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Pulse oximetry is a noninvasive technique for measuring O2 saturation (SpO2) continuously. We applied pulse oximetry to 9 pediatric patients with tetralogy of Fallot during shunt surgery. Arterial oxygen tensions (PaO2) and saturations (SaO2) were also measured at the time of postinduction, just before the shunt, after the shunt and at the end of the operation. The SpO2 and SaO2 levels were identically changed in all 4 periods. The PaO2 was increased a little without statistical significance after the shunt procedure and at the end of the operation compared with the values before the shunt. However, SaO2 values increased with statistical significance after the shunt procedure and SpO2 values also showed similar increases with significance. In conclusion, continuous monitoring of SpO2 by pulse oximetry, instead of PaO2, is a very useful and reliable method to assess the improvement of perfusion after shunt, particularly in cyanotic cases.

The effects of chemical quench reactions on the formation of organic compounds at a water surface under simulated primordial earth conditions were investigated for the study of chemical evolution. A mixture of gaseous methane and ammonia over a water surface was exposed to an arc discharge between an electrode and the water surface. This discharge served as a source of dissociated, ionized and excited atomic and molecular species. Various organic molecules were formed in the gaseous, aqueous, and solid states by a subsequent quenching of these reactive species on the water surface. The effects of these water-surface quench reactions were assessed by comparing the amounts of synthesized molecules to the amounts which formed during the discharge of an arc above the water level. The results showed that: (1) the water-surface quench reaction permitted faster rates of formation of an insoluble solid and (2) the quench discharge yielded twice as much amino acids and 17 times more insoluble solids by weight than the other discharge. The highest yield of amino acids with the quench reaction was 9 x 10-7 molecules per erg of input energy. These observations indicate that quench reactions on the oceans, rain, and clouds that would have followed excitation by lightning and shock waves may have played an important role in the prebiotic milieu. Furthermore, the possibility exists that quench reactions can be exploited for the synthesis of organic compounds on a larger scale from simple starting materials.

The coupling of fluorescamine (4-phenylspiro[furan-2(3H), 1'-PHTHALAN]-3,3'dione) to angiotensin II to form a fluorescent derivative was studied. Complete reaction of the peptide below concentrations of 10- minus 4 M could be achieved with a fluorescamine concentration of 0-3 mg ml- minus 1 of acetone at pH 8-3, and the lowest concentration detectable by fluorescence spectroscopy was 100 pmol ml- minus 1. The derivative, as prepared did not react with ninhydrin, and no fluorescence was generated when fluorescamine was reacted with (1-Sar)-ATII. These data suggest that fluorescence is generated only through the coupling of fluorescamine to the N-terminal primary amine of ATII. The ATII-fluorescamine derivative has the same intrinsic activity on the contraction of rat colon (elevenfold loss of affinity), and on the release of fluorogenic corticosteroids from bovine adrenal cortical slices (sixfold loss of affinity) compared to ATII. Water-hydrolysed fluorescamine and Asp-fluorescamine did not contract rat colon preparations; the contractile response to ATII-fluorescamine was blocked by (8-Leu)-ATII, a specific ATII antagonist. These findings suggest that theATII fluorophore shares a common receptor site with the native octapeptide. The rate loss of biological activity of the ATII-fluorescamine derivative was appreciably lower than that observed for ATII. The present study suggests that the ATII-fluorescamine derivative can be substituted for radioactively-labelled ATII for use in a variety of applications.

The action of angiotensin II (ATII), 1-des-Asp-ATII (Hepta-2-8), angiotensin I (ATI), 1-Sar,8-Gly-ATII and catecholamines on isometric force and transmembrane potential were studied in rabbit isolated atria, driven electrically. In some experiments two microelectrodes were implated to record simultaneously cjamges of intracellular electrical events in the left and in the right atrium: changes of tension were recorded isometrically. In other experiments changes of transmembrane potential were measured with floating microelectrodes. Norepinephrine and epinephrine increased tension, prolonged the plateau phase of the action potential (A.P.) in both atria, while facilitating conduction. ATII and 1-des-Asp-ATII showed similar effects on tension and greater changes on the electrical events of the left than on the right atrium, while ATI was more effective on the right than on the left atrium. 1-Sar, 8-Gly-ATII had no direct effect but prevented or reduced the action of ATII, 1-des-Asp-ATII and ATI, without influencing norepinephrine and epinephrine. All angiotensions except 1-Sar,8-Gly-ATII slightly prolonged the time of conduction. The results indicate that: a)angiotensins and catecholamines prolong the duration of the action potential and induce minor changes of potential overshoot in atrial fibers; b) ATII and 1-des-Asp-ATII act preferentially on the left and ATI on the right atrium; c) 1-Sar,8Gly-ATII inhibits secifically the effects of ATII and ATI in this preparation.

Substitutions of 8 phenylalanine with L-alanine and D-phenylalanine abolish the myotropic action of the angiotensin II (AT(II)) analogues and confer inhibitory properties on the molecule. [8-L-Ala]-AT(II) and [8-D-Phe]-AT(II) antagonize specifically the myotropic action of AT(II) and angiotensin I (AT(I)) on the rat colon, while the action of other myotropic agents (acetylcholine, 5 hydroxytryptamine) is not modified.