Biomedical subjects

Y Mutoh

Publications and source records attributed to Y Mutoh.

At least 37 records · Page 2Linked to original sources

PubMed1993

Adaptations to six months of aerobic swim training. Changes in velocity, stroke rate, stroke length and blood lactate.

The purpose of this investigation was to determine how swimming velocity (SV), stroke rate (SR), stroke length (SL) and blood lactate concentration change as adaptations to six months of aerobic swim training. Subjects were trained male college swimmers (n = 8). Measurements were obtained following specially designed 400m freestyle swim tests, pre- and post-intervention. The swim test consisted of 4 x 400 m freestyle over two days. On day 1, subjects performed a maximal effort 400 m freestyle swimming trial; maximal mean velocity (Vmax) for each swimmer was calculated from this effort. On the next day, subjects were instructed to perform three 400 m freestyle swims at constant velocities equal to 85%, 90% and 95% of Vmax, respectively. Subjects rested one hour between swims. During each 400 m trial, lap time and time to complete 10 mid-pool strokes (50 m) were measured to determine SV (m.s-1), SR (stroke.min-1) and SL (m.stroke-1). Mixed arterial blood samples were taken at the end of each 400 m trial to evaluate blood lactate concentration. Results indicated that post-maximal swimming velocity (Vpostmax) increased significantly from pre-intervention measures (p < 0.05). Blood lactate concentration decreased significantly relative to SV and absolute lactate concentration following Vpostmax was significantly lower than that at Vpremax (p < 0.05). Six of seven subjects increased Vmax due to increases in SL. Mean SL during the second test was significantly higher (p < 0.05). Also, during the 400 m maximal test, SL increased significantly after sixth lap (p < 0.05). There was no significant difference between SRs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗

PubMed1993

[Effects of rHuEPO on aplastic anemia: results of a phase II clinical study].

The safety and efficacy of recombinant human erythropoietin (epoetin alpha) were investigated in adult aplastic anemia patients whose hemoglobin (Hb) concentration was less than 10g/dl. Epoetin alpha was given subcutaneously every day at a dose of 3,000IU/body for two weeks, and the dosage was increased to 6,000IU, 12,000IU and 24,000IU every two weeks when the increment of Hb was insufficient. In cases in whom Hb concentration increased by more than 1g/dl or whose transfusion requirements reduced to less than 50%, treatment was judged to be effective. The whole rate of efficacy was 34.5% (10/29). Response to epoetin alpha treatment was better in patients whose symptoms were relatively mild. Mild cases responded to the treatment with 6,000IU/body/day, although a dosage of 24,000IU/body/day was required in moderate or severe cases. Neither serious adverse effect nor abnormal laboratory findings were observed. These results suggest that high dose subcutaneous epoetin alpha treatment is effective for the aplastic anemia in terms of increasing Hb concentration and reducing blood transfusions.

Adolescent↗

PubMed1993

[Phase II clinical study of recombinant human erythropoietin on the anemia associated with multiple myeloma].

Safety and efficacy of recombinant human erythropoietin (epoetin alpha) were investigated in anemic patients with multiple myeloma whose hemoglobin (Hb) concentration was less than 10g/dl. Epoetin alpha (3,000IU/body) was given subcutaneously daily for two weeks and the dosage was increased to 6,000IU, 12,000IU and 24,000IU every two weeks when the increment of Hb was insufficient. Cases in which Hb concentration increased by more than 1g/dl or in which blood transfusion requirements decreased by more than 50% were judged to be effective. The overall rate of efficacy was 52.6% (10/19). Response to epoetin alpha treatment was better in patients whose blood erythropoietin level was relatively low. The majority of patients responded to the treatment with up to 6,000IU/body/day but a dosage of more than 12,000IU/body/day was required in some cases. No serious adverse effects or abnormal laboratory findings were observed. These results suggest that high-dose subcutaneous epoetin alpha treatment is effective for anemia associated with multiple myeloma in terms of increasing Hb concentration and reducing blood transfusion.

Aged↗

PubMed1993

[Phase II clinical study of recombinant human erythropoietin on the anemia of myelodysplastic syndrome].

