Rectal immunization with antigen-containing microspheres induces stronger Th2 responses than oral immunization: a new method for vaccination

The rectum as an effective site for induction of systemic and local immunity has received little attention. Rectal immunization with microspheres-containing ovalbumin (MS-OVA) was tested for its ability to elicit systemic and mucosal immune responses. Rectal immunization with MS-OVA enhanced both Th2 dominant OVA-specific IgG levels in the serum and OVA-specific IgA levels in fecal extracts more prominently than did oral immunization. Cytokine analysis of CD4(+) T cells indicated a predominant induction of Th2-type responses compared to Th1-type responses following rectal immunization compared to oral immunization. These results demonstrate that rectal immunization with microspheres could be an effective new vaccination method.

Therapeutic effects on intestinal Behçet's disease of an intravenous drug delivery system using dexamethasone incorporated in lipid emulsion

Recurrent intestinal ulcer is a frequent problem in the management of Behçet's disease. However, no standard therapy for intestinal Beheçt's disease has been established. We report two patients with intestinal Behçet disease and recurrent ileal ulcers who were treated successfuly with a lipid emulsion of dexamethasone. In one patient, the cecal ulcer did not relapse after the intravenous administration initiation of a lipid emulsion of dexamethasone once a week, despite the discontinuation of prednisolone. In the other patient, the cecal ulcer showed a healing tendency, and oral administration of prednisolone was reduced from 40 to 15 mg/day after intravenous administration of a lipid emulsion of dexamethasone. Both patients experienced no complications associated with the administration of the emulsion. These results suggest that an intravenous drug delivery system using a lipid emulsion of dexamethasone is useful for treatment of intestinal Behçet's disease.

Successful treatment with steroids of upper gastrointestinal acute graft vs. host disease after hematopoietic stem cell transplantation

A 39-year-old man with acute myeloid leukemia underwent completely matched related hematopoietic stem cell transplantation. On post-transplantation day 83 he was diagnosed as having upper gastrointestinal graft-versus-host disease (GVHD) by endoscopic examination and pathological examination of endoscopic biopsy specimens, and daily administration of 60 mg of water-soluble prednisolone and 50 mg of cyclosporine was started. After steroid therapy, the symptoms of upper gastrointestinal GVHD disappeared completely and endoscopic findings dramatically improved.

Substrate recognition mechanism of carboxypeptidase Y

To clarify the substrate-recognition mechanism of carboxypeptidase Y, Fmoc-(Glu)n Ala-OH (n = 1 to 6), Fmoc-(Glu)n Ala-NH2 (1 to 5), and Fmoc-Lys(Glu)3Ala-NH2 were synthesized, and kinetic parameters for these substrates were measured. Km for Fmoc-peptides significantly decreased as peptide length increased from n = 1 to n = 5 with only slight changes in kcat. Km for Fmoc-(Glu)(5,6)Ala-OH were almost the same as one for protein substrates described previously (Nakase et al., Bull. Chem. Soc. Jpn., 73, 2587-2590). These results show that the enzyme has six subsites (S1' and S1-S5). Each subsite affinity calculated from the Km revealed subsite properties, and from the differences of subsite affinity between pH 6.5 and 5.0, the residues in each subsite were predicted. For Fmoc-peptide amide substrates, the priorities of amidase and carboxamide peptidase activities were dependent on the substrate. It is likely that the interactions between side chains of peptide and subsites compensate for the lack of P1'-S1' interaction, so the amidase activity prevailed for Fmoc-(Glu)(3,5)Ala-NH2. These results suggest that these subsites contribute extensively to substrate recognition rather than a hydrogen bond network.

