C14 Uptake Research Articles

A New Biologic Membrane in Cardiovascular Surgery

Reconstruction techniques for major vessels and intracardiac defect repair use synthetic grafts or autogenic pericardium. Here, autologous abdominal parietal peritoneum with the overlying posterior rectus sheath as a biologic membrane are evaluated. Twelve adult canines were used. Via a midline subumbilical incision, the parietal peritoneum and overlying posterior rectus sheath were harvested. In the first group of six, the membrane was used to repair the right ventricular infundibulum and perform pulmonary artery annuloplasty. In the second group of six, under cardiopulmonary bypass and moderate hypothermia, the right atrium was opened and a secundum type defect was created. Autopsies performed 90 days after surgery revealed mild intrapericardial adhesions and moderate pericardial reaction over the cardiotomy incisions. The right ventricular outflow tract patch was nonaneurysmal. The interatrial patch was intact without thrombi. Histologic examination revealed intact membrane morphology, fibroblasts, smooth muscle cells, and endothelialization. Proline C14 uptake and autoradiography detected cellular viability of implanted membranes. These findings suggest that the peritoneum with overlying sheath repaired vascular and intracardiac defects and substituted for pericardium. Future studies are needed before clinical use.

Produtividade primária, biomassa e fatores limitantes na área estuarina SW da Baía de Todos os Santos

The primary production by C14, standing crop as ratio of particulate carbon/nitrogen and biossay tests concerning to dissolved nitrogen and phosphorus were investigated in the SW estuahne mangrove area of the Bay of Todos os Santos (Brazil) during 10 months. The phytoplankton displaied in this area a mean density of 9x105 cells/liter. The primary productivity showed an average range of 9.52 to 10.93 mgC/m3/h, representing the rate about 45 g C/m3 /year or 181 g C/m2 /year. Phytoplankton fraction under 35µ at the stations 0 and 1 was responsible for the most C14 uptake. A negative relationship between primary production and limiting nitrogen and phosphorus was verified. February samples exhibited the most drastic situation regarding to N and P, as limiting factors; an opposite situation corresponded Jo June and July. The relationship between particulated carbon and nitrogen showed a concentration area among the ranges of400/1400 mgC/m3/ and 4/28 mgN/m3, The ratios C/N revealed the most of times a short variation.

A Comparison of Benthic Microalgal Production Measured by C14 and Oxygen Methods

A comparison of estimates of benthic primary production on a sandy beach measured by in situ oxygen and laboratory C14 methods showed that both methods gave similar measures of the magnitude of production. Sources of error in each method are discussed. Measures of C14 uptake offer sensitivity when production is low, but when undisturbed sediment cores can be obtained, production is most easily measured by following changes in dissolved oxygen.

Self-diffusion of carbon and oxygen in calcite by isotope exchange with carbon dioxide

Carbon self-diffusion coefficients were determined by exchange between calcite grains and a large reservior of C14-labeled CO2 at 250°–750°C. The progress of diffusion and the surface area of the grains were measured by the C14 uptake of the solid. Both carbon and oxygen self-diffusion coefficients were determined by exchange between calcite grains and a limited reservoir of C13- and O18-enriched CO2 at 650°–850°C. The progress of diffusion was measured by the change in isotope composition of the gas. On an Arrhenius plot of log D versus 103/T°K, the carbon self-diffusion coefficients are fitted to two straight lines. Carbon diffusivity determined by both methods in unannealed and annealed material at temperatures above 550°C are given by D = 1.3 × 103 exp(−88,000/RT)cm2/sec. Oxygen self-diffusion coefficients were higher than the corresponding carbon values by up to a factor of 4. Carbon diffusivity determined by the C14 method in unannealed calcite below 550°C are given by D = 4.6 × 10−16 exp(−17,000/RT)cm2/sec. Diffusivity in annealed material is lower by a factor of 50. The relative rates of oxygen and carbon self-diffusion indicate that there may be several mechanisms of oxygen migration in calcite in the high temperature region. A detailed examination of the C14 uptake results suggest that carbon self-diffusion is depth-dependent for the shallow penetration distances obtained in these experiments. Extrapolation of these results suggests that solid-state diffusion will not significantly alter the isotopic record of calcite under a wide range of geologic environments.

