Liver apoptosis after dimethylnitrosamine administration in shrews

Female house musk shrews (Suncus murinus, Insectivora) were given a single i.p. dose of 30 mg/kg dimethylnitrosamine (DMN) at 8 weeks of age which was lethal 36 to 48 hrs after dosing. Liver tissues were collected from shrews killed 3, 6, 16, 24 and 36 hrs after treatment, and the sequential development of the lesions was characterized. DMN induced acute centrilobular cell injury. In 6 hrs, a few cells became apoptotic in the centrilobular area; the number increased at 16 hrs and 24 hrs, and was prominent at 36 hrs. There was no inflammatory reaction or necrosis and hemorrhage was not obvious. These apoptotic cells as well as normal appearing cells in the centrilobular area were labeled by the TUNEL method. In both hepatocytes and endothelial cells, apoptosis was confirmed electron microscopically as nuclear chromatin condensation at the periphery with no mitochondria swelling. When an i.p. dose of 10 mg/kg DMN was given twice at 8 and 9 weeks of age, no acute toxicity was induced, and the liver of shrews surviving for 50 weeks of age was normal with no tumor formation. These findings indicate that a single i.p. administration of 30 mg/kg DMN induced severe and fatal toxicity on liver tissues in shrews due to apoptosis, whereas 2 x 10 mg/kg DMN had no carcinogenic effect.

[CD26/dipeptidyl peptidase IV and thyroid peroxidase as molecular markers for differentiated thyroid carcinoma]

Differential expression of two enzymes, dipeptidyl peptidase IV (CD26/DPP IV) and thyroid peroxidase (TPO), in neoplastic thyroid tissues was studied by Northern blot analysis and histochemical analysis using 31 thyroid tissue specimens of various thyroid diseases. On Northern blot analysis, all 16 differentiated carcinomas (12 papillary and 4 follicular carcinomas) overexpressed CD26/DPP IV mRNA, whereas all 14 benign tissue specimens (4 normal thyroid, 4 Graves' disease, 2 adenomatous goiters and 4 follicular adenomas) showed faint expression of CD26/DPP IV mRNA. All 14 benign tissues expressed high levels of TPO mRNA, whereas all 12 papillary carcinomas strongly underexpressed TPO mRNA. A medullary carcinoma did not show any mRNA expression of either enzyme. TPO mRNA expression in differentiated carcinomas did not always correlate with mRNA expression of thyroglobulin, thyroid stimulating hormone receptor, and thyroid transcription factor-1. Northern blot analysis also revealed that CD26/DPP IV is a more specific marker of differentiated carcinoma than three proto-oncogenes previously reported to increase mRNA expression in thyroid carcinomas: c-met, c-erbB-2, and EGF-R. Histochemically, all 14 benign tissues were CD26/DPP IV negative and strongly TPO positive, while all 12 papillary carcinomas were strongly CD26/DPP IV positive and TPO negative. Three of 4 follicular carcinomas were histochemically positive for the two enzymes. These findings suggest that the differential expression of these two enzymes can be applied to study the thyroid tumorigenesis.

Lectin bindings in non-neoplastic esophageal epithelium and esophageal carcinomas

Lectin binding was examined histochemically in 22 cases of primary esophageal carcinomas (10 well differentiated, 8 moderately differentiated and 3 poorly differentiated squamous cell carcinomas, and 1 undifferentiated carcinoma) and was compared with the adjacent non-neoplastic epithelium by means of a panel of 10 different lectins (RCA-I, WGA, Con A, LCA, SEA, UEA-I, HPA, PNA, DBA and GS-I) on formalin-fixed paraffin-embedded sections. In the non-neoplastic epithelium, RCA-I and WGA showed basal/parabasal binding, Con A, LCA, SEA, UEA-I, HPA and PNA revealed prickle cell binding, while DBA and GS-I only stained the surface cells of the squamous cell layer. In squamous cell carcinomas, no clear difference was evident regarding the grade of differentiation. However, basal/parabasal specific lectins were expressed in all the cases, the prickle cell-specific lectins were expressed less frequently, whereas lectins expressed at the surface cells of the squamous cell layer were only infrequently expressed. Therefore, basal/parabasal cell specific lectins were widely preserved in squamous cell carcinomas. One case of undifferentiated cancer tested was devoid of all the lectins.

