Biomedical subjects

M Kato

Publications and source records attributed to M Kato.

At least 145 records · Page 8Linked to original sources

PubMed2001

Simultaneous determination of D-lactic acid and 3-hydroxybutyric acid in rat plasma using a column-switching HPLC with fluorescent derivatization with 4-nitro-7-piperazino-2,1,3-benzoxadiazole (NBD-PZ).

A highly sensitive method for the determination of D-lactic acid and 3-hydroxybutyric acid (3-HB) in rat plasma was developed using high-performance liquid chromatography with octadecylsilica (ODS) connected to a chiral column. At first, (D + L)-lactic acid and 3-HB in the plasma were derivatized with a fluorescent reagent, 4-nitro-7-piperazino-2,1,3-benzoxadiazole (NBD-PZ), separated on the ODS column and determined fluorimetrically at 547 nm with 491 nm of excitation wavelength. During the separation step on the ODS, the peak fraction of (D + L)-lactate derivative was introduced directly to a phenylcarbamoylated beta-cyclodextrin chiral column by changing the flow of the eluent via a six-port valve. Then, D-lactate derivative was separated enantiomerically from the L-lactate derivative, and the enantiomeric ratio was determined from the chromatogram. Intra- and inter-day accuracy values for the determination of D-lactic acid in 10 microL of rat plasma were 97.8-109.2 and 98.4-109.9%, and those for 3-HB were 99.8-108.4 and 99.8-103.8%, respectively. The intra- and inter-day precision values were within 4.6 and 5.1% for D-lactic acid, and 2.7 and 2.4% for 3-HB, respectively. The detection limits for D-lactic acid and 3-HB were approximately 2.0 and 0.04 microM, respectively (signal-to-noise ratio 3). The proposed method was applied to the plasma of diabetic rats induced by intraperitoneal administration of streptozotocin, and the significant increases of both D-lactic acid and 3-HB concentrations were observed in the diabetic rats as compared to the normal rats.

3-Hydroxybutyric Acid↗

PubMed2001

Induced circular dichroism in solid-state inclusion compounds.

In order to measure the circular dichroism (CD) spectrum in the solid state of a chiral compound which has no chromophore, an induced CD spectral method was developed by measuring the spectrum of the inclusion crystal of the chiral compound with a simple achiral aromatic host compound in the Nujol mulls.

Journal Article↗

PubMed2001

Acrolein induces activation of the epidermal growth factor receptor of human keratinocytes for cell death.

Acrolein, which is a highly reactive formaldehyde generated by lipid peroxidation, can affect skin and cause various disorders. The effect of exposure of human keratinocytes to acrolein on cell surface-oriented signal transduction into cells was examined. Incubation of human keratinocytes with a relatively low concentration (50 microM) of acrolein caused a prompt and selective induction of tyrosine phosphorylation of the epidermal growth factor receptor (EGFR) as a 180-kDa molecule during the period from 5-30 min after the start of incubation. This early event was followed by an increase in the density and number of phosphotyrosine-containing proteins during the period from 60-120 min after the start of incubation. The catalytic activity of EGFR as measured by the levels of autophorphorylation and phosphorylation of an exogenously added substrate, casein, in in vitro kinase assay, greatly increased as early as 1 min after the start of incubation and then decreased gradually 30 min later. MAP family kinases, including ERK, JNK, and p38 kinase, and the potentially downstream transcription factor c-Jun were all promoted for phosphorylation/activation during a period of 5-30 min. Selective prompt phosphorylation/activation of EGFR followed by phosphorylation of MAP family kinases and c-Jun and their blockade by a specific EGFR inhibitor, AG1478, suggested that activation of EGFR is the major, and possibly single, cell surface element for intracellular signal transduction in acrolein-treated cells. Incubation of human keratinocytes with 50 microM of acrolein induced atypical apoptosis with morphologic apoptotic features with low-grade oligonucleoside-sized DNA fragmentation. Partial inhibition of such a cytopathic effect of acrolein on human keratinocytes by preincubation with AG1478 suggests the involvement of an EGFR-mediated signal pathway for atypical apoptosis. These results provide new information on acrolein-induced cell surface-oriented signal transduction to human keratinocytes, and this information may be useful for understanding the pathogenesis of a number of skin diseases in response to environmental acrolein and acrolein-generating ultraviolet irradiation.

