Effect of a five minutes isokinetic one leg knee extension training on maximal oxygen uptake during 20 days of -6 degrees head-down tilting bed-rest in young male subjects

Due to prolonged bed rest (BR), maximal oxygen uptake (VO2max) might be decreased by above -8%, even if a moderate supine bicycle exercise (SBE) was performed for 45 to 60 minutes every day during BR. However, the decrement of VO2max was lowered to below -5% by isometric training and using a reverse gradient garment. Further it was rather slightly increased by SBE training with gradually increasing load from 40% to 90% VO2max. The facts suggest the dependency of the decrease of VO2max during BR on exercising muscle mass (MM) and strength. In the present study, therefore, the effects of isokinetic knee extension (Ik-KnE) training on VO2max, exercising MM and muscle contraction strength during BR were investigated. Then, the relationships between changes in VO2max and the muscle mass and strength were considered.     

Psychological stress induced by 20 days bed rest

We investigated the changes of the psychological state during 20 days bed rest (BR) in 10 young participants,(5 males and 5 females, age; 19-24 yrs). Psychological assessment was accomplished by the following authorized 3 indices: 1) Zung's Self-rating Depression Scale, 2) Cornell Medical Index, and 3) Goldberg's General Health Questionnaire. Zung's Self-rating Depression Scale is a indicator for depression, and the other two indices were used for detecting signs of neurosis. The results from Zung's Self-rating Depression Scale and the General Health Questionnaire in this study indicated a tendency toward depression and neurosis developing during BR, respectively. The scores in the Cornell Medical Index did not change. Urinary excretion of 17-hydroxycorticosteroid increased significantly, indicating that BR immobilization induced an important psychological stress. We were unable to determine which factors caused the changes in psychological state during BR, immobilization insert or personal problems.     

Effect of bed rest immobilization on metabolic turnover of bone and bone mineral density

Immobilization induces abnormal bone metabolism and severe decalcification of bone. To investigate the effect of middle-term immobilization on bone metabolism, we studied 10 young healthy males and females during bed rest for 20 days. Bone mineral density (BMD) rapidly decreased in both lumbar and metacarpal bones. No bone showed consistent BMD alterations, partial increase and partial decrease, and both lumbar and metacarpal bone showed similar rapid BMD change. Urinary excretion of pyridinoline tended to slightly increase by day 10, and to decline by day 20 (mean +/-SE: 34.2 +/-7.4, 26.3+/-4.6 nmol day-1, respectively). Neither alkaline phosphatase (isoform III) nor tartrate-resistant acid phosphatase, changed, suggesting that in the early stage of immobilization bone matrix in some part might increase or be resorbed without any activation of osteoblast or osteoclast, resulting in rapid calcification or decalcification, respectively.     

Effects of 20 days of bed rest on physiological cross-sectional area of human thigh and leg muscles evaluated by magnetic resonance imaging

The present study was to investigate the effects of 20 days of bed rest on morphological characteristics of lower limb skeletal muscles. Ten sedentary volunteers (5 males and 5 females) were participating in this study. Magnetic resonance imaging techniques were used to measure the physiological cross-sectional areas (PCSAs) of the major muscles and muscle groups of the lower limb. Consecutive images were taken from the right thigh and leg of subjects, and muscle volumes (MV), muscle length, and fiber length were calculated. PCSA of each muscle was determined as MV times the cosine of the angle of fiber pennation divided by fiber length. PCSA of knee extensor and flexor muscles were significant reduced during and after bed rest. MV and PCSA of individual muscles in the knee extensors decreased by -5.1 % to -8.0%. In knee flexors, MV and PCSA in biceps femoris (long head), semitendinosus, semimembranosus, and sartorius decreased during and after bed rest. MV and PCSA in medial and lateralis [correction of andateralis] gastrocnemius, and soleus were remarkably reduced by -9.4 to -10.3% after bed rest. The results suggest that there is a great variability of muscle atrophy in the lower limb muscle groups or individual muscle after bed rest and that the plantar flexors primarily affected.     

Effects of 20 days bed rest on muscle morphology

Using ultrasound, muscle thickness and fascicle angles from aponeurosis were evaluated before, during and after 20 days bed rest (BR). Subjects were healthy adults (4 women and 4 men). Measurements were carried out before and after BR and after 10 weeks of recovery, respectively. Muscle measurements were taken at nine sites in trunk and upper and lower extremities, respectively. For the m. triceps brachii, m. vastus lateralis, and m. gastrocnemius medialis, fascicle angles from the aponeurosis as well as muscle thickness were measured. There was a high statistical significant correlation between muscle thickness and cross-sectional area for quadriceps muscles, suggesting applicability of muscle thickness for evaluation of muscle size. Muscle thickness decreased in muscles of the lower extremity by 2.1-4.4 % after bed rest. In triceps brachii and vastus lateralis muscles, there were no prominent changes in muscle thickness and fascicle angles. It was concluded that muscle morphology deteriorates with changes in muscle architecture by bed rest but the response is small and muscle-specific. It was also suggested that bed rest affects not only muscle mass but muscle tone as well.     

Decrease of bone mineral density and muscle and/or strength in the leg during 20 days horizontal bed rest

Ten individuals underwent 20 days of horizontal bed rest for this study of the influence of muscle mass and strength on bone mineral density. Muscle mass volume and cross sectional area were measured using magnetic resonance imaging and bone mineral density was determined by dual energy X-ray absorptiometry before and after bed rest. Measurements were made at various parts of the leg, including the knee. Gender differences were also determined. Results are presented and discussed.     