The long-term effect of eicosapentaenoic acid on serum levels of lipoprotein (a) and lipids in patients with vascular disease

The effects of eicosapentaenoic acid (EPA) on serum lipoprotein (a) (Lp(a)) and other lipid levels in patients with vascular disease were examined. The serum levels of Lp(a), total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL) and very-low-density lipoprotein (VLDL) were measured in 24 patients with vascular disease. An elevated serum Lp(a) level (39 +/- 22 mg/dl) was noted in 9 patients, elevated total cholesterol level (263 +/- 31 mg/dl) in 12 patients, elevated triglyceride level (240 +/- 98 mg/dl) in 10 patients and elevated LDL level (651 +/- 88 mg/dl) in 6 patients before administration of EPA. EPA (1,800 mg/day) was given to these patients for long periods ranging from 6 to 24 months. The serum levels of Lp(a), TC, TG and LDL were lowered significantly (p < 0.05) after EPA administration for 12 and 18 months, for 6, 12, 18 and 24 months, for 18 months and for 12 and 18 months, respectively. These findings indicated that long-term administration of EPA may lower Lp(a) and serum lipids, which is beneficial for patients with various arterial diseases in terms of preventing progression of the disease.

Activation of heat shock factor 1 in rat brain during cerebral ischemia or after heat shock

Recently, many studies have demonstrated the induction of stress proteins in the mammalian nervous system under various pathological conditions. These altered genetic programs may function to protect individual cells against stressful conditions. However, little is known about the molecular mechanisms regulating these stress responses in animals. We report here the activation of a heat shock factor (HSF) in the rat brain during cerebral ischemia or after heat shock. Gel mobility shift assays revealed an increase in DNA binding activity to the heat shock element (HSE) during the early phases of ischemia. Supershift experiments using specific antisera against HSF1 and HSF2 showed that the ischemia-induced HSE-binding activity was mainly due to HSF1. In the heat-shocked brain, HSF1 was also activated, and the HSE-binding activity was higher in the cerebellum than in the cerebral cortex or hippocampus; Western blot analysis also showed that HSF1 was more abundant in the cerebellum than in the other two brain regions. Our results indicate that heat shock gene transcription is regulated by the activation of HSF1 in both cerebral ischemia and heat shock, and that different brain regions display differential sensitivities in their stress response. The cellular signals for heat shock gene transcription under in vivo pathological conditions will also be discussed.

[Genetic analysis by fluorescence in situ hybridization of lung cancer cells obtained by bronchial brushing]

Fluorescence in situ hybridization was done with specimens obtained by bronchial brushing from 25 patients with abnormal lung shadows. A satellite DNA probe, specific for chromosome 11, was used to detect numerical chromosome aberrations in tumor cell nuclei. Normal diploid human lymphocyte nuclei, which served as control, had two signal spots in 99.6% of the nuclei in response to the chromosome 11 probe. The most frequent signal spots in class V cells (Case 1-7) ranged from 3 to 5, followed by 6 to 8, regardless of histopathological findings of lung cancer. In class I cells (cases 8-11) the signal appearance was similar to that in class V cells. The disease in patients from whom class I cells were obtained was found to be malignant by other diagnostic procedures performed afterward. The abnormalities in cases 13-25 were diagnosed as non-malignant by brush cytology, and clinical course showed a little more than 3 spots. These data indicate that fluorescence in situ hybridization with specimens obtained by bronchial brushing can be useful for detecting numerical chromosome abnormalities and can aid in the rapid diagnosis of lung cancer.

Stimulation of cell proliferation and autoregulation of elastin expression by elastin peptide VPGVG in cultured chick vascular smooth muscle cells

Synthetic elastin peptides, VPGVG or its polymer (VPGVG)n, enhanced the proliferation of smooth muscle cells 1.5-fold during 48 h treatment at the concentrations over 10(-6) M or 1.0 microgram/ml, respectively. Monomeric and polymeric VPGVG sequences reduced elastin synthesis and its mRNA level to one-third and one-half of control respectively under the conditions in which the proliferation of cells were enhanced, but did not change collagen synthesis as measured by bacterial collagenase digestion. The elastin-specific autoregulation by elastin fragments may reflect the feedback regulation of elastin expression which may play an essential role in elastin metabolism under the normal and diseased conditions.