Acrolein↗

PubMed2001

Cepharanthine activates caspases and induces apoptosis in Jurkat and K562 human leukemia cell lines.

Cepharanthine (CEP) is a known membrane stabilizer that has been widely used in Japan for the treatment of several disorders such as anticancer therapy-provoked leukopenia. We here report that apoptosis was induced by low concentrations (1-5 microM) of CEP in a human leukemia T cell line, Jurkat, and by slightly higher concentrations (5-10 microM) in a human chronic myelogenous leukemia (CML) cell line K562, which expresses a p210 antiapoptotic Bcr-Abl fusion protein. Induction of apoptosis was confirmed in both Jurkat and K562 cells by DNA fragmentation and typical apoptotic nuclear change, which were preceded by disruption of mitochondrial membrane potential and were induced through a Fas-independent pathway. CEP treatment induced activation of caspase-9 and -3 accompanied by cleavage of PARP, Bid, lamin B1, and DFF45/ICAD in both Jurkat and K562 cells, whereas caspase-8 activation and Akt cleavage were observed only in Jurkat cells. The CEP-induced apoptosis was completely blocked by zVAD-fmk, a broad caspase inhibitor. Interestingly, CEP treatment induced remarkable degradation of the Bcr-Abl protein in K562 cells, and this degradation was prevented partially by zVAD-fmk. When used in combination with a nontoxic concentration of herbimycin A, lower concentrations (2-5 microM) of CEP induced obvious apoptosis in K562 cells with rapid degradation or decrease in the amount of Bcr-Abl and Akt proteins. Our results suggest that CEP, which does not have bone marrow toxicity, may possess therapeutic potential against human leukemias, including CML, which is resistant to anticancer drugs and radiotherapy.

Alkaloids↗

PubMed2001

Effects of cryopreservation of pronuclear-stage rabbit zygotes on the morphological survival, blastocyst formation, and full-term development after DNA microinjection.

The objectives of this study were to examine the freezing sensitivity of pronuclear-stage rabbit zygotes and to produce transgenic rabbits using the cryopreserved zygotes. Zygotes were cryopreserved either by one of two vitrification protocols or by one of the two conventional freezing protocols. The morphological survival rates of zygotes subjected to two-step freezing in 1.5 M ethylene glycol and 0.1 M sucrose (74%) or to vitrification in 7.2 M ethylene glycol and 1.0 M sucrose (81%) were higher than those subjected to freezing in 1.5 M DMSO (46%) or to vitrification in a mixture of 2.0 M DMSO, 1.0 M acetamide, and 3.0 M propylene glycol (41%). But the in vitro development into blastocysts of zygotes cryopreserved by vitrification (17%) or to a lesser extent by freezing (52%) was impaired, when compared to that of fresh control zygotes (89%). Next, a fusion gene composed from bovine aS1-casein promoter and a human GH structural gene (2.8 kb) was microinjected into the pronucleus of rabbit zygotes frozen-thawed in ethylene glycol and sucrose. Then, the presence of exogenous DNA in the genome of newborn offspring was determined by PCR. The post-injection survival of frozen zygotes (97%) was the same as that of fresh control zygotes (96%). However, of 18 offspring derived from 414 frozen-thawed and DNA-injected zygotes, no transgenic rabbits were produced. Of 52 offspring derived from 403 DNA-injected fresh zygotes, 3 transgenic rabbits were found. Here we report the first rabbit offspring resulting from zygotes cryopreserved at the pronuclear-stage, although the cryopreservation procedure employed must be improved if zygotes are to be used for systematic production of transgenic rabbits.

Animals↗

PubMed2001

Release of IL-4 and IL-5 from human peripheral blood mononuclear cells co-cultured with Japanese cedar pollen antigen in vitro.

