Evolutional and biological aspects of placentophagia

Over the last 30 years it could be observed that a very small minority of modern humans consumes the human placenta that belongs to the afterbirth. This behavior, which is known by the technical term of placentophagia, is the focal point of the present essay. Placentophagia is a behavior common among almost all kinds of mammals, even primates can be observed ingesting at least amniotic fluid during the birth. However, humans of traditional human cultures consume the afterbirth only in rare cases. In detail, the present essay discusses the hypothesis that human placentophagia has a phylogenetic basis and the hypothesis that human placentophagia is physiologically reasonable. It is concluded that the behavior of the human placentophagia neither possesses a phylogenetic basis nor can be regarded as physiologically reasonable.     

Age-related changes in the cell kinetics of rat foot epidermis

The durations of the cell cycle and its component phases have been determined for the basal layer of the epidermis of the skin from the upper surface of the hind foot of the rat using single pulse [3H]-thymidine labelling and the percent labelled mitosis (PLM) technique. Rats of three age groups were used, namely 7, 14 and 52 weeks. The duration of DNA synthesis (Ts) and the G2 plus M phase (TG2 + M) were comparable in 7-week and 52-week-old rats (P greater than 0.1). The major difference between 7-week and 52-week-old rats was in the duration of the G1 phase (TG1). In 7-week-old rats TG1 was 15.0 +/- 0.8 h and in 52-week-old rats TG1 was 31.2 +/- 3.5 h. A consequence of this variation was that the overall duration of the cell cycle was longer in 52-week-old rats (53.9 +/- 5.3 h) than in 7-week-old rats (30.1 +/- 1.3 h). Difficulties were found in fitting a simple curve to the PLM data for 14-week-old rats. This suggests that the proliferative cell population of the epidermis of rats of this age group may be heterogeneous. A satisfactory fit to the data was obtained using a computer model which assumed that the proliferative population of the epidermis of 14-week-old rats was a mixture of cells with cell cycle parameters the same as those of the 7-week and the 52-week-old rats. These two sub-populations of relatively slowly and rapidly proliferating cells were present in the ratio of 2:1.     

Age-related changes in the cell kinetics of rat foot epidermis

Abstract. The durations of the cell cycle and its component phases have been determined for the basal layer of the epidermis of the skin from the upper surface of the hind foot of the rat using single pulse [³H]-thymidine labelling and the percent labelled mitosis (PLM) technique. Rats of three age groups were used, namely 7, 14 and 52 weeks. The duration of DNA synthesis (T_s) and the G₂ plus M phase (Tg₂± m) were comparable in 7-week and 52-week-old rats ( P > 0–1). The major difference between 7-week and 52-week-old rats was in the duration of the G₁ phase (Tg₁). In 7-week-old rats Tg₁ was 15.0 ± 0.8 h and in 52-week-old rats Tg₁ was 31.2 ± 3.5 h. A consequence of this variation was that the overall duration of the cell cycle was longer in 52-week-old rats (53.9 ± 5.3 h) than in 7-week-old rats (30.1 ± 1.3 h).
Difficulties were found in fitting a simple curve to the PLM data for 14-week-old rats. This suggests that the proliferative cell population of the epidermis of rats of this age group may be heterogeneous. A satisfactory fit to the data was obtained using a computer model which assumed that the proliferative population of the epidermis of 14-week-old rats was a mixture of cells with cell cycle parameters the same as those of the 7-week and the 52-week-old rats. These two sub-populations of relatively slowly and rapidly proliferating cells were present in the ratio of 2:1.     

