[Subclones of fragment DNA recombinant rpDJH2 of L. interrogans serovar lai strain 017 and it's expression of high level in E. coli]

Fragment of 1.9 kb recombinant DNA of pDJH2 was linked with vectors pT7-7 and pRSETs. Then they were transformed into E. coli JM109 (DE3) respectively. Expression of subclones was achieved in E. coli JM109 (DE3) with IPTG inducement. SDS-PAGE showed that the molecular weights of products were 68kd and 23 kd respectively. The amount of production seemed to be higher than that of the outer membrane proteins of L. interrogans serovar strain 017 in nature. Immunoblotting of pDJt and pDJrB2 (both are subclones) with the specific antiserum of anti-OMP of L. interrogans serovar lai strain 017 and the experiment of initiative immuno-protection in guinea pigs showed both protein-68 kd and 23 kd might be the antigens of immuno-protection on the outer membrane of L. interrogans serovar lai strain 017.

Progesterone is neuroprotective after transient middle cerebral artery occlusion in male rats

Progesterone (PROG) is a neurosteroid, possessing a variety of functions in the central nervous system. Exogenous PROG has been shown to reduce secondary neuronal loss in conjunction with attenuated brain edema after cerebral contusion and to reduce brain edema after focal cerebral ischemia. In the present study, we assessed the neuroprotective potential of PROG in a model of focal cerebral ischemia in the rat. Forty-eight male Wistar rats were randomly assigned to 4 groups, i.e. pretreatment with water soluble PROG, or dimethyl sulfoxide (DMSO) dissolved PROG, or DMSO as control or delayed treatment with DMSO dissolved PROG. Middle cerebral artery occlusion (MCAO) was induced by insertion of an intraluminal suture and reperfusion was performed by withdrawing the suture. Pretreatments were initiated 30 min before MCAO via intraperitoneal injection. Delayed treatment was initiated upon reperfusion following 2 h of MCAO. Infarct volume, body weight loss, and neurological deficit were measured 48 h after MCAO. Pre- and delayed treatment with DMSO dissolved PROG resulted in a 39% (P < 0.05) and 34% (P < 0.05) reduction in cerebral infarction, respectively, along with decreased body weight loss and improved neurological function as compared to control animals, whereas no statistically significant reduction in infarct volume by water soluble PROG was found. We demonstrated that administration of PROG to the male rat before or 2 hours after onset of MCAO reduces ischemic cell damage and improves physiological and neurological function 2 days after stroke. These results suggests potential therapeutic properties of PROG in the management of stroke.

Delayed intravenous administration of basic fibroblast growth factor (bFGF) reduces infarct volume in a model of focal cerebral ischemia/reperfusion in the rat

Basic fibroblast growth factor (bFGF) is a potent neurotrophic and vasoactive peptide. Previous studies have shown that intraventricularly-administered bFGF reduces the size of cerebral infarcts following focal ischemia. In the current study, we tested the effects of intravenously-administered bFGF in a model of focal ischemia/reperfusion. The right middle cerebral artery of mature male Wistar rats was occluded by intraluminal suture. After 2 h of occlusion, the suture was removed and intravenous infusion of bFGF in vehicle (45 micrograms/kg/h) or vehicle alone was begun, lasting 3 h. Animals were weighed and evaluated neurologically until sacrifice 7 days after ischemia. The volume of cerebral infarcts was then determined by H and E staining and image analysis. We found a 40% reduction in infarct volume in bFGF- vs. vehicle-treated rats (n = 11 vs. 11, P < 0.05). Reduction in infarct volume was associated with improved neurological outcome and regained body weight in bFGF-treated animals (both P < 0.05). No change in blood pressure was found during bFGF treatment. These results show that the delayed intravenous administration of bFGF reduces infarct size in this model of focal ischemia/reperfusion. The mechanisms of infarct reduction may include direct cytoprotective and/or vasoactive effects.