The Japanese cedar pollen (JCP) is a major allergen with respect to pollinosis in Japan. It is believed that interleukin-4 (IL-4) and interleukin-5 (IL-5) derived from lymphocytes and other cells play a pivotal role in allergic reactions. We investigated whether the JCP antigen stimulates the release of these cytokines by peripheral blood mononuclear cells (PBMCs). PBMCs from eight adults (five adults with JCP pollinosis and three adults without JCP pollinosis) were co-incubated with purified JCP antigens. IL-4 was released in response to JCP antigens in six of the eight subjects at 24 h and in three subjects at 48 h. IL-4 release at 24 h occurred in all five subjects with JCP pollinosis but in only one of the three subjects without pollinosis. IL-5 was released in response to the JCP antigen in five of the eight subjects at 24 h and 48 h, including four of the five subjects with JCP pollinosis and one of the three subjects without pollinosis. These results suggest that PBMCs were more likely to release IL-4 and IL-5 in the presence of JCP pollinosis.

Adult↗

PubMed2001

Peripheral T/natural killer-cell lymphoma involving the female genital tract: a clinicopathologic study of 5 cases.

Malignant lymphoma of the female genital tract (FGT) is rare. In this study, 5 peripheral T/natural killer (NK)-cell lymphomas (PTCLs) involving the FGT are reported. They include 2 from the uterus and 1 each from ovary, uterus and ovary, and vagina, and were detected between 1996 and 2000. One of the 2 ovarian tumors was bilateral. In all cases, the FGT was the initial site of clinical presentation of disease. Age at presentation ranged from 21 to 52 years (median, 36 years). One case was stage I disease, 2 were stage II, and 2 were stage IV. All 5 tumors were positive for CD3epsilon, and 3 harbored the Epstein-Barr virus, although the detailed immunophenotypic profiles varied. Three were diagnosed as nasal type T/NK-cell lymphoma, 1 as anaplastic large-cell lymphoma (anaplastic lymphoma kinase [ALK]-positive), and 1 as unspecified PTCL of cytotoxic phenotype, according to the forthcoming World Health Organization classification. Four of 5 patients received laparotomy and chemotherapy. Four patients (in stages II and IV) died of disease within 16 months of the initial diagnosis, whereas only 1 patient (in stage I) is alive without disease at 39 months of follow-up. Our experience in this series provided clinically relevant information on diagnosis, treatment, and outcome for extremely rare tumors of the FGT.

Adult↗

PubMed2001

Improvement of splenomegaly and pancytopenia by enzyme replacement therapy against type 1 Gaucher disease: a report of sibling cases.

Gaucher disease is a genetic lipid storage disease and represents a potentially serious health problem. It arises from a deficiency of glucocerebrosidase activity with secondary accumulation of large quantities of glucocerebroside. Symptoms are usually multisystemic, often debilitating or disabling, and sometimes disfiguring, and they can lead to death. We report objective clinical response's to repeated infusion of human placental and recombinant glucocerebrosidase in 2 patients with type 1 Gaucher disease and increased hemoglobin levels and platelet counts. Splenic volume decreased during the period of enzyme administration. Enzyme replacement therapy has improved the treatment of type 1 Gaucher disease by safely and effectively arresting, decreasing, or normalizing many of its major signs and symptoms. Consideration by physicians must be given to Gaucher disease, and appropriate treatments must be given when confronted with cryptogenic pancytopenia or hepatosplenomegaly.

Adult↗

PubMed2001

One missense mutation in the factor X gene causing factor X deficiency--factor X Kanazawa.

We investigated the molecular basis of factor X deficiency in a Japanese patient whose factor X activity and antigen level were 45% and 50% of normal control values, respectively. All exons and intron/exon junctions of the factor X gene were studied using a strategy combining polymerase chain reaction (PCR) amplification and nonradioactive single-strand conformational polymorphism (SSCP) analysis. Exon 5, containing the DNA fragment of the proband, showed aberrant migration by SSCP analysis. All exon-containing DNA fragments amplified by PCR were sequenced, and it was revealed that the proband was a heterozygote for a G --> A substitution in exon 5 of the factor X gene of the proband. This mutation predicts an amino acid replacement of arginine (Arg) for glycine (Gly) at codon 114 in the second EGF-like domain.

Aged↗

PubMed2001

Pregnancy-associated cytotoxic lymphoma: a report of 4 cases.

