Showing papers by "Louisiana State University published in 1976"

Autoxidation of polyunsaturated fatty acids: II. A suggested mechanism for the formation of TBA-reactive materials from prostaglandin-like endoperoxides.

Abstract: The nature and mechanism of formation of the thiobarbituric acid (TBA)-reactive material produced in the autoxidation of polyunsaturated fatty acids (PUFA) or their esters has been studied. On the basis of chemical studies and

Subaqueous liquefied and fluidized sediment flows and their deposits

Abstract: A clear distinction must be made between liquefied and fluidized systems. In liquefied beds and flows, the solids settle downward through the fluid, displacing it upward, whereas, in fluidized beds, the fluid moves upward through the solids, which are temporarily suspended without net downward movement. Many recent references to fluidized sediment gravity flows refer, in fact, to flows of liquefied debris. Most uniformly liquefied beds of well-sorted sand- or gravel-sized sediment will resediment as simple two-layer systems. Liquefied flows can originate either by liquefaction followed by failure, as in many retrogressive flow slides, or by failure followed by liquefaction, as in the case of some slumps. Empirical and theoretical estimates of flow velocity, thickness, and travel distance suggest that natural laminar liquefied flows of fine-grained sand will generally resediment after moving a kilometre or less. Laminar flows of coarse-grained sand will resediment after moving only a few metres. Grain dispersive pressure is thought to be of little significance in the development or maintenance of liquefied flows. Many surficial submarine sand beds are apparently susceptible to liquefaction, including submarine canyon and continental rise deposits. Within submarine canyons and narrow fjords, steep slopes and channels promote the evolution of liquefied flows from slumps by liquefaction after failure and of high density turbidity currents from liquefied flows by the development of turbulence. Upon moving into the lower parts of submarine canyons or into proximal fan channels, liquefied flows will resediment and high density turbidity currents will tend to decline to flows transitional between liquefied flows and turbidity currents. The liquefied, coarser detritus within such transitional flows will be deposited while finer-grained debris will remain in suspension and continue downslope as dilute turbidity currents. Resedimentation of the liquefied portions of such flows may be responsible for the deposition of the A-subdivision of many turbidites and many thick, structureless ‘proximal turbidites’ or ‘fluxoturbidites’. Similar units can originate by liquefaction of the traction deposits of normal turbidity currents. Fluidized flows are probably uncommon, thin, and, where formed, originate through fluidization of the fine-grained tops of liquefied graded beds.

Grain Flow and Grain Flow Deposits

Abstract: The term grain flow is restricted to sediment gravity flows in which a dispersion of cohesionless grains is maintained against gravity by grain dispersive pressure and in which the fluid interstitial to the grains is the same as the ambient fluid above the flow. Modified flows include those in which a dense interstitial fluid, current, or escaping pure fluid aids in maintaining the dispersion. Conclusions regarding the dynamics of grain flows have been based largely on the analysis of Bagnold (1954) of fully confined, gravity-free dispersions. Natural flows are neither fully confined nor gravity-free, and their characteristics and dynamics differ significantly from his experimental systems. Velocity equations are developed and used to analyze natural grain flows. Unmodified subaerial and subaqueous, steady and uniform flows of sand occur only on slopes at or near the angle of repose, are generally less than 5 cm thick, and cannot individually account for the formation of thick sedimentation units. On slopes inclined at less than the angle of repose, grain flows collapse and freeze; on higher slopes, they accelerate, dilate, and become increasingly influenced by fluid forces. Thick grain flows of gravel-sized debris and thick flows modified by the presence of dense, plastic mud interstitial to the clasts (debris flows), polymodal coarse-sediment size distribution (density-modified grain flows), or concurrent sediment liquefaction or fluidization (liquefied or fluidized sediment flows) can move over relatively low slopes and accumulate as thick sedimentation units.

High sodium-low potassium environment and hypertension.

