The inhibitory effect of antihyperlipidemic drugs on the growth of Chlamydia pneumoniae in vitro.
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Journal Article↗
Biomedical subjects
A Ohtake
Publications and source records attributed to A Ohtake.
Mutations of the mitochondrial ND1 gene as a cause of MELAS.
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Adolescent↗
Two cases with transient lipoprotein lipase (LPL) activity impairment: evidence for the possible involvement of an LPL inhibitor.
UNLABELLED: Two independent severe hypertriglyceridemic infants with transiently impaired lipoprotein lipase (LPL) activity were observed and the causes were explored. Both infants were female, born prematurely with low birth weight and developed hypertriglyceridemia (Fredrickson type V hyperlipidemia: high VLDL and low LDL/HDL) a few months after birth. While mass levels of their post-heparin plasma LPL and apoprotein C-II (apo C-II), a physiological activator of LPL, were normal, their post-heparin plasma LPL activities were remarkably impaired. Both of their mothers' post-heparin plasma LPL activities were slightly or moderately impaired as well, without a decrease in the LPL mass level. No mutations in the genes for LPL and apo C-II were detected in either patient. In an in vitro study with their serum at onset, we could not detect any distinct circulating inhibitors for LPL. There was no data supporting infection or autoimmune diseases, which might have an impact on LPL activity, during the follow-up period. Levels of their plasma triglyceride (TG) and total cholesterol (TC) were decreased quickly by a dietary intervention with medium-chain triglyceride (MCT) milk and kept normal even after stopping the intervention at around age 1 year. However, their low post-heparin LPL activity persisted and returned to normal at around age 2 years. Their low HDL cholesterol levels persisted even after recovery of the TG and TC levels, although lecithin:cholesterol acyltransferase (LCAT) and cholesterol-ester-transfer protein (CETP), two key enzymes of HDL metabolism, were normal throughout the course. The exact reasons why their post-heparin LPL activities were impaired for a certain period and why their HDL cholesterol levels have remained low are still unclear. CONCLUSION: Transiently impaired LPL activity with no defect in LPL enzyme induced severe hypertriglyceridemia in infants. The transient occurrence of inhibitor(s) for LPL was proposed.
Child↗
Extracellular carbohydrate-signal triggering cAMP-dependent protein kinase-dependent neuronal actin-reorganization.
Cell surface glycoconjugates are thought to mediate cell-cell recognition and to play roles in neuronal development and functions. We demonstrated here that exposure of neuronal cells to nanomolar levels of glyco-chains with an N-acetylgalactosamine (GalNAc) residue at the non-reducing termini (GalNAc-S) such as GalNAcbeta4(Neu5Acalpha3)Galbeta4GlcCer (GM2) ganglioside, its oligosaccharide portion, GalNAcbeta4Galbeta4GlcCer (Gg(3)) Cer, GalNAcalpha3GalNAcbeta3Galalpha4Galbeta4GlcCer (Gb(5)) Cer (Forssman hapten) and alpha1-4 linked oligomers of GalNAc, induced a rapid and transient activation of cAMP-dependent protein kinase (PKA) in subplasmalemma. The treatment was accompanied by peripheral actin polymerization and filopodia formation in NG108-15 cells and primary cultured hippocampal neurons, but not in glial cells. A cAMP-dependent protein kinase (PKA) selective inhibitor and an adenylate cyclase inhibitor blocked both PKA activation and the subsequent filopodia formation. A small GTPase cdc42 was a potential downstream target of GalNAc-S-activated PKA. These results suggest that extracellular GalNAc-S serve as potential regulators of the filopodia formation in neuronal cells by triggering the activation of PKA followed by cdc42 up-regulation via a cell surface receptor-like component. Filopodia formation induced by GalNAc-S may have a physiological relevance because long-term exposure to GalNAc-S enhanced F-actin-rich dendrite generation of primary cultured hippocampal neurons, and PKA-dependent dendritic outgrowth and branch formation of primary cultured cerebellar Purkinje neurons, in which actin isoforms were localized to motile structures in dendrites. These findings provide evidence for a novel GalNAc/PKA-signaling cascade in regulating some neuronal maturation.
Acetylgalactosamine↗
Tau-tubulin kinase phosphorylates tau at Ser-208 and Ser-210, sites found in paired helical filament-tau.
