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Developmental Markers (developmental + marker)
Selected AbstractsMandibular Morphology as an Indicator of Human Subadult Age: Interlandmark Approaches,JOURNAL OF FORENSIC SCIENCES, Issue 5 2007Daniel Franklin Ph.D. Abstract:, The dentition is widely recognized as the set of developmental markers that appear to show the least variability against chronological age; these markers are thus widely used in forensic anthropological investigations. As a possible alternative, we investigate here the potential of mandibular morphology as a developmental marker for estimating age at death in subadults. The sample analyzed comprises 79 known age and sex subadult individuals of South African Bantu and African American origin. Linear measurements of ramus height were obtained from the mathematical conversion of three-dimensional landmark data. A series of regression analyses were then performed to predict age by using the measurement of ramus height; results were cross-validated using a jackknife procedure. Our results show that ramus height can be used to predict age in the subadult skeleton with accuracy, closely approaching that of standards based on the dentition (standard error rates are between ±1.1 years and ±2.4 years). [source] Improved organotypic cell culture model for analysis of the neuronal circuit involved in the monosynaptic stretch reflexJOURNAL OF NEUROSCIENCE RESEARCH, Issue 2 2006Björn Dagberg Abstract Knowledge regarding neuronal circuit formation is central for the understanding of the vast network making up the brain. It is therefore necessary to find novel ways to analyze the mechanisms involved in well-defined neural circuits. We present an improved in vitro model of the monosynaptic stretch reflex circuit, based on primary organotypic cell cultures. By using limb tissue as a source of muscle fibers instead of circumspinal tissue we could make the in vitro system more in vivo like in the sense that it focuses on the stretch reflex involving limb muscles. Furthermore, our analyses showed that this procedure allows muscle fibers to follow the normal developmental pattern. Particularly interesting was the finding of slow tonic myosin heavy chain expressing muscle fibers, a developmental marker for muscle spindles, in the cultures showing that this system has the potential to contain the complete reflex circuits. © 2006 Wiley-Liss, Inc. [source] Mandibular Morphology as an Indicator of Human Subadult Age: Interlandmark Approaches,JOURNAL OF FORENSIC SCIENCES, Issue 5 2007Daniel Franklin Ph.D. Abstract:, The dentition is widely recognized as the set of developmental markers that appear to show the least variability against chronological age; these markers are thus widely used in forensic anthropological investigations. As a possible alternative, we investigate here the potential of mandibular morphology as a developmental marker for estimating age at death in subadults. The sample analyzed comprises 79 known age and sex subadult individuals of South African Bantu and African American origin. Linear measurements of ramus height were obtained from the mathematical conversion of three-dimensional landmark data. A series of regression analyses were then performed to predict age by using the measurement of ramus height; results were cross-validated using a jackknife procedure. Our results show that ramus height can be used to predict age in the subadult skeleton with accuracy, closely approaching that of standards based on the dentition (standard error rates are between ±1.1 years and ±2.4 years). [source] Skeletal age, dental age, and the maturation of KNM-WT 15000AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2004Shelley L. Smith Abstract The skeleton of the Homo erectus boy from West Lake Turkana, Kenya (KNM-WT 15000), is remarkably complete, and this individual has thus provided a case study for several researchers examining Homo erectus growth. Using data from a longitudinal study of Montreal French-Canadian children, it is shown that while dental and skeletal ages match reasonably well at the level of a sample of children, individuals can display differences between skeletal and dental ages of 2 years or more. Furthermore, the relationship between these two markers may change over time in individual children. It is also possible to find children with patterns of dental maturation similar to KNM-WT 15000's pattern in the Montreal sample. Therefore, neither the discrepancy between skeletal age and dental age alone nor the pattern of dental maturation as assessed by dental stages precludes a human-like pattern of growth, including an adolescent growth spurt, for this individual. Some indicators (e.g., estimated body size for predicted age, and enamel formation) do suggest possible growth-patterning differences from modern humans, and therefore earlier maturation is a reasonable hypothesis, but caution is warranted, given the large degree of modern human variation in developmental markers and the inherent uncertainty in precise estimation of KNM-WT 15000's maturational parameters. Am J Phys Anthropol, 2004. © 2004 Wiley-Liss, Inc. [source] Gestational stage sensitivity to ultrasound effect on postnatal growth and development of miceBIRTH DEFECTS RESEARCH, Issue 8 2006Suresh Rao Abstract BACKGROUND: An experiment was conducted to find out whether ultrasound exposure leads to changes in postnatal growth and development in the mouse. METHODS: A total of 15 pregnant Swiss albino mice were exposed to diagnostic levels of ultrasound (3.5 MHz, 65 mW/cm2, ISPTP = 1 mW/cm2 Intensity(Spatial Peak-Temporal Peak), ISATA = 240 mW/cm2 Intensity(Spatial Average-Temporal Average)) for 30 min for a single day between days 10 and 18 of gestation (GD 10,18). Virgin female mice were placed with same age group males for mating in the ratio 2 females : 1 male and examined the next morning for the presence of vaginal plug, a sign of successful copulation. The females with vaginal plugs were separated and labeled as 0-day pregnant. Maternal vaginal temperature was also measured. A sham exposed control group of 15 pregnant mice was maintained for comparison. All exposed as well as control animals were left to complete gestation and parturition. Their offspring were used in our further studies. They were monitored during early postnatal life for standard developmental markers, postnatal mortality, body weight, body length, head length, and head width, and growth restriction was recorded up to 6 weeks of age. RESULTS: An exposure to ultrasound induced nonsignificant deviations in the maternal vaginal temperature or developmental markers. Significant low birth weight was observed in the present study, after exposure at GD 11, 12, 14, and 16. However, 14 and 16 days postcoitus during the fetal period appears to be the most sensitive to the ultrasound effect, in view of the number of different effects as well as severity of most of the observed effects when exposed on these gestation days. CONCLUSIONS: The results indicate that diagnostic ultrasound can induce harmful effects on mouse growth and development when given at certain critical periods of gestation. Birth Defects Research (Part A) 76:602,608, 2006. © 2006 Wiley-Liss, Inc. [source] | ||||||||||