The box1 domain of the erythropoietin receptor specifies Janus kinase 2 activation and functions mitogenically within an interleukin 2 beta-receptor chimera

Several distinct classes of cytokine receptors engage Jak kinases as primary effectors. Among type 1 receptors, Janus-activated kinase (Jak) recruitment is mediated by membrane-proximal cytoplasmic domains, which typically contain conserved box motifs. In the erythropoietin receptor (Epo-R), two such motifs (box1 and box2) have been suggested to be essential for the activation of Jak2 and mitogenesis. Presently, an Epo-R chimera containing the extracellular and box1 domains of the Epo-R (Jak2-associated receptor) and the box2 and carboxyl-terminal domains of the interleukin 2 beta-receptor (IL2beta-R; a Jak1-associated subunit) is shown to activate Jak2. Interestingly, Jak2 also was activated in FDC-P1 cells by a control Epo-R chimera containing the complete IL2beta-R cytoplasmic domain, and mitogenesis was supported by each of these above chimeras. By comparison, in BaF3 cells expressing IL2 receptor alpha and gamma subunits, an ectopically expressed IL2beta-R chimera containing the box1 domain of the Epo-R, activated Jak2 and Jak3 and was as mitogenically active as the wild-type IL2beta-R (Jak1 and Jak3 activation). Thus, the box1 domain of the Epo-R specifies Jak2 activation and functions efficiently within a heterologous IL2 receptor complex that normally activates Jak1 and Jak3.

Antibodies against adhesion molecules reduce apoptosis after transient middle cerebral artery occlusion in rat brain

We tested the hypothesis that treatment of transient focal cerebral ischemia in rat with antibodies directed against adhesion molecules reduces apoptosis. Rats (n = 31) were subjected to 2 h of middle cerebral artery (MCA) occlusion induced by intraluminal insertion of a nylon monofilament into the internal carotid artery. Upon reperfusion, animals were treated with monoclonal antibodies directed against intercellular adhesion molecule (ICAM)-1) (n = 8) or integrin CD11b/CD18 (n = 10), or administered IgG1 as a control (n = 13). At 48 h after ischemia, animals were killed and the brains analyzed for ischemic cell damage, using hematoxylin and eosin (H/E); apoptosis, using the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) method; and inflammatory cells, using immunohistochemistry with an anti-myeloperoxidase (MPO) antibody. Data revealed a significant reduction in the volume of infarction (p < 0.01) and a decline in the absolute (p < 0.001), and normalized (to the ischemic areas, p < 0.05) numbers of apoptotic cells in both animals treated with anti-ICAM-1 and anti-CD11b antibodies compared to control animals. The numbers of immunoreactive MPO cells were also reduced in the treatment groups compared to those in the control group (p < 0.05). These data suggest that treatment with anti-adhesion molecule antibodies selectively reduce apoptosis, and that a contributing factor to the beneficial effect of antibody treatment for reducing ischemic cell damage may be a reduction in numbers of apoptotic cells.

Selection of linkers for a catalytic single-chain antibody using phage display technology

Phage display has been evaluated as a means of rapidly selecting tailored linkers for single-chain antibodies (scFvs) from protein linker libraries. Preliminary experiments with a conventional linker failed to yield a functional single-chain version of a catalytic antibody with chorismate mutase activity. A random linker library was therefore constructed in which the genes for the heavy and light chain variable domains were linked by a segment encoding an 18-amino acid polypeptide of variable composition. The scFv repertoire ( approximately 5 x 10(6) different members) was displayed on filamentous phage and subjected to affinity selection with hapten. The population of selected variants exhibited significant increases in binding activity but retained considerable sequence diversity. Screening 1054 individual variants subsequently yielded a catalytically active scFv that was produced efficiently in soluble form. Sequence analysis revealed a conserved proline in the linker two residues after the VH C terminus and an abundance of arginines and prolines at other positions as the only common features of the selected tethers. There are apparently many viable solutions to the problem of linking individual VH and VL domains, but subtle differences in sequence dramatically influence the production, stability, and recognition properties of the scFv. The success of these experiments suggests that phage display will be generally useful for identifying peptide sequences for covalently linking any two protein domains.