Immunohistochemical features of the human retina and retinoblastoma

The immunohistochemical features of 24 retinoblastoma specimens from 22 patients, 15 with unilateral and 7 with bilateral disease, were examined by the labelled streptavidin biotin (LSAB) method and compared with those of specimens from the remaining morphologically normal retina. In the normal retina, S-100 protein, glial fibrillary acidic protein (GFAP) and vimentin were detected in astrocytes and/or Müller cells. Neurofilament protein was seen in axons of the ganglion cells, synaptophysin was present in both plexiform layers, bcl-2 oncoprotein was seen in ganglion cells and bipolar cells, and neuron-specific enolase (NSE) was detected in ganglion cells, bipolar cells and photoreceptor cells and in their cell processes. While retinoblastoma (Rb) protein expression was noted in ganglion cells, bipolar cells, and some photoreceptor cells, p53 protein was not expressed at all. In all retinoblastomas, strong NSE expression and weak bcl-2 expression was observed in almost all tumour cells and synaptophysin was localized in rosette-forming cells, while tumour cells were devoid of S-100, GFAP, vimentin and neurofilament protein. These findings support the view that retinoblastomas are composed of neuron-committed cells. In addition, no Rb protein expression was detected in retinoblastomas, whereas p53 expression was found in 18 cases (75%).

Induction of mammary carcinomas by the direct application of crystalline N-methyl-N-nitrosourea onto rat mammary gland

The effectiveness of the direct application of crystalline N-methyl-N-nitrosourea (MNU) onto the mammary gland was compared with the systemic intraperitoneal (i.p.) administration method for the induction of mammary carcinomas in female Sprague-Dawley (S-D) rats. The effectiveness was also tested in genetically resistant female Copenhagen (Cop) rats. The 10 mg crystalline MNU was dusted directly onto the right-inguinal mammary gland, or 50 mg/kg body weight MNU solution was given i.p. at 50 days of age. Animals were palpated for tumor detection twice weekly and killed when the tumor reached 1-2 cm in diameter or were necropsied 30 weeks after carcinogen treatment. In S-D rats, all of the 78 tumors produced by dusting were adenocarcinomas. By contrast, 40 tumors produced i.p. were adenocarcinomas, 1 was fibroadenoma, and 5 were lactating adenomas. The cumulative incidence of mammary carcinoma was high in the dusting and the i.p. groups (12/12; 100% and 11/13; 84%, respectively). However, the dusting groups showed a high number of carcinoma per rats (6.5 vs. 3.6; P < 0.01) and short cancer latency (13.8 weeks v.s. 28.1 weeks; P < 0.001) than the i.p. groups. In Cop rats, although low (4/11; 36%), adenocarcinomas were developed by the dusting method. In both strains, adenocarcinomas displayed various degrees of differentiation but no evidence was found for metastasis. For MNU-administration, the direct dusting technique is an effective method and offers added advantages of ease for the induction of mammary carcinomas in rats.

Direct transplantation of chronic myelogenous leukemia cells into nude mice and establishment of a leukemic stem cell (Ph1+, CD34+) line dependent on mouse bone marrow stromal cells in vitro

Peripheral blood cells from a female patient with Ph1-positive chronic myelogenous leukemia (CML) in blast crisis were serially transplanted in BALB/c nude mice for 16 passages. This in vivo cell line, designated CML-N-1, had Ph1 chromosome abnormality and BCR gene rearrangement. The cells expressed CD11b, CD13, CD33, CD34, CD38, and HLA-DR antigens until the 11th passage and subcutaneous tumors produced by these passages were composed of admixtures of immature and maturing cells that differentiated to basophils when cultured in vitro. From the 12th passage on, the tumors became composed mainly of immature cells expressing CD13, CD34, and HLA-DR, and no longer differentiated to basophils even upon in vitro culture. In contrast to the vigorous proliferation in vivo, CML-N-1 cells from any passage failed to proliferate in vitro under standard liquid culture conditions with or without growth factors, such as granulocyte-macrophage colony-stimulating factor, granulocyte colony-stimulating factor, monocyte colony-stimulating factor, interleukin 3, interleukin 6 and stem cell factor. However, a continuously growing cell line, designated CML-C-1, was established by culturing CML-N-1 cells on feeder layers of mouse bone marrow stromal cells. This mouse bone marrow stromal cell-dependent cell line showed immature cell morphology and expressed early myeloid phenotype positive for CD13, CD34, and HLA-DR. These results indicate that mouse bone marrow stromal cells provide a certain growth factor(s) active on human leukemia cells.

