PubMed Health⌕ Search

Biomedical subjects

Yoshiaki Yamada

Publications and source records attributed to Yoshiaki Yamada.

At least 37 records · Page 2Linked to original sources
PubMed2005

Does off-pump coronary artery bypass grafting beneficially affect renal function?

BACKGROUND: Off-pump coronary artery bypass grafting (CABG) has been reported to beneficially affect renal function, but this remains to be confirmed. The purpose of the present paper was to study the effects of off-pump CABG on renal function and analyse predictors of postoperative renal impairment in patients who received off-pump CABG. METHODS: A total of 451 patients who underwent isolated CABG between January 1999 and August 2003 were retrospectively studied. No patient was receiving dialysis. A total of 300 patients (228 men) underwent off-pump CABG (off-pump group) and 151 patients (104 men) underwent on-pump CABG (on-pump group). Perioperative serum creatinine levels and creatinine ratios (peak postoperative creatinine level/preoperative creatinine level) were compared between the groups. RESULTS: Renal impairment (serum creatinine >1.5 mg/dL) developed postoperatively in 12.7% of the off-pump group and 18.5% of the on-pump group (P = 0.1). The creatinine ratio was significantly lower in the off-pump group (1.2 +/- 0.4) than in the on-pump group (1.4 +/- 0.7, P = 0.003). Logistic regression analysis demonstrated that the strongest predictors of postoperative renal impairment in off-pump CABG were left ventricular dysfunction (odds ratio 10.8) and multivessel grafting (odds ratio 4.3). CONCLUSIONS: Off-pump CABG provides better renal protection than on-pump CABG. However, perioperative renal function should be closely monitored in patients who have left ventricular dysfunction or who undergo multivessel grafting, even when off-pump CABG is performed.

Aged↗
PubMed2004

Extrinsic tongue and suprahyoid muscle activities during mastication in freely feeding rabbits.

To evaluate the coordination of tongue and suprahyoid muscle activities during natural mastication, electromyograms (EMGs) of jaw-closer, jaw-opener, suprahyoid (mylohyoid, MH), tongue-retractor (styloglossus, SG) and tongue-protractor (genioglossus, GG) muscles were recorded as well as the jaw-movement trajectories in vertical and horizontal axes in awake rabbits. Each masticatory cycle had three components including the fast-closing (FC), slow-closing (SC) and opening (Op) phases. The duration of the SC phase was much longer during pellet chewing while the durations of the FC and Op phases were much shorter during pellet chewing than bread or banana chewing. The jaw movements during banana chewing had a small amplitude of lateral excursion and a large amplitude of gape as compared with those during pellet and bread chewing. The MH muscle exhibited double-peaked EMG bursts during the Op phase. The MH bursts in the late part of the Op phase were dominant on the non-chewing side during pellet and bread chewing. The SG muscle also exhibited double-peaked EMG bursts. During pellet and bread chewing, the SG bursts during the SC phase were significantly larger on the chewing side than the non-chewing side. These bursts were also dominant during pellet chewing as compared with banana chewing. There was little difference in the GG bursts between the chewing and non-chewing sides or among the foods. Our results suggest that patterns of the MH and SG muscle activity are affected by the peripheral inputs and/or chewing patterns while those of the GG muscle activity was less modulated regardless of the consistency of foods.

Animal Feed↗
PubMed2004

Effects of food consistency on the pattern of extrinsic tongue muscle activities during mastication in freely moving rabbits.

The effects of physical characteristics of foods on the coordination of extrinsic tongue muscle activities during natural mastication were evaluated. Electromyograms of tongue-retractor (styloglossus, SG) and tongue-protractor (genioglossus, GG) muscles as well as the jaw-movement trajectories were recorded during raw rice and chow pellet chewing in the freely moving rabbit. Each masticatory cycle included a jaw closing (Cl) phase consisting of a fast-closing (FC) and a slow-closing (SC) phase, and a jaw opening (Op) phase. The duration of the Cl and SC phases was found to be much larger while the duration of the FC phase was much smaller during rice chewing than pellet chewing. The jaw movements during rice chewing had smaller amplitudes of the gape and lateral excursion of the jaw as compared with those during pellet chewing. The SG muscle had a double-peaked burst activity in each masticatory cycle with one peak during the Op phase (the SG1 burst) and the other during the Cl phase (the SG2 burst). They were significantly larger during pellet chewing as compared with rice chewing, but the duration of the SG2 burst was significantly longer during rice chewing than pellet chewing. The offset of the SG2 burst was delayed during rice chewing as compared with that during pellet chewing. There was little difference in the activity pattern of the GG burst between the foods. Our present results suggest that the SG muscle activity could be modified by the sensory feedback possibly to adapt to environmental demands during chewing.

