Biomedical subjects

M Ohta

Publications and source records attributed to M Ohta.

At least 19 recordsLinked to original sources

PubMed1992

Structural elucidation of a novel phosphonoglycosphingolipid in eggs of the sea hare Aplysia juliana.

A novel phosphonoglycosphingolipid (AJPnGL) was isolated from eggs of the sea hare Aplysia juliana. The structure was determined to be Gal alpha 1-->2Gal beta 1-->4(2-aminoethylphosphonyl-->6)Glc beta 1-->1Cer by FAB/MS, 1H-NMR, hydrogen fluoride degradation, methylation analysis, partial acid hydrolysis and GC analysis of the component sugars, fatty acids and long-chain bases. The ceramide moiety of this lipid consisted of branched nonadeca-4-sphingenine and octadeca-4-sphingenine as main long-chain bases and palmitic acid and stearic acid as major fatty acids. Since the sugar chain (Gal alpha 1-->2Gal beta 1-->4Glc beta 1-->) and the ceramide moiety of AJPnGL were identical with those of the main neutral glycosphingolipid of eggs of A. juliana, the biosynthesis of AJPnGL may occur by the addition of 2-aminoethylphosphonate to the main neutral glycosphingolipid, Gal alpha 1-->2Gal beta 1-->4Glc beta 1-->1Cer.

Animals↗

PubMed1992

In vitro proliferation and the cytotoxic specificity of a cryopreserved cytotoxic T cell clone reacting against human autologous tumor cells.

Proliferation and functional maintenance of CTL after cell cryopreservation often proves to be quite difficult. We developed an improved method for proliferating cryopreserved CTL, and for gaining their specific cytotoxic function. T cells were cryopreserved at -180 degrees C in RPMI 1640 containing 50% FCS and 10% DMSO. The cryopreserved T cells were well recovered by culturing in a medium containing the supernatant of primary cultures with TIL and autologous tumor cells, in addition to a high concentration (350 U/ml) of rIL-2. Furthermore, these cells were proliferated more efficiently when MMC-treated autologous tumor cells were used in vitro as a feeder and an antigenic stimulant. However, such a high dose IL-2 cultivation resulted in the loss of cytotoxic reactivity of CTL clone. In contrast, the withdrawal of rIL-2 from in vitro cultivation for 24 h prior to the cytotoxic assays conferred the specificity of cytotoxicity on CTL. By these methods, one can obtain a large number of CTL, and pursue the physiologic detail of the specific cytotoxic mechanism of CTL against autologous human tumor cells.

Antigens, Surface↗

PubMed1992

A new member of the insulin receptor family, insulin receptor-related receptor, is expressed preferentially in the kidney.

Shier and Watt isolated human and guinea pig genomic DNA encoding a putative protein, insulin receptor-related receptor (IRR), the primary structure of which is similar to that of other members of the insulin receptor family, the insulin receptor and type-I IGF receptor (J. Biol. Chem. 264, 14605-14608 (1989)). However, the expression of the IRR gene remained unknown. In this paper, we isolated the IRR cDNA from the rat brain and examined the expression of the IRR mRNA in a variety of rat tissues, including the brain, heart, lung, liver, small intestine, kidney, thymus, spleen, muscle, adipose tissue and cartilage by polymerase chain reaction. In contrast to the wide distribution of the insulin receptor and type-I IGF receptor mRNAs, the IRR mRNA is expressed preferentially in the kidney, which indicates that IRR has unique functions as a member of the insulin receptor family.

Amino Acid Sequence↗

PubMed1992

Transforming growth factor-beta inhibits phosphorylation of the retinoblastoma susceptibility gene product in human monocytic leukemia cell line JOSK-I.

