive inotropic and chronotropic effects of capsaicin were investigated using the spontaneously beating guinea-pig atrium in vitro. Capsaicin induced a long-lasting stimulatory effect (threshold dose 10(-9) M). Tetrodotoxin, phentolamine, 6-OHDA, mepyramine plus cimetidine, methysergide-, indomethacin-, somatostatin- or morphine pretreatment and local treatment with capsaicin on the vagal nerves did not reduce the capsaicin response, while it was abolished up to 1 month after systemic capsaicin pretreatment. The capsaicin response was subject to a rapid tachyphylaxis. During capsaicin tachyphylaxis, the positive inotropic and chronotropic effects of noradrenaline, serotonin and histamine were unchanged. Various neuropeptides were investigated with regard to cardiac activity. Physalaemin, eledoisin and somatostatin had negative inotropic and chronotropic effects. Substance P, bombesin, kassinin, CCK-8 or PHI (up to 10(-6)M of each) did not cause any detectable response on the guinea-pig auricle, while the substance P antagonist [D-Arg, D-Pro, D-Trp, Leu]SP induced a long-lasting stimulation of heart activity, VIP also stimulated the heart. Various adenyl compounds were also tested. Adenosine, AMP, ADP, ATP and beta-, gamma-methylene ATP had negative chronotropic and inotropic effects, while alpha-, beta-methylene ATP induced a stimulatory response. During alpha-, beta-methylene ATP tachyphylaxis, the auricles still responded to capsaicin. The inhibitory effects of adenosine and ATP analogues were antagonized by theophylline and 8-p-sulfophenyl theophylline. Capsaicin induced a small release of labelled nucleotides from 3(H)-adenine-prelabelled atria from control, but not from capsaicin-pretreated animals.(ABSTRACT TRUNCATED AT 250 WORDS)