Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “INCUBATOR”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources
PubMed1975

Binding of intracellular protein to the erythrocyte membrane during incubation: the production of Heinz bodies.

During sterile incubation of normal human erythrocytes at 37 degrees C., intracellular nonhemoglobin protein is bound to the membrane prior to hemolysis. These studies have characterized this phenomenon further. Protein binding to the membrane began after 12 hours incubation when cellular ATP was depleted and increased to 36 hours incubation. The binding was prevented by adding adenosine or glucose at the start of incubation and was arrested by adding adenosine to regenerate ATP during the course of incubation. However, protein, once bound, was not released by regeneration of ATP. The amount of protein bound was not altered by: (1) addition of Ca++ or EDTA to the medium, (2) blockade of sulfhydryl groups with N-ethylmaleimide, or (3) stabilization of heme-globin bonds by conversion of hemoglobin to cyanmethemoglobin. Conversion of hemoglobin to carboxyhemoglobin by incubations under carbon monoxide inhibited protein binding, but this appeared to be an effect of exclusion of oxygen rather than stabilization of heme-globin bonds since incubation under nitrogen had a similar effect. The morphological counterpart of this chemically-measured membrane-bound protein was visible in red cell ghosts stained with crystal violet as small membrane-associated particles resembling Heinz bodies. Sodium dodecyl sulfate acrylamide gel electrophoresis of membranes of incubated cells revealed a new protein band that was identical to globin monomers. This membrane binding of globin during incubation provides a model for the study of Heinz body formation in clinical disorders.

Adenosine↗
PubMed2004

Transfer of preterm infants from incubator to open cot at lower versus higher body weight.

BACKGROUND: The use of incubators in helping to maintain a thermoneutral environment for preterm infants has become routine practice in neonatal nurseries. As one of the key criteria for discharging preterm infants from nurseries is their ability to maintain temperature, the infant will need to make the transition from incubator to open cot at some time before discharge. The timing of this transition is important because when an infant is challenged by cold, the infant attempts to increase its heat production to maintain body temperature. The increase in energy expenditure may affect weight gain. The practice of transferring infants from incubators to open cots usually occurs once a weight of around 1700-1800 g has been reached; however, this practice varies widely between neonatal units. This preferred weight mark appears to be largely based on tradition or the personal experience of clinicians, with little consideration of the infant's weight or gestational age at birth. OBJECTIVES: The main objective was to assess the effects on weight gain and temperature control of a policy of transferring preterm infants from incubator to open cot at lower versus higher body weight. SEARCH STRATEGY: Searches were undertaken of MEDLINE from June 2003 back to 1966, CINAHL from June 2003 back to 1987 and the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2003). The title and abstract of each retrieved study were examined to assess eligibility. If there was uncertainty, the full paper was examined. SELECTION CRITERIA: Trials in which preterm infants were randomly allocated to a policy of transfer from incubators to open cots at a lower body weight versus at a higher body weight. DATA COLLECTION AND ANALYSIS: Quality assessments and data extraction for included trials were conducted independently by the reviewers. Data for individual trial results were analysed using relative risk (RR) and mean difference (MD). Results are presented with 95% confidence intervals (CI). Due to insufficient data, meta-analysis could not be undertaken. MAIN RESULTS: Four studies were identified as potentially eligible for inclusion in this review. Two studies were excluded as random allocation to the exposure was not employed. One study is pending, awaiting additional information from the authors. Therefore, one study involving 60 preterm infants, employing a matched-pairs design, which compared the transfer of infants to open cots at 1700 g versus 1800 g, is included in this review. Only two outcomes could be included from this study; return to incubator and daily weight gain. No statistically significant difference was shown for either return to incubator (RR 2.00, 95% CI 0.40 to 10.11) or daily weight gain [MD 4.00 g/day (95% CI -5.23, 13.23)]. Due to small numbers, effects on clinically important outcomes could not be adequately assessed. REVIEWERS' CONCLUSIONS: There is currently little evidence from randomised trials to inform practice on the preferred weight for transferring preterm infants from incubators to open cots. There is a need for larger randomised controlled trials to address this deficiency.