Proliferation of the human monocytic leukemia cell line JOSK-I is inhibited by transforming growth factor-beta (TGF-beta). Growth inhibition by TGF-beta was not due to either a toxic effect or to induction of differentiation. TGF-beta induced a cell cycle arrest at late G1 phase and was not found to be inhibitory to JOSK-I cells in S phase or G2/M. This G1 cell cycle arrest was associated with an accumulation of the unphosphorylated form of the retinoblastoma susceptibility gene product (Rb) in good correlation with inhibition of DNA synthesis. In contrast to the effects of TGF-beta, two other agents which induced a G1 arrest of JOSK-I cells had a different effect on Rb. Aphidicolin blocked cells at G1/S but could not reduce Rb phosphorylation as great as that seen with TGF-beta. 12-O-Tetradecanoylphorbol-13-acetate, an inducer of differentiation, did reduce Rb phosphorylation, but not until 72 h, when differentiation had already occurred. The identities of the Rb kinases are unknown, but recent evidence suggests that the cdc2 gene product could participate in Rb phosphorylation. Although cdc2 mRNA and total protein levels were not affected, TGF-beta inhibited the rate of translation and kinase activity of cdc2 in JOSK-I cells. These results suggest that growth inhibition of hematopoietic cells by TGF-beta is linked to suppression of Rb phosphorylation to retain Rb in an unphosphorylated, growth-inhibitory state. The suppression of Rb phosphorylation is suggested to be mediated through inhibition of cdc2 kinase activity by TGF-beta.

Aphidicolin↗

PubMed1992

Identification of osteopontin in isolated rabbit osteoclasts.

Bone remodeling is a complex process coupling bone formation and resorption. Osteoblasts, the bone-forming cells, are known to produce various bone matrix proteins and cytokines; however, little is known about protein factors produced by osteoclasts or bone-resorbing cells. A method utilizing the high affinity of osteoclasts for tissue culture dishes was developed to isolate a large number of pure osteoclasts from rabbit long bones. A cDNA library was then constructed from these isolated osteoclasts, and differential cDNA screening was performed between osteoclasts and spleen cells. Two clones representing osteoclast-specific clones, named OC-1 and OC-2, were isolated. By Northern blot analysis, OC-1 was expressed in osteoclasts and in kidneys, whereas OC-2 was specific for osteoclasts. OC-1 was found to encode osteopontin from its nucleotide sequence, and therefore, osteopontin may have other functions for osteoclastic bone resorption besides osteoclast attachment to bone.

Amino Acid Sequence↗

PubMed1992

[Effects of duct reconstruction and estrogen treatment on endocrine and exocrine functions of fibrotic pancreas caused by ligation of the pancreatic duct in dogs].

After fibrotic pancreas was produced by ligation of the pancreatic ducts in mongrel dogs, effects of duct reconstruction and estrogen treatment on endocrine and exocrine function of the fibrotic pancreas were investigated. 1) K value in IV-GTT and sigma IRG in IV-ITT were significantly improved after duct reconstruction in group with estrogen treatment, especially K value was significantly improved as compared with that in group without estrogen treatment. 2) Total volume of pancreatic secretion, total amylase output and maximal bicarbonate concentration in P-S tests were improved significantly after duct reconstruction in the group with estrogen treatment, but not significantly improved in the group without estrogen treatment. 3) Histological changes of the islet and pancreatic fibrosis, caused by the pancreatic duct ligation, were also significantly improved after duct reconstruction in the group with estrogen treatment, as compared with those in the group without estrogen treatment.

Amylases↗

PubMed1992

Different preparations of zymosan induce glycogenolysis independently in the perfused rat liver. Involvement of mannose receptors, peptide-leukotrienes and prostaglandins.

