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PubMed2002

Calcium concentration in rat liver mitochondria during anoxic incubation.

BACKGROUND AND PURPOSE: The impairment of mitochondrial respiratory function is an important problem in anoxia-reoxygenation injury in animal cells. This study investigated the role of mitochondrial calcium ions (Ca2+) in a model of anoxic incubation in isolated rat liver mitochondria. METHODS: Mitochondria isolated from Wistar rat liver were subjected to anoxic incubation for 5 to 60 minutes. Changes in oxygen consumption by anoxic mitochondria were recorded using polarography. Changes in NAD(P)H fluorescence were recorded simultaneously. Intramitochondrial matrix free calcium concentration ([Ca2+]) was measured using the fluo-3/AM loading method. Respiratory function in anoxic mitochondria was measured polarographically from oxygen consumption. RESULTS: Mitochondrial state 3 respiration decreased progressively with increased duration of anoxic incubation, while state 4 respiration increased progressively. The decrease in the ADP/O ratio with the duration of anoxic incubation indicated that the efficiency of oxidative phosphorylation decreased with increased duration of anoxia. As the duration of anoxic incubation increased, the amplitude and rapidity of the oxido-reduction change in NAD(P)H fluorescence decreased. The respiratory control ratio showed that the functional integrity of mitochondria was linearly correlated with the free [Ca2+] in mitochondrial matrix (r2 = 0.977) and the total calcium concentration (r2 = 0.934). The free [Ca2+] in mitochondrial matrix significantly decreased with increasing anoxic duration. Total mitochondrial calcium concentration also decreased with increasing anoxic duration (p < 0.01). CONCLUSIONS: The supply of NADH was reduced during anoxic incubation of isolated rat hepatocyte mitochondria, which resulted in impairment of mitochondrial respiratory function. The decrease in free [Ca2+] in the mitochondrial matrix with increased duration of anoxic incubation implies that calcium ions may be released into the cytosol during anoxia.

Analysis of Variance↗
PubMed2002

[Geographic variation in female reproductive characteristics and egg incubation of Eumeces chinensis].

Geographic variation in female reproductive characteristics and egg incubation of Chinese skink (Eumeces chinensis) was studied by using two populations from eastern (Lishui, Zhejiang) and southern (Shaoguan, Guangdong) China, respectively. The results showed that female adults of the two populations both laid a single clutch per breeding season, and the clutch size, clutch mass, and egg mass had a positive correlation with female SVL. There was obvious geographic variation in head shape of females, reproductive characteristics, timing date of oviposition, and thermal dependence of egg incubation between two populations. Skinks from Shaoguan began to lay eggs in mid-May, approximately two weeks earlier than the timing date of skinks from Lishui. Skinks from Shaoguan produced more but smaller eggs. The size-specific (SVL) clutch size of skinks from Shaoguan outnumbered that of skinks from Lishui by 2.8 eggs. It implied there was a trade-off between the number and the size of offspring between populations, because there was no difference in size-specific clutch mass among skinks from both populations, and skinks within a population could produce larger clutches without a concomitant reduction in egg mass. Overall, compared to eggs incubated under 32 degrees C, eggs incubated under 24 degrees C could produce larger (SVL) and well-developed hatchlings with less unutilized yolks. Compared to eggs from Lishui incubated under the same temperature of 24 degrees C and 32 degrees C, eggs from Shaoguan produced hatchlings with smaller body wet mass and carcass dry mass. Accordingly, there was geographic variation in suitable range of incubation temperatures, and eggs laid by skinks from Lishui could successfully incubate in a wider range of temperatures.

Animals↗
PubMed1991

Ultrastructural study of isolated rat hepatocyte suspensions incubated in incomplete or complete culture medium.