The clinicopathological and biological significance of Hodgkin's disease and non-Hodgkin's lymphoma, which are infrequently encountered in women of childbearing age, remains to be clarified. We recently reviewed 4 cases of non-Hodgkin's lymphoma of the T/natural killer (T/NK)-cell phenotype, all of which were associated with pregnancy and characterized by the expression of the cytotoxic granule-associated proteins T-cell intracellular antigen-1 and/or granzyme B. The 4 cases selected had presented between November 1993 and May 1999. The criteria for selection were that the onset of clinical manifestations occurred during pregnancy or within 6 months after delivery. The patients comprised 1 patient with p80/anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALCL), 1 with p80/ALK-negative ALCL, and 2 with peripheral T/NK-cell lymphomas of unspecified type. The diseases followed aggressive clinical courses: 3 patients died within 6.5 months after diagnosis, and only 1 was still alive with the disease 17 months after diagnosis. The diseases appeared to progress rapidly after delivery. Maternal immunity and hormonal changes during pregnancy may be closely related to the biological behavior of these unusual tumors. This study is, to the best of our knowledge, the first to address pregnancy-associated cytotoxic lymphoma.

Adult↗

PubMed2001

A primary culture system of rat olfactory bulb forming many synapses similar to intact ones and spontaneously generating synchronous intracellular calcium oscillations.

Previously, several studies attempting to analyze olfactory functions using dissociated culture systems of the olfactory bulb (OB) have been reported. Reciprocal dendrodendritic synapses between secondary neurons (mitral/tufted cells) and interneurons (periglomerular/granule cells) are considered to play the most important role in signal processing in the OB. However, it is unclear whether these reciprocal synapses are formed in vitro in the same way as they are in the intact OB. Thus, we synaptologically investigated the nature of cultured OB neurons. These neurons from embryonic rats were classified into four groups based on the size of their somata and their glutamic acid decarboxylase (GAD) immunoreactivity. At 14 days in vitro, most of the neurons synchronously showed spontaneous intracellular Ca2+ oscillations that were reversibly inhibited by application of D-APV and CNQX. Moreover, the frequency of the oscillations decreased and their amplitude became larger following application of bicuculline. These results suggest functional glutamatergic synaptic coupling and inhibitory GABAergic synaptic modulation. Immunocytochemical staining revealed many dot-like products (puncta) that were immunoreactive to GAD as well as to synaptophysin surrounding the cultured neurons. These results strongly indicate the presence of GABAergic synapses. The existence of synaptic contacts in OB neuron cultures was also confirmed by electron microscopy. Two types of synapses, symmetrical and asymmetrical, were morphologically recognizable. Moreover, we could also identify peculiar synapses resembling the in vivo reciprocal dendrodendritic synapses. The use of these primary culture systems will facilitate the elucidation of mechanisms underlying olfactory functions.

Animals↗

PubMed2001

Vitamin K administration to elderly patients with osteoporosis induces no hemostatic activation, even in those with suspected vitamin K deficiency.

The administration of menaquinone-4 (MK-4), one of subclasses of vitamin K2, significantly reduces bone loss in postmenopausal osteoporotic women. However, concerns have been raised about whether vitamin K administration alters the hemostatic balance by inducing a thrombotic tendency. We investigated were whether the administration of vitamin K in the form of MK-4 induced a thrombotic tendency in 29 elderly patients with osteoporosis (5 men, 24 women; age range 78.7+/-5.1 years). Patients were administered 45 mg/day (three times a day, 30 min after each meal) of MK-4 for 12 weeks. Blood samples were obtained from the patients at 0, 4 and 12 weeks after the start of MK-4 administration. A number of hemostatic parameters remained stable under the markedly increased plasma levels of MK-4. However, in patients with suspected vitamin K deficiency, whose plasma levels of vitamin K or factor VII were low, vitamin-K-dependent clotting factors such as factor VII and prothrombin were gradually increased after administration of MK-4. No changes in the sensitive molecular markers such as TAT and F1+2, which reflect the amount of thrombin generated in the blood stream, were observed, even in those patients with suspected vitamin K deficiency. These results indicate that MK-4 can be administered safely, with regard to maintaining the hemostatic balance, to osteoporotic patients receiving no anticoagulant therapy.