Abstract: The high sodium-low potassium environment of civilized people, operating on a genetic substrate of susceptibility, is the cardinal factor in the genesis and perpetuation of "essential" hypertension. The noxious effects begin in childhood, when habits of excess salt consumption are acquired at the family table, and are perpetuated by continuing habit and by increasing use of convenience and snack foods with artificially high concentrations of sodium and low levels of potassium. Present methods of food preparation leach out the protective potassium. Extradietary sodium chloride is a condiment not a requirement. Some primitive populations clearly preferred potassium chloride to sodium chloride. Chronic expansion of extracellular fluid volume induced by excess salt consumption causes the central and peripheral circulatory regulatory mechanisms to work at cross purposes, resulting in increased arterial pressure. The protective effect of potassium is dramatic and easily demonstrable in animals and man but its mechanism is not known. It cannot be entirely a direct effect on blood pressure because rats protected with extra potassium against a moderately high salt intake live much longer than control rats but have the same elevated blood pressures. In hypertension with a demonstrable "cause," the high sodium-low potassium environment makes a bad matter worse. In nature, feral man and his forebears were not confronted with excessive sodium and deficient potassium; indeed, the reverse was the case. Evolution has provided powerful mechanisms for conserving sodium and eliminating potassium, but no efficient physiologic mechanisms for conserving potassium and eliminating excess sodium. Most laboratory animal "control" diets contain an amount of sodium that fully suppresses aldosterone secretion, and the same is true of the "average" diet of the American people. Inadequate attention to dietary sodium and potassium makes many studies in both animals and man of uncertain validity. Internally, essential hypertension is an exceedingly complex mosaic of physiologic interactions. Viewed from outside, it is a disorder for which genetic material sets the stage; excessive sodium precipitates it and perpetuates it. Extra salt makes all forms more rapidly progressive and accelerates the onset of terminal events; extra potassium is everywhere protective. When an entire population eats excessively of salt, hypertension will develop among those genetically susceptible, but epidemiologic studies of salt versus blood pressure will not show a relation of salt to hypertension. This is the saturation effect. Low sodium diets are therapeutically effective but generally regarded as an impossible or an unnecessary nuisance. Effective prevention programs must be instituted at as early an age as possible. The efficacy of a prophylactic/therapeutic low sodium-high potassium diet should be weighed against the uncertain hazards of a lifetime of pill taking.

Productivity and composition of a baldcypress-water tupelo site and a bottomland hardwood site in a louisiana swamp'

Abstract: hardwood site (BLH) and 500 g dry wt/m2 for a baldcypress-water tupelo site (CT). Litter-fall was 574 g dry wt/m2/yr for BLH and 620 g dry wt/m2/yr for CT. Harvest samples within the two plots yielded 200 g dry wt/m2 and 20 g dry wt/m2 for BLH and CT, respectively. Minimum net primary production was calculated as the sum of the three: 1574 g dry wt/m2/ yr for BLH and 1140 g dry wt/m2/yr for CT. Maximum estimates of herbaceous production and insect consumption were made by using values from the literature. Estimated total net primary productivity was 1733 g dry wt/m2/yr for BLH and 1516 g dry wt/m2/yr for CT. Tree composition was determined by the point-centered quarter method. Relative frequency, relative density, absolute density, relative dominance, and importance value (IV) were calculated for the tree species along each transect. In the bottomland hardwood area many woody species exist with Acer rubrum var. drummondii (IV = 23.9) and Nyssa aquatica (IV = 18.4) the most dominant. In the baldcypress-water tupelo area, fewer woody species exist and Taxodium distichum (IV - 39.2) and N. aquatica (IV = 37.6) dominated. Comparison of productivity data from several southeastern swamps indicate that flowing water regimes tend to result in the highest swamp forest productivity.

Serum cholesterol and triglyceride levels in 3,446 children from a biracial community: the Bogalusa Heart Study.

Abstract: The need to recognize Coronary Artery Disease (CAD) risk factors at an early age is becoming increasingly important. Serum cholesterol has long been known to be a major independent risk factor for CAD in adults (1). More recently, the level of serum triglycerides has been incriminated as a CAD risk factor independent of cholesterol (2) although the evidence for independence is not conclusive (3).

