The distribution of intratracheally administered plutonium-239 throughout the skeletal bones]

The data are presented on distribution of the intratracheally administered plutonium-239 within the skeleton bones. Plutonium was found to be distributed non-uniformly within the skeleton: it was concentrated mainly in the bones where the trabecular fraction of the bone tissue was most manifest. The results obtained were supported by the correlation analysis.     

Synthesis of phosphoenolpyruvate [correction of phosphoenolphosphate] from pyruvate in rat skeletal muscle

1. The activity of pyruvate kinase, malic enzyme, phosphoenolpyruvate carbonoxykinase and pyruvate carboxylase was measured in muscle tissue. 2. The enzyme assays were critically evaluated. 3. Muscle tissue possesses at the most only residual activities of pyruvate carboxylase and PEP carboxykinase. 4. The pyruvate kinase activity was significantly lowered after a 24 hr fast. 5. Malic enzyme activity was increased after the fast.     

The mechanism [correction of mehanism] of spatial [correction of spetial] orientation in conditions of G-stress

Six test subjects were subjected to lateral (+Gy) and longitudinal-lateral (+Gz/+Gy) accelerations in a centrifuge with a rotation radius of 6.55 m. During rotation, test subjects were instructed to indicate the position of subjective visual vertical. Results of this study demonstrated that during exposure to +Gy and +Gz/+Gy accelerations, the direction of the indicated subjective vertical approached the direction of the resultant acceleration vector when the lateral component increased. This observed effect decreases with an increase of the longitudinal component of the acceleration. It was suggested that exposure to (i.e. "pulling") high lateral acceleration (up to 2-3 Gy) in highly maneuverable aircraft can hinder spatial orientation of a pilot due to this persistent illusory spatial position as reported above. Our analysis showed that the process of spatial orientation under the conditions of G-load influence becomes more difficult and it is depending on the compromise between visual and vestibular-proprioceptive inputs. On account of this finding, it may be proposed that under conditions of G-load influence, pilots that rely primarily on visual perception may be exposed to higher risk of spatial disorientation.     

The relationship between the stiffness and the mineral content of bone

The modulus of elasticity (E) of bone increases very rapidly with increase in mineral content, and in this is atypical of most composite materials. It is proposed that this apparent anomaly is caused by the end-to-end fusion of apatite crystals as the matrix becomes saturated with mineral. There is electron microscopic evidence that this occurs. Calculations using a fairly simple model show that this mechanism could be effective in life.     

Peculiarities [correction of Peculiarites] of the graviperception and graviresponses [correction of graviresponces] in some unicellular eukaryotic organisms

The growth and ultrastructure of Vaucheria sessilis, a siphonaceous alga, were studied during simulated weightlessness using a clinostat and during hypergravity on a centrifuge. Observations, including abnormalities in sporulation and changes in the distribution of nuclei, are presented and discussed.     

Physique types and the skeletal mineral saturation of young men and women

The term "massiveness of the skeleton" does not reflect the amount of the mineral component in bones. As demonstrates application of the standard linear x-ray densitometry, in a more "massive" skeleton amount of mineral salts per a volume unit of the osseous tissue is less than in a thin "gracile" skeleton of the thoracal type of constitution. The muscular type of constitution concerning the mineral saturation occupies an intermediate position between the thoracal and digestive constitutional types.     

The difference between the mineral content and the width of the radius on each side and its significance for handedness determination of skeletal material

The objective of our work was to investigate whether the side-different use of the upper extremities due to handedness produces detectable differences in bone-mineral content (BMC) and bone width (BW). For this purpose 251 recent individuals whose handedness was established, were examined by means of the 125I-photon-absorption technique. Highly significant right-left differences in BMC and BW were found on the midshaft and distal radius. Discrimination functions based on BMC and BW were carried out, allowing for the classification into the appropriate handedness categories. Applying the same method we tried to diagnose the handedness of the skeletal material of 40 medieval and 27 neolithic individuals.     

Phosphate metabolism in the mineral matrix of intact bones and after single and multiple fractures]

The level of mineral matrix phosphates in unbroken bones was investigated in rats with isolated and multiple fractures. It was found out that in bones lying close to the broken one the phosphates exchange shifts were similar to the changes happening in the region of the trauma. On the resorption stage the phosphates level in the nearby intact tissue decreases, during the bone callus formation it increases, and in the process of remodelling decreases again. The authors suggest that this zone should be identified under the term "trauma field".     

