Effects of reversible shutdown of the monkey flocculus on the retention of adaptation of the horizontal vestibulo-ocular reflex

There are two different proposals regarding the role of the cerebellar flocculus in the adaptation of the vestibulo-ocular reflex: that the flocculus is the site for both the induction and retention of the adaptation, or that the flocculus plays an important role in the induction, but the vestibular nuclei to which the flocculus issues its efferents are the site of retention. To locate the memory trace for the adaptation of the vestibulo-ocular reflex, we determined effects of acute pharmacological shutdown of the bilateral cerebellar flocculi in four Macaca fuscata. The gain of the horizontal vestibulo-ocular reflex was measured by sinusoidal oscillation of the turntable by 10 degrees (peak-to-peak) at 0.33 Hz in the dark. Two hours of 0.33 Hz-10 degrees sinusoidal oscillation of the turntable while viewing the stationary checked-pattern screen through a x2.2 magnifying lens adaptively increased the horizontal vestibulo-ocular reflex gain by 0.2 on the average. The gain increase lasted for 1 h when the monkeys were left with their heads fixed in darkness, but it disappeared within 24 h after the monkeys were returned to their cages where they had free movements. The effects of injections of 5 or 10% lidocaine chloride into the bilateral floccular areas (8 microl for each side) immediately after adaptation occurred were determined in nine sessions. The gain of the horizontal vestibulo-ocular reflex immediately decreased to the level before the adaptation. These effects of lidocaine lasted for at least 1 h. On the contrary, injections of the same amount of Ringer's solution, tested in eight sessions, hardly affected gain of the horizontal vestibulo-ocular reflex over 1-h period. These depressant effects of lidocaine injections were specific to the gains increased by adaptation. These results suggest that the memory trace for the short-term adaptation of the horizontal vestibulo-ocular reflex gain induced by 2 h of sustained visual-vestibular interactions resides within the flocculus.

Do rapid systemic changes of brain temperature have an influence on the brain?

BACKGROUND

The purpose of the present study was to examine the influence of cooling and rewarming conditions using an accurate brain temperature control system.

METHOD

The brain temperature of animals was measured with a thermometer while feedback regulation was achieved with a cold (4( degrees )C) and hot (50( degrees )C) water on-off flow system. Brain temperature was well controlled throughout the experiment by using both cold water and hot water simultaneously. Three groups were studied, as follows: 1) the standard group (cooled to 24( degrees )C for 1 hour, kept at 24( degrees )C for 2 hours and rewarmed to 37( degrees )C for 1 hour), 2) the rapid-cooling group (cooled to 24( degrees )C for 30 min, kept at 24( degrees )C for 2 h, and rewarmed to 37( degrees )C for 1 h), 3) the rapid-rewarming group (cooled to 24( degrees )C for 1 h, kept at 24( degrees )C for 2 h, and rewarmed to 37( degrees )C for 30 min) and the normal-control group.

FINDINGS

An increase of MAP-2 immunoreactivity of the CA1 neurons in the dorsal hippocampus was observed one week but not one month after hypothermia in the rapid-rewarming group. There was also a significant increase in the glutamate and lactate value at the end of rewarming compared with the baseline in the rapid-rewarming group (p<0.01).

INTERPRETATION

Our results suggest that rapid rewarming after hypothermia triggered an uncoupling of cerebral circulation and metabolism, inducing an increase of extracellular glutamate and lactate, consequently reversible neuronal cell damage.

The use of mild hypothermia for patients with severe vasospasm: a preliminary report

The purpose of this study was to determine the effect of mild hypothermia on cerebral ischaemia due to severe vasospasm, which was refractory to medical and intravascular treatments and to assess the brain protection of this treatment in patients who underwent delayed aneurysm clipping after presenting with ischaemic neurological deficits. Mild hypothermia (32-34 degrees C of brain temperature) was employed in two groups: (1) Patients (Hunt and Kosnik grades I to II) who showed progressive neurological deficits due to vasospasm and did not respond to conventional therapy (Group 1) and (2) Patients who received delayed aneurysm clipping after presenting with ischaemic neurological deficits due to vasospasm (Group 2). Seven of 8 patients in both Groups showed a favorable outcome with mild hypothermia (good recovery in 5 and moderate disability in two patients). Mild hypothermia is considered to be effective on critical cerebral ischaemia due to vasospasm even after failure to response the conventional therapies and to provide brain protection in delayed aneurysm clipping.