Zymosan (non-boiled) induced glycogenolysis biphasically, with no lag time, in the perfused rat liver. After the zymosan was boiled, it could be separated into two fractions, both of which stimulated glycogenolysis independently. The soluble fraction of boiled zymosan (zymosan sup) showed homologous desensitization, indicating that zymosan sup-induced glycogenolysis is a receptor-mediated event. Mannan (polymannose), which is known to be a biologically active component of zymosan, induced a glycogenolytic response similar to that produced by zymosan sup, and desensitized the response to the latter. Preinfusion of platelet-activating factor (PAF, 20 nM) or isoprenaline (10 microM) did not extinguish the glycogenolytic response to zymosan sup, while the response to a secondary infusion of PAF was blocked. The glycogenolytic response to zymosan sup was completely inhibited by nordihydroguaiaretic acid (NDGA, 10 microM), a lipoxygenase inhibitor, and by ONO-1078 (100 ng/ml), a leukotriene (LT) D4 receptor antagonist. On the other hand, the glycogenolytic effect of zymosan pellet (the particulate fraction of boiled zymosan) was not affected by preinfusion of zymosan sup, and was inhibited by ibuprofen (20 microM), a cyclo-oxygenase inhibitor. Prostaglandins (PGs) detected in the perfusate were augmented with infusion of zymosan pellet. Opsonization of the zymosan pellet by serum (complement) enhanced the glycogenolytic response without a lag period, and with a concomitant enhancement of PG output. Correlations between glucose production and PGs were r = 0.832 (PGD2), r = 0.872 (PGF2 alpha), r = 0.752 (PGE2) and r = 0.349 (6-oxo-PGF1 alpha). The glycogenolytic response to non-boiled zymosan was delayed and the biphasic glycogenolytic response was not observed when mannan was infused first. NDGA mimicked the effects of the preinfusion of mannan, while ibuprofen had no effect on the non-boiled-zymosan-induced glycogenolysis. These results suggest: (1) that non-boiled zymosan stimulates glycogenolysis through a mannose receptor-dependent, but unidentified, pathway, (2) that zymosan sup induces glycogenolysis via mannose receptor activation through the production of peptide-LTs but not PAF, and (3) that zymosan pellet causes glycogenolysis through the production of prostanoids, which is enhanced in the presence of complement.

Animals↗

PubMed1992

Relationships between energy level and insulin secretion in isolated rat islets of Langerhans. Manipulation of [ATP]/[ADP][Pi] by 2-deoxy-D-glucose.

Perifusion of islets with nominally phosphate-free buffer containing increasing concentrations of 2-deoxy-D-glucose (2.5 to 10 mM) produced increments in high alpha-ketoisocaproic acid-induced secretion of insulin beyond those observed in the absence of the sugar analogue. 3-O-methyl-D-glucose, a poorly metabolized sugar, was without effect. Insulin release evoked by 40 mM KCl was not altered by 2-deoxyglucose. The concentration of intracellular inorganic phosphate was lower in islets perifused with 2-deoxyglucose and declined to a lower level after addition of 20 mM alpha-ketoisocaproic acid. The enhancement of alpha-ketoisocaproic acid-induced hormone secretion by 2-deoxyglucose was not seen in islets perifused with medium containing 1.5 mM phosphate; instead a small inhibition was observed. It is postulated that conditions which lower intracellular [Pi] facilitate, either directly or indirectly, hormone release although the mechanism of this effect remains to be elucidated.

Adenine Nucleotides↗

PubMed1992

Superoxide anion-generating activity of polymorphonuclear leukocytes and monocytes in patients with lung cancer.

Superoxide anion (O2-) production by polymorphonuclear leukocytes (PMN) and monocytes (MN) was measured in the peripheral blood of 70 patients with lung cancer. The O2- production by these cells was decreased in many, but not all, patients. The incidence of patients with lower O2- production increased as the stage advanced. The correlation between O2- production by these cells and peripheral blood smears was evaluated in patients with cancer. Patients with 80% granulocytes and 40% monocytes or more in their peripheral blood had a significantly lower O2- production by PMN and MN compared with those with less than 80% granulocytes and 40% monocytes, respectively. These results indicate that an abnormally increased number of granulocytes and monocytes in the peripheral blood of patients with cancer may depress immunoregulatory function. In addition, decreased O2- production by these cells should be considered when assessing the defense mechanisms and susceptibility to infection of these patients.

Adult↗

PubMed1992

Tissue-specific expression of the rat secretin precursor gene.

