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Biomedical subjects

M Toyama

Publications and source records attributed to M Toyama.

At least 37 records · Page 2Linked to original sources
PubMed2000

Inflammatory oedema induced by the lys-49 phospholipase A(2) homologue piratoxin-i in the rat and rabbit. Effect of polyanions and p-bromophenacyl bromide.

Piratoxin-I (PrTX-I) is a Lys-49 phospholipase (PLA(2)) homologue, isolated from Bothrops pirajai snake venom, that has no phospholipase activity. In this study, we investigated the in vivo oedematogenic activity of PrTX-I in both the rat and the rabbit as well as the ability of PrTX-I to activate rat mast cells in vitro. In the rat paw and skin, PrTX-I (3-100 microg/paw) induced a dose-dependent oedema that was associated with extensive mast cell degranulation. The involvement of mast cells in PrTX-I-mediated oedema formation in the rat was further confirmed by the findings that this protein significantly activated rat peritoneal mast cells in vitro, causing the release of [(14)C]5-hydroxytryptamine ([(14)C]5-HT; 51 +/- 1%). In the rabbit, PrTX-I (10-100 microg/site) also induced dose-dependent skin oedema formation that was not affected by either mepyramine (a histamine H(1) receptor antagonist) or cyproheptadine (1.0 microg/site), indicating that mast cells do not play a role in this animal species. The bradykinin B(2) receptor antagonist Hoe 140 (0.5 microg/site) and the platelet-activating factor (PAF) receptor antagonist WEB 2086 (200 microg/site) also failed to affect the PrTX-I-induced rabbit skin oedema, ruling out the involvement of kinins and PAF. The PLA(2) inhibitor p-bromophenacyl bromide greatly reduced the PrTX-I-induced oedema in both the rat and the rabbit, and also inhibited the rat in vitro mast cell activation induced by this PLA(2) homologue. The polyanions heparin and dermatan sulphate efficiently prevented oedema formation in both species, and heparin inhibited PrTX-I-induced rat mast cell degranulation. Our results are consistent with the suggestion that the cationic charge of PrTX-I plays a major role in the inflammatory responses induced by this PLA(2) homologue.

Animals↗
PubMed2000

Low-dose dobutamine radionuclide ventriculography for prediction of myocardial viability: quantitative analysis of regional left ventricular function.

BACKGROUND: It is important to distinguish viable myocardium from necrotic tissue in order to decide upon therapy in patients with ischemic heart disease. HYPOTHESIS: We verified the hypothesis that quantitative analysis of regional left ventricular function using low-dose dobutamine radionuclide ventriculography (RNV) can sensitively predict myocardial viability and compared its usefulness with thallium-201 (201Tl) single-photon emission computed tomography (201Tl-SPECT). METHODS: Radionuclide ventriculography at rest and during low-dose dobutamine infusion (5 micrograms/kg/min), 201Tl-SPECT, and coronary angiography were performed in 51 subjects with severe ischemia-related stenosis of coronary arteries and 3 subjects without coronary artery disease. 201Tl uptake was assessed as normal (control), low perfusion (LP), or defect. We compared the response of regional function to dobutamine with the regional 201Tl uptake. The accuracy of both methods for identifying viable myocardium was investigated in 17 patients who underwent successful coronary revascularization, with a resulting improvement in wall motion. RESULTS: The increase in regional ejection fraction (delta r-EF) in response to dobutamine was significantly greater in the control (12 +/- 6%) and LP (16 +/- 11%) regions than in the defect (5 +/- 10%) regions. The increase in one-third regional ejection fraction (delta r-1/3EF) was also significantly higher in the control (14 +/- 7%) and LP (10 +/- 8%) regions than in the defect regions (5 +/- 6%). We defined myocardial viability as a delta r-EF > 5% or a delta r-1/3EF > 2%. The sensitivity and specificity of the delta r-EF for identification of myocardial viability were 91.4 and 55.5%, respectively. The sensitivity and specificity of the delta r-1/3EF were 91.4 and 66.6%, respectively; the corresponding values for 201Tl SPECT were 74.2 and 77.8%. CONCLUSION: Low-dose dobutamine RNV with quantitative analysis of regional left ventricular function was more sensitive for identification of viable myocardium than 201Tl-SPECT.

