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At least 19 recordsLinked to original sources
PubMed1991

Paradoxical shortening of scrapie incubation times by expression of prion protein transgenes derived from long incubation period mice.

Prolonged incubation times for experimental scrapie in I/LnJ mice are dictated by a dominant gene linked to the prion protein gene (Prn-p). Transgenic mice were analyzed to discriminate between an effect of the I/LnJ Prn-pb allele and a distinct incubation time locus designated Prn-i. Paradoxically, 4 independent Prn-pb transgenic mouse lines had scrapie incubation times shorter than nontransgenic controls, instead of the anticipated prolonged incubation periods. Aberrant or overexpression of the Prn-pb transgenes may dictate abbreviated incubation times, masking genuine Prn-p/Prn-i congruence; alternatively, a discrete Prn-i gene lies adjacent to Prn-p.

Animals↗
PubMed1976

The effects of ouabain and ethacrynic acid on the intracellular sodium and potassium concentrations in renal medullary slices incubated in cold potassium-free ringer solution and re-incubated at 37 degrees C in the presence of external potassium.

1. The cells in slices cut from the renal outer medulla of normally hydrated adult rats were loaded with Na and depleted of K by incubation for up to 100 min in cold iso-osmolal K-free Ringer containing 180 mM-Na. There was a continuous net cellular water loss during this time; an inverse linear relationship existed between water content and intracellular Na concentration. 2. The original intracellular Na and K concentration were restored following 60 min re-incubation in warm Ringer (37 degrees C) containing 5-9 mM-K. Restoration of cellular water content was incomplete after re-incubation for up to 120 min. 3. During incubation in cold K-free Ringer the presence of 1 mM ouabain did not affect cellular Na uptake or K and water loss. Ethacrynic acid, 1 mM, completely blocked cellular Na uptake and water loss, without affecting the intracellular K concentration at 100 min. When ouabain and ethacrynic acid were present together water loss was also prevented but intracellular Na concentration rose slightly by 100 min. 4. During re-incubation in warm K-containing Ringer 1 mM ouabain inhibited Na extrusion completely for up to 60 min while only partially preventing K uptake and further depressing the level of cellular hydration. Ouabain in the presence of 1 mM ethacrynic acid had similar effects on intracellular Na and K concentrations, but raised the level of intracellular water above that of cells in control slices. 5. Ethacrynic acid alone, 1 mM, did not interfere with Na extrusion or K uptake, but also raised intracellular water above control values. 6. The results obtained are discussed in relation to (a) the nature of the preparation used, (b) the possible membrane transport processes occurring and their known or suggested sensitivity to ouabain and ethacrynic acid, (c) the mechanisms which may be responsible for cell volume maintenance in the medulla.

Animals↗
PubMed1992

Cardiovascular responses to thoracic skin cooling: comparison of incubating and non-incubating Bantam hens.

Body temperatures, metabolic rate, haemostatic parameters, and cardiovascular reactions to thoracic skin cooling were compared between incubating (broody) and non-broody Bantam hens. Under resting conditions, without thoracic skin cooling, cardiac output of broody hens was twice that of non-broody hens. However, their metabolic rate (VO2) was increased by only one-third over that of non-broody hens, and the arteriovenous difference in oxygen concentration was smaller for broody birds. This indicates a higher rate of non-nutrient blood flow during incubation. A higher thoracic skin temperature (Tths) for broody hens compared to non-broody hens suggests that brood patches are the probable site of this increased flow through arteriovenous anastomoses (AVAs). Thoracic skin cooling increased metabolic rate and Q significantly more in broody hens, but did not increase AVA blood flow. The relation between metabolic rate and total peripheral resistance indicated more intense vasodilation for broody hens at the relatively low metabolic rates during moderate cooling, and more intense vasoconstriction for the broody hens at the high metabolic rates during stronger cooling. This corresponds to Tths measurements indicating dilation of brood patch AVAs with moderate cooling and AVA constriction with severe cooling. During moderate cooling, vasoconstriction in the feet and wattles of broody hens (but not of non-broody hens) freed non-nutrient blood flow for redistribution to the brood patches. Thus, the cardiovascular system of the hen seems to adjust to the special demands of incubation by a permanent increase of AVA flow in the brood patch, and by an additional capacity for brood patch vasodilation induced by cold stimuli in the range from 35 to 25 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1976

Host-parasite relationships of Fasciola hepatica in the white mouse. VII. effects of anti-worm incubate sera on transferred worms and successful vaccination with a crude incubate antigen.

