Circulation in the lungs and microcirculation in the alveoli

Human lungs weighing ca 600 g permit the passage of 5–6 l of blood per minute. The blood capacity of the human lungs is about 0.5 l. Consequently, each 0.5 l of blood is during 5 s. The questions arise of how such a large mass of blood passes through such a small mass of lungs and what the reasons are for such a high rate of blood oxygenation. Since the structure of lungs in mammals is almost the same, we tried to solve these issues studying the rats, in which 20–22 ml of blood pass through the lungs of 1.5–2.0 g mass. A great blood flow appeared to be associated with a large diameter of the lung arterioles and a high rate of the blood flow in them. The high rate of oxygenation is accounted for by a special structure of alveoli and special conditions of the blood flow, which create ideal conditions for oxygen diffusion.     

Cutaneous calciphylactic reactions in the mouse and the rat and the effects of diphosphonates on the reaction in the rat

Calciphylaxis is a local tissue calcific reaction at the site of an injection of challenger substance given a critical time period after the oral administration of a sensitizer substance such as dihydrotachysterol (DHT), vitamin D or parathormone. Cutaneous calciphylaxis is readily induced in the rat but not in the mouse and this may be because, in the latter, the challenger substance is absorbed rapidly by macrophages. In the rat the administration of 500 micrograms/0.1 ml of DHT followed after 24 h by the subcutaneous (SC) injection of ferric chloride (FeCl3) (30 micrograms/0.1 ml) is followed rapidly by calcification of the SC site. There is an early transient acute inflammatory reaction with the incrustation of collagen fibres by the iron salt and an apparent exudation of calcium and phosphate ions from the bloodstream. These ions also become associated with collagen fibres. Two days after injection macrophages and multinucleated giant cells become the dominant cells. Calciphylaxis is a useful experimental model of ectopic calcification and is associated with an initial hypercalcaemia. The diphosphonates ethane-1-hydroxy-1, 1-diphosphonate (EHDP) and dichloromethylene diphosphonate (Cl2MDP) are effective inhibitors of the calciphylactic reaction when administered prior to the initiation of the experimental procedure.     

Verbal and visual cognition: Individual differences in the lab,in the brain,and in the classroom

In many ways, individuals vary in their thought processes, and in their cognitive strengths and weaknesses. Among the findings revealed by individual differences research, one major dividing line highlighted recurrently by decades of experimental studies is that between linguistically-mediated cognitive operations (verbal cognition), versus cognition, which primarily operates on visual – or visuospatial – representations (visual cognition). In this article, we review findings from three research areas—cognitive abilities, working memory, and task strategies—focusing on individual differences in verbal and visual cognition. In each area we highlight behavioral, neuroimaging, and classroom-based findings, bridging the perspectives of these different methodologies.     

Action prediction in the cerebellum and in the parietal lobe

The ability of the central nervous system to predict motor behaviour is a central issue in experimental and computational studies of motor control. The parietal cortex and the cerebellum have been proposed to play a role in sensorimotor prediction. Here we discuss the roles of these two brain regions in various aspects of sensorimotor prediction according to results of recent empirical studies using a variety of techniques including electrophysiology, psychophysics, functional neuroimaging and the investigation of neurological patients.     

Bathing before sleep in the young and in the elderly

In this study we investigated the effects of bathing on the quality of sleep in 30 elderly people (ages 65–83 years) and in 30 young people (ages 17–22 years) in their homes. Room temperature did not vary significantly during the nights that data were acquired, ranging from 8 to 12°C. After bathing and at the beginning of sleep, the mean (SE) rectal temperatures of the young and the elderly were 37.8?(0.08) and 37.5?(0.07)°C, respectively, and were higher by 0.7?(0.13) and 0.6?(0.07)°C, respectively, than when the subjects had not bathed. At the beginning of the sleep after bathing in the young subjects, skin temperature was 32.5?(0.24) and 1.5?(0.34)°C higher than when those subjects had not bathed. In the elderly, however, there were no significant differences in skin temperature with and without prior bathing because they used electric blankets during sleep. After bathing, the young people reported “warmth” in their hands and/or legs, while the elderly more often reported “good sleep” or “quickness of falling asleep”. During the first 3?h of sleep, body movements were less frequent after bathing for both the young and the elderly subjects. The results suggest that a bath before sleep enhances the quality of sleep, particularly in the elderly.     

Oxygen supply and uptake in the liver and the intestine

The oxygen supply to the liver was found to be dependent on the total blood flow only and not on the ratio of arterial to portal contribution. The mean value of O2-uptake in the liver, related to a blood flow of 110 ml/min - 100 g liver, amounted to 6.08 +/- 0.2 ml O2/min - 100 g liver (mean +/- S.E.M.). O2-uptake of the intestine was found to be 1.95 +/- 0.13 ml O2/min - 100 g tissue, related to a normal blood flow of 50 ml/min - 100 g tissue. With low oxygen supply O2 extraction in the liver reaches values of 97%, whereas the intestinal extraction does not surpass 75%. A rise in oxygen supply surmounting normal values does not increase the O2-consumption. Contrary to the intestinal circulation the liver showed no postocclusive vasodilatation. The oxygen debt was payed back by a greater extraction. The portal oxygen supply to the liver can markedly increase due to intestinal metabolic hyperemia. High O2-extraction capacity, rather than vasodilatation, is the main mechanism for matching hepatic oxygen supply with requirements. The hepatic venous blood may leave the liver with an extremely low O2-content.     

Cell degeneration and mitosis in the buccopharyngeal and branchial membranes in the mouse embryo

Summary The frequencies of cell degeneration and mitosis were investigated in the rupturing buccopharyngeal membrane (BPM) and in the persistent first branchial membrane (BM). In the BPM, cell degeneration starts many hours before rupture is visible, but mitotic figures are absent. In the BM this situation is reversed: mitotic figures are regularly observed, but a degenerating cell only occasionally. It is concluded that the ratio between the numbers of degenerating and dividing cells regulates the fate of both the BPM and the BM.