Oxygen radical-induced single-strand DNA breaks and repair of the damage in a cell-free system

Ferric nitrilotriacetate (Fe(3+)-NTA) catalyzes hydrogen peroxide-derived production of hydroxyl radicals, which are known to cause DNA damage. In the present work, Fe(3+)-NTA plus hydrogen peroxide-induced single-strand DNA breaks and repair of the DNA damage were studied in vitro by monitoring DNA damage- and DNA repair-dependent conformational changes of pUC18 plasmid DNA. Single-strand DNA breaks were induced in the pUC18 DNA by Fe(3+)-NTA plus hydrogen peroxide in a dose-dependent fashion. Induction of the DNA damage was inhibited by deferoxamine mesylate (an iron chelator) and by hydroxyl radical scavengers such as dimethyl sulfoxide (DMSO), D-mannitol and ethanol indicating that the DNA damage was caused by hydroxyl radicals which were generated by reaction of Fe(3+)-NTA with hydrogen peroxide. The oxygen radical-induced single-strand DNA breaks were repaired partly (more than 50%) by incubating the damaged DNA at 37 degrees C for 3 h with a partially purified preparation of APEX nuclease (a multifunctional DNA repair enzyme), DNA polymerase beta, four deoxyribonucleoside triphosphates, T4 DNA ligase and ATP. Analyses of the partially purified preparation of APEX nuclease revealed that a 45-kDa protein as well as APEX nuclease in the preparation were involved in the repair of the single-strand DNA breaks. APEX nuclease was suggested to initiate the repair by removing 3' termini blocked by the nucleotide fragments and also by incising the 5' side of AP sites. The 45-kDa protein was suggested to be required for removal of the 5' tags such as 5'-terminal deoxyribose phosphate residues produced by the action of APEX nuclease on AP sites.

Restoration of gap junctions in the regenerative process of ethanol-induced gastric mucosal injury

Gap junctions mediate intercellular communication and play an important role in cell proliferation and differentiation. The present study examined the expression of the gap junction protein connexin 32 in rat gastric mucosa during the regenerative process of ethanol-induced gastric mucosal injury. Absolute ethanol (0.5 mL/100 g bodyweight) was administered to rats via gastric intubation. Following the treatment, rats were killed periodically, and gastric tissues were processed for indirect immunofluorescence microscopy using an anti-connexin 32 antibody. Haematoxylin and eosin (H&E), periodic acid Schiff (PAS) and Bromodeoxyuridine (BrdU) staining were also performed in serial sections. Gastric injuries were limited in the mucosal layer. The injury was most severe 1 h after treatment, and was completely resolved by the 4th day after treatment. The number of immunoreactive spots for gap junctions was markedly decreased 1 h after the ethanol treatment. Reappearance of these immunostaining gap junctions occurred with repair of the injury. The reappearance of connexin 32 after injury was delayed in comparison with both the histologic resolution of the injury and the normalization of PAS-stained mucus. In contrast, the time course of reappearance of gap junctions closely paralleled the appearance of BrdU-labelled cells. These results indicate that morphologic repair is different to the recovery of cell maturity and cell proliferation in the regenerative gastric mucosa.

Fatal cerebral infarction in an asymptomatic young patient with primary antiphospholipid syndrome

An 18-year-old woman with primary antiphospholipid syndrome developed a major cerebral infarction leading to brain death despite intensive treatment with steroids, urokinase, glyceol and heparin. Fatal strokes associated with this syndrome are rare. A computed tomographic scan of the brain suggested occlusion of the main trunk of the right middle cerebral artery. The titer of antibodies against cardiolipin/ beta 2-glycoprotein I complex in serum was extremely high.