Effects of brain hypothermia on brain edema formation after intracerebral hemorrhage in rats

Patients with intracerebral hemorrhage (ICH) may deteriorate progressively after the initial ictus because of the brain edema around the hematoma. Recently, thrombin has become known to play an important role in the brain edema formation after ICH. In this study, we examined the effect of brain hypothermia on brain edema formation after hematoma and thrombin injection into the brain in rats and clarified the mechanism of hypothermia on brain damage. Anesthetized Sprague-Dawley rats received an injection of 100 microL of autologous blood or 10 units of bovine thrombin into the basal ganglia. Animals were divided into the normothermic and hypothermic groups, which were housed in a room at 25 degrees C and in a cold room at 5 degrees C respectively, for 24 hours. Brain water content was significantly reduced with hypothermia in the cortex (80.8 vs. 79.7% p < 0.05) after hematoma induction. After thrombin injection, brain water content was also significantly reduced with hypothermia in the basal ganglia (84.5 vs. 82.2%; p < 0.01), accompanied by a significant reduction in blood-brain barrier (BBB) permeability to Evan's blue (29.4 vs. 11.6 ng/g tissue; p < 0.05) and in accumulation of polymorphonuclear leukocytes (3.03 vs. 0.27 U of myeloperoxidase/g tissue; p < 0.01). This study indicates that brain hypothermia significantly reduces brain edema formation after hematoma and thrombin injection into the brain in rats. Inhibition of thrombin-induced BBB breakdown and inflammatory response with hypothermia appear to contribute to brain protection in this model.

Particulate and dissolved elemental loads in the Kuji River related to discharge rate

In order to investigate influences of discharge rates on fluvial transport behavior of elements in the Kuji River, Japan, suspended and dissolved phase concentrations in the river water were measured together with the water flow rates. The concentrations of suspended particulate matter (SPM) increased by two or three orders of magnitude with the water discharge, and also had seasonal variations. Adsorptive elements or heavy metal elements, which tend to form insoluble compounds, were present generally as suspended forms in the river waters, and their dissolved form concentrations tended to increase with the water discharge. On the other hand, non-adsorptive elements such as alkali and alkaline-earth elements were present as dissolved forms under a normal flow rate condition, but equivalent quantity of suspended species also occurred under a high flow condition. In this case, the dissolved form concentrations decreased with the water discharge. Characterization of SPM with analyses of chemical compositions, scanning electron microscopy (SEM) and X-ray diffractometry (XRD) indicated that clay mineral such as montmorillonite would be the main carrier material of trace and major elements during the fluvial transport in the Kuji River. Variations of contents of selected elements in SPM with the water discharge indicated that river bottom sediments, which are probably potential sources of SPM added due to high water flow rates, would be different in chemical compositions from SPM floating under a normal flow condition. Variations of chemical compositions of SPM as well as of suspended or dissolved form concentrations of elements in the river waters were formulated as a function of the water discharge rates.

Cerebral oxygen metabolism monitoring under hypothermia for severe subarachnoid hemorrhage: report of eight cases

OBJECTIVES

The significance of cerebral oxygen metabolism monitoring under hypothermia for severe subarachnoid hemorrhage (SAH) was studied.

MATERIAL AND METHODS

Cerebral oxygen metabolism monitoring (jugular venous oxygen saturation: SjO2, arterio-jugular venous difference of oxygen: AJDO2, and oxygen extraction fraction:OEF) during hypothermia (32-34 degrees C) was evaluated in eight patients with SAH (severe vasoapasm group: five patients, and severe brain damage group: three patients).