Aged↗
PubMed2000

Comparison of standard coronary artery bypass grafting and minimary invasive direct coronary artery bypass grafting. Early and mid-term result.

OBJECTIVES: We studied indications and problems involved in minimally invasive coronary artery bypass grafting (MIDCAB). METHODS: We compared patients profiles, graft patency, stenosis severity, morbidity, mortality, long-term survival and freedom from cardiac accidents in 174 patients undergoing elective standard coronary artery bypass grafting (CABG) and 128 undergoing between January 1996 and March 1999. RESULTS: No statistically difference was seen in gender, diabetes mellitus, renal failure, cerebrovascular accident, multi-vessel disease ratios, or left main trunk stenosis between 2 groups. Internal thoracic artery graft patency was 97% (114/118) and the rate of anastomotic stenosis (> 50%) was 9% (10/118) compared to 96% (213/221) in the MIDCAB group. The 3-year survival rate was 91% in the MIDCAB group and 92% in the CABG group and freedom from cardiac accidents, most involving pericutaneus transluminal coronary angioplasty retreatment, was 66% in the MIDCAB group and 88% in the CABG group. CONCLUSION: Although patency and stenosis incidence did not differ between 2 groups, freedom from cardiac accidents was lower in the MIDCAB group.

Aged↗
PubMed2000

Thickened intima of the aortic arch is a risk factor for stroke with coronary artery bypass grafting.

BACKGROUND: Perioperative stroke is one of the most serious complications of cardiac surgery. METHODS: Using transesophageal echocardiography, we estimated the intimal thickness of the thoracic aorta as an index of the severity of aortic atherosclerosis to determine the risk of stroke in coronary artery bypass grafting (CABG) patients. The study population comprised 315 consecutive patients who underwent isolated CABG with cardiopulmonary bypass. RESULTS: Five patients (1.6%) had perioperative cerebral stroke or systemic emboli. We compared the mean intimal thicknesses of the ascending aorta, aortic arch, and descending aorta. Mean thicknesses in patients without stroke were 2.07 +/- 0.76, 2.78 +/- 1.15, and 2.32 +/- 1.21 mm, respectively, and mean thicknesses in the stroke patients were 1.94 +/- 0.55, 6.94 +/- 3.79, and 3.39 +/- 1.85 mm, respectively. The patients with an intima of more than 5 mm at the aortic arch had a significantly greater incidence of perioperative stroke (p = 0.007). CONCLUSIONS: These results suggest that patients who have an aortic arch intima thickened to more than 5 mm are at a significantly high risk for perioperative stroke, and thus, the CABG procedure should be carefully evaluated to prevent such complications.

Aged↗
PubMed2000

Effect of crotapotin and heparin on the rat paw oedema induced by different secretory phospholipases A2.

The effects of crotapotin (a non-toxic and non-enzymatic acid polypeptide naturally complexed with phospholipase A2) and heparin on rat paw edema induced by different secretory phospholipases A2 (sPLA2) have been investigated. The ability of crotapotin to affect the enzymatic activity of the sPLA2(s) have also been evaluated. Secretory PLA2(s) obtained from both snake (Naja naja, Naja mocambique mocambique, Crotalus adamanteus and Crotalus durissus terrificus) and bee (Apis mellifera) venoms as well as that from bovine pancreas were used in this study. Rat paw oedema was induced by a single subplantar injection of the sPLA2s (5-30 microg/paw) in absence and presence of either crotapotin (10-100 microg/paw) or heparin (50 U/paw). Paw volume was measured using a hydroplethysmometer. Phospholipase A2 from Naja naja, Naja mocambique mocambique, Apis mellifera venoms and the basic component of Crotalus durissus terrificus venom all induced dose-dependent rat paw oedema whereas those from Crotalus adamanteus venom and bovine pancreas were ineffective. Paw oedema induced by PLA2(s) from both Naja naja and Apis mellifera venoms was significantly (P < 0.05) inhibited by crotapotin (0.1-100 microg/site) whereas the Naja mocambique mocambique venom PLA2-induced oedema was significantly potentiated (P < 0.05) by this polypeptide (40 microg/site). On the other hand, heparin (50 U/paw) had no effect on the paw oedema induced by PLA2 from Naja naja and Apis mellifera venoms but significantly inhibited the Naja mocambique mocambique venom PLA2-induced oedema. The measurement of the in vitro phospholipasic activity revealed that crotapotin inhibited by 60-70% the enzymatic activities of PLA2(s) from Crotalus adamanteus, Naja mocambique mocambique, Apis mellifera venoms and bovine pancreas. Our results suggest that despite the great homology between the various types of sPLA2 they interact with crotapotin on cell surfaces in different ways leading to either inhibition or potentiation of the paw oedema by a mechanism unrelated to their enzymatic activities. Since heparin reduced paw oedema induced by PLA2 from Naja mocambique mocambique venom it is likely that this sPLA2 is similar to the novel heparin-sensitive PLA2 found in mast cells.