Analysis of cytokines in the early development of gastric secondary lymphoid follicles in Helicobacter pylori-infected BALB/c mice with neonatal thymectomy

Immunological interaction between the host and Helicobacter pylori seems to play a critical role in follicular formation in gastric mucosa. We reported H. pylori-induced follicular gastritis model using neonatally thymectomized mice. In this study, we investigated the involvement of various cytokines in this model. BALB/c mice were thymectomized on the third day after birth (nTx). At 6 weeks old, these mice were orally infected with H. pylori. Histological studies showed that follicular formation occurred from 8 weeks after the infection and that most of the infiltrating lymphocytes were CD4(+) and B cells. Neutrophils increased transiently at 1 week after the infection. Gamma interferon, interleukin-7 (IL-7), and IL-7 receptor were expressed in the stomach of the nTx mice irrespective of the infection. In contrast, expressions of the tumor necrosis factor alpha, IL-4 and lymphotoxin-alpha genes were remarkably upregulated by the infection. Our findings suggest that follicular formation may require cooperative involvement of a Th2-type immune response, tumor necrosis factor alpha and lymphotoxin-alpha in addition to the Th1-type immune response in H. pylori-induced gastritis in nTx mice.

Intermittent isometric exposure prevents brain retraction injury under venous circulatory impairment

It is recognized that surgical obliteration of the cerebral veins by additional brain compression using retractors is dangerous. However, there is a lack of satisfactory management of this problem. We investigated whether intermittent brain compression can reduce brain injury from cerebral venous circulation disturbances (CVCDs). In Wistar rats (n = 25), a solitary cortical vein was occluded photochemically. The brain surface was compressed by a spring balance and constant compression at 30 mmHg was carried out for 60 min. Intermittent procedure compression protocols included four 15 min compressions at 5 min intervals, intermittent isometric exposure (IM), and intermittent isotonic exposure (IT). Local cerebral blood flow (ICBF) in the compressed area was measured together by laser-Doppler (LD) with the degree of brain compression. After 24 h, the brains were examined histologically. The animals were divided into the following five groups (each n = 5): 1, a sham operated control; 2, cortical vein occlusion (VO); 3, VO + continuous brain compression (CC); 4, VO + IM; and 5, VO + IT. The ICBF decreased significantly during the compression; however, recovery after the series of compressions was observed only in the VO + IM group, not in the VO + CC and the VO + IT groups (p < 0.05). The depth of the brain surface increased stepwise in the VO + IT group compared with the VO + IM group (p < 0.01). The resulting tissue damage was significantly larger in the VO + CC and VO + IT groups than in the vein occlusion group (p < 0.05), but not in the VO + IM group. The results of the present study suggest that intermittent isometric exposure under CVCDs could decrease brain retraction injury during neurosurgical operations and be more beneficial than continuous compression, providing that the compression pressure declines as the process advances.

Comparative study of 2,3,5-triphenyltetrazolium chloride (TTC) and hematoxylin-eosin staining for quantification of early brain ischemic injury in cats

There are no staining methods that can reliably and unequivocally detect final infarcts in the acute stage of experimental ischemia. In most instances, 2,3,5-triphenyltetrazolium chloride (TTC) and hematoxylin and eosin (HE) stainings are accepted for this purpose, but neither is perfect. We performed a comparative study of the TTC immersion method and HE staining for quantification of early brain ischemic injury in cats, focussing on the reproducibility associated with planimetry. Focal brain ischemia was produced by middle cerebral artery (MCA) occlusion via the transorbital approach in 14 cats. After 6 h of occlusion, two slices of 3 mm thickness, passing through the optic chiasma and mammillary body, were selected for pathological examination. TTC immersion and HE staining were both used for planimetric study of the surface of the same slice. The area of the injury was traced manually with the aid of computerized digital planimetry and expressed as a percentage of the area of the contralateral hemisphere. The area of hemispheric injury and the area of gray matter injury were separately calculated in the TTC specimens, and each was compared with the area of gray matter injury in the HE-stained specimens. Measurements were repeated twice on each slice to estimate errors associated with manual tracing of the boundary of the area of injury. The mean percentage values of the area of injury in the TTC-immersed gray matter specimens were lower than those detected by HE staining, although there was a very significant correlation between the two. The differences between each two measurements of TTC-determined gray matter injury were significantly less than those between each two measurements of HE-determined gray matter injury. The differences between each two measurements of TTC-determined hemispheric injury were slightly less than those between each two measurements of TTC-determined gray matter injury, although there was no significant difference between them. For quantifying ischemic injury after 6 h of MCA occlusion in cats, the TTC immersion method is more reproducible and simpler in manner than HE staining, but the results of both are significantly correlated.

