References: Hair growth and hair loss
Br J Dermatol. 1997 Feb;136(2):159-65.
The cross-sectional size and shape of human terminal scalp hair.
Hutchinson PE, Thompson JR.
Department of Dermatology, Leicester Royal Infirmary, UK.
Change in size of the hair shaft with distance form the scalp has been investigated, using a rotatory profile method of diameter measurement, in terminal human scalp hair of long-haired young Caucasian women. As the whole length of hairs having completed anagen are rarely found intact, two types of hair were investigated: those including segments produced at the onset of anagen ('anagen hairs'), and those including segments produced at the end of anagen ('telogen hairs'). In addition, a method of determining the cause of any size variation has been described and employed. Changes were found in the major axis of the hair cross-section, cross-sectional area and ellipticity with distance from the scalp, while the minor cross-sectional axis remained constant. It was established that these changes were the result of intrafollicular rather than extrafollicular mechanisms. Finally, a composite picture of the cross-sectional size and shape of the 'average' whole anagen hair of the study has been constructed. From the distal tip towards the scalp for approximately 6-8 cm, there was an abrupt increase in size, representing a starting-up phase of early anagen. Following this, the hair was at its greatest cross-sectional size and ellipticity which then progressively decreased through anagen (20% decrease for cross-sectional area and 13% for ellipticity). In contrast, the minor axis of the hair cross-section, remained constant throughout anagen. The hair was not therefore a uniformly sized cylinder. It was approximately spear-shaped, being broadened out in one plane distally where it was more elliptical. Subsequently as anagen progressed the hair shaft became smaller and more circular.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9068724&dopt=Abstract
Neuroscience. 1997 Apr;77(3):673-82.
Calcium currents in dissociated cochlear neurons from the chick embryo and their modification by neurotrophin-3.
Jimenez C, Gireldez F, Represa J, Garcia-Diaz JF.
Instituto de Biologia y Genetica Molecular, Universidad de Valladolid, Spain.
Calcium entry through voltage-dependent channels play a critical role in neuronal development. Using patch-clamp techniques we have identified the components of the macroscopic Ca2+ current in acutely-isolated chick cochlear ganglion neurons and analysed their functional expression throughout embryonic development. With Ba2+ as a charge carrier, the currents exhibited two main components, both with a high activation threshold but differing in their inactivation kinetics. One component showed inactivation with a time constant around 100 ms (transient) whereas the other hardly inactivated (sustained). The currents were sensitive to omega-Conotoxin GVIA and dihydropyridines, blocked by 20 microM Cd2+, but unaffected by omega-Agatoxin IVA. In a few cases, only with Ca2+ as a charge carrier, an additional component with low activation threshold and fast inactivation (time constant of 20 ms), was observed. Currents were first detected at day 7 of embryonic development. Current density (amplitude/cell capacitance) increased through embryonic day 9, when early synaptic contacts are established, and decreased thereafter to lower steady values. The effect of neurotrophin-3, a neurotrophic factor required for survival and differentiation of cochlear ganglion neurons, was also examined. Neurons isolated at embryonic day 7 or day 11 and maintained two days in culture with 2 ng/ml neurotrophin-3 showed a substantial increase in Ca2+ current density, particularly in the transient component. These findings indicate that the expression of neuronal Ca2+ channels is predominant at the time of synapse formation between transducing hair cells and their primary afferents. Besides its effects on survival and neuritogenesis, neurotrophin-3 enhances the expression of Ca2+ channels in cultured neurons. Taken together these results suggest that the functional expression of Ca2+ channels is regulated during embryonