[Study on polysaccharide of Lobaria kurokauae]

LOK polysaccharide is isolated from Lobaria kurokauae. By chromatography, LOK is shown to be sing substance. By gas chromatography analysis, LOK composes of rhamnose, arabinose, xylose, mannose, glucose and galactose. Their molecule ratio is about 1.00:1.34:1.12:10.13:6.99:6.47. Its mean molecule weight is estimated to be 1.5 x 10(4), its main chain is joined by a (1-->4) and a (1-->6) glucosidic linkages.

Colocalization of P2Y2 and P2Y6 receptor genes at human chromosome 11q13.3-14.1

Extracellular nucleotides mediate a number of physiological responses through either ligand gated P2X or G protein-coupled P2Y receptors. To date, six P2Y receptor subtypes, P2Y1-P2Y6, have been cloned. We mapped the human P2Y6 receptor gene to chromosome 11q13.3-13.5. Oligonucleotide primers complementary to a part of the human P2Y6 receptor cDNA were used to amplify a region from genomic DNA from a panel of mouse/human somatic cell hybrid cell lines, each containing a single human chromosome. A PCR product of the expected size (714 bp) resulted from a single hybrid cell line containing human chromosome 11. The gene was further localized to a region of chromosome 11 using a subchromosomal hybrid panel containing different segments of chromosome 11. Based on the specific PCR product obtained and its Southern hybridization to the P2Y6 receptor cDNA, the human P2Y6 receptor gene was localized to chromosome 11q13.3-13.5. Previously, we have localized the P2Y2 receptor gene to human chromosome 11q13.5-14.1. This is the first report of the clustering of the P2 receptor genes. The clustering of these two P2Y receptor subtypes suggests a relatively recent expansion of the gene family by gene duplication.

Inhibitory receptors, ITIM sequences and phosphatases

A diverse group of inhibitory receptors, including FcgammaRII, killer cell inhibitory receptors, and B22, shares an immunoreceptor tyrosine-based inhibition motif (ITIM). Recent studies have shown that this motif, when phosphorylated on tyrosine, forms a docking site for the Src homology 2 recognition domains of the protein tyrosine phosphatase SHP-1 and the inositol 5-phosphatase SHIP. A similar motif in cytotoxic T-lymphocyte antigen-4 recruits the related tyrosine phosphatase SHP-2. These three enzymes act to inhibit signaling cascades resulting from ligation of the BCR, TCR, FcgammaRIII, and FcepsilonRI, although the relative importance of the tyrosine phosphatases and the inositol phosphatase differs depending on the cell type.