Administration of a competitive NMDA antagonist MDL-100,453 reduces infarct size after permanent middle cerebral artery occlusion in rat

The competitive N-methyl-D-aspartate antagonist MDL-100,453 has been shown to attenuate ischemic cell damage when administered after permanent focal cerebral ischemia. The aim of the present study was to measure the dose-response of cerebral infarcted volume to the agent administered 30 min after permanent middle cerebral artery occlusion and to test whether short-term infusion of this drug reduces ischemic cell damage. Thirty-five Sprague-Dawley rats were randomly assigned to 4 groups: low dose group, a bolus of 12.4 mg/kg MDL-100,453 followed by infusion of 31.7 mg/kg/h MDL-100,453; middle and high dose groups, bolus and infusion doses increased to 24.8 mg/kg, 63.3 mg/kg/h and 49.6 mg/kg, 126.7 mg/kg/h, respectively; and control group, saline used for bolus and infusion. Middle cerebral artery occlusion (MCAO) was induced by insertion of intraluminal suture. The infusion was accomplished by a microprocessor controlled pump connected to a jugular vein, which delivered drug or saline over a period of 9 h. Infarct volume was calculated using 2,3,5-triphenyltetrazolium chloride staining 24 h after MCAO. The infarct volumes were significantly reduced in both middle (46%) and high (52%) dose groups compared with the saline group (p < 0.05). No reduction of infarct volume was found in the low dose group. A statistically significant (p < 0.05), but poor inverse correlation existed between the average blood level of MDL-100,453 and infarct volume. We demonstrated that a short-term (9 h) intravenous administration of an appropriate dose of MDL-100,453 beginning 30 min after MCAO significantly reduces ischemic lesion volume at 24 h after onset of permanent focal cerebral ischemia.

Exploring the active site of chorismate mutase by combinatorial mutagenesis and selection: the importance of electrostatic catalysis

Chorismate mutase (EC 5.4.99.5) catalyzes the intramolecular rearrangement of chorismate to prephenate. Arg-90 in the active site of the enzyme from Bacillus subtilis is in close proximity to the substrate's ether oxygen and may contribute to efficient catalysis by stabilizing the presumed dipolar transition state that would result upon scission of the C--O bond. To test this idea, we have developed a novel complementation system for chorismate mutase activity in Escherichia coli by reengineering parts of the aromatic amino acid biosynthetic pathway. The codon for Arg-90 was randomized, alone and in combination with that for Cys-88, and active clones were selected. The results show that a positively charged residue either at position 88 (Lys) or 90 (Arg or Lys) is essential. Our data provide strong support for the hypothesis that the positive charge is required for stabilization of the transition state of the enzymatic chorismate rearrangement. The new selection system, in conjunction with combinatorial mutagenesis, renders the mechanism of the natural enzyme(s) accessible to further exploration and opens avenues for the improvement of first generation catalytic antibodies with chorismate mutase activity.

Mutation spectra of M13 vectors containing site-specific Cis-Syn, Trans-Syn-I, (6-4), and Dewar pyrimidone photoproducts of thymidylyl-(3'-->5')-thymidine in Escherichia coli under SOS conditions

The mutations spectra of cis-syn, trans-syn-I, (6-4), and Dewar pyrimidone photoproducts of the TT site of AATTAA and TATTAT in the (-) strand of a heteroduplex M13 vector were obtained in an excision and photoreversal repair deficient Escherichia coli host under SOS conditions. Oligonucleotides containing site-specific photoproducts were annealed to a complementary uracil-containing (+) strand that contained one or more unique pairs of nucleotide mismatches and used to prime (-) strand synthesis with a DNA polymerase and dNTPs. Following DNA synthesis, the reaction mixtures were incubated with T4 DNA ligase and ATP and then used to transfect SOS-induced competent CSRO6F' cells (uvrA6 and phr-1). The transfectants were plated, gridded, and probed by oligonucleotides specific for progeny of the (-) and (+) strands. Individual progeny of the photoproduct-containing (-) strands were plaque purified and sequenced by the dideoxy method. The cis-syn and trans-syn-I dimers were found not to be very mutagenic (<9%), the Dewar product more so (<33%), and the (6-4) product the most mutagenic (<73%). The mutation spectra were similar to those previously reported for the same photoproducts of the TT site of AGTTGG in the (+) strand of an M13 vector [Lawrence, C. W., et al. (1990) Mol. Gen Genet. 222, 166-168; LeClerc, J. E., et al. (1991) Proc. Natl. Acad. Sci. U.S.A. 88, 9685-9689] except that -1 deletion mutations were not observed for the trans-syn-I photoproducts, and a lower frequency of 3'-T-->C mutations was observed for the (6-4) photoproduct. Evidence that a small percentage of (+) strand repair of a double mismatch to the 3'-side of the photoproduct. Evidence that a small percentage of (+) strand repair of a double mismatch to the 3'-side was obtained from transfection experiments in which a second double mismatch was introduced opposite or flanking the photoproduct. Analysis of the minor tandem mutations induced by the (6-4) and Dewar products suggests that the SOS polymerase complex is able to elongate what amounts to double mismatches opposite these photoproducts and is consistent with the action of a highly processive polymerase that lacks proofreading ability.