Body Temperature Regulation↗
PubMed1981

Determination of scrapie agent titer from incubation period measurements in hamsters.

Progress in studies on the scrapie agent has been hampered by the slow and tedious endpoint titration assays in rodents. A new assay based on incubation period measurements has been developed. The incubation period is defined as the time interval from inoculation to the onset of clinically detectable neurological illness or as the interval from inoculation to death. Both of these intervals or incubation periods are inversely proportional to the size of the dose injected intracerebrally into random bred weanling syrian hamsters. The incubation period was found to be a linear function of the logarithm of the inoculum size over a wide range of dosages (10(2) - 10(8) ID50 units). From these studies an equation relating the titer of the inoculum to the dilution of the sample and the length of the incubation period has been developed facilitating the use of a computerized record system. Validation of the assay was provided by comparing samples where the agent was measured both by endpoint titration and incubation period methods. Agreement between the 2 methods was generally within +/- 0.5 log10 ID50 units. In addition, no differences between the molecular properties of the agents from hamster and murine sources have been detected using primarily the incubation period method with the former and endpoint titration with the latter. The advantages of the incubation period assay are considerable with respect to time and economy.

Animals↗
PubMed2001

Influences of incubation temperature and various saccharides on the production of organic acids and gases by gut microbes of rainbow trout Oncorhynchus mykiss in a micro-scale batch culture.

We studied the influence of incubation temperature and additional saccharides on the metabolism of hindgut microbes of the rainbow trout Oncorhynchus mykiss in a 50 microl-scale batch culture system. Intestinal contents of rainbow trout reared at 15 degrees C were incubated with glucose, lactosucrose, sodium alginate or colloidal chitin (each 10 g/l) at 15 degrees C or 25 degrees C for 12 h. Levels of organic acids at 0 h and 12 h of incubation were quantified with HPLC. We also monitored gas release from these cultures during incubation. The main product was iso-butyric acid, except for the cultures with colloidal chitin where no net production of organic acids was observed. We detected higher levels of iso-butyric acid in cultures with lactosucrose than in the other cultures. Net production of this acid was less in cultures with colloidal chitin than in blank cultures. The volume of released gas was larger when incubated at 25 degrees C than at 15 degrees C. Cultures with colloidal chitin released more gas than blank cultures when they were incubated at 15 degrees C. Cultures with sodium alginate released less gas than blank cultures irrespective of incubation temperature. These results indicate that the hindgut microbes of this carnivorous fish mainly produce branched-chain fatty acids, very likely by microbial digestion of nitrogenous materials rather than saccharides. However, additional saccharides affected production of branched-chain fatty acids. The influence of incubation temperature in the present study also suggested that the environmental temperature of host fish should affect microbial digestion in the fish gut.

Acids↗
PubMedDate not supplied

Improved transport incubator temperature control with insulating thermal cover.

INTRODUCTION: Cold stress, secondary to heat loss, can compromise infants in transport incubators during interfacility transfer. With current incubator designs, considerable radiant heat loss occurs. The use of additional external thermal insulation to reduce heat loss has been recommended for infant transports in cold environments. METHOD: A laboratory experiment was done to compare the rate of heat loss from a transport incubator with and without a commercially available, thermal insulating cover in place. The environment was a commercial freezer simulating subzero environmental temperatures. Measurements included air temperatures. inside the incubator and freezer, patterns of heater action and duration of battery power output. The significance of the different rates of cooling was compared using Pearson's r. Suboptimal battery performance was excluded by repeating one arm of the study with an external battery in place of the internal unit. RESULTS: The rate of heat loss from the incubator was: 1) significantly slower when the covered and uncovered incubators were compared (r2 = 0.52), and 2) essentially identical for the uncovered incubator with either the internal or the external battery (r2 = 0.96). CONCLUSION: In the laboratory setting, external thermal insulation slows transport incubator radiant heat loss. Clinically, this effect likely would benefit infants at risk of cold stress during interfacility transports.

British Columbia↗
PubMed2001

Effects of incubator humidity and hen age on yolk composition in broiler hatching eggs from young breeders.

