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Biomedical subjects

K Sakai

Publications and source records attributed to K Sakai.

At least 1,099 records · Page 61Linked to original sources
PubMed1987

Susceptibility of human glial cells to infection with human immunodeficiency virus (HIV).

Three human brain-derived cell lines (including two of astrocytic origin) were exposed in vitro to the human immunodeficiency virus (HIV), the etiologic agent of immunodeficiency in AIDS. In all three lines, HIV transcripts were detected by in situ hybridisation in 20-30% of cells 48 h after infection. Synthesis of virus gag gene products p24 and p55 was demonstrated by immunoblotting. No cytopathic effects typical of HIV-infected human T lymphocytes were observed. Our data indicate that HIV is neurotropic, and support the hypothesis that this virus may infect astrocytes in the brain.

Antibodies, Monoclonal↗
PubMed1987

Transglycosylation reaction of a chitinase purified from Nocardia orientalis.

Chitinase from the culture filtrates of Nocardia orientalis IFO 12806 was purified to apparent homogeneity by precipitation with ammonium sulfate followed by successive chromatography on CM-Sephadex and Bio-Gel P-60, and finally by affinity chromatography on a phenyl-Sepharose CL-4B column. The enzyme, which is essentially a hydrolase, also catalyzed a transglycosylation reaction on tetra-N-acetyl-chitotetraose (GlcNAc)4 and penta-N-acetyl-chitopentaose (GlcNAc)5. The enzyme converted the tetrasaccharide into hexa-N-acetyl-chitohexaose (GlcNAc)6 (21%) and di-N-acetyl-chitobiose (GlcNAc)2 (63%) as the major products. The corresponding values for penta-N-acetyl-chitopentaose (GlcNAc)5 were hepta-N-acetyl-chitoheptaose (GlcNAc)7 23% and tri-N-acetyl-chitotriose (GlcNAc)3 59%. The rate of the transglycosylation depended on the temperature, the concentration of substrate and the pH.

Chitinases↗
PubMed1987

Peptidergic hypothalamic afferents to the cat nucleus raphe pallidus as revealed by a double immunostaining technique using unconjugated cholera toxin as a retrograde tracer.

Using a double immunostaining technique with unconjugated cholera toxin (CT) as a retrograde tracer, we have demonstrated in the cat that the nucleus raphe pallidus receives two major afferent projections from the hypothalamus: the preoptic periventricular nucleus; and the peri- and paraventricular zones of the posterior hypothalamic area. Some CT-labeled neurons in the preoptic periventricular nucleus showed Met-Enk-like immunoreactivity, while many CT-labeled neurons in the posterior hypothalamic area presented either corticotropin-releasing-factor-like or Met-Enk-like immunoreactivity.

Afferent Pathways↗
PubMed1987

Experimental allergic encephalomyelitis mediated by murine encephalitogenic T cell lines specific for myelin proteolipid apoprotein.

T cell lines specific for bovine myelin proteolipid apoprotein (PLP) were established from SJL/J mice. The line cells bore surface phenotypes of T helper/inducer cells (Lyt-1+, Lyt-2-, L3T4+) and responded well to bovine, rat, and guinea pig PLP but not to myelin basic protein. One line responded to major PLP, and another responded to both major PLP and DM-20, which are the two major intrinsic membrane proteins of the central nervous system (CNS) myelin. Intraperitoneal inoculation of 4 to 30 X 10(6) PLP-activated line cells followed by injection of pertussis vaccine induced acute inflammatory disease of the CNS, with typical clinical signs of EAE mostly in a week in recipient mice that had been treated with low-dose irradiation. Almost all animals recovered completely, and two of the 12 animals relapsed 42 or 75 days after inoculation. The lesions were restricted to the CNS and were characterized by perivascular and parenchymal infiltration of inflammatory cells, fibrin deposit, and demyelination. In the severe lesions, axons were also damaged. These observations suggest that PLP is a definite encephalitogen, and PLP-sensitized effector T cells induce inflammatory demyelination in the CNS.

Animals↗
PubMed1987

Recognition of alloantigens and induction of experimental allergic encephalomyelitis by a murine encephalitogenic T cell clone.