Ultrastructural changes in isolated rat hepatocytes (IHC) in suspension were examined after 1, 3, 5 and 10 hr incubation, and the influence of Krebs-Henseleit (K-H) buffer as an incomplete medium and GIT culture medium (Nihon Pharmaceutical Co.) as a complete culture medium were investigated. The viability was approximately 60-75% after 1, 3 and 5 hr incubation, and was slightly higher in GIT medium than K-H buffer. Immediately after isolation, IHC showed a cuboidal shape, and after 3 and 5 hr incubation, a round shape with numerous surface microvilli. Cytoplasmic organelles appeared almost normal. After 10 hr incubation, cells reaggregated and the number of autophagic vacuoles increased. Cellular changes, such as slight dilatation of the endosplasmic reticulum and Golgi apparatus, and bleb formation in the cell surface, were more often observed in IHC incubated in K-H buffer than in GIT medium. IHC incubated in GIT medium contained glycogen particles in the cytoplasm, and lipoprotein-like particles were observed in the cisternae of Golgi apparatus and smooth endoplasmic reticulum. The lipoprotein-like particles were found in the intercellular spaces after 10 hr incubation. These results suggest that GIT medium is superior to K-H buffer in its ability to preserve normal structure and function of IHC.

Animals↗
PubMed1990

Microwave-stimulated brain enzyme incubations are possible at the unphysiological condition of 50 degrees C.

Microwave-stimulated enzyme incubations for acetylcholinesterase, 5'-nucleotidase, alkaline phosphatase, lactate dehydrogenase, malate dehydrogenase, succinic dehydrogenase and isocitric dehydrogenase were studied, and compared with incubations in a waterbath. Temperature settings of 37 degrees C and 50 degrees C were used, and the incubation times were varied from 30 seconds to 30 minutes. The desired temperature of the incubation solution was reached in the microwave oven within 1 minute, whilst in the waterbath it took 10 to 25 minutes. The microscopic results for alkaline phosphatase and succinic dehydrogenase at a temperature setting of 50 degrees C were superior in the microwave method for incubation times less than 15 minutes. It is postulated that the increased reaction product of alkaline phosphatase and succinic dehydrogenase is due to a temperature effect, which has to be large enough to be of practical value. For the other enzymes studied, microwave-stimulated incubations were no better than the conventional incubations at corresponding temperatures. For 5'-nucleotidase there were aspecific lead deposits in the microwave method. All enzymes performed at the elevated, unphysiological temperature of 50 degrees C proved to have advantages, except for 5'-nucleotidase, whilst for malate dehydrogenase there was an aspecific reduction of the colour developer at this temperature.

Animals↗
PubMed1989

Relationship between adenosine deaminase activity (ADA) and inosinemonophosphate (IMP) accumulation in fresh erythrocytes incubated with adenosine and dipyridamole.

Fresh human erythrocytes were incubated in two media: a) adenosine (10 mM), pyruvate (10 mM), phosphate (50 mM) (APP medium); b) APP medium enriched with 100 mumol/l dipyridamole (APPD) medium. The amount of IMP in fresh erythrocytes was 0.18 +/- 0.09 mumol/g Hb, after incubation in APP medium it was 1.52 +/- 0.78 mumol/g Hb, and after incubation in APP medium it was 1.52 +/- 0.78 mumol/g Hb, and after incubation in APPD the amount was 5.28 +/- 0.94 mumol/g Hb. ADA activity was measured simultaneously. The mean activity (+/- SD) of ADA fresh red cells was 1.29 +/- 0.36 U/g Hb, after 2 h incubation in APP medium it was 1.71 +/- 0.38 U/g Hb, and after 2 h incubation in APPD medium an activity of 2.68 +/- 0.95 U/g Hb was found. A highly significant correlation between the accumulation of IMP and the activity of ADA in fresh erythrocytes (r = 0.93; p = less than 0.001) and in erythrocytes incubated in APPD medium (r = 0.97; p = less than 0.001) was found.

Adenosine↗
PubMed1987

Reversibility of decreased insulin-stimulated glucose transport capacity in diabetic muscle with in vitro incubation. Insulin is not required.