RESULTS

In favorable cases in both groups, each parameter tended to normalize during hypothermia therapy. When changes in SjO2 were normal, however, the value of AJDO2 was low in unfavorable cases in the severe vasospasm group. In unfavorable cases in the severe brain damage group, high level of SjO2 and low level of OEF and AJDO2 were shown even if hypothermia therapy was performed.

CONCLUSIONS

The measurement of SjO2 and AJDO2 is useful for estimation of cerebral oxygen metabolism in patients with severe conscious disturbance after SAH under hypothermia therapy.

Increased expression of mucosal addressin cell adhesion molecule-1 (MAdCAM-1) and lymphocyte recruitment in murine gastritis induced by Helicobacter pylori

Although T cell involvement in Helicobactor pylori-induced gastritis is known, mechanism about T cell recruitment is not understood. In this study we examined how mucosal addressin cell adhesion -molecule-1 (MAdCAM-1) is involved in lymphocyte recruitment in murine chronic gastritis induced by H. pylori. C57 BL/6 mice were infected with Sydney strain (SS1). Six months after infection, the stomach was removed. The expression of adhesion molecules, MAdCAM-1, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), and the cell surface antigens CD4, CD8, CD45R/B220 or beta7-integrin were determined by immunohistochemistry. A significant increase in CD4 lymphocytes was observed in the body portion of stomach in SS1-infected mice and most of these CD4 cells express beta7-integrin, a known counter ligand for MAdCAM-1 molecule. Strong MAdCAM-1 expression was observed adjacent to these cells in the lamina propria as well as in the submucosa of SS1-infected stomach. Quantitative analysis showed that the area of MAdCAM-1 expression well correlated with the infiltration of beta7-integrin positive lymphocytes. On the other hand, expression of ICAM-1 or VCAM-1 in the lamina propria was few even in the SS1-infected stomach. Increased expression of MAdCAM-1 was well correlated to the location of lymphocytes, which express CD4 and beta7-integrin. These results suggest the possibility that MAdCAM-1 may be largely involved in the lymphocyte recruitment in the gastritis mucosa with H. pylori.

Balloon-assisted guglielmi detachable coil placement in wide-necked internal carotid-ophthalmic aneurysms: a report of four cases

We present an endovascular technique for treating wide-necked ophthalmic aneurysms using Guglielmi detachable coils with simultaneous temporary balloon protection. Four illustrative cases of wide-necked ophthalmic aneurysms treated with Guglielmi detachable coils and a temporary balloon are presented. By blocking the parent artery with a non-detachable balloon, the coils could be safely placed in these aneurysms without herniation when the balloon was deflated. All patients exhibited embolic manifestations after the procedure, and the use of simultaneous temporary balloon protection allowed more dense intra-aneurysmal coil packing. Although this technique requires manipulation of a second microcatheter and balloon, which increases its technical difficulties and is a higher-risk procedure than the standard coil placement, it can be used for patients who are not candidates for surgery. Long-term follow-up is needed to determine the final outcome of aneurysms treated by this technique.

Antiproliferative constituents in the plant 8. Seeds of Rhynchosia volubilis

The MeOH extract of the seeds of Rhynchosia volubilis (Leguminosae) showed antiproliferative activity against human gastric adenocarcinoma [MK-1, 50% growth inhibition (GI50): 25 microg/ml], human uterus carcinoma (HeLa, GI50: 30 microg/ml), and murine melanoma (B16F10, GI50: 8 microg/ml) cells. Bioactivity-guided fractionation resulted in the isolation of gallic acid methylester (1), gallic acid (2), 7-O-galloylcatechin (3), 1,6-di-O-galloylglucose (4), 1-O-galloylglucose (5), and trigalloylgallic acid (6), and their antiproliferative activity was estimated. All showed much stronger inhibition against B16F10 cell growth than against HeLa and MK-1 cell growth. Compound 2 and its tetramer (6) with a free carboxyl group showed higher activity than those which did not have a free carboxyl group. In relation to the gallic acid tetramer (6), two gallic acid dimers (ellagic acid and dehydrodigallic acid) and trimers (tergallic acid dilactone and flavogallonic acid dilactone) were tested for their activity, and compared with those of the isolates.

