[Study on dopamine D2 binding capacity in vascular parkinsonism]

To investigate whether the striatal dopamine receptor function is involved in the development of vascular parkinsonism (VP), a positron emission tomography (PET) study was conducted on 9 patients with VP by using [11C] N-methylspiperone as the tracer. The rate of binding availability in the striatal dopamine D2 receptor (k3) was determined semiquantitatively, and the values were compared to the predicted normal values based on the results from 7 normal volunteers. Of 9 patients with VP, the normalized D2 receptor binding [%k3] was more than 90% in 5 patients, 89 to 87% in 3, and 75% in one. These values showed no evident correlation with the Hoehn and Yahr stage. The laterality of the striatal %k3 did not correspond to that of the parkinsonism. Thus, the striatal dopamine D2 receptor binding was not severely impaired and did not correlate with the neurological status in patients with VP. This may indicate that striatal dopamine D2 receptor function is not primarily associated with the development of the parkinsonism in VP.

Enhanced generation of reactive oxygen species in the limb skeletal muscles from a murine infarct model of heart failure

BACKGROUND

The generation of reactive oxygen species (ROS) is enhanced in the failing myocardium. We hypothesized that ROS were also increased in the limb skeletal muscles in heart failure. Methods and Results-- Myocardial infarction (MI) was created in mice by ligating the left coronary artery. After 4 weeks, the left ventricle was dilated and contractility was diminished by echocardiography. Left ventricular end-diastolic pressure was elevated after MI in association with an increase in lung weight/body weight and the presence of pleural effusion. The generation of ROS in the limb muscles, including the soleus and gastrocnemius muscles, which were excised after MI, was measured by electron spin resonance spectroscopy with 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl (hydroxy-TEMPO). Overall, generation was increased, but it was attenuated in the presence of dimethylthiourea or 4,5-dihydroxy-1,2-benzenedisulfonic disodium salt in the reaction mixture, indicating increased generation of hydroxyl radicals originating from superoxide anion. Thiobarbituric acid-reactive substance formation was also increased in muscles after MI. Mitochondrial complex I and III activities were both decreased after MI, which may have caused the functional uncoupling of the respiratory chain and ROS production. Antioxidant enzyme activities, including superoxide dismutase, catalase, and glutathione peroxidase, were comparable between groups.

CONCLUSIONS

Skeletal muscle in post-MI heart failure expressed an increased amount of ROS in association with ROS-mediated lipid peroxidation. This supports the hypothesis that oxidative stress may cause (at least in part) skeletal muscle dysfunction in heart failure.

Effects of ACE inhibition on left ventricular failure and oxidative stress in Dahl salt-sensitive rats

Dahl salt-sensitive (DS) rats fed high-salt diet exert compensated left ventricular (LV) hypertrophy and eventually develop heart failure. Oxidative stress has been shown to be involved in myocardial remodeling and failure and thus might play an important role in this transition from hypertrophy to failure. We measured the amount of reactive oxygen species (ROS) in the myocardium from DS rats by using electron spin resonance spectroscopy with 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl (hydroxy-TEMPO) and also examined the effects of chronic angiotensin-converting enzyme (ACE) inhibition on the transition. We divided DS rats (5 weeks old, 150-200 g) into three groups: low-salt (0.3% NaCl) diet for 10 weeks (LS group), high-salt (8% NaCl) diet for 10 weeks (HS-10+V group), and high-salt diet and cilazapril (10 mg/kg body weight per day) started after 5 weeks of high-salt diet and maintained for 5 weeks (HS-10+Cil group). Systolic blood pressure (mm Hg) was significantly elevated in the HS-10+V (229+/-5) and HS-10+Cil (209+/-5) groups compared with the LS group (141+/-2). The amount of myocardial ROS was not changed after 5 weeks of high-salt diet, but significantly increased in HS-10+V rats compared with LS rats, and was abolished in the HS-10+Cil group. HS-10+V rats exerted the clinical signs of heart failure, including increased lung weight and pleural effusion, associated with LV hypertrophy and LV cavity dilatation. In the HS-10+Cil group, signs of heart failure were significantly attenuated despite only a modest reduction in systolic blood pressure (-20 mm Hg). The progression of LV failure after hypertrophy in high-salt-loaded DS hypertensive rats was associated with increased myocardial ROS, and ACE inhibitor could prevent this transition from compensated hypertrophy to failure.

