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Biomedical subjects

T Mikami

Publications and source records attributed to T Mikami.

At least 415 records · Page 23Linked to original sources
PubMed1993

An experimental study on the effects of selected drugs on pancreatic regeneration after partial pancreatectomy.

This study was undertaken to determine the effect of the single and combined administration of caerulein, hydrocortisone, and FOY-305 (camostat) on the regeneration of the remnant pancreas after a 90% pancreatectomy in rats. After undergoing either a sham operation or a 90% pancreatectomy, the rats were administered the three drugs either singly or in combination. After the rats were killed, the pancreas was weighed and examined for tissue amylase activity, tissue protein content and total DNA content. The results were as follows: In the sham operation group, the caerulein among three drugs produced a significant trophic effect. The trophic effect in the combined administration group was greater than that in the single administration group. In the 90% pancreatectomy group, of the three drugs administered, hydrocortisone produced the most significant trophic effect. The trophic effect in the combined administration group was greater than that in the single administration group. These data suggest that the trophic effect of caerulein is significant in mature pancreatic cells while that of hydrocortisone is an immature one and that an additive effect of the three drugs was observed.

Amylases↗
PubMed1993

Interrelationship between O6-alkylguanine-DNA alkyltransferase activity and susceptibility to chloroethylnitrosoureas in several glioma cell lines.

In order to study the dynamic relationship in glioma cells between O6-alkylguanine-DNA alkyltransferase (AGT) activity and resistance to the cytotoxic effect of chloroethylnitrosoureas (CENUs), we investigated the changes in sensitivity to 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU) after modulation of AGT activity. In ACNU-resistant rat glioma cell lines (9LR1, 9LR3, and 9LR12) and a human glioma cell (HNG-1), O6-methylguanine enhanced cytotoxicity to ACNU following a depletion of AGT activity. But no enhancement of cytotoxicity was seen in an ACNU-sensitive rat glioma cell line (9L). In the 9L and 9LR12 cells, equivalently sublethal doses of ACNU similarly depleted AGT activity but the regeneration rates of this repair protein were different. In the case of a 7-day pretreatment with human recombinant interferon-beta (HuIFN-beta), although it could modulate AGT activity in HNG-1 cells, no definite influence on cellular sensitivity to CENUs was observed. However, a 50-day pretreatment with HuIFN-beta conferred resistance to CENUs on them despite its effect to reduce AGT activity. Thus, diversity was seen in the relation between AGT activity and resistance to CENUs when AGT activity was modulated by HuIFN-beta. The results of this study suggest that AGT activity is one of factors affecting cellular sensitivity to CENUs but that alternative mechanisms of tolerance may be induced depending upon some environmental effects.

Animals↗
PubMed1993

Identification and nucleotide sequence of a gene in feline herpesvirus type 1 homologous to the herpes simplex virus gene encoding the glycoprotein H.

A gene encoding the glycoprotein H (gH) homologue of feline herpesvirus type 1 was identified and sequenced. It was located immediately downstream of the thymidine kinase gene within an EcoRI 6.6 kbp fragment. In addition, a partial UL21 homologous gene was located downstream of the gH homologous gene. The primary translation product of the gH homologous gene is predicted to consist of 821 amino acids with a molecular weight of 92.5 kDa. It possesses several characteristics typical of transmembrane glycoproteins, including a N-terminal hydrophobic signal sequence, C-terminal transmembrane domain, and putative N-linked glycosylation sites. Analysis of this protein revealed amino acid sequence homologies of 33.1% with equine herpesvirus type 1 (EHV-1) gH, 32.6% with EHV-4 gH, 29.1% with varicella-zoster virus gIII, 28.5% with pseudorabies virus gH, and 25.1% with herpes simplex virus type 1 gH. By Northern blot analysis, one of the transcripts specific for the gH homologous gene might be a mRNA of approximately 3.0 kb.

Amino Acid Sequence↗
PubMed1993

Feline CD4 molecules expressed on feline non-lymphoid cell lines are not enough for productive infection of highly lymphotropic feline immunodeficiency virus isolates.

