Showing papers on "Incubation published in 1985"
TL;DR: The stoichiometric evaluation of fatty acid loss and the production of malonaldehyde and other carbonyls suggests that the pathways of lipid peroxidation triggered by CCl4 and ADP-iron are different.
Abstract: Carbonyl products were separated and identified in suspensions of rat liver microsomal fractions and in isolated hepatocytes, after stimulation of lipid peroxidation by incubation with the pro-oxidants CCl4 and ADP-iron. The carbonyl products were allowed to react with 2,4-dinitrophenylhydrazine, and the derivatives were extracted and separated by t.l.c. into three zones of non-polar materials, and one fraction of polar derivatives that remained at the origin. Separation of the individual non-polar hydrazones in each zone by h.p.l.c. demonstrated that zone I prepared from microsomal fraction or hepatocytes incubated with CCl4 or ADP-iron contained mainly 4-hydroxyhex-2-enal, 4-hydroxynon-2-enal and 4-hydroxynona-2,5-dienal. Zone III consisted mainly of the alkanals propanal, pentanal and hexanal, the 2-alkenals propenal, pent-2-enal, hex-2-enal, hept-2-enal, oct-2-enal and non-2-enal, the ketones butanone, pentan-2-one and pentan-3-one, and deca-2,4-dienal. Incubation of a microsomal fraction with ADP-iron was much more effective in producing malonaldehyde and other carbonyl products than an incubation with CCl4. Despite such quantitative differences, there were no obvious qualitative differences in the h.p.l.c. spectra obtained from zones I and III. However, the stoichiometric evaluation of fatty acid loss and the production of malonaldehyde and other carbonyls suggests that the pathways of lipid peroxidation triggered by CCl4 and ADP-iron are different. The accumulation of carbonyl products of lipid peroxidation in isolated hepatocytes is strongly affected by their metabolism; in particular, 4-hydroxyalkenals were found to be metabolized very rapidly. Nonetheless, both CCl4 and ADP-iron produced stimulation in the production of malonaldehyde and non-polar carbonyl production. After incubation of rat hepatocytes with CCl4 or ADP-iron it was found that approx. 50% of the total amount of non-polar carbonyls produced during incubation escaped into the external medium. This was not leakage from dead cells, as 90-95% of the hepatocytes had retained their integrity at the end of the incubation. Release of carbonyl products from cells stimulated to undergo lipid peroxidation may be a mechanism for spreading an initial intracellular disturbance to affect critical targets outside the parent cell.
362 citations
TL;DR: The energetic cost of incubation of a free-living Blue Tit (Parus caeruleus) female was studied during two breeding seasons by measuring the rate of oxygen consumption in a nest box converted into a metabolic chamber and the results show that the energy cost is relatively important below the lower critical temperature.
Abstract: -The energetic cost of incubation of a free-living Blue Tit (Parus caeruleus) female was studied during two breeding seasons by measuring the rate of oxygen consumption in a nest box converted into a metabolic chamber. Like its congeners, only the female Blue Tit incubates and during that time is fed by the male. Just before and during the egg-laying period the female spends the night in the nest. Because of the progressive development of incubation behavior during this period, it is possible to measure the oxygen-consumption rate of a nonincubating female (resting metabolism) and to compare it with values obtained later when the bird is incubating a full clutch under otherwise similar conditions. The air temperature in the metabolic chamber was regulated experimentally. The results show that the energy cost of incubation is relatively important below the lower critical temperature (about 15?C). With a fall in the air temperature, energy expenditure increased in relation to that of the resting metabolism. The energy cost of incubation also increased with clutch size, by about 6-7% for each additional egg. At air temperatures around 0?C, which are frequent under natural conditions in Fennoscandia, the female must increase her metabolic rate by 50-90% to keep the eggs in a normal-size clutch (10-13 eggs) warm. During the last days of incubation we accounted for the metabolism of the embryos, which on the day before hatching contributed about 15% of the total oxygen consumption when the female was incubating a clutch of 13 eggs. Received 30 May 1984, accepted 16 November 1984. THE evaluation of the energy cost of incubation by birds has been a subject of some controversy (e.g. Vleck 1981, Walsberg 1983). Based on heat-flow models, Walsberg and King (1978a, b) claimed that the resting metabolism of three passerine species, the Red-winged Blackbird (Agelaius phoeniceus), the Willow Flycatcher (Empidonax traillii), and the White-crowned Sparrow (Zonotrichia leucophrys), averaged about 15-18% less than that of nonincubating birds. Biebach (1979) and Vleck (1981) found from measurements of the rate of oxygen consumption in the Zebra Finch (Poephila guttata) and the European Starling (Sturnus vulgaris) that the metabolic rate of the female while incubating was 20-30% greater than that of nonincubating birds. Mertens (1980) estimated the energy requirement by measuring the heat loss from a Great Tit's (Parus major) nest and found that a considerable energy expenditure was involved in incubating. Using heat-flux disks mounted in the walls of a nest box occupied by a female Great Tit, Mertens concluded that the heat loss during incubation, at an air temperature of 8?C, was roughly 3 times greater than the heat loss incurred at the resting metabolic rate of a non-
181 citations
TL;DR: Since both parents benefitted from incubation feeding by increased hatching success and shorter incubation periods, it is concluded that this behaviour is an adaptive form of indirect parental care by males and is not the result of female manipulation.