The mechanisms by which insulin deficiency affects muscle glucose transport were investigated. Epitrochlearis muscles from rats with streptozotocin-induced diabetes and from controls were incubated in vitro for 0.5-14 h. The incubation was shown not to impair muscle energy stores or tissue oxygenation. Diabetes decreased basal 3-O-methylglucose transport by 40% (p less than 0.01), and insulin-stimulated (20 milli-units/ml) glucose transport capacity by 70% (p less than 0.001). In vitro incubation gradually normalized insulin responsiveness (3.77 +/- 0.38 before versus 8.97 +/- 0.65 mumol X ml-1 X h-1 after 12 h of incubation). Basal glucose transport remained significantly reduced. The reversal of the insulin responsiveness did not require the presence of rat serum and, furthermore, took place even in the absence of insulin. In fact, insulin responsiveness was higher after incubation (14 h) with no insulin than with 100 microunits/ml insulin (9.85 +/- 0.59 versus 8.06 +/- 0.59 mumol X ml-1 X h-1, p less than 0.05). Glucose at 30 mM did not affect the normalization of the insulin-stimulated glucose transport capacity, whereas incubation in serum from diabetic rats resulted in a slightly (26%) blunted reversal (7.60 +/- 0.39 versus 8.89 +/- 0.45 mumol X ml-1 X h-1 with diabetic versus control serum for 14 h, p less than 0.05; before incubation the value was 3.87 +/- 0.40). Inhibition of protein synthesis by cycloheximide blocked the normalization by 80%. These results suggest the presence in diabetic serum of some labile factor that might inhibit the glucose transport system. The results indicate that the decreased insulin-stimulated glucose transport capacity, in the insulin-deficient diabetic muscle, is not a direct consequence of the lack of insulin or of high glucose concentrations.

3-O-Methylglucose↗
PubMed1968

Dates of onset of relapses and the duration of infection in induced tertian malaria with short and long incubation periods.

The course of induced tertian malaria has been studied in patients in psychoneurological hospitals in Moscow over a long period. Various strains of P. vivax were used to infect patients; the sporozoites were transmitted by Anopheles maculipennis atroparvus bred under laboratory conditions. There are marked differences between the dates of onset of relapses, reckoned from the primary manifestations of the disease, in patients developing malaria after long and short incubation periods. P. vivax strains which have a short incubation period are characterized by producing in patients a series of relapses following a long latent period; strains with a long incubation period are characterized by the occurrence of relapses during the first 3 months after the end of the primary series of attacks. However, some P. vivax strains give rise to both types of relapse, depending on the incubation period. In any event, the duration of the disease does not, as a rule, exceed 2 years, including the incubation period. The number of mosquitos (and hence the number of sporozoites) used to infect a patient does not have any noticeable effect on the number and frequency of relapses. In short-incubation tertian malaria, the use of quinocide during the period of treatment of the primary manifestations greatly reduced the number of relapses; in long-incubation tertian malaria similarly treated with quinocide, no relapses occurred.

Anopheles↗
PubMed1983

Cholesterol efflux from cells enriched with cholesteryl esters by incubation with hypercholesterolemic monkey low density lipoprotein.

