Growth Development and Aging最新文献

Data are presented on the pattern of organ growth in the Common Tern, a semi-precocial bird species with a high growth rate, and are compared with data from some bird species within the altricial-precocial spectrum. The data show that a high growth rate is linked to a growth pattern characterized by a rapid early development of the digestive organs and a late development of pectoral muscles and feathers. These results suggest that the growth rate is most likely restricted by the capacity to ingest and digest food. It also appears that the organ growth pattern is more closely related to the growth rate than to the degree of precocity.

Anthropometry is widely used to monitor infant growth and to estimate child nutritional status. Current evidence suggests that existent growth curves are not adequate for use with all infants and researchers sought to identify another data set suitable for development as a new international growth reference. In this article we cast about unconditional limits for growth monitoring from raw data on age, sex, height and weight. Anthrompometric data from children aged 1 to 9 years from two studies on malnutrition in Brazil was analyzed. Data on age, sex, weight, height and body mass index from 141 Amerindian children was used to develop mathematical models to predict percent of NCHS medians for weight-for-age, weight-for-height, and height-for-age using multiple linear regression. Data from 251 children in a non-indian seaside village was used for cross-validation. Six age-specific equations were obtained with coefficients of determination greater than 0.96. Coefficients of correlation between NCHS-derived and model-derived values into the validation data set were greater than 0.96 for weight-for-age, greater than 0.99 for weight-for-height, and near 1.00 for height-for-age. It remains to be seen if one can achieve universal linear models from more representative samples, using the approach described here. Perhaps establishing a mathematical relation among anthropometric data would result in absolute individual limits for growth monitoring. They may even be as important to infant nutritional assessment as growth reference values.

Two experiments were conducted to assess the role of the yolk sac during the perinatal period (i.e., from embryonic Day 18 through hatch) and until 15 days after hatching. Experiment 1 describes changes in several yolk components. Approximately 70% of the yolk was absorbed during the perinatal period. Moisture, lipid, protein, and carbohydrate fractions were all utilized during this period. In Experiment 2, the age at which set-point physiological levels of several blood metabolites, as well as the magnitudes of these levels, in deutectomized (DT) chicks (surgical ablation of the yolk sac within 1 hr post-hatch) were not different from non-DT controls. Results indicate that the yolk sac plays a central role in the hatching process of chicks, rather than serving as a major metabolic reserve during the neonatal period.

Growth of chick embryonic femora, tibiotarsi and first phalanges of digit three were measured at one day intervals from day 6 through 16 of incubation. Normal controls were compared to embryos paralyzed at 5 days of incubation. Over the 10 day study period, length of the paralyzed femora, length and width of the paralyzed tibiotarsi and differences in length of the phalanges were observed. Growth in length of phalanx one of digit three was most affected by paralysis over this period. Changes in shape of these bones also occurred during growth. Normal long bones undergo changes in shape as differential growth in length and width occurs. Such changes in shape can be considered as the bone's normal growth "trajectory". Paralyzed bones displayed a different growth trajectory than normal bones. As expected, the long bones of paralyzed embryos were shorter than age-matched controls. Contrary to expectations, however, paralyzed long bones were relatively more stout than age-matched controls.

It has been reported that the amount of D-aspartic acid in dentin is highly correlated with age. However, further studies are necessary to determine the details of this correlation. We quantitatively determined L- and D-aspartic acids in dentin, and from the data calculated the D/L ratio. We did not find any statistically significant difference in the D/L ratio between the same type of left and right teeth from the same jaw, and between the vestibular and lingual sides of the root dentin. However, the D/L ratio was significantly higher on the lingual side than on the labial side of the dentin. Although the D/L ratio in young subjects was comparatively high in the tooth crown and decreased toward the apex of the root, we did not always observe such a tendency in middle- to advanced-age individuals. These results indicate that the ratio of D/L aspartic acid in dentin varies between the lingual side and vestibular side of the crown dentin. Therefore, it appears that the racemization rate of aspartic acid is not uniform but differs with the region of the dentin, and may be affected by differences in factors such as temperature.

The brushtail possum, Trichosurus vulpecula, produces a single offspring 200 mg in body weight. The young grow slowly during the first half of pouch of life at approximately 1g/day. At day 96 post partum the growth rate increases dramatically and it has been suggested that this change in growth rate may result from the initiation of thyroid function in the young possum. To determine the role of the thyroid gland of the possum on growth, the production of hormones from the thyroid was inhibited by administration of the drug, methimazole. The drug was administered to adult and young possums at day 140 post partum for 28 days and to young at day 100 post partum for 42 days and the effects of this treatment on plasma concentrations of thyroxine and on growth were monitored. Methimazole was found to inhibit thyroxine production in 4 of the 6 adult possums although it had no effect on body weight. Similar treatment administered to nine young possums inhibited growth. The three surviving methimazole possum young treated at 100 days post partum weighed less than control possums after day 163 post partum. The four young treated at 140 days post partum also showed depression in growth rate. However, the depression was not as marked as that of the 100 day treated possums. It is highly likely therefore that the surge in growth rate in the possum at day 96 post partum is initiated by thyroxine produced by the thyroid gland of the young.

