Biomedical subjects

T Takishima

Publications and source records attributed to T Takishima.

At least 181 records · Page 10Linked to original sources

PubMed1991

Influence of reduced presynaptic myocardial norepinephrine stores on left ventricular contractility.

Many investigators have reported that myocardial norepinephrine content is decreased in congestive heart failure. However there have been no studies of how decrease in myocardial norepinephrine might influence myocardial contraction. To clarify whether decreased myocardial norepinephrine per se affects myocardial contraction, we observed the change in left ventricular contractility during 30 min of left stellate ganglion stimulation in control and acutely reserpinized dogs. We obtained left ventricular max dp/dt and left ventricular end-systolic pressure-segment length relationships as indicators of left ventricular contractility. Both parameters decreased after left stellate ganglion stimulation in reserpinized dogs (left ventricular max dp/dt: 2064 +/- 200 to 1608 +/- 168 mmHg/s, left ventricular end-systolic pressure-segment length slope 117 +/- 22 to 79 +/- 14 mmHg/mm, n = 8, P less than 0.05), while they did not change in controls. In reserpinized dogs, left ventricular norepinephrine content decreased to one-third that of controls before the stimulation, and further decreased after stimulation. These data indicate that lowered myocardial norepinephrine itself may be responsible for the negative effect on left ventricular contractility in congestive heart failure.

Animals↗

PubMed1991

Surfactant apoprotein-A concentration in sputum for diagnosis of pulmonary alveolar proteinosis.

Pulmonary alveolar proteinosis (PAP), a disease characterised by accumulation of surfactant in alveoli, is diagnosed on the basis of invasive biopsy procedures. We have measured apoprotein A (SP-A) concentrations in sputum to see if this is useful for the diagnosis of PAP. Sputum samples from three patients with PAP and twenty patients with other pulmonary disease were assayed using monoclonal antibodies to SP-A. SP-A concentrations were 400 times higher in patients with PAP than in the controls, suggestions that this measurement is useful for the diagnosis of PAP especially where lung biopsy is contraindicated.

Anti-Infective Agents↗

PubMed1991

[Developmental changes in normal images of 123I-IMP brain SPECT in young children].

In an attempt to determine the normal evolution of N-isopropyl p-I-123-iodoamphetamine (123I-IMP) single photon emission computed tomography (SPECT), we selected 12 children (an age range of 1 month-3 year) who were diagnosed as normal in follow-up between 6 month-3 year by neurological examination, X-ray computed tomography, electroencephalography and 123I-IMP SPECT in our 78 cases. SPECT of the brain was performed 30 minutes after intravenous administration of 74 MBq (2 mCi) 123I-IMP using a rotating gamma camera equipped with a 30-degree slant-hole collimator. In neonates, a predominant activity was observed in the basal ganglia and thalamus, with only slight parietal and occipital activity. Frontal cortex was barely recognizable. Under 1 year, cortical activity was gradually increased and clearly visible. After 1 year, SPECT images were similar to those of adult. In conclusion there was an important modification of the regional perfusion pattern in relation to brain maturation.

Amphetamines↗

PubMed1991

Effects of age on right ventricular hypertrophic response to pressure-overload in rats.

To examine the effects of age on hypertrophic response to pressure-overload in the right ventricle, we determined the rate and extent of hypertrophy in three age groups of Wistar rats: 2, 7 and 18 months. We created pulmonary artery constriction so that increases in right ventricular pressure were similar in those groups. One or 3 weeks after pulmonary artery constriction, the rats were sacrificed and hypertrophic response was estimated from right ventricular weight, myocyte width and protein content. In the 2-month-old rats, significant hypertrophy was observed 1 and 3 weeks after pulmonary artery constriction in terms of right ventricular weight/body weight (161% of controls at 1 week and 209% at 3 weeks), right ventricular weight/tibial length (161 and 251%, respectively) and right ventricular weight/left ventricular weight (174 and 211%, respectively). In the 7-month-old rats, significant hypertrophy was observed only at 3 weeks, but was not observed even at 3 weeks in the 18-month-old rats. The age-associated decrease and delay in hypertrophic response was also observed at cellular (myocyte width) and biochemical (protein content) levels. Thus, there is an age-associated diminution in the rate and extent of myocardial hypertrophy in the right ventricle.