Abstract: Summary. Male snow buntings regularly feed their mates on the nest during the incubation period. We removed males from 7 females at the start of incubation (Early Widows) and from 7 others when the eggs hatched (Late Widows) to experimentally assess the effects of incubation feeding on the behaviour of females and the reproductive success of both parents. Early Widows spent significantly more time off their nests than Late Widows and Controls. As a consequence, Early Widows had significantly longer incubation periods and a significantly higher proportion of them lost two or more eggs during development. There was no difference between Early and Late Widows in any index of reproductive success measured during the nestling period although significantly earlier brood reduction suggests that Early Widows were in poorer condition than Late Widows. Since both parents benefitted from incubation feeding by increased hatching success and shorter incubation periods, we conclude that this behaviour is an adaptive form of indirect parental care by males and is not the result of female manipulation.
127 citations
TL;DR: The modification by VE of reoxygenation‐induced lipid peroxidation suggests free radical mediation in rats and propagates peroxidative reactions within esterified polyunsaturated FAs.
Abstract: Using an in vitro system, we studied the effect of postischemic reoxygenation on cerebral lipid peroxidation in relation to the dietary intake of vitamin E (VE) in rats. Homogenates prepared from VE-deficient, -normal, and -supplemented brains, which were previously rendered ischemic for 30 min by decapitation, were incubated under air or nitrogen gas for 60 min. The extent of peroxidation in brain tissue was estimated by a thiobarbituric acid (TBA) test and by diene conjugation in total lipid extracts. The brain levels of alpha-tocopherol and of total and free fatty acids (FAs) were also determined. Aerobic incubation increased TBA reactants in all dietary groups; the effect was largest in the VE-deficient group, intermediate in the VE-normal group, and smallest in the VE-supplemented group. In contrast, nitrogen incubation did not alter the basal levels of TBA reactants except for a small rise associated with VE deficiency. Conjugated dienes changed in parallel with TBA reactants. alpha-Tocopherol decreased after aerobic incubation and also, to a lesser degree, after nitrogen incubation in each dietary group. Only in the reoxygenated samples of the VE-deficient group was there a significant fall in total polyunsaturated FAs. The levels of free FAs continuously increased throughout ischemia and subsequent incubation. However, the level of free polyunsaturated FAs was similar after aerobic and nitrogen incubation in each dietary group, and was not affected by VE. Thus, cerebral reoxygenation after ischemia propagates peroxidative reactions within esterified polyunsaturated FAs. The modification by VE of reoxygenation-induced lipid peroxidation suggests free radical mediation.
126 citations
TL;DR: Results indicate that fungi, mainly some of the mucoraceous fungi, may be the primary source of β-glucosidase in tomato-field soil.
Abstract: The distribution of β-glucosidase activity in a tomato-field soil was examined. Of the total activity found, > 50% was in the Selective inhibition of bacterial or fungal growth in re-moistened, over-dried, inoculated soil indicated that fungi were a more important source of β-glucosidase in this soil. Monierella, Actinomucor, Coniochaeta and Penicillium were the principal fungi isolated from the soil by the dilution-plate technique, comprising over 60% of the total isolates. Remoistened oven-dried soil, inoculated with Mortierella and Actinomucor spp exhibited higher β-glucosidase activity after incubation than did soil inoculated with other strains. The β-glucosidase activity of extracts from cultured fungal strains had similar pH optima and Q10 values to those of soil extracts. The β-glucosidase of extracts from isolates of bacteria and actinomycetes had similar Q10 values, but higher pH optima, than did that of soil extracts. These results indicate that fungi, mainly some of the mucoraceous fungi, may be the primary source of β-glucosidase in tomato-field soil.