The relationship between the aggregational state of the amyloid-beta peptides and free radical generation by the peptides

In the present study, we investigated whether or not the amyloid-beta protein (Abeta) peptide itself spontaneously generates free radicals using electron spin resonance (ESR) spectroscopy while also monitoring the aggregational state of Abeta and Abeta-induced cytotoxicity. The present results demonstrated a four-line spectrum in the presence of both Abeta40 and Abeta42 with Ntert-butyl-alpha-phenylnitrone (PBN), but not in the presence of PBN alone in phosphate-buffered saline (PBS). The fact that the four-line spectrum obtained for the Abeta/PBN in PBS was completely abolished in the presence of the iron-chelating agent Desferal demonstrated the observed four-line spectrum to be iron-dependent. The present study also revealed that either Abeta40 or Abeta42 with PBN in phosphate buffer (PB) did not produce any definite four-line spectrum. Both a thioflavine-T (Th-T) fluorometric assay and circular dichroism (CD) spectroscopy showed the amyloid fibril formation of Abeta in PBS to be much higher than that of Abeta in PB. Moreover, Abeta-induced cytotoxicity assays showed Abeta incubated in PBS to be more cytotoxic than that incubated in PB. These results thus suggest that Abeta-associated free radical generation is strongly influenced by the aggregational state of the peptides.

The relationship between Abeta-associated free radical generation and Abeta fibril formation revealed by negative stain electron microscopy and thioflavine-T fluorometric assay

In the present study, we investigated whether or not the Abeta peptide itself spontaneously generates free radicals using electron spin resonance (ESR) spectroscopy while also observing the Abeta fibril formation by negative stain electron microscopy. The present results demonstrated a four-line spectrum in the presence of Abeta(1-40) with N-tert-butyl-alpha-phenylnitrone (PBN) but not in the presence of PBN alone in phosphate-buffered saline. Negative stain electron microscopy has shown that Abeta peptides after 96 h of incubation showed more amyloid-like fibrils than those after 72 h of incubation while the four-line spectrum obtained by ESR spectroscopy attained a maximum intensity after 72 h of incubation and thereafter its intensity immediately decreased during the 4-day incubation period. These results were also supported by a thioflavine-T (Th-T) fluorometric assay. In conclusion, the present results suggest that Abeta-associated free radical generation is correlated with Abeta fibril formation while its generation is only observed transiently during the process of Abeta fibril formation.

Requirement for repair of DNA double-strand breaks by homologous recombination in split-dose recovery

Utsumi, H., Tano, K., Takata, M., Takeda, S. and Elkind, M. M. Requirement for Repair of DNA Double-Strand Breaks by Homologous Recombination in Split-Dose Recovery. Radiat. Res. 155, 680-686 (2001). Split-dose recovery has been observed under a variety of experimental conditions in many cell systems and is believed to be the result of the repair of sublethal damage. It is considered to be one of the most widespread and important cellular responses in clinical radiotherapy. To study the molecular mechanism(s) of this repair, we analyzed the knockout mutants KU70-/-, RAD54-/-, and KU70-/-/RAD54-/- of the chicken B-cell line, DT40. RAD54 participates in the recombinational repair of DNA double-strand breaks (DSBs), while members of the KU family of proteins are involved in nonhomologous end joining. Split-dose recovery was observed in the parent DT40 and the KU70-/- cells. Moreover, the split-dose survival enhancement had all of the characteristics demonstrated earlier for the repair of sublethal damage, e.g., the reappearance of the shoulder on the survival curve with dose fractionation; cyclic fluctuation in cell survival at 37 degrees C; repair and no cyclic fluctuation at 25 degrees C. These results strongly suggest that repair of sublethal damage is due to DSB repair mediated by homologous recombination, and that these DNA DSBs constitute sublethal damage.

Effect of the central nervous system on mucosal growth and apoptosis in the small intestine

Recently our studies have demonstrated that the central nervous system regulates in part mucosal cell growth and apoptosis in the rat small intestine. Ornithine decarboxylase (ODC) activity is a key enzyme for polyamine synthesis which plays an important role for the intestinal mucosal growth. We have demonstrated that the increase of ODC activity in the duodenum just before the dark period is abolished by truncal vagotomy and that the infusion of 2-deoxy-D-glucose into the third cerebroventricle activates ODC activity in the small intestine. Epithelial homeostasis is balanced by regulation of cell proliferation and cell death. Our preliminary data showed that intestinal mucosal apoptosis decreased in the ventromedial-hypothalamus-lesioned rat. These results indicate that the central nervous system, in addition to local factors, is related to regulation of mucosal homeostasis in the intestinal mucosa.

