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Results for “Human Development”

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At least 19 recordsLinked to original sources
PubMed1978

Changes of the ratio between myelin thickness and axon diameter in the human developing sural nerve.

Axon caliber and myelin sheath thickness of individual nerve fibers were evaluated in the developing human sural nerve using three different methods of measurement: 1. ocular micrometer evaluation of large fibers, 2. photographic enlargements for evaluating large numbers of nerve fibers of all sizes, and 3. electron microscopic enlargements for more precise measurements in selected nerves. The average axonal diameter doubles from 5 months gestation to about 5 years of age. Large fiber group axons increase, during the same period, by a factor of 3--3.5 with a slight decrease thereafter. The myelin thickness increases more slowly, but continuously, between 5 months gestation until the age of 14. This asynchronous development of axons and myelin sheaths results in a statistically significant change of the ratio between axonal caliber and myelin thickness. The slope of the regression line is steeper in older than in younger individuals, and the correlation coefficient increases during development of the nerve.

Adolescent↗
PubMed1992

Expression and amplification of cellular oncogenes in human developing placenta and neoplastic trophoblastic tissue.

To confirm the expression of cellular oncogenes during normal development, their differential RNA levels in developing human placenta have been studied using radioactive probes such as v-abl, v-erbA, v-fms, v-mos, v-myc, N-ras and v-src. The c-mos and N-ras genes are expressed and amplified at high levels especially in term placenta, while c-abl, and c-erbA are expressed constantly during development. These findings indicate that c-mos and N-ras genes may be closely linked to normal differentiation, although c-abl and c-erbA may participate in overall developmental processes. In contrast, transcripts of c-myc and c-src are enhanced at first trimester and decreased sequentially thereafter, showing that these genes may play a role in early proliferation. Expression patterns of c-fms gene are same as that of c-myc and c-src except reelevation at term. In addition, to characterize the effect of cellular oncogene expression has been also examined in hydatidiform mole and tumor cells such as BeWo and choriocarcinoma. All cellular oncogenes examined in this study were significantly overexpressed. Thus, our results suggest that cellular oncogene activation may be strongly associated with neoplastic change of trophoblast.

DNA Probes↗
PubMed1991

Opioid receptors localize to the external granular cell layer of the developing human cerebellum.

The distribution of opioid receptors in the developing human cerebellum was determined by tissue autoradiography using [3H]naloxone. In infants, opioid receptors were heavily concentrated in the external granular layer, a matrix of germinal cells, and were substantially less concentrated in the internal granular layer, differentiating progeny of external granular cells. In the mature internal granular layer of the child and adult, opioid receptors were negligible. Thus, in the human cerebellum, opioid receptors localize to a population of germinal cells and are negligible in their mature progeny. These data support the idea that endogenous opioids play a role in human brain development and may function as receptor-mediated growth factors. The cerebellum provides a model site to examine abnormal opioid effects upon human brain development, particularly in infants exposed to narcotics in utero.

Cell Differentiation↗
PubMed1979

Early human development and the chief sources of information on staged human embryos.

In a brief historical survey, the importance of Wilhelm His, senior, to human embryology is emphasized. He provided the impetus to Mall to establish the Carnegie Embryological Collection, which serves as a 'Bureau of Standards' for early human development. The Carnegie system of 23 stages for the embryonic period proper (first 8 postovulatory wk) is outlined, and some common misusages are noted. Finally, because of the difficulty in tracking down data based on staged human embryos, an annotated list of more than 40 key references is provided.

Embryology↗
PubMed1992

Insulin-like growth factor II expression in the developing human brain.

