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At least 217 records · Page 12Linked to original sources

PubMed1995

Powdered eggshell: a pilot study on a new bone substitute for use in maxillofacial surgery.

The present study is a preliminary report on the use of hen's eggshell as a possible bone substitute. In the first part of the study, particles ranging from 400 microns to 600 microns in diameter were bioassayed in an intramuscular pouch in rodents. This material was found to be biocompatible, but appeared not to have osteoinductive capacities. In the second and third part of the study, this material was used as an interpositional graft material in critical-size defects of rat mandibles and rabbit skulls. At 2 months, a morphologic restoration was obtained using the graft, but the healing was only achieved by fibrous union. In the fourth part of the study, the material was experimented on as an onlay bone graft on rabbit mandibles. A 6-month follow-up of the implant confirmed its stability. In conclusion, the use of this safe and inexpensive material is suggested for filling limited bone defects in non-weight-bearing areas. The use of eggshell powder for bone augmentation may also be considered, after further studies, to assess its long-term stability.

Animals↗

PubMed2002

Aspartame optical biosensor with bienzyme-immobilized eggshell membrane and oxygen-sensitive optode membrane.

An aspartame optical biosensor has been fabricated by employing a bienzyme system composed of alpha-chymotrypsin and alcohol oxidase immobilized onto an eggshell membrane and an oxygen-sensitive optode membrane as the transducer. The detection schemes involve the enzymatic reactions of aspartame leading to the depletion of the oxygen level of the medium with a concomitant enhancement of the fluorescence intensity of the oxygen-sensitive membrane. The scanning electron and transmission electron micrographs show the microstructure of the eggshell membrane which is successfully immobilized with bienzyme. Using this novel immobilization technique, the aspartame biosensor shows extremely good stability with a shelf life of at least 8 months. The rate change of the fluorescence intensity in 4 min is found to be linearly related to the concentration of aspartame. The useful analytical working range of the biosensor is from 0.056 to 3.07 mM aspartame. The effects of temperature, pH, and ionic strength on the response of the aspartame biosensor are investigated in detail. Citric acid, cyclamic acid, D-fructose, D-galactose, D-glucose, hydrogen peroxide, DL-malic acid, L-phenylalanine, saccharin, sodium benzoate, and sucrose show no interferences but ethanol interferes strongly. The aspartame biosensor has been applied to determine aspartame contents in some commercial products.

Animals↗

PubMed1999

Ostrich eggshell as a bone substitute: a preliminary report of its biological behaviour in animals--a possibility in facial reconstructive surgery.

The aim of this study was to assess the biological behaviour of an implant of ostrich eggshell in various animal models of facial bone reconstruction. The implant was first bioassayed in a rat muscle pouch (n=10), and then tested as an interpositional graft in rat (n=10) and rabbit (n=5) cranial defects. It was finally used as an onlay graft on rabbit mandibles (n=5). Animals were killed after two months in the bioassay, three months in the interpositional model, and six months in the onlay model. The specimens were studied by contact radiography and standard histological techniques. All animals showed normal wound-healing. In the bioassay, the implants produced only a minimal inflammatory reaction. In the interpositional model, the implants maintained a good contour, but there was no sign of graft-remodelling. In the onlay model, the grafts were stable and partly osteointegrated. The onlay graft model gave the most promising results. Because ostrich eggshell is inexpensive and has good mechanical properties, it deserves further study. Long-term studies will clarify its possible role in maxillofacial surgery.

Animals↗

PubMed1992

Relationship between shell structure and movement of Salmonella enteritidis across the eggshell wall.

1. Ultrastructural analyses of the eggshells of one strain of commercial layers indicated that the cuticular layer is rarely present as an even covering over the shell surface and the paired shell membranes are invariably pitted with holes larger than bacterial dimensions. 2. The above conditions pertain irrespective of the age of the laying bird. 3. Bacterial penetration of the eggshell is independent of pore numbers. 4. In the absence of a functional cuticle and with the shell membranes removed, bacteria are checked in their movement by structural modifications in the mammillary layer.

Age Factors↗

PubMed1998

Organic matrix morphology and distribution in the palisade layer of eggshells sampled at selected periods during lay.