Frequent alterations of the p14(ARF) and p16(INK4a) genes in primary central nervous system lymphomas

To elucidate the role of p53/p16(INK4a)/RB1 pathways in the tumorigenesis of primary central nervous system lymphomas (PCNSLs), we have analyzed p14(ARF), p16(INK4a), RB1, p21(Waf1), and p27(Kip1) status in a series of their 18 sporadic cases of diffuse large B-cell lymphoma, using methylation-specific PCR, differential PCR, and immunohistochemistry. Homozygous deletion or methylation of p14(ARF) was detected in 10 (56%) PCNSLs, and they were almost entirely deletions (except 1 case). A total of 11 (61%) PCNSLs demonstrated homozygous deletion (6 cases) or methylation (5 cases) of p16(INK4a). Six tumors showed both p14(ARF) and p16(INK4a) homozygous deletions. Hypermethylation of the RB1 and the p27(Kip1) promoter region was detected in 2 (11%) cases, whereas p21(Waf1) methylation was not detected in any. Immunohistochemistry revealed loss of p14(ARF) and p16(INK4a) expression in 10 (56%) samples, correlating with the gene status. Four cases showed independent negative immunoreactivity for pRB and p27(Kip1), and nearly one-half of cases (8 of 18; 44%) were characterized by lack of p21(Waf1) expression. These results indicate that inactivation of p14(ARF) and p16(INK4a) by either homozygous deletion or promoter hypermethylation represents an important molecular pathogenesis in PCNSLs. Hypermethylation of RB1, p21(Waf1), and p27(Kip1) appears to be of minor significance, these genes being independently methylated in PCNSLs.

[Experimental study of pharmacological hypothermia: enhanced neuroprotective effect of a novel 5-HT 1 A agonist SUN N4057 by the pharmacological hypothermia]

PURPOSE

5-hydroxytryptamine(5-HT) 1 A receptor agonists have a potentially marked neuroprotective reaction by both neuroprotective and hypothermic effects. We previously reported (1) the neuroprotective effect against the cerebral ischemia under normothermic condition, and (2) the hypothermic effect of the novel compound of 5-HT 1 A agonist, SUN N4057. The present investigation was designed to examine the enhancement of the neuroprotective effect by its pharmacological hypothermia.

METHODS

In 24 anesthetized cats(body weight 1.9-4.6 kg), the left middle cerebral artery(MCA) occlusion was performed via the transorbital approach. Just after MCA occlusion, SUN N4057(6 micrograms/kg/min) was infused. Physiological parameters were measured continuously, and arterial blood gas was analyzed hourly for 6 hours and maintained within the normal ranges. Animals were randomly allocated to the following three groups: (1) ischemic controls infused with sterile saline(Group A, n = 8), (2) SUN N4057 under normothermic condition(Group B, n = 8), (3) SUN N4057 (Group C, n = 8). Then, brain coronal sections of 3 mm in thickness were stained with 1% triphenyltetrazolium chloride(TTC) solution, and hemispheric infarct volumes were calculated by using a computerized image analysis system.

RESULTS

There were no significant differences in any physiological parameters among 3 groups. In Group C, brain temperature decreased significantly starting 1 hour after MCA occlusion and dropped by 2.1 +/- 0.7 degrees C 5 hours. Infarct volumes were 35.6 +/- 6.9% (Group A), 23.3 +/- 5.8% (Group B) and 12.3 +/- 11.3% (Group C), respectively. There were significant differences among three groups(p < 0.05).