Aged↗

PubMed2001

Phototoxic retinal degeneration and toxicokinetics of sitafloxacin, a quinolone antibacterial agent, in mice.

We examined drug concentrations and the incidence of retinal degeneration in the eyes of albino BALB/c mice after a single intravenous administration of sitafloxacin plus a 4 h period of UVA irradiation. Retinal degeneration was induced at 40 mg/kg or more plus UVA irradiation, and there was little decrease in ocular sitafloxacin concentration under UVA irradiation. We then examined the incidence of retinal degeneration with various periods of UVA irradiation in BALB/c mice given a single intravenous administration of 40 mg/kg sitafloxacin. Retinal degeneration occurred in all the groups receiving UVA irradiation immediately after sitafloxacin administration, whereas no retinal degeneration occurred in the groups receiving UVA irradiation starting 30 min or later after administration. In addition, we examined both the retinal degeneration and auricular inflammation in BALB/c mice given a 7-day repeated administration of sitafloxacin at 1, 3.3 and 10 mg/kg per day, which never induce retinal or auricular change by a single administration. Retinal degeneration was not induced at any dose level, although auricular skin inflammation was augmented by repeated administration. These results suggest that the occurrence of retinal degeneration depends on maximum ocular sitafloxacin concentration during UVA irradiation, whereas the severity of auricular inflammation is directly proportional to the total decrease in area under the drug concentration curve for auricular sitafloxacin under UVA irradiation. This difference between retinal degeneration and auricular inflammation may derive from their respective mechanisms of pathogenesis.

Animals↗

PubMed2001

Characterization of the amyR gene encoding a transcriptional activator for the amylase genes in Aspergillus nidulans.

The Aspergillus nidulans amyR gene and its cDNA were cloned and sequenced. The genomic gene comprised 2,092 bp, interrupted by two short introns, and encoded a cys-6 zinc transcriptional activator (AMYR) of 662 amino acid residues with a calculated molecular mass of 72,862 Da. Disruption of the amyR gene caused defects in the utilization of maltose and starch and abolished expression of the taaG2 gene encoding A. oryzae Taka-amylase A, which is inducibly and abundantly expressed in the wild-type A. nidulans. Expression of the amyR gene was under the control of the carbon catabolite repressor, CREA. The growth defect of the malA1 mutant on maltose was complemented by the amyR gene; and the amyR gene derived from the mutant possessed a single mutation, from A to T, at position 1,483, resulting in a substitution of His478 to Leu. These results indicate that the amyR gene is identical to the genetically defined malA gene. AMYR possessed five domains (Zn and MH1-MH4) homologous to Mal63p, a transcriptional activator for the genes involved in maltose utilization in Saccharomyces cerevisiae. The His478 to Leu substitution lay within the MH3 domain, corresponding to the negative regulatory domain of Mal63p which relieves the inhibitory effect on the activation function in response to maltose.

Amino Acid Sequence↗

PubMed2001

AoHapB, AoHapC and AoHapE, subunits of the Aspergillus oryzae CCAAT-binding complex, are functionally interchangeable with the corresponding subunits in Aspergillus nidulans.

Two genes, AohapB and AohapE, encoding subunits of the Aspergillus oryzae CCAAT-binding complex were cloned and sequenced. The polypeptides encoded by AohapB and AohapE were expressed in Escherichia coli and used to reconstitute a DNA-binding complex with recombinant AoHapC. The DNA-binding activity was observed only in the presence of all three subunits, indicating that AoHapB, AoHapE and AoHapC are essential for CCAAT-binding. Furthermore, introduction of the AohapB, AohapC and AohapE genes into the A. nidulans hapB delta, hapC delta and hapE delta strains, respectively, revealed that the A. oryzae Hap subunits are functionally interchangeable with the corresponding subunits in A. nidulans.

Amino Acid Sequence↗

PubMed2001

Copper chaperone for superoxide dismutase co-aggregates with superoxide dismutase 1 (SOD1) in neuronal Lewy body-like hyaline inclusions: an immunohistochemical study on familial amyotrophic lateral sclerosis with SOD1 gene mutation.