121 citations
TL;DR: A comparison of these North American species with Eurasian acipenserids suggests that all the sturgeon that have been examined exhibit a similar influence of incubation temperature on developmental rate.
Abstract: The effect of constant incubation temperatures (between 10°C and 26°C) on the developmental rates was found to fit a similar exponential relationship in both the lake and white sturgeon embryos and larvae. Although the lake sturgeon had an overall slower rate of development than the white sturgeon, no statistically significant difference was detected in the slopes of the exponential equations describing the effect of temperature on developmental rate. The effect of these incubation temperatures on embryonic survival also did not differ between these two species. Both species exhibited optimal survival between 14–17° C and incipient mortalities occurred at 20°C. Temperatures above 20°C were lethal for white sturgeon embryos. No effect of low incubation temperature on survival was evident from this study. A comparison of these North American species with Eurasian acipenserids suggests that all the sturgeon that have been examined exhibit a similar influence of incubation temperature on developmental rate.
110 citations
TL;DR: It was indicated that the amount of mineralizable nitrogen in the resistant N-fraction depended directly on clay content, and variation of type and quantity of added residues changed the net N-mineralization in a characteristic way.
Abstract: In aerobic incubation experiments, nitrogen mineralization was investigated in agricultural loess and sandy soils. Fresh, fieldmoist samples were used for incubation. Using an optimization procedure the N-mineralization was split into two nitrogen fractions: A resistant, slowly decomposable organic N-fraction (index rpm) and a fast decomposable N-fraction (index dpm). Loess- and sandy soils showed similar mean reaction coefficients for N-mineralization. The results also indicated that the amount of mineralizable nitrogen in the resistant N-fraction depended directly on clay content. Soil sampling at different times during crop growing period gave different mineralization amounts and courses. Effect of added plant residues on N-mineralization, was also studied by incubation. Variation of type and quantity of added residues changed the net N-mineralization in a characteristic way: Sugar beet leaves, added in minced form, caused an increase in mineralization; while straw caused a temporary immobilization, followed by remineralization. Incubation experiments on undisturbed soil columns showed nearly linear mineralization with time.
106 citations
TL;DR: The hypothesis that following the night period about 50% of the enzyme is catalytically inactive because of the tight-binding of a small molecular weight, phosphorylated inhibitor at the active site is supported.
Abstract: The activity of ribulose-1,5-bisphosphate carboxylase/oxygenase was measured at various times during the purification of the enzyme from leaves of Nicotiana tabacum which were collected either 1 hour before the start of the photoperiod (predawn) or in the middle of the photoperiod (midday). The activity of the enzyme in extracts of the predawn leaves (0.8 units/mg enzyme) was consistently about 2-fold lower than that measured in extracts of midday leaves (1.7 units/mg enzyme). The activity of the predawn enzyme was increased to that of the midday enzyme following removal of CO(2) and Mg(2+) (deactivation), (NH(4))(2)SO(4) precipitation, or incubation in SO(4) (2-) (18 millimolar required for one-half maximal increase). Following purification to >95% homogeneity, the predawn enzyme was found to have approximately 0.5 moles of bound organic phosphate per mole of enzyme active sites, while the midday enzyme had only approximately 0.08 moles of bound organic phosphate per mole of enzyme active sites. Deactivation of the predawn enzyme or treatment with 0.2 molar SO(4) (2-) resulted in the removal of most of the bound organic phosphate. These findings support the hypothesis that following the night period about 50% of the enzyme is catalytically inactive because of the tight-binding of a small molecular weight, phosphorylated inhibitor at the active site.
105 citations
TL;DR: Results indicate that GRF stimulates both release and synthesis of GH; these two effects have different kinetics and different sensitivities to SRIF; andGRF stimulates the release of GH from heterogeneous pools disproportionally.
Abstract: The effects of rat hypothalamic GH-releasing factor (GRF) and somatostatin (SRIF) on the release and biosynthesis of rat GH were studied by RIA and quantitative immunoprecipitation using monolayer cultures of rat anterior pituitary cells In kinetic studies, GRF stimulation of GH release appeared at the first sampling time (20-min incubation) and the effect began to diminish after 2-h incubation with GRF On the other hand, total (cell plus medium) content of GH significantly increased only after 24-h incubation To examine the GHsynthesizing effect of GRF more directly, newly synthesized GH labeled by [35S]methionine during incubation with GRF was quantified by immunoprecipitation The amount of immunoprecipitable GH increased significantly and specifically (compared with the total amount of labeled proteins) also only after 24-h incubation When GH pools were labeled with [35S]methionine under different schedules, the basal release of newly synthesized GH, which was labeled for 1 h immediately before ch
90 citations
TL;DR: It is suggested that PRL can act directly on the brain to inhibit gonadotropin release and to stimulate ingestive behavior but central effects of PRL alone are not sufficient to maintain incubation readiness.