Reversible changes of protein configuration in stimulated nerve structures

Changes in the configuration of proteins were studied by the modifications of the ultraviolet absorption of their alkaline solutions. These were expressed in terms of the ratio O.D.(pH12)/O.D.(pH7), termed side-group ionization ratio (SGIR). This ratio showed two peaks; one at 300 to 305 mmicro is known to correspond to the phenolic hydroxyl of tyrosine and another at 245 mmicro seems to be caused by the ionization of the sulfhydryl group of cysteine. The SGIR of extracts from electrically stimulated nerve structures was found to be consistently and significantly higher than that of similar extracts from resting tissues. The phenomenon was observed in isolated nerves (frog and rat sciatic) stimulated in vitro and in the cerebral cortex of cats, dogs, and rats after stimulation of their afferents. The increase in SGIR was reversible if the stimulated structures were allowed to rest. Prolonged stimulation, in addition to causing structural changes, also caused breakdown of proteins and the appearance of proteolytic activity. The latter, studied on a synthetic substrate, could be detected even after shorter stimuli, together with configurational changes but without proteolysis. The structural changes detected with the spectrophotometric method are closely related to reversible denaturation as produced by urea. The changes probably involve rupture of hydrogen bonds which loosens the protein molecule and perhaps changes its affinity for different ions. It is possible that such a process may play a role in the mechanism of excitation.     

Ultrastructural aspects of the reversible nature of sclerotic changes in the liver

Experiments on mice have demonstrated ultrastructural changes in collagen and hepatocytes during reverse development of liver cirrhosis. Progressive lysis of collagenous fibers has been noted. Changes in hepatocytes point to a rise in the synthetic and endocytosis activity in these cells. It is suggested that exocellular lysis of collagen in the process under consideration is initiated by collagenase whereas subsequently it takes place under the action of lysosomal enzymes secreted by hepatocytes to the exocellular space.     

Age-related changes of the bones of the leg, foot and ankle joint in pole-vaulters

The data on age changes occurring in the height of the articular cleft of the talocrural joint, in morphological components of the diaphysis of the crus and foot bones have been presented in pole-jumpers and in non-sportsmen at the age of 13-21 years. Roentgenological, roentgenogrammetric and x-ray densitometric methods have been used. At the age of 14-15 years the greatest changes in the talocrural joint, crus and foot bones are noted.     

Dynamic changes in microtubule configuration correlate with nuclear migration in the preblastoderm Drosophila embryo

Drosophila embryogenesis is initiated by a series of syncytial mitotic divisions. The first nine of these divisions are internal, and are accompanied by two temporally distinct nuclear movements that lead to the formation of a syncytial blastoderm with a uniform monolayer of cortical nuclei. The first of these movements, which we term axial expansion, occurs during division cycles 4-6 and distributes nuclei in a hollow ellipsoid underlying the cortex. This is followed by cortical migration, during cycles 7-10, which places the nuclei in a uniform monolayer at the cortex. Here we report that these two movements differ in their geometry, velocity, cell-cycle dependence, and protein synthesis requirement. We therefore conclude that axial expansion and cortical migration are mechanistically distinct, amplifying a similar conclusion based on pharmacological data (Zalokar and Erk, 1976). We have examined microtubule organization during cortical migration and find that a network of interdigitating microtubules connects the migrating nuclei. These anti-parallel microtubule arrays are observed between migrating nuclei and yolk nuclei located deeper in the embryo. These arrays are present during nuclear movement but break down when the nuclei are not moving. We propose that cortical migration is driven by microtubule-dependent forces that repel adjacent nuclei, leading to an expansion of the nuclear ellipsoid established by axial expansion.     

Some aspects of secular changes in Hungary over the twentieth century

Growth and maturation are considered the most reliable indicators of health status. Their progression rates in turn are strongly influenced by nutrition and socio-economic status, a well-documented relationship. The pattern of the so-called positive secular changes, i.e. the increase in size and earlier maturation, fits the populations' historical model of economic development very well. The historical, political and economic changes occurring in this century in Hungary have had a remarkably strong impact. Until World War I Hungary was an agrarian part of the Austro-Hungarian monarchy, its ethnic composition was most variegated. Both World Wars caused fundamental changes, namely in respect of post-war Hungary they were associated with marked territorial losses and considerable population mobility. In interpreting the developmental differences in the data collected before and after these wars one should take account of the important facts that, in addition to the changes in socio-economic conditions, affected the gene pool of the populations in Hungary. Over the past 100 years profound changes have occurred in the mean body size, growth rate and timing of maturation of the country's population. This paper is a brief analytic summary of the tendencies observed in adult stature, maturation and some socio-economic conditions. It also compares the cohorts of sub-populations as reflected by the reviewed reports. In summarizing the change in adult stature estimated by the data on recruits, soldiers and students of higher education, it could be stated that adult mean stature had become markedly taller in Hungary since the end of the fifties. However, any estimation of the absolute increment and the exact rate is severely biased by the variable character of the samples' representativeness. Similar problems arose in dealing with sexual maturation, because the retrospective and status-quo methods of assessment were found incomparable. Nevertheless, menarche was observed to have shifted to an appreciably younger age lately, a trend that by the end of the 20th century seemed to have reached a more or less stable level.     