Daily Variation in Concentration of Plasma Corticosteroid in Hypophysectomized Rats

Abstract: A daily variation in the concentration of plasma corticosteroid hormone is present in hypophysectomized rats implanted with pellets of adrenocorticotropic hormone (ACTH) and thyroxine. Although ACTH is necessary to maintain a functional adrenal, and thyroxine is required to permit the expression of the plasma corticosteroid rhythm, a normal daily variation in plasma corticosteroid concentration does not appear to depend on the periodic release of pituitary hormones. (Endocrinology 98: 1475, 1976)

Fetal and Neonatal Development of the Microsomal Monooxygenase System

Abstract: (1976). Fetal and Neonatal Development of the Microsomal Monooxygenase System. Drug Metabolism Reviews: Vol. 5, No. 1, pp. 1-42.

Proline metabolism in Trypanosoma cruzi epimastigotes.

Abstract: 1. 1. Oxygen uptake by epimastigotes of Trypanosoma cruzi , Costa Rica strain, was stimulated by l -proline, l -glutamate and to a lesser degree by l -aspartate. 2. 2. l -proline reversed partially malonate-induced inhibition of respiration but did not reverse KCN-induced inhibition. 3. 3. Labeled proline, glutamate, aspartate, cystine and lysine were detected by thin-layer chromatography in the free amino acid pool from cells incubated with l -proline- 14 C. 4. 4. Labeled tricarboxylic acid intermediates were also found by this method in extracts from organisms incubated with l -proline- 14 C which contained also pyruvate. 5. 5. Labeled alanine was not found in epimastigotes incubated with l -proline- 14 C, l -glutamate- 14 C or aspartate- 14 C indicating a difference between T. cruzi amino acid metabolism and that found in other hemoflagellates. 6. 6. Labeled l -proline was not found in epimastigotes incubated with d -glucose- 14 C, glutamate- 14 C or aspartate- 14 C indicating that the flow of carbon from proline to glutamate and aspartate may not be reversible. 7. 7. All results suggest the presence of a proline-glutamate inter-conversion pathway in T. cruzi epimastigotes.

Effects of in situ tidal salinity fluctuations on osmotic and lonic composition of body fluid in Southeastern Alaska Rocky intertidal fauna

Abstract: Tidal fluctuations in salinity and temperature were monitored at a location on Lynn Canal, north of Juneau, Alaska. Organisms were collected from 4 tidal levels during each slack water over a period of 24 h. Body-fluid milliosmolality as well as sodium, potassium, calcium, magnesium and chloride levels were determined. Mytilus edulis were collected at the +1.0 m tidal level, where ambient salinity ranged from 7.9 to 25.1% and body fluids from 356±62 to 730±17 mOsm/kg water. Cucumaria vegea and Katherina tunicata were collected at the +0.6 m level, where ambient salinity ranged from 13.5 to 24.9‰ and body fluids from 461±27 to 662±50 and 443±31 to 616±38 mOsm/kg water, respectively. Eupentacta quinquesemita and Evasterias troschelii were collected at the -0.9 m level, where ambient salinity ranged from 11.0 to 28.2‰ and body fluids from 504±32 to 632±51 and 316±31 to 664±37 mOsm/kg water, respectively. Strongylocentrotus droebachiensis were collected subtidally at the -3.7 m level, where ambient salinity ranged from 14.1 to 28.0‰ and perivisceral fluids from 448±35 to 661±51 mOsm/kg water. Ion levels of the perivisceral fluid of c. vegae were not determined. Potassium appeared to be regulated by all animals except Evasterias troschelii. Little regulation occurred for calcium, magnesium, sodium and chloride by the organisms. Eupentacta quinquesemita appeared to be regulating all ions determined, but this may have been due to its microhabitat. Water temperature cycled inversely to salinity at all tidal levels. Ambient-water sodium, chloride and calcium levels deviated from levels that would be expected upon dilution of seawater with deionized water. There was not indication that body-fluid osmoconcentration of the species collected intertidally increased on exposure to air.