The mass efflux of free and esterified cholesterol was studied in skin fibroblasts loaded with cholesterol by incubation with low density lipoproteins (LDL) isolated from normal or hypercholesterolemic cynomolgus monkeys. Cells incubated with hypercholesterolemic LDL accumulated 2-3 times more cholesteryl ester than did cells incubated with the same amount of normal LDL. Cholesteryl oleate was the principal cholesteryl ester species to accumulate in cells incubated with both normal and hypercholesterolemic LDL. Efflux of this accumulated cholesterol was absolutely dependent on the presence of a cholesterol acceptor in the culture medium. Lipoprotein-deficient serum (LPDS) was the most potent promoter of cholesterol efflux tested, with maximum efflux occurring at LPDS concentrations greater than 1.5 mg protein/ml. Upon addition of efflux medium containing LPDS, there was a reduction in both the free and esterified cholesterol concentration of the cells. Greater than 90% of the cholesteryl esters that were lost from the cells appeared in the culture medium as free cholesterol, indicating that hydrolysis of cholesteryl esters preceded efflux. Efflux was not inhibited by chloroquine, however, suggesting a mechanism independent of lysosomes. Loss of cellular free cholesterol was maximum by 6 hr and changed very little thereafter up to 72 hr. Cholesteryl ester loss from cells decreased in a log linear fashion for efflux periods of 6-72 hr, with an average half-life for cholesteryl ester efflux of 30 hr, but with a range of 20-50 hr, depending upon the specific cell line. The rate of efflux of cellular cholesteryl esters was similar for cells loaded with normal or hypercholesterolemic LDL. In cells loaded with cholesteryl esters, cholesterol synthesis was suppressed and cholesterol esterification and fatty acid synthesis were enhanced. During efflux, cholesterol synthesis remained maximally suppressed while cholesterol esterification decreased for the first 24 hr of efflux, then plateaued at a level approximately 5-fold higher than control levels, while fatty acid synthesis was slightly stimulated. There was little difference in the rate of efflux of individual cholesteryl ester species. There was, however, the suggestion that reesterification of cholesterol principally to palmitic acid occurred during efflux. Since the rate of cellular cholesteryl ester efflux was similar regardless of whether the cells had been loaded with cholesterol by incubation with normal LDL or hypercholesterolemic LDL, the greater accumulation of cholesterol in cells incubated with hypercholesterolemic LDL cannot be explained by differences in rates of efflux.-St. Clair, R. W., and M. A. Leight. Cholesterol efflux from cells enriched with cholesteryl esters by incubation with hypercholesterolemic monkey low density lipoprotein.

Animals↗
PubMedDate not supplied

Development of a simple incubation system for metabolism studies with precision-cut liver slices.

The use of precision-cut liver slices for toxicity and drug metabolism studies becomes more and more popular. So far, most of these studies are conducted using the dynamic organ culture system as incubation system. However, this system has some disadvantages, especially for the study of drug metabolism. Therefore, the aim of this study was to develop a simple incubation system for precision-cut liver slices. Rat liver slices were incubated individually in 12-well culture plates filled with 1.5 ml Krebs-Henseleit buffer, pH 7.4. Instead of glucose, fructose was used as carbohydrate source. The plates were put on a gyratory shaker (90 rpm) in a temperature controlled incubator (37 degrees C) under an atmosphere of 95% air/5% CO2. Under these conditions slices could be kept viable for at least 11 hr, which seems to be long enough for metabolism studies. Slice thickness was a critical factor in both studies on optimal incubation conditions and metabolism studies. A correlation was found between slice thickness (i.e. slice weight) and metabolite production (amount formed/mg slice) as demonstrated with tolbutamide and diazepam as test substances. It is demonstrated that a variation in slice thickness does not alter the number of cells involved in drug metabolism (i.e. the absolute amount of metabolite formed per slice does not alter). In conclusion, the way liver slices are incubated as well as the thickness of slices highly determines the results of studies on incubation conditions and metabolism studies with precision-cut liver slices.

Animals↗
PubMed2003

Cot-nursing versus incubator care for preterm infants.

