Potential etiologic role of PAF in two major septic complications; disseminated intravascular coagulation and multiple organ failure

A possible role of platelet-activating factor (PAF) in the occurrence of the two septic complications, i.e., disseminated intravascular coagulation (DIC) and multiple organ failure (MOF) was investigated, employing a rabbit model and a novel PAF antagonist E5880. By an instillation of fecal suspension into the common bile duct of the rabbit, manifestations of DIC and MOF were observed with high reproducibility by 9 hours after the septic insult. E5880 was intravenously administered to 12 rabbits for 1 hour after the septic insult at dose of 1 mg/kg (n = 6) or 3mg/kg (n = 6). All the rabbits were subjected to observation of vital signs and serial determination of laboratory tests for 9 hours and then lung, liver and kidney were removed for histological examination. Blood endotoxin level increased significantly by 9 hours after the septic insult. Although administration of E5880 did not affect the endotoxemia, the antagonist attenuated in a dose related manner laboratory manifestation of DIC such as thrombocytopenia and prolonged prothrombin time as well as that of MOF such as increase in serum bilirubin and creatinine level. The beneficial effect of E5880 on MOF was also confirmed by the histological evaluation. These observations indicated that PAF is deeply involved in the occurrence of DIC and MOF due to sepsis and E5880 may be one of the modalities to treat or prevent these two major septic complications.

A new method of purification and sensitive bioassay of platelet-activating factor (PAF) in human whole blood

There is no satisfactory assay procedure of PAF in human whole blood in terms of sensitivity, reproducibility and simplicity. This is due to coexisting lipids from plasma and cellular membranes which inhibit measurement of PAF in various assay procedures, including bioassay. In the present study, an attempt was made to eliminate these interfering lipid inhibitors from blood samples. Lipids in human whole blood were extracted according to the method of Bligh & Dyer and the organic layer was dried under a stream of nitrogen. Then, the dried organic layer was dissolved in diethyl-ether and the solution was kept at -20 degrees C which was then centrifuged. The resulting supernatant was then applied to an anion-exchange column and the PAF fraction was obtained by step-wise gradient elution. The fraction was further purified by normal phase HPLC. Then PAF in the final sample was determined by sensitive bioassay using rabbit platelets containing fibrinogen and epinephrine. The recovery rate of PAF throughout this procedure was constant and satisfactory (37.4 +/- 9.7%), which was confirmed using [3H]-PAF. The lower limit of the present assay was estimated to be 5pg in 1 ml of blood and it was sensitive enough to detect PAF in blood samples from healthy volunteers and patients with sepsis or liver cirrhosis. Furthermore, attempts were made to compare the sensitivity and the recovery of our method with these of a commercially available radioimmunoassay (RIA) kit for PAF. However, it was not possible to detect any amount of authentic PAF added to whole blood.

Pharmacokinetic study of loprinone hydrochloride, a new cardiotonic agent, in beagle dogs

Pharmacokinetic parameters and bioavailability of a new cardiotonic agent, loprinone hydrochloride, in beagle dogs were determined by measuring plasma levels of loprinone after intravenous bolus and oral administration. The plasma half-life after intravenous administration of loprinone varied among individuals over the range 2.65-15.40 h. The bioavailability after oral administration of loprinone as a solution was 37.1%. Effects of enterohepatic circulation on the time-course of plasma levels after intravenous administration of the drug were also studied in bile-duct-cannulated beagle dogs. The amounts of loprinone and its glucuronide excreted in bile during 8 h after administration were 25.4 and 8.6% of the dose, respectively, indicating the possibility of enterohepatic circulation. The plasma half-life in bile-duct-cannulated beagle dogs was 1.98 h. These results indicate that the variation in the half-life in beagle dogs resulted from enterohepatic circulation and that the true half-life is about 2 h. The relative bioavailability after oral administration of the drug as a powder in a capsule compared with a solution was 95.7%. In addition, the amounts of loprinone and its glucuronide excreted in bile, and the AUC of plasma level after infusion for 30 min into the portal vein in bile-duct-cannulated beagle dogs were similar to those after bolus intravenous administration. These results show that the low bioavailability reflects incomplete absorption.