The effects of broiler breeder age (26, 28, and 30 wk) and incubator relative humidity (43, 53, and 63% RH) on yolk sac weight and composition in broiler hatching eggs between 16 and 19 d of incubation were evaluated. Percentage yolk sac weight was reduced in eggs from the youngest (26 wk) breeder hens and in eggs incubated at 53% RH. Percentage yolk moisture, in eggs from the youngest hens, was lowest at 16 d and was highest at 19 d, and percentage yolk lipid was highest at 16 and 17 d of incubation in eggs from 30-wk-old hens. Percentage yolk lipid content was higher at 63% RH compared with 53% RH in eggs from 26-wk-old breeders but was lower in eggs incubated at a 43% RH compared with 53 and 63% RH from 30-wk-old breeders. Yolk stearic and arachidonic acid concentrations were higher and myristic acid concentration was lower in eggs from the 26-wk-old hens. Conversely, the highest yolk concentrations of linolenic and palmitoleic acids occurred in eggs from 30- and 28-wk-old breeders, respectively. At 16, 17, 18, and 19 d of incubation, yolk oleic acid concentrations were significantly, but variably, affected by breeder age, whereas linoleic acid concentration was highest in 26-wk-old breeders only at 19 d. Palmitic acid concentration at 17 d was lower in eggs incubated at 53% RH compared with 43 and 63% RH. Rate of yolk uptake from the yolk sac by embryos may be increased by incubating eggs at 53% RH, and the effects of changes in RH between 43 and 63% on yolk lipid content are influenced by breeder age.

Age Factors↗
PubMed1980

The construction of a closed-chambered incubator for use in such techniques as enzyme and immunoperoxidase histochemistry.

Many histochemical procedures, in an attempt to be as variable-free as possible, often require such a quantity of incubation solution that there is a resulting waste of expensive chemical substrates, coupling salts, antigens, etc. More economic procedures are justifiably ignored in histochemical studies because of their uncontrollable variables. However, the variables associated with one such economic procedure (the drop method) can now be eliminated by utilizing the closed-chambered incubator described in this paper. Slides containing tissue sections incubated in this apparatus need only 1 ml of incubation medium per slide to achieve a similar reaction product as tissue sections emersed in Coplin jars of medium. This incubator incorporates a water-bath circulator to heat and circulate water below a shelf containing the tissue sections. Within 0.5 h, the entire incubating chamber is saturated with a 310 K water vapour. The water vapour eliminates the primary variable of the drop method incubation, evaporation of the medium. This paper describes the construction of the incubator, its evaluation, the savings obtained from one simple histochemical procedure and its applicability in enzyme and the immunoperoxidase histochemical techniques.

Enzymes↗
PubMed2004

Randomized controlled trial of skin-to-skin contact from birth versus conventional incubator for physiological stabilization in 1200- to 2199-gram newborns.

AIM: Conventional care of prematurely born infants involves extended maternal-infant separation and incubator care. Recent research has shown that separation causes adverse effects. Maternal-infant skin-to-skin contact (SSC) provides an alternative habitat to the incubator, with proven benefits for stable prematures; this has not been established for unstable or newborn low-birthweight infants. SSC from birth was therefore compared to incubator care for infants between 1200 and 2199 g at birth. METHODS: This was a prospective, unblinded, randomized controlled clinical trial; potential subjects were identified before delivery and randomized by computerized minimization technique at 5 min if eligible. Standardized care and observations were maintained for 6 h. Stability was measured in terms of a set of pre-determined physiological parameters, and a composite cardio-respiratory stabilization score (SCRIP). RESULTS: 34 infants were analysed in comparable groups: 3/18 SSC compared to 12/13 incubator babies exceeded the pre-determined parameters (p < 0.001). Stabilization scores were 77.11 for SSC versus 74.23 for incubator (maximum 78), mean difference 2.88 (95% CI: 0.3-5.46, p = 0.031). All 18 SSC subjects were stable in the sixth hour, compared to 6/13 incubator infants. Eight out of 13 incubator subjects experienced hypothermia. CONCLUSION: Newborn care provided by skin-to-skin contact on the mother's chest results in better physiological outcomes and stability than the same care provided in closed servo-controlled incubators. The cardio-respiratory instability seen in separated infants in the first 6 h is consistent with mammalian "protest-despair" biology, and with "hyper-arousal and dissociation" response patterns described in human infants: newborns should not be separated from their mothers.

