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PubMed1982

The thyroid hormone effects on growth and development may be mediated by growth factors.

Thyroid hormones modulate energy metabolism and importantly influence growth and development. These effects are independently mediated. Thyroid calorigenesis is influenced predominantly via nuclear receptor mediated synthesis of mitochondrial respiratory assemblies and cell membrane sodium potassium ATPase. Accumulating evidence suggests that many of the thyroid hormone effects on development are mediated via growth factors, including somatomedins (SM), erythropoietin (EP), nerve growth factor (NGF) and epidermal growth factor (EGF). Thyroid hormone binding to nuclear receptors is known to stimulate growth hormone (GH) synthesis, and thyroid hormones probably potentiate GH stimulation of SM production as well as the anabolic effects of SM. The production of EP, NGF and EGF also are thyroid hormone responsive, and it seems likely that these growth factors mediate the thyroid hormone effects on erythrocyte production, autonomic and perhaps central nervous system maturation, and epidermal development, respectively.

Adenosine Triphosphatases↗
PubMed2003

Latitudinal and temperature-dependent variation in embryonic development and growth in Rana temporaria.

Variation in seasonal time constraints and temperature along latitudinal gradients are expected to select for life history trait differentiation, but information about the relative importance of these factors in shaping patterns of divergence in embryonic traits remains sparse. We studied embryonic survival, growth and development rates in the common frog (Rana temporaria) along a 1,400-km latitudinal gradient across Sweden by raising embryos from four populations in the laboratory at seven temperatures (9 degrees C, 12 degrees C, 15 degrees C, 18 degrees C, 21 degrees C, 24 degrees C, 27 degrees C). We found significant differences in mean values of all traits between the populations and temperature treatments, but this variation was not latitudinally ordered. In general, embryonic survival decreased at the two highest temperatures in all populations, but less so in the southernmost as compared to the other populations. The northernmost population developed slowest at the lowest temperature, while the two mid-latitude populations were slowest at the other temperatures. Hatchling size increased with increasing temperature especially in the two northern populations, whereas the two southern populations showed peak hatchling size at 15 degrees C. Analyses of within-population genetic variation with a half-sib design revealed that there was significant additive genetic variation in all traits, and egg size-related maternal effects were important in the case of hatchling size. Overall, our results indicate that unlike larval growth and development, variation in embryonic development and growth in R. temporaria cannot be explained in terms of a latitudinal gradient in season length. While adaptation to a latitudinal variation in temperature might have contributed to the observed differentiation in embryonic performance, the effects of other, perhaps more local environmental factors, seem to have overridden them in importance.

Analysis of Variance↗
PubMedDate not supplied

Male and female correlations for taster (P.T.C.) phenotypes and rate of adolescent development.

Growth and development from infancy to age 18 years in tasters and non-tasters of phenylthiocarbamide (P.T.C.) were studied in 50 female and 44 male subjects. Taster girls reached all indices of maturation an average of 3.8 months earlier than non-taster girls. The reverse was true for boys, non-tasters maturing on average 6.2 months earlier than tasters. For both sexes, there was a significant correlation between an overall Maturity Index and P.T.C. sensitivity, positive for girls and negative for boys. Thirty-two of the females and 20 of the males could be classified according to P.T.C. genotype. For these, the onset, midpoint, and end of the pubertal growth spurt was estimated. Heterozygotes reached these points at times intermediate to homozygotes. Taster females preceded non-taster females and non-taster males preceded taster males by about 6 months. The finding of reversed associations between P.T.C. phenotype and maturation in males and females implies that factors underlying the P.T.C. polymorphism may not be confined to mediation through thyroid metabolism, but may also involve other complex pathways of the hypothalamic-pituitary-gonadal axis, particularly those of the sex hormones. The data were examined for evidence of whether or not the findings could be related to a means of maintaining the P.T.C. polymorphism. A significant negative assortative mating pattern was found. This accords with reports from the literature indicating personality differences between early and late maturers and a tendency for spouses to have similar personality characteristics. However, disassortative mating alone could not produce a stable equilibrium. A hypothesis for the maintenance of the P.T.C. polymorphism is developed on the assumption that the timing of puberty is related to reproductive fitness and subject to balancing selection. Heterozygotes for P.T.C. would be at an advantage because they have intermediate maturation times. In this small sample, P.T.C. heterozygotes were also found to produce more offspring than homozygotes.