To investigate whether the feline CD 4 (fCD4) molecules are involved in infections of highly lymphotropic feline immunodeficiency virus (FIV) isolates, we expressed fCD4 stably on Crandell feline kidney cells and Felis catus whole foetus 4 cells by transfection of a cDNA encoding the fCD4 glycoprotein, and then infected them with TM 1 and TM 2 strains of FIV, which are unable to infect these cells productively. In spite of fCD 4 being expressed on these cells, no virus production was observed. This result indicates that fCD 4 expression alone cannot induce a productive infection of the FIV TM 1 and TM 2 strains.

Animals↗
PubMed1993

Localization of the viral antigen of feline immunodeficiency virus in the lymph nodes of cats at the early stage of infection.

Immunohistochemical examinations of localization of feline immunodeficiency virus (FIV) Gag protein were performed on lymph nodes of cats experimentally inoculated with three different strains of FIV (infectious molecular clone of TM 1, Petaluma, and KYO-1 strains), using rabbit anti-FIV Gag serum. The FIV Gag antigens were observed in many follicular dendritic cells (FDCs) and sparsely in small lymphocytes of paracortical area in the lymph nodes of cats inoculated with Petaluma and KYO-1 strains. However, the antigens were present only in small lymphocytes, and not in FDCs of a cat inoculated with infectious molecular clone of the TM1 strain. The cell type differences in expression of the viral antigen in vivo might reflect on the cell tropisms of the FIV strains in vitro. By double immunohistochemical staining with rabbit anti-FIV Gag serum and monoclonal antibodies which recognize feline CD4, feline CD8 or feline pan-T molecules, the FIV Gag-positive lymphocytes were characterized as feline CD4-positive T cells. Since the distributions of FIV Gag antigens were mainly in the FDCs, the FDCs may play an important role as a major reservoir and may be a primary target of FIV at early stages of infection.

Animals↗
PubMed1993

The function of the hypothalamo-pituitary axis in brain dead patients.

In order to find out the function of the hypothalamo-pituitary axis in brain dead patients, pituitary and hypothalamic hormone concentrations were measured and several anterior pituitary releasing tests were carried out in 39 brain dead patients. In addition, cerebral blood flow measurements were simultaneously performed. In almost all cases, the blood concentration of pituitary and hypothalamic hormones were above the sensitivity of the assay. Anterior pituitary releasing tests indicated that efficient functions of the hypothalamus were severely suppressed, while the normal secretory mechanism of the anterior pituitary was partially preserved in brain dead patients. Histological changes of hypothalamic neurons varied from barely detectable ghost cells to nearly normal cells even in the same case. Although, the remaining circulation seemed not to be sufficient enough to maintain integrated hypothalamo-pituitary function, as shown by the examinations of cerebral blood flow, the presence of hypothalamic hormones in the systemic circulation suggests that these hormones were released and carried from the hypothalamus by minimal flow which is preserved even after the diagnosis of brain death.

Adolescent↗
PubMed1993

Hyperaemia prior to acute cerebral swelling in severe head injuries: the role of transcranial Doppler monitoring.

Acute cerebrovascular congestion after a closed head injury is significantly related to intracranial hypertension. As an indirect method of cerebral blood flow measurement; transcranial doppler sonography (TCD) provides a rapid and noninvasive assessment of cerebral haemodynamics, including hyperaemic conditions. TCD examinations was serially performed in 35 patients with severe head injury with intact cerebral circulation; i.e. the mean flow velocity (MFV) patterns of the middle cerebral artery (MCA) did not show signs of cerebral circulatory arrest such as systolic spike, to and fro, or no flow. The results showed that the MFV of the MCAs and ipsilateral extracranial internal carotid arteries (ICAs) in 9 of these patients increased sharply and pulsatility index (PI) decreased during 48-96 hours after the injury. This was soon followed by patterns of high intracranial resistance, consistent with elevated intracranial pressure (ICP) in monitored patients and acute brain swelling on repeated computed tomographic (CT) scans. The correlation between increased MFVs, decreased PIs, and cerebral haemodynamic changes leading to acute brain swelling is discussed. The number of patients who ended with severe disability, vegetative state, or death was 66% in this group of 9 patients, compared to only 34% for the 35 patients overall with severe head injury. Though the morbidity and mortality rates largely depend on the primary injury, the presence of acute cerebral swelling aggravate the grave course in these patients. And the ability of TCD to monitor the hyperaemic state prior to oedema should lead us to adjust the therapy in order to minimize the secondary insult related to intracranial hypertension.

