Biomedical subjects

N Yamaguchi

Publications and source records attributed to N Yamaguchi.

At least 253 records · Page 14Linked to original sources

PubMed1996

Analysis of CSK homologous kinase (CHK/HYL) in hematopoiesis by utilizing gene knockout mice.

CHK/HYL is a non-receptor tyrosine kinase that belongs to CSK (C-terminal Src kinase) family. Northern blotting and RT-PCR analyses showed that CHK/HYL was expressed in large spectrum of hematopoietic cells except for erythroid cells and brain. To explore the function of CHK/HYL in hematopoietic cells, we generated CHK/HYL deficient mice. The mutant mice were apparently normal and fertile, while CSK knockout mice died until E11.5 from a defect in the neural tube formation. Hematological observations including blood counts and FACS analysis showed no significant abnormalities in CHK/HYL mutant mice. CHK/HYL did not affect the activity of Src, Hck, and Fgr in cultured bone marrow cells, although CSK negatively regulates Src family kinases. These results suggest that CHK/HYL might not have the same function as CSK.

Animals↗

PubMed1996

Regional cerebral blood flow in patients with schizophrenia: relevance to symptom structures.

Regional cerebral blood flow (rCBF) was measured with technetium-99m hexamethylpropyleneamine oxime single photon emission computed tomography in 38 neuroleptic-treated schizophrenic patients. To improve the validity of the evaluation of symptomatology, we applied findings previously derived in a principal component analysis (PCA) of the Positive and Negative Syndrome Scale. The PCA had disclosed five orthogonal independent symptom structures (i.e., negative, hostile/excited, thought disordered, delusional/hallucinatory, and depressive components), and obtained factor scores for 70 schizophrenic subjects, including the present sample. Stepwise regression analysis elucidated some of the cortical regions in which relative rCBF predicted the severity of symptoms--namely, lateral and orbital prefrontal, lateral temporal, inferior parietal, and medial temporal regions. Findings suggested that symptom structures derived from PCA could prove helpful in elucidating the pathophysiology of neural mechanisms.

Adult↗

PubMed1996

Activation of GABAergic function necessary for afterdischarge generation in rat hippocampal slices.

Involvement of gamma-aminobutyric acid (GABA)-mediated function in epileptogenesis was studied in rat hippocampal slices, in which repetition of high-frequency electrical stimulation induced afterdischarges (ADs) to create an in vitro model for ictal activity. A GABAA receptor antagonist, bicuculline, fully blocked the ADs. On the other hand, the presence of bicuculline caused single stimuli to evoke short-duration epileptiform bursts, a well-known model for interictal activity. Therefore, we conclude that activation of GABAergic function appears to be necessary for ictal activity, while its dysfunction induces interictal activity, and propose a modification to the simple disinhibition hypothesis for epileptogenesis.

4-Aminopyridine↗

PubMed1996

The cDNA cloning of the hamster homologue of the human L6 gene.

The cDNA cloning and sequencing of a Syrian hamster gene that produces a surface antigen on cells transformed by the SV40 or BK virus are described. Sequence analysis showed that this gene is a member of the transmembrane 4 superfamily (TM4SF) and encodes the Syrian hamster counterpart of the human and the murine L6 antigens. The amino-acid sequences are highly conserved, being 71% identical among three species.

Amino Acid Sequence↗

PubMed1996

Predominant expression of a receptor tyrosine kinase, TIE, in hematopoietic stem cells and B cells.