Anxiety, Separation↗
PubMed2001

A clinical comparison of radiant warmer and incubator care for preterm infants from birth to 1800 grams.

OBJECTIVE: The objective of this study was to compare radiant warmer and incubator care for preterm infants from birth with respect to temperature control and weight gain. METHODS: Sixty preterm infants <33 weeks' gestation were randomized at birth to radiant warmer or incubator care. The initial goal was to maintain abdominal temperature at 36.8 degrees C in both groups and axillary temperature at 36.8 to 37.3 degrees C; air servocontrol was used for incubator infants. Infants in both groups received added humidity for 5 days if their weight was <1000 g and for 3 days if they weighed between 1000 and 1249 g. During a 3-hour period on days 1 to 7, recordings of abdominal, forehead, and foot temperatures were obtained. The percentage of the recording time during which the abdominal temperature was in the target range of between 36 degrees C and 37.5 degrees C was determined as an indicator of temperature control. Weight gain from birth to 1800 g was compared. Secondary outcomes included fluid balance and clinical events. RESULTS: There were 30 infants in each group; 48 were <1500 g (of whom 17 were <1000 g). There were no significant differences in birth weight, gestation, gender, or illness severity scores in the 2 groups. Significant differences in temperature control were noted on day 1. Although admission temperatures were similar, lower abdominal temperatures were noted in the first 2 hours of life in the incubator group (medians were 36.6 degrees C and 35.9 degrees C in the radiant warmer and incubator groups, respectively). Similarly, mean abdominal temperatures during the 3-hour recording on day 1 were lower in the incubator group, and infants in this group spent a significantly greater percentage of the recording time with temperatures outside the target range (17.3% compared with 0.88%). Other temperature recordings from the forehead and foot were not significantly different in the groups. Fluid intakes were higher for infants under radiant warmer on days 2, 3, and 4, and the difference amounted to a mean of 12.8 mL/kg/d. Maximum sodium levels in the first week were similar in the 2 groups. Mean weight gain was 17.4 g/kg/d for the radiant warmer group and 17.1 g/kg/d for the incubator group; days to regain birth weight and length of hospital stay were not significantly different. Greater numbers of infants in the radiant warmer group required phototherapy, and adverse events (which included death, necrotizing enterocolitis, chronic lung disease, grade 3 or 4 intraventricular hemorrhage, periventricular leukomalacia, or retinopathy requiring laser treatment) were less frequent in the radiant warmer group (1 infant compared with 8 in the incubator group; relative risk 0.1; 95% confidence intervals: 0.01-0.82). CONCLUSIONS: This study has shown differences in abdominal temperatures on day 1 and outcome, although the latter finding should be viewed with caution because of the sample size. The results indicate benefits for the initial use of the radiant warmer after birth. Although fluid requirements were higher in the radiant warmer group for days 2 through 4, the increased fluid volumes were given without apparent adverse effect.

Body Temperature↗
PubMedDate not supplied

Incubator noise: a method to decrease decibels.

PURPOSE: To examine the effect of covering the incubator on environmental noise levels inside the incubator. METHOD: Noise level measurements were taken to measure noise outside the incubators, inside the uncovered incubators, and inside covered incubators of 24 premature infants. The sound levels and differences in patient care equipment were analyzed by means, t-tests, and ANOVA. FINDINGS: Significant differences were found between the covered and uncovered incubators' sound level readings. Covered incubators had lower noise level readings. CONCLUSION: Covering incubators is one method to decrease environmental noise in the NICU.

Evaluation Studies as Topic↗
PubMed1997

Oxygen-free radical-mediated injury to cultured rat hepatocytes during cold incubation in preservation solutions.

