Biomedical subjects

I Tabata

Publications and source records attributed to I Tabata.

At least 37 records · Page 2Linked to original sources

PubMed1996

Neuroendocrine differentiation in pancreatic duct carcinoma special emphasis on duct-endocrine cell carcinoma of the pancreas.

To evaluate the significance of neuroendocrine differentiation in duct carcinoma of the pancreas, we investigated 79 pancreatic carcinomas, applying histochemistry and immunohistochemistry (chromogranin A, Leu-7, synaptophysin and neuron-specific enolase (NSE), and correlated the morphologic differentiation pattern with clinicopathological characteristics. There were two types of neuroendocrine differentiation: scattered (n = 23) and diffuse (n = 3). The scattered type of pancreatic duct carcinoma contained scattered endocrine cells amounting to less than 10% of the neoplastic cells and was seen more frequently in well-differentiated carcinomas. There was no characteristic clinical feature found in the scattered type when compared with the tumors devoid of endocrine cells (n = 53). In contrast, the diffuse type showed diffuse immunostaining with NSE and synaptophysin in tumor cells and dense core granules ultrastructurally. These tumors showed a greater hypervascularity in angiography (p < 0.01) and the patients had relatively longer survival (33.3 months, p < 0.05) than unresectable cases of other histological types of pancreatic cancer. Two types of neuroendocrine differentiation (scattered and diffuse) existed in pancreatic ductal carcinoma. The diffuse type (Duct-Endocrine Cell Carcinoma of the Pancreas) showed synchronous duct and endocrine differentiation and particular clinical features.

Adenocarcinoma↗

PubMed1996

Anaerobic capacity and maximal oxygen uptake during arm stroke, leg kicking and whole body swimming.

In the present study, we determined both anaerobic capacity (the maximal accumulated oxygen deficit) and maximal oxygen uptake (VO2max) during arm stroke (A), leg kicking (K), and whole body swimming (S), and compared them. The subjects were six trained college swimmers (two male and four female), aged 20 +/- 1 years. To determine VO2max for A, K and S, VO2max was measured during a 6-min swim at constant water flow rates. VO2 was measured by the Douglas bag method. Anaerobic capacity was determined by accumulated oxygen deficit during exercise lasting 2-3 min according to the methods of Medbø et al. Mean values of VO2max during A, K and S were 2.53 +/- 0.37 L min-1, 2.93 +/- 0.37 L min-1, and 3.23 +/- 0.43 L min-1, respectively. Those in A and K corresponded to 78.2% and 91.0% of that in S. Mean values of anaerobic capacity during A, K and S were 2.15 +/- 0.31 L, 2.52 +/- 1.08 L and 2.99 +/- 0.52 L, respectively. Those in A and K corresponded to 73.3% and 81.7% of that in S. Both VO2max and anaerobic capacity in S were much lower than the sum of A and K, corresponding to only 59.3% and 65.9%, respectively. These results suggest that the total energy production during S is lower than simply the sum of A and K because the potentials of both the anaerobic and aerobic energy releasing processes in the muscle groups involved in A and K cannot be fully reached during S.

Adult↗

PubMed1996

Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max.

This study consists of two training experiments using a mechanically braked cycle ergometer. First, the effect of 6 wk of moderate-intensity endurance training (intensity: 70% of maximal oxygen uptake (VO2max), 60 min.d-1, 5 d.wk-1) on the anaerobic capacity (the maximal accumulated oxygen deficit) and VO2max was evaluated. After the training, the anaerobic capacity did not increase significantly (P > 0.10), while VO2max increased from 53 +/- 5 ml.kg-1 min-1 to 58 +/- 3 ml.kg-1.min-1 (P < 0.01) (mean +/- SD). Second, to quantify the effect of high-intensity intermittent training on energy release, seven subjects performed an intermittent training exercise 5 d.wk-1 for 6 wk. The exhaustive intermittent training consisted of seven to eight sets of 20-s exercise at an intensity of about 170% of VO2max with a 10-s rest between each bout. After the training period, VO2max increased by 7 ml.kg-1.min-1, while the anaerobic capacity increased by 28%. In conclusion, this study showed that moderate-intensity aerobic training that improves the maximal aerobic power does not change anaerobic capacity and that adequate high-intensity intermittent training may improve both anaerobic and aerobic energy supplying systems significantly, probably through imposing intensive stimuli on both systems.

