Analysis of the ternary complex formation of human urokinase with the separated two domains of its receptor

Human urokinase-type-plasminogen-activator receptor (uPAR) is a glycolipid-anchored membrane glycoprotein comprising three structurally similar domains. We have succeeded in direct observation of the ternary complex formation of single-chain urokinase (scuPA) or its N-terminal fragment (ATF) with the separated domain-1 (N-terminal domain) and domain-(2+3) (internal and C-terminal domain) of human uPAR, by means of gel-filtration HPLC analysis. This complex was found to consist of the three components in an equimolar ratio (thus referred to as the three-part complex). To determine the nature of the interaction between these components, cross-linking experiments involving various kinds of cross-linkers and competitive binding assay on ELISA were performed. These experiments have shown that each uPAR domain can bind directly to scuPA at low affinity, and that both these domains contribute to the high-affinity binding between scuPA and uPAR in a synergistic manner. It can be considered that the synergistic effect of domain-1 and domain-(2+3) on scuPA binding would result from a conformational change, and that this steric event might trigger the signal transduction reported for scuPA/uPAR binding.

The cloning of mouse keratocan cDNA and genomic DNA and the characterization of its expression during eye development

Keratan sulfate proteoglycans (KSPGs) play a pivotal role in the development and maintenance of corneal transparency. Keratocan, lumican, and mimecan (osteoglycin) are the major KSPGs in vertebrate corneas. To provide a better understanding of the structure/function relationship of keratocan, we have cloned both the mouse keratocan gene and its cDNA. We have also examined its expression during embryonic development. The mouse keratocan gene spans approximately 6.5 kilobases of the mouse genome and contains three exons and two introns. Northern blotting and in situ hybridization were employed to examine keratocan gene expression during mouse development. Unlike lumican gene, which is expressed by many tissues other than cornea, keratocan mRNA is more selectively expressed in the corneal tissue of the adult mouse. During embryonic development, keratocan mRNA was first detected in periocular mesenchymal cells migrating toward developing corneas on embryonic day 13.5 (E13.5). Its expression was gradually restricted to corneal stromal cells on E14. 5 approximately E18.5. Interestingly, keratocan mRNA can be detected in scleral cells of E15.5 embryos, but not in E18.5 embryos. In adult eyes, keratocan mRNA can be detected in corneal keratocytes, but not in scleral cells.

Induction of oral tolerance in splenocyte-reconstituted SCID mice

The participation of each lymphocyte compartment in the induction of oral tolerance for antibody response was investigated by means of a new cell-transfer experimental system, using severe combined immunodeficiency (SCID) mice. Various lymphocyte compartments from BALB/c mice were transferred into SCID mice and these mice were evaluated for oral tolerance induction. First, whole splenocytes from BALB/c mice were transferred into SCID mice and these mice were orally administered bovine alpha s1-casein. The specific antibody response in these mice after subsequent immunization with antigen was greatly reduced compared to controls which were not fed the antigen, and it was demonstrated that oral tolerance was induced in SCID mice bearing donor splenocytes. Oral tolerance was induced in SCID mice that were reconstituted with only T cells, revealing that B cells were not required for the induction of oral tolerance. Further, oral tolerance was induced in SCID mice reconstituted with CD8-depleted splenocytes but not in mice reconstituted with only CD8+ T cells. These results demonstrate that oral tolerance could be induced in SCID mice bearing normal splenocytes and that interaction of CD4+ T cells with antigen-presenting cells other than B cells are responsible for the induction of oral tolerance. Our experimental system may be useful for investigations with human lymphocytes.

Characterization of Bsk mice: I. The Bsk mutation does not involve a recombination of cornea-specific keratin 12 and skin-specific hair keratin genes

PURPOSE

Bsk (bare skin) is an autosomal dominant mutation linked to the Krt 1 (type 1 keratin) locus of mouse chromosome 11. The adult Bsk mouse manifests hair loss and corneal opacity. To identify and characterize the keratin genes involved in this mutation, we examined the hypothesis proposing that the Bsk mutation might involve a recombination event between cornea-specific (K12) and hair-specific (mHa 1, 2, 3 and 4) type I keratin genes.

METHODS

The Bsk phenotype was examined by histochemical analysis, using light and electron microscopy. RFLP was used for their genotyping, and possible keratin gene expression was examined by immunohistochemical staining, Western analysis, RT-PCR and Northern hybridization.

RESULTS

Northern hybridization, RT-PCR and Western blot analysis revealed that mHa 1, 2, 3 and 4 keratins are expressed in the skin, but not in cornea, whereas the expression of K12 is limited to the corneas of the Bsk mice. These data ruled out the hypothesis that Bsk phenotype results from a recombination event between K12 and mHa 1, 2, 3 and 4. Ultrastructural and biochemical analyses also indicated that Bsk does not involve negative dominant mutations of keratin 12, mHa 1, 2, 3 and 4, epidermal-specific keratin 10, or basal cell-specific keratin 14. Expression of an acidic 50 kD keratin, recognized by monoclonal antibody AK 2, was up-regulated in the injured corneas of normal mice as well as Bsk corneas.

CONCLUSION

The gene linked to the Bsk mutation remains unknown. The pathological changes in the skin and corneas may be secondary to the loss of protecting hairs and lashes by an unknown mechanism.

Characterization and expression of the mouse lumican gene

Lumican is one of the major keratan sulfate proteoglycans (KSPG) in vertebrate corneas. We previously cloned the murine lumican cDNA. This study determines the structure of murine lumican gene (Lum) and its expression during mouse embryonic developments. The mouse lumican gene was isolated from a bacterial artificial chromosome mouse genomic DNA library and characterized by polymerase chain reaction and Southern hybridization. The lumican gene spans 6.9 kilobase pairs of mouse genome. The gene consists of three exons and two introns. Exon 1 constitutes 88 bases (b) of untranslated sequence. Exon 2 is 883 b and contains most of the coding sequence of lumican mRNA, and exon 3 has 152 b of coding sequence and 659 b of 3' noncoding sequence. The mouse lumican gene has a TATCA element, a presumptive TATA box, which locates 27 b 5'-upstream from the transcription initiation site. Northern hybridization and in situ hybridization indicate that in early stages of embryonic development, day 7 post coitus the embryo expresses little or no lumican. Thereafter, different levels of lumican mRNA can be detected in various organ systems, such as cornea stroma, dermis, cartilage, heart, lung, and kidney. The cornea and heart are the two tissues that have the highest expression in adult. Immunoblotting studies found that KSPG core proteins became abundant in the cornea and sclera by postnatal day 10 but that sulfated KSPG could not be detected until after the eyes open. These results indicate that lumican is widely distributed in most interstitial connective tissues. The modification of lumican with keratan sulfates in cornea is concurrent with eye opening and may contribute to corneal transparency.

