Homogenization Speed Research Articles

Study on the biological characteristics of intra-trophoblastic gonadotropins

The extracts of human chorionic tissues and hydatidiform moles were prepared by homogenization and high speed centrifugation. The particle free supernatant fraction precipitated by ethanol and purified samples of urinary HCG assaying 5,100 I.U. and 2,406 I.U. per mg. were subjected to zone electrophoresis in starch grain.Proteins recovered after electrophoresis from portions of the starch grain were tested for gonadotropic activities by the weight of rat ovaries, seminal vesicles and the augmentation test of Steelman & Pohley. There were found at least two biologically active components (G-A and G-B) in all of the extracts and preparations examined. G-A has luteinizing activity and G-B has follicle stimulating activity. Each electrophoretically homogeneous component could be isolated by repeated electrophoresis.The extracts of human chorionic tissues in the early stage of pregnancy have predominant G-B activity and in the late stage, G-A activity when assayed by the ovarian weight method. The extracts of hydatidiform moles have more predominant G-B activity than that of normal chorionic tissues when assayed by the augmentation test of Steelman & Pohley.The urea denaturatuion experiments and RDE digestions show that there may be differences between urinary HCG and trophoblastic HCG, between G-A of urinary HCG and G-A of urinary HMG.The acetone powder of the supernatant fraction of hydatidiform moles has the specific component with gonadotropic activity, assayed by the augmentation test of Steelman & Pohley, in the zone of segment number 35-39, which is not found in the case of normal chorionic tissues.

Storage and in vitro release rate of catecholamines from granules isolated from preaortal paraganglia and adrenals of newborn rabbits.

AbstractCatecholamine containing granules from paraganglia and adrenals were isolated by homogenization and high speed centrifugation. On incubation at 37d̀ C in potassium phosphate buffer, pH 7.4, the rate of spontaneous release from paraganglionic granules was similar to that of adrenomedullary granules with a half‐time of 30 min. These similarities between granules from the two organs are discussed in view of the different hormone contents in paraganglia (noradrenaline) and adrenals (adrenaline).

Degradation of polymers in high speed rotary homogenizers: A hydrodynamic interpretation

AbstractDilute solutions of DNA in neutral phosphate buffer and of polystyrene in toluene are degraded to limiting molecular weights by high speed stirring in a Virtis homogenizer equipped with special thin, highly sharpened blades. Results are interpreted and justified in terms of the hydrodynamic theory of laminar boundary layers. Estimates of critical stress values for chain scission are obtained at various limiting molecular weights for the two polymer systems, and the treatment is used to rationalize the dependence of degradation upon homogenizer speed. The agreement between the hydrodynamic theory and experimental data implies that limiting molecular degradation occurs entirely in the boundary layer region extending a distance equal to approximately the molecular contour length from the leading edge of the blade tip and that laminar flow conditions prevail in this region. It therefore seems likely that polymer molecules subjected to a critical shearing stress are essentially completely extended in the streamlines of flow. The hydrodynamic theory is finally used to explain the peculiar kinetics of molecular degradation in high speed rotary homogenizers.

Electrophoresis in starch gel of extracts of human anterior pituitary glands, with bioassay of gonadotrophin.

ABSTRACT Extracts of human anterior pituitary glands were prepared by homogenization and high speed centrifugation. The particle-free supernatant solution were subjected to electrophoresis on paper, in starch grain and in starch gel. A preparative method for electrophoresis in starch gel was devised. Separation of serum proteins into 14 zones was obtained with this method and the patterns obtained with pituitary extracts showed three major zones, one of which was haemoglobin, and a variable number of other zones. Protein recovered after electrophoresis from portions of the gel was tested for gonadotrophin by the mouse uterus test. Gonadotrophic activity was found among the more slowly moving fractions and could not be correlated with any individual protein zones revealed by staining with nigrosine.