Increased renal expression of monocyte chemoattractant protein-1 and osteopontin in ADPKD in rats

BACKGROUND

Human autosomal-dominant polycystic kidney disease (ADPKD) is variable in the rate of deterioration of renal function, with end-stage renal disease (ESRD) occurring in only approximately 50% of affected individuals. Evidence suggests that interstitial inflammation may be important in the development of ESRD in ADPKD. Han:SPRD rats manifest ADPKD that resembles the human disease. Homozygous cystic (Cy/Cy) rats develop rapidly progressive PKD and die near age 3 weeks. Heterozygous (Cy/+) females develop slowly progressive PKD without evidence of renal dysfunction until the second year of life, whereas heterozygous (Cy/+) males develop more aggressive PKD with renal failure beginning by 8 to 12 weeks of age.

METHODS

To examine the relationship between proinflammatory chemoattractants and the development of interstitial inflammation and ultimately renal failure in ADPKD, we evaluated monocyte chemoattractant protein-1 (MCP-1) and osteopontin mRNAs and proteins in kidneys from Han:SRPD rats.

RESULTS

MCP-1 and osteopontin mRNAs, expressed at low levels in kidneys from normal (+/+) animals at all ages, were markedly elevated in kidneys from 3-week-old Cy/Cy animals. In kidneys from heterozygous (Cy/+) adults of either gender, MCP-1 and osteopontin mRNAs were more abundant than normal; MCP-1 mRNA was more abundant in Cy/+ males than in females. Thus, chemoattractant mRNA expression correlated with the development of renal failure in Cy/Cy and Cy/+ rats. Osteopontin mRNA, localized by in situ hybridization, was moderately expressed in the renal medulla of normal animals; however, this mRNA was expressed at very high levels in the cystic epithelia of Cy/+ and Cy/Cy animals. MCP-1 and osteopontin proteins, localized by immunohistochemistry, were weakly detected in +/+ kidneys but were densely expressed in Cy/Cy and in adult Cy/+ kidneys, primarily over cystic epithelium. Increased expression of chemoattractants was associated with the accumulation of ED-1 positive cells (macrophages) in the interstitium of cystic kidneys.

CONCLUSIONS

We suggest that proinflammatory chemoattractants have a role in the development of interstitial inflammation and renal failure in ADPKD.

Involvement of mucosal addressin cell adhesion molecule-1 (MAdCAM-1) in the pathogenesis of granulomatous colitis in rats

Although increased expression of mucosal addressin cell adhesion molecule-1 (MAdCAM-1) has been demonstrated in inflammatory sites of various diseases, its role in colitis remains unknown. In this study, we examined whether MAdCAM-1 is involved in the pathogenesis of granulomatous colitis induced by peptidoglycan-polysaccharide (PG-PS). Experimental colitis was induced by intramural injection of PG-PS to rat colon. After 3 weeks the colon was removed and the mucosal inflammation was assessed. The area of MAdCAM-1-positive venules and the subsets of infiltrating cells were determined in colonic mucosa by immunohistochemistry. In another experiment, monoclonal antibody against MAdCAM-1 was administered intraperitoneally to examine its attenuating effect on colitis. The intramural injection of PG-PS induced significant colonic inflammation with granuloma formation. The submucosa was drastically thickened with the infiltration of CD4 positive lymphocytes and ED-1 positive macrophages. Intense MAdCAM-1 expression was observed on endothelium of the submucosal venules in inflamed mucosa. Administration of anti-MAdCAM-1 antibody significantly attenuated the PG-PS-induced colonic damage and cell infiltration. Enhanced expression of MAdCAM-1 was demonstrated in venular endothelium of the inflamed colon in PG-PS-induced colitis. The attenuating effect of anti-MAdCAM-1 suggests the importance of the MAdCAM-1-dependent process in the formation of chronic granulomatous colitis.