The role of IFN regulatory factor-1 in synovitis and nitric oxide production

The IFN regulatory factor-1 (IRF-1) DNA binding protein regulates expression of genes that are involved with the induction of immune and inflammatory responses. The present study used mice with a targeted disruption of the IFN regulatory factor-1 gene (IRF-1-/-) to examine the role of this transcription factor in synovial inflammation and nitric oxide production. Intraarticular injection of IL-1 or LPS was associated with a significantly reduced intensity of synovial lining hyperplasia and leukocyte infiltration in the IRF-1-/- mice as compared with wild-type mice of the same parental lineage C57BL/6. Nitric oxide (NO) is involved with the pathogenesis of arthritis, and IRF-1 regulates expression of inducible NO synthase (iNOS) in mononuclear phagocytes. Articular chondrocytes from IRF-1-/- mice produced similar levels of NO in response to IL-1 or LPS. Furthermore, the synergistic induction of NO by IFN-gamma and IL-1 or LPS was almost identical in chondrocytes from wild-type and IRF-1-/- mice. This was in contrast to the expected decrease in NO production by peritoneal macrophages from IRF-1-/- mice, suggesting that IRF-1 is not required for iNOS expression in chondrocytes. These results indicate that IRF-1 has a tissue-specific role in the induction of iNOS. Inhibition of this transcription factor may represent a novel approach in controlling inflammatory diseases such as arthritis.

Synthetic studies of vitamin D analogs. XXIV. Synthesis of active vitamin D3 analogs substituted at the 2 beta-position and their preventive effects on bone mineral loss in ovariectomized rats

Analogs related to 1 alpha,25-dihydroxy-2 beta-(3-hydroxypropoxy)vitamin D3 (ED-71) (4), oxa-type and carba-type analogs of vitamin D3 bearing substituents at the 2 beta-position of 1 alpha,25-dihydroxyvitamin D3 (1), were synthesized from the alpha-epoxides (6 and 13). Three analogs, ED-71 (4) and two carba-type analogs (16 and 26), showed potent preventive effects on bone mineral loss in pre-osteoporosis model rats. ED-71 (4) was concluded to be an optimized analog and a promising candidate for the treatment of osteoporosis.

The role of IFN regulatory factor-1 in synovitis and nitric oxide production

The IFN regulatory factor-1 (IRF-1) DNA binding protein regulates expression of genes that are involved with the induction of immune and inflammatory responses. The present study used mice with a targeted disruption of the IFN regulatory factor-1 gene (IRF-1-/-) to examine the role of this transcription factor in synovial inflammation and nitric oxide production. Intraarticular injection of IL-1 or LPS was associated with a significantly reduced intensity of synovial lining hyperplasia and leukocyte infiltration in the IRF-1-/- mice as compared with wild-type mice of the same parental lineage C57BL/6. Nitric oxide (NO) is involved with the pathogenesis of arthritis, and IRF-1 regulates expression of inducible NO synthase (iNOS) in mononuclear phagocytes. Articular chondrocytes from IRF-1-/- mice produced similar levels of NO in response to IL-1 or LPS. Furthermore, the synergistic induction of NO by IFN-gamma and IL-1 or LPS was almost identical in chondrocytes from wild-type and IRF-1-/- mice. This was in contrast to the expected decrease in NO production by peritoneal macrophages from IRF-1-/- mice, suggesting that IRF-1 is not required for iNOS expression in chondrocytes. These results indicate that IRF-1 has a tissue-specific role in the induction of iNOS. Inhibition of this transcription factor may represent a novel approach in controlling inflammatory diseases such as arthritis.

High incidence of nitrosamine-induced tumorigenesis in mice lacking DNA repair methyltransferase

The enzyme O6-methylguanine-DNA methyltransferase repairs alkylation-induced DNA damage, O6-methylguanine and O4-methylthymine, the former being formed more frequently. Previously, by means of gene targeting, we generated mice in which alleles for methyltransferase were disrupted. We now use these mouse lines, which are totally deficient in methyltransferase activity, to examine protective effects of the enzyme against tumor formation. In gene-targeted female mice given an i.p. injection of 5 mg/kg of dimethylnitrosamine, a larger number of liver and lung tumors occurred, as compared with normal female mice treated in the same manner. In male mice given a lower dose of carcinogen, the difference between normal and gene-targeted mice was statistically insignificant although more tumors did form in the gene-targeted mice. Methyltransferase apparently afforded protection from nitrosamine-induced tumorigenesis.

Methylnitrosourea-induced tumorigenesis in MGMT gene knockout mice

Gene targeting was used to obtain mice defective in the MGMT gene, encoding O6-methylguanine-DNA methyltransferase [Tsuzuki et al., Carcinogenesis (Lond.), 17: 1215-1220, 1996]. These MGMT-/- mice were most sensitive to the alkylating carcinogen, methylnitrosourea; when varied doses of methylnitrosourea were administered to 6-week-old mice and survivals at the 30th day were determined, LD50s of MGMT-/- and MGMT+/+ mice were 20 and 240 mg/kg of body weight, respectively. MGMT+/- mice were as resistant as MGMT+/+ mice, but some difference in survival time was noted when the two genotypes of mice were exposed to a relatively high dose of methylnitrosourea. A large number of thymic lymphomas, as well as lung adenomas, occurred in MGMT-/- mice exposed to methylnitrosourea at a dose of 2.5 mg/kg of body weight. In case of exposure to the same dose of drug, no or few tumors occurred in the MGMT+/+ and MGMT+/- mice. It appears that the DNA repair methyltransferase protein protected these mice from methylnitrosourea-induced tumorigenesis.

Alkylation-induced apoptosis of embryonic stem cells in which the gene for DNA-repair, methyltransferase, had been disrupted by gene targeting

An enzyme O6-methylguanine-DNA methyltransferase (MGMT) catalyzes transfer of a methyl group from O6-methylguanine and O4-methylthymine of alkylated DNA to its own molecule, thereby repairing the pre-mutagenic lesions in a single step reaction. Making use of gene targeting, we developed mouse embryonic stem (ES) cell lines deficient in the methyltransferase. Quantitative immunoblot analysis and enzyme assay revealed that MGMT-/- cells, in which both alleles were disrupted, contained no methyltransferase protein while cells with one intact allele (MGMT+/-) contained about half the amount of protein carried by the parental MGMT+/+ cells. MGMT-/- cells have an extremely high degree of sensitivity to simple alkylating agents, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and N-methyl-N-nitrosourea (MNU), whereas MGMT+/- cells are slightly more sensitive to these agents, as compared with findings from normal cells. A high frequency of mutation was induced in MGMT-/- cells on exposure to a relatively low dose of MNNG. Electrophoretic analyses of the DNAs as well as fluorochrome staining of the cells revealed that MGMT-/- cells treated with MNNG undergo apoptotic death, which occurs after G2-M arrest in the second cycle of cell proliferation.