Adult↗

PubMed1995

Annular pancreas associated with carcinoma in the dorsal part of pancreas divisum.

A carcinoma in the dorsal part of the pancreas divisum with an annular pancreas in the anterior part is reported. A 79-yr-old female was admitted in our hospital complaining of epigastralgia. Computed tomography (CT) and ultrasound (US) showed an irregular mass in the pancreatic body. A pancreatogram obtained through the major duodenal papilla demonstrated only the ventral pancreatic duct that encircled the duodenum. Contrast medium injected from the minor duodenal papilla showed Santorini's duct obstruction at the neck portion of the pancreas without communication with the ventral pancreatic duct. The patient died with liver metastases. Autopsy confirmed annular pancreas and a 6-cm tumor in the pancreatic body extending to the pancreatic head and pancreas divisum. Pancreatic carcinoma; histologically a moderately differentiated adenocarcinoma; originated from the dorsal part of pancreas divisum. To our knowledge this is the first report of pancreatic carcinoma associated with annular pancreas coexistent with pancreas divisum.

Adenocarcinoma↗

PubMed1995

A case of pleomorphic carcinoma of the pancreas showing sequential histological change by immunohistochemical study.

Pleomorphic carcinoma of the pancreas is a rare, histologically characterized pancreatic tumor with a rapid and fatal course. We report a case of a resected pleomorphic carcinoma located in the body of the pancreas in a 61-yr-old male. Histological analysis of the resected specimen revealed the coexistence of pleomorphic carcinoma with adenocarcinoma, but the recurrent tumors at autopsy 20 mo later were only of the adenocarcinomatous type. Cells in the adenocarcinomatous component showed a diffuse reactivity for CA19-9, CEA, and cytokeratin, and a focal reactivity for vimentin. In contrast, vimentin was diffusely expressed in pleomorphic lesion. Adenocarcinoma at autopsy expressed CA19-9, CEA, and cytokeratin, but not vimentin. These findings suggest that the recurrent adenocarcinoma may have developed as a consequence of sequential change in the nature of the tumor.

CA-19-9 Antigen↗

PubMed1994

Non-insulin and non-exercise related increase of glucose utilization in rats and mice.

The effects of high-energy phosphate contents in muscles on glucose tolerance and glucose uptake into tissues were studied in rats and mice. Enhanced glucose tolerance associated with depleted high-energy phosphates and elevated glycogen content in muscles and liver was observed in animals fed creatine analogue beta-guanidinopropionic acid (beta-GPA). Distribution of infused 2-[1-14C]deoxy-D-glucose in tissues especially in the soleus muscle, kidney, and brain was greater in mice fed beta-GPA than controls. The glucose uptake was decreased when the contents of ATP and glycogen were normalized following creatine supplementation. Plasma insulin in animals at rest was lower and its concentration after intraperitoneal glucose infusion tended to be less in animals fed beta-GPA than controls (p > 0.05), although the pattern of insulin response to glucose loading was similar to the control. The daily voluntary activity in beta-GPA fed mice was also less than controls. These results suggest that improved glucose tolerance is not related to elevated insulin concentration and/or decreased glycogen following exercise. Such improvement may be due to an increased mitochondrial energy metabolism caused by depletion of high-energy phosphates.

Animals↗

PubMed1994

Lithium increases susceptibility of muscle glucose transport to stimulation by various agents.