The safety and efficacy of recombinant human erythropoietin (epoetin alpha) were investigated in anemic patients with myelodysplastic syndrome (MDS) whose hemoglobin (Hb) concentration was less than 10g/dl. Epoetin alpha was given subcutaneously daily at a dose of 3,000IU/body for two weeks and the dosage was increased to 6,000IU, 12,000IU, and 24,000IU at two week interval when the increment of Hb was insufficient. Patients in whom the Hb concentration increased by more than 1g/dl or whose blood transfusion requirement reduced to below 50% were considered to be cases of effective treatment. The overall rate of effectiveness was 20.6% (7/34). Response to epoetin alpha treatment was better in patients with refractory anemia (RA) or RA with ringed sideroblasts (RARS). The high dose epoetin alpha (12,000-24,000IU/body/day) was required for the patients to respond. These results suggest that the high dose subcutaneous epoetin alpha treatment is effective for the anemia associated with MDS in terms of increasing Hb concentration and reducing blood transfusion.

Adolescent↗

PubMed1992

Reduction and inactivation of the sarcoplasmic Ca(2+)-ATPase by 2-mercaptoethanol--contrast to the (Na+,K+) ATPase.

The sarcoplasmic Ca(2+)-ATPase was reduced with 300 mM 2-mercaptoethanol at elevated temperatures (40-45 degrees C) with a concomitant loss of ATPase activity. The reduction and inactivation of the Ca(2+)-ATPase proceeded rapidly in the absence of Ca2+. The Ca(2+)-ATPase was also inactivated with 2-mercaptoethanol in the presence of diluted SDS (0.4 mg/ml) even at 20 degrees C. In contrast to the (Na+, K+) ATPase, the inactivated Ca(2+)-ATPase in the presence of diluted SDS was sedimented by the centrifugation at 100,000 x g for 30 min.

Animals↗

PubMed1992

Determination and validity of critical velocity as an index of swimming performance in the competitive swimmer.

The purpose of this investigation was to test whether the concept of critical power used in previous studies could be applied to the field of competitive swimming as critical swimming velocity (vcrit). The vcrit, defined as the swimming velocity over a very long period of time without exhaustion, was expressed as the slope of a straight line between swimming distance (dlim) at each speed (with six predetermined speeds) and the duration (tlim). Nine trained college swimmers underwent tests in a swimming flume to measure vcrit at those velocities until the onset of fatigue. A regression analysis of dlim on tlim calculated for each swimmer showed linear relationships (r2 greater than 0.998, P less than 0.01), and the slope coefficient signifying vcrit ranged from 1.062 to 1.262 m.s-1 with a mean of 1.166 (SD 0.052) m.s-1. Maximal oxygen consumption (VO2max), oxygen consumption (VO2) at anaerobic threshold, and the swimming also velocity at the onset of blood lactate accumulation (vOBLA) were also determined during the incremental swimming test. The vcrit showed significant positive correlations with VO2 at anaerobic threshold (r = 0.818, P less than 0.01), vOBLA (r = 0.949, P less than 0.01) and mean velocity of 400 m freestyle (r = 0.864, P less than 0.01). These data suggested that vcrit could be adopted as an index of endurance performance in competitive swimmers.

Adolescent↗

PubMed1992

Cardiovascular reflexes during sustained handgrip exercise: role of muscle fibre composition, potassium and lactate.

Six healthy men performed sustained static handgrip exercise for 2 min at 40% maximal voluntary contraction followed by a 6-min recovery period. Heart rate (fc), arterial blood pressures, and forearm blood flow were measured during rest, exercise, and recovery. Potassium ([K+]) and lactate concentrations in blood from a deep forearm vein were analysed at rest and during recovery. Mean arterial pressure (MAP) and fc declined immediately after exercise and had returned to control levels about 2 min into recovery. The time course of the changes in MAP observed during recovery closely paralleled the changes in [K+] (r = 0.800, P < 0.01), whereas the lactate concentration remained elevated throughout the recovery period. The close relationship between MAP and [K+] was also confirmed by experiments in which a 3-min arterial occlusion period was applied during recovery to the exercised arm by an upper arm cuff. The arterial occlusion affected MAP while fc recovered at almost the same rate as in the control experiment. Muscle biopsies were taken from the brachioradialis muscle and analysed for fibre composition and capillary supply. The MAP at the end of static contraction and the [K+] appearing in the effluent blood immediately after contraction were positively correlated to the relative content of fast twitch (% FT) fibres (r = 0.886 for MAP vs % FT fibres, P < 0.05 and r = 0.878 for [K+] vs % FT fibres, P < 0.05). Capillary to fibre ratio showed an inverse correlation to % FT fibres (r = -0.979, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

A simple method for determining critical speed as swimming fatigue threshold in competitive swimming.