Constitutive activity of human prostaglandin E receptor EP3 isoforms

1. The human EP3 prostaglandin receptor is a seven transmembrane, G protein-coupled receptor that couples to inhibition of adenylyl cyclase. The receptor occurs as at least six isoforms which result from alternative splicing. The isoforms are identical over the first 359 amino acids, comprising the seven transmembrane helices, but differ in the carboxyl terminal tail which ranges in length from 6 to 65 amino acids beyond the common region. 2. We have stably expressed in CHO-K1 cells four of the isoforms (EP3I-EP3IV) and a form of the EP3 receptor (T-359) truncated at the carboxyl-terminal region defined by the alternative splicing site at amino acid number 359. 3. Isoforms EP3I and EP3II showed concentration-dependent inhibition of forskolin-stimulated adenylyl cyclase in CHO-K1 cells by the EP3 receptor agonist, sulprostone. The IC50 calculated for sulprostone inhibition was 0.2 nM for EP3I and 0.15 nM for EP3II. The maximum extent of inhibition was 80% for both isoforms. 4. Isoforms EP3III and EP3IV showed marked constitutive activity, inhibiting forskolin-stimulated adenylyl cyclase in the absence of agonist. EP3IV also displayed some agonist-dependent inhibition whereas EP3III was fully constitutively active. 5. The truncated receptor T-359 was fully constitutively active, inhibiting forskolin-stimulated adenylyl cyclase by about 70% in the absence of agonist, and showed no agonist-dependent inhibition, in agreement with a similar truncation of the mouse EP3 receptor. 6. To confirm that differences in cyclic AMP level between isoforms represent constitutive activity, we treated cells with pertussis toxin for 6 h to abolish Gi function. Pertussis toxin reversed sulprostone-mediated inhibition of cyclic AMP formation in EP3I and EP3II and abolished constitutive activity of EP3III, EP3IV and T-359 so that the level of forskolin-stimulated cyclic AMP produced was the same in all cells and similar to that obtained in mock-transfected cells. In mock-transfected cells, sulprostone had no effect on forskolin-stimulated cyclic AMP formation. 7. For these experiments we chose clones that showed similar expression levels of each isoform, as determined by binding of [3H]-prostaglandin E2 (PGE2) (EP3I, 0.71; EP3II, 1.47; EP3IV, 1.59 pmol mg-1 protein). Mock-transfected cells showed no detectable binding of [3H]-PGE2. In addition, we performed a detailed study of the effects of expression level on constitutive activity. Over a six fold range of expression there was no change in the properties of each isoform with regard to whether it was constitutively active or not. 8. The degree of constitutive activity correlated with the inverse of the length of the C-terminal tail of the isoforms. However, no correlation was found between isoforms from human and mouse: whereas EP3II shows no constitutive activity, its mouse homologue, EP3 gamma, shows almost complete constitutive activity, even though the C-terminal domains of the receptors following the splice site differ in only 7 of 29 amino acids.

Characteristics of memory dysfunction in olfactory bulbectomized rats and the effects of cholinergic drugs

The memory impairment of olfactory bulbs (OB)-lesioned rats was characterized using 4 different tasks of learning/memory, and the effects of certain cholinergic drugs on such memory impairment were examined. In reference memory and working memory tasks using a 3-panel runway apparatus, OB-lesioned rats showed a marked increase in errors. In the 3-lever operant task using delayed matching to a sample (DMTS) procedure, OB lesions significantly decreased the correct response in choice (test) trials without affecting the in sample (training) trials. An interesting finding is that impairment in the DMTS performance did not appear immediately after the OB lesion, but tended to appear after a delay. Based on this finding, it is unlikely that memory impairment in the OB-lesioned rats is due to the olfactory deficit itself. However, OB lesions significantly reduced the choice accuracy and delayed the choice reaction time during the 3-choice serial time task for assessing attentional function, using a 3-lever operant apparatus. These findings suggest that marked impairment of learning and memory in OB-lesioned rats may be caused by the attention deficit. Furthermore, the memory impairment in OB-lesioned rats was reduced by cholinesterase inhibitors, physostigmine and NIK-247. These finding suggest that dysfunction of the cholinergic system is involved, at least in part, in the memory impairment of OB-lesioned rats.