Lithium is thought to have an insulin-like effect on glucose transport and metabolism in skeletal muscle and adipocytes. However, we found that lithium had only a minimal effect on basal glucose transport activity in rat epitrochlearis muscles. Instead, lithium markedly increased the sensitivity of glucose transport to insulin, so that the increase in glucose transport activity induced by 300 pM insulin was approximately 2.5-fold greater in the presence of lithium than in its absence. Lithium also caused a modest increase in insulin responsiveness. This enhancement of the susceptibility of the glucose transport process to stimulation was not limited to insulin, because lithium induced increases in the susceptibility of glucose transport to stimulation by contractile activity, hypoxia, a phorbol ester, and phospholipase C. Lithium also blunted the activation of glycogen phosphorylase by epinephrine. These effects were not mediated by inhibition of adenylate cyclase, because neither basal- nor epinephrine-stimulated muscle cAMP concentration was affected by lithium treatment. The effects of lithium on glucose transport and metabolism in skeletal muscle are strikingly similar to the persistent effects of exercise. These results support the possibility that lithium might be useful in the treatment of insulin resistance in patients with non-insulin-dependent diabetes mellitus.

3-O-Methylglucose↗

PubMed1993

Effect of hand paddle aids on oxygen uptake during arm-stroke-only swimming.

Cardiorespiratory responses during arm-stroke-only swimming with and without the aid of paddle were compared in seven trained swimmers. Water flow rate was started at 0.80 m.s-1 and was increased by 0.05 m.s-1 every 2 min up. to 1.00 m.s-1. Subsequently, the flow rate was increased by 0.05 m.s-1 every minute until exhaustion. At given submaximal water flow rates, oxygen uptake, heart rate (fc), pulmonary ventilation (VE) and respiratory frequency (fR) during swimming using hands alone (H) were significantly higher than when aided by paddles (P). There were no significant differences in tidal volume (VT) between H and P. The subjects were able to swim significantly faster using paddles (P < 0.05); however, no significant differences between H and P were found in peak oxygen uptake (VO2peak, Fc, VE, FR, VT and the blood lactate concentration at which VO2peak was obtained (P > 0.05). These results would suggest that the ability to swim faster with paddles does not depend on higher energy production but may be attributed to higher propelling efficiency.

Adult↗

PubMed1993

Anaerobic energy release in working muscle during 30 s to 3 min of exhausting bicycling.

To examine the anaerobic energy release during intense exercise, 16 healthy young men cycled as long as possible at constant powers chosen to exhaust the subjects in approximately 30 s, 1 min, or 2-3 min. Muscle biopsies were taken before and approximately 10 s after exercise and analyzed for lactate, phosphocreatine (PCr), and other metabolites. O2 uptake was measured for determination of the accumulated O2 deficit (a whole body measure of the anaerobic energy release), and this indirect measure of the anaerobic energy release was compared with a direct value obtained from measured muscle metabolites. Muscle lactate concentration rose by 30.0 +/- 1.2 mmol/kg and muscle PCr concentration fell by 12.4 +/- 0.9 mmol/kg during the 2-3 min of exhausting exercise. The anaerobic ATP production was consequently 58 +/- 2 mmol/kg wet muscle mass, which may be the maximum anaerobic energy release for human muscle during bicycling. Because the anaerobic ATP production was 6 and 32% less for 1 min and 30 s of exercise, respectively, than for 2 min of exercise (P < 0.03), 2 min of exhausting exercise may be required for maximal use of anaerobic sources. Lactate production provided three times more ATP than PCr breakdown for all three exercise durations. There was a close linear relationship between the rates of anaerobic ATP production in muscle and the value estimated for the whole body by the O2 deficit (r = 0.94). This suggests that the accumulated O2 deficit is a valid measure of the anaerobic energy release during bicycling.

Adenosine Triphosphate↗

PubMed1992

Oxygen uptake during swimming in a hypobaric hypoxic environment.

