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Rapid vascular escape of arterially injected 16alpha-radioiodo,17beta-estradiol

Purpose : We undertook this study because confirmation of a rapid vascular escape and slow release back into the circulatory system suggests that arterial injection of radiohalogenated steroid receptor ligands might provide an efficacious route of administration for imaging or treatment of receptor-rich malignant tumors in peripheral tissues. Methods and Materials : We injected radiolabeled 16alpha-iodo,17beta-estradiol ([IFE~ an estrogen receptor ligand, into the femoral artery of swine in a solution that contained [ 125I–E in a known ratio to [ 99mTc]-labeled red blood cells. Fractions of femoral venous blood were collected at short intervals during 10 min. We looked for changes in the ratio of the radiolabels. [ 99mTc]-labeled red blood cells are known to remain in the vascular system for an hour or more. Results : After passage of the injectate through the capillary bed of the swine leg, a dramatic decrease of the initial 125I: 99mTc ratio to only 10% was observed in the femoral venous blood. This ratio increased gradually during the next 10 min to approximately 30% of that in the injectate, indicating that a significant portion (approximately 90%) of the [ 125I]-E was initially trapped in the limb and then slowly re-entered the vascular system. To obtain visual confirmation of the rapid vascular escape of iodo-estrogen, we injected either an imageable form of [I]-E ( 123E) or [ 99mTc]-labeled red blood cells into the dorsal aorta of superovulated rabbits, whose smaller size allowed whole body imaging. The biodistributions of these radiopharmaceuticals were surveyed continuously by real-time planar gamma imaging. Within 2 min after the injection of [ 123I]-E, the outlines of the circulatory system were entirely lost; however, some estrogen receptor-rich tissues (the ovaries) as well as some non-target tissues, for example, the lower leg extremities, yielded well-defined images. In contrast, after intra-arterial injection of [ 99mTc]-labeled red blood cells, the circulatory system remained sharply defined for the duration of the study (40 min). Conclusion : A large fraction of [I]-E escapes from the vascular system during the fast pass through an organ or limb, without regard to the estrogen receptor content of the tissue.

Serum gonadotropins and gonadal steroids associated with ovulation and egg production in sea turtles

Changes in serum concentrations of gonadotropins and gonadal steroids during the periovulatory period were monitored in green, Chelonia mydas, and loggerhead, Caretta caretta, sea turtles. Turtles were from natural populations that nest on a coral island on the Great Barrier Reef. After nesting, each turtle was transferred to a holding tank and held for a maximum of 8 days. A time series of blood samples was obtained from each of five sea turtles (three C. mydas and two C. caretta) starting immediately after nesting and then at approximately 12-hr intervals until the time of release. Prior to release back into the ocean, each turtle was examined by laparoscopy to verify that ovulation had occurred. Serum concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), progesterone (PRO), and testosterone (T) in both species exhibited significant changes during this period. Surges of FSH, LH, and PRO were evident within approximately 20 to 50 hr after each turtle had nested. The significant change in FSH concentration during the periovulatory period is the first such report for a reptile. Coincident with maximal concentrations of FSH, LH, and PRO was a decline in T concentrations in both species. Estradiol-17β concentrations were near or below assay sensitivity in the C. mydas, whereas those in the C. caretta were detectable but exhibited no significant changes. The dynamic changes in FSH, LH, PRO, and T concentrations are consistent with the hypothesis that these hormones facilitate specific physiological events during ovulation and egg production.

A model for the deposition of hydrothermal manganese near ridge crests

A two‐stage scavenging model is used to describe the transport of hydrothermal Mn to the sediments adjacent to ridge crests. Dissolved Mn is hypothesized to be scavenged by slowly settling metal‐depositing capsuled bacteria which, in turn, are incorporated into rapidly settling macroaggregates. Upon reaching the seafloor, the Mn is subject to resuspension in particulate form and to remobilization within the sediment column and release back into the water column as dissolved Mn. Measured Mn distributions in the vicinity of the southern Juan de Fuca Ridge and estimated values of process rate constants are used to limit the range of possible model outcomes. The results present a picture of water column distributions and fluxes of dissolved, fine particulate, and large‐particle associated Mn in a plume advecting off axis. The model and best available parameter values suggest that more than 80% of the hydrothermal Mn is deposited within several hundred kilometers of the ridge crest, though dissolved Mn concentrations beyond that distance exceed background levels by many times. The residence time of hydrothermal Mn in the water column is of the order of several years. An off‐axis component of advection of the order of 0.1–0.3 cm/s is needed to make similar the model and measured distributions of Mn depositing in the sediments.

