References: Hair growth and hair loss
Percept Mot Skills. 2002 Jun;94(3 Pt 1):707-19.
Right-left discrimination in younger and older children measured with two tests containing stimuli on different abstraction levels.
Ofte SH, Hugdahl K.
Department of Biological and Medical Psychology, University of Bergen, Norway.
Two paper-and-pen tests, consisting of line drawings of human figures, viewed from the back, the front, or randomly alternating between back and front drawings, were used to study right-left discrimination in younger and older children. One test, called the Abstract test, had just a circle to indicate heads of the figures. The other test, called the Concrete test, showed facial characteristics and hair in the head circle. The sample consisted of 280 younger and older children, ages 7-8 and 12-13 years, respectively. The main findings were that participants who responded to the Concrete test solved more items correctly compared to those using the old figures in the Abstract test. The error scores did not differ between the tests. The older children solved more items correctly than the younger children. The older children also showed a significant decrease in correct scores on the subtest with the alternating views subtest compared with the other subtests. Their error scores did not differ across the subtests. The younger children solved a similar number of correct items on all subtests; however, they made significantly more errors on the subtest using the front view than on the other two subtests. The results are discussed in relation to theories of hemispheric lateralization, brain development, and cognitive development.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12081270&dopt=Abstract
Am J Clin Nutr. 2002 Jul;76(1):128-40.
Overexpression of arginase I in enterocytes of transgenic mice elicits a selective arginine deficiency and affects skin, muscle, and lymphoid development.
de Jonge WJ, Hallemeesch MM, Kwikkers KL, Ruijter JM, de Gier-de Vries C, van Roon MA, Meijer AJ, Marescau B, de Deyn PP, Deutz NE, Lamers WH.
Department of Anatomy and Embryology, Academic Medical Center, University of Amsterdam, Netherlands.
BACKGROUND: Arginine is required for the detoxification of ammonia and the synthesis of proteins, nitric oxide, agmatine, creatine, and polyamines, and it may promote lymphocyte function. In suckling mammals, arginine is synthesized in the enterocytes of the small intestine, but this capacity is lost after weaning. OBJECTIVE: We investigated the significance of intestinal arginine production for neonatal development in a murine model of chronic arginine deficiency. DESIGN: Two lines of transgenic mice that express different levels of arginase I in their enterocytes were analyzed. RESULTS: Both lines suffer from a selective but quantitatively different reduction in circulating arginine concentration. The degree of arginine deficiency correlated with the degree of retardation of hair and muscle growth and with the development of the lymphoid tissue, in particular Peyer's patches. Expression of arginase in all enterocytes was necessary to elicit this phenotype. Phenotypic abnormalities were reversed by daily injections of arginine but not of creatine. The expression level of the very arginine-rich skin protein trichohyalin was not affected in transgenic mice. Finally, nitric oxide synthase-deficient mice did not show any of the features of arginine deficiency. CONCLUSIONS: Enterocytes are important for maintaining arginine homeostasis in neonatal mice. Graded arginine deficiency causes graded impairment of skin, muscle, and lymphoid development. The effects of arginine deficiency are not mediated by impaired synthesis of creatine or by incomplete charging of arginyl-transfer RNA.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12081826&dopt=Abstract
bme.jhu.edu
Mobile intracellular calcium buffers play an important role in regulating calcium flux into mechanosensory hair cells and calbindin D-28k is expressed at high levels in the chick's basilar papilla. We have used RT-PCR, in situ hybridization, and immunohistology to demonstrate that calbindin expression varies systematically according to hair cell position and developmental age. RT-PCR using microdissected quarters of the posthatch basilar papilla showed that mRNA levels were lowest in the (low frequency) apex and higher in basal quadrants. In situ hybridization revealed calbindin mRNA in posthatch hair cells and supporting cells, with more intense labeling of hair cells from basal (high frequency) positions. A similar topology was obtained with calbindin antibodies. Neither calbindin riboprobe nor calbindin antibody labeled cochlear neurons. In contrast, a subset of large vestibular neurons and their calyciform endings onto Type I vestibu lar hair cells were strongly labeled by the calbindin antibody, while vestibular hair cells were negative for calbindin immunoreactivity. Likewise, calbindin in situ hybridization was negative for vestibular hair cells but positive in a subset of larger vestibular neurons. Calbindin mRNA was detected in hair cells of the basal half of the papilla at embryonic day 10 (E10) and calbindin immunoreactivity was detected at E12. Hair cells in the apical half of the papilla had equivalent calbindin expression two days later. Immunoreactivity appeared in abneural supporting cells days later than in hair cells, and not until E20 in neurally located supporting cells. These results demonstrate that calbindin message and protein levels are greater in high-frequency hair cells. This "tonotopic" gradient may result from the stabilization of a basal-to-apical developmental gradient and could be related at least in part to calcium channel expression along this axis.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12083720&dopt=Abstract
Lipitor
Herbs and Pharmaceuticals Online ||
Hair Million herbal formula for hair loss and hair growth ||
Hair growth research references ||