Eccrine syringofibroadenoma. Report of a case and immunohistochemical study of keratin expression

We report a 49-year-old woman with an eccrine syringofibroadenoma. An asymptomatic nodule appeared on the right heel, and subsequently enlarged gradually. Histological examination revealed anastomosing strands of pale epithelial cells, with occasional duct formation and mucinous fibrovascular stroma. There were two types of strands: thick and thin. Immunohistochemical study, using a panel of monoclonal antikeratin antibodies, revealed that the immunoreactivity differed between the two types of strands. The thick strands showed a staining pattern similar to the uppermost portion of the intradermal duct, and the thin strands showed a pattern similar to the other portion of the duct. This observation suggests that the thick and thin strands differentiate towards the uppermost portion and the remainder of the duct, respectively.

Correspondence of RLGS-M spot behavior with tissue expression on mouse homologue of DP1/TB2 gene

RLGS-M is a novel method which enables visual and quantitative detection of many methylatable loci as two-dimensional gel spots. We isolated and characterized a mouse genomic clone corresponding to the RLGS-M gel spot #109v, which showed different intensities between two tissues: the spot was much more faint in liver than in brain. Southern and Northern blot analysis disclosed this spot behavior to be related to the methylation state of NotI site and also to be correlated with the differential expression in both tissues; the transcripts for #109v were observed in the brain but hardly any in the liver. Furthermore, in the base sequence analysis, this #109v gene was found to be the mouse homologue of human DP1/TB2 gene and had a CpG island adjacent to the NotI site. These results indicate that the mouse DP1/TB2 gene is expressed corresponding to its RLGS-M spot behavior which is related to its methylation condition.

Increase in the septal vasopressin content by prolyl endopeptidase inhibitors in rats

Prolyl endopeptidase (PEP; EC 3.4.21.26) cleaves the Pro-Arg bond of arginine-vasopressin (AVP). This study investigated the effects of PEP inhibitors, 1-[1-(benzyloxycarbonyl)-L-prolyl]prolinal (Z-Pro-prolinal) and 1-[3-(2-indanylacetyl)-L-thioprolyl]pyrrolidine (Z-321), on the AVP content in the septum of rats. Oral administration of Z-Pro-prolinal (100 mg/kg) and Z-321 (100 mg/kg) significantly increased the septal AVP content. At 10 mg/kg, Z-321 slightly increased the content. In contrast, the D-thioprolyl form of Z-321 (100 mg/kg), which lacks an inhibitory effect on the enzyme, failed to affect the AVP content. These results indicate that PEP inhibitors increase the content of AVP through inhibition of the enzyme activity in vivo. Therefore, it is suggested that PEP may contribute to the degradation of endogenous AVP in the brain.

Preparation of long-circulating immunoliposomes containing adriamycin by a novel method to coat immunoliposomes with poly(ethylene glycol)

Modifications of liposomes with poly (ethylene glycol) (PEG) have been reported to prolong blood circulation time of liposomes. In this report, an adriamycin-encapsulated immunoliposomes were modified with PEG by two different approaches: one is the pre-coating method using lipid derivative of PEG as described by Allen et al. The other is post-coating method which is presented here. The former pre-coating method did not allow coupling of antibody due to the steric hindrance of PEG which had been introduced on liposome surface. On the other hand, in the later post-coating method, PEG-succinylcysteine was synthesized and was successfully conjugated with immunoliposomes via maleimido linker. Resultant PEG-coated immunoliposomes containing adriamycin retained their binding activity and cytotoxicity to target cells, and also showed significantly prolonged blood circulating time as compared with conventional immunoliposomes. This is a novel method to coat immunoliposomes with PEG.

Methylcobalamin attenuates the hypoxia/hypoglycemia- or glutamate-induced reduction in hippocampal fiber spikes in vitro

