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Biomedical subjects

N Maki

Publications and source records attributed to N Maki.

52 records · Page 3Linked to original sources
PubMed1991

Molecular cloning of a novel isolate of feline immunodeficiency virus biologically and genetically different from the original U.S. isolate.

The Japanese isolate (TM1 strain) of feline immunodeficiency virus (FIV) which replicates in a feline CD4 (fCD4)-positive lymphoblastoid cell line (MYA-1 cells) was molecularly cloned from extrachromosomal closed circular DNA. The restriction map of the clone, termed pFTM 191 complete genome (CG), showed a considerable difference from that of the U.S. isolate (Petaluma strain) of FIV. The sequence homology in the long terminal repeat between the TM1 and Petaluma strain was 82%. The pFTM 191 CG was biologically active after transfection into Crandell feline kidney cells which were permissive for replication of FIV Petaluma. However, the progeny virions could not reinfect fCD4-negative Crandell feline kidney cells but could infect fCD4-positive MYA-1 cells. When a specific-pathogen-free cat was inoculated with the virus derived from the pFTM 191 CG, the cat seroconverted within 8 weeks postinoculation and FIV was reisolated at 4, 8, and 20 weeks postinoculation. These results indicate the infectivity of the pFTM 191 CG in vivo.

Animals↗
PubMed1991

Identification of feline immunodeficiency virus rev gene activity.

We constructed 16 deletion mutants from an infectious molecular clone of feline immunodeficiency virus (FIV) and a reporter plasmid carrying the bacterial chloramphenicol acetyltransferase (CAT) gene to identify the rev transactivator activity of the virus. Cotransfections of various mutants and the rev reporter clone bearing a portion of FIV env in addition to the CAT gene revealed that the sequence important for the augmentation of CAT production was located in three separate parts of the virus genome. This enhancement was FIV specific in that the human retrovirus rev and rex gene products did not activate the reporter. The phenotypic properties of an FIV proviral mutant containing a small deletion in the genome were similar to those of rev mutants derived from primate immunodeficiency viruses. These results indicate that FIV, like the other lentiviruses, contains the rev gene in its genome.

Animals↗
PubMed1990

Complementary DNA encoding the human T-cell FK506-binding protein, a peptidylprolyl cis-trans isomerase distinct from cyclophilin.

The recently discovered macrolide FK506 has been demonstrated to have potent immunosuppressive activity at concentrations 100-fold lower than cyclosporin A, a cyclic undecapeptide that is used to prevent rejection after transplantation of bone marrow and organs, such as kidney, heart, and liver. After the recent discovery that the cyclosporin A-binding protein cyclophilin is identical to peptidylprolyl cis-trans isomerase, a cellular binding protein for FK506 was found to be distinct from cyclophilin but to have the same enzymatic activity. In this study, we isolated a cDNA coding for FK506-binding protein (FKBP) from human peripheral blood T cells by using mixed 20-mer oligonucleotide probes synthesized on the basis of the sequence, Glu-Asp-Gly-Lys-Lys-Phe-Asp, reported for bovine FKBP. The DNA isolated contained an open reading frame encoding 108 amino acid residues. The first 40 residues of the deduced amino acid sequence were identical to those of the reported amino-terminal sequence of bovine FKBP, indicating that the DNA sequence isolated represents the gene coding for FKBP. Computer-assisted analysis of the deduced amino acid sequence indicates that FKBP exhibits no internal homology and does not have significant sequence similarity to any other amino acid sequences of known proteins, including cyclophilin. This result suggests that two catalytically similar proteins, cyclophilin and FKBP, evolved independently. In Northern blot analysis, mRNA species of approximately 1.8 kilobases that hybridized with human FKBP cDNA were detected in poly(A)+ RNAs from brain, lung, liver, and placental cells and leukocytes. Induction of Jurkat leukemic T cells with phorbol 12-myristate 13-acetate and ionomycin did not affect the level of FKBP mRNA. Southern blot analysis of human genomic DNA digested with different restriction enzymes suggests the existence of only a few copies of the DNA sequence encoding FKBP. This is in contrast to the result that as many as 20 copies of the cyclophilin gene and possible pseudogenes may be present in the mammalian genome.