Adult↗
PubMed1993

Age, sex and source of hamster affect experimental cholesterol cholelithiasis.

In the present study, we examined the effect of the following factors on a hamster model of cholesterol cholelithiasis: (i) the source of the golden Syrian hamsters (Sasco, Omaha, NE or Charles River, Wilmington, MA), (ii) the sex of the experimental animals and (iii) their age (4 wk vs. 8 wk of age). All hamsters were fed a semipurified diet which contained cholesterol (0.3%) and palmitic acid (1.2%). No cholesterol gallstones formed in any of the female hamsters regardless of age or source. The 4-week-old male hamsters from Sasco had the greatest incidence of gallstones (93%). The 8-week-old male hamsters tended to have a lower incidence of cholesterol gallstones than the younger ones, regardless of the commercial supplier (67 vs. 93% for Sasco and 27 vs. 40% for Charles River). Female hamsters had higher liver and serum cholesterol levels than the male hamsters; Charles River hamsters had lower serum cholesterol concentrations than the Sasco animals. Total biliary lipid concentrations were highest in Sasco male hamsters, but biliary cholesterol (mol%) was lower in the males than in the females (4.2-4.5% vs. 6.1-7.1%) regardless of age. The cholesterol saturation indices were higher in the Sasco females than the corresponding males; these values were lower in the Sasco hamsters than the Charles River animals, regardless of age or sex. The male Sasco hamsters had a higher total biliary bile acid concentration (98.9 mg/mL) than the Sasco females (58.9 mg/mL) and the Charles River animals (24.6 mg/mL for males and 38.2 mg/mL for females). The percentage of chenodeoxycholic acid in bile was significantly lower, and the percentage of cholic acid was higher in all females as compared to males.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1993

Antigenic analysis of feline calicivirus capsid precursor protein and its deleted polypeptides produced in a mammalian cDNA expression system.

An entire open reading frame in a cDNA encoding the capsid protein gene of feline calicivirus (FCV) was subcloned into a mammalian expression vector. After transfection of the constructed plasmid (pMCV-II) into COS-7 cells, the expressed protein was detected by indirect immunofluorescence assay (IFA) using a panel of monoclonal antibodies (MAbs) to the capsid protein of FCV. All of the MAbs reacted with the transfected COS-7 cells in IFA. The 76 kDa capsid precursor protein was demonstrated in an immunoblot analysis, indicating that the translated precursor protein was not processed into the matured capsid protein in this expression system. Two in-frame deleted and a frameshift mutated cDNAs were generated by using restriction sites within the capsid protein coding sequence in pMCV-II to analyze the antigenic sites of the protein. The results of IFA using the MAbs and COS-7 cells transfected with the deleted or mutated cDNAs suggested that three neutralizing epitopes had a conformational nature and that the other four linear epitopes were related to 74 amino acid residues between positions 381 and 454 in the protein, in which high variation was known to be present among three strains of FCV.

Antibodies, Monoclonal↗
PubMed1993

Detection of feline immunodeficiency virus proviral DNA in feline peripheral blood mononuclear cells by the nested two-step polymerase chain reaction.