The effects of methylcobalamin, a vitamin B12 analogue, on the hypoxia/hypoglycemia- or glutamate-induced reduction in hippocampal CA1 presynaptic fiber spikes elicited by Schaffer collateral stimulation in rat brain slices were evaluated. Hippocampal slices were exposed to 15 min of hypoxia/hypoglycemia, and then these slices were returned to oxygenated and glucose-containing buffer for 3 h. Hypoxia/hypoglycemia reduced CA1 presynaptic potentials in vitro. Treatment with 10 microM methylcobalamin attenuated the impairment of CA1 presynaptic potentials induced by hypoxia/hypoglycemia or glutamate application (10 mM). Daily injection of methylcobalamin (0.5 mg/kg i.p./day) for 3 days in vivo also attenuated the hypoxia/hypoglycemia- or glutamate-induced reduction in presynaptic potentials in hippocampal slices. Pretreatment with cyanocobalamin at 10 microM failed to attenuate the impairment of CA1 presynaptic potentials. However, daily injection of cyanocobalamin (0.5 mg/kg i.p./day) for 3 days caused a protective action against the hypoxia/hypoglycemia- or glutamate-induced functional deficit. Furthermore, co-treatment of L-arginine (100 microM), a substrate for nitric oxide synthase, with methylcobalamin in vitro reversed the methylcobalamin-induced functional recovery. The present results demonstrate that methylcobalamin application in vivo or in vitro leads to functional recovery from hypoxia/hypoglycemia- or glutamate-induced impairment of CA1 presynaptic potentials. Neuroprotection was obtained by in vivo application of cyanocobalamin, but not by its in vitro application. It is reported that in vivo injected cyanocobalamin converted to methylcobalamin in the hepatic cells. Therefore, the results suggest that a transmethylation reaction in the hippocampal regions may be involved in the methylcobalamin-induced functional recovery from ischemic impairment.

Stable production of mutant mice from double gene converted ES cells with puromycin and neomycin

The antibiotic puromycin is an effective inhibitor of protein synthesis and puromycin N-acetyl transferase gene could be used as a dominant selection marker. We report the effective production of mutant mice from double gene-converted ES cells by selection with G418 and puromycin. We confirmed that (i) puromycin efficiently inhibited the growth of ES cells at a low-dose (0.1 microgram/ml) and for a short time (2 days), independent of G418 selection; (ii) when these selected ES cells were injected into eight-cell stage embryos, the cells produced chimeras with high levels of chimerism; (iii) these chimeric males were fertile and exclusively yielded ES cell-derived offspring; and (iv) each offspring contained both neomycin transferase and puromycin N-acetyl transferase genes.

Immunohistochemical characterization of keratin expression in clear cell acanthoma

The nature of clear cell acanthoma has not been clarified, although many hypotheses have been proposed, including a benign neoplasm derived from epidermis or the acrosyringium, or a non-specific dermatosis. In this study, seven cases of clear cell acanthoma were analysed by immunohistochemical techniques, using various monoclonal antikeratin antibodies, and antibodies against filaggrin, involucrin and epithelial membrane antigen. Different immunoreactivities were noted between clear cell acanthoma and a normal eccrine gland, including the acrosyringium. Immunoreactivities of clear cell acanthoma were almost identical to those of normal epidermis, although some antibodies gave a different staining pattern between clear cell acanthoma and normal epidermis. The expression of cytokeratins in psoriatic epidermis has been reported to change as a result of abnormal differentiation or maturation. Clear cell acanthoma showed a similar staining pattern to inflammatory dermatoses such as psoriasis vulgaris, lichen planus and discoid lupus erythematosus. We speculate that clear cell acanthoma is a localized form of inflammatory dermatosis rather than a neoplasm.

[Myocardial infarction caused by spontaneous coronary artery dissection associated with significant mitral regurgitation--a successful surgical case]

We experienced a case of 34-year-old male with old myocardial infarction, which seemed to be caused by spontaneous dissection of the left circumflex coronary artery, and associated papillary muscle disfunction with resultant significant mitral regurgitation. He was treated surgically by coronary artery bypass grafting and mitral valvuloplasty. Ungraftable circumflex was abandoned; instead, pediculated graft of the right gastroepiploic artery was anastomosed to the mid-portion of the right coronary artery, which also had been spontaneously dissected. Mitral regurgitation was treated with Reed's plasty of the posterior commissure and the ring annuloplasty using Carpentier-Edwards Ring. His postoperative course has been smooth and uneventful. According to the English literature of the Western hemisphere, spontaneous coronary arterial dissection usually occurs in relatively young people with a striking predilection for women, and nearly all report deal only with the coronary abnormality. To our knowledge, this is the first report of a surgical case of the spontaneous coronary dissection associated with significant mitral regurgitation.

