Biomedical subjects

T Okamura

Publications and source records attributed to T Okamura.

At least 253 records · Page 14Linked to original sources

PubMed1997

Prejunctional regulation by endogenous and exogenous acetylcholine of adrenergic nerve function in isolated canine mesenteric arteries.

Transmural electrical stimulation (5-30 Hz) produced a frequency-dependent increase in the perfusion pressure of isolated, perfused dog mesenteric artery segments without the endothelium, which was abolished by prazosin or tetrodotoxin. Physostigmine inhibited the pressor response to transmural electrical stimulation, whereas atropine potentiated the response. Treatment with acetylcholine (10(-6) and 10(-5) M) dose-dependently inhibited the response to electrical nerve stimulation. The effect was reversed by the addition of atropine and AF-DX 116 at a concentration (10(-7) M) that selectively blocked the M2 receptor subtype, but not by pirenzepine or 4-DAMP. Acetylcholine did not alter the pressure raised by norepinephrine in perfused arterial segments nor the contraction caused by exogenous norepinephrine in the artery strips. 3H-overflow evoked by transmural electrical stimulation from tissues prelabeled with [3H] norepinephrine was decreased by acetylcholine (10(-6) M) in the superfused dog mesenteric arterial strips. It is concluded that acetylcholine inhibits adrenergic neurogenic contractions by interfering with the release of norepinephrine, which possibly results from activation of the prejunctional M2 receptor subtype.

Acetylcholine↗

PubMed1997

Vertebral artery dissection not detected by initial angiography--case report.

A 57-year-old male presented with subarachnoid hemorrhage caused by vertebral artery dissection. The first cerebral angiogram on the day of ictus found minimal caliber change with lower contrast density at the V4 segment, but repeat angiography showed typical segmental narrowing of the artery on the 14th day. Repeat angiography with magnetic resonance imaging in the subacute stage would be useful to identify the cause of "angiogram-negative" subarachnoid hemorrhage.

Cerebral Angiography↗

PubMed1997

Biphenotypic blast crisis of chronic myelogenous leukemia: abnormalities of p53 and retinoblastoma genes.

The molecular mechanisms responsible for progression of chronic myelogenous leukemia (CML) to blast crisis have not been well defined. Blast crisis may be partially related to inactivation of tumor suppressor genes/such as p53 or retinoblastoma (Rb) gene. There is evidence for an association of blast cell phenotypes in CML with alterations of these genes: a strong association of myeloid phenotypes with abnormalities of the p53 gene and a weaker association of lymphoid phenotypes with abnormalities of the Rb system. We found a marked decrease in Rb gene product and rearrangements of the p53 gene simultaneously in two cases of biphenotypic blast crisis of CML (myeloid and B-lymphoid). These results support the association of blast cell phenotypes with alterations in tumor suppressor genes in CML blast crisis.

Blast Crisis↗

PubMed1997

Rapid disappearance of AML1/ETO fusion transcripts in patients with t(8;21) acute myeloid leukemia following bone marrow transplantation and chemotherapy.

To assess the clinical significance of monitoring minimal residual disease in t(8;21)(q22;q22) AML, RT-PCR assay was conducted during the clinical course of 12 patients who had undergone BMT or conventional chemotherapy. Two cases relapsed after BMT and chimeric RNA was detected soon after BMT in their bone marrow cells. The other three cases, in whom chimeric RNA was not detected after BMT, are in CR at 21 to 33 months following BMT. Similarly, four out of 7 cases who showed negative chimeric RNA after completion of chemotherapy have been in CR at 11 to 34 months following completion of chemotherapy. The present findings appear different from other studies which reported the detection of AML1-ETO chimeric RNA in long-term CR patients.

Adolescent↗

PubMed1997

Fumaric acid, anti-thrombin substance from Rhizopus javanicus.