1. 1 cm2 pieces of eggshells from a commercial battery flock were plasma etched to remove the outer shell membranes. 2. They were decalcified using EDTA (200 g/l, pH 6.9 to 7.0) in paraformaldehyde (20 g/l) and 25% gluteraldehyde (20 ml in 0.98 l) in phosphate buffer, then prepared for light and transmission electron microscopy. 3. Light microscopy revealed a differential distribution of matrix material within all 3 regions of the palisade layer at the beginning of lay. 4. Transmission electron microscopy revealed a more even distribution of matrix at the beginning of lay, although morphological differences were observed. At the end of lay all 3 regions showed an increase in % matrix and vesicles/10 cm2 of micrograph compared to the middle and beginning of lay periods. 5. It is hypothesised that matrix vesicles are involved in the regulation of the physiochemical environment within the forming eggshell and that the decline in shell quality associated with the end of lay is related to a concomitant change in matrix quality.

Animals↗

PubMed1999

Features of eggshell formation in guinea fowl: kinetics of shell deposition, uterine protein secretion and uterine histology.

1. Rate of calcium carbonate deposition, duration of eggshell formation, organic composition of the uterine fluid, morphology of the egg shells and histochemistry of the uterus were studied in guinea fowl to analyse the origin of such thick, strong egg shells. 2. The egg shell was linearly deposited from 6.4 h to 21.8 h after the oviposition of the previous egg. The rate of egg shell deposition was similar to that in laying hens. However, the duration of linear shell deposition was increased by 2.1 h relative to that in hens. This explained the increased egg shell weight observed in the guinea fowl. 3. Intervals between oviposition of intra-clutch eggs were 24 h throughout the laying period. Ovulation occurred just after oviposition of the previous egg in the guinea fowl, as previously observed in hens but the duration of egg white protein deposition, of plumping and of initiation of shell mineralisation were all 1.5 h shorter than in domestic hen. 4. Uterine fluid can only be collected during the growth and terminal phase of shell formation. The electrophoretic profiles of the uterine fluid differed between phases and were somewhat different from those previously observed in the hen. Ovalbumin and ovocleidin-17 were both present in the uterine fluid and also in egg shell extract. Ovocleidin-17 was predominant during the growth phase. 5. The histology of the uterus differed slightly in guinea fowl compared to hens. Ovocleidin and ovalbumin are both secreted by the tubular glands. 6. Examination of radial ultrathin sections of eggshell showed, above the mammillary layer, intricate interlacing of adjacent exospherite in guinea fowl in contrast to the continuous columnar microstructure in hens. 7. The kinetics of egg shell deposition largely explains the increased egg shell weight of guinea fowl. The organic matrix proteins may be associated with the contrast between the structural organisation of the guinea fowl egg shell and that of the hen egg shell.

Animals↗

PubMed2001

The functions of the multiproduct and rapidly evolving dec-1 eggshell gene are conserved between evolutionarily distant species of Drosophila.

The Drosophila dec-1 gene encodes multiple proteins that are required for female fertility and proper eggshell morphogenesis. Genetic and immunolocalization data suggest that the different DEC-1 proteins are functionally distinct. To identify regions within the proteins with potential biological significance, we cloned and sequenced the D. yakuba and D. virilis dec-1 homologs. Interspecies comparisons of the predicted translation products revealed rapidly evolving sequences punctuated by blocks of conserved amino acids. Despite extensive amino acid variability, the proteins produced by the different dec-1 homologs were functionally interchangeable. The introduction of transgenes containing either the D. yakuba or the D. virilis dec-1 open reading frames into a D. melanogaster DEC-1 protein null mutant was sufficient to restore female fertility and wild-type eggshell morphology. Normal expression and extracellular processing of the DEC-1 proteins was correlated with the phenotypic rescue. The nature of the conserved features highlighted by the evolutionary comparison and the molecular resemblance of some of these features to those found in other extracellular proteins suggests functional correlates for some of the multiple DEC-1 derivatives.

Amino Acid Sequence↗

PubMed1997

Improving eggshell quality at high temperatures with dietary sodium bicarbonate.

Two experiments were conducted that confirmed the hypothesis that a dietary bicarbonate supplement will improve eggshell quality in hens at high temperatures as long as feed is consumed during the period of eggshell formation. End-of-lay hens were maintained on continuous light at temperatures of 30 and 35 C. Individual egg weights and shell quality measures for each hen were calculated as a proportion of the initial values determined during an acclimatization period at 25 C. Improvements in shell breaking strength in both experiments were observed as a result of supplementing control diets with 1% sodium bicarbonate (NaHCO3). This response to NaHCO3 was not a reflection of a reduced rate of lay or egg mass output, as these were similar or inferior on the control diets. Similar feed intakes on the control and NaHCO3 diets indicated that the response was not related to differences in calcium intakes. Supplements of zinc methionine and ascorbic acid proved to be inferior to NaHCO3. Improvements in egg weight were associated with the introduction of continuous lighting.

