Biomedical subjects

H Iida

Publications and source records attributed to H Iida.

At least 145 records · Page 8Linked to original sources

PubMed1998

Importance of left anterior descending coronary artery curvature in determining cross-sectional plaque distribution assessed by intravascular ultrasound.

We assessed the relation between the circumferential distribution of coronary atherosclerotic plaques and the structure of the epicardial coronary arteries in patients with coronary artery disease using intravascular ultrasound in vivo. Coronary atherosclerosis preferentially formed at the inner arc of the curved coronary vessels, and greater vessel curvatures were associated with greater distributions of atherosclerotic lesions along the inner coronary artery wall.

Adult↗

PubMed1998

Distal radius fractures: mechanisms of injury and strength prediction by bone mineral assessment.

The strength of the radius depends on the mechanical properties of cancellous and cortical bone. By assessing both compartments quantitatively with bone densitometry, we tried to identify the specificity of each in predicting the load at which the distal radius will fracture. Twenty human cadaver forearms were scanned for bone mineral and geometric properties with quantitative computed tomography and dual x-ray absorptiometry. In both a neutral loading situation and one in which the wrist was extended 45 degrees, the load distribution was determined with pressure-sensitive films, and a fracture simulating a fall on the hand was produced with a material testing machine. Fractures that occur with the wrist in extension were produced by a central impact of the scaphoid onto the radiocarpal joint, and those that occur under neutral loading conditions were produced by a more commonly distributed loading pattern. The load at fracture was most specifically predicted (r2=0.74) by bone mineral and geometric measures of the cortex at the shaft of the radius. Bone mineral density measures of trabecular (r2=0.64) and total (r2=0.66) bone were less successful in predicting the fracture load. After adjustment for bone size, the geometric and density measures revealed similar specificity. Cortical bone, therefore, contributes significantly to the strength of the distal radius and may play an important role in the prediction of osteoporotic wrist fractures.

Absorptiometry, Photon↗

PubMed1998

Clonidine premedication modifies responses to adrenoceptor agonists and baroreflex sensitivity.

PURPOSE: To evaluate the effects of clonidine on responses to adrenoceptor agonists and baroreflex sensitivity, we examined arterial blood pressure (AP) responses to phenylephrine and heart rate (HR) responses to isoproterenol and baroreflex sensitivity (HR response to AP changes due to phenylephrine or nitroglycerin). METHODS: We studied 60 anaesthetized patients who either did or did not receive 5 micrograms.kg-1 clonidine po before they were anaesthetized. After induction of general anaesthesia, the patients received 3 micrograms.kg-1 phenylephrine, 0.02 microgram.kg-1 isoproterenol, or 2-3 micrograms.kg-1 nitroglycerin, and haemodynamic measurements were taken. Baroreflex sensitivity was expressed as the slope of the linear regression line (msec.mmHg-1; in msec of R-R interval change vs mmHg change in systolic arterial pressure) following the administration of phenylephrine and nitroglycerin. RESULTS: Patients who received clonidine had greater augmented responses in AP to phenylephrine and in HR to isoproterenol (47.2 +/- 15.6% vs 23.7 +/- 11.9% for increase in systolic AP and 59.8 +/- 22.6% vs 26.2 +/- 11.0% for increase in HR, P < 0.05 respectively). There were no differences between the baroreflex sensitivities in the pressor (phenylephrine) test groups (3.77 +/- 1.08 vs 4.41 +/- 1.66 msec.mmHg-1). In contrast, the slopes of depressor (nitroglycerin) test groups were decreased in patients receiving clonidine (1.98 +/- 0.73 vs 3.68 +/- 1.72 msec.mmHg-1, P < 0.05). CONCLUSION: The results suggest that premedication with clonidine might enhance critical hypotension during anaesthesia and surgery, but restoration both of AP and HR decrease can be achieved effectively by phenylephrine and isoproterenol i.v., respectively.

Adrenergic alpha-Agonists↗

PubMed1998

[A case report of recurrent self inserted needle in heart].

A 17-year-old female who had, on two occasions, inserted a total of 7 needles into her heart and chest wall, resulting in autolesion on both occasions, was examined. On the first occasion, because the needle end was recognizably protruding from the right ventricle, we successfully removed the needle without using ECC. No complications arose prior to discharge, after which she regularly visited the psychiatric department for treatment. Two months after discharge, she again inserted needles into her chest wall and was admitted to hospital. At that time, five needles were evident in the chest wall. During preparation for removal of the needles under local anesthetic, she escaped from the room. When found in a ward several hours later, six needles were embedded in her chest wall, the sixth, most recently inserted needle was an injection needle. Due to the depth to which the needle had been inserted in the heart, neither the point nor end were visible, and thus the needle had to be removed using ECC and fluoroscopy.