Epstein-Barr virus in gastric carcinoma

Epstein-Barr virus (EBV) is known to be related to lymphoid tumors and some types of epithelial tumors, including lymphoepithelioma-like gastric carcinoma with marked lymphocytic stroma. In this study, prevalence of EBV involvement in gastric cancer, and characteristics of tumors with such involvement, were investigated by EBV-encoded RNA 1 in situ hybridization applied to paraffin sections, including the tumor and adjacent gastric tissue, from 999 gastric carcinomas observed in 970 consecutive cases from a large Japanese hospital. EBV involvement occurred in 6.9 percent of lesions, a significantly lower proportion than has been observed in a North American series. Involvement was significantly more frequent among males, in tumors in the upper part of the stomach, and in adenocarcinomas of the moderately differentiated tubular and poorly differentiated solid or medullary types. Almost all carcinomas with marked lymphoid stroma were EBV-positive. Positive lesions were characterized by the presence of uniform hybridized signals in almost all carcinoma cells and by their absence from adjacent non-neoplastic tissue.

Epstein-Barr virus in adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is a well-known human T-cell lymphotropic virus type-1-related disease. We studied Epstein-Barr virus (EBV) in the tumor cells of ATLL, to investigate the etiological significance of double infection with these viruses. We used polymerase chain reaction and EBV-encoded small RNA-1 in situ hybridization to investigate the presence of EBV and immunohistochemistry to detect EBV-related oncoproteins, such as EBV-determined nuclear antigen-2 and latent membrane protein. Polymerase chain reaction performed on DNA of frozen specimens from 96 cases of ATLL revealed that the tumor tissue from 21 cases contained EBV DNA. EBV-encoded small RNA-1 in situ hybridization performed on the paraffin sections of the polymerase chain reaction-positive cases indicated EBV in the nuclei of ATLL tumor cells in 16 cases, nine of which were in the pleomorphic nuclei. Latent membrane protein was also detected in the cytoplasm of ATLL tumor cells in 15 cases, and EBV nuclear antigen-2 was observed in the nuclei of ATLL tumor cells in 11 cases. We conclude that EBV was present within tumor cells in about 17% of cases with ATLL and expressed EBV oncoprotein in the tumor cells. It is hypothesized that EBV and human T-cell lymphotropic virus-1 may infect the same T cells in early life and may play a role in the oncogenesis of ATLL.

Epstein-Barr virus related gastric cancer in Japan: a molecular patho-epidemiological study

Epstein-Barr virus (EBV) involvement in gastric carcinoma has been demonstrated by the presence of EBV genomes and EBV-encoded small RNA (EBER) in the carcinoma cells, monoclonal proliferation of EBV-infected carcinoma cells and elevated antibody titers. The present study was conducted to investigate the prevalence of EBV involvement among gastric carcinomas observed in nine Japanese cities with varying gastric cancer rates. In situ hybridization of EBER-1 was applied to paraffin sections from 1848 carcinomas observed in 1795 cases and EBV involvement was detected based on uniform hybridization in carcinoma cells. Epstein-Barr virus was detected in 6.6% of lesions and 6.7% of cases. The rate of EBV involvement did not vary significantly for each city and there was no correlation with underlying gastric cancer mortality rates. Thus, geographic variation of gastric cancer rates within Japan cannot be explained in terms of EBV involvement. Epstein-Barr virus-related gastric carcinoma is one of the most common EBV-related tumors in Japan. The involvement of EBV was significantly more frequent among males than among females, mainly for cancers occurring in the upper and middle part of the stomach, and exhibited more variation by cell type among males. These observations suggest that other factors yet to be discovered may modulate the causal role of EBV in gastric carcinogenesis.

Purification and characterization of endogenous protein activator of human platelet proteasome

An endogenous activator of 20S proteasome was purified from human platelets and its effect on three peptidase activities of proteasome was studied. This activator had a molecular weight of 170 kDa, and was composed of 32 kDa polypeptides as determined by SDS-PAGE. It was highly labile upon heat treatment (56 degrees C, 20 s) and proteinase (pronase CB) digestion. Suc-LLVY-MCA degrading activity of the platelet proteasome showed positive cooperativity between two or more catalytic sites because the coefficient was 1.54 when analyzed by use of the Hill plot. The endogenous activator increased Vmax and caused a loss of cooperativity. The plot of reaction velocity as a function of activator concentration yielded a saturation curve, implying the binding of the activator to proteasome. Boc-LTR-MCA degrading activity followed Michaelis-Menten kinetics. The activator enhanced the activity by increasing Vmax and decreasing Km. In contrast, CBz-LLE-2NA degrading activity could not be analyzed according to any kinetic scheme reported so far. The activator stimulated this activity at lower substrate concentrations (below 200 microM), while it inhibited the activity at higher substrate concentrations (400-800 microM). It is concluded from these findings that the endogenous protein activator may regulate the intracellular proteasome activity by functioning as a positive allosteric effector.

