Changes in material and architectural properties of rat femoral diaphysis during ontogeny in hypophysectomized rats

Adenohypophyseal hormones are important for normal growth and maintenance of skeletal mass. From a mechanical point of view, the skeleton can be viewed as a biomechanically regulated structure, the strength of which depends on the intrinsic stiffness (material properties) and the spatial distribution (architectural properties) of the mineralized tissue. Both material and architectural properties of bone change during ontogeny. Both muscle strength and body weight, the main two types of load producing strain, remain practically unchanged in a young rat after hypophysectomy (HX). Therefore, this study was performed to analyse the effect of HX on bone development in a model in which the main loads on bone are almost constant from infancy to adulthood. Female rats were HX at 30 days of age. A basal control group (BC) was sacrificed on the same day. An age-matched control group (CON) was also included. HX and CON rats were sacrificed 5 months later. Mechanical properties of the right femur were determined using a three-point bending mechanical test. HX rats failed to gain body weight and body and femur length. Femur weight was about 1.09 times increased and femoral calcium content (left femur) was 2.25 times greater in HX than in BC rats. The load-capacity extrinsic properties (stiffness, elastic limit, and ultimate load) were 3.47, 3.42, and 3.11 times increased, respectively, in HX rats in relation to BC ones. Focussing on the intrinsic material properties, the cortical elastic modulus (E) was 10.73 and 2.54 times higher in HX rats than in BC and CON rats, respectively. In summary, HX in the rat induced the transformation of the juvenile femur to a type of adult bone characterised by its high mineral density and its unusual large modulus of elasticity in spite of cessation of lineal growth. These effects are probably due to secondary hypothyroidism induced by TSH deficiency and associated to increased collagen maturation and cross-linking, and degree of bone calcification.     

Changes in pyridinoline content of elastin during ontogeny

It has been shown that, contrary to desmosine and isodesmosine, the content of pyridinoline increases in elastin preparations obtained from rat and bovine aortae and from bovine ligamentum nuchae throughout the whole lifespan. The molar proportion of this cross-linking amino acid is within the range of 0.6–2.5 leucine equivalents per 1000 amino acid residues.     

Changes in the cytokine regulation of stem cell self-renewal during ontogeny

The last 10 years have seen the development of a quantitative assay that is specific for transplantable totipotent murine hematopoietic cells with durable in vivo blood-forming ability. Recently, this assay has been successfully adapted to allow the detection and enumeration of an analogous population of human hematopoietic stem cells using myelosuppressed immunodeficient (nonobese diabetic/severe-combined immunodeficiency) mice as recipients. Characterization of the cells detected by this assay indicates their close relationship in both mice and humans with cells detected in vitro as long-term culture-initiating cells (LTC-IC). Culture conditions have now been identified that support a significant net expansion of these cells from both species. More detailed analyses of the cytokine requirements for this response indicate that the viability, mitogenesis and maintenance of LTC-IC function by human CD34+ CD38- cells can be independently regulated by exogenous factors. Superimposed on this uncoupling of hematopoietic stem cell "self-renewal" and proliferation control is a change during ontogeny in the particular cytokines that regulate their responses. These findings unite stochastic and deterministic models of hematopoietic stem cell control through the concept of a molecular mechanism that actively blocks stem cell differentiation and must be maintained when these cells are stimulated to divide by exposure to certain types and concentrations of cytokines.     

Changes in reactivity of pial microvessels of rats during ontogeny

Research Institute of Child and Adolescent Physiology, Academy of Pedagogic Sciences of The USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Kupriyanov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 105, No. 5, pp. 520–522, May, 1988.     

Changes in some physicochemical properties of cerebral cortical proteins during clinical death and resuscitation after mechanical asphyxia

During the period of clinical death from mechanical asphyxia in dogs, changes take place in the physicochemical properties of protein of the postimitochondrial supernatant from brain gray matter homogenates. The densitogram obtained by electrophoresis of the proteins in polyacrylamide gel is modified. The total protein concentration after centrifugation and total lactate dehydrogenase (LD) activity are reduced. The combined fraction of unadsorbed and globulins is reduced after adsorption on DEAE-Sephadex A-50 and the activity of LD isozymes (3+4+5) is considerably reduced. The disturbance of the behavior of proteins in sedimentation and electrical fields and changes in their adsorption properties, showing specific features at different times of clinical death, play an important role in the formation of the irreversible changes in the gray matter of the brain tissue. In the early recovery period successive restoration of the adsorption and sedimentation properties of the protein is observed, whereas the electrophoretic spectrum does not return to normal during the first day.Scientific-Research Laboratory of General Resuscitation, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. A. Negovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 87, No. 6, pp. 539–542, June, 1979.     

Changes in number of neurotransmitter receptors on mouse lymphocytes during ontogeny

Institute of Immunology, Ministry of Health of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR M. E. Vartanyan.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 110, No. 11, pp. 515–517, November, 1990.     

Changes in the electrophoretic mobility of mouse lymph node lymphocytes during ontogeny.

