Showing papers by "Boston University published in 1968"
TL;DR: The planum temporale (the area behind Hesch's gyrus) is larger on the left in 65 percent of brains; on the right it is larger in only 11 percent.
Abstract: We have found marked anatomical asymmetries between tile upper surfaces of the human right and left temporal lobes. The planum temporale (the area behind Hesch's gyrus) is larger on the left in 65 percent of brains; on the right it is larger in only 11 percent. The left planum is on the average one-third longer than the planum. This area makes up part of the temporal speech cortex, whose importance is well established on the basis of both anatomical findings in aphasic patients ans cortical stimulation at operation.
2,137 citations
TL;DR: Speculations are presented on the relation between these special structural features and the special function of the initial segment of multipolar neurons.
Abstract: Axon hillocks and initial segments have been recognized and studied in electron micrographs of a wide variety of neurons. In all multipolar neurons the fine structure of the initial segment has the same pattern, whether or not the axon is ensheathed in myelin. The internal structure of the initial segment is characterized by three special features: (a) a dense layer of finely granular material undercoating the plasma membrane, (b) scattered clusters of ribosomes, and (c) fascicles of microtubules. A similar undercoating occurs beneath the plasma membrane of myelinated axons at nodes of Ranvier. The ribosomes are not organized into Nissl bodies and are too sparsely distributed to produce basophilia. They vanish at the end of the initial segment. Fascicles of microtubules occur only in the axon hillock and initial segment and nowhere else in the neuron. Therefore, they are the principal identifying mark. Some speculations are presented on the relation between these special structural features and the special function of the initial segment.
453 citations
TL;DR: Doreen Kimura’s modification of the dichotic listening technique of Broadbent for use as a means of studying the functions of the individual hemispheres represents a major contribution to the study of the human brain.
362 citations
TL;DR: A procedure for photodensitometric quantitation of thin-layer chromatograms is described which can give a complete analysis of a mixture of neutral lipids in a single chromatogram without the necessity for reference mixtures.
270 citations
TL;DR: The axon of the pyramidal neuron in the cerebral cortex arises either directly from the perikaryon or as a branch from a basal dendrite, and an axon hillock is present, a region in which there is a transition between the cytological features of the perIKaryon and those of the initial segment of the axon.
Abstract: The axon of the pyramidal neuron in the cerebral cortex arises either directly from the perikaryon or as a branch from a basal dendrite. When it arises from the perikaryon, an axon hillock is present. The hillock is a region in which there is a transition between the cytological features of the perikaryon and those of the initial segment of the axon. Thus, in the hillock there is a diminution in the number of ribosomes and a beginning of the fasciculation of microtubules that characterize the initial segment. Not all of the microtubules entering the hillock from the perikaryon continue into the initial segment. Distally, the axon hillock ends where the dense undercoating of the plasma membrane of the initial segment commences. Dense material also appears in the extracellular space surrounding the initial segment. The initial segment of the pyramidal cell axon contains a cisternal organelle consisting of stacks of flattened cisternae alternating with plates of dense granular material. These cisternal organelles resemble the spine apparatuses that occur in the dendritic spines of this same neuron. Axo-axonal synapses are formed between the initial segment and surrounding axon terminals. The axon terminals contain clear synaptic vesicles and, at the synaptic junctions, both synaptic complexes and puncta adhaerentia are present.
253 citations
TL;DR: Data from developing nerves indicates that the former are derived from neuroectodermal matrix cells and not from invading mesenchymal elements, which suggests that the third type of neuroglia in adult nerves may represent cells of a similar nature to the multipotential stem cells of other tissues.
Abstract: During a study of developing optic nerves, it was necessary to reevaluate the earlier electron microscopic evidence that only two neuroglial types, oligodendrocytes and fibrous astrocytes, are contained within central white matter. A reexamination of adult optic nerves showed that in addition to these two kinds of cells, a third morphologically distinct cell type exists. Cells of this third neuroglial variety are small and their cytoplasmic density is less than that of all forms of oligodendrocytes but slightly more than that of astrocytes. Neither the filaments and glycogen particles characteristic of astrocytes nor the microtubules typical of oligodendrocytes are observed in the third type of neuroglia. Dense, laminar bodies and fat droplets are frequently present within their cytoplasm, and profiles of the granular endoplasmic reticulum consist of long, stringy cisternae. Fetal and early postnatal optic nerves contain a cell type with the same morphological characteristics. This suggests that the third type of neuroglia in adult nerves may represent cells of a similar nature to the multipotential stem cells of other tissues. Some of the characteristics of the third type of neuroglia are reminiscent of the microglia of classical light microscopy, but data from developing nerves indicates that the former are derived from neuroectodermal matrix cells and not from invading mesenchymal elements.