Changes in the mouse exocrine pancreas after pancreatic duct ligation: a qualitative and quantitative histological study

The pancreatic duct from the splenic lobe, the largest lobe of the pancreas in the mouse, was ligated at 6 weeks of age, with histological and cytological changes in the organ examined 1 day to 16 weeks after the ligation. Changes in the volumes of the pancreatic lobe, exocrine tissue, and interstitial tissue as well as relative total numbers of each cellular element in the organ after duct ligation were stereologically obtained using serial sections of the whole pancreas. Cell sizes, degenerated cell and mitotic cell indices, and nuclear densities of the acinar and ductal cells were also obtained. After duct ligation, the volume of the pancreas increased by interstitial edema in the first 2 days but rapidly decreased thereafter due to atrophy of the exocrine tissue, amounting to 10% or less of normal volume by 7 days. The acinar cells showed an accumulation of the zymogen granules, cytoplasmic condensation and a pyknotic figure of the nucleus; they then were thoroughly deleted with appearance of numerous macrophages. This cell death was suggested to be due to apoptosis. On the other hand, the ductal cells remained in the atrophic pancreas and proliferated with mitotic figures to two times the normal frequency at 3 days, and then formed duct-like structures lacking in the acinar cells. After 2 week, the ductal cells slowly decreased in number also due to cell death, but the pancreas became gradually enlarged by intralobular fatty replacement, to reach a volume approximating that of normal 8 weeks after duct ligation. The stereological method serves for the correct evaluation of cell dynamics including the deletion and proliferation of the cells in the whole organ.

Concurrent blockade of beta-adrenergic and muscarinic receptors disrupts working memory but not reference memory in rats

In order to clarify the interactions between monoaminergic and cholinergic systems in working and reference memory functions, the effects of administration of the alpha, beta-adrenergic, D1-, D2-dopaminergic or serotonergic receptor antagonist together with the muscarinic receptor antagonist scopolamine on this behavior were examined using a three-panel runway task. Both in working and reference memory tasks, the number of errors (attempts to pass through two incorrect panels of the three panel-gates at four choice points) was significantly increased by 0.32 mg/kg scopolamine, but not by the doses up to 0.18 mg/kg. The beta-adrenergic antagonist propranolol at 10 mg/kg had no effect on the number of working memory errors. Combined administration of 10 mg/kg propranolol and scopolamine at 0.1 and 0.18 mg/kg significantly increased the number of working memory errors. However, in a reference memory task, propranolol at 10 mg/kg did not affect the number of errors, whether administered alone or together with 0.1 mg/kg scopolamine. Other monoaminergic receptor antagonists, including the alpha-adrenergic antagonist phentolamine (3.2 and 10 mg/kg), D1-antagonist SCH23390 (0.032 and 0.056 mg/kg). D2-antagonist sulpiride (100 mg/kg) and serotonin antagonist cinanserin (10 and 32 mg/kg) had no significant effect on working or reference memory errors, whether they were administered independently or in combination with scopolamine at 0.1 mg/kg. These results suggest that beta-adrenergic/muscarinic interactions play an important role in mediating processes involved in working memory performance of rats.

Mechanism of angiogenic effects of saponin from ginseng Radix rubra in human umbilical vein endothelial cells

