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Comparative disposition, receptor affinity, and teratogenic activity of sulfon arotinoids.

To investigate the relationship between sulfon arotinoid biotransformation and teratogenic activity, the potency of the ethyl (Ro 15-1570) and methyl (Ro 14-9706) arotinoid sulfones and their in vivo disposition in pregnant hamsters were studied. Administration of Ro 15-1570 was teratogenic, but Ro 14-9706 showed no such activity. Total absorbed doses of the ethyl and methyl sulfones (measured as maternal plasma AUC) were very similar. Total delivered dose of Ro 14-9706 to liver and lung was 120-160% that of Ro 15-157, and Ro 14-9706 was transferred in greater amounts to the embryo as well. Placenta AUC for parent sulfon arotinoids was 160-250% that in the embryo. Plasma analyses by HPLC suggested that the ethyl sulfone was oxidized and appeared in maternal plasma as the corresponding sulfinic (Ro 14-9572) and sulfonic (Ro 14-3899) acids, amounting to 10% and 16%, respectively, of the mean maternal ethyl sulfone Cmax value. The concentrations of sulfinic and sulfonic metabolites were always less than the analytical limit of detection in placenta and embryo after maternal ethyl sulfone intubation. Neither the sulfinic nor the sulfonic acid were ever detected in maternal circulation, placenta, or embryo after methyl sulfone intubation. Comparisons of their binding affinities found that neither the ethyl nor the methyl arotinoid sulfone could act as a ligand for cellular retinoic acid-binding protein (CRABP), nor could these compounds bind retinoid nuclear receptors (RAR). Transcriptional activation of RARs was weak and similar for both compounds. The sulfinic and sulfonic acid arotinoids bind and transactivate RARs, and bind CRABP with efficiencies similar to all-trans-retinoic acid. Furthermore, they are active in cultured limb bud chondrocytes. The results suggest that the methyl sulfone (in accord with its lack of activity in cultured limb bud chondrocytes) is of no toxicologic significance in hamster embryo--even after relatively high delivered dose. Teratogenicity of the ethyl sulfone (which shows marked inhibition of chondrogenesis in cultured limb bud) does not appear to depend on measurable concentrations of these sulfinic/sulfonic acid metabolites in the hamster embryo.

Abnormalities, Drug-Induced↗

[Origin of the hepatic artery in the embryo and fetus].

Study of the hepatic artery in 52 human foetuses and 4 embryos. The authors compare their findings to those published on adults. They underline the higher frequency of the hepatic artery arising out of the left gastric artery (67%) in foetuses and embryos, either associated to the common hepatic artery only (55,4%) or to both the common hepatic artery and the right hepatic artery (12,5%). Graphic reconstruction of foetal hepatic arteries shows two important lines of force one coming from the coeliac trunk - the future common hepatic artery, the other arising from the left gastric artery - the future left hepatic artery. At the 19th stage according to Streeter, the definitive disposition is attained.

Female↗

The second EF-hand is responsible for the isoform-specific sorting of myosin essential light chain.

It has been known that isoforms of myosin essential light chain (LC) exhibit the isoform-specific sorting within cardiac myocytes and fibroblasts. In order to analyze which domain of LC is responsible for the sorting, various chimeric cDNA constructs between human nonmuscle isoform (LC3nm) and chicken fast skeletal muscle isoform (LC3f) were generated and expressed in cultured chicken cardiac myocytes. If chimeras contained LC3f sequence at the place that was restricted by BssHII and PstI, they were preferentially sorted to sarcomeres and precisely localized at A-bands, and their incorporation levels into the A-bands were identical with that of the wild type LC3f. However, other chimeras were distributed throughout the cytoplasm like the wild type LC3nm. Comparison of amino acid sequences revealed that 12 amino acids are different between chicken LC3f and human LC3nm in the BssHII-PstI fragment, and these amino acids are located within the second EF-hand of LC. These results indicated that the second EF-hand is responsible for the isoform-specific sorting of LC. Although the second EF-hand is not included in the key contacts with myosin heavy chain, it is supposed that this domain is important for the relative disposition of neighboring domains. Thus, the 12 amino acids in the second EF-hand might play a key role for modulation of overall configuration of LC, thereby influencing the precise association of the key contacts.