Animals↗
PubMed2004

Coordination of jaw and extrinsic tongue muscle activity during rhythmic jaw movements in anesthetized rabbits.

To clarify the jaw-closer and tongue-retractor muscle activity patterns during mastication, electromyographic activity of the styloglossus (SG) as a tongue-retractor and masseter (Mass) as a jaw-closer muscles as well as jaw-movement trajectories were recorded during cortically evoked rhythmic jaw movements (CRJMs) in anesthetized rabbits. The SG and Mass muscles were mainly active during the jaw-closing (Cl) phase. The SG activity was composed of two bursts in one masticatory cycle; one had its peak during the jaw-opening (Op) phase (SG1 burst) and the other during the Cl phase (SG2 burst). The Mass activity during the Cl phase was dominant on the working side (opposite to the stimulating side) while the SG1 and SG2 bursts were not different between the sides. When the wooden stick was inserted between the molar teeth on the working side during CRJMs, the facilitatory effects on the SG1 and SG2 bursts on both sides were noted as well as those on the Mass bursts, but the effects on the SG1 burst seemed to be weak as compared with those on the Mass and SG2 bursts. The difference in the burst timing between the sides was noted only in the SG1 burst. When the trigeminal nerves were blocked, the peak and area of the SG and Mass burst decreased during CRJMs, and the facilitatory effects of the wooden stick application on the muscles were not noted. The results suggest that the jaw and tongue muscle activities may be adjusted to chew the food and make the food bolus.

Anesthesia↗
PubMed2004

The involvement of brain-derived neurotrophic factor in the pattern generator of mastication.

Brain-derived neurotrophic factor (BDNF) is a family of neurotrophins that plays crucial roles in neural development, survival, maintenance and regeneration both in central and peripheral nervous systems. To examine the effects of BDNF on mastication, jaw movement trajectories and masticatory muscle activities were electrophysiologically investigated in BDNF-deficient mice, compared with those of littermate wild-type mice. BDNF-deficient mice showed less number of chewing strokes and more irregular chewing pattern during mastication than wild-type mice. Masseter muscle activities of BDNF-deficient mice exhibited smaller values than those of wild-type mice. No significant difference in the cycle duration existed between these two types of the mice. These results indicate that the burst pattern is more susceptible to peripheral sensory inputs than the timing and suggest the involvement of BDNF in the control of jaw movement.

Animals↗
PubMed2004

Activity of peri-oral facial muscles and its coordination with jaw muscles during ingestive behavior in awake rabbits.

To study peri-oral facial muscle activity patterns and coordination with jaw muscles during ingestive behavior, electromyographic (EMG) activities in the peri-oral facial (buccinator: BUC, orbicularis oris: ORB) and jaw (masseter, digastric) muscles along with jaw movement trajectories were recorded in awake rabbits. A standardized amount of apple in a cylindrical shape was used as the test food. The period from food intake to just before swallowing (the masticatory sequence) was divided into three masticatory periods (preparatory period, rhythmic chewing period and preswallow period) based on the activity pattern of jaw muscles and jaw movement trajectories, and jaw movements and EMG activities in both the jaw and facial muscles during each masticatory period were assessed. Both the jaw and facial muscles were active throughout the masticatory sequence, and the activity patterns of facial muscles and the pattern of coordination between the facial and jaw muscles varied for each masticatory period. No consistent pattern was noted for the BUC activity during the preparatory period, whereas the ORB showed tonic activity throughout this period. During the rhythmic chewing and preswallow periods, both the ORB and BUC showed jaw-movement-related rhythmic bursts. However, significant differences were noted in the burst properties in both facial muscles and their temporal correlations with the jaw muscle activities between these two periods. Results suggest that the neural mechanisms regulating facial muscle activities may differ between the masticatory periods, and such mechanisms may contribute to the well-coordinated orofacial movements required for smooth masticatory sequence.