A1-adenosine receptor antagonists block endotoxin-induced lung injury

Endotoxin produces a variety of biological effects on different cell types, such as priming of neutrophils and macrophages, which then release a number of important mediators of endotoxin-induced lung injury. However, the specific mechanism by which endotoxin initiates its cascade of pathophysiological events in the lung has not been described. Both A1 adenosine receptor activation and endotoxin induce the release of thromboxane A2 from the lung and inhibit adenylate cyclase. By acting on A1 adenosine receptors, adenosine promotes neutrophil chemotaxis and adherence to endothelial cells. We hypothesized that A1 adenosine receptor activation is essential to endotoxin-induced lung injury, and we used the highly selective A1-adenosine receptor antagonists, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) and 8-benzyl-7,[2-[ethyl(2-hydroxyethyl)amino]-ethyl] theophylline (bamiphylline), to investigate whether selective blocking of the A1 adenosine receptor would prevent endotoxin-induced acute lung injury. An intralobar arterial infusion of endotoxin (15 mg/kg) into the left lower lobe of the lung in intact-chest, spontaneously breathing cats produced lung injury characterized by the presence of neutrophils, macrophages, and red blood cells (RBCs) in alveoli, and alveolar edema and necrosis. Lower doses of endotoxin (5 or 10 mg/kg) produced less severe and dose-dependent lung injury. Endotoxin (15 mg/kg)-induced alveolar injury was blocked in a highly significant manner by A1-adenosine receptor antagonists, DPCPX and bamiphylline. An intravenous bolus of DPCPX 30 min before endotoxin infusion or a continuous intravenous infusion of bamiphylline 30 min before, during, and 30 min after endotoxin reduced the percent injured alveoli (defined as the presence of 2 or more inflammatory cells or RBCs, or edematous fluid) from 57 +/- 31% (endotoxin 15 mg/kg) to 9 +/- 1% (DPCPX) or 21 +/- 14% (bamiphylline), which were not significantly different from control (1-h perfusion only) (4 +/- 1%) (P < 0.05). These data represent the first evidence that A1-adenosine receptor antagonism blocks the capacity of endotoxin to cause lung injury. A1-adenosine receptor antagonists may be useful in preventing adult respiratory distress syndrome associated with septicemia.

Description of blood pressure changes in patients beginning cyclosporin A therapy

Cyclosporin A (CyA) is the primary immunosuppressive agent for the prophylaxis of rejection episodes in renal, cardiac, liver, and other transplants. Recently, its use in autoimmune diseases has been investigated as well. Although several studies have produced promising results, nephrotoxicity and hypertension can result from CyA treatment, and their development must be understood in order to facilitate patient management. This article describes the diastolic blood pressure (DBP) responses in two populations of patients during three months of CyA therapy. Study A involved psoriasis patients and Study B involved postoperative renal transplant patients. The relationship between blood pressure and systemic CyA exposure and other covariates was evaluated using linear mixed effects modeling. Temporal patterns of blood pressure changes with varying duration of CyA exposure were investigated. In Study A, the psoriasis patients showed transient exposure-related increases in DBP on CyA. These elevations, while statistically significant, were clinically insignificant. In Study B, the renal transplant patients showed no CyA-related rises in DBP. In neither study was there evidence for a difference in effect on DBP between Sandimmune and Neoral, the two formulations of CyA presently approved for marketing by the Food and Drug Administration, after differences in CyA exposure were taken into account.

The involvement of sigma receptors in the choice reaction performance deficits induced by phencyclidine

The present study investigated the effects of phencyclidine (PCP) on choice reaction in a 3-choice serial reaction time task for studying attentional function. PCP (3.2 mg/kg) significantly delayed choice reaction time and reduced choice accuracy. A novel sigma receptor antagonist N,N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]-ethylamine monohydrochloride (NE-100) at 3.2 mg/kg, and 1-(cyclopropylmethyl)-4-[2'-4"-fluorophenyl)-2'-oxoethyl]piperidin e HBr (DuP734) at 1.0-3.2 mg/kg, but not 4-[2'-(4"-cyanophenyl)-2'-oxoethyl]-1-(cyclopropylmethyl)pip eridine (XJ448), antagonized both the delayed choice reaction time and the decreased choice accuracy elicited by PCP administration. The antagonism induced by NE-100 was blocked by the sigma receptor agonist (+)-N-allylnormetazocine HCl [(+)-SKF10,047]. These findings indicated that PCP (3.2 mg/kg) significantly induced attention deficit in a 3-choice serial reaction time task, and that this process may be mediated by sigma receptors.