Ciliary neurotrophic factor regulates nicotinic acetylcholine receptors on human neuroblastoma cells

We have investigated the effects of several neurokine/cytokine family members on the level of alpha-bungarotoxin-binding to neuronal nicotinic acetylcholine receptors. Exposure of human neuroblastoma cells (SH-SY5Y and IMR-32) to ciliary neurotrophic factor (CNTF), leukemia inhibitory factor or oncostatin-M resulted in a 30-40% decline in alpha-bungarotoxin receptors on the cells with no decrease seen in either muscarinic acetylcholine receptors or in L-type Ca2+ channels. The level of nicotinic receptor was not affected by the related cytokine, interleukin-6. Treatment of IMR-32 cells with 40 pM CNTF produced a half-maximal decrease of alpha-bungarotoxin binding which compared well with the affinity estimated from binding of 125I-CNTF (Ki approximately 40 pM) and the concentration causing c-fos activation in SH-SY5Y cells, as detected by nuclear run-on assays (60-120 pM). Previous results have indicated that the differentiating agents, phorbol esters and retinoic acid, also decrease nicotinic receptor numbers. Here the effects of CNTF, which did not induce neural differentiation, were enhanced by differentiation with 12-O-tetradecanoylphorbol 13-acetate (10 nM) and prevented by retinoic acid (10 microM). Therefore, the response of neuroblastoma cells to cytokines may be under developmental control. These cells offer a system to examine cytokine responses and signal transduction mechanisms during neural development.

Chemical modification of dehalogenase

Dehalogenase is an enzyme which catalyzes alpha-haloacid into alpha-hydroxyl acid. Chemical modification reactions of dehalogenase YL, 109, and H-2 were carried out by various reagents. The experimental results showed that the activity was not significantly altered by seryl, lysyl, and trpyl reagents but decreased by hisyl, arginyl, and carboxyl reagents. A substitute could protect the active center to chemical modification. It was indicated that hisyl, arginyl, and carboxyl (Glu or Asp) residues would be essential for the activity of dehalogenase.

Neutrophil inhibitory factor is neuroprotective after focal ischemia in rats

We tested the neuroprotective potential of neutrophil inhibitory factor (rNIF), a novel 41-kd recombinant glycoprotein derived from a hookworm, in a model of focal cerebral ischemia in the rat. Male Wistar rats were assigned to treatment with rNIF and vehicle. Middle cerebral artery occlusion (MCAO) for 2 hours was induced by insertion of an intraluminal suture. Infusion of the drug was initiated at the onset of reperfusion. Infarct volume was determined 48 hours after reperfusion. Neutrophils were measured within the ischemic tissue by myeloperoxidase (MPO) staining. Treatment with rNIF resulted in a 48% reduction in cerebral infarction compared with control animals (p < 0.01). Neutrophil accumulation in the ischemic brains of rNIF-treated rats was reduced significantly (p < 0.01) compared with control animals. The number of neutrophils within the infarcted tissue correlated positively with the size of the area of infarction (p < 0.001, r = 0.6) within representative cerebral coronal sections. We demonstrated a significant neuroprotective effect of rNIF with continuous treatment for 48 hours following 2 hours of MCAO. The neuroprotective effect was correlated with a reduced number of neutrophils within the ischemic tissue. These results demonstrate potential therapeutic properties of rNIF in the management of stroke.