Clonal origin of Philadelphia chromosome negative cells with trisomy 8 appearing during the course of alpha-interferon therapy for Ph positive chronic myelocytic leukemia

The transient appearance of a Philadelphia chromosome (Ph) negative clone with trisomy 8 was found in the bone marrow cells from a patient with Ph positive CML during the course of alpha-interferon (IFN) therapy. To determine whether this clone was derived from a Ph positive clone or from some other cell lineage, we performed molecular cytogenetic studies on bone marrow cells from the patient by fluorescence in situ hybridization (FISH). No fusion of BCR-ABL could be detected in cells with trisomy 8, clearly indicating that the Ph negative trisomy 8 clone was not derived from the Ph positive CML population.

Involvement of dysplasminogenemia in occurrence of deep vein thrombosis

Although various hematological disorders have been considered to be etiologic factors in deep vein thrombosis (DVT), the involvement of dysplasminogenemia (DPG) in DVT has not been studied in detail. In 72 consecutive DVT patients, the presence of DVT was suspected based on a history of lower limb swelling and tenderness with acute onset, and was confirmed by duplex scanning, radioisotope venography, or contrast venography. DPG was identified by the observation of dissociation between the activity and antigenicity of plasminogen. Of the 72 patients, 9 (12.5%) were diagnosed as having DPG, and several antithrombin-III deficiency and protein C and S deficiency were identified. The mean age of the genetically normal and DPG patients was 52 +/- 15 and 40 +/- 15 years, respectively (p < 0.05). Thus, these findings suggest that DPG is deeply related to the development of DVT, and that abnormality of the fibrinolytic system is one of the major etiologic factors in DVT.

Appraisal of the use of an externally supported polytetrafluoroethylene graft in left gastric vein to inferior vena cava shunting

OBJECTIVE

To assess the results of left gastric vein to inferior vena cava (IVC) shunts with externally supported (ringed) polytetrafluoroethylene (PTFE) grafts in six patients with considerably dilated left gastric veins who required portal decompression.

DESIGN

Open study.

SETTING

University hospital, Japan.

SUBJECTS

Six patients with advanced portal hypertension and massive oesophageal bleeding.

INTERVENTIONS

The PTFE graft was first anastomosed end to side to the IVC, and then end to end (n = 4) or end to side (n = 2) to the left gastric vein.

MAIN OUTCOME MEASURES

Short term and long term morbidity and mortality.

RESULTS

There were no operative mortality or morbidity. Endoscopic examination postoperatively showed gradual, steady improvement in the oesophageal varices, and the hyperaemic appearance of the mucosa had disappeared within 10 months in all cases. Median follow up was 19 months (range 10-70); one patients rebled after occlusion of the graft at 12 months, one died of hepatocellular carcinoma at 16 months, and the remaining four patients are well with patent grafts at 10, 22, 40, and 70 months, respectively.

CONCLUSIONS

These results confirm the effectiveness of externally supported PTFE grafts in left gastric vein to IVC shunts, and remove the technical restraints that have prevented surgeons from recommending the operation in the past.

Antibody Fc functional activity of intravenous immunoglobulin preparations treated with solvent-detergent for virus inactivation

We report here results of in vitro comparisons of the Fc functional activity of a second-generation intravenous immunoglobulin (IGIV) preparation (Venoglobulin-I) and a third-generation IGIV product that includes a deliberate virus-inactivation step (Venoglobulin-S). Both formulations showed equivalent Fc-mediated function against viral antigens (rubella, influenza A, and influenza B) by single-radial hemolysis test, and against group B Streptococcus, Staphylococcus aureus and Escherichia coli by opsonophagocytosis assay. In addition, we showed by three different immunochemical reactions and by HPLC analysis that both preparations consisted of mostly monomeric IgG and contained very low levels of complement-fixing IgG aggregates. However, IgG aggregation induced by heating at 63 degrees C markedly enhanced fixation of Clq and C3 and binding to Raji cells, indicating that the IgG molecules retained their complement-fixing capacity. Thus, the incorporation of a virus inactivation step in the manufacture of our third-generation IGIV did not alter the Fc functional activities of the IgG, as measured by these in vitro assay systems.