CONCLUSION

On the basis of these data, we conclude that SUN N4057 provides more effective neuroprotection by the combination of hypothermic and neuroprotective effects. Chemical hypothermia may lead to a new therapeutic approaches for treatment of brain ischemia.

A critical role for IL-7R signaling in the development of Helicobacter felis-induced gastritis in mice

BACKGROUND & AIMS

Interleukin (IL)-7 is a critical cytokine in the development of T and B cells and is involved in gastrointestinal pathophysiology. The aim of this study was to investigate the involvement of IL-7 receptor (IL-7R) signaling in Helicobacter-induced gastritis.

METHODS

C57BL/6 mice (n = 40) were inoculated with H. felis. Twenty mice were injected intraperitoneally with neutralizing IL-7R antibody (A7R34) every seventh day for 3 months. Histology, serum anti-H. felis antibody, and gene expression of IL-7, IL-7R, and proinflammatory cytokines in the gastric mucosa were evaluated.

RESULTS

Seventeen of 20 (85%) infected mice without A7R34 developed severe atrophic gastritis, whereas there was no gastritis in A7R34-treated infected mice. There was no difference in the serum levels of anti-H. felis antibody between the 2 groups. IL-7, IL-7R, IL-1alpha, tumor necrosis factor alpha, and interferon gamma messenger RNA expressions were up-regulated in control infected mice, whereas only IL-7 messenger RNA was up-regulated in A7R34-treated infected mice. Immunohistochemistry indicated positive cytoplasmic staining of IL-7 in the gastric epithelial cells.

CONCLUSIONS

These data suggest a critical role for IL-7 receptor signaling in the development of Helicobacter-induced gastritis in mice.

[The effect of C 1 esterase inhibitor on ischemia: reperfusion injury in the rat brain]

BACKGROUND

Despite the current interest in thrombolytic therapy for acute stroke, ischemia-reperfusion injury remains a potentially hazardous complication. The complement system is thought to play a major role in initiating some of the inflammatory events occurring in the reperfusion injury. This study was conducted to explore the effect of C 1 esterase inhibitor (C 1 INH) on the reperfusion injury in rat middle cerebral artery (MCA) occlusion-reperfusion model.

METHODS

Twenty-nine male Wistar rats were used. Intraluminal MCA occlusion was performed for 60 minutes. Just before the reperfusion, C 1 INH(50 IU/kg, C 1 INH group, n = 15) or saline (control group, n = 14) was administrated. Forty-eight hours after the reperfusion, infarct volume and myeloperoxidase(MPO) activity of the brain were evaluated.

RESULT

Infarct volume and MPO activity were significantly smaller in the C 1 INH group(86.5 +/- 76.8 mm3, 0.38 +/- 0.30 U/g) than in control group(179 +/- 92.8 mm3, 1.37 +/- 0.46 U/g) (p < 0.01).

CONCLUSION

The results of this study provided the first evidence that C 1 INH reduced polymorphonuclear leukocytes(PMN) accumulation and reperfusion damage in the brain.

A scanning technique to measure regional cerebral blood flow and oxyhemoglobin level

OBJECTIVE

The application of a laser scanning technique to measure regional cerebral blood flow (CBF) and tissue hemoglobin oxygenation (HbO2) using the rat closed cranial window preparation is described.

METHODS

Twenty-nine male Wistar rats were used to consecutively measure local CBF by laser Doppler flowmetry and tissue HbO2 by a microspectrophotometric method at multiple corresponding cortical locations. The scanning technique used a computer-controlled micromanipulator. Data from three experimental models are presented: the whisker stimulation model, the ischemia-reperfusion model, and the sinus-vein thrombosis model. Sequential changes in local CBF and HbO2 data before, during, and after stimulation, ischemia, and sinus thrombosis were examined. Data from predefined locations within the same region were correlated with the topographical location and then arranged in a three-dimensional image.