Regulation of nicotinic acetylcholine receptors on human neuroblastoma cells during differentiation

Neuronal nicotinic acetylcholine receptors are expressed on a variety of cells in the nervous system where they play key roles in synaptic transmission and information transfer. Little is known, however, about the molecular mechanisms that control their expression, distribution, and function during nervous system development. We have investigated the control of expression during differentiation of one class of acetylcholine receptors that bind alpha-bungarotoxin of human neuroblastoma cells. We report that induction of differentiation of SH-SY5Y, SK-n-SH or IMR-32 cells by the phorbol ester 12-O-tetradecanoyl phorbol 13-myristate (10 nM, TPA) or by retinoic acid resulted in as much as a 70% decline in alpha-bungarotoxin receptors on the cells. The response to the phorbol ester was blocked by the protein kinase C inhibitors staurosporine and bisindolylmaleimide. The decrease in receptors induced by 10 microM retinoic acid was not affected by either agent. However, responses to lower (10 nM) concentrations of retinoic acid were blocked by staurosporine but not bisindolylmaleimide, suggesting a dual mechanism of action for retinoic acid in regulating acetylcholine receptors. It appears that acetylcholine receptors on neuroblastoma cells are regulated during differentiation by both protein kinase C-dependent and -independent mechanisms.

Postischemic treatment (2-4 h) with anti-CD11b and anti-CD18 monoclonal antibodies are neuroprotective after transient (2 h) focal cerebral ischemia in the rat

We investigated the effects of F(ab')2 fragments of anti-CD11b and anti-CD18 monoclonal antibodies on ischemic cell damage in the rat when administered upon reperfusion and at 2 h of reperfusion after transient (2 h) middle cerebral artery (MCA) occlusion. 2 h of MCA occlusion was induced by intraluminal insertion of a monofilament. The following groups of animals were investigated. Anti-CD11b groups (n = 15): an intact anti-CD11b antibody (1B6c) and an anti-CD11b F(ab')2 fragment of 1B6c were infused upon reperfusion (4 mg/kg i.v.). Anti-CD18 group (n = 8): an anti-CD18 F(ab')2 fragment of CL26 was infused upon reperfusion (2 mg/kg i.v.), and at 22 h of reperfusion (1 mg/kg i.v.). Anti-CD11b delayed group (n = 9): an anti-CD11b F(ab')2 fragment of 1B6c was infused at 2 h of reperfusion (4 mg/kg i.v.), and at 22 h after reperfusion (2 mg/kg i.v.). Control groups (n = 18): an isotype-matched control antibody (mouse IgG1) was administered: (a) upon reperfusion (n = 13), and (b) at 2 h and 22 h of reperfusion (n = 5). Rats were sacrificed at 7 days of reperfusion. In a separate population of rats subjected to 2 h of MCA occlusion (n = 9), brain myeloperoxidase (MPO) activity was measured at 46 h of reperfusion. The vehicle groups had infarct volumes of 35.21 +/- 2.82% to 41.39 +/- 2.73% of the contralateral hemisphere, respectively. Infarct volume was significantly reduced after treatment with: the intact anti-CD11b antibody upon reperfusion (19.0 +/- 6.6%) (P < 0.05), the fragments of mAbs of anti-CD11b administered upon reperfusion (19.7 +/- 2.7%) (P < 0.05), and at 2 h of reperfusion (22.2 +/- 4.8%) (P < 0.05), and anti-CD18 administered upon reperfusion (20.4 +/- 4.8%) (P < 0.05). Anti-CD11b treatment significantly (P < 0.05) inhibited the increase of MPO activity in the ischemic hemisphere. Our data demonstrate that anti-CD11b and anti-CD18 mAb fragments significantly reduce infarct volume and inhibit the increase of MPO activity in the ischemic lesion; administration of anti-CD11b mAb fragment even at 2 h of reperfusion significantly reduces infarct volume. These data support importance of the beta 2 integrin CD11b/CD18 in ischemia/reperfusion injury and indicate that the therapeutic window for intervention to reduce ischemic cell damage in this model is at least 4 h from the onset of MCA occlusion.

