Showing papers by "University of Miami published in 1975"
TL;DR: Monte Carlo simulations of the transfer of radiation in the ocean are used to compute the apparent optical properties of a flat homogeneous ocean as a function of the inherent optical properties and it is shown that these relations can be used with measurements of the upwelling and downwelling irradiance, the beam attenuation coefficient, and the incident radiance distribution.
Abstract: Monte Carlo simulations of the transfer of radiation in the ocean are used to compute the apparent optical properties of a flat homogeneous ocean as a function of the inherent optical properties. The data are used to find general relationships between the inherent and apparent optical properties for optical depths tau
771 citations
TL;DR: The traditional distinction between active and passive euthanasia requires critical analysis and it is suggested that the American Medical Association policy statement that endorses this doctrine is unsound.
Abstract: The distinction between active and passive euthanasia is thought to be crucial for medical ethics. The idea is that it is permissible, at least in some cases, to withhold treatment and allow a patient to die, but it is never permissible to take any direct action designed to kill the patient. This doctrine seems to be accepted by most doctors, and is endorsed in a statement adopted by the House of Delegates of the American Medical Association on December 4, 1973:
The intentional termination of the life of one human being by another—mercy killing—is contrary to that for which the medical profession stands and is contrary to the policy of the American Medical Association.
The cessation of the employment of extraordinary means to prolong the life of the body when there is irrefutable evidence that biological death is imminent is the decision of the patient and/or his immediate family. The advice and judgment of the physician should be freely available to the patient and/or his immediate family.
559 citations
TL;DR: Since cell proliferation was present on all available surfaces, such as the upper and under surface of the retina, and along vitreous surfaces, it is proposed to call this entity "massive periretinal proliferation" (MPP).
522 citations
TL;DR: The penetration depth of light in the sea is defined for remote sensing purposes as the depth above which 90% of the diffusely reflected irradiance originates, and it is demonstrated that for a homogeneous ocean, this is the depth at which the downwelling in-water irradiance falls to 1/e of its value at the surface.
Abstract: The penetration depth of light in the sea is defined for remote sensing purposes as the depth above which 90% of the diffusely reflected irradiance (excluding specular reflectance) originates. It is demonstrated that for a homogeneous ocean, this is the depth at which the downwelling in-water irradiance falls to 1/e of its value at the surface. Penetration depths as a function of wavelength are presented for a variety of water types, and a mean penetration depth z (90) for a broadband sensor is defined and applied to the MSS on ERTS-1. The maximum z (90) expected for ERTS-l is found to be somewhat less than 20 m.
513 citations
TL;DR: It will be shown that uncoupling ensues when the rise in [Ca2+]i occurs at the junction, but not when it occurs at other regions in the cell, as well as when the concentration of free ionised calcium in cytoplasm increases.
Abstract: MANY kinds of cells are coupled by junctions consisting of membrane channels through which molecules of a certain size range can flow freely from one cell interior to another1. It has been proposed that the permeability of the junctional channels depends on the concentration of free ionised calcium in cytoplasm ([Ca2+]i) (ref. 2). This hypothesis is supported by two classes of experiments. In one, the interior of a coupled cell system is allowed ito exchange freely with a known [Ca2+] in the exterior, through a hole in the (non-junctional) membrane; junctional conductance is reduced (uncoupling) when the [Ca2+]i is above 5–8 × 10−5 M (ref. 3). In the other class, uncoupling ensues when the (closed) cell system is treated with inhibitors of energy metabolism or with Ca2+ ionophores5, or on exposure for long periods to Ca,Mg-free medium or to Li medium6; in these conditions a rise in [Ca2+]i, may be expected because of known properties of cellular Ca metabolism7,8. Here, we demonstrate the changes in [Ca2+]i together with those in coupling in three of these conditions, using aequorin to display the distribution of Ca2+ in the cell. It will be shown that the uncoupling is, indeed, in each case associated with a rise in [Ca2+]. Furthermore, by local injection of Ca2+ into the cells, it will be shown that uncoupling ensues when the rise in [Ca2+]i occurs at the junction, but not when it occurs at other regions in the cell.
