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Biomedical subjects

T Ashihara

Publications and source records attributed to T Ashihara.

At least 109 records · Page 6Linked to original sources
PubMed1985

Digitalis-induced augmentation of cardiopulmonary baroreflex control of forearm vascular resistance.

We sought to determine whether digitalis augments cardiopulmonary baroreflex control of forearm vascular resistance in normal young men. Cardiopulmonary baroreceptor input was reduced with lower body negative pressure (LBNP) at 10 and 20 mm Hg, which decreased central venous pressure but did not alter blood pressure or heart rate. Decreases in forearm blood flow and increases in forearm vascular resistance with LBNP were greater after administration of lanatoside C (Cedilanid) than before, and the slope of the regression line relating changes in central venous pressure and those in forearm vascular resistance was steeper after lanatoside C. Vasoconstrictor responses to the cold pressor test did not differ before and after lanatoside C, which suggested that augmented responses to LBNP after the drug were not caused by a generalized change in reflex control. These results suggest that lanatoside C augments the tonic inhibitory influence of cardiopulmonary baroreceptors in normal men.

Adult↗
PubMed1985

The effects of sublingually administered nitroglycerin on forearm vascular resistance in patients with heart failure and in normal subjects.

This study examined the effects of sublingually administered nitroglycerin on forearm resistance vessels in normal subjects (n = 9) and in patients with congestive heart failure (n = 8). Forearm blood flow was measured with a strain-gauge plethysmograph and forearm vascular resistance was calculated. To assess the magnitude of reflex forearm vasoconstriction triggered by decreased central venous pressure after sublingual nitroglycerin, lower body negative pressure (LBNP) was applied to produce a comparable decrease in central venous pressure to that after nitroglycerin. The change in forearm vascular resistance during LBNP was compared with that after nitroglycerin. In normal subjects, LBNP increased but nitroglycerin did not change forearm vascular resistance. In patients with congestive heart failure neither nitroglycerin nor LBNP changed forearm vascular resistance. The direct vasodilator effect of nitroglycerin on forearm resistance vessels assessed by the difference between the change in forearm vascular resistance produced by nitroglycerin and that during LBNP tended to be less in patients with congestive heart failure than in normal subjects, which might have resulted from decreased vasodilator capacity of resistance vessels in patients with congestive heart failure. Changes in forearm vascular resistance with a cold pressor test were not different between normal subjects and patients with congestive heart failure. These data suggest that in normal subjects, nitroglycerin does not alter forearm vascular resistance because its dilator effect is offset by reflex vasoconstriction. In patients with congestive heart failure, reflex vasoconstriction is impaired but the direct vasodilator effect of nitroglycerin also tends to be reduced, so that as a net effect forearm vascular resistance is not altered.

Adult↗
PubMed1985

[DNA-RNA cytofluorometric analysis of a case of osteosarcoma in relation to histological characteristics].

We applied DNA-RNA cytofluorometry with AO stain to cell kinetic analysis of osteosarcoma in a 12-year-old girl in relation to its histological characteristics. Histological findings obtained for 9 macroscopically different lesions were grouped into 4 main structural characteristics, but their cytofluorometric results were classified into 2 main patterns of DNA-RNA distribution. One showed remarkable polyploidization with many DNA synthetic cells in the invasive lesions, which were composed of pleomorphic cells forming osteoid or occasionally cartilaginous matrix. The other showed marked accumulation of tetraploid cells almost without DNA synthetic cells, being composed of relatively uniform fibroblastic or stellate-like cells in the cartilaginous matrix. These results indicated a close relationship between cell proliferative activity and the tissue environment.

Bone Neoplasms↗
PubMed1985

[DNA cytofluorometric analysis of nerve sheath tumors].