Acclimatization↗

PubMed1998

Effects of dietary fat and eggshell cuticle removal on egg water loss and embryo growth in broiler hatching eggs.

The effects of dietary fat and eggshell cuticle removal on egg water loss, embryo growth, and hatchability were determined in eggs from broiler breeder hens at different ages. Hens were fed isocaloric diets containing one of three different types and levels of added fat. In addition, eggs were either left intact or washed to remove the eggshell cuticle prior to set. Cuticle removal increased egg water loss between 43 and 62 wk. Cuticle removal increased relative wet embryo weight at Week 52 and relative dry embryo weight at 52 and 62 wk. Furthermore, at 62 wk, diet and day of incubation interacted to affect wet embryo weight, and diet variably affected dry embryo weight. No treatment differences were observed for cumulative hatchability, rate of hatch, and relative yolk sac weight at Day 19 of incubation. It was concluded that cuticle removal and the addition of fat to breeder diets may influence embryonic growth without having any subsequent effects on hatchability.

Animal Feed↗

PubMed2000

Paternal influences on turkey embryonic growth in the absence of changes in egg weight and eggshell conductance.

The hypothesis was proposed that embryonic growth could be influenced paternally in the absence of changes in egg weight or eggshell conductance. Sire families were established by selecting 11 sires based on blood sampling of approximately 50 commercial turkey males. Southern blot analysis was used to identify the most distantly related individuals in the subpopulation. Five hen siblings or half-siblings of the males were randomly assigned to each male to randomize effects of egg size and eggshell conductance. Artificial inseminations were performed weekly for 17 wk, using each sire with the assigned hens. Fertilized eggs were collected and set in incubators at biweekly intervals. Offspring were observed at the time of hatching for sex, body weight, and blood glucose concentration. Significant differences among sires were observed at hatching for poult weights and blood glucose concentration, and a significant correlation between the BW and glucose concentration was noted. Progeny of sires with the highest and lowest BW and blood glucose concentrations were subsequently compared. Mean BW of poults from different sires differed by as much as 10 g, although they were hatched from eggs of the same weight. Elevated blood glucose was associated with heavier BW; heavier heart, liver, and muscle weights; a rapid utilization of glycogen at pipping; and increased gluconeogenesis as measured by plasma organic acids and glucose-6-phosphatase activity. We conclude that poult embryonic growth differs even when not mediated by egg size and functional characteristics.

Animals↗

PubMed2000

Mineral, amino acid, and hormonal composition of chicken eggshell powder and the evaluation of its use in human nutrition.

Chicken eggshell powder (ESP) might be an attractive source of Ca for human nutrition. To study its nutritional value, we analyzed minerals, amino acids, and hormones in commercially available Slovakian ESP. The mineral composition was compared with three Dutch ESP samples that differed in feed and housing, a Japanese ESP, refined CaCO3, and an oyster shell supplement. Chicken eggshell powder contains high levels of Ca (mean +/- SD/g EPS: 401+/-7.2 mg) and Sr (372+/-161 microg) when compared with recommended or estimated daily intakes for humans 51 to 70 yr of age. Levels of potentially toxic Pb, Al, Cd, and Hg were very low as were levels of V, B, Fe, Zn, P, Mg, N, F, Se, Cu, and Cr. Large differences in the levels of F, Se, Cu, Cr, and Sr in the Dutch and Slovakian ESP indicated a strong influence of feed and environment. The small protein fraction of ESP contains high levels of Gly and Arg. Furthermore, small amounts of transforming growth factor-beta1 (0.75 to 7.28 ng/g ESP), calcitonin (10 to 25 ng/g ESP), and progesterone (0.30 to 0.33 ng/g ESP) were detected. Estradiol-17beta and calcitriol were below the detection limit of the methods used. Compared with ESP, refined CaCO3 was found to contain increased levels of Cd, and the oyster shell supplement showed increased levels of Al and Cd. Therefore, ESP seems to have a beneficial composition with about 39% of elemental Ca, relevant amounts of Sr, and low levels of Al, Pb, Cd and Hg. It may be used as a Ca source in human nutrition.

Aged↗

PubMed2002

Reduction of eggshell aerobic plate counts by ultraviolet irradiation.

