Changing activation sequence in the embryonic chick heart. Implications for the development of the His-Purkinje system

Viruses that establish persistent infections in their host, such as herpesviruses, adenoviruses or HIV, express proteins designed to pre-empt or evade recognition and elimination by MHC class I restricted CD8+ T lymphocytes. Notable discoveries during the annual period of review have demonstrated that, in principle, each single step within the MHC class I pathway of antigen processing and presentation is fair game for manipulation by viral functions. The viral factors that are natural inhibitors of this pathway have been instrumental for the elucidation of the distinct molecular mechanisms that are exploited by viruses. The viral stealth strategies that downregulate MHC class I protein surface expression may lead, however, to a higher susceptibility of virus-infected cells to natural killer cell activity. Strikingly, there is evidence that some viruses counteract increased natural killer cell recognition by expressing viral MHC class I homologues that function as surrogate inhibitors of natural killer cell activity.     

The effect of hyperoxia on embryonic and organ mass in the developing chick embryo

OBJECTIVES: We investigated the sensitivity and specificity of exercise-induced T wave normalization (TWN) in infarct-related electrocardiographic leads (IRLs) for detection of residual viability in the infarct area. BACKGROUND: The meaning of exercise-induced TWN on IRLs is not yet well understood. Recent reports suggest that TWN during dobutamine echocardiography could indicate the presence of viable myocardium. METHODS: We evaluated 40 consecutive patients with a recent acute myocardial infarction and negative T waves in at least two IRLs. All patients underwent exercise testing; positron emission tomography (PET) with nitrogen-13 ammonia and fluorine-18 fluorodeoxyglucose; and coronary angiography. RESULTS: Twenty-four patients showed exercise-induced TWN: 18 at a work load < or =50 W (group la) and 6 at a work load > or =75 W (group 1b); 16 patients did not show TWN (group 2). On the PET study, viability in the infarct area was present in 17 patients (94%) from group la, in only 1 (16%) from group 1b and in 4 (25%) from group 2 (p < 0.0001). The sensitivity, specificity and diagnostic accuracy of exercise-induced TWN, in comparison with residual viability, were, respectively, 82%, 67%, 75% for TWN at every work load and 77%, 94%, 85% for TWN at a work load < or =50 W. Moreover, the sensitivity and diagnostic accuracy of TWN at the low work load were higher for anterior infarctions (87% and 88%, respectively). CONCLUSIONS: Exercise-induced TWN on IRLs at low work loads is a sensitive and specific index for the presence of residual viability in the infarct area. Sensitivity and diagnostic accuracy of this sign are higher for anterior infarctions.     

Phospholipid distribution and fatty acid composition in different brain regions during chick embryo development

The phospholipid profile of different chick embryo brain regions was studied from 11 to 21 days of development, revealing interesting changes in content and distribution. Total phospholipid phosphorus (P), in micrograms of P per microgram of DNA, increases significantly during development of cerebral hemispheres (CHs), optic lobes (OLs), and brainstem (BS). Compared with CH and OL, the BS shows at all stages a significantly higher concentration of phospholipid P, which in contrast decreases in the cerebellum (CB) during development. Moreover, the data show interesting differences between the right and the left portion of the brain. The distribution of phospholipid P and the fatty acid composition of phospholipids were asymmetric between left and right OL and CH, as were the concentrations of DNA and cholesterol, demonstrating lateralized neurochemical development in these structures, i.e., left OL, right OL, left CH, and right CH. The data are discussed also in relation to the potential importance of neurochemical lateralization for determining lateralized embryonic and postnatal behavior of this species.     

Ontogeny of behavioral responsiveness to sound in the chick embryo as indicated by electrical recordings of motility.

