Biomedical subjects

M Nakai

Publications and source records attributed to M Nakai.

At least 127 records · Page 7Linked to original sources

PubMed1997

Basal forebrain and cerebral cortical muscarinic receptors mediate increase in cortical blood flow provoked by periaqueductal gray matter.

The midbrain periaqueductal gray matter has been identified as a reflex centre located uppermost in the central organization of diverse defensive reactions. We recently found that when activated, the caudal third of the lateral periaqueductal gray was also capable of provoking a marked increase in cortical blood flow. The response may be the combined outcome of a flow increase of nitrergic origin and that coupled to a possible concomitant cortical activation. In the present study, we attempted to clarify the neural substrates for mediation of the increase in flow (observed by laser-Doppler flowmetry), in 49 anaesthetized, artificially ventilated, and cervically cordotomized rats. The flow increase provoked by stimulation of the particular subdivision of the periaqueductal gray with N-methyl-D-aspartate (1 mM, 100 nl) was unaffected by i.v. pentolinium tartrate (10 mg/kg), suggesting little contribution by the cerebrovasodilator parasympathetic nervous system to the response. The response was abolished by i.v. or topical cortical administration of scopolamine hydrobromide (3.16 mg/kg or 1.0 mM, respectively). Placement of bilateral lesions in the basal forebrain with alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (15 mM) impaired the cortical choline acetyltransferase activity and attenuated the flow response. Overall, we suggest that the cholinergic corticopetal neurons of the nucleus basalis of Meynert and cortical muscarinic receptors may form a principal efferent arm of a central circuitry emanating from the subdivision of the periaqueductal gray, in the mediation of the increase in cortical blood flow and possible cortical activation.

Animals↗

PubMed1997

Malignant lymphoma of the mandible: report of a case.

Extranodal malignant lymphoma is relatively rare. When it occurs in the oral region, it is sometimes misdiagnosed as inflammatory disease. This report details a case of malignant lymphoma that involved the fight mandibular region.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1997

Detection of Epstein-Barr virus DNA in virus-infected cells by electron microscopic in situ hybridization.

We describe a procedure for in situ hybridization using a biotinylated Epstein-Barr virus (EBV) sequence with detection at the light and electron microscopic levels. In situ hybridization using an immunogold-silver staining detection system was used to identify biotinylated DNA probes in cell smears and in Lowicryl K4M-embedded EBV-infected and -noninfected cell lines. At the light microscopic level, the reaction product of hybridized EBV DNA sequence seemed to be located mainly in the nuclei. The labelling was dependent on the cell strains. However, at the electron microscopic level, the reaction product was evident as spots or clusters distributed not only in the nuclei of EBV-infected cells but also in the cytoplasm and extracellular particles. These findings suggest that immature particles in the cytoplasm contain EBV DNA. This procedure can be applied to the observation and identification of virus infection.

Biotinylation↗

PubMed1997

Establishment of a murine model for metastasis of cytokine-producing tumor to the brain.

The A375 cell line, derived from human malignant melanoma, has characteristics of interleukin-6 (IL-6) production. By using this cell line, we have investigated a murine metastasis model of IL-6-producing tumors to the brain by injecting A375 cells directly into the left cardiac ventricle. Nude mice were anesthetized with intraperitoneal injection of pentobarbital sodium. Next, A375 cells suspended in phosphate-buffered saline (PBS) were injected into the left cardiac ventricle of mice. An intracardiac injection of 10(5) cells developed tumor colonies in the brain after 4 to 6 weeks. Metastatic cells were found in every lobe of the brain. An immunocytochemical study revealed IL-6 production by A375 cells at the metastatic sites in the brain. By the transfection of genes encoding proteins into A375 cells, a novel model of protein expression in the brain in vivo could be constructed. Our system does not require great skill. Our experimental model will facilitate future studies of the local effects of proteins in the brain.