81 citations
TL;DR: The modifications and suggestions described herein for the respiratory response method, for biomass estimation, can enhance and be readily applied to long-term soil incubation studies.
Abstract: The respiratory response method to determine microbial biomass during soil incubation was investigated A maximum respiratory response at early stages of incubation can be determined without addition of extra substrates The amount of substrate required to produce a maximum respiratory response after 2–3 days of incubation was found to be similar to that required after prolonged incubation Soils with similar levels of soluble-carbon have similar substrate-saturation values As the nutritional status of the soil would decline during incubation, the use of a more complete substrate than glucose is proposed to keep the soil nutrient composition consistent during respiratory response analysis With the use of 14 C it is possible to estimate the active fraction of the total biomass The modifications and suggestions described herein for the respiratory response method, for biomass estimation, can enhance and be readily applied to long-term soil incubation studies
TL;DR: The incubation period is not endogenously timed but that prolactin may still affect the overall duration of the incubation-brood-guard period, although having little or no effect on the number or duration of incubation shifts.
TL;DR: The results suggest that some of the genes controlling minor variation in the incubation period also influence plaque production, consistent with previous evidence that the number of amyloid plaques depends, to some extent, on the duration of agent replication within the brain.
Abstract: The extent of amyloid plaque production was investigated in three inbred mouse strains carrying the p7 allele of the scrapie incubation (Sinc) gene (VM, IM and MB). With either ME7 or 87V scrapie, many more plaques were seen in the MB strain than in VM or IM mice. A backcrossing experiment using 87V suggested the involvement of more than one gene. Within this backcrossing experiment there was a positive correlation between mean plaque count and mean incubation period for the various strains and crosses. Also male mice tended to have higher plaque counts and longer incubation periods than female mice of the same genotype. These results suggest that some of the genes controlling minor variation in the incubation period also influence plaque production. This is consistent with previous evidence that the number of amyloid plaques depends, to some extent, on the duration of agent replication within the brain. This study has also identified a high plaque model (MB mice infected with 87V) for future investigation of the nature of the amyloid protein.
TL;DR: The relativelyLarge eggs of Terrapene ornata may represent the one adaptation of this species for development in terrestrial conditions, because large eggs of other turtles are more likely to hatch following incubation in a stressful hydric environment than are smaller eggs laid by conspecifics.
Abstract: Flexible-shelled eggs of the terrestrial turtle Terrapene ornata were incubated on wet (-150 kPa) and dry (-800 kPa) substrates at 29 C. Eggs on the wet medium absorbed water from the environment and increased in mass by 6% over the course of incubation, whereas eggs on the dry substrate lost water throughout development and weighed 17% less late in incubation than they did at oviposition. Availability of water to embryos had no apparent influence on hatching success, but embryos in the wet environment incubated longer, mobilized more of the nutrient reserve in their yolk, and grew larger before hatching than did those in the dry setting. Most of the ammonia released in catabolism of protein by embryonic Terrapene was detoxified by converting it to urea, which accumulated in eggs during incubation. In later stages of development urea attained concentrations inside eggs that may have been sufficient to inhibit metabolism of embryos, with the inhibition potentially being greater in dry settings than in wet ...
TL;DR: Loss in complement-fixing activity was observed at glycation levels well comparable to those found in diabetics, and inactivation of specific antibody was dependent on incubation time and glucose concentration employed.
Abstract: Incubation of purified human and rabbit immunoglobulin G with glucose leads to covalent incorporation of the sugar into the protein, depending on glucose concentration, incubation time and pH. Furthermore, the level of glycated immunoglobulin G from normal and diabetic subjects has been determined using the thiobarbituric acid reaction. The median for glycated immunoglobulin G, expressed as mmol 5-hydroxymethylfurfural per mol IgG, obtained from 20 normal and 29 diabetic subjects was 62 and 107, respectively. Glucose incubation of immunoglobulin G purified from rabbit anti-human-transferrin serum, from human anti-varicella/zoster virus serum and from human anti-lues-spirochete serum, respectively, leads to a marked decrease in biological activity, as determined in a micro complement fixation test. Inactivation of specific antibody was dependent on incubation time and glucose concentration employed. Loss in complement-fixing activity was observed at glycation levels well comparable to those found in diabetics.