Analysis of Variance↗
PubMed2004

Cortical regulation during the early stage of initiation of voluntary swallowing in humans.

The aim of the present study was to reveal the spatiotemporal relations among cortical regions involved in the initiation of voluntary swallowing in humans using magnetoencephalography (MEG). As a control task, finger extension movement, which is purely voluntary, was also investigated using the same techniques. The swallowing-related activity was distributed widely for 2000 ms before the electromyogram onset of the right suprahyoid muscle; however, the finger-related activity occurred in the late stage of the recording. The cingulate cortex, the insula, and the inferior frontal gyrus were the main loci active prior to swallowing. These cortical loci coincide with those suggested by previous human brain mapping studies that investigated the brain mechanism which controls swallowing. Activation in the cingulate cortex was registered in the early stage of swallowing and could be related to the cognitive process regarding the food being safe to swallow. The activation in the insula lasted for a long time before the initiation of swallowing. This suggests that the long-lasting activation in the insula prior to swallowing is essential for the initiation of swallowing.

Adult↗
PubMed2004

Effects of sounds generated by a dental turbine and a stream on regional cerebral blood flow and cardiovascular responses.

Effects of sound generated by a dental turbine and a small stream (murmur) and the effects of no sound (null, control) on heart rate, systolic and diastolic blood pressure, and hemodynamic changes (oxygenated, deoxygenated, and total hemoglobin concentrations) in the frontal cortex were measured in 18 young volunteers. Questionnaires completed by the volunteers were also evaluated. Near-infrared spectroscopy and the Finapres technique were employed to measure hemodynamic and vascular responses, respectively. The subjects assessed the murmur, null, and turbine sounds as "pleasant," "natural," and "unpleasant," respectively. Blood pressures changed in response to the murmur, null, and turbine sound stimuli as expected: lower than the control level, unchanged, and higher than the control level, respectively. Mean blood pressure values tended to increase gradually over the recording time even during the null sound stimulation, possibly because of the recording environment. Oxygenated hemoglobin concentrations decreased drastically in response to the dental turbine sound, while deoxygenated hemoglobin concentrations remained unchanged and thus total hemoglobin concentrations decreased (due to the decreased oxygenated hemoglobin concentrations). Hemodynamic responses to the murmuring sound and the null sound were slight or unchanged, respectively. Surprisingly, heart rate measurements remained fairly stable in response to the stimulatory noises. In conclusion, we demonstrate here that sound generated by a dental turbine may affect cerebral blood flow and metabolism as well as autonomic responses.

Acoustic Stimulation↗
PubMed2004

Partial translocation for repair of left ventricular rupture after mitral valve replacement.

A new partial translocation technique to repair left ventricular rupture after mitral valve replacement and reimplant a mitral prosthesis is described. We repaired a tear from the interior by using mattress stitches buttressed with strips of Dacron felt, constructed a new annulus with a crescent-shaped piece of bovine pericardium on the left atrial wall above the repaired mitral annulus, and implanted a new prosthesis by using the newly constructed mitral annulus. We consider avoidance of mechanical stress by the prosthesis on the repaired site crucial to a successful outcome, and this new method is useful.

Aged↗
PubMed2003

Effect of cortical masticatory area stimulation on swallowing in anesthetized rabbits.

The effects of stimulation of the cortical masticatory area (CMA) on swallowing evoked by superior laryngeal nerve (SLN) were studied in anesthetized rabbits. Electromyographic activity of the thyrohyoid, masseter, and digastric muscles and jaw-movement trajectories were recorded to monitor rhythmic jaw movements (RJMs) or swallowing. A systematic series of microelectrode penetrations within the CMA was made for each animal, and the effects of CMA stimulation on swallowing were tested by comparing the number of swallows evoked by stimulation of the CMA alone, the SLN alone, and simultaneous stimulation of the SLN and CMA. A significant facilitatory effect was observed in 49 (52%) of the 95 CMA loci tested. No significant effect was noted in the remaining 46 loci. Three different types of RJMs were evoked by CMA stimulation, and topographical organization was noted among CMA loci that evoked different types of RJMs. A high percentage of (77%) the CMA loci that evoked RJMs with a prominent horizontal excursion of the jaw facilitated swallowing and was located in the posterolateral and deep part of the CMA. A majority (88%) of the CMA loci that evoked RJMs with small circular jaw movements did not affect swallowing and was located in the anteromedial and shallow part of the CMA. The facilitatory effect of CMA stimulation on swallowing remained even after removal of peripheral sensory inputs by means of deafferentation of infraorbital and inferior alveolar nerves. Results suggest the existence of facilitatory descending pathways to the swallowing center from particular intracortical loci of CMA.