Secretin is a 27-amino acid gastrointestinal hormone that stimulates the secretion of bicarbonate-rich pancreatic fluid. We previously demonstrated that the secretin precursor gene is expressed in the brain as well as in the small intestine. In this study, we demonstrated that the abundance of secretin precursor mRNA in the heart, lung, and kidney was comparable to that of the small intestine. The nucleotide sequences of the coding regions of the secretin precursor mRNAs in these tissues were identical to those of the small intestine, indicating that secretin precursor proteins produced in these tissues are identical to those in the small intestine. This is the first report that the secretin precursor gene is also expressed in the heart, lung, kidney, and testis as well as in the gastrointestinal tract and brain.

Animals↗

PubMed1992

Firing of 'possibly' cholinergic neurons in the rat laterodorsal tegmental nucleus during sleep and wakefulness.

To clarify functional roles of mesopontine cholinergic neurons as a component of an activating system, single neuronal activity in the laterodorsal tegmental nucleus (LDT) of undrugged rats, whose head was fixed painlessly, was recorded along with cortical EEG and neck EMG. Activity of some dorsal raphe (DR) neurons was also recorded for comparison. Most of the animals had been sleep-deprived for 24 h. Observation was made only on neurons generating broad spikes, presumed from previous studies to be cholinergic or monoaminergic. The position of recorded neurons was marked by Pontamine sky blue ejected from the glass pipette microelectrode, and was identified on sections processed for NADPH diaphorase histochemistry which specifically stained cholinergic neurons. According to their firing rates during wakefulness (AW), slow-wave sleep (SWS) and paradoxical sleep (PS), 46 broad-spike neurons in the LDT were classified into 4 groups: (1) neurons most active during AW and silent during PS (some of these neurons might be serotonergic rather than cholinergic, as all the 9 neurons in the DR); (2) neurons most active during PS and silent during AW; (3) neurons equally more active during AW and PS than SWS; and (4) others mainly characterized by transiently facilitated activity at awakening and/or onset of PS. Neurons of groups 2 and 3 were the major constituents of the LDT. In most neurons change in firing preceded EEG change, except at awakening from PS. These results suggest that: (1) the LDT is composed of cholinergic neurons with heterogenous characteristics in relation to sleep/wakefulness; and (2) some tegmental cholinergic neurons play a privotal role in induction and maintenance of PS.

Acetylcholine↗

PubMed1992

Sclerotherapy vs. esophageal transection vs. distal splenorenal shunt for the clinical management of esophageal varices in patients with child class A and B liver function: a prospective randomized trial.

Ninety-six patients with good liver function (Child class A or B) and esophageal varices were randomly assigned to one of three groups given different treatments: endoscopic injection sclerotherapy (n = 32), esophageal transection (n = 32) or distal splenorenal shunt (n = 32). Five patients (5.2%) had to be excluded from this study because severe chronic pancreatitis made separation of the distal splenic vein from the pancreatic bed difficult. Esophageal transection was performed for these patients. No deaths occurred during the 30 days of treatment. The 5-yr cumulative bleeding rates were 0%, 5.9% and 12.9% in the endoscopic injection sclerotherapy, esophageal transection and distal splenorenal shunt groups, respectively (no statistical significance). In no case in the three groups did death occur because of variceal bleeding. Sixteen patients died, mainly because of underlying liver disease; four were in the endoscopic injection sclerotherapy group, five were in the esophageal transection group and seven were in the distal splenorenal shunt group. No statistically significant difference in survival rate among the three groups was found. These results show that endoscopic injection sclerotherapy is a satisfactory alternative to esophageal transection or distal splenorenal shunt for the clinical management of patients with esophageal varices.

Esophageal and Gastric Varices↗

PubMed1992

Endoscopic injection sclerotherapy for 1,000 patients with esophageal varices: a nine-year prospective study.