302 citations
TL;DR: It is concluded that high levels of PEEP can be therapeutic for patients with refractory respiratory failure when combined with intermittent mandatory ventilation and careful cardiovascular monitoring.
293 citations
TL;DR: Goat antibodies to pig lung angiotensin-converting enzyme (kininase II) were conjugated to microperoxidase and reaction product was revealed on the plasma membrane and caveolae of endothelial cells, especially those of capillaries and venules.
Abstract: Goat antibodies to pig lung angiotensin-converting enzyme (kininase II) were conjugated to microperoxidase. Rat lung tissue, previously incubated with non-immune goat serum, was incubated with the antibody-microperoxidase conjugate and then with H2O2 and 3,3-diaminobenzidine. Electron microscopy revealed reaction product on the plasma membrane and caveolae of endothelial cells, especially those of capillaries and venules. These results support the hypothesis that angiotensin I and bradykinin are metabolized by enzymes on the luminal surface of pulmonary endothelial cells.
286 citations
TL;DR: Based on light microscopic findings it is concluded that retinal cells grow out of the retina and build up the preretinal and subretinal tissue.
240 citations
TL;DR: In this paper, the effects of a baroclinic current on inertial internal waves at constant frequency were investigated, primarily through use of the method of characteristics, and the effect of the slope of an isopycnal is of the same order of magnitude as the slopes of the characteristics.
Abstract: Several effects of a baroclinic current on inertial‐internal waves at constant frequency are investigated, primarily through use of the method of characteristics. The special case of waves propagating transverse to a baroclinic current is considered. When the slope of an isopycnal is of the same order of magnitude as the slope of the characteristics, appreciable asymmetries are induced in the characteristics, the phase and group velocities, and the solution itself. These asymmetric effects are especially significant for waves at the low frequency end of the passband for free waves. Also, modifications occur to the passband, resulting in anomalously high and low frequency bands. The effective local inertial frequency, σf = [f(f+vx )]1/2, separates the normal and anomalously low frequency bands. Hence, the low frequency limit of the normal frequency band increases or decreases depending upon whether the horizontal shear in the mean flow is cyclonic or anticyclonic. In the anomalous frequency bands, the slop...
222 citations
TL;DR: In cell regions where the sequestering machinery is sufficiently dense, different Ca2+ message functions inside a cell may be effectively segregated, permitting private-line intracellular communication.
Abstract: The distribution of Ca2+ in the cytoplasm following a local rise in Ca2+ concentration is visualized by means of aequorin luminescence and a television system with an image intensifier. Diffusion of Ca2+ through the cytosol is so constrained that a rise in cytoplasmic Ca2+ concentration produced by local Ca2+ entry through cell membrane or by local Ca2+ injection is confined to the immediate vicinity of these sites. The diffusion constraints are lifted by treatment with cyanide or ruthenium red. Thus, energized calcium sequestering, probably by mitochondria, is the dominant factor in the constraints. In cell regions where the sequestering machinery is sufficiently dense, different Ca2+ message functions inside a cell may be effectively segregated, permitting private-line intracellular communication.
189 citations
TL;DR: Photosynthetically enhanced calcification has been studied in the hermatypic coral, Acropora cervicornis, and dark rates of calcification are unaffected by the addition of these compounds.
Abstract: Photosynthetically enhanced calcification has been studied in the hermatypic coral, Acropora cervicornis. The rate in the light is directly proportional to the intensity of illumination between 0 and 10500 lx. Sodium azide, sodium cyanide, 2,4-dinitrophenol (2,4-DNP), pentachlorophenol and carbonyl cyanide, m-chlorophenyl hydrazone (CCCP) inhibit light (i.e. photosynthetically) dependent rates. With the exception of sodium azide, this may be attributed to an inhibition of oxidative phosphorylation. Dark rates of calcification are unaffected by the addition of these compounds.