Adolescent↗

PubMed1998

Interleukin-6 and "complex" cardiac myxoma.

A rare case of "complex" cardiac myxoma is reported. Complex cardiac myxoma manifests with more constitutional signs than the sporadic type. These constitutional signs are known to be associated with the overproduction of interleukin-6 by cardiac myxomas. In our study, immunohistochemical staining of the myxoma for interleukin-6 was strongly positive. The serum interleukin-6 level decreased after surgical removal of the tumor and has remained undetectable for the past 2 years.

Adolescent↗

PubMed1998

Development of bioactive bone cement and its clinical applications.

This paper is a summary of already published papers on the bioactive bone cement (BA cement) which consists of CaO-SiO2-P2O5-MgO-CaF2 (AW glass-ceramic) powder and bisphenol-a-glycidyl methacrylate (Bis-GMA) resin. Two types of BA cement, dough and injection type, were prepared by changing their chemical compositions slightly. They harden in a few minutes exhibiting much lower curing temperature than PMMA cement. They have significantly higher compressive, bending, and tensile strengths than PMMA cement and have a character of bonding directly with bone in 4-8 weeks in vivo. Intercalary prosthetic replacement of the femur and total prosthetic replacement of the hip were performed in dogs using either PMMA cement or BA cement. Mechanical tests demonstrated that fixation strengths of these prostheses with BA cement increased with time and were significantly greater than those with PMMA cement tested at any time. Results of histological examinations showed direct bonding between BA cement and bone, and that the bone trabeculae around BA cement mantle grew with time, while with PMMA cement an intervening soft tissue layer was always observed at the cement-bone interface. BA cement was used in a few aged patients to install a hip prosthesis either in cases of revision or femoral neck fracture. The longest follow-up period of the patient is 4 yrs. The patients have been doing well with no adverse effect of the cement to date.

Animals↗

PubMed1998

Early impairment of coronary flow reserve in young men with borderline hypertension.

OBJECTIVES: The purpose of this study was to investigate whether functional abnormalities in coronary vasomotion are present in young healthy asymptomatic men fulfilling the World Health Organization (WHO) criteria for borderline hypertension. BACKGROUND: Previous studies have reported reduced coronary flow reserve in middle-aged subjects with sustained hypertension and hypertension-induced microvascular heart disease or left ventricular hypertrophy. METHODS: Myocardial blood flow was measured at baseline and during dipyridamole-induced hyperemia by means of positron emission tomography and oxygen-15-labeled water in asymptomatic young men with borderline hypertension (group 1: n = 16, mean +/- SD age 37 +/- 4 years, 24-h ambulatory blood pressure 135 +/- 10/81 +/- 9 mm Hg) and matched healthy control subjects (group 2: n = 19, age 35 +/- 3 years, 24-h ambulatory blood pressure 119 +/- 8/69 +/- 8 mm Hg, p < 0.001). Left ventricular (LV) mass, dimensions and function were measured by echocardiography. RESULTS: LV mass, dimensions and diastolic function were similar in the study groups. Baseline myocardial blood flow was similar (0.83 +/- 0.21 vs. 0.80 +/- 0.22 ml/g per min, group 1 vs. group 2, respectively, p = NS), and a significant increase in flow was detected after dipyridamole infusion (0.56 mg/kg body weight in 4 min intravenously) in both groups. However, the flow response to dipyridamole was significantly lower in group 1, leading to lower hyperemic flow in group 1 than in group 2 (2.85 +/- 1.20 vs. 3.80 +/- 1.44 ml/g per min, respectively). Consequently, the coronary flow response was lower in hypertensive than in normotensive men (3.46 +/- 1.23 vs. 4.99 +/- 2.5 ml/g per min, group 1 vs. group 2, respectively, p < 0.05). CONCLUSIONS: These results demonstrate reduced coronary reactivity present in young asymptomatic men with borderline hypertension and no signs of hypertension-induced angina or left ventricular hypertrophy. Because baseline basal myocardial blood flow was unchanged, the reduction in coronary flow reserve depends on an impaired maximal vasodilator capacity.

Adult↗

PubMed1998

Marked increases of aminotransferase levels after cresol ingestion.

A 26-year-old woman developed marked increases in levels of aminotransferases about 24 hours after ingestion of 70 mL of 50% cresol. Responding to supportive measures, the patient recovered without any significant complications. Cresol and/or its metabolite may have caused transient hepato-cellular injury in this patient. In cresol poisoning, hepato-cellular injury can manifest even after a 24-hour asymptomatic period.