TL;DR: The dynamics of scrapie agent replication in brain and spleen following intracerebral or intraperitoneal infection were investigated in a model with particularly long incubation periods, and there was no delay in onset of replication in spleen using either route of infection.
Abstract: The dynamics of scrapie agent replication in brain and spleen following intracerebral or intraperitoneal infection were investigated in a model with particularly long incubation periods [IM mice (Sincp7) infected with 87V scrapie]. In contrast to other mouse scrapie models previously investigated, there was no delay in onset of replication ('zero phase') in spleen using either route of infection, For both routes infectivity levels reached a plateau in spleen, which was maintained for at least 250 days in intraperitoneally infected mice. An infectivity plateau was also apparent in brain following intracerebral infection, suggesting that there may be constraints on agent replication in brain during the later part of the incubation period. In addition, the efficiency of the intraperitoneal route to produce disease was found to be particularly low for this model.
TL;DR: It is concluded that prolactin plays a role in maintaining readiness to incubate in doves, but that other factors may also contribute to this response.
Abstract: The role of prolactin in the maintenance of incubation behaviour in ring doves was re-examined and the dose-response relationships for behavioural, target tissue and body weight changes induced by injections of prolactin were compared in doves tested during the incubation phase of the breeding cycle. Doves given injections of prolactin twice a day starting on day 4 of incubation, during a 10-day period of isolation from their mates and nests, showed a higher persistence of incubation behaviour than doves injected with saline vehicle. However, the prolactin treatment failed to maintain incubation behaviour to the same extent as that observed in non-isolated untreated breeding pairs. Liver and body weights were higher and testicular weights lower in birds treated with high doses of prolactin than in non-isolated birds which had been incubating for 14 days. Good dose-response relationships were established between body, liver, crop and testes weights and the dose of prolactin administered. However, only a weak dose-response relationship was observed between prolactin and the maintenance of incubation behaviour. Overall, females injected with prolactin displayed more quiet sitting behaviour, less body weight gain and more gonadal regression than males injected with prolactin. Males in untreated breeding pairs had higher liver weights and lower crop weights than females. It is concluded that prolactin plays a role in maintaining readiness to incubate in doves, but that other factors may also contribute to this response. Further, it appears that prolactin mediates several target tissue changes which are sex-specific during incubation.
TL;DR: Phytohemagglutinin-induced lymphocyte proliferation was significantly inhibited by beta-endorphin, and the influence of beta- endorphin on the expression of mononuclear cell surface antigens using the OKT3, OKT4,OKT8, anti-HLA-DR and anti-beta 2-microglobulin monoclonal antibodies was evaluated.
TL;DR: This paper replies to Richter's (1982) critique of the nest failure hypothesis and further explores the problem of assessing the costs and benefits of incubating before a clutch is complete, and reexamined the brood reduction hypothesis.
Abstract: Birds vary between and within species in the moment at which they begin incubation of a clutch. The timing of incubation in birds can have important effects on fitness and thus an adaptive explanation has seemed warranted. The most prominent of the several which have been offered is Lack's (1954) brood reduction hypothesis. More recently, we outlined a nest failure hypothesis (Clark and Wilson 1981) and showed that it was supported by existing data for small altricial birds. In this paper, we reply to Richter's (1982) critique of the nest failure hypothesis and further explore the problem of assessing the costs and benefits of incubating before a clutch is complete. First, we briefly review the logic of the general problem. One effect of incubating before the last egg is laid is hatching asynchrony and the production of offspring that are younger, and therefore smaller, than their nestmates. Lack (1954) proposed that this size asymmetry is itself an adaptation to facilitate brood reduction when food becomes suddenly scarce. If equally matched nestmates compete for insufficient food, they may all receive too little and all have reduced chances for survival as nestlings or fledglings. If some nestmates are smaller, however, these are likely to starve quickly while the others receive adequate food. Another possible purpose of early incubation is to minimize the potential for total nest failure, usually by predation. A clutch on which incubation is initiated sooner will have at least some young ready to fledge sooner, as observers have often noted (e.g., Marchant 1960). A nest that is destroyed after the first offspring fledges, but before the last, is at least partially successful. If incubation had been postponed, the same nest would have been a total loss. This interpretation suggests that early incubation serves to decrease the time spent in the nest by first eggs or offspring. Size and age differences among nestlings are a by-product of the adaptation, and mortality from these differences is a cost. We (Clark and Wilson 1981) built a specific model of the nest failure hypothesis, and tested it with data from 87 altricial bird species. We also reexamined the brood reduction hypothesis. Our conclusions can be briefly summarized as follows. 1. Most small altricial birds begin incubation before the last egg is laid; in contrast, proponents of the brood reduction hypothesis give an impression of general hatching synchrony.