Amino Acid Sequence↗

Differential aldehyde sensitivity of newly replicated chromatin from Drosophila melanogaster embryos.

By using a series of formalin concentrations we have found that high aldehyde levels in the fixation buffer of Miller spreads are correlated with the appearance of nonnucleosomal stretches in newly replicated chromatin of embryos from Drosophila melanogaster. These nucleosome-free gaps are found 0-500 nm behind the replication fork and do not correspond to naked DNA. The analysis of the distribution of nucleosome-free gaps on newly replicated DNA has revealed some structural details about the maturation of nucleosomes and provides direct evidence that parental nucleosomes have an altered structure at the replication fork. Finally, these stretches of nonnucleosomal chromatin are located in a trans disposition inside the active replicon, although there exists a considerable variability.

Animals↗

Disposition of 14C-nicotine in the fertilized chick egg.

14C-Nicotine-HCl (4.5 mg) was injected into the air space of chick eggs after one day of incubation and the distribution of radioactivity measured on days 3, 5, 7 and 12. By day 3, 98% of the dose had passed from the air space into the egg, proper. The quantity of nicotine in the yolk was highest on day 3 (74% of dose) and decreased steadily until day 12 (52%). The quantity in the albumen increased from 16% on day 3 to a maximum on day 7 and remained constant at 34% until day 12. The embryo contained 0.03% of the nicotine on day 3, and this level increased to 5% by day 12. Nicotine in the allantois increased throughout the study period (0.01% on day 3 to 3% on day 12). Although only 5% of the dose was present in the embryo, the highest concentrations within these components of the embryo ranged from a minimum of 0.85 microng nicotine/mg dry wt in the heart to a maximum of 2.00 microng nicotine/mg dry wt in the carcass. These levels within the embryo were two to five times higher than the greatest concentrations in the yolk and albumen. The dynamics of nicotine passage from the air space into other components of the fertilized chick egg were clarified. Whereas the conventional expression of teratogenic doses of drugs in chick eggs (i.e., ppm of egg weight) assumes that the compound is distributed uniformly, this study indicates that such expressions are inaccurate.

Animals↗

Notes on the pathogenesis of enterovirus infections. Observations, experiments, and speculations.

Despite extensive investigations over the last decades, several aspects of the pathogenesis of enterovirus infections in humans and animals are only poorly understood, such as the molecular basis of virulence (in particular of neurovirulence), tissue tropisms (e.g. the precise site of initial virus replication in the human intestinal tract), and precipitating factors of paralytic disease ("disposition"). Studies on poliovirus myocarditis in man are reviewed. Unequivocal evidence on replication of poliovirus type 2 (strains MEF1 and Lansing) in newborn and suckling mice and on poliovirus myocarditis is presented. Our observations strengthen the thesis of similar pathogenic potentials of the enterovirus group.

Animals↗

Development of the hip joint in relation to congenital dislocation.

As an introduction to the pathology and treatment of C.D.H., a simplified outline of fundamental embryologic events and growth characteristics of the hip joint (selected from past and actual bibliography) is presented. Congenital dislocation of the hip appears to be the result of various genetic, developmental, environmental and mechanical factors that affect articular structures in the perinatal period. At this time, the hip joint is anatomically and functionally more vulnerable to alterations of its normal concentric disposition. If incongruency persists, subsequent morphological changes, characteristic of dysplasia will develop. The main conclusions derived from a review of the development of the hip joint in relation to C.D.H. are: 1) The hip joint is an anatomical and functional unit derived from a common primitive blastema. 2) Primitive condensed sclerotomic mesenchyme transforms into cartilage that shapes in a genetically determined pattern to form the femur and os innominatum in continuity. 3) The joint space develops by autolytic degeneration in the 7-8 week embryo. By the 11th week, the joint cavity, evolved in the capsule lined internally by synovium, has a well differentiated labrum and ligamentum teres with the basic morphology of a developed hip joint. Only after this stage is displacement possible. 4) Depth (and stability) of the acetabulum increase with development of the glenoid labrum and cartilaginous rim (incomplete only in its inferior portion). Here a fibrous band (transverse ligament) offers less resistance to displacement, but on occasions is an anatomic barrier to concentric reduction. 5) In the early fetal period, the acetabulum is a deep set cavity, becoming shallower at the time of birth. Femoral head coverage at birth is more deficient than at any other previous or subsequent stage of development. 6) The relationship between femoral and acetabular anteversion (instability index) is more important than absolute values which are variable during intrauterine life. The degree of femoral anteversion depends on teh rotational attitude and muscular action of the extremity.(ABSTRACT TRUNCATED AT 400 WORDS)

