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At least 199 records · Page 11Linked to original sources
PubMed1994

In vitro incubation of bovine ovarian follicles: indications for an active and regulated renin-angiotensin system.

1. The ovarian follicular renin-angiotensin system was investigated by using an in vitro incubation method, based on tissue incubation of individual bovine follicles. 2. Very high and varying concentrations of active renin (median 18.0 GU/kg, range 2.1-107 GU/kg; n = 101) and prorenin (11.7 GU/kg, range < 2.6-142 GU/kg; n = 101) existed in unincubated ovarian follicular tissue. 3. Active renin and prorenin increased 35 and 959%, respectively, in follicular wall tissue and incubation medium during 72 h of in vitro incubation. The protein synthesis inhibitor cyclohexamide inhibited active renin and prorenin formation. No activation of prorenin occurred in incubation medium or follicular fluid in vitro. Active renin was degraded during incubation. 4. Primarily prorenin but also active renin were secreted into the incubation medium. Secretion was directed both to the internal and external surface of the follicular wall. 5. Follicle-stimulating hormone (FSH) slightly stimulated the synthesis and secretion of prorenin in vitro. 6. The synthesis and secretion rates of active renin and prorenin varied markedly between individual follicles. 7. The finding of very high and varying concentrations of active renin in follicular wall tissues together with the formation and secretion of active renin during in vitro incubation provide further evidence for an active and regulated renin-angiotensin system in ovarian follicles.

Animals↗
PubMed1981

Peptidase regulation of gonadotropin-releasing hormone levels during in vitro incubations of the rat hypothalamus.

The fate of gonadotropin-releasing hormone (GnRH) was examined by a GnRH radioimmunoassay during in vitro incubations of the rat medial basal hypothalamus (MBH). There was a progressive disappearance of exogenous GnRH during MBH incubations. The GnRH degradation could be explained by the release of peptidases from the MBH into the incubation medium. The cytoplasmic marker lactic dehydrogenase (LDH) was also released into the incubation medium. The peptide antibiotic bacitracin produced a dose-dependent inhibition of GnRH degradation during MBH incubations; 1 mM-bacitracin completely inhibited exogenous GnRH degradation during 4-h incubations. Bacitracin also produced dose-dependent increases in the recovery of endogenous GnRH released from the MBH under basal conditions or when stimulated with the depolarizing agent veratrine. Veratrine also was found to decrease the GnRH peptidase activity significantly but not the LDH activity during MBH incubations. The present results indicate that peptidase activity can be an important regulator of endogenous GnRH released from the hypothalamus during in vitro incubations.

Animals↗
PubMed2006

Oral treatment and in vitro incubation with fructose modify vascular prostanoid production in the rat.

1.-- In the rat, a fructose-enriched diet induces hyperglycaemia, hypertriglyceridaemia, insulin resistance and hypertension; a model which resembles the human metabolic syndrome. 2.-- Prostanoids, metabolites of arachidonic acid, include vasoactive substances synthesized and released from the vascular wall that have been implicated in the increase of peripheral resistance, one of the mechanisms involved in the fructose-induced hypertension. 3.-- The aim of the present study was to: (i) analyse the effects of the in vitro incubation with fructose on the production and release of prostanoids in rat thoracic aorta and in rat mesenteric bed and (ii) compare the effects of incubation with those of the in vivo acute and chronic treatment of rats with fructose and with the combination of both in vivo and in vitro procedures. 4.-- Blood pressure, glycaemia and triglyceridaemia were significantly elevated in both 4- and 22-week fructose-treated groups. Meanwhile, body and heart weight as well as insulinaemia were similar between experimental animals and controls. 5.-- In aortae, 4 weeks of Fructose treatment did not modify the prostanoid pattern release, but in vitro incubation decreased prostacyclin (PGI(2)) production. However, after 22 weeks, fructose treatment and incubation exerted the same effect. 6.-- In mesenteric bed, after 4 weeks, the incubation and the combination of both procedures reduced the release of the vasodilators PGI(2) and PGE(2), while fructose treatment only diminished the PGE(2) release. On the contrary, the production of the vasoconstrictor thromboxane A(2) (TXA(2)) was enhanced by incubation and both the procedures. After 22 weeks, fructose treatment increased PGI(2) release, while it was reduced by incubation. The combination of both did not modify this peripheral resistance when compared with controls. Finally, incubation of tissues from treated rats increased the release of the vasoconstrictors, PGF(2alpha) and TXA(2). 7.-- In conclusion, the mesenteric bed, a resistance vascular bed, seems to be more sensitive than the aorta, a conductance vessel, to the effects of fructose on prostanoid production. This difference could be related to a more relevant role of resistance vessels in the regulation of peripheral resistance and consequently of blood pressure. The observed effects should contribute to a shift in the balance of the release of prostanoid in favour of vasoconstrictor metabolites. This phenomenon could be related to an increase in the peripheral resistance and the mild hypertension observed in the fructose-treated rats.

