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Biomedical subjects

T Sasa

Publications and source records attributed to T Sasa.

At least 19 recordsLinked to original sources
PubMed2003

Effects of active recovery under a decreasing work load following intense muscular exercise on intramuscular energy metabolism.

The effect of active recovery at a decreasing % of MVC following intense muscular exercise on intramuscular pH was investigated in vivo using 31P-MRS. Seven healthy men participated, and their right wrist flexor muscle group was examined. The subjects were asked to flex their right wrist at 60 % of the maximum voluntary contraction (MVC) every 2 s until the intracellular pH in the wrist flexor muscle decreased to 6.4. After the exercise period, the subjects underwent active or passive recovery for 10 min. For the active recovery (AR), the subject was asked to continue exercising at a decreasing % of MVC, decreasing from 25 to 5 % MVC every two min during AR. 31P-MR-spectra were obtained throughout the experiments, and from the spectra the intracellular pH (pHi) was calculated as an indicator of intracellular events. AR data were compared to data collected during passive recovery (PR). During AR, the pHi increased immediately after the exercise period; whereas in that of PR, it did not recover within 5 minutes after exercise. The results suggested that mild exercise was an effective manoeuver to promote recovery from intramuscular metabolic acidosis.

Adult↗
PubMed2001

Effects of ovariectomy on intramuscular energy metabolism in young rats: how does sports-related-amenorrhea affect muscles of young female athletes?

The purpose of this study was to evaluate the effects of ovariectomy on intramuscular energy metabolism in young rats. Twenty-four Sprague-Dawley rats (7 weeks old) were used. Twelve of them underwent ovariectomy (OVX), and the others were sham-operated on. Seven OVX rats were examined 1-week after surgery (OVX-1 group), and the other five, 4 weeks after surgery (OVX-4 group). The gastrocnemius-plantaris-soleus (GPS) muscles group was subjected to the following measurements, and the data were compared with those of the sham group (Sham-1: n = 7, or Sham-4 group: n = 5). From the 31P-MR spectra of the GPS muscles group at rest and during electric stimulation, the muscular oxidative capacity was measured. Maximum tension and wet weight of the whole GPS muscles group were also measured. Body weight in the OVX-4 group was significantly (p < 0.01) larger than that in the Sham-4 group. The weights of the whole GPS muscles group in the Sham-1, Sham-4, OVX-1 and OVX-4 groups were 1.17, 1.51, 1.25 and 1.71 (g), respectively. The muscle weight in the OVX group tended to be greater than that in the Sham group (p < 0.10). The maximum tension and oxidative capacity did not differ significantly among the groups. These data indicated that in young rats, ovariectomy induced an increase in body and muscle weight, but did not affect the maximum tension nor oxidative capacity.

Amenorrhea↗
PubMed2001

Evaluation of disuse atrophy of rat skeletal muscle based on muscle energy metabolism assessed by 31P-MRS.

The purpose of this study was to evaluate disuse atrophy of skeletal muscle using a hind-limb suspension model, with special reference to energy metabolism. Twenty-four Sprague-Dawley rats were divided into four groups: control group (C), hind-limb suspended for 3 days (HS-3), for 7 days (HS-7) and for 14 days (HS-14). The gastrocnemius-plantaris-soleus (GPS) muscles in each group were subjected to the following measurements. After a 2-min rest, contraction of the GPS muscles was induced by electrical stimulation of the sciatic nerve at 0.25 Hz for 10 min, then the frequency was increased to 0.5 and 1.0 Hz every 10 min. During the stimulation, twitch forces were recorded by a strain gauge, and 31P-MRS was performed simultaneously. Maximum tension was measured at the muscle contraction induced at 0.25 Hz; the wet weight of the whole and each muscle in the GPS muscles was also measured. From the 31P-MR spectra during muscle contraction, the oxidative capacity was calculated and compared among the groups. The weights of the whole GPS muscles in C, HS-3, HS-7 and HS-14, were 2.66 +/- 0.09, 2.39 +/- 0.21, 2.34 +/- 0.21 and 2.18 +/- 0.14 (g) respectively. Thus, the muscle mass significantly decreased with time (p < 0.05). Among the GPS muscles, the decrease in weight of the soleus muscle was especially remarkable; in the HS-14 group its weight decreased to 60% of that in the C group. We evaluated maximum tension and oxidative capacity as the muscle function. The maximum tensions in C, HS-3, HS-7 and HS-14 were 519 +/- 43, 446 +/- 66, 450 +/- 23 and 465 +/- 29 (g), respectively. This was significantly greater in the C group than in any other groups, however there were no significant differences among the three HS groups. The oxidative capacity during muscle contraction in the C group was higher than in any HS group and it did not further decrease even if the suspension of the limbs was prolonged beyond 3 days. The present study showed that in disuse atrophy, muscle mass and muscle function did not change simultaneously. Thus, it is necessary to develop countermeasures to prevent muscle atrophy and muscle function deterioration independently.