The present study was undertaken to clarify the ploidy patterns of peripheral nerve sheath tumors by determining nuclear DNA content of the individual tumor cells using PI-DNA cytofluorometry (NIKON SPM-RF1-D), and to investigate the relation between the ploidy patterns and histopathological findings. Most of the solitary neurilemmomas and neurofibromas studied were found to be associated with euploid-polyploidization, almost without DNA synthetic cells. It was also shown that the number of polyploid cells increased in accordance with an increase in the frequency of cells having large, atypical nuclei in histological picture, regardless of the natures of cellular arrangements. Malignant schwannomas, however, were composed of many polyploid and aneuploid cells with an increase of DNA synthetic cells, indicating their active cell proliferation. Thus, the ploidy patterns of nerve sheath tumors were remarkably different between benign and malignant ones. Furthermore, a case of multiple schwannoma suspected to be a variant of von Recklinghausen's disease, showed euploid-polyploidization with many DNA synthetic cells, indicating a ploidy pattern intermediate between benign and malignant tumors. This tumor thus appears to be a premalignant tumor or in the early stages of malignancy.

Adolescent↗
PubMed1984

Impaired baroreflex control of vascular resistance and heart rate in acute myocardial infarction.

The baroreflex control of vascular resistance and heart rate was studied in 11 patients to determine whether it is impaired in patients with acute myocardial infarction. Reflex forearm vasoconstriction in response to lower body negative pressure at 40 mm Hg was less in the early convalescent phase (mean seven days) than in the late convalescent phase (mean 41 days). Pressor as well as vasoconstricting responses to the cold pressor test did not differ between the early and late convalescent phases. The slope of the regression line relating systolic blood pressure and the RR interval during a transient rise in blood pressure produced by intravenous phenylephrine was appreciably reduced in the early convalescent phase of myocardial infarction. These results suggest that baroreflex control of vascular resistance and heart rate is impaired in patients with acute myocardial infarction.

Adult↗
PubMed1984

Increase in reflex vasoconstriction with indomethacin in patients with orthostatic hypotension and central nervous system involvement.

Since indomethacin may be effective in the treatment of orthostatic hypotension, the ability of this drug to increase reflex vasoconstriction was studied in six patients with orthostatic hypotension and in five normal subjects. Reflex forearm vasoconstriction during lower body negative pressure at 20-40 mm Hg was measured before and after indomethacin 50 mg by mouth. In patients with orthostatic hypotension and central nervous system involvement indomethacin increased recumbent blood pressure, resting forearm vascular resistance, and reflex forearm vasoconstriction during lower body negative pressure. The fall in blood pressure with lower body negative pressure was not significantly inhibited by indomethacin, but mean blood pressure during lower body negative pressure was higher after than before indomethacin. Indomethacin did not alter these responses in normal subjects. The increase in reflex vasoconstriction with indomethacin may contribute to its therapeutic effects in the treatment of orthostatic hypotension.

Adult↗
PubMed1984

Venous responses to salt loading in hypertensive subjects.

It has been previously suggested that salt loading produces structural changes of the arteries in hypertensive patients who respond to salt loading with a greater rise of blood pressure. This study examined the possibility that salt loading alters venous distensibility in hypertensive patients. Twenty-one patients with essential hypertension were placed on a low-sodium diet (70 meq) for 7 days and then were placed on a high-sodium diet (345 meq) for 7 days. Patients were arbitrarily divided into two groups based on the response of their blood pressure to salt loading: (1) those whose mean blood pressure increased by more than 10% while on the high-salt diet as compared with those on the low-salt diet (salt-responsive patients, n = 8) and (2) those whose mean blood pressure did not increase by more than 10% (salt-nonresponsive patients, n = 13). The venous pressure-volume relationship was determined in the forearm with a water-filled plethysmograph when patients were on the low- and high-salt diet. Venous pressure-volume curves were not different between salt-responsive and salt-nonresponsive patients while on the low-salt diet. High-salt intake shifted the curve toward the pressure axis for salt-responsive patients (p less than .05) but not for salt-nonresponsive patients. Phentolamine, 1 mg administered intravenously for 5 min, did not significantly alter venous pressure-volume curves for either group while on the low- or high-salt diet. These results suggest that salt loading decreased venous distensibility in salt-responsive patients, which resulted from nonadrenergic mechanisms: structural changes of the veins could perhaps be included as one of these mechanisms.