Hip Dislocation, Congenital↗

Development of the excitation-contraction coupling apparatus in skeletal muscle: association of sarcoplasmic reticulum and transverse tubules with myofibrils.

The formation and maintenance of the highly regular organization of membrane systems and proteins in striated muscle require specific membrane-membrane and membrane-cytoskeleton interactions. The development of T-tubules and sarcoplasmic reticulum (SR) was followed in gastrocnemius muscle fibers from chicken embryos between 12 days (E12) and 21 days (E21) of incubation, with particular attention to their relationship with one another and with the myofibrils. The fluorescent lipid analog DiIC16[3] was used to label either the external membranes (plasmalemma and transverse (T)-tubules) or the internal SR in living and fixed muscle. Short membrane invaginations can first be seen in fibers at E14, and at E15 longitudinal T-tubules appear in the periphery of the fibers. A complex network of T-tubules filling the whole fiber diameter develops suddenly at E16. In contrast, SR is abundant at the earliest observed stage (E12) and forms regularly spaced cross striations located at the I-Z-I bands. These correspond to a specific accumulation of smooth membranes around the Z-discs seen in electron micrographs. While SR is specifically associated with the newly formed myofibrils in the periphery of the fibers, the disposition of early T-tubules shows little specific relationship to either SR or the myofibrils. However, electron microscopy shows that junctions between T-tubules and SR are formed during this period (Takekura and Franzini-Armstrong, submitted for publication). Junctions do not acquire a specific relation to the myofibrils until around hatching when triads begin to reorganize into their mature location, the A-I junction. These findings indicate three key events in the organization of T-tubules and SR in the sarcomeres: (1) early SR/Z-line interactions independent of T-tubules; (2) SR/T-tubule interactions to form the triad junctions, independent from the myofibrils; and (3) the late association of the junctional complexes with the myofibrils at the A-I border.

Animals↗

Bis(2-methoxyethyl) ether: metabolism and embryonic disposition of a developmental toxicant in the pregnant CD-1 mouse.

An embryotoxic oral dose of bis(2-methoxyethyl) ether (DGDME), 3.73 mmol/kg body wt (500 mg/kg), administered on the 11th day of gestation to pregnant CD-1 mice was metabolized predominantly by O-demethylation to 2-(2-methoxyethoxy)ethanol with subsequent oxidation to (2-methoxyethoxy)acetic acid. Urinary excretion of this metabolite over 48 hr amounted to 63 +/- 2% of the dose. A smaller percentage of the administered dose was metabolized at the central ether linkage to produce 2-methoxyethanol, which was further metabolized by alcohol dehydrogenase to methoxyacetic acid. Urinary excretion of methoxyacetic acid, a potent developmental toxicant, amounted to 28 +/- 1% of the administered dose by 48 hr and was the second most prominent urinary metabolite. Unchanged DGDME and methoxyacetic acid were detected in the embryonic tissues from these animals, and embryos harvested after the initial 6-hr period showed detectable amounts of only methoxyacetic acid. The average amount of methoxyacetic acid per embryo was calculated to be 1.5 +/- 1.0 mumol (5.9 mmol/kg body wt) at the 6-hr termination time. This finding suggests that the reported teratogenic effects of DGDME are due to methoxyacetic acid formed, either in the fetus or by hepatic metabolism in the dam with subsequent distribution to the embryonic tissue. These results suggest that such developmental toxicity may occur with structurally similar aprotic ethylene glycol ethers in which metabolic O-dearylation would yield 2-methoxy-ethanol.

Animals↗

Effects of elevated intracellular calcium levels on the cytoskeleton and tau in cultured human cortical neurons.