Mouse antisera against the 16-day-old worm incubate and sera from 25-day infections in mice debilitated migrating flukes in recipient animals as measured by worm recovery and host mortality. Mouse antisomatic and 100-day infection sera produced no such effects. Host mortality was significantly lower after challenge in mice given one ip immunizing injection of the worm incubate; however, worm recovery was not significantly reduced. Injections at 2, 7, 12, and 24 hr with the worm incubate elaborated over a 24-hr period protected 75% of the mice from infection after challenge, and reduced the worm burden by 83.3%.

Animals↗
PubMed1977

A comparison of the effects of prior cold incubation on cerebral cortex function in a hibernator (Cricetus auratus) and a non-hibernator (Cavia porcellus)--II. High energy phosphate levels in cerebral cortex slices after in vitro cold incubation.

1. ATP and CP levels were measured in brain slices from golden hamster and guinea pig after varying periods of cold storage and subsequent incubation at 37 degrees C in the presence and absence of K+ salts. 2. ATP and CP levels were maintained at higher levels in hamster tissue. 3. The results are discussed in relation to the ability of a hibernator to transform and transport chemical energy at low temperatures.

Adenosine Triphosphate↗
PubMed1990

Desensitization of beta-adrenoceptor-mediated functional responses of guinea pig atria by in vitro incubation with isoprenaline.

Positive inotropic and chronotropic responses to (-)-isoprenaline were recorded in guinea pig isolated paced left and spontaneously beating right atria. Concentration-response curves were determined before and after incubation with 10(-6) M (-)-isoprenaline for various times from 0.5 to 8 h. Before construction of the postincubation curve, isoprenaline was washed from the tissue for either 0.5 or 1 h. Preincubation curves were corrected from controls for time-dependent changes in sensitivity. After a 2-h incubation with 10(-6) M isoprenaline and a 0.5-h washout, there was a significant rightward shift of the right atrial rate curve [concentration ratio (CR) 10.6 +/- 2.1]. This was reversed by extending the washout to 1 h. After a 4-h incubation, however, a poorly reversible desensitization occurred, the curve still being significantly shifted after a 1-h washout (CR, 17.4 +/- 6.2). A higher incubation concentration, 10(-5) M, appeared to produce greater desensitization as a depression of the maximum response, however, this was an artifact caused by the failure to wash the isoprenaline from the tissue. When left atria were paced throughout the incubation period, a substantial nonspecific depression of the maximum response to 73.7 +/- 7.6% occurred. When pacing was stopped during incubation, only a rightward shift of the curve was produced by incubation with isoprenaline (10(-6) M), with no change of maximum (96.5 +/- 6.3%). There was no cross-desensitization of histamine in either the left (unpaced while incubating) or right atria after a 4-h incubation period with isoprenaline (10(-6) M). The desensitization was therefore beta-adrenoceptor specific and of the homologous type. After an 8-h incubation, there was an additional depression of the postincubation maximum which was greater in the left (68.9 +/- 2.3%) than right atria (85.2 +/- 5.4%). This true reduction of the maxima indicates that desensitization had effectively removed a proportion of the beta adrenoceptors.

Animals↗
PubMed1991

Prolonged incubation of skeletal muscle in vitro: prevention of increases in glucose transport.

During experiments involving prolonged incubation of skeletal muscle, we observed large increases in glucose transport activity. The basal rate of 3-O-methylglucose (3-MG) transport increased two- to fourfold in rat epitrochlearis muscles incubated for 9 h without insulin in Krebs-Henseleit buffer supplemented with 8 mM glucose. The stimulatory effect of a low concentration of insulin (30 microU/ml, added during the final 30 or 60 min of incubation) on glucose transport activity was enhanced 2.5-fold after 6 h and approximately 5-fold after 9 h of incubation. Exposure of muscles to 100 microU/ml of insulin for the first 8 h inhibited slightly but significantly the increase in insulin-stimulated 3-MG transport over a 9-h incubation period. Incubation of muscles in minimal essential medium (MEM) for 9 h inhibited the time-dependent rise in basal and insulin-stimulated transport by approximately 45%. The effect of MEM was reproduced with MEM essential, but not nonessential, amino acids. Incubation of muscles with MEM plus 100 microU/ml of insulin for the first 8 h prevented the increases in 3-MG transport activity measured after a 9-h incubation period. Muscles incubated for 9 h maintained ATP and phosphocreatine concentrations, and changes in glycogen concentrations were small. Thus we have defined conditions for long-term incubation of skeletal muscle under which a progressive increase in glucose transport is prevented.

