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K Terao

Publications and source records attributed to K Terao.

At least 19 recordsLinked to original sources
PubMed2001

Interplay of the main chain, chiral side chains, and solvent in conformational transitions: poly([(R)-3,7-dimethyloctyl]-[(S)-3-methylpentyl]silylene).

Light scattering, sedimentation equilibrium, viscosity, circular dichroism (CD), and UV absorption (UV) measurements were made on dilute solutions of poly([(R)-3,7-dimethyloctyl]-[(S)-3-methylpentyl]silylene)(PRS) as functions of molecular weight. From light scattering and viscosity data, PRS is found to be a very stiff polymer of persistence length q as large as 103 nm at 25 degrees C, essentially a 7(3) helix found in the solid state; q increases only gradually with lowering temperature between -15 and 25 degrees C. The CD data show that PRS undergoes a conformational transition around 3 degrees C in isooctane (transition temperature T(c)). The CD signal is largely positive at low temperatures, passes through zero at T(c), and becomes largely negative at higher temperatures; T(c) is independent of sample's chain length N. This is a highly cooperative helix (M)-to-helix (P) transition depending remarkably on N, as PRS is substantially rodlike. The CD data are converted to the fraction f(P) of P helix as a function of N and analyzed successfully by a statistical mechanical theory based on a helix reversal model, where a polymer chain consists of M and P helices intervened by helix reversals, with the result that the free energy difference DeltaG(h) between P and M shows a temperature dependence similar to that of 2f(P) - 1, whereas the helix reversal energy is substantially constant at 1.2 x 10(4) J mol(-1); the latter value means that the helix reversal occurs only once in 100 Si units or less. This DeltaG(h) change and solvent dependence of T(c) are explained by a double-well potential for the rotation about Si-Si bonds, which incorporates into DeltaG(h) the solvent interactions with the helical grooves of side chains surrounding the main chain. Detailed features of UV absorption spectra at different temperature and molecular weights are also presented.

Journal Article↗
PubMed2001

Behavioral compensations in a positional learning and memory task by aged monkeys.

The present experiment assessed learning and memory of a positional task by evaluating behavioral strategies as well as accuracy of a task in four young and four aged monkeys. They were tested in a delayed response (DR) task that has been widely used to study animal models of aging. The task consisted of two phases; an acquisition of the task and a positional memory test with five delay times (1-30 s). There was no clear difference between age groups in the number of trials needed for acquisition of the task. However, an analysis of behavior revealed differences in behavioral characteristics displayed during testing. The young monkeys showed various irrelevant behaviors during the execution of the task. In contrast, the aged monkeys consistently concentrated on the task exhibiting no behaviors irrelevant to the task. These results showed than the aged monkeys' performance was supported by a different behavioral strategy from the young monkeys. The results of the memory test were similar to those of the acquisition on the accuracy and the behavior. The aged monkeys depended on behavioral cues to preserve their positional memory, especially during the task. The present study suggests that cognitive impairments in aged monkeys can be compensated for by employing behavioral strategies.

Journal Article↗
PubMed2001

Assignment of 118 novel cDNAs of cynomolgus monkey brain to human chromosomes.

In order to isolate genes that may not be represented in current human brain cDNA libraries, we have sequenced about 20,000 sequence tags of cDNA clones derived from cerebellum and parietal lobe of cynomolgus monkeys (Macaca fascicularis). We determined the entire cDNA sequence of approximately 700 clones whose 5'-terminal sequences showed no homology to annotated putative genes or expressed sequence tags in current databases of genetic information. From this, 118 clones with sequences encoding novel open reading frames of more than 100 amino acid residues were selected for further analysis. To localize the genes corresponding to these 118 newly identified cDNA clones on human chromosomes, we performed a homology search using the human genome sequence and fluorescent in situ hybridization. In total, 108 of 118 clones were successfully assigned to specific regions of human chromosomes. This result demonstrates that genes expressed in cynomolgus monkey are highly conserved throughout primate evolution, and that virtually all had human homologs. Furthermore, we will be able to discover novel human genes in the human genome using monkey homologs as probes.