Modeling problems in conservation genetics using captive Drosophila populations: Rapid genetic adaptation to captivity

AbstractLong‐term captive breeding programs for endangered species generally aim to preserve the option of release back into the wild. However, the success of re‐release programs will be jeopardized if there is significant genetic adaptation to the captive environment. Since it is difficult to study this problem in rare and endangered species, a convenient laboratory animal model is required. The reproductive fitness of a large population of Drosophila melanogaster maintained in captivity for 12 months was compared with that of a recently caught wild population from the same locality. The competitive index measure of reproductive fitness for the captive population was twice that of the recently caught wild population, the difference being highly significant. Natural selection over approximately eight generations in captivity has caused rapid genetic adaptation.Captive breeding strategies for endangered species should minimize adaptation to captivity in populations destined for reintroduction into the wild. A framework for predicting the impact of factors on the rate of genetic adaptation to captivity is suggested. Equalization of family sizes is predicted to approximately halve the rate of genetic adaptation. Introduction of genes from the wild, increasing the generation interval, using captive environments close to those in the wild and achieving low mortality rates are all expected to slow genetic adaptation to captivity. Many of these procedures are already recommended for other reasons. © 1992 Wiley‐Liss, Inc.

Prolonged occurrence of cocaine in human saliva and urine after chronic use.

Cocaine was detected by immunoassay in saliva and urine of chronic cocaine addicts for 5-10 days during abstinence. Confirmation by a less sensitive but highly specific GC/MS assay of unmetabolized cocaine was successful in saliva through the first 24 h of collection and for the initial 4-5 days in urine. Cocaine saliva concentrations and subject scores for cocaine craving and depression declined during this time and correlated significantly. The presence of unmetabolized cocaine in these biofluids long after the last drug administration suggests that multiple dosing and high exposure to cocaine in man leads to accumulation in deep body compartments and subsequent slow release back into circulation and eventual excretion. The prolonged presence of cocaine in saliva and urine may have implications in testing for cocaine use and in treatment of cocaine withdrawal.

Survival of Freshwater Drums Released from Lake Erie Commercial Shore Seines

Catch size and oxygen concentration affected survival of commercially seined fresh-water drums Aplodinotus grunniens intended for release back to Lake Erie or for live transport to fishing ponds. Survival was inversely related to the time that fish in beached seines were exposed to deoxygenated water and, in general, survival was greater in smaller catches (1-3 tonnes) than in larger catches (7-30 tonnes). Dissolved oxygen (DO) concentrations declined drastically with the length of time fish remained in the beached seine and with increased catch size. Fish sampled from water with more than 6 mg DO/L had greater survival than fish taken from water with 2-6 mg DO/L; oxygen levels below 2 mg/L were associated with high mortality. Survival was not related to water temperature (14.5-19.5°C), and large fish were less affected by seine capture than were smaller fish. Maintenance of oxygen levels in the seine by encouraging water flow into the beach seine, direct delivery of oxygen, or less crowding of captured fish are proposed to improve survival of released fish. A model to predict the survival of released fish indicated that approximately 85% of the freshwater drums die after release from Sandusky Bay (Ohio) shore seines during the spring fishing season.

Sedimentary and Geochemical Systems in Transitional Marine Sediments in Northern Gulf of Mexico: ABSTRACT

The coastal zone of the northern Gulf of Mexico is marked by a series of bays and estuaries that serve as the principal depositional basins for rivers draining an area of greater than 160,000 km2. These rivers annually contribute a sediment load to the basins in excess of 12 million tons. Because each river drains a watershed of different lithologic character and each river is further characterized by a different flow regime and hydraulic properties, the sediments deposited in the marginal basins have unique characteristics. Extensive municipal and industrial dumping of effluent over the years has also acted to imprint geochemical differences on each of the depositional basins. Depending on the degree of industrialization within the watershed, the bays and estuaries may be described as heavily impacted (Mobile Bay), moderately impacted (Apalachicola Bay, Mississippi Sound), or slightly impacted (Pensacola Bay). A strong correlation was observed between the degree of heavy metal contamination and the textural and organic content of the sediments. Analyses further indicated that most metals were partitioned in the bottom sediments in forms that would permit their subsequent release back into the water column or would allow transference of the metal to fauna by ingestion. End_of_Article - Last_Page 1424------------