Hyperphosphorylated tau protein is known to be a major component of the paired helical filaments (PHFs) that accumulate in the brain of Alzheimer's patients. The kinase that phosphorylated Ser-208 and Ser-210 in PHF-tau had remained unknown. We used anti-pS208 and anti-pS210 antibodies and Western blots to confirm that the tau-tubulin kinase (TTK) phosphorylates tau at Ser-208 and at Ser-210. Using partial amino acid sequences of purified bovine brain TTK, a mouse cDNA of TTK was isolated and the sequence was determined. Its 963 bp coding region is composed of 320 amino acids and encodes a 36 kDa protein indistinguishable in size from authentic bovine brain TTK. Our immunoblot analysis demonstrated that TTK is ubiquitously distributed in the rat tissues, and that it is developmentally regulated in the rat brain.
Amino Acid Sequence↗
Role of Thr(11) in the binding of omega-conotoxin MVIIC to N-type Ca2+ channels.
As replacement of Thr(11) of omega-conotoxin MVIIC with Ala significantly reduced the affinity for both N- and P/Q-type calcium channels, we examined the effect of substitution at this position with other residues. Binding assays using rat cerebellar P2 membranes showed that the affinity is in the order of Leu>Val, aminobutyric acid, Thr>Asn&z.Gt;Ser, Ala, Asp, Phe, Tyr for N-type channels and Thr>Leu, Val, aminobutyric acid, Asn, Ser>Ala&z.Gt;Asp, Phe, Tyr for P/Q-type channels, suggesting that aliphatic amino acids with longer side chains are favorable for block of N-type channels. The effects of substitution were examined electrophysiologically in BHK cells expressing N-type Ca2+ channels. Inhibition of Ba2+ current by the analogs did not completely correlate with binding affinity, although binding to BHK cells was comparable to rat cerebellar membranes.
Alanine↗
A genetic factor for age-related cataract: identification and characterization of a novel galactokinase variant, "Osaka," in Asians.
Galactokinase (GALK) deficiency is an autosomal recessive disorder characterized by hypergalactosemia and cataract formation. Through mass screening of newborn infants, we identified a novel and prevalent GALK variant (designated here as the "Osaka" variant) associated with an A198V mutation in three infants with mild GALK deficiency. GALK activity and the amount of immunoreactive protein in the mutant were both 20% of normal construct in expression analysis. The K(m) values for galactose and ATP-Mg(2+) in erythrocytes with homozygous A198V were similar to those of the healthy adult control subjects. A population study for A198V revealed prevalences of 4.1% in Japanese and 2.8% in Koreans, lower incidence in Taiwanese and Chinese, no incidence in blacks and whites from the United States, and a significantly high frequency (7.8%; P < .023) in Japanese individuals with bilateral cataract. This variant probably originated in Japanese and Korean ancestors and is one of the genetic factors that causes cataract in elderly individuals.
Adult↗
Immune thrombocytopenia in an elderly patient treated successfully by pulse therapy with cyclophosphamide.
Thrombocytopenia due to immune mechanisms is rare and difficult to manage in elderly patients. We describe a case of an 89-year-old female with severe immune thrombocytopenia (ITP) who rapidly improved by pulse therapy with cyclophosphamide. She was admitted to our hospital because she had arthralgia in both sides of her femoral region since January 1999, aphthous stomatitis and ecchymosis of the leg since April 1999, and bloody phlegm in July 1999. On admission, her peripheral blood count revealed severe thrombocytopenia (0.1 x 10(4)/microl). Her megakaryocyte count from bone marrow was increased to 512/microl without abnormal cells. Systemic lupus erythematosus was suspected because of strong positive protein in the urine in addition to the clinical and hematological findings described above, but she was negative for all the autoantibodies examined. Finally, she was diagnosed as having ITP on the basis of high platelet associated immunoglobulin G in addition to hematological and physical findings and she was treated with prednisolone. It was difficult to maintain her platelet count with only prednisolone, but 600 mg of cyclophosphamide rapidly increased her platelet count in spite of tapering the prednisolone. In September 2000, her platelet count was kept within normal limits by administration of 15 mg/day of prednisolon. It is suggested that immunosuppressive therapy for ITP using high-dose cyclophosphamide is useful in elderly patients as well as in juvenile adult patients.