RESULTS

In the whisker stimulation model, we found a disproportionate increase in CBF (32 +/- 12%) as compared with that of HbO2 (9 +/- 4%) during stimulation. In the ischemia-reperfusion model, the three-dimensional image showed heterogeneous low CBF (depending on the area) and homogeneous HbO2 at a reduced level during ischemia and postischemic hyperperfusion. However, the range of oxygenation was normal after reperfusion. In the sinus-vein thrombosis model, drainage of the unsaturated blood via the collateral pathways was noted.

CONCLUSION

The laser scanning technique is useful for visualizing sequential changes in hemodynamic-metabolic interactions of cortical brain tissue. This technique can reveal phenomena not detected by traditional monitoring procedures.

An oral drug delivery system targeting immune-regulating cells ameliorates mucosal injury in trinitrobenzene sulfonic acid-induced colitis

Control of immune-regulating cells in the colonic mucosa is important in the treatment of patients with inflammatory bowel disease (IBD). The aim of study was to examine the therapeutic effect of dexamethasone (DX) microspheres on 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats, a model for human Crohn's disease. DX microspheres and DX alone were administered orally to rats with TNBS-induced colitis. The macroscopic score, histological score, myeloperoxidase (MPO) activity, nitric oxide (NO) production, and gene expressions of proinflammatory cytokines, cyclooxygenase (COX)-1, and COX-2 in the colonic tissue were determined. Proliferating cell nuclear antigen (PCNA) staining and expression of nuclear transcription factor (NF)-kappaB in colonic tissues were also investigated. Macroscopic score, histological score, MPO activity, and NO production in rats treated with DX microspheres were significantly lower than in those treated with DX alone. The gene expression of proinflammatory cytokines and COX-2 in rats treated with DX microspheres was down-regulated, compared with that in rats treated with DX alone. The number of PCNA-positive cells in the DX microsphere group was larger than in the group treated with DX alone. DX microspheres suppressed NF-kappaB activation in TNBS-induced colitis more strongly than DX alone. Oral administration of DX microspheres appears to ameliorate mucosal injury in TNBS-induced colitis. This drug delivery system could be an ideal therapy for human IBD.

Budd-Chiari syndrome and extrahepatic portal obstruction associated with congenital antithrombin III deficiency

We report a patient with Budd-Chiari syndrome (BCS) and extrahepatic portal obstruction (EHO) associated with congenital antithrombin (AT) III deficiency. A 35-year-old man was admitted to Nishi Kobe Medical Center for evaluation of abnormal intrahepatic veins. By various imaging modalities, BCS and EHO were diagnosed. Laboratory data revealed parallel decreases in activity and antigen concentration of AT III despite normal liver function. Taken together, the etiology of both BCS and EHO was considered to be thrombosis, associated with congenital AT III deficiency. Two years after beginning warfarin therapy, the patient has no symptoms and his liver function remains normal. Anticoagulant therapy is considered useful for preventing progression of the disease.

Effects of Helicobacter pylori infection on Zollinger-Ellison syndrome

Both Zollinger-Ellison syndrome (ZES) and Helicobacter pylori infection are major etiologic factors for peptic ulcer. The aim of this study was to investigate the effect of H. pylori infection on ZES with special reference to acid secretion. Sixteen patients with ZES were selected (median age, 59 years; range, 39-66 years; M/F, 9/7), and H. pylori status, ulcer location, gastric acid secretion, serum pepsinogen (PG) I and II concentrations, and PG I/II ratio were determined. The seroprevalence of H. pylori infection was 50%, whereas active H. pylori infection was seen in only 25% of the patients. Thirteen patients had duodenal ulcer (DU), 1 had gastric ulcer (GU), and 2 had both GU and DU. DU was seen in both H. pylori-positive and H. pylori-negative patients, whereas GU was found only in H. pylori-positive patients. Both basal and maximal acid outputs were significantly lower in H. pylori-positive patients than in H. pylori-negative patients (P< 0.05). Moreover, both serum PG I and the PG I/II ratio were significantly lower in H. pylori-positive patients than in H. pylori-negative patients. These results indicate that ZES is an independent risk factor for DU, but H. pylori infection may play some role in the development of GU in ZES. In patients with ZES, H. pylori infection may reduce both hypersecretion from parietal cells and PG I secretion from chief cells, and hyperacidity of the stomach in ZES may have eradicated H. pylori in some patients.