Keratin 12-deficient mice have fragile corneal epithelia

PURPOSE

Expression of the K3-K12 keratin pair characterizes the corneal epithelial differentiation. To elucidate the role of keratin 12 in the maintenance of corneal epithelium integrity, the authors bred mice deficient in keratin 12 by gene-targeting techniques.

METHODS

One allele of murine Krt1.12 gene was ablated in the embryonic stem cell line, E14.1, by homologous recombination with a DNA construct in which the DNA element between intron 2 and exon 8 of the keratin 12 gene was replaced by a neo-gene. The homologous recombinant embryonic stem cells were injected to mouse blastocysts, and germ lines of chimeras were obtained. The corneas of heterozygous and homozygous mice were characterized by clinical observations using stereomicroscopy, histology with light and electron microscopy, Western immunoblot analysis, immunohistochemistry, in situ hybridization, and Northern hybridization.

RESULTS

The heterozygous mice (+/-) one allele of the Krt1.12 gene appear normal and do not develop any clinical manifestations (e.g., corneal epithelial defects). Homozygous mice (-/-) develop normally and suffer mild corneal epithelial erosion. Their corneal epithelia are fragile and can be removed by gentle rubbing of the eyes or brushing with a Microsponge. The corneal epithelium of the homozygote (-/-) does not express keratin 12 as judged by immunohistochemistry, Western immunoblot analysis with epitope-specific anti-keratin 12 antibodies, Northern hybridization with 32P-labeled keratin 12 cDNA, and in situ hybridization with an anti-sense keratin 12 riboprobe. Light and electron microscopy revealed subtle abnormalities in the corneal epithelia of -/- mice (i.e., a decrease in number of cell layers) and cytolysis of superficial cells, but the number of hemidesmosomes and desmosomes are normal in basal and suprabasal cells. The number of keratin intermediate filaments in basal and suprabasal corneal epithelial cells in -/- mice decreases, and they appear as dense bundles. This morphology is similar to that of keratin intermediate filaments in epidermal epithelial, cells but differs from that of normal corneal epithelial cells in which the keratins form fine filamentous networks. The superficial epithelial cells are devoid of keratin intermediate filaments and often detach from the corneal surface of -/- mice.

CONCLUSIONS

The presence of cornea-specific K3-K12 keratin pairs is essential for the maintenance of corneal epithelium integrity.

Organization and expression of the mouse gene for DNA repair methyltransferase

06-Methylguanine-DNA methyltransferase (MGMT) is present in various organisms, from bacteria to human cells, and plays an important role in preventing mutations caused by alkylating substances. To understand better the regulatory mechanism involved in the expression of the gene and to construct a mouse model to investigate roles of the enzyme in carcinogenesis, the genomic sequence for mouse methyltransferase was isolated and characterized. The gene consists of 5 exons and spans over 180 kb, whereas mRNA for the enzyme was less than 1 kb. The promoter region for the gene is GC-rich, contains many Sp1 recognition sequences and lacks typical TATA and CCAAT boxes. Primer extension and S1 mapping revealed the existence of multiple transcription initiation sites, among which a major site was defined as +1. The putative promoter region was placed upstream of the chloramphenicol acetyltransferase (CAT) reporter gene and the construct was introduced into mouse NIH-3T3 cells. Deletion analyses revealed that a sequence from -262 to + 56 carries the basic promoter activity. In addition, an adjacent region, spanning from +56 to +95, carries an E2F-like element that greatly stimulates the frequency of transcription. Alteration of TTTTGGGGC to TTAACGGGC considerably reduced the activity.

Mini ecosystem in space--preliminary experiment on board STS-77

An enclosed ecosystem which is stable on Earth will behave differently when brought into space. Micro-gravity and radiation will affect the dynamics of material circulation or the activities of small creatures of the ecosystem. One series of space experiments aiming to address such issues was planned in the United States (It is termed as ABS--Autonomous Biological System) and Japanese group has been involved with cooperating with the analysis of the flight samples. Before the ecosystem will be on board Russian Space Station "Mir" later 1996 for 3 months, a preliminary flight was carried out in May 1996 on Space Shuttle (STS-77) for 10 days flight. It was the first of such experiments to fly one whole ecosystem in space.

Targeted disruption of the DNA repair methyltransferase gene renders mice hypersensitive to alkylating agent

Alkylation of DNA at the O(6)-position of guanine is one of the most critical events leading to induction of mutation as well as to cancer. The enzyme O(6)-methylguanine-DNA methyltransferase repairs this and related lesions in DNA. By means of gene targeting, we established mouse lines deficient in the methyltransferase gene and tissues from these mice contained no methyltransferase activity. Administration of methylnitrosourea to these gene-targeted mice led to early death, and normal mice treated in the same manner showed no untoward effects. In mice given methylnitrosourea treatment, the bone marrow became hypocellular and there was a drastic decrease in the number of leukocytes and platelets, thereby indicating an impaired reproductive capacity of hematopoietic stem cells. Methyltransferase apparently protected these mice from the pancytopenia caused by the alkylating agent.

TGF-beta contributes to the shift toward Th2-type responses through direct and IL-10-mediated pathways in tumor-bearing mice

In previous reports, we showed that tumor-derived TGF-beta induced overproduction of IL-10, and these suppressive cytokines caused macrophage suppression in EL4-bearing mice. Proliferation of T cells from EL-4, but not IL-2, whereas T cells from normal mice were responsive to IL-2. A balance between Th1- and Th2-type cytokine production in EL4-T in response to anti-CD3 Ab or phorbor myristate acetate plus A23187 shifted toward the Th2 dominant pattern. The prevention of TGF-beta and IL-10 activates in vivo by administration of anti-IL-10 Ab (anti-IL-10) or anti TGF-beta Ab (anti-TGF-beta) resulted in the reduction in EL4-T of both IL-4 dependent proliferation and Th2-dominant cytokine production induced by anti-CD-3 stimulation. In addition, the anti-TGF-beta treatment resulted in complete restoration in EL4-T of suppressed IL-2 responsiveness, IL-2R expression, and Th1-type cytokine production, whereas the anti-IL-10 treatment produced partial recovery. These results lead us to conclude that TGF-beta drives the shift in the Th1/Th2 balance toward Th2 via IL-10-mediated development of the Th2 responses and via inhibition of the Th1-type responses directly in EL4-bearing mice.