6-Ketoprostaglandin F1 alpha↗
PubMedDate not supplied

Changes in orthophosphate, pyrophosphate and long-chain polyphosphate levels in Leishmania major promastigotes incubated with and without glucose.

The intracellular levels of orthophosphate (Pi), pyrophosphate (PPi) and short- and long-chain polyphosphate (Poly P) were measured in Leishmania major promastigotes incubated in a phosphate-free medium. In the absence of exogenous substrate, the levels of both Pi and PPi increased during a 1 h incubation. The increase in both Pi and PPi was prevented when glucose was present, but glycerol prevented the rise in Pi only. A rise in Pi and PPi was also seen in cells incubated in the absence of exogenous substrate under anaerobic conditions. This was reversed upon addition of glucose plus oxygen. Polyphosphate, here shown to be present in L. major, was measured by means of a polyphosphate glucokinase assay. Short-chain Poly P content did not differ between cells incubated for 1 h in the absence of exogenous substrate or in the presence of glucose or glycerol. Long-chain Poly P content, however, was lower in cells incubated without glucose than in cells incubated with glucose and was also lower in cells incubated for 1 h with glycerol as compared with freshly washed cells. Up to 61% of the increase in Pi and PPi that occurred in promastigotes incubated in the absence of exogenous substrate could have arisen from the concomitant decrease in long-chain Poly P.

Animals↗
PubMed1989

In vitro drug testing in patients with acute leukemia with incubations mimicking in vivo intracellular drug concentrations.

The differential staining cytotoxicity (DiSC) assay was evaluated as a predictive test for response to therapy in patients with acute non-lymphoblastic leukemia. Incubations were designed in such a way that the intracellular concentrations of cytostatic drugs in vitro paralleled those in vivo. Leukemic cells were isolated from 53 patients with acute non-lymphocytic leukemia. 13 of these patients died early due to supportive care failure and were not evaluable for the predictive drug testing. Of the remaining 40 patients, 25 entered a complete remission (CR) and 15 had a resistant disease (RD). According to the patients randomization to therapy the cells were incubated with anthracyclines and Ara-C separately and in combination. After 4 days of culturing in liquid medium the in vitro cytotoxicity was determined by dye exclusion according to Weisenthal. The cytotoxic effect in vitro was significantly higher on cells from patients who achieved a CR compared to patients with RD after incubations with anthracyclines 0.2 mumol/l (p less than or equal to 0.005), Ara-C 0.5 mumol/l (p less than or equal to 0.05) and with the combination of anthracyclines with Ara-C (p less than or equal to 0.0005). The best predictive value was achieved when incubations with 0.2 mumol/l anthracyclines and 0.5 mumol/l Ara-C were analyzed together. With these incubations cells from 20 out of 21 patients who achieved CR showed either less than or equal to 60% surviving cells after the anthracycline incubation or less than or equal to 35% surviving cells after the Ara-C incubation. Cells from 11 out of 13 patients with RD did not fulfill either of these criteria. In vitro drug sensitivity was significantly correlated to a prolonged survival (p less than 0.01). We conclude that, when performed with incubations that mimic in vivo tumor cell exposure to cytostatic drugs, the DiSC assay shows a high correlation to clinical outcome for patients with acute non-lymphocytic leukemia.

