Coumarin in vanilla extracts: Its detection and significance

Coumarin was a component of some commercial vanilla preparations until banned in the United States by the Food and Drug Administration in 1954 because of evidence of hepatotoxicity in animals. However, in the present investigation coumarin was detected by capillary column gas chromatography/mass spectrometry in Mexican vanilla extracts commercially available or introduced in the United States by tourists or travelers. The significance of the presence of coumarin in Mexican vanilla extracts is discussed in light of recent evidence suggesting a lack of significant coumarin toxicity in humans.     

Degradation of atrial natriuretic factor by kidney cortex membranes. Isolation and characterization of the primary proteolytic product

Synthetic rat atrial natriuretic factor (r-ANF, 1-28) was incubated with rat kidney cortex membranes, and a predominant degradation product was identified by reverse-phase high performance liquid chromatography. The degradation product was subjected to amino acid analyses and found to have a composition identical to r-ANF. Amino-terminal sequence analyses identified two distinct amino-terminal residues and suggested that cleavage had occurred between the cysteine-phenylalanine bond (residues 7 and 8) of r-ANF. This degradative process could be inhibited by 1,10-phenanthroline and EDTA, suggesting that the enzyme responsible for proteolysis is a metalloendoprotease. The enzyme exhibits a Michaelis-Menten constant of approximately 10 microM for the metabolism of r-ANF and has a broad pH optimum between 8.5 and 9.5. These findings suggest that ANF may be initially degraded in the kidney at a single cleavage site within the 17-residue ring structure.     

Adenohypophysial-thyroid activity of the tiger salamander, Ambystoma tigrinum, as a function of metamorphosis and captivity

The aim of this study was to determine the timing of adenohypophysial activation during metamorphosis of the tiger salamander, Ambystoma tigrinum. It consisted of two parts: 1) determination of plasma thyroid hormone concentrations and analysis of thyroid gland histology as a function of metamorphic stage and 2) analysis of the time-course of uptake of 125I by the thyroids during metamorphosis as an indicator of endogenous thyrotropin (TSH) levels. Significant increases in both triiodothyronine (T3) and thyroxine (T4) first were evident at the onset of metamorphic climax (stage II). Maximum levels of both hormones were not observed, however, until the completion of gill resorption (stage VII). No changes in thyroid histology were observed that could be unambiguously related to metamorphic transformation. The thyroids accumulated 125I in a slow but linear fashion in premetamorphic larvae (stage I). However, uptake exhibited a rapid peak during early climax (stage II), before maximum concentrations of thyroid hormones were observed. In addition, uptake was maintained above premetamorphic levels at stage VII, in conjunction with maximum levels of T4 and T3. Captivity alone produced a small but significant increase in plasma concentrations of T3. It produced no significant effect on either thyroid histology or uptake of 125I. These results indicate that adenohypophysial activation occurs rapidly and is maximal at the onset of metamorphic climax.     

Observations on the diagenetic behavior of arsenic in a deep coastal sediment

Vertical profiles of total dissolved arsenic, manganese and iron, pH, Eh and rates of sulfate reduction were determined in a freshly-collected box core from a 335m depth station in the Laurentian Trough. The relationships observed between the profiles were further examined in the laboratory by measuring these same parameters with time in surficial sediment slurries as the Eh decreased in response to biological activity or chemical alteration.Both field and laboratory observations have shown that arsenic is released predominantly as As(III) into reducing sediment porewaters. This occurs after the dissolution of manganese oxides and at the same time as the dissolution of iron oxyhydroxides and the onset of sulfate reduction. Laboratory experiments indicated that sulfate reduction and the production of sulfide ions are not solely responsible for the release of arsenic to the porewaters, although this process is necessary to create and maintain a highly reducing environment conducive to rapid iron dissolution.The diagenesis of arsenic in Laurentain Trough sediments involves the simultaneous release of arsenic and iron at a subsurface depth, followed by its removal from porewaters by precipitation and adsorption reactions after migration by diffusion along concentration gradients. A qualitative model is presented to describe the behavior of arsenic in coastal marine sediments.Present address: Department of Geological Sciences, McGill University, 3450 UniversityStreet, Montreal, Quebec H3A 2A7, Canada     

Permeability of intact and dechorionated zebra fish embryos to glycerol and dimethyl sulfoxide