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

Surgical treatment for ossification of the posterior longitudinal ligament and the yellow ligament in the thoracic and cervico-thoracic spine.

This study analyzed the postoperative results of surgical treatment for thoracic and cervicothoracic myelopathy caused by ossification of the posterior longitudinal ligaments (OPLL) or ossification of the yellow ligaments (OYL) in 22 patients using magnetic resonance imaging (MRI), myelography and computed tomography (CT). Anterior procedures were performed in 11 patients for OPLL, while posterior approaches were adopted for the management of 11 patients for both OYL and OPLL combined with OYL lesions. Clinical symptoms were improved using both anterior and posterior techniques. MRI and myelo-CT studies, which show the direction of cord compression, the form and extent of the lesion, and the degree of thoracic kyphosis, are very useful when the surgical procedure for OPLL and OYL in the thoracic and cervico-thoracic spine is selected.

Adolescent↗

PubMed1998

Differential constitutive activation between STAT-related proteins and MAP kinase in primary acute myelogenous leukaemia.

Many cytokines and growth factors stimulate multiple signal transduction pathways essential for proliferation in human acute leukaemia cells, including a mitogen-activated protein (MAP) kinase pathway and a Janus kinase (JAK)-STAT (signal transducers and activators of transcription) pathway. We have previously shown constitutive activation of MAP kinase in approximately 50% of acute myelogenous leukaemia (AML) samples. Recently, STAT proteins have been reported to be constitutively activated in 10-20% of AML cases. STAT3 and STAT5 are the main STAT proteins activated in haemopoietic progenitors in response to cytokines such as IL-3, GM-CSF, erythropoietin and thrombopoietin. Although the possibility of STAT1 protein as a substrate for MAP kinase at a serine residue has been suggested, the cross-talk between STATs and MAP kinase pathways in vivo, especially in leukaemia cells, remains unknown. We examined the phosphorylation of STAT 3 and STAT 5 at the tyrosine residues in AML samples in which MAP kinase activity had already been found. 40/50 primary AML cases (80%) exhibited constitutive tyrosine phosphorylation of STAT5. Electrophoretic mobility shift assay showed DNA binding activity of STAT5 correlated with tyrosine phosphorylation of STAT5. Similarly, with respect to STAT3, 17/23 cases examined (74%) showed constitutive tyrosine phosphorylation of STAT3. In addition, we examined the tyrosyl-phosphorylation of STAT5 isoforms, STAT5A and STAT5B, in 20 AML cases, and found selective STAT5B phosphorylation in the absence of STAT5A phosphorylation in three cases. Furthermore, in certain AML cases, constitutive activation of MAP kinase and STAT proteins occurred independently. No significant correlation of MAP kinase activation was observed with either tyrosine phosphorylation of STAT3/STAT5 or positive DNA binding of STAT proteins. These results suggest that constitutive activation of STAT proteins occurs commonly and that the causes of constitutive activation of these two major cascades are heterogeneous in AML.

Acute Disease↗

PubMed1998

Accuracy of cortical and trabecular bone measurements with peripheral quantitative computed tomography (pQCT).

In order to assess the accuracy of peripheral QCT (Stratec XCT 960) we analysed scans of the European Forearm Phantom and another phantom consisting of K2HPO4 encased in aluminium tubes to simulate cortical walls. Additionally 14 cadaveric forearm specimen scans were compared to CT scans acquired on a GE9800Q. The accuracy for density assessment of the European Forearm Phantom was better than 3%. A small increase in density was observed with increasing thickness of the aluminium wall (10% for each mm). Density measurements within the wall were confounded by limited spatial resolution. For a thickness of less than 4 mm, the density within the wall was underestimated by up to 40%. The measurement of mineral content was not influenced by this effect and showed an accuracy error of less than 6%. The agreement of density measurements on the different CT systems was very strong (R2 > 0.96; RMSE < 6.2%). Our findings suggest that the Stratec pQCT scanner very accurately measures volumetric trabecular and total bone mineral densities at the distal radius while the assessment of cortical density is associated with considerable inaccuracies due to limited spatial resolution.

Aluminum↗

PubMed1998

The vascular effects of topical and intravenous alpha2-adrenoceptor agonist clonidine on canine pial microcirculation.

