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Biomedical subjects

T Ishimitsu

Publications and source records attributed to T Ishimitsu.

At least 91 records · Page 5Linked to original sources
PubMed1993

[Efficacy and safety of long-term erythropoietin therapy in chronic hemodialysis patients with renal anemia].

In order to examine the efficacy and safety of long-term erythropoietin (rHuEPO) therapy, 103 hemodialysis patients were treated with rHuEPO for their renal anemia and the effects were observed for 1 year. Within 3 or 4 months after starting the rHuEPO therapy, the hematocrit (Ht) value rose up to nearly 30% and the level was maintained thereafter by approximately 4500 IU per week of rHuEPO. Tachyphylaxis did not occur even after 1 year of rHuEPO treatment. Symptoms such as headache, dizziness or palpitation were markedly reduced with the improvement of anemia. Although blood pressure was modestly elevated (systolic by 9 mmHg, p < 0.01 and diastolic by 5 mmHg, p < 0.01 at 6-month-stage), only 1 patient was forced to stop the therapy. Moreover, the blood pressure was successfully controlled to the original level after 11 months. This blood pressure elevation was not related to the increase of Ht level nor the dose of rHuEPO. Serum protein, lipid, electrolytes and liver enzymes did not change during 1 year of rHuEPO therapy. These results indicate that rHuEPO treatment is effective and innocuous as a long-term therapy of renal anemia in hemodialysis patients.

Anemia↗
PubMed1993

The role of eosinophils in interleukin-2/lymphokine-activated killer cell therapy.

When interleukin-2 alone or in combination with lymphokine-activated killer (LAK) cells is administered to patients with cancer, peripheral or local eosinophilia is frequently seen. To evaluate the role of eosinophils in this setting, we studied the functional changes of human eosinophils induced by the supernatant of LAK cell cultures. The chemotactic activity, change in chemiluminescence, superoxide production, expression of leukocyte integrins (CD11/CD18 family), and adherent activity to plastic dishes were investigated after stimulation of eosinophils with LAK cell culture supernatant. The chemotactic activity of eosinophils in the supernatant of LAK cell cultures was increased significantly, and this activity was chemotactic rather than chemokinetic by checkerboard analysis. Both chemiluminescence and superoxide production of stimulated eosinophils increased significantly compared with resting. In addition, eosinophil-adherent activity to plastic dishes was also increased. Among leukocyte integrins, CD11b expression on stimulated eosinophils increased. Moreover, eosinophil antibody-dependent cellular cytotoxicity against Raji cells was enhanced after stimulation with the supernatant of LAK cell cultures. These results suggest that the eosinophils activated by LAK cells may play an important role in the antitumor effect of interleukin-2/LAK cell therapy.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1993

[The role of eosinophil chemotactic factor in localized tissue eosinophilia by parasitic infection].

Eosinophil chemotactic factors (ECFs) are thought to play an important role in the recruitment of eosinophils to parasitic inflammatory regions. ECF-A derived from mast cells, lymphokines from lymphocytes and ECFs from complements are well known as host-derived ECFs. On the other hand, ECF from parasites (ECF-P) and cytokines such as ESP (eosinophil stimulation promoter) and interleukin-5 are reported to be responsible for the eosinophil accumulation in parasitic inflammatory regions. In a series of our experiments using Anisakis larvae, we discovered a mechanism of eosinophil recruitment which could be accelerated by priming with ECF-P in parasite infected eosinophil phlegmon.

Animals↗
PubMed1992

The increase of low density subpopulations and CD10 (CALLA) negative neutrophils in severely infected patients.

We investigated the changes in polymorphonuclear leukocyte (PMN) subpopulations that accompany severe bacterial infection and examined their usefulness as a parameter for assessing the severity of infection. The Percoll density gradient was used to fractionate neutrophils into subpopulations of high density (1.09-1.10), intermediate density (1.08-1.09), and low density (1.07-1.08) with the majority of neutrophils from normal volunteers being of high density. By contrast, neutrophils from infected patients were of intermediate or low density, while those from severely infected patients showed a high percentage of the low density fraction with functional changes in lower chemotactic and beta-gulcuronidase activity. When each density subpopulation in the normal blood neutrophils was tested, low density PMNs had the lowest chemotaxis and minimal beta-glucuronidase activity. These results indicate that the increase in low density PMNs in patients with severe infection clearly reflects the functional impairment of PMNs. Flow cytometric analysis demonstrated that the neutrophils from severely infected patients had an decrease in CD10 expression. The percentage of CD10 positive PMNs correlated well with the severity of infection and with the clinical course of the patients. Thus, we conclude that PMN-density and CD10 expression change during severe bacterial infection, and that the measurement of PMN-subpopulations may be used to complement the clinical assessment of the severity of infections.