BACKGROUND: An optimal thermal environment is desirable for preterm infants. These infants are usually nursed in incubators, but cot-nursing may provide an alternative. Measures to assist the maintenance of body temperature for smaller infants in open cots include extra clothing/bedding, warming up the nursery and heating the cot mattress. Recently a heated water-filled mattress has been developed to maintain the temperature of a cot-nursed preterm infant. While there may be benefits of nursing preterm infants in open cots, there may be potential risks such as nosocomial infection caused by more handling due to easier access. OBJECTIVES: Among preterm infants allocated to cot-nursing vs incubator care in neonatal period, to assess effects on their temperature control and weight gain. SEARCH STRATEGY: The standard search strategy of the Cochrane Neonatal Review Group was used. This included searches of electronic databases: Oxford Database of Perinatal Trials; Cochrane Controlled Trials Register (Cochrane Library Issue 4 2001); MEDLINE (1966-2001); and CINAHL (1982-2001), previous reviews including cross references. SELECTION CRITERIA: All trials using random or quasi-random patient allocation in which infants receiving care in standard newborn cots were compared to infants managed in a conventional air heated incubator. DATA COLLECTION AND ANALYSIS: The authors independently assessed trial quality and extracted data for the primary outcomes of temperature control and weight gain. Meta-analysis was conducted using a fixed effects model. Results are presented as relative risk (RR) for categorical data and mean difference (MD) and weighted mean differences (WMD) for data measured on a continuous scale. MAIN RESULTS: Nine potential studies were identified of which four, involving 173 babies, were included in this review. When compared to incubator care, cot-nursing resulted in a statistically significantly higher mean body temperature (MD 0.30 degrees C; 95% CI 0.10, 0.50, one trial) and a decrease in proportion of infants not breast feeding at hospital discharge (RR 0.52; 95% CI 0.28, 0.94, two trials, 77 infants). No statistically significant difference was shown in weight gain, reported by two trials involving 69 infants. The comparison of cot-nursing using a heated water-filled mattress versus incubator care, which included four trials and a total of 149 infants, produced similar results. Cot-nursing with warming of the nursery resulted in statistically significantly smaller weight gain during week one compared to the incubator group in one trial that involved 49 infants (MD -5.90 g/kg/day; 95% CI -11.13, -0.67) with no significant difference found for weeks two and three. REVIEWER'S CONCLUSIONS: Due to the small numbers of trials included and infants studied, and the resulting imprecision in the measures of effect for all outcomes, the review does not give a clear indication for the role of cot-nursing for preterm infants. Further assessment of the role of cot nursing for preterm infants using randomised controlled trials is necessary.

Beds↗
PubMed2006

MRI-compatible incubation chamber for cell culture experiments.

PURPOSE: To develop an incubation chamber that is compatible with MRI, while avoiding sources of error due to the experimental setup. MATERIALS AND METHODS: Two identical and gas-tight chambers were constructed of Plexiglas. The temperature and the CO(2) concentration were adjustable. Temperature variations within and between both chambers were measured. The pH values of the cell culture media were measured under different environmental settings. For each environment a colony formation test was carried out. The homogeneity of the magnetic field inside the chambers was estimated by phantom tests. RESULTS: The temperature variations within the chambers were <0.3 degrees C, and the variation between the chambers was on average <0.05 degrees C. After eight hours the pH values of the cell culture media were 7.47 and 7.48 in the reference and measurement chambers, respectively; 7.41 in the CO(2) incubator; and 8.73 in ambient air. In colony formation tests the survival fraction in the Plexiglas chamber was comparable to that in the CO(2) incubator. No distortions of the magnetic field from the incubation chamber were observed. CONCLUSION: The incubation system presented can provide the conditions of a CO(2) incubator without alteration of the magnetic flux density.

Carbon Dioxide↗
PubMed1995

Using Fyrite to monitor incubator carbon dioxide levels.

PURPOSE: The Fyrite analyzer (Bacharach, Incorporated) was evaluated to ascertain whether it would perform within the range specified by the manufacturer (+/- 0.5%). Fyrite analyzer samples were compared to control samples obtained using an infrared CO2 monitor (Ohmeda, Model Number 5200). METHODS: Ten Fyrite analyzer measurements from each of three incubators were obtained using two different analyzers by three investigators for a total of 60 measurements per investigator. Twenty control measurements for each of the three incubators were obtained using an infrared monitor calibrated at the 5.0% CO2 level. RESULTS: Fyrite analyzer values fell outside of an acceptable range (Control mean CO2 +/- 0.5%) for 7 of 60 (11.7%) observations for Incubator 1 and 4 of 60 (6.7%) observations for Incubator 2. (Incubator 3 had no values outside the range.) The Fyrite analyzers were significantly different from each other (P = 0.002). The three investigators (I) differed significantly from the control (I1 and I3, P < 0.001; I2, P = 0.02) as well as from each other (I1 vs I2, P < 0.001; I1 vs I3, P < 0.001; I2 vs I3, P < 0.016). CONCLUSIONS: Use of an infrared monitor for incubator calibration and monthly CO2 checks in concert with daily use of the Fyrite as a monitoring tool only is the better method.