Insulin-like growth factor II (IGF-II) is a polypeptide hormone with insulin-like metabolic activity and neurotrophic activity in vitro that has been implicated in human brain development. In this study, we used northern blot analysis to examine the patterns of IGF-II mRNA expression in selected regions of 18 human brains from cases ranging in age from 20 gestational weeks to 2.5 years (median age 31 gestational weeks). The expression of IGF-II mRNA was widespread throughout the brain from midgestation through the perinatal period. Each region showed a distinct developmental pattern of expression and IGF-II mRNA levels varied considerably between regions. The highest levels of expression at all ages were in leptomeninges and choroid plexus. After two postnatal months, IGF-II mRNA virtually disappeared from parenchymal regions. Beyond the perinatal period, IGF-II expression persisted primarily in choroid plexus. Transcripts of both 6.0 and 4.8 kb were detected in most brain regions. A developmental change in the relative amounts of the two transcripts occurred in choroid plexus, leptomeninges and medulla. The expression of IGF-II mRNA in the brain parenchyma during the last half of gestation correlates with a period of major brain growth and supports the hypothesis that high levels of IGF-II stimulate the proliferation and differentiation of neural cells early in development.

Blotting, Northern↗
PubMed1979

Human development through occupation: a philosophy and conceptual model for practice, part 2.

The development of a philosophy of practice called "human development through occupation" is described in this paper. This philosophy was developed through study and identification of generic concepts in four major theoretical frameworks for occupational therapy described in a preceding article. The philosophy of practice proposes a view of Man, a view of human health, and a view of the profession. These theoretical and philosophical resources are then used to construct a conceptual model of the content and sequence of the occupational therapy practice process. It is believed that the four theoretical frameworks, philosophy of practice, and conceptual model detailed in these two papers can provide direction for general practitioners and specialists in service, education, and research. Examples of application are included, together with suggestions for further investigation.

Health↗
PubMed2025

Human development, inequality, and their associations with brain structure across 29 countries.

BACKGROUND: The macro-social and environmental conditions in which people live, such as the level of a country's development or inequality, are associated with brain-related disorders. However, the relationship between these systemic environmental factors and the brain remains unclear. We aimed to determine the association between the level of development and inequality of a country and the brain structure of healthy adults. METHODS: We conducted a cross-sectional study pooling brain imaging (T1-based) data from 145 magnetic resonance imaging (MRI) studies in 7,962 healthy adults (4,110 women) in 29 different countries. We used a meta-regression approach to relate the brain structure to the country's level of development and inequality. RESULTS: Higher human development was consistently associated with larger hippocampi and more expanded global cortical surface area, particularly in frontal areas. Increased inequality was most consistently associated with smaller hippocampal volume and thinner cortical thickness across the brain. CONCLUSIONS: Our results suggest that the macro-economic conditions of a country are reflected in its inhabitants' brains and may explain the different incidence of brain disorders across the world. The observed variability of brain structure in health across countries should be considered when developing tools in the field of personalized or precision medicine that are intended to be used across the world.

Humans↗
PubMed1992

Expression of thymosin beta-4 and related genes in developing human brain.

The retinoic acid-responsive thymosin beta-10 gene is known to be developmentally regulated in the human brain. We now report the novel finding that thymosin beta-4, a structurally related 5-kDa actin-sequestering protein, is also subject to a similar but not identical pattern of expression during normal human neuroembryogenesis. However, while thymosin beta-10 mRNA was undetectable (by northern blot analysis) in adult human brain, levels of thymosin beta-4 mRNA, although greatly reduced, were still present. Moreover, a novel thymosin beta-10-like gene was also found to exhibit a unique stage-specific expression during early human neural development. These experiments, together with previous findings, indicate that the products of the two thymosin genes, possibly in association with cytoskeletal elements, may play different roles during early neuroembryogenesis and neural maturation.

Adult↗
PubMed2025

Recent evolution of the developing human intestine affects metabolic and barrier functions.

Diet, microbiota, and other exposures make the intestinal epithelium a nexus for evolutionary change; however, little is known about genomic changes associated with adaptation to a distinctly human environment. In this work, we interrogate the evolution of cell types in the developing human intestine by comparing tissue and organoids from humans, chimpanzees, and mice. We find that recent changes in primates are associated with immune barrier function and lipid and xenobiotic metabolism and that human-specific genetic features affect these functions. Enhancer assays, genetic deletion, and in silico mutagenesis resolve evolutionarily important enhancers of lactase (LCT) and insulin-like growth factor binding protein 2 (IGFBP2). Altogether, we identify the developing human intestinal epithelium as a rapidly evolving system and show that great ape organoids provide insight into human biology.