TGF-beta contributes to the shift toward Th2-type responses through direct and IL-10-mediated pathways in tumor-bearing mice

In previous reports, we showed that tumor-derived TGF-beta induced overproduction of IL-10, and these suppressive cytokines caused macrophage suppression in EL4-bearing mice. Proliferation of T cells from EL-4, but not IL-2, whereas T cells from normal mice were responsive to IL-2. A balance between Th1- and Th2-type cytokine production in EL4-T in response to anti-CD3 Ab or phorbor myristate acetate plus A23187 shifted toward the Th2 dominant pattern. The prevention of TGF-beta and IL-10 activates in vivo by administration of anti-IL-10 Ab (anti-IL-10) or anti TGF-beta Ab (anti-TGF-beta) resulted in the reduction in EL4-T of both IL-4 dependent proliferation and Th2-dominant cytokine production induced by anti-CD-3 stimulation. In addition, the anti-TGF-beta treatment resulted in complete restoration in EL4-T of suppressed IL-2 responsiveness, IL-2R expression, and Th1-type cytokine production, whereas the anti-IL-10 treatment produced partial recovery. These results lead us to conclude that TGF-beta drives the shift in the Th1/Th2 balance toward Th2 via IL-10-mediated development of the Th2 responses and via inhibition of the Th1-type responses directly in EL4-bearing mice.

Cytotoxicity tests for antimicrobial agents using cultured skin substitutes fixed at interface of air and culture medium

The present study is focused on a new cytotoxicity test using cultured dermal and epidermal sheets, which are fixed at the air and medium interface as a wound surface model. The cultured dermal sheet is composed of human fibroblasts and a collagen matrix, and the cultured epidermal sheet is composed of human keratinocytes and a collagen matrix. Each cultured sheet was fixed at the air and medium interface, over which a piece of test specimen was placed. The in vitro system created, provides a mimetic wound surface since during wound repair, fibroblasts are embedded in an extracellular matrix, while keratinocytes migrate and proliferate on provisional granulation tissue. The results thus obtained in this cytotoxicity test are useful for determining the efficacious amount of antimicrobial agent used in clinical cases.

Leustroduscin B, a new cytokine inducer derived from an actinomycetes, induces thrombocytosis in mice

Leustroduscin B (LSN-B), a novel colony-stimulating factor (CSF) inducer produced by an actinomycetes, has previously been shown to induce CSF production in bone marrow stromal cells. To determine the biological activity of LSN-B on hematopoiesis in vivo, LSN-B was administered intraperitoneally to mice every day for three to six days. Peripheral platelet counts were markedly elevated on days 4 through 6 compared with the control mice injected with vehicle. Serum II/6 levels were low (0.8 ng/ml) or virtually undetectable in the drug treated groups. This cytokine profile suggests that LSN-B induction of thrombocytosis is mechanistically distinct from other cytokine inducers such as IL-1 or FK-565.

TGF-beta enhances macrophage ability to produce IL-10 in normal and tumor-bearing mice

In the present study, we demonstrate that TGF-beta is capable of enhancing macrophage ability to produce IL-10 in normal and EL4 tumor-bearing mice. We found the increase in IL-10 in ascitic fluid and IL-10 mRNA expression in macrophages in parallel with the TGF-beta level and tumor progression. The macrophage production of IL-10 in the tumor-bearing mice was significantly enhanced without LPS stimulation in vitro, compared with normal controls. To clarify the mechanism wherein increased IL-10 production was induced, anti-TGF-beta or anti-IL-10 Abs were administered to EL4-bearing mice. Administration of anti-TGF-beta Ab led to a reduction in the IL-10 contents in ascitic fluid of tumor-bearing mice; however, anti-IL-10 Ab administration did not prevent the increase in TGF-beta contents. Enhanced IL-10 production and mRNA expression of macrophages from the tumor-bearing mice were also reduced by anti-TGF-beta Ab administration. Both anti-TGF-beta and anti-IL-10 Ab administration restored the TNF-alpha production by macrophages in EL4-bearing mice. In normal macrophages, in vitro pretreatment with TGF-beta 1 potentiated IL-10 production, and when natural TGF-beta 1 was administered to normal mice, the recovered peritoneal macrophages showed enhanced IL-10 production. Based on the above findings it can be concluded that TGF-beta enhances macrophage ability to produce IL-10, which sheds a new light on the role of TGF-beta in the immune system.

TGF-beta enhances macrophage ability to produce IL-10 in normal and tumor-bearing mice

In the present study, we demonstrate that TGF-beta is capable of enhancing macrophage ability to produce IL-10 in normal and EL4 tumor-bearing mice. We found the increase in IL-10 in ascitic fluid and IL-10 mRNA expression in macrophages in parallel with the TGF-beta level and tumor progression. The macrophage production of IL-10 in the tumor-bearing mice was significantly enhanced without LPS stimulation in vitro, compared with normal controls. To clarify the mechanism wherein increased IL-10 production was induced, anti-TGF-beta or anti-IL-10 Abs were administered to EL4-bearing mice. Administration of anti-TGF-beta Ab led to a reduction in the IL-10 contents in ascitic fluid of tumor-bearing mice; however, anti-IL-10 Ab administration did not prevent the increase in TGF-beta contents. Enhanced IL-10 production and mRNA expression of macrophages from the tumor-bearing mice were also reduced by anti-TGF-beta Ab administration. Both anti-TGF-beta and anti-IL-10 Ab administration restored the TNF-alpha production by macrophages in EL4-bearing mice. In normal macrophages, in vitro pretreatment with TGF-beta 1 potentiated IL-10 production, and when natural TGF-beta 1 was administered to normal mice, the recovered peritoneal macrophages showed enhanced IL-10 production. Based on the above findings it can be concluded that TGF-beta enhances macrophage ability to produce IL-10, which sheds a new light on the role of TGF-beta in the immune system.