TL;DR: It is suggested that the axoplasm is morphologically more organized than is sometimes supposed, and that this should be taken into account in attempts to identify the structural basis of neuronal function and especially of the logistic details of the physiological rapport between the cell body and its extensions.
Abstract: Fine structural studies have shown a uniform pattern of neuronal organization, in that the complex intracellular environment of the perikaryon is separated from morphologically well-characterized and often distant synaptic foci, by a tract of axoplasm that is structurally simple in its variety of components and notably possesses longitudinally oriented neurofilaments and microtubules set in an electron-lucent matrix. Studies on living neurones have indicated that the axoplasm is not only secreted within the cell body and passed slowly outwards, but that it is, in addition, the site of the varied traffic in which structural and molecular components are translocated at a range of speeds in excess of that of bulk centrifugal flow. Intracellular translocation of particulates is a widespread cytoplasmic activity, and the conservatism of evolution and specialization emerging from studies on subcellular structure and function prompts a search for a common mechanism underlying this activity. Experimental evidence from neurones and other cell types suggests that a salient function of cytoplasmic microtubules is the control and/or mediation of intracellular transport. The premise of this account is that functional coupling between translocated particulates and any axoplasmic component responsible for the movement and preserved as an identifiable system by present preparative techniques is likely to involve close physical juxtaposition. Accordingly, the distribution of membrane-limited inclusions with respect to neurofilaments and microtubules has been examined in detail, in thin sections of central axons of ammocoete larvae of the lamprey (Petromyzon marinus), to augment previous studies by a number of investigators on the nervous system of other animals. Subjective examination of electron micrographs may leave open the possibility of apparent association of axoplasmic components by fortuitous pairing in a randomly dispersed system, and the distribution of axoplasmic mitochondria was selected for more quantitative analysis by comparison between data obtained from micrographs and appropriately constructed computed “model axons.” It is suggested that the axoplasm is morphologically more organized than is sometimes supposed, and that this should be taken into account in attempts to identify the structural basis of neuronal function and especially of the logistic details of the physiological rapport between the cell body and its extensions.
TL;DR: This in vivo experiment demonstrated that the vitreous cavity is an adequate culture medium for cells deriving from the pigment epithelium and that pigment epit Helium cells could be the source of intraocular proliferation seen in massive periretinal proliferation.
Journal Article•
TL;DR: Findings indicate that the retinal circulation parallels that of the brain in adjusting to changes in arterial PO2 with compensatory changes in blood flow, which increases considerably in hypoxia and shows a moderate decrease in hyperoxia.
Abstract: The relationship of blood oxygenation to retinal blood flow has been studies in rhesus monkeys Constriction of major retinal arteries and veins during hyperoxia and dilation during hypoxia are demonstrated Together with mean circulation times based on the technique of fluorescein densitometry curves, these data allow an estimation of retinal blood flow, which increases considerably in hypoxia and shows a moderate decrease in hyperoxia These findings indicate that the retinal circulation parallels that of the brain in adjusting to changes in arterial PO2 with compensatory changes in blood flow
TL;DR: In this paper, the GATE Equatorial Oceanographic Experiment (GATE) was used to observe the South Equatorial Current and the Equatorial Undercurrent with time scales of 2-3 weeks.
Abstract: Observations from the GATE Equatorial Oceanographic Experiment are presented. They reveal large scale meandering of the westward flowing South Equatorial Current and of the eastward flowing Equatorial Undercurrent with time scales of 2–3 weeks. Meandering of the flow pattern was found to be related to corresponding displacements of the high salinity core of the undercurrent. The observations tend to support the assumption of a long wave propagating westward with a phase speed of 2.3 m s−1 and a wavelength of 3,200 km. A possible explanation may be given in terms of unstable waves caused by large scale horizontal shear in the Equatorial Current System.
TL;DR: It is suggested on the basis of the observations described in paragraphs 6 to 8 that the time constant of decay of end‐plate currents in the presence of prostigmine increases with increasing concentrations of ACh in the synaptic cleft.