Considerable evidence suggests that altered neuronal calcium homeostasis plays a role in the neuronal degeneration that occurs in an array of neurological disorders. A reduction in microtubules, the accumulation of 8-15 nm straight filaments, and altered antigenicity toward antibodies to the microtubule-associated protein tau and ubiquitin, as well as granulovacuolar degeneration, are observed in many human neurodegenerative disorders. Progress toward understanding how and why human neurons degenerate has been hindered by the inability to examine living human neurons under controlled conditions. We used cultured human fetal cerebral cortical neurons to examine ultrastructural and antigenic changes resulting from elevations in intracellular calcium levels. Elevation of intracellular calcium by exposure to a calcium ionophore or a reduced level of extracellular Na+ for periods of hours to days caused a loss of microtubules, an increase in 8-15 nm straight filaments, and increased immunostaining with Alz-50 and 5E2 (tau antibodies) and ubiquitin antibodies. Granulovacuolar degeneration was also observed. Antigenic changes in tau were sensitive to phosphatases, and the electrophoretic mobility of tau was altered in cells exposed to calcium ionophore, indicating that tau was excessively phosphorylated as the result of elevated intracellular calcium levels. Colchicine also caused an accumulation of straight filaments and altered tau immunoreactivity, suggesting that a disruption of microtubules secondary to altered calcium homeostasis may be a key event leading to altered tau disposition and neuronal degeneration. These data demonstrate that aberrant rises in intraneuronal calcium levels can result in changes in the neuronal cytoskeleton similar to those seen in neurodegenerative disorders, and suggest that this experimental system will be useful in furthering our understanding of the cellular and molecular mechanisms of human neurological disorders.

Antibodies↗

[Contribution to the development of the union between the manubrium of the malleus and the tympanic membrane in human fetus].

The development of the union between the manubrium of the malleus and the tympanic membrane was studied in human embryo. For that purpose 25 temporal bones of human foetus, aged from 36 days (14 mm) to 29 weeks (270 mm) were analyzed. Samples were fixed in a 10% formaldehyde solution, decalcified with 2% nitric acid, embedded in Paraplast, cut in sections of 7 microns thick and stained with Martin's trichrome method. During the development a pseudojoint between the malleus and the tympanic membrane several stages were seen. In the first stage, the manubrium was adhered to membrane mesenchyme of primitive tympanum, in the second one this mesenchyme was loose and there appeared capillars in it, in the third one there were collagen fibers in a radial disposition, and in the forth stage, the hollow in the meatal plug gave independence to the tympanic membrane for the external acoustic meatus. The distal portion of the manubrium, included in tympanic membrane, has remained with a cartilaginous structure during end of the time it has been studied by us. The collagen fibers at the level of the umbo surround the manubrium, while the rest of it remains in its anterior edge.

Humans↗

[Regularities in the distribution of sweat glands and the principles of their grouping in man].

Under study were skin pieces from 80 regions of the body of 41 human fetuses and embryos, 5 corpses of newborns and 43 corpses of people of different age. Series of paraffin sections stained by conventional methods as well as total preparations and thick sections stained with methylene blue were examined. The laying of eccrine and apocrine sweat glands in the skin covered or not with hair was shown to occur repeatedly. Basing on the succession of their appearance they are called the glands of the first, second and third generations. The principle of grouping of eccrine sweat glands is shown both in the composition of glandular-hair complexes and in the groups independent of hair. The author proposes using of letter and figure symbols to signify variations of their disposition in formulars. The appocrine sweat glands are also laid repeatedly in the sites of their typical localization.

Age Factors↗

A physiologically based kinetic model of rat and mouse gestation: disposition of a weak acid.

