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Biomedical subjects

M Fukuda

Publications and source records attributed to M Fukuda.

At least 1,081 records · Page 60Linked to original sources
PubMed1987

Freeze fracture study of the schizonts and merozoites of Leucocytozoon caulleryi.

The fine structure of the schizonts and merozoites of Leucocytozoon caulleryi was studied by the freeze fracture technique. Young schizonts were spherical, surrounded by a thick fibrous capsule and possessed numerous nuclei. The nucleus was surrounded by the outer and inner nuclear membrane. A number of nuclear pores were evident in the nuclear membranes. Advanced schizonts were characterized by the formation of cytomeres. Each cytomere was surrounded by a membrane. Several nuclei lay along the periphery of the cytomere. The protoplasmic face (P-face) of the membrane of the cytomere contained numerous intramembranous particles (IMP). The exoerythrocytic merozoites were surrounded by a two-layered pellicle consisting of the outer and inner membrane. During freeze fracturing, each of the two membranes could split along its hydrophobic interior to yield a total of four fracture faces. The P-faces of the outer and inner membranes were closely covered with evenly distributed IMP. The external faces (E-face) of these membranes had less IMP than the P-faces. The membrane architecture of the erythrocytic merozoites was similar to that of the exoerythrocytic merozoites. The erythrocytic merozoite was enveloped by an additional membrane probably derived from the plasma membrane of host cell.

Animals↗
PubMed1987

Bidirectional assembly of tobacco mosaic virus in vitro.

THE TIMING OF THE BIDIRECTIONAL GROWTH IN THE ASSEMBLY REACTION OF TOBACCO MOSAIC VIRUS HAS BEEN THE SUBJECT OF CONTROVERSY: Does elongation actually occur simultaneously to 5' and 3' ends or sequentially, first to the 5' end and then to the 3' end? To determine the timing of elongation toward the 3' end directly, using the S1 nuclease mapping method on a cloned cDNA with micrococcal nuclease-digested tobacco mosaic virus RNA, we analyzed encapsidation of the RNA region that was located downstream from the assembly origin. The results clearly showed that elongation toward the 3' end did not occur for at least the first 4 min. Actually it was first observed at 8 min. It is concluded that, in the first 5-7 min, a rapid elongation of the nucleation complex occurs only toward the 5' end of the RNA and that this gives rise to an intermediate particle 260 nm long. Furthermore, the lengths of the RNA that were protected against S1 nuclease digestion showed a clear banding pattern that had a spacing of approximately 100 nucleotides. This supports the hypothesis that the 20S aggregate is kinetically favored as the protein source for elongation to the 3' end.

Journal Article↗
PubMed1987

Molecular cloning of a human glycophorin B cDNA: nucleotide sequence and genomic relationship to glycophorin A.

Here we describe the isolation and nucleotide sequence of a human glycophorin B cDNA. The cDNA was identified by differential hybridization of synthetic oligonucleotide probes to a human erythroleukemic cell line (K562) cDNA library constructed in phage vector lambda gt10. The nucleotide sequence of the glycophorin B cDNA was compared with that of a previously cloned glycophorin A cDNA. The nucleotide sequences encoding the NH2-terminal leader peptide and first 26 amino acids of the two proteins are nearly identical. This homologous region is followed by areas specific to either glycophorin A or B and a number of small regions of homology, which in turn are followed by a very homologous region encoding the presumed membrane-spanning portion of the proteins. We used RNA blot hybridization with both cDNA and synthetic oligonucleotide probes to prove our previous hypothesis that glycophorin B is encoded by a single 0.5- to 0.6-kb mRNA and to show that glycophorins A and B are negatively and coordinately regulated by a tumor-promoting phorbol ester, phorbol 12-myristate 13-acetate. We established the intron/exon structure of the glycophorin A and B genes by oligonucleotide mapping; the results suggest a complex evolution of the glycophorin genes.

Amino Acid Sequence↗
PubMed1987

Kinetic studies of wheat carboxypeptidase-catalyzed reaction: differences in pressure and temperature dependence of peptidase and esterase activities.

