Delay of ganglion cell death by tetrodotoxin during retinal development in chick embryos

Acid-soluble collagen from rat skin was modified by active oxygen in vitro, and properties of the modified collagen as a substratum for fibroblasts were studied. When collagen was treated with ascorbate-copper ion systems, cross-linking and a little degradation occurred rapidly. The cells attached but spread poorly on the modified collagen gel as compared with on the untreated collagen gel. On the other hand, when collagen was treated with H2O2-copper ion systems, only degradation of collagen molecule occurred rapidly. This treatment did not affect the attachment and spreading of the cells on the collagen gel, but when the incubation was continued for a long time, the cells migrated actively and gathered. Thymidine incorporation by the cells was suppressed on both modified collagen gels as compared with that on untreated collagen gel, and the extent of the suppression on the H2O2-copper-treated collagen was larger than that on the ascorbate-copper-treated collagen. These results indicate that the active oxygen-induced cross-linking and degradation significantly alter properties of collagen as a substratum for fibroblasts.     

Pattern formation in chick feather development: distribution of beta 1-integrin in normal and scaleless embryos

We have examined the immunolocalization of beta 1-integrin during feather development in the spino-lumbar tract of the backskin from normal and scaleless chick embryos. beta 1-integrin appears during early feather development in three distinct phases which correspond to important developmental events. The first phase (5-5 1/2 days of incubation; Hamburger and Hamilton [H.H.] stage 27) represents the period prior to the formation of dermis. During this phase, beta 1-integrin antiserum labels mesenchymal cells located in the central region of the spino-lumbar tract where the initiation site for feather development is located. The second phase (5 1/2-7 1/2 days of incubation; H.H. stages 28-32) corresponds to the period during which dermis is formed. The cells that make up the dermis are readily distinguished by their lack of beta 1-integrin immunostaining. The third phase (7 1/2-10 days of incubation; H.H. stages 33-36) begins with the sudden appearance of beta 1-integrin in the central and lateral regions of the dermis. The pattern of beta 1-integrin immunostaining in scaleless backskin becomes different from that of normal backskin during this phase. In normal backskin the dermal condensations of feather germs are not labeled with the beta 1-integrin antiserum. This produces a heterogeneous immunostaining pattern very similar to the pattern seen for Type I collagen (Mauger et al. [1982] Dev. Biol. 94:93-105). In contrast, homogeneous immunostaining is observed in the dermis of scaleless backskin. The initial time of appearance, manner of appearance, and pattern of integrin expression in the third phase suggest that beta 1-integrin may be involved in the stabilization of the feather pattern. We also observed the appearance of beta 1-integrin on the epidermal basal cells during the time of feather follicle formation. The beta 1-integrin antiserum reacts strongly with the baso-lateral surfaces of normal basal cells, yet the basal surfaces of the scaleless basal cells are unstained. This lack of immunostaining along the basal surfaces of the scaleless basal cells may relate to the abnormal adhesion between the epidermis and dermis in scaleless backskin.     

Mortality, size of the gonads, and ultrastructure of primordial germ cell in chick embryos treated with gamma-irradiation or injected with donor cells

The effects of injection and/or gamma-irradiation prior to injection on mortality, size of the gonads, and ultrastructure of primordial germ cell (PGC) were examined after 5 d of incubation. The mortality of embryos injected with donor cells was significantly higher than that of control and irradiated embryos. All irradiated embryos were alive, although their development was delayed compared to those not exposed to irradiation. The size of the gonads of embryos injected with donor cells were similar to those of control embryos, however, the size of the gonads in irradiated embryos was significantly smaller than those of control embryos. The number of PGC in the gonads was significantly decreased by irradiation. There was no notable effect of irradiation or injection on the nuclei and cytoplasmic organelles in PGC.     

Toxic interactions between disopyramide and propranolol in chick embryos

The toxic interaction between disopyramide and propranolol were studied in chick embryos. Fertilized eggs of White Leghorns were incubated and investigated. Disopyramide with and without propranolol was injected into the air sac of a fertilized egg on the 16th day of incubation. Electrocardiograms (ECGs) were recorded 0 to 60 min after the injection. After each drug injection alone, the heart rate was not different compared with control. However, the heart rate was significantly decreased by combination with disopyramide and propranolol. In addition, arrhythmia was produced by disopyramide 1.0 mg/egg alone and in combination with propranolol. These findings indicate that the interaction between disopyramide and propranolol has a marked influence on the heart rate in chick embryos.     