UNLABELLED: To assess the direct cerebrovascular effects of clonidine, we investigated the pharmacological responses of pial vessels to its topical and i.v. administration using a cranial window. Forty-six dogs anesthetized with pentobarbital had the cranial window implanted. We administered six different concentrations of clonidine (10(-8), 10(-7), 10(-6), 10(-5), 10(-4), 10(-3) mol/L) dissolved in artificial cerebrospinal fluid under the window and measured the pial arterial and venous diameters. After pretreating pial vessels with either yohimbine, an alpha2-adrenoceptor antagonist, or glibenclamide, an adenosine triphosphate-sensitive K+-channel blocker, their action was examined after applying clonidine. We also evaluated the effects of i.v. clonidine (5 microg/kg) on pial vascular tone. Topical clonidine produced significant constriction of the pial large and small arteries and veins in a concentration-dependent manner (P < 0.05). Yohimbine abolished the clonidine-induced pial arterial (large P < 0.005; small P < 0.0005) and venous constriction (large and small P < 0.0001). Glibenclamide potentiated the clonidine-induced pial arterial constriction (P < 0.05). I.v. clonidine did not cause significant changes in pial arteries, but it caused significant constriction of small veins. These were associated with a significant decrease in heart rate and an increase in serum potassium level and glucose concentration. In the present study, we demonstrate that the topical application of clonidine constricts both pial arterial and venous vessels in a concentration-dependent manner and suggest that mechanisms of such action are caused by the activation of alpha2-adrenoceptors and adenosine triphosphate-sensitive K+-channels, whereas i.v. clonidine constricts only pial small veins. IMPLICATIONS: In this study, we describe the direct and i.v. effects of clonidine on pial vessels using a cranial window in anesthetized dogs. The topical application of clonidine constricts pial vessels. This is mediated by the activation of alpha2-adrenoceptors and adenosine triphosphate-sensitive K+-channels. I.v. clonidine constricts only pial small veins.

Adjuvants, Anesthesia↗

PubMed1998

The optimal test dose of epinephrine for epidural injection with lidocaine solution in awake patients premedicated with oral clonidine.

UNLABELLED: We attempted to determine the optimal test dose of epinephrine for use with epidural anesthesia in awake patients premedicated with clonidine. Eighty-eight adult patients were randomized into two groups [oral premedication with clonidine 5 microg/kg (CLON) or no premedication (CONT)]. Before induction of general anesthesia, heart rate (HR) and blood pressure (BP) were measured for 3 min after the i.v. injection of 3 mL of 1.5% lidocaine containing epinephrine (0, 1.25, 2.5, 5, 7.5, or 15 microg) in a randomized, double-blind manner. We calculated 95% confidence intervals for the peak HR and BP increases induced by each dose of epinephrine. At 7.5 microg, epinephrine induced a significantly greater increase in HR and BP in CLON than in CONT. The 95% confidence interval for the HR change induced by 7.5 microg of epinephrine in CLON was nearly the same as the accepted standard dose of epinephrine (15 microg) in CONT. We conclude that premedication with clonidine enhances HR and BP responses to the i.v. administration of epinephrine-containing epidural test solutions. Consequently, 7.5 microg of epinephrine may be sufficient to enable detection of accidental injection into a blood vessel in awake patients premedicated with clonidine 5 microg/kg. IMPLICATIONS: Clonidine, a commonly used preanesthetic medication, alters patients' cardiovascular responses to drugs such as epinephrine. Our randomized, double-blind study suggests that, in awake patients receiving oral clonidine premedication, 7.5 microg of epinephrine (half the usual dose) is adequate as an indicator of accidental injection into the epidural vessels during epidural anesthesia.

Adult↗

PubMed1998

Isoflurane and sevoflurane induce vasodilation of cerebral vessels via ATP-sensitive K+ channel activation.

BACKGROUND: Activation of adenosine triphosphate-sensitive K+ channels causes cerebral vasodilation. To assess their contribution to volatile anesthetic-induced cerebral vasodilation, the effects of glibenclamide, an adenosine triphosphate-sensitive K+ channel blocker, on the cerebral vasodilation induced by isoflurane and sevoflurane were studied. METHODS: Pentobarbital-anesthetized dogs (n = 24) assigned to one of two groups were prepared for measurement of pial vessel diameter using a cranial window preparation. Each dog received three minimum alveolar concentrations (MAC; 0.5, 1, and 1.5 MAC) of either isoflurane or sevoflurane, and the pial arteriolar diameters were measured in the presence or absence of glibenclamide (10(-5) M) infused continuously into the window. Mean arterial pressure was maintained with phenylephrine. Furthermore, to assess the direct effect of isoflurane and sevoflurane on cerebral vessels, artificial cerebrospinal fluid was administered topically by being bubbled with isoflurane or sevoflurane. The blocking effect of glibenclamide on the vasoactive effects of these anesthetics also were evaluated. RESULTS: Isoflurane and sevoflurane both significantly dilated large (> or = 100 microm) and small (< 100 microm) pial arterioles in a concentration-dependent manner (6% and 10%, 3% and 8% for 0.5 MAC; 10% and 19%, 7% and 14% for 1 MAC; 17% and 28%, 13% and 25% for 1.5 MAC). Glibenclamide attenuated the arteriolar dilation induced by these anesthetics (not significant in isoflurane). Topical application of isoflurane or sevoflurane dilated large and small arterioles both in a concentration-dependent manner. Such vasodilation was inhibited completely by glibenclamide. CONCLUSION: The vasodilation of cerebral pial vessels induced by isoflurane and sevoflurane appears to be mediated, at least in part, via activation of adenosine triphosphate-sensitive K+ channels.