A kinetic study of hydrolytic catalysis by wheat bran carboxypeptidase (carboxypeptidase W) was carried out using 3-(2-furyl)acryloyl-acylated (Fua-) synthetic substrates. This enzyme showed high esterase activity in addition to the intrinsic carboxypeptidase activity. The optimum pH for the peptidase activity (kcat/Km) was at pH 3.3 and the kcat/Km value decreased with increasing pH with an apparent pKa of 4.50, while the esterase activity increased with pH up to pH 8 with an apparent pKa of 6.04. Optimum pH's for kcat for the peptidase and esterase reactions were also very different and their apparent pKa values were 3.80 and 6.15, respectively. From a measurement of the pressure dependences of kcat and Km, the activation volumes (delta V not equal to) and reaction volumes (delta V), respectively, were determined. delta V not equal to for kcat was -7 to -8 ml/mol for peptidase and -2 to -3 ml/mol for esterase. These results lead us to propose that the peptidase and esterase activities of carboxypeptidase W are different not in the rate-determining steps in a common reaction pathway, but in the binding modes and/or catalytic site(s).

Atmospheric Pressure↗
PubMed1987

Developmental regulation of sialic acid modifications in rat and human colon.

Using high-pressure liquid chromatography (HPLC) and gas-liquid chromatography/mass spectrometry (GLC/MS), we have confirmed the existence of several sialic acid modifications in the adult rat and human colon. The major O-acetylated sialic acid in both species is 9-O-acetyl-N-acetylneuraminic acid; N-glycolylneuraminic acid is a major component of the adult rat colon. Both of these major modifications were found to be developmentally regulated during the perinatal period in the rat. The N-glycolyl modification is present prenatally and disappears rapidly in the postnatal period. It reappears in the preweanling period, reaching levels at weaning comparable to those found prenatally. In contrast, the 9-O-acetyl modification is very low prenatally, and undergoes a marked increase shortly after birth in both the rat and human colon. The difference in the kinetics of appearance of the two modifications suggests that they are independently regulated. Regulation of these modifications seems to be influenced by exposure to bacterial by-products or environmental stimuli. The N-glycolyl modification in the rat colon reappeared at weaning, a time of major change in enteral colonic substances. Spontaneously aborted human fetuses, including three with intrauterine infection at 27, 33, and 35 wk of gestation, showed adult levels of O-acetylation in colonic tissue. Also, although O-acetylation in freshly isolated colon tumor specimens was only somewhat lower than that in the adult normal colon, all established colon cancer cell lines studied showed minimal O-acetylation.

Abortion, Spontaneous↗
PubMed1987

Spontaneous persistent epithelial defects after cataract surgery.

The natural course of corneal epithelial erosions was studied retrospectively in patients who had undergone cataract extraction. Postsurgical epithelial defects occurred in 41 of 796 eyes (5.2%). No difference was noted in the incidence of corneal epithelial defects in eyes after intracapsular and extracapsular cataract extraction. Of the 41 eyes with postsurgical corneal erosion, 26 (63.4%) showed corneal epithelial defects by the fourth postoperative day. Two types of healing patterns were noticed: rapid healing, in which there was complete epithelial resurfacing within 4 days after the onset of corneal erosion, and prolonged healing, in which the period for complete epithelial resurfacing ranged from 6 days to 34 days. Since fibronectin has been reported to facilitate corneal epithelial migration and adhesion, we administered autologous fibronectin eyedrops in five cases in which corneal epithelial erosion developed after cataract surgery and epithelial defects persisted more than 7 days (except case 2). In all cases receiving fibronectin treatment, complete epithelial resurfacing occurred. In four of five eyes, fibronectin eye drops were effective in epithelial resurfacing within 3-9 days; in one eye, complete epithelial resurfacing took 23 days. The present results indicate that there are two types of epithelial erosion and that fibronectin eye drops might be one of the possible therapeutic approaches for the treatment of persistent epithelial defects. The weak adhesion of epithelial cells underlying basement membrane may be one of the causes of persistent epithelial defects after cataract surgery.