We have previously shown that the injury to cultured liver endothelial cells during cold incubation in University of Wisconsin (UW) solution is energy-dependent and is mediated by reactive oxygen species. Here we demonstrate that this reactive oxygen-mediated injury is specific neither to endothelial cells nor to UW solution: cultured hepatocytes incubated in cold (4 degrees C) UW solution or histidine-tryptophan-ketoglutarate (HTK) solution were injured under normoxic conditions (loss of viability, 63% +/- 10% after 48 hours of cold incubation in UW solution and 82% +/- 11% after 24 hours of cold incubation in HTK solution), whereas hypoxia was protective (loss of viability, 29% +/- 12% [UW] and 13% +/- 3% [HTK] after the same cold incubation times). The injury under normoxic conditions was also largely decreased by adding either the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) or the flavonoid silibinin to the solutions, or by preincubating the cells with the iron chelator deferoxamine before the hypothermic incubation. Marked lipid peroxidation was observed during cold incubation in both preservation solutions. These results suggest that the injury to cultured hepatocytes during cold incubation in UW and HTK solutions is mediated by reactive oxygen species as is the injury to cultured liver endothelial cells.

Adenosine↗
PubMed1994

Lens-on-surface method for investigating adhesion of Staphylococcus aureus to solid surfaces incubated in blood plasma.

Adhesion of Staphylococcus aureus was investigated on flat silicon oxide surfaces that had been incubated in human plasma at different concentrations. Adhesion of bacteria did not occur at high incubation concentrations of plasma or when the surface had been incubated in egg albumin. However, significant adhesion was observed when plasma was diluted. With the use of antibody method, it was noted that the adhesion of the bacteria coincided with adsorbed fibrinogen, and possibly also with IgG. We also investigated the effect of "narrow space" on the adsorption of blood plasma and subsequent adhesion of S. aureus. In these experiments, blood plasma was incubated under a convex lens placed upside-down on the silicon oxide surface. This method creates a continuous gradient of space from the contact point of the lens and outward. After rinsing off the plasma and the lens, the surface was incubated with a suspension of S. aureus followed by quantification of the attached bacteria by means of optical methods. Adhesion of bacteria occurred in several circular zones that were easily detectable with the naked eye or by the means of simple optical methods. In addition, in these experiments, adhesion coincided with adsorbed fibrinogen or IgG at the surfaces. The increased bacterial adhesion to surfaces incubated in diluted plasma, or plasma incubated in narrow space, is a variant of the so-called "Vroman effect." With a model protein system consisting of fibrinogen and IgG and the corresponding antibodies, we demonstrate that "dilution" and "incubation in narrow space" are two phenomenologically similar methods.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗
PubMed1989

Effects of in vitro incubation on a zona binding site found on murine spermatozoa.

Murine cauda epididymal sperm possess a site, the acceptor, on the plasma membrane over the apical cap region of the acrosome which recognizes both a proteinase inhibitor of seminal vesicle origin and homologous zonae. The acceptor site may participate in both capacitation and zona binding. This presentation explores the effect of in vitro incubation in a medium known to induce capacitation on the binding capabilities of this site. Approximately 80% of fresh cauda epididymal sperm will bind the seminal inhibitor in vitro. Incubating sperm, pretreated with inhibitor for 2 hr in a medium (M199-M) known to support capacitation, reduces by 60% the number of sperm showing evidence of the inhibitor. No such decrease is seen when sperm are incubated in a medium (M199) that does not support capacitation. During the 2-hr incubation in either medium, 60-70% of the sperm retain two diverse components on the plasma membrane over the acrosome: a receptor for the Fc portion of IgG and an epitope recognized by a monoclonal antibody to the acceptor site. These observations suggest that the plasma membrane in the acrosome region of the cell remains structurally intact during incubation. Furthermore, sperm retain the ability to bind the seminal inhibitor during incubation. After a 2-hr incubation in M199-M, sperm pretreated with heat-solubilized zonae no longer bind the inhibitor. These sperm, however, retain the plasma membrane over the acrosomal cap region. When the sperm are incubated in M199, no decrease in inhibitor binding due to zona treatment is noted.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrosome↗
PubMed1987

Effects of in utero and in vitro incubation on the lipid-bound fatty acids and sterols of porcine spermatozoa.