Effect of amifostine (Ethyol) on the development of extraembryonic blood vessels in chick embryos

An unrecognised right aortic arch (RAA) found at thoracotomy may complicate the repair of oesophageal atresia (OA) and tracheo-oesophageal fistula (TOF). This paper analyses the patient characteristics, peri-operative management, and outcome of 16 infants with a RAA, and proposes management guidelines. Between 1948 and 1996, 709 patients with OA/TOF were admitted to the Royal Children's Hospital, of whom 13 had a RAA. Three additional cases from two other paediatric surgical units were included. All 16 case records were reviewed retrospectively. The overall incidence of RAA in OA was 1.8%. Neither a chest radiograph in 16, nor antenatal ultrasonography in 7 detected a RAA. Post-natal echocardiography (ECHG) detected a RAA in only 1 of 7 infants examined; that patient underwent repair of the OA through a left (L) thoracotomy. The other 15 infants underwent initial right (R) thoracotomy. Six of these had a complete repair from the R side and 5 had division of the fistula only; 2 of these 5 had initial division of the fistula, and the OA was repaired through a repeat R thoracotomy 4 and 7 weeks later. In the remaining 4 infants where the fistula could not be located at the initial R thoracotomy, complete repair proved possible through the L chest. Three of these infants underwent an immediate L thoracotomy; the 4th had a delayed L thoracotomy 1 week later. There were 6 deaths: these occurred early in the study and were related to severe prematurity, congenital heart disease (CHD), and post-operative respiratory complications. CHD was identified in 11 of 16 infants (71%). Routine pre-operative ECHG is unreliable in determining the laterality of the aortic arch. Should a RAA be encountered during a R thoracotomy for OA, it is often possible to divide the fistula and repair the OA from that side, but where repair looks potentially difficult it is wise to proceed to an immediate L thoracotomy.     

Protective role of thyroxine in methylparathion intoxicated chick embryos

Graded activity of the DPP signaling pathway is critical for specification of dorsal embryonic cell fates in Drosophila. We present evidence that a second BMP ligand, SCW, potentiates DPP activity. Using dominant-negative forms of the type I receptors SAX and TKV, we demonstrate that SAX mediates the SCW signal, while TKV is required for both DPP and SCW activity. We find that while DPP/TKV signaling is obligatorily required, SCW/SAX activity is necessary but not sufficient for dorsal patterning. SAX and TKV act synergistically, suggesting a mechanism for integration of the SCW and DPP signals. Further, we show that the extracellular protein SOG can antagonize SCW, thus limiting its ability to augment DPP signaling in a graded manner.     

Effect of selenium and mercury on survival of chick embryos

Factorial experiments were arranged in a completely randomized or randomized block design. The factors included: selenium and day of injection; mercury and day of injection; selenium and mercury; and selenium, mercury and day of injection. Each treatment factor consisted of several levels, selenium ranged from 0.00 p.p.m. to 0.05 p.p.m., mercury from 0.00 p.p.m. to 0.30 p.p.m. and injection was performed on day-3, 9, and 15 of incubation. Babcock-300, and White Leghorn x New Hampshire cross eggs were obtained from 13-15 month old hens. Mercury was injected into the air cell at 4 or 24 hours after selenium injection. Analysis of variance on arcsine transformed data showed that selenium significantly decreased survival at all 3 injection times (P less than 0.01). Survival was significantly greater with increasing age at injection (P less than 0.01). Survival of embryos significantly decreased (P less than 0.01) with increasing levels of mercury from 0.00 p.p.m. to 0.20 p.p.m. injected into eggs on day-3 of incubation. Survival of embryos injected at later stages was less than that of controls but not significantly less. Injection of low levels of selenium, 0.01 p.p.m. or 0.02 p.p.m., to mercury treated eggs tended to improve the survival of embryos as compared to treatment with mercury alone, although individual differences were not significant. At higher levels, selenium accentuated the toxicity of mercury.     

