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PubMed2006

Gene polymorphisms of the renin-angiotensin system and early development of hypertension.

BACKGROUND: A case-control association study was conducted to investigate a possible involvement of polymorphisms of three renin-angiotensin system genes: ACE (I/D and T-3892C), AGT (M235T and T174M), and AT1R (A1166C) in the early development of hypertension. METHODS: One hundred nineteen hypertensive and 125 normotensive participants aged 18 to 40 years were selected from a broader sample representative of the general population of Croatia. The selection criteria for hypertensive cases were systolic blood pressure (BP) higher than 140 mm Hg or diastolic BP higher than 90 mm Hg and a history of hypertension according to patient interview. RESULTS: Among the polymorphisms investigated, only those located on the ACE gene were associated with hypertension. For ACE I/D, the odds ratio for hypertension of DD versus II homozygote individuals was 2.50 (95% confidence interval [CI] 1.19-5.25) and for ACE T-3892C, the odds ratio of CC versus TT individuals was 2.32 (95% CI 1.05-5.10). Both polymorphisms of the ACE gene were in tight linkage disequilibrium. Of the investigated risk factors for hypertension, only body mass index (BMI) showed an influence on the early development of hypertension, acting independently of the ACE polymorphism. Their additive effect gives rise to 86% of hypertensives in subjects having both the DD genotype and BMI >or=30 kg/m(2). CONCLUSIONS: The present study provides evidence of the association of the ACE gene polymorphisms and premature hypertension. In addition, BMI proved to be another important predictor of the disorder acting independently of the ACE gene.

Adolescent↗

PubMed1999

The roles of 5'-HS2, 5'-HS3, and the gamma-globin TATA, CACCC, and stage selector elements in suppression of beta-globin expression in early development.

The roles of HS2 and HS3 from the human beta-globin locus control region and of the TATA, CACCC, and stage selector elements of the gamma-globin promoter, in competitive inhibition of beta-globin gene expression in early development, were tested using stable transfections of HEL and K562 cells. Cells with an HS3gamma beta construct demonstrate that HS3 exhibits enhancing activity, but compared with HS2, this site participates less consistently in the inhibition of embryonic/fetal beta-globin expression. In cells with HS3HS2gamma beta constructs, the two HS sites act in concert to more effectively enhance gamma-globin gene expression and to drive stage-specific expression of the gamma- and beta-globin genes. A gamma-globin gene with a -161 promoter can competitively inhibit beta-globin gene expression. HS3HS2gamma beta constructs were used to determine the effects of gamma-globin promoter mutations within this region on competition. The CACCC and TATA elements, but not the stage selector element, inhibit inappropriate embryonic/fetal stage expression of the beta-globin gene. The mutation in the gamma-globin TATA element results in the use of two major alternative transcription start sites. The data suggest that proteins binding to the gamma-globin CACCC and TATA elements interact with those binding to HS2 and/or HS3 to preclude beta-globin transcription in early development.

Cell Line↗

PubMed2003

Chromatin remodeling during sea urchin early development: molecular determinants for pronuclei formation and transcriptional activation.

Transcriptional activation of specific genes is initiated after fertilization by the interaction of specific transcription factors with its cognate sequences in the chromatin context, thereby leading to a concerted and coordinated program which determines early development. Remodeling of the sperm chromatin after fertilization is a fundamental event for transcriptional activation and expression of the paternally inherited genome. The transitions in chromosomal proteins, as well as the mechanisms that participate in these transitions, have been investigated only to a limited extent as compared to the signal transduction patterns that govern egg activation or the dynamics and structural changes accompanying sperm nuclear membrane dissociation-association following insemination. In this review, we will discuss the remodeling of sperm chromatin that follows fertilization. We will emphasize the transitions of chromosomal proteins, as well as the post-translational modifications associated with these transitions. The molecular mechanisms that may be participating in these events will also be analyzed. We will further discuss the mechanisms that govern chromatin remodeling and the role of specific transcription factors in the control of the transcriptional program during sea urchin early development.

Animals↗

PubMed1988

Early development of four Diphyllobothrium species in the final host.