An anti-thrombin substance (M2) was isolated from a culture broth of Rhizopus javanicus. Accumulation of M2 reached a maximum peak after 14 to 15 days of incubation and then decreased. The yield of M2 was 500 mg from 1 L of culture broth. M2 inhibited thrombin activity, and its 50% inhibition concentration in a reaction mixture containing 50 microL of 12.5 NIH unit/mL thrombin and 200 microL of 0.33% bovine fibrinogen was 63 microM. M2 had a specific activity for thrombin, but it was less responsive to plasmin, tissue-type plasminogen activator, urokinase, plasma kallikrein and glandular kallikrein. The structure of M2 was identified as fumaric acid by elementary analysis, FAB/MS, 1H-NMR, 13C-NMR and IR spectra.

Animals↗

PubMed1997

Mechanism of adrenomedullin-induced relaxation in isolated canine retinal arteries.

PURPOSE: To analyze the mechanism of action of adrenomedullin (AM), a peptide recently isolated from human pheochromocytoma, in isolated canine central retinal arteries and to compare the action of calcitonin gene-related peptide (CCRP). METHODS: Changes in isometric tension were recorded in helical strips of the arteries with and without the endothelium. RESULTS: Both AM and CGRP produced relaxation: EC50s were 2.62 and 0.71 x 10(-9) mol/l, respectively, and maximal relaxations were 85.1% and 84.3%, respectively. The AM-induced relaxation was endothelium-independent and unaffected by indomethacin, Ng-nitro-L-arginine, methylene blue, and glibencaalmide. Treatment with [8-37] CGRP markedly inhibited the relaxations caused by AM and CGRP. Treatment with a high concentration of sodium nitroprusside abolished the relaxation caused by nitroglycerin and atrial natriuretic peptide and reduced the relaxation caused by AM and CGRP. A high concentration of beraprost, a stable analog of prostaglandin I2, suppressed the response to AM and CGRP but not to nitroglycerin. CONCLUSIONS: Endothelium-independent relaxations to AM of canine retinal arteries may be mediated primarily by intracellular cyclic adenosine monophosphate by stimulation of CGRP1 receptors and partially by cyclic guanosine monophosphate; cyclic guanosine monophosphate is unlikely ot be produced by methylene blue-sensitive soluble guanylate cyclase. Prostanoids, nitric oxide, and adenosine triphosphate-dependent K+ channel opening do not appear to be involved in the AM-induced relaxation.

Adrenomedullin↗

PubMed1997

Changes in results of Gallium-67-citrate scanning after interferon therapy for chronic hepatitis C.

UNLABELLED: Gallium-67 scanning is useful for early diagnosis and grading of interstitial lung disease. In a study of the side effects of interferon (IFN) on the lungs of patients with chronic hepatitis C, we performed 67Ga scanning before and after IFN therapy. METHODS: The 66 subjects who underwent at least one scanning, before IFN therapy, were 8 patients with chronic persistent hepatitis (CPH), 21 with chronic aggressive hepatitis 2A (CAH-2A), 25 with chronic aggressive hepatitis 2B (CAH-2B) and 12 with cirrhosis. All had underlying hepatitis C viral infection. Of those patients, 20 were examined again within 1 mo after IFN therapy. Patients received an intravenous injection of 340 MBq 67Ga-citrate and were imaged 72 hr later. ROIs were established for anterior views of the lungs (Lu), liver (Li) and soft tissue of the upper arm as background (B). The counts per unit size of each region of interest were used in calculation of the ratios Lu/B and Li/B. RESULTS: The medians of Lu/B were 2.46 in CPH, 2.56 in CAH-2A, 2.50 in CAH-2B and 2.47 in cirrhosis. These differences were not statistically significant. The medians of Li/B were 6.42 in CPH, 6.14 in CAH-2A, 5.11 in CAH-2B and 4.03 in cirrhosis. The differences between the median Li/B of cirrhotic patients and the medians for patients with CPH, CAH-2A and CAH-2B were significant. After therapy, Lu/B was higher than before in 16 of the 20 patients and lower in the four other patients; the overall rise was significant (Wilcoxon rank-sum test). Li/B was higher than before in 11 of the 20 patients and lower in the nine other patients. CONCLUSION: IFN caused uptake of the radionuclide to increase in most patients. This method showed changes in the accumulation of 67Ga-citrate that could have been missed if the results had been inspected by eye. IFN can cause interstitial lung disease, but unlike other drugs with this side effect, the onset seems to be gradual enough to be detected quantitatively by 67Ga scanning.

