Wave-like Movements Research Articles

Slow cellular dynamics in MDCK and R5 cells monitored by time-lapse atomic force microscopy

We have examined dynamic events that occur on a time scale of minutes in an epithelial monolayer of Madine-Darby Canine Kidney (MDCK) cells and in ras-transformed MDCK cells by atomic force microscopy (AFM). Cells were imaged under physiological conditions, and time-lapse movies representing approximately 60 s real time per frame were assembled. In normal MDCK cells, two types of protrusions in the apical plasma membrane exhibit dynamic behavior. First, smooth bulges formed transiently over the time scale of minutes to tens of minutes. Second, spike-like protrusions appear initially as bulges, extend well above the apical surface and, finally, seem to detach. R5, an oncogenic transformant derived from MDCK cells, grows very flat on glass. During AFM imaging, these cells sometimes round up and detach from the substrate. In light microscopic observations of parallel preparations, cells rarely detach, suggesting that this is an active response of these cells to irritation by the AFM tip. R5 cells often extend processes that are supported by actin stress fibers. During imaging with the AFM, these processes withdraw at a rate of 1-5 microns/min, similar to that observed by light microscopy. During the withdrawal, movement of the stress fibers can be clearly seen. In the flat periphery of these cells, the transport of intracellular particles along cytoskeletal elements was seen. In addition, we have observed two types of wave-like movements through the cell, which appear to be an organized rearrangement of cytoplasm. One type of wave moves radially out from center of the cell while the other moves circularly along the cell periphery.

Sand waves along the Dutch coast

Sand waves, defined as longshore wave-like movements of the shoreline, measured in a horizontal plane, are described along several stretches of the shoreline of The Netherlands. They have a celerity in the order of 50–200 m yr −1, a period of 50–150 years and an amplitude of 30–500 m. They are found along the whole Dutch shoreline. Analysis of sand waves shows that the assumed effect of groins might be very small along this shoreline. There are indications that groins did not have any long-term effect on coastal regression.

Changes in the motility pattern of human spermatozoa during in vitro incubation.

Suspensions of capacitating human spermatozoa were analyzed for movement characteristics using high-speed videomicrography. The status of the acrosome reaction was also assessed by the zona-free hamster ova penetration test. (1) Movement characteristics of human spermatozoa were classified into 4 types (A, B, C, D). Type A: The movement was active, but its progressive orientation was irregular. Type B: The spermatozoa moved with a wide amplitude of the end of tail. Type C: The amplitude of the tail decreased, and the linear velocity of progression increased. Type D: The whole part of tail showed wavelike rhythmical movements, and the velocity more increased. (2) Movement characteristics of human spermatozoa in vitro gradually changed from Type A to B, C and D. As the spermatozoa classified Type D moved very powerfully and this motility pattern was obviously different from the other types, it was considered hyperactivation of human spermatozoa. The Type D was found from 2 or 3 hr of incubation, and after 3 or 4 hr most of the spermatozoa showed Type D. (3) The motility pattern of human spermatozoa changed to the Type D before the spermatozoa penetrate into zona-free hamster oocytes. It suggested that the hyperactivation occurred before the acrosome reaction takes place.