The purpose of this study was to determine oxygen uptake (VO2) at various water flow rates and maximal oxygen uptake (VO2max) during swimming in a hypobaric hypoxic environment. Seven trained swimmers swam in normal [N; 751 mmHg (100.1 kPa)] and hypobaric hypoxic [H; 601 mmHg (80.27 kPa)] environments in a chamber where atmospheric pressure could be regulated. Water flow rate started at 0.80 m.s-1 and was increased by 0.05 m.s-1 every 2 min up to 1.00 m.s-1 and then by 0.05 m.s-1 every minute until exhaustion. At submaximal water flow rates, carbon dioxide production (VCO2), pulmonary ventilation (VE) and tidal volume (VT) were significantly greater in H than in N. There were no significant differences in the response of submaximal VO2, heart rate (fc) or respiratory frequency (fR) between N and H. Maximal VE, fR, VT, fc, blood lactate concentration and water flow rate were not significantly different between N and H. However, VO2max under H [3.65 (SD 0.11) l.min-1] was significantly lower by 12.0% (SD 3.4)% than that in N [4.15 (SD 0.18) l.min-1]. This decrease agrees well with previous investigations that have studied centrally limited exercise, such as running and cycling, under similar levels of hypoxia.

Adult↗

PubMed1992

Glycogen breakdown in different human muscle fibre types during exhaustive exercise of short duration.

The rates of glycogen breakdown during exhaustive intense exercise of three different intensities were determined in type I and subgroups of type II fibres. The exercise intensity corresponded to 122 +/- 2, 150 +/- 7 and 194 +/- 7% of VO2max. Muscle biopsies were taken from both legs before and immediately after exhaustion. Muscle lactate concentration increased by 27 +/- 1, 27 +/- 1 and 20 +/- 2 mmol kg-1 wet wt during the exercise at 122, 150 and 194% VO2max, respectively. The rates of glycogen depletion increased in all fibre types with increasing intensity, and the decline in type I fibres was 30-35% less than in type II fibres at all intensities. No differences were observed between the glycogen depletion rates in subgroups of type II fibres (IIA, IIAB and IIB). During the exercise at 194% VO2max, the rates of glycogen breakdown were 0.35 +/- 0.03 and 0.52 +/- 0.05 mmol s-1 kg-1 wet wt in type I and type II fibres, respectively. For both fibre types, the rates were 32 and 69% lower during the exercise at 150 and 122% VO2max. These data indicate that the glycolytic capacity of type I fibres is 30-35% lower than the capacity of type II fibres, in good agreement with the differences in phosphorylase and phosphofructokinase activities (Essén et al. 1975, Harris et al. 1976). The data also indicate that both fibre types contribute significantly to the anaerobic energy release at powers up till almost 200% VO2max.

Adult↗

PubMed1992

Relationship between arterial oxygen desaturation and ventilation during maximal exercise.

The purpose of the present study was to investigate the contribution of ventilation to arterial O2 desaturation during maximal exercise. Nine untrained subjects and 22 trained long-distance runners [age 18-36 yr, maximal O2 uptake (VO2max) 48-74 ml.min-1 x kg-1] volunteered to participate in the study. The subjects performed an incremental exhaustive cycle ergometry test at 70 rpm of pedaling frequency, during which arterial O2 saturation (SaO2) and ventilatory data were collected every minute. SaO2 was estimated with a pulse oximeter. A significant positive correlation was found between SaO2 and end-tidal PO2 (PETO2; r = 0.72, r2 = 0.52, P < 0.001) during maximal exercise. These statistical results suggest that approximately 50% of the variability of SaO2 can be accounted for by differences in PETO2, which reflects alveolar PO2. Furthermore, PETO2 was highly correlated with the ventilatory equivalent for O2 (VE/VO2; r = 0.91, P < 0.001), which indicates that PETO2 could be the result of ventilation stimulated by maximal exercise. Finally, SaO2 was positively related to VE/VO2 during maximal exercise (r = 0.74, r2 = 0.55, P < 0.001). Therefore, one-half of the arterial O2 desaturation occurring during maximal exercise may be explained by less hyperventilation, specifically for our subjects, who demonstrated a wide range of trained states. Furthermore, we found an indirect positive correlation between SaO2 and ventilatory response to CO2 at rest (r = 0.45, P < 0.05), which was mediated by ventilation during maximal exercise. These data also suggest that ventilation is an important factor for arterial O2 desaturation during maximal exercise.

