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At least 55 records · Page 3Linked to original sources
PubMed1969

The "vesicle in a basket". A morphological study of the coated vesicle isolated from the nerve endings of the guinea pig brain, with special reference to the mechanism of membrane movements.

Five points are discussed regarding the vesicular structure isolated by fractionation techniques from the brain and liver of the guinea pig. 1. One type of vesicle, fixed by OsO(4) and shown in thin sections, is identified with the coated vesicle that has been observed in many varieties of tissues. 2. The vesicle contained in a spherical polygonal "basketwork" shown by the negative-staining techniques is identical with the coated vesicle shown in sections. 3. Despite minute observation of this basketwork we could not confirm the existence of "hairlike projections" extending from the convex cytoplasmic surface of the vesicle. We are inclined to believe, therefore, that the hairlike projections are actually the superimposed visual images of the regular hexagons and pentagons of the network composing the basketwork. 4. We repeat the hypothesis originally advanced by Roth and Porter (1) that the "coating" of the coated vesicle plays a role in the mechanism of the infolding and fission of the membrane; we suggest that these events are caused by the transformation of the regular hexagons (of the coating) into regular pentagons. 5. Finally, we make a suggestion as to the nature of those vesicles which have on their surface subparticles which look like "elementary particles (2)."

Animals↗
PubMed1989

High-resolution low-temperature scanning electron microscopy for observing intracellular structures of quick frozen biological specimens.

Intracellular structures of rapidly frozen biological tissues were observed in 3-D under a low-temperature scanning electron microscope using a newly developed side-entry type cryo-holder. The present low-temperature SEM is simple, easy to operate and effective for observing biological materials at high magnification. Biological tissues (the pancreas, small intestine, brown adipose tissue and Harderian gland) freshly removed from the mouse were immediately frozen in liquid propane cooled with liquid nitrogen, and their surfaces were manually fractured using a precooled razor blade in liquid nitrogen before introducing the cryo-holder into the SEM. When intracellular structures were revealed after appropriate sublimation, the specimens were coated with gold using a metal evaporator fitted to the side of the microscope column at one of the specimen chamber ports. The cryo-holder was connected to a copper braid coming from a liquid nitrogen reservoir to maintain a low temperature. Using this method, intracellular structures such as the mitochondria and endoplasmic reticulum were demonstrated at high magnifications. Ribosomal granules were discerned on the rough endoplasmic reticulum of the pancreatic acinar cells. Granular substances, presumably elementary particles, were also recognized on the mitochondrial cristae of the brown adipose tissue. The method was particularly effective for studying the 3-D configuration of lipid droplets which had been difficult to preserve by chemical fixation.

Adipose Tissue, Brown↗
PubMed1995

Big-bang nucleosynthesis and the baryon density of the universe.

For almost 30 years, the predictions of big-bang nucleosynthesis have been used to test the big-bang model to within a fraction of a second of the bang. The agreement between the predicted and observed abundances of deuterium, helium-3, helium-4, and lithium-7 confirms the standard cosmology model and allows accurate determination of the baryon density, between 1.7 x 10(-31) and 4.1 x 10(-31) grams per cubic centimeter (corresponding to about 1 to 15 percent of the critical density). This measurement of the density of ordinary matter is pivotal to the establishment of two dark-matter problems: (i) most of the baryons are dark, and (ii) if the total mass density is greater than about 15 percent of the critical density, as many determinations indicate, the bulk of the dark matter must be "non-baryonic," composed of elementary particles left from the earliest moments.

Astronomical Phenomena↗
PubMed1988

Deafferentation pain in man.

Pains of various etiologies are described in so many overlapping ways that verbal descriptions alone do not permit a valid distinction between those pains associated with neurological injury (with or without sensory loss) and those associated with neurological compression. Nor does the fact of some sensory loss plus pain constitute a useful classification to determine either the mechanism of the pain or its treatment. Progress is more likely to ensue if we seek to characterize in detail each type of painful lesion. Evidence for these conclusions is drawn from cases of brachial plexus injury, trigeminal rhizotomy and tractotomy, postcordotomy dysesthesia and central pain treated by regional guanethidine block. Examples of the value of totally innovative approaches are drawn from the physics of elementary particles.

Afferent Pathways↗
PubMed1986

Physical bases for a triad of biological similarity theories.