A physiologically based toxicokinetic model of gestation in the rat and mouse has been developed. The model is superimposed on the normal growth curve for nonpregnant females. It describes the entire gestation period including the period of organogenesis. The model consists of uterus, mammary tissue, maternal fat, kidney, liver, other well-perfused maternal tissues, and other poorly perfused maternal tissues, embryo/fetal tissues, and yolk sac and chorioallantoic placentas. It takes into account the growth of maternal tissues such as uterus, mammary glands, fat, and liver during pregnancy, as well as growth of the conceptus. The gestation model is based on published values of organ volumes and blood flows for the rat throughout pregnancy. It is scaled to the mouse using conventional scaling procedures. Its descriptive utility has been examined with the test chemical 5,5'-dimethyloxazolidine-2,4-dione (DMO), a weak acid that is not bound measurably in plasma or tissues and is eliminated by excretion in the urine. Concentrations of DMO were monitored in maternal rat and embryo plasma and in homogenates of maternal rat muscle and whole embryo after ip administration at 9:00 AM on Day 13 of gestation. On the basis that distribution of DMO is determined solely by its pK and the pH's of body fluids, pH and excretion rate values were estimated by visual optimization of model predictions to the concentration profile. Successful prediction of concentrations of DMO in the same tissues of pregnant mice after its ip administration at 9:00 AM on Day 10 or 11 of gestation required only adjustment for pH's of mouse body fluids.

Animals↗

Expression of alpha-smooth muscle actin in the stromal cells of bone marrow in fetuses in different stages of development, in multiple myeloma and monoclonal gammopathy of unknown significance.

Several disorders are associated with a monoclonal immunoglobulin detected by serum or urine electrophoresis, the most common being a monoclonal gammopathy of unknown significance, multiple myeloma, Waldenstrom's macroglobulinemia, and amyloidosis. Plasma cells, the immunoglobulin secretory cells of the immune system, are normal constituents of bone marrow (BM). Plasma cells are seen in small numbers in the stroma, surrounding blood vessels in the marrow. Their perivascular disposition is consistent with their secreting capacity. The hematopoietic microenvironment has a crucial role homing and regulating precursor cell growth both in physiologic and pathologic conditions. Cellular components such as branched adventitial reticular cells, macrophages, endothelial cells and fat cells constitute the supporting framework (stroma) for hematopoiesis, which takes place in the extravascular compartment. The presence of myiod cells (MCs) in human bone marrow has been observed during hematopoiesis in embryonic life, whereas during adult life, it is strictly related to various pathologic conditions. The aim of this study was to examine in the stroma of BM the presence, distribution and quantitation of cells expressing a-smooth muscle actin (MCs) from patients with monoclonal gammopathy of unknown significance, those with plasma cell myeloma and embryos (gestational age 15 to 25 weeks). For this reason, a series of 20 trephine bone marrow biopsies from adult patients and ten fetal specimens of the spine and femur were examined for the presence of stromal myoid cells using a monoclonal recognising alpha-smooth muscle actin, a contractile microfilament expressed solely by smooth muscle cells, myofibroblasts and related cells. Our results suggest that the appearance of MCs and subsequent fibrosis is not a feature of malignant BM disorders such as MM but it is also seen to a lesser degree in the BM stroma of individuals with monoclonal gammopathy of unknown significance (MGUS). Stromal cells with phenotypic smooth muscle features appear in bone marrow during pathological situations in a manner reminiscent of what occurs during normal development.

Actins↗

Map of the Anlage fields in the avian unincubated blastoderm.

By excision at different sites of rectangular fragments from unincubated chicken blastoderms and replacement by isotopic fragments from unincubated quail blastoderms, we could make the first complete map of the Anlage fields in the freshly laid avian blastoderm. All the Anlage fields (Fig. 11) are found in the upper layer (UL) of the caudal half of the area centralis (bordered by the Rauber-Koller's sickle). In the UL of the area marginalis, peripheral to Rauber-Koller's sickle, neither gastrulation nor neurulation phenomena could be observed. Similar heterotopic replacement experiments indicate that before incubation, the different parts of the UL of the area centralis are still uncommitted or reversibly committed. The Anlage fields of chordamesoblast and definitive endoderm (gut endoderm) in unincubated avian blastoderms appeared to be disposed caudally in the caudal half of the area centralis. As far as we know we are the first to demonstrate that the Anlage field of the definitive gut endoderm (which is derived from the upper layer: Hunt, 1937; Vakaet, 1962b) is localized in the most caudal upper layer part of the area centralis just centrally to the Rauber-Koller's sickle. The Anlage field of the neural plate is localized in the upper layer over the more cranial endophyll. The Anlage of the brain is shield-shaped, whilst the other Anlage fields are sickle-shaped, parallel with the Rauber-Koller's sickle. Their general hemicircular disposition and form still seem to reflect (together with the Rauber-Koller's sickle) the original ooplasmic radial symmetry (Callebaut, 1972) combined with the eccentricity of the deep layer components, which was observed during early symmetrization by gravitational orientation of the egg yolk (Callebaut, 1993a,b). The Rauber-Koller's sickle might be homologous with the vegetal dorsalizing cells or centre of Nieuwkoop (1973) in amphibian blastulas.