Adolescent↗
PubMed2002

Mitochondrial genome content is regulated during nematode development.

Growth and development rely on the mitochondrial respiratory chain (MRC) as the major source of ATP. We measured the mitochondrial DNA (mtDNA) copy number of each of the Caenorhabditis elegans developmental stages. Embryos, L1, L2, and L3 larvae all have approximately 25,000 copies of maternally derived mtDNA. The copy number increases fivefold in L4 larvae and a further sixfold in adult hermaphrodites, but only twofold in adult males. The majority of mtDNA in adult worms is germline associated, and germline-deficient mutants show markedly reduced mtDNA contents. With sperm-deficient or oocyte-deficient mutants, we confirm that mtDNA amplification is primarily associated with oocyte production. When mtDNA replication is inhibited, a quantitative and homogeneous arrest as L3 larvae occurs. Thus, mtDNA amplification is a necessary component of normal development and its regulation may involve an energy-sensing decision or checkpoint that can be invoked when mitochondrial energy generation is impaired.

Animals↗
PubMed1991

Growth and development in orthodontics.

Growth and development comprise the infrastructure of clinical diagnosis and treatment planning in orthodontics. The two current key issues have been growth prediction and growth stimulation induced by functional appliances. The stability of results in orthodontics and in the combined orthognathic-orthodontic treatment modality are likewise linked to growth and development. Changes in the untreated dentition after the permanent teeth are present in the mouth provide another important frame of reference for the clinician. The hazards of cephalometric analysis when relying on intracranial reference lines has recently captured a wave of attention, and if comprehended, should revitalize cephalometrics in clinical practice and in research.

Activator Appliances↗
PubMed1989

Fibroblast growth factor and transforming growth factor beta in early embryonic development.

Growth factors are known to have pleiotropic effects on many cell types ranging from the control of cell proliferation to inducing cell differentiation. FGF and TGF beta are members of two growth factor families which are thought to be involved in embryogenesis of the frog, Xenopus laevis. These two growth factors are equivalent to the embryonic "morphogen(s)" which induce one of the first differentiation events during embryogenesis, the formation of the mesoderm. Embryonic induction events are crucial for the development of most organisms and, therefore, these growth factors may be involved in induction events during mammalian embryogenesis. Thus, the structure and function of TGF beta and FGF molecules appear to be conserved throughout vertebrate evolution and during ontogeny, growth factors and their signalling pathways may be used for different functions depending upon the nature of the target cell.

Animals↗
PubMed1998

Care of the premature infant: Part I. Monitoring growth and development.

When monitoring growth and development in the premature infant, physicians should make adjustments for the estimated due date. With minor exceptions, administration of immunizations is based on the chronologic age. Administration of hepatitis B vaccine should be delayed until the infant weighs 2,000 g (4 lb, 5 oz). Administration of influenza vaccine should be considered in infants with chronic medical problems, and the pneumococcal vaccine may be beneficial at age two in children with chronic problems, especially pulmonary disease. Premature infants should also be monitored to assure appropriate nutrition. Breast-fed infants should probably receive vitamin supplements during the first year. Supplemental iron should be initiated at two weeks to two months after birth and continued for 12 to 15 months. Office care includes screening for problems that occur more frequently in premature infants, especially vision and hearing problems. Because many of these infants require care from multiple medical disciplines, coordination of care is another important role for the family physician. The goals of this care are to promote normal growth and development and minimize morbidity and mortality.

Deficiency Diseases↗
PubMedDate not supplied

The effects of a fluoroquinolone on the growth and development of infants.

Growth and development were monitored for up to 42 months in nine neonates to whom ciprofloxacin, a fluoroquinolone, was given in the neonatal period at a dosage of 20 mg/kg/day. Ciprofloxacin was used only as a ¿life-saving' therapy in cases of sepsis produced by bacterial agents resistant to other antibiotics. Two other groups of nine neonates, matched by birth weight and gestational age, were studied as controls: one group with sepsis, which was effectively treated with cefotaxime and a group of healthy neonates. No statistically significant differences in growth and development between the groups were found during follow-up for 42 months. No osteoarticular problems or joint deformities were observed in the ciprofloxacin group. Ciprofloxacin appears to provide a therapeutic option as a ¿life-saving' therapy for newborns with sepsis produced by multiply resistant organisms.

Anti-Infective Agents↗
PubMed1989

[Development of mandibular movements associated with growth and development of stomatognathic system].