Abstract: 1. End-plate currents have been studied in gylcerol-treated frog sartorius nerve-muscle preparations with the voltage-clamp technique. 2. Adding the anticholinesterase prostigmine (3 muM) to the solution bathing the muscle caused a 2-7 (mean 3-3) times increase in the time constant of decay of end-plate currents. The anticholinesterase edrophonium (15 muM) also prolonged the time course of end-plate currents. 3. Pre-treatment of the preparation with collagenase, which leads to the removal of acetylcholinesterase in the synaptic cleft, prolongs the time course of end-plate currents. 4. Curare (1-2 muM), cobratoxin (0-13 muM), or alpha-bungarotoxin (0-13-0-26 muM) decreased the time constant of decay of end-plate currents in the presence of prostigmine. 5. These observations are consistant with the suggestion that repeated binding of acetylcholine (ACh) molecules to receptors as the ACh escapes from the synaptic cleft can contribute to the prolongation of end-plate currents which occurrs when acetylcholinesterase activity is eliminated. 6. Increasing the amount of transmitter released from the presynaptic nerve terminal leads to a prolongation of end-plate currents in the presence of prostigmine. 7. In the presence of prostigmine, the second of two end-plate currents (interval 2-10 msec) decays more slowly than the first. 8. ACh (1-40 muM) or carbachol (40 muM) applied in the solution bathing the muscle prolongs end-plate currents in the presence of prostigmine. 9. It is suggested on the basis of the observations described in paragraphs 6 to 8 that the time constant of decay of end-plate currents in the presence of prostigmine increases with increasing concentrations of ACh in the synaptic cleft. In the absence of prostigmine, increasing the concentration of ACh in the synaptic cleft did not change the time constant for decay of end-plate currents. 10. We interpret these results to suggest that ACh can have a cooperative action on receptors such that the association of ACh with one receptor (defined as binding a single ACh molecule) favours the binding or retention of ACh at other receptors. This implies that receptors can interact.
TL;DR: It is suggested that metabolism of intact hormone may be required before full biological expression is possible in bovine parathyroid hormone, and three peaks identified in these experiments were analogous in size, biological activity, and immunological characteristics to those described for fractionated human hyperparathyroid serum.
Abstract: The metabolism of bovine parathyroid hormone (PTH) by the perfused rat liver was studied. Labeled hormone, with or without cold hormone, was infused into the circulating perfusion medium containing various calcium concentrations. Pefusate samples at various time periods after the introduction of PTH into the system were chromatographed on Bio-gel P-10; radioactivity and/or immunoreactivity were measured in eluted fractions. Before the perfusion, all immuno- and radioactivity eluted in a single peak, with an apparent mol wt of 9,500 (peak I). After perfusion for 15 min, two other peaks with approximate mol wt of 7,000 (peak II) and 3,500 (peak III) were discernible. Peak I contained both NH2-terminal and COOH-terminal immunoreactivity and was biologically active at all time periods tested. The relative contribution of NH2-terminal and COOH-terminal immunoreactivity to the total immunoreactivity remained constant in this peak throughout the perfusion. In every respect, peak I had the characteristics of intact hormone. At all times, peak II consisted of only COOH-terminal immunoreactivity and was biologically inactive. At early time periods, peak III contained predominantly NH2-terminal immunoreactivity and was biologically active. With time, the relative contribution of NH2-terminal immunoreactivity decreased strikingly while that of COOH-terminal immunoreactivity increased. The three peaks identified in these experiments were analogous in size, biological activity, and immunological characteristics to those we have previously described for fractionated human hyperparathyroid serum. The rate of metabolism of PTH appeared to be regulated by the calcium concentration in the medium. At a high concentration of calcium (greater than 11 mg/100 ml), PTH metabolism was greatly retarded. At a low concentration of calcium (smaller than 5 mg/100 ml), the rate of metabolism was greatly increased. The physiological significance of our observations on the metabolism of PTH by isolated perfused rat liver is not known. However, since such metabolism results in a biologically active fragment, it is suggested that metabolism of intact hormone may be required before full biological expression is possible.