Adult↗
PubMed1984

Altered control of hindlimb vascular resistance by vagal afferents in spontaneously hypertensive rats. Difference in the early and late stage of hypertension.

The aim of this study was to examine whether control of vascular resistance by vagal afferents is altered in the early as well as late stage of hypertension. We examined the effects of vagotomy on hindlimb vascular resistance as well as on arterial baroreflex control of hindlimb vascular resistance in spontaneously hypertensive rats and Wistar-Kyoto rats, 12 and 35 weeks old. Vagotomy in rats with the intact arterial baroreceptors increased hindlimb vascular resistance in all four groups. Hindlimb vascular responses to graded sympathetic nerve stimulation were closely linear up to 6 Hz in all groups, and the slope of the response was approximately 1.4 times steeper in spontaneously hypertensive than in Wistar-Kyoto rats, in both the young and old groups. The increase in hindlimb vascular resistance after vagotomy normalized by the slope of the response to sympathetic nerve stimulation was greater in young spontaneously hypertensive rats than in young Wistar-Kyoto rats, but was less in old spontaneously hypertensive rats than in old Wistar-Kyoto rats. Vagotomy increased the gain of arterial baroreflex control of hindlimb vascular resistance in young spontaneously hypertensive rats, and in two groups of Wistar-Kyoto rats, but not in old spontaneously hypertensive rats. The percent increase in the gain of arterial baroreflex control of hindlimb vascular resistance after vagotomy tended to be greater in young spontaneously hypertensive than in young Wistar-Kyoto rats, but was less in old spontaneously hypertensive than in old Wistar-Kyoto rats. Central venous pressure and left ventricular end-diastolic pressure were higher in spontaneously hypertensive than in Wistar-Kyoto rats in both young and old groups. Left atrial distensibility assessed by obtaining the atrial pressure-volume relationship was comparable between young spontaneously hypertensive and young Wistar-Kyoto rats, but was less in old spontaneously hypertensive than in old Wistar-Kyoto rats. These results indicate that vagal afferents exert tonic inhibition on control of hindlimb vascular resistance in spontaneously hypertensive as well as in Wistar-Kyoto rats, and that tonic inhibitory influence of vagal afferents on control of hindlimb vascular resistance is altered in spontaneously hypertensive rats, augmented in young, but attenuated in old, spontaneously hypertensive rats, compared with that in age-matched Wistar-Kyoto rats. It is considered that altered control of vascular resistance by vagal afferents in spontaneously hypertensive rats may result from changes in vagal afferent activity.

Animals↗
PubMed1984

[DNA cytofluorometry of soft tissue tumors].

We carried out DNA cytofluorometry with propidium iodide stain on the 17 cases of soft tissue tumors including giant cell tumor of the tendon sheath, pigmented villonodular synovitis, 2 hemangiomas, 3 lipomas, 5 schwannomas, 3 neurofibromas, liposarcoma and synovial sarcoma. The benign tumors were characterized by regular polyploidization with very few S-phase cells, indicating slow tumor growth. Most of the malignant soft tissue tumors were associated with remarkable polyploidization with an increase in S-phase cells. However, some malignant tumors did not show polyploidization. We concluded, therefore, that an increase in S-phase cells is an important, cytofluorometric criterion for malignancy of soft tissue tumors.

Adult↗
PubMed1984

[Cell kinetics and nuclear ploidy pattern in relation to the growth of gastric cancers as analyzed by DNA-RNA cytofluorometry].