Amino Acid Isomerases↗
PubMed1989

Sequence of a novel simian immunodeficiency virus from a wild-caught African mandrill.

Since the isolation of an HIV-2-related virus from captive macaques (SIVMAC), the origin of human immunodeficiency viruses, a much debated subject, has been attributed to monkeys. The sequence of SIVAGM, which is derived from a naturally infected African green monkey, shows equal relatedness to HIV-1 and HIV-2, suggesting that the derivation of these viruses from SIVAGM is unlikely. Recent sequence analysis of SIV from a captive sooty mangabey (SIVMAC), however, shows its close relatedness to HIV-2 and SIVMAC, indicating a possible origin of HIV-2 and SIVMAC from SIVSM (refs 4, 7, 9). We report here the sequence of a novel simian lentivirus, SIVMND, isolated from a wild-caught mandrill in Africa. It is distinct from the three other main groups, HIV-1, HIV-2/SIVMAC/SIVSM and SIVAGM, and therefore represents a fourth main group of primate lentiviruses. Phylogenetic analysis indicates that these four main virus groups might have diverged from a common ancestor at about the same time, long before the spread of AIDS in humans.

Animals↗
PubMed1989

Genomic divergence of HIV-2 from Ghana.

Genetic variability in human immunodeficiency virus type 1 (HIV-1) has been studied extensively, but the total nucleotide sequence of the HIV-2 genome has been reported only in two strains. For phylogenetic analyses of HIV, the genetic variability of HIV-2 should be investigated. This paper reports the complete nucleotide sequence of an HIV-2 isolate from Ghana, HIV-2[GH-1]. This virus showed approximately 85% homology in overall nucleotide sequence with HIV-2ROD. The amino acid sequence of the gag and pol proteins of HIV-2[GH-1] showed 90% homology with those of HIV-2ROD, but its env gene and central regions were highly variable (more than 20% divergence in amino acids), indicating the presence of extensive genetic heterogeneity in HIV-2. However, the sequences with specific functions were relatively well conserved in these HIV-2 isolates.

Amino Acid Sequence↗
PubMed1988

Platelet-activating factor induces glycogen degradation in fetal rabbit lung in utero.

The role of platelet-activating factor (PAF, 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine) in initiating glycogen breakdown in the fetal rabbit lung was assessed by intraperitoneal administration of this potent ether-linked glycerophospholipid. Forty-five min after in utero injection of PAF (2.5 X 10(-7) mol), fetal pulmonary and hepatic glycogen concentrations were reduced from 326 to 256 and from 9.8 to 6.6 micrograms of glycogen/mg protein, respectively. Glycolytic activity was similarly increased as judged by an elevation of lactate (2-fold) in lung, liver, and plasma upon PAF injection. These actions of PAF were dose- and time-dependent. The glycogenolytic response did not occur when an equimolar dose of the inactive enantiomer, D-PAF was injected. Pretreatment of the fetus with a specific PAF receptor antagonist, SRI-63-441, prevented the PAF response. We have previously demonstrated (Hoffman, D. R., Truong, C. T., and Johnston, J. M. (1986) Biochim. Biophys. Acta 879, 88-96) that PAF biosynthesis and PAF concentrations increase significantly on day 24 of fetal rabbit lung development. A concurrent decrease in pulmonary glycogen concentration at this point of gestation is potentially reflective of the PAF-induced action. Thus, these observations would suggest a role for PAF in the normal physiology of fetal lung maturation.

Animals↗
PubMed1988

Platelet-activating factor acetylhydrolase activity in maternal, fetal, and newborn rabbit plasma during pregnancy and lactation.

