Biomedical subjects

H Morimoto

Publications and source records attributed to H Morimoto.

At least 73 records · Page 4Linked to original sources

PubMed1996

Oxygen equilibrium properties of chromium (III)-iron (II) hybrid hemoglobins.

Cr(III)-Fe(II) hybrid hemoglobins, alpha 2(Cr) beta 2(Fe) and alpha 2(Fe) beta 2(Cr), in which hemes in either the alpha- or beta-subunits were substituted with chromium(III) protoporphyrin IX (Cr(III)(PPIX), were prepared and characterized by oxygen equilibrium measurements. Because Cr(III)PPIX binds neither oxygen molecules nor carbon monoxide, the oxygen equilibrium properties of Fe(II) subunits within these hybrids can be analyzed by a two-step oxygen equilibrium scheme. The oxygen equilibrium constants for both hybrids at the second oxygenation step agree with those for human adult hemoglobin at the last oxygenation step (at pH 6.5-8.4 with an without inositol hexaphosphate at 25 degrees C). The similarity between the effects of the Cr(III)PPIX and each subunits' oxygeme on the oxygen equilibrium properties of the counterpart Fe(II) subunits within hemoglobin indicate the utility of Cr(III)PPIX as a model for a permanently oxygenated heme within the hemoglobin molecule. We found that Cr(III)-Fe(II) hybrid hemoglobins have several advantages over cyanomet valency hybrid hemoglobins, which have been frequently used as a model system for partially oxygenated hemoglobins. In contrast to cyanomet heme, Cr(III)PPIX within hemoglobin is not subject to reduction with dithionite or enzymatic reduction systems. Therefore, we could obtain more accurate and reasonable oxygen equilibrium curves of Cr(III)-Fe(II) hybrids in the presence of an enzymatic reduction system, and we could obtain single crystals of deoxy-alpha 2(Cr) beta 2(Fe) when grown in low salt solution in the presence of polyethylene glycol 1000 and 50 mM dithionite.

Adult↗

PubMed1996

High-resolution crystal structure of magnesium (MgII)-iron (FeII) hybrid hemoglobin with liganded beta subunits.

The structures of deoxy (alpha(Mg(II))2 beta(Fe(II))2) and CO-liganded (alpha(Mg(II)2(Fe(II)-CO)2) forms of human hemoglobin were determined by X-ray crystallography to a resolution of 1.7 A and 1.9 A, respectively. The deoxy hybrid has virtually the same structure as that of the native deoxy HbA. Both the deoxy and CO-liganded hybrids assumed a T quaternary structure characteristic of native deoxy HbA. No significant structural difference was found between the alpha subunits of the CO-liganded hybrid and deoxy HbA, while in the beta subunit, significant tertiary structural changes were confined to the heme pocket. Baldwin showed by a comparison of COHbA and deoxy HbA that there is a 1.5 A shift of the beta subunit heme into its pocket. This shift was much reduced in alpha(Mg(II))2 beta(Fe(II)-CO)2. On the other hand, when the two structures are compared with superposition of hemes, the nearest neighbors of CO (Fe, E11 Val and E7 His) have shifted nearly to the same positions as those in COHbA. Thus the tertiary structure of the beta subunit of alpha(Mg(II))2 beta(Fe(II)-CO)2 is such that the CO molecule and the neighboring atoms assume nearly the same conformation as those of COHbA, while the block shift of these groups is impeded with respect to the structural invariant portions of the molecule.

Amino Acid Sequence↗

PubMed1996

Applications of tritium NMR to macromolecules: a study of two nucleic acid molecules.

We have tritium labeled two nucleic acid molecules, an 8 kDa DNA oligomer and a 20 kDa 'hammer-head' RNA for tritium NMR investigations. The DNA sequence studied has been previously used in homonuclear studies of DNA-bound water molecules and tritium NMR was expected to facilitate these investigations by eliminating the need to suppress the water resonance in tritium-detected 3H-1H NOESY experiments. We observed the anticipated through-space interactions found in B-form DNA in the NOESY experiments and an unexpected 'antiphase' cross-peak at the water frequency. T1 measurements on the tritiated DNA molecule indicated that relaxation rates were also accelerated for tritium and protons. Tritium NMR spectra of the hammerhead RNA molecule indicated conformational dynamics in the conserved region of the molecule in the absence of Mg2+ and spermine, two components necessary for cleavage. The dynamics were also investigated by 15N-correlated 1H spectroscopy and persisted after the addition of Mg2+ and spermine.