Algal Growth and Primary Productivity in a Thermal Stream

Estimates of primary production and respiration of cyanophycean algal species growing in the run-off stream of a hot spring (37 C) were obtained throughout 1966 using the diurnal oxygen curve technique. Rates of gross primary production were slightly higher than published values from other aquatic ecosystems, but were less than recent estimates from hot springs in Yellowstone and Mount Lassen National Parks using the C14 uptake method. Production/respiration ratios were calculated and ranged from 1.1 to 5.0. The effect of photosynthesis on the ionic concentration of influent and effluent water was noted, together with morphological changes in the algal mat as the growing season progressed. Changes in algal standing stock were studied in 1964 and 1965, together with growth rates from denuded areas by two methods of harvest. In both years the most rapid growth was recorded in May and June, whereas during the winter months growth was negligible. Maximum values of primary production in May and June 1966 coincided with these maximum growth periods. Significant differences in growth rates between years were thought to be due to several factors; most notably, harvest methods and auto-inhibitory toxins produced by layers of senescent cells composing the "mature" algal mat. Energy losses due to algal export and grazing are discussed in relation to the dynamics of the mat, and an annual energy budget is derived from estimates obtained in 1966.

UPTAKE OF C-14-1-PALMITIC ACID-P-32-PHOSPHOLIPID LABELED CHYLOMICRONS BY PERFUSED LIVER AND LIVER SLICES.

SummaryLiver slices from post absorptive dogs and fed rats were incubated for up to 3 hours with chylomicrons containing C14-palmitate and P32-phospholipid suspended in phosphate buffer. The ratio of P32/C14 in the liver slices was in most instances higher than that of the substrate chylomicrons. Re-incubation of the dog liver slices with buffer or nonlabeled chylomicrons showed some release of C14 and P32. Cyanide failed to inhibit lipid uptake by dog liver tissue, but lowered temperatures reduced the uptake. Dog liver slices deactivated by heating took up chylomicron P32 but the C14 uptake was greatly diminished from normal. Separation of chylomicrons into different size classes by centrifugation in sucrose gradients showed that the smaller particles are relatively richer in P32 than the larger chylomicrons. Evidence indicates, however, that the high P32/C14 ratios in the liver slice are probably not caused by preferential uptake of small chylomicron particles. The perfused rat liver took up the two lab...

Effect of Fasting on the Incorporation in Vitro of Palmitate-C14 into Glycerolipids of Mitochondria

The effect of a 24-hour fast and a re-feeding of glucose, corn oil, or egg albumin by a stomach tube following the fast upon the incorporation of palmitate-1-C14 into various lipids of rat liver mitochondria was determined. Both normal animals and animals with regenerating livers were used. Fasting depressed the incorporation of palmitate-1-C14 into both triglycerides and total phospholipids. The latter was reflected in an almost complete cessation of the incorporation of C14 into ethanolamine phosphatide, and little change in that of the inositol and choline phosphatide. When the fasted rats were fed glucose, the incorporation of C14 into triglycerides and ethanolamine and choline phosphatides increased. Re-feeding corn oil depressed the incorporation of palmitate-1-C14 into the lipids and re-feeding egg albumin increased C14 uptake by the phospholidips but not by the triglycerides. With mitochondria from regenerating livers, the incorporation of palmitate-1-C14 into the choline phosphatides was markedly increased, and that in the other lipids decreased when compared with the values found employing mitochondria from normal livers. Fasting the partially hepatectomized animals resulted in lower incorporation of C14 into choline phosphatides and triglycerides. Glucose, corn oil, and egg albumin re-feedings generally had the same effects on regenerating liver mitochondria as on normal ones.

Metabolism of red and white muscle fiber groups.