The inactivation of the biologically active ether-containing glycerophospholipid platelet-activating factor (PAF) is catalyzed by the enzyme PAF acetylhydrolase (1-alkyl-2-acetyl-sn-glycero-3-phosphocholine acetylhydrolase, EC 3.1.1.48). The specific activity of acetylhydrolase has been assayed in maternal rabbit plasma prior to and throughout pregnancy and after parturition. The specific activity of acetylhydrolase was 131 +/- 8 nmol.min-1.ml-1 of plasma (mean +/- SEM) in the nonpregnant rabbit. Similar specific activities were found throughout the first half of pregnancy; however, on day 15 the acetylhydrolase activity began to decrease and reached a minimum around day 27. Within 24-48 hr following delivery, the specific activity of the enzyme increased to the levels found in the nonpregnant animals. The specific activity of acetylhydrolase in fetuses (gestational ages of 21-30 days) and neonates increased from 22 nmol.min-1.ml-1 of plasma (21-day-old) to 328 nmol.min-1.ml-1 of plasma (35-day-old rabbits). The decrease in enzymatic activity of the pregnant rabbit plasma cannot be accounted for by the presence of an inhibitor as determined by plasma-mixing experiments with nonpregnant and pregnant (27-day) plasma. The properties of this enzyme in the rabbit were consistent with those reported by others, i.e., substrate specificity, inactivation by heat and various inhibitors, and Ca2+ independency. The activity of PAF acetylhydrolase was associated primarily with the high density lipoprotein fraction in rabbit plasma. The decrease of this enzymatic activity during pregnancy may serve to remove the protective effect on myometrium to allow an increased amount of PAF to come in contact with this tissue.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1985

Cloning and structural analysis of a part of the human epidermal growth factor receptor gene.

We screened a gene library constructed with human leukocyte chromosomal DNA fragments with an oligonucleotide probe complementary to the middle part of the cDNA for the human epidermal growth factor receptor. One of the genomic DNA clones obtained contains an insert of 36 kilobase pairs encoding 54% of the mature receptor protein. From the sequencing experiments, we were able to locate the exact site of the gene rearrangement, which had been previously suggested in some epidermoid carcinoma cell lines, in the intron preceding the exon coding for the hydrophobic transmembrane domain. Such a rearrangement must result in the removal of an authentic splicing acceptor site and the separation of the 3'-segment of the receptor gene which could encode a polypeptide homologous to the v-erb-B oncogene product responsible for chicken carcinogenesis.

Base Sequence↗
PubMedDate not supplied

Purification and characterization of a protease degrading 30 kDa yolk proteins of the silkworm, Bombyx mori.

The second major yolk proteins, 30 kDa proteins (30kPs) of the silkworm, Bombyx mori, which have been provided during oogenesis, are kept continuously unused during embryogenesis and are utilized just before larval hatching. The crude extracts of newly hatched larvae cleaved 30kPs in an in vitro incubation system. A protease was highly purified from newly hatched larvae using ammonium sulfate precipitation, gel filtration and ionic exchange chromatography, and non-denaturing-polyacrylamide gel electrophoresis (ND-PAGE). The protease shared the NH2-terminal amino acid sequence conserved in many serine proteases, and the apparent molecular mass was estimated to be approximately 600 kDa by gel filtration column chromatography. The enzymatic activity was strongly inhibited by elastatinal and diisopropyl fluorophosphate (DFP), indicating that this protease is an elastase-like serine protease. The protease selectively hydrolysed 30kP-1 and 30kP-4 between Ser6 and Ala7, but could not attack other 30kPs such as 30kP-2, 30kP-3 and 30kP-5. Consequently, the protease characterized in the present study is a unique protease which may be specialized for the selective degradation of yolk proteins in silkworm eggs.

Amino Acid Sequence↗
PubMedDate not supplied

The validity of the MMSE and SMQ as screening tests for dementia in the elderly general population-- a study of one rural community in Japan.