Aging↗

PubMed1991

Effect of artificial surfactant on ciliary beat frequency in guinea pig trachea.

This study defines the effect of artificial surfactant on ciliary beat frequency. We employed guinea pig tracheal rings and a photomultiplier which allows in vitro measurement of ciliary beat frequency. The beat frequency without surfactant decreased continuously while surfactant caused a relative increase in beat frequency. The difference between the relative beat frequency in the presence and absence of surfactant was significant. The effect of surfactant was dose dependent. Fifteen minute treatments with 2 mM hydrogen peroxide reduced the beat frequency. The reduction partially recovered in the absence of surfactant. In contrast, surfactant markedly accelerated the recovery of the beat frequency. Surfactant did not influence the effect of terbutaline (a beta 2-adrenergic agonist) on beat frequency. These results indicate that artificial surfactant can, in some circumstances, promote ciliary beat frequency. This concept is important to the clearance mechanism of the airways, and its application to some pathophysiological states such as chronic bronchitis and bronchial asthma should be considered.

Animals↗

PubMed1991

Effects of focal cooling of the ventral medullary surface on breathing pattern and blood pressure in dogs.

We assessed the effect of focal graded cooling of the ventral medullary surface (VMS) on breathing pattern and blood pressure in 15 anesthetized, vagotomized and artificially ventilated dogs. Diaphragmatic electromyogram or phrenic neurogram, referred to as Ec, and blood pressure (BP) were obtained during localized (2 x 2 mm2) cooling of the VMS. Greatest depression of both Ec and BP was obtained by cooling in the areas located 4-9 mm caudal to the foramen cecum (Fc) and lateral to the pyramids. Mild cooling in these intermediate areas decreased both inspiratory duration (Ti) and the rate of rise of Ec (Ec/Ti), but respiratory rate was unchanged. Cooling of the rostral areas (0-3 mm from Fc) induced mild depression of Ec amplitude due to reduction in Ec/Ti without changing Ti, and prolonged expiratory duration (Te) significantly. Cooling of the caudal areas (12-18 mm from Fc) reduced Ec amplitude mildly due to reduction in Ti without affecting Ec/Ti, and shortened Te greatly. Cooling of the rostral areas produced mild fall in BP, but cooling of the caudal areas did not affect BP significantly. It is suggested that rostral and intermediate parts of the VMS participate in the shaping of inspiratory drive, whereas wide areas of the VMS including caudal part are involved in the determination of respiratory timing. It is also suggested that the rostral and intermediate parts, and not the caudal part, of the VMS are important in the regulation of vasomotor tone.

Animals↗

PubMed1991

Responses of upper airway muscles to gastrocnemius muscle contraction in dogs.

We studied electromyographic (EMG) responses of the alae nasi (AN) and the posterior cricoarytenoid (PCA) muscles, which act as upper airway dilators, during contraction of gastrocnemius muscle in six chest-intact anesthetized dogs with spontaneous breathing and in four thoracotomized, phrenicotomized and mechanically ventilated dogs with right thoracic and left cervical vagotomy. Muscle contraction was phasically induced by electrical stimulation of the intact gastrocnemius nerve or the distal cut end of this nerve for 20-30 sec. Stimulation intensity was determined as twice the motor threshold in each dog. In chest-intact animals, phasic contraction induced by intact nerve stimulation produced initial rapid increases in upper airway muscle activity, but stimulation of the distal cut end of the nerve did not show the rapid increase in upper airway muscle activity. Furthermore, stimulation of the proximal cut end did not produce any transient response with the stimulation intensity used in this study. In chest-open and vagotomized animals with artificial ventilation, responses of the upper airway muscles to contraction during the intact nerve stimulation were observed. These results suggest that the contraction of the gastrocnemius muscle activates upper airway dilating muscles via reflex mechanisms.

Afferent Pathways↗

PubMed1991

Tumor necrosis factor attenuates beta agonist-evoked Cl- secretion in canine tracheal epithelium.

