The changes of histopathology and serum anti-sparganum IgG in experimental sparganosis of mice

The present study is intended to observe the chronologic changes of experimental sparganosis by histopathological observation and detection of circulating anti-sparganum IgG antibody using ELISA. Each of 25 mice was infected with five spargana, and they were examined after 1, 2, 4, 10 weeks or 6 months from infection. The followings are summarized results. 1. The plerocercoids were detected in the subcutaneous tissue of the trunk, neck or axilla, but a few often extended into the skeletal muscle. The recovery rates were 72% at the first week, 80% at the second week, 95% at the fourth week, 92% at the tenth week and 100% at the sixth month. The larvae grew slowly in both length and weight until 6 months. 2. Histopathologically, most of the larvae were observed alive in the soft tissue or skeletal muscle. Numerous eosinophils, neutrophils, lymphocytes and plasma cells were infiltrated focally around the worms by the second week, but they surrounded the worms to form a layer of inflammatory reaction after 4 weeks of infection. Also histiocytes and fibroblasts began to appear around the inflammatory cells at 4 weeks. After 10 weeks, the worms encircled by a thin fibrous layer were found. After 6 months, the worms were surrounded by either fibrous tissue or active inflammatory cells. The inflammation looked more severe in the tracks left by the worms, rather than around the worms. 3. The level of anti-sparganum IgG antibody in the serum showed an increase by the fourth week, and a rapid and continuous increase was observed thereafter by the tenth week after infection.(ABSTRACT TRUNCATED AT 250 WORDS)     

Differential effects of phencyclidine (PCP) and ketamine on mesocortical and mesostriatal dopamine release in vivo

The interactions of phencyclidine (PCP) with the mesocortical dopaminergic system were of interest because of the putative role of this pathway in the etiology of schizophrenia. In the present investigation we examined the effects of PCP, and PCP-receptor agonist, ketamine, on dopamine (DA) release by measuring the levels of 3-methoxytyramine (3-MT), the only DA metabolite which is a reliable indicator of DA release in vivo. PCP increased DA release in the amygdala, pyriform and prefrontal cortices, while ketamine was less potent than PCP in this respect. In contrast to the changes in DA release in the cortical regions, ketamine decreased DA release in striatum, while PCP did not change DA release.     

Phosphatidylinositol-3-kinase is a non-tyrosine phosphorylated member of the insulin receptor signalling complex.

In rat HTC cells expressing a large number of human insulin receptors, insulin stimulated phosphatidylinositol-3-kinase (PI-3-kinase) activity. This activity was more effectively immunoprecipitated with anti-phosphotyrosine antibody (alpha-PY) than with anti-insulin receptor antibody (alpha-IR), suggesting that PI-3-kinase was not directly associated with the insulin receptor. alpha-PY immunoprecipitable PI-3 kinase activity, which was regulated by insulin, corresponded to a small pool of the total cellular PI-3-kinase activity. PI-3-kinase was not directly tyrosine phosphorylated by insulin treatment. A comparison of both catalytic activity and content of PI-3-kinase in alpha-PY immunoprecipitates indicated that after insulin treatment PI-3-kinase activity was enhanced by its association with tyrosine phosphorylated proteins. These studies suggest therefore that PI-3-kinase is a non-tyrosine phosphorylated member of the insulin receptor signalling complex.     

Mutational analysis reveals only one catalytic histidine in neutral endopeptidase ("enkephalinase").

Aside from serving as zinc ligands, kinetic data has implicated one or more additional histidines as catalytic residues in neutral endopeptidase ("enkephalinase") action. One of these histidines has previously been identified as histidine 704 (Bateman et al., J. Biol. Chem., 265:8365-8368, 1990). In order to determine whether a second histidine is involved in catalysis each of these residues not previously changed have been converted to glutamine by site directed mutagenesis. The resultant recombinant enzymes possess full catalytic activity indicating that histidine 704 is the only catalytic histidine in the enzyme.     

Structure of a ricin mutant showing rescue of activity by a noncatalytic residue.

Ricin A chain is an N-glycosidase which removes a single adenine base from a conservative loop of 28S rRNA, thereby inactivating eukaryotic ribosomes. The mechanism of action has been proposed to include transition-state stabilization of an oxycarbonium ion on the substrate ribose by interaction with Glu 177. Conversion of Glu 177 to Gln reduces activity nearly 200-fold [Ready, M. P., Kim, Y., & Robertus, J. D. (1991) Proteins: Struct., Funct., Genet. 10, 270-278] while conversion to Ala (E177A) reduces activity only 20-fold [Schlossman, D., Withers, D., Welsh, P., Alexander, A., Robertus, J., & Frankel, A. (1989) Mol. Cell. Biol. 9, 5012-5021]. X-ray analysis of the latter mutant protein shows that a residue at the edge of the active site, Glu 208, rotates into the space left vacant by the mutation. Its rearranged carboxylate partially substitutes for that of Glu 177. This is equivalent to the rescue of enzyme activity by a second-site reversion. Kinetic analysis shows the E177A mutation affects kcat and not Km, consistent with the notion that the carboxylate serves in transition-state stabilization.     