Adolescent↗
PubMed1982

Effect of mouse peritoneal macrophages on scrapie infectivity during extended in vitro incubation.

Mouse peritoneal macrophages were exposed to scrapie (ME7 strain) brain homogenate in vitro for 2 h at 37 degrees. The samples were assayed for infectivity by analysis of scrapie incubation periods and their values compared to those obtained after extended (1-28 days) in vitro incubation. The scrapie incubation periods for scrapie agent-macrophage mixtures which had undergone extended in vitro incubation were longer than for mixtures assayed after a 2-hour exposure to the scrapie agent. The difference in scrapie incubation periods was more dramatic when residual scrapie was eliminated by washing the cells after the 2-hour exposure to brain homogenate. The scrapie incubation period also increased following in vitro incubation of ME7 in the absence of cells; however, the changes were less than those observed for scrapie agent-macrophage mixtures. In a culture in which cells had been destroyed by UV irradiation after exposure to the scrapie agent, there was more scrapie infectivity than in a comparable culture of untreated, scrapie-exposed macrophages. These results show that scrapie infectivity decreases with extended incubation of scrapie-exposed macrophages, and the data suggest that macrophages can inactivate the scrapie agent in vitro.

Animals↗
PubMedDate not supplied

Prostaglandin release from isolated rabbit cerebral cortex micro-vessels--comparison of 6-keto PGF1 alpha and PGE2 release from micro-vessels incubated in 100% O2, room air and 95% N2:5% CO2.

Prostaglandin release from microvessels isolated from the rabbit cerebral cortex was determined under three different atmospheric conditions: 100% O2 ("O2") room air, and 95% N2:5% CO2 ("N2-CO2"). Initial studies with homogenates prepared from rabbit cerebral microvessels (RCMV) indicated two pathways of enzymatic PGH2 transformation, namely PGI2 synthase and GSH-dependent PGH-PGE isomerase. We measured the release of the principal products of these pathways, 6-keto PGF1 alpha and PGE2 from freshly prepared RCMV. The release of 6-keto PGF1 alpha exceeded that of PGE2 in all three protocols. RCMV incubated in "N2-CO2" exhibited a reduction in the release of 6-keto PGF1 alpha compared to room air or "O2" incubated RCMV, evident at 30-60 min of incubation. No significant differences in the release of PGE2 were observed among the three incubation protocols. In all three incubation protocols the ratio of 6-keto PGF1 alpha to PGE2 did not differ during the initial 10 minutes of each incubation. After 30 to 60 min of incubation, this ratio did not change from the "O2" or room air treated RCMV, but decreased significantly for the "N2-CO2" treated group. To determine the reversibility of the apparent "N2-CO2" induced decline in 6-keto PGF1 alpha release, microvessels were removed from the nitrogen atmosphere and incubated in room air. Release was measured during the initial 10 min following reintroduction to room air and was compared to room air pretreated controls treated in an identical manner.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed2004

Acclimation to hypothermic incubation in developing chicken embryos (Gallus domesticus): II. Hematology and blood O2 transport.

