Biomedical subjects

T Akino

Publications and source records attributed to T Akino.

At least 19 recordsLinked to original sources

PubMed2002

Parasitoid secretions provoke ant warfare.

Insect social parasites are extreme specialists that typically use mimicry or stealth to enter ant colonies to exploit the rich, but fiercely protected, resources within their nests. Here we show how a parasitic wasp (parasitoid) contrives to reach its host, itself an endangered species of social parasite that lives inside the brood chambers of ant nests, by releasing semiochemicals to induce in-fighting between worker ants, locking the colony in combat and leaving it underprotected. Four of these chemicals are new to biology and have the potential to control pest species by inducing different agonistic behaviours in ants.

Aggression↗

PubMed2001

Differential lipid specificities of the repeated domains of annexin IV.

The roles of the four domains of annexin IV in binding to phospholipids and glycolipids were assessed by analyzing the binding of a group of mutant annexins IV in which one or more of the four domains was inactivated by replacing a critical amino residue(s) (Asp or Glu) with the neutral residue Ala. The data reveal that individual annexin domains may have characteristic affinities for different lipids. In particular, inactivation of the fourth domain inhibits the binding to phosphatidylserine (PS) and phosphatidylinositol (PI) but not to phosphatidylglycerol (PG), suggesting that this domain specifically can accommodate the larger head groups of PS and PI whereas the other three domains may form more restricted binding pockets. In order to block binding to PG, domain 1, or both domains 2 and 3 must be inactivated in addition to domain 4, suggesting that all four domains may be able to accommodate the headgroup of PG to some extent. Binding to acidic glycolipids (sulfatides) was also sensitive to inactivation of domain 4. However, in the case of sulfatides the nature of the binding reaction is fundamentally different compared with the binding to phospholipids since the interaction with sulfatides was highly sensitive to an increase in ionic strength. The binding to sulfatides may depend therefore on charge-charge interactions whereas the binding to phospholipid may involve a more specific interaction between the lipid headgroup and the protein surface, and/or interaction of the protein with the hydrophobic portion of a lipid bilayer.

Alanine↗

PubMed2001

Binding of annexins to lung lamellar bodies and the PMA-stimulated secretion of annexin V from alveolar type II cells.

To identify lung lamellar body (LB)-binding proteins, the fractions binding to LB-Sepharose 4B in a Ca(2+)-dependent manner from the lung soluble fractions were analyzed with Mono Q column. Four annexins (annexins III, IV, V, and VIII) were identified by partial amino acid sequence analyses as the LB-binding proteins in the lung soluble fractions. A control experiment using phospholipid (phosphatidylserine/phosphatidylglycerol/phosphtidylcholine) liposome-Sepharose 4B revealed that annexins III, IV and V were the Ca(2+)-dependent proteins binding to the column in the lung soluble fractions, while annexin VIII was not detected. Thus, annexin VIII might preferentially bind to LB. On the other hand, the only Ca(2+)-dependent LB-binding protein identified in the bronchoalveolar lavage fluids was annexin V. It was further demonstrated that annexin V was secreted by isolated alveolar type II cells from rats and that the secretion was stimulated by the addition of phorbol ester (PMA), a potent stimulator of surfactant secretion. The PMA-dependent stimulation of annexin V was attenuated by preincubation with surfactant protein-A (SP-A), a potent inhibitor of surfactant secretion. As LB is thought to be an intracellular store of pulmonary surfactant, which is secreted by alveolar type II cells, annexin V is likely to be secreted together with the lamellar body.

Animals↗

PubMed2000

Importance of the carboxy-terminal 25 amino acid residues of lung collectins in interactions with lipids and alveolar type II cells.