Rat adductor fiber groups, predominantly composed of either red or white muscle fibers, have been utilized to demonstrate metabolic differences in these two types of voluntary skeletal muscle. Glycogen concentrations of muscle obtained immediately after sacrificing the rats were higher in white than in red muscle, but at the end of 2-hr incubation this relationship was reversed. No difference could be demonstrated in glucose uptake in the two types of muscle, while lactate production was greater in white than in red muscle. Acetoacetic acid uptake by red muscle was higher than that by white muscle as measured by chemical analysis and uptake of acetoacetic acid-C14. A lower percentage of acetoacetic acid-C14 uptake appeared in the lactate fraction in white as compared to red muscle fiber groups. In the case of glycogen, this relationship was reversed and a larger percentage of C14 uptake appeared in the glycogen fraction of white as compared to red muscle. Oxygen uptake and the counts from acetoacetic acid-C14 appearing in C14O2 were higher in red than in white muscle. The creatine phosphate level, after 2-hr incubation, was higher in white muscle. These data demonstrate striking differences in the relative distribution of various metabolic pathways in red and white muscle.

RELATIONS BETWEEN PRIMARY PRODUCTION, CHLOROPHYLL AND PARTICULATE CARBON

In two very different areas in the North Sea, Aberdeen Bay (7 m) and the Fladen Ground (140 m) seasonal cycles of C14 uptake, chlorophyll and particulate organic carbon were observed. The ratios of C14 uptake to chlorophyll concentration showed marked variations seasonally. There were no signs of “dead” chlorophyll or of a decrease in the ratio due to nutrient deficiency. The ratios of chlorophyll to particulate carbon suggest that in coastal waters living plants generally form the most important part of the particulate carbon. At the deeper position the ratio was much smaller so that chlorophyll is not a good index of organic matter in the water.

Effects of plasma erythropoiesis stimulating factor (E.S.F.) at different time intervals after single injection.

SummarySeveral effects of E.S.F. in normal mice were studied as a function of time after injection. The first change was a marked increase of C14 amino acid uptake by globin at 24 hours. This was followed at 48 hours by increase in iron consumption by erythroid tissue, and at 72 hours by an increase of reticulocyte count in peripheral blood as well as by increase in Fe59 and leucine C14 uptake by incubated red cells.

Use of Radioisotopes in Hydrobiology and Fish Culture

Use of radioisotopes has increased rapidly in hydrobiology and fish culture. Their use, especially P32, to study circulation of nutrients has been demonstrated and offers opportunities in problems of lake metabolism. The most extensive use of isotopes has been to determine photosynthetic activity in plankton through C14 uptake. Applications and limitations are discussed. Isotopes have been successfully used in food studies of fish to determine food selection, metabolism, and storage. Water movements in fresh and salt water and in sewage problems have been successfully followed by use of various isotopes. Marking of aquatic animals with radioisotopes has many possible applications, but has been little used because of some inherent problems related to danger to organisms and in field use. Extent of future use of isotopes in hydrobiology will be determined by further study of hazards and public acceptance of field studies.

Primary Production of Continental Shelf Waters off New York1

The chlorophyll‐radiation method of measuring primary production, described earlier by the authors, was employed on six oceanographic cruises during 1956–7, each occupying 25 stations across the continental shelf off New York. The relationship photosynthesis/ hour (opt. light):chlorophyll a, using the oxygen production method, was found to agree with that determined earlier from culture and harbor water experiments, despite wide variations of temperature, nutrients, and the abundance of phytoplankton. The same ratio, with photosynthesis measured by C14 uptake, was extremely variable and usually lower than that obtained by oxygen‐production photosynthesis values.Estimates of daily production beneath a square meter of sea surface by the chlorophyll‐radiation method and in situ C14 values agreed within reasonable limits in 75% of the measurements; for the remainder of the times the C14 values were consistently lower.Daily production throughout the year ranged roughly from 0.20 to 1.00 g carbon/m2/day within the whole area studied. Estimated annual production decreased in a seaward direction from 160 g carbon/m2/year in the shallow coastal waters to 100 g carbon/m2/year on the continental slope. These values are intermediate between Riley’s estimates for Long Island Sound and the Sargasso Sea.