Animals↗
PubMed1996

Long-term administration of natural interferon-alpha in patients with chronic hepatitis C: relationship to serum RNA concentration, HCV-RNA genotypes, histological changes and hepatitis C virus.

To virologically assess the efficacy of interferon therapy in chronic hepatitis C, either 5 or 10 MU/day natural interferon-alpha (IFN alpha) was administered to 57 patients with chronic hepatitis C for 38 weeks. A complete and sustained response (CR-SR), as evidenced by the absence of serum hepatitis C virus (HCV)-RNA during the administration period and at 6 months after the final administration of IFN alpha and normal GPT level at 6 months after final administration, occurred in 42.6% (23/54) of subjects. Liver tissue was histologically evaluated using the histological activity index (HAI) score before and after the administration period. In CR-SR cases, significant improvements (P < 0.01) occurred in periportal necrosis, intralobular necrosis, portal inflammation and total score. A comparison, by HCV genotypes, revealed that CR-SR occurred in 60% (9/15) of subjects with type 2a and 30.3% (10/33) of subjects with type 1b. A comparison by virus concentration revealed that CR-SR occurred in 71.4% (15/21) of those subjects having a virus concentration of < 10(5) copies/mL, but in only 24.2% (8/33) of those having a virus concentration of > 10(5) copies/mL. Analysis by a multiple logistic model revealed a strong correlation between the therapeutic effect of interferon therapy and the pre-administration virus concentration (P = 0.0061) and genotype (P = 0.0015). These results suggest that the pre-administration virus concentration and genotype are both key factors affecting the therapeutic effect of interferon therapy in chronic hepatitis C and that the therapeutic effect of interferon is satisfactorily high, irrespective of virus concentration, in subjects with type 2a HCV, but varies depending on virus concentration in subjects with type 1b.

Aged↗
PubMed1986

Purification and characterization of benzoyl-L-arginine p-nitroanilide hydrolase from etiolated leaves of Zea mays.

Benzoyl-L-arginine p-nitroanilide hydrolase in the etiolated leaves of Zea mays L. has been purified 1,266-fold by a combination of gel filtration, ion exchange, and hydrophobic chromatography with a recovery of 13%. The specific activity of the purified enzyme is 5.7 units/mg protein. The enzyme is an acidic protein with a pI value of 4.6 and optimum pH of 8.2. The molecular weight of the enzyme was estimated to be 59,000. Substrate inhibition was observed at a concentration higher than 30 microM BAPA and the apparent Km for BAPA was 29 microM at pH 8.0. The enzyme activity was inhibited by sulfhydryl reagents, leupeptin, antipain, and N-tosyl-L-lysine chloromethyl ketone. The inhibitor study suggests that the enzyme belongs to the class of the sulfhydryl proteases.

Endopeptidases↗
PubMed1984

Purification and properties of L-alanine:4,5-dioxovalerate aminotransferase from Chlorella regularis.

The enzyme L-alanine:4,5-dioxovalerate aminotransferase (EC 2.6.1.43), which catalyzes the synthesis of 5-aminolevulinic acid, was purified 161-fold from Chlorella regularis. The enzyme also showed L-alanine:glyoxylate aminotransferase activity (EC 2.6.1.44). The activity of glyoxylate aminotransferase was 56-fold greater than that of 4,5-dioxovalerate aminotransferase. The ratio of the two activities remained nearly constant during purification, and when the enzyme was subjected to a variety of treatments. 4,5-Dioxovalerate aminotransferase activity was competitively inhibited by glyoxylate, with a Ki value of 0.5 mM. Double-reciprocal plots of velocity versus 4,5-dioxovalerate with varying L-alanine concentrations indicate a ping-pong reaction mechanism. The apparent Km values for 4,5-dioxovalerate and L-alanine were 0.12 and 3.5 mM, respectively. The enzyme is an acidic protein having an isoelectric point of 4.8. The molecular weight of the enzyme was estimated to be 126,000, with two identical subunits. These results suggest that, in Chlorella, as in bovine liver mitochondria and Euglena, both 4,5-dioxovalerate and glyoxylate aminotransferase activities are associated with the same protein. From the activity ratio of transamination and catalytic properties, it is concluded that this enzyme does not function primarily as a part of the 5-carbon pathway to 5-aminolevulinic acid synthesis.

Catalysis↗
PubMed1984

Terminal steps of bacteriochlorophyll a phytol formation in purple photosynthetic bacteria.

Four chemically different bacteriochlorophylls (Bchls) a esterified with geranylgeraniol, dihydrogeranylgeraniol, tetrahydrogeranylgeraniol, and phytol have been detected by high-pressure liquid chromatography in cell extracts from Rhodopseudomonas sphaeroides and Chromatium vinosum. Bchl a containing phytol is the principal component, and the other three Bchls a comprise about 4% of the total Bchls a in stationary-phase cells of R. sphaeroides and C. vinosum. The high levels of the minor pigments occur in the beginning of Bchl a phytol formation, indicating that they are not degradation products, but intermediates of Bchl a phytol formation.

