Incubation

About: Incubation is a research topic. Over the lifetime, 5748 publications have been published within this topic receiving 126541 citations.

Induction of thermotolerance in Chinese hamster ovary cells by high (45 degrees) or low (40 degrees) hyperthermia.

Abstract: Thermotolerance induced in Chinese hamster ovary (CHO) cells by a 45° heat treatment and developed at 37° resulted in an increased D 0 but a reduced extrapolation number, n , of a subsequent 45° heat survival curve. The time course and magnitude of thermotolerance development were dependent upon the conditioning hyperthermia treatment. Within 2 hr after a 10-min exposure to 45°, the n of the subsequent 45° hyperthermia survival curve increased approximately 5-fold with little change in the D 0 . Thereafter, n returned to control values, whereas the D 0 increased by a factor of 5 by 8 hr and then only slowly disappeared at a rate of 0.1 min at 45° per hr of incubation at 37°. A conditioning dose of 5 min at 45° increased the D 0 of the subsequent 45° heat survival curve by a factor of 3.3 within 2 hr, but then the D 0 returned to control values at the same rate as after a conditioning treatment of 10 min at 45°. CHO cells incubated at 40° grew normally without any evidence of cell killing for more than 2 generations, and incubation at 40° for 0 to 7 hr prior to acute heating at 45° did not induce thermotolerance in terms of an increased D 0 . However, the D q of the 45° heat survival curve was increased approximately 3-fold by 40° preincubation for 7 hr. Increasing the incubation temperature from 37 to 39–41° between 45° heat treatments did not alter the thermotolerant D 0 of the subsequent 45° heat survival curve but did reduce n to 1.0. In addition, the survival curves following 45° conditioning and incubation at 39, 40, or 41° were displaced downward by factors of 5.3, 47, and 360, respectively. The enhanced cell killing resulting from post-45° hyperthermia incubation at 39–41° may be due to the conversion of sublethal damage to lethal damage independently of the induction of thermotolerance.

Physicochemical and structural characteristics of sodium caseinate biopolymers induced by microbial transglutaminase

Abstract: Some physicochemical properties and structural characteristics of microbial transglutaminase (MTGase)-induced biopolymers of sodium caseinate (SC) were investigated. The sodium dodecyl sulfatepolyacrylamide gel electrophoresis and size-exclusionhigh-performance liquid chromatography analyses showed that all components of SC were easily polymerized or transformed by MTGase to form high-molecular weight biopolymers, and the susceptibility order of individual components was kappa-Casein (C) > alpha-C > beta-C. The emulsifying properties of biopolymers depended on the incubation time with MTGase. The emulsifying activity index of biopolymers persistently increased with the MTGase (0-12 h) incubation time. The emulsion stability also increased with the incubation time (< 4 h), then declined a little with longer incubation (412 h). The differential scanning calorimetry analysis showed that the thermal properties of the biopolymers obtained after a 12-h incubation were different from that of native SC or biopolymers obtained after a shorter incubation time (< 4 h), suggesting that the former has higher thermal stability. In addition, the ultraviolet (UV) spectra showed that the UV absorbance (at 275 nm) of MTGase-induced biopolymers of SC decreased with an increasing incubation time with MTGase, and the maximal emission wavelength (lambda(max)) slightly shifted to the "blue side." The fluorescence spectra showed that the lambda(max) was related with incubation time with MTGase, slightly shifting to the "blue side" after 4 h with no further changes; its relative fluorescence intensity also increased. These results suggest a relationship between the functionalities and structural characteristics of the MTGase-induced biopolymers of SC.

Amino acid incorporation in vitro into protein of neuronal and glial cell-enriched fractions.

Abstract: — Slices of rabbit cerebral cortex were incubated in the presence of labelled amino acids. Following incubation, neuron- and gliaenriched fractions were obtained by density gradient centrifugation and the TCA-insoluble radioactivity determined. The protein-bound radioactivity was five to six times higher in the neuronal-enriched fraction than in the glial-enriched fraction after incubation with tritiated leucine. The neuronal fraction incorporated also a number of other amino acids to a higher extent than the glial fraction (neuron/glia ratio 2·5-6). A definite dependence of incorporation on the rate of oxygenation was demonstrated. The suppression of amino acid incorporation was more marked for the neuronal fraction than for the glial fraction during incubation in relative hypoxia. An increase of potassium concentration in the incubation medium enhanced the amino acid incorporation in both fractions. Low sodium levels decreased the incorporation. Puromycin inhibited incorporation to approximately 30 per cent of control for both fractions. Addition of cycloheximide and dinitrophenol resulted in greater inhibition of incorporation in the neuronal fraction than in the neuroglial fraction. Actinomycin D did not markedly affect the incorporation in any fraction. These results are discussed in relation to in vivo and in in vitro differences for transport and incorporation of amino acids.

Increased renin activity after cold storage of human plasma.

Abstract: The velocity of angiotensin generation during incubation for 3 h at 37 °C increased up to 600% if plasma (EDTA) from normal men was first preincubated for 3 days at 4 °C. Longer preincubation (9–31 days) generally resulted in additional potentiation that continued to be expressed during incubation periods of 3–48 h at 37 °C. The effect is not abolished in the presence of up to 200 μg/ml of neomycin sulfate. Recovery of synthetic angiotensin I added to both cold-stored and control plasma is about 90% after 3 h of contact at 4 °C. The cause of potentiation has not been established, but possibilities under investigation include renin activation and preferential degradation of a renin inhibitor.

The testing of proven Trypanosoma brucei and T. rhodesiense strains by the blood incubation infectivity test.

Abstract: The authors describe a simple test (the blood incubation infectivity test) by which Trypanosoma brucei (sensu stricto) may be differentiated from T. rhodesiense without recourse to human volunteers. The method consists in incubating the strain of trypanosome under test for 5 hours at 37 degrees C in vitro in human blood, followed by observation of the effect of this procedure on the strain's infectivity to rats.Thirteen strains of T. rhodesiense were investigated; in each, the ability to infect rats was retained after incubation. In all 6 strains of man-tested T. brucei, it was destroyed.The consistency of the results with proven strains suggests very strongly that the blood incubation infectivity test provides a valid means of differentiating these parasites.