TL;DR: Oxygen isotopic, radiocarbon, and micropaleontological analysis of deep-sea cores from the northeastern Gulf of Mexico identify an episode of rapid ice melting and sea-level rise at about 9600 years B.C, which coincides with the age of the Valders ice readvance and with the Age of Plato to the flood he describes.
Abstract: Oxygen isotopic, radiocarbon, and micropaleontological analysis of deep-sea cores from the northeastern Gulf of Mexico identify an episode of rapid ice melting and sea-level rise at about 9600 years B.C. This age coincides, within the limits of all errors, with the age of the Valders ice readvance and with the age assigned by Plato to the flood he describes.
TL;DR: In this article, a heat-stable, non-dialysable inhibitor of PHYLase phosphatase was found in rabbit liver extracts, which is polydisperse on gel permeation chromatography and the mechanism of the inhibition is due to a direct interaction of the protein inhibitor with the enzyme.
TL;DR: Rodingites were dredged from fracture zones of the equatorial Mid-Atlantic Ridge along with serpentinized ultramafics, and fresh and metamorphosed basalts and gabbroids as mentioned in this paper.
Abstract: Rodingites were dredged from fracture zones of the equatorial Mid-Atlantic Ridge along with serpentinized ultramafics, and fresh and metamorphosed basalts and gabbroids. These rodingites were generated by a metasomatic process at low temperature involving an enrichment in lime and water, and a loss of silica and alkalis. The parent rocks were gabbronorites which intruded ultramafic material as it ascended from the upper mantle to its present location in the upper oceanic crust. The gabbronorites were probably altered to rodingites while they were still in the lower oceanic crust. Since the rodingitization process appears to be concomitant, complementary and simultaneous with the serpentinization of the host ultramafic rocks, we infer that the serpentinization process also took place in the deeper part of the oceanic crust. These two simultaneous metasomatic processes thus predate the major phase of tectonic events which uplifted these blocks as cold, solid diapiric emplacements of ultramafic material and accompanying rodingites to their present positions along lines of weakness expressed as fracture zones.
TL;DR: The clinical as well as the histologic findings suggested that the retinal abnormality overlying the hypertrophied RPE was due to secondary degeneration rather than primary maldevelopment of photoreceptor cells.
TL;DR: Szadeczky-Kardoss et al. as discussed by the authors proposed using two sets of morphometric parameters to discriminate the hyaloclastites from hyalotuffs.
Abstract: Hyaloclastites are volcaniclastic rocks generated by non-explosive granulation of volcanic glass which takes place when basaltic magmas are quenched by contact with water; hyaloclastites are common products of deep submarine basaltic central volcanoes (seamounts and guyots). We suggested (Honnorlz, 1966) calling hyalotuffs the actual pyroclastic rocks which are generated by phreatomagmatic and phreatic explosions taking place when basaltic volcanoes crupt in shallow waters; hyalotuffs are restricted to shallow subaqueous conditions since no volcanic explosion can occur in deep seas. The distinction between hyaloclastites and hyalotuffs is therefore a useful tool when reconstructing the paleogeography of ancient submarine volcanic edifices and the mechanism by which their lavas were emplaced. We propose using two sets of morphometric parameters to discriminate the hyaloclastites from the hyalotuffs. The granules making up these two volcaniclastic rock types plot in different areas of either 1) a ternary diagram the apexes of which represent the grain planarity (P), convexity (V) and concavity (C) % («roundness» according to Szadeczky-Kardoss); or 2) a binary diagram relating the number of grain corners (N) to their planarity (P) %.
TL;DR: It is suggested that recent evidence indicates that the uptake of NaCl of ionic regulation is secondary to the extrusion of HCO−3, H+ and NH+4 and that the exchange systems may be functioning in sea water acclimated fish that already face a NaCl load.
TL;DR: Growth and survival of sea bream, Archosargus rhomboidalis (L.) larvae were affected by both abundance of eggs that were initially stocked in 75 1 rearing systems and by the concentration of copepod nauplii andCopepodites that were fed to larvae.