Animals↗

PubMed1997

Mutational analysis of human immunodeficiency virus type 1 (HIV-1) accessory genes: requirement of a site in the nef gene for HIV-1 replication in activated CD4+ T cells in vitro and in vivo.

Human immunodeficiency virus type 1 (HIV-1) accessory genes including nef, vif, and vpr are important factors that determine the replication and pathogenesis of HIV-1. The state of activation is also important for the replication of HIV-1. We evaluated the properties of nef-, vif-, and vpr-minus macrophage-tropic HIV-1(JR) CSF in primary CD4+ Th1- or Th2-like cell cultures which had been activated through CD3 molecules in the presence of interleukin-2 (IL-2) and IL-12 (Th1-like culture) or IL-4 (Th2-like culture), respectively. In activated Th1- or Th2-like cultures, replication of nef-minus HIV-1(JR-CSF) was markedly lower than that of wild-type HIV-1. Subsequent analysis by site-directed mutagenesis showed that (i) the presence of an acidic amino acid-rich domain (amino acid residues 72 to 75) in the Nef protein was critical for the enhancement of viral DNA synthesis, resulting in increased virus growth rate, and (ii) prolines that form part of Src homology 3 binding domain were not essential for viral replication. We also confirmed the importance of sites by using an HIV-1-infected animal model, the hu-PBL-SCID mouse system, representing HIV-1 replication and pathogenesis in activated CD4+ T cells in vivo. These results indicate that Nef accelerates viral replication in activated CD4+ T cells.

Amino Acid Sequence↗

PubMed1997

Possible different mechanism between amyloid-beta (25-35)-and substance P-induced chemotaxis of murine microglia.

The mechanism of murine microglial chemotaxis induced by amyloid-beta protein (A beta (25-35)) was investigated. A beta (25-35) dose-dependently stimulated microglial chemotaxis at concentrations between 100 pM and 10 nM. Substance P, a NK-1 agonist, stimulated chemotaxis at concentrations of 10 nM or more. GR-64349, a NK-2 agonist, and senktide, a NK-3 agonist, did not stimulate microglial chemotaxis. We examined whether homologous desensitization of chemotaxis would occur by A beta (25-35). The chemotactic effect of microglia was homologously desensitized by 10 nM A beta (25-35). On the other hand, substance P at 10 nM did not desensitize the A beta (25-35)-induced chemotaxis. These data show that A beta (25-35) induces the chemotaxis of microglia probably through a receptor other than the NK-1 receptor.

Amyloid beta-Peptides↗

PubMed1997

A study on the biological significance of midregion and intact parathyroid hormone in hemodialysis patients.

In this study, we investigated the relationship between the concentrations of intact parathyroid hormone (i-PTH) and midregion PTH (m-PTH) measured by an immunoradiometric assay and a radioimmunoassay, respectively, versus various demographic and biochemical parameters, bone mineral density (BMD) of the lumbar spine (LS) and radius, and the radiographic findings of osteosclerosis and aortic calcification in hemodialysis (HD) patients. m-PTH correlated positively and more significantly with serum calcium (Ca), serum phosphorus (P), Ca-P solubility products (Ca x P) and LS-BMD than i-PTH did (P = 0.024 vs. 0.531, 0.001 vs. 0.061, 0.0001 vs. 0.125, and 0.017 vs. 0.284, respectively). A positive correlation between the percent changes in serum P over the 1-month measurement period and those in m-PTH rather than in i-PTH was also observed (P = 0.021 vs. 0.869). These data indicate than m-PTH is distinct from i-PTH in its positive correlation with serum Ca, serum P, Ca [symbol: see text] P and LS-BMD in HD patients. Since m-PTH is known to consist mostly of the midregion and carboxyl-terminal fragments of PTH in HD patients, the present study suggests that these PTH fragments may be biologically significant in the patients in vivo.

Adult↗

PubMed1997

[Coronary artery bypass grafting using arterial grafts in a patient with rheumatoid arthritis requiring steroid therapy].