Surfactant proteins A and D (SP-A and SP-D) are structurally related members of the collectin family found in the alveolar compartment of the lung. SP-A binds dipalmitoylphosphatidylcholine (DPPC) and galactosylceramide (GalCer), induces liposome aggregation, and regulates the uptake and secretion of surfactant lipids by alveolar type II cells in vitro. SP-D binds phosphatidylinositol (PI) and glucosylceramide. The purpose of this study was to identify a critical stretch of primary sequence in the SP-A region Cys(204)-Phe(228) and the SP-D region Cys(331)-Phe(355) that is involved in protein-specific lipid and type II cell interactions. Chimeras ad1 and ad2 were constructed with rat SP-A/SP-D splice junctions at Cys(218)/Gly(346) and Lys(203)/Cys(331), respectively. Chimera ad1 but not ad2 retained DPPC liposome binding activity. Both chimeras retained significant binding to GalCer liposomes. Chimera ad1 did not bind to PI, whereas chimera ad2 acquired a significant PI binding. Both chimeras failed to induce liposome aggregation and to interact with alveolar type II cells. In addition, monoclonal antibody 1D6 that blocks specific SP-A functions did not recognize either chimera. From these results, we conclude that (1) the SP-A region Leu(219)-Phe(228) is required for liposome aggregation and interaction with alveolar type II cells, (2) the SP-A region Cys(204)-Cys(218) is required for DPPC binding, (3) the SP-D region Cys(331)-Phe(355) is essential for minimal PI binding, and (4) the epitope for mAb 1D6 is located at the region contiguous to the SP-A region Leu(219)-Phe(228).

1,2-Dipalmitoylphosphatidylcholine↗

PubMed2000

Elevation of carboxyl methylation activity on GTP-binding protein gamma-subunit in synovial tissues from rheumatoid arthritis: how does elevation of the methylation relate to the signal transduction system of rheumatoid arthritis?

We examined guanosine triphosphate (GTP)-binding proteins (G-proteins) in synovial tissues obtained from patients with rheumatoid arthritis or osteoarthritis. The results of immunoblot analysis with anti-bovine G-protein betagamma-subunit antibody in the rheumatoid synovial tissue were similar to those in the osteoarthritis synovial tissue. On the other hand, the carboxyl methylation activity on G-protein gamma-subunit in the rheumatoid synovial tissue was enhanced compared with that in the osteoarthritis synovial tissues: Km and Vm values were 2.6 microM and 10 pmol/mg x min, respectively, for the rheumatoid arthritis, and 4.8 microM and 5.6 pmol/mg x min, respectively, for the osteoarthritis. These results suggest that G-protein-linked signal transduction, in reference to carboxyl methylation of the gamma-subunit, is affected in rheumatoid tissues.

Arthritis, Rheumatoid↗

PubMed1999

Characterization of the Ca2+-dependent binding of annexin IV to surfactant protein A.

We have shown previously that surfactant protein A (SP-A) binds to annexin IV in a Ca2+-dependent manner [Sohma, Matsushima, Watanabe, Hattori, Kuroki and Akino (1995) Biochem. J. 312, 175-181]. Annexin IV is a member of the annexin family having four consensus repeats of about 70 amino acids and a unique N-terminal tail. In the present study, the functional site of both annexin IV and SP-A for the Ca2+-dependent binding was investigated using mutant proteins. SP-A bound in a Ca2+-dependent manner to an annexin-IV truncation mutant consisting of the N-terminal domain and the first three domains (T(N-1-2-3)). SP-A also bound to T3-4, but this interaction was not Ca2+-dependent. SP-A bound weakly to the other truncation mutants (T(N-1-2), T(2-3) and T(2-3-4)). Each consensus repeat of annexin IV possesses a conserved acidic amino acid residue (Glu70, Asp142, Glu226 and Asp301) that putatively ligates Ca2+. Using annexin-IV DE mutants in which one, two or three residues out of the four Asp/Glu were altered to Ala by site-directed mutagenesis [Nelson and Creutz (1995) Biochemistry 34, 3121-3132], it was revealed that Ca2+ binding in the third domain is more important than in the other Ca2+-binding sites. SP-A is a member of the animal lectin group homologous with mannose-binding protein A. The substitution of Arg197 of rat SP-A with Asp or Asn eliminated binding to annexin IV, whereas the substitution of Glu195 with Gln was silent. These results suggest that the Ca2+ binding to domain 3 of annexin IV is required for the Ca2+-dependent binding by SP-A and that Arg197 of SP-A is important in this binding.

