1.Relationships of intracellular pH to oxygenated hemoglobin/myoglobin and to phosphate compounds in active muscle during forearm exercise.
MASASUKE KUWAMORI ; HISAO IWANE ; TAKAFUMI HAMAOKA ; NORIO MURASE ; YUKO KUROSAWA
Japanese Journal of Physical Fitness and Sports Medicine 1995;44(4):465-474
The purpose of this study is to find a key to clarifying the mechanism of lactic acid production during exercise. Five healthy men performed the grip and wrist flexion exercises at different occasions. Exercise intensities were increased by 5% MVC (maximum voluntary contraction force) per minute from 10% MVC. Intracellular pH, oxygenated hemoglobin/myoglobin (Oxy-Hb/Mb), inorganic phosphate (Pi), and phosphocreatin (PCr) in forearm flexor muscles were measured by 31P-MRS and NIRS. The lowest Oxy-Hb/Mb concentrations during the grip and wrist flexion exercises were 40.7± 8.86% (average±SE) and 15.4 ± 2.26%, respectively. These results suggest that oxygen remain sufficient in the muscles at least during the grip exercise. Intracellular pH dropped as exercise intensity rose above 25% MVC for the grip and above 10% MVC for the wrist flexion exercise. These results support the idea that oxygen deficiency is not the only cause for lactic acid production during exercise. On the other hand, intracellular pH fell with either negative or positive relations to Pi/PCr ratio, Pi, and PCr in each exercise. These results support the suggestion that the main causes of lactic acid production during exercise are the changes in ADP, Pi, and PCr.
2.Metagenome analysis of tempeh production: Where did the bacterial community in tempeh come from?
Rahmadina Radita ; Antonius Suwanto ; Norio Kurosawa ; Aris Tri Wahyudi ; Iman Rusmana
Malaysian Journal of Microbiology 2017;13(4):280-288
Aims: Tempeh is a soy-based traditional food fermented by Rhizopus oligosporus. Although this mold is the main
microorganism responsible for tempeh fermentation, various unknown bacteria presence in tempeh could enhance
tempeh’s nutritional value. This study is aimed to examine the identity of bacteria in tempeh bacterial community by
combining metagenomics analysis and culturable technique.
Methodology and results: Samples were obtained from a tempeh producer which consists of raw soybeans, fresh
water used to soak the beans, soaking water after the beans were soaked for 18 h, dehulled-soybean before inoculation,
starter culture, and fresh tempeh. All samples were plated onto Enterobacteriaceae and Lactic Acid Bacteria agar media,
and the total DNA was extracted for metagenomics analysis based on 16S rRNA gene cloning and High-Throughput
Sequencing (HTS). Metagenomic analysis indicated that Firmicutes and Proteobacteria were the predominant and subdominant
bacteria, respectively, while the culturable technique showed Proteobacteria were the predominant bacteria.
Firmicutes species detected in tempeh were similar to the ones in the soaking water, which were populated by
Lactobacillus. However, another predominant bacteria from tempeh, Enterococcus, was similar to minor population of
Enterococcus detected in dehulled-soybean before inoculation. Based on the cloned 16S rRNA genes, we observed L.
agilis, L. fermentum, and E. cecorum as the predominant bacteria in tempeh. The starter culture, which was dominated
by Clostridium, did not alter bacterial community in tempeh, since its proportion was only 2.7% in tempeh clean reads.
Conclusion, significance and impact of study: The dominant bacteria in tempeh was Lactobacillus from Firmicutes.
The bacterial community in tempeh was not affected by the starter culture used, but mainly because of the soybean
soaking process.
3.MUSCLE OXYGENATION HETEROGENEITY IN A SINGLE MUSCLE AT REST AND DURING BICYCLE EXERCISE
RYOTARO KIME ; TAKUYA OSADA ; KIYOSHI SHIROISHI ; SHIRO ICHIMURA ; YUKO KUROSAWA ; TOSHIYUKI HOMMA ; NAOKI NAKAGAWA ; JUNICHI MIYAZAKI ; NORIO MURASE ; TOSHIHITO KATSUMURA
Japanese Journal of Physical Fitness and Sports Medicine 2006;55(Supplement):S19-S22
We evaluated regional differences of muscle O2 dynamics between distal and proximal sites in the vastus lateralis (VL) muscle using near infrared spatial resolved spectroscopy (NIRSRS). forty-one male subjects performed a 30 W ramp incremental bicycle exercise test until exhaustion. The NIRSRS probes were attached on each distal and proximal site in the VL. The pulmonary O2 uptake and heart rate were monitored continuously during the experiment. The TOI at rest was significantly higher in proximal than distal sites (65.0±5.2 vs. 69.7±4.6%, p<0.001). The TOI at exhaustion was also significantly higher in proximal than distal sites (39.5±6.7 vs. 47.5±7.6%, p<0.001). Moreover, a significant correlation was found between VO2max and the TOI at exhaustion in each proximal and distal site in the VL. Half time reoxygenation, the time to reach a value of half-maximal recovery, was significantly slower in distal sites than proximal sites (27.1±5.6 vs. 25.0±6.1 sec, p<0.01). In conclusion, lower muscle oxygenation at exhaustion in higher VO2max may be due to enhanced O2 extraction in high oxidative capacity muscle. In addition, slower reoxygenation and lower muscle deoxygenation at the distal site in the VL may be explained by differences in O2 supply and/or muscle fiber composition between distal and proximal sites.