Animals↗
PubMed2000

Magnetic resonance arthrography of the temporomandibular joint.

PURPOSE: This study evaluated the usefulness of magnetic resonance arthrography (MRAr) in imaging the pathologic temporomandibular joint (TMJ). PATIENTS AND METHODS: Thirteen TMJs of 11 patients with chronic TMJ pain and disability were examined with MRAr. T1-weighted and T2-weighted first spin-echo sequence with fat suppression images were obtained after the intra-articular injection of gadopentetate dimeglumine. RESULTS: The disc, the posterior attachment, and the presence of perforations and adhesions were evaluated in each image. All of these anatomic and pathologic structures were clearly detected. CONCLUSION: MRAr appears to be a promising imaging modality in detecting adhesions and perforations in the TMJ. The MRAr findings simplified the decision of whether a patient should undergo surgery.

Adult↗
PubMed2000

[Clinical study of aortic root replacement].

From 1990 to 1999, 19 patients underwent aortic root replacement. Annulo-aortic ectasia was observed in 14 patients, aortic dissection in 4, and aortitis in 1. Mean aortic cross-clamp times and cardiopulmonary bypass times were 163 +/- 44 and 247 +/- 99 min, respectively. Concomitant procedures were coronary artery bypass grafting in 3 patients, aortic arch replacement in 1 and aortic arch replacement and elephant trunk method in 2. There were two hospital deaths due to cardiac failure. There was one late death because of pharyngeal cancer 1.7 years after the operation. Seventeen survivors were followed for a mean duration of 4.4 years (0.6-9.3 years). There were no complications during this period. In conclusion, good results were obtained by modified Bentall operation.

Adult↗
PubMed1999

Decreased disk-eminence ratio is associated with advanced stages of temporomandibular joint internal derangement.

OBJECTIVE: To examine the possible correlation between the stage of internal derangement and the antero-posterior length of the disk in relation to the length of the articular eminence. STUDY DESIGN: Twenty asymptomatic volunteers with normal joints and 120 patients with TMJ dysfunction underwent MR imaging. The A-P length of the disk in relation to the length of the articular eminence (D/E ratio) was measured. RESULTS: The D/E ratio was 0.95 in the asymptomatic volunteers, 0.83 in patients with disk displacement with reduction, 0.74 in those with disk displacement without reduction and 0.57 in the patients with disk displacement and osteoarthritis. The relationship between the D/E ratio and the stage of internal derangement was statistically significant (P<0.01). CONCLUSION: The D/E ratio decreases with advancing internal derangement. We suggest that it is a reliable numerical method for staging the degree of the internal derangement.

Adult↗
PubMed1999

Mitral valve thrombus attached to the intact mitral valve associated with distal embolism.