A receptor tyrosine kinase (RTK), TIE (tyrosine kinase that contains immunoglobulin-like loops and epidermal growth factor [EGF] homology domains), is expressed in vascular endothelial and hematopoietic cells. We generated monoclonal antibodies (MoAbs) against the extracellular domain of TIE and a polyclonal antibody against the TIE carboxyterminus and used them to analyze expression of TIE in hematopoietic cells. Western blotting detected two forms of TIE protein with a molecular mass of 135 and 130 kD in hematopoietic and endothelial cells. Northern blotting analysis revealed that TIE was expressed preferentially in undifferentiated cell lines, especially when megakaryocytic, but not erythroid differentiation was induced. Reverse transcriptase-polymerase chain reaction (RT-PCR) showed that TIE was predominantly expressed in the human hematopoietic progenitor fraction, CD34+ cells. Fluorescence-activated cell sorting (FACS) showed that 42% of CD34+ and 17% of KIT-positive (KIT+) cells were TIE-positive (TIE+). The majority (81%) of the primitive hematopoietic stem cells, CD34+CD38- cells, were TIE+. Assays of progenitor cells and long-term culture-initiating cells (LTC-IC) showed that the TIE+ fraction contained more primitive cells than the TIE- fraction. Some TIE+ cells were in the CD34- fraction, which were CD19+ and CD20+ (B cells). These findings indicate that TIE has a unique spectrum of expression in primitive hematopoietic stem cells and B cells. Although its ligand has not been identified, TIE and its ligand may establish a novel regulatory pathway not only in early hematopoiesis, but also in the differentiation and/or proliferation of B cells.

Animals↗

PubMed1996

Characterization, molecular cloning and expression of megakaryocyte potentiating factor.

We examined whether the conditioned media of 64 kinds of cell lines, which have been maintained by a protein-free culture system, could produce megakaryocyte potentiating (Meg-POT) activity. In these cell lines, HPC-Y5, established from human pancreatic cancer, was shown to have the highest level of activity. The megakaryocyte potentiating factor (MPF) was purified from its conditioned medium by a combination of ion-exchange chromatography, gel filtration and reversed-phase HPLC. The purified MPF showed Meg-POT activity almost equal to human (Hu) interleukin 6 (IL-6) in the presence of murine IL-3 in a colony-forming assay with mouse bone marrow cells. The molecular weight of MPF was estimated to be 33 kDa by SDS-PAGE. Glycopeptidase F digestion and amino sugar analysis of the factor demonstrated that MPF is a glycoprotein carrying at least one N-linked sugar chain. The N-terminal amino acid sequence of MPF was determined to be Leu-Ala-Gly-Glu-Thr-Gly-Gln-Glu-Ala-Ala-Pro-Leu-Asp-Gly-Val-Leu-Ala-Asn. The same or homologous amino acid sequence has not been found in known proteins, demonstrating that MPF may be a novel cytokine which has Meg-POT activity. Then, we isolated HuMPF cDNA from an HPC-Y5 cDNA library using polymerase chain reaction and plaque hybridization methods. The HuMPF cDNA encodes a polypeptide consisting of 622 amino acids, including a signal peptide of 33 amino acids, and with a deduced molecular weight of 68 kDa, although HPC-Y5 cells secrete a 33 kDa form of HuMPF. HuMPF cDNA does not show any significant homology with other known sequences. The cDNA was expressed in COS-7 and Chinese hamster ovary (CHO) cells, and Meg-POT activity was detected in their culture supernatant. The COS-7 cells secreted only a 33 kDa recombinant (r)HuMPF, however, an additional 30 kDa form was detected in the culture medium of CHO cells. The 33 kDa rHuMPF from CHO cells showed Meg-POT activity, but not the purified 30 kDa rHuMPF. The difference in structure and activity between the 33 and 30 kDa forms of HuMPF was ascribed to the existence in the 33 kDa form of the C-terminal 25 amino acid residues. The expression of MPF mRNA was examined by Northern blot analysis using labeled MPF cDNA as a probe. MPF mRNA was detected in HPC-Y5 cells, with an approximate molecular size of 2.4 kb. We also examined the expression of the MPF gene in various human tissues, and the 2.4 kb band was detected only in lung. Then, the immunohistocytochemical analysis and in situ hybridization revealed that MPF-producing cells were identified as lung macrophages. MPF may exhibit other biological activities such as regeneration of the lung tissues.

Amidohydrolases↗

PubMed1996

Strain-dependent differences in the human cytomegalovirus replication origin.