TL;DR: Estimates of degradability of nitrogen in the sheep rumen for a basal hay diet and for soya-bean meal, groundnut meal and fish meal, when given together with the hay, were determined from measurements of duodenal N flow, ammonia kinetics andRumen N disappearance from polyester bags and rumen outflow rate.
Abstract: 1. Estimates of degradability of nitrogen in the sheep rumen for a basal hay diet and for soya-bean meal (SBM), groundnut meal (GNM) and fish meal (FM), when given together with the hay, were determined from measurements of (1) duodenal N flow, (2) ammonia kinetics and (3) rumen N disappearance from polyester bags and rumen outflow rate. The ability of various in vitro procedures to predict in vivo N degradability was also examined.2. Four sheep were given a basal hay diet (800 g dry matter (DM) and 19 g N/d) either alone or supplemented with isonitrogenous amounts (15 g N/d) of SBM, GNM or FM. Duodenal non-ammonia-N flow (g/d) was increased more by FM (8.0) than by GNM (5.9) and SBM (5.8), whilst microbial N flow (g/d) was increased more by SBM (3.9) than by GNM (2.3) and FM (1.6). N degradability values calculated from these results were 0.88, 0.76 and 0.57 for the SBM, GNM and FM respectively. The corresponding value for hay was calculated to be 0.76.3. The irreversible loss of ammonia in the forestomachs (g N/d) was increased more by SBM (11.9) than by GNM (7.2) and FM (5.8) whilst ammonia outflow from the rumen (g N/d) was increased to a similar extent by all supplements ( I.1, 0.9 and 0.8 respectively), as was the amount of microbial N (g/d) synthesized from sources other than rumen ammonia (1.8, 2.0 and 1.9 respectively). N degradability values calculated from these results were 0.84, 0.54 and 0.45 for the SBM, GNM and FM respectively.4. The fractional rate of N disappearance (/h) when the feedstuffs were incubated in polyester bags in the rumen of sheep receiving the basal hay diet (800 g DM/d) was the highest for SBM (0,145) and lowest for FM (0.037), with the hay (0.082) and GNM (0.071) intermediate, whilst the fractional outflow rates from the rumen (/h) of the three supplements were similar (0.034, 0.038 and 0,030 for SBM, GNM and FM espectively). N degradability values calculated from these results were 0.82, 0.67 and 0.60 for the SBM, GNM and FM respectively; the value for the hay was 0.73.5. Of a number of in vitro procedures tested, only N solubility in sodium hydroxide and ammonia or total non-protein-N (NPN) production during incubation with rumen fluid in the absence of hydrazine sulphate ranked the supplements, although not the hay, in the same order as the in vivo degradability procedures. In terms of absolute values, N solubility in NaOH, at room temperature, gave estimates similar to those derived from the duodenal flow measurements; estimates derived from ammonia and total NPN production were lower.
Journal Article•
TL;DR: The findings suggest that glucocorticoid regulation of hepatocyte SC most likely involves stimulation of its synthesis and may play a role in enhancing the clearance of IgA from blood into bile in the intact animal.
Abstract: The present study examined the effects of steroid hormones on the production of secretory component (SC) by rat hepatocytes in cell culture. When hepatocytes were incubated in the presence of cortisol (10(-6) M), the levels of SC in media increased significantly after 2 days of incubation. This response was dose-dependent and specific for glucocorticoids because progesterone, dihydrotestosterone, and estradiol had no effect. When estradiol was added to the incubation media along with dexamethasone, a known potent synthetic glucocorticoid, it diminished the glucocorticoid response. The addition of cycloheximide to incubation media significantly decreased the effect of dexamethasone on SC accumulation. These findings suggest that glucocorticoid regulation of hepatocyte SC most likely involves stimulation of its synthesis. In addition, our results suggest that endogenous glucocorticoids may play a role in enhancing the clearance of IgA from blood into bile in the intact animal.