Amino Acids↗
PubMed1992

Adaptation of rabbit cortical collecting duct to in vitro acid incubation.

Cortical collecting ducts (CCDs) isolated from acid-loaded rabbits and perfused in vitro absorb HCO3-, whereas CCDs from normal animals secrete HCO3-. We have previously shown that CCDs incubated in vitro for 3 h at pH 6.9 show a reduction in net (baseline and stimulated) HCO3- secretion. In this study we ascertained the minimum duration of an acidic stimulus necessary to induce adaptive changes in stimulated HCO3- secretion (determined in the absence of basolateral Cl-) and the roles of protein synthesis and cytoskeletal function in this process. CCDs incubated in acid (pH 6.8, HCO3- 6 mM) for 1 h followed by incubation at pH 7.4 (HCO3- 25 mM) for 2 h showed a 41% reduction in stimulated HCO3- secretion (P < 0.001), similar to that observed after 3 h of incubation at pH 6.8. However, this incubation protocol failed to enhance stimulated HCO3- absorption (determined in the absence of luminal Cl-). Addition of 10 microM anisomycin, a reversible inhibitor of protein synthesis, throughout the entire period of incubation (1 h at pH 6.8 plus 2 h at pH 7.4) blocked adaptive reduction in HCO3- secretion, as did exposure to anisomycin only during the initial 1 h of acid incubation. In contrast, anisomycin application during the 2-h incubation at pH 7.4 failed to block this adaptation of HCO3- secretion. Application of 4 microM actinomycin D, an inhibitor of DNA transcription, during the acid incubation also prevented the adaptive response, as did application during the total or during the 2-h pH 7.4 incubation period of 0.2 microM cytochalasin D, an inhibitor of actin filament function.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1992

Time-related morphological changes of porcine ovarian granulosa cells incubated with urea-EDTA solution.

Morphological profiles of porcine granulosa cells incubated with 10 mM Tris-HCl containing 1 M urea and 5 mM EDTA (urea-EDTA solution) were investigated. The percentages of granulosa cells incorporating the dye, trypan blue on incubation with urea-EDTA solution did not change during the initial 30 min. Thereafter, granulosa cells gradually took up the dye throughout the incubation. The amount of protein released from granulosa cells increased dramatically during initial 15 min of incubation, but decreased during the following 15-30 min of incubation. Thereafter, the amount of proteins released from granulosa cells increased gradually again. The releasing profile of 51Cr-bounded substances in granulosa cells increased markedly during the initial 15 min of incubation, and decreased during the next 15 min of incubation. Subsequently the amount of 51Cr released was enhanced. The min of incubation. Subsequently the amount of 51Cr released was enhanced. The plasma membranes of granulosa cells remained intact at 30 min of incubation, although chromatin clusters of granulosa cells disappeared. Thereafter, a number of cells showed signs of degeneration, including broken plasma membrane and cytolysis. The present study revealed that urea-EDTA solution is useful in extracting materials from porcine granulosa cells. The majority of the materials extracted from granulosa cells during the initial 30 min of incubation with urea-EDTA solution is considered to be from the cell surfaces and/or intercellular matrix.

Animals↗
PubMed1979

[Studies on noise stress caused by infant incubators (author's transl)].

The following acoustic effects of incubators were investigated: Noise level and vibration measurements inside incubators. Noise emanation into the vicinity of incubators. Deadening of incubator noise by the hood. The noise intensity inside the incubators was also registered under conditions of intensive care using sound emitting therapeutic and monitoring equipment. The results show that the noise level of incubator motors can be tolerated. This applies to well-serviced incubators only, however. The hood muffles outside noise, particularly in the range of greatest hearing acuity. But there is no protection against noisy intensive-care systems within the incubator. The infants own noise production is considered to contribute substantially to the noise within an incubator.

Humans↗
PubMed1991

Increased in-vitro incubation time of endothelial cells on fibronectin-treated ePTFE increases cell retention in blood flow.