Inactivation and elimination of viruses during preparation of human intravenous immunoglobulin

We report here the results of our evaluation of virus inactivation during the manufacturing steps of two intravenous immunoglobulin (IGIV) preparations. Virus inactivation and/or removal by processing steps, such as ethanol fractionation and polyethylene glycol precipitation, and deliberate virucidal steps, such as solvent/detergent treatment and pasteurization, were tested on a variety of human pathogenic and experimental model viruses, including human immunodeficiency, Hepatitis C, Mumps, Vaccinia, Chikungunya, Vesicular Stomatitis, Sindbis, and ECHO viruses. All viruses were successfully inactivated and/or eliminated by the processing steps studied. In some cases, however, multiple steps were required. We conclude that the incorporation of steps deliberately designed to inactivate or remove viruses during the production of IGIV provides an extra measure of viral safety.

A unique morphology of Epstein-Barr virus-related early gastric carcinoma

Epstein-Barr virus (EBV) involvement in gastric cancer is demonstrated by uniform presence of viral RNA in carcinoma cells as detected by EBV-encoded small RNA in situ hybridization, monoclonal proliferation of EBV-infected carcinoma cells, and elevated antibodies. Our review of selected early gastric cancers found that 46 of 49 EBV-positive lesions (94%) but only four of 97 EBV-negative lesions (4%) conformed to a unique morphology, in which carcinoma cells formed lace patterns of branching and/or anastomosing structures with lymphocytic infiltration in and around the carcinoma nests in the mucosa. We conclude that EBV-related gastric carcinoma has a distinct and characteristic morphology in the early stage of development, and this lace pattern is a biomarker of EBV involvement in early gastric cancer.

Gastric carcinoma: monoclonal epithelial malignant cells expressing Epstein-Barr virus latent infection protein

In 1000 primary gastric carcinomas, 70 (7.0%) contained Epstein-Barr virus (EBV) genomic sequences detected by PCR and Southern blots. The positive tumors comprised 8 of 9 (89%) undifferentiated lymphoepithelioma-like carcinomas, 27 of 476 (5.7%) poorly differentiated adenocarcinomas, and 35 of 515 (6.8%) moderately to well-differentiated adenocarcinomas. In situ EBV-encoded small RNA 1 hybridization and hematoxylin/eosin staining in adjacent sections showed that the EBV was present in every carcinoma cell but was not significantly present in lymphoid stroma and in normal mucosa. Two-color immunofluorescence and hematoxylin/eosin staining in parallel sections revealed that every keratin-positive epithelial malignant cell expressed EBV-determined nuclear antigen 1 (EBNA1) but did not significantly express CD45+ infiltrating leukocytes. A single fused terminal fragment was detected in each of the EBNA1-expressing tumors, thereby suggesting that the EBV-carrying gastric carcinomas represent clonal proliferation of cells infected with EBV. The carcinoma cells had exclusively EBNA1 but not EBNA2, -3A, -3B, and -3C; leader protein; and latent membrane protein 1 because of methylation. The patients with EBV-carrying gastric carcinoma had elevated serum EBV-specific antibodies. The EBV-specific cellular immunity was not significantly reduced; however, the cytotoxic T-cell target antigens were not expressed. These findings strongly suggest a causal relation between a significant proportion of gastric carcinoma and EBV, and the virus-carrying carcinoma cells may evade immune surveillance.

Ischemia induces the expression of the platelet-derived growth factor-B chain in neurons and brain macrophages in vivo

To elucidate the role of the platelet-derived growth factor (PDGF)-B chain in the brain, we examined its expression in rat brains with focal ischemia. Focal ischemia was induced by permanent tandem occlusion of the middle cerebral and common carotid arteries in spontaneously hypertensive rats (SHRs). Northern analysis demonstrated that ischemia transiently increased mRNA expression of the PDGF-B chain, but not the PDGF-A chain, in the injured neocortex. The larger transcript (3.5 kb) of the B chain gradually increased to threefold by 16 h, whereas the smaller transcript (2.6 kb) of the B chain markedly increased sixfold by 4 h. Immunohistochemistry revealed enhanced immunoreactivity in the neurons in the infarct and in the periinfarct area from 16 h to days 4-7, with a peak at 24 h. Furthermore, the brain macrophages that accumulated in the infarct showed intense immunostaining in their perinuclear region from days 2 to 14, with a peak at days 5-6. The present study demonstrates that ischemia induces the expression of the PDGF-B chain, first in neurons and later in brain macrophages, and suggests an important role of the PDGF-B chain in the healing process of the injured brain.