Role of hydroxyl radicals in radiation-induced activation of lyn tyrosine kinase in human B-cell precursors

Here we show that exposure of human B-cell precursors to gamma-rays stimulates the enzymatic activity of the Src protooncogene family protein tyrosine kinase LYN. LYN activation in irradiated cells is not triggered by DNA damage or a nuclear signal since gamma-rays effectively stimulated LYN kinase in enucleated B-cell precursors as well. LYN activation in irradiated cells was abrogated by presence of the OH* radical scavenger dimethylsulfoxide and exposure of intact or enucleated B-cell precursors to chemically generated OH* radicals instead of gamma-rays also triggered LYN kinase activation and enhanced tyrosine phosphorylation of multiple electrophoretically distinct protein substrates. Thus, OH* radicals appear to be both mandatory and sufficient for radiation-induced LYN kinase activation in irradiated B-cell precursors. We further present evidence which indicates that OH* radicals activate LYN by a novel mechanism which involves disruption of inactive LYN-LYN homodimers and monomerization of the LYN kinase after proteolytic degradation of a putative LYN-associated adapter protein through a cytoplasmic TPCK-sensitive chymotrypsin-like protease following its oxidation. LYN kinase plays a pivotal role in initiation of signal cascades that affect the proliferation, differentiation, and survival of B-cell precursors. Our results prompt the hypothesis that a growth regulatory balance might be altered in human B-cell precursors by radiation-induced stimulation of LYN kinase.

Intramyocardial arterial cushions of coronary vessels in animals and humans: morphology, occurrence and relation to heart disease

The existence of coronary endoarterial cushions (CEC) in the human heart as nonpathological, functional entities has been debated, and CEC have been sparsely reported in animals. Arterial cushions are localized thickenings that protrude into the lumen of specific arteries. We have identified CEC in the rhesus monkey, dog, sheep, goat, pig, rabbit and rat, and in the human heart. Two distinct types are described: the ovoid CEC arranged singly, in pairs, or in groups of three to four, and the less common polypoid CEC seen primarily in humans. The highest incidence of CEC in rabbits and humans was in the left ventricle in arteries 150-488 microns in diameter. Light and electron microscopy demonstrated intimal location with smooth muscle cells surrounded by ground substance, collagen and elastin fibers in a highly organized pattern. Nerve fibers identified by their immunoreactivity with antiserum to the vasodilatory calcitonin-gene-related peptide contacted the CEC along the tunica media and were occasionally seen within CEC. Arrangement and histological composition of CEC suggest a role in the regulation of local blood flow and myocardial perfusion. In human hearts, the CEC density index correlated highly with the degree of heart disease. In subjects with high heart disease rating, increased connective tissue, lipid-like infiltration and calcification was seen within CEC, and foam cells were present in CEC of obese rabbits. This suggests that CEC in coronary arteries could be predisposed sites of atherosclerosis, and that injured CEC can cause coronary artery spasm and ischemia. We conclude that CEC occur in animals and humans as innervated intimal smooth muscle cushions that might have a role in myocardial perfusion and heart disease.

[The pulmonary function in scoliotic patient]

This paper investigated preoperative pulmonary functions in 134 scoliotic patients, of whom 32 cases was followed up for their postoperative pulmonary functions. The results show that the bigger the Cobb of the scoliosis, the greater the damages of the pulmonary functions. Congenital scoliosis is more severely affected by pulmonary functions than idiopathic scoliosis. There was no significant difference among the different sections of scoliosis with regard to their effect on the pulmonary functions. The authors concluded that the Harrington Instrumentation improved pulmonary functions in scoliosis.

Stabilization of a HemA-LacZ hybrid protein against proteolysis during carbon starvation in atp mutants of Salmonella typhimurium

Transposon insertions that stabilize the beta-galactosidase activity of a HemA-LacZ hybrid protein following carbon starvation were mapped to the atp operon of Salmonella typhimurium. This effect is similar to that seen with nuo mutants defective in the energy-conserving type I NADH dehydrogenase. Insertions in several other genes, including such highly pleiotropic mutants as rpoS, polA, and hfq, were isolated with the same phenotypic screen, but they do not affect the beta-galactosidase activity of HemA-LacZ. All of these mutants act indirectly to alter the colony color of many different fusion strains on indicator plates.