The copper chaperone for superoxide dismutase (CCS) interacts with Cu/Zn-binding superoxide dismutase 1 (SOD1) specifically and delivers copper to SOD1. To determine the role of the CCS-SOD1 interaction in the pathogenesis of SOD1-mutated familial amyotrophic lateral sclerosis (FALS) patients, we produced an affinity-purified rabbit antibody against CCS and investigated the immunohistochemical localization of both CCS and SOD1 in neuronal Lewy body-like hyaline inclusions (LBHIs) in the spinal cords of two FALS patients with a two-base pair deletion at codon 126 in the SOD1 gene and three FALS patients with an Ala to Val substitution at codon 4. The LBHIs in anterior horn cells from the five FALS patients showed identical immunoreactivities for CCS: the reaction product deposits with the antibody against CCS were generally restricted to the periphery of the core and halo-type LBHIs. The localizations of the immunoreactivities for CCS and SOD1 were similar in the inclusions: both CCS and SOD1 colocalized in neuronal LBHIs in the five mutant SOD1-linked FALS patients. Our results suggest that the specific interaction and aggregation of CCS-SOD1 (probably CCS-mutant SOD1) in SOD1-mutated FALS patients may amplify the formation of inclusions and emphasize a more marked mutant SOD1-mediated toxicity.

Adult↗

PubMed2001

The effects of facial fanning on thermal comfort sensation during hyperthermia.

We studied how facial fanning during hyperthermia improves the thermal comfort sensation. Experiments were carried out on ten male subjects. They were immersed in hot water at 40 degrees C for 45 min. At 20 min and 35 min, fanning (1 m x s(-1)) was applied to their faces for 5 min. Core temperature (Tc) measured as esophageal temperature (Tes) and tympanic temperature (Tty) continued to rise during the immersion, but temporarily decreased during fanning with a delay of 2 or 3 min. Skin temperatures (Ts) on the forehead and cheek continued to increase slightly during immersion, but decreased immediately after the start of fanning. During immersion before face fanning, the time trend of thermal sensation towards the warm level was similar to that of skin temperature on the face, whereas the time trend of thermal comfort ratings towards the uncomfortable level was similar to that of Tc. The scores of both thermal sensation and thermal comfort were reduced significantly immediately after the start of fanning, and their time courses were different to those of Ts and Tty. These results support previous reports that thermal sensation depends on skin temperature, and that thermal comfort depends on both the skin and core temperatures. Moreover, they indicate that both thermal sensation and comfort ratings are affected by the dynamic responses of the cutaneous thermoreceptors when fanning is applied to the face during hyperthermia.

Adult↗

PubMed2001

QT intervals and QT dispersion in patients with subarachnoid hemorrhage.

PURPOSE: To clarify the clinical significance of QT dispersion and the longest QT intervals (L-QTc) in patients with subarachnoid hemorrhage (SAH). METHODS: ECGs, clinical features, and laboratory data were analyzed in 38 patients with SAH (R) and 30 with unruptured cerebral aneurysms (U). Standard 12-lead ECGs obtained on admission were analyzed manually, and the longest QT interval (L-QTc) and the QT dispersion (difference between longest and shortest QTc) were compared between groups. RESULTS: There were no differences between groups R and U in age, sex, or location of aneurysms. The QT dispersion and L-QTc were greater in R than in U (109 +/- 49 vs 64 +/- 21 ms and 503 +/- 63 vs 435 +/- 38 ms, respectively; P < 0.01). The QT dispersion and L-QTc were longer in patients with premature ventricular contractions (PVCs) than in patients without PVCs (185 +/- 30 vs 85 +/- 41 ms and 586 +/- 47 vs 467 +/- 59 ms, respectively; P < 0.01). There were positive correlations between QT dispersion or L-QTc and preoperative Hunt and Hess grade (rs = 0.560 and rs = 0.615, respectively; P < 0.01). QT dispersion and L-QTc tended to correlate negatively with serum K(+) (r = -0.365 and r = -0.376, respectively). CONCLUSION: QT dispersion in patients with SAH is prolonged, especially in high-grade cases.

Journal Article↗