Endothelial cell (EC) seeding is postulated as a mechanism of improving patency of small calibre vascular grafts. However, the majority of seeded cells are lost within hours following restoration of blood flow. We postulated that incubating EC in-vitro on a graft will improve adherence and resistance to the sheer stresses of pulsatile blood flow. Fibronectin-treated ePTFE (5 cm x 4 mm ID) seeded with Indium-111-labelled autologous canine EC (1.5 x 10(5) cells/cm2) were incubated for four different time periods; 90 min, 24 h, 72 h and 6 days. Incubated grafts were subjected to blood flow of 75 ml/min for 6 h, in a canine ex-vivo arteriovenous shunt circuit. EC retention during perfusion was studied by measuring gamma activity emitted by the grafts. Cell morphology of non-perfused control groups and perfused groups was compared using scanning electron microscopy (SEM). SEM of control grafts showed progressive EC spreading on the ePTFE surface for up to 72 h incubation. Gamma activity was significantly higher at 6 h perfusion in grafts incubated for 72 h (82 +/- 4%) and 24 h (63 +/- 6%) vs. 90 min (34 +/- 13%, p less than 0.05), and between grafts incubated for 72 h vs. 6 days (55 +/- 7%, p less than 0.05). Perfused grafts incubated for 72 h showed unaltered EC morphology on SEM, few cells remained on 90 min incubated grafts. We conclude that incubating EC on fibronectin-treated ePTFE for 72 h in-vitro after seeding improves cell retention during blood flow.

Animals↗
PubMed1991

Ovarian steroid production in vitro during gonadal regression in the turkey. I. Changes associated with incubation behavior.

The mechanism regulating ovarian regression during incubation behavior in the domestic turkey has not been elucidated. This study was designed to determine whether ovarian steroidogenic potential is depressed during gonadal regression associated with the onset of incubation behavior. Hens were housed in floor pens equipped with trap nests that were checked 7 times per day. Hens were grouped, according to nesting frequency and egg production, into the following classifications: laying (laid an egg every day and trapped in the nest only once/day); transitional (laid an egg every day but trapped in the nest 4 or more times/day); and Day 1, Day 3, and Day 5 incubating (no egg for 2, 4, or 6 days, respectively, while trapped in the nest at least 4 times/day). Follicular atresia was evident in the largest preovulatory follicle (F1) in transitional hens, extensive in F1 through the third largest follicle (F3) in Day 1 incubating hens, and extensive in F1 through F7in Day 3 incubating hens. Levels of circulating LH, progesterone (P), androgen (A), and estradiol (E) decreased in transitional hens relative to concentrations in laying hens and remained low thereafter. In contrast, levels of prolactin were greater in Day 3 and Day 5 incubating hens than in laying, transitional, or Day 1 incubating hens. Basal production of P by F1 granulosa cells was lower from Day 1 incubating hens than from the other groups. Production of P in response to porcine-luteinizing hormone (pLH) was greater by cells from transitional and Day 1 incubating hens than from those of laying hens.(ABSTRACT TRUNCATED AT 250 WORDS)

Androgens↗
PubMed1979

Increases in mitochondrial steroidogenesis after short term incubation of porcine ovarian follicles with luteinizing hormone.

[4-14C]Cholesterol side chain cleavage, progesterone synthesis, and cytochrome oxidase activities were measured in mitochondria from unincubated and short term incubated large (8-10 mm) follicles isolated from porcine ovaries. Compared to the activity of mitochondria from unincubated follicles, specific [4-14C]cholesterol side chain cleavage activity in mitochondria from follicles incubated with LH (0.05 microgrogram/ml) did not change significantly after 12 h, but increased almost 2-fold after 18 h and 5-fold after 24 h. Also, specific mitochondrial progesterone synthesis activity increased dramatically after incubation of follicles for 24 h with LH. In comparison, mitochondria prepared from follicles incubated without LH showed no significant change in specific [4-14C]cholesterol side chain cleavage or progesterone synthesis activities after 18 h of incubation. While both of these activities increased after incubating follicles 24 h without LH, the values were significantly lower than those observed for preparations from follicles incubated with LH. In contrast to these changes in mitochondrial steroidogenesis, specific cytochrome oxidase activity in mitochondria did not change after incubation of follicles without or with LH. It is concluded that incubation of follicles with LH stimulates the development of mitochondrial steroidogenesis but initially does not affect some components of the respiratory chain.