Calyculin A inhibits the exposure of fibrinogen receptor in thrombin-stimulated platelets

Calyculin A (CLA) and okadaic acid (OA), specific and potent inhibitors of protein phosphatase 1/2A, inhibit platelet aggregation. However, their inhibitory mechanisms remain unknown. We investigated the effects of CLA on the exposure of fibrinogen receptor in thrombin-stimulated platelets, using flow cytometry with a monoclonal antibody against the fibrinogen receptor of activated glycoprotein(Gp)IIb/IIIa complex (PAC-1). CLA inhibited the exposure of fibrinogen receptor in a dose related manner when added either before or 3 min after thrombin stimulation. In contrast, CLA had no significant effect when the expression of GpIIb/IIIa complex was examined in resting platelets, using a monoclonal antibody recognizing non-activated GpIIb/IIIa complex (NNKY1-32). These results suggest that protein phosphatase 1/2A may be directly involved in the exposure of platelet fibrinogen receptor.

Ischemic tolerance due to the induction of HSP70 in a rat ischemic recirculation model

Various studies have demonstrated an increase in heat shock protein 70 (HSP70) synthesis in the brain following transiently induced ischemia, suggesting a protective role for HSP70 against ischemic insult. In this study, we determined the time course of HSP70 mRNA and protein induction in rat hippocampus following ischemia using Pulsinelli's four-vessel occlusion model, and suggested a protective role for HSP70 induction in limiting ischemic damage to neurons and delayed neuronal death. In Northern blotting analysis using human HSP70 DNA as a probe, the accumulation of HSP70 mRNA after 5 min ischemia became evident at 4 h, and continued until 16 h, while after 30 min ischemia, HSP70 mRNA appeared at 2 h, and continued above control level until 24 h after treatment. In immunoblot analysis using anti-HSP70 antibody, induction of HSP70 protein appeared 24 h and reached a maximum 48 h after 5 min ischemia. In immunohistochemical analysis using anti-HSP70 antibody, staining was not detected in CA1 neurons until 16 h after 5 min ischemia, but staining in CA1 gradually increased 1 day after ischemia and reached a maximum level 2 days after ischemia. Similar time profiles in the staining pattern of HSP70 protein were observed in CA3 and CA4 neuronal cells following 30 min ischemia. When rats pretreated with 5 min ischemia (non-lethal for CA1 pyramidal neurons) were exposed to a 30 min, lethal period of ischemia, 2 days after pretreatment, considerable staining of HSP70 was observed. Pretreated rats had much less neuronal damage in the CA1 sector than did rats subjected to lethal, 30 min ischemia alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistochemical detection of Pneumocystis carinii in transbronchial lung biopsy specimens: antigen difference between human and rat Pneumocystis carinii

Transbronchial lung biopsy specimens, from three patients with non-AIDS-related Pneumocystis carinii pneumonia (PCP) and rat lung tissue in which PCP was induced by the administration of dexamethasone, were studied to determine the diagnostic usefulness of an immunohistochemical method using commercially available anti-Pneumocystis monoclonal antibody, 3F6, on formalin-fixed, paraffin-embedded tissue. PC was consistently stained a bright red color and unambiguously identified in all three human lung specimens, but not stained in lung tissues at autopsy from patients with various fungal pneumonias. In contrast, PC was weakly stained in PCP-induced rat lungs. The present study indicates human PC and rat PC to be antigenically different in terms of the existence of the 82 kilo-dalton (kD) antigen against which 3F6 is directed.

The Tokyo Metropolitan Home Vision Screening Program for amblyopia in 3-year-old children

In August 1989, the Tokyo Metropolitan Government officially began a vision screening program for children aged 3 years 1 month. A 1988 pilot study of 1,303 children this age disclosed five cases (0.38%) of amblyopia. The home vision test, which uses picture cards of familiar figures, proved to be an efficient and inexpensive method of screening when incorporated into the existing health-check program for 3-year-old children. In the initial eight months of the program, 21,906 children were screened. Of these, 419 children (1.9%) were referred to an ophthalmologist for follow-up, and amblyopia was detected in 41 children (0.19%).