Mitochondrial DNA damage and dysfunction associated with oxidative stress in failing hearts after myocardial infarction

Mitochondria are one of the enzymatic sources of reactive oxygen species (ROS) and could also be a major target for ROS-mediated damage. We hypothesized that ROS may induce mitochondrial DNA (mtDNA) damage, which leads to defects of mtDNA-encoded gene expression and respiratory chain complex enzymes and thus may contribute to the progression of left ventricular (LV) remodeling and failure after myocardial infarction (MI). In a murine model of MI and remodeling created by the left anterior descending coronary artery ligation for 4 weeks, the LV was dilated and contractility was diminished. Hydroxyl radicals, which originated from the superoxide anion, and lipid peroxide formation in the mitochondria were both increased in the noninfarcted LV from MI mice. The mtDNA copy number relative to the nuclear gene (18S rRNA) preferentially decreased by 44% in MI by a Southern blot analysis, associated with a parallel decrease (30% to 50% of sham) in the mtDNA-encoded gene transcripts, including the subunits of complex I (ND1, 2, 3, 4, 4L, and 5), complex III (cytochrome b), complex IV (cytochrome c oxidase), and rRNA (12S and 16S). Consistent with these molecular changes, the enzymatic activity of complexes I, III, and IV decreased in MI, whereas, in contrast, complex II and citrate synthase, encoded only by nuclear DNA, both remained at normal levels. An intimate link among ROS, mtDNA damage, and defects in the electron transport function, which may lead to an additional generation of ROS, might play an important role in the development and progression of LV remodeling and failure.

Suppression of apoptosis is responsible for increased thickness of intestinal mucosa in streptozotocin-induced diabetic rats

Intestinal mucosal growth is a common, but uncharacterized, observation associated with diabetes mellitus. Epithelial homeostasis is balanced by regulation of cell proliferation and cell death. To determine the contribution of apoptosis to the overall maintenance of intestinal growth, we examined intestinal apoptosis in the well-characterized streptozotocin (STZ)-induced diabetes rat model. Rats were injected with STZ (75 mg/kg body weight), thereafter they were allowed free feeding or restricted feeding for 3 weeks. Food intake and intestinal mucosal height were evaluated. In a second experiment, additional groups of animals were injected with STZ and were fed ad libitum for 1 or 3 weeks. Ornithine decarboxylase (ODC) activity, ratio of fragmented DNA to total DNA, electrophoresis of fragmented DNA, and Western blot analysis of caspase-3 were examined. Food intake gradually increased in free-feeding rats after induction of diabetes. Intestinal mucosal height in free-feeding diabetic rats was approximately 25% longer than controls, but this increase in mucosal height was not observed in restricted-fed diabetic rats (25 g/d). ODC activity in intestinal mucosa in diabetic rats did not differ from that of control rats. Percent fragmented DNA of diabetic rats 1 week after STZ injection was significantly lower than that of control rats, and this decrease returned to the control level 3 weeks after STZ treatment. Active form of caspase-3 was attenuated 1 week after drug treatment. Attenuated effect of diabetic rats on intestinal apoptosis did not affect increased apoptosis after ischemia-reperfusion. Suppression of apoptosis in the early days of STZ-induced diabetes was responsible for the increased mucosal height in the small intestine in STZ-induced diabetic animals.