[Homology of the recombinant DNA of plasmid pDJH2 with the recombinant DNA probe of L. alstoni and analysis of its expression in Escherichia coli]

Dig-labeled recombinant DNA probe of L. alstoni which contains the entire structural OmpL1 gene was hybridized with the recombinant DNA of the plasmid named pDJH2 of the gene library of L. interrogans serovar lai strain 017. The result showed a high degree of homology among them; expression of recombinant DNA of pDJH2 was achieved by beta-D-galactosidase (IPTG) induction in E. coli. The molecular weight of this product is 68kd. Then they were treated with proteinase K and subjected to SDS-PAGE. The results showed it is a protein in nature. Using the specific monoclonal antibody E4B7D5 on immunoblotting and specific polyclonal antibody on dot-ELISA assay, we investigated the immune reaction and noticed that protein 68kd might be an antigen in character. E. coli which contains the recombinant plasmid pDJH2 were injected into BALB/c mice. Then the mice were challenged by leptospires of the strong virulence strain 017, but all the infected mice survived. In this paper, we first report the expression of recombinant DNA of L. interrogans serovar lai strain 017 in E. coli when injected with IPTG, and immunoprotection of BALB/c mice which were injected with the expression against the infection of L. interrogans serovar lai strain 017. pDJH2 may be the first recombinant for which the gene has been cloned and its expression product 68kd may be the immunoprotective antigens.

Anti-intercellular adhesion molecule-1 antibody reduces ischemic cell damage after transient but not permanent middle cerebral artery occlusion in the Wistar rat

BACKGROUND AND PURPOSE

Postischemic cerebral inflammation may contribute to ischemic cell damage. Intercellular adhesion molecule-1 (ICAM-1) is a glycoprotein expressed on endothelial cells that facilitates leukocyte adhesion. We investigated the effect of administration of an anti-ICAM-1 antibody (1A29) on ischemic cell damage after transient (2-hour) or permanent middle cerebral artery (MCA) occlusion in the Wistar rat.

METHODS

Groups studied were as follows: (1) transient MCA occlusion: rats were subjected to 2 hours of MCA occlusion, and after 1 hour of reperfusion they were treated with 1A29 (n = 11) or an isotype control antibody (n = 9); and (2) permanent MCA occlusion: rats were treated with 1A29 (n = 9) or an isotype control antibody (n = 7) 2 hours after onset of MCA occlusion. All animals were killed 1 week after onset of ischemia. Brain sections were stained with hematoxylin and eosin for histological evaluation.

RESULTS

Significant reductions (P < .05) in both volume (44%) of the ischemic lesion and weight loss were found in animals subjected to transient MCA occlusion and treated with 1A29 compared with vehicle-treated animals. In contrast, in animals subjected to permanent MCA occlusion the lesion and the temporal profile of body weight were not altered by 1A29 administration.

CONCLUSIONS

Ischemic cell damage is promoted by postischemic inflammatory response after 2 hours of transient MCA occlusion, and ischemic cell damage is reduced by administration of an anti-ICAM-1 antibody during reperfusion.

Induction of DNA fragmentation after 10 to 120 minutes of focal cerebral ischemia in rats

BACKGROUND AND PURPOSE

The induction of neuronal necrosis has been studied after various durations of transient middle cerebral artery (MCA) occlusion in the rat. The objective of the present study was to measure the numbers and anatomic distribution of cells exhibiting apoptotic bodies as an indication of DNA fragmentation and apoptotic cell death as a function of duration of transient MCA occlusion in the rat.

METHODS

The MCA of male Wistar rats (n = 24) was occluded for 10, 20, 30, 60, 90, and 120 minutes (n = 4 per group) with the use of an intraluminal monofilament, and reperfusion was instituted for 48 hours. DNA fragmentation was measured in paraffin sections with the use of a terminal deoxynucleotidyl-transferase (TdT)-mediated dUTP-biotin nick end-labeling (TUNEL) method. Adjacent sections were stained with hematoxylin and eosin for analysis of ischemic cell damage, and immunohistochemical double staining methods were used for cell identification. Sham-operated rats (n = 4) and normal rats not subjected to any surgical procedure (n = 4) were used as controls for apoptosis detection.