Adult↗

PubMed1997

Molecular and genetic analysis of two patients with Bernard-Soulier syndrome--identification of new mutations in glycoprotein Ib alpha gene.

We investigated two unrelated patients with Bernard-Soulier syndrome (BSS) by performing molecular and genetic analysis. A flow cytometric and immunoblotting analysis showed GP Ib alpha to be absent from the platelet membrane of both patients. Other glycoproteins that formed GP Ib/IX/V complex were present on the platelets, but in decreased amounts. Therefore, GP Ib alpha gene from both cases was sequenced after PCR amplification and subcloning. We identified a homozygous mutation of a dinucleotide deletion within the TGTG repeat at cDNA number 972 to 975 in GP Ib alpha gene from Case 1. In Case 2, compound heterozygosity was demonstrated in GP Ib alpha gene; an insertion of a single base (T) at cDNA number 1,418 in one allele, and a deletion of a single base (A) within the 7-adenine repeat at cDNA number 1,438 to 1,444 in another allele. The three new mutations in both patients appeared to cause a frameshift, which created a new termination codon shortly thereafter, and thus lead to a GP Ib alpha deficiency on the platelet membrane. Truncated mutant proteins could be detected in the plasma and platelets of Case 2, but not of Case 1. According to these findings, it is thus supposed that the properties and conformation of additional COOH-terminal peptides, which were supposedly synthesized as results of the mutations, may have an important role on the processing of mutant GP Ib alpha in megakaryocytes and platelets.

Adult↗

PubMed1997

[Leukoencephalopathy probably caused by tacrolimus hydrate after stem cell transplantation in a girl with MDS 7 monosomy].

Leukoencephalopathy probably caused by tacrolimus hydrate after stem cell transplantation in a girl with MDS 7 monosomy is reported. The conditioning regimen consisted of thiotepa (150 mg/m2 x 4), melphalan (70 mg/m2 x 2) and 12 Gy total body irradiation. She received peripheral blood CD34 positive cells (4.17 x 10(6)/kg) from her HLA-mismatched father and tacrolimus hydrate was used for GVHD prophylaxis. Engraftment was rapid and grade 1 acute GVHD of the skin responded well to pulse therapy. From day 27 she became irritable and sleepless, and right facial convulsions developed on day 37. No abnormality was found in the cerebrospinal fluid. Cranial CT findings showed no abnormalities except for low density lesions around the bilateral ventricle. Leukoencephalopathy was suspected and tacrolimus hydrate was discontinued. Thereafter psychosomatic symptoms improved, temporarily however, similar symptoms again developed following cyclosporine administration. Therefore we had to halt the administration of both tacrolimus and cyclosporine. She died on day 104 because of GVHD and fungal infection without recovering from leukoencephalopathy.

Brain Diseases↗

PubMed1997

Perforated diverticulum of the transverse colon.

We report a case of perforated diverticulitis of the transverse colon. The preoperative diagnosis of perforated appendicitis was made on the basis of findings of both ultrasonography and CT. At surgery, an inflammatory mass resembling carcinoma was found in the transverse colon, and segmental resection was then performed. Diverticulitis of the transverse colon is rare, and there have been few reports in the English-language medical literature. This report describes a true diverticulum of the transverse colon that presented as acute diverticulitis.

Adult↗

PubMed1997

Modulation by neurogenic acetylcholine of nitroxidergic nerve function in porcine ciliary arteries.