Inhibition of erythropoietin signalling destroys xenografts of ovarian and uterine cancers in nude mice

We have recently shown that malignant tumours from the ovary and uterus expressed erythropoietin (Epo) and its receptor (EpoR), and that deprivation of Epo signal in tumour blocks induced death of malignant cells and capillary endothelial cells in vitro (Yasuda et al, submitted). These in vitro results prompted us to examine the effect of Epo-signal withdrawal on tumours in vivo. RT-PCR analysis demonstrated the expression of mRNAs for Epo and EpoR in the transplants of uterine and ovarian tumours in nude mice. Then we injected locally anti-Epo antibody or soluble form of EpoR into the transplants. At 12 h, 1, 7 or 14 days after the injection, all transplants were resected and examined macro- and microscopically. Tumour size was reduced in Epo signal-deprived transplants. Immunohistochemical examinations revealed destruction of Epo-responding malignant and capillary endothelial cells through apoptotic death. The degree of tumour regression correlated well with the dose and frequency of the injections. Control xenografts with saline injection or needle insertion showed well-developed tumour masses. This Epo response pathway will have profound implications for our understanding of the development and progression of malignant tumours and for the use of Epo-signal deprivation as an effective therapy.

Apoptosis induced by ischemia-reperfusion and fasting in gastric mucosa compared to small intestinal mucosa in rats

The effect of ischemia-reperfusion and 48-hr fasting on apoptosis was characterized in rat gastric mucosa and compared to small intestinal mucosa. Under halothane anesthesia, the celiac artery or superior mesenteric artery in the rat was occluded for 60 min followed by reperfusion. Occlusion of the celiac artery reduced blood flow in the stomach and occlusion of the mesenteric artery reduced blood flow in the small intestine. Additional rats were fasted for 48 hr to evaluate the effect of fasting on mucosal apoptosis. The ratios of fragmented DNA to total DNA, electrophoresis, and immunohistochemical staining were examined after ischemia-reperfusion or fasting. Apoptosis was not induced significantly in the gastric mucosa after ischemia-reperfusion, although it increased dramatically in the intestinal mucosa after ischemia-reperfusion. Further, after 48 fasting, apoptosis was induced in the small intestine, but not in the stomach. These results indicate that rat gastric mucosa is not as sensitive as small intestinal mucosa to ischemia-reperfusion or fasting-induced apoptosis.

Noninvasive detection of hydroxyl radical generation in lung by diesel exhaust particles

Diesel exhaust particles (DEP) induce pulmonary tumors, asthma-like symptoms, and the like in experimental animals. The involvement of reactive oxygen species (ROS) is suggested in the injuries induced by DEP, though the generation of ROS has not been proven. The present study provided the first direct evidence of *OH generation in the lungs of living mice after intratracheal instillation of DEP, using noninvasive L-band ESR spectroscopy and a membrane-impermeable nitroxyl probe. *OH generation is confirmed with the enhancement of in vivo ESR signal decay rate of the probe. The decay rate at mid-thorax was significantly enhanced in DEP-treated mice compared to that in vehicle-treated mice. The enhancement was completely suppressed by the administration of either *OH scavengers, catalase, or desferrioxamine, while the administration of SOD further increased the rate. The administration of Fenton's reagents into the lung also enhanced the decay rate of the probe at mid-thorax of mice. These results clearly provided evidence that the intratracheal exposure to DEP in mice produced *OH in the lung through an iron-catalyzed reaction of superoxide/H(2)O(2). This first direct evidence of *OH generation in DEP-treated mice lung may be utilized to determine treatments for DEP-induced lung injury.

Greater susceptibility of failing cardiac myocytes to oxygen free radical-mediated injury

OBJECTIVE

Oxygen-derived free radicals can produce myocardial cellular damage, which might contribute to the ischemia-reperfusion injury and to heart failure (HF). However, the effects of oxygen radicals on myocyte structure have not been examined in the failing heart.

METHODS

We examined the susceptibility of intact cardiac myocytes isolated from control (n=16) and rapid pacing (240 bpm, 4 wks)-induced HF (n=8) dog hearts to an exogenous hydroxyl radical (.OH), generated from H(2)O(2) and Fe(3+)-nitrilotriacetate. The production of (.OH) was monitored by electron spin resonance with 5,5'-dimethyl-1-pyroline-N-oxide (DMPO) as a spin trap.

RESULTS

The magnitude of DMPO-OH signals was not attenuated in the presence of either control or HF myocytes. (.OH) induced a time-dependent decrease in myocyte length (i.e. hypercontracture). The time to the onset of hypercontracture and that to the submaximal hypercontracture after exposure was significantly shortened in HF. Activities of superoxide dismutase, catalase, and glutathione peroxidase was not decreased in HF.

CONCLUSIONS

HF myocytes were more susceptible to oxidative stress-induced cellular injury, which was not due to decreased antioxidant defense, but to the intrinsic properties of cells.