Intracellular activation and cytotoxic action of RS-1541 against cultured human tumor cells

RS-1541, an acyl-derivative of rhizoxin (Fig. 1), is a potent antitumor compound. This agent showed cytotoxicity in vitro on some cultured human tumor cells, although it was less potent than rhizoxin. Rhizoxin exhibited antitumor effects by inhibiting the polymerization of tubulin, whereas RS-1541 did not inhibit tubulin polymerization in vitro. However, cell cycle analysis in vivo showed that the two agents had the same mode of action. The cytotoxicity of RS-1541 was enhanced when the initial cell density of the cells was increased. The cytotoxicity was also enhanced when the membrane fraction of St-4 cells, which were the most sensitive to RS-1541 among the cell lines tested, was added to the target cells. When St-4 cells were incubated with [14C]-RS-1541, significant amounts of [14C]-rhizoxin were produced within the cells. Further fractionation of the crude membrane showed that the activity that enhanced the cytotoxicity of RS-1541 (RS-1541-enhancing activity) belonged to the mitochondrial-lysosomal fraction, not to the microsomal fraction. Both the enhancing activity and the activity that converting [14C]-RS-1541 to [14C]-rhizoxin (RS-1541-converting activity) were inhibited by treatment with chloroquine, an inhibitor of lysosomal function. Cholesterol esterase derived from Candida cylindracea had RS-1541-enhancing and -converting activities. These data suggest that RS-1541 exerts its cytotoxic action after being converted to rhizoxin within the cells by a lysosomal enzyme such as cholesterol esterase.

Delivery and cytotoxicity of RS-1541 in St-4 human gastric cancer cells in vitro by the low-density-lipoprotein pathway

RS-1541 is a 13-O-palmitoyl derivative of rhizoxin, an inhibitor of tubulin polymerization. RS-1541 has been shown to bind preferentially to plasma lipoproteins and to exhibit selective and sustained uptake by tumors in mice. To elucidate a mechanism of RS-1541 cytotoxicity, the cellular uptake and the cytotoxicity of a complex of RS-1541 with human low-density lipoprotein (RS-1541/LDL complex) were investigated in cultured St-4 human gastric cancer cells. Both the cellular uptake and the cytotoxicity of the RS-1541/LDL complex were greater in cells with higher LDL-receptor activities than in control cells. Excess amounts of LDL or 1 microM of monensin, a proton ionophore, significantly inhibited both the uptake and the cytotoxicity of the complex. Chloroquine, an inhibitor of lysosomal enzymes, decreased the intracellular level of rhizoxin liberated from RS-1541 and suppressed the cytotoxicity of the RS-1541/LDL complex. However, a detergent-aided solution of RS-1541 showed very low cellular uptake and cytotoxicity, irrespective of the LDL-receptor activities of these cells. These results demonstrate that the RS-1541/LDL complex is incorporated into the cells via the LDL receptor and that it manifests its cytotoxic activity after forming rhizoxin, the original antitumor agent, in the lysosomes.

Improvement of macrophage dysfunction by administration of anti-transforming growth factor-beta antibody in EL4-bearing hosts

An experimental therapy for improvement of macrophage dysfunction caused by transforming growth factor-beta (TGF-beta) was tried in EL4 tumor-bearing mice. TGF-beta was detected in cell-free ascitic fluid from EL4-bearers, but not in that from normal mice, by western blot analysis. The ascites also showed growth-suppressive activity against Mv1Lu cells, and the suppressive activity was potentiated by transient acidification. To investigate whether the functions of peritoneal macrophages were suppressed in EL4-bearers, the abilities to produce nitric oxide and tumor necrosis factor-alpha (TNF-alpha) upon lipopolysaccharide (LPS) stimulation were measured. Both abilities of macrophages in EL4-bearing mice were suppressed remarkably on day 9, and decreased further by day 14, compared with non-tumor-bearing controls. TGF-beta activity was abrogated by administration of anti-TGF-beta antibody to EL4-bearing mice. While a large amount of TGF-beta was detected in ascitic fluid from control EL4-bearers, little TGF-beta was detectable in ascites from EL4-bearers given anti-TGF-beta antibody. Furthermore, while control macrophages exhibited little or no production of nitric oxide and TNF-alpha on LPS stimulation in vitro, macrophages from EL4-bearers administered with anti-TGF-beta antibody showed the same ability as normal macrophages. These results clearly indicate that TGF-beta contributes to macrophage dysfunction and that the administration of specific antibody for TGF-beta reverses macrophage dysfunction in EL4-bearing hosts.

Augmentation of host resistance against bacterial infection by treatment with leustroducsin B, a new CSF inducer

We tested the in vivo activity of leustroducsin B (LSN B), a new colony-stimulating factor (CSF) inducer isolated from the culture broth of Streptomyces platensis, with mice infected with Escherichia coli. Treatment with LSN B augmented the host resistance to lethal infection of E. coli at doses between 0.1 mg/kg and 1 mg/kg. Serum interleukin-6 (IL-6) levels were found to increase after this treatment, and superoxide anion generation of neutrophils was enhanced in vivo, suggesting that LSN B augmented the host resistance at least in part by inducing IL-6, which subsequently enhanced the bactericidal activity of the neutrophils.

Development of a new wound dressing with antimicrobial delivery capability

A bilaminar wound dressing composed of an outer membrane and an inner three-dimensional matrix of a fabric or a sponge may be considered to constitute an ideal structure that promotes wound healing: the outer membrane prevents body fluid loss, controls water evaporation, and protects the wound surface from bacterial invasion, and the inner matrix encourages adherence by tissue growth into the matrix. Using this concept, we developed a biosynthetic wound dressing with a drug delivery capability. This medicated wound dressing is composed of a spongy sheet of a chitosane derivative and collagen mixture that is laminated to an antimicrobial-impregnated polyurethane membrane. In this study, a gentamycin sulfate-impregnated wound dressing was prepared and evaluated. The antimicrobial efficacy of this wound dressing was examined on an agar plate seeded with Pseudomonas aeruginosa. Also, the cytotoxicity of an antimicrobial released from this wound dressing was examined in an in vitro system with cultured skin substitutes. Both in vitro tests have shown that this wound dressing is capable of suppressing bacterial growth and minimizing cellular damage. In addition, in the treatment of wounds inflicted on rats and rabbits, this wound dressing was shown to be efficacious in covering full-thickness and split-thickness skin defects. Finally, the efficacy of this wound dressing was evaluated in a nonrandomized open-label study of 31 clinical cases. In 31 cases treated with this wound dressing, good or excellent wound healing was achieved.

Using a computer color-matching system in color reproduction of porcelain restorations. Part 3: A newly developed spectrophotometer designed for clinical application

This paper reports the development of a newly modified, noncontact spectrophotometer for clinical use. The instrument is capable of accurately measuring the color within small areas (1 x 2 mm) of a tooth. This spectrophotometer used a 45 degree/0 degree geometry, a 150W halogen lamp, and fiberoptics to focus the light, together with a lens having a focal point distance of 85 mm. A movable platform was added to the apparatus to automatically scan and measure the color of specific areas. Short-term repeatability indicated the color difference delta E to be approximately 0.15.