TL;DR: C. jejuni was recovered without difficulty when the intestinal tracts of chicks were enriched, but recovery from early dead-in-shell or infertile eggs was poor, suggesting that the vibrio is sensitive to some part of the incubating egg or to the temperature of prolonged incubation.
Abstract: Fertile chicken eggs were infected in our laboratory with Campylobacter jejuni suspensions by using temperature or pressure differential methods of inoculation. After 2 days of incubation, over 90% of the eggs carried C. jejuni when iron was present in the inoculum. This percentage declined rapidly until by day 8, less than 10% of the eggs were detectably infected. However, up to 11% of hatched, healthy chicks carried C. jejuni in their intestinal tracts. The isolated organisms were of the same serotype as the initial inoculum. C. jejuni was recovered without difficulty when the intestinal tracts of chicks were enriched, but recovery from early dead-in-shell or infertile eggs was poor. This poor recovery and the rapid decline of C. jejuni after 2 days of egg incubation suggest that the vibrio is sensitive to some part of the incubating egg or to the temperature of prolonged incubation. It was impossible to predict which eggs would yield infected chicks on the basis of the number of organisms taken up by each egg, and no correlation existed between the number of organisms taken up and the efficiency of the hatch, i.e., the hatch ratio. If iron was omitted from the inoculum broth, the egg infection rate at day 2 was lower.
TL;DR: A nonlinear regression model has provided reasonable predictions of the disease incubation period when used within the temperature regimes found throughout New York State.
TL;DR: The N digestibility of the protein meals and of their residues resistant to rumen degradation were estimated in cattle and the true N digestibilities of all three protein meals when fed to rats as the sole protein source were significantly reduced.
Abstract: Fishmeal (FM), meat and bone meal (MBM) and rapeseed meal (RSM) were incubated for 8h (RSM) or 24 h (FM, MBM) in nylon bags in the rumens of cattle, in order to prepare from each meal sufficient residues resistant to rumen degradation for evaluation of their nutritive value. The nitrogen (N) and organic matter (OM) contents of FM and MBM were significantly (P<0.05) reduced by rumen incubation. The modified acid detergent fibre content of RSM was increased, and only traces of glucosinolates remained after rumen incubation. The amino acid profiles of FM and RSM were observed to change as a result of rumen incubation, whereas that of MBM was unchanged. The true N digestibilities of all three protein meals when fed to rats as the sole protein source were significantly (P<0.05) reduced by prior rumen incubation (FM, 0.90 to 0.86; MBM, 0.81 to 0.55 and RSM, 0.76 to 0.67). When measured using a rat bioassay, the biological values of FM (65.0 to 79.2) and RSM (53.3 to 83.1) protein were significantly (P<0.05) increased as a result of rumen incubation but that of MBM was unchanged (47.7 vs 41.1). The N digestibility of the protein meals and of their residues resistant to rumen degradation were also estimated in cattle. Samples of the feedstuffs were placed in small polyester bags, inserted into the proximal duodenum of cattle, recovered in faeces and N disappearance from the bags measured. This technique ranked the N digestibilities of the feedstuffs in the same order as in the rat.
TL;DR: Hib in the Res phenotype (and perhaps Hib in vivo) contains more LPS than Hib in the Sen phenotype, but its LPS appears less accessible to antibody.
Abstract: Haemophilus influenzae type b (Hib) grown in broth is much more sensitive to killing by antibody to lipopolysaccharide (LPS) and complement than is Hib in bacteremic rats; upon brief incubation with low-molecular-weight components of plasma or serum, however, broth-grown cells are phenotypically converted to a resistance resembling that in vivo. This conversion was found to consume a limiting factor in serum filtrate, to require protein synthesis, and to occur independently of the presence of capsule. Less antibody to LPS bound to cells of the resistant (Res) phenotype than to cells of the sensitive (Sen) phenotype. In electrophoretic analysis the mobility of LPS bands was identical, but the staining density of the LPS bands extracted from Res cells (with phenol-water) was two-to fourfold greater than from an equal number of Sen cells. A similar differential was found in an immunologic assay of LPS in the extracts. Thus, Hib in the Res phenotype (and perhaps Hib in vivo) contains more LPS than Hib in the Sen phenotype, but its LPS appears less accessible to antibody.
Journal Article•
TL;DR: The alkyl-linked lipoidal amine 4-aminomethyl-1-[2,3-(di-n-decyloxy)-n-propyl]-4-phenylpiperidine (CP-46,665) inhibited the in vitro incorporation of tritiated thymidine into blasts of eight leukemias and cells of nine different solid tumors of human origin.