The effects of 254 nm ultraviolet light (UV) radiation on aerobic plate count (APC) of egg shells were investigated. In the first experiment, eggs were exposed to UV treatment (7.35 mW/cm2) for 0, 15, 30, and 60 s. Three eggs from each treatment were aseptically collected and placed into sterile plastic bags containing 50 mL of sterile phosphate-buffered solution. Serial dilutions of the phosphate-buffered solution were plated on aerobic plate count agar and incubated at 37 C for 48 h. Exposure of eggshells to 30 and 60 s UV significantly reduced aerobic plate counts compared to untreated eggs. Exposure to 60 s of UV resulted in a 2 to 3 log10 cfu/egg APC reduction and reduced counts below detectable levels. In the second experiment, UV lights were placed in a chamber equipped with a commercial-style egg conveyor. A UV treatment of 7.5 mW/cm2 and time intervals of 0, 12, 36, and 48 s were used. Three eggs were placed consecutively on the conveyor and passed through the chamber. The center egg was selected for APC evaluation. Sample size, dilution, plating, and incubation procedures were used as described for the first experiment. A significant 1 to 2 log10 reduction in colony-forming units per egg between the eggs treated 48 s to the untreated eggs was detected. The results of these studies show that UV light treatment at high intensities and low time intervals has the potential to reduce aerobic plate counts of eggshells.

Animals↗

PubMed1992

Pleistocene geochronology and palaeothermometry from protein diagenesis in ostrich eggshells: implications for the evolution of modern humans.

Proteinaceous residues incorporated within the crystal structure of ostrich eggshells (OES) are retained without loss over geological time exceeding 10 million years. Degradation of the polypeptides, including hydrolysis to smaller peptide fragments and eventual release of free amino acids, decomposition, and racemization and epimerization occur at regular, predictable rates dependent on ambient temperature. The extent of isoleucine epimerization (aIle/Ile ratio) in OES follows linear first-order reversible kinetics in controlled-temperature laboratory simulations of time up to an aIle/Ile ratio in excess of 1.0. The hydrolysis of leucine also follows a predictable pattern, but deviates from first-order kinetics. A nonlinear mathematical model has been developed that adequately describes the pattern of leucine hydrolysis through a wide temperature range. Arrhenius parameters were derived from laboratory experiments combined with rate constant values found for 14C-dated OES from stratified caves in southern Africa. These parameters for isoleucine epimerization and leucine hydrolysis differ by ca. 10%, allowing the simultaneous solution of the two equations for temperature, independent of sample age. Although the uncertainty of the simultaneous temperature is relatively high (+/- 10 degrees C), it provides an effective means of identifying burned samples. If sample age is known, palaeotemperatures (the integrated thermal history experienced by an eggshell as opposed to an 'instantaneous' temperature) can be calculated with a precision of better than +/- 1 degrees C. The ages of levels at Border Cave, South Africa, from which anatomically modern human skeletal remains have been recovered, are dated by the extent of isoleucine epimerization in associated OES.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Cloning and analysis of the dec-1 female-sterile locus, a gene required for proper assembly of the Drosophila eggshell.

Female-sterile mutations at the dec-1 (defective chorion-1) locus of Drosophila severely disrupt the organization of the eggshell late in oogenesis. Previous characterization of dec-1 mutations has correlated the defects with failure to accumulate an early eggshell protein that undergoes proteolytic cleavage during choriogenesis. To enable further study of the regulation and processing of dec-1 products, we have molecularly cloned the locus and characterized its transcripts. Chromosome jumping was used to isolate a deficiency breakpoint within the locus. Overlapping genomic clones from a wild-type library were then obtained, and a region including the dec-1 locus was identified by hybridization to cDNA probes complementary to RNA from stage 9-10 egg chambers. Analysis of genomic rearrangements associated with the locus verified its identity. Two transcripts from the locus have been identified and characterized using cDNA clones, RNase protection, and primer extension analyses. A 4.0-kb transcript accumulates maximally in stages 9-10, when the primary follicle cell protein associated with dec-1 mutations is synthesized. A second transcript of 5.8 kb, generated by alternative splicing, accumulates during stages 11-12. These results are discussed in light of previous analysis of dec-1 mutations.

Animals↗

PubMed1978

Isolation of messenger RNA coding for eggshell protein of the DNA-eliminating nematode Ascaris lumbricoides.

Poly(A)-containing RNA from polyploid uterine epithelial cells of Ascaris lumbricoides has been isolated by poly(U)-Sepharose chromatography. The bulk of poly(A)-containing RNA migrates as 18-S RNA in formamide/polyacrylamide gels. In a cell-free wheat germ system, this RNA directs the synthesis of a polypeptide with identical migration behavior in dodecylsulphate/urea/polyacrylamide gels as the polypeptide isolated from the proteinaceous eggshell. The two proteins reveal almost identical peptide patterns in fingerprint analysis. The authentic eggshell protein has been identified as a glycoprotein with a molecular weight of about 10000, as determined by dodecylsulphate/polyacrylamide gel electrophoresis. The apparent discrepancy between mRNA length and the required coding length for the protein is discussed.

