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At least 883 records · Page 49Linked to original sources
PubMed1976

[Trials of artificial vaginas for bulls (author's transl)].

Introduction of short artificial vaginas with smooth plastic inner liners and without any internal pressure reduced the bacterial contamination of bull semen to a very considerable extent. Moreover, semen production increased, partly because of lower semen losses in short artificial vaginas with smooth inner liners which were not under pressure, partly because more intensive sexual preparation of the bulls was required to collect semen with this type of artificial vagina. When adequate sexual preparation of the bulls is practised, all bulls will accept short artificial vaginas with smooth inner liners which are not under pressure. The use of particularly rough rubber inner liners in artificial vaginas for bulls and using long artificial vaginas with internal pressure is not advisable because of unnecessarily high semen losses in the artificial vagina and unnecessary contamination of the crude semen.

Animals↗
PubMed1988

Ethical dilemmas in organ donation and transplantation.

Since the first successful organ transplantation in 1953, we have seen an explosive development in transplantation surgery, particularly during the 1980s. With it followed an abundance of legal controversies and ethical dilemmas. Optimal use of viable organs necessitated precise definition of brain death in heart-beating cadavers with artificially maintained ventilation and circulation. Viable organs must remain well perfused to be suitable for procurement and transplantation into carefully selected recipients on an equal-opportunity basis. Due consideration must be given to both medical and social indications. At present, homografts dominate the field of organ transplantation; however, because of the shortage of human organs, both artificial organs (especially hearts) and xenografts are expected to become increasingly common in the near future. No doubt, the use of such modern technology will introduce additional ethical problems.

Brain Death↗
PubMed1992

Reverse vesicles as a new system for studying enzymes in organic solvents.

A new approach to the study of enzyme activity in organic solvents has been developed by using optically transparent reverse vesicles. Polyphenol oxidase was incorporated in an active form into the above ternary system formed by the non-ionic surfactant tetra(ethylene glycol) dodecyl ether/n-dodecane/water. The enzyme in this microenvironment, surprisingly, showed an apparent positive co-operativity which has never before been described either in aqueous solution or in reverse micelles. In addition, the Vmax. expressed was similar to that in water and twice that displayed in reverse micelles.

Catechol Oxidase↗
PubMed1989

Enzymatic detoxification using lipophilic hollow-fiber membranes: III. Oxidation reactions of sulfides.

A lipophilic hollow-fiber membrane preparation that was previously described for glucuronidation and sulfation reactions was used for the enzymatic oxidation of sulfides. Endogenous and exogenous toxins in buffer solution or in serum or blood of intoxicated animals were circulated through the internal lumen of lipophilic hollow fibers. Native liver microsomes of the rabbit were circulated on the outside of the hollow fibers. Lipophilic toxins accumulate in and penetrate through the lipophilic membrane and the toxins are oxidized by the mixed function oxygenase system of liver microsomes. The oxidized products cannot rediffuse to the donor side. The endogenous toxin dimethylsulfide (DMS) was converted on the enzyme side to dimethylsulfoxide (DMSO) and small amounts of dimethylsulfone, which are hydrophilic and nontoxic substances. Other sulfide compounds, ethylmethylsulfide (EMS) and s-butylmethylsulfide (BMS), have also been converted to their oxidized forms. The enzymatic clearance of the hollow-fiber module for DMS in in vivo experiments in the rabbit was found to be 1.30 nmol/h/mg protein/cm2 hollow-fiber surface. The transmembranous enzymatic clearance of the in vitro oxidation reactions of DMS, EMS, and BMS in buffer solutions (open circuit) were measured, respectively, as 1.63, 3.45, and 5.16 nmol/h/mg protein/cm2 hollow-fiber surface. This technique allows the enzymatic oxidation of sulfur compounds with liver microsomes in vitro and in vivo without immunological hazards, and it is suited for artificial liver support.

Animals↗
PubMedDate not supplied

Bioartificial thyroid. The in vitro culture of microencapsulated rabbit thyroid tissue.

A new technique of encapsulating thyroid tissue with an artificial membrane for protection against immune attack is reported. The membrane was made of calcium alginate and a poly-L-lysin coating. The membrane prevents the diffusion of large molecules such as hemoglobin but freely permits the passage of smaller molecules such as T4 and culture medium 1640. Because larger molecules are barred, the contents of the microcapsules are safe from immune system rejection. In vitro cultured, microencapsulated rabbit thyroid tissue secreted T3 and T4, achieving a concentration of 8.68 +/- 2.93 nmol/L and 245.23 +/- 124.87 nmol/L, after 3 days; this level remained steady for 6 to 9 days of incubation. These microcapsules show promise as a treatment modality and as a possible solution to the problem of immuno-isolation.

Animals↗