Aged↗
Pharmacological effect of tamsulosin in relation to dog plasma and tissue concentrations: prostatic and urethral retention possibly contributes to uroselectivity of tamsulosin.
In the present study the pharmacokinetics and pharmacodynamics of tamsulosin were investigated in anesthetized male dogs. Hypogastric nerve stimulation elevated the intraurethral pressure (IUP), which was inhibited dose dependently by intraduodenal administration of tamsulosin (3-30 microg/kg). The inhibition peaked about 90 min after dosing and lasted up to 240 min. The basal mean blood pressure did not change significantly during the observation period. The plasma, prostatic, and urethral concentrations of tamsulosin were determined by the liquid chromatography-mass spectrometry/mass spectrometry method. The plasma concentration reached the maximal level within 30 min after dosing and gradually declined thereafter. The maximal total plasma concentration of tamsulosin (C(max, t)) and its unbound concentration (C(max, u)) correlated with the maximal effect on IUP response [r(2) = 0.81 (p<0.01, n = 15) and r(2) = 0.84 (p<0.01, n = 15), respectively]. Each individual unbound plasma concentration did not correlate, however, with its associated inhibition of IUP response (r(2) = 0.04, n = 126). Although the plasma concentration of tamsulosin decreased nearly to the lower limit of quantitation 240 min after dosing, the prostatic and urethral concentrations remained high, i.e., 13 to 44 times greater than the plasma concentration. Our data demonstrate that the maximal inhibition by tamsulosin of IUP response is well correlated with the maximal plasma concentration in the early phase. The sustained effect of tamsulosin on IUP response that follows may be related to prostatic and urethral retention of tamsulosin.
Adrenergic alpha-Antagonists↗
lambda-conotoxins, a new family of conotoxins with unique disulfide pattern and protein folding. Isolation and characterization from the venom of Conus marmoreus.
Conotoxins are multiple disulfide-bonded peptides isolated from marine cone snail venom. These toxins have been classified into several families based on their disulfide pattern and biological properties. Here, we report a new family of Conus peptides, which have a novel cysteine motif. Three peptides of this family (CMrVIA, CMrVIB, and CMrX) have been purified from Conus marmoreus venom, and their structures have been determined. Their amino acid sequences are VCCGYK-LCHOC (CMrVIA), NGVCCGYKLCHOC (CMrVIB), and GICCGVSFCYOC (CMrX), where O represents 4-trans-hydroxyproline. Two of these peptides (CMrVIA and CMrX) have been chemically synthesized. Using a selective protection and deprotection strategy during disulfide bond formation, peptides with both feasible cysteine-pairing combinations were generated. The disulfide pattern (C(1)-C(4), C(2)-C(3)) in native toxins was identified by their co-elution with the synthetic disulfide-isomeric peptides on reverse-phase high pressure liquid chromatography. Although cysteine residues were found in comparable positions with those of alpha-conotoxins, these toxins exhibited a distinctly different disulfide bonding pattern; we have named this new family "lambda -conotoxins." CMrVIA and CMrX induced different biological effects when injected intra-cerebroventricularly in mice; CMrVIA induces seizures, whereas CMrX induces flaccid paralysis. The synthetic peptide with lambda-conotoxin folding is about 1150-fold more potent in inducing seizures than the mispaired isomer with alpha-conotoxin folding. Thus it appears that the unique disulfide pattern, and hence the "ribbon" conformation, in lambda-conotoxins is important for their biological activity.
Amino Acid Sequence↗
Strain relaxation in InAs/GaAs(111)A heteroepitaxy
We have studied strain-relaxation processes in InAs heteroepitaxy on GaAs(111)A using rocking-curve analysis of reflection high-energy electron diffraction. Strain relaxation in the direction parallel to the surface occurs at approximately 1.5 bilayers (BL) thickness. On the other hand, the lattice constant in the direction normal to the surface remains almost unchanged below approximately 3 BL thickness and is estimated to be approximately 3.3 A. This value, slightly larger than that of bulk GaAs (3.26 A), does not quite reach the value predicted by classical elastic theory, 3.64 A. The present result has been supported by the first-principles total-energy calculations.