Hypothermic incubation reduces the ability of the late-stage chicken embryo to mount endothermic heat production. This study investigates whether blood O(2) transport is similarly limited by cooler incubation temperatures. Two populations of chicken embryos were incubated at 38 degrees C and 35 degrees C. At Hamilton-Hamburger (HH) developmental stage 41-42, hypothermic incubation had no significant effect on hematocrit ( approximately 26%) or [Hb] (7 g%). However, in the final stages of incubation (stage 43-44), hypothermic incubation reduced hematocrit from approximately 31% at 38 degrees C to approximately 27.5% at 35 degrees C. Hypothermic incubation similarly caused a reduced [Hb] from 8.5 g% (38 degrees C) to 6.25 g% (35 degrees C), indicating a reduction in blood O(2)-carrying capacity in embryos. Incubation temperature had a strong effect on blood-O(2) affinity in late development (stage 43-44), with P(50) at 38 degrees C falling significantly from approximately 6 kPa in 38 degrees C embryos to approximately 4 kPa in 35 degrees C embryos. P(O(2)) values in chorioallantoic arterial blood at HH 41-42 were 4.3 kPa at pH 7.46 (38 degrees C) and 3.4 kPa at pH 7.39 (35 degrees C). In chorioallantoic venous blood these values were 9.1 kPa at pH 7.34 (38 degrees C) and 8.1 kPa at pH 7.42 (35 degrees C). With further development to HH 43-44, chorioallantoic arterial blood oxygenation fell to 2.4 kPa at pH 7.54 (38 degrees C) and 2.8 kPa at pH 7.52 (35 degrees C). Similarly, P(O(2)) in chorioallantoic venous blood fell slightly to 7.7 kPa at pH 7.42 (38 degrees C) and 7.4 kPa at pH 7.48 (35 degrees C). Collectively, these data reveal that beyond HH 41-42, 35 degrees C embryos experience retarded hematological development, and the findings that support the observed delayed metabolic response to acute temperature changes.

2,3-Diphosphoglycerate↗
PubMed1995

Thermosensitization of murine FM3A cells by transient incubation at low culture temperatures.

We show that when murine FM3A cells maintained at 37 degrees C were incubated at low culture temperatures between 24 degrees and 33 degrees C for 12-24 h, they became thermosensitive as compared to those incubated at 37 degrees C. The synthesis and accumulation of inducible HSP70 and constitutive HSC70 by heat shock decreased in cells incubated at 33 degrees C, whereas no such decreases were found in cells incubated at 37 degrees C. The accumulation of HSP105 because of heat shock also decreased in cells incubated at 33 degrees C. The decreased inducibility of HSP70, HSC70, and HSP105 by heat shock may in part be responsible for the increase seen in the thermosensitivity of the cells. Furthermore, the cellular concentration of HSP105 decreased in cells incubated at 33 degrees C but not in those incubated at 37 degrees C, whereas the concentration of HSC70 did not change at all in cells incubated at either temperature. The cellular content of HSP105, but not of HSC70, therefore may be a good indicator of the thermoresistant state of cells.

Animals↗
PubMed1975

Studies on isolated rat adrenal cells. I. Continuous flow and batch incubation.

A procedure for the continuous flow incubation of isolated adrenal cells is described. In this way the advantages of continuous flow incubations of adrenal tissue are combined with those of isolated adrenal cells. Suspensions of isolated adrenal cells were prepared by a modification of the collagenase method. A sigmoid dose-response curve was obtained when these cells were incubated with ACTH in batch incubations. Under these conditions (in the presence of 1 mU ACTH/ml) the corticosterone production rate remained constant during at least 240 min. This production rate was linearly related to the number of cells. Pre-incubation of the cells during 3 h resulted in an increased response to ACTH. In continuous flow incubations without ACTH the corticosterone production was negligible. With 100 mu U ACTH/ml corticosterone production increased sharply after a short lag period. A maximum was reached after 60-75 min followed by a slow decrease. Cells pre-incubated in the continuous flow apparatus had a slightly diminished ACTH response without loss of affinity to ACTH. The continuous flow incubation of isolated adrenal cells offers new possibilities for the dynamic study of steroid biosynthesis in vitro. The method may also be valuable to study processes in a wide variety of other tissues.

Adrenal Glands↗
PubMedDate not supplied

Incubation time effects on imazaquin desorption as determined by nonequilibrium thin-soil disc flow.