207 citations
TL;DR: The foundation is a synthesis of psychological, mathematical, and philosophical ideas in a series of papers that appeared between 1967 and 1969.
Abstract: This note is a flashback to the time when the theory’s foundation was being laid. The foundation is a synthesis of psychological, mathematical, and philosophical ideas in a series of papers that appeared between 1967 and 1969 (Papers [1] – [18] in the List of Publications at the end of this book.) The note is the tip of this theoretical iceberg.
191 citations
TL;DR: An alpha globulin fraction prepared from normal human plasma by column chromatography prevents homologous lymphocyte transformation and the stimulation of DNA, and also protein synthesis induced by phytohemagglutinin and specific antigens.
Abstract: An alpha globulin fraction prepared from normal human plasma by column chromatography prevents homologous lymphocyte transformation and the stimulation of DNA, and also protein synthesis induced by phytohemagglutinin and specific antigens. These observations support the concept of a normal circulating immunosuppressant factor which prevents lymphoid cell proliferation.
169 citations
TL;DR: The unprecedented number of young people in the world today can be isolated as one of the crucial reality factors conditioning political and cultural developments as mentioned in this paper, and the role of youth in the light of historical experience.
Abstract: The unprecedented number of young people in the world today can be isolated as one of the crucial reality factors conditioning political and cultural developments. Age distribution is only one demographic variable in the complex of social and political life, but the tremendous growth of world population in the twentieth century has magnified its dynamic potentialities. To gain perspective, it will be useful to briefly consider the role of youth in the light of historical experience.
158 citations
TL;DR: The pharmacokinetics of intravenous infusion is studied for models assuming more than one body compartment, and the rate of which decreases exponentially to the proper steady-state rate is studied.
149 citations
TL;DR: In these studies a constant-infusion technique ordinarily used for the study of intestinal absorption of liquids was modified to obtain quantitative data on human intestinal gas production.
Abstract: For many years it has been known that hydrogen and methane are produced by bacteria and that these gases may be present in high concentration in flatus. Recently, Nielsen has developed methods to measure hydrogen and methane in expired air,l and Calloway has related the breath hydrogen concentration to the ingestion of certain foods.2 There are, however, few data on the site and rate of formation of H2 and CH4 in man. In our studies a constant-infusion technique ordinarily used for the study of intestinal absorption of liquids was modified to obtain quantitative data on human intestinal gas production.
TL;DR: It can be concluded that the Fink-Heimer silver impregnation technique is preferential in its impregnnation of degenerating axons and axon terminals.
TL;DR: The M. irus monkey lends itself well as an experimental model for the study of coronary atherosclerosis and its sequelae, and the consistent predominance of coronary Atherosclerotic lesions over lesions in other arteries are unusual features of this monkey species.
01 Jan 1968
TL;DR: It was concluded that the fibers visualized with the fluorescence histochemical method were adrenergic nerve fibers, and the possible physiologic role of the adrenergic innervation of the canine kidney is discussed.
Abstract: The adrenergic innervation of the canine kidney was studied with the fluorescence histochemical method of Falck and Hillarp in conjunction with chemical assays for catecholamines in specific portions of the kidney. Adrenergic nerve fibers were seen traveling along the interlobar, arcuate, and interlobular arteries and along the afferent arterioles. The vasa recta of the outer medulla also received adrenergic innervation. Adrenergic nerve fibers were never seen in association with the glomerulus, the efferent arteriole, or the tubules. The distribution of the nerve fibers agreed with the distribution of norepinephrine. After administration of reserpine or denervation of the kidney, no adrenergic nerve fibers were seen, and the norepinephrine level in all portions of the kidney fell to negligible levels. Accumulation of norepinephrine in the nerve fibers was observed after kidney slices had been exposed to solutions of norepinephrine. On the basis of these experiments, it was concluded that the fibers visua...
TL;DR: It is shown mathematically on physical grounds that the total-force hypothesis is incapable of accounting even in very simple systems for expansion without increase in pressure or for differential expansion.
TL;DR: An abnormal hemoglobin, termed hemoglobin Kempsey, was found in association with erythrocytosis in ten members of an Australian family and identified a single amino acid substitution, β99Asp→Asn.