Calibration↗
PubMed1992

An application of computational fluid mechanics to the air flow in an infant incubator.

An application of the computational fluid mechanical method to the air flow in a two-dimensional model of an infant incubator was described. The air flow in a numerical model was simulated and the Navier-Stokes equations were directly solved using a finite-volume method incorporating a body-fitted coordinate system on a mini-supercomputer. The model was based on a real infant incubator, slightly simplified for the sake of computing speed, and included a model of a baby. The number of computation grids was 101 x 61 = 6161. The calculation was carried out under the condition of unsteady, starting airflow and the results were examined by the means of color graphics animation. There were several very large scale eddies in the incubator free space, and their global structure did not show strong changes once they were established. Although the global structure did not change, small scale eddies were shown to be produced around the air inlet and convected down through the free space of the incubator. From these results, we believe that assuming steady and uniform flow in the incubator may not always be relevant when considering heat loss of a baby in an incubator. The steady and uniform flow has been previously assumed either implicitly or explicitly by most of the authors.

Air↗
PubMed2002

Incubation of rigid-shelled turtle eggs: do hydric conditions matter?

Rigid-shelled eggs of the broad-shelled river turtle Chelodina expansa were incubated at 28 degrees C in wet (-100 kPa), intermediate (-350 kPa) and dry (-750 kPa) conditions. Incubation period was influenced by clutch of origin, but was independent of incubation water potential. Rates of water gained from the environment and pre-pipping egg mass were influenced by incubation water potential -- eggs incubating at higher (less negative) water potentials absorbing more water from their environment. Hatchlings from wet conditions had greater mass but a smaller amount of residual yolk than hatchlings from dry conditions and it is suggested that the amount of yolk converted to tissue is influenced by the amount of water absorbed by the egg during incubation. Water content of yolk-free hatchlings from the -100-kPa treatment was greater than those from the -350-kPa and -750-kPa treatments, but the water content of residual yolks was similar across all hydric conditions.

Absorption↗
PubMed2005

Successful pig embryonic development in vitro outside a CO2 gas-regulated incubator: effects of pH and osmolality.

We investigated the effects of HEPES in the medium (to maintain pH) and paraffin oil covering the medium (to maintain osmolality) on the developmental ability of porcine embryos produced in vitro using tightly closed glass tubes in the absence of a CO2 gas-regulated incubator. Putative porcine zygotes obtained by in vitro fertilization (IVF) of in vitro-matured (IVM) oocytes (day of IVF=Day 0) were cultured in 5% CO2 gas-equilibrated NCSU-37 media containing pyruvate and lactate during Days 0-2, and glucose during Days 2-6, in open glass tubes in a CO2 incubator or tightly closed glass tubes without a CO2 incubator at 38.5 degrees C. The following four media were used: (1) medium covered with paraffin oil and supplemented with HEPES; (2) medium covered with paraffin oil but with no HEPES supplementation; (3) medium not covered with paraffin oil but supplemented with HEPES; (4) medium not covered with paraffin oil and with no HEPES supplementation. As a control group, zygotes were cultured in medium with neither paraffin oil coverage nor HEPES supplementation using a four-well dish in a CO2 gas-regulated incubator. After culture, the osmolality in each of the four closed conditions was maintained at approximately 285-286 mOsm, lower (P<0.05) than that in the control (291 mOsm). In the two HEPES-supplemented media groups in the closed-tube system, the pH was maintained at 7.5-7.7, and the blastocyst development rates (15.5% in non-oil covered and 18.5% in oil covered group) did not differ significantly from that of the control (20.2%), although the mean cell numbers in the blastocysts in the two closed-tube condition groups (28.2 and 33.0) were lower (P<0.05) than in the control (43.5). In contrast, the pH was higher in the two groups without HEPES supplementation (approximately 8.0) than the control (7.4; P<0.05), and the blastocyst development rates (10.9% in non-oil covered and 7.5% in oil covered group) or total cell numbers in the blastocyst (24.8 and 28.7) in the two non-HEPES groups were drastically decreased (P<0.05) compared to those in the control (20.2% and 43.5). These results suggested that maintenance of pH is important for successful in vitro porcine embryo culture under closed-air conditions, whereas the range of osmolality that suits embryo development is not limited to a small range. Furthermore, blastocyst production was possible in a glass tube without a CO2 incubator, although blastocyst quality was lower compared to those produced in an incubator.