Incidence of mutation and deletion in topoisomerase II alpha mRNA of etoposide and mAMSA-resistant cell lines

The efficacy of all chemotherapeutic agents is limited by the occurrence of drug resistance. To further understand resistance to topoisomerase II inhibitors, 50 sublines were isolated as single clones from parental cells by exposure to VP-16 (etoposide) or mAMSA (m-amsacrine). Subsequently, a population of cells from each subline was exposed to three-fold higher drug concentrations allowing 16 stable sublines to be established at higher extracellular drug concentration. Finally, 66 sublines were picked up. The frequency and nature of mutations in the topoisomerase II gene in the drug-selected cell lines were evaluated. In order to screen a large number of cell lines, an RNAse protection assay was developed and mismatches were observed in 13.6% of resistant cell lines (12% of resistant cell lines exposed to lower drug concentrations and 18.8% of resistant cell lines exposed to higher drug concentrations). Some of these mutations are located in vital regions of topoisomerase II (phosphorylation sites in the C-terminal or N-terminal, and nuclear localizing signal of topoisomerase II). Our findings suggest that mutations of topoisomerase II gene are an important and frequent mechanism of resistance to topoisomerase II inhibitors.

Degradation characteristics of humic acid during photo-Fenton processes

Changes in the molecular and structural characteristics of humic acid (HA) during photo-Fenton processes were studied. When aqueous solutions at pH 5.0, which contained HA, Fe(III), and H2O2, were irradiated (lambda > 370 nm), the concentrations of total organic carbon (TOC) decreased with increasing irradiation time, indicating that a portion of the HA was mineralized to CO2 during this process. To investigate the changes in molecular and structural characteristics, the HA was reisolated from the reaction mixtures after each period of irradiation. The increased elution volumes required for isolation by gel permeation chromatography indicated that the molecular size of HA decreased as a result of the irradiation. In the FTIR spectra, ether and epoxide functional groups were identified, after irradiation. These products could be formed via radical coupling and/or via peroxy radical addition reactions to the unsaturated groups in the HA, such as vinyl and aromatic groups. Moreover, an analysis of structural fragments in HA by pyrolysis-GC/MS showed that the cinnamic acid moieties (CA) disappeared, as a result of irradiation. In the molecular weight fractionated HA, the majority of the iron species were complexed with the high molecular weight HA fraction, and the CA levels of the high molecular weight fraction were larger than those in the low molecular weight fraction. These results are consistent with residues, as the reactive sites in the photo-Fenton systems. Therefore, the degradation of these sites in the high molecular weight fraction may serve as a factor in decreasing the molecular size of HA.

Long-term activation of the glutamatergic system associated with N-methyl-D-aspartate receptors after postischemic hypothermia in gerbils

OBJECTIVE

The objective of this study was to investigate whether hypothermia would suppress secondary damage in the chronic postischemic stage, in terms of glutamate excitotoxicity.

METHODS

Gerbils underwent 5 minutes of ischemia via bilateral common carotid artery occlusion. Seven groups were studied, as follows: 1) ischemia without treatment group; 2) intraischemic hypothermia group; 3) postischemic hypothermia group (32 degrees C for 4 h); 4) MK-801 treatment group (2 mg/kg, every other day for 1 mo); 5) postischemic hypothermia with MK-801 treatment for 1 week group (2 mg/kg, every other day); 6) postischemic hypothermia with MK-801 treatment for 1 month group (2 mg/kg, every other day); and 7) sham-treated control group. One month after ischemia, histological changes in hippocampal CA1 neurons (assessed using hematoxylin and eosin staining) and memory function (assessed using an eight-arm radial maze) were studied. Extracellular glutamate concentrations were monitored by microdialysis during ischemia and hypothermia. Staining of microglia was performed 1 week and 1 month after ischemia.