1. The effects of saponin from Ginseng Radix rubra on angiogenesis (tube formation) and its key steps (protease secretion, proliferation and migration) in human umbilical vein endothelial cells (HUVEC) were examined to elucidate the mechanism of the tissue repairing effects of Ginseng Radix rubra. The effect on a wound healing model was also studied. 2. Tube formation was measured by an in vitro system. The activity and immunoreactivity of tissue-type plasminogen activator (tPA) as a protease for angiogenesis and the immunoreactivity of its inhibitor, plasminogen activator inhibitor-1 (PAI-1), were measured in conditioned medium of HUVEC stimulated for 24 h with saponin. Cell proliferation was measured by counting the cell numbers at 2-7 days after seeding. Migration was measured by Boyden's chamber method. The effect on wound healing was studied in the skin of diabetic rats. 3. Saponin at 10-100 micrograms ml-1 significantly stimulated tube formation by HUVEC in a dose-dependent manner. Saponin in a similar concentration-range increased the secretion of tPA from HUVEC as estimated by immunoreactivity and enzyme activity. On the other hand, PAI-1 immunoreactivity was slightly increased at 10 micrograms ml-1 of saponin, but then was significantly decreased at 50 and 100 micrograms ml-1. Cell proliferation was only slightly enhanced by 1-100 micrograms ml-1 of saponin, but migration was significantly enhanced by 10-100 micrograms ml-1 in a dose-dependent manner. Moreover, saponin stimulated wound healing with enhanced angiogenesis in vivo. 4. These results indicate that saponin stimulates tube formation mainly by modifying the balance of protease/protease inhibitor secretion from HUVEC and enhancing the migration of HUVEC, and that it is effective in vivo.

[Study on reverse transcriptase inhibiting antibody in plasma of HIV-1 seropositive subjects]

Reverse transcriptase (RT) inhibiting antibody in a series of plasma of HIV-1-seropositive subjects was quantitatively measured by poly A-linked colorimetric microtiter plate assay. The plasma were obtained from 6 asymptomatic carrier (AC)s and from 3 patients who progressed to AIDS. They had been followed 29-51 months. RT inhibiting antibody levels in the plasma were measured by inhibition assay against HTLV-IIIB RT activity. In five of the 6 AC cases, RT inhibiting antibodies in the serial plasma maintained high levels, and 50% inhibiting titers of the serial plasma did not decrease throughout the observation periods (45-51 months). HIV isolation from peripheral blood mononuclear cell (PBMC) of these 5 ACs did not succeed, and HIV p24 antigens were not detected in the plasma. In one AC case (046) RT inhibiting antibody levels gradually decreased after 48 months. In this case, HIV p24 antigen was not detected in the serial plasma throughout the observation period (48 months), but HIV was isolated from PBMC after 27 months. On the other hand, RT inhibiting antibody levels in the serial plasma of all 3 patients who progressed to AIDS gradually decreased in observation periods (29-35 months). HIV strains were isolated from these 3 cases. These results suggest that reduction of RT inhibiting antibody levels correlate well with the success of HIV isolation and with progression of clinical manifestation.

A rapid assessment of stimulus properties of morphine

The difficulty in assessing stimulus properties of drugs becomes apparent when the test drug, like morphine, carries both aversive and reinforcing effects at certain doses. Mice (ICR Crj strain) were trained in a passive avoidance conditioning using a two-compartment shuttle-box. On alternate days, morphine (3.0 mg/kg) was paired with shock in one compartment and saline with shock in the other compartment. A total of 3 morphine/saline pairings were given. Animals were then tested 7 times, one test per day, with saline and different doses of morphine (0.75, 1.12, 1.32, 0.93, 1.50, 3.0 mg/kg) to reveal the stimulus properties of morphine. The preference for the morphine-conditioned safe compartment after morphine injections was used to indicate that the animals associated some "stimulus" or "motivational" properties of morphine with the cues of the safe compartment. The animals discriminated very well between saline and low doses of morphine on the one hand, and higher doses of morphine (close to that given during conditioning) on the other. The discontinuity between injections responded to as saline and those responded to as morphine was virtually complete between 1.12 and 1.32 mg/kg of morphine. These findings demonstrate that the present method can be used to establish an association between some stimulus properties of morphine and avoidance of shock. Accordingly, the successful discrimination of the animals between the two compartments revealed some stimulus properties of morphine.