Intact developing embryos of the zebra fish Brachydanio rerio were exposed to [¹⁴C]DMSO and [³H]glycerol (1 M in Fish Ringer) to assess the degree of permeation of these cryoprotectants. Glycerol enters the embryo more easily, although reaching only about 8% of the expected equilibrium level after 2 hr at room temperature; DMSO reaches only about 2.5% of this level. In an attempt to identify the barrier to permeation, dechorionated embryos were similarly exposed to isotopic DMSO. Permeation increased severalfold, indicating that the chorion retards the free exchange of solute. Embryos are unaffected by exposure to 1 M DMSO in Fish Ringer at 23 °C for up to 1 hr. The number of embryos hatching after 1-hr exposure to DMSO at varying concentrations was significantly reduced at 1.5 and 2 M. Embryos exposed to 1 M glycerol for 1 hr at 23 °C showed disruption of periblast cells and separation of the blastoderm; it was impossible to remove glycerol either by abrupt or very slow dilution.     

Hysterosalpingography in Cynomolgus Monkeys

This paper describes recent success in performing hysterosalpingography in cynomolgus monkeys. The animals were anesthesized, and a needle was manipulated through the cervical canal into the endometrial cavity for injection of contrast material. Difficulties in threading the needle through the canal were due to several blind pouches formed by folds in the cervical mucosa. The uterine lumen and both tubes could be visualized in over 75% of the cases. The study demonstrates that the hysterosalpingography technique can be performed satisfactorily in cynomolgus monkeys.     

Influence of Nitrogen Source, Thiamine, and Light on Biosynthesis of Abscisic Acid by Cercospora rosicola Passerini

Abscisic acid production by Cercospora rosicola Passerini in liquid shake culture was measured with different amino acids in combination and singly as nitrogen sources and with different amounts of thiamine in the media. Production of abscisic acid was highest with aspartic acid-glutamic acid and aspartic acid-glutamic acid-serine mixtures as nitrogen sources. Single amino acids that supported the highest production of abscisic acid were asparagine and monosodium glutamate. Thiamine was important for abscisic acid production. Leucine inhibited abscisic acid production. C. rosicola produced abscisic acid in the dark, but production more than doubled in the presence of light.     

Iatrogenic ascending aortic dissection following cannulation for arterial return and for infusion of cardioplegic solution: Prevention and repair

Two patients are presented in whom dissection of the ascending aorta resulted from cannulation for arterial return and from the infusion of cardioplegic solution. The dissections were recognized promptly. Following dissection in the first patient, the femoral artery was used to reestablish systemic perfusion. The aortic valve and dissected ascending aorta were replaced, and three vessels were grafted. In the second patient, the dissected anterior wall of the ascending aorta was excised and replaced with a low-porosity Dacron patch into which the proximal aortocoronary anastomoses were inserted. Predisposing factors are discussed, along with preventive measures and methods of repair.     

Supravalvular stenosing ring of the left atrium: Case report and review of the literature

This report concerns a 3(1/2)-year-old boy who had a supravalvular stenosing ring of the left atrium that produced left ventricular inflow obstruction. Echocardiographic and angiocardiographic data are presented, along with a review of the literature and possible theories as to the origin of this lesion.     

Use of a composite Biomer-butyl rubber/Biomer material to prevent transdiaphragmatic water permeation during long-term, electrically-actuated left ventricular assist device (LVAD) pumping

The pumping diaphragm of the Texas Heart Institute (THI) E-Type ALVAD must perform the dual functions of providing a flexible blood interface and isolating the electrical actuator from adjacent fluids. Thus, protection is required against fluid leakage and moisture diffusion to prevent corrosion and damage to electrical actuator components. Average diffusion rates up to 1 ml per day through currently used elastomeric diaphragm materials have been measured during static in-vitro and in-vivo tests. To circumvent this problem, an improved pumping diaphragm has been recently developed for use with the electrically-actuated THI E-Type ALVAD. This trilaminar diaphragm consists of a composite Biomer and butyl rubber design. A.010 inch layer of butyl rubber (characterized by an extremely low diffusion rate for water, approximately 0 ml per day) is positioned between two Biomer layers (.020 and.010 inches in thickness). Initial invitro and in-vivo studies, in calves, indicate that this composite diaphragm provides an excellent barrier to water permeation, without sacrificing biocompatibility or structural integrity under conditions of chronic flexure.