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Biomedical subjects

N Ohtani

Publications and source records attributed to N Ohtani.

At least 55 records · Page 3Linked to original sources
PubMed1994

[Recent advances and problems in peripheral arterial reconstruction].

Recent advances in the field of peripheral arterial reconstruction have been remarkable. These advances are mainly derived from the development of diagnostic technology such as Doppler ultrasound analysis, further refinement of surgical technique including surgical instruments and materials, and naturally improvement of patient care in the pre-, peri- and postoperative period. During the past 14 years we have performed peripheral arterial reconstruction in 1,200 cases (1,660 limbs) mainly with occlusive lesion due to arteriosclerosis obliterans. In our hand, aorto-iliac occlusive lesion has been routinely bypassed with Dacron prostheses and the secondary patency rate at eleven years reached 96.5%. The main problems encountered in this region were anastomotic aneurysm in the femoral artery (3.9%) and graft infection (1.2%). In the infrainguinal region there are still problems to be solved, although the primary (secondary) 5 year patency rates of reversed vein graft as well as in situ vein graft including femoro-popliteal below knee and femoro-crural bypasses have exceeded 70% (85%). First, there is no graft material comparable to the autogenous vein (AVG). Secondly, many of the AVG should suffer occlusive pathological changes from the environment in the long term following surgery. At the present time, we have no effective method to solve these problems, therefore we should follow up the patients heedfully to maintain the graft patency as well as to improve their quality of life and prognosis.

Anastomosis, Surgical↗
PubMed1993

Biologically active extracellular products of oral viridans streptococci and the aetiology of Kawasaki disease.

A bacteriological study of isolates from the oral cavity of patients with Kawasaki disease (KD), age-matched non-KD patients and healthy children, showed that over half the KD and control isolates had gram-positive, catalase-negative cocci. About 50% of these organisms were identified as viridans streptococci by means of an API Strep 20 kit. Further identification by fluorometric DNA-DNA hybridisation demonstrated that the predominant species were S. oralis and S. mitis, each of which accounted for 25% of the isolates of viridans streptococci; 40% of viridans strains were unidentifiable; and S. sanguis and S. parasanguis were minor components. Studies in vivo showed that insertion of culture supernates of most of the viridans streptococci increased capillary permeability and induced redness with swelling and occasional bleeding in rabbit skin. One-third of S. mitis strains and one-fifth of the unidentified strains caused aggregation of human blood platelets, whereas S. oralis and other strains had no such effect. The distribution of extracellular lipoteichoic acids and glucan produced in the presence of sucrose was also examined. There were no significant differences in the recovery rate of viridans streptococci forming these biologically active extracellular products between KD and control groups.

Adult↗
PubMed1992

Pancreatic arteriovenous malformation with pancreatitis involving a pancreatico-venous fistula.

An arteriovenous malformation of the pancreas is a very rare disease, but its presentation is distinct and unique. In this report, we describe a patient who presented with this malformation which was localized in the tail of pancreas and demonstrated by abnormal angiography findings. The patient was a 60-year-old male with severe left hypochondralgia. Angiography revealed an increased blood volume in the tail of the pancreas with arteriovenous shunting. Secondary pancreatitis caused by the arteriovenous malformation was suspected by abnormal laboratory data, and confirmed by histology from the resected tail of the pancreas. This is a very rare report in which pancreatic arteriovenous malformation involving a pancreatico-venous fistula was confirmed by endoscopic retrograde cholangiopancreatography (ERCP).

Arteriovenous Fistula↗
PubMed1992

[Two cases of broncholithiasis removed by bronchofiberscopy].

Two cases of broncholithiasis, removed bronchoscopically, are reported. Case 1 was a 38-year-old female who was admitted with hemoptysis. The chest tomogram showed calcification near the right middle lobe bronchus. Bronchoscopy revealed a broncholith in B4. Component analysis showed that more than 98% of this stone consisted of calcium carbonate. Case 2 was a 75-year-old male who was hospitalized because of continuous cough. The chest radiograph showed calcification and atelectasis in the right upper lobe. Bronchoscopically, right B3 was obstructed by a broncholith. After removal of the stone, the distal part of B3 was noted to be filled with pus. Analysis of the stone's composition revealed calcium phosphate (77%) and calcium carbonate (23%).

Adult↗
PubMed1991

Oncogenic germ-line mutations in Sp1 and ATF sites in the human retinoblastoma gene.