Asterixis and astatic seizures in association with bilateral insular lesions in a patient with viral encephalitis

We report a 48-year-old man who suffered from viral encephalitis and developed involuntary movements of the hands and astatic seizures as sequelae. T2-weighted magnetic resonance imaging of the brain showed high intensity areas in the bilateral insulae. Electroencephalography (EEG) revealed spike and slow wave complexes and high-amplitude slow waves. The involuntary movements of the hands were diagnosed as asterixis by electromyography. Asterixis affected both hands. Administration of sodium valproate aggravated asterixis and EEG findings, but treatment with clonazepam markedly improved these findings and astatic seizures. The present case indicates that insular lesions might be also responsible for the development of asterixis.

Involvement of dopamine, N-methyl-D-aspartate and sigma receptor mechanisms in methamphetamine-induced anticipatory activity rhythm in rats

Daily injection of methamphetamine (MAP) increased the locomotor activity and produced the development of MAP-induced anticipatory activity on the next withdrawal day. Daily restricted feeding also causes a feeding-associated anticipatory activity rhythm. The importance of catecholaminergic neurons has been suggested in the manifestation of a feeding-associated corticosterone rhythm. In our study, we examined the role of dopaminergic neurons in the development of MAP-induced anticipatory activity. The development of MAP-induced anticipatory activity was blocked by coadministration of dopamine D2 receptor antagonists such as YM-09151-2 and sulpiride, the D1 receptor antagonist SCH23390 and haloperidol weak D1/D2 receptor antagonist, but not by clozapine. The anticipatory activity increase was reproduced by daily injection of the D2 receptor agonist quinpirole as well as moderately by the D1 receptor agonist SKF38393. Moreover, MAP-induced anticipation was blocked by coadministration of the N-methyl-D-aspartate receptor antagonist MK-801 or sigma ligands rimcazol and NE-100. Our results suggest that activation of the dopaminergic system, especially via D2 receptors may be required for the development of MAP-associated anticipatory activity increases and that N-methyl-D-aspartate receptors and sigma receptor mechanisms are also involved in the development of this behavior.

Estimation of the total saliva volume produced per day in five-year-old children

Fifteen boys and 15 girls were asked to record for 2 days the time spent awake, eating meals or snacks, and sleeping. The salivary flow rates elicited by chewing foods were also determined. The mean flow rate (+/- SD) of unstimulated saliva was 0.26 +/- 0.16 ml/min and that of saliva while chewing six different foods was 3.6 +/- 0.8 ml/min. The mean times spent eating, and awake but not eating, were 80.8 +/- 27.3 and 820 +/- 59 min, respectively, and the volumes of saliva produced during those periods would average about 288 and 208 ml, respectively. If the flow rate is virtually zero during sleep, the estimated total salivary volume produced per day is calculated to be about 500 ml.

Topography of somatosensory evoked magnetic fields following posterior tibial nerve stimulation

The topography of somatosensory evoked magnetic fields (SEFs) following stimulation of the right and left posterior tibial nerves was investigated in 5 normal subjects (10 nerves). The main deflections N37m-P45m-N60m-P75m and their counterparts P37m-N45m-P60m-N75m were identified in the hemisphere contralateral to the stimulated nerve. Their equivalent current dipoles (ECDs) were located in the foot area of the primary sensory cortex (SI), probably in area 3b. Restricted minor deflections, P40m-N40m and N50m-P50m, were considered to be generated in area 1 in SI. As the generator sources of P37m-N37m, P40m-N40m and N45m-P45m were temporarily changed and interfered with each other, the direction of ECDs appeared to be rotated with the passage of time. Small middle-latency deflections, N100m-P100m, were clearly identified in 2 subjects. ECDs of these deflections were found in the second sensory cortex (SII), in both hemispheres, although they were clearer in the hemisphere contralateral to the stimulated nerve. In conclusion, short- and middle-latency SEFs are mainly generated in area 3b in SI contralateral to the stimulated nerve, and responses generated in area 1 of SI and SII affect the SEFs to some degree, but interindividual differences are large compared with SEFs evoked by upper limb stimulation.