[Neuroprotective effect of a neurotoxin, 3-nitropropionic acid, against hypoxic damage to the gerbil hippocampus: neuroprotection after the onset of hypoxic depolarization]

Ischemic/hypoxic tolerance induced by a subtoxic dose of neurotoxin, 3-nitropropionic acid(3-NPA), was recently reported as "chemical preconditioning". We previously showed that the neuroprotective effect by chemical preconditioning with 3-NPA was induced by prolonging the delay to hypoxic depolarization (HD) via activating adenosine receptors. In this study, we electrophysiologically assessed whether the protective effect of chemical preconditioning was potent after the onset of HD. An in vitro hippocampal slice model from adult gerbils was used to study the delay to HD during hypoxia and the recovery of synaptic responses after hypoxia. Hypoxia was sustained until a fixed period(8 min) following HD. These responses were examined in control slices and slices pretreated with subtoxic dose of 3-NPA(4 mg/kg) intraperitoneally at 3 hours prior to slice preparation. The delay to hypoxic depolarization in 3-NPA treated slices was significantly prolonged(p < 0.05). The field excitatory postsynaptic potential recovery after a fixed period of hypoxia under HD was also significantly improved in the 3-NPA treated group(48.6 +/- 23.8%) compared with the control group(29.2 +/- 12.2%) (p < 0.05). This finding indicates that chemical preconditioning with 3-NPA induces the neuroprotective effect against hypoxic damage after as well as before the onset of HD to the hippocampus.

[Microcirculatory changes in the development of the cerebrovascular adaptation]

Recently, long-term cerebrovascular adaptations after unilateral carotid ligation that increase the tolerance of the brain to subsequent episode of ischemia was reported(J Cereb Blood Flow Metab, 1998). However, the pathophysiological mechanisms underlying the phenomenon was unknown. We examined regional cerebral blood flow(rCBF) before, during and after subsequent ischemia in the development of the adaptation. Male Wistar rats(n = 18) were used. Unilateral(right) carotid artery ligation was performed 3 hours(group A: n = 8), 3 days(group B: n = 10) before forebrain ischemia. With bilateral carotid arteries occlusion, mean arterial blood pressure(MABP) was reduced by hypobaric hypotension down to 50 mmHg and maintained constant for 30 min. After hypotension, the experiment continued for 90 min. Local CBF were registered at 25(5 x 5) identical locations by laser Doppler scanning in the cortex during the experiment in bilateral hemispheres(at control phase, after the left carotid artery ligation, during ischemia and after hypotension). The physiological variable such as blood pressure and gas analysis were within normal range in all groups. There were no differences of rCBF between the right and left hemispheres in group A during the experiment. In group A, rCBF of both hemispheres significantly decreased after the ligation of the left carotid artery, during the induced ischemia (P < 0.05), and recovered to the value of before ischemia. Whereas, in group B rCBF of the left side(non-occluded side) decreased after the ligation of the left carotid artery, during the induced ischemia(P < 0.05), and recovered to the value of before ischemia, but rCBF of the right side(occluded side) decreased only during the induced ischemia(P < 0.05) and rCBF of the right side was significantly higher than the left brain after ligation of the carotid artery, during ischemia and after hypotension(P < 0.05). On the basis of these data, we concluded that cerebrovascular adaptations can be acquired by 3 days after unilateral carotid artery occlusion and the tolerance phenomenon is certainly attributed to microcirculatory improvement.