The nucleotide sequence of the human cytomegalovirus replication origin of strain Towne (an AatII-SacI fragment corresponding to nt 90372-94637 of strain AD169) was determined and compared with AD169. Two differences were found in the nucleotide sequence level. One was the alteration of structural organization (a major difference): a 189-bp region of AD169 (nt 93337-93525) was directly repeated three times in Towne. The other was a change in the nucleotide residue level including substitution, insertion, or deletion (a minor difference). The divergent residues were predominantly localized within the nt 92591-92855 region of AD169. A replication assay revealed that replication ability remained after deletion of the 189-bp repeat but disappeared after either a 1.5-kb deletion from the AatII end or a 0.9-kb deletion from the SacI end. The 1.5- and 0.9-kb regions were relatively conserved. These results indicate that at least two regions essential for replication ability lie outside of both the relatively variable region and the 189-bp repeat and suggest that these essential regions support replication even with a spatial separation of either one (AD169) or three repeats (Towne) of the 189-bp region.

Base Sequence↗

PubMed1996

In vitro chemosensitivity of human pancreatic cancer cell lines.

CONCLUSION: These results show that eight pancreatic cancer cell lines are broadly sensitive to CDDP, and that chemotherapy for pancreatic cancer may improve the prognosis by more effective drug delivery to cancer cells. BACKGROUND: Chemotherapy for pancreatic cancer does not satisfactorily improve prognosis. The efficacy of chemotherapy depends on choosing sensitive anticancer drugs. METHODS: The in vitro chemosensitivity of eight human pancreatic cancer cell lines was investigated. Growth inhibition was measured by 3H-thymidine incorporation assays for doxorubicin hydrochloride (ADM), mitomycin C (MMC), cisplatin (CDDP), and etoposide (VP-16), and by Alamar Blue assay for (AB assay) 5-fluorouracil (5-FU). The cells were exposed to ADM, MMC, CDDP, and VP-16 for 2 h, and 5-FU for 72 h. From the dose-response curves, the 50% growth inhibition (IC50) level for each drug was estimated. RESULTS: The IC50 after 2 h of exposure of each of the eight kinds of cell lines to each anticancer drug ranged from 0.12-8.2 micrograms/mL for ADM, 0.066-25 micrograms/mL for MMC, 0.57-7 micrograms/mL for CDDP, 0.68-300 micrograms/mL for VP-16. IC50 after 72 h of exposure to 5-FU ranged from 1.8-23 micrograms/mL.

Aged↗

PubMed1996

Strength-duration curve of conductive spinal cord evoked potentials in cats.

Strength-duration curves of the ascending and descending conductive spinal cord potentials (SCEPs) in cats were obtained using constant current stimuli. For the formulation of numeric indices of excitability, the rheobase is defined as the minimal current strength below which response cannot occur even if the current continues, and the chronaxie is defined as the minimal duration of a current required to evoke the potential at twice the rheobase strength. The chronaxies and rheobases were calculated from the constructed strength-duration curves. The purpose of this study is to produce strength-duration curves and to evaluate the utility of chronaxies and rheobases for SCEPs. This study showed the following results: (1) there was a hyperbolic relationship between stimulus strength and stimulus duration at threshold values, similar to that seen in peripheral nerves; (2) the ascending and descending tracts of SCEP were mediated through the same pathway (based on the similar chronaxies and rheobases); (3) following spinal cord compression the chronaxie and rheobase increased significantly (P < 0.05), which is similar to peripheral nerve disturbance. However, the rheobase decreased significantly following slight spinal cord compression (P < 0.05) and systemic cooling (P < 0.01), and the strength-duration curve shifted showing a tendency towards decrease of the galvanic threshold, therefore, amplitude augmentation with slight compression and with decrease in temperature seems to contribute to the reduction of the threshold. The strength-duration curve, the chronaxie and the rheobase may be useful in assessing spinal cord function.

Animals↗

PubMed1996

Influence of medium-chain triglyceride-based lipid emulsion on rat polymorphonuclear cell functions.