We report a 58-year-old man with rheumatoid arthritis (RA) who underwent successful coronary artery bypass grafting (CABG) for stable angina after myocardial infarction. He had been receiving prednisolone for 9 years. Selective coronary angiography revealed 99% stenosis in the left anterior descending branch (LAD; seg. 6). Before going on cardiopulmonary bypass, the inferior epigastric artery (IEA) was anastomosed to the left internal thoracic artery (LITA) in end-to-side fashion. The LITA was anastomosed to LAD (seg. 7) and the IEA was anastomosed to the first diagonal branch (seg. 9). The postoperative course was uneventful and postoperative angiography showed both grafts were well patent. He is now doing well with no angina attack. The stumps of the LITA and IEA were examined pathologically with the atherosclerotic changes of both grafts relatively mild. We consider the arterial grafts are useful for CABG even in the patient with RA requiring steroid therapy.

Angina Pectoris↗

PubMed1997

[Surgical treatment of thoracic aorta for elderly patient].

From 1986 to 1996, 237 patients underwent surgical treatment of thoracic aorta in our institute. We classified them as follows: group 1 is 41 patients older than 75: group 2 is 196 patients younger than 74. The number of patients of elective surgery, emergent surgery for acute dissection type A and emergent surgery for rupture or impending rupture were 28, 9, 4 in group 1 and 123, 47, 26 in group 2. Operative death (within 30 days) of elective surgery, emergent surgery for acute dissection type A and emergent surgery for rupture or impending rupture were 1 (3.6%, MOF), 1 (11%, liver failure), 2 (50%, brain damage) in group 1 and 8 (6.5), 3 (6.4%), 9 (35%) in group 2, respectively. Hospital deaths (after 30 days and cannot discharge) were 3 (11%), 0.1 (25%) in group 1 and 3 (2.4%), 1 (2.1%), 1 (3.8%) in group 2. There was no significant difference between two groups. Survival rate of each group were 48% and 80% for five-year survival rate. Complications in elderly patients were common (88%). Respiratory insufficiency is the most frequent (51%). Otherwise survival rate of patients who had no surgical treatment of diseased thoracic aorta was reported poor by several researches. We will perform operation for elderly patients positively if we can get agreement of patients.

Acute Disease↗

PubMed1997

[Results of cardiac operation and thoracic aortic operation in patients aged 75 years or older].

A total of 121 patients aged 75 years or older underwent cardiac operation or thoracic aortic operation at our hospital between 1988 and February 1997. They were composed of 74 cases of ischemic heart disease, 22 cases of valvular disease, 1 case of myxoma, and 24 cases of thoracic aortic disease. Operative mortality rate was 13.5% in ischemic heart disease, 4.2% in valvular disease and myxoma, and 25% in thoracic aortic disease. In ischemic heart disease, the operative mortality rate was especially high in emergency operation for acute myocardial infarction. In thoracic aortic operation, further improvement should be made with regard to preoperative and intraoperative management.

Age Factors↗

PubMed1997

[Study on risk factors and late results of coronary artery bypass grafting for acute myocardial infarction].

Study was made on the operative results, risk factors, and late results of coronary artery bypass grafting (CABG) for acute myocardial infarction (AMI) conducted at our hospital. The subjects of the present study were 70 cases of AMI who underwent CABG during a period of five years from January 1991 to December 1995. They were composed of 61 males and 9 females whose mean age was 61.9 years. LMT disease was observed in 13 cases and preoperative shock in 18 cases. The mean aortic cross-clamp time was 64 minutes with the mean extracorporeal circulation time being 134 minutes and the mean number of grafts being 2.5. The mean preoperative-postoperative peak creatine kinase was 4479 IU/L. The number of operative deaths was 14 with a mortality rate of 20%. When compared with elective cases of CABG conducted during the same period with a mortality rate of 2.7%, the operative result of AMI was poor. The mortality rate by risk factor was 40% for age of 70 years or more, 46.2% for complication of LMT disease, 52.9% for preoperative shock, 58.3% for preoperative C.I. of less than 2.0, 80% for postoperative C.I. of less than 2.0, 28.2% for conduct of postoperative circulatory support, and 42.1% for peak creatine kinase of 5000 IU/L or more. Aortic cross-clamp time and reperfusion time (interval from onset of AMI to aortic declamp) were found not to be risk factors. Late death accounted for 5 cases including one case of cardiac death due to suspected AMI. Survival rate excluding operative deaths and hospital deaths was 98% in one year and 83.9% in five years. When compared to non cardiacevent cases, the survival rate of positive cardiac event cases was significantly poor. The operative results of severe myocardial ischemia cases represented by cases of complication of LMT disease were poor and it is considered that improvement of intraoperative myocardial protection and aggressive use of postoperative circulatory support are necessary in the future. The survival cases of those who could endure surgery was comparatively satisfactory, but when cardiac event developed, prognosis was poor and thus more rigid follow-up is considered to be necessary.