Behavior of Japanese tree frogs under microgravity on MIR and in parabolic flight

Japanese tree frogs (Hyla japonica) were flown to the space station MIR and spent eight days in orbit during December, 1990. Under microgravity, their postures and behaviors were observed and recorded. On the MIR, floating frogs stretched four legs out, bent their bodies backward and expanded their abdomens. Frogs on a surface often bent their neck backward and walked backwards. This behavior was observed on parabolic flights and resembles the retching behavior of sick frogs on land--a possible indicator of motion sickness. Observations on MIR were carried out twice to investigate the frog's adaptation to space. The frequency of failure in landing after a jump decreased in the second observation period. After the frogs returned to earth, readaptation processes were observed. The frogs behaved normally as early as 2.5 hours after landing.

Activation of temperature-dependent flagellar movement of demembranated fowl spermatozoa: involvement of an endogenous serine protease

In the presence of ATP, the motility of demembranated fowl spermatozoa was vigorous at 30 degrees C, but negligible at 40 degrees C. Motility could be restored at 40 degrees C by the addition of 10-100 ng trypsin ml-1. Chymotrypsin also stimulated the motility, but neither papain nor carboxypeptidase B appreciably affected motility. Conversely, at 30 degrees C sperm motility was inhibited by aprotinin or phenylmethylsulfonyl fluoride. These results suggest that endogenous protease, presumably serine protease, activity is instrumental in the regulation of fowl sperm motility. It seems likely that the site of action of this protease is axonemal, but a direct effect of added protease on dynein ATPase activity could not be demonstrated.

Novel microbial metabolites of the phoslactomycins family induce production of colony-stimulating factors by bone marrow stromal cells. II. Isolation, physico-chemical properties and structure determination

Leustroducsins (LSNs) A, B and C, novel inducers of colony-stimulating factors (CSFs), were isolated from culture broth of Streptomyces platensis SANK 60191 mainly by ethyl acetate extraction and preparative reverse-phase HPLC. The molecular weights and molecular formulae of LSNs A, B and C are 641: C32H52O10NP, 669: C34H56O10NP and 669: C34H56O10NP, respectively. The structure elucidation revealed that they belong to the phoslactomycin group antibiotics, and their structures contain an alpha,beta-unsaturated delta-lactone, an amino group, a phosphate ester and a cyclohexane ring moiety. The structures differ only at the substituent bound to the cyclohexane ring.

A cultured skin substitute composed of fibroblasts and keratinocytes with a collagen matrix: preliminary results of clinical trials

The cultured skin substitute was created through successive cultivation of fibroblasts and keratinocytes that were combined within a collagen matrix. This collagen matrix was composed of a collagen spongy sheet and a collagen gel. The collagen spongy sheet was designed to produce a honeycomb structure having many holes in which all holes through the sheet were filled with collagen gel. This specific structure thereby allows for the nourishment of the cultured keratinocytes on the surface of the matrix when placed on the graft bed. In this study, autologous cultured skin substitute was applied to a 51-year-old man who had sustained a burn injury. Three sheets of the cultured skin substitute (6 x 9.5 cm) were grafted onto the full-thickness excised wound in the right anterior chest wall. One week after grafting most of the matrix disappeared and stratified keratinocytes were seen to have firmly attached to the underlying tissue. Five weeks after grafting a cornified epidermal layer was seen. Ten months after grafting a mature epidermis and a well-differentiated papillary and reticular dermis replacement were observed. The physical properties and color of this grafted area resemble those of normal skin. In the second test case, autologous cultured skin substitute was applied to a 30-year-old man with a scar remaining after tattoo removal. Eight sheets of the cultured skin substitute (10 x 18 cm) were applied on an excised wound (thickness, 0.02-0.025 in.) of both the fore- and upper arms. The histological appearance of a biopsied skin specimen from the grafted area at 3 months after grafting showed a mature epidermis and a well-differentiated reticular dermis replacement. The regenerated skin at 14 months after grafting showed an excellent result.

Screening method for colony-stimulating factor inducers using a human bone marrow stromal cell line, KM-102

A new screening method for inducers of colony-stimulating factors (CSFs) was established using KM-102, a human bone marrow stromal cell line as the producer. In this method, the assay system which uses CSF dependent cell lines is combined with the CSF production system. Interleukin-1 (IL-1), which is known to upregulate CSF production in many cell populations, was used as a positive control for production of granulocyte CSF (G-CSF) and granulocyte-macrophage CSF (GM-CSF). Induction in the positive controls was clearly detected within 24 hours. Activators of protein kinase C (PKC), protein phosphatase inhibitors and lipopolysaccharide (LPS) were positive in this assay system, but muramyl dipeptide (MDP) and Bestatin which are known macrophage activators, were negative. Inducers of CSFs were successfully detected using this assay method. Among 1,600 microbial strains tested, 2 actinomycete strains were found to produce active substances. One strain produces teleocidin-A, a strong activator of PKC, and the other strain produces a mixture of active compounds including three novel compounds. These three compounds do not induce terminal differentiation of HL-60 cells, suggesting that they are not teleocidin-like substances and form a new class of CSF inducers.

[Influence of cerebellopontine angle tumor on cerebellar circulation--possibility of remote effect to the cerebellum]

Nine cases (4 men and 5 women, ranging in age from 39 to 73 years with a mean age of 51 years) of cerebello-pontine angle tumors were evaluated by cerebral blood flow scintigraphy on the basis of clinico-functional anatomy. In the 4 of 5 cases in which the middle cerebellar peduncle was compressed by the mass, definite hypoperfusion was revealed in the ipsilateral cerebellar hemisphere. On the other hand, in the 3 of 4 cases without compression of the middle cerebellar peduncle, no asymmetric perfusion was seen in either the right or left cerebellar hemisphere. There were neither supratentorial lesions nor signs of increased intracranial pressure in any of the 9 cases. On the vertebral angiograms of the 4 cases with compression of the middle cerebellar peduncle, non-opacification of the ipsilateral anterior inferior cerebellar artery occurred in only one case. There were no definite signs of reduction of cerebellar blood flow in the other 3 cases. The middle cerebellar peduncle is one of the largest bundles of centripetal fibers in the cerebellar hemispheres. Secondary neuronal fibers of the corticopontocerebellar pathway are the most prominent among these fibers. The mass lesion in the cerebellopontine cistern has a tendency to compress the middle cerebellar peduncle and may deactivate the corticopontocerebellar pathway even if it is small.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of cell-mediated immunity in the resistance to experimental sporotrichosis in mice