Animals↗
PubMed1992

Effect of gamma-interferon on the expression of major histocompatibility complex class I and II gene products in neural cells isolated from the developing human fetal peripheral nervous system.

The effect of gamma-interferon (gamma-IFN) on the expression of major histocompatibility complex (MHC) gene products was examined in the developing human fetal peripheral nervous system. RNA blot hybridization analysis of total RNA isolated from human fetal dorsal root ganglia (DRG) neural cell populations cultured in vitro for 5 days resulted in the detection of both MHC class I- and class II-specific RNAs. As determined by protein immunoblotting and fluorescence-activated flow cytometry, MHC class I and II proteins were also readily detectable in cultured human fetal DRG neural cell populations 5 days after isolation. In addition, treatment of 3-day human fetal DRG neural cells with gamma-IFN (100 U/ml; 48 h) resulted in a marked increase in the level of MHC class I- and class II-specific RNA and protein without inhibiting the proliferation of the neural cell population. These results suggest that changes in the levels of selected cytokines such as gamma-IFN may alter the ability of specific neural cell populations present in the developing human nervous system to participate in immune reactions by alteration of MHC class I and II antigen expression which may lead to perturbation in glial cell function and ultimately to nervous system dysfunction in general.

Cell Division↗
PubMed1975

Light and electron microscopic studies of postcapillary venules in developing human fetal lymph nodes.

Developing lymph nodes from 30 human fetuses with crownrump lengths (CRL) of 38 mm (8.7 wk) to 245 mm (26 wk) were studied by light and electron microscopy. Blood vessels that appear to be postcapillary venules (PCV) are present in nodes of 47 mm CRL and older fetuses. These venules first appear in nodes whehn the nodal population of lymphocytes is sparse. In these early nodes PCV are distributed randomly and consist of a low endothelium, underlying basal lamina and incomplete pericyte sheath. Early nodal PCV are distinguised from other nodal blood vessels by the presence of lymphocyte diapedesis and several luminal lymphocytes. In the late stages of nodal development PCV are the more common non-capillary blood vessel and appear in the parenchyma near the periphery of the node. Late nodal PCV are generally characterized by a cuboidal endothelium that is rich in Golgi apparatus, lysosomes and Weibel-Palade bodies. The lumen and wall of late nodal PCV contain lymphocytes. The relationship between the development of the parenchyma of fetal nodes and the appearance and activity of PCV, the passage of lymphocytes through the PCV wall and the fine structure of developing PCV are described. It is suggested that the lymphocytes that first appear in developing nodes, and the majority of the lymphocytes found in late nodes, migrate to the node via the blood vascular system and enter the nodal parenchyma by passing across PCV endothelium.

Abortion, Spontaneous↗
PubMed1979

Human development through occupation: theoretical frameworks in contemporary occupational therapy practice, part 1.

In 1968, the report of a conference sponsored by the American Occupational Therapy Association called for the development of an integrated theory of occupational therapy. A review of the practical problems faced by therapists today, contrasted with major developments in the art and science of the field during the past decade, suggests that this goal has not been attained. However, three major theoretical frameworks for therapy have evolved through the work of Fidler and Mosey, Wilbarger, and Llorens, who participated in the conference on theory. Reilly and associates developed a fourth framework of significance. Through analysis of theoretical constructs, generic concepts that characterize occupational therapy can be identified. Theoretical constructs and research validation of the four approaches to occupational therapy are discussed in this article. A second article to appear in a subsequent issue of AJOT illustrates the use of the four theoretical frameworks to derive a philosophical basis for practice and a model of the practice process called "human development through occupation."

Human Development↗
PubMed1992

[Transcription activity of ribosomal genes in the pre- and postnatal periods of human development].

Transcriptional activity of silver-stained nucleolar-organizing region (NOR) of human chromosomes was studied in 50 medical abortuses at 6-12 weeks of gestation and 125 healthy individuals from 20 to 85-years-old. Transcriptional activity of rRNA genes was higher at the prenatal period of ontogenesis than at the postnatal period. Decline in total activity of ribosomal genes in both sexes was shown. Linear regression coefficients of the NOR activity in dependence of age satisfactorily predict the level of total NOR activity at the prenatal period of human development.

Adult↗