The early development of four Diphyllobothrium species, D. latum, D. dendriticum, D. ditremum, and D. vogeli, are described. D. latum sheds the entire larval body easily and shows a high shedding rate of 82.1% on average. On the other hand, D. dendriticum exhibits a different developmental pattern, with a low shedding rate of 8.7% in the hamster and a high shedding rate of 34.9% in the rat. D. ditremum is difficult to recover from hamsters but shows a high shedding rate of 42.9%. D. vogeli shows a constant recovery rate of 38.3% without shedding. The species specificity of these four diphyllobothriids is discussed briefly in relation to the early developmental pattern and the growth rate.

Animals↗

PubMed2000

[Long-chain polyunsaturated fatty acids in the early development of the human nervous system].

The role of long-chain polyunsaturated fatty acids (LCPUFA) in the early development of the human nervous system was put forward by the better cognitive development observed in breast-fed than in formula fed infants in parallel with the presence of LCPUFA in human milk but not in formula. The role of LCPUFA in early human neurodevelopment can be investigated by comparing data obtained in formula fed infants randomly assigned to receive formula with or without LCPUFA. Investigations in preterm infants indicate that the presence of LCPUFA in the formula offers benefits for the early postnatal development of visual and cognitive functions. The unequivocal results obtained in preterm infants led to the recommendation of LCPUFA supplementation to formulae for preterm infants. In several studies in full-term infants, enhanced dietary intake of LCPUFA was accompanied with better visual acuity and better results in various cognitive tests. However, other studies did not show visual or cognitive differences between full-term infants fed formula with or without LCPUFA. It is a question under current debate whether supplementation of LCPUFA to formulae for full-term infants is required to lessen the difference between the intellectual development of breast-fed and formula fed infants.

Breast Feeding↗

PubMed1998

Early development of EMG localized muscle fatigue in hand muscles of patients with chronic heart failure.

BACKGROUND: Patients with chronic heart failure (CHF) frequently complain of fatigue and exercise intolerance that are not directly related to the severity of cardiac failure. A not well-defined muscle function impairment is generally considered the cause of such symptoms. The frequency compression of electromyographic (EMG) signal power spectrum during isometric contractions is commonly accepted as an index of the fatigue occurring in the muscle (localized muscle fatigue). PURPOSE AND METHODS: The purpose of the study was to evaluate muscle fatigue development in a selected group of CHF patients by studying the compression of the EMG signal power spectrum. The first dorsal interosseus of the right, dominant hand was investigated at two levels of contraction: 40% and 80% of the maximal voluntary contraction (MVC). RESULTS: In CHF patients there was early development of localized muscle fatigue during the high level of contraction (80% of MVC). CONCLUSION: This study demonstrates the presence of an early development of localized muscle fatigue in CHF patients and confirms the possibility of an increased glycolytic metabolism. Moreover, the changes seem to show that muscle impairment is not limited to large muscles, but also occurs in small muscles of the hands, frequently used during daily activities. Finally, this study confirms the validity of EMG spectral analysis techniques in evaluating muscle fatigue of CHF patients, suggesting a possible use in the rehabilitation of such patients when the technique is correctly used.

Adult↗

PubMed1990

Early development and myogenesis of the posterior anuran lymph hearts.

The early development of anuran posterior lymph hearts studied by light- and electron-microscopy in frog larval stages 25-29 (Gosner 1960) can be subdivided into three phases. In phase I, mesenchymal myogenic cells are found, each possessing a single 9 + 0 cilium and numerous filopode-like processes aggregated near the vena caudalis lateralis, forming up to three metameric organ anlagen arranged like a cuff around the preexisting lymphatics (stages 26/27). In phase II, cell proliferation starts at stage 28 within the lymph heart wall as does the formation of primarily polynuclear myofibres by fusion of several myoblasts. At this stage immature myofibres show a vast sarcoplasm, a poorly developed SR and only few myofibrils with not yet distinguishable A- and I-bands. In phase III, the afferent and efferent valves are formed at the onset of pulsation in stage 29. Contractile myofibres contain large glycogen fields and a considerable amount of myofibrils which frequently branch and show distinct Z-lines, A-, I-, H- and M-bands; 1-3 cilia were found lying within a channel-like cell invagination. The peculiarities of organogenesis and myofibre development are discussed.

Animals↗

PubMed1990

Early development of brainstem auditory evoked potentials in Down's syndrome.