Bacterial Infections↗
PubMed1992

Abnormal response of urinary eicosanoid system to norepinephrine infusion in patients with essential hypertension.

To define the role of the renal eicosanoid system in sustaining renal homeostasis in hypertension, we investigated the alterations in urinary excretions of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), a stable metabolite of vasodepressor prostacyclin, and thromboxane B2 (TXB2), a stable metabolite of vasoconstrictor TXA2, when norepinephrine was continuously infused for 90 min in hypertensive (n = 13) and normotensive subjects (n = 14). There was no difference in plasma norepinephrine concentration after the infusion between the hypertensive and the normotensive subjects. Moreover, the percent changes in renal vascular resistance elicited by norepinephrine in the hypertensives were equal to those of the normotensive subjects. In the normotensive subjects, the norepinephrine infusion significantly increased urinary 6-keto-PGF1 alpha excretion and decreased urinary excretion of TX, both of which are beneficial for sustaining renal function. In fact, the greater the production of renal 6-keto-PGF1 alpha was, the less the reduction of renal blood flow and urinary sodium excretion was. In the hypertensive subjects, however, these normal responses of the renal eicosanoid system, seen in the normotensives, were abolished; urinary 6-keto-PGF1 alpha was unaltered and thromboxane generation was rather increased. Thus, the renal eicosanoid system dysfunctions in hypertensive subjects when the renal circulation is challenged by norepinephrine. These abnormal responses are likely to cause sodium retention and could contribute, in part, to the hypertensive mechanism in patients with essential hypertension.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

In vivo and in vitro effects of atrial natriuretic peptide on renin release.

1. This study investigated the effect of atrial natriuretic peptide on renin release from the kidney. The in vitro direct effect was examined in the animal experiment using renal cortical slices of rat, and the in vivo effect was observed in the human infusion study. 2. In the in vitro experiments, alpha-human atrial natriuretic peptide (alpha-hANP) ranging 10(-9) to 10(-6) mol/L did not change the basal renin release rate from the renal cortical slices (-9% at 10(-6) mol/L, NS). Isoproterenol (10(-6) mol/L) increased renin release by 40% (P < 0.001), whereas angiotensin II (10(-6) mol/L) suppressed it by 48% (P < 0.001). However, alpha-hANP did not affect the stimulative effect of isoproterenol or the inhibitory effect of angiotensin II. 3. Also in the human study, infusion of 25 ng/kg per min alpha-hANP failed to change the plasma renin activity in normotensive subjects (-4%) or patients with essential hypertension (+5%), or even in patients with raised renin levels such as renovascular hypertension (+10%) or congestive heart failure (-13%). 4. These results put forth negative views on the direct involvement of atrial natriuretic peptide in renin release from the juxtaglomerular apparatus.

Adult↗
PubMed1992

Regulatory effect of thromboxane A2 on proliferation of vascular smooth muscle cells from rats.

We investigated the regulatory effects of the vasoconstrictor thromboxane A2 on the proliferation of vascular smooth muscle cells (VSMC) from Wistar-Kyoto rats using 9,11-epithio-11,12-methano-thromboxane A2 (STA2), a stable analogue of thromboxane A2. STA2 dose dependently increased incorporation of [3H]thymidine into DNA in randomly cycling VSMC and significantly shortened the doubling time. Cell cycle analysis revealed that the increased cell cycle progression was primarily due to a rapid transition from the DNA synthetic (S) to the G2/mitotic (M) phase. Moreover, STA2 enhanced protein synthesis in VSMC during the G2/M phase, whereas the protein synthesis was unaffected in the G0/G1 period. In fact, STA2 prompted the cells in G2/M phase to synthesize actin, a major cytoskeleton protein. Conversely, inhibition of protein synthesis by puromycin retarded the transition from S to G2/M. In addition, depolymerization of the actin molecules by cytochalasin D offset the quick progression to the G2/M phase by STA2. These data indicate that thromboxane A2 stimulates the cell cycle progression in VSMC primarily through a rapid transition from S to G2/M. This enhanced progression is attributable partly to a rapid buildup of the cytoskeleton proteins during the G2/M period.

Animals↗
PubMed1992

High potassium diets greatly increase growth-inhibiting agents in aortas of hypertensive rats.