In this communication we report a SJL/J (H-2s, Mlsc)-derived encephalitogenic T cell clone 4b.14a which has dual specificities for myelin basic protein/I-As and allogeneic H-2Ik gene products. Monoclonal antibodies specific for public class II major histocompatibility complex (MHC) determinants (Ia.17, I-Ak, r and Ia.7) and anti-L3T4 antibody inhibited the response of the clone 4b.14a to alloantigens, but a monoclonal antibody specific for a private determinant on I-Ak (Ia.2) did not inhibit the response. Although this clone proliferated in response to allogeneic spleen cells expressing H-2Ik determinants regardless of disparate Mlsa, b, c, d alleles, CBA/N cells (H-2k, Mlsnull) failed to stimulate the clone 4b.14a. These results suggest that recognition of allogeneic class II MHC molecules by this clone requires recognition with non-MHC gene products such as Mls. In addition, the clone 4b.14a stimulated by alloantigens could mediate clinical signs of experimental allergic encephalomyelitis in syngeneic recipients. However, interleukin 2 of rat spleen cell origin alone failed to activate the clone cells to make them encephalitogenic, though it could make them proliferate. The significance of these findings for T cell recognition and activation is discussed.

Animals↗
PubMed1987

Modified versus classical Blalock-Taussig shunts for congenital cyanotic heart diseases: a comparison of long-term results.

Between March 1977 and December 1984, 103 Blalock-Taussig shunts were performed on 88 patients. Included in this study were 40 patients who underwent the modified BT shunt and 63 patients who underwent the classical BT shunt. 13 of the modified BT shunts (33 per cent) and 18 of the classical BT shunts (29 per cent) were performed during infancy and 10 of the modified BT shunts (25 per cent) were performed on patients under the age of 3 months. EPTFE grafts of varying sizes were used in the patients who underwent modified BT shunts--4 mm in 14 cases, 5 mm in 15 cases and 6 mm in 11 cases, respectively. The early mortality rate was 11 per cent (3 deaths) in the group who had modified BT shunts and 8 per cent (5 deaths) in the group who had classical BT shunts. Over a follow-up period of 6 years, 6 shunt failures were diagnosed in the modified BTS group by auscultation and/or angiographic study, and during a follow-up period of 8 years, 12 shunt failures were diagnosed in the classical BTS group. The patency rate 3 years after surgery was 88.8 per cent in the modified BTS group and 78.0 per cent in the classical BTS group. The patency rate 5 years after surgery was 88.8 per cent in the modified BTS group and 75 per cent in the classical BTS group.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1987

Light and electron microscopical demonstration of c- erB-2 gene product-like immunoreactivity in human malignant tumors.

C-erbB-2 is a human protooncogene homologous with the well-known c-erbB. Genes and gene products of the EGF receptor and c-erbB are known to be closely related and to be closely homologous in their intracellular domain. Inspection of the deduced amino acid sequence suggested that the c-erbB-2 gene encodes a receptor for a yet unidentified growth factor. An immunohistological study was performed by introducing an antibody raised in the rabbit by immunization with a synthetic peptide corresponding to a part of the intracytoplasmic domain of predicted gene product. Specimens from 13 normal human organs, fresh frozen tissue from 41 surgically excised human malignant tumors and eight cell lines maintained in nude mice were studied. Positive staining was found in 4 of the 41 (9.8%) malignant tumors. All of the positive tumors were adenocarcinomas and two adenocarcinoma cell lines were also positive. Amongst the normal human tissues, epithelial cells in stomach, small and large intestine were faintly stained. When the positively stained cell lines were studied by immunoelectronmicroscopy, the reaction was most prominent in the membrane of microvilli, but part of the nuclear membrane, the endoplasmic reticulum and the outer cell membrane were also stained. DNA and mRNA blot assays, as well as our immunoprecipitation test, revealed that immunohistologically positive cell lines bore amplified c-erbB-2 DNA, c-erbB-2 mRNA and 185 kD protein which is supposed to be the gene product, while negative cell lines did not.

Cell Line↗
PubMed1987

A human T-cell line resistant to cytopathic effects of the human immunodeficiency virus (HIV).