Abstract: The alkyl-linked lipoidal amine 4-aminomethyl-1-[2,3-(di- n -decyloxy)- n -propyl]-4-phenylpiperidine (CP-46,665) inhibited the in vitro incorporation of tritiated thymidine into blasts of eight leukemias and cells of nine different solid tumors of human origin. This activity was well correlated with trypan blue dye exclusion, which was tested to assess cell membrane damage. Scanning electron microscopy revealed loss of cell surface features and severe cell membrane destruction after incubation with CP-46,665. These effects on thymidine uptake and single cell viability were accompanied by a clear loss of the reproductive capacities of human tumor and leukemic cells as measured in a human tumor stem cell assay after incubation with CP-46,665.
The above-mentioned cytostatic and cytotoxic effects of CP-46,665 were dependent on dosage and incubation time. Destruction of leukemic blasts was often completed with ≥5 µg/ml after an incubation of ≥48 hr or ≥10 µg/ml after an incubation of ≥24 hr. Cells from solid tumors usually required a slightly higher drug concentration and longer incubation period for maximum killing. The alkyl-linked lipoidal amine CP-46,665 often showed considerably greater efficacy than did the alkyl-linked phospholipid rac -1- O -octadecyl-2- O -methylglycero-3-phosphocholine tested in comparison. In contrast to both drugs, 2-lysophosphatidylcholine showed only minor activity within the same dose range.
TL;DR: Prolactin can serve to maintain incubation, while incubation does not necessarily stimulate prolactin secretion at this phase of the breeding cycle.
TL;DR: Administration of lipopolysaccharide (LPS), a known activator of phospho‐lipase A2, results in a fivefold increase in PGE2 and a two fold increase in 6‐keto‐PGFlQ released into the medium.
Abstract: The release of prostaglandin E2 (PGE2) from cortical slices of mice into incubation medium is followed for 3 h and compared to PGE2 levels in the corresponding slice. Immediately after decapitation, the rate of PGE2 released into the incubation medium is elevated and a steady low rate of spontaneous release is gained within 1-2 h of incubation. PGE2 synthesis and release is blocked in a dose-dependent manner by either indomethacin (3 X 10(-6) -3 X 10(-4) M) or flufenamic acid (2.6 X 10(-6) M) either when added in vitro or administered in vivo. Full recovery of PGE2 synthesis is reached after 3 h incubation of slices following in vivo administration of indomethacin. In vivo administration of flufenamic acid results in prolonged inhibition of PGE2 released in vitro. The inhibition of PGE2 released by indomethacin is also correlated with the slice PGE2 content. Administration of lipopolysaccharide (LPS), a known activator of phospholipase A2, results in a fivefold increase in PGE2 and a twofold increase in 6-keto-PGF1 alpha released into the medium. The release of thromboxane B2 is not affected by LPS.
TL;DR: The data indicate that the epidermal beta-adrenergic adenylate cyclase response is modulated by retinoids probably as an independent mechanism stimulated by glucocorticoids or colchicine.
TL;DR: It is shown that incubation at 20 degrees C offers an approach to study 70- to 95-mg muscles in vitro without compromising structure and function and ATP concentration after incubation was not affected by temperature.
Abstract: We compared the structure, function, protein synthesis, and degradation of 70- to 95-mg rat soleus muscles during 120 min of incubation at 20 and 37 degrees C. At 37 degrees C, muscles were characterized by a damaged central core region and a decline of isometric tension development during incubation. Protein synthesis in the core region at 37 degrees C was depressed relative to the peripheral region. At 20 degrees C, developed tension remained constant during incubation, and synthesis rates in the core region were not different from the peripheral region. Compared with fresh muscle, ATP concentration after incubation was not affected by temperature. After equilibration of phenylalanine specific activity between extracellular and intracellular spaces (60 min at 20 degrees C; 30 min at 37 degrees C), rates of protein synthesis at 20 [0.048 nmol tyrosine (Tyr) X mg wet mass-1 X 2 h-1] and 37 degrees C (0.160 nmol Tyr X mg wet mass-1 X 2 h-1) were linear up to 180 and 120 min, respectively. Rates of protein degradation at 20 (0.076 nmol Tyr X mg wet mass-1 X 2 h-1) and 37 degrees C (0.248 nmol Tyr X mg wet mass-1 X 2 h-1) measured after 60 min were linear up to 180 and 120 min, respectively. Incubation at 20 degrees C offers an approach to study 70- to 95-mg muscles in vitro without compromising structure and function.