Because organic sorption in soil may never reach equilibrium, a thin-disc flow nonequilibrium method may be helpful in understanding herbicide-soil interactions. This research was conducted to (i) determine the influence of incubation time on imazaquin [2-(4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl)-3-quinolinecarboxylic acid] desorption from soil, (ii) examine the influence of solution flow velocities on desorption, and (iii) elucidate the most appropriate kinetic model to describe imazaquin leaching. Soil at 7.5% moisture w/w was treated with imazaquin and incubated for 24, 72, and 168 h. Treated soil was sealed in an in-line filter apparatus and rinsed with 5.0 mM CaCl2 at 0.33, 0.67, or 1.0 mL min(-1). Effluent was collected as 1.0-mL fractions for a total of 50 mL. Flow was stopped for 24 h. When flow resumed, fractions were collected for an additional 15 mL. After the initial desorption, 79% of the imazaquin incubated for 24 h was leached. Increasing incubation time beyond 24 h reduced imazaquin leaching. After both desorption events, 13% of the initially applied imazaquin remained in the soil incubated for 168 h, compared with 7% with soil incubated for 24 h. Elovich and Freundlich kinetics accounted for 98% of the variance observed in the imazaquin desorption curves. First-order and diffusion kinetics accounted for 91% of the variance. Incubating soil for 72 h before desorption reduced the rate of imazaquin desorption by approximately 12%, compared with the 24-h incubation treatment. Imazaquin desorption was not affected by wash solution flow rate. These data suggest that the kinetics of desorption in prolonged desorption events are limited by transport phenomena (i.e., particle and film diffusion).

Adsorption↗
PubMed1984

Morphological changes in chicken and turkey spermatozoa incubated under various conditions.

The viability and morphology of undiluted and diluted chicken and turkey spermatozoa were compared when incubated at either 41, 25, 15, or 5 C for 0 (control), 3, or 6 hr. Increasing the incubation time to 6 hr, raising the incubation temperature to 41 C, or both resulted in higher numbers of dead spermatozoa in semen from both species. Conversely, dilution (1:5 with Beltsville Poultry Semen Extender) of chicken or turkey semen resulted in a significant (P less than .05) decrease in the number of dead spermatozoa as compared to their respective undiluted counterparts, especially in samples incubated at 41 C. Turkey semen exhibited a somewhat lower percentage of dead spermatozoa, bent spermatozoa, and sperm tail coiling than did chicken semen incubated under similar conditions. No significant (P greater than .05) differences were observed in chicken and turkey semen samples when measuring other sperm cell abnormalities regardless of incubation conditions. These results indicate selective species differences in sperm morphological changes in response to incubation temperature, incubation time, and semen dilution.

Animals↗
PubMed2000

[Collagenase production increases in rheumatoid arthritis and osteoarthritis synoviocytes incubated].

Cartilage is a specialized connective tissue. It contains few cells into an extracell matrix. The matrix mainly constituents are collagen and proteoglycans. Its degradation depends on synoviocytes activity, that secrete metalloproteases, agents to proteoglycans catabolism. There are two types of synoviocytes: macrophagics (type "A:') and fibroblastics (type "B"). The proteoglycan destruction can be LT-dependent or LT-independent. The aim of this work is synoviocytes function ex vívo study, free immune system influence. In order to do it, heparinized synovial fluid samples were obtained from 6 osteoarthritic (OA) and 6 arthritic (RA) both sex untreated patients, diagnosed according ACR criteria, which disease duration was longer than 6 months. Patients average age was 70 +/- 2 years. Control samples were synovial fluid from traumatic arthritis or non inflammatory bone-muscle pathology. Synovial fluid was centifugated at 1500 g for 30 minutes to isolate synoviocytes. Sediment containing cells was 6 hs incubed with Dulbecco-Eagles media, that has HEPES Gibco (26 mM); NaHCO3 (0.5 g/I); glutamine (2 mM), streptomicine (100 mg/l), G-penicillin (1 U/ml); anphotericine B (2.5 mg/l). Cells calification and viability were cytopathologically determined. Before and after incubation, collagenase activity was measured by ELISA-double-sandwich, using 10 micrograms/ml monoclonal anti-MMPs in phosphate-buffer-saline. The antigen-antibody complex production with inespecific proteins was blocked by bovine seric albumine. Streptavidin peroxidase was added and washed with 2,2,azin,di(3-ethyl-benztazoilinsuiphonic) acid to develop color. The link of labeled antibody by absorbance at 410 nm was determined in ELISA-spectrophothometer. RA patients earlier MMPs synoviocytes production was 1373 +/- 115 ng/ml. Then 6 hs incubation 2143 +/- 132 ng/ml was reached. The increase (56%) had high significance (p < 0.0001). OA earlier MMPs cells production was 276 +/- 23 ng/ml, but after incubation it reached 542 +/- 47 ng/ml. (96% increased with highly significativa difference too: p < 0.0001). Microscopic study was carried out before and after incubation, and shows a lot of synoviocytes with plenty of cytopiasme when the collagenase leveis were highest. On the contrary, when low MMPs production by synovial fluid, as no incubated osteoarthritic material, a few cells containing picnotics nucleous were observed. Significant quantitative differences in AR and OA enzymatic secretion were observed. Although in rheumatoid arthritic MMPs leveis synoviocytes production were 4.6 times than OA levels, after 6 hs incubation percentage of increase in OA cells secretion was highest. Described results confirm MMP-1 synthesis by synoviocytes, and these levels correlate with inflammation, more pronounced in acute (RA) than chronic pathology (OA). Synoviocyte incubation let us to test disease changes in synovial fluid according to cells number and phagocytic activity. Authors agree to assert that synovial fluid may reflect what is happening in an articular cartilago, because SF provides markers of joint disease. MMPs are giving information about pathways involved in OA and RA cartilage degradation.