Sperm-rich semen and washed porcine spermatozoa were incubated for up to 2 hr either in utero in the presence of oviduct fluid or in vitro at 37 degrees C. Sperm lipids were extracted and separated into phospholipid and neutral lipid fractions. Eleven phospholipid and five neutral lipid fatty acids were identified and quantified using GC and GC-MS. The percentage of 22:5n6, the major phospholipid fatty acid, decreased slightly but significantly during 1.5 hr of in utero incubation (41.2-38.0%), but after 2.0 hr of in utero incubation no significant difference was observed (40.0%). None of the phospholipid fatty acids changed in concentration during in vitro incubation. The mole ratio of phospholipid to phospholipid fatty acid (1.00:1.27) did not change during incubation. The levels of neutral lipid-bound 14:0 decreased (43.5% to 31.8%) and that of 18:0 increased (11.1% to 18.2%) during in utero incubation. Similar but less pronounced changes were observed during in vitro incubation. (43.5% to 36.0%; and 11.1% to 15.8%, respectively). Two major sterols, cholesterol (73%) and desmosterol (27%) were identified by gas chromatography-mass spectrometry. The mole ratio of phospholipid to sterol (2.47:1:00) did not change during incubation.

Animals↗
PubMed1993

Adenine nucleotides and inhibition of protein synthesis in isolated hepatocytes incubated under different pO2 levels.

Hepatocytes incubated at a pO2 of 0 mm Hg (N2/CO2, 95%/5%) loose their intracellular ATP content and their ability to synthesize RNA and proteins. Protein synthesis is virtually inhibited from the beginning of the incubation, while ATP content is gradually lost, thus suggesting a primary response of the cell to the absence of O2 rather than to ATP depletion. Such an early decrease of protein synthesis (as estimated as the incorporation of [14C]Leu into cell proteins) is unlikely the result of inhibition of amino acids uptake, enhanced protein degradation, or decreased RNA synthesis. Reoxygenation of such previously hypoxic cells with O2/CO2 at 95%/5% (pO2 of 700 mm Hg), leads to the recovery of both ATP and protein synthesis, even better the hypoxic period is not longer than 30 min. In hepatocytes incubated for 30 min under a pO2 of 700, 80, or 50 mm Hg, cell survival and ADP content are almost identical. Incorporation of radiolabelled leucine is linear in cells incubated under 700 mm Hg O2, but it rather stops at a pO2 of 80 or 50 mm Hg. The time course of both ATP and GTP content behaves in a similar way: it is fairly constant at a pO2 of 700 mm Hg, but a depletion is initiated after 20 min of incubation at a pO2 of 50 or 80 mm Hg. Finally, incubation of hepatocytes either at 700 or 0 mm Hg O2, in the presence of fructose (10 mM), shows that ATP content is maintained at the same level whatever the pO2 level. AMP content is increased only in cells incubated at 0 mm Hg O2 in the absence of fructose. Incorporation of radiolabelled leucine is stopped in such hypoxic cells incubated or not in the presence of fructose. From these results it appears that the presence or the absence of O2 might represent a turn on/off signal to which hepatocytes respond immediately by important metabolic changes like the inhibition of protein synthesis.

Adenine Nucleotides↗
PubMed1998

Antipredator behaviour of hatchling snakes: effects of incubation temperature and simulated predators.