Animals↗
PubMed2001

Computing handedness: quantized and superposed switch and dynamic memory of helical polysilylene.

Two new conjugating helical polymers comprising a rodlike silicon backbone and enantiopure chiral pendants, poly[(R)-3,7-dimethyloctyl-(S)-3-methylpentylsilylene] (PS-1) and its diastereomeric poly[(S)-3,7-dimethyloctyl-(S)-3-methylpentylsilylene] (PS-2), were prepared. Molecular mechanics calculations of PS-1 and PS-2 model oligomers indicated a double well potential energy curve corresponding to almost enantiomeric helices with dihedral angles of 150-160 degrees (P-motif, global minimum) and 200-210 degrees (M-motif), regardless of their tacticity. Experimentally, it was found that PS-1 in dilute isooctane revealed switchable ambidextrous helicity on application of a thermal energy bias. Although PS-1 featured three distinct switching regions, viz. "region 1, between -80 and -10 degrees C", "region 2, between -10 and +10 degrees C", and "region 3, between +10 degrees C and +80 degrees C", the switching properties were interpreted as the result of superposed P- and M-helicities, undergoing dynamic pseudo-racemization or oscillation. Oscillating helicity in region 2 was roughly estimated to be about 13 cm(-)(1). The superposed helicity in region 2 was critical since it afforded molecular recognition ability with a dynamic memory function that was highly susceptible to solvent molecular topology and volume fraction. This could lead to potential as a molecular information processor to serve as a gauge of chemical properties. On the other hand, PS-2 could not switch its preferential screw-sense in the range of -80 to +80 degrees C. This may be related to greater differences the potential energy curve between P- and M-motifs.

Journal Article↗
PubMed2001

Cryopreservation-induced acrosomal vesiculation in live spermatozoa from cynomolgus monkeys (Macaca fascicularis).

BACKGROUND: Cryopreserved spermatozoa are known to undergo accelerated capacitation and require a shorter incubation time for fertilization. However, details of their acrosomal membranes following cryopreservation remain unclear. METHODS: Percoll density gradient centrifugation was used to remove dead spermatozoa; thus >90% live spermatozoa were recovered after cryopreservation, and acrosomal status was compared among non-incubated and incubated fresh and cryopreserved spermatozoa. RESULTS: Transmission election microscopy (TEM) using microwave methods and fluorescein isothiocyanate-conjugated Pisum sativum agglutinin (FITC-PSA) staining revealed that 21.1 and 61.6% respectively of non-incubated, cryopreserved spermatozoa were intact, whereas 97.6% (TEM) or 91.9% (FITC-PSA) of non-incubated fresh spermatozoa were intact. TEM revealed that 28.8% of the cryopreserved spermatozoa were swollen, and probably included among those counted as intact by FITC-PSA staining. The non-incubated cryopreserved spermatozoa had fused plasma and outer acrosomal membranes, and 36.4% of them had vesiculation when observed by TEM. FITC-PSA staining indicated that 22% of the live spermatozoa were acrosome reacted. CONCLUSIONS: Acceleration of the acrosome reaction was evident by both TEM and FITC-PSA. Incubation of cryopreserved spermatozoa for 2 h accelerated vesiculation to a state similar to that of fresh spermatozoa that had been incubated for 8 h. These results reveal that in cryopreserved spermatozoa, the process of acrosome reaction begins before incubation.

Acrosome↗
PubMed2001

Natural killer type 2 bias in remission of multiple sclerosis.

Multiple sclerosis (MS) is an autoimmune disease characterized by clinical relapse and remission. Because of the potential role of natural killer (NK) cells in the regulation of autoimmunity, we have examined cytokine profile and surface phenotype of NK cells in the peripheral blood of MS. Here we demonstrate that NK cells in the remission of MS are characterized by a remarkable elevation of IL-5 mRNA and a decreased expression of IL-12Rbeta2 mRNA, as well as a higher expression of CD95. Moreover, the NK cells from MS in remission produced much larger amounts of IL-5 than did those from controls after stimulation with phorbol myristate acetate (PMA) and ionomycin. These features are reminiscent of those of NK type 2 (NK2) cells that can be induced in a condition favoring functional deviation of T cells toward Th2. Remarkably, the NK cells lose the NK2-like property when relapse of MS occurs, but regain it after recovery. We also found that NK2 cells induced in vitro inhibit induction of Th1 cells, suggesting that the NK2-like cells in vivo may also prohibit autoimmune effector T cells. Taken together, it is possible that NK cells play an active role in maintaining the remission of MS.