Signal transduction through the beta1 integrin family surface adhesion molecules VLA-4 and VLA-5 of human B-cell precursors activates CD19 receptor-associated protein-tyrosine kinases

We demonstrate that the CD19 receptor associates with the beta1 family integrin receptors on human B-cell precursors as well as mature B-lymphocytes, and engagement of the beta1 family integrin receptors with monoclonal antibody homoconjugates leads to rapid activation of the CD19-associated protein-tyrosine kinases (PTK) and results in hyperphosphorylation of CD19 on tyrosine residues. Our findings prompt the hypothesis that homoconjugate-induced integrin clustering may effect the approximation and, by intermolecular cross-phosphorylation, activation of the CD19-associated PTK and subsequent tyrosine phosphorylation of the CD19 receptor. The ability of the beta1 family integrin receptors to transmit a biochemical signal triggering the CD19-linked multifunctional PTK pathway provides a possible explanation for the pleiotropic biologic responses generated though adhesive VLA-4- and VLA-5-mediated contacts.

Physical and functional interactions between Lyn and p34cdc2 kinases in irradiated human B-cell precursors

Exposure of human B-cell precursors (BCP) to ionizing radiation results in cell cycle arrest at the G2-M checkpoint as a result of inhibitory tyrosine phosphorylation of p34cdc2 . Here, we show that ionizing radiation promotes physical interactions between p34cdc2 and the Src family protein-tyrosine kinase Lyn in the cytoplasm of human BCP leading to tyrosine phosphorylation of p34cdc2. Lyn kinase immunoprecipitated from lysates of irradiated BCP as well as a full-length glutathione S-transferase (GST)-Lyn fusion protein-phosphorylated recombinant human p34cdc2 on tyrosine 15. Furthermore, Lyn kinase physically associated with and tyrosine-phosphorylated p34cdc2 kinase in vivo when co-expressed in COS-7 cells. Binding experiments with truncated GST-Lyn fusion proteins suggested a functional role for the SH3 rather than the SH2 domain of Lyn in Lyn-p34cdc2 interactions in BCP. The first 27 residues of the unique amino-terminal domain of Lyn were also essential for the ability of GST-Lyn fusion proteins to bind to p34cdc2 from BCP lysates. Ionizing radiation failed to cause tyrosine phosphorylation of p34cdc2 or G2 arrest in Lyn kinase-deficient BCP, supporting an important role of Lyn kinase in radiation-induced G2 phase-specific cell cycle arrest. Our findings implicate Lyn as an important cytoplasmic suppressor of p34cdc2 function.

Recognition of diverse sequences by class I zinc fingers: asymmetries and indirect effects on specificity in the interaction between CF2II and A+T-rich elements

The Drosophila CF2II protein, which contains zinc fingers of the Cys2His2 type and recognizes an A+T-rich sequence, behaves in cell culture as an activator of a reporter chloramphenicol acetyltransferase gene. This activity depends on C-terminal but not N-terminal zinc fingers, as does in vitro DNA binding. By site-specific mutagenesis and binding site selection, we define the critical amino acid-base interactions. Mutations of single amino acid residues at the leading edge of the recognition helix are rarely neutral: many result in a slight change in affinity for the ideal DNA target site; some cause major loss of affinity; and others change specificity for as many as two bases in the target site. Compared to zinc fingers that recognize G+C-rich DNA, CF2II fingers appear to bind to A+T-rich DNA in a generally similar manner, but with additional flexibility and amino acid-base interactions. The results illustrate how zinc fingers may be evolving to recognize an unusually diverse set of DNA sequences.