Animals↗

PubMed1999

Introduction of mannose binding protein-type phosphatidylinositol recognition into pulmonary surfactant protein A.

Pulmonary surfactant protein A (SP-A) and mannose-binding protein A (MBP-A) are collectins in the C-type lectin superfamily. These collectins exhibit unique lipid binding properties. SP-A binds to dipalmitoyl phosphatidylcholine (DPPC) and galactosylceramide (GalCer) and MBP-A binds to phosphatidylinositol (PI). SP-A also interacts with alveolar type II cells. Monoclonal antibodies (mAbs PE10 and PC6) that recognize human SP-A inhibit the interactions of SP-A with lipids and alveolar type II cells. We mapped the epitopes for anti-human SP-A mAbs by a phage display peptide library. Phage selected by mAbs displayed the consensus peptide sequences that are nearly identical to 184TPVNYTNWYRG194 of human SP-A. The synthetic peptide GTPVNYTNWYRG completely blocked the binding of mAbs to human SP-A. Chimeric proteins were generated in which the rat SP-A region Thr174-Gly194 or the human SP-A region Ser174-Gly194 was replaced with the MBP-A region Thr164-Asp184 (rat ama4 or hu ama4, respectively). The mAbs failed to bind hu ama4. Rat ama4 bound to an affinity matrix on mannose-sepharose but lost all of the SP-A functions except carbohydrate binding and Ca2+-independent GalCer binding. Strikingly, the rat ama4 chimera acquired the PI binding property that MBP-A exhibits. This study demonstrates that the amino acid residues 174-194 of SP-A and the corresponding region of MBP-A are critical for SP-A-type II cell interaction and Ca2+-dependent lipid binding of collectins.

Animals↗

PubMed1999

Antigenicity of the carbohydrate moiety of ganglioside GM3 having 3-O-acetyl ceramide.

To elucidate the effect of a modification of ceramide on antigenicity of the carbohydrate of ganglioside, the reactivity of O-acetyl GM3 having 3-O-acetyl ceramide, which has been characterized as a glioma-related ganglioside, with monoclonal antibody M2590 was examined in comparison to that of non-acetylated GM3, by means of quantitative enzyme-linked immunosorbent assay, TLC-immunostaining and liposome immune lysis assay. In all these assay systems, O-acetyl GM3 showed less activity than GM3 as follows: GM3 was detected till 0.1 nmol in TLC-immunostaining, whereas O-acetyl GM3 could not be detected even at 0.25 nmol; the GM3 reaction was approximately twofold that of O-acetyl GM3 at each diluted point in the enzyme-linked immunosorbent assay; and 20% of the liposomes containing GM3 were lysed at 6 mol%, while liposomes containing O-acetyl GM3 did not lyse at that concentration. The lesser antigenicity of the sugar moiety of O-acetyl GM3 could be ascribed to the presence of an acetyl group in the ceramide at the 3-position of sphingosine.

Ceramides↗

PubMed1999

Experimental neonatal respiratory failure induced by lysophosphatidylcholine: effect of surfactant treatment.

The purpose of this study was to characterize the toxic effects of lysophosphatidylcholine (lyso-PC) on neonatal lung function. Various doses of lyso-PC (from 0 to 40 mg/kg) were administered to near-term newborn rabbits. Lung-thorax compliance during mechanical ventilation was significantly decreased by doses >/=10 mg/kg, and static lung volumes during deflation were decreased by doses >/=20 mg/kg. Using the same experimental model, we investigated the effects of modified porcine surfactant (Curosurf, 200 mg/kg). Animals exposed to lyso-PC at birth and treated simultaneously with surfactant showed a satisfactory therapeutic response, whereas those treated after 30 min failed to respond. These animals also had a much larger leak of albumin into the air spaces and an elevated minimum surface tension of the lavage fluid in a pulsating bubble surfactometer, suggesting inactivation of the exogenous surfactant. Timing of surfactant administration may thus be essential for the therapeutic effect in this experimental model of acute lung injury.