A fundamental study of injectable collagen in vocal rehabilitation

Vocal fold augmentation therapy has been accepted as a choice of treatment for glottic insufficiency due to unilateral recurrent nerve paralysis, vocal fold atrophy and sulcus vocalis. Various injectable materials have so far been investigated and clinically utilized. Although silicone and teflon are materials most widely used currently, our clinical experiences have indicated that they are not totally dependable because of such problems as tissue rection and instability of the volume.Recently, atelocollagen extracted from young calf skin has been reported to be an excellent injectable material and its application to phonosurgery has been described by Ford without investigating its long-termed safety and histocompatibility, and its effect on the vocal fold vibrations after the injection.This lack of investigation on the injection therapy of atelocollagen has prompted the animal experiments to study histological attitude of collagen in the vocal fold and the vocal fold vibration after the injection. The collagen at a concentration of 35, 20 and 10mg/ml were injected into canine vocal folds. The follow up period ranged from 3 days to 9 months after the injection. It was revealed that the most suitable concentration of the collagen for maintenance of the contour of the vocal fold was 35mg/ml, although the volume of the vocal fold tended to decrease very slightly during three days after the injection. Histological studies confirmed no inflammatory reaction in the surrounding tissue after the injection and no migration of collagen during the following-up period. Vibrations of the injected vocal folds during phonation were photographed with an ultra-high speed motion camera and frame-by-frame analyses were done. Mucosal wave-like movements were satisfactority preserved even when the collagen stayed in the submucosal superficial layer of the vocal fold. The result indicates that atelocollagen can be injected into any layers of the vocal fold without specific technical care. Owing to this advantage, use of the atelocollagen will expand indication of augmentation therapy.

Motile components in early rat spermatids

In early rat spermatids, two distinctly different kinds of movements of cell components were detected by video-analysis. The primary flagellum, a typical 9 + 2 axonema, is capable of inducing wave-like movements in three dimensions, unlike late spermatid forms, which display motility of the now thickened flagellum only by repeated bending of its extreme part. Additionally, at the apical regions of spermatids of the same early stage, cytoplasmic protrusions executed rhythmic movements at a frequency of almost three times per second. The two kinds of motility of the different components in the same cell type are thought to be involved in normal orientation and transfer of spermatids in the tubulus seminiferus during their differentiation to sperm.

Movements of airglow structures within the intertropical arc observed from southern Kenya

6300 Å airglow observations from Olorgesailie, Kenya (1.6°S, 36.4°E) show two types of movement within the southern intertropical red arc. The arc moves as a whole equatorwards at a rate of 3–4° per hour before local midnight tending to reverse direction after midnight. The second movement is an east-west wave propagation with a wavelength of approximately 600 km and a velocity of 120–130 m s −1. The wavelike movements have properties similar to medium scale atmospheric gravity waves.

Cytokinetic activities in a human cell line: the midbody and intracellular bridge

The midbody and intercellular bridge of D-98S cells were studied by time lapse cinemicrography. Before separation interconnected daughter cells tended to move in opposition to each other, maintaining tension across the bridge and, in some cases, lengthening the bridge. Cell separation was preceded by a reduction in width of the bridge, on one or both sides of the midbody, to a cytoplasmic strand less than 0-5 μ wide, which was then stretched and broken by movements of the daughter cells, completing cytokinesis. Wave-like movements were observed to pass along longer intercellular bridges from the midbody to the daughter cells. This activity was judged to be involved with the retraction of cytoplasm from the bridge into the daughter cells. Wave activity was disrupted by the drug cytochalasin B.

Effect of influenza virus on cilia and epithelial cells in the bronchi of mice.

In order to determine the effect of infection with influenza virus on bronchial cilia of the mouse, ciliary beat has been visualized directly by microscopic examination of the bronchi in slices of fresh lung. Cilia have been shown also in sections of fixed tissue by the use of special silver staining methods. The results have shown persistence of the cilia in spite of severe viral infection and indicate that the lowered resistance to secondary pneumococcal infection which occurs in influenzal pneumonia of the mouse is not due to interference with the ciliary mechanism. By a process of exclusion, the findings give further support to the theory that lowered resistance to pneumococcal infection in influenzal pneumonia is due to edema fluid in the viral lesion furnishing a culture medium for inhaled pneumococci. A widely used method for evaluation of ciliary activity on respiratory epithelia has been the microscopic observation of wave-like movements in reflected light. This activity was observed readily in the bronchi of mice but evidence was obtained showing that at this site it was due to something other than ciliary beat. Further histopathologic observations were made in order to define the lesion of the bronchial epithelium that would permit sparing of ciliated cells. In addition to usual techniques, mice were injected with colchicine for estimation of the rate of cellular proliferation and were exposed to a large dose of roentgen rays to eliminate polymorphonuclear leucocytes. Stains for mucous and for mitochondria were done also. The evidence obtained favors the theory that the viral infection does not destroy any of the cells of the bronchial epithelium. Inclusion bodies were found in the cytoplasm, making it seem likely instead that viral particles grow in colony-like aggregations and that liberation of virus into the lumen takes place not only by simple extrusion of inclusions but also by detachment of inclusion-laden globular portions of the cytoplasm.