Evolutional Genetics and Diseases of Civilization

Inclination for hyperinsulinemia that was formed in the human population at early stages of development and was fixed genetically in the process of evolution is suggested to underlie pathogenesis of the currently most widely spread diseases of the cardiovascular system (atherosclerosis and hypertension) as well as diabetes mellitus of the 2 type and obesity that are concomitant with a high frequency. Under conditions of civilization, chronic hyperinsulinemia can develop in response to the regularly excessive nutrition. The consequence of the excessive food consumption and the chronic hyperinsulinemia can be overcrowding with lipids (triglycerides) of adipose tissue—the organism lipid store. The natural protective reaction of the cell that contains the limitedly possible amount of lipids is a decrease of the number of insulin receptors and development of insulin resistance. The insulin resistance, in turn, provides the appearance of hyper- and dislipoproteinemia alongside with hyperglycemia. One of the most clinically significant ways of achievement of homeostasis is storage of lipids in the arterial wall. Atherogenic and other concomitant metabolic disorders, specifically changes of blood coagulation properties providing susceptibility to hypercoagulation, affect the blood rheological properties and seem to lead to pathology of the entire vascular system: chronic venous insufficiency, disturbance of microcirculation, and arterial atherosclerosis. There is substantiated the natural interconnection of atherosclerosis, type 2 diabetes, obesity, and arterial hypertension that at present are accepted as the main clinical manifestations of the so-called “metabolic syndrome.” It is suggested that the basis for arterial hypertension might be disturbances of microcirculation leading to an increase of peripheral vascular resistance as well as insufficiency of renal blood supply at the level of arterial and microcirculatory bed.__________Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 41, No. 2, 2005, pp. 186–191.Original Russian Text Copyright © 2005 by Liberman.     

Conformational changes in the foot protein of the sarcoplasmic reticulum assessed by site-directed fluorescent labeling.

Ca2+ release from sarcoplasmic reticulum during excitation--contraction coupling is likely to be mediated by conformational changes in the foot protein moiety of the triadic vesicles. As a preparative step toward the studies of dynamic conformational changes in the foot protein moiety, we have developed a new method that permits specific labeling of the foot protein moiety of the isolated membranes with a fluorophore. A novel fluorescent cleavable photoaffinity cross-linking reagent, sulfosuccinimidyl 3-((2-(7-azido-4-methylcoumarin-3-acetamido)ethyl)dithio)propionate (SAED), was conjugated with site-directing carriers, polylysine (Ca(2+)-release inducer) and neomycin (Ca(2+)-release blocker). The conjugates were allowed to bind to polylysine- and neomycin-binding sites of the heavy fraction of SR (HSR). After photolysis, the cross-linked reagent was cleaved by reduction and the fluorescently labeled HSR was separated from the carriers by centrifugation. These procedures led to specific incorporation of the methylcoumarin acetate (MCA) into the foot protein. Polylysine and neomycin bound to different sites of the foot protein, since neomycin, at release-blocking concentrations, did not interfere with polylysine binding. The fluorescence intensity of the foot protein labeled with the carrier, neomycin, showed biphasic changes as a function of ryanodine concentration (increasing up to 1 microM ryanodine and decreasing above it), while with the carrier polylysine, ryanodine induced no change in fluorescence intensity. In contrast, the fluorescence intensity of the foot protein labeled with each of the two carriers, neomycin and polylysine, showed almost identical calcium dependence (first increasing from 0.1 microM to about 3.0 microM calcium concentration, and then decreasing at higher calcium concentrations).(ABSTRACT TRUNCATED AT 250 WORDS)