The electrokinetic properties of peripheral lymph node (LN) cells from C3H and nude mice aged 1, 3 or 10 weeks, were investigated by means of preparative and analytical cell electrophoresis. Two groups of cells were distinguishable throughout the age interval examined. The first group, with low-mobility (LM) included the majority of surface-immunoglobulin positive lymphocytes, was predominant in athymic nude mice and is thus likely to represent B cells. The other group, with higher mobility (HM), was sensitive to anti-Thy 1-2 serum, made up the major LN population in C3H mice and normal nude littermates and thus probably corresponds to T cells. In C3H mice, the relative proportion of LM cells was found to increase with age of LN donors (from 9-22%). Moreover, significant alterations in the mean electrophoretic mobility (EPM) of both lymphocyte populations were detected in the course of development. While the EPM of LM cells diminished from 0-81-0-70 micrometer.s-1.V-1.cm, that of HM cells increased from 1-11-1-22 micrometer.s-1.V-1.cm as the animals grew from 1-10 weeks. These observations indicate a relationship between the degree of maturity of peripheral B- and T-cell populations and their electrokinetic properties.     

Changes in the immunologic status reflected in the physicochemical characteristics of cells of the immunocompetent system during carcinogenesis

The state of the cell population of the lymph nodes and thymus was studied by the fluorescent probe method in rats with sarcoma of the thigh induced by dimethylbenzanthracene. Statistically significant changes were found in the uptake of the negatively charged probe 1-aniline-8-naphthalene-sulfonate (ANS) in cell suspensions depending on the stage of development of the sarcoma. In the early stages of carcinogenesis cell forms with a less hydrophobic surface and containing fewer binding sites were observed to appear. It is suggested that these cells belong to the immature category. It is concluded that the fluorescent probe method is suitable for recording changes in the immunologic status of the organism during carcinogenesis.Scientific-Research Laboratory of Experimental Immunobiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. N. Zhukov-Verezhnikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 1, pp. 73–75, January, 1977.     

Changes in skeletal muscle myosin heavy chain isoform content during congestive heart failure

Recent investigations have suggested that changes in contractile protein expression contribute to reductions in skeletal muscle function during congestive heart failure (CHF). Myosin heavy chain (MHC), a major contractile protein, has been shown to undergo alterations in protein isoform expression during CHF. The purpose of this investigation was twofold: (1) to determine whether muscles of the same functional group undergo similar changes in MHC expression, and (2) determine whether the magnitude of alterations in MHC is related to the severity of CHF. Using the rat coronary ligation model, mild and severe forms of CHF were produced and muscles of the plantar flexor group were analyzed. Whole-muscle MHC isoform proportions were not altered in the soleus and white gastrocnemius muscle, however significant increases in the percentage of fast MHC isoforms (7–9% increases in MHC IIx and IIb expression) were found in the red gastrocnemius muscle. In addition, there were significant proportional increases (8%) in MHC type IIb at the expense of MHC type IIx in the plantaris muscle. Many of the changes in the proportions of MHC isoforms were significantly correlated with indices of CHF severity. This indicates that changes in skeletal muscle MHC isoform expression are related to the severity of CHF and suggests that some peripheral skeletal muscles are more susceptible to shifts in MHC expression due to CHF. These changes in MHC isoform expression may contribute to alterations in the physiological performance of skeletal muscle and exercise capacity during CHF. Electronic Publication     

Changes in template properties of chromatin during aminoazo-carcinogenesis

Male rats were kept on a diet containing the carcinogen 3-methyl-4-dimethylaminoazobenzene. No difference from the control was found either in the electrophoretic spectrum of the total protein of deoxyribonucleoproteins (DNP) or nonhistone proteins, or in the character of the melting curves of DNA and DNP, or in the template ability of DNA isolated from rat liver. DNP of tumor tissue functioned more actively as template for RNA synthesisin vitro in a system with animal or bacterial RNA-polymerase, with low concentrations of substrates (of the order of 2·10^–5 M), but RNA synthesis did not differ from the control in the presence of high concentrations of each of the substrates (2·10^–3 M). During lysis of the nuclei in a solution with alkaline pH the percentage of activity of RNA-polymerase that could be extracted from the complex with chromatin decreased considerably if the rats were fed with the carcinogen.Laboratory of Biochemistry of Tumors, Institute of Experimental and Clinical Oncology, Academy of Medical Sciences of the USSR, Moscow. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 3, pp. 363–365, March, 1976.     

Postural and lateral asymmetries in the ontogeny of handedness during infancy

Ten newborn infants who preferred to lie with their heads turned rightward and ten who preferred to lie with their heads turned leftward had their hand-use preferences for reaching assessed at 8 different ages during the period 12-74 weeks postpartum. Eighteen infants maintained stable hand-use preferences throughout this period and the direction of their neonatal head orientation preference predicted the hand they preferred to use. The neonatal head-turn preference was maintained through the first 2 months and induced lateral asymmetries in visual regard and motor control of the hands. These lateral asymmetries are plausible contributors to mechanisms linking neonatal headturn preference to infant hand-use preference. Thus, the dextral bias in handedness may be derived, in part, from the rightward bias in neonatal head-turn preference.