Conformational studies on a unique bis-sulfated glycolipid using NMR spectroscopy and molecular dynamics simulations

The time-averaged solution conformation of a unique bis-sulfated glycolipid (HSO3)2-2,6Manalpha-2Glcalpha-1-sn-2,3-O-alkylglycerol , was studied in terms of the torsional angles of two glycosidic linkages, phi (H1-C1-O-Cx) and psi (C1-O-Cx-Hx), derived from heteronuclear three-bond coupling constants (3JC,H), and inter-residual proton-proton distances from J-HMBC 2D and ROESY experiments, respectively. The dihedral angles of Glcalpha1Gro in glycolipids were determined for the first time. The C1-C4 diagonal line of the alpha-glucose ring makes an angle of approximately 120 degrees with the glycerol backbone, suggesting that the alpha-glucose ring is almost parallel to the membrane surface in contrast with the perpendicular orientation of the beta-isomer. Furthermore, minimum-energy states around the conformation were estimated by Monte Carlo/stochastic dynamics (MCSD) mixed-mode simulations and the energy minimization with assisted model building and energy refinement (AMBER) force field. The Glcalpha1Gro linkage has a single minimum-energy structure. On the other hand, three conformers were observed for the Manalpha2Glc linkage. The flexibility of Manalpha2Glc was further confirmed by the absence of inter-residual hydrogen bonds which were judged from the temperature coefficients of the chemical shifts, ddelta/dT (-10-3 p.p.m. degrees C-1), of hydroxy protons. The conformational flexibility may facilitate interaction of extracellular substances with both sulfate groups.

Development of separable electron spin resonance-computed tomography imaging for multiple radical species: an application to .OH and .NO

A method of separable ESR-CT (electron spin resonance-computed tomography) imaging for multiple radical species was developed and applied to imaging of .OH and .NO. The algorithm was improved by combining filtered back-projection with a modified algebraic reconstruction technique to enhance accuracy and shorten calculation time. With this algorithm, spectral-spatial images of the phantom consisting of 3-carbamoyl-2,2,5,5,-tetramethylpyrrolidine-N-oxyl and 2-phenyl-4,4,5,5,-tetramethylimidazoline-3-oxide-1-oxyl could be obtained in different directions by rotating the spatial axis. The spatial function of individual radicals was extracted by each of the two methods from each spectral-spatial image. The separative 2D images of each radical were individually constructed using the spatial function obtained with the two methods. By comparing the separative images with the phantom sample, the algorithm for separable ESR-CT imaging was established. This ESR-CT technique was combined with L-band ESR spectroscopy and applied to the separative imaging of .OH and .NO, which were spin trapped with 5, 5-dimethyl-1-pyrroline-N-oxide (DMPO) and Fe(2+)-N-methyl-D-glucamine dithiocarbamate complex, respectively. The ESR signal of DMPO-OH decreased gradually during data acquisition, and the decrease was calibrated by extrapolating the signal intensity to the beginning of data sampling. Both the position and size of the individual images for .OH and .NO were in very good agreement with the findings for the sample.

High glucose level and free fatty acid stimulate reactive oxygen species production through protein kinase C--dependent activation of NAD(P)H oxidase in cultured vascular cells

Recent studies have revealed that vascular cells can produce reactive oxygen species (ROS) through NAD(P)H oxidase, which may be involved in vascular injury. However, the pathological role of vascular NAD(P)H oxidase in diabetes or in the insulin-resistant state remains unknown. In this study, we examined the effect of high glucose level and free fatty acid (FFA) (palmitate) on ROS production in cultured aortic smooth muscle cells (SMCs) and endothelial cells (ECs) using electron spin resonance spectroscopy. Exposure of cultured SMCs or ECs to a high glucose level (400 mg/dl) for 72 h significantly increased the free radical production compared with low glucose level exposure (100 mg/dl). Treatment of the cells for 3 h with phorbol myristic acid (PMA), a protein kinase C (PKC) activator, also increased free radical production. This increase was restored to the control value by diphenylene iodonium, a NAD(P)H oxidase inhibitor, suggesting ROS production through PKC-dependent activation of NAD(P)H oxidase. The increase in free radical production by high glucose level exposure was completely restored by both diphenylene iodonium and GF109203X, a PKC-specific inhibitor. Exposure to palmitate (200 micromol/l) also increased free radical production, which was concomitant with increases in diacylglycerol level and PKC activity. Again, this increase was restored to the control value by both diphenylene iodonium and GF109203X. The present results suggest that both high glucose level and palmitate may stimulate ROS production through PKC-dependent activation of NAD(P)H oxidase in both vascular SMCs and ECs. This finding may be involved in the excessive acceleration of atherosclerosis in patients with diabetes and insulin resistance syndrome.