Increased shikonin production inLithospermum erythrorhizon suspension cultures within situ extraction and fungal cell treatment (elicitor)

Summary The effect ofin situ extraction and elicitor treatment on shikonin production was studied with the suspension cultures ofLithospermum erythrorhizon. Shikonin concentration of 60 mg/L was achieved by the use of both techniques which was 24 times higher than that of control culture, and 65 times higher in terms of shikonin productivity. The host-pathogen effect of elicitor treatment andin situ extraction for product removal were effective for shikonin production.     

Rat thymus reconstitution after thymocyte destruction by glucocorticoid treatment--from the view of endogenous DNA synthesis and soybean lectin responsiveness in thymocytes

The dynamic process in rat thymocyte restoration after their destruction by glucocorticoid (GC) administration was examined. Thymus weight and thymocyte count became minimal 4-5 days after the administration. Then the thymus took a course of recovery. Endogenous DNA synthesis in thymocytes, reflecting their proliferation within thymus, decreased for 4 days but began to increase 6-8 days after GC treatment. Thymocyte responsiveness to soybean lectin (SBL), a possible stimulator for T-cell-precursors, showed elevation 4-5 days after the treatment. A marked decrease of lymphocytes in the cortex and unclearness of cortico-medullary junction were observed 2-3 days after GC treatment. Clusters of small lymphoid cells, which possibly contained SBL-responding cells, were found in the subcapsular area 4 days after the treatment and successively, large lymphocytes became visible in the same area. Thereafter, small lymphocytes in the cortical mid and deep zones increased, and cortico-medullary junction was restored. These histological features are discussed from the view of correspondence with the dynamic changes of endogenous DNA synthesis and SBL responsiveness in the thymocytes after GC administration.     

Substance P modulation of DAMGO binding in the brain of CXBK and Swiss-Webster mice.

The effects of substance P (SP) on the binding of the selective mu opioid agonist [3H]DAMGO to brain membranes of CXBK and Swiss-Webster (SW) mice were compared. We have previously shown that subnanomolar concentrations of SP and N-terminal fragments of SP modulate DAMGO binding in SW brain membranes and hypothesized that modulation occurs via SP interaction with mu 1 sites. In the present study, binding assays using CXBK mice, a strain deficient in mu receptors including mu 1 sites, were performed to assess the effect of mu receptor deficiency on SP-induced modulation of DAMGO binding. Whereas the addition of 0.1 nM SP to the binding mixtures produced up to 30% increase in the values of Kd and maximum binding capacity (R) for the SW strain, SP produced little or no change in the case of CXBK strain. Maximum binding capacity for DAMGO was 43% less in the brain of CXBK mice than in SW mice. No difference was observed in the estimated binding parameters of the spinal cord for the two strains. Whereas pretreatment of brain membranes of SW mice using beta-funaltrexamine (beta-FNA) increased from 2- to 10-fold the modulatory effect of SP, CXBK brain membranes pretreated with beta-FNA remained nearly insensitive to modulation by SP. The effect of SP on the affinity of DAMGO binding in SW mice, but not in CXBK mice, was reversed by the addition of GTP. It is concluded that mu receptor deficiency can markedly influence SP-induced modulation of DAMGO binding.     

Interaction of nuclear factors with upstream sequences of a lipid body membrane protein gene from carrot.

To study the regulation of gene expression during embryo development, we isolated a gene, DC 59, expressed in embryos but not in mature carrot plants. Sequence and S1 analysis showed that the gene was composed of one exon encoding a polypeptide of 19 kilodaltons and was highly homologous to the lipid body membrane protein gene L3 from maize. The plant hormone abscisic acid regulated the accumulation of DC 59 mRNA. To understand the mechanism of embryo-specific and hormonal regulation of DC 59, 5' DNA fragments were incubated with nuclear proteins. Two adjacent regions (from -706 to -235) interacted with nuclear extracts from embryos, resulting in the formation of four complexes (C1, C2, C3, and C4). Factors involved in the formation of the C3 and C4 complexes could be competed with sequences upstream of DC 8, a gene that is coordinately expressed with DC 59 during embryo development. DNase I footprinting analysis revealed that nuclear extracts from embryos bound to four AT-rich sequences, and the protected motifs within fragment V were located in the highly homologous upstream regions of DC 59 and DC 8 genes.     

A photoactive phosphonamide derivative of GTP for the identification of the GTP-binding domain in beta-tubulin

A GTP photoaffinity probe (125I-APTG) was developed that incorporated an [125I]-N-(4-azidophenyl)-2-amino-3-(4-hydroxy-3-iodophenyl)propionamide group at the gamma-position of GTP through a phosphonamide linkage. A combination of saturation and GTP protection studies (90% protection at 25 microM GTP with an apparent Kd of 5 microM) validated the use of this new probe as a satisfactory GTP mimic. This probe offered the advantage of possessing an 125I radiolabel external to the GTP moiety, in contrast to the previously reported [gamma 32P]-8-N3GTP that possessed an internal 32P radiolabel. This novel feature accommodated the purification of photolabeled peptides using a combination of ion-exclusion, gel filtration, and HPLC techniques. [125I]APTG was used to identify a peptide (beta:65-79) in the exchangeable GTP-binding domain of the beta-subunit of tubulin.