Comparison of techniques for measuring pulse-wave velocity in the rat

Mitchell, Gary F., Marc A. Pfeffer, Peter V. Finn, andJanice M. Pfeffer. Comparison of techniques for measuringpulse-wave velocity in the rat. J. Appl.Physiol. 82(1): 203-210, 1997.We evaluatedmethods for measuring average and regional pulse-wave velocity alongthe full length of the aorta in 18-mo-old ether-anesthetized malespontaneously hypertensive rats. Catheter-tip manometers were placed inthe ascending and descending thoracic aorta via the right carotid andleft femoral arteries, respectively. As the distal catheter waswithdrawn at 1-cm intervals, the relationship between distal catheterinsertion distance and distance between transducers was determined fromthe intercept of the insertion distance vs. transmission delayregression line. Methods that assessed the foot-to-foot time delaybetween pressures accurately predicted the separation between catheters(measured distance of 14.3 cm; intercept of 14.0 ± 0.5 cm;P = not significant) were highlyreproducible (coefficient of variation of 2.3% for repeated measurements) and showed minimal variability (range 509 ± 30 to 600 ± 29 cm/s) along the full length of the aorta. Methods that madeuse of the pressure-pressure transfer function were spatially (range ofvalues along the aorta 367 ± 17 to 722 ± 39 cm/s) and temporally more variable, especially during vasoconstriction with methoxamine, due to the effects of reflected waves.

     

Effect of heat treatment on survival of, and growth from, spores of nonproteolytic Clostridium botulinum at refrigeration temperatures.

Spores of five type B, five type E, and two type F strains of nonproteolytic Clostridium botulinum were inoculated into tubes of an anaerobic meat medium plus lysozyme to give approximately 10(6) spores per tube. Sets of tubes were then subjected to a heat treatment, cooled, and incubated at 6, 8, 10, 12, and 25 degrees C for up to 60 days. Treatments equivalent to heating at 65 degrees C for 364 min, 70 degrees C for 8 min, and 75 degrees C for 27 min had little effect on growth and toxin formation. After a treatment equivalent to heating at 85 degrees C for 23 min, growth occurred at 6 and 8 degrees C within 28 to 40 days. After a treatment equivalent to heating at 80 degrees C for 19 min, growth occurred in some tubes at 6, 8, 10, or 12 degrees C within 28 to 53 days and at 25 degrees C in all tubes within 15 days. Following a treatment equivalent to heating at 95 degrees C for 15 mine, growth was detected in some tubes incubated at 25 degrees C for fewer than 60 days but not in tubes incubated at 6 to 12 degrees C. The results indicate that heat treatment of processed foods equivalent to maintenance at 85 degrees C for 19 min combined with storage below 12 degrees C and a shelf life of not more than 28 days would reduce the risk of growth from spores of nonproteolytic C. botulinum by a factor of 10(6).(ABSTRACT TRUNCATED AT 250 WORDS)     

Location of the active site of the bean {alpha}-amylase inhibitor and involvement of a Trp, Arg, Tyr triad

Seeds of the common bean contain three homologous proteins:phytohaemagglutinin E, phytohaemagglutinin L and the lectin-likeprotein     

A genetic component in human lysosomal enzyme excretion

Acid hydrolases are present in normal human urine in appreciable amounts. Their source appears to be lysosomes released by kidney proximal tubule epithelial cells. For a given lysosomal enzyme the total amount excreted is the product of two parameters, a general one describing the rate of lysosome secretion and a specific one describing the relative concentration of that enzyme in lysosomes. There is considerable population variation in both parameters. Studies of -glucuronidase, -galactosidase, -hexosaminidase, and -galactosidase in monozygotic and dizygotic twins show that an appreciable part of this variation is genetic in origin. This appears to be true for both total enzyme excretion and lysosome composition. Although it was not possible to test directly whether this is also true for the rate of lysosome secretion, the fact that the two former parameters are both heritable strongly suggests that the rate of lysosome excretion is also a heritable trait. Taken together with previous data, the results suggest polygenic control of these biochemical traits. It is particularly significant that -glucuronidase excretion in normal individuals is a heritable trait since the excretion of this enzyme has frequently been used as a measure of normal and pathological physiological changes.This study was supported by grants from the National Institutes of Health (GM-19521) and the Council for Tobacco Research—U.S.A., Inc. (1080). The work was done while the authors were in the Department of Molecular Biology, Roswell Park Memorial Institute, Buffalo, New York 14263.     

