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.     

Photoacoustic assessment of hemodynamic changes in foot vessels

Monitoring the blood supply in the lower extremities is critical for individuals who are vulnerable to vascular dysfunction. Current clinical approaches are ineffective in observing hemodynamic changes in peripheral vessels. In this paper, we investigate the potential of photoacoustic tomography (PAT) as an alternative way to in vivo monitor hemodynamic changes in foot vessels. High spatial and temporal resolution maps of hemoglobin in major arteries and veins are shown. Results from twelve human subjects are presented here to visualize vascular perfusion of healthy volunteers in two age groups (young vs aged). Significant differences between the two groups are observed and verify the declining in vascular function with aging, highlighting the potential of PAT as a new tool to evaluate vascular function in the lower extremities.      

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.     

Clinging ability is related to particular aspects of foot morphology in salamanders

The interaction between morphology, performance, and ecology has long been studied in order to explain variation in the natural world. Within arboreal salamanders, diversification in foot morphology and microhabitat use are thought to be linked by the impact of foot size and shape on clinging and climbing performance, resulting in an ability to access new habitats. We examine whether various foot shape metrics correlate with stationary cling performance and microhabitat to explicitly quantify this performance gradient across 14 species of salamander, including both arboreal and nonarboreal species. Clinging performance did not correlate with foot shape, as quantified by landmark‐based geometric morphometrics, nor with microhabitat use. Mass‐corrected foot centroid size and foot contact area, on the other hand, correlated positively with clinging performance on a smooth substrate. Interestingly, these foot variables correlated negatively with clinging performance on rough substrates, suggesting the use of multiple clinging mechanisms dependent upon the texture of the surface. These findings demonstrate that centroid size and foot contact area are more functionally relevant for clinging in salamanders than foot shape, suggesting that foot shape need not converge in order to achieve convergent performance. More broadly, our results provide an example of how the quantification of the performance gradient can provide the appropriate lens through which to understand the macroevolution of morphology and ecology.     

Detecting hemodynamic changes in the foot vessels of diabetic patients by photoacoustic tomography

Limb perfusion monitoring is critical for diabetes mellitus (DM) patients as they are vulnerable to vascular complications due to prolonged hyperglycemia. However, current clinical approaches are ineffective in vascular imaging and in assessing vascular function in lower limbs. In this work, a concave ultrasound transducer array‐based photoacoustic tomography (PAT) system was used to image the foot dorsal section of a subject, and a total of seven DM patients and seven healthy volunteers were enrolled in this study. Hemodynamic changes in foot vessels during vascular occlusion as well as oxygen saturation (SO₂) in rest were analyzed for both groups. The results obtained showed that DM patients have a unique peripheral hemodynamic response to occlusion and a lower level SO₂, compared to that for healthy subjects. This suggests that PAT has the potential to detect vascular dysfunction in DM patients and to measure the effect of treatment.     

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.     

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.     

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.