Uptake and Conversion of Selenium by a Marine Bacterium

Bio-conversion of Se was examined by incubating Pseudomonas marina in seawater containing either selenite (Na2SeIVO3) or selenate (Na2SeVIO4). At the concentrations of selenite and selenate used (10−4–10−7 mol/L), the growth of P. marina was not inhibited. Under these conditions, selenite was taken up by P. marina, but selenate was not found to enter the cells. Pseudomonas marina incorporated selenite from filtered seawater into sub-cellular fractions, primarily protein (30–50%) and amino acids (44–70%). When incubated in marine broth, P. marina incorporated 75selenite primarily into protein (up to 75%), with a lesser amount into the amino acid fraction (approximately 25%). Insignificant amounts were associated with the bacterial lipid fraction. SeIV was found in the protein and amino acid fractions within 10 min of incubation in medium containing selenite. In uptake studies the level of SeIV in the incubating medium decreased markedly, corresponding presumably to SeIV entering the bacterial cells from the medium. However, simultaneous measurements of total Se in the medium (gas–liquid chromatography following photooxidation) revealed an increasing amount of non-SeIV species of Se in the medium throughout the same period. These results were interpreted as due to the bioconversion of selenite by P. marina into water-soluble non-SeIV metabolite(s) and their subsequent release back into the medium. Up to 35% of the total Se found in the medium after 24 h can be accounted for by this conversion of SeIV into another oxidation state. Pseudomonas marina is also capable of reducing SeIV to elemental Se; this pathway becomes increasingly evident at higher concentrations of Na2SeO3.

The relationship between sugar metabolism and potassium translocation by caries-inducing streptococci and the inhibitory role of fluoride

The caries-conducive strain FA-1 of Streptococcus mutans removed more glucose than sucrose during anaerobic incubation, mainly at pH 5.8, in a medium that did not promote growth. The addition of fluoride reduced the sugar disappearance but this reduction was partly alleviated by extra potassium. The uptake of potassium by the cells was also greater in the presence of glucose than sucrose. Potassium was extruded from both fermenting and non-fermenting cells on addition of about 50 ppm fluoride. This was accompanied by a rapid uptake of fluoride by fermenting cells followed by an immediate release back into the fluid phase. Simultaneously, the concentration of intracellular sugar was higher in the presence of glucose than of sucrose. The intracellular sugar increased during the initial disappearance of the external sugar but diminished during the period of reduced sugar utilisation. Fluoride or potassium modified the intracellular sugar changes only slightly or negligibly. Acid production from the cells was greater from glucose than sucrose and both were slightly enhanced by potassium. Acid production was completely inhibited by about 50 ppm fluoride concentration. The results suggest a close association of potassium transport of this streptococcus to sugar uptake and metabolism. The inhibition by fluoride of sugar uptake and metabolism seems to be largely due to its interferring action of the cation translocation and vice versa.

Nomenclature in Elasticity

IN reference to a communication of mine which you published not long ago (see NATURE, vol. xxxi. p. 504) on this subject, I have pleasure in enclosing for publication, should you think fit, photos from three automatically recorded stress-and-strain diagrams made in my laboratory. The originals were traced on smoked glass, the glass plate then varnished to fix it, and used at once as a negative. Test-piece No. 9461, of which Fig. 1 shows the behaviour, was a very ductile piece of Swedish bariron, turned to ¾-inch diameter. The extensions were measured on a length of 10 inches, and recorded double full size; they are to be measured from the curved base-line, distances along which measure the total load on the piece (on a scale, as recorded, of about 1.9 tons per inch), and therefore the load per unit area (or, as I prefer to call it, the intensity of stress) up to the limit of elasticity, to which point the cross-section remains practically unchanged. The point where instability comes in is very marked, and also the release or going back of the stress after the material has “broken down.” Lastly, the condition of local flow, or whatever it is to be called, is excellently shown. The material draws down in one place, so that the increase of extension, being confined to that place, is very small, and the total load diminishes, although the intensity of stress, on the now greatly reduced area, is much increased, as is shown further on in Fig. 4.