Adult↗
PubMed1987

Conjugates of catecholamines. VII. Synthesis and beta-adrenergic activity of peptide catecholamine conjugates.

A series of novel catecholamine derivatives has been prepared in which one of the N-methyl substituents of isoproterenol has been extended by a spacer consisting of a chain of four methylenes which terminates with an amide linkage to a peptide, the point of attachment being via the aromatic amino group of p-aminophenylalanine. In one of the derivatives, two catecholamines are attached to the same peptide in this manner. The peptides, which range in size from three to eight amino acid residues and contain phenylalanine, glycine, and L-alpha-amino-delta-hydroxyvaleric acid, were synthesized via stepwise and fragment condensation techniques. The beta-adrenergic agonist activities of the derivatives were evaluated in vitro by measuring the intracellular accumulation of cyclic AMP in S49 mouse lymphoma cells.

Adrenergic beta-Agonists↗
PubMed1987

Functional relations among inferotemporal cortex, amygdala, and lateral hypothalamus in monkey operant feeding behavior.

Neural activity in either the amygdala (AM) or lateral hypothalamus (LHA) was examined while monkeys obtained food as a reward for operant bar pressing. Neurons in the AM were tested before, during, and after reversible cooling of the inferotemporal cortex (ITCx). LHA neurons were tested similarly except that the cooling probe was located in the AM. Cooling probes were chronically implanted bilaterally over the dura of the anterior ITCx in one monkey and in the lateral part of the AM in two monkeys. The activity of 43 AM neurons was analyzed. Before ITCx cooling, each AM neuron was classified into one of four groups based on its response pattern: 6 neurons responded primarily to the sight of food, 11 responded primarily to the sight of nonfood objects, 21 responded to the sight of both food and nonfood (arousal related), and 5 neurons did not respond. ITCx cooling changed the spontaneous firing rate of 15 AM neurons (2 increased, 13 decreased). Responses to the sight of food and/or nonfood of two food-related, four nonfood-related, and seven arousal-related neurons were depressed, and responses of two nonfood-related and three arousal-related neurons were enhanced. Of 17 neurons that were normally food or nonfood specific, 8 became nondiscriminative during ITCx cooling. The activity of 55 LHA neurons was tested. Of these, 22 were food related, 6 responded primarily during ingestion, 22 were arousal related, and 5 did not respond. AM cooling changed the spontaneous firing rates of 21 LHA neurons (12 increased, 9 decreased). Visual responses of nine food-related neurons and two arousal-related neurons were depressed by AM cooling. Ingestion-related responses in the AM (3 of 6 food-related neurons) were not affected by ITCx cooling, but responses of three ingestion-related LHA neurons (3/6) were depressed by AM cooling. The data suggest that dynamic interactions among the ITCx, the AM, and the LHA are important in discriminating between food and nonfood, and, consequently, in the stimulus-reinforcement process, i.e., recognition of reward or no reward. The results are discussed in terms of known anatomical data and behavioral evidence from earlier lesion experiments.

Amygdala↗
PubMed1987

Differential polycythemia: a comparative study between spurious polycythemia and pure erythrocytosis.

The definite differential diagnosis between spurious polycythemia (SP) and pure erythrocytosis (PE) was tested. Serum erythropoietin (EPO) levels in 6 patients with PE were 12.8 +/- 3.7 mU/ml and were significantly lower than those of both 19 normal controls (28.5 +/- 15.0 mU/ml) and 9 patients with SP (21.3 +/- 10.2 mU/ml). Three of 11 patients with SP and 1 of 3 patients with PE had significantly higher marrow erythroid progenitor cells (CFU-Es) than those of the normal controls. Spontaneous CFU-E growth (CFU-E growth in the absence of added EPO) was found in 4 of 11 patients with SP, 1 of 3 patients with PE, and all patients with polycythemia vera. However, the number of spontaneous CFU-E was low in SP and PE. The measurements of serum EPO levels and CFU-E growth did not provide differentiation between PE and SP. Even if some patients, whose total red cell volumes are either higher than 12.5% above the mean predicted values or their CFU-E growth is great, are diagnosed as SP, consideration should be made that they might, in fact, have PE.

