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Biomedical subjects

T Nakada

Publications and source records attributed to T Nakada.

At least 613 records · Page 34Linked to original sources
PubMed1982

Enhanced protein synthesis of heart in adrenal-regeneration hypertension and its reduction following antihypertensive treatment.

After unilateral nephrectomy and bilateral adrenal enucleation at 5 weeks of age, salt-loaded rats developed hypertension (ARH) at 6 weeks. Fibrous vascular protein and in vivo incorporation of 3H-lysine into this protein fraction were measured at 15 weeks of age in these animals. This study demonstrates: (1) that incorporation rates of 3H-lysine into cardiac collagen and elastin in ARH rats were greater than in control rats (p less than 0.001, respectively), and (2) that administration of phenoxy-benzamine hydrochloride decreased the incorporation of tritiated lysine into cardiac collagen in ARH rats, concomitant with a reduction in blood pressure. Based on these findings, increased synthesis of cardiac collagen and elastin appears to play an important role in the development of hypertension in ARH.

Adrenal Glands↗
PubMed1982

Quantitative assessment of water content of human lung: a study on open lung biopsy specimen.

Quantitative assessments of human lung water are necessary to evaluate lung water changes, but little knowledge is available about a human "normal" lung. To determine a "normal" lung water content, pieces of lung tissue were obtained from lungs which should be resected for solitary nodular lung diseases, and the water content was assessed in terms of the ratio of extravascular lung water to blood free dry lung weight (Qw1), using the gravimetric methods. Among 152 patients who underwent open thorax surgeries for their solitary nodular lung diseases, 35 lung specimens were obtained from lungs which were free from any abnormal lesions. Since the postoperative histological examination did not reveal any pathological findings except for the solitary nodules in the resected lobes of 35 patients, the 35 pieces were also considered to be "normal". The value of Qw1 was 3.66 +/- 0.29 (mean +/- S.D.) g/g blood free dry lung. This value would serve as a reference of Qw1 in human "normal" lung.

Adult↗
PubMed1982

Effects of irradiation on the pulmonary vascular fluid and protein exchange.

In anesthetized sheep, ventilated by positive pressure, pulmonary arterial and left atrial pressures, cardiac output, and lung lymph flow (Qlym) were measured and lymph-to-plasma protein concentration ratio (L/P) was determined. For sheep were irradiated with 60Co on the bilateral lower lobes, avoiding irradiation on the heart and the caudal mediastinal lymph node. Qlym increased during and after irradiation, and reached a new steady state (160% increase), while pulmonary arterial or left atrial pressure did not change. In 4 control experiments, pulmonary hemodynamics, Qlym or L/P did not change. Therefore the increased fluid or protein flux after irradiation cannot be ascribed only to abnormal pulmonary hemodynamics. Endothelial damages seem to play a role in the increase of fluid filtration and protein permeability.

Animals↗
PubMed1982

The role of vascular protein and renin in chronic two-kidney, one clip Goldblatt hypertension.

Chronic hypertension was induced in rats by application of a clip for 17 or 20 weeks to the unilateral renal artery and leaving the contrarenal vessel intact (two-kidney one clip hypertension, 2K-1C hypertension). Some of the rats received antihypertensive treatment with phenoxybenzamine (POB). 3H-proline was injected into all rats in the 17th experimental week to observe the in vivo incorporation rates of 3H-proline into vascular non-collagenous protein and vascular collagen. Plasma renin activity (PRA) of decapitated rats was assayed in the terminal stage of the experiment. Significant differences were noted between 2K-1C hypertensive rats and sham-operated normotensive rats, the former rats having significantly higher incorporation rates of 3H-proline into non-collagenous protein (p less than 0.001) and collagen of testicular (p less than 0.05) or mesenteric artery (p less than 0.01). The 3H-proline incorporated into each fraction of vascular protein was reduced by antihypertensive treatment with POB either in sham-operated rats (p less than 0.05) or 2K-1C rats (p less than 0.001), except for the aorta and heart. Positive correlations were noted between blood pressure and incorporated 3H-proline into non-collagenous protein of testicular arteries (r = 0.78, p less than 0.001) and mesenteric arteries (r = 0.90, p less than 0.001), in all animals. Similar positive correlations were also noted between blood pressure and tritiated collagen, to lesser extents, in testicular arteries (r = 0.67, p less than 0.001) and mesenteric arteries (r = 0.73, P less than 0.001). A rapid turnover of 3H-proline incorporated into non-collagenous protein was characteristically observed in the testicular arteries, mesenteric arteries and aorta of 2K-1C hypertensive rats 3 weeks after the proline injection. Though magnitude was low, the turnover of 3H-proline was also noted in each collagen fraction of the equivalent vessels of the same hypertensive rats. PRA of 2K-1C hypertensive rats was similar to that of sham-operated normotensive rats at the 20th week. Levels of PRA of the former or the latter rats treated with POB were 2.4-fold (p less than 0.001) or 2.5-fold (p less than 0.001) higher than those of non-medicated corresponding controls. These results indicate that (1) increased synthesis of vascular non-collagenous protein as well as collagen, especially of small arteries, plays a major role for the pathogenesis of chronic hypertension in 2K-1C rats, and (2) renin does not contribute to elevation of the blood pressure in the maintenance phase of this type of experimental hypertension.

Animals↗
PubMed1982

Floccular inhibition of the vestibulo-ocular reflex in man.

The vestibulo-ocular reflex (VOR) plays a major role in ocular motility. Stimulation of each semicircular canal produces excitation of a specific extraocular muscle and inhibition of its antagonist in each eye. Floccular inhibition of the VOR has been extensively studied in the rabbit. Inhibitory projections from floccular Purkinje cells reach the ipsilateral vestibular nucleus via the restiform body and selectively control certain VORs. We examined the ocular functions in a patient with a lateral lower pontine infarct that included the restiform body. The patient exhibited unilateral, selective disinhibition of the VOR manifested by disconjugate upward rotatory drift of the eyes at the end of lateral eye movement towards the side of the lesion. He had marked directional preponderance on caloric testing. The same underlying mechanism which produced the biased VOR also appeared to affect target position determination in fast eye movements, resulting in lateropulsion of saccades and asymmetric OKNs. This is the first clinical case supporting the theory of selective cerebellar inhibition of the VOR.

Animals↗