The purpose of this investigation was to determine whether the concept of the critical power could be applied to competitive swimming by using critical swimming speed (CS) as determined both in the swimming flume (CS-flume) and in the normal swimming pool (CS-pool) and whether CS could be utilized as a practical index for assessing a swimmer's endurance performance. CS defined as the swimming speed which could be theoretically maintained continuously without exhaustion was expressed as the slope of a regression line between swimming distance (D) and its duration (T) obtained at various swimming speeds. Eight highly trained swimmers were instructed to swim until onset of fatigue at four predetermined swimming speed levels in the swimming flume and at maximal effort over four different swimming distances in the swimming pool. In the results of CS-flume and CS-pool, the regression relations between D and T were expressed in the general form, D = a+b x T, with r2 being higher than 0.998 (p less than 0.01), respectively. These results both from the flume and the pool indicated extremely good linearity. Furthermore, maximal oxygen uptake (VO2max) during the incremental exercise test, swimming speed corresponding 4 mM of blood lactate concentration (V-OBLA) and mean velocity in the 400 m freestyle (V-400) were measured on each subject.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1992

Validity of critical velocity as swimming fatigue threshold in the competitive swimmer.

The purpose of this investigation was to determine whether the critical velocity (CV) as the swimming speed which can be theoretically maintained for a very long time without exhaustion could be applied to estimate the swimmer's endurance performance. CV was based on the concept of critical power originality established by Monod and Scherrer (1965) and extended by Moritani et al. (1981), and expressed as the slope of a regression line between swimming distance (D) at each velocity and its sustained time (T). Seventeen highly trained swimmers were instructed to swim the four different swimming distances (50 m, 100 m, 200 m and 400 m) at maximal effort using the swimming pool. In the results of CV, the regression relations between D and T were expressed in the general form, D = a + bxT, with r2 showing higher than 0.997 (p less than 0.001). These results indicate extremely good lineality. Furthermore, VO2max during incremental exercise test, swimming speed corresponding 4 mM of blood lactate concentration (V-OBLA) and mean velocity in the 200 m and 400 m freestyle (V-200 and V-400) were measured on nine subjects. Significant correlations were found between CV and V-OBLA (r = 0.862, p less than 0.01), CV and V-200 (r = 0.781, p less than 0.01), CV and V-400 (r = 0.999, p less than 0.001), V-OBLA and V-400 (r = 0.869, p less than 0.01) and V-200 and V-400 (r = 0.776, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Competitive Behavior↗

PubMed1992

Expression and assembly of Torpedo californica (Na,K)ATPase alpha-subunit truncated at N-terminal end in Xenopus oocytes.

cDNAs for mutant alpha-subunits of Torpedo californica (Na,K)ATPase variously truncated at the N-terminal end were constructed and transcribed in vitro. Each of the mRNAs thus synthesized was co-injected into Xenopus oocytes together with mRNA for wild-type beta-subunit. Truncation of the alpha-subunit at trypsin accessible site T2(removal of the N-terminal 36 residues, alpha delta K37) led to a decrease in ouabain-sensitive ATPase activity and ouabain-binding capacity, leaving the amount of immunoprecipitable alpha-subunit unchanged. The Km values for Na+ and K+ of alpha delta K37 were about 10mM and 2mM, respectively, and fall in the same range for the wild-type ATPase. Truncation of the alpha-subunit leaving lysine-54(alpha delta K54) or alanine-79(alpha delta A79) resulted in the loss of the ATPase activity as well as a substantial decrease in the amount of immunoprecipitable alpha-subunit. Since the beta-subunit assembles with and thereby stabilizes the alpha-subunit, which is otherwise degraded rapidly, these results suggest that the segment of the alpha-subunit between lysine-37 and lysine-54 is involved in the assembly with the beta-subunit leading to the formation of the stable and active alpha beta complex.

Animals↗

PubMed1991

The 'lysine cluster' in the N-terminal region of Na+/K(+)-ATPase alpha-subunit is not involved in ATPase activity.

The alpha-subunit of the Na+/K(+)-ATPases from several animal species have markedly similar amino acid sequences. However, the N-terminal sequences of the alpha-subunit are rather divergent except for lysine-rich sequences, the 'lysine cluster'. Here we report that the alpha-subunit from frog (Rana catesbeiana) has an N-terminal sequence with the 29 amino acid residues shorter than that of the Xenopus alpha-subunit deduced from its cDNA and hence lacks the 'lysine cluster'. Nevertheless, the Rana enzyme still exhibits ATPase activity. The ATP-dependent Na+ transport activity of the Rana enzyme was similar to that of the dog enzyme, which contains the 'lysine cluster'. Moreover, the Torpedo alpha-subunits deprived of the 'lysine cluster' by means of two gene deletions showed the same Na+/K(+)-ATPase activities as that of the wild type when expressed in Xenopus oocytes from their mRNAs. These results strongly suggest that the 'lysine cluster' in the N-terminal region of the alpha-subunit is not involved in the ATPase and ion transport activities. Since an active alpha-subunit was translated in Xenopus oocytes from mRNA lacking the N-terminal region including the 'lysine cluster', these regions were proved not to function as a membrane insertion signal sequence.