Animals↗

PubMed1983

The inhibitory effect of some chlorinated hydrocarbon pesticides on the ATP-dependent Ca2+ binding of the particulate fraction of the eggshell gland mucosa cells.

The pesticide p-p'-DDT and its persistent metabolite p-p'-DDE cause thinning of the eggshells in several species of birds. In earlier investigations on ducks this thinning was found to be associated with a reduction of the ATP-dependent Ca2+ binding to a homogenate of the shell gland mucosal cells by DDE. The activity of a Ca2+-Mg2+-activated ATPase in the homogenate was also decreased on administration of DDE in vivo. We have therefore investigated the in vitro effects of some other chlorinated hydrocarbon pesticides of ecotoxicological interest on the ATP-dependent Ca2+ binding and the Ca2+-Mg2+-activated ATPase activity in a homogenate of the eggshell gland mucosa of the hen and determined the molar concentrations that produced 50% inhibition (=IC50). Several of the investigated compounds, namely toxaphene, chlordane, p-p'-DDD, o-p'-DDE, p-p'-DDT, methoxychlor and PCB (Arochlor 1242), had a similar IC50 to inhibit the Ca2+ binding as p-p'-DDE. Lindane, p-p'-DDA and biphenyl had an IC50 3.3-4 times higher and that of 2.4 D was 13.5 times higher than that of p-p'-DDE. When the IC50 of some of the compounds (p-p'-DDE, PCB, toxaphene, Lindane) was determined that decreased the Ca2+-Mg2+-activated ATPase of the homogenate it was found to be only 18 to 29 per cent of that needed to inhibit the Ca2+ binding by the homogenate. It is therefore probable that some other effect than inhibition of this enzyme is also involved in the Ca2+-binding process and affected by the compounds.

Adenosine Triphosphatases↗

PubMed1986

Effect of some metal compounds on the Ca2+ binding and Ca2+-Mg2+-ATPase activity of eggshell gland mucosa homogenate from the domestic fowl.

Some metal ions, e.g. Hg2+, Cd2+ and Al3+, can have the effects as ecotoxicological agents, of causing eggshell thinning and breakage in birds. In a homogenate of the Ca2+-secreting part of the eggshell gland mucosa, a study was made of the influence of Hg2+, Cd2+, Cu2+, Pb2+, methyl-Hg+, Zn2+, V3+, Al3+ and Ni2+ in different concentrations on the rate of ATP-dependent 10(-4) M Ca2+ binding. All compounds had an inhibitory action. The most potent metal (Hg2+) produced 50% inhibition (IC50) at 1.1 X 10(-6) M, whereas this value for the least potent compound (Ni2+) was 9 X 10(-4) M. The specific Ca2+-Mg2+-ATPase activity was also inhibited by the tested metal ions. In all cases except methyl-Hg+ the IC50 for this activity was lower than that for Ca2+ binding. The most potent ion in this respect was Cd2+, with an IC50 of 8 X 10(-8) M, and the least potent was methyl-Hg+, with an IC50 of 1.4 X 10(-3) M. Pb2+ and Cd2+ in a concentration range of 10(-5)-10(-4) stimulated the Mg2+-ATPase activity, however, to almost the same extent as 10(-4) M Ca2+. A possible explanation for this effect is that these ions may have an affinity for sites of Ca2+ binding of the polypeptide calmodulin and thereby influence the Ca2+ metabolism of the shell gland mucosa.

Animals↗

PubMed1971

DDE residues and eggshell changes in Alaskan falcons and hawks.

Eggshell thickness after exposure to DDT was reduced by 21.7 percent in Alaskan tundra peregrines, by 16.8 percent in taiga peregrines, by 7.5 percent in Aleutian peregrines, by 3.3 percent in rough-legged hawks, and not at all in gyrfalcons. Tundra peregrine eggs contain an average of 889 parts of DDE per million (lipid basis); taiga peregrine eggs contain 673 parts per million; Aleutian peregrine eggs contain 167 parts per million; rough-legged hawk eggs contain 22.5 parts per million; and gyrfalcon eggs contain 3.88 parts per million. These changes in eggshell thickness and the pesticide residues reflect different degrees of exposure to contamination. There is a highly significant negative correlation between shell thickness and DDE content in peregrine eggs. Tundra and taiga peregrines have fledged progressively fewer young each year since 1966.

Alaska↗