Gathered normative behavioral data regarding the ontogeny of responsiveness to sound in the chicken embryo. As a prerequisite, a sensitive and accurate method for recording embryonic motility was developed (Exp I). By means of platinum electrodes inserted just beneath the shell membrane, potentials resulting from heartbeat and movement of 300 White Leghorn embryos were recorded on a polygraph. The technique was found to be effective when applied to chick embryos 6 days and older. Correlations between visual observations of activity and the records produced by the electronic technique substantiated its accuracy. Behavioral responses of 300 chick embryos (Stages 39–43) to acoustic stimulation (Exp II) were then recorded. High-intensity (115-db) tones of 400, 700, and 1,400 Hz were used as stimuli. The earliest consistent responses were recorded from Stage 40 (Days 14–25) Ss; the 700 and 1,400 Hz tones produced statistically reliable inhibition of movement during the stimulus period compared with the post-stimulus period. Reliable increases in movement during the stimulus period were first recorded at Stage 42 (Days 16–27) in response to 700 and 1,400 Hz and at Stage 43 (Days 17–28) in response to 400 Hz. (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Changes in the content of progesterone receptor isoforms and estrogen receptor alpha in the chick brain during embryonic development

Progesterone and estradiol participate in the regulation of several reproductive functions through interaction with intracellular progesterone receptors (PR) and estrogen receptors (ER), respectively. In this work, we determined PR and ER-alpha isoforms content in the brain of chicks of both sexes on days 8 and 13 of embryonic development as well as on the day of hatching by Western blot analysis. PR isoforms protein content increased during embryonic development in both female and male chick brain. The highest PR isoforms content was observed on the day of hatching in both sexes. Interestingly, PR-A content was higher in the brain of chick males than in that of females on day 8 of embryonic development. PR-A/PR-B ratio was higher in the brain of males than in that of females at all ages. We found two ER-alpha isoforms of 66 and 52 kDa; the content of both isoforms was higher in the brain of females than in that of males on days 8 and 13 of embryonic development. An opposite pattern of ER-alpha isoforms content was observed. In males, ER-alpha content increased during embryonic development whereas in the females it decreased during this process. These results indicate that the content of PR and ER-alpha isoforms is related to the degree of brain development in chicks, and suggest that PR and ER-alpha isoforms should exhibit sexual dimorphism in the brain of chicks during embryonic development.     

Immunohistochemical localization of netrin-1 in the embryonic chick nervous system

Netrin-1 has profound in vitro effects on the growth properties of vertebrate embryonic axons. In addition, netrin-1 mRNA is found in the floor plate of the embryonic nervous system, an intermediate target of many axons, including commissural axons that are affected by netrin-1 in vitro. Moreover, genetic studies of netrin-1 homologs in Caenorhabditis elegans and Drosophila implicate these proteins in commissure formation. We raised polyclonal antisera that recognize chick netrin-1 in fixed tissue sections. The antisera were used to immunohistochemically map netrin-1 in the embryonic spinal cord, brain, and retina. The relationship between netrin-1 localization and the growth of pioneering axons suggests roles for netrin-1 in the regulation of circumferential, commissural, and longitudinal axon growth in the spinal cord and brain. The data also suggest that the primary or sole effect of netrin-1 on pioneering spinal cord commissural axons is haptotactic. Furthermore, the pattern of netrin-1 localization raises the possibility that this protein helps mediate neuronal migration in the spinal cord, brain, and retina.     

Effects of stimulation on embryonic activity in the chick.

Studied the effects of stimulation on the stereotyped and coordinated movements in the chick (Rhode Island Red/Light Sussex hybrids) embryo using the type of stimulation (regular loud clicks) known to accelerate development and the time of hatching. The number of coordinated movements, the amount and approximate size of all activity, heart rates and, in 20-day embryos, respiration rates were assessed during 15-min control, stimulation, and no stimulation periods. Results show an increase in the number of coordinated movements, but not their size, and some changes in the heart and respiration rates after the onset of stimulation. Effects occurred mostly after several minutes' delay. It is suggested that this delay may be connected with the reciprocal relationship between the coordinated movements and random motility in that the former may be triggered more readily at times when the latter are suppressed. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of endometrial factors in regulating secretion of components of the immunoreactive human embryonic interleukin-1 system during embryonic development