Base Sequence↗

PubMed1996

Effects of omega-conotoxin GVIA on the activation of capsaicin-sensitive afferent sensory nerves in guinea pig airway tissues.

We examined the effects of Ca2+ channel antagonists on various respiratory reactions induced by the activation of capsaicin-sensitive afferent sensory nerves. Intravenous (i.v.) injection of the N-type Ca2+ channel antagonist omega-conotoxin GVIA (CgTX) (1-20 micrograms/kg) dose-dependently inhibited capsaicin-induced guinea pig bronchoconstriction, whereas i.v. administration of the L-type antagonist nicardipine (100 micrograms/kg), the P-type antagonist omega-agatoxin IVA (AgaTX) (20 micrograms/kg) or the OPQ family-type antagonist omega-conotoxin MVIIC (CmTX) (20 micrograms/kg) had no effect. However, CgTX (20 micrograms/kg) failed to inhibit substance P-induced guinea pig bronchoconstriction. CgTX (20 micrograms/kg) significantly inhibited cigarette smoke-induced guinea pig tracheal plasma extravasation, but not the substance P-induced reaction. CgTX also reduced electrical field stimulation-induced guinea pig bronchial smooth muscle contraction (0.01-10 microM) and capsaicin-induced substance P-like immunoreactivity release from guinea pig lung (0.14 microM). This evidence suggests that N-type Ca2+ channels modulate tachykinin release from capsaicin-sensitive afferent sensory nerve endings in guinea pig airway tissue.

Animals↗

PubMed1996

Characterization of dextran sulfate-induced guinea pig tracheal plasma extravasation.

We examined the effect of dextran sulfate on guinea pig tracheal vascular permeability. I.v. injection of dextran sulfate (10-100 mg/kg) with captopril (1 mg/kg) induced guinea pig tracheal plasma extravasation. The i.v. administration of bradykinin (0.8-8 micrograms/kg) with captopril (1 mg/kg) also induced plasma extravasation. Bradykinin B2 antagonists, D-Arg[Hyp3-Thi5-D-Tic7-Tic8]-bradykinin (NPC 16731) and D-Arg[Hyp3-Thi5-D-Tic7-Oic8]-bradykinin (Hoe 140), reduced both dextran sulfate (32 mg/kg)- and bradykinin (2.5 micrograms/kg)-induced tracheal plasma extravasation in a dose-dependent manner. However, a cyclooxygenase inhibitor, indomethacin (1 mg/kg), and a neurokinin antagonist, [N-[N2-[N-[N-[N-[2,3-didehydro-N-methyl-N-[N-[3-(2-pentylphenyl )- propionyl]-L-threonyl]tyrosyl-L-leucynyl]-D-phenylalanyl]-L-a llo-threonyl]-L-asparaginyl]-L-serine-D-lactone] (FK 224) (1 mg/kg), had no effect on tracheal plasma extravasation induced by dextran sulfate and bradykinin. Dextran sulfate (32 mg/kg) with captopril (1 mg/kg) greatly increased the bradykinin level in guinea pig plasma. This evidence suggests that dextran sulfate releases bradykinin in guinea pig plasma and causes guinea pig tracheal plasma extravasation via the activation of bradykinin B2-receptors.

Analysis of Variance↗

PubMed1996

Relationship between hepatic iron deposits and response to interferon in chronic hepatitis C.