The polymerase chain reaction (PCR) was applied to detect feline immunodeficiency virus (FIV) proviral DNAs in primary peripheral blood mononuclear cells (PBMC). Suitable conditions for PCR amplification were examined to obtain highly sensitive and specific results by simple staining in agarose gel. Specific amplification of FIV proviral DNA in PBMC DNA of FIV-infected cats was achieved by a nested two-step PCR that amplified the DNA first with outer primers and then with inner primers nested within the first primers. PCR amplification using different primers indicated that those based on the gag sequence of the FIV/TM2 strain isolated in Japan were suitable for the detection of FIV genomes in naturally infected Japanese pet cats. By the nested two-step PCR with mixed gag primers of TM2 and Petaluma, isolated in the USA, we could detect FIV genomes in all 11 primary PBMC samples from FIV-seropositive cats tested. The PCR protocol developed here is sensitive and specific for molecular detection of FIV infection in cats.

Animals↗
PubMed1993

Feline immunodeficiency virus gene expression: analysis of the RNA splicing pattern and the monocistronic rev mRNA.

The transcription pattern of the feline immunodeficiency virus (FIV) genome in a feline CD4+ cell line was examined. In addition to the genomic RNA (9.2 kb), at least five FIV-specific transcripts [5.2, 4.4 (doublet), 1.7 and 1.4 kb] were detected by using subgenomic restriction enzyme fragments of an FIV molecular clone or FIV-specific oligonucleotides as probes. Among these transcripts, the 9.2, 5.2 and 4.4 (doublet) kb mRNAs were not expressed in the cytoplasm of cells transfected with a rev- mutant. To determine the location of splice junctions in the FIV genome, we used PCR to amplify and clone cDNAs corresponding to the viral mRNAs from infected cells. The region between pol and env was found to contain at least two splice donor and three splice acceptor sites. Two splice acceptor sites were detected in the 3' region of env. By hybridization analysis and sequencing of cDNA clones, it was revealed that the medium sized mRNAs are derived from a single splice event, with different splice acceptor sites, and that the two smaller transcripts are doubly or triply spliced mRNAs. Our results demonstrate a complex pattern of alternative splicing of FIV mRNAs. Furthermore, we identified monocistronic rev mRNA species that employ a unique splice acceptor site.

Amino Acid Sequence↗
PubMed1993

The AP-1 binding site in the feline immunodeficiency virus long terminal repeat is not required for virus replication in feline T lymphocytes.

Sequences of 31 bp containing putative AP-1 and AP-4 binding sequences in the U3 region of the feline immunodeficiency virus (FIV) long terminal repeat (LTR) were deleted and the basal promoter activity of the LTR was measured by the chloramphenicol acetyltransferase (CAT) assay. The activity of the FIV LTR was reduced in Felis catus whole foetus 4 (fcwf-4) cells and Crandell feline kidney cells by this deletion. Cotransfection of murine c-Fos or c-Jun expression plasmids with the FIV LTR-CAT reporter plasmid into fcwf-4 cells revealed that FIV LTR could be activated by c-Fos but not c-Jun in the cells. The mutated LTR was introduced into an infectious molecular clone of FIV and the replication rate and the cytopathogenic activity of the mutant were compared with those of the wild-type in two feline CD4-positive T lymphoblastoid cell lines. It was found that the rate and activity of the mutant were almost the same as those of the wild-type. From these data, we conclude that the 31 bp fragment is important for achieving maximal expression of the FIV genome, but not required for the replication of FIV in feline T lymphocytes.

Animals↗
PubMed1993

The feline immunodeficiency virus ORF-A gene facilitates efficient viral replication in established T-cell lines and peripheral blood lymphocytes.

Frameshift mutants corresponding to all of the identified open reading frames of feline immunodeficiency virus, including the ORF-A gene, which has an unknown function, were constructed in vitro. Upon transfection into cells, no significant difference between the phenotypes of ORF-A mutant clones and those of wild-type clones was demonstrated. Although only ORF-A mutant virus among all mutant viruses from transfected cells showed infectivity in established T-cell lines, the replication and propagation of the ORF-A mutant virus were efficiently reduced compared with those of the wild-type virus. Moreover, the loss of the function of the ORF-A gene resulted in a severe defect in productive infection in primary peripheral blood lymphocytes both in the amount of reverse transcriptase activity produced and in core protein expression. These findings demonstrate that the ORF-A gene of feline immunodeficiency virus is required for efficient viral replication and suggest that the ORF-A gene is likely to be important for natural infection.