A novel CoA-independent transacetylase produces the ethanolamine plasmalogen and acyl analogs of platelet-activating factor (PAF) with PAF as the acetate donor in HL-60 cells

In this study, we demonstrate the presence of a unique membrane-associated transacetylase that transfers the acetate group from platelet-activating factor (PAF) to lysoplasmalogen (in the presence of EDTA and sodium acetate) with the formation of 1-alk-1-enyl-2-acetyl-sn-glycero-3-phosphoethanolamine (alk-1-enylacetyl-GPE). The identity of alk-1-enylacetyl-GPE was confirmed by acid hydrolysis, phospholipases A2 or C treatment and derivatization by fluorodinitrobenzene. The transacetylase has no requirement for Ca2+, Mg2+, or CoA and a broad pH optimum (7.0-8.0) with Km values of 12.0 microM for PAF and 106.4 microM for lysoplasmalogens. The enzyme activity from the isolated membrane fraction is not changed when whole cells are supplemented with 20:4, induced to differentiate into granulocytes, or treated with ionophore A23187. Radyllyso-sn-glycero-3-phosphocholine (GPC), radyllyso-GPE, acyllyso-sn-glycero-3-phosphoserine (GPS), acyllyso-sn-glycero-3-phosphoinositol (GPI), alkyllyso-sn-glycero-3-phosphate (GP), acyllyso-GP, or cis-9-octadecen-1-ol can also serve as acetate acceptors, whereas alkylglycerol, acylglycerol, or cholesterol are inactive. Differences in substrate acceptor specificity, sensitivity toward phenylmethylsulfonyl fluoride, and response to temperature suggest that the CoA-independent transacetylase and the CoA-independent transacylase that transfers long-chain acyl moieties are two separate enzymes. With intact differentiated HL-60 cells, [3H]acetate from [3H]PAF can be incorporated into alk-1-enylacetyl-GPE in the presence of ionophore A23187, but not in its absence. Moreover, phospholipase A2 inhibitors (p-bromophenacyl bromide and mepacrine) block the transacetylation process in whole cell system. These results indicate the production of alk-1-enyllyso-GPE is a rate-limiting factor for the subsequent transacetylation step during cell activation. We conclude that the transacetylase may participate in the biosynthesis of ethanolamine plasmalogen and acyl analogs of PAF, in vivo, fine-tuning of PAF biological responses, and cross-talk between de novo and remodeling pathways of PAF biosynthesis.

Alpha-elastin coacervate as a protein liquid membrane: effect of pH on transmembrane potential responses

A protein liquid membrane composed of coacervated alpha-elastin, a chemical fragmentation product of the biological elastic fiber protein, functioned as an amphoteric liquid ion-exchange membrane. Ionic permselectivities of the alpha-elastin coacervate membrane to a series of metal chlorides were investigated for the concentration-cell systems by the ordinary electrochemical measurements. Effects of pH on the transmembrane potential responses for NaCl, CaCl2, and MgCl2 systems were examined. Only in the Ca(2+)-containing system did potential responses stay at constant levels against the pH changes, whereas in the other systems, increasing pH caused potential changes, indicating an improvement of cationic permselectivity across the alpha-elastin coacervate membrane. It was suggested that the characteristic Ca2+ transport mechanisms across the alpha-elastin coacervate membrane are related in some way to the polypeptide backbone interactions specific and selective to Ca2+ ions.

[Intensive induction chemotherapy of adult acute myelogenous leukemia by continuing daunorubicin, behenoyl-cytosine arabinoside, 6-mercaptopurine and prednisolone until marrow aplasia]

Intensive induction chemotherapy was applied to 25 patients with acute myelogenous leukemia by continuing drugs (daunorubicin, behenoyl-cytosine arabinoside, 6-mercaptopurine and prednisolone) until the achievement of severe bone marrow aplasia (leukemic cells less than 1,000/microliters). Complete remission (CR) was achieved in 18 (72%). Numbers of partial remission and an early death were 5 (20%) and 2 (8%), respectively. Although median nadirs of white blood cells (WBC) and platelet counts (Pl) (205/microliters and 8,200/microliters, respectively) were remarkably low, recovery of WBC (over 1,000/microliters) and Pl (over 50,000/microliters) were achieved in 23.8 and 24.5 days, after an initiation of the chemotherapy. Sepsis was a most frequently observed complication during induction stage and a duration of fever was 2-48 days (median 15). Median duration of CR was 22.9 months. Unexpectedly, 11 of 17 CR (except one with bone marrow transplanted) relapsed after 4.2-41.4 months (median; 9.4), but 6 (35.3%) still remain in first CR for 30.5-72.9 months (median; 51.4). A long-term survival might be obtained by intensifying induction chemotherapy in about one fourth of patients, but the intensification or application of non-cross resistant anti-leukemic agents in post-remission therapy may be required to avoid relapses even if induction is intensified.