The transcription of a eukaryotic gene is a consequence of intricate interactions between members of a set of transcription factors. We describe here evidence indicating that at least two distinct DNA-binding factors play an important part in the transcription of the human retinoblastoma gene (Rb). One of the factors reacts with a sequence overlapping with a potential Sp1 recognition sequence in the promoter region of the gene, the other with a nearby ATF recognition sequence. We have identified two naturally occurring point mutations in these recognition sequences that cause hereditary retinoblastoma. The nuclear factors do not bind to the mutant sequences. We infer that these nuclear factors are necessary for the expression of the Rb gene and the suppression of cancer.

Activating Transcription Factors↗
PubMed1991

Allele-specific hypermethylation of the retinoblastoma tumor-suppressor gene.

Inactivation of the retinoblastoma gene appears to have a fundamental role in the genesis of retinoblastoma, osteosarcoma, and other malignant tumors. The gene is generally inactivated because of loss-of-function mutations, although epigenetic phenomena, such as hypermethylation of the promoter region, could possibly have the same effect. We investigated the methylation pattern at the 5' end of the retinoblastoma gene, including its promoter region and exon 1, in DNA purified from 56 primary retinoblastomas. We found five tumors with evidence for hypermethylation, all from unilateral, simplex patients. No methylation abnormalities were detected in DNA purified from the leukocytes from these patients. It is interesting that in one of these tumors the hypermethylation was confined to one allele. There were no mutations in a 1,306-bp sequence including the hypermethylated region that might account for the allele-specific hypermethylation. We believe that the hypermethylation of the retinoblastoma gene that we found in these tumors corresponds to the allelic inactivation of the gene, and we speculate that erroneous hypermethylation without alteration of nucleotide sequence occasionally plays a role in the genesis of this cancer. If this is true, then retinoblastomas with hypermethylation might be treatable with chemotherapeutic agents that interfere with methylation of DNA.

Alleles↗
PubMed1990

Change of left atrial systolic pressure waveform in relation to left ventricular end-diastolic pressure.

The relation between the left atrial systolic pressure waveform and left ventricular end-diastolic pressure was observed in 17 patients who underwent diagnostic cardiac catheterization. Left atrial pressure and left ventricular pressure were simultaneously recorded from a multisensor catheter before and during angiotensin infusion. Left ventricular systolic pressure and left ventricular end-diastolic pressure were 133 +/- 17 and 12.3 +/- 3.2 mm Hg, respectively, before angiotensin infusion and increased to 168 +/- 18 (p less than 0.01) and 19.4 +/- 4.5 mm Hg (p less than 0.01), respectively, during infusion. The left atrial systolic pressure curve consisted of two positive waves--a first wave (A) and a second wave (A'). The A and A' wave pressures were 11.6 +/- 2.3 and 10.2 +/- 3.9 mm Hg, respectively, before angiotensin infusion and 16.5 +/- 2.9 (p less than 0.01) and 18.1 +/- 4.7 mm Hg (p less than 0.01), respectively, during infusion. The ratio of A'/A of left atrial systolic pressure was 0.81 +/- 0.27 before angiotensin infusion and 1.08 +/- 0.14 (p less than 0.01) during infusion. The ratio of A' to A of left atrial systolic pressure was linearly related to left ventricular end-diastolic pressure before and during (p less than 0.01) angiotensin infusion. The amplitude of the A wave exceeded that of the A' wave at normal left ventricular end-diastolic pressures. However, as the left ventricular end-diastolic pressure increased either at rest or during angiotensin infusion, the amplitude of the A' wave increased and often exceeded that of the A wave. These results suggest that the second (A') wave might be attributed to the increased reflection associated with increased left ventricular end-diastolic pressure.

Adult↗
PubMed1990

Global and regional diastolic filling dynamics in compensated dilated cardiomyopathy.