Early development of brainstem auditory pathway was studied in 14 children with Down's syndrome (age range from 1 month to 3 years). The brainstem auditory evoked potentials (BAEP) during infancy was characterized by elevated threshold and poorly differentiated wave I. All children within 2 years had elevated threshold in one or both ears, suggesting a high incidence of peripheral hearing deficits. Follow-up tests showed that as age increased up to 3 years the elevated threshold gradually decreased and the differentiation of wave I improved. The I-V interpeak interval was slightly shorter and the amplitude of wave V was smaller than the normal controls, which existed continuously during follow-up studies. Our findings suggest that the development of peripheral hearing is delayed, although persistent hearing deficits cannot be excluded, and the functioning and development of the brainstem auditory pathway may also be abnormal in Down's syndrome children.

Aging↗

PubMed2005

[Effects of different electrofusion parameters on activation and early development of mouse embryos reconstructed by cumulus cell nuclear transfer].

OBJECTIVE: To study the effects of different parameters for electrofusion on the activation and early development of mouse embryos reconstructed by cumulus cell nuclear transfer, and explore optimal parameters for electrofusion. METHODS: A C57BL/6j mouse cumulus cell nucleus 10-12 mm in diameter was inserted into the perivitelline space of an enucleated oocyte. The fusion of donor-recipient pairs was induced with different parameters for electrofusion (with variation in electric field intensity, pulse duration and pulse times). Successful formation of the reconstructed embryos from donor-recipient pairs and the reconstructed embryos developing into the early embryonic stages (2-cell, 4-8-cell and morula stages) were observed and counted. RESULTS: The electric field intensity and pulse duration allowed variation during electrofusion within the range of 1 000-2 000 kV/cm and 40-160 ms, respectively. The donor-recipient pairs fused at very low rate when the parameters were below the allowed ranges, and disintegration or even death might occur when the parameters were above the ranges. Within these allowed ranges, variation of the electrofusion parameters did not produce significant impact on the ratio of the reconstructed embryos in 2-cell, 4-8-cell or morula stages (P<0.05). In addition, we suggested that pulse times be limited to 1-2. CONCLUSION: Optimal parameters for electrofusion are crucial for the fusion of donor-recipient pairs and the activation of the reconstructed embryo.

Animals↗

PubMed1985

The hierarchy of requirements for an elevated intracellular pH during early development of sea urchin embryos.

The intracellular pH (pHi) rises 0.3-0.5 units after fertilization of sea urchin eggs, and this and previous work show this pHi change is necessary for initiating the developmental processes leading to cell division. The experiments described here reveal that while the elevated pHi is permanently required for a normal early development, lowering pHi of embryos after fertilization affects different processes to different extents. Protein synthesis gradually becomes less sensitive to pHi. Karyokinesis proceeds to completion under a low pHi, but is retarded, while cytokinesis is always impaired. These results indicate a hierarchy of requirements for high pHi during early development of sea urchin embryos, with protein synthesis, karyokinesis, and cytokinesis showing, respectively, increasing requirements for an elevated pHi.

Acetates↗

PubMed1989

Effects of cadmium and PCBs on reproduction of the sea star Asterias rubens: aberrations in the early development.

In semifield experiments sea stars, Asterias rubens, were exposed to 25 micrograms Cd/liter or fed with mussels containing 0.6 microgram/g wet wt PCBs (Clophen A50). After 5 months of exposure, Cd concentrations in testes and ovaries were respectively 17 and 50 times higher than those in unexposed sea stars. PCB concentrations were respectively 7 and 9 times higher. With spermatozoa obtained from Cd- or PCB-exposed sea stars, normal fertilization could be achieved. However, maturation of oocytes from Cd-exposed animals was delayed and early development of embryos from Cd- or PCB-exposed animals was disturbed. Due to aberrations during the early development only 24 and 30% of the embryos obtained from Cd- or PCB-exposed sea stars, respectively, had developed to normal bipinnaria larvae after 1 week.

Animals↗

PubMedDate not supplied

Early development of the neural plate, neural crest and facial region of marsupials.