Vascular effects of endothelin-1 in stage 21 chick embryos

Endothelin-1 is a very potent vasoconstrictor, but its function has not yet been investigated in the early stage of cardiovascular development. The purpose of the present study was to clarify whether endothelin-1 exerts a hemodynamic effect in stage 21 chick embryos. We measured vitelline artery blood pressure with a servo-null micropressure system and blood flow velocity at the dorsal aorta with a 20 MHz pulsed Doppler velocity meter. The vitelline vessels were directly measured with a microscope video system. While monitoring these parameters, endothelin-1 was infused into a vein by a microinjector and data were collected. Endothelin-1 increased the blood pressure and heart rate, but decreased the dorsal aortic blood flow. Only the vitelline veins with a diameter of between 100 and 200 microm constricted after endothelin infusion, but smaller or larger veins and the arteries did not show any significant change in size, although the resistant arteries could not be measured by this method. In conclusion, endothelin-1 has apparent constrictive effects in the selected vessel in the early stages of cardiovascular development when the endocrine and autonomic nervous systems have not yet developed.     

Mesonephric origin of the gonadal primitive medulla in chick embryos

The development of the gonadal primitive medulla in embryonic chick gonads was studied with the light microscope, using serial longitudinal sections from 72 h to 108 h of incubation. The sex of embryos was established from karyotypes. At 72 h, the germinal epithelium in the genital ridges was thickened. The nephrogenic cord was not differentiated into nephrons underneath, although the surrounding mesonephros displayed renal corpuscles and tubules. Clusters and trabeculae of mobilized mesonephric cells piled up under the germinal epithelium, forming the rudiment of the primitive medulla. From 78 h onwards, nephrotome-like structures existed in the mesenchyme underlying the germinal epithelium. Mesonephric cells became detached from their ventral walls and incorporated into the rudiment of the medulla. Finally, at 90 h, when the gonads were constituted, the primitive medulla was definitively formed without any contribution of the germinal epithelium. Adrenal cortical cells, also originating from the mesonephric blastema, showed tight relationships with the gonadal medullarian structures. Our observations support the concept of the mesonephric origin of the gonadal components having male potentialities in birds.     

Pathogenicity of K. ozaenae for mice and chick embryos

The authors tested the virulence of K. ozaenae--its old museum strains, the freshly isolated ones and those passaged on meat-peptone agar; experiments were carried out on mice and chick embryos. To mice the culture was administered intraperitoneally, subcutaneously, intranasally, and to embryos--into the allantoic cavity and on the chorioallantoic membrane. Irrespective of the method of administration, the freshly isolated strains were highly virulent both for mice and for chick embryos. The virulence of such strains decreased in the process of passaging on the nutrient medium. Old museum strains were of low virulence for albino mice and avirulent for chick embryos. In comparing the virulent and avirulent strains there were found no differences in the antigenic structure and toxicity of the Boiven complex, cytoplasm, membrane, capsular polysaccharide or whole virulent and avirulent bacteria killed by heating.     

Alteration of activities of hepatic antioxidant defence enzymes in developing chick embryos after glucocorticoid administration--a factor to produce some adverse effects?

Nickel is a strong biological sensitizer and consequently may induce a delayed hypersensitivity reaction (type IV immune response). Because nickel is a component of the majority of the orthodontic alloys, the objectives of this cross-sectional study were to determine the prevalence of nickel hypersensitivity reaction before, during, and after orthodontic therapy with conventional stainless steel brackets and wires; to evidence the induction of this reaction by the orthodontic appliances; and to characterize the nickel hypersensitive persons. Nickel patch tests and a questionnaire were used to evaluate the hypersensitivity to this metal. The total sample consisted of 170 patients, 105 females and 65 males, from the orthodontic department at Bauru Dental School, University of S?o Paulo. They were divided into three groups as follows: A (n = 60), patients before the beginning of orthodontic therapy; B (n = 66), patients currently undergoing orthodontic treatment, and C (n = 44), patients who had undergone orthodontic treatment previously. The chi-square test (chi2) showed an allergic reaction in 28.3% of the total sample with 23% female and 5.3% male. This indicated a gender difference (chi2 = 10.75, p < 0.001). There was a positive association between nickel hypersensitivity and previous personal allergic history to metals (chi2 = 34.88, p < 0.0001) as well as with the daily use of metal objects (chi2 = 11.95, p < 0.0005). There was no statistically significant difference in the prevalence of contact dermatitis among the three groups (chi2 = 0.39, p = 0.848). This suggests that orthodontic therapy with conventional stainless steel appliances does not initiate or aggravate a nickel hypersensitivity reaction.     