All animals that are exposed to predators must distinguish dangerous from nondangerous threats and respond correctly. In reptiles, emerging hatchlings are vulnerable to a wide range of predators, particularly if they emerge during daylight. In these experiments I tested the response of pine snake, Pituophis melanoleucus, hatchlings incubated at 22-23, 27-28, or 32-33 degreesC to visual and vibratory stimuli to examine antipredator behaviour. Emerging hatchlings were exposed to one of five conditions: (1) hawk model, (2) white head model with no facial features, (3) white head model with black eyes, (4) a person, or (5) a vibration without a visual stimulus. I tested the null hypotheses of no differences in response as a function of predator type or incubation temperature. Emergence behaviour when undisturbed was affected by incubating temperature, and antipredatory behaviour was affected by both predator type and incubation temperature. Pine snake hatchlings responded more protectively (withdrawal into tunnels) than defensively (striking), responded with less intensity to a vibration compared with visual predator stimuli, and required longer to respond to a head model without eyes than to all other predator types. Given the relatively small size of hatchlings, it is adaptive for them to withdraw into the nest rather than attack a predator. Hatchlings from eggs that were incubated at medium temperatures required less time to emerge from their underground nests when undisturbed, and had stronger protective responses than snakes incubated at other temperatures. These results suggest that hatchlings incubated at medium temperatures are generally less vulnerable to predators than hatchlings incubated at higher or lower temperatures. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1996

Changes in bioactive prolactin-like activity in plasma and its relationship to incubation behavior in breeding ring doves.

Previous radioimmunoassay (RIA) data indicate that plasma prolactin (PRL) is elevated during the late incubation and the early posthatching periods of the ring dove breeding cycle. Although these changes are temporally associated with changes in PRL-dependent crop sac growth, the precise relationship between immunoreactive and bioactive PRL has not been directly examined. To investigate this question and to further explore the relationship between sitting behavior and PRL secretion, we used rat Nb2 lymphoma cell proliferation to estimate the concentration of bioactive PRL-like activity (PLA) in the plasma of breeding ring doves. Serial dilutions of dove pituitary homogenate and dove plasma stimulated mitogenic responses that were parallel to those observed with purified ovine PRL. Changes in plasma PLA during the breeding cycle closely resembled changes in PRL that have been previously reported by RIA, although the relative changes in PLA were more pronounced. In both sexes, PLA remained at basal levels prior to egg laying and during early incubation (Day 4-5) but then abruptly increased to reach peak values near the time of hatching (Day 14-15). Activity remained high for 3-4 days after hatching, declined gradually thereafter, and returned to baseline values by Posthatching Days 14-17. Plasma PLA levels of birds sampled at the end of incubation were correlated with those of their breeding partners. In the majority of pairs, females had higher PLA levels than their mates at this stage even though no significant overall sex differences in PLA levels were observed. Plasma PLA declined precipitously in birds that were nest deprived on the last day of the incubation period. Nevertheless, plasma PLA levels of normally breeding birds at the end of incubation were not correlated with the average time spent in the nest during the incubation period. However, day-to-day variability in time spent in the nest correlated negatively with plasma PLA in incubating males, and females exhibited a similar trend that approached significance. These data suggest (1) that published RIA estimates of PRL are reasonably accurate reflections of changes in bioactive PLA in dove plasma and (2) that while sitting duration itself is not strongly related to plasma PLA, large day-to-day fluctuations in nest occupation time are associated with reduced PLA levels in incubating doves.

Animals↗
PubMed1998

Influence of stimuli from chicks on behavior and concentrations of plasma prolactin and luteinizing hormone in incubating hens.

Removal of eggs from the nests of incubating birds or substitution of eggs for chicks disrupts incubation behavior and induces changes in the secretion of prolactin and luteinizing hormone (LH). The aim of the present study was to determine how different stimuli, such as physical contact with eggs and tactile, visual, and/or auditory cues from chicks, interact to control the transition between incubation and brooding and to induce changes in prolactin and LH plasma concentrations. Physical contact with chicks, in the presence or absence of eggs, induced brooding behavior and an immediate fall in plasma prolactin concentration and a gradual increase in LH concentration. Vocalizations, particularly clucking and food calls, increased rapidly while incubation and nest attachment disappeared slowly. No change in plasma prolactin or LH concentration was observed in incubating hens which could hear and see or only hear chicks. These incubating hens showed no interest in chicks and continued to incubate persistently. To conclude, tactile stimuli, alone or in combination with visual and/or auditory stimuli from newly hatched chicks, are the only cues that induce the transition from incubation to brooding and the associated decrease in prolactin secretion and increase in LH secretion.

Acoustic Stimulation↗