Acute megakaryoblastic leukemia: establishment of a new cell line (MKPL-1) in vitro and in vivo

A megakaryoblastic cell line (MKPL-1) was newly established from the bone marrow of an adult patient with acute megakaryoblastic leukemia. This cell line grew in single cell suspension with a doubling time of 30 h and consisted of large primitive blasts with persistent development of giant cells carrying multilobed nuclei. MKPL-1 cells were positive for platelet GPIIb/IIIa (CD41) and GPIIIa (CD61), and expressed OKM5 (CD36), MY7 (CD13), and MY9 (CD33) antigens in the absence of erythroid and lymphoid markers. The cytochemical and morphologic characteristics of MKPL-1 were also consistent with those of megakaryoblasts. The cells did not, however, express ultrastructural platelet peroxidase which is considered to be another marker of the megakaryocytic lineage. Cytogenetic analysis of MKPL-1 revealed a model chromosome number of 92 with abnormal chromosomes including those found in the patient's bone marrow cells. Furthermore, MKPL-1 cells were serially transplanted into nude mice for nine passages with production of lethal tumors and leukemic manifestation. Thus, our megakaryoblastic cell line which can be maintained both in vitro and in vivo would be useful for further studies of the biology of megakaryopoiesis and megakaryoblastic leukemia.

Human pulmonary hypoplasia. Statistical, morphological, morphometric, and biochemical study

Human pulmonary hypoplasia was studied statistically and pathologically in a large series of autopsy cases. Multiple logistic regression analysis indicated five independent risk factors from 10 statistically significant factors for pulmonary hypoplasia: (1) hydrops fetalis; (2) renal anomalies; (3) hernia, including diaphragmatic hernia and omphalocele; (4) skeletal anomalies; and (5) abnormalities of amniotic fluid, such as oligohydramnios and polyhydramnios. The characteristics of pulmonary hypoplasia for each factor were defined by morphological, morphometric, and biochemical methods. All bronchiolar branching, acinar complexity, and acinar maturation were retarded in hypoplastic lungs with hydrops fetalis, renal anomalies, affected side of diaphragmatic hernia, omphalocele, and skeletal anomalies. Only acinar complexity and maturation were impaired in the lung with oligohydramnios due to prolonged rupture of membranes. The pathogenesis of pulmonary hypoplasias should be considered differently with each associated anomaly and time of impairment. While impairment in early gestational stage before 16 weeks' gestation results in both reduced bronchiolar branching and retarded acinar development, that, at late stage, influences only acinar development.

Neurochemical analysis of focal ischemia in rats

BACKGROUND AND PURPOSE

Increases in uric acid follow experimental stroke, which may be related to free radical formation by xanthine oxidase. The present study examined the time course of changes in xanthine and uric acid and their relationship to changes in the free radical scavengers glutathione, cysteine, and ascorbic acid.

METHODS

Focal ischemia was induced by occluding the middle cerebral artery, followed by transient occlusion of the common carotid arteries for 60 minutes. At varying time points, animals were sacrificed, and ischemic cortex was dissected. Neurochemical measurements were made by high-performance liquid chromatography with 16-sensor electrochemical detection.

RESULTS

Marked increases in uric acid were seen at all time points, with a maximal increase at 1 day and a persistent increase lasting up to 21 days. There were smaller reciprocal decreases in xanthine. Glutathione, cysteine, and ascorbic acid showed significant decreases, consistent with the generation of free radicals. Reductions in levels of cysteine and glutathione were significantly correlated with increases in uric acid levels.

CONCLUSIONS

These findings confirm marked alterations in purine metabolism following focal ischemia and suggest that xanthine oxidase contributes to the generation of free radicals.