In the study reported here, we localized at the protein level the major components of the interleukin (IL)-1 system in the human embryo, and we investigated the endometrial factors influencing their secretion during embryonic development. To localize these components, we performed immunohistochemical experiments in 44 oocytes and 78 embryos. The following primary antibodies were used: monoclonal mouse anti-human IL-1 receptor type I (IL-1R tl), monoclonal mouse anti-human IL-1 beta, and polyclonal rabbit anti-human IL-1 receptor antagonist (IL-1ra). For embryo culture, human embryos at different developmental stages were cultured in 100-microliters drops of Ham's F-10 medium + 4 mg/ml BSA (n = 33), in 100-microliters drops of Menezo B2 culture medium (n = 18), or in wells with 1 ml of Menezo B2 culture medium (n = 8). For embryo coculture, endometrial stromal cells (ESC) and endometrial epithelial cells (EEC) were isolated from human secretory endometrium and cultured until confluence in 75% Dulbecco's Modified Eagle's Medium and 25% MCDB-105 containing antibiotics and supplemented with 10% charcoal-Dextran-treated fetal bovine serum. Individual human embryos were cocultured with experimental EEC and ESC (n = 23 and n = 4, respectively) for 5 days in 600-microliters drops of Menezo B2 medium, and conditioned medium was removed every 24 h. Human embryos were also cultured with EEC-conditioned medium (n = 9). IL-1 alpha, IL-1 beta, and IL-1ra levels were determined by ELISA in the 24-h culture- or coculture-conditioned media. Immunostaining confirmed the presence of IL-1 beta, IL-1ra, and IL-1R tl in oocytes and embryos in all stages analyzed, with no statistical differences. IL-1 alpha, IL-1 beta, and IL-1ra were absent in conditioned media of cultured embryos and embryos cocultured with ESC. However, when human embryos were cocultured with EEC or with EEC-conditioned medium alone, two different populations of embryos were observed: IL-1 producers (57% and 56%) and IL-1 nonproducers (43% and 44%, respectively). Finally, the IL-1 profile of a single human embryo cocultured with maternal EEC which successfully implanted and developed is presented, this pattern being similar to that described in the IL-1 producer population. These results demonstrate the presence of the IL-1 system in the human embryo. However, the selective release of IL-1 only when embryos were cocultured with EEC or EEC-conditioned medium indicates an obligatory role of the endometrium in the regulation of the embryonic IL-1 system. Furthermore, the differential embryonic production of IL-1 may be related to the implantation capability of the embryos.     

Distribution of desmin and fibronectin in chick embryo gonad during testicular cord formation

In order to compare PCR with rapid virus culture for the early detection of CMV in bronchoalveolar lavage (BAL) after bone marrow transplantation, 26 asymptomatic patients were routinely evaluated for the presence of CMV on day 35 using these two techniques. Concurrent blood samples were also analyzed in all cases. CMV was detected synchronously by both culture and PCR in six of 26 (23%) BAL and in five of 26 (19%) blood specimens. Among these positive specimens, three BAL and blood samples were positive in the same patients. Five (19%) BAL and five (19%) blood samples were culture-negative but PCR-positive. No BAL or blood specimens were positive by culture alone. When considering matched BAL-blood samples, five were positive in only one fluid, BAL (n = 3) or blood (n = 2) using culture, while seven were positive in only one fluid, BAL (n = 4) or blood (in = 3) using PCR. Overall, six of 26 (23%) patients had culture-negative but PCR-positive results. Three of these six patients were positive only in BAL and two of them subsequently received antiviral therapy for development of symptoms suggestive of CMV infection. We suggest that asymptomatic patients with negative-culture but PCR-positive results on day 35 in BAL should be subsequently closely monitored for the presence of CMV.     