Marsupial mammals have a distinctive reproductive strategy. The young are born after an exceptionally short period of organogenesis and are consequently extremely altricial. Yet because they must be functionally independent in an essentially embryonic condition, the marsupial neonate exhibits a unique suite of adaptations. In particular, certain bones of the facial region, most cranial musculature and a few additional structures are accelerated in their development. In contrast, central nervous system structures, especially the forebrain, are markedly premature at birth, resembling an embryonic d 11 or 12 mouse. This review examines the developmental processes that are modified to produce these evolutionary changes. The focus is on the early development of the neural plate, neural crest and facial region in the marsupial, Monodelphis domestica, compared with patterns reported for rodents. Neural crest begins differentiation and migration at the neural plate stage, which results in large accumulations of neural crest in the facial region at an early stage of development. The early accumulation of neural crest provides the material for the accelerated development of oral and facial structures. The first arch region is massive in the early embryo, and the development of the olfactory placode and frontonasal region is advanced relative to the forebrain region. The development of the forebrain is delayed in marsupials relative to the hindbrain or facial region. These observations illustrate how development may be modified to produce evolutionary changes that distinguish taxa. Further, they suggest that development is not necessarily highly conserved, but instead may be quite plastic.

Adaptation, Physiological↗

PubMed1999

Nuclear import of p53 during Xenopus laevis early development in relation to DNA replication and DNA repair.

The role of p53 in transcriptional activation of genes involved in cell cycle progression is well established. However, the wide range of functions attributed to this gene suggests that some of them might be unrelated to transcription. Here we investigated p53 localization and recruitment to chromatin during Xenopus early development when 12 rapid cell cycles occur without transcription of the genome. We show that after fertilization, part of the large store of p53 previously stored in the cytoplasm of the oocyte is imported into the nucleus. This import was further analyzed in relation with DNA replication and DNA repair using cell-free systems from Xenopus eggs. Formation of a nuclear lamina envelope is necessary for the import of p53 into the nucleus. p53 associates both with decondensed DNA and the nuclear lamina envelope, but no colocalization with prereplication or replication complexes is observed. We show that UV- or gamma-damaged nuclei recruit p53 as well as replication protein A (RPA) in large common foci. Together, these data suggest that p53 plays a role in the regulation of the accelerated S phases that occur during Xenopus early development, in a manner that does not rely on its transcription-mediated activity.

Animals↗

PubMed1998

Evidence for introduction of a variable G1 phase at the midblastula transition during early development in axolotl.

After fertilization in axolotl, the synchronous cell cleavages are triphasic (S, G2 and M phases). Midblastula transition (MBT) begins at the ninth cleavage and is the consequence of lengthening of cell cycles. By spectrofluorometry and incorporation of 3H thymidine into the nuclear DNA followed by autoradiography on individual cells, the time at which a G1 phase appears during early development was investigated. The present results show that the G1 phase was introduced for the first time at MBT and its duration was variable from one blastomere to another. This variability could account for lengthening of cell cycles and be required for zygotic transcriptions necessary for DNA replication. From this point of view, axolotl represents an interesting alternative amphibian model to identify regulators involved in the G1-S transition at MBT during early development.

Ambystoma↗

PubMed2004

Collagen IV is essential for basement membrane stability but dispensable for initiation of its assembly during early development.

Basement membranes are specialized extracellular matrices consisting of tissue-specific organizations of multiple matrix molecules and serve as structural barriers as well as substrates for cellular interactions. The network of collagen IV is thought to define the scaffold integrating other components such as, laminins, nidogens or perlecan, into highly organized supramolecular architectures. To analyze the functional roles of the major collagen IV isoform alpha1(IV)(2)alpha2(IV) for basement membrane assembly and embryonic development, we generated a null allele of the Col4a1/2 locus in mice, thereby ablating both alpha-chains. Unexpectedly, embryos developed up to E9.5 at the expected Mendelian ratio and showed a variable degree of growth retardation. Basement membrane proteins were deposited and assembled at expected sites in mutant embryos, indicating that this isoform is dispensable for matrix deposition and assembly during early development. However, lethality occurred between E10.5-E11.5, because of structural deficiencies in the basement membranes and finally by failure of the integrity of Reichert's membrane. These data demonstrate for the first time that collagen IV is fundamental for the maintenance of integrity and function of basement membranes under conditions of increasing mechanical demands, but dispensable for deposition and initial assembly of components. Taken together with other basement membrane protein knockouts, these data suggest that laminin is sufficient for basement membrane-like matrices during early development, but at later stages the specific composition of components including collagen IV defines integrity, stability and functionality.