Adenosine Triphosphatases↗

PubMed1991

The ventilatory threshold gives maximal lactate steady state.

The purpose of this study was to examine whether the ventilatory threshold (Thv) would give the maximal lactate steady state ([la]ss, max), which was defined as the highest work rate (W) attained by a subject without a progressive increase in blood lactate concentration [la]b at constant intensity exercise. Firstly, 8 healthy men repeated ramp-work tests (20 W.min-1) on an electrically braked cycle ergometer on different days. During the tests, alveolar gas exchange was measured breath-by-breath, and the W at Thv (WThv) was determined. The results of two-way ANOVA showed that the coefficient of variation of a single WThv determination was 2.6%. Secondly, 13 men performed 30-min exercise at WThv (Thv trial) and at 4.9% above WThv (Thv + trial), which corresponded to the 95% confidence interval of the single determination. The [la]b was measured at 15 and 30 min from the onset of exercise. The [la]b at 15 min (3.15 mmol.l-1, SEM 0.14) and at 30 min (2.95 mmol.l-1, SEM 0.18) were not significantly different in Thv trial. However, the [la]b of Thv + trial significantly increased (P less than 0.05) from 15 min (3.62 mmol.l-1, SEM 0.36) to 30 min (3.91 mmol.l-1, SEM 0.40). These results indicate that Thv gives the [la]ss, max, at which one can perform sustained exercise without continuous [la]b accumulation.

Adult↗

PubMed1991

Three-dimensional analysis of condylar hyperplasia with computed tomography.

Three-dimensional surface reconstruction imaging from CT scans was used to study the deformity of the mandible in six patients with mandibular asymmetry. High-resolution axial CT scans of the mandible were obtained using Somatom-DR3 (Siemens). COSMOZONE-2SA (Nikon) with PC-9801VX21 (NEC) was used to reconstruct the three-dimensional images. The six patients were divided into two groups. One group was classified as unilateral hybrid forms and the other group was classified hemimandibular elongation on the diagnostic criteria of Obwegeser and Makek (1986). In the three-dimensional surface reconstruction, exact location and the degree of the deformity in the region from the ascending ramus to the condylar head and the lingual aspect from the ascending ramus to the mandibular body were accurately represented. In addition, the three-dimensional images could be easily rotated arbitrarily, precise evaluation could be done at every part of the mandible. On diagnosis, the mandibular morphology classified into the unilateral hybrid forms was presumed to vary from case to case even in the same classification.

Adolescent↗

PubMed1991

High-dose cytosine arabinoside as consolidation chemotherapy for acute nonlymphocytic leukemia in remission.

A controlled study was conducted to evaluate the efficacy of high-dose cytosine arabinoside (Ara-C) in consolidation therapy of acute nonlymphocytic leukemia in remission. Twenty-seven patients with acute nonlymphocytic leukemia during their first complete remission were divided into two groups. The high-dose Ara-C group (15 patients) received two courses of high-dose Ara-C and daunorubicin, i.e., 3 g/m2 of Ara-C IV over 1 h every 12 h eight times followed by 25 mg/m2 per day daunorubicin IV bolus for 2 days, and no maintenance chemotherapy. The control group (12 patients) received the conventional consolidation therapy (usually 7 days administration of 200 mg/m2 of behenoyl-arabino-furanosylcytosine and 2 to 3 days administration of 25 mg/m2 of daunorubicin) repeated every 3 to 4 months for more than 2 years. There were no significant differences in the duration of remission and survival between the two groups. It is suggested that high-dose Ara-C consolidation is worth employing in the treatment of acute nonlymphocytic leukemia because of its convenience for patients.

Adolescent↗

PubMed1991

[Prediction of bone marrow function by the appearance rate of RNA-rich reticulocytes during the chemotherapy for hematologic malignancy].