High potassium diets greatly reduce intimal and medial thickening in stroke-prone spontaneously hypertensive rats (SHRSP). In vascular smooth muscle cells, transforming growth factor-beta (TGF-beta) inhibits proliferation. To test whether high potassium diets decrease aortic thickening through TGF-beta, we measured TGF-beta-like activity in medium bathing aortas from rats fed either normal potassium or high potassium diets. Five-week-old SHRSP were fed 6% high NaCl diets containing either normal (0.5%) potassium (11 rats) or high (2.1%) potassium (14 rats) for 7 weeks. Aortas were freshly excised and perfused for 3 hours with tissue culture medium at ordinary arterial pressures. TGF-beta-like activity in the acid-activated perfusing medium was assessed using the growth inhibitory action on mink lung cells. Growth inhibition was assessed by [3H]thymidine incorporation. In the medium perfusing the outside of the aorta, the growth inhibitory rates were 2.5 times higher in high potassium SHRSP than in normal potassium SHRSP (-49% versus -20%, p less than 0.03). Antibodies to TGF-beta 1 and TGF-beta 2 were added to other aliquots and did not alter the results whatsoever. Thus, the difference in growth inhibition was not due to differences in TGF-beta. The high potassium aortas released 2.5 times more growth-inhibiting agents than the normal potassium aortas. The same pattern of growth inhibition was also seen using vascular smooth muscle cells rather than mink lung cells (r = +0.818, p less than 0.001, n = 13). The increased growth inhibition of high potassium aortas was not due to an increased release of heparin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Interferon gamma attenuates hypertensive renal injury in salt-sensitive Dahl rats.

Evidence has been provided that the immunological mechanism is involved in the genesis or maintenance of hypertension. In the present study, we investigated the effects of interferon gamma, a potent immunomodulator derived from lymphocytes, on hypertension and organ damage in Dahl salt-sensitive rats and in spontaneously hypertensive rats. Subcutaneous injection of interferon gamma (5 x 10(4) units/kg body wt once a week for 10 weeks) reduced blood pressure in Dahl salt-sensitive rats fed a 4% high salt diet (174 versus 194 mm Hg, p less than 0.025). This blood pressure reduction was associated with an improvement of renal functions, an increase in glomerular filtration rate (690 versus 569 ml/day/100 g body wt, p less than 0.05), and decreases in urinary protein excretion (48 versus 78 mg/day/100 g body wt, p less than 0.025) and urinary N-acetyl-beta-D-glucosaminidase excretion (143 versus 183 milliunits/day/100 g body wt, p less than 0.05). Morphological investigation showed a marked resolution of the vascular injuries seen in untreated Dahl salt-sensitive rats, e.g., intimal and medial hyperplasia, with infiltration of inflammatory cells, and significant amelioration of the glomerular sclerotic changes. In contrast, interferon gamma affected neither blood pressure nor renal functions in spontaneously hypertensive rats. These data indicate that interferon gamma ameliorates the development of hypertension and vascular and renal injuries in Dahl salt-sensitive rats. The resolution of vascular and renal injuries contributes, in part, to the antihypertensive action of interferon gamma.

Acetylglucosaminidase↗
PubMed1992

Left atrial function in ischemic heart disease assessed by intravenous digital subtraction angiography.

To investigate changes in left atrial morphology and dimensions during the cardiac cycle, the atrium was visualized by intravenous digital subtraction angiography (DSA). The study subjects consisted of 22 male patients whose average age was 54.5 +/- 8.6 years. They had ischemic heart disease without mitral valve disease and were in sinus rhythm. They were 11 patients with old myocardial infarction (OMI group) and 11 who had chest pain without evidence of infarction (AP group). DSA was performed in the continuous mode. Contrast material (35 ml) was injected at a rate of 18 ml/sec via a catheter in the superior vena cava and subtraction images were obtained at a speed of 30 frames/sec in the right anterior oblique projection. The left atrial and left ventricular margins were traced manually, their areas were calculated, and fractional changes in area were analyzed. The left ventricular ejection fraction (LVEF) was calculated by densitometry. Cardiac catheterization was performed in 16 patients and the left ventricular end-diastolic pressure (LVEDP) and mean pulmonary arterial wedge pressure (PAWP) were measured. The entire left atrium was clearly imaged using DSA. Phase analysis of the time-area curves in the right anterior oblique projection revealed that the left atrial area was maximal during left ventricular end-systole (%LA1 = 100%), it decreased during early left ventricular diastole (%LA2), and then increased slightly again during mid-diastole (%LA3). After left atrial contraction, the minimum area was obtained (%LA4). The left atrium showed a two-stage decrease in the area due to passive emptying and active contraction during left ventricular diastole. Passive emptying (%LA1-%LA2) was significantly less in the OMI group than in the AP group (6.3 +/- 3.6 vs 13.3 +/- 4.8%, p < 0.01, respectively). In all 22 subjects, passive emptying correlated with LVEF (r = 0.70, p < 0.001) and LVEDP (r = -0.58, p < 0.05). There was no difference in active contraction (%LA3-%LA4) between the 2 groups (26.0 +/- 5.7% in the OMI group, 28.2 +/- 8.4% in the AP group), and it did not correlate with LVEF or LVEDP. The ratio of passive emptying to active contraction [(%LA1-%LA2)/(%LA3-%LA4)] correlated with LVEF (r = 0.63, p < 0.01). These findings suggested that impaired left ventricular diastolic function and a relative increase in atrial contraction were present in patients with a lower LVEF. The %LA4 correlated with LVEDP and PAWP (r = 0.65, r = 0.63, p < 0.01, respectively). In conclusion, DSA proved to be a useful method for investigating left atrial morphology and function.

