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[Antioxidant stabilization of the antifoaming agents used in the fermentation process].

Oils used as antifoaming agents in fermentation are subjected to oxidation to form various products, such as aldehydes, carboxylic acids, peroxides, etc. The negative effect of such products on biosynthesis of chlortetracycline by strains VUA 84 and Iz 22/VUPL of Str. aureofaciens was recorded. The level of the oil oxidation was characterized by the contents of peroxides and epihydrinaldehydes. The Kreiss qualitative test was modified for quantitative estimation of epihydrinalydehydes. The oil antifoaming agents characterized by the routine parameters used in determination of oil quality, such as acid number, saponification number and iodine number. In the control experiments lard and soybeen oil were oxidized by air at a temperature of 100 degrees C without an antioxidant (2,6-ditetrabutyl-4-methylphenol). The oil antifoaming agents such as soybeen oil and lard were tested in biosynthesis of chlortetracycline carried out in flasks and pilot plant 750 1 apparatus. Antioxidant 4K, an alkylphenol antioxidant, in a 2% concentration proved to be effective for prevention of oxidation and nontoxic for the culture.

Antifoaming Agents↗

Microemboli observed in deaths following cardiopulmonary bypass surgery: silicone antifoam agents and polyvinyl chloride tubing as sources of emboli.

Refractile foreign particles within clear vacuoles were observed in capillaries of 17 patients who underwent cardiopulmonary bypass surgery, died, and were autopsied at the George Washington University Hospital from December 1978 through April 1981. The postoperative survival time ranged from less than one day to more than eight months. The approximate maximal diameter of the individual particles was 10 micrometer and that of the vacuoles 60 micrometer. The particle-droplet complexes showed affinity for hydrophobic stains. In all 17 cases, the kidneys were involved in combination with several other organs. In two patients, the emboli were associated with microinfarcts in one or more organs. Scanning electron microscopy (SEM) of the polyvinyl chloride tubing used during four cardiopulmonary bypasses showed spallation and shredding of the luminal surface in the areas exposed to the roller pump heads. This suggested that fragments of polyvinyl chloride might be the particles in the emboli. Another possible source was the antifoam agent used in the bubble oxygenator. Scanning electron microscopy x-ray microprobe analysis of the foreign material within capillaries of several organs showed it to be strongly positive for silicon but not for chlorine. Therefore, it was concluded that the microemboli were droplets of antifoam agent, the refractile particles corresponding to the particulate silica component and the vacuoles corresponding to the dimethylpolysiloxane liquid component. Since x-ray microprobe analysis of the microemboli did not reveal a strong chloride peak, there is as yet no evidence that polyvinyl chloride fragments were involved in the microembolism. The morphologic findings reported here indicate that antifoam microembolization continues to complicate cardiopulmonary bypass surgery and must, therefore, be considered a potential cause of postoperative morbidity. The consequence of the fragments of polyvinyl chloride tubing released into the circulation remains to be established.

Antifoaming Agents↗

Double contrast preparations: an in vitro study of some antifoaming agents.

An apparatus is described for the study of foam formation in double contrast preparations in vitro. Antifoaming agents are shown to be of considerable benefit to the double contrast technique, silicone and silicone-free antifoamers being equally effective. Silicone antifoamers are preferred because of their wide clinical acceptability. Antifoamer formulation and concentration are found to be critical factors in determining efficacy of foam suppression, and may lead to erroneous results in the clinic.

Antifoaming Agents↗

[Antifoaming agent microembolism in patients undergoing extracorporeal circulation. Its frequency in post mortem material and its pathogenic potential in vitro].

Antifoam microembolisms in patients that undergo open heart surgery, represent a risk for postoperative complications. We decided to study its frequency in an autopsy population of patients who died after heart surgery. Forty-five patients were selected and histological sections from the kidneys were studied under light microscopy, scanning electron microscopy and X-ray microanalysis. Thirty-six cases (80%) showed microemboli in the glomerular capillaries lumens. There was a positive correlation between the number of particles found and the length of the surgery. Microemboli were composed of an amorphous fraction and a particulated one composed of silicon. In vitro experimentation demonstrated that the particles are capable to induce cell lysis in a dose related manner. They also are susceptible of been phagocitated by macrophages. We conclude that bubble oxygenator are capable to induce microembolisms in a high percentage of the cases studied. Components of the microemboli are cytotoxic. Therefore microembolisms could be participating in the morbidity of patients subjects to cardiopulmonary bypass.

Antifoaming Agents↗

[Effect of sodium dodecylbenzenesulfonate and antifoaming agents on the endonuclease activity of Serratia marcescens].

The effect of sodium dodecylbenzene sulfonate (sulfonol) and certain froth breakers on the activity of endonuclease was studied in the cultural broth of Serratia marcescens in order to find out whether sulfonol could be used for limiting the infection. Sulfonol was found to have no effect on the cultural growth; it increased the activity of endonuclease in the cultural broth, and the peak of the activity appeared earlier than in the control medium. Propanol B-400 was shown to be the best froth breaker.

Antifoaming Agents↗