OBJECTIVE: To compare the validity of the Mini Mental State Examination (MMSE) and the Short-Memory Questionnaire (SMQ) as screening tests to detect dementia in the elderly general population. SUBJECTS: Six hundred and sixty-two subjects and their informants from the elderly general population sample who had completed these tests. SETTING: One rural community survey in Japan. METHOD: We used receiver-operating characteristic analysis to compare the performance of the MMSE and the SMQ with the clinical diagnosis of dementia according to DSM-III-R. RESULTS: The areas under the receiver-operating characteristic curve of the MMSE and the SMQ were 0.980 (SE = 0.006) and 0.982 (SE = 0.008), respectively. This differed from chance to a highly significant degree for both the MMSE and the SMQ, but the difference between the two scales was not statistically significant. CONCLUSION: As screening tests to detect dementia in the elderly general population, the SMQ which is assessed by informants demonstrates a statistically significant discriminating ability as well as the MMSE.

Aged↗
PubMedDate not supplied

Utility of (99m)Tc-HM-PAO SPECT hippocampal image to diagnose early stages of Alzheimer's disease using semiquantitative analysis.

OBJECTIVE: Examination of the utility of (99m)Tc-hexamethylpropylene amine oxide ((99m)Tc-HM-PAO) SPECT hippocampal image to diagnose early stages of Alzheimer's disease (AD) using semiquantitative analysis. SUBJECTS: 10 early-stage AD patients and 8 normal sex-matched elderly controls. SETTING: Outpatient division of the Ehime University Hospital. METHOD: We performed (99m)Tc-HM-PAO SPECT perfusion imaging in each subject. A semiquantitative method of assessing regional variation was used. The regions of interest for temporal regions were set at images parallel to the long axis of the hippocampal formation which were reconstructed at 30 degrees negative to the orbitomeatal line and those for other regions were set on ordinary transaxial images. RESULTS: The regional cerebral blood flow ratio of the bilateral medial temporal lobe at the hippocampal image was significantly lower in the AD subjects than in the normally aged controls without any other differences in ordinary transaxial images. CONCLUSION: This study suggests that (99m)Tc-HM-PAO SPECT hippocampal images might be a helpful tool for the diagnosis of very-early-stage AD.

Aged↗
PubMedDate not supplied

Relationship between blood flow kinetics and severity of Alzheimer's disease: assessment of severity using a questionnaire-type examination, Alzheimer's disease assessment scale, cognitive sub-scale (ADAS(cog)).

We assessed hemokinetics associated with changes in Alzheimer's disease (AD) severity in 90 AD patients by researching the relationship between AD Assessment Scale, cognitive sub-scale (ADAS(cog)) scores and regional cerebral blood flow (rCBF). In the present study, we employed the questionnaire-type ADAS(cog) examination to accurately assess the severity of AD. Between five groups classified on the basis of ADAS(cog) score, significant differences were observed in parietal, lateral temporal and superior frontal rCBF. In addition, in parietal and lateral temporal regions, significant correlations were also observed between ADAS(cog) score and rCBF. In superior frontal rCBF, significant differences were noted only between group 5 (> or =40 ADAS(cog) points) and each of the other groups; there was no significant correlation between rCBF and ADAS(cog) score. Thus, we propose the following mechanism for blood flow kinetics associated with changed severity: In an early stage of AD, blood flow in the medial temporal cortex is impaired, and gradually involves the temporoparietal regions. While the medial temporal impairment of blood flow reaches a plateau, temporoparietal blood flow continues to be impaired well into a severe stage, at which point blood flow impairment in the frontal region is initiated.

Aged↗
PubMedDate not supplied

Frontotemporal lobar degeneration: a study in Japan.

Frontotemporal lobar degeneration is the most common form of cortical dementia occurring in the presenium after Alzheimer's disease. We analyzed two types of frontotemporal dementia (FTD) and semantic dementia (SD) selected from a consecutive series of outpatients based on neuropsychological symptoms, psychiatric symptoms and abnormal behavior. In our series of 134 patients with primary degenerative dementia, there were 16 cases of FTD and 6 cases of SD. Patients with subgroups of FTD and patients with SD were distinguishable only by the presence of aphasia in the latter group. They were not distinguishable from one another by other neuropsychological examinations, behavioral abnormalities or psychiatric symptoms assessed with the Neuropsychiatric Inventory.

Aged↗