A Clinical and Histologic Study of Healing following the Excisional New Attachment Procedure in Rhesus Monkeys

Abstract: Experimental suprabony periodontal pockets were established around the incisors of Rhesus monkeys and subsequently were treated by the Excisional New Attachment Procedure. Healing was evaluated clinically and histologically for up to 6 months. Clinical examinations demonstrated an overall mean pocket depth reduction from 5.02 mm to 2.82 mm, of which 0.57 mm was recession and 1.59 mm (73.6%) was clinical new attachment. Histologic evaluation of experimental sites consistently revealed a long, thin junctional epithelium with a minimal amount of inflammatory infiltrate in the subjacent, densely fibered, lamina propria. Control areas demonstrated the classic histologic picture of periodontal disease and tended to be progressive in nature clinically.

Wave Action and Bottom Movements in Fine Sediments

Abstract: Mudbanks have been observed to have an extraordinary calming effect on the sea surface. In certain cases this effect is due primarily to the transfer of energy through the sea/mud interface and its frictional dissipation within the bottom sediments. This paper describes an experiment that measured wave characteristics and the resulting sea floor oscillations in an area where the bottom is composed of fine-grained sediments. The energy lost by the waves at the position of the experimental setup is calculated and compared with a direct measurement of the net energy lost by the waves in going from the point of the experiment to a station 3.35 km inshore. Results show that bottom motions in the range of wave-induced bottom pressures from near zero to 2.39 x 10-3 Pascal have the appearance of forced waves on an elastic half space. The apparent effect of internal viscosity is seen in a phase shift between the crest of the pressure wave and the trough of the mud wave. Measurements show this angle to be 22° (ill") for the peak spectral component (T = 7.75 seconds). The energy lost to the bottom by the waves at the field site was found to be at least an order of magnitude greater than that resulting from the processes of percolation or that caused by normal frictional effects. This newly observed mechanism for the dissipation of wave energy is particularly important for waves in intermediate-depth water and could be a prime factor in determining design wave heights in muddy coastal areas.

Preservation of Channel Catfish Sperm

Abstract: Three activators, eight extenders, and three protective agents at two concentration levels each were used to determine the best combination that will maintain in storage the viability of channel catfish (Ictalurus punctatus) sperm cells. There was a highly significant (P < 0.01) difference in motility score among activators. Saline (0.65%) gave the highest motility score. Extended sperm cells became motile when activated after 2 months of storage at 4 C. Extender I (Truscott and Idlers Hfx #1) with 10% dimethyl sulfoxide (DMSO) and 2 hours equilibration produced the highest motility scores after freezing of 24 hours or 1 week. Freezing rate was controlled by placing vials of sperm in a double-layered, kapok-lined paper bag and freezing at the height of 127 mm above the liquid nitrogen level.

High-density expansion of the electron-gas correlation function

Abstract: A high-density expansion of the electron-gas correlation function $g(r)$ is carried out in powers of the coupling constant $\ensuremath{\alpha}{r}_{s}$. It is found that at zero interparticle separation, $g(0)=\frac{1}{2}\ensuremath{-}\ensuremath{\alpha}{r}_{s}\frac{({\ensuremath{\pi}}^{2}+6\mathrm{ln}2\ensuremath{-}3)}{5\ensuremath{\pi}}\ensuremath{-}{(\frac{3\ensuremath{\alpha}{r}_{s}}{2\ensuremath{\pi}})}^{2}\mathrm{ln}({r}_{s})(3\ensuremath{-}\frac{{\ensuremath{\pi}}^{2}}{4})+O({r}_{s}^{2})$. For large interelectronic separation, the zero-order correction to $g(r)$ is obtained and the correction linear in ${r}_{s}$ is estimated.