Age Factors↗

PubMed1997

Electronmicroscopic study of human herpesvirus 6-infected human T cell lines superinfected with human immunodeficiency virus type 1.

Human herpesvirus 6 (HHV-6) has been proposed as one of the co-factors responsible for the development of acquired immunodeficiency syndrome (AIDS) in human immunodeficiency virus (HIV) carriers. We analyzed the interaction between HHV-6 and HIV-1 in superinfected cells. Cell-free HIV-1 could superinfect human T cell lines, MT-4 and Molt-4, which had been previously infected with HHV-6. Both HHV-1 and HHV-6 replicated in the same cells. We observed two types of morphologically distinguished cells as early as 4 days after superinfection. One type (D) was degenerate cells with intracellular and extracellular HHV-6 and with less HIV-1 virions. The other type (I) was relatively intact cells with both HIV-1 and HHV-6 virions. Replication of HIV-1 was more active in the type I as compared with type D cells. The level of HIV-1 reverse transcriptase (RT) activity in the culture supernatants of cells superinfected on day 0 declined after day 7, while that in the supernatants of cell cultures infected with HIV-1 alone remained high between days 12 and 40. These results suggest that the superinfection of the HHV-6-infected cells with HIV-1 may induce a degenerative process in these cells.

Cell Line, Transformed↗

PubMed1997

[Adenocarcinoma occurring 37 years after augmentation ileocystoplasty for tuberculous bladder atrophy: report of a case].

A 55-year-old woman was admitted with urinary frequency. She had undergone augmentation ileocystoplasty due to tuberculous bladder atrophy 37 years previously. Cystoscopy revealed a tumor on the posterior wall which had been augmented with the ileum. Partial cystectomy and bladder reconstruction using a segment of ileum and ascending colon were performed. Gross inspection showed a 15 x 10 mm, papillary tumor on the ileal mucosa near the vesico-ileal anastomosis. Histologically, moderately differentiated adenocarcinoma infiltrating into the muscle layer was surrounded by the normal ileal mucosa. She has been free of recurrence for 2 years postoperatively. This is the 8th case of adenocarcinoma following augmentation ileocystoplasty reported in the Japanese literature.

Adenocarcinoma↗

PubMed1996

Human antibodies responsible for binding inhibition and polymerization inhibition of human immunodeficiency virus type 1 reverse transcriptase.

Using a solid-phase non-radioisotopic (non-RI) reverse transcriptase (RT) assay, antibodies inhibiting human immunodeficiency virus type 1 (HIV-1) RT activity (RTI antibody) were investigated for their ability to inhibit binding of RT to a template-primer and DNA polymerization. The RTI antibody inhibited the binding of RT to the template-primer (BI antibody), and directly reacted with the RT-template-primer complex and inhibited enzymatic activity (PI antibody). The RTI antibody interfered with formation of the RT-template-primer complex suggesting that it recognized the antigenic site involved in template-primer binding of RT molecules. Since deoxynucleotide triphosphates (dNTPs) blocked inhibition of the RT activity by the PI antibody, the antigenic site recognized by the PI antibody may be closely related to the dNTP binding site. The seropositivities of the BI and PI antibodies were 84.6% and 91.2%, respectively, in HIV-1-infected individuals; healthy individuals, HTLV-I-positive individuals, autoimmune disease patients and leukemia patients were all seronegative. No significant correlation of residual RT activities was observed when BI and PI antibodies were compared (r = 0.688). It is possible that the epitopes recognized by the BI antibody differs from those recognized by the PI antibody. The assays described are able to detect BI and PI antibodies in the sera of HIV-1-infected individuals.