Acute Disease↗

PubMed1999

Serial changes in surfactant-associated proteins in lung and serum before and after onset of ARDS.

The goal of this study was to determine the changes that occur in surfactant-associated proteins in bronchoalveolar lavage fluid (BAL) and serum of patients at risk for ARDS and during the course of ARDS. We found that the concentrations of SP-A and SP-B were low in the BAL of patients at risk for ARDS before the onset of clinically defined lung injury, whereas the concentration of SP-D was normal. In patients with established ARDS, BAL SP-A and SP-B concentrations were low during the entire 14-d observation period, but the median SP-D concentrations remained in the normal range. Immunoreactive SP-A and SP-D were not increased in the serum of patients at risk for ARDS, but both increased after the onset of ARDS to a maximum on Day 3 and remained elevated for as long as 14 d. The BAL SP-A concentrations were significantly lower in at-risk patients who developed ARDS, and no patient with a BAL SP-A concentration greater than 1.2 microg/ml developed ARDS. On Days 1 and 3 of ARDS, the BAL SP-D concentration was significantly lower in patients who died, and the BAL SP-D concentration was significantly related to the PI(O(2))/FI(O(2)) ratio. Thus, surfactant protein abnormalities occur before and after the onset of ARDS, and the responses of SP-A, SP-B, and SP-D differ in important ways. The BAL SP-A and SP-D measurements can be used to classify patients as high or low risk for progression to ARDS and/or death after the onset of ARDS. Strategies to increase these surfactant proteins in the lungs of patients with ARDS could be useful to modify the onset or the course of ARDS.

APACHE↗

PubMed1999

Purification and biochemical characterization of pulmonary surfactant protein A of horses.

OBJECTIVE: To characterize surfactant protein isolated from bronchoalveolar lavage fluids of healthy horses. ANIMALS: 10 Thoroughbreds (5 males, 5 females; 26 to 40 months old) that did not have a history or clinical signs of respiratory tract disease. PROCEDURE: Bronchoalveolar lavage fluid (BALF) was obtained and centrifuged at 33,000 X g. Lipid was removed from precipitated fractions by means of extraction with 1-butanol, and organic solvent-insoluble protein precipitates were dialyzed against Tris buffer. The suspension was centrifuged, and supernatant was placed in a mannose-Sepharose affinity column, with calcium. The bound protein fraction was analyzed by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, western immunoblot analysis, and amino acid sequencing. A liposome-aggregation assay was also performed, using purified proteins. RESULTS: Protein isolated by use of mannose-affinity matrices was identified as surfactant protein A (SP-A). It had carbohydrate-binding and phospholipid-aggregation properties characteristic of SP-A isolated from other animal species. The partial primary sequence of the isolated protein had high homology with rat and human SP-A. Furthermore, the equine SP-A reacted with anti-human and anti-rat SP-A specific antibodies. CONCLUSION: Analysis of these findings indicated the existence of SP-A in pulmonary tissues of horses. CLINICAL RELEVANCE: Measurement of SP-A concentrations may be useful for clinicians evaluating pulmonary disease of horses.

Amidohydrolases↗

PubMed1999

Purification and biochemical characterization of equine pulmonary surfactant protein D.