Adult↗

PubMed1992

Peak oxygen uptake during arm stroke under a hypobaric hypoxic condition.

The purpose of this study was to examine the limiting factor for swimming by measuring peak oxygen uptake (peak VO2) during front crawl (C) and arm stroke (A) under a hypobaric hypoxic condition. Seven-trained swimmers (age; 19-21 yrs, 100 m free style event; 57.2 +/- 2.5 secs) were measured twice under a normal (N) (751 mmHg) and a hypobaric hypoxic (H) (602 mmHg) condition in a chamber where atmospheric pressure was regulated. Water flow rate started at 0.80 m.sec-1 and was increased by 0.05 m.sec-1 every 2 min up to 1.00 m.sec-1. Subsequently, flow rate was increased by 0.05 m.sec-1 every minute until exhaustion. VO2 was measured with an automatic analyzer. The peak heart rate under N was not significantly different from that under H in both C (N; 190 +/- 9, H; 184 +/- 6 beats.min-1) and A (N; 180 +/- 6, H; 181 +/- 6 beats.min-1). Peak VO2 values during A (N; 3.42 +/- 0.27, H; 3.08 +/- 0.19 l.min-1) were significantly lower by 15-20% than those during C (N; 4.18 +/- 0.18, H; 3.65 +/- 0.11 l.min-1) for both N and H (p less than 0.01). Peak VO2 values under H were significantly lower than those under N during both C and A (p less than 0.01). There was no significant difference in the magnitude of decrease in peak VO2 between C (12.0 +/- 3.4%) and A (9.8 +/- 3.8%) under H. This ratio of decrease agrees with previous investigations that studied centrally limited exercise, such as running and cycling, under similar levels of hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Muscle metabolism during exercise: anaerobic threshold does not exist.

Blood lactate level begins to increase at a certain work load or oxygen consumption which is called as anaerobic threshold (AT). However, numerous studies showed that anaerobic glycolysis is not the cause of the enhanced accumulation of blood lactate during exercise. Increased lactate production is seen even in fully aerobic muscles. Some studies suggest that elevation of lactate is due to a temporary imbalance between the rates of pyruvate formation by aerobic glycolysis and pyruvate utilization in the Krebs cycle. These results clearly suggest that AT does not exist.

Anaerobic Threshold↗

PubMed1992

[Sequential MTX and 5-FU therapy of gastric cancer with systemic bone metastasis and disseminated intravascular coagulation].

UNLABELLED: Sequential therapy consisting of methotrexate (MTX) and 5-FU was performed together with the administration of heparin and FOY in 10 cases of gastric cancer with disseminated intravascular coagulation (DIC) causing systemic bone metastasis. The ages of the subjects ranged from 29 to 65 years (median: 49 years) with systemic bone metastasis and bone marrow carcinosis observed in all cases. Histological types consisted of 6 cases of poorly differentiated adenocarcinoma, 2 cases of signet-ring cell carcinoma, and one case each of mucocellular and tubular adenocarcinoma. Therapy consisted of intravenous injection of 30 mg-100 mg/m2 (one case, 20 mg) of MTX followed three hours later by intravenous injection of 600 mg/m2 of 5-FU weekly. Determination of DIC was made in accordance with the DIC diagnostic standards of the Ministry of Health and Welfare, and determination of tumor effectiveness was based on gastric cancer handling codes. RESULTS: PR was observed in 3 cases. Diffuse metastasis observed in the entire lung field disappeared in one case, while remarkable improvement was observed in systemic bone metastasis in scintigram findings for the other 2 cases. All 3 cases were able to be discharged. Reduction of DIC score and absence of pain were observed in 8 cases. Based on the above, aggressive implementation of this treatment method is suggested.

Adenocarcinoma↗

PubMed1991

Lymphoplasmacytic sclerosing pancreatitis with cholangitis: a variant of primary sclerosing cholangitis extensively involving pancreas.