Proficient repair of potentially lethal damage sensitive to hypertonic treatment in osteosarcoma cells

Fast-repairing potentially lethal damage (PLD) in seven osteosarcoma cell lines was analyzed after treatment with a hypertonic 0.5 M NaCl solution for 20 min and compared to that in seven human fibroblast strains. Fixation of PLD after exposure to ionizing radiation was observed without exception in both the osteosarcoma cells and the fibroblast strains. The percentages by which the D(o)'s of the osteosarcoma cells decreased were significantly higher than the percentage decreases in the C(o)'s of the fibroblast strains (P < 0.01). Hypertonic treatment resulted in radiosensitization due to fixation of PLD in all of the osteosarcoma cell lines, demonstrating that osteosarcoma cells can repair PLD better than normal fibroblast cells. The radiobiological response of the osteosarcoma cells, with enhanced killing after hypertonic treatment, was similar to that of normal untreated fibroblast cells.

Treatment with dimethylthiourea prevents left ventricular remodeling and failure after experimental myocardial infarction in mice: role of oxidative stress

Oxidative stress might play an important role in the progression of left ventricular (LV) remodeling and failure that occur after myocardial infarction (MI). We determined whether reactive oxygen species (ROS) are increased in the LV remodeling and failure in experimental MI with the use of electron spin resonance spectroscopy and whether the long-term administration of dimethylthiourea (DMTU), hydroxyl radical (.OH) scavenger, could attenuate these changes. We studied 3 groups of mice: sham-operated (sham), MI, and MI animals that received DMTU (MI+DMTU). Drugs were administered to the animals daily via intraperitoneal injection for 4 weeks.OH was increased in the noninfarcted myocardium from MI animals, which was abolished in MI+DMTU. Fractional shortening was depressed by 65%, LV chamber diameter was increased by 53%, and the thickness of noninfarcted myocardium was increased by 37% in MI. MI+DMTU animals had significantly better LV contractile function and smaller increases in LV chamber size and hypertrophy than MI animals. Changes in myocyte cross-sectional area determined with LV mid-free wall specimens were concordant with the wall thickness data. Collagen volume fraction of the noninfarcted myocardium showed significant increases in the MI, which were also attenuated with DMTU. Myocardial matrix metalloproteinase-2 activity, measured with gelatin zymography, was increased with MI after 7 and 28 days, which was attenuated in MI+DMTU. Thus, the attenuation of increased myocardial ROS and metalloproteinase activity with DMTU may contribute, at least in part, to its beneficial effects on LV remodeling and failure. Therapies designed to interfere with oxidative stress might be beneficial to prevent myocardial failure.

Expression of GFRalpha-1, receptor for GDNF, in rat brain capillary during postnatal development of the BBB

It is well known that the blood-brain barrier (BBB) matures at approximately 2 wk after birth in the rat. Recently, we showed that glial cell line-derived neurotrophic factor (GDNF) enhances the barrier function of porcine endothelial cells forming the BBB in culture. In the present study, we examined the relation between permeability of the BBB, using Evans blue as a tracer, and expression of the GDNF family receptor (GFRalpha-1) during postnatal development of the BBB. Morphometric analysis showed that exudation of Evans blue from capillaries of the cerebral cortex progressively decreased until postnatal day 21. Inversely, immunohistochemical examinations showed expression of GFRalpha-1 in the capillaries at postnatal day 3 and expression that reached the same levels as observed in adult rats by postnatal day 10. However, c-ret, which is thought to mediate a signal evoked by binding of GDNF to GFRalpha-1, was not expressed in the capillaries of the brain cortex in 3-mo-old rats. On the other hand, the tight junction proteins occludin and ZO-1 appeared to be fully expressed at birth. The reciprocal relation between GFRalpha-1 expression and the permeability of the BBB strongly suggests active participation of GDNF in postnatal development of the BBB, although the mechanism(s) involved is still veiled.