Infection of human helper T lymphocytes with the human immunodeficiency virus (HIV) results in a rapid induction of cytopathic effects and cell lysis. We isolated a variant of the human T-lymphoblastoid cell line, CEM, that is fully susceptible to HIV infection but resistant to virally induced cytopathic effects. Exposure of the cells, designated CR-10, to HIV resulted in the expression of viral antigens in 100% of cells within 6-9 days. Virus-infected cells remained fully viable and could be cultivated under standard culture conditions for a desired period of time. Parental CEM cells died within 9-12 days after HIV infection. Proviral DNA could be detected in the HIV-infected CR-10 cells by Southern blot and molecular hybridization 4-5 days after infection; the relative amount of proviral DNA reached maximum at Days 6-10 and remained stable during an 8-month follow-up period. Virus production by HIV-infected CR-10 cells was documented by electron microscopy and detection of reverse transcriptase activity in cell culture supernatants. HIV-infected CR-10 cells exhibited a down modulation of the OKT-3, OKT-4, OKT-4A, OKT-8, and OKT-11 T-cell surface markers, but not of the OKT-9 (transferrin receptor). One of the HIV persistently infected CR-10 cell clones has been kept in continuous culture for over 8 months. During this period, the cells remained fully viable, 100% positive for HIV antigens, and negative for most of the T-cell surface markers tested and continued to produce biologically active HIV. The CR-10 and HIV-infected CR-10 cell lines will be useful in studies on the biology of HIV and in the isolation and large-scale propagation of this virus.

Antibodies, Monoclonal↗
PubMed1987

A reliable technique of free vascularized sural nerve grafting and preliminary results of clinical applications.

A technique of harvesting a free vascularized sural nerve graft based on either the cutaneous branch of the peroneal artery or the muscular perforating branch of the posterior tibial artery is described. Anatomic dissections with dye injection studies confirmed the reliability of this blood supply to a 25 cm long segment of the sural nerve. The sural nerve can be sectioned into as many as four segments while safely maintaining each segment's vascularity through intact fascia. A skin monitor can be elevated with the nerve to monitor vascular patency. The free vascularized sural nerve was used to reconstruct 16 nerve defects in the upper extremity. All 13 skin monitors elevated have survived. Early follow-up (range, 2 to 31 months) has shown encouraging clinical recovery. Although our preliminary results are difficult to compare with other series, this technique appears promising in clinical circumstances when interfascicular nerve grafting is indicated but the recipient bed is heavily scarred and poorly vascularized.

Adolescent↗
PubMed1987

Preoperative left ventricular function: minimal requirement for successful late results of valve replacement for aortic regurgitation.

Postoperative survival and left ventricular function were studied in 62 patients who underwent aortic valve replacement for isolated, chronic aortic regurgitation between 1978 and 1985. The average follow-up period was 3.8 years. There were three in-hospital and six late deaths. Five (56%) of the nine postoperative deaths were of cardiac-related causes. The mean 7 year survival rate was 83 +/- 5%. Preoperative left ventricular end-systolic volume index was the most important indicator (p less than 0.001) for subsequent cardiac death. The 6.5 year survival rate was 92 +/- 4% for patients with an end-systolic volume index less than 200 ml/m2 compared with 51 +/- 16% for those whose index was greater than 200 ml/m2. None of the 48 patients with an end-systolic volume index less than 200 ml/m2 died of cardiac-related causes. Twenty-three of the 48 patients with an end-systolic volume index less than 200 ml/m2 (Group 1) and 6 of the 12 patients with a higher index (Group 2) underwent repeat catheterization 26 months postoperatively. Preoperative afterload, assessed by end-systolic wall stress, was elevated in both groups, but decreased postoperatively, becoming identical to the afterload in 20 normal control subjects. Although the preoperative ejection fraction was depressed in both groups, the great majority of patients in Group 1, compared with none in Group 2, exhibited normal ejection fraction postoperatively. Thus, in patients who recently underwent surgery for aortic regurgitation, satisfactory late results in both long-term survival and reversal of left ventricular dysfunction were obtained when the preoperative end-systolic volume index was less than 200 ml/m2.

Adolescent↗
PubMed1987

A unique specificity of a calcium activated neutral protease indicated in histone hydrolysis.