To assess the left ventricular (LV) global and regional (anterior, apical, inferior) diastolic filling dynamics in compensated dilated cardiomyopathy (DCM), we measured left ventricular pressure and instantaneous volume from angiography in 7 normal controls (CTL) and 6 DCM patients with sinus rhythm. Global and regional peak filling rate (PER), time constant of LV pressure decline (T; Weiss's method) and LV chamber stiffness (k; Gaasch's method) were calculated. In DCM, left ventricular end-diastolic volume (ml/m2) was larger than in CTL (137 +/- 29 vs. 74 +/- 6, p less than 0.001), and stroke index (ml/m2) was not different from CTL (46 +/- 14 vs. 46 +/- 8, NS), indicating a compensated state of LV. Mitral valve opening pressure (mmHg) tended to increase in DCM compared with CTL (12 +/- 6 vs. 8 +/- 4). Global PFR (ml/sec/m2) (CTL = 216 +/- 47 vs. DCM = 201 +/- 36) and k (CTL = 0.044 +/- 0.023 vs. DCM = 0.029 +/- 0.016) were not different between 2 groups. However, T (msec) was markedly prolonged in DCM compared with CTL (61 +/- 10 vs. 35 +/- 5, p less than 0.001). In CTL, regional PFR (1/sec) showed almost the same values in each region, but in DCM, apical region showed higher PFR than in other regions. Thus, early diastolic filling might play an important role in maintaining the total transmitral flow in DCM despite severe impairment of LV relaxation. This compensation could be related mainly to accelerated regional lengthening of the LV apical region.

Adaptation, Physiological↗
PubMed1990

[Comparison of myocardial perfusion assessments by digital subtraction angiography with those of left ventricular wall dynamics].

In clinical and experimental studies we assessed images of digital subtraction coronary angiography (DSA) for evaluating regional myocardial perfusion. Myocardial perfusion was assessed by injecting contrast medium into the coronary artery, and by imaging the regional myocardium using DSA. On the time-density curve obtained from the myocardial region of interest, we calculated the time to peak concentration (TPC) and the exponential washout rate (T). TPC and T were measured in five patients with stable effort angina pectoris (AP) and left anterior descending (LAD) lesions before and after percutaneous transluminal coronary angioplasty (PTCA). The values of 1/T increased significantly from 0.09 +/- 0.02 l/sec to 0.21 +/- 0.04 l/sec (p less than 0.01) after PTCA, but l/TPC did not change. No significant difference in ejection fractions was observed between the patients with AP and the normal subjects (n = 7), while the regional percent area shrinkage in the anterolateral and apical regions supplied by the LAD was significantly decreased in the patients with AP compared with those of normal subjects (anterolateral: 39.8 +/- 8.8% vs 51.3 +/- 6.8%, apical: 36.6 +/- 8.4% vs 52.4 +/- 13.4%, both p less than 0.01). In 10 anesthetized dogs with varying degrees of reduction in the left circumflex coronary artery (LCX) blood flow (CBF: categories of stenosis (S1-S5), we compared 1/TPC and 1/T with regional myocardial function (systolic wall thickening: %WTh). With varying LCX stenosis, there were no significant changes in heart rate and mean aortic pressure and significant linear correlations were observed between %WTh and 1/TPC (r = 0.51), between %WTh and 1/T (r = 0.55). At S1 (CBF: 100-90% of the control), neither %WTh nor 1/TPC differed from that of the controls, but 1/T was significantly decreased (80% of the controls, p less than 0.01). From S3 (CBF: 79-60%) to S5 (CBF: 39-0%), %WTh, 1/TPC and 1/T were significantly decreased from those of the control levels (all p less than 0.01). However, at S5 (CBF: 39-0%) the values of 1/TPC (71% of controls) and 1/T (33%) did not differ from those at S4; whereas, %WTh was markedly reduced and the systolic thinning of the ventricular wall occurred at S5. Therefore, in critical coronary stenosis, 1/T was more sensitive than 1/TPC or wall dynamics for assessing myocardial ischemia. Both 1/TPC and 1/T, as well as %WTh, were useful for assessing moderate myocardial ischemia; however, these DSA indices had considerable limitations for evaluating the severity of myocardial ischemia when CBF was markedly reduced.

Aged↗
PubMed1989

Analysis of digital subtraction coronary angiography for estimation of flow reserve in critical coronary stenosis.

To examine the accuracy of digital subtraction angiographic assessment of coronary flow reserve in critical coronary stenosis, time-density curves were obtained from digital angiograms for a myocardial region of interest. Time-to-peak contrast (TPC) and contrast washout rate (T) were measured in 11 patients with critical 1-vessel lesions before and after percutaneous transluminal coronary angioplasty (PTCA). Collectively, the values of TPC and T were significantly shortened, from 5.8 +/- 1.1 to 4.4 +/- 1.0 seconds (p less than 0.01) and from 11.3 +/- 4.0 to 5.2 +/- 1.2 seconds (p less than 0.001) after PTCA, respectively. All 11 patients except 1 showed shortened T after PTCA; however, in 5 of the 11 patients, TPC after PTCA had approximately the same values as those before PTCA. In experiments in dogs with critical circumflex stenosis, coronary flow and posterior wall thickening at rest were not different from control; however, contrast media-induced hyperemia was markedly attenuated, accompanied by a significant prolongation of T (7.7 +/- 4.5 vs 15.8 +/- 1.9 seconds, p less than 0.01) and completely unchanged TPC (both 6.8 seconds). With simultaneous tracings of coronary flow and time-density curves, TPC and the washout phase on the curve corresponded with contrast-induced transient flow reduction and hyperemic phases, respectively. It is concluded that T appears more sensitive than TPC when basal coronary flow is maintained to almost normal levels, as in patients with stable effort angina pectoris having critical coronary stenosis.