Arthritis, Rheumatoid↗
PubMedDate not supplied

[Phenotypic variability in P. vivax with short- and long-term incubation period].

The combined transmission of P. vivax phenotypes was studied. The phenotypes were determined by the duration of a latent parasitic development stage by comparing the intervals from first manifestations of malaria with short- and long-term incubations to its relapse. The study used data on 2493 patients treated with chloroquine (900 mg base for adults) alone at follow-ups in the North-Eastern Delhi (India) in 1988-1992. The combined transmission of P. vivax phenotypes was shown to differ in malaria with short- and long-term incubation. The P. vivax phenotype with manifestations on an average a year following infection in patients with mainly short-term incubation malaria and that with manifestations on an average year and a half after infection in a group of patients with primary long-term incubation malaria were significantly more frequently. Long-term incubation malaria shows simultaneously a larger number of phenotypes than does short-term incubation one. Patients with long-term incubation malaria display a combination of 2 phenotypes (6%) significantly less frequently than that of 3 different phenotypes or more (17%). The similar combinations were observed in the equal number of patients with short-term incubation malaria (7%).

Animals↗
PubMed2002

[In vitro activity of clarithromycin and metronidazole against Helicobacter pylori in different incubation atmospheres].

The aim of this study was to determine the in vitro activity of clarithromycin and metronidazole using an agar dilution method to compare two different incubation atmospheres: a CO2 incubator and a jar with a microaerobic gas-generating system. Antibiotics were placed on plates in twofold dilutions ranging from 128 to 0.064 mg/l in Mueller-Hinton agar supplemented with 7% horse blood. The inoculum was prepared from 31 Helicobacter pylori isolates and was inoculated using a Steers replicator. Plates were incubated for 3 to 5 days and MICs were recorded as the lowest concentration of antibiotic inhibiting visible growth. Two different incubation atmospheres were used: a CO2 incubator set at 95% humidity and 10% CO2, and a jar with a gas-generating envelope that produces 7-10% O2 and 14% CO2 (BioMerieux). Clarithromycin resistance was found in 19% of strains both in the gas-generating system and the CO2 incubator. Metronidazole resistance was 23% in both atmospheres. MICs for clarithromycin in both atmospheres showed two dilutions of difference for 100% of the strains, and were slightly higher in the jar with a gas-generating envelope. However, MICs for metronidazole were higher when it was incubated in the CO2 incubator, and in 86.7% of strains the MICs showed < or = 2 dilutions of difference. No great discrepancies were found for either metronidazole or clarithromycin using the two methods.

Anti-Bacterial Agents↗
PubMed1991

Incubation and the persistence of fixation in problem solving.