PURPOSE: To determine whether nitroxidergic, cholinergic, and vasoactive intestinal polypeptide (VIP)-mediated nerves participate in the regulation of porcine ciliary arterial tone and to analyze the mechanisms underlying the neuronal interaction. METHODS: Changes in isometric tension were recorded in helical strips of the arteries, which were stimulated by transmurally applied electrical pulses or nicotine. The presence of perivascular nerve fibers containing reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase, acetylcholinesterase, and VIP immunoreactivity were determined histologically. RESULTS: Transmural electrical stimulation (2, 5, and 20 Hz) and nicotine produced a relaxation of the arterial strips denuded of the endothelium and contracted with prostaglandin F2alpha. The response was not influenced by timolol but was abolished by oxyhemoglobin and methylene blue. N(G)-nitro-L-arginine, a nitric oxide (NO) synthase inhibitor, abolished the neurogenic relaxation, and L-arginine restored the response. Physostigmine inhibited, but atropine potentiated, the neurogenic response. The relaxation was attenuated by acetylcholine but was not influenced by VIP. There were nerve fibers and bundles containing NADPH diaphorase, acetylcholinesterase, and VIP immunoreactivity in the adventitia of ciliary arteries. CONCLUSIONS: Porcine ciliary arteries are innervated by NO synthase-containing nerves that liberate NO, possibly as a neurotransmitter on excitation to produce muscular relaxation. Nitroxidergic nerve function is inhibited by acetylcholine released from cholinergic nerve, possibly because of impaired production or release of NO. VIP does not seem to function as a neurotransmitter or a modulator.

Acetylcholine↗

PubMed1997

[A case of an adult neuroblastoma with bone-marrow metastases: 131I-MIBG scintigraphy in comparison with MRI].

To detect a primary neuroblastoma lesion and its metastases, 131I-MIBG scintigraphy was performed for a 24-year-old woman who had a high level of serum catecholamine. 131I-MIBG scintigrams showed high radioactivity in the left upper quadrant, pelvic bone, and vertebral bodies. A biopsy of the pelvic bone revealed metastasis from the neuroblastoma. After four chemotherapy courses, the accumulation of 131I-MIBG decreased after each course; however, scintigraphy performed after the last chemotherapy course showed focal mild uptake in the right sacroiliac. The presence of residual tumor in the sacroiliac was confirmed histologically. On the other hand, T1-weighted and T2-weighted MR images performed before the treatment showed low signal intensity and high signal intensity in the pelvic bone, respectively. After the fourth chemotherapy course, T2-weighted MR images showed low signal intensity in the pelvic bone; however, it was difficult to determinate whether it should improve. To assess the effect of treatment of neuroblastoma, 131I-MIBG scintigraphy was considered more useful than MRI.

3-Iodobenzylguanidine↗

PubMed1997

[Successful surgical correction of incomplete endocardial cushion defect in a 65-year-old female].

We report a case of surgical correction of a 65-year-old female. She presented severe congestive heart failure and preoperative cardiac catheterization showed massive left to right shunt (87%), mild mitral regurgitation, severe tricuspid regurgitation and pulmonary hypertension. The operative procedure consisted of annuloplasty of mitral valve (Kay's method), patch closure of the ostium primum defect and annuloplasty of tricuspid valve. Postoperative examination showed complete competence of mitral valve and improved functional capacity. This is the fourth successful case report of surgical correction of incomplete endocardial cushion defect in patients older than 65-year-old in Japan to our knowledge. Surgical correction of incomplete endocardial cushion defect should be recommended even in elder patients.

Age Factors↗

PubMed1997

[Double negative adult T-cell leukemia with hemophagocytic syndrome].

A 79-year-old woman was admitted with general fatigue, jaundice and hepatosplenomegaly. Perpheral blood examination showed 8.0 g/dl Hb, 15 x 10(3)/microliter platelet and 10,490/microliter leukocytes with 86% abnormal lymphocytes. Immunophenotypic analysis of abnormal lymphocytes demonstrated CD2(+), CD3(+/-), CD4(-), and CD8(-). Serum antibody for HTLV-1 was positive. In addition, the monoclonal integration of HTLV-1 proviral DNA into the genome of leukemic cells was demonstrated on Southern blot hybridization. Bone marrow revealed ATL cell in vasion with myelofibrosis and hemophagocytic cell proliferation. Therefore, adult T-cell leukemia with hemophagocytic syndrome was diagnosed. She was treated with methyl prednisolone pulse therapy and gammaglobulin. But she died of hepatic failure 14 days after hospitalization. On autopsy, EB virus LMP-1 was detected in ATL cells in bone marrow. ATL with hemophagocytosis is relatively rare. The association of both pathological states was discussed.