Pancreatic involvement in primary sclerosing cholangitis (PSC) is an extremely rare condition, and its pathologic features are poorly documented. We report two cases of an unusual lymphoplasmacytic sclerosing inflammatory disease involving the total pancreas, common bile duct, gallbladder, and, in one patient, the lip. Two elderly men presented with waxing and waning obstructive jaundice, and exhibited radiologic and ultrasonographic findings highly suggestive of pancreatic carcinoma. Gross appearance of the pancreas showed firm and mass-like enlargement with regional lymph node swelling. Histologic findings were characterized by diffuse lymphoplasmacytic infiltration with marked interstitial fibrosis and acinar atrophy, obliterated phlebitis of the pancreatic veins, and involvement of the portal vein. Similar inflammatory processes involved the bile duct and the gallbladder. Lymphoplasmacytic sclerosing pancreatitis with cholangitis is thought to be a more appropriate term for this condition, of which a similar lesion has been previously noted in a single case of "PSC involving pancreas". Differences in age, radiologic appearance, and the negative history of ulcerative colitis exist, but the two cases in this study could be considered as a variant of PSC extensively involving pancreas, which can readily be mistaken for pancreatic carcinoma.

Aged↗

PubMed1991

Effect of low blood glucose on plasma CRF, ACTH, and cortisol during prolonged physical exercise.

The effects of low blood glucose concentration during low-intensity prolonged physical exercise on the hypothalamus-pituitary-adrenocortical axis were investigated in healthy young men. In experiment 1, six subjects who had fasted for 14 h performed bicycle exercise at 50% of their maximal O2 uptake until exhaustion. At the end of the exercise, adrenocorticotropic hormone (ACTH) and cortisol increased significantly. However, this hormonal response was totally abolished when the same subjects exercised at the same intensity while blood glucose concentrations were maintained at the preexercise level. In experiment 2, in addition to ACTH and cortisol, the possible changes in plasma concentration of corticotropin-releasing factor (CRF) were investigated during exercise of the same intensity performed by six subjects. As suggested by a previous study (Tabata et al. Clin. Physiol. Oxf. 4: 299-307, 1984), when the blood glucose concentrations decreased to less than 3.3 mM, plasma concentrations of CRF, ACTH, and cortisol showed a significant increase. At exhaustion, further increases were observed in plasma CRF, ACTH, and cortisol concentrations. These results demonstrate that decreases in blood glucose concentration trigger the pituitary-adrenocortical axis to enhance secretion of ACTH and cortisol during low-intensity prolonged exercise in humans. The data also might suggest that this activation is due to increased concentration of CRF, which was shown to increase when blood glucose concentration decreased to a critical level of 3.3 mM.

Adrenocorticotropic Hormone↗

PubMed1991

Effects of blood glucose concentration on ratings of perceived exertion during prolonged low-intensity physical exercise.

The purpose of this investigation was to determine the relationship between blood glucose concentration and perceived exertion during prolonged low-intensity exercise. After a 12-h overnight fast, seven young healthy males began bicycle exercise from 0800 h at 50% Vo2max. One hour after initiation of the exercise, 20% glucose was infused by means of an infusion pump, to maintain blood glucose concentration at a level of approximately 6.5 mM for 20 min. This was followed by 20 min of sham infusion (no glucose). This 40-min cycle was repeated until 220 min of exercise. During the first 120 min of exercise, the ratings of perceived exertion (RPE) increased gradually without any effects of the glucose infusion. Thereafter, RPE tended to decrease during glucose infusion, and finally showed a significant decrease from 180 (17 +/- 2) to 190 (16 +/- 2) min. This result showed that an increase in blood glucose concentration has a significant effect on perceived exertion, even if exercise time is prolonged. The different responses of RPE during the two phases of the exercise may be explained by the difference of glycogen concentration in muscle, because glucose infusion had no effect on RPE when muscle glycogen content was presumed to be at normal level, and was effective when glycogen in the exercising muscles was presumed to be depleted.

Adult↗