The dimensional analysis of physics, based on the MLT-system (M = mass, L = length, T = time), can be applied to the living world, from mycoplasmas (10(-13) g) to the blue whales (10(8) g). Body mass (M), or body weight (W), are utilized as convenient reference systems, since they represent the integrated masses of all elementary particles--at the atomic level--which conform an organism. A triad of biological similarities (mechanical, biological, transport) have been previously described. Each similarity was based on two postulates, of which the first was common to all three, i.e., the constancy of body density; whereas the second postulates were specific for each of the three theories. In this study a physical foundation for these second postulates, based on three universal constants of nature, is presented, these are: 1) the acceleration of gravity (g = LT-2); 2) the velocity of light (c = LT-1); and 3) the mass-specific quantum (h/m = L2T-1). The realm of each of these biological similarities is the following: 1) the gravitational or mechanical similarity (where g = constant), deals mainly with the relationship between a whole organism and its environment, particularly with locomotion. The acceleration of gravity (g) is also one of the determining factors of the "potential" energy (E = m.g.H), where m is the mass, and H is the height above the reference level; 2) the electrodynamic similarity (formerly biological similarity), (c = constant), is able to quantitatively define the internal organization of an organism from both a morphological and a physiological point of view.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Transport↗
PubMedDate not supplied

[Molecular computer. Biological physics and physics of the real world].

Any mind (man or computer) using Physical laws is a part of physical world, and thus it is necessary to correct physical laws for taking into account influence of the work of real limited computer on the predicted result. If we suppose that univerce was constructed to be supreme regular for mind, then this correction is negligible and on principle there is possibility to calculate relation between fundamental physical and biophysical constants. Two main principle are proposed: 1. The principle of minimum action and uncontrole influence of mind. 2. The maximum asymmetry of elementary particles, which are allowed by first principle. The first principle requires the upper and the lower limits for all physical values, and first of all the upper limit for velocity (c) and the lower limit for action (h). The second principle allows to construct the minimal physical elements for mind.

Biophysical Phenomena↗
PubMed1980

[Cutaneous argyria: an electron microscopic study of four eases with microanalysis X study of one case (author's transl)].

This study was done in order to follow the fate of silver in the dermis of chronic argyria. Silver was easily recognizable in the tissue as irregular aggregates of elementary granules round or ovoid in shape, ranging from 30 to 40 mm in size. The microanalysis X showed that the metal was bound with sulfur. In the cases of recent intoxication, the main location of silver was intracellular: the granules were found in the lysosomes as elementary particle or as dense heterogen bodies. In the cases where intoxication had been stopped a long time ago, silver was found either on fibrillar component of the connective tissue or in the basal material of sweat glands. The results show that silver is at first phagocytized by macrophages but this cell is unable to perform complete degradation of the silver salt or metal. Then silver is found on connective fibers where it remains on sulfated glycoproteins.

Aged↗
PubMedDate not supplied

[Is the "biopsychosocial model" a helpful construct?].

In 1977, G. L. Engel proposed a biopsychosocial model, applicable to all illness and disease. It was based on systems theory which orders the world into a ladder (of systems) from the most elementary particles to social phenomena and the cosmos. Systems theory was proposed to combat reductionism and to deal with complexity and order. Central to that theory is the concept of emergence that the properties of each "higher" or more complex system are not explainable either by their components nor by those at a lower level. However, no one form of complexity exists. Some forms of complexity arise out of the interactions of the components, especially as the result of feed-back, which in turn allows us to understand order, and sudden change. Living systems are characterized by genetic programs, self-replication, self-organization and adaptability. These properties exist at every "level", and thus make systems theory and its hierarchies no longer necessary, and also eliminate the concept of emergence.

Adaptation, Psychological↗
PubMed1976

[Basic changes in neurons in the peripheral regions of the human nervous system during pathologic processes (electron microscopic study)].

Compensatory-adaptational and reparative reactions were studied in bodies, processes, receptors and synapses of the human peripheral nervous system and in the innervated substrate (myocardium, kidney, liver) by means of electron microscopy. An extreme increase of the electron density of macromolecular protein formations of specific elementary particles was revealed, in particular, in the outer layers of the hypertrophid mitochondria cryst membranes at 50000.000 magnification. These particles are considered as mitochondria precursors.

Cell Nucleus↗
PubMed1982

Physical and biologic aspects on the optimum choice of radiation modality.

The most generally used radiation modalities, low energy photon and electron beams, have been gradually optimized with regard to their physical properties during the last decade. The advantages of increasing the energy range of these beams as high as 50 MeV are discussed based on the assumption that high quality beam flattening systems are used. Possible further developments of the conventional low LET electron and photon beams using grid irradiation and ultra short pulses are also indicated. The dose distributional properties of high quality electron and photon beams are compared with those of heavy particle beams indicating that in several cases only marginal advantages should be expected for the heavy charged particle beams.

Alpha Particles↗