Erythroid carbonic anhydrases of developing chick embryos. Coordinate expression with primitive and definitive embryonic haemoglobins

Erythroid carbonic anhydrase activity of chick embryos from the 3rd day of incubation to the egg hatching has been determined. Three minor activity peaks at 3, 9 and 15 days of development and a major one at 19 days were found. The enzyme molecular forms were purified by affinity chromatography from haemolysates of embryos at several stages of development. As has been found for the adult erythrocytes, only type II isozyme was detected in the embryo red cells. Isoelectrofocusing analysis demonstrated that two different molecular forms of this isozyme are synthesized by the red cells of developing embryos. Only the early form is present up to 5 days of development; the late form, which is indistinguishable from the adult isozyme, appears in the haemolysate at 6-7 days and quickly replaces the early form. Analysis of purified primitive and definitive erythroid lines from 7-days-old embryos showed a compartmentalization of the early and late forms into the primitive and definitive erythroid cells, respectively.     

Analysis of heart development in cultured rat embryos

The long-range goal of this research is to establish an in vitro system that will permit pertubation of mammalian heart development and in situ examination of the cellular and molecular events underlying cardiac morphogenesis. Rat embryos at 9.5-11.5 days of gestation were placed in culture bottles containing rat serum and Tyrode's solution. Embryos cultured for 24 and 48 h were compared to age-matched in vivo controls for morphological score, morphometric analysis of heart development, and confocal and electron microscopic analysis of myofiber pattern formation. Morphological scores indicated that embryos cultured for 24 h from day 9.5 to 10.5 had essentially normal development when compared to age-matched embryos allowed to develop in vivo. Development of embryos maintained for 48 h in culture was slightly delayed at 66-68% of age matched in vivo embryos. Analysis of hearts from embryos allowed to develop 9.5-11.5 days in vivo plus 24 and 48 h in culture showed that the ventricular thickness and height, as well as the truncal, atrial and ventricular diameters were equivalent to those of hearts from age-matched in vivo controls. Hearts from embryos allowed to develop from 11.5-12.5 days in vitro and cultured for 24 and 48 h had smaller left ventricular and atrial dimensions than controls. Cardiac myofibrillogenesis and myofibrillar pattern formation in embryos cultured from 9.5 days of in vivo development for 48 h were also normal. These studies indicate that the rat whole embryo culture system is a useful model to study several critical periods in mammalian heart development.     

Regulation of nitrogen catabolic enzymes in chick liver -- effects of amino acids

It is well-known that in the chick, dietary protein increases the levels of several hepatic enzymes that are involved in nitrogen metabolism and excretion. However, the biochemical mechanism of this response is essentially unknown. The experiments presented in this paper show that the chick is responding to alpha-amino nitrogen and not to any specific amino acid. Furthermore, it is shown that this system responds to endogenous sources of nitrogen as well as dietary protein and that the xanthine dehydrogenase response involves regulation of enzyme synthesis without changing the rate of degradation.     

Net transfer and incorporation of yolk n-3 fatty acids into developing chick embryos

The effect of egg yolk fatty acid composition on the uptake and utilization of essential n-6 and n-3 fatty acids by the developing chick embryo was studied. Eggs were enriched with n-9, n-3, or n-6 fatty acids by incorporating sunflower seed high in oleic acid (C18:1 n-9), flax seed rich in linolenic acid (C18:3 n-3), or sunflower seed high in linoleic acid (C18:2 n-6) into the laying hen diets. Fertile eggs were collected and incubated. The fatty acid composition of eggs and newly hatched chicks were compared. Feeding diets containing flax seed increased (P < .05) total n-3 fatty to 528.4 mg compared with 53.9 and 39.3 mg for eggs from hens fed diets with high oleic acid or regular sunflower seed, respectively. Levels of C18:2 n-6 and monounsaturated fatty acids were higher in eggs from hens fed diets containing regular or high oleic acid sunflower seeds. Dietary fat did not influence the total lipid content of the egg yolk or total lipids of chick tissues. The fatty acid composition of the hatched progeny was significantly altered by egg yolk lipids. However, the percentage incorporation of essential n-6 and n-3 fatty acids into the progeny increased when yolk sources of these fatty acids were low. The developing chick embryo appeared to preferentially take up docosahexaenoic acid and arachidonic acid from the yolk lipids. Evidence also suggests that conversion of C18:2 n-6 and C18:2 n-3 to longer chain n-3 or n-6 fatty acids occurs during the incubation period.