Adult↗
PubMed2001

Possible role of peripheral CD14low monocytes in the development of collagen-induced arthritis in cynomolgus monkeys (Macaca fascicularis).

The changes in levels of peripheral major lymphocyte subsets were monitored with 10 adult cynomolgus monkeys (5 females and 5 males) during the 9 weeks after immunization with chick type-II collagen in Freund's complete adjuvant. Three females and 3 males developed overt arthritis determined by swelling of small joints and increase of plasma alkaline phosphatase as well as C-reactive protein. An increase of CD16+ NK cells was observed in four non-arthritis-developed monkeys (two females and two males). There was no significant difference in the fluctuation pattern of CD4+ T cell, CD8+ T cell and CD20+ B cell levels between arthritis-developed monkeys and non-developed ones. In addition, the percentages of CD45RA+ CD4+ T cells to total CD4+ T cells, CD28- CD8+ T cells to total CD8+ T cells, and IgD- B cells to total B cells did not significantly differ between them. On the other hand, a significant increase was demonstrated in CD14-positive cells at 3 weeks after immunization in only arthritis-developed monkeys regardless of sex. The expression of CD14 antigen on the surface of increased cells was low in comparison with those appearing in blood obtained before immunization. In addition, increased CD14low cells showed no response to LPS stimulation. However, there was no significant difference in antibody titer to both chick type-II and monkey type-II collagen between arthritis-developed monkeys and non-developed ones. These results suggest that an increase in number of CD14low monocytes with immature function might be a part of the autoimmune response, and that the appearance of these cells is of pathogenic importance in the arthritic process in cynomolgus monkeys regardless of the production of autoantibody.

Alkaline Phosphatase↗
PubMed2001

Gene transfer into nonhuman primate hematopoietic stem cells: implications for gene therapy.

Hematopoietic stem cells (HSCs) are desirable targets for gene therapy because of their self-renewal and multilineage differentiation abilities. Retroviral vectors are extensively used for HSC gene therapy. However, the initial human trials of HSC gene marking and therapy showed that the gene transfer efficiency into human HSCs with retroviral vectors was very low in contrast to the much higher efficiency observed in murine experiments. The more quiescent nature of human HSCs and the lower density of retroviral receptors on them hindered the efficient gene transfer with retroviral vectors. Since nonhuman primates have marked similarity to humans in all aspects including the HSC biology, their models are considered to be important to evaluate and improve gene transfer into human HSCs. Using these models, clinically relevant levels (around 10% or even more) of gene-modified cells in peripheral blood have recently been achieved after gene transfer into HSCs and their autologous transplantation. This has been made possible by improving ex vivo transduction conditions such as introduction of Flt-3 ligand and specific fibronectin fragment (CH-296) into ex vivo culture during transduction, and the use of retroviral vectors pseudotyped with the gibbon ape leukemia virus or feline endogenous retrovirus envelope. Other strategies including the use of lentiviral vectors and in vivo selective expansion of gene-modified cells with the drug resistance gene or selective amplifier gene (also designated the molecular growth switch) are now being tested to further increase the fraction of gene-modified cells using nonhuman primate models. In addition to the high gene transfer efficiency, high-level and long-term expression of transgenes in human HSCs and their progeny is also required for effective HSC gene therapy. For this purpose, other backbones of retroviral vectors such as the murine stem cell virus and cis-DNA elements, such as the ss-globin locus control region and the chromatin insulator, also need to be tested in nonhuman primate models. Nonhuman primate studies will continue to provide an important framework for human HSC gene therapy. Well-designed nonhuman primate studies will also offer unique insights into the HSCs, immune system, and transplantation biology characteristic of large animals.