We investigated the cell kinetics and nuclear ploidy pattern of human gastric cancers (12 early and 30 advanced cancers) using DNA-RNA cytofluorometry (NIKON SPM-RF1-D) with AO stain. The results showed that the gastric cancers studied could be divided into two main groups on the basis of ploidy pattern determined both by DNA and RNA contents: group I without, and group II with polyploidization. Cells having nuclear DNA contents between 2 n and 4 n were regarded as representing those in the S phase, and it was found that both groups had similar proliferative activity. In group I, cell proliferation without polyploidization seemed to be maintained during tumor growth regardless of the extent of invasion, and the fraction of 2 n cells was 72-94%, compared to 93-99% in control cells from the non-neoplastic gastric epithelium. In group II, however, the extent of polyploidization appeared to be increased in association with both the tumor growth and its invasion into deeper tissues; thus the fraction of 2 n cells was low, ranging from 12 to 79%. Especially, the fraction of 2 n cells in cancers with aneuploid-polyploidization was further decreased to 6-25%. Based on these results, it is hypothesized that, in the early stages of gastric cancers, the cell population may be composed mostly of diploid cells, but with both further tumor development and its invasion, the neoplastic cells may gradually differentiate into two distinct cell populations.

Adult↗
PubMed1984

[Cytofluorometric analysis of cell kinetics in relation to tumor growth of advanced gastric cancers].

Correlated studies on both cell kinetics in association with nuclear ploidy pattern and pathological morphology of advanced gastric cancers were carried out using DNA-RNA cytofluorometry (NIKON SPM-RF1-D) with AO stain. The results showed that advanced gastric cancers could be divided into two main groups. Group 1 (12 cases) was the diploid cell population, commonly found in Borrmann type 4 showing diffuse infiltration of cancer cells, and group II (14 cases) was characterized by polyploidization, usually found in Borrmann type 2 or 3 showing adenocarcinomas composed of markedly pleomorphic cells. In addition, we further differentiated from group II four cases of cancers which included aneuploid cells with more pronounced pleomorphism than group II, and classified them as group II'. These results suggest that cell kinetics and nuclear ploidy pattern of the advanced gastric cancers are closely related to pathological characteristics, i.e., groups I and II to undifferentiated (gastric type) and differentiated (intestinal type) carcinomas, respectively.

Adenocarcinoma↗
PubMed1983

Endogenous prostaglandins do not modulate the hindquarters vascular responses to adrenergic stimulation in rats.

The purpose of this study was to examine whether endogenous prostaglandins (PGs) modulate vascular responsiveness to adrenergic stimuli in the hindquarters of stroke-prone Spontaneously Hypertensive Rats (SHR-sp) and Wistar-Kyoto rats (WKY). Previously we have shown that synthesis of endogenous PGs in blood vessels in the rat hindquarters was greater in SHR-sp than in WKY and that high salt diet increased the level of endogenous PGs in SHR-sp but not in WKY. Vascular responses to norepinephrine (NE) and sympathetic nerve stimulation (SNS) were examined before and after indomethacin (IND), 2 mg/kg, administered intravenously. NE was administered intraarterially into the autoperfused hindquarters. Hindquarters vascular responses to these vasoconstrictor stimuli were not altered by IND in SHR-sp and WKY at the different level of endogenous PGs. These results indicate that hindquarters vasoconstriction in response to adrenergic stimuli were not altered by IND even when vascular synthesis of endogenous PGs was augmented. The results suggest that endogenous PGs do not modulate the hindquarters responses to adrenergic stimulation in rats.

Animals↗
PubMed1983

[Quantitative analysis of nuclear DNA of rat chondrocytes during the course of growth and aging--Feulgen-DNA cytofluorometry method].