We examined the effect of human recombinant TNF alpha on the potential difference (PD) and short circuit current (SCC) of canine tracheal epithelium using an Ussing chamber. Luminal or submucosal TNF (2 to 200 U/ml) produced no significant alterations in the basal PD or SCC values. Pretreatment with luminal TNF significantly reduced isoproterenol (ISOP, 10(-6) M)-evoked increases in SCC and PD to 57% and 66% of that with ISOP alone, respectively, with a significant decrease in conductance (G) to 87% of that with ISOP alone in a dose-dependent fashion, from 10 to 200 U/ml. Even after ISOP (10(-6) M)-evoked PD and SCC had reached a plateau, TNF produced significant decreases in PD and SCC up to 79% and 83% of that with ISOP alone, respectively, in a dose-dependent fashion, from 50 to 200 U/ml. Amiloride did not alter the inhibitory action of TNF on ISOP-evoked SCC and PD values. Antiserum against TNF abolished the inhibitory action of TNF on ISOP-evoked response. In contrast, submucosal TNF did not alter PD, SCC or G. These findings indicate that TNF attenuates beta agonist-evoked increases in chloride secretion across airway epithelium.

Animals↗

PubMed1991

Nicotine improves cognitive disturbance in rodents fed with a choline-deficient diet.

The effect of nicotine on learning disturbances was tested in rats. Rats were fed either a choline-enriched or a choline-deficient diet. Concentration of acetylcholine in the whole brain was significantly lower in rats fed with choline-deficient diet than rats fed with choline-enriched diet. Passive avoidance learning shows that rats on a choline-deficient diet showed significantly impaired learning compared to rats on a choline-enriched diet. Nicotine (0.04 mg/kg) administered intraperitoneally significantly potentiated learning in rats on a choline-deficient diet, as well as in rats on a choline-enriched diet. We, therefore, suggest that nicotine may potentiate learning in an acetylcholine-deprived brain.

Acetylcholine↗

PubMed1991

Effective site of bronchodilation by antiasthma drugs in subjects with asthma.

We studied the effective sites of airway response to atropine and fenoterol aerosols and to the intravenous injection of aminophylline in patients with stable and spontaneous asthma, by the simultaneous assessment of respiratory resistance (Rrs) and anatomic dead space (VD). Central airway response was determined by VD, and overall response was determined by Rrs. Peripheral airway response was inferred from Rrs when the change in VD was slight. Atropine (4 mg/ml) or fenoterol (0.4 mg/ml) was continuously inhaled during tidal breathing for 5 minutes. Inhalation of both atropine and fenoterol increased Grs (reciprocal of Rrs) (p less than 0.01) with a simultaneous increase in VD (p less than 0.01) in the patients with stable and spontaneous asthma. Fenoterol increased Grs more than did atropine at an equivalent increase in VD in patients with spontaneous asthma (p less than 0.05). Intravenous injection of aminophylline (250 mg) had no effect on either Grs or VD in patients with stable asthma, but it significantly increased Grs (p less than 0.01) without change in VD in patients with spontaneous asthma. These results suggest that the predominant sites of bronchodilation induced by inhaled atropine are the central airways, that those sites induced by intravenous injection of aminophylline are the peripheral airways, and that inhaled fenoterol dilates both the central and peripheral airways in subjects with asthma. Differences among clinically used bronchodilators on the effective sites may be considered in the treatment of bronchial asthma.

Adult↗

PubMed1991

Gallium scintigraphy in neoplastic angioendotheliosis of the lung.

A case of neoplastic angioendotheliosis of the lung is reported. A 56-year-old man presented with a 2-month history of fever, increased serum lactic dehydrogenase, and arterial hypoxemia. Chest radiography revealed diffuse reticulonodular opacity, whereas CT scanning showed diffuse small nodular areas of increased attenuation with indistinct borders. Diffuse pulmonary uptake of Ga-67 was noted in scintigraphy. Combination chemotherapy designed for lymphoma induced a remission of the disease.

Gallium Radioisotopes↗

PubMed1991

Cinematic three-dimensional surface display of cardiac blood pool tomography.