Role of tyrosine phosphorylation in radiation-induced cell cycle-arrest of leukemic B-cell precursors at the G2-M transition checkpoint

Here we provide experimental evidence that ionizing radiation induces inhibitory tyrosine phosphorylation of the p34cdc2 kinase in human leukemic B-cell precursors. Herbimycin A markedly reduced tyrosine phosphorylation of p34cdc2 in irradiated leukemic B-cell precursors, thereby preventing radiation-induced cell cycle arrest at the G2-M transition checkpoint. Thus, tyrosine phosphorylation is directly responsible for the inactivation of p34cdc2 in irradiated human leukemic B-cell precursors and activation of protein tyrosine kinases is a proximal and mandatory step in radiation-induced G2-arrest arrest at the G2-M checkpoint. Human WEE1 kinase isolated from unirradiated or irradiated leukemic B-cell precursors had minimal tyrosine kinase activity towards p34cdc2. We detected no increase of human WEE1 kinase activity after radiation of leukemic B-cell precursors, as measured by (a) autophosphorylation, (b) tyrosine phosphorylation of a synthetic peptide derived from the p34cdc2 amino-terminal region or (c) recombinant human p34cdc2-cyclin B complex. Thus the signaling pathway leading to inhibitory tyrosine phosphorylation of p34cdc2 and G2-arrest in irradiated human leukemic B-cell precursors functions independent of p49 WEE1 HU and enzymes which augment the tyrosine kinase activity of p49 WEE 1HU.

Periprosthetic microvasculature in loosening of total hip replacement

This study was performed to quantitate vascularity in periprosthetic tissues of loose total hip replacements (THRs), because most likely revascularization and endothelial cells are important for implant osseointegration and loosening. Interface and pseudocapsular tissue samples obtained from loose THRs were stained with an immunohistochemical labelling (ABC technique) for von Willebrand factor. Non-inflammatory synovial samples served as controls. The results were quantitated by morphometry using the Kontron image analysis system. Evaluation of the mean endothelial index (EI; positively stained area micron/mm2 of tissue) revealed that in the control samples synovium was better vascularized than was the case in the cellular areas of the periprosthetic pseudocapsule (P = 0.0008) and interface (P = 0.0004) of loose THRs. There was no significant difference between mean EI of cellular areas in the interface and that of the pseudocapsule (P = 0.24). In the interface the vascularity was irregular. Vascular injury and decreased blood supply seem to occur at the implant-host interface, which may be one of the reasons for insufficient implant osseointegration and loosening.

Studies on mu and delta opioid receptor selectivity utilizing chimeric and site-mutagenized receptors

Opioid receptors are members of the guanine nucleotide binding protein (G protein)-coupled receptor family. Three types of opioid receptors have been cloned and characterized and are referred to as the delta, kappa and mu types. Analysis of receptor chimeras and site-directed mutant receptors has provided a great deal of information about functionally important amino acid side chains that constitute the ligand-binding domains and G-protein-coupling domains of G-protein-coupled receptors. We have constructed delta/mu opioid receptor chimeras that were express in human embryonic kidney 293 cells in order to define receptor domains that are responsible for receptor type selectivity. All chimeric receptors and wild-type delta and mu opioid receptors displayed high-affinity binding of etorphine (an agonist), naloxone (an antagonist), and bremazocine (a mixed agonist/antagonist). In contrast, chimeras that lacked the putative first extracellular loop of the mu receptor did not bind the mu-selective peptide [D-Ala2,MePhe4,Gly5-ol]enkephalin (DAMGO). Chimeras that lacked the putative third extracellular loop of the delta receptor did not bind the delta-selective peptide, [D-Ser2,D-Leu5]enkephalin-Thr (DSLET). Point mutations in the putative third extracellular loop of the wild-type delta receptor that converted vicinal arginine residues to glutamine abolished DSLET binding while not affecting bremazocine, etorphine, and naltrindole binding. We conclude that amino acids in the putative first extracellular loop of the mu receptor are critical for high-affinity DAMGO binding and that arginine residues in the putative third extracellular loop of the delta receptor are important for high-affinity DSLET binding.