Nile water as a cause of Eastern Mediterranean sapropel formation: Evidence for and against

During the late Pleistocene, sapropels (layers of organic-carbon rich sediment) formed throughout the entire Eastern Mediterranean Basin in close association with glacial/interglacial transitions. The current theory for the mechanism of sapropel formation involves a density stratification of the water column, due to the invasion of a large quantity of low-saline water, which resulted in oxygen depletion of the bottom waters. Most workers believe that this low-salinity water was glacial meltwater that entered the Mediterranean via the Black Sea and a series of interconnected glacial lakes, but the suggestion also has been made that the freshwater originated from the Nile River. In this study the oxygen isotope values of planktonic foraminifera,Globigerinoides ruber, have been examined in six gravity cores and one piston core from the southern Levantine Basin, and compared with the oxygen isotope records ofG. ruber from other areas of the Eastern Mediterranean. This study deals mainly with the latest sapropel which was deposited approximately 7000 to 9000 years ago. Results indicate that Nile discharge probably does reduce salinities somewhat in the immediate area surrounding the mouth of the Nile, but this water is rapidly mixed with the highly saline waters of the easternmost Mediterranean.Using a mixing equation and surface water salinity limitations, an approximate oxygen isotope balance of surface waters was calculated for the time of latest sapropel deposition. This calculation shows that neither Nile River discharge nor Black Sea input (nor both together) are large enough to account for the large-scale oxygen isotope depletion associated with latest sapropel deposition in the Eastern Mediterranean. This suggests that part of the isotopic change at Termination I is probably due to increased surface water salinities during the last glacial maximum. In addition, evidence from the timing of sapropel 1 deposition and the dissolved oxygen balance indicates that deposition of the latest sapropel is associated with increased surface water production of biogenic material, as much as three times higher than that of present day.     

Inversions and other unusual heteromorphisms detected by C-banding

Summary Sixteen patients with unusual heteromorphisms involving alterations of the length and/or position of centromeric heterochromatin are described. Family studies showed that the heteromorphisms were present in other relatives and segregated in the expected 1:1 ratio. There was a significantly greater frequency of unusual heteromorphisms among Orientals than in other races studied.     

Regulation of the synthesis of human chorionic gonadotropin by strains of HeLa cells in culture

Summary Thirty-seven strains of HeLa cells were examined for their ability to synthesize human chorionic gonadotropin (hCG) and its alpha subunit (hCG-α) in culture. Synthesis of hCG-α and hCG also was investigated in the presence of sodium butyrate and 5-bromo-2′-deoxyuridine (BrdUrd). All HeLa strains synthesized hCG-α in culture. Sodium butyrate increased the synthesis of hCG-α in all HeLa cells; BrdUrd increased synthesis in 32 of the 37 strains examined. Although few HeLa strains synthesized hCG in the absence of inducers, hCG was detected in most strains in the presence of sodium butyrate. The synthesis of hCG and its alpha subunit is, therefore, a stable genetic characteristics of HeLa cells. Certain preparations of hCG and its subunits were generously provided through the Center for Population Research of the National Institute of Child Health and Human Development, NIH.     

Lateral mobility of β-receptors involved in adenylate cyclase activation

Cationized ferritin was found to inhibit the lateral mobility of intramembrane proteins in turkey erythrocyte membranes and the activation of adenylate cyclase by the (?)-epinephrine-bound β-adrenergic receptor. It was observed that cationized ferritin has only a small direct effect on the β-receptor and on the adenylate cyclase moiety. It is concluded that the cationized ferritin-induced inhibition of the hormone-dependent cyclase activity results from the inhibition of the lateral mobility of the receptor and therefore a decrease in the bimolecular rate of interaction between the receptor and the enzyme.     

Competitive interactions and the availability of sleeping sites for a diurnal coral reef fish

A field study was made to test whether the population size of a diurnal reef fish, the wrasse Thalassoma bifasciatum (Bloch), was limited by inter- or intraspecific competition for sleeping shelter. T. bifasciatum is often attacked at dusk by two small territorial damselfishes, Eupomacentrus dorsopunicans (Poey) and E. planifrons (Cuvier). Although these three species sleep in the same general habitats, there are qualitative differences in the types of holes they use and how they use them. Wrasse holes are usually in these damselfishes' territories, but damselfish attacks do not prevent wrasses entering holes. Wrasses infrequently defend their holes intraspecifically. They regularly change their holes, with little intra- or interspecific aggressive interaction. When its hole is removed, a wrasse is late in retiring but finds a hole near its old one with little aggressive interaction, and does not have a higher mortality rate. Empty wrasse holes are rarely refilled, and then only by conspecifics. Wrasses added to reefs find unoccupied holes and do not usurp other fishes' holes. Damselfish defend their eggs and food against the wrasse, but not their sleeping shelter, nor living space per se. Sleeping sites are not limiting the wrasse, but are present in a surplus. Intraspecific hole defense by a wrasse prevents a delay in its retiring that would increase the risk of crepuscular predation on it.