[Searching for hepatitis C virus by immunoelectron microscopy and its morphology]

Many investigators have searched for the causative agent(s) of blood-borne non-A, non-B hepatitis in sera and liver from patients and experimental animals, and have reported various virus-like particles, morphologically resembling parvovirus, togavirus, picornavirus, hepadnavirus, paramyxovirus, papovavirus, retrovirus or bunyavirus. Despite extensive effort, none of these virus-like particles has been confirmed universally as an etiologic virus because of the absence of immunological identification. The frustration was solved by the success in cloning cDNA of the genome of hepatitis C virus (HCV), a major etiologic agent of human non-A, non-B hepatitis, in 1989, but the morphology of HCV remained in riddles. We attempted to visualize HCV by indirect immunogold electron microscopy, using specific antibodies to the putative HCV envelope 1 protein and succeeded in identifying HCV particle in HCV-RNA-rich plasma. Our study showed that HCV particles are 55-65 nm spherical particles with 6 nm fine surface spike-like projections, and have a 30-35 nm inner core.

[The effects of sevoflurane on the coronary circulation in the instrumented dog with or without coronary stenosis]

The effects of sevoflurane on the coronary circulation were investigated in the instrumented dogs with or without coronary stenosis. A-V block was produced by injection of formalin into A-V node to control heart rate at 120 beats.min-1 by pacing and mean systemic blood pressure was held constant at 65 mmHg with the pressurized blood reservoir. Left anterior descending coronary artery was cannulated with stainless steel tube supplied from the femoral artery. Total coronary flow was measured with an electromagnetic flow probe and the regional myocardial blood flow was calculated using color microsphere technique. Coronary resistance was reduced with the increasing end-tidal concentrations of sevoflurane up to 1.2 MAC. An adjustable screw clamp was used to reduce the coronary flow down to 50% of control value. Inner/outer ratio of regional myocardial blood flow decreased with stenosis, but was unaffected with 1.2 MAC of sevoflurane. We concluded that 1.2 MAC of sevoflurane was not strong enough to dilate the coronary artery to produce the transmural steal phenomenon in the dog with coronary stenosis. Further investigations are needed to clarify how hemodynamic factors influence the transmural steal phenomenon in myocardium.

Somatosensory evoked magnetic fields after mechanical stimulation of the scalp in humans

Somatosensory evoked magnetic fields after mechanical stimulation by air-pressure-induced tapping which was applied to the forehead and occiput were examined in normal human subjects. The equivalent current dipole (ECD) of the initial magnetic field, 1M, was identified in the primary somatosensory cortex (SI) in the hemisphere contralateral to the stimulation. The ECD of the subsequent magnetic fields, 2M, was identified in bilateral second sensory cortices (SII). The ECD position of 1M in SI generated after the scalp stimulation was closely inferior to the hand area of the SI, which was consistent with the well-known somatotopic organization, 'homunculus'.

Intrahippocampal administration of (+)-SKF 10,047, a sigma ligand, reverses MK-801-induced impairment of working memory in rats

In order to clarify the roles of the hippocampal sigma site and phencyclidine (PCP) binding site on the NMDA receptor/channel complex in the regulation of working memory in rats, the effects of intrahippocampal administration of ligands for both binding sites on this behavior were examined with a three-panel runway task. MK-801, a potent noncompetitive NMDA antagonist with high affinity for the PCP site, significantly increased the number of working memory errors (attempts to pass through two incorrect panels of the three panel-gates at four choice points), when injected bilaterally at 0.1 and 0.18 microgram/side into the dorsal hippocampus. However, intrahippocampal injection of (+)-SKF 10,047, a sigma ligand, at doses up to 1.0 microgram/side had no significant effect on the number of working memory errors. The working memory impairment induced by intrahippocampal MK-801 (0.18 microgram/side) was attenuated by concurrent injection of 1.0 microgram/side (+)-SKF 10,047, but not by that of 1.0 microgram/side (-)-SKF 10,047. These results suggest that activation of hippocampal sigma and PCP binding sites exerts antagonistic effects on working memory function, possibly through modulation of NMDA receptor-mediated glutamatergic neurotransmission.