Aged↗
PubMed1991

Vascular eicosanoid production in experimental hypertensive rats with different mechanisms.

This study investigated the release of prostacyclin (PGI2) and thromboxane A2 (TXA2) from the aortic walls of various experimental hypertensive rats, e.g. spontaneously hypertensive rats (SHR), Dahl salt-sensitive (Dahl S) rats, deoxycorticosterone (DOCA)-salt hypertensive rats and renovascular (2-kidney, 1-clip (2K1C) and 1-kidney, 1-clip (1K1C] hypertensive rats. The PGI2 generation was increased significantly in these hypertensive models, irrespective of the hypertensive mechanisms, when they developed established hypertension. Dahl S rats, having an impaired PGI2 production on a low salt diet, restored PGI2 generating capacity to the control level of Dahl salt-resistant rats when they were fed a high salt diet and developed salt-induced hypertension. On the other hand, the TXA2 generation in the vascular walls was enhanced particularly in rat models for genetic hypertension, and this system was unaltered in the models for secondary hypertension, e.g. DOCA-salt and renovascular hypertension. Thus, it is suggested that the elevation of blood pressure is associated with an increase in vascular PGI2 production, and that the increased vascular TXA2 production is a characteristic feature of genetic hypertension.

Animals↗
PubMed1991

Rapid smooth muscle cell growth and endogenous prostaglandin system in spontaneously hypertensive rats.

Vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR) exhibit rapid cell growth. In this study, to reveal the mechanisms of the quick VSMC growth, we analyzed the alterations in the respective periods of the proliferating cell cycle, and investigated the role of the endogenous prostaglandin system in this rapid cell growth. The VSMC from SHR showed increased [3H]thymidine uptake and shortened doubling time, compared with Wistar-Kyoto rats (WKY). These properties were mainly due to both shortened transition time from G0/G1 to S and shortened G2 duration. There was a difference neither in the DNA-replication rate nor in the mitotic period. Generating capacity for vasodepressor prostaglandins was significantly reduced in the VSMC from SHR, particularly in the G0/G1 period. When the endogenous prostaglandin synthesis was inhibited by 10(-5) mol/L indomethacin, the transition from G0/G1 to S was shortened. This alteration was eliminated by supplementation with OP41483, a stable prostacyclin analog. In contrast, the alteration in the G2 duration was unaffected by indomethacin. These data indicate that the rapid VSMC growth in SHR is mainly due to the shortening of both the G0/G1 and G2 period, and that the impaired prostaglandin system is responsible, at least in part, for the shortened G0/G1 duration.

Animals↗
PubMed1991

Possible role of prostacyclin synthase in altered prostacyclin generation in DOCA-salt hypertensive rats.

Prostacyclin (PGI2) synthase is one of the key enzymes for vasodepressor PGI2 biosynthesis in the vascular wall. In this study, we attempted to define the alterations in PGI2 synthase and its role in the PGI2 generation in the vascular wall of deoxycorticosterone acetate (DOCA)-salt rats. The PGI2-generating capacity was enhanced significantly when DOCA-salt rats established hypertension, whereas the generation of other arachidonate metabolites, eg, PGE2, PGF2 alpha, and thromboxane, was unaltered. Moreover, the increase in PGI2 generation was associated with an increase in PGI2 synthase activity in the vascular wall. Indeed, the averaged PGI2 generating capacity was closely correlated to the averaged PGI2 synthase activity in DOCA-salt hypertensive rats and three lines of control rats. Incontrast, phospholipase C and phospholipase A2, both of which liberate arachidonate for PGI2 synthesis, were rather lowered in DOCA-salt hypertensive rats. These data clearly indicate that vascular PGI2 generation is increased in the development of DOCA-salt hypertension and that PGI2 synthase is mainly responsible for this enhancement. The increased PGI2 synthase may be relevant to the blood pressure elevation and is expected to have beneficial effects on the vascular protection in hypertension.