Adenosine Triphosphate↗

PubMed1998

Insulin resistance in essential hypertension is characterized by impaired insulin stimulation of blood flow in skeletal muscle.

OBJECTIVE: To determine whether insulin-stimulated blood flow in patients with mild essential hypertension is altered. SUBJECTS: Eleven untreated mildly hypertensive patients [aged 35 +/- 2 years, body mass index 25.1 +/- 0.4 kg/m2, mean arterial pressure 110 +/- 2 mmHg (means +/- SEM) and 10 matched normotensive subjects (mean arterial pressure 94 +/- 3 mmHg). METHODS: Blood flow was quantitated directly in skeletal muscle both basally and during supraphysiologic hyperinsulinemia (serum insulin approximately = 450 mU/l) using radiowater ([15O]H2O) and positron emission tomography. Whole-body and femoral muscle glucose uptakes were determined using the euglycemic insulin clamp technique, [18F]-2-fluoro-2-deoxy-D-glucose and positron emission tomography. RESULTS: Rates of whole-body and femoral muscle glucose uptake were significantly lower in the hypertensive than in the normotensive group. Insulin increased muscle blood flow by 91% in the normotensive group, but only by 33% in the hypertensive group. CONCLUSIONS: The ability of insulin to stimulate blood flow in patients with mild essential hypertension is impaired.

Adult↗

PubMed1998

Optimized acquisition time and image sampling for dynamic SPECT of Tl-201.

With the recent development in scatter and attenuation correction algorithms, dynamic single photon emission computerized tomography (SPECT) can potentially yield physiological parameters, with tracers exhibiting suitable kinetics such as thallium-201 (Tl-201). A systematic way is proposed to investigate the minimum data acquisition times and sampling requirements for estimating physiological parameters with quantitative dynamic SPECT. Two different sampling schemes were investigated with Monte Carlo simulations: 1) Continuous data collection for total study duration ranging from 30-240 min. 2) Continuous data collection for first 10-45 min followed by a delayed study at approximately 3 h. Tissue time activity curves with realistic noise were generated from a mean plasma time activity curve and rate constants (K1 - k4) derived from Tl-201 kinetic studies in 16 dogs. Full dynamic sampling schedules (DynSS) were compared to optimum sampling schedules (OSS). We found that OSS can reliably estimate the blood flow related K1 and Vd comparable to DynSS. A 30-min continuous collection was sufficient if only K1 was of interest. A split session schedule of a 30-min dynamic followed by a static study at 3 h allowed reliable estimation of both K1 and Vd avoiding the need for a prolonged (>60-min) continuous dynamic acquisition. The methodology developed should also be applicable to optimizing sampling schedules for other SPECT tracers.

Animals↗

PubMed1998

Ingrown nails: a comparison of the nail matrix phenolization method with the elevation of the nail bed-periosteal flap procedure.

Seventy-five procedures were performed on 62 patients with ingrown nails from 1992 to 1996. Those consisted of 51 nail matrix phenolization methods (NMP) and 24 elevation of the nail bed-periosteal flap procedures (ENF). Ingrown nails were classified into type A (normal nail plate) and type B (incurved nail plate). The duration and intensity of postoperative pain were assessed, and the recurrence rate was monitered. The recurrence rate was 3.9% in the NMP group and 4.1% in the ENF group. Concerning the recurrence rate, there was no statistical significance between ENF and NMP in both types. Postoperative pain intensity was less in the NMP group than in the ENF group in both types (P < 0.01). The same tendency was seen in postoperative pain duration. However, the NMP group had longer duration of wound healing compared with the ENF group in type A (P < 0.01). We conclude that NMP is a recommendable treatment for most ingrown nails.

Administration, Topical↗