Animals↗

PubMed1996

Efficient gene activation system on mammalian cell chromosomes using recombinant adenovirus producing Cre recombinase.

To develop a method for activating genes located on cell chromosomes, an on/off switching unit regulated by the site-specific recombinase Cre was constructed. The switching unit was designed to express firstly the neo gene and secondly the reporter lacZ gene by Cre-mediated excisional deletion of the neo gene. CV1 cell lines bearing the switching unit on a cell chromosome were isolated and activation of the lacZ gene was examined after infection with a Cre-producing recombinant adenovirus. In one cell line virtually 100% of the cells stably expressed the lacZ gene, whereas in another cell line lacZ-expressing cell populations reached only to about 90% and decreased after cell divisions. The Southern blot analyses showed that the latter type of cells contained a head-to-tail array of the switching units, and that consequently the lacZ-expressing units were excised from a cell chromosome and present as extrachromosomal circular DNAs. These results showed that the system offers efficient activation of genes introduced into cell chromosomes and that the organization of the reporter units are important for efficiency and duration of the activated gene expression.

Adenoviridae↗

PubMed1996

Nitrergic cerebral vasodilatation provoked by the periaqueductal grey.

The present study evaluated the contribution of nitric oxide to the increase in cerebral cortical blood flow that is provoked by chemical stimulation of the caudal third of the lateral periaqueductal grey (PAG), employing 48 anaesthetized rats with cervical cordotomy. Following topical application over the cortical surface, the inhibitor of nitric oxide synthase NG-nitro-L-arginine inhibited the response stereospecifically and achieved its maximal effect at 1 mM, when the response was reduced to 47 +/- 16% (n = 16). Since the PAG represents a principal site for the central organization of defence reactions, we suggest that nitric oxide may play a definitive role in the central regulation of the cerebral circulation, thereby participating in such important biological processes as the defensive reflex activity.

Animals↗

PubMed1996

Cytochrome f encoded by the chloroplast genome is imported into thylakoids via the SecA-dependent pathway.

In vitro import of the precursor of tobacco cytochrome f, which is is encoded by the chloroplast genome, into isolated pea thylakoids was analyzed. Upon incubation with thylakoids and a stromal fraction, the precursor of cytochrome f was efficiently imported into thylakoids. The imported cytochrome f was tightly integrated into the thylakoid membrane. Insertion of cytochrome f into the thylakoid membrane was blocked by nigericin, sodium azide, and antibodies against pea chloroplast SecA. These results suggest that cytochrome f utilizes the bacterial-type SecA-dependent pathway to be imported into thylakoids.

Adenosine Triphosphatases↗

PubMed1996

Expression of apolipoprotein E mRNA in rat microglia.

Apolipoprotein E (apoE) is a major risk factor for Alzheimer disease (AD), which is the most common cause of progressive dementing illness. ApoE has been postulated to be synthesized by astrocytes and taken up by microglia and neuronal cells. However, it remains unknown whether apoE is also produced by microglia in the brain. We analyzed apoE mRNA expression of microglia using a rat primary culture system. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis revealed expression of apoE mRNA in cultured rat microglia. By RT-in situ-PCR, microglia showed positive staining for the PCR product of apoE mRNA. These results indicated that apoE was biosynthesized in rat microglia. We suggest that microglia might be one of the sources of apoE in the brain, and that apoE synthesized in microglia might be closely related to the pathogenesis of AD.

Animals↗