Abstract: Growth and survival of sea bream, Archosargus rhomboidalis (L.) larvae were affected by both abundance of eggs that were initially stocked in 75 1 rearing systems and by the concentration of copepod nauplii and copepodites that were fed to larvae. Stocking levels were 2, 4, 8,16 or 32 per litre while food abundance was maintained at approximately 100, 500, 1500 or 3000 per litre. Experiments were of 16 days duration at 26° C. Survival was best, often exceeding 60%, when food levels were 1500 or 3000 per litre and when stocking density did not exceed 8 eggs per litre. Growth was best at the lowest stocking densities and highest food levels. The highest total yields in wet weight occurred at 8 per litre stock density and 3000 per litre food level. Mean wet weight per survivor and yield per stocked egg were greatest at the lowest stocking densities and highest food levels. A 500 per litre food level was marginal for growth and survival, and 100 per litre produced significant survival only at the 2 per litre stocking density. Two experiments at 6000 and 10 000 per litre food levels at 4 per litre stock density gave the best observed growth, and survival as good as in any other experiments. Possible relations between sea bream larvae and their food supply in the natural environment are discussed. Results also are discussed in terms of their possible contribution to aquaculture efforts.
TL;DR: In this article, a kinematic model, combining a moving vortex pair with a uniform background current, is used to determine the spatial dimensions, phase speed, and circulation of spin-off eddies.
TL;DR: The hypothesis that RPE proliferation and transformation play a major role in the formation of collagen containing membranes, such as are found in massive periretinal proliferation, is supported.
TL;DR: In the owl monkey, proliferation of pigment epithelial and glial cells occurred in varying degrees in nearly all eyes with retinal detachments, and was called massive periretinal proliferation to emphasize the importance and ubiquity of cellular proliferations.
TL;DR: Methanogenesis was irreversibly inhibited in sediments by concentrations of acetylene employed in nitrogen fixation assays (1 to 20%, vol/vol), and the inhibition was reversed by gassing with hydrogen.
Abstract: Methanogenesis was irreversibly inhibited in sediments by concentrations of acetylene employed in nitrogen fixation assays (1 to 20%, vol/vol). Ethylene, but not ethane, also stopped methane production, and the inhibition was reversed by gassing with hydrogen.
TL;DR: Preliminary observations of populations of Ithomiinae and Danaus reveal that the presence of naturally occurring PA-sources are a major factor in determining population distribution, abundance, and reproductive behavior.
Abstract: Various plants containing pyrrolizidine alkaloids (PA) are visited by Lepidoptera, which congregate on dead stems, seeds, and foliage to feed. Most visitors to PA-plants belong to the nymphalid subfamilies Ithomiinae and Danainae and the moth families Ctenuchidae and Arctiidae. Ninety-six percent of ithomiines and danaines caught feeding at PA-plants are males which ingest alkaloids necessary for the production of PA-derived sex pheromones. Among Arctiidae and Ctenuchidae, however, many species show either unbiased or female-biased attraction patterns. Their visits may be linked to acquisition of PA's used for chemical defense or as yet unidentified nutritive substances. Extensive baiting with a variety of PA-plants as well as samples of etude alkaloids indicate that attraction is primarily the result of olfactory cues. Once a visitor lands on a PA-source, substances on the plant surface act as phagostimulants. Judging from attraction spectra of different PA-plant and chemical baits, at least 2 types of volatile attractants are involved: dissociated “esterifying acids” from the fused ring nucleus of the alkaloids, and substances derived from the nucleus itself. Preliminary observations of populations of Ithomiinae and Danaus reveal that the presence of naturally occurring PA-sources are a major factor in determining population distribution, abundance, and reproductive behavior. The evolution of PA-attraction is discussed with respect to the various roles PA's may play in the Lepidoptera ingesting them.
TL;DR: Evidence is given that the stable complex is effected by Ca-2+-mediated salt bridges between the two membranes and that the rate constant of the transformation step derives from the statistics of the distribution and the rate of redistribution of Ca- 2+-occupied polar head groups on the membrane surfaces.