Aged↗
PubMed1989

A case of myocardial damage following acute paracetamol poisoning.

A 24-year-old woman was admitted to our hospital with acute paracetamol poisoning, and severe hepatic injury. The peak blood level of GOT, GPT and LDH were 32,600 U, 119,200 U and 36,500 U respectively. Glucagon-insulin and glutathione were administered to save the liver function. On the third hospital day, hemodialysis was administered to treat acute renal failure. On the 16th hospital day, when the liver and renal functions recovered, severe pulmonary congestion occurred and right heart catheterization revealed high pulmonary pressure. Echocardiography showed left ventricular enlargement accompanied by a severe diffuse impairment of left ventricular wall motion. Multi-focal ventricular arrhythmia was frequent during this period. Hemodialysis and artificial respiration were carried out for the treatment of heart failure. Three months after admission, myocardial perfusion scintigram showed patchy reduction in the uptake of Tl-201 throughout the myocardium, and left ventriculography showed mild diffuse impairment of the LV wall motion (ejection fraction: 49%). In this case, acute heart failure appeared approximately 2 weeks after the severe hepatic injury. Apparently myocardial damage following paracetamol overdosage is caused not only by direct toxicity but by severe metabolic derangement.

Acetaminophen↗
PubMed1987

Synthesis and quantitative structure-activity relationship analysis of N-triiodoallyl- and N-iodopropargylazoles. New antifungal agents.

New series of N-(2,3,3-triiodoallyl) and N-(3-iodopropargyl) azole derivatives (100 compounds) involving pyrrole, pyrazole, imidazole, triazole, and tetrazole nuclei were synthesized successively with the aid of quantitative structure-activity relationship (QSAR) analysis to obtain potent antifungal agents. Starting from the derivatives of nitropyrrole-containing antibiotics, the QSAR analysis of the pyrrole derivatives against Candida albicans and Trichophyton mentagrophytes strains indicated the positive contribution of the nitro group and negative effect of the size of molecule. Further application of the QSAR analysis on the multi-azole derivatives revealed the importance of hydrophobicity and electronegativity as well as steric effect to the activities and led to the synthesis of one of the most potent iodo compounds, 2-(2,3,3-triiodoallyl)tetrazole (67, ME1401).

Allyl Compounds↗
PubMed1987

Comparison of the effects of Fe2+ and Cu2+ on prostaglandin synthesis in rabbit kidney medulla slices.

The effects of Fe2+ and Cu2+ on the generation of medullary prostaglandins E2 and F2 alpha have been compared. Fe2+ markedly promoted the lipid peroxidation of rabbit kidney medulla slices. The lipid peroxidation induced by Fe2+ inhibited both prostaglandin E2 and prostaglandin F2 alpha formation to a similar extent. While Cu2+ produced only a small increase in lipid peroxidation, it had a powerful inhibitory effect on prostaglandin E2 formation. Simultaneously, prostaglandin F2 alpha production was increased. In the presence of Cu2+ the net increased amount of prostaglandin F2 alpha was much smaller than the net decreased amount of prostaglandin E2 (15-20%). These results suggest that Cu2+ has the potential to modulate prostaglandins E2 and F2 alpha synthesis by affecting endoperoxide E2 isomerase or endoperoxide reductase independent of its peroxidative action.

Animals↗
PubMed1987

Effect of pyridoxine on prostaglandin synthesis in rabbit kidney medulla slices.

Pyridoxine stimulated the generation of prostaglandin E2 in rabbit kidney medulla slices. Moreover, pyridoxine in the presence of aspirin reduced the release of linoleic acid, but enhanced the release of arachidonic acid from the medulla slices as compared with aspirin alone, indicating that the enhancement of prostaglandin E2 formation elicited by pyridoxine may be ascribed to an increased conversion of linoleic acid to arachidonic acid. These results suggest that pyridoxine can be an important modulating factor in prostaglandin synthesis by the kidney.

Animals↗