Animals↗
PubMedDate not supplied

Influence of incubation time/temperature on acrosome reaction/sperm penetration assay.

The acrosomal status of human spermatozoa was studied in relation to the score of the sperm penetration assay (SPA) at low-temperature (4 degrees C) incubation for induction and synchronization of the acrosome reaction (AR) and the incubation time of spermatozoa in conventional SPA. Spermatozoa were collected from 18 patients, selected by the "swim-up" method and treated in three different ways: (1) short-term incubation group (SIG): 3 h incubation at 37 degrees C, and (2) long-term incubation group (LIG): 20 h incubation at 37 degrees C, and (3) low temperature group (LTG): 24 h incubation at 4 degrees C followed by additional incubation at 37 degrees C for 3 h. The conventional methods of incubation, i.e. SIG (3 h) and LIG (20 h) did not show any significant differences as evaluated by the sperm penetration rate and the number of decondensing sperm heads per oocyte. In contrast, in the LTG all parameters were significantly increased, especially those of penetration rate (p less than 0.0005) and decondensing sperm heads per oocyte (p less than 0.0005). The percentage of AR significantly increased (p less than 0.0005) in the LTG (14.7%) compared with SIG (6.1%) and LIG (10.6%). A significant correlation was demonstrated between AR and the parameters used for evaluation of the SPA. The penetration rate (Spearman test, r = 0.462, n = 54, p less than 0.003) was the most significant parameter correlated with AR. It would appear that only human spermatozoa having completed AR are capable of fusing with the zona-free hamster ova.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrosome↗
PubMed1992

Effect of prolonged incubation of male rat whole pituitary or pituitary-hypothalamus complex with testosterone on release of gonadotrophin and prolactin in vitro.

Investigations were undertaken to study the effect of in vitro addition of testosterone (0.3 mM) on the release of luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin (PRL) by pituitary-hypothalamus complex (PHC) or the whole pituitary (PI) incubated for 72 hr, with incubation media changed every 24 hr. PHC or PI were from adult intact or castrated (7 days post castration) rats. The tissues incubated with or without testosterone were further exposed to 0.1 nM luteinizing hormone-releasing hormone (LHRH) for 4 hr. Incubation media and the pituitary were analyzed for PRL and gonadotrophin content. While PHC from normal and castrated rats released increasing amounts of LH with diminishing amounts of FSH and PRL at different periods of incubation, PI showed a decrease in the amounts of gonadotrophin and PRL released. Co-incubation of PHC or PI of intact or castrated rats with testosterone stimulated the release of LH and FSH during the first or second-24 hr incubation but inhibited the release of PRL in all the three incubations of 24 hr each. The extent of PRL inhibition increased with increasing incubation period. Testosterone had no effect on LHRH induced release of PRL but inhibited LHRH induced release of LH and FSH by pituitaries from constructs of normal rats. Testosterone reduced intrapituitary contents of PRL and FSH of intact and castrated rats. The data are interpreted to suggest that hypothalamus is essential for the maintenance of functional pituitary in vitro and that intrinsic differences exist in mechanisms regulating the secretion of LH, FSH and PRL.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

ELISA incubation times can be reduced by 2.45-GHz microwaves.

The ELISA (Enzyme Linked Immuno Sorbent Assay) technique is widely applied in the field of immunology. The use of this technique implies several incubation periods, often requiring more than one hour each. Microwave irradiation is known to be very useful in accelerating different kinds of processes. This knowledge has led to the present study in which it is proved that 2.45-GHz microwaves are able to reduce ELISA incubation times. This time reduction of 50% or more concerns each of the four incubation steps of the specific indirect ELISA which is used to determine the amount of antibodies in NF90-hybridoma cell culture supernatants. These incubation steps involve the coating of the microtiter plate, the incubation with BSA against non-specific binding, and the incubations with the first and second antibody. Combinations of more microwave-influenced steps in one ELISA save a considerable amount of time. When in addition air is blown through the incubation fluid during microwaving, the extinction values are almost the same as those of conventionally performed ELISAs. Thus, a good match of power setting and irradiation time results in a total incubation time reduction from 5.5 hours to 2 hours in this particular ELISA. Carefully monitoring the temperature of the incubation fluids during irradiation with the use of a fiberoptic thermometer appeared to be of crucial importance in the development of an optimal procedure.

Enzyme-Linked Immunosorbent Assay↗