Aged↗

PubMed1996

[Clinical study of occupational uroepithelial cancer].

We studied 438 persons who were engaged in the production and use of aromatic amines (benzidine sulfate, beta-naphthylamine, alpha-naphthylamine and dianisidine). Among these 438 persons, 88 new cases of occupational uroepithelial cancer had occurred from 1949 to 1995. The incident rate of occupational uroepithelial cancer was 20.1%. The average exposure period of these 88 cases to the aromatic amines was 7.40 years (range, 0.75-26.75), and the incidence rate of tumors increased with the length of exposure to aromatic amines. The average latent period was 26.79 years (range, 1.33-48.50), and the average age of first onset was 52.59 (range, 24-79). Recently it has been determined that the longer the latent period, the older the age of first onset. Of these 88 cases, the tumor sites were bladder in 67 cases (76.1%) and upper urinary tract (renal pelvis and/or ureter) in 5 cases (5.7%). The other 16 cases (18.2%) were the bladder and upper urinary tract. The screening examination for chemical workers using urinary cytology was begun in 1962. In our cases, urine cytology was a useful method for diagnosing occupational uroepithelial cancer. As for initial treatment of the 88 cases, transurethral surgery was most frequently performed, that is on 58 cases (65.9%). However, eight cases (9.1%) had to undergo a total nephroureterectomy, and six cases (6.8%) had a total cystectomy. Recurrence was observed in 61 cases (69.3%) out of the 88 patients with an average of 1.81 times. The other organic cancers developed in 39 cases (8.9%) out of 438 workers who were exposed to aromatic amines and in 8 cases out of 88 patients (9.1%). Prognosis of the 88 patients is that, the number of alive and dead is 51 (58.0%) and 37 (42.0%) respectively on December 31, 1995. Twenty-eight patients (31.8%) died of uroepithelial cancer, and five patients (5.7%) died of other organic cancers. The survival rates of 5, 10, 15 and 20 years was 87.9%, 74.0%, 65.9% and 56.3%, respectively. From these results, patients with occupational uroepithelial cancer and workers who are exposed to aromatic amines should undergo long term observation.

2-Naphthylamine↗

PubMed1996

Hypocalcemia associated with 5-fluorouracil and low dose leucovorin in patients with advanced colorectal or gastric carcinomas.

BACKGROUND: The biochemical modulation of 5-fluorouracil (5-FU) by leucovorin (LV) has demonstrated significantly increased response rates in comparison with the use of 5-FU alone in patients with advanced colorectal carcinoma. However, the higher response rate of LV/5-FU may occur at the expense of increased toxicity and side effects such as diarrhea, myelosuppression, and mucositis. During chemotherapy, a high incidence of hypocalcemia associated with this chemotherapy regimen was noted. This study was therefore aimed at assessing the side effects of chemotherapy using low dose LV/5-FU on calcium metabolism. METHODS: Twenty-five patients with advanced gastric or colorectal carcinoma were treated with chemotherapy comprised of low dose LV administered at 20 mg/m2/ day by intravenous bolus, followed by 1-hour intravenous infusion of 5-FU at 425-600 mg/m2/day for 5 consecutive days every 28 days. RESULTS: The toxic effects were generally mild, and included diarrhea, mucositis, leukopenia, and nausea/vomiting. Fifteen patients (65%) experienced hypocalcemia. The plasma 1,25-(OH)2D3 levels were significantly reduced on Day 5 due to the chemotherapy. CONCLUSIONS: The toxic effects of the regimen were generally mild. However, a high percentage of hypocalcemia occurred with the combination of LV/5-FU. It is therefore necessary to examine carefully the serum calcium levels of patients when using this chemotherapeutic modality.

Aged↗

PubMed1996

In vitro expansion of hematopoietic progenitor cells induces functional expression of Fas antigen (CD95).