Intravenous lipid emulsions are used as energy and essential fatty acids sources. There are controversial reports postulating in vitro and in vivo inhibitory effects of long-chain triglycerides (LCT) upon the blood polymorphonuclear leukocytes (PMNL) functions. In the present study the in vivo and in vitro effects of LCT and a physical mixture of medium- and long-chain triglycerides (MCT/LCT) emulsions were investigated on select PMNL functions, i.e., chemotaxis, phagocytosis, and bacterial killing. Blood from 20 rats was incubated with LCT, MCT, MCT/LCT, and saline, respectively. MCT-containing emulsions exhibited an inhibitory effect on all PMNL functions investigated, whereas LCT exerted an effect on the phagocytic index only. The administration of a parenteral supply of LCT, MCT/LCT, and saline for 30 h followed by saline infusion for 14 h in discontinuous mode did not influence any of the investigated PMNL functions. Similarly, continuous infusion over 44 h at increasing infusion rates up to 1.5 mL/h did not affect the PMNL functions. The obvious difference between in vitro and in vivo response of the PMNL model emphasizes the necessity for continuous monitoring of in vivo conditions. Appropriate interpretation of the data requires continuous circumspection and consideration of trials in a clinical setting.

Animals↗

PubMed1996

Simultaneous observation of regional cerebral blood flow and event-related potential during performance of an auditory task.

Reduced amplitude of the P300 component has been reported consistently in patients with neurological and psychiatric disorders. It is unclear, however, how such patients' cognitive dysfunction is related to their P300 abnormality. Further basic knowledge regarding neural substrates for P300 generation is required for gaining an understanding of the pathological significance of the P300 amplitude reduction. To determine the brain structures involved in P300 generation, we observed the event-related potential and the regional cerebral blood flow (rCBF) in 10 normal subjects performing an oddball discrimination of pure tones. The rCBF value was assessed quantitatively with the aid of single photon emission computed tomography using technetium-99m hexamethylpropylene amine oxime. During the task performance, significant activation was observed in the posterior superior temporal and inferior parietal regions of the right hemisphere. In addition, positive correlation of the task-related increase in rCBF with the simultaneously recorded P300 amplitude was observed in the right but not the left posterior superior temporal region. These findings indicate that activation of the right non-verbal auditory area might modulate P300 generation during pure-tone discrimination.

Acoustic Stimulation↗

PubMed1996

Cellular mechanisms of adaptation of grafts to antibody.

New, more effective, strategies of immunosuppression, including those recently designed to induce durable T cell tolerance (by grafting allogeneic or xenogeneic haematopoietic cells into T lymphocyte-depleted recipients), leave humoral rejection as the main barrier to transplantation of vascularized organs between different species. Recent experimental work indicates that hyperacute rejection can be prevented by manipulations of antibodies and complement. In this paper, we review the mechanisms governing the interaction of antibodies with cell surface antigens in vitro and in vivo, and their cellular consequences. Evidence is presented that, in appropriate conditions, antibodies can protect by effecting modification of graft antigenicity (adaptation or accommodation).

Animals↗

PubMed1996

Parasite prevalence in free-ranging farm cats, Felis silvestris catus.

No animals tested were positive for feline leukemia virus antigen and Chlamydia psittaci antibodies, but all were positive for antibodies to feline calicivirus (FCV), feline herpesvirus 1 (FHV1) and rotavirus. They had antibodies to feline parvovirus (96%), feline coronavirus (84% and cowpox virus (2%). Antibody to feline immunodeficiency virus (FIV) was found in 53% of animals, which were less likely to be infected with Haemobartonella felis, and had higher FHV antibody titres than cats without FIV. FCV was isolated from 51% cats and FHV1 and feline reovirus each from 4%. H. felis was present in 42% of animals, and antibody to Toxoplasma gondii in 62%. Clinical abnormality had a significant association with FIV and feline calicivirus infections, but sex, age, social status and feeding group had no significant association with prevalence of any parasites. Toxocara cati and Toxascaris leonina eggs were found, respectively, in 91% and 82% of animals tested.

Animals↗

PubMed1996

Immunogenicity of Actinobacillus actinomycetemcomitans serotype b-specific polysaccharide-protein conjugate.