RESULTS

Within 5-microns-thick coronal sections, DNA fragmentation was present in 0 to 3 apoptotic cells in each hemisphere of normal, sham-operated rats as well as in the contralateral hemisphere of ischemic rats. After 10 to 20 minutes of MCA occlusion, apoptotic cells exhibiting DNA fragmentation (10 to 20) increased in the regions of selective neuronal necrosis in the preoptic area and in the striatum. After 30 to 60 minutes of ischemia, scattered apoptotic cells (30 to 60) exhibited DNA fragmentation and expanded into areas of selective neuronal necrosis in the cortex. After 90 to 120 minutes of occlusion, groups of apoptotic cells (70 to 200, > 95% neurons) were primarily localized to the inner boundary zone of the infarct.

CONCLUSIONS

A range of mild to severe ischemia-reperfusion stimuli induce internucleosomal DNA cleavage. The presence and anatomic location of apoptotic cells exhibiting DNA fragmentation after transient cerebral occlusion indicate that apoptosis accompanies neuronal necrosis.

The temporal profiles of ICAM-1 protein and mRNA expression after transient MCA occlusion in the rat

Leukocytes may contribute to ischemic cell damage. ICAM-1 expression on endothelial cells facilitates the migration of leukocytes into tissue. Therefore, we measured the temporal profiles of ICAM-1 mRNA and protein in rat brain after transient (1 or 2 h) of middle cerebral artery (MCA) occlusion. Male Wistar rats (n = 86) were subjected to 1 or 2 h MCA of occlusion, or 2 h of MCA occlusion followed by reperfusion for a variety of durations ranging from 1 h to 1 week. 10 additional control animals were employed. ICAM-1 mRNA and protein were measured during ischemia and reperfusion, and immunohistochemical methods were used to identify specific cell types expressing ICAM-1. ICAM-1 mRNA was detected 1 h after the onset of ischemia. mRNA maximized at 10 h of reperfusion and persisted out to 1 week of reperfusion. ICAM-1 significantly increased in microvascular endothelial cells at 2 h of reperfusion, maximized at 46 h and persisted out to 1 week of reperfusion (P < 0.05). ICAM-1 mRNA and protein are present in ischemic brain early after the onset of ischemia and reperfusion, respectively. These data provide support for the role of ICAM-1 in mediating leukocyte-endothelial adhesion after transient MCA occlusion in the rat.

Erythropoietin-induced recruitment of Shc via a receptor phosphotyrosine-independent, Jak2-associated pathway

Based on the recently implicated role of Shc as a signaling effector for type I cytokine receptors, factors which mediate the recruitment and phosphorylation of Shc in the erythropoietin receptor (EPOR) system have been studied. FDC-P1 cells stably expressing the wild type murine EPOR supported the EPO-induced association of Shc with Jak2 and its rapid tyrosine phosphorylation. However, this did not depend upon the presence of phosphotyrosine sites within the EPOR and was mediated by a mitogenically deficient receptor form (EPOR329) lacking cytoplasmic tyrosine residues. This was shown both by Western blotting of Shc and Jak2 co-immunoprecipitates and through the development of an in vitro assay for cytokine-induced Shc phosphorylation. The direct association of Shc with Jak2 also was observed and was shown to depend upon EPO-exposure and the SH2 subdomain of Shc. Together, these studies indicate that Jak2, in part, may mediate the EPO-induced phosphorylation of Shc.

Ultrastructural and light microscopic evidence of apoptosis after middle cerebral artery occlusion in the rat

Brains from eight rats subjected to transient focal ischemia (2 hours) and reperfusion (22 hours) revealed an ultrastructural appearance of apoptosis and light microscopic features of cells exhibiting DNA fragmentation. The number of cells exhibiting DNA fragmentation was significantly higher (P < 0.01) in the ipsilateral hemisphere (216 +/- 43 per section) than in the contralateral hemisphere and in normal (n = 4) and sham operated (n = 4) rats (0 to 3 positive cells per section in controls). Cells exhibiting DNA fragmentation were primarily located in the inner boundary zone to the infarct. Cells exhibiting DNA fragmentation provided morphological information of apoptosis. Apoptosis may contribute to the development of infarct after transient focal cerebral ischemia.