Fas antigen (Fas Ag; CD95) is a cell surface molecule that can mediate apoptosis. Bcl-2 is a cytoplasmic molecule that prolongs cellular survival by inhibiting apoptosis. To investigate the role of both molecules in hematopoiesis, we evaluated the expression of Fas Ag and Bcl-2 on CD34+ hematopoietic progenitor cells expanded in vitro. CD34+ cells isolated from bone marrow were cultured in iscove's modified Dulbecco's medium supplemented with 10% fetal calf serum, 1% bovine serum albumin, 50 ng/mL stem cell factor, 50 ng/mL interleukin-3 (IL-3), 50 ng/mL IL-6, 100 ng/mL granulocyte colony-stimulating factor, and 3 U/mL erythropoietin for 7 days. Colony-forming unit of granulocytes/macrophages (CFU-GM) and burst-forming unit of erythroids (BFU-E) were expanded 6.9-fold and 8.8-fold in number at day 5 of culture, respectively. Freshly isolated CD34+ cells did not express Fas Ag, whereas approximately half of them expressed Bcl-2. CD34+ cells cultured with hematopoietic growth factors gradually became positive for Fas Ag and rapidly lost Bcl-2 expression. Furthermore, apoptosis was induced in the cultured CD34+ population when anti-Fan antibody (IgM; 1 microgram/mL) was added, as shown by significant decrease in the number of viable cells, morphologic changes, induction of DNA fragmentation, and significant decrease in the number of clonogenic progenitor cells including CFU. GM and BFU-E. These results indicate that functional expression of Fas Ag is induced on CD34+ cells expanded in vitro in the presence of hematopoietic growth factors. Induction of Fas Ag and downregulation of Bcl-2 may be expressed as part of the differentiation program of hematopoietic cells and may be involved in the regulation of hematopoiesis.

Adult↗

PubMed1996

Pre- and postjunctional modulation by endothelin-1 of the adrenergic neurogenic response in canine mesenteric arteries.

Transmural electrical stimulation (5-30 Hz) produced a frequency-dependent increase in the perfusion pressure of isolated, perfused dog mesenteric artery segments, which was suppressed by prazosin and abolished by tetrodotoxin. Treatment with endothelin-1 in low concentrations (10(-10) and 3 x 10(-10) M) inhibited the response to electrical nerve stimulation. The effect was not affected by NG-nitro-L-arginine, indomethacin and removal of the endothelium. The endothelin-1-induced inhibition was antagonized by 10(-7) M BQ123[cyclo(D-Trp-D-Asp-L-Pro-D-Val-L-Leu-)sodium], an endothelin ETA receptor antagonist, but not by 10(-5) M BQ788 [N-cis-2,6-dimethyl-piperidinocarbonyl-L- gamma-methylleucyl-D-1-methoxycarbonyltryptophanyl-D-norleuc ine], an antagonist of endothelin ETB1 and ETB2 receptors. IRL1620 [Suc-[Glu9, Ala11,15]endothelin-1-(8-21)], a selective endothelin ETB1 receptor agonist, did not alter the response to electrical stimulation. However, raising the concentration of endothelin-1 to 10(-9) M or higher potentiated the response. Similar results were also obtained in mesenteric artery strips in response to electrical stimulation. Endothelin-1 at low concentrations did not alter the contraction caused by exogenous norepinephrine in the artery strips, whereas the peptide at high concentrations potentiated the response. 3H-overflow evoked by transmural electrical stimulation from tissues prelabeled with [3H]norepinephrine was decreased by endothelin-1 (3 x 10(-10) M) in the superfused dog mesenteric arteries. It is concluded that endothelin-1 at low concentrations activates prejunctional endothelin ETA receptors and inhibits adrenergic nerve-mediated contractions by an inhibition of amine release, whereas the peptide at high concentrations potentiates the neurally induced contractions by a postjunctional enhancement, via endothelin ETA receptors, of the action of norepinephrine. Low concentrations of endothelin-1 appear to act as a vasodilator in adrenergically innervated mesenteric artery

Animals↗