OBJECTIVE: To characterize surfactant protein D (SP-D) isolated from bronchoalveolar lavage fluid (BALF) of healthy horses. SAMPLE POPULATION: BALF from 10 Thoroughbreds (5 males, 5 females; 26 to 40 months old) without history or clinical signs of respiratory tract disease. PROCEDURE: BALF was obtained and centrifuged at 33,000 X g. The supernatant was applied to a mannose-Sepharose 6B affinity column in the presence of calcium, and the bound protein fraction was analyzed by use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblot analysis; amino acid composition was determined and partial sequencing was done. Phospholipid binding and liposome aggregation assay were performed, using purified proteins. RESULTS: The protein isolated by use of mannose affinity matrices was SP-D. It bound carbohydrates and phosphatidylinositol, which are the characteristic features of SP-D isolated from other animal species. Amino acid analysis and partial primary sequence of the isolated protein indicated high homology with rat and human SP-D. Furthermore, immunoblot analysis indicated that equine SP-D reacted with human and rat SP-D-specific antibodies. CONCLUSION AND CLINICAL RELEVANCE: SP-D exists in equine lungs; its measurement may be useful in evaluating equine lung disease.

Amino Acids↗

PubMed1999

Novel plasmalogalactosylalkylglycerol from equine brain.

A novel galactosylalkylglycerol modified with a long-chain cyclic acetal at the sugar moiety, 3-O-(4'6'-plasmalogalactosyl) 1-O-alkylglycerol, was isolated from equine brain. The presence of cyclic acetal linkage, its linked position, and the length of the acetal chain of the natural plasmalo lipid were determined by proton NMR spectroscopy and fast-atom bombardment;-mass spectrometry, as well as gas chromatography;-mass spectrometry and gas;-liquid chromatography. To identify the isomeric stereostructure of the natural product, the plasmalo derivative was chemically synthesized from 3-O-galactosyl 2-O-acyl 1-O-alkyl glyceride through acetalization after deacylation. As a result, the direction and position of the acetal chain of the natural plasmalo lipid were characterized as an "endo"-type 4',6'-O-acetal derivative linked to galactoside by comparison with the NMR data of the synthesized product. The chain lengths of alkyl and acetal groups were C(14) for the former and C(16) and C(18) for the latter, and those for the latter group were mostly similar to those of plasmalogalactosyl ceramide, which was previously isolated from equine brain.

Animals↗

PubMed1998

Surfactant proteins A and D: disease markers.

The abundant and restricted expression of surfactant proteins SP-A and SP-D within the lung makes these collectins specific markers for lung diseases. The measurement of SP-A and SP-D in amniotic fluids and tracheal aspirates reflects lung maturity and the production level of the lung surfactant in infants with respiratory distress syndrome (RDS). The SP-A concentrations in bronchoalveolar lavage (BAL) fluids are significantly decreased in patients with acute respiratory distress syndrome (ARDS) and also in patients at risk to develop ARDS. The prominent increase of these proteins in BAL fluids and sputum is diagnostic for pulmonary alveolar proteinosis (PAP). The concentrations of SP-A and SP-D in BAL fluids from patients with idiopathic pulmonary fibrosis (IPF) and interstitial pneumonia with collagen vascular diseases (IPCD) are rather lower than those in healthy controls and the SP-A/phospholipid ratio may be a useful marker of survival prediction. SP-A and SP-D appear in the circulation in specific lung diseases. Their serum concentrations significantly increase in patients with PAP, IPF and IPCD. The successive monitoring of serum levels of SP-A and SP-D may predict the disease activity. The serum SP-A levels increase in patients with ARDS. SP-A is also a marker for lung adenocarcinomas and can be used to differentiate lung adenocarcinomas from other types and metastatic cancers from other origins, and to detect metastasis of lung adenocarcinomas.

Enzyme-Linked Immunosorbent Assay↗

PubMed1998

New blocking method for the hydroxyl group on carbohydrate. Determination of the O-acylated position of the modified glycolipid.

To determine O-esterified positions, a rapid and complete acetalization to prepare an intermediate was established using ethyl vinyl ether as a new reagent. The new method was applied to O-esterified glycolipids followed by GC-MS analysis of the monosaccharide derivatives after methylation and methanolysis, revealing the derivatives with correctly substituted positions. This method was superior in terms of its shorter reaction time and complete acetalization, particularly of the N-glycolyl hydroxyl residue, to previously reported methods using methyl vinyl ether.

