Anti-ICAM-1 antibody reduces ischemic cell damage after transient middle cerebral artery occlusion in the rat

Intercellular adhesion molecule-1 (ICAM-1) is a glycoprotein expressed on endothelial cells that facilitates leukocyte adhesion. To test the hypothesis that reduction of leukocytes in an ischemic lesion reduces ischemic brain damage, we measured the effect of administration of an anti-ICAM-1 monoclonal antibody on ischemic brain damage after transient middle cerebral artery occlusion in the rat. ICAM-1 expression increased in the ischemic lesion, and the lesion volume was significantly reduced by 41% in the anti-ICAM-1 antibody group compared with the control group (p < 0.05). Numbers of polymorphonuclear leukocytes (PMNs) were significantly reduced in the cortices of the anti-ICAM-1 antibody group compared with the control animals (p < 0.05). Our data indicate that administration of anti-ICAM-1 antibody results in a significant reduction of ischemic brain damage concomitant with a reduction of PMNs in the lesion after transient focal cerebral ischemia in the rat.

The extended box 2 subdomain of erythropoietin receptor is nonessential for Jak2 activation yet critical for efficient mitogenesis in FDC-ER cells

The development of erythroid progenitor cells depends upon exposure to the glycoprotein hormone, erythropoietin (EPO). Binding of EPO to its transmembrane receptor leads to the rapid tyrosine phosphorylation of several cellular targets including Shc, Raf-1, Gap120, the cloned EPO receptor (EPOR), pp100/97, and a M(r) 130,000 EPO-activated receptor-associated Janus protein tyrosine kinase, Jak2. A membrane-proximal cytosolic region of the EPOR recently has been shown to be essential for the activation of Jak2 and sufficient for EPO-induced mitogenesis. This cytosolic region includes 8-12 amino acid box 1 and box 2 subdomains, which are conserved in certain class I receptors as well as a more distal 10-40 amino acid subdomain (extended box 2 subdomain, ExBx2), which likewise is implicated in mitogenic signaling. Through the expression of EPOR carboxyl-terminal truncation mutants in FDC-P1 cells, we presently show that an EPOR form truncated within the ExBx2 domain efficiently activates Jak2, yet is deficient in mitogenesis. Efficient expression of this mutant receptor at the cell surface and its ability to activate Jak2 indicate that poor mitogenic activity does not result from aberrant transport or folding. Rather, failure of this mutant to support proliferation above nominal rates underlines an apparent role for the EPOR ExBx2 subdomain in the activation of a distinct primary mitogenic effector.

Postischemic administration of an anti-Mac-1 antibody reduces ischemic cell damage after transient middle cerebral artery occlusion in rats

BACKGROUND AND PURPOSE

Postischemic cerebral inflammation may contribute to ischemic cell damage. The CD11b/18 (Mac-1) integrin mediates stimulated neutrophil binding to endothelia. We therefore investigated the effect of administration of an anti-Mac-1 monoclonal antibody on cerebral ischemic cell damage in the rat.

METHODS

Rats (n = 10) were subjected to 2 hours of middle cerebral artery occlusion; the anti-Mac-1 antibody was administered at a dose of 2 mg/kg i.v. at 1 hour of reperfusion and 1 mg/kg i.v. at 22 hours of reperfusion or an isotype-matched control antibody (n = 10) was administered using the same experimental protocol. Rats were killed at 46 hours of reperfusion, and brain sections were stained with hematoxylin and eosin for histological evaluation. In a separate population of rats given either vehicle (n = 8) or anti-Mac-1 antibodies (n = 9), intraparenchymal neutrophils were measured by means of a myeloperoxidase assay.

RESULTS

The lesion volume was significantly smaller (28%) in the anti-Mac-1 antibody group compared with the vehicle control group (P < .01). Numbers of intraparenchymal polymorphonuclear cells were significantly reduced (P < .05) in the cortex of the anti-Mac-1 antibody group compared with the vehicle control group.

CONCLUSIONS

Our data demonstrate that administration of anti-Mac-1 antibody 1 hour after onset of reperfusion results in significant reductions of ischemic cell damage and intraparenchymal neutrophils after transient (2-hour) focal cerebral ischemia in the rat.

Association of the p85 regulatory subunit of phosphatidylinositol 3-kinase with an essential erythropoietin receptor subdomain

Using an active, HAI epitope-tagged form of the murine erythropoietin (EPO) receptor and via direct coimmunoprecipitation, the p85 regulatory subunit of phosphatidyl inositol-3 kinase (p85/PI3-K) is shown to associate with the EPO receptor in transfected FDC-P1 cell lines. Coimmunoprecipitation of p85 with epitope-tagged EPO receptors was observed initially in FDC-HER cells labeled metabolically with [32P]orthophosphate, and association of these factors was confirmed by Western analyses of receptor immunoprecipitates using p85 antiserum. Interestingly, this association occurred in the absence of ligand, and exposure of FDC-HER cells to EPO did not detectably affect levels of receptor-associated p85 or overall levels of p85 phosphorylation. However, EPO was observed to stimulated the rapid formation of phosphatidylinositol 32P-phosphate in FDC-HER and FDC-ER cells. Through baculovirus-mediated expression of epitope-tagged EPO receptor forms in SF9 cells, domains for p85 association were mapped. Analyses of receptor forms with cytosolic truncations and deletions delineated a candidate subdomain for p85 binding to an essential extended box-2 region (P329-E374; including a putative motif for SH2 binding, Y343LVL). These findings extend a mechanistic alignment between the EPO receptor and protein tyrosine kinase-encoding receptors that likewise activate PI3-K, and expand the importance of further defining pathways to PI3-K activation.