Animals↗
PubMed1988

Environmental temperature control in very low birth weight infants (less than 1000 grams) cared for in double-walled incubators.

To evaluate the effect of fluctuations in environment and body temperatures on preterm infants, we recorded these variables in very immature newborn infants (birth weight less than 1000 gm) cared for in double-walled incubators (Air-Shields model C-100 and Ohio model IC). Both incubators maintained environmental temperatures corresponding overall to the set point, despite incubator openings. Under skin temperature servocontrol, however, environmental temperature fluctuations were greater than 2 degrees C even in strictly controlled conditions. The pattern of incubator temperature fluctuations depended on the set point rather than on the type of incubator (conventionally heated or heated by warm air blown between the double walls). The long-term clinical significance of the incubator temperature variability remains to be determined; the choice between air and skin servocontrolling should depend in part on the need for environmental stability.

Body Temperature↗
PubMed2002

Cryopreserved precision-cut rat liver slices: morphology and cytochrome P450 isoforms expression after prolonged incubation.

Precision-cut liver slices are an accepted in vitro system for toxicological investigations. However, cryopreservation of slices would make a more efficient utilisation, particularly of human liver tissue possible. In the present study sections of cryopreserved male rat liver slices were examined immunohistochemically for cytochrome P450 (CYP) isoforms expression after prolonged incubation and after exposure to typical inducers. Morphologically, with just thawed slices no major alterations were seen, but remarkable cell damage was observed even after 2 h of incubation mainly in the middle of the slices and in the periportal and intermediate regions of the lobules. After 24 h of incubation, viable cells were only observed at the edges of the slices or around bigger vessels. In the viable cells of the cryopreserved liver slices after 2 h of incubation CYP expression pattern was similar to that in normal liver specimens: a low CYP1A1, but a strong CYP2B1 and 3A2 expression predominantly in the central and intermediate lobular zones. After 24 h, the immunostaining for CYP2B1 and 3A2 in the viable cells was reduced, but that for CYP1A1 was increased. Incubation with beta-naphthoflavone further elevated CYP1A1 and 2B1 expression. Phenobarbital caused an enhanced CYP2B1 and 3A2 and dexamethasone and pregnenolone 16 alpha-carbonitrile an increased CYP3A2 immunostaining. These results show that also in cryopreserved liver slices and after a prolonged incubation, a distinct expression pattern and an in vitro induction of phase I enzymes can be demonstrated immunohistochemically.

Animals↗
PubMedDate not supplied

Vibration analysis on incubating eggs and its relation to embryonic development.

Coucke (1998) was the first to use acoustic resonance analysis to monitor embryo development in chicken eggs. He remarked that at around 100 hours of incubation, the course of the resonant frequency and damping changed abruptly in the case of fertile eggs. He also showed that these changes were related to a physiologic event during early embryonic development. The objective of our study is to monitor the course of the vibration parameters during the early incubation of chicken eggs and to relate these changes to egg and embryo characteristics. A total of 72 Hybro eggs were incubated vertically in a small incubator at standard conditions. Several egg parameters were measured before incubation. During the early stages of incubation the vibration behavior of these eggs was monitored. The time at which the damping of the vibration suddenly changed, the diameter of the eggs and their interaction were found to be significant explanatory variables in order to predict hatching time. A correlation coefficient r of 0.72 was obtained.

Animals↗