Search PubMed⌕ Search

Biomedical subjects

A Ito

Publications and source records attributed to A Ito.

At least 955 records · Page 53Linked to original sources
PubMed1981

Blood flow of the round window.

Motion pictures of the blood flow of the round window in guinea pigs were taken. In this part the blood flow of the inner ear could be distinguished from that of the middle ear. Our motion pictures show that the blood flow of the inner ear can be observed through the round window membrane without an operation on the inner ear.

Animals↗
PubMed1981

Muscle metabolism, lactate breaking point, and biomechanical features of endurance running.

Nine subjects ranging in muscle fiber composition (m, vastus lateralis) from 38% to 100% slow twitch (ST) were filmed while running on a treadmill at a speed corresponding to the onset of blood lactate accumulation (VOBLA). The film analysis concentrated on several kinetic features of running, such as mechanical work (W) and average power output (W) for the total step cycle including the positive and negative work phases. The results indicated that %ST was related significantly (r = 0.78) with VOBLA and with the average speed of a marathon race (Vm; r = 0.80), which followed the treadmill test. The values of VOBLA and Vm were 4.27 +/- 0.51 and 3.74 +/- 0.64 m x s-1, respectively. Capillary density as calculated from amylase PAS staining of the muscle samples demonstrated also a significant relationship with Vm (r = 0.80). The value of W was not significantly related to either %ST or VOBLA. However, the average mechanical power output at VOBLA (WOBLA) demonstrated high correlations with %ST (r = 0.75), VOBLA (r = 0.90), Vm (r = 0.92), and with capillary density (r = 0.77). The findings suggest that mechanical power at VOBLA is an important parameter, which indicates the maximum power output of the runner under pure aerobic conditions.

Capillaries↗
PubMed1981

Involvement of free ribosomes in the early stage of secretory protein biosynthesis in rat liver.

Nascent peptides on free and bound ribosomes prepared from rat liver were labeled and released with [3H]puromycin, and the amounts of the nascent peptides of two secretory proteins, serum albumin and transferrin, were determined by immunoprecipitation with specific antibodies. An appreciable amount of serum albumin nascent peptides was associated with free ribosomes, although most of them were carried by bound ribosomes. Serum albumin nascent peptides associated with free ribosomes were smaller in size than those carried by bound ribosomes. When the products of cell-free translation programmed by free and bound polysomes were immunoprecipitated with antibodies, the percentages of serum albumin to the total translation products were in good agreement with those obtained in the nascent peptides experiment. Cell-free translation of free polysomes produced serum albumin with a similar molecular weight to the authentic one. Although nascent peptides of transferrin were detected only on bound ribosomes, and not on free ribosomes, the transferrin antibody immunoprecipitated 0.2% of total translation products of free polysomes. These observations indicate that free polysomes have complete messenger RNA's and shorter growing nascent peptides of serum albumin and transferrin.

Animals↗
PubMed1981

Prestretch potentiation of human skeletal muscle during ballistic movement.

The conditions associated prior to and during the transition from prestretch to shortening may have considerable influence on the final performance of muscle. In the present study male subjects of good physical condition performed vertical jumps on the force-platform with and without preliminary counter movement. In the counter movement jump (CMJ) the amplitude of the knee bending, velocity of the prestretch and the force attained at end of prestretch were the primary parameters of interest. In addition the coupling time indicating the transition from the eccentric (prestretch) phase to the concentric phase was recorded from the angular displacement and reaction force curves. In the final calculation the mechanical performance parameters of CMJ were always compared with those of the jumps performed without counter movement. The results indicated in general first that CMJ enhanced the average concentric force and average mechanical power by 423 N (66%) and 1158 W (81%), respectively. This potentiation effect was the higher the higher was the force at end of prestretch (p less than 0.001). Similarly, the prestretch speed (p less than 0.001) and short coupling time (p less than 0.01) were associated with enhanced performance during the concentric phase. The average coupling time was 23 ms. The results are interpreted through changes in the prestretch conditions to modify the acto-myosin cross-bridge formation so that the storage and utilization of elastic energy is associated with high prestretch speed, high eccentric force and short coupling time. The role of the reflex potentiation is also suggested as additional enhancement of the final performance.

Adult↗
PubMed1981

Spinal tumors induced by neonatal administration of N-ethyl-N-nitrosourea in Wistar rats.

The carcinogenic effect of N-ethyl-N-nitrosourea (ENU) administered by single neonatal injection (40 mg/kg) was examined in wistar rats. By 2 months after ENU administration, 30% of the examined animals had spinal cord tumors. After months all rats had neurogenic tumors, and the incidence of spinal tumor was as high as 86%. Spinal cord tumors were observed at all levels of the white matter of the spinal cord without any predilection site, though spinal root tumors were located exclusively on lumbosacral plexuses. Most of the spinal cord tumors were oligodedrogliomas or glioependymomas, whereas all the spinal root tumors were anaplastic schwannomas.

Animals↗