Animals↗

PubMed1997

Activin signalling has a necessary function in Xenopus early development.

The first signalling event in Xenopus development is the mesoderm-forming (or Nieuwkoop) induction, starting three hours after fertilization [1]. Two prime candidates for the molecule that mediates this signalling are activin [2] and Vg1 [3], both members of the transforming growth factor beta (TGFbeta) family. Because genetic methods are not available for amphibian studies, 'dominant-negative' truncated receptors have been used in studying signalling molecules such as the receptors for fibroblast and platelet-derived growth factors (FGF and PDGF) [4] [5]. The truncated receptors bind to, and prevent signalling from, endogenous receptors. Activin is a potent mesoderm inducer in vitro, and the severe phenotype obtained using a dominant-negative activin receptor in Xenopus [6], coupled with evidence from fish [7], suggested that activin is essential for development. However, a dominant-negative receptor for activin blocked the activity of other TGFbeta family members in Xenopus, most notably Vg1 [8], and activin 'knock-out' mice are essentially wild-type in phenotype [7]; these two findings cast doubt on the idea of a function for activin in early development. We have designed a new receptor construct which can selectively block the function of activin but not of Vg1, and we have used it to show that activin has an essential role in vivo in Xenopus early development. We conclude that activin, or a close relative that has yet to be described, is required for normal development.

Activin Receptors↗

PubMed1998

Chlorpropham [isopropyl N-(3-chlorophenyl) carbamate] disrupts microtubule organization, cell division, and early development of sea urchin embryos.

The herbicide CIPC [N-(3-chlorophenyl) carbamate] has been shown to disrupt microtubule organization in plants, apparently by interfering with the functioning of the microtubule organizing center. Very few studies have examined the effects of CIPC on animal cell microtubules and centrosomes, however, and the effects of this cytoskeletal disrupting agent on fertilization and early development have not been studied in detail. To address these questions, fertilized sea urchin eggs were cultured in the presence of CIPC until the prism stage, and perturbations in the cytoskeleton and development were examined. It was found that Lytechinus pictus embryos are sensitive to micromolar amounts of CIPC, and that a characteristic set of cytoskeletal and developmental deficits is produced as a result of exposure to this herbicide. Mitotic spindles were truncated and randomly oriented within zygotes and blastomeres, and cytokinesis was compromised, resulting in the production of blastomeres of various sizes and ploidy. Interestingly, in spite of these cytoskeletal and nuclear alterations, spindle poles at fourth cleavage retained their ability to interact with the plasma membrane in a manner similar to that normally characterizing the unequal division of macromeres and micromeres. CIPC treatment resulted in unequal cell divisions at atypical times, and skeletal spicule formation in these embryos was abnormal. These results indicate that CIPC may pose a significant health risk during mammalian embryogenesis; in addition, it may be a useful tool with which to study microtubule and centrosomal functioning during animal cell division-especially in those cell types that exhibit stereotypic patterns of cell division during early development.

Actin Cytoskeleton↗

PubMed2005

Is the early development of girls with Rett disorder really normal?

An apparently normal early development was one of the initial criteria for classical Rett syndrome. However, several investigators considered Rett syndrome to be a developmental disorder manifesting very soon after birth. Videos of 22 Rett cases were assessed carefully for movements, posture, and behavior during the first 6 mo of life. All signs that deviated from the normal standard were recorded meticulously. Special attention was paid to the face, the hands, and body movements. A detailed analysis clearly demonstrated an abnormal quality of general movements (100%), tongue protrusion (62%), postural stiffness (58%), asymmetric eye opening and closing (56%), abnormal finger movements (52%), hand stereotypies (42%), bursts of abnormal facial expressions (42%), bizarre smile (32%), tremor (28%), and stereotyped body movements (15%). Our study is the first to apply specific standardized measures of early spontaneous movements to Rett infants, proving conclusively that the disorder is manifested within the first months of life. Although not necessarily specific, the signs that we have observed will be of value in alerting clinicians to the possibility of the diagnosis at an early stage, when intervention is likely to be most effective.

Child Development↗