Adult↗
PubMed1987

The effects of aldose reductase inhibitor on the corneal endothelial morphology in diabetic rats.

Diabetic rats were produced by intravenous injection of streptozotocin. Of these, eleven rats were treated with topical instillation of 0.5% aldose reductase inhibitor (ARI), while ten received vehicle alone. The corneal endothelium of these diabetic rats was examined by specular microscopy and compared to age-matched nondiabetic rats (ten rats). Computerized morphometric analysis of individual cells demonstrated that the endothelium of the untreated diabetic rats had marked polymegathism (increased coefficient of variation in cell area) and pleomorphism (decreased percentage of hexagonal cells), as previously observed in diabetic patients. Similar endothelial changes were also noted in the ARI-treated diabetic rats, but to a significantly lesser extent. These results suggest that topically applied ARI can be effective in reducing morphologic changes of the diabetic endothelium, and that activation of the sorbitol pathway may be implicated in the etiology of such endothelial changes.

Aldehyde Reductase↗
PubMed1987

Isolation of complementary DNA clones for genes exhibiting reduced expression after treatment of mouse teratocarcinoma stem cells with a tumor-promoting phorbol ester.

For the study of the effects of the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) on early mammalian cell differentiation, a complementary DNA (cDNA) library was constructed on the poly(A)+RNAs extracted from undifferentiated F9 cells derived from a 129/Sv mouse teratocarcinoma OTT6050, and screening was done for the cNDA sequences corresponding to the mRNAs, the levels of which decreased significantly in the F9 cells after the TPA treatment. From about 80,000 clones screened, 3 different cDNA clones, pFT27, pFT43, and pFT60, were isolated and characterized. Levels of the RNAs hybridizable to these clones were decreased by fourfold to more than fiftyfold within 1-10 hours in the presence of TPA. Northern blotting experiments identified transcripts corresponding to these clones: pFT27 hybridized to 3.0 kb RNA, pFT43 hybridized to 1.5 kb RNA, and pFT60 hybridized to 1.0 kb RNA. The levels of these 3 transcripts were also decreased after treatment of the undifferentiated F9 cells with retinoic acid (RA) and dibutyryl cyclic AMP (cAMP). The TPA-induced as well as the RA- and cAMP-induced decreases in the RNAs hybridizable to pFT27 were regulated at the transcriptional level, whereas similar decreases in the RNAs hybridizable to pFT43 and pFT60 were regulated at the post-transcriptional level. These findings show that TPA treatment shares common effects with RA and cAMP on the undifferentiated F9 cells.

Animals↗
PubMed1987

Delta glycophorin (glycophorin B) gene deletion in two individuals homozygous for the S--s--U-- blood group phenotype.

Blood cells from two unrelated individuals whose erythrocytes exhibit respectively N S-s-U- and MN S-s-U- blood group phenotypes were examined by immunoblotting, periodic acid-Schiff (PAS) staining, and Southern blotting. Protein bands characteristic of delta glycophorin (glycophorin B) were absent from the immunoblots of whole erythrocyte lysates when probed with polyclonal glycophorin antisera and from isolated erythrocyte membranes stained with PAS reagents. Genomic DNA from the two individuals' leukocytes was digested with a panel of restriction enzymes and probed with alpha M glycophorin cDNA obtained from human K562 leukemic cell line. The EcoRI, PstI, and KpnI restriction site patterns were identical to those of S+s+U+ controls in fragment numbers and relative size but differed from controls in band intensities. Restriction mapping with HindIII, PvuII, SacI, MspI, and BamHI revealed that S-s-U- individuals lack fragments that are reproducibly observed in S+s+U+ controls, and most likely encode delta glycophorin. Using truncated 5' and 3' cDNA segments as probes and comparing, in control individuals, hybridization intensities of fragments with amino acid sequence homologies, we have inferred the assignment of restriction fragments to the alpha and delta glycophorin genes. Our results suggest that the absence of delta glycophorin in the two S-s-U- individuals is a result of deletion of the entire delta glycophorin gene. This is the first report of a glycophorin gene deletion.

Chromosome Deletion↗