Animals↗
PubMed2001

Carrier-mediated hepatobiliary transport of a novel antifolate, N-[4-[(2,4-dianninopteridine-6-yl)methyl]-3,4-dihydro-2H-1,4-benzothiazin-7-yl]carbonyl-L-homoglutamic acid, in rats.

The hepatic uptake and biliary excretion of a novel methotrexate derivative, N-[4-[(2,4-diamminopteridine-6-yl)methyl]-3,4-dihydro-2H-1,4-benzothiazin-7-yl]carbonyl-L-homoglutamic acid (MX-68), were examined in rats in vitro using isolated hepatocytes and bile canalicular membrane vesicles (CMVs), respectively. The uptake of MX-68 by isolated rat hepatocytes showed a saturable component (Km = 2.15 microM and Vmax = 2.34 pmol/min/mg of protein) and was inhibited by ATP-depletors and anionic compounds such as taurocholate and probenecid. [3H]MX-68 uptake was also inhibited by folate analogs such as methotrexate and 5CH3-tetrahydrofolate, but the effect of these compounds was slightly less than that of unlabeled MX-68. On replacing Na+ with choline, MX-68 uptake remained unchanged, whereas the methotrexate uptake was reduced. Uptake of MX-68 increased as the extracellular pH fell from 7.5 to 5.5. These results suggest that MX-68 is taken up via active transport systems. The uptake of MX-68 by CMVs prepared from normal rats exhibited clear ATP dependence, whereas ATP had only a minimal effect on the uptake by CMVs from Eisai-hyperbilirubinemic rats with a hereditary deficiency in canalicular multispecific organic anion transporter (cMOAT). The initial uptake rate of ATP-dependent MX-68 transport showed saturation with kinetic parameters similar to those of methotrexate. MX-68 inhibited the ATP-dependent transport of 2,4-dinitrophenyl-S-glutathione, a typical substrate for cMOAT, the inhibition constant (162 microM) being comparable with the Km of ATP-dependent MX-68 transport. These results suggest that the biliary excretion of MX-68 via the bile canalicular membrane is mediated mainly by cMOAT. In conclusion, active transport systems are involved in membrane penetration of MX-68 both at sinusoidal and canalicular sides in the liver, the latter being mainly involved with methotrexate (MTX) whereas the former differs partially from that for MTX.

2-Aminoadipic Acid↗
PubMed2001

Specific gravity of whole blood in cynomolgus monkeys (Macaca fascicularis), squirrel monkeys (Saimiri sciureus), and tamarins (Saguinus labiatus) and total blood volume in cynomolgus monkeys.

Blood collection is a common laboratory procedure in animal experiments. The purpose of this study is to establish baseline data for two essential hematologic parameters, total blood volume (TBV) and specific gravity of blood (SGB), of nonhuman primates. The SGB was determined by dropping samples of whole blood into cupric sulfate solution. The values for the mean SGB +/- 1 standard deviation are: cynomolgus monkeys, 1.0526 +/- 0.0019 [males (n = 39), 1.0531 +/- 0.0017; females (n = 48), 1.0522 +/- 0.001]; squirrel monkeys, 1.0555 +/- 0.0037 [males (n = 56), 1.0581 +/- 0.0027; females (n = 76), 1.0536 +/- 0.0032]; and tamarins, 1.0582 +/- 0.0020 [males (n = 13), 1.0582 +/- 0.0023; females (n = 17), 1.0581 +/- 0.0018]. To determine the TBV, blood was collected in tubes containing 1.5 mg EDTA after intravenous injection of Evans Blue solution. The TBV was obtained after correcting for the hematocrit and the dilution factor of the Evans Blue solution. The formulae were established to estimate TBV by referring to body weight (BW). There was no significance between TBV and BW in male monkeys weighing more than 6 kg.

Animals↗
PubMed2000

Screening of the Men1 gene and discovery of germ-line and somatic mutations in apparently sporadic parathyroid tumors.