Acetylation↗

PubMed1998

Characterization of a O-fatty-acylated sulfatide from equine brain.

A sulfatide, O-fatty-acylated 3-sulfogalactosylceramide at C6-O on galactoside, was isolated from equine brain and the chemical structure was characterized by proton NMR and MS. The O-acylation site of the acylated sulfatide was determined by the down-field shift of protons attached to a carbon having an O-acyl group in the NMR spectrum and by analysis of a partially methylated derivative before and after acetalization of the intact sulfatide using GC-MS. The O-acyl chain length was determined by GLC, revealing that it exclusively had palmitoyl and stearoyl residues as the major fatty acids. The enzymatic conversion to the O-acyl sulfatide was further examined using equine brain microsomes as an enzyme source and different lipid substrates, resulting in O-acylation of 3-sulfogalactosylceramide from stearoyl CoA, while 6-O-acyl galactosylceramide was not O-sulfated from phosphoadenosine phosphosulfate. The results were supported by the comparably different N-linked fatty acid components between two lipid substrates, in which the component of 6-O-acyl sulfatide was mostly similar to that of sulfatide, but not to 6-O-acyl galactosylceramide.

Acylation↗

PubMed1998

Analysis of chimeric proteins identifies the regions in the carbohydrate recognition domains of rat lung collectins that are essential for interactions with phospholipids, glycolipids, and alveolar type II cells.

Pulmonary surfactant proteins A (SP-A) and D (SP-D) are collectins in the C-type lectin superfamily. SP-A binds to dipalmitoylphosphatidylcholine and galactosylceramide, and it regulates the uptake and secretion of surfactant lipids by alveolar type II cells. In contrast, SP-D binds to phosphatidylinositol (PI) and glucosylceramide (GlcCer). We investigated the functional region in the carbohydrate recognition domain of rat SP-A and SP-D that is involved in binding lipids and interacting with alveolar type II cells by using chimeric proteins. Chimeras ad3, ad4, and ad5 were constructed with SP-A/SP-D splice junctions at Gly194/Glu321, Gln173/Thr300, and Met134/Cys261, respectively. All three chimeras lost SP-A-specific functions. Chimeras ad3, ad4, and ad5 bound to PI with increasing activity. In contrast, chimeras ad3 and ad4 did not bind to GlcCer, whereas ad5 avidly bound this lipid. From these results, we conclude that 1) the SP-A region of Glu195-Phe228 is required for lipid and type II cell interactions, 2) the SP-D region of Cys261-Phe355 is required for optimal lipid interactions, and 3) the structural requirement for the binding of SP-D to PI is different from that for GlcCer.

Animals↗

PubMed1998

BAL surfactant protein A and Clara cell 10-kDa protein levels in healthy subjects.

Lung surfactant protein A (SP-A) and Clara cell 10-kDa protein (CC10) are the most abundant proteins produced locally in the lower respiratory tract, as assessed in bronchoalveolar lavage (BAL) analysis. However, it is not known what factors influence SP-A and CC10 levels in BAL fluids, and the relationship between SP-A and CC10 levels in BAL fluids has been unclear. We measured SP-A and CC10 concentrations in BAL fluids from 11 healthy nonsmokers and 12 healthy smokers by enzyme-linked immunosorbent assays using specific antibodies. Mean SP-A and CC10 levels in BAL fluids of healthy smokers were significantly lower than those of healthy nonsmokers. SP-A values correlated significantly with CC10 and phospholipid values in BAL fluids. On BAL examinations using three 50-ml aliquots, the mean SP-A level in the second lavage was 2.0-fold and 2.4-fold, respectively, of that in the first and third lavages, and the mean CC10 level in the first lavage was 5.0-fold and 5.6-fold, respectively, of that in the second and third lavages. We conclude that BAL fluid SP-A and CC10 levels are influenced by the BAL methods and by cigarette smoking. There is a significant positive correlation between SP-A and CC10 values in BAL fluids of healthy subjects.

Adult↗