RESULTS

MK-801 alone, postischemic hypothermia alone, and postischemic hypothermia with MK-801 treatment for 1 week failed to prevent ischemic neuronal damage and memory function decreases 1 month after the insult (P < 0.05 versus control). However, the postischemic hypothermia with MK-801 treatment for 1 month group exhibited significant protective effects (not significant [P > 0.05] compared with the control group). Extracellular glutamate levels for the intraischemic hypothermia group were significantly low, compared with the postischemic hypothermia group. There was no microglial activation in the postischemic hypothermia at 1 week and 1 month after ischemia groups.

CONCLUSION

Postischemic hypothermia and long-term intermittent administration of MK-801 demonstrated significant neuronal protection, indicating that long-term glutamatergic activation, with changes in N-methyl-D-aspartate receptors, plays a role in neuronal damage in the chronic postischemic stage.

Altered topoisomerase IIalpha and multidrug resistance-associated protein levels during drug selection: adaptations to increasing drug pressure

To understand resistance to topoisomerase II inhibitors, we used four cancer cell lines (ZR-75B, MDA-MB-231, T47D, and MCF-7) and performed a single-step selection process to isolate 50 clones resistant to topoisomerase II inhibitors. Of these, 26 were isolated with VP-16 and 24 with mAMSA. Sixteen of these isolates (four from each cell line; two selected with VP-16 and two with mAMSA) were further exposed to higher drug concentrations. Characterization of the resistant sublines revealed the adaptation that occurs with increasing drug concentration during in-vitro selections. Reduced topoisomerase IIalpha mRNA level was observed in the majority of the initial isolates. This reduction was accompanied by a decrease in topoisomerase II activity. Other isolates showed increased levels of multidrug resistance-associated protein (MRP). With advancing resistance, MRP expression was increased further, concomitantly with some recovery in topoisomerase IIalpha expression and topoisomerase II activity. In these sublines, high levels of resistance were attained as a result of synergism between the reduced topoisomerase IIalpha levels and MRP overexpression. These results extend previous studies demonstrating how cellular adaptation to increasing drug pressure utilizes more than one mechanism. Reduced expression of topoisomerase IIalpha occurs early in the selection process. MRP overexpression can occur early or can help to confer high levels of resistance. In the latter case, MRP overexpression allows some recovery of topoisomerase II activity without loss of high drug resistance.

Effects of hypothermia on intracranial hemodynamics and ischemic brain damage-studies in the rat acute subdural hematoma model

Brain ischemia is the leading pathophysiological mechanism in the development of secondary brain damage after subdural hematoma (SDH). Hypothermia has been used as the effective neuroprotective treatment in clinical and laboratory studies of ischemic brain injury. In this study, we have examined the rat acute SDH model to assess the effect of hypothermia upon intracranial hemodynamics and also upon ischemic brain injury 4 hours after the induction of hematoma. Moderate hypothermia (32 degrees C) did not affect the intracranial pressure nor cerebral perfusion pressure, and it significantly reduced cortical brain edema formation underneath the hematoma (80.88 +/- 0.17%; p < 0.01) compared with the normothermic control group (81.65 +/- 0.52%). This reduction in brain edema formation was comparable to the result of MK-801 (2 mg/kg) treatment (80.95 +/- 0.35%; p < 0.01). Ischemic brain damage detected by H-E staining was also significantly reduced in the hypothermia and MK-801 treated groups (59.1 +/- 12.3 mm3 and 66.4 +/- 13.8 mm3; p < 0.01 and p < 0.05) compared with the normothermic control group (86.6 +/- 20.7 mm3). In conclusion, the present study demonstrates that hypothermia is a potent neuroprotective method and an inhibition of the glutamate excitotoxic process may contribute the protective mechanisms of hypothermia in this rat acute SDH model.