We report here the results of endoscopic injection sclerotherapy performed in 1,000 consecutively treated Japanese patients with esophageal varices. This prospective study covered the period from 1982 to 1990. Variceal bleeding was controlled in 215 (97.7%) of 220 patients. Esophageal varices were completely eradicated in 778 patients (77.8%); the mean number of sessions was 4.2. In only 3 of the 778 patients did esophageal varices of the same size recur. Small, dilated, venous vessels that required additional sclerotherapy in follow-up endoscopy at 3-mo intervals appeared in 171 (22.2%) of 778 patients. The cumulative nonbleeding rate at 5 yr was 94.5% in patients in whom the varices had been eradicated. Deaths caused by upper gastrointestinal bleeding accounted for 2.6% of cases, whereas the rates of liver failure and hepatoma were 4.6% and 47.3%, respectively. The 5-yr cumulative survival rate was 54.1% in patients without concomitant hepatoma; it was 12.0% in patients with hepatomas. Multivariate analysis showed that hepatoma, Child classification, indication (acute, elective or prophylactic) and eradication were independent factors that significantly influenced survival time. This study clearly shows that close follow-up with endoscopy and complete eradication lead to significant reduction in bleeding from esophageal varices and reduction of mortality related to this bleeding.

Endoscopy↗

PubMed1992

Passive immunizations of suckling mice and infants with bovine colostrum containing antibodies to human rotavirus.

After immunizing 8-month pregnant Holstein cows with the human rotavirus MO strain, cow colostrum containing neutralizing antibody to four different serotypes of human rotavirus, designated Rota colostrum, was obtained. Oral inoculation of human rotavirus MO strain into 5-day-old BALB/c mice causes gastroenteritis characterized by diarrhea. Using this small animal model, passive protection of suckling mice against human rotavirus infection was achieved with the use of Rota colostrum. Rota colostrum completely protected against rotavirus infection, but purified IgG and IgA obtained from Rota colostrum were unable to protect against infection. After grouping randomly 20 infants from a baby care center, 10 infants received 20 ml of Rota colostrum per day for 2 weeks and 10 control infants did not. Rotavirus-associated diarrhea developed in 7 of 10 infants in the control group. None of the three infants in the every day recipient group of Rota colostrum had such symptoms, and one of three infants in the every other day recipient group developed rotavirus-induced diarrhea. All four infants who received Rota colostrum after symptoms appeared developed diarrhea. Oral administration of Rota colostrum seems to be an effective and safe means of preventing diarrhea caused by human rotavirus infection.

Age Factors↗

PubMed1992

Oligosaccharides accumulated in the bovine beta-mannosidosis kidney.

The phenotype of bovine beta-mannosidosis (beta-mannosidase deficiency), recently identified in Salers cattle, is similar to the caprine form of the disease (Abbitt et al., 1991). This investigation was designed to characterize accumulated kidney oligosaccharides in bovine beta-mannosidosis. Oligosaccharides were extracted from the kidney of an affected Salers calf and purified by chromatographic techniques. The amount of accumulating oligosaccharides in 1 g of wet tissue was about 21 mumol. Structures of derivatized oligosaccharides were characterized by high-performance liquid chromatography, mass spectrometry, methylation analysis and sequential exoglycosidase digestions. The major accumulating oligosaccharides were Man beta 1-4GlcNAc and Man beta 1-4GlcNAc beta 1-4GlcNAc. Oligosaccharides accumulating in minor amounts were Man beta 1-4GlcNAc beta 1-4Man beta 1-4GlcNAc, Man alpha 1-6Man beta 1-4GlcNAc beta 1-4GlcNAc and Man beta 1-4GlcNAc beta 1-4Man beta 1-4GlcNAc beta 1-4GlcNAc. As in caprine beta-mannosidosis, oligosaccharides with terminal beta-mannose residues and cleaved as well as uncleaved chitobiose linkages were identified in bovine beta-mannosidosis kidney. The accumulating oligosaccharides in tissue were thus identical in bovine and caprine beta-mannosidosis; however, the source of the novel oligosaccharides remains to be determined.

Animals↗

PubMed1992

Comparison between resected and irradiated small cell lung cancer in patients in stages I through IIIa.