mRNA expression of cytokines and chemokines in the normal gastric surface mucous epithelial cell line GSM06 during bacterial infection with Helicobacter felis

BACKGROUND AND AIM

A group of the proinflammatory and chemotactic cytokines (chemokines) has been considered as an important factor in the pathomechanism of different bacterial diseases, among them the common Helicobacter pylori infection. Experimental results obtained with gastric biopsy samples of H. pylori positive patients, and with H. pylori infected tumor originated gastric cell lines indicated that these cytokines have essential roles in the development and maintenance of the immune response and inflammation of the gastric mucosa during H. pylori infection. Although the mRNA expression was shown in these biopsy samples and cell lines, it is not yet proved that the normal gastric mucosal epithelial cells themselves express these cytokines. The establishment of a gastric surface mucous cell line with non-tumor origin (GSM06), and the usage of Helicobacter felis as a model of the classic H. pylori infection gave us the possibility to check this question.

MATERIALS AND METHODS

in this study GSM06 cells were infected with different numbers (10(5), 10(6), 10(7), 10(8), 10(9) bacterium/ml medium) of H. felis for two different time periods (2, 4 h). Cells treated with medium only were used as control. Then the mRNA expression of the following cytokines was measured by RT-PCR method in the GSM06 cells: proinflammatory cytokine IL1-beta, and chemokine RANTES, eotaxin, MCP-1, MIP1-alpha and MIP1-beta.

RESULTS

we found that neither mRNA of the investigated cytokines was expressed constitutively, however the GSM06 cells expressed the mRNA of each cytokine during H. felis infection.

CONCLUSION

our results prove that normal gastric surface mucous epithelial cells express immunologically active peptides during H. felis infection. We may suppose that the epithelial cells of the gastric mucosa contribute to the immune response and inflammation by expressing proinflammatory (IL1-beta) and chemotactic (RANTES, eotaxin, MCP-1, MIP1-alpha and beta) cytokines during H. pylori infection in human.

Chemical preconditioning with 3-nitropropionic acid in gerbil hippocampal slices: therapeutic window and the participation of adenosine receptor

Ischemic tolerance induced by a subtoxic dose of neurotoxin, 3-nitropropionic acid (3-NPA), was recently reported as "chemical preconditioning." We electrophysiologically investigated the therapeutic window and the effect via action at the adenosine receptor using a gerbil hippocampal slice model of the tolerance phenomenon. 3-NPA at the dose of 4 mg/kg was administered intraperitoneally at 3, 24, and 72 h prior to slice preparation. Prolonged delay to hypoxic depolarization (HD) and improvement of the field excitatory postsynaptic potential recovery following a fixed period of hypoxia (8 min) were observed in the groups pretreated at 3 and 24 h compared with the control (P < 0.05). Correlation between the delay to HD and the recovery was highly significant (r = 0.37, P < 0.001). These effects were completely reversed by administration of theophylline (20 mg/kg), an adenosine receptor blocker. These findings indicate that chemical preconditioning with 3-NPA induces early onset (3 h) and long-lasting (24 h) tolerance of hypoxic damage to excitatory synaptic mechanisms in the hippocampus by delayed calcium entry, and the activation of adenosine receptor contributes to this neuroprotective effect.

The effect of brain compression under venous circulatory impairment

It is well known that surgical obliteration of the cerebral veins with additional brain compression by retractors is dangerous. To evaluate the mechanism, we studied the change in cerebral microcirculation and parenchymal damage following brain compression with venous circulatory impairment using a rat model. The animals were divided into the following four groups (each n = 5) (1) a sham-operated control; (2) group A, one cortical vein occlusion; (3) group B, a 30 mmHg compression pressure; and (4) group C, one cortical vein occlusion with 30 mmHg compression. The cortical vein was occluded photochemically. Local cerebral blood flow (l-CBF) in the compressed area was measured by stationary laser-Doppler (LD) flowmetry and regional CBF (r-CBF) in the surrounding area was also measured by LD scanning technique for 120 min. l-CBF in the compressed area decreased significantly in groups B and C. A gradual and significant increase in group B and decrease in group C in r-CBF of the surrounding area were observed. Histologically, more extensive damage was observed in group C than in group A and B. The degree of hypoperfusion of the affected brain correlated well with the subsequent brain damage in the experiments. We demonstrated that, compared with vein occlusion or brain compression alone, the accumulated episode caused severe ischemia, then increased the vulnerability of the rat brain to tissue damage.