Temporal profile of in situ DNA fragmentation after transient middle cerebral artery occlusion in the rat

We measured the temporal profile and anatomic distribution of cells exhibiting DNA fragmentation at various durations of reperfusion after middle cerebral artery (MCA) occlusion in the rat. Focal cerebral ischemia was induced in male Wistar rats (n = 62) using an intraluminal monofilament blockade of the MCA. After 2 h of MCA occlusion, the animals were killed at different durations of reperfusion (0.5, 3, 6, 9, and 12 h and 1, 2, 4, 7, 14, 21, and 28 days, n = 4 per time point). Sham-operated rats (n = 4) and normal rats not subjected to any surgical procedure (n = 4) were used as controls. Coronal brain sections (5 microns) were analyzed, using an in situ ApopTag kit, hematoxylin and eosin, and immunohistochemical double-staining methods. Six rats subjected to 2 h of MCA occlusion were killed at 24 h for measurement of DNA fragmentation by gel electrophoresis. Our data indicate that within a coronal section, DNA fragmentation was present in zero to three cells in each hemisphere of normal and sham-operated rats as well as in the contralateral hemisphere of ischemic rats. The number of cells exhibiting DNA fragmentation increased as early as 0.5 h (8 +/- 6), peaked at 24-48 h (213 +/- 59), and persisted for 4 weeks (10 +/- 2) after onset of reperfusion (p < 0.01). Groups of cells exhibiting DNA fragmentation (> 95% neurons) were located primarily in the inner boundary zone of the infarct. With use of gel electrophoresis, purified DNA obtained from the ischemic tissue exhibited the characteristic nucleosome ladder pattern associated with apoptosis.(ABSTRACT TRUNCATED AT 250 WORDS)

[Identification of pathogenic and nonpathogenic leptospires by recombinant DNA probe]

A gene bank of L. interrogans serovar lai strain 017 was constructed with plasmid vector pUC 18. Recombinant plasmids designated pDJ 6 and pDJ 8 were screened from the gene bank. Inserted fragments of them are 1.9kb and 2.2kb respectively. Diglabelled 1.9kb inserted fragment of pDJ 6. Results showed that the probe had hybridization with pathogenic leptospires, but it did not have hybridization with nonpathogenic leptospires such as L. biflexa strain Patoc I and Leptonema illini. The probe did not have hybridization with nonhomologous DNA (e.g. human leucocyte and E. coli JM 103), either. So, the recombinant probe is a good tool for distinguishing and identifying genus, species, pathogenic leptospires and nonpathogenic leptospires.

Intestinal fatty acid binding protein: folding of fluorescein-modified proteins

The rat intestinal fatty acid binding protein is an almost all beta-sheet protein that encloses a large interior cavity into which the fatty acid ligand binds. The protein contains neither cysteine nor proline. In a previous report, six site-directed mutants were obtained, each having a single cysteine residue [Jiang, N., & Frieden, C., (1993) Biochemistry 32, 11015-11021] either in a turn or pointed into the cavity. In this report, each mutant has been unfolded in denaturant and modified with 5-iodoacetamido-fluorescein to introduce a large, bulky, and fluorescent group into the protein at a known position. In all cases, fluorescence changes indicated that the modified protein refolded, and circular dichroism measurements suggested that the refolded protein appeared to be mostly beta-sheet. Denaturation curves suggest that for two mutants intermediate structures exist at denaturant concentrations well below the midpoint of the unfolding curve. For each modified, folded protein, one- and two-dimensional 1H NMR spectra were accumulated and compared to the unmodified and wild-type proteins. While the spectra for the modified proteins showed a number of changes in chemical shifts, they were also consistent with folded proteins on the basis of the degree of chemical shift dispersion. Of the six modified mutant proteins, two appear to have the fluorescein group located in the cavity, but only one of these did not bind fatty acid. The remaining modified proteins are capable of ligand binding.(ABSTRACT TRUNCATED AT 250 WORDS)

In situ detection of DNA fragmentation after focal cerebral ischemia in mice

Brains from 5 mice subjected to focal ischemia (2 hours)--reperfusion (22 h), revealed a significant increase (P < 0.01) in cells exhibiting DNA fragmentation (100-200 per section)--ipsilateral hemisphere compared to 0-3 per section found in the contralateral hemisphere and normal (n = 5) and sham operated (n = 5) mice. Neurons were the predominant cells (90-95%) exhibiting DNA fragmentation, and were primarily located in the inner boundary zone to the infarct. Apoptosis may contribute to the development of infarct after transient focal cerebral ischemia.