To enhance the immunogenicity of capsular-like serotype b-specific polysaccharide antigen (SPA) of Actinobacillus actinomycetemcomitans, the purified antigen was coupled with bovine serum albumin via an adipic acid hydrazide functional group. The conjugate (SPA-bovine serum albumin) or the native SPA was administered subcutaneously or intranasally to BALB/c mice. Neither subcutaneous immunization with SPA emulsified in Freund adjuvant nor intranasal immunization with SPA and cholera toxin B subunit elicited any antibody responses to the polysaccharide antigen. High serum immunoglobulin M (IgM) and IgG responses to SPA were induced by subcutaneous immunization with SPA-bovine serum albumin in Freund adjuvant. Serum and salivary IgA responses to SPA in addition to IgM and IgG responses were induced by intranasal immunization with the conjugate and cholera toxin B subunit. To investigate the functional activity of SPA-specific antibodies, the opsonic activity of sera from BALB/c mice immunized with the conjugate was assessed by chemiluminescence assay using human polymorphonuclear leukocytes. Murine antisera efficiently opsonized A. actinomycetemcomitans serotype b in the assay, suggesting that antibodies to SPA of the organism might serve as a protective role.

Aggregatibacter actinomycetemcomitans↗

PubMed1996

[The effect of herbal medicines on the immunodeficient animals by injecting cancer chemotherapeutic agent-special reference to age related recovery of the function].

The acquired immunodeficiency of the host plays an essential role in the occurrence of infections even with low pathogenic bacteria. The increase of cases with MRSA and/or pseudomonas infection is one of the serious problems in hospital management in Japan for the elderly as well as pediatric patients. In the present study, mitomycin C (MMC)-treated hosts were prepared in young, adult and old mice to test the immunopotentiating action of the promising Chinese herbal medicine, Tohki-Rikuoh-Toh (TRT), Hotyu-Ekki-Toh (HET) and Juzen-Taiho-Toh (JTT). The effect of these herbal medicines on organ structure and its function in the MMC-treated hosts is clarified and discussed for medical use. 4-5, 8-10 and over 50 week old male C57BL/6 (Clea Japan Inc.) were injected with MMC at a dosage of 3 to 5 mg/kg to inhibit the bone marrow, thus creating a mouse model with reduced immunopotential. A powder extract of TRT, HET and JTT was administrated orally at a dosage of 500 mg/kg/day for seven consecutive days. The white cell number and the subset analysis were carried out by the FACS method. The bactericidal effect of the host was monitored by NBT reduction test. Peritoneal macrophages were prepared by the adherence technique. The macrophage phagocytic activity was examined by an ACAS system. After the administration of TRT, HET and JTT, the body weights recovered as much as 90%, especially in young animals which had been reduced to 75% of their normal values. After MMC-treatment, with the herbal medicines, HET was good for young mice while JTT was effective for the old ones. As for the effect on B cells, the plaque-forming cells (PFC) of spleen cells were compared among the groups. As a result, PFC in the HET group was 184% and the other two were 80 approximately 95% as compared to 76% in the MMC-treated ones. The number of white blood cells in the MMC-treated mice returned to 80% of their normal value. In addition, the phagocytic activity of macrophages increased to 50% although that of the non-treated group was only 20%. The phagocytic activity also recovered in the JTT and TRT of 131% to 95%, respectively compared to 11% in the MMC-treated control. When TRT, HET and JTT were administered orally to mouse models whose immunopotential had been inhibited, the herbal medicines activated both quantitatively and qualitatively, showing themselves to be effective interstitial medicines. In addition, the data from the animal models showed no side effects, confirming the complete efficacy of the drug. Moreover, there was no direct anti-bactericidal effect from these medicines, suggesting that the immunomodulating action of this medicine is host-mediated. It is interesting that quantitative and qualitative recovery were seen when HET was administered to MMC-treated young hosts while JTT was good for the old. With this investigation, the effective components are still unknown for different generations, and we need to clarify this aspect for better understanding of the efficacy of herbal medicines.

Acquired Immunodeficiency Syndrome↗

PubMed1996

Detection of specific bacterial cells with 2-hydroxy-3-naphthoic acid-2'-phenylanilide phosphate and fast red TR in situ hybridization.