A method of three-dimensional cinematic display (3D cine) of cardiac blood pool tomography is described. ECG-gated transaxial blood pool imaging was obtained from a set of projection images that were collected from 32 images with 10 ECG-gated images per projection during a 180 degrees arc of a rotating gamma camera. A surface contour of the blood pool was determined by a set of isocount lines (40-55% of the maximum pixel counts) of the transaxial images. 3D cine was made by a depth-shading method, in which brightness of a given point on the contour was set proportional to the distance between the viewing plane and the point and to the incident angle formed by the viewing line and the surface of the point. In 15 patients, 3D cine showed hypokinesia, akinesia, dyskinesia, ventricular aneurysm, and opposite motions of the atria and ventricles. Diagnoses of left ventricular motion by 3D cine agreed well with those by echocardiography and contrast left ventriculography.

Aged↗

PubMed1991

Do diagnostic procedures other than inhalation challenge predict immediate bronchial responses to inhaled allergen?

To investigate the relationships between allergen inhalation challenge and other diagnostic procedures, inhalation challenge with house dust (HD) allergen, intradermal skin tests with HD allergen, inhalation challenge with methacholine and circulating HD allergen-specific IgE levels were examined in 104 patients with bronchial asthma. Using the single exposure method, allergen inhalation challenge was performed. Forty-three patients had positive bronchial responses to allergen and 61 patients had negative bronchial responses. With serially diluted HD allergen (10(-3) to 10(-6), w/v), skin-test sensitivity was expressed as the highest dilution required to produce a weal of more than 9 x 9 mm. With the continuous exposure method, bronchial responsiveness to methacholine was evaluated as the number of units of inhaled methacholine (PD35-Grs) from the start to the point at which Grs had decreased by 35% from its baseline value. The level of circulating HD allergen-specific IgE was measured with the Phadebas RAST system and the results were assessed as a RAST score. Using discriminant analysis, in which the independent variables were skin-test sensitivity, PD35-Grs and the RAST score, only in 30% of all patients was bronchial responsiveness to inhaled HD allergen predictable. Therefore, we suggest that inhalation challenge with allergen is an essential test for determining the role of a specific allergen in airways at present.

Administration, Inhalation↗

PubMed1991

Responses of atrium and ventricle to sustained sympathetic nerve stimulation.

To determine whether chronotropic and atrial inotropic responses to sympathetic nerve stimulation are maintained longer than ventricular inotropic response, the present study was performed with control and acute reserpinized dogs. We stimulated the right stellate ganglion of both groups supramaximally for 60 min and compared right atrial responses (chronotropism and inotropism) with left ventricular (LV) dP/dtmax. In the control group, heart rate (HR) immediately increased and was only slightly attenuated with 60 min of stimulation, and right atrial (RA) inotropic response was less attenuated than was LV response (7% in HR, 33% in RA dP/dtmax, 50% in LV dP/dtmax, P less than 0.01, from the peak value of each response). RA and LV norepinephrine (NE) content was decreased by the stimulation but remained higher than the LV control value. In the reserpinized group, NE content in the RA was low before the stimulation and was further decreased by the stimulation. In this group, HR response was attenuated (27% in HR, P less than 0.01) as was LV dP/dtmax, and the difference in contractile responsiveness between atrium and ventricle disappeared (58% in RA dP/dtmax vs. 61% in LV dP/dtmax, NS). The results indicate that the chronotropic response was only slightly attenuated and that the atrial contractile response was attenuated less than the ventricular response, with sustained sympathetic nerve stimulation in the normal heart. This can be ascribed to the much higher NE content in the RA than that in the LV.

Animals↗

PubMed1991

Inhomogeneous response of expiratory muscle activity to cold block of the ventral medullary surface.

We assessed the effects of cooling the ventral medullary surface (VMS) on the activity of chest wall and abdominal expiratory muscles in eight anesthetized artificially ventilated dogs after vagotomy and denervation of the carotid sinus nerves. Electromyograms (EMGs) of the triangularis sterni, internal intercostal, abdominal external oblique, abdominal internal oblique, and transversus abdominis muscles were measured with EMG of the diaphragm as an index of inspiratory activity. Bilateral localized cooling (2 x 2 mm) in the thermosensitive intermediate part of the VMS produced temperature-dependent reduction in the EMG of diaphragm and abdominal muscles. The rib cage expiratory EMGs were little affected at 25 degrees C; their amplitudes decreased at lower VMS temperatures (less than 20 degrees C) but by significantly fewer degrees than the diaphragmatic and abdominal expiratory EMGs at a constant VMS temperature. With moderate to severe cooling (less than 20 degrees C) diaphragmatic EMG disappeared, but rib cage expiratory EMGs became tonic and resumed a phasic pattern shortly before the recovery of diaphragmatic EMG during rewarming of the VMS. These results indicate that the effects of cooling the VMS differ between the activity of rib cage and abdominal expiratory muscles. This variability may be due to inhomogeneous inputs from the VMS to expiratory motoneurons or to a different responsiveness of various expiratory motoneurons to the same input either from the VMS or the inspiratory neurons.