Hyperparathyroidism is the first manifestation in a majority of multiple endocrine neoplasia (MEN1) patients. To discriminate between sporadic and hereditary parathyroid tumors and characterize MEN1 somatic mutations, we examined MEN1 gene mutations in patients who had undergone surgery for sporadic parathyroid tumors. DNA was extracted from fresh frozen parathyroid tumor specimens from 112 patients as well as from peripheral blood leukocytes from 64 of the 112 patients. Sequence analysis was performed to examine exons 2-10 of the MEN1 gene for mutations. Loss of heterozygosity (LOH) was also examined by an analysis of codon 418 and 541, which lie within a polymorphic region of MEN1. Somatic MEN1 mutations were found in 25 of the 112 patients (22%). Two patients had two point mutations (508del33 and Y341X and 363insT and 1767delT, respectively). A total of 27 mutations were characterized, 20 of which have not been reported previously. There were 7 nonsense mutations, 10 frameshift mutations, 2 splice site deletions, 5 missense mutations, and 3 in-frame mutations. Nineteen mutations (70%) predicted truncation of the menin protein. Germ-line MEN1 mutations were found in 3 of 64 patients (5%) who had no family history of endocrine tumors associated with MEN1, and these patients were identified as MEN1 gene probands. LOH at the MEN1 locus was detected in three parathyroid tumors showing germ-line mutation. LOH was significantly frequent in parathyroid tumors with somatic MEN1 mutations (15 of 22 tumors, 68%) but not in those without germ-line or somatic MEN1 mutations (14 of 51 tumors, 28%; P = 0.0011). Our findings suggest that alterations of both alleles of the MEN1 gene may be associated not only with endocrine tumors of affected MEN1 patients but also with sporadic parathyroid tumors. Germ-line MEN1 gene analysis can distinguish heritable from nonheritable parathyroid tumors, and MEN1 gene evaluation of patients with apparently sporadic parathyroid tumor is recommended before parathyroid surgery.

Adult↗
PubMed2000

Development of novel simian immunodeficiency virus vectors carrying a dual gene expression system.

The development of highly efficient and safe gene transfer methods suitable for clinical use is required for human gene therapies. We have developed a novel lentiviral vector system, based on the nonpathogenic simian immunodeficiency virus from African green monkeys (SIVagm), that carries a unique dual gene expression system. This system utilizes the lentivirus Rev responsive element (RRE). Self-inactivating vectors were also developed by deleting a U3 region in the 3' long terminal repeat (3' LTR) of the virus. When pseudotyped with a vesicular stomatitis virus envelope glycoprotein G (VSV-G), the SIVagm-based vectors could transduce both growth-arrested human cells and terminally differentiated neuronal cell lines. Using these vectors, two reporter genes could be expressed simultaneously at equal levels, and expression levels of both genes could be altered by modifying the length of the RRE sequence. These SIVagm-based vectors might offer safety advantages over other lentivirus-based vectors. Furthermore, the novel dual gene expression system described here could increase the usefulness and value of both viral and nonviral vectors in gene therapy.

Base Sequence↗
PubMed2000

Involvement of granzyme B expression in the enhancement of natural killer activity by beta-endorphin.

Beta-Endorphin has been reported to enhance natural killer (NK) activity in vitro. However, few studies have examined the precise regulation of the cytolytic stage of NK cells. We therefore investigated the regulation by beta-endorphin of cytotoxicity-associated molecules such as granzyme B, perforin, and Fas ligand (FasL) in human CD16(+) NK cells. On semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) assay, the granzyme B mRNA level apparently increased in CD16(+) NK cells from high responding subjects having ratios >1.5 for the LU(30) ratio. An increase in intracellular granzyme B molecules was also detected in CD16(+) NK cells by flow cytometry. On the other hand, perforin and FasL appeared not to be involved in regulation by beta-endorphin. These findings suggest that up-regulation of granzyme B expression may be involved in the enhancement of NK activity by beta-endorphin.

Adult↗
PubMed2000

Immunohistochemical detection of apolipoprotein E within prion-associated lesions in squirrel monkey brains.