Industrially employed PCB has caused wide-spread environmental contamination through improper disposal and has been associated with detrimental physiological states in exposed organisms, including depressed body weight, food consumption, and circulating levels of T4 and T3. Previously, the activity of choline acetyltransferase (ChAT) in the basal forebrain and hippocampus was shown to be depressed in young rats exposed to the PCB diet from the time of conception. The present study measured the neurochemical effects of similar PCB exposure in older (i.e., 60 day old) rats, and examined possible restoration of PCB-induced deficits by removing PCB at weaning (28 days). Possible PCB-induced impairment of memory was also evaluated with a radial arm maze. Findings included a significant depression of circulating levels of T4 in all treatment groups with the most profound depression seen in rats continuously fed PCB. Also, T3 levels and relative thyroid weights were not found to be severely depressed. The ChAT activity in both the basal forebrain and hippocampus was not different from control in all treatment groups. It appears that the effect of PCB on thyroxine is persistent, but its influence on ChAT activity is not. However, modest memory deficits were observed despite normal ChAT activity. Average number of working memory errors per test session in the maze increased in a dose-dependent manner across treatment groups.

The estimation of the parameters of a nonlinear model by means of the maximum likelihood procedure is widely used in the study of growth phenomena. The accuracy with which these parameters are calculated is a function of the number of measures taken and particularly, of their distribution across the growth period. If the growth curve is only partially known, the inaccuracy can increase considerably. However, if we have information on the distribution of the parameters of a model in the population, the empirical Bayes method should be used. In this paper, the principle of this approach for nonlinear modeling was recalled. The method was then applied on data of human height. Four nonlinear models are used and their performances are compared. The results show the importance of information on the quality of estimates of growth parameters and consequently on the prediction of adult height.

As far as we know, there is no available information about ontogenic changes of tissue concentrations of IGF-I and II and IGFBPs in large mammals. Serum, liver and kidney levels of IGFs and IGFBPs were examined in fetuses at 90 and 110 days of gestation and in pigs at 1d, 3 wk, 3 mo and 6 mo of age. Ontogeny of mRNA levels of IGFs, IGF type I and type II receptors (IGFI-R and IGFII-R), IGFBP-1 and -3 (IGFBPs) and growth hormone receptor (GHR) were also examined by Northern blot analysis in liver, kidney and skeletal muscle of pig. Serum IGF-I, IGF-II and IGFBP-3 concentrations were low during the fetal life and increased after birth. The highest level of IGF-II mRNA was found in fetuses for all studied tissues. In the liver, IGF-I mRNA level and its protein content peaked at 3 wk of age. The highest IGF-II concentration was found at 1d and 3 wk of age. The IGFII-R mRNA remained at a constant level during the whole development period. The most abundant IGFBP-1 mRNA and its protein content were found at birth. The level of IGFBP-2 was high during fetal and early postnatal life. The IGFBP-3 content was relatively low in fetuses and reached the highest level after 3 wk of age. In the kidney, IGFs, IGFBP-3, IGFI-R and IGFII-R as well as GHR mRNA levels were relatively high during the fetal and early postnatal life. The IGFs concentrations were the highest in newborns. In the skeletal muscle, IGFs, IGFBP-3 and IGFI-R mRNA levels decreased with advancing age. During the postnatal life, the high IGFs concentrations in the liver and the kidney correspond to fast growth periods of these organs.

We hypothesized that abnormal capillary formation, which might be associated with an alteration in extracellular malular matrix (ECM), occurs in the alveoli of growing rat lungs treated with beta-aminopropionitrile (beta APN), a lathyrogen that inhibits lysyl oxidase activity. On scanning electron microscopy, a corrosion cast of alveolar capillaries in lungs treated with beta APN appeared abnormal in configuration; transmission electron microscopy showed extensive morphological changes in interstitial cells and ECMs, including collagen, elastin, and presumably glycosaminoglycans and, in binding water (GBW). Morphometric data revealed an increase in GBW of up to 24.4%, a decrease in the amount of collagen fiber (44.5%), and a decrease in lipid-laden interstitial cells; however, the change in elastin was limited to morphological appearance. From these observations, we conclude that alterations in alveolar capillary formation are associate with extensive changes in ECMs, and that these changes in ECM components might also be involved in the abnormal alveolar formations induced by beta APN.