Animals↗

Cell disposition and adhesiveness in the developing chick neural retina.

The adhesive properties of neural retinal cells located in the ventral and dorsal hemispheres of chick embryonic eyes were investigated. Cell adhesion was monitored using the collision efficiency method; this technique provides a system in which it is possible to identify any preferential adhesions that may occur between cells. In this study no adhesive specificity was detected between cells of the dorsal and ventral retina. This evidence would not support theories which invoke preferential cell adhesion as an explanation of the ordered projection of the neural retina onto the optic tectum during development.

Animals↗

Differentiation of membrane systems during development of slow and fast skeletal muscle fibres in chicken.

The disposition of transverse (T) tubules, sarcoplasmic reticulum (SR) and T-SR junctions (triads) and the width of Z lines are matched to contractile properties in adult muscle fibres. We have studied the development of the membrane systems in the slow anterior (ALD) and the fast posterior (PLD) latissimus dorsi of the chicken in ovo (E14-E21) and after hatching (D1-D30). T tubules, SR, triads and Z lines were visualized using DiIC16[3] labelling for confocal microscopy and either Ca-osmium-ferrocyanide or standard procedures for electron microscopy. Anterior latissimus dorsi and PLD have similar, slow twitches in early development (E14-E16), but PLD suddenly becomes faster starting at E17-E18. We find that in coincidence with the differentiation of faster contraction properties (starting at E18-E19) density of triads is significantly higher and width of Z lines is narrower in PLD. The SR also begins to acquire fibre-type specific characteristics at this time. Early development of T tubules, on the other hand, is quite similar in the two muscles. Peripherally-located, longitudinally-oriented T tubules, and the first T networks crossing the fibre center appear earlier in ALD (E14-E15 and E16) than in PLD (E14-E16 and E17), but have similar dispositions. The final fibre-type specific distribution of T tubules is achieved after hatching. Some T tubules-rich fibres in the ALD, presumably future fast fibres, develop extensive T tubules networks at early stages. Location of triads at the Z line in pectoralis occurs in three steps: an initial location of longitudinally oriented triads at the A-I junction; a subsequent move to the Z lines and finally a rotation to a transverse orientation.

Animals↗

Tissue disposition of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in maternal and developing long-evans rats following subchronic exposure.

Prenatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) produces alterations in the reproductive system of the developing pups. The objective of this study was to determine the disposition of TCDD in maternal and fetal Long-Evans (LE) rats following subchronic exposure, since the adverse reproductive and developmental effects have been extensively characterized in this strain of rat. LE rats were dosed by gavage with 1, 10, or 30 ng [(3)H]TCDD/kg in corn oil, 5 days/week for 13 weeks. At the end of 13 weeks, females were mated and dosing continued every day throughout gestation. Dams were sacrificed on gestation day (GD) 9, GD16, GD21, and post-natal day 4 and analyzed for [(3)H]TCDD-derived activity in maternal and fetal tissues. Maternal body burdens were equivalent at different time points, indicating that the dams were at steady state. Maternal body burdens were approximately 19, 120, and 300 ng TCDD/kg following doses of 1, 10, and 30 ng TCDD/kg, respectively. Individual embryo concentrations on GD9 were 1.6, 7, and 16 pg TCDD/g after maternal exposure of 1, 10, and 30 ng/kg/d, respectively. On GD 16, fetal liver, urogenital tract, head, and body concentrations were similar and averaged 1.4, 7.8, and 16.4 pg TCDD/g after administration of 1, 10, or 30 ng TCDD/kg/d, respectively, indicating no preferential sequestration within the different fetal tissues. These concentrations of TCDD within fetal tissues after subchronic exposure are comparable to those seen after a single dose of 50, 200, or 1000 ng TCDD/kg administered on GD15, a critical period of gestation.

Adipose Tissue↗