The survival and recurrence of 37 patients with small cell lung cancer who underwent surgical resection were compared with those of 32 patients who were excluded from surgical resection but received radiotherapy. All but 2 patients received chemotherapy. The number of patients in the resected and nonresected groups in each pretreatment clinical stage were, respectively, as follows: 13 and 2 in stage I, 12 and 7 in stage II, and 12 and 23 in stage IIIa. The main reasons for exclusion from surgical resection were locally advanced disease in 15 patients, avoidance of pneumonectomy in 7, and poor pulmonary function in 5. In stage II, the mean tumor size was larger and there were fewer patients with peripheral tumors in the nonresected group than in the resected group. In stage IIIa, there were significantly more patients with overt N2 disease and central tumors in the nonresected group than in the resected group. The 5-year survival rate of the resected group in stage I was 67.7%. Although the nonresected group in stages II and IIIa had many adverse prognostic factors, there was no statistically significant difference between the survival of the resected and the nonresected groups. With respect to the site of first recurrence, a similar pattern was observed in the two groups in each stage, whereas local disease in stage I was completely controlled by surgical resection. These observations suggest that surgical resection can be considered a modality of treatment in clinical stage I. However, the treatment role of surgical resection in clinical stages II and IIIa, even in selected patients, remains unclear.

Adult↗

PubMed1992

Induction of avascular yolk sac due to reduction of basic fibroblast growth factor by retinoic acid in mice.

Vasculogenesis depends on autocrine secretion of basic fibroblast growth factor (bFGF) from capillary endothelial cells. Retinoic acid (RA) induced avascular yolk sac (AVY) of mouse embryos of dams given 60 mg/kg of RA orally on Day 8 of gestation and sacrificed 3 days later. We studied the localization and transcriptional expression of bFGF and FGF-receptor (flg), heparin-binding growth factor (HBGF) activity, localization of lysosomal enzymes and alpha 1-antitrypsin (AAT), and electron microscopy of the normal mouse visceral yolk sac (VYS) and AVY. bFGF, which is normally present in the endoderm of the VYS of 8-day-old embryos and in all components of the VYS by Day 11 of gestation, was reduced in the AVY. However, in the presence of bFGF in vitro capillary nets were restored in the AVY. The mRNA for bFGF was not detectable in either VYS or AVY, while flg mRNA was detected equally in both organs in Northern blotting. The characteristic distribution pattern of lysosomal enzymes, acid phosphatase, lysozyme, and cathepsin D, and AAT was altered in the AVY. The level of acid phosphatase and AAT was reduced to 10% in the AVY. Electron microscopy revealed a partial or total loss of lysosomal membranes where the contents of lysosomes fused with adjacent lysosomes and the external organelles. These results suggest that vitelline blood vessels are not developed by endogenous autocrine bFGF but by exogenous transcellular bFGF from absorptive endodermal cells. Retinoic acid does not affect the angiogenic capacity of the VYS mesenchyme but destroys lysosomes, which release hydrolytic enzymes, leading to degradation of AAT in the endodermal cells and then digestion of endocytosed bFGF.

Acid Phosphatase↗

PubMed1992

Intraventricular infusion of leupeptin decreases Bmax of the D2 receptor in the striatum of young rats.

Intraventricular infusion of a thiol protease inhibitor, leupeptin, was previously shown to induce several morphological and immunochemical manifestations of normal and pathological aging in rat brain. The present study attempted to elucidate whether this treatment also perturbs another brain function which declines in aging, dopamine D2 receptor binding in striatum. Intraventricular infusion of leupeptin (0.6 mg per day) for two weeks caused a significant (about 20%) reduction in the binding maximum (Bmax) of dopamine D2 receptors (as examined by [3H] spiperone binding) in the striatum of young male Fischer-344 rats in comparison to (saline-infused) control rats. The apparent Kd values did not differ significantly between the control and leupeptin-treated rat groups. The results suggest that decreased protein turnover may be a factor in the decline in Bmax of D2 receptors during aging.

Animals↗