Animals↗
PubMed1993

Effect of 12-O-tetradecanoylphorbol-13-acetate on expression of cell surface antigens in two subclones of human leukemia K562 cells.

Two subclones (K562-L and -H) were previously isolated from K562 human leukemic cells according to hemoglobin production: K562-L was expressed in less than 5% and K562-H in more than 90% of dianisidine positive cells. 12-O-Tetradecanoylphorbol-13- acetate (TPA) suppressed the expression of the erythrocytic (glycophorin A) and myelocytic (CD11b) antigens in K562-L, but increased the expression of these antigens in K562-H. TPA increased the megakaryocytic (CD61) antigens in both cells. These findings suggest that there are distinct TPA responsible factors in K562-L and -H on the expression of the erythrocytic and myelocytic antigens.

Antigens, Surface↗
PubMed1993

Cloning and characterization of K562 cells on hemoglobin synthetic activity.

Two clones of the K562 human leukemic cell line were isolated according to hemoglobin (Hb) expression. One clone was expressed less than 5% (K562-L) and the other more than 90% (K562-H). The two clones did not exhibit any difference in cell growth or cell cycle. However, the Hb expression of K562-H cells was reduced by succinylacetone (S.A.). The above results suggested that the difference in the Hb production of K562-L and K562-H cells depended on the heme synthetic activity. On the other hand, glycophorin A was expressed to a greater extent on K562-L cells than on K562-H cells. These findings suggested that heme synthesis and the expression of glycophorin A on K562 cells were not always related. The CD11b and the CD61 were also expressed to a greater extent on K562-L cells than on K562-H cells, but the CD34 was not expressed on these cells.

Antigens, CD↗
PubMed1993

Analysis of a common antigenic epitope in Bacillus cereus flagellar fraction.

The strain-specific antigenicity between Bacillus cereus decreased but the common antigenicity did not change, when the flagellar antigen was treated with pH 2. Flagellar antigen of B. cereus H.1 was separated into two fractions by gel chromatography, one with a specific antigenicity (P1 fraction), and the other with a common antigenicity (P2 fraction). It was revealed that a common antigenic epitope of the P2 fraction was detected on a 61 kDa protein by further purification using a Mono Q column. This common antigenicity of flagella was increased by treatment with sodium dodecyl sulfate (SDS) and 2-mercaptoethanol, suggesting that a common antigenic epitope exists inside the flagellar component.

Antibodies, Monoclonal↗
PubMed1993

Ventilatory anaerobic threshold before and after cardiac valve surgery.

The purpose of this study was to objectively assess exercise tolerance before and after cardiac valve surgery by using an objectively determined ventilatory anaerobic threshold (AT). Nine patients (mean age: 38.2 +/- 8.1 years) with predominantly mitral regurgitant lesions were studied by a symptomatic maximal treadmill exercise test which included a determination of AT. The mean lengths of time from preoperative exercise testing to cardiac surgery, and from surgery to postoperative exercise testing were 5.9 +/- 4.0 and 12.1 +/- 8.3 months, respectively. The determination of AT on data plots was performed after blinding to patient identification and pre- vs postoperative status. After surgery, the clinical symptoms and NYHA class improved significantly with a decrease in the cardio-thoracic ratio and echocardiographic diastolic dimensions. The mean peak VO2 (ml/kg/min) increased significantly from 20.2 +/- 7.1 to 29.7 +/- 7.9 (p < 0.01). Together with these changes, AT (ml/kg/min in VO2) increased from a mean of 14.8 +/- 4.8 to 22.8 +/- 5.5 (p < 0.01). In conclusion, symptomatic improvement and an increase in peak oxygen uptake after cardiac valve surgery were accompanied by a significant increase in the objectively determined AT. AT determined in a blind manner provides an objective means of evaluating exercise tolerance when a double-blind intervention cannot be performed.

Adult↗