OBJECTIVES: The response to interferon in chronic hepatitis C is believed to be affected by hepatic iron content. We histopathologically examined liver biopsy specimens from patients with chronic hepatitis C to determine whether the presence or absence of hepatic iron deposits correlated with the response to interferon. METHODS: Sixty-three patients with hepatitis C treated with interferon-alpha were examined. Liver biopsy specimens obtained just before treatment were sliced and stained with Perls' Prussian blue. Twenty patients had complete responses, 24 patients had transient responses, and 19 patients had no response. RESULTS: Iron deposits stained by Prussian blue were seen in hepatocytes, sinusoidal cells, and portal mesenchymal cells. The degree of hepatocytic and sinusoidal iron deposits did not correlate with the response to interferon. However, the degree of portal iron deposits did correlate with hepatic inflammation activity (tau = 0.55, p < 0.001) and the severity of liver fibrosis (tau = 0.60, p < 0.001), and it correlated negatively to the response to interferon (tau = -0.49, p < 0.001). CONCLUSIONS: The results suggest that portal iron deposits are a factor in the response to interferon. The presence of portal iron deposits seems to be related to a poor response.

Adult↗

PubMed1996

Detection of K-ras point mutation at codon 12 in pure pancreatic juice collected 3 years and 6 months before the clinical diagnosis of pancreatic cancer.

We report herein a patient with K-ras point mutation at codon 12 that had been detected in pure pancreatic juice (PPJ) obtained 3 yr and 6 months before he was diagnosed with pancreatic cancer (PC). In this 73-yr-old man, PC was diagnosed by ERCP, which showed obstruction of the main pancreatic duct (MPD) at the borderline area between the body and tail of the pancreas. Distal pancreatosplenectomy was performed, and an advanced PC at the tail of the pancreas with a few metastatic nodules in the liver was confirmed. Retrospectively, a K-ras point mutation at codon 12 from GGT (glycine) to GAT (aspartic acid) was detected in the PPJ collected endoscopically 3 yr and 6 months earlier, as well as in the PPJ when PC was diagnosed and in the resected tumor tissue. Reevaluation of pancreatography from the ERCP performed at that time revealed a very mild stenotic lesion of the MPD, speculated to be a PC at a very early stage, at the body-tail border, but it was difficult to diagnose this lesion as a PC, based only on this morphological study. Accordingly, we believe that this is an interesting and valuable clinical case, indicating that K-ras mutation can precede clinical evidence, and its determination in PPJ could be a useful genetic test calling for a careful and extensive clinical investigation for early detection of PC.

Adenocarcinoma↗

PubMed1995

Randomised trial of effects of interferon-alpha on incidence of hepatocellular carcinoma in chronic active hepatitis C with cirrhosis.

Patients with chronic active hepatitis C and cirrhosis often develop hepatocellular carcinoma. Interferon (IFN) seems to be effective in some patients but whether it prevents carcinogenesis is unknown. In a prospective randomised controlled trial, we evaluated the effects of IFN-alpha in cirrhotic patients with HCV infection because of their high risk of hepatocellular carcinoma. 90 patients with compensated chronic active hepatitis C with cirrhosis were randomly allocated to receive IFN-alpha (6 MU three times weekly for 12-24 weeks) (45 patients) or symptomatic treatment (45 controls), and were followed up for 2-7 years. In nine controls, alanine aminotransferase (ALT) decreased to less than 80 IU/L but did not stay in the normal range. In 19 patients given IFN-alpha, ALT decreased to less than 80 IU/L (in seven patients, it became and stayed normal; p = 0.011, Wilcoxon rank-sum test). However, the mean change in ALT was not significantly different between the two groups. The mean change in peak alpha-fetoprotein values was smaller in patients given IFN-alpha than in controls (p = 0.021). The mean change in the serum albumin level was higher in the IFN-alpha group (p < 0.001). The histological activity index in the 12 IFN-alpha patients undergoing a second biopsy after therapy was improved (p = 0.031). Hepatitis C viral RNA disappeared in seven (16%) of the 45 IFN-alpha patients (95% CI, 7-29%) and in none of the 45 controls (0-8%; p = 0.018). Hepatocellular carcinoma was detected in two (4%, 1-15%) IFN-alpha patients and 17 (38%, 24-54%) controls (p = 0.002, Wilcoxon signed-rank test). The risk ratio of IFN-alpha treatment versus symptomatic treatment was 0.067 (0.009-0.530; p = 0.010 Cox's proportional hazards). IFN-alpha improved liver function in chronic active hepatitis C with cirrhosis, and its use was associated with a decreased incidence of hepatocellular carcinoma.