Histologic observation of the ductus arteriosus in premature infants with intrauterine growth retardation

The ductus arteriosus of 19 premature infants with intrauterine growth retardation (IUGR) (study group) was compared histologically with that of 22 infants without IUGR (control group). The two groups exhibited no significant differences in gestational age, age at death, and frequency of disseminated intravascular coagulation. Maternal complications, that is, pregnancy-induced hypertension, cesarean section, and low umbilical artery oxygen tension values, were seen more frequently (p < 0.01) in the study group than in the control group. The histologic changes of ductus arteriosus, such as fragmentation, coagulation necrosis of the intimal elastic lamina, hemorrhage with necrosis, and loosening of elastic fibers and muscles in the tunica media, were seen more frequently in the study group. These findings are suggestive of both the maturation process and the prenatal hypoxic response of premature IUGR fetuses with chronic hypoxia. These changes may have produced subsequent patent ductus arteriosus, which in turn may have induced pulmonary hemorrhage.

Epstein-Barr virus and gastric remnant cancer

BACKGROUND

Carcinoma arising in the gastric remnant many years after partial gastrectomy for benign disease, referred to as gastric remnant cancer (GRC) is well known, and many causal explanations have been proposed. Elsewhere, Epstein-Barr virus (EBV) involvement has been demonstrated in a small but significant fraction of gastric cancers, and evidence has been presented suggesting that, in positive cases, EBV may have played a causal role. The present report is concerned with EBV involvement in GRC in particular.

METHODS

Paraffin sections from 48 cases of GRC were studied by EBER-1 in situ hybridization.

RESULTS

Thirteen cases (27.1%) showed uniform hybridized signals restricted to the carcinoma cells in contrast to no hybridization in the normal mucosa, intestinal metaplasia, or hyperplastic epithelium. The prevalence of EBV involvement in GRC was significantly higher (P < 0.0001) than in gastric carcinomas from 1825 nonremnant cases; the difference remained highly significant even when the comparison was restricted to nonremnant cancers arising in the cardia and middle stomach, for which EBV-positive rates were highest.

CONCLUSION

The EBV may play an important role in the carcinogenesis of GRC.

Epstein-Barr virus and gastric remnant cancer

BACKGROUND

Carcinoma arising in the gastric remnant many years after partial gastrectomy for benign disease, referred to as gastric remnant cancer (GRC) is well known, and many causal explanations have been proposed. Elsewhere, Epstein-Barr virus (EBV) involvement has been demonstrated in a small but significant fraction of gastric cancers, and evidence has been presented suggesting that, in positive cases, EBV may have played a causal role. The present report is concerned with EBV involvement in GRC in particular.

METHODS

Paraffin sections from 48 cases of GRC were studied by EBER-1 in situ hybridization.

RESULTS

Thirteen cases (27.1%) showed uniform hybridized signals restricted to the carcinoma cells in contrast to no hybridization in the normal mucosa, intestinal metaplasia, or hyperplastic epithelium. The prevalence of EBV involvement in GRC was significantly higher (P < 0.0001) than in gastric carcinomas from 1825 nonremnant cases; the difference remained highly significant even when the comparison was restricted to nonremnant cancers arising in the cardia and middle stomach, for which EBV-positive rates were highest.

CONCLUSION

The EBV may play an important role in the carcinogenesis of GRC.

Differential induction of mRNA species encoding several classes of stress proteins following focal cerebral ischemia in rats

We report here the time-dependent expression of several classes of HSP mRNAs following focal cerebral ischemia in rats. HSP70, GRP78, HSP27, HSP90 and HSP47 have been reported to possess distinct functions under normal and/or stress conditions. These different classes of HSP mRNAs were differentially induced by ischemia, as determined by Northern blot analysis. Messenger RNAs of the HSP70 family proteins were induced within 4 h after ischemia and then rapidly decreased, whereas HSP27 and HSP47 mRNAs reached a maximum level of expression at 24 h and 48 h after ischemic treatment, respectively. In situ hybridization showed that the expression of inducible HSP70 mRNA was observed predominantly in regions adjacent to the ischemic core except during the early periods of ischemia. HSP27 mRNA was expressed over a broad area of the ipsilateral cerebral neocortex except for the ischemic center 24 h after ischemia. The unique induction kinetics for each HSP mRNA species may reflect their distinct roles in the brain during various physiological stresses. We will also discuss that stress proteins may be involved in the central nervous system after ischemia in two important aspects: early protection against stress and restoration of damaged lesions in the brain at later stages after ischemia.