Calf thymus histones were found to be susceptible to a calcium-activated neutral protease [CANP: EC 3.4.22.17] which required a high concentration of calcium ions for its activity (mCANP). The susceptibilities of histones were in the order of relative degradation rate: H2B, H2A, and H3. The major peptide fragments released by CANP from H2A, H2B, and H3 were isolated and the cleavage sites were determined. Examination of amino acid sequences and environmental features around the cleavage site as well as kinetic analysis of the degradation process led us to the following conclusions about the mode of substrate recognition of mCANP: 1) The cleavage sites in histones could not be interpreted in terms of the primary structure around them. Thus, it seems unlikely that the specificity of CANP solely depends on its recognition of any specific amino acid residues or sequences. 2) The susceptible bonds were never located in the midst of either a hydrophobic or hydrophilic alignment of amino acid residues but in the vicinity of the boundary between hydrophilic and hydrophobic clusters. 3) Once a peptide fragment was generated by the proteolytic degradation, no further cleavage occurred even if the peptide still contained a bond corresponding to what was susceptible to CANP in an intact histone. This observation was interpreted to mean that CANP may recognize a certain higher order structure of its substrates.

Animals↗
PubMed1987

Affinity labeling of the allosteric site of fructose 1,6-bisphosphatase with an AMP analog.

D-Fructose 1,6-bisphosphatase [EC 3.1.3.11, FBPase] is one of the key enzymes in glyconeogenesis and its activity is controlled by various effectors such as substrate, AMP and ATP. To analyze this complex regulation system, we tried an affinity labeling of FBPase with an AMP derivative, since AMP is a potent allosteric inhibitor of this enzyme. The results obtained are as follows. 1. To determine the functional groups which are essential for AMP as an inhibitor, inhibitory activities of some AMP derivatives were examined. These derivatives modified at the purine ring or phosphate group lost the activity while one modified at the ribose ring retained the ability to inhibit FBPase. This shows that an affinity labeling reagent should be an AMP derivative in which the ribose ring is modified. 2. 2',3'-Dialdehyde AMP (dial-AMP) was prepared by periodate oxidation of AMP and was reacted with FBPase. Under appropriate conditions, 1 mol of the reagent was incorporated per mol of enzyme subunit with a concomitant loss of enzyme activity. The reaction was prevented by the presence of AMP but not of ATP. The heat-stability, the kinetic parameters and the UV-absorption spectrum of the modified enzyme were all the same as those of native FBPase in the presence of AMP. Thus it was concluded that the allosteric AMP site in FBPase was modified specifically.

Adenosine Monophosphate↗
PubMed1987

Industrialization and mental health in Japan--mental health of large enterprise employees in their 40s and 50s.

Some difficulties in dealing with the mental health of large company employees in their 40s and 50s are discussed based on the authors' experiences as infirmary psychiatrists over the last decade. Some characteristics of Japanese enterprise are introduced and explained, such as "Tanshin-Funin," "Madogiwazoku" and "Shukko," which are intimately related to the management system of modern Japanese companies. The most prevalent psychiatric disorders among company employees are briefly discussed. They are usually diligent and hard-working middle management employees at least until the disorder becomes manifest. Form the socio-psychiatric viewpoint, it is assumed to be of increasing importance to deal with such a large cohort of individuals working in large companies as one of the significant objects of contemporary hygienic activities.

Adult↗
PubMed1987

Electron microscopic evidence for epidermal growth factor receptor (EGF-R)-like immunoreactivity associated with the basolateral surface of gastric parietal cells.

Epidermal growth factor (EGF), in addition to its effects on cell growth, has a suppressive effect on gastric hydrochloride secretion. We recently demonstrated EGF-receptor (EGF-R)-like immunoreactivity on human gastric parietal cells by light microscopy. To reveal further the localization of this reaction an immuno-electron microscopical study was performed. 528IgG, an anti-EGF-R murine monoclonal antibody and a polyclonal anti-EGF antibody were employed for immunostaining using the avidin-biotin method. Positive reaction against 528IgG was shown mostly on the outer membrane of parietal cells, except in the apical portion. No reaction was observed on most of the intracytoplasmic membranes including intracellular canaliculi, endoplasmic reticulum and other membranous components. In the basillar portion, the 528IgG-positive parietal cell membrane formed labyrinthine interdigitations. No reaction against anti-EGF was demonstrated in any of the gastric mucosal cells, although a reaction was clearly shown on salivary gland cells. These findings suggest a blood-mediated direct action of EGF on parietal cells.

Cell Membrane↗