An in situ hybridization technique with HNPP (2-hydroxy-3-naphthoic acid-2'-phenylanilide phosphate) and Fast Red TR was used to detect specific bacterial cells at the single-cell level. By this technique, the fluorescent signals of target bacterial cells were up to eight times more intense than those of standard fluorescence in situ hybridization with mono-fluorescein isothiocyanate-labeled oligonucleotide probes. This novel HNPP-Fast Red TR whole-cell hybridization technique is available for the identification of small or low-rRNA-content bacterial cells in the natural environment.

Bacteria↗

PubMed1996

Actinobacillus actinomycetemcomitans serotype b-specific polysaccharide antigen stimulates production of chemotactic factors and inflammatory cytokines by human monocytes.

Serotype b-specific polysaccharide antigen (SPA) was extracted from whole cells of Actinobacillus actinomycetemcomitans Y4 by autoclaving and purified by chromatography on DEAE-Sephadex A-25 and Sephacryl S-300. SPA induced the release of monocyte and leukocyte chemotactic factors by human monocytes. Polymyxin B had almost no effect on the release of monocyte chemotactic factor, but a monoclonal antibody against SPA markedly inhibited it. Human monocytes stimulated with SPA exhibited the increased mRNA expression of monocyte chemoattractant protein 1 (MCP-1) and a neutrophil chemotactic factor, interleukin-8 (IL-8). On the other hand, SPA induced the release of IL-1, IL-6, and tumor necrosis factor (TNF) and enhanced the expression of IL-1alpha, IL-1beta, IL-6, and TNF alpha (TNF-alpha) mRNAs. Human monocytes expressed MCP-1 and IL-8 mRNAs when stimulated by human recombinant IL-1alpha, I1-1beta, IL-6, and TNF-alpha, suggesting that these inflammatory cytokines induced by SPA might participate in the production of chemotactic factors in human monocytes.

Aggregatibacter actinomycetemcomitans↗

PubMed1996

Selective hypoglycemia in the liver induces adrenomedullary counterregulatory response.

The present study was designed to investigate adrenal medullary responses to a selective regional hypoglycemia in the liver of dogs with hepatic cross-perfusion. The liver of recipient dogs (Rc) was perfused with vena caval and aortic blood of donor dogs (Dn) through the portal vein and hepatic artery, respectively. Total hepatic venous blood of Rc was returned to Dn through the left jugular vein. Upon the cross-perfusion, glucose (Glc, 5%) was infused at an average rate of 3.5 +/- 0.2 mg.kg-1.min-1 (n = 12) in Rc to compensate the loss of hepatic Glc delivery into the systemic circulation. Insulin (5.0 IU/kg i.v.) was administered to Dn followed by infusion with an average rate of 0.95 +/- 0.17 IU kg-1.min-1 (n = 6), and this served as the hepatic hypoglycemic group. Saline was similarly administered to Dn, which served as the normoglycemic control group. In the hepatic hypoglycemic group, aortic and vena caval Glc levels in Dn, which represent Glc concentrations entering the liver of Rc, decreased from 129.9 +/- 7.1 and 122.5 +/- 7.8 to 44.6 +/- 6.1 and 38.0 +/- 5.9 mg/dl (P < 0.05) 45 min after insulin administration, respectively. During this regional hepatic hypoglycemia in Rc, the systemic glycemia being kept within a normal range, adrenal epinephrine and norepinephrine output increased from 245.5 +/- 55.8 and 39.1 +/- 9.9 to 618.9 +/- 180.4 and 134.3 +/- 52.7 ng/min (P < 0.05), respectively. By contrast, aortic Glc and insulin levels in Dn of the normoglycemic control group remained unchanged, as did adrenal epinephrine and norepinephrine output in Rc. The results indicate that the regional hepatic hypoglycemia can significantly increase adrenal catecholamine secretion even during systemic (central) normoglycemia. The study suggests that the hepatoadrenal Glc counter-regulatory reflex may be functionally implicated in insulin-induced hypoglycemia.

Adrenal Medulla↗