Anesthetics, Inhalation↗
PubMed2003

Role of the pharyngeal branch of the vagus nerve in laryngeal elevation and UES pressure during swallowing in rabbits.

Elevation of the larynx during swallowing plays an important role in protecting the laryngeal inlet and in the opening of the upper esophageal sphincter (UES). The thyrohyoid (TH) muscle is the most important muscle for laryngeal elevation, and it is thought to be innervated by the thyrohyoid branch. However, in preliminary studies we found that laryngeal elevation was severely disturbed after sectioning of the pharyngeal branch of the vagus nerve (X-ph). In the present study, we examined the role of the X-ph in laryngeal elevation and the contribution of this nerve to UES pressure. Ten male rabbits under anesthesia were used. Sectioning of the X-ph not only abolished the electromyographic activities of the TH and cricopharyngeus (CP) muscles, it also greatly reduced the maximal value of laryngeal elevation during swallowing. On the other hand, sectioning of the hypoglossal nerve, which contains the thyrohyoid branch, produced no appreciable change in the electromyographic activity of either muscle and it reduced the maximal value of the elevation only slightly. These results indicate that the X-ph innervates the TH and CP muscles and suggest that the X-ph plays an important role in elevating the larynx and in regulating the UES pressure in rabbits.

Animals↗
PubMed2003

Further investigation of the epitope recognized by the new monoclonal antibody 2C9.

OBJECTIVE: We established a new monoclonal antibody (2C9) that reacted with prostate tissue. The immunohistochemical reactivity of this antibody is similar to anti-prostate-specific membrane antigen (PSMA). Herein, we report the antigenic determinant of 2C9 antibody. METHODS: The reactivity of the antibody was characterized by immunohistochemical staining and the antigen target was characterized by amino acid sequencing after immuno-affinity purification from an LNCaP cell lysate and cloning of a cDNA using a mammalian expression cDNA cloning system. RESULTS: The amino acid and nucleotide sequences for the antigen molecule recognized with 2C9 monoclonal antibody demonstrated identity with PSMA. CONCLUSION: The target molecule of the 2C9 monoclonal antibody is PSMA, pointing to future diagnostic and therapeutic applications.

Amino Acid Sequence↗
PubMed2003

Relationship between facial asymmetry and masseter reflex activity.

PURPOSE: In this study, we evaluated the tonic vibration reflex (TVR) of the masseter muscles in patients with facial asymmetry. SUBJECTS AND METHODS: The study was conducted with 10 volunteers without facial asymmetry and 12 orthognathic patients with facial asymmetry. Subjects were seated in a chair and held a stimulator composed of an electric motor and an acrylic bite block between the upper and lower dentitions at facial midline, to elicit TVR. Electromyographic activity was recorded using a pair of silver electrodes affixed bilaterally with adhesive tape to the skin over the superficial masseter. The amount of mandibular deviation was measured on the frontal cephalogram. The reflex response was evaluated with the following: TVR index (%) = integral TVR x 100/ integral maximum voluntary contraction (MVC), and with the TVR ratio: integral TVR on the high MVC side/ integral TVR on the low MVC side. RESULTS: In the patient group, the average TVR index on the deviated side was significantly higher than that on the nondeviated side. In all subjects, including the control and patient groups, a negative correlation between the amount of mandibular deviation and the side-to-side difference in TVR index was seen (r = -0.536, P <.05, n = 22). In addition, patients with a lower MVC on the deviated side than on the nondeviated side showed a significantly higher TVR ratio than did the control group. CONCLUSIONS: These results suggest that the difference between the right and left reflex responses elicited by TVR might be related to frontal craniofacial morphology.

Adult↗
PubMed2003

Magnetoencephalographic study of the starting point of voluntary swallowing.