The Long Waves in Economic Life

I. The idea that the dynamics of economic life in the capitalistic social order is not of a simple and linear but rather of a complex and cyclical character is nowadays generally recognized. Science, however, has fallen far short of clarifying the nature and the types of these cyclical, wave-like movements. When in economics we speak of cycles, we generally mean seven to eleven year business cycles. But these seven to eleven year movements are obviously not the only type of economic cycles. The dynamics of economic life is in reality more complicated. In addition to the above-mentioned cycles, which we shall agree to call intermediate, the existence of still shorter waves of about three and one-half years' length has recently been shown to be probable.1

Cycles of Crime

One of the customary ways to study social behavior is to measure its operation over a period of time. This interest in the quantitative analysis of human society has led to studies of birth and death rates, poverty, marriage, divorce, crime illegitimacy, and so on.2 In the world of commerce, the business cycle has become a standard index for measuring prosperity, depression, and related conditions. These indexes confirm the notion of social change and serve a useful purpose in a preliminary analysis of the causes of social change. It has long been suspected that crime tends to move in cycles. This hypothesis is primarily responsible for the explanation of an increase or decrease in crime througli fluctuations in economic conditions. Little accurate information has been available, however, to verify this relationship. Prison commitment records which are most frequently used to indicate cyclical movements in crime may not be sufficiently representative either of crime in general or of the less serious crimes, though the latter may constitute the greater proportion of all crimes and be consequently of great significance. If comparisons are made between crime and other social activities, it is necessary to have a representative index of the various kinds of crime. It is then possible to determine whether crime does move in cycles and the correspondence between these cycles and other social activities. An unusual increase or decrease in crime constitutes a cycle. These cycles are popularly known as crime waves. An analysis of the wave-like movements in crime furnishes three significant keys to an understanding of crime conditions. In the first place, they indicate in a definite period of time how much crime tends to vary above or below a general increase or decrease in crime. Secondly, the cycles of special classes of crime show what types of crime are responsible for a general cycle of increase or decrease. As a third contribution, it is possible to compare these various types of crime and to relate their movements with indexes of other social or economic conditions. In this connection these cycles help to determine the kinds of crime

The action of bile and some of its constituents upon intestinal peristalsis and the circulation

In their experiments with a Vella fistula, Fubini and Luzzati found that a pea, fastened to a thread, passed along the bowel more quickly when ten to fifteen minutes previously they had injected two grams of bile. C. Eckhard, of Giessen, also studied the influence of the bile upon the peristaltic movement of the small intestine. Eckhard experimented upon rabbits. He used a sodium chloride bath and studied the movements of the intestine in situ after opening the abdomen. After the injection into the duodenum of one cubic centimeter of bile of the rabbit the duodenum remained for ten minutes in absolute rest. He injected three c.c. of bile of rabbit, calf and sheep in different parts of the small intestine with the same result, the intestine remaining quiet fifteen to twenty minutes. If, however, the intestine remained for some time in the salt solution, it became more sensitive to the irritant. With the injection of large quantities of bile there was more frequently than before little wave-like movements, although Eckhard does not feel sure that this was the result of the bile injected. Drs. Hallion and Netter have studied the influence of bile on the peristalsis of the intestine. They operated on dogs curarized or narcotized by chloralose or by morphine and chloral. By a small button hole in the small (mainly in the duodenum) intestine they introduced a balloon which was connected with a water manometer by means of rubber tubing. The balloon was flexible rubber and mounted upon a metal tube perforated by a large number of lateral openings, which prevented bends of the balloon upon itself. The water manometer was connected with a Marey tambour which inscribed the movements.