In order to clarify the development of mandibular movements associated with growth and development of the stomatognathic system, we compared the mandibular movements of children with normal occlusion at different Hellman's dental age between IIA and IIIB, during tooth tapping movements using the following 7 different kinds of frequency; ad lib.; 1 time/sec, 2 times/sec and 3 times/sec movements with reguration; 1 time/sec, 2 times/sec and 3 times/sec movements without reguration. Then, we determined the correlation between the results and the subjects' chronological age and obtained the following findings. 1) During 5 strokes between the 3rd and 7th strokes after the start of the tooth tapping movements, mandibular movements were not very diversified among 30 tooth tapping movements using the 7 different kinds of frequency, and the mean values were almost consistent. 2) In the 5 strokes between the 3rd and 7th strokes at all dental age, each determined item showed minimal dispersion during the 3 times/sec unregurated movements. 3) In the following items, changes related to age were noted during the 3 times/sec unregurated movements. (1) Cycle time decreased and became closer to the calculated value (333.33 msec), and maximum velocity in closing increased as age advanced. (2) Although there was no significant correlation with the subjects' chronological age, degree of mandibular opening, duration of opening phase, duration of closing phase, duration of occluding phase and velocity peak time in opening decreased, and maximum velocity in opening increased as age advanced. (3) Velocity peak time in closing was only slightly influenced by age. 4) These results indicate that mandibular movements develop in the course of growth and development of the stomatognathic system.

Humans↗
PubMed2000

The roles of placental growth hormone and placental lactogen in the regulation of human fetal growth and development.

The human growth hormone (hGH)/human placental lactogen (hPL) gene family, which consists of two GH and three PL genes, is important in the regulation of maternal and fetal metabolism and the growth and development of the fetus. During pregnancy, pituitary GH (hGH-N) expression in the mother is suppressed; and hGH-V, a GH variant expressed by the placenta, becomes the predominant GH in the mother. hPL, which is the product of the hPL-A and hPL-B genes, is secreted into both the maternal and fetal circulations after the sixth week of pregnancy. hGH-V and hPL act in concert in the mother to stimulate insulin-like growth factor (IGF) production and modulate intermediary metabolism, resulting in an increase in the availability of glucose and amino acids to the fetus. In the fetus, hPL acts via lactogenic receptors and possibly a unique PL receptor to modulate embryonic development, regulate intermediary metabolism and stimulate the production of IGFs, insulin, adrenocortical hormones and pulmonary surfactant. hGH-N, which is expressed by the fetal pituitary, has little or no physiological actions in the fetus until late in pregnancy due to the lack of functional GH receptors on fetal tissues. hGH-V, which is also a potent somatogenic hormone, is not released into the fetus. Taken together, studies of the hGH/hPL gene family during pregnancy reveal a complex interaction of the hormones with one another and with other growth factors. Additional investigations are necessary to clarify the relative roles of the family members in the regulation of fetal growth and development and the factors that modulate the expression of the genes.

Embryonic and Fetal Development↗
PubMed1999

Growth monitoring: family participation: effective community development.

Growth monitoring was introduced into most developing countries in the 1970s with the aim of combating under nutrition in infancy and childhood. Ten years later analysis showed weight charts were not completed satisfactorily and not used in decision making. Although growth monitoring is now seldom mentioned in nutrition studies, the authors of this study are convinced of its value. With new technology using the direct recording scales (DRS), illiterate or semi-literate mothers are able to complete the growth curve on the weight chart and acquire understanding about the process and its significance for their infant. This study investigates the understanding of the growth curve by the rest of the family. The mother, their daughters and significantly, the grandmothers were shown to have comprehended the meaning of the growth curve. In families where mothers weighed their infant using the DRS, a smaller proportion were found to be suffering from periods of growth failure compared with families where the infant was weighed by community health workers with a dial scale. There are obvious gains if technologies are moved from the clinic into the family and the community. The weighing and charting of children by DRS may be a further step in the fight to overcome undernutrition in developing countries.

Adolescent↗
PubMed2004

Megakaryocyte growth and development factor is a potent growth factor for primitive hematopoietic progenitors in the human fetus.