Bacteriochlorophylls↗
PubMed1983

Analysis of porphyrin precursors, 5-aminolevulinic acid derivatives by isotachophoresis.

Porphyrin precursors, 5-aminolevulinic acid (ALA), 4,5-dioxovaleric acid (DOVA), and porphobilinogen (PBG) can be simultaneously and conveniently analyzed by isotachophoresis. The quantitative analysis requires a minimum of 12 nmol for ALA, 4 nmol for DOVA, and 35 nmol for PBG. The reproducibility determined as coefficient of variation for qualitative and quantitative determination is within 4 and 5%, respectively. Isotachophoresis permits simple, efficient and quantitative detection, and identification of ALA derivatives in a mixture.

Aminolevulinic Acid↗
PubMed1983

Compositional heterogeneity of protochlorophyllide ester in etiolated leaves of higher plants.

The formation and degradation of protochlorophyllide esters, i.e., protochlorophylls, were studied in etiolated leaves of kidney bean in relation to their aging. By the sensitive analysis of the pigments using high-performance liquid chromatography, the presence of four protochlorophylls esterified with phytol, tetrahydrogeranylgeraniol (THGG), dihydrogeranylgeraniol (DHGG), and geranylgeraniol (GG) was detected in kidney bean grown in the dark. Similar components were also observed in the etiolated seedlings of cucumber, sunflower, and corn. The content of each protochlorophyll species changed with the plant species and age of plants. In the case of kidney bean, the content of protochlorophyll phytol reached a maximal level at 9 days, then decreased rapidly during the subsequent development, in spite of the total protochlorophyll content remaining unchanged. In contrast to the degradation of protochlorophyll phytol, the other three protochlorophylls esterified with THGG, DHGG, and GG accumulated. These results may indicate that (i) protochlorophyll phytol is formed from the first esterified protochlorophyll GG through the next three hydrogenation steps as in the case of chlorophyll a phytol formation; (ii) the esterification reaction stops at 9 days and then reaction proceeds in sequence in the reverse direction, leading to the dehydrogenation of the alcohol moiety of protochlorophyll phytol to protochlorophylls THGG, DHGG, and GG.

Chlorophyll↗
PubMed1980

Purification by affinity chromatography and properties of uroporphyrinogen I synthetase from Chlorella regularis.

Uroporphyrinogen I synthetase (porphobilinogen ammonia-lyase (polymerizing), EC 4.3.1.8) from Chlorella regularis was purified to homogeneity by affinity chromatography on porphobilinogen-AH-Sepharose 4B, which was prepared by reacting carbodiimide with substrate, porphobilinogen. The enzyme was purified 232-fold from the initial crude extract and specific activity was 348 nmol porphyrinogen I formed (mg protein)-1 . h-1 at pH 7.4. The molecular weight of the enzyme was 35 000-36 000 as determined by Sephadex G-100 gel filtration. This enzyme was acidic protein having an isoelectric point of 4.2. The enzyme exhibited a single pH optimum at a pH value of 7.4 both in phosphate and Tris-HCl buffer. The Km value for porphobilinogen was 89 microM as measured by its consumption and 85 microM when uroporphyrin formation was used. The Arrhenius plot obtained from the enzyme activity measurements appeared triphasic with breaks occurring at 35 and 46 degrees C and activation energy was calculated to be 21 700 (10-35 degrees C), 12 700 (35-46 degrees C) and 1800 cal . mol-1 (46-65 degrees C). This enzyme was heat stable and the enzyme still retained 87% of activity, even after 1 h incubation at 75 degrees C.

Amino Acids↗
PubMed1978

[Complications after pacemaker-implantation and their treatment (author's transl)].

Of the 1050 pacemaker-implantations in the German Heart Centre in Munich from April 1974 to December 1977 complications arose in 229 cases necessitating a renewed surgical intervention. In accordance with the literature the dislocation of electrodes was the most frequent complication in the first days and weeks after implantation in our patients wil 11,1%. In cases of electrode dislocation the repositioning of the electrode is necessary; in certain cases an epi-myocardial electrode must be substituted for the usual transvenous electrode. Essential causes of complications were disturbances in woundhealing, necrosis of the skin and infection of the pacemaker-system, which were seen in 3,7% of all cases. In the case of infection of therapy of choice is the explntation of the pacemaker and the implantation of a new system in another position. Technical complications due to material are electrode fractures and battery defects. Complications due to material defects necessitate the exchange of the pacemaker or the electrode. Rare indications for reoperation were increase in threshold, muscle stimulation and allergi reactions caused by pacemakers.

Electrodes, Implanted↗