[Indoles. 10. Synthesis, structure and D2-affinity of beta-carboline analogs of flutroline]

10 is a beta-carboline analogue of the neuroleptic flutroline2a,b) with significant lower affinity at the dopamine D2 binding site. Various synthetic routes to 10 and the solid state structure of 8 are described, structure activity relations, in particular the importance of the "S-shape" and the rigid dopamine conformation are discussed.

Intestinal fatty acid binding protein: characterization of mutant proteins containing inserted cysteine residues

Site-directed mutagenesis was used to introduce cysteine residues into the rat intestinal fatty acid binding protein, an almost all beta-sheet protein that in the wild-type contains neither cysteine nor proline residues. Six mutants (I23C, S53C, V60C, L72C, L89C, and A104C) with a single cysteine residue substituted for a hydrophobic residue were characterized by their stability toward denaturants at pH 7.2 and 9.6, by their fluorescent properties, and by their reactivity toward the sulfhydryl modifying reagents 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) and 4,4'-dipyridyl disulfide (4-PDS). In terms of protein stability, the substitutions were reasonably conservative with only two (V60C and L89C) being somewhat less stable than the wild-type. The mutant proteins differed considerably, however, in their reactivity toward the modifying reagents. One residue, Cys89, located in a hydrophobic core near a turn between two beta-strands, was unreactive, while two residues, Cys60 and Cys104, located in the middle of beta-strands in the cavity into which fatty acid binds, reacted only very slowly and were further protected by oleate. Cys53, located near a turn and partially buried, appeared to have an unusually low pK value. Two residues, Cys23 and Cys72, reacted more rapidly in the native protein than in the unfolded protein. Both residues are located near the portal for the fatty acid binding, and one, Cys72, was strongly protected from modification by the presence of oleate. Examination of the crystal structure indicates that Cys72 is not easily solvent-accessible. We conclude that this high reactivity for this residue may be a consequence of rapid conformational flexibility in this region of the structure.

[Indoles. 9. 4-Arylated tetrahydro-beta-carbolines--synthesis and first pharmacologic data]

Two different routes lead to the 4-arylated tetrahydro-beta-carbolines 5, 11, 12. One includes Pictet-Spengler cyclization of tryptamines 9, the other follows our "lactone-route", starting with 1 via 2-4. In a first pharmacological screening some target compounds show significant affinity at the 5-HT2-receptor but no or only low affinity to other binding sites.

In vivo evidence that UV-induced C-->T mutations at dipyrimidine sites could result from the replicative bypass of cis-syn cyclobutane dimers or their deamination products

The major mutations induced by UV light are C-->T transitions at dipyrimidines and arise from the incorporation of A opposite the C of dipyrimidine photoproducts. The incorporation of A has most often been explained by the known preference of a polymerase to do so opposite noninstructional DNA damage such as an abasic site (A rule). There are also mechanisms that suppose, however, that cis-syn dipyrimidine photodimers are instructional. In one such mechanism (tautomer bypass), the incorporation of A is directed by the tautomer of a C of a dimer that is equivalent in base-pairing properties to U [Person et al. (1974) Genetics 78, 1035-1049]. In another mechanism (deamination bypass), the incorporation of A is directed by a U of a dimer that results from the deamination of the C of a dimer [Taylor & O'Day (1990) Biochemistry 29, 1624-1632]. The viability of these mechanisms was tested by obtaining the mutation spectrum of a TU dimer in Escherichia coli by application of a standard method for site-directed mutagenesis. To this end, a 41-mer containing a site-specific TU dimer was constructed via ligation of a dimer-containing decamer that was produced by triplet-sensitized irradiation and used to prime DNA synthesis on a uracil-containing (+) strand of an M13 clone containing a double mismatch opposite the dimer. The reaction mixture was used to transfect a uracil glycosylase proficient, photoproduct repair deficient E. coli host, and all progeny phage weakly hybridizing to the parental (+) or (-) strands were sequenced. Under non-SOS conditions the TU dimer almost completely blocked replication, while under SOS conditions it directed the incorporation of two As with much higher specificity (96%) than would an abasic site. The implications of these results to the mechanism of the UV-induced TC-->TT mutation, and by extension to the CT-->TT, CC-->TC, CC-->CT, and the tandem CC-->TT mutations, are discussed.

Steroid receptors and giant cell tumor of bone

The cell of origin and giant cell tumor remains unknown, but on the basis of most experimental evidence it is probably a mesenchymal cell showing some macrophage characteristics. The clinical features which have led people to suggest that this tumor may be a steroid receptor positive lesion are tenuous at best. Early histochemical data suggesting a presence of estrogen and progesterone receptors in giant cell tumor have not been substantiated by further studies. Immunohistochemical techniques have not identified estrogen receptors in giant cell tumor. Multiple biochemical techniques have failed to identify clinically significant levels of estrogen or progesterone receptors in giant cell tumor.

Laboratory medicine. Series on clinical testing. 2. Fractionation of urinary ketosteroids. Procedure and clinical significance

Ketosteroids, the excretory metabolities of adrenal and gonadal steroids, can be analyzed individually in urine by a simple extraction procedure followed by separation and quantitation by the use of gas/liquid chromatography. The ketosteroids quantitatively detected by the technique are androsterone, etiocholanolone, dehydroepiandrosterone, 11-hydroxyandrosterone, 11-hydroxyetiocholanolone, 11-ketandrosterone, and 11-ketoetiocholanolone. Other steroid metabolities detected are pregnanediol, pregnanetriol, delta5-pregnenetriol, and 11-ketopregnanetriol. In comparison with concentrations of these steroids observed in urine specimens collected from healthy individuals, abnormal results occur in specimens from patients with testicular disease, Cushing's syndrome, adrenal hyperplasia, and several types of female hirsutism. Characteristic profiles for each of these diseases are presented.