Expression of receptors for glial cell line-derived neurotrophic factor (GDNF) and neurturin in the inner blood-retinal barrier of rats

The retina is protected from somatic circulation by the blood-retinal barrrier (BRB) composed of tight junctions between retinal vascular endothelial cells (the inner BRB) and those between retinal pigment epithelial cells (the outer BRB). Our recent studies showed that glial cell line-derived neurotrophic factor (GDNF) secreted from astrocytes regulates the permeability of the BBB. In the present study, we immunohistochemically examined the expression of GDNF, neurturin (NTN) and their receptors, GFRalpha1 for GDNF and GFRalpha2 for NTN, because the capillaries of the inner BRB show specialization very similar to the blood-brain barrier (BBB). GDNF and NTN were detected in glial fibrillary acidic protein (GFAP)-positive cells, including Müller cells. GFRalpha1 and GFRalpha2 were localized in von Willebrand factor-positive cells. GDNF and NTN enhanced the barrier function of endothelial cells derived from porcine brain cortex. These results strongly suggest that the barrier function of the BRB is regulated by GDNF and NTN secreted from glial cells, like the BBB.

Linkage of autosomal recessive hereditary spastic paraplegia with mental impairment and thin corpus callosum to chromosome 15A13-15

To date, three loci for autosomal recessive hereditary spastic paraplegia (ARHSP) linked to chromosomes 8p12-q13, 16qter, and 15q13-15 have been characterized. We have clinically characterized 13 Japanese ARHSP families and performed genetic linkage analyses. All 13 families were classified as having the "complicated" form, which manifests with mental impairment and thin corpus callosum. Linkage to the 8p12-q13 and 16qter loci was excluded, although 10 of the 13 families showed marker data consistent with linkage to the 15q13-15 locus. The multipoint LOD score of the 10 families linked to chromosome 15 was above 9.00 in the 3-centimorgan segment flanked by D15S994 and D15S659, with a maximum multipoint LOD score of 9.68 at a position 1.2 centimorgans telomeric from D15S994 to D15S659. We have shown that ARHSP with thin corpus callosum, a subtype of recessive spastic paraplegia, maps to chromosome 15q13-15.

In vivo electron spin resonance assessment of decay constant of nitroxyl radical in selenium-deficient rat

In vivo reducing capacity and cytosolic glutathione peroxidase (GSH-Px) activity in liver homogenate were evaluated in 6 weeks old Se-deficient and normal rats. GSH-Px was significantly lower in Se-deficient rats than in normal rats. In vivo reducing capacity in head and liver parts, estimated from in vivo signal decay of a nitroxyl spin probe using a low frequency (300 MHz) ESR spectrometer, was significantly decreased in Se-deficient rats, suggesting a decrease of antioxidant capacity in Se-deficient rats.

Membrane structure of the hepatitis B virus surface antigen particle

Expression of S protein, an envelope protein of hepatitis B virus, in the absence of other viral proteins, leads to the secretion of hepatitis B virus surface antigen (HBsAg) particles that are formed by budding from the endoplasmic reticulum membranes. The HBsAg particles produced by mouse fibroblast cells show a unique lipid composition, with 1,2-diacyl glycerophosphocholine being the dominant component. The lipid organization of the HBsAg particles was studied by measuring electron spin resonance (ESR) using various spin-labeled fatty acids, and the results were compared with a parallel study on HVJ (Sendai virus) and vesicles reconstituted with total lipids of the HBsAg particles (HBs-lipid vesicles). HVJ and the HBs-lipid vesicles showed typical ESR spectra of lipids arranged in a lipid bilayer structure. In contrast, the ESR spectra obtained with the HBsAg particles showed that the movement of lipids in the particle is severely restricted and a typical immobilized signal characteristic of tight lipid-protein interactions was also evident. Phosphatidylcholine (PC) in the HBsAg particles was not exchangeable by a PC-specific exchange protein purified from bovine liver, while phospholipase A(2) from Naja naja vemon was able to hydrolyze all the PC in the particles. These analyses suggest that the lipids in the HBsAg particles are not organized in a typical lipid bilayer structure, but are located at the surface of the particles and are in a highly immobilized state. Based on these observations we propose a unique lipid assembly and membrane structure model for HBsAg particles.