Congenitally athymic nude (nu/nu) mice showed higher sensitivity to intratestical infection of Sporothrix schenckii than phenotypically normal littermates (nu/+). Active immunization with viable cells enhanced the resistance to intravenous (i.v.) infection of this fungus in BALB/c mice. Nu/nu mice transferred with immune spleen cells acquired the enhancement of resistance to the infection with S. schenckii, but not ones with normal spleen cells. Pre-treatment of OK-432 (Picibanil), one of the macrophage activating agents, enhanced resistance to i.v. infection of this fungus in BALB/c mice. On the other hand, pretreatment of carrageenan, one of the macrophage inhibitors, impaired the resistance. This fungus was intracellularly killed by peritoneal macrophage from OK-432 treated or immunized mice but not by those from normal mice in vitro. These results suggest that activated macrophage, that was mediated by T cells, play an important role in the resistance to S. schenckii in mice.

[Principle of treatment of intermittent claudication due to arteriosclerosis obliterans--reconstruction or conservative treatment]

MATERIALS AND METHODS

Two hundred and one patients of arteriosclerosis obliterans (ASO) with intermittent claudication (IC) were studied. Improvement of IC, score of return to social life, change of life condition and prognosis were compared between the two groups of reconstructive and conservative treatment.

RESULTS

Improvement of IC was seen in 88.0% of the patients in the group of reconstruction and only 30.4% in the conservative treatment group. In the reconstructive group, the score of return to social life improved from 2.10 to 1.31 and the score of life condition also improved from 2.71 to 1.66. However in the conservative treatment group these score showed no significant improvement. Moreover the long term mortality rate was lower in the treatment group of reconstruction.

CONCLUSION

The arterial reconstruction for IC is significant for improving the quality of life and exerts a favorable effect on life prognosis.

Isolation and characterization of cDNA and genomic sequences for mouse O6-methylguanine-DNA methyltransferase

An enzyme, O6-methylguanine-DNA methyltransferase, is present in various organisms and plays an important role in repair of DNA damaged by alkylating agents. The enzyme transfers methyl groups from O6-methylguanine and other methylated moieties of the DNA to its own molecule. As a first step to construct animal models with altered levels of the enzyme activity, we cloned cDNA and genomic DNA sequences for mouse methyltransferase and elucidated their structures. The nucleotide sequence of the cDNA revealed an open reading frame comprising 211 amino acid residues. The mol. wt of mouse O6-methylguanine-DNA methyltransferase, calculated from the predicted amino acid sequence, was 22,400, and the methyltransferase protein of this size was present when the cDNA was expressed in methyltransferase-deficient human cells. The predicted amino acid sequence of the mouse methyltransferase exhibits an intense homology with those of human and bacterial counterparts. Using the cDNA as a probe, part of the mouse gene for methyltransferase was isolated. The gene consisted of at least four exons and spanned greater than 145 kb. Sequences around the exon/intron junctions for the mouse gene are almost the same as those for the human species.

Local motion processing in the optic tectum of the Japanese toad, Bufo japonicus

The results of previous behavioral studies can be so interpreted that the prey-catching behavior in the toad is elicited if there is a 'local' motion restricted within a small part of the visual field, while it is suppressed if there is a 'global' motion over a large part of the visual field. This has led us to design experiments to answer a specific question (yet a very essential one for understanding neural processes underlying this behavior): Are there 'local motion detectors' in the toad's visual system that are not activated by 'global' motion over a large part of the visual field but are activated by 'local' motion confined within a smaller part of it? The present study showed that (1) the majority of the toad's tectal neurons exhibit properties of the 'local motion detectors' as defined above, and (2) these properties can be explained from the receptive field structure revealed in the present experiments. Based on these results, we suggest that the tectal 'local motion detectors' are essential for the detection and localization of small moving prey-objects in the natural environment while ignoring the large moving objects or the self-induced motion of the visual field.

Cloning and expresion of cDNA for rat O6-methylguanine-DNA methyltransferase

cDNA for O6-methylguanine-DNA methyltransferase was isolated by screening rat liver cDNA libraries, using as a probe the human cDNA sequence for methyltransferase. The rat cDNA encodes a protein with 209 amino acid residues. The predicted amino acid sequence of the rat methyltransferase exhibits considerable homology with those of the human, yeast and bacterial enzymes, especially around putative methyl acceptor sites. When the cDNA was placed under control of the lac promoter and expressed in methyltransferase-deficient Escherichia coli (ada-, ogt-) cells, a characteristic methyltransferase protein was produced. The rat DNA methyltransferase thus expressed could complement the biological defects of the E. coli cell caused by lack of its own DNA methyltransferases; e.g. increased sensitivity to alkylating agents in terms of both cell death and mutation induction.

New noninvasive assessment of regional left ventricular function by digital subtraction angiography without the use of contrast medium

We have developed a new noninvasive method to evaluate regional left ventricular (LV) function by digital subtraction angiography (DSA) without the use of contrast medium. DSA images of the left ventricle with and without contrast medium were obtained from 35 patients with anterior myocardial infarction (MI) and from 35 control subjects. Using an image-processing computer, regional LV time-density curves were constructed for one cardiac cycle. Regional LV time-density curves obtained from DSA without the use of contrast medium presented a pattern similar to those from intravenous DSA. The amplitude of regional LV time-density curves in patients with MI decreased along with increasing severity of regional wall motion abnormality assessed by conventional left ventriculography. In attempting semi-quantitative evaluation by DSA without the use of contrast medium, the regional wall motion index (RWI) in the 6 segments of the left ventricle was calculated by normalizing segmental density changes to the maximal segmental density changes. When compared with control subjects, patients with MI have significantly lower RWIs in the anterolateral and apical regions. RWI showed a good correlation with the regional ejection fraction (REF) obtained from intravenous contrast DSA (r = 0.83). RWI decreased with increasing severity of regional wall motion abnormality by qualitative analysis in conventional left ventriculography, being consistent with REF. The diagnostic accuracy of RWI therefore seemed to be comparable to that of REF derived from intravenous contrast DSA. These results indicate that computerized analysis of DSA without the use of contrast medium is a valuable noninvasive method for semi-quantitative assessment of regional LV function.