Increased uptake sites for serotonin and dopamine with decreased S2 serotonin receptors in microencephalic rat brain

Methylazoxymethanol (MAM)-induced cerebral hypoplasia resulted in a significant increase in densities of both serotonin uptake sites in frontal cortex and dopamine uptake sites in striatum, suggesting serotonergic and dopaminergic axon terminals were compressed in the smaller brain volumes. The density of S2 serotonin receptors in MAM-lesioned frontal cortex was decreased probably due to down-regulation, while densities of D1 and D2 dopamine receptors in striatum were identical between MAM-lesioned rats and control rats.     

Generation and characterization of purified adherent lymphokine-activated killer cells in mice

During the incubation of murine spleen, lymph node, or bone marrow cells with IL-2 (1000 U/ml) a small percentage of cells became adherent to the surface of plastic tissue culture flasks. After removal of the non-adherent lymphoid cells, plastic adherent lymphokine-activated killer (LAK) cells could be efficiently expanded in the presence of IL-2. Plastic adherent-derived A-LAK cells were characterized by high rates of proliferation and their cytotoxic activity was more than 10 fold higher than LAK cells generated in the bulk (unfractionated) spleen cell cultures. A-LAK cells could be continuously generated from the non-adherent cell population. Using multiple transfers (every 1 to 2 days) of non-adherent LAK cells into new flasks, new rounds of plastic adherent cells were generated with high expansion capability and high levels of cytotoxic activity. Morphologically, A-LAK cells were large granular lymphocyte and phenotypically expressed markers characteristic of NK cells (asialo GM1+, NK1.1+, Qa5+, Ly-6.2+, Thy-1.2+, but negative for Lyt-2.2 and L3T4). A-LAK cells generated from mice of different strains expressing low and high levels of NK cell activity were equally highly cytotoxic. However, A-LAK cells obtained from nude or beige mice had relatively lower levels of cytotoxicity. Stimulation of NK cell activity by poly I:C or inhibition by in vivo or in vitro treatment with anti-asialo GM1 serum did not affect the generation of A-LAK cells. A-LAK cells derived from spleen or bone marrow of C57BL/6 or nude mice treated with anti-asialo GM1 serum were found to be asialo GM1+ suggesting that A-LAK cell could be generated from the asialo GM1- precursor cells. Expansion of plastic adherent A-LAK cells in the presence of IL-2 could provide large numbers of highly purified cytotoxic A-LAK cells suitable for cancer immunotherapy.     

Scanning Strategies Do Not Modulate Face Identification: Eye-Tracking and Near-Infrared Spectroscopy Study

Background

During face identification in humans, facial information is sampled (seeing) and handled (processing) in ways that are influenced by the kind of facial image type, such as a self-image or an image of another face. However, the relationship between seeing and information processing is seldom considered. In this study, we aimed to reveal this relationship using simultaneous eye-tracking measurements and near-infrared spectroscopy (NIRS) in face identification tasks.

Methodology/Principal Findings

22 healthy adult subjects (8 males and 14 females) were shown facial morphing movies in which an initial facial image gradually changed into another facial image (that is, the subject''s own face was changed to a familiar face). The fixation patterns on facial features were recorded, along with changes in oxyhemoglobin (oxyHb) levels in the frontal lobe, while the subjects identified several faces. In the self-face condition (self-face as the initial image), hemodynamic activity around the right inferior frontal gyrus (IFG) was significantly greater than in the familiar-face condition. On the other hand, the scanning strategy was similar in almost all conditions with more fixations on the eyes and nose than on other areas. Fixation time on the eye area did not correlate with changes in oxyHb levels, and none of the scanning strategy indices could estimate the hemodynamic changes.

Conclusions/Significance

We conclude that hemodynamic activity, i.e., the means of processing facial information, is not always modulated by the face-scanning strategy, i.e., the way of seeing, and that the right IFG plays important roles in both self-other facial discrimination and self-evaluation.     

Characterization of the L-lysine biosynthetic pathway in the obligate methylotroph Methylophilus methylotrophus

The L-lysine biosynthetic pathway of the gram-negative obligate methylotroph Methylophilus methylotrophus AS1 was examined through characterization of the enzymes aspartokinase (AK), aspartsemialdehyde dehydrogenase, dihydrodipicolinate synthase (DDPS), dihydrodipicolinate reductase, and diaminopimelate decarboxylase. The AK was inhibited by L-threonine and by a combination of L-threonine and L-lysine, but not by L-lysine alone, and the activity of DDPS was moderately reduced by L-lysine. In an L-lysine producing mutant (G49), isolated as an S-(2-aminoethyl)-L-cysteine (lysine analog) resistant strain, both AK and DDPS were partially resistant to feedback inhibition. The ask and dapA genes encoding AK and DDPS respectively were isolated from the parental strain, AS1, and its G49 derivative. Comparison of the sequences revealed a point mutation in each of these genes in G49. The mutation in the ask gene altered aspartic acid in a key region involved in the allosteric regulation common to AKs, while a novel mutation in the dapA gene altered tyrosine-106, which was assumed to be involved in the binding of L-lysine to DDPS.