Sediment Transport and Dispersal Across the Deep Fore-Reef and Island Slope (-55 m to -305 m), Discovery Bay, Jamaica

Abstract: Observations and samples taken during submersible operations on the deep fore-reef and island slope (-55 m to -305 m) off Discovery Bay, north Jamaica, revealed a surprising lack of reef-derived sediments on the deeper parts of the island slope as a result of the barrier effect of sill reefs at the top of the deep fore-reef. In those areas where sill reefs are absent such as the area immediately above the Discovery Bay submarine canyon, compositional and textural data, together with bulk carbon-14 age dates that range from 900 to 3,530 years BP, indicate occasional catastrophic movement of discrete sediment masses down the axis of the canyon, separated by long periods of suspended sediment addition and biologic mixing. During the present sedimentologic regimen, the coarse reef-derived debris found in the canyon does not continue down-slope into the adjacent deep basin (Cayman-Bartlett trench), but seems to be restricted to the island slope above 800 m. The green alga, Halimeda, is a major reef-sediment source, particularly in the deep fore-reef where it was found alive and growing in significant quantities to depths as great as 100 m. The various species of Halimeda can be useful sediment tracers, with H. goreauii and H. opuntia being characteristic of fore-reef slope environments and H. cryptica essentially restricted to the deep fore-reef. The present study confirms that boring sponges particularly Cliona sp. generate significant quantities of easily recognizable silt-sized detritus as a result of their boring activity. More than 5% of the total volume of the island slope sediment samples can be attributed to the boring activity of the clionid sponges with a mean of 24% of the silt fraction being composed of clionid debris. Where sponge chips contain microscopic algal borings from the original substrate, clionid debris may serve as a powerful sediment tracer from shallow to deep water. The submersible NEKTON Gamma made possible direct observation and sampling of a hitherto unknown, highly complex environment. These observations, and the data generated from these samples, have significantly reshaped our understanding of fore-reef sediment transport and deposition.

Seroepidemiologic Investigations of Human Hepatitis Caused by A, B, and a Possible Third Virus

Abstract: SummarySeroepidemiologic studies were made of normal subjects in populations in the United States and Costa Rica and in family outbreaks of hepatitis in Costa Rica. Hepatitis A affected a majority of children of very young age in Costa Rica, while such experience in persons of high socioeconomic status in the United States did not occur before middle life. Persons of low socioeconomic status (paid plasma donors) and residents and attendants of institutions for the mentally retarded showed a far greater incidence of hepatitis A antibody than did their counterparts in the open community. Hepatitis A and B epidemics occurred in families in Costa Rica with rapid spread to other susceptible members of the group. The disease was clinically apparent in roughly half the cases, whether the responsible agent be hepatitis A or B. Five cases of nonhepatitis A or B (hypothetical hepatitis C) were found and all but one of them were subclinical.The authors are indebted to M. A. Chacon, D. Jimenez E., and A. Rivas E. and...

A Clinical Study of Healing in Humans following the Excisional New Attachment Procedure

Abstract: The excisional new attachment procedure was used to treat 75 suprabony pockets on 32 teeth in 9 patients. One-year postoperative measurements demonstrated an overall mean pocket reduction from 4.7 mm to 2.0 mm, of which 2.1 mm (77%) was new attachment and 0.6 mm was recession. Average amount of new attachment and percentage of new attachment were greatest on the midlingual surfaces of the teeth treated in this study. The results of this study showed the excisional new attachment procedure to be a simple, effective, and predictable procedure for achieving pocket elimination by means of a clinical new attachment of the gingival tissues in suprabony pockets.

Effect of frequent changes in aerobic and anaerobic conditions on redox potential and nitrogen loss in a flooded soil

Abstract: The effect of frequent changes in aerobic and anaerobic conditions on redox potential and N loss in a flooded soil was investigated under laboratory conditions. Increasing the frequency of changing from aerobic to anaerobic conditions from 48 h aerobic-48 h anaerobic to 6 h aerobic-6 h anaerobic increased N loss. A separate experiment showed that losses were somewhat less when the frequency was increased from 6 h aerobic-6 h anaerobic to 3 h aerobic-3 h anaerobic, but the loss of N again increased when the frequency was further increased to 1.5 h aerobic-1.5 h anaerobic. N losses were due to alternate nitrification (aerobic period) and denitrification (anaerobic period), possibly coupled with chemical decomposition of nitrite at the greater aerobic-anaerobic frequencies.