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Biomedical subjects

R Kikuchi

Publications and source records attributed to R Kikuchi.

At least 73 records · Page 4Linked to original sources
PubMed1985

Airway responsiveness after antigen inhalation challenge in hypersensitive pneumonia.

We performed pulmonary function tests after antigen inhalation challenge in 6 patients with hypersensitive pneumonia. 2 patients showed a reduction in maximal expiratory flow at 25% vital capacity (V25) within the first 1-3 h (early reaction) followed by a decrease in vital capacity, forced expiratory volume at 1 s and increased respiratory resistance in the next 4-7 h (late reaction). In the other 4 patients, only V25 decreased within the first 1-3 h. Diffusion capacity did not change significantly. It is suggested that the small airway is the most sensitive site of reaction to an antigen inhalation challenge in hypersensitive pneumonia and that the obstructive change of the small airway could occur as the early reaction.

Adolescent↗
PubMed1984

Effects of pulmonary congestion on airway reactivity to histamine aerosol in dogs.

We examined the effect of acute pulmonary vascular congestion on bronchial reactivity in dogs in a standard challenge protocol. Airway responsiveness to histamine whose concentration was varied in a stepwise incremental fashion was assessed from changes in pulmonary resistance (RL) and dynamic compliance (Cdyn) in 10 anesthetized dogs. Brief acute pulmonary congestion was created by inflating a balloon placed in the left atrium to raise left atrial pressure to 20-30 cmH2O for 1 min. Pulmonary congestion did not change RL in the control condition. However, after histamine inhalation, RL was further increased by pulmonary congestion, making the two effects synergistic. This phenomenon could not be observed with vagi cut. Pulmonary congestion decreased Cdyn in all dogs regardless of histamine concentration, with or without vagotomy. We conclude that pulmonary vascular congestion makes the bronchi hyperreactive through vagal reflexes. The reduction in Cdyn caused by pulmonary congestion appears to stem mainly from the narrowing of peripheral airways by adjacent vascular engorgement.

Aerosols↗
PubMed1982

Effect of vagal tone on airway smooth muscle force and peribronchial pressure in dogs.

The main lobar bronchi were isolated airtight from the rest of the lung in excised dog lung. In the relaxed isolated lobar bronchi in excised dog lung, we simulated the percent narrowing of bronchial diameter which was observed with vagus nerves intact and stimulated relative to that with vagus nerves cut (relaxed state). The percent narrowing of bronchi with vagus nerve intact and stimulated were adapted from the data by Hahn et al. (J. appl. Physiol., 41, 581-589, 1976). The forces of airway smooth muscle (Psm) were obtained as the negative intrabronchial pressure (Pbr) when the isolated bronchi were narrowed to the same diameter as those with vagus intact and stimulated, and they were 5 to 10 cmH20 and 10 to 30 cmH20, respectively. Peribronchial pressure (Px) was obtained as the difference of Pbr in the conditions of intact and dissected parenchyma when the diameter of the isolated bronchi were simulated to those with vagus intact and stimulated, and they were positive relative to pleural pressure (Ppl) with vagus cut, negative to Ppl with vagus stimulated and near zero relative to Ppl with vagus intact. It was suggested that smooth muscle tone which narrowed the bronchi to the same extent as the diameter with vagus intact made homogeneous expansion between bronchi and lung parenchyma.

Animals↗
PubMed1982

Disappearance curves and single-breath DLCO from consecutive samples during slow expiration.

The disappearance of CO in three expirates consecutively sampled after various breath holding periods was measured in seven normal subjects. The CO disappearance curves in the three expired portions were nearly linear and parallel each other, but the curves for later sampled expirates were lower, and even those for earlier sampled expirates passed under unity at time zero when extrapolated on a logarithmic graph of relative expired alveolar CO concentration against breath holding time. The slope of each disappearance curve shows "the true diffusing capacity at breath holding lung volume", eliminating an effect of rapid CO absorption at a lower lung volume during expiration. This effect is considered the cause of the downward shift of the decay curve, and the shift is magnified in slow expiration. In addition, the three parallel lines indicate a homogeneous distribution of DL/VA within the lungs. Subsequently, DLCO in conventional calculations had greater values in shorter breath holding time and later sampling.

Adult↗
PubMed1981

Bronchial length behavior with respect to lung volume histories in different bronchial sizes in excised dog lungs.

The bronchial length behavior of three different-sized segments in seven excised dog lobes was examined in terms of the transpulmonary pressure (PL)-bronchial length relationship and the absolute lung volume (VL)-bronchial length relationship during lung inflation and deflation. The straight bronchi of the right lower lobes were used and the bronchial lengths were measured directly and continuously with a linear displacement transducer which was connected by a thin rod to a wedged bead in the bronchi. From PL 30 to 0 cmH2O, the lengths of proximal, intermediate and distal bronchi from the airway opening decreased by 25.2 +/- 4.0%; 36.5 +/- 10.4%; and 37.0 +/- 11.5% (mean +/- S.D.), respectively. Hysteresis of bronchial length existed in the lung volume histories at the same PL, but not at the same VL. With deflation of lung from PL 30 to 0 cmH2O, the more proximal bronchi less changed their length disproportionately with lung volume. It is suggested that nonhomogeneous expansion between lung parenchyma and the bronchi would be more intense in the proximal bronchi than the distal bronchi in terms of bronchial length.

Animals↗
PubMed1980

The locus of the posterior subdivision of the inferotemporal visual learning area in the monkey.

In an attempt to define the posterior subdivision of the inferotemporal visual learning area more precisely than before, pattern discrimination retention, serial object discrimination learning and concurrent object discrimination learning were tested in 16 monkeys with lesions in one of four different cytoarchitectural areas; TEO, OA, OB and OC, and in five unoperated monkeys. Marked impairment was found only in pattern discrimination retention and only in the monkeys with lesions of area TEO. It was concluded that the posterior limit of the inferotemporal visual learning area is at the ascending limb of the inferior occipital sulcus, and that the posterior subdivision thus comprises the single anatomical area TEO and does not extend into areas OA and OB.

Animals↗