The interaction of various amyloid precursors and apolipoprotein E (apoE) is important for Congophilic amyloid formation. As for cerebral amyloidoses, although the correlation between amyloid beta protein (Abeta) and apoE in Alzheimer's disease (AD) has been clarified, the interaction of prion protein isoform (PrPsc) and apoE in several types of prion diseases (PDs) has not been examined in detail. ApoE colocalization has been confirmed in Congophilic PrPsc plaques, but to clarify the participation of apoE in the early stage of PDs, apoE deposition in immature lesions without Congophilic amyloid in PDs needs to be examined. In the present study two squirrel monkeys were inoculated with mouse PrPsc derived from sheep scrapie, and showed signs of severe spongiform degeneration. These lesions were immunohistochemically characterized as patchy perivacuolar and diffuse synaptic lesions without Congophilic amyloid. The central portion of the assemblies involving a few patchy perivacuolar lesions was detected by methenamine silver staining and appeared as a plaque-like lesion. ApoE was colocalized in all the plaque-like lesions and in half of the patchy perivacuolar lesions, but not in any diffuse synaptic lesions. These immunohistochemical characteristics indicated that apoE colocalization occurred in moderate mature lesions in PDs, and apoE might play an important role in the aggregation of PrPsc after a conformational change from cellular PrP isoform to PrPsc.

Amyloid beta-Peptides↗
PubMed2000

Molecular cloning and characterization of cynomolgus monkey Fas.

The Fas-FasL system plays a crucial role in the maintenance of homeostasis in the immune system. To characterize the Fas/FasL system in macaque monkeys that are commonly used as experimental primates, we cloned and sequenced Fas cDNA derived from the cynomolgus monkey. The predicted amino acid sequence consists of 331 amino acids with a calculated molecular weight of 35,800. The extracellular cysteine-rich motif of cynomolgus Fas is highly homologous to that of humans (96%), whereas the intracellular death domain has a relatively low similarity to that of humans (86%). An agonistic Fas antibody (CH11) or cynomolgus FasL induced apoptosis in human Fas-transfected K562 cells in the presence of CHX but not in the cynomolgus Fas transfectant. CH11 and FasL failed to trigger apoptosis in the transfectant expressing human-cynomolgus chimera Fas consisting mostly of human-derived extracellular region and cynomolgus-derived intracellular portion. On the other hand, the transfectant expressing cynomolgus-human chimera Fas with human-derived intracellular region underwent apoptosis upon exposure to FasL. In addition, the virus-transformed, Fas-positive cynomolgus monkey cell line was highly sensitive to FasL. These findings suggest that the lack of apoptotic activity in the cynomolgus Fas transfectant in the human cell line might be related to the species-specific structure of Fas, especially of the death domain.

Amino Acid Sequence↗
PubMed2000

Comparative FISH mapping of the ancestral fusion point of human chromosome 2.

It is known that human chromosome 2 originated from the fusion of two ancestral primate chromosomes. This has been confirmed by chromosome banding and fluorescence in-situ hybridization (FISH) with human chromosome-2-specific DNA libraries. In this study, the order of 38 cosmid clones derived from the human chromosome region 2q12-q14 was exactly determined by high-resolution FISH in human chromosome 2 and its homologous chromosomes in chimpanzees (Pan trogrodydes, 2n=48) and cynomolgus monkeys (Macacafascicularis, 2n = 42). This region includes the telomere-to-telomere fusion point of two ancestral ape-type chromosomes. As a result of comparative mapping, human chromosome region 2q12-q14 was found to correspond to the short arms of chimpanzee chromosomes 12 and 13 and cynomolgus monkey chromosomes 9 and 15. It is noted that no difference was detected in the relative order of the cosmid clones between human and chimpanzee chromosomes. This suggests that two ancestral ape-type chromosomes fused tandemly at telomeres to form human chromosome 2, and the genomic organization of this region is thought to be considerably conserved. In the cynomolgus monkey, however, the order of clones in each homologue was inverted. In addition to cosmid mapping, two chromosome-2-specific yeast artificial chromosome (YAC) clones containing the fusion point were identified by FISH.

Animals↗