Aladapcin, a new microbial metabolite that enhances host resistance against bacterial infection. Production, isolation, physico-chemical properties and biological activities

We have constructed a new screening system for detecting microbial products that enhance host resistance against bacterial infection. It was found that a new compound with such activity is produced by a soil isolate classified as Nocardia sp. SANK 60484. The compound was isolated from the culture filtrate of the organism and named aladapcin after its amino acid composition. Aladapcin was obtained as an amphoteric white amorphous powder with the molecular formula, C13H25N5O5. It consists of 2 mol of D-alanine and 1 mol of meso-diaminopimelic acid. From the analysis of IR, 1H NMR and FAB-MS spectra, the structure was assigned to be a tripeptide. Aladapcin enhanced host resistance against an experimental Escherichia coli infection in mice at doses ranging between 1 and 100 micrograms/kg.

Relationship between coronary risk factor and arteriographic feature of coronary atherosclerosis

Coronary arteriography was performed in 1,029 consecutive patients with ischemic heart disease and the relationship between the arteriographic features of coronary atherosclerosis and coronary risk factors was analyzed by case control studies. Patients were divided into four groups according to coronary arteriographic findings. Patients with normal or near normal coronary arteriograms (Group I) showed a high prevalence of smoking habit and a higher value of serum uric acid compared with the control group, so smoking and hyperuricemia were considered to be the risk factors for coronary atherosclerosis in patients of group. Four selected variables: smoking, hyperuricemia, hypertension and hyperlipidemia, were identified to be risk factors for the patients with minor plaques in the coronary arteries (Group II). As in Group I, smoking and hyperuricemia had a close relationship to solitary tight plaque in a branch of the coronary artery (Group III). Multiple tight stenoses in the coronary arteries (Group IV) correlated closely with smoking, hyperuricemia, hypertension, hyperlipidemia and diabetes mellitus. Thus, there were many strong risk factors for patients with diffuse, extended coronary atherosclerosis (Group II and Group IV), while only two factors, smoking and hyperuricemia, were considered to be risk factors for the patients with near normal coronary arteries ies or a solitary plaque in a branch of the coronary artery. These findings suggest that the role of the coronary risk factors on the pathogenesis of coronary atherosclerosis is not uniform but variable depending on the morphologic variability of the coronary atherosclerosis and on the pathophysiology of the ischemic heart disease.

[A case of alcoholic cirrhosis demonstrating long-term poor-visualization of the hepatic image on 99mTc-phytate scintigraphy]

A 27-year-old female patient with alcoholic cirrhosis was reported. She was admitted to the hospital because of jaundice and ascites after heavy drinking. She had a history of drinking Japanese Sake in quantities of more than 5 go/day (900 ml/day) for 7 years. On admission, she was icteric, and had both hepatosplenomegaly and ascites. Laboratory data showed an elevation of serum transaminase and bilirubin, and a decrease in the albumin and prothrombin values. A biopsy specimen of the liver showed pericellular fibrosis, fatty change, Mallory bodies and regenerative nodules, and revealed findings compatible with alcoholic cirrhosis. A 99mTc-N-pyridoxyl-5-methyltryptophan scintigram showed hepatomegaly. On the 99mTc-phytate scintigram, the uptake of radioisotope to the liver was markedly decreased with the increased uptake to the spleen and bone marrow. Even 6 months after the onset, poor visualization of the hepatic image on 99mTc-phytate scintigram continued. This is the first report of alcoholic cirrhosis demonstrating a long-term poor visualization of the hepatic image on 99mTc-phytate scintigraphy.

Behavioral sensitization to beta-phenylethylamine (PEA): enduring modifications of specific dopaminergic neuron systems in the rat

Repeated daily administration of an endogenous trace amine, beta-phenylethylamine (PEA), produces behavioral sensitization such that the intensity of PEA-induced stereotyped behaviors in rats increases gradually during the treatment, and a challenge injection with PEA reinstates the enhanced stereotypy even long after withdrawal. In the present study, we examined the neurochemical changes in the central dopaminergic neurons systems in the rat for 7 drug-free days after repeated treatment with PEA (50 mg/kg, IP day for 14 or 28 days). During withdrawal, a decrease in steady-state levels of tissue dopamine (DA) and its metabolite, dihydroxyphenylacetic acid (DOPAC), was found in the mesolimbic DA nerve terminal areas of the rat brain receiving repeated PEA treatment. Fifteen minutes after challenge administration of PEA at varying doses from 6.3 to 75 mg/kg, the rats with repeated PEA treatment required smaller doses of PEA challenge than the rats with acute PEA treatment in order to obtain a significant decrease in striatal DOPAC content compared to the saline control in each treatment group. These results imply that the behavioral sensitization to PEA is accompanied by enduring modifications of the specific dopaminergic neuron systems in the rat brain. This suggestion was strongly supported by the results of the study using in vivo intracerebral dialysis, which indicated that 25 mg/kg PEA challenge elicited a remarkable increase in the extracellular DA concentrations in striatal perfusates collected from the PEA-pretreated rats, in accordance with the intensity of stereotyped behaviors. These findings argue that the hyper-responsiveness to PEA of the striatal dopaminergic neuron systems persists long after withdrawal from repeated treatment with PEA.

After-effects of moving textured background in motion-sensitive neurons of anuran optic tectum

Motion-sensitive neurons in anuran optic tectum were shown to respond to a stationary object centered in the excitatory receptive field, if a textured background moved for a while and then stopped ('motion after-response'). This motion after-response was attributed to a post-inhibitory rebound activation derived from effects of masking the excitatory receptive field center surrounded by an antagonistic inhibitory region. It was suggested that a similar rebound activation mechanism may also be involved in a certain type of perceptual motion after-effects in humans.

[A case of esophageal diverticula in a child]

Esophageal diverticula in infants and children are rarely seen, even by the pediatric radiologist. This is a case report of an infant girl presenting with an esophageal diverticulum arising from the right anterior lateral aspect of the proximal third of the esophagus. The diverticulum included a metallic foreign body.

Determination of guanine by high-performance liquid chromatography with electrochemical detection: application to DNA and RNA assays

A highly sensitive assay for guanine was developed using high-performance liquid chromatography with electrochemical detection (ECD). Guanine was susceptible to the electrochemical oxidation, and ECD response was proportional to the amount of guanine in the range 0.25-4 pmol of guanine. The ECD of guanine was applicable to the analysis of nucleic acids. DNA and RNA were hydrolyzed in 0.03 and 3 M HCl, respectively, and guanine liberated from the nucleic acids was separated on a reverse-phase column and determined by ECD. The method allowed detection of 0.2 ng of calf thymus DNA or tRNA. An application of the method is shown for DNA and RNA assays in trichloroacetic acid extracts of rat adrenal and liver.