Antineoplastic Agents↗

PubMed1995

Oxygen equilibrium and electron paramagnetic resonance studies on copper(II)-iron(II) hybrid hemoglobins at room temperature.

Copper(II)-iron(II) hybrid hemoglobins, in which hemes in either the alpha or beta subunits are substituted with copper(II) protoporphyrin IX, have been prepared. The affinities of the ferrous-subunits in both hybrids for the first binding oxygen are as low as the affinity of deoxyhemoglobin under various solution conditions, indicating the equality of behavior in copper(II) protoporphyrin IX and deoxyheme. Electron paramagnetic resonance (EPR) examinations on these hybrids at room temperature show that the interaction between copper(II) and the proximal histidine (F8) is specifically weakened in the alpha subunits within a low affinity conformation of hemoglobin. These results suggest that copper(II) protoporphyrin IX is a useful EPR probe at room temperature for investigating the deoxyheme environment in hemoglobin.

Copper↗

PubMed1995

Characterization of the adipokinetic hormone receptor form the fat body of Manduca sexta.

A tritium labeled Manduca sexta adipokinetic hormone (M-AKH) was synthesized (pE-L-T-[p3H]F-T-S-S-W-G-NH2) (specific activity 27 Ci/mmol) which was fully active in a bioassay. It was used in a filtration based binding assay to characterize the M-AKH receptor from the fat body of M. sexta. Membrane fractions were prepared from fat body and optimal binding conditions were determined. A Kd of 7.10(-10) M was determined and the receptor concentration estimated to be 0.5 pmol/mg membrane protein. No receptor binding was found when membranes were prepared from brain, heart or flight muscle of M. sexta or from fat body of the cockroach Blaberus discoidalis. However, specific binding was found with membrane preparations from the pterothoracic ganglion of M. sexta. The membranes from the ganglion had a much smaller number of binding sites than the fat body membranes, however, the binding was specific and observed in each experiment.

Amino Acid Sequence↗

PubMed1995

Oxygen equilibrium properties of nickel(II)-iron(II) hybrid hemoglobins cross-linked between 82 beta 1 and 82 beta 2 lysyl residues by bis(3,5-dibromosalicyl)fumarate: determination of the first two-step microscopic Adair constants for human hemoglobin.

We have previously reported that cross-linked asymmetric Ni(II)-Fe(II) hybrid hemoglobin, XL[alpha (Fe) beta (Fe)][alpha (Ni) beta (Ni)], in which the alpha 1 beta 1 dimer containing ferrous protoporphyrin IX and the adjacent alpha 2 beta 2 dimer containing nickel(II) protoporphyrin IX were cross-linked between Lys-82 beta 1 and Lys-82 beta 2 by reaction with bis(3,5-dibromosalicyl)fumarate, represents an adequate model for determination of the alpha 1 beta 1 oxygenation properties of native hemoglobin [Shibayama, N., Imai, K., Morimoto, H., & Saigo, S. (1993) Biochemistry 32, 8792-8798]. To extend the approach using cross-linked Ni(II)-Fe(II) hybrids to all possible pathways for initial-half oxygenation of hemoglobin, we have prepared three other types of cross-linked Ni(II)-Fe(II) hybrids, carrying nickel(II) protoporphyrin IX in two subunits and ferrous protoporphyrin IX in the other two subunits, and have determined the two-step oxygen equilibrium curves of the ferrous subunits within these cross-linked hybrids. For the first step of oxygenation, the alpha subunit shows about 3-fold higher affinity than the beta subunit at all pH values examined, indicative of a significant functional heterogeneity of the subunits in deoxyhemoglobin. For the second step of oxygenation, the cooperativity represented by the Hill coefficient (nmax) increases in the order of beta 1 beta 2 (nmax = 1.36), alpha 1 beta 1 (nmax = 1.41), alpha 1 beta 2 (nmax = 1.64), and alpha 1 alpha 2 (nmax = 1.72) at pH 7.4 in the presence of 0.1 M Cl- at 25 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspirin↗

PubMed1995

Epidural analgesia shortens postoperative ileus after ileal pouch-anal canal anastomosis.