A 61-year-old man was referred for cardiac investigation because embolism was suspected to be the cause of the sudden onset of severe pain in his right leg after a surgical procedure. The electrocardiogram revealed no atrial fibrillation. Transthoracic echocardiography demonstrated a tumor-like echo at the anterior mitral leaflet, and transesophageal echocardiography documented a mass 13x9mm in size, attached by a stalk to the left atrial side of the anterior mitral leaflet. The other parts of the mitral valve appeared to be intact. At emergency surgery, the mass was located in the center of the left atrial side of the anterior mitral leaflet. It mimicked a myxoma and had a stalk arising from the anterior leaflet. After resection of the mitral valve mass, catheter thrombo-embolectomy was performed and several long pieces of fresh thrombus were removed. On histological examination, the mass consisted of fresh thrombus tissue. No cellular component or myxoma tissue was documented. The distal embolus also consisted of fresh thrombus tissue. This is the first case of a thrombus of the intact mitral valve without atrial fibrillation.

Diagnosis, Differential↗
PubMed1999

Osmoregulation of vasopressin secretion in patients with the syndrome of inappropriate antidiuresis associated with central nervous system disorders.

To clarify the characteristics of vasopressin (AVP) secretion in patients with the syndrome of inappropriate antidiuresis (SIAD) related to central nervous system disorders, we examined the response of AVP secretion to osmotic stimulus by hypertonic saline infusion and analyzed the possible causative factors in six patients with SIAD associated with head trauma or cerebral infarction. Hyponatremia developed after head trauma in four patients and cerebral infarction in two patients. In all patients the clinical state and laboratory findings fulfilled the criteria for SIAD, which was supported by either nonsuppressible plasma AVP levels or effectiveness of treatments with water restriction, demeclocycline, nonpeptide V2 AVP antagonist or diphenylhydantoin. Although patterns of plasma AVP response to the osmotic stimulus varied, plasma AVP concentrations neither increased nor decreased to undetectable levels with a rise in plasma osmolality. In one patient, plasma AVP levels responded to increasing plasma osmolality when plasma osmolality normalized; in which the threshold and the sensitivity of osmostat were normal. In two other patients, AVP secretion responded to plasma osmolality after the treatment. The changes in AVP secretion were not due to nonosmotic stimuli for AVP release. In conclusion, this study shows that patients with SIAD and central nervous system disorders may have persistent AVP secretion with a loss of hypotonic suppression such as found in patients with adrenal insufficiency or depletional hyponatremia in central nervous system disorders, indicating that careful evaluation is necessary to determine the relationship between persistent AVP secretion and the pathogenesis of hyponatremic disorders.

Aged↗
PubMed1999

Concurrent infection with Legionella pneumophila and Pneumocystis carinii in a patient with adult T cell leukemia.

A 48-year-old woman was admitted to our hospital with high fever, chills, cough, and exertional dyspnea. On admission, the chest roentgenogram and computed tomography scan showed bilateral alveolar infiltration in the middle and lower lung fields. Microscopic examination of the bronchial lavage fluid showed flower cells typical for adult T-cell leukemia (ATL) and cysts of Pneumocystis carinii, and Legionella pneumophila serogroup 1 grew on buffered charcoal yeast extract (BCYE)-alpha agar. The patient was successfully treated with antibiotics including trimethoprim/sulfamethoxazole, erythromycin, and sparfloxacin. Remission of ATL was achieved after three courses of antileukemic chemotherapy. Mixed infection of opportunistic pathogens should be considered in patients with ATL.

Anti-Bacterial Agents↗
PubMed1998

Correlation between preoperative mouth opening and surgical outcome after arthroscopic lysis and lavage in patients with disc displacement without reduction.

PURPOSE: This study was designed to evaluate the efficacy of arthroscopic lysis and lavage for patients with limited mouth opening. The relationship between preoperative mouth opening and the surgical outcome was determined. METHOD: Fourteen patients with 16 internally deranged joints were treated by arthroscopic lysis and lavage. All had received 10.4 (7 to 19) months of nonsurgical treatment before arthroscopy. The preoperative magnetic resonance images showed anterior disc displacement without reduction in all treated joints. RESULTS: Twelve of the 14 patients (86%) showed good reduction in pain and improved range of jaw movement on average follow-up of 28.5 (13 to 66) months. Two patients showed no improvement after arthroscopy and required open surgical procedures. The preoperative mouth opening of the successful group averaged 29.4 (22 to 35) mm, whereas the two failed cases had 10- and 19-mm openings, respectively (P < .05). CONCLUSION: Persistent limitation of mouth opening of more than 22 mm after nonsurgical treatment has a good prognosis when treated by arthroscopic lysis and lavage. However, those with greater limitation should probably have earlier surgical intervention.