Journal Article↗
Binding of Ala-scanning analogs of omega-conotoxin MVIIC to N- and P/Q-type calcium channels.
omega-Conotoxin MVIIC binds to P/Q-type calcium channels with high affinity and N-type channels with low affinity. To reveal the residues essential for subtype selectivity, we synthesized Ala-scanning analogs of MVIIC. Binding assays using rat cerebellar P(2) membranes suggested that Thr(11), Tyr(13) and Lys(2) are essential for binding to both N- and P/Q-type channels, whereas Lys(4) and Arg(22) are important for binding to P/Q-type channels. These results suggest that MVIIC interacts with P/Q-type channels via a large surface, in good agreement with previous observations using chimeric analogs.
Alanine↗
Binding of six chimeric analogs of omega-conotoxin MVIIA and MVIIC to N- and P/Q-type calcium channels.
Replacement of the N-terminal half of omega-conotoxin MVIIC, a peptide blocker of P/Q-type calcium channels, with that of omega-conotoxin MVIIA significantly increased the affinity for N-type calcium channels. To identify the residues essential for subtype selectivity, we examined single reverse mutations from MVIIA-type to MVIIC-type in this chimeric analog. A reverse mutation from Lys(7) to Pro(7) decreased the affinity for both P/Q- and N-type channels, whereas that from Leu(11) to Thr(11) increased the affinity for P/Q-type channels and decreased the affinity for N-type channels. The roles of these two residues were confirmed by synthesizing two MVIIC analogs in which Pro(7) and Thr(11) were replaced with Lys(7) and Leu(11), respectively.
Amino Acid Sequence↗
Familial Alzheimer's disease-associated mutations block translocation of full-length presenilin 1 to the nuclear envelope.
A polyclonal antibody, M5, to the hydrophilic loop domain of human presenilin 1 (PS1) was prepared. Western blot and immunoprecipitation analyses showed that M5 specifically recognized the processed C-terminal fragment, but not the full-length PS1. Epitope mapping analysis revealed that the essential sequence for recognition of the C-terminal fragment by M5 is DPEAQRR (302-308). The recognition of the C-terminal fragment by M5 in a processing-dependent manner was further confirmed by competitive enzyme-linked immunosorbent assay using the synthetic peptide L281 (281-311), which contains the putative processing site and the preceding amino acids to the site. Although L281 contains the epitope sequence for M5, the maximum inhibition was only 14%. Immunocytochemistry using M5 combined with hL312, which recognizes both full-length PS1 and the C-terminal fragment, allowed us to distinguish the localization of the processed C-terminal fragment from that of full-length PS1. Confocal microscopy demonstrated that the full-length form of wild-type PS1 is preferentially located in the nuclear envelope, while the processed C-terminal fragment is mainly present in the endoplasmic reticulum (ER). However, PS1 with familial Alzheimer's disease-associated mutations could not translocate to the nuclear envelope, and both the full-length and processed mutants were co-localized in the ER.
Alzheimer Disease↗
Chromosomal and extrachromosomal synthesis of exfoliative toxin from Staphylococcus hyicus.
Evidence for the existence of two molecular species of exfoliative toxin (ET) synthesized by Staphylococcus hyicus (SHET) under chromosomal and plasmid control is presented. Serological evidence that these molecular species of toxins are distinct from each other is given. The molecular weights of SHET from plasmidless strain P-1 (SHETA) and from plasmid-carrying strains P-10 and P-23 (SHETB) were almost equal. Both of the serotypes of SHET exhibited exfoliation in 1-day-old chickens. The plasmid-cured (P(-)) substrains (P-23C1 and P-23C2) of S. hyicus P-23 did not cause exfoliation in 1-day-old chickens, whereas P(-) substrains (P-10C1 and P-10C2) of strain P-10 caused exfoliation, but they decreased their exfoliative activity. These findings suggest that SHETB was synthesized along with SHETA by strain P-10, whereas the P-23 strain synthesized SHETB alone. The plasmid-carrying strain (P-23) as well as the plasmidless strain (P-1) exhibited the typical clinical signs of exudative epidermitis in pigs. However, plasmid-cured (P(-)) substrains of P-23 (P23C1 and P23C2) did not exhibit the typical clinical signs of exudative epidermitis. These findings suggest that SHETA is synthesized under chromosomal control and SHETB is synthesized under plasmid control and that SHET-producing strains can be divided into three groups: SHETA-producing strains, SHETB-producing strains, and strains producing both toxins.
Animals↗
Missense mutations in the gp91-phox gene encoding cytochrome b558 in patients with cytochrome b positive and negative X-linked chronic granulomatous disease.