There have been no reported studies on the Feulgen-DNA cytofluorometry of the cartilage cells. We have attempted to devise a method of cell separation from the epiphyseal and articular cartilages of the rats, and to analyze by cytofluorometry the changes in the ploidy patterns of these chondrocytes during growth and ageing of the animals. Chondrocytes were isolated from the proximal cartilage of tibia by dual enzymatic digestions of the cartilage matrix with papain and collagenase, followed by mechanical cell separation with scissors and a micro-homogenizer, and were smeared onto the object glass with PBS. These procedures were found to be suitable for the Feulgen-DNA cytofluorometry of the chondrocytes from our repeated studies. We also carried out Feulgen-DNA cytofluorometry combined with 3H-thymidine autoradiography to determine cellular DNA content of the DNA synthetic chondrocytes in the epiphyseal cartilage. It has been clarified that during the growth course of the rats, the chondrocytes of the epiphyseal cartilage consist of many mononuclear diploid cells, a few mononuclear tetraploid cells and of some fraction of the cells having intermediate DNA values between the diploid and tetraploid levels. Those cells with intermediate DNA values, after autoradiographic studies, were found to correspond to DNA synthetic cells, indicating cell proliferative activity. It has been shown that during ageing of the rats, most of the chondrocytes from the articular cartilage are mononuclear diploid cells. The distribution of each cellular DNA content at the diploid level as determined by Feulgen-DNA cytofluorometry was shown to become gradually broader.

Aging↗
PubMed1982

Salt loading augments vascular responses to indomethacin in stroke-prone SHR.

We examined whether endogenous prostaglandins (PGs) participated in control of hindquarters vascular resistance during salt loading in stroke-prone spontaneously hypertensive rates (SHR-SP). SHR-SP and Wistar-Kyoto rats (WKY) were fed either a normal (0.3% NaCl) or high (8% NaCl) salt diet for 5 wk. High salt increased blood pressure and hindquarter vascular resistance (VR) in SHR-SP (P less than 0.01) but not in WKY. Indomethacin given intravenously increased hindquarter VR in SHR-SP during high salt as well as during normal salt (P less than 0.01) but not in either group of WKY. In SHR-SP the increase in hindquarter VR by PG synthesis inhibitors were two times greater during high salt than during normal salt (P less than 0.01). In addition, hindquarter vasodilatation by bradykinin was greater (P less than 0.05) in SHR-SP during high salt than that during normal salt, but vasodilatation by prostaglandin E1 or nitroglycerin was not different between the two groups. These results suggest that vascular synthesis of endogenous PGs was greater in SHR-SP during high salt than that during normal salt. Increased endogenous PGs may play an important role in the regulation of hindquarter VR during high salt intake in SHR-SP.

Alprostadil↗
PubMed1982

Limited maximal vasodilator capacity of forearm resistance vessels in normotensive young men with a familial predisposition to hypertension.

The study was performed to determine whether there is a structural vascular abnormality in normotensive subjects with hypertensive relatives. We examined maximal vasodilator capacity of forearm resistance vessels in 23 normotensive young men (mean blood pressure 94 +/- 0.4 mm Hg, mean +/- SE) with hypertensive relatives (age 24 +/- 0.1 years) and in 17 normotensive subjects (mean blood pressure 85 +/- 0.4 mm Hg) with no family history of hypertension (age 24 +/- 0.1 years). Maximal vasodilator capacity was examined by measuring minimal vascular resistance during peak reactive hyperemia after release from 10 minutes of arterial occlusion. Minimal forearm vascular resistance after release from 10 minutes of arterial occlusion was 25% higher (P less than 0.02) in subjects with hypertensive relatives (2.0 +/- 0.02 units) than that in subjects with no family history (1.5 +/- 0.01) units. We confirmed the previous findings that increasing metabolic vasodilator stimulus by performing intermittent handgrip exercise during 10 minutes of arterial occlusion did not augment peak dilation. This suggests that 10 minutes of arterial occlusion produced maximal vasodilation. Forearm vascular responses to ice on the forehead was greater in subjects with hypertensive relatives than those in subjects with no family history. These results suggest that there may be a structural abnormality in the forearm resistance vessels in normotensive subjects with family history of hypertension.

Adult↗