Animals↗
PubMed1991

Antiproliferative effects of the serotonin type 2 receptor antagonist, ketanserin, on smooth muscle cell growth in rats.

We defined the role of a serotonin type 2 receptor antagonist, ketanserin, in the growth of aortic vascular smooth muscle cells (VSMCs) from Wistar rats, using cell culture and cell synchrony methods. Deoxyribonucleic acid (DNA) replication in the G0/G1- or G1/S-synchronized VSMCs was assessed by [3H]thymidine uptake into DNA. Ketanserin at 2 x 10(-5) M significantly decreased the thymidine uptake by 48% in the proliferating VSMCs, whereas methysergide, a nonspecific serotonin inhibitor, unaffected the thymidine uptake. Ketanserin at 10(-5) M did not influence the duration of the G1 resting period. However, this dose of ketanserin significantly lowered DNA replication in the DNA synthetic (S) period in a dose-dependent manner. Neither methysergide nor the alpha 1-adrenoceptor antagonist, prazosin, affected DNA synthesis in the S period. Ketanserin exhibits antiproliferative effects on rat VSMC growth probably through the suppression of DNA replication in the S phase. This property would also contribute to the vascular protective effects of ketanserin with its well-documented antihypertensive action.

Animals↗
PubMed1991

Atrial natriuretic peptide inhibits the aldosterone response to metoclopramide in patients with glomerular disease and essential hypertension.

1. We examined the effects of metoclopramide (MCP: 10 mg i.v.) on plasma atrial natriuretic peptide (ANP) and aldosterone concentrations (PAC) and the effect of ANP on MCP-induced PAC in four patients with primary glomerular diseases and seven patients with essential hypertension. 2. MCP injection caused no significant changes in plasma ANP. MCP produced a marked increase in PAC without a significant change in plasma renin activity. 3. The increase in PAC induced by MCP injection was markedly attenuated when preceded by the infusion of ANP (25 ng/kg per min). 4. These results suggest that the dopaminergic D2 mechanism is not involved in the regulation of ANP secretion and that ANP modulates the dopaminergic regulation of aldosterone secretion.

Adult↗
PubMed1991

[Mitral regurgitation due to redundant chordae].

This paper reports the etiology and the findings of phonocardiograms and echocardiograms in four cases with mitral regurgitation caused by the redundant chordae. Redundancy of the chordae were determined by the surgeon during operation. The results were as follows: 1. The etiology of redundant chordae was either congenital, rheumatic, or mucoid degeneration. 2. Phonocardiographic findings of this condition are a holosystolic murmur accompanied by a diastolic rumble at the apex. 3. Two-dimensional echocardiogram shows holosystolic bulging of the mitral leaflet to which redundant chordae are attached. 4. The findings of the M-mode echocardiogram are multiple linear echoes and bowing of the mitral valve in systole.

Adult↗
PubMed1990

Significant prolongation of disease-free period gained by oral polysaccharide K (PSK) administration after curative surgical operation of colorectal cancer.

To examine the clinical efficacy and the mechanism of action of polysaccharide K (PSK), a protein-bound polysaccharide extracted from a Basidiomycetes fungus, a randomized double-blind trial was performed by administering PSK to 56 patients and a placebo to another group of 55 patients after surgical operations on their colorectal cancers. The rate of patients in remission (or disease-free) was significantly higher in the PSK group than in the placebo group; the difference between both groups was statistically significant at P less than 0.05 by the log-rank test. The survival rate of patients was also significantly (P less than 0.05) higher in the PSK group than in the control group. The most significant laboratory finding was that polymorphonuclear leukocytes from PSK-treated patients showed remarkable enhancement in their activities, such as random and/or chemotactic locomotion, and phagocytic activity, when compared with those in the control group. In conclusion, PSK was useful as a maintenance therapy for patients after their curative surgical operations for colorectal cancer. The beneficial effects were probably due to the activation of leukocyte functions as one of the many biological-response-modifying (activities induced by PSK).

Administration, Oral↗