Programmed cell death during the earliest stages of spinal cord development in the chick embryo: a possible means of early phenotypic selection

The spatiotemporal distribution of cell death in the chick embryo neural tube and spinal cord (brachial region) was examined between stage (St.) 12 and 22, in plastic semithin sections. Between St. 12 and 16, the total number of pycnotic cells per segment was low, whereas after St. 16 the number of pycnotic cells was substantially increased. Between St. 17 and 19 three cell death foci or regions could be recognized. One region, the dorsal pycnotic zone, was located in the most dorsal part of the spinal cord, including the neural crest, with the highest number of pycnotic cells observed at St. 18. The second region, or ventral pycnotic zone, was located between motoneurons and the floor plate and had the highest number of dying cells at St. 17. The third region, the floor plate pycnotic zone, was located in the midportion of the floor plate and had the greatest amount of cell death at St. 19. Although low numbers of pycnotic cells were also observed in other regions between St. 17 and 19, no pycnotic cells were found in the ventrolateral region that gives rise to motoneurons. Ultrastructural observations as well as data from in situ nick end labeling indicate that the pycnotic cells observed in the neural tube die by apoptosis and that the debris from the dead cells is phagocytized primarily by adjacent healthy neuroepithelial cells. Although the spatiotemporal distribution of pycnotic cells suggests that cell death at these early stages could play a role in establishing the pioneer axonal pathway for spinal commissural neurons, preliminary observations following perturbations of cell death do not support this notion. Alternatively, early cell death may be involved in the regulation of cellular patterning along the dorsoventral axis of the neural tube by a kind of negative selection of specific progenitor cells.     

Intercellular adhesive selectivity. I. An improved assay for the measurement of embryonic chick intercellular adhesion (liver and other tissues)

An improved assay for measuring intercellular adhesive selectivity of embryonic chick liver cells is described. Three major improvements over earlier procedures are noted: (a) enhanced reproducibility of liver cell-liver cell aggregate adhesion (homotypic adhesion) was achieved; (b) 25-70% of the input cells adhered to the collecting aggregates during the course of routine experiments as compared to the 0.25% in earlier assays. This increase in cellular adhesion suggests that the observed cell pick-up is a characteristic of the majority of the dissociated liver cell population; (c) the rate of intercellular adhesion was increased 1,000-fold. The main feature of the assay is that it measures the tissue adhesive selectivities of the dissociated cell population. Studies were undertaken on three embryonic chick tissues (liver, neural retina, and mesencephalon) to determine the tissue selectivity of intercellular adhesion of these dissociated cell types. Some general properties of liver cell homotypic adhesion have been studied and are reported.     

Factors in the motor behavior of functional psychotics.

The author presents a continuation of a research project (see 32: 1873) which suggested that reactive inhibition developed to a greater extent in schizophrenics than normals. The initial task (depressing a key in response to the appearance of a light on a panel) was altered to permit the possibility of quicker response rates, and a group of depressives was added for comparison. The results of the follow-up study are shown to continue to support the theory re: reactive inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Heart rate during development in the turtle embryo: effect of temperature

Growth and development can occur over a wide range of physical conditions in reptiles. Cardiovascular function must be critical to this ability. However, information on cardiovascular function in developing reptiles is lacking. Previous work indicated that in reptiles the effects of temperature on growth and metabolism are largely restricted to early development. This study examined whether the previously observed effects of temperature and different perinatal patterns of metabolism observed in amniotic vertebrates are correlated with cardiovascular function. Embryonic and hatchling carcass mass, heart mass and heart rate (HR) were compared for snapping turtle eggs (Chelydra serpentina) incubated at 24 degrees and 29 degrees C. Incubation time was shorter at 29 degrees C (56.2 days) than at 24 degrees C (71.1 days). Carcass and heart growth showed a sigmoidal pattern at both temperatures. However, cardiac growth showed a relative decrease as incubation proceeded. Incubation temperature significantly affected the HR pattern during development. The HR of embryos incubated at 24 degrees C was constant for most of incubation (51.8 +/- 4.8 min-1). A small decrease was observed just prior to and a large decrease immediately following hatching (posthatch, 22.3 +/- 4.1 min-1). At 29 degrees C embryonic HR was greater than at 24 degrees C early in development (72.3 +/- 3 min-1). The HR steadily decreased to values equivalent to those at 24 degrees C. The HRs of 24 degrees C and 29 degrees C hatchlings were not different. Cardiac output (estimated as the product of heart mass and HR) increased rapidly during early development and then slowed dramatically at both temperatures. These data are consistent with the suggestion that temperature exerts its effects primarily early in development. Furthermore, the changes in cardiovascular function are correlated with metabolic changes in hatching vertebrates.     