Surgery for dural arteriovenous fistula in superior sagittal sinus and transverse sigmoid sinus

The aim of this study was to evaluate the outcome of surgically treated dural arteriovenous fistula (DAVF). The authors performed surgical removal of DAVF in 12 patients. The locations of DAVF were the transverse sigmoid sinus in seven patients and superior sagittal sinus in five patients. These 12 patients had undergone endovascular embolisation prior to removal. Among them, six patients were completely cured, according to angiography immediately after embolisation, but these six patients showed the recurrence of DAVF within 1 year. The other six patients showed a decrease of feeding vessels. Therefore, all 12 patients underwent surgical removal of DAVF. The surgical strategies were as follows. The feeding vessels and the cortical veins with retrograde filling were occluded and cut. The affected sinus was skeletonised, and if it was occluded or almost occluded, the sinus was removed. Postoperatively, transient aphasia was seen in one patient. There was no surgical morbidity or mortality. During the follow-up period (mean 2.9 years), no recurrence of DAVF was seen. Surgical treatment is a safe and effective treatment manoeuvre for DAVF around the transverse sigmoid sinus and superior sagittal sinus.

Alexia caused by a fusiform or posterior inferior temporal lesion

We evaluated the alexia and agraphia of three patients with different lesions using Japanese kanji (morphograms) and kana (phonograms) and made a lesion-to-symptom analysis. Patient 1 (pure alexia for both kanji and kana and minor agraphia for kanji after a fusiform lesion) made more paragraphic errors for kanji, whereas patient 2 (alexia with agraphia for kanji after a posterior inferior temporal lesion) showed severe reading and writing disturbances and more agraphic errors for kanji. Brodmann Area 37 was affected in both patients, but in patient 2 the lesion was located lateral to that in patient 1. Patient 3 showed agraphia without alexia after restricted lesion to the angular gyrus. We believe that pure alexia (patient 1) results from a disconnection between the medial fusiform gyrus and posterior inferior temporal area (the lateral fusiform and inferior temporal gyri), whereas alexia with agraphia for kanji (patient 2), corresponding to lexical agraphia in Western countries, results from damage to the posterior inferior temporal area, in which whole-word images of words are thought to be stored. Furthermore, restricted lesion in the angular gyrus (patient 3) does not produce alexia; the alexic symptom of "angular" alexia with agraphia may be the result of damage to the adjacent lateral occipital gyri.

Early-onset tolerance in rat global cerebral ischemia induced by a mitochondrial inhibitor

It was studied whether a subtoxic dose of the mitochondrial neurotoxin, 3-nitropropionic acid (3-NPA), can initiate early-onset tolerance induction for subsequent ischemic injury. Wistar rats were pretreated for 3 h by intraperitoneal 3-NPA (20 mg/kg body weight; n=13) or solvent (n=12). Fifteen minutes global cerebral ischemia was induced by bilateral carotid artery occlusion and hypobaric hypotension. rCBF and tissue hemoglobin oxygen saturation were measured by laser Doppler scanning and a microspectrophotometric method. Ischemic insult and brain temperature were identical in both groups. Body weight and neurological scores recovered in the pretreated group but further deteriorated in the non-treated group (P<0.05). Quantitative histology demonstrated a better neuronal density in neocortex and hippocampal CA2, CA3, and CA4 of pretreated animals (P<0.05).