Animals↗

PubMed1991

Decrease in functional residual capacity during inspiratory loading and the sensation of dyspnea.

The purposes of the present study were to determine the changes in functional residual capacity (FRC) during inspiratory loading and to examine their mechanisms. We studied seven normal subjects seated in a body plethysmograph. In both graded inspiratory elastic (35, 48, and 68 cmH2O/l) and resistive (21, 86, and 192 cmH2O.l-1.s) loading, FRC invariably decreased from control FRC and phasic expiratory activity increased. The reduction in FRC was greater with greater loads. A single inspiratory effort against an inspiratory occlusion at three different target mouth pressures (-25, -50, and -75 cmH2O) and durations (1, 2, and 5 s) also resulted in a decrease in FRC with an increase in expiratory electromyogram activity in the following expiration. The decrease in FRC was greater with greater target pressure and duration. This decrease in FRC is qualitatively similar to that during inspiratory loaded breathing, and we suspect that the same mechanisms are at work. Because neither vagal nor chemoreceptor reflex can account for these responses, we suspect conscious awareness of breathing or behavioral control to be responsible. In an additional study, the sensation of discomfort of breathing during elastic loading decreased with a decrease in FRC. These results suggest that the reduced FRC may be due to behavioral control of breathing to reduce the sensation of dyspnea during inspiratory loading.

Adult↗

PubMed1991

Effects of bronchoconstriction and external resistive loading on the sensation of dyspnea.

To determine whether the intensity of dyspnea at a given level of respiratory motor output differs between bronchoconstriction and the presence of an external resistance, we compared the sensation of difficulty in breathing during isocapnic voluntary hyperventilation in six normal subjects. An external resistance of 1.9 cmH2O.1-1.s was applied during both inspiration and expiration. To induce bronchoconstriction, histamine aerosol (5 mg/ml) was inhaled until airway resistance (Raw) increased to a level approximately equal to the subject's control Raw plus the added external resistance. To clarify the role of vagal afferents on the genesis of dyspnea during both forms of obstruction to airflow, the effect of airway anesthesia by lidocaine aerosol inhalation was also examined after histamine and during external resistive loading. The sensation of difficulty in breathing was rated at 30-s intervals on a visual analog scale during isocapnic voluntary hyperpnea, in which the subjects were asked to copy an oscilloscope volume trace obtained previously during progressive hypercapnia. Histamine inhalation significantly increased the intensity of the dyspneic sensation over the equivalent external resistive load at the same levels of ventilation and occlusion pressure during voluntary hyperpnea. Inhaled lidocaine decreased the sensation of dyspnea during bronchoconstriction with no change in Raw, but it did not significantly change the sensation during external resistive loading. These results suggest that afferent vagal activity plays a role in the genesis of dyspnea during bronchoconstriction.

Adult↗

PubMed1991

Effect of mabuterol on tracheal mucociliary clearance of magnetized iron particles in anesthetized dogs.

We studied the effect of mabuterol on the tracheal mucociliary clearance of magnetized iron particles in anesthetized dogs. A catheter was inserted directly into the trachea through the mouth and 0.05 ml of saline solution with 30 mg of Fe3O4 was instilled into the trachea. After magnetization from outside the chest wall, the remanent magnetic field (RMF) strength generated in the trachea was sequentially measured with a flux-gate magnetometer. The decay of RMF immediately after sequential magnetization showed a clearance of Fe3O4 particles. Mabuterol (10 micrograms/kg) increased clearance as much as isoproterenol (10 micrograms/kg) 30 min after intravenous injection relative to control measurement (p less than 0.01). These results suggest that mabuterol is useful to promote clearance.

Adrenergic beta-Agonists↗