Adult↗
PubMed1998

Observer agreement in the detection of proximal caries with direct digital intraoral radiography.

OBJECTIVE: The aim of this study was to compare several values for consistency obtained by charged-coupled-device-based direct digital intraoral radiography with those obtained by conventional film-based radiography to evaluate observer agreement in determining the depth of proximal caries. STUDY DESIGN: A total of 93 proximal surfaces on radiologic images that were obtained by both the conventional film-based bite-wing technique and by direct digital intraoral radiography were evaluated by six observers. One of these observers also evaluated the same images six months after the initial evaluation. The kappa value, consistency ratio, agreement ratio, and Kendall's correlation coefficient were calculated for interobserver and intraobserver agreement. RESULTS: The overall kappa values for interobserver agreement were 0.439 and 0.424 in the direct digital system and the film-based radiography, respectively. The depth-related change of the values showed similar patterns in the two modalities for both interobserver and intraobserver agreement. CONCLUSION: The digital intraoral system resulted in no deterioration in observer agreement, and it presents no problems for clinical use with respect to the reliability of diagnosis.

Dental Caries↗
PubMed1998

Separation of the two reactions, oxidation and isomerization, catalyzed by Streptomyces cholesterol oxidase.

Site-directed mutagenesis was used to identify key amino acid residues of the cholesterol oxidase from Streptomyces sp., which catalyzes the oxidation of cholesterol and the isomerization of 5-cholesten-3-one. Eight mutant enzymes were constructed and the following amino acid substitutions were identified: N318A, N318H, E356A, E356D, H441A, H441N, N480A and N480Q. Mutants N318A and N318H retained both oxidation and isomerization activities. The mutant E356D retained oxidation but not isomerization activity. On the other hand, mutants N480A and N480Q showed no oxidation activity but retained their isomerization activities. The two catalytic reactions, oxidation and isomerization, in cholesterol oxidase were thus successfully separated. When the H441A or H441N mutation was introduced, both the oxidase and isomerase activities were completely lost. The H441, E356 and N480 residues thus appear to participate in the catalysis of cholesterol oxidase, whereas N318 does not. An analysis of the products of these mutant enzymes suggested that the previously proposed 6-hydroxylation reaction by cholesterol oxidase is actually autooxidation from 5-cholesten-3-one. Kinetic studies of the purified wild-type and mutant enzymes showed that the k(cat)/Km values for oxidation in E356D and for isomerization in N480A increased six- and threefold, respectively, over those in the wild-type. These mutational effects and the reaction mechanisms are discussed in terms of the three-dimensional structure of the enzyme constructed on the basis of homology modeling.

Amino Acids↗
PubMed1998

Primary uterine T-cell lymphoma.

A uterine CD8-positive, HTLV-1-negative T-cell lymphoma associated with atypical endometrial hyperplasia was found in a 63-year-old Japanese woman. Primary T-cell lymphoma of the uterus has not been previously reported.

Blotting, Southern↗
PubMed1998

Natural course of untreated symptomatic temporomandibular joint disc displacement without reduction.

In some patients with disc displacement without reduction, the symptoms of pain and decreased range of motion have been observed to resolve spontaneously over time without treatment. The natural history of this condition, however, is not well-understood. Thus, to study the natural course of disc displacement without reduction, we followed 40 patients without treatment for a period of 2.5 years. The diagnosis was established by history and physical examination and confirmed with magnetic resonance (MR) imaging. After 2.5 years, 43% of the patients were asymptomatic, 33% had decreased symptoms, and 25% of the patients showed no improvement or had required treatment. MR evidence of osteoarthritis and advanced stages of internal derangement at the initial evaluation was associated with a poor prognosis. The result of this prospective cohort study indicated that approximately 40% of patients with symptomatic disc displacement without reduction will be free of symptoms within 2.5 years, one-third will improve, whereas one-quarter will continue to be symptomatic. This knowledge should be valuable for the treatment planning and evaluation of prognosis of patients with non-reducing symptomatic disc displacement.

Adolescent↗