Chronic granulomatous disease (CGD) is a disorder of host defense due to genetic defects of the superoxide (O2-) generating NADPH oxidase in phagocytes. A membrane-bound cytochrome b558, a heterodimer consisting of gp91-phox and p22-phox, is a critical component of the oxidase. The X-linked form of the disease is due to defects in the gp91-phox gene. We report here biochemical and genetic analyses of patients with typical and atypical X-linked CGD. Immunoblots showed that neutrophils from one patient had small amounts of p22-phox and gp91-phox and a low level of O2- forming oxidase activity, in contrast to the complete absence of both subunits in two patients with typical CGD. Using polymerase chain reactions (PCR) on cDNA and genomic DNA, we found novel missense mutations of gp91-phox in the two typical patients and a point mutation in the variant CGD, a characteristic common to two other patients with similar variant CGD reported previously. Spectrophotometric analysis of the neutrophils from the variant patient provided evidence for the presence of heme of cytochrome b558. Recently, we reported another variant CGD with similar amounts of both subunits, but without oxidase activity or the heme spectrum. A predicted mutation at amino acid 101 in gp91-phox was also confirmed in this variant CGD by PCR of the genomic DNA. These results on four patients, including those with two variant CGD, are discussed with respect to the missense mutated sites and the heme binding ligands in gp91-phox.
Adult↗
Characteristics of brain injury-derived neurotrophic peptide-binding sites on rat brain synaptosomes and neurons in culture.
Brain injury-derived neurotrophic peptide is the fragmental 13-mer peptide of the novel neurotrophic factor which was extracted and purified from Sponge Gelform made of gelatin implanted at the mechanically-induced injury site in neonatal rat brains. Brain injury-derived neurotrophic peptide supports survival of septal cholinergic and mesencephalic dopaminergic neurons in culture, and rescues hippocampal neurons in culture from glutamate neurotoxicity. Here we studied the binding characteristics of brain injury-derived neurotrophic peptide to synaptosomes from normal adult rat brains and neurons in culture from neonatal rat brains. [125I]Asp-[Tyr11]-brain injury-derived neurotrophic peptide binding to rat brain synaptosomes was specific and saturable. Equilibrium binding studies revealed that [125I]Asp-[Tyr11]-brain injury-derived neurotrophic peptide bound to 1.1 pmol/mg protein with a Kd (dissociation constant) of 0.17 microM in hippocampal synaptosomes and to 2.0 pmol/mg protein with a Kd of 0.38 microM in septal synaptosomes. [125I]Asp-[Tyr11]-brain injury-derived neurotrophic peptide could bind to a subpopulation of hippocampal neurons in culture from embryonic rat brains. Affinity cross-linking with the carboxyl-reactive cross-linking reagent 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide-HCl and [125I]Asp-[Tyr11]-brain injury-derived neurotrophic peptide produced radiolabeled bands corresponding to 100,000, 50,000 and 40,000 mol. wt molecules on hippocampal neurons in culture. These results suggest that the 13-mer sequence of brain injury-derived neurotrophic peptide plays a crucial role in expressing the neurotrophic properties of the factor.
Animals↗
Requirement for a different hydrophobic moiety and reliable chromogenic substrate for endo-type glycosylceramidases.
A series of synthetic lactosides with aglycones that differed in length and structure were used to determine the substrate specificity of endo-type glycosylceramidases. Endoglycoceramidases (EGCase) from bacteria preferred lactosides with an acylamide structure over simple n-alkyl lactosides. While ceramide glycanase (CGase) from leech did not show preference. N -Acylaminoethyl beta-lactosides and n -alkyl lactosides were substrates for both EGCase and CGase, but N-acylaminobutyl beta-lactosides, whose acylamide residue differs from that in ceramide, were not hydrolyzed by EGCases. Thus, EGCases, but not CGase, appear to require an N-acyl group at the same position as that of intact glycosphingolipid for substrate recognition. A p-nitrophenyl lactoside derivative possessing an N-acyl chain was degraded by both EGCases and CGase and this chromogenic substrate may be an alternative substrate for endo-type glycosylceramidase activity. Km of the chromogenic lactoside for CGase and Rhodococcus EGCase were 28 microM and 2.9 mM, respectively.
Chromogenic Compounds↗