Megakaryocyte growth and development factor (MGDF), or thrombopoietin, has received considerable attention as a therapeutic agent for treating thrombocytopenia or for its use in the ex vivo culture of hematopoietic stem cells. MGDF is known to support the growth of a broad spectrum of hematopoietic precursors obtained from adult or neonatal tissues, but its effects on the growth of fetal progenitors and stem cells has not been studied. Human CD38(+)CD34(2+) progenitors and CD38(-)CD34(2+) cells, a population that contains stem cells, were isolated from midgestation liver and grown under defined conditions with MGDF and various cytokines known to support the growth of primitive hematopoietic precursors. In clonal assays of colony-forming cells (CFCs), MGDF supported the growth of 15-25% of candidate stem cells when combined with granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor (GM-CSF), flk-2/flt3 ligand, or stem cell factor. MGDF was observed to strongly support the early stages of hematopoiesis and expansion of high proliferative potential CFCs. More mature progenitors were expanded nearly 78-fold in 1 wk of culture with MGDF+SCF+GM-CSF. MGDF alone was also found to support the short-term (2 d) survival of CD38(-)CD34(2+) high proliferative potential CFCs. The effects of MGDF were more modest on CD38(+)CD34(2+) progenitors with only additive increases in colony formation being observed. These findings suggest that MGDF administration in fetuses and neonates may strongly affect the growth and mobilization of primitive hematopoietic progenitors and that MGDF may find use in the ex vivo growth and expansion of fetal stem cells.

Colony-Forming Units Assay↗
PubMed1990

Functional roles of insulin and insulinlike growth factors in preimplantation mouse embryo development.

Growth factors are known to play important roles in cellular proliferation and differentiation. However, little information is available concerning their roles in the earliest stages of mammalian development. The effect of physiologic levels of insulin, insulinlike growth factor-I, and insulinlike growth factor II (IGF-I and -II) on DNA, RNA, and protein synthesis in preimplantation stages of the mouse are described in this study. Quantitative studies of the incorporation of labeled thymidine, uridine, and methionine into trichloroacetic acid-insoluble material by different developmental stages of preimplantation mouse embryos labeled in vitro, indicate that physiologic levels of insulin stimulated DNA, RNA, and protein synthesis with significant effects observed first at the morula stage of development. In contrast, neither IGF-I nor IGF-II stimulated DNA, RNA, or protein synthesis to a significant degree under the same experimental conditions. These results suggest a functional role for insulin at the earliest stages of mammalian embryogenesis.

Animals↗
PubMed2006

The effects of the members of growth hormone family knockdown in zebrafish development.

Growth hormone (GH), prolactin (PRL), and somatolactin (SL) are members of GH/PRL superfamily. These hormones are involved in the regulation of an array of physiological processes, including growth, lactation, and osmoregulation. While recent evidence has shown the GH, PRL, and SL gene transcripts and protein products are expressed during early zebrafish development, their functions at this time of embryogenesis remain unknown. In the current study, antisense morpholino oligonucleotide (MO) inhibition of gh, prl, and sl gene translation was used to examine the effects of gene knockdown on hormone function in zebrafish development. We observed that PRL, SLalpha and SLbeta MO treatment all affected development. PRL MO-treated embryos showed defects in gas bladder inflation, reduced head and eye size, shorter body length and fewer melanophores than untreated controls, whereas SLalpha and SLbeta MO-treated embryos were only defective in gas bladder inflation, GH MO-inhibition of GH specific translation did not lead to any discernable morphological changes within 10 days post fertilization (dpf). The effects of PRL knockdown were further verified using a second PRL morpholino antisense and by a rescue experiment with in vitro transcribed prl mRNA containing 5 nucleotide mismatch within the PRL-MO binding region. These results provide the first evidence that members of the GH/PRL superfamily play a role in proper development of various structures including the head, eyes, melanophores and the gas bladder in zebrafish.

Air Sacs↗
PubMed2005

Spatial distribution of growth hormone receptor, insulin-like growth factor-I receptor and apoptotic chondrocytes during growth plate development.