Nigrostriatally induced motor reactions in the rat. I. Rotational behavior and posture asymetry after intracerebral injection of apomorphine and dopamine

Using a rotameter described by Ungrstedt, the influence of pretreatment with 6-hydroxy-dopamine and transections of the Capsula interna on the asymmetry of the animal's poise and movement following systemic and intracerebral administration of dopamine and apomorphine was studied. After lesion of the nigrostriatal tract, i.p. administered apomorphine caused the animals to rotate towards the damaged side. After injection of apomorphine in the Nucleus caudatoputamen of healthy animals, initial rotations towards the injection side with subsequent opposite rotation were observed, whereas dopamine injected into the Nucleus caudatoputamen and the Substantia nigra initiated rotations in contralateral direction only. Pretreatment with haloperidole nullified the effect of apomorphine. The results have proved the effectiveness both in the Nucleus caudatoputamen and the Substantia nigra of drugs stimulating the dopamine receptors. With intact rats, the two sides of the nigrostriatal system are functionally asymmetric, which is reflected by the quantitative differences of responses following stimulation of dopamine-sensitive receptors and the individually different preference of one rotational direction. These individual behavioural patterns are modified by experimental influences.     

Kinetic constants of alpha-methyl-D-glucoside transport in the chick small intestine during perinatal development

BACKGROUND: Experimental evidence suggests that neutralizing antibodies could constitute an important factor in the control of AIDS progression and that the V3 loop of gp120 constitutes the main target for such purposes. We have previously developed two neutralizing murine monoclonal antibodies (Mabs) against the V3 region of the HIV-1 MN strain. OBJECTIVES: To characterize those Mabs in terms of fine specificity and DNA sequence of their V regions and to study if Fab fragments retain their neutralizing potential in vitro. STUDY DESIGN: A set of 12-mer alanine substituted peptides were employed for epitope mapping using two ELISA procedures: (1) indirect, with each peptide bound to polystyrene plates, and (2) competitive, with co-incubation of peptides and Mabs in solution. The V regions of both Mabs were PCR amplified from cDNA and their nucleotide sequences were determined. Finally, Fab fragments of Mab 10F10 were generated and their neutralizing capacity against the MN isolated was assessed. RESULTS: We first restricted the minimal length of the epitopes recognized by 2C4 and 10F10 to the 12-mer peptide KRIHIGPGRAFY. The core of the epitopes recognized by Mabs 2C4 and 10F10 were IHIGP-R and IHIG-R, respectively. While substitution of proline in position 7 completely abolished the binding of 2C4, it only reduced that of 10F10 by 50%. Finally, Fab fragments of Mab 10F10 were still able to neutralize the HIV-1 MN strain in vitro. CONCLUSION: This subtle distinction in the fine mapping of the epitope recognized by Mabs 2C4 and 10F10 should correspond to three amino acid differences that we found in the heavy chain V-regions. The Fab fragments of Mab 10F10 retained the neutralizing capacity. This indicates that HIV neutralization by anti V3 Mabs is an Fc independent process.     

Neurons of the Drosophila giant fiber system: I. Dorsal longitudinal motor neurons

About 98% of the DNA sequence of the lymphotropic Aleutian disease parvovirus isolate ADV-SL3 was determined and analysed. The sequence revealed that this isolate was a type-1 ADV strain, supporting that the currently used typing of ADV viruses does not correlate with virulence or pathogenicity. ADV-SL3 had a very high overall homology of 99.5% to the prototype strain ADV-G at the DNA level. Comparative sequence analyses with various ADV isolates of known virulence did not reveal a consensus sequence that could obviously be responsible for the apparently unique biological properties of this virus strain.