Clear findings relative to where in the brain the starting point of voluntary swallowing is controlled were obtained in the present magnetoencephalographic study. Namely, the cerebral activity was observed in the cingulate gyrus and supplementary motor area for about 80 ms between 1,000 and 1,500 ms before swallowing in all test subjects. Thus, it is clear that this type of central control mechanism also plays an important role in complicated swallowing movements.

Adult↗
PubMed2003

Vesicourethral anastomotic suture placement during radical prostatectomy using Maniceps.

INTRODUCTION: A new method of using a semiautomatic device (Maniceps) for precise vesicourethral anastomosis during radical retropubic prostatectomy is described. METHODS: A total of 15 patients underwent radical retropubic prostatectomy with this technique. The follow-up period ranged from 6 to 16 months. The retrograde urethrocystography was performed at 2 weeks. Patients were evaluated specifically for anastomotic time, anastomotic obstruction and urinary continence. RESULTS: The average anastomotic time was 8.1 (range 5-12) min. The catheter of all patients could be removed at 2 weeks. Anastomotic obstruction occurred in 1 patient (6.7%), and 14 patients (93.3%) were completely continent of urine. CONCLUSION: Maniceps is a useful procedure to carry out vesicourethral anastomosis safely, easily and surely, and it has provided good surgical results in our experience.

Aged↗
PubMed2003

Impact of myocardial angiotensin-converting enzyme activity on coronary vascular resistance and serum brain natriuretic peptide concentration in coronary bypass surgery.

Angiotensin-converting enzyme (ACE) inhibitors have cardioprotective effects in animals, but whether that occurs in humans is still controversial. The effect of myocardial ACE activity on coronary vascular resistance during coronary artery bypass surgery and on serum brain natriuretic peptide (BNP) concentration after surgery was studied in myocardial tissue sampled from the right atrium of patients during cardiac surgery (n=20). Tissue enzyme activity (nmol/min per mg protein) was measured using a photometric technique, and the flow rate and pressure upon antegrade infusion of a crystalloid cardioplegic solution was measured for calculating the coronary vascular resistance (mmHg. ml(-1). min(-1)). Serum BNP concentration (pg/ml) was measured on days 0 and 5 after the surgery. Linear regression between tissue ACE activity and coronary vascular resistance (y = 0.46x + 0.56, r=0.85) as well as serum BNP concentration on days 0 (y = 129x + 30, r=0.59) and 5 (y = 347x + 180, r=0.73) after the surgery was significant (x: ACE activity; y: coronary vascular resistance/serum BNP concentration). The results indicate that inhibition of myocardial ACE activity might improve coronary circulation during surgery and hence, cardiac function after surgery.

Aged↗
PubMed2002

Convergence of selected inputs from sensory afferents to trigeminal premotor neurons with possible projections to masseter motoneurons in the rabbit.

Peripheral input convergence on trigeminal premotor neurons in the vicinity of trigeminal motor nucleus has been investigated. Thirty neurons were identified by their antidromic responses to microstimulation of the masseteric subnucleus of trigeminal motor nucleus (NVmot-mass). Peripheral receptive fields were found in the buccal mucosae, periodontal ligaments, palate, tongue and vibrissae for 16 neurons located in the intertrigeminal area (NVint), supratrigeminal area (NVs), main sensory trigeminal nucleus (NVsnpr) and subnucleus gamma of the oral nucleus of the spinal trigeminal tract (NVspo-gamma). Eleven neurons in the NVint, NVs and NVspo-gamma responded to passive jaw opening: nine neurons were activated and two were inhibited. None of the neurons responded to both the orofacial mechanical stimulation and passive jaw opening. Forty-six percent of neurons (13 out of 28 tested) received inputs from the inferior alveolar nerve (IAN) and 53% of neurons (8 out of 15 tested) received inputs from the infraorbital nerve (ION). Out of 15 neurons tested for inputs from the IAN and ION, 7 neurons in the NVsnpr and NVspo-gamma received input from both. Sixteen percent of neurons (4 out of 25) received inputs from the masseteric nerve (MassN). None of the neurons with inputs from IAN and/or ION also received inputs from the MassN. We suggest that trigeminal premotor interneurons with projections to the NVmot-mass fall into two broad categories, those with inputs from the IAN and/or ION and those with inputs from the MassN, possibly muscle spindle afferents, and no neuron receiving inputs from both.

Afferent Pathways↗