Different effects of oestradiol benzoate and norethisterone on the blood flow and mineral content in rat bones.

In three experiments (2 on females, 1 on males), we determined the blood flow in the tibia and the distal part of the femur, together with cardiac output (by means of 85Sr-microspheres), tibial bone density and tibial ash weight related to bone volume. We found that 1) the bone blood flow always fell significantly after oestradiol benzoate, 2) no change occurred after norethisterone in doses corresponding to those of oestradiol benzoate, but the blood flow showed a tendency to fall after doses one order higher (it decreased significantly in one case only), 3) the density of the tibia and tibial ash weight related to bone volume rose nonsignificantly after oestradiol benzoate, but fell (mostly statistically significantly) after norethisterone. The lowering of the bone mineral indexes in rat bones after norethisterone is a surprising and potentially significant finding requiring further verification.     

Interaction between phospholipid bilayer membranes and the polyene antibiotic amphotericin B: Lipid state and cholesterol content dependence

The interaction between amphotericin B and egg yolk phosphatidylcholine, dimyristoyl (DMPC) and dipalmitoyl phosphatidylcholine (DPPC) phospholipid bilayer vesicles has been monitored by the circular dichroism (CD) spectra of amphotericin B at a 1 · 10^?5 M concentration. This method has revealed that amphotericin B may be present in a number of different forms depending on the time elapsed after the mixing, the cholesterol content of the vesicles and the vesicles' physical state. Some striking features of these CD detected species are the following: with egg yolk phosphatidylcholine and a molar cholesterol percentage lower than 25, at 25°C several forms are coexistent, their amount is time-dependent; with dipalmitoyl or dimyristoyl phosphatidylcholines without cholesterol or with a cholesterol molar percentage lower than 25, in the gel state, a form different from the former appears very rapidly; with egg yolk phosphatidylcholine, DMPC and DPPC at a molar cholesterol percentage between 25 and 50 a new form is monitored, identical in the three cases and observed in the liquid crystalline state as well as in the gel state. In the case of the three phospholipids without cholesterol a definite interaction with the antibiotic is observed but with different characteristics according to the nature of lipid.With amphotericin B ‘Fungizone’ the same species are monitored but their appearance is much slower.Two explanations are proposed for the origin of the discrepancies between CD and electronic absorption.     

Effect of physical work on the aging process in certain skeletal bones of the extremities]

The long-term investigation of the influence of physical exercise upon the structure of human skeleton revealed certain peculiar features in the process of developmental reconstruction of joints of the upper (humeral joint, hand joints) and lower (knee joint, the joints of the foot) extremities resulting from the occupation of the persons under study. Roentgen-anatomical studies performed in 433 industrial and 430 office workers established the fact of retardation and deceleration of ageing of the extremities bone system in representatives of physical labour as compared with office workers. So the significance of spectal physical exercises compensating the progressing with age hypodynamia in persons of non-physical labour gets special importance.     

The relation between forearm and vertebral mineral density and fractures in postmenopausal women

Vertebral and forearm mineral density (VMD and FMD, respectively) were determined in 124 postmenopausal women with no crushed vertebrae or peripheral fractures, 51 who had sustained peripheral fractures only since the menopause, 62 with vertebral compression(s) only and 75 with both types of fracture.There was a very significant correlation between the two measurements in the whole set. The scatter could not be accounted for by methodological error but was partly accounted for by body weight, since VMD was related to body weight and FMD was not. Whatever criterion was used for the diagnosis of osteoporosis (whether fracture or density) the percentage of misclassified cases was very similar by the two methods. However, VMD was relatively more reduced than FMD in vertebral fracture cases and FMD was marginally more reduced than VMD in peripheral fracture cases.There is little to choose between vertebral and forearm density in the diagnosis of osteoporosis but vertebral densitometry is slightly superior to forearm densitometry in describing the severity of osteoporosis in vertebral fracture patients.     

The specificity of the deposition of intratracheally administered plutonium in different skeletal bones with a change in iron homeostasis]

A study was made of the distribution of plutonium-239 injected intratracheally within different bones of the skeleton, the iron status in the blood being changed. The iron preparation caused a 2.5-3-fold decrease in the plutonium loading onto cancellous bone tissue that displayed, in ordinary conditions, a higher tropism to the radionuclide than a cortical highly mineralized bone did.