TL;DR: It is concluded that a true sphincter exists at the human ileocecal junction and a 4-cm zone of elevated pressure was consistently demonstrated at the junction ofhuman ileum and colon.
TL;DR: Preliminary observations of living randomized patients show that colonic exclusion substantially reduces the need for conventional medical treatment of hepatic encephalopathy, but surgery has provided no advantage in terms of over-all rehabilitation.
TL;DR: The resulting prokaryote phylogeny is presented here; it is claimed to be more consistent with cytological data, measured DNA base ratios, and the fossil record than the several classical partial phylogenies for Thallophytes recently published.
Abstract: The classical assumptions, upon which all previous phylogenies for the lower plants (Thallophytes) have been based, are claimed to be erroneous. An alternative view, that the eukaryotic cell arose in the late Precambrian from prokaryotic ancestors by a specific series of symbioses, is referred to here. Mutually consistent phylogenies, one for the prokaryotes, another for the lower eukaryotes, can be constructed on the basis of the symbiotic theory. The resulting prokaryote phylogeny is presented here; it is claimed to be more consistent with cytological data, measured DNA base ratios, and the fossil record than the several classical partial phylogenies for Thallophytes recently published.
TL;DR: Changes that take place in the skin of the chick embryo from day 6 to day 18 of development have been studied by histochemical techniques and electron microscopy.
TL;DR: The degenerative changes involving the peripheral RPE were postulated to be the result of a disparity between the rate of growth of the RPE and the sclera in this region.
Abstract: A quantitative analysis of the retinal pigment epithelium (RPE) was accomplished by examining ten eyes obtained postmortem from eight individuals between the ages of four months of gestation and 96 years. The RPE was found to consist of a dynamic population of cells which change in number and dimensions as a function of age and location in the eye. The total number of RPE cells per eye was estimated at 4.2 to 6.1 million with greater numbers in older eyes. The degenerative changes involving the peripheral RPE were postulated to be the result of a disparity between the rate of growth of the RPE and the sclera in this region.
TL;DR: The senescent changes in the human retinal pigment epithelium were studied by examining bleached flat mounts prepared from postmortem specimens and found to be a progressive pleomorphism involving the size and shape of the cells, nuclei, and pigment granules.
Abstract: The senescent changes in the human retinal pigment epithelium were studied by examining bleached flat mounts prepared from postmortem specimens. The change most characteristic of senescence of the retinal pigment epithelium in general was found to be a progressive pleomorphism involving the size and shape of the cells, nuclei, and pigment granules. In addition, the retinal pigment epithelial cells of the macular area of the aging eye were found to become progressively narrower, higher, and more densely and irregularly pigmented. The retinal pigment epithelial cells of the periphery of the aging eye were found to become progressively broader, lower, vacuolated, and markedly pleomorphic. Drusen which were felt to be the result of decompensation of the vortex venous system of the choroid were found to be associated with significant degenerative changes involving the retinal pigment epithelium of the macular area of the senile eye.
TL;DR: To measure the morphine effect a foot-shock attenuation procedure that allowed the animal to adjust the shock intensity was used in studying delays of up to 180 days.
Abstract: Rats show a significant degree of tolerance to a second dose of morphine, with the degree of tolerance increasing the longer the delay between the two doses of morphine. To measure the morphine effect a foot-shock attenuation procedure that allowed the animal to adjust the shock intensity was used in studying delays of up to 180 days.
TL;DR: This modification of the von Rudloff procedure allows rapid determination of double-bond positions and analysis of mixtures of positional isomers of monoenoic fatty acids.
Abstract: Tetramethylammonium hydroxide has been used in the extraction and pyrolysis methylation of the carboxylic acids produced by periodate-permanganate oxidation of monounsaturated fatty acid methyl esters. This modification of the von Rudloff procedure allows rapid determination of double-bond positions and analysis of mixtures of positional isomers of monoenoic fatty acids.
TL;DR: The lymphocytes from two patients with primary demyelinating diseases showed significant transformation when stimulated by a pure encephalitogenic myelin basic protein, and lymphoblasts undergoing mitosis were found in their peripheral blood.
TL;DR: The ability of the ova to incorporate exogenous substrates into their endogenous reservers was demonstrated in experiments in which ova were incubated in the presence of C14-labeled acetate or pyruvate for several days; subsequent incubation of the washedp ova and collection of the respiratory CO2 showed that C14O2 was released at linear rates over periods of several hours.