Association of Epstein-Barr virus with undifferentiated gastric carcinomas with intense lymphoid infiltration. Lymphoepithelioma-like carcinoma

Some undifferentiated gastric carcinomas with intense lymphoid infiltration have a striking resemblance to nasopharyngeal lymphoepithelioma. The authors identified eight such cases (seven patients from Japan and one from the United States) of undifferentiated gastric carcinoma (lymphoepithelioma-like carcinoma [LELC]) and examined them for Epstein-Barr (EBV) viral sequences using polymerase chain reaction (PCR) and in situ hybridization (ISH) techniques. EBV was detected in seven of the eight cases by PCR, including a lymph-node metastasis. ISH that was performed in six of these cases showed EBV genomes to be uniformly present in the carcinoma cells and not present in the reactive lymphoid infiltrate or normal gastric mucosa. PCR of a polymorphic EBV locus (lymphocyte-determined membrane antigen) showed that a single genotype was present in each gastric LELC, consistent with a clonal process. These findings suggest that some undifferentiated gastric carcinomas are EBV-related and that focal EBV infection occurs before transformation.

Expression of three major protein kinase C isozymes in various types of human leukemic cells

We examined the levels of protein kinase C (PKC) activity and the expressions of its three major isozymes, designated types I (gamma), II (beta), and III (alpha), in the cytosol and particulate fractions of cells from patients with acute myelogenous leukemia (AML), acute lymphocytic leukemia (ALL), and chronic lymphocytic leukemia (CLL), in an attempt to elucidate the cell type- or lineage-specific expression of these isozymes. The levels of PKC activities in the cytosol and particulate fractions from AML cells were higher than those from ALL or CLL cells. The average PKC activities of AML cells, ALL cells, and CLL cells were 18.7, 12.2, and 11.3 pmol/min/10(8) cells, respectively, in the cytosol fractions and 4.4, 3.1, and 2.6 pmol/min/10(8) cells, respectively, in their particulate fractions. M1 cells (French-American-British classification) and AML cells with T-lymphocyte-associated surface antigens, such as CD2 and CD7, had significantly lower PKC activities among AML cells. Immunoblot analyses using monoclonal antibodies against each isozyme revealed that all three isozymes were broadly distributed on leukemic cells with considerable variability in the level of expression. All lymphoid leukemic cells expressed PKC-gamma in the cytosol fractions, albeit a minor component; however, this type was observed in cells from only half the number of AML patients. Those AML cells with cytosolic PKC-gamma usually expressed lymphoid surface antigens, such as CD2, CD7, and CD19. On the other hand, cytosolic PKC-beta and PKC-alpha were commonly observed in all types of leukemic cells. AML cells expressed these two types at almost equal levels, but in lymphoid cells, expressions of PKC-beta were usually more abundant than those of PKC-alpha. These data suggest that AML cells with lymphoid antigens might have a lower PKC activity but more predominant expression of cytosolic PKC-gamma than the usual AML cells.

Focal ischemia in rats causes time-dependent expression of c-fos protein immunoreactivity in widespread regions of ipsilateral cortex

c-Fos protein expression was examined in brain by immunohistochemistry following permanent middle cerebral artery (MCA) occlusion above the rhinal fissure and ipsilateral common carotid artery (CCA) occlusion in Long-Evans rats. In sham-operated animals, c-fos protein-like immunoreactivity (CFPLI) was confined to neuronal nuclei of the hypothalamus and was not present in other regions including cerebral cortex. In the core territory of the MCA, CFPLI was not detected when examined at 15 and 30 min, 1, 4 and 8 h and 1, 2, 4 and 7 days after occlusion. Focal ischemia induced two temporal and spatial patterns of CFPLI. At 1 h, c-fos protein was expressed in the nuclei of many neurons in layers II-V of the ipsilateral cortex both immediately adjacent to and remote from the ischemic territory. Within regions outside the MCA territory (e.g. cingulate gyrus and piriform cortices), CFPLI in these neurons peaked at 2-4 h and was undetectable after 2 days. Neurons in the zone immediately surrounding the ischemic core within MCA territory also expressed CFPLI, but in contrast, continued to express c-fos up to 4 days after ischemia. Immunoreactivity surrounding the ischemic core was found in neuronal nuclei predominantly, although from 1 to 4 days, CFPLI was found in perikarya and dendrites as well. MK-801 (3 mg/kg, i.p., 30 min prior to occlusion) completely blocked the early c-fos protein induction in all regions but expression within neurons surrounding the ischemic core was present 1 day after a single injection.(ABSTRACT TRUNCATED AT 250 WORDS)