Percentage of RNA-rich (High fluorescence Ratio, HFR), RNA-middle (Middle Fluorescence Ratio, MFR) and RNA-low (Low Fluorescence Ratio, LFR) reticulocytes was estimated by Sysmex R-1000 reticulocyte counter during the chemotherapy of 27 cases with acute leukemia and malignant lymphoma (36 courses). In the beginning of marrow suppression, HFR and/or MFR were decreased faster than LFR, neutrophils or platelets in 14 courses (38.9%). Simultaneous decrease of HFR, MFR and other blood cells were observed in 57.2%. In the recovery phase of bone marrow, faster increase of HFR and/or MFR was noted in 52.8% and simultaneous increase of these reticulocytes with other blood cells was observed in 9 courses (25%). Appearance rate of RNA-rich younger reticulocytes is a sensitive parameter for the prediction of bone marrow suppression and recovery during the chemotherapy for hematologic malignancy.

Adolescent↗

PubMed1990

Effect of physical training on the responses of serum adrenocorticotropic hormone during prolonged exhausting exercise.

The purpose of this study was to investigate the effects of physical training on the responses of serum adrenocorticotropic hormone (ACTH) and cortisol concentration during low-intensity prolonged exercise. Five subjects who had fasted for 12 h cycled at the same absolute intensity that elicited 50% of pre-training maximal oxygen uptake (VO2max), either until exhaustion or for up to 3 h, before and after 7 weeks of vigorous physical training [mean daily energy consumption during training exercise, 531 kcal (2230 kJ)]. In the pretraining test, serum ACTH and cortisol concentrations did not increase during the early part of the exercise. Increases in concentrations of both hormones occurred in all subjects when blood glucose concentration decreased during the later phase of the exercise. The mean values and SEM of serum ACTH and cortisol concentrations at the end of the exercise were 356 ng.l-1, SEM 79 and 438 micrograms.l-1, SEM 36, respectively. After the physical training, VO2max of the subjects improved significantly from the mean value of 50.2 ml.kg-1.min-1, SEM 2.5 to 57.3 ml.kg-1.min-1, SEM 2.0 (P less than 0.05). In the post-training test, exercise time to exhaustion was prolonged in three subjects. Comparing the pre- and post training values observed after the same length of time that the subjects had exercised in the pre-training test, the post-training values of serum ACTH (44 ng.l-1, SEM 3) and cortisol (167 micrograms.l-1, SEM 30) concentration were less than the pre-training value (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗

PubMed1990

[Combination therapy with aztreonam and clindamycin on severe infections accompanying neutropenic patients with hematological disorders].

We studied effectiveness and safety of combination therapy of aztreonam (AZT) (2-6 g/day) and clindamycin (CLDM) (1,200-2,400 mg/day) on severe infections in neutropenic patients with hematological diseases. We administered AZT and CLDM to 250 consecutive patients and analyzed the results of a total of 212 cases for evaluation except 38 cases of exclusions and dropouts. Hematological malignancies constituted the dominating underlying diseases which represented 90.6% of all underlying diseases. The overall clinical efficacy of the combination therapy with AZT and CLDM was 65.6% and the following results were obtained for different categories: sepsis, 64.7%; suspected sepsis, 66.4%; and pneumonia 54.5%. Even severe patients with less than 100/microliters of neutrophil counts showed good responses with an efficacy rate at 57.4%. Side effects were observed in only 7 cases (2.8%). We concluded that the combination therapy with AZT and CLDM would be useful as empiric therapy against various infections in febrile neutropenic patients with hematological diseases.

Adult↗

PubMed1990

[Diagnostic significance of the number of bone marrow megakaryocytes in cases with decreased platelet production evidenced by platelet kinetic study].

In 18 patients with decreased platelet production proved by reduced platelet turnover, the numbers of megakaryocytes in clot section of marrow aspirate were counted. Platelet counts ranged from 19,000 to 128,000/microliters. The sternal marrow showed decrease of megakaryocytes only in 3 out of 18 cases while megakaryocytes in the iliac marrow were reduced in 6 out of 11 cases. Only one of 11 cases showed decrease of megakaryocyte in both marrows examined. On the contrary, four cases showed normal number of megakaryocytes at both sites. Of 9 cases with normal or increased number of megakaryocytes in sternal and/or iliac marrow, no case showed morphologically abnormal megakaryocytes and only one case had the reduced number of platelet-forming megakaryocytes. Results suggested that the number of megakaryocytes in bone marrow especially in the sternum was not reliable for establishing the diagnosis of decreased platelet production, and that about 50% of patients with thrombocytopenia due to hypoproduction of platelets could be diagnosed pertinently only after the study of platelet kinetics.

Adolescent↗