Extra work on unsolved problems may lead to more improvement if the new work is delayed rather than undertaken immediately after initial solution attempts. Such a result constitutes incubation in problem solving. "Unconscious work" on a problem, commonly assumed to be responsible for incubation effects, may not be necessary to observe the phenomenon. We hypothesize that fixation, a block to successful problem solving, may develop during initial solution attempts and persist, interfering with immediate extra work more than with delayed extra work. Five experiments are reported in which fixation was induced to prevent optimal performance on the initial test of Remote Associates Test (RAT) problems (e.g., Mednick, 1962). After the fixation manipulation in three of the experiments, the effects of incubation intervals were examined by retesting the fixated problems. Both fixation (poorer initial problem-solving performance) and incubation (more improvement after a delayed retest than an immediate retest) were found in all the experiments which tested for the effects. In Experiments 1, 2, and 3, misleading distractors were presented alongside the RAT problems during the initial test of the problems to cause fixation. In Experiment 4, a block of paired associates--pairing the RAT words with the misleading distractors prior to problem solving--successfully induced fixation, indicating that the distractors affected memory retrieval. In Experiment 5, a trial-by-trial technique allowed fixation and incubation to be induced and tested separately for each item. All of our findings of incubation effects appear to have depended upon the initial induction of fixation. Although the experiments may not be representative of all naturally occurring cases of incubation, they provide a methodology for the study of fixation and incubation effects in problem solving in the laboratory.

Adult↗
PubMed1990

The incubation of human blood monocytes with tumor necrosis factor-alpha leads to lysis of tumor necrosis factor-sensitive but not resistant tumor cells.

The purpose of this study was to determine whether the incubation of human blood monocytes with tumor necrosis factor (TNF) induces tumoricidal activity. Peripheral blood monocytes isolated by centrifugal elutriation from buffy coats of healthy donors were incubated with lipopolysaccharide (LPS), lipopeptide derived from Escherichia coli (CGP-31362), recombinant human interferon-gamma (rIFN-gamma) plus muramyl dipeptide (MDP) or recombinant human TNF for 24 hr. The human melanoma A375-M (highly sensitive to TNF), A375-P (moderately sensitive to TNF), and A375-R (resistant to TNF) cells were all lysed in vitro by monocytes activated with LPS, CGP-31362, or MDP plus rIFN-gamma. On the other hand, A375-M, but not A375-P or A375-R cells, were lysed by human monocytes incubated with rTNF. After incubation with rTNF, paraformaldehyde-fixed monocytes lysed A375-M cells. Monocytes incubated with LPS, CGP-31362, and MDP plus rIFN-gamma secreted a high level of IL-1 activity into the culture medium, but monocytes incubated with rTNF did not. The cytolytic activities of monocytes incubated with LPS, CGP-31362, and MDP plus rIFN-gamma were not affected by the presence of anti-TNF antiserum, whereas the lysis of A375-M cells by monocytes incubated with rTNF was completely abolished by the presence of anti-TNF antiserum. We conclude that exogenous TNF does not render blood monocytes tumoricidal, but rather that TNF bound to cell-surface receptors can produce lysis of TNF-sensitive cells by a "carryover" mechanism.

Adjuvants, Immunologic↗
PubMed1987

Effect of two gas mixtures on growth of the domestic fowl embryo from days 14 through 17 of incubation.

Eggs weighing 62.5 +/- 0.5 gm when fresh were incubated in air in a forced-draft incubator for 13 days during which time their shell conductance to water vapor (GH2O) was determined. Eggs whose shells represented the entire range of GH2O values present in the population were then incubated for a further 4 days in either air or an experimental gas mixture. Embryo dry weights were determined after a total of 408 hr of incubation to assess the affect of the experimental gas mixture on embryonic development. Embryo growth was found to be stimulated for all eggshell conductances by 4 days incubation in a 50% oxygen/50% nitrogen mixture. This suggests that the decrease in oxygen within the egg that occurs during development normally limits embryonic growth. Growth of the embryo was unaffected by 4 days incubation in a mixture of 17% oxygen/83% helium. This mixture reduced the carbon dioxide tension in the airspace but did not affect the oxygen tension relative to eggs incubated in air. It is suggested, therefore, that the carbon dioxide that builds up within eggs during incubation does not limit embryo growth.

Animals↗