Linear bone growth depends upon proliferation, maturation, and apoptosis of growth plate chondrocytes, processes regulated by growth hormone (GH) and insulin-like growth factor-I (IGF-I). To investigate the contribution of GH, IGF-I and apoptosis to growth plate function, the expression of GH receptor (GHR) and IGF-I receptor (IGF-IR) mRNA were evaluated by in situ hybridization in fractionated costochondral growth plates of growing rats (at 2, 4, and 7 weeks). Apoptosis was determined by TUNEL assay and morphology in histological sections. GHR mRNA was greatest in resting cells with hypertropic cells increasing GHR expression with increasing age. Hypertropic and resting cell IGF-IR mRNA declined over the ages studied. Receptor mRNA expression was altered by exposing cells to GH or IGF-I. GH and IGF significantly decreased GHR mRNA in proliferative cells. GH and IGF also decreased IGF-IR mRNA in resting cells and the 2- and 4-week-old proliferative and hypertropic cells. Treating cells in culture with GH increased the number of apoptotic cells across all ages and zones. Histologically, apoptotic cells were observed at the chondro-osseous junction and within actively proliferating chondrocytes but not in resting cells. Apoptosis was highest at 4 weeks of age with lateral regions displaying the greatest number of cells undergoing apoptosis. These data indicate that apoptosis plays a role in growth plate function, particularly spatial configuration as indicated by the preferential lateral cell apoptosis. The susceptibility of proliferative cells to GHR and IGF-IR down regulation during the period of greatest apoptosis supports a role for the GH-IGF axis in both proliferation and apoptosis during growth plate development.

Animals↗
PubMed1988

Disturbances of bone growth and development.

"What is growth anyway? Can one talk about positive growth in childhood, neutral growth in maturity, and negative growth in old age?" Our goal is to help promote normal positive growth in infants and children. To achieve this, we must be cognizant of the morphologic changes of both normal and abnormal bone formation as they are reflected in the radiographic image of the skeleton. The knowledge of the various causes and the pathophysiologic mechanisms of the disturbances of bone growth and development allows us to recognize the early radiographic manifestations. Endocrine and metabolic disorders affect the whole skeleton, but the early changes are best seen in the distal ends of the femurs, where growth rate is most rapid. In skeletal infections and in some vascular injuries two-or three-phase bone scintigraphy supercedes radiography early in the course of the disease. MRI has proved to be very helpful in the early detection of avascular bone necrosis, osteomyelitis, and tumor. Some benign bone tumors and many bone dysplasias have distinct and diagnostic radiographic findings that may preclude further studies. In constitutional diseases of bone, including chromosomal aberrations, skeletal surveys of the patient and all family members together with biochemical and cytogenetic studies are essential for both diagnosis and genetic counseling. Our role is to perform the least invasive and most informative diagnostic imaging modalities that corroborate the biochemical and histologic findings to establish the definitive diagnosis. Unrecognized, misdiagnosed, or improperly treated disturbance of bone growth can result in permanent deformity usually associated with disability.

Bone Diseases, Developmental↗
PubMed1984

Intrinsic and extrinsic control of growth in developing organs.

The growth rate and final size of developing organs is controlled by organ-intrinsic mechanisms as well as by hormones and growth factors that originate outside the target organ. Recent work on Drosophila imagined discs and other regenerating systems has led to the conclusion that the intrinsic growth-control mechanism that controls regenerative growth depends on position-specific interactions between cells and their neighbors, and that these interactions also control pattern formation. According to this interpretation, local growth by cell proliferation is stimulated when cells with disparate positional information are confronted as a result of grafting or wound healing. This local growth leads to intercalation of cells with intervening positional values until the positional information discontinuity is eliminated. When all discontinuities have been eliminated from a positional field, growth stops. In this article we consider the possibility that organ growth during normal development may be controlled by an intercalation mechanism similar to that proposed for regenerative growth. Studies of imaginal disc growth are consistent with this suggestion, and in addition they show that the cell interactions thought to control growth are independent of cell lineage. Developing organs of vertebrates also show intrinsic growth-control mechanisms, as demonstrated by the execution of normal growth programs by immature organs that are transplanted to fully grown hosts or to hosts with genetically different growth parameters. Furthermore, these organ-intrinsic mechanisms also appear to be based on position-specific cell interactions, as suggested by the growth stimulation seen after partial extirpation or rearrangement by grafting. In organs of most adult vertebrates, the organ-intrinsic growth-control system seems to be suppressed as shown by the loss of regenerative ability, although it is clearly retained in the limbs, tails and other organs of salamanders. The clearest example of an extrinsic growth regulator is growth hormone, which plays a dominant role along with insulin-like growth factors, thyroid hormone and sex hormones in supporting the growth of bones and other organs in postnatal mammals. These hormones do not appear to regulate prenatal growth, but other hormones and insulin-like growth factors may be important prenatally. The importance of other growth factors in regulating organ growth in vivo remains to be established. It is argued that both intrinsic and extrinsic factors control organ growth, and that there may be important interactions between the two types of control during development.

Ambystoma↗