PURPOSE: A retrospective study was conducted to determine whether epidural analgesia would speed recovery from postoperative ileus in patients undergoing ileal pouch-anal canal anastomosis. METHODS: Among 85 patients who underwent proctocolectomy with ileal pouch-anal canal anastomosis at the Mayo Medical Center between January 1, 1991 and October 31, 1992, 44 were treated for postoperative pain with continuous infusion of epidural fentanyl citrate supplemented by intravenous morphine on request, while 41 controls were given only systemic morphine sulfate as needed. RESULTS: The patients in the two groups were matched and similar with regard to preoperative and operative risk factors and postoperative morbidity. No operative mortality occurred. Epidural fentanyl analgesia resulted in less need for nasogastric suction and intravenous fluids, more rapid discharge of fecal content, more rapid return to oral intake, and shorter hospitalization. CONCLUSION: Epidural analgesia with fentanyl citrate shortened postoperative ileus after proctocolectomy and ileal pouch-anal canal anastomosis.

Adolescent↗

PubMed1995

Polysaccharides in fungi. XXXV. Anti diabetic activity of an acidic polysaccharide from the fruiting bodies of Tremella aurantia.

An acidic polysaccharide (TAP) was isolated from a hot-water extract of the fruiting bodies of Tremella aurantia. It showed remarkable hypoglycemic activity in normal mice and two diabetic mouse models, streptozotocin-induced diabetes and genetic diabetes, following intraperitoneal administration. Continuous oral administration of TAP solution (0.5g/l) for a long period was found to be also effective in hyperglycemia in glucose-loaded mice and no harmful physical effects were found. TAP had an [alpha]D -7 degrees in water, and its molecular weight was estimated to be about 1500000. TAP is composed of mannose, xylose, glucuronic acid and glucose (molar ratio, 4:2:1:0.3), and it contains 2.2% of O-acetyl groups.

Animals↗

PubMed1994

Site-directed mutagenesis in hemoglobin: functional and structural role of the penultimate tyrosine in the alpha subunit.

The penultimate tyrosine in the hemoglobin subunit is considered to be one of the most important residues for the normal structure and function of hemoglobin. To elucidate the functional and structural role of the penultimate residue in the alpha-subunit, we prepared new artificial mutants; Hb Y140 alpha Q, in which Tyr-140 alpha is replaced by a nonaromatic residue, Gln, and Hb Y140 alpha F, which loses its hydrogen bond to Val-93 alpha by the substitution of Phe for Tyr. HB Y140 alpha Q exhibited a markedly increased oxygen affinity and almost completely diminished cooperativity, whereas Hb Y140 alpha F showed similar but less extensively impaired function, indicating that the aromatic residue at the penultimate position in the alpha-subunit contributes to the stabilization of the T-quaternary structure as does the corresponding residue in the beta-subunit. However, the deoxygenated forms of these mutants bear significant T-state character in their spectroscopic properties observed at high protein concentrations. The tetramer-dimer equilibrium data of the mutants suggested that a significant part of the functional alterations observed for dilute solution appears to result from partial dissociation into alpha beta dimers rather than direct destabilization of the T-quaternary structure in the deoxygenated form. Therefore, we can conclude that the penultimate tyrosine in the alpha-chain plays a key role not only in the stabilization of the T-state but also in the subunit assembly.(ABSTRACT TRUNCATED AT 250 WORDS)

Allosteric Regulation↗

PubMed1994

Aberrant hepatic duct connected with the main pancreatic duct by anomalous pancreato-biliary ductal union: case report.

An aberrant hepatic duct directly connected to the main pancreatic duct with anomalous arrangement of the pancreato-biliary ductal system is reported here, the first report of such a case, to our knowledge. A 53-year-old woman was admitted to our hospital because of cholecystolithiasis with abdominal pain in the right upper quadrant. Endoscopic retrograde cholangiopancreatography (ERCP) showed that an aberrant hepatic duct, which independently drained the right posterior segment of the liver, connected to the main pancreatic duct at a high insertion site distal to the sphincter area of the major papilla. The common bile duct (containing stones), on the other hand, united with the main pancreatic duct in a normal fashion. Cholecystectomy and bile duct lithotomy were performed. The aberrant hepatic duct was separated from the main pancreatic duct just above the junction, and was anastomosed side-by-side to the common hepatic duct. The embryologic development of this lesion is not clear, but is discussed in this report.

Anastomosis, Surgical↗

PubMed1994

Immunohistochemical analysis of p53 in gynecologic tumors.

Immunohistochemical staining for the p53 protein was performed in microwave-fixed, paraffin-embedded sections of normal, premalignant and malignant tissues of the female genital tract using a monoclonal antibody, PAb 1801. No staining was detected in normal and premalignant tissues, whereas nuclear staining of cancer cells was observed in 12 (22%) of 55 cervical squamous cell carcinomas, 4 (25%) of 16 cervical adenocarcinomas, 37 (42%) of 88 endometrial carcinomas, 23 (38%) of 60 ovarian adenocarcinomas, and 6 (100%) of 6 squamous cell carcinomas arising in dermoid cysts. Of interest, 1 of 7 endometrial cancers with concomitant atypical hyperplasia showed weak nuclear staining in a few atypical hyperplastic glands in addition to the cancerous lesions. Although staining was associated with cancers having a high histologic grade and serous papillary adenocarcinomas of the endometrium, it did not correlate with invasion, metastasis, or clinical stage. Comparison of the staining patterns with molecular analysis of mutations in the p53 gene showed the expected correlation of nuclear staining with missense mutations but not with nonsense mutations, which consistuted one third of all mutations found in this series. In addition, cytoplasmic staining did not predict mutation.

Cervix Uteri↗

PubMed1994

[A case of myelodysplastic syndrome with pericarditis due to atypical Mycobacterium].

A 28-year-old woman with high fever and cough was admitted because of an abnormal shadow on the chest X-ray film. Mycobacterium kansasii was detected by sputum culture. The complete blood cell count disclosed pancytopenia and the myelogram showed slight hypoplasia and abnormality of the cell morphology. We diagnosed her disease as atypical mycobacteriosis and myelodysplastic syndrome. We began medical therapy with antituberculous drugs against Mycobacterium kansassi, and the sputum culture became negative. She was discharged after 4 months, but cardiothoracic ratio (CTR) increased gradually and pericardial effusion was detected by echocardiogram during follow-up. She was admitted again. We did not perform exploratory puncture, because the pericardial effusion did not increase for 6 months after admission and she had no complaints. We continued the antituberculous drugs, and CTR and the pericardial effusion decreased during follow-up. We considered the diagnosis in this case to be pericarditis due to Mycobacterium kansasii.

Adult↗

PubMed1993

Loxiglumide (CR1505), a cholecystokinin antagonist, specifically inhibits the growth of human pancreatic cancer lines xenografted into nude mice.

BACKGROUND: Cholecystokinin is thought to be an important factor regulating the growth of human pancreatic cancers. The study was designed to evaluate the effects of the cholecystokinin antagonist loxiglumide (CR1505) on the growth of human pancreatic cancer. METHODS: Human gastrointestinal cancer xenografted tumors (one esophageal, one gastric, two colorectal, two biliary tract, and two pancreatic cancers) were transplanted into nude mice. The mice were given CR1505 at 250 mg/kg daily for 14 days, either subcutaneously or intragastrically, and the tumor volumes before and after treatment were compared. In vitro effects of CR1505 were assessed by measuring the DNA synthesis (3H-thymidine incorporation). RESULTS: CR1505 inhibited the growth of the two pancreatic cancer lines but did not inhibit the growth of the other lines. CR1505 also inhibited in vitro DNA synthesis in the two pancreatic cancer lines at lower concentrations than in the other lines. This pancreatic cancer-specific inhibitory effect of CR1505 was retarded by exogenously administered cholecystokinin in one pancreatic cancer line but was augmented in the other line. The effect of CR1505 was inhibited by oral administration of the trypsin-inhibitor camostate (FOY-305) in both pancreatic cancer lines. CONCLUSIONS: These results suggest that CR1505 may specifically inhibit the growth of human pancreatic cancers and may be suitable for clinical study. However, its antiproliferative effect may not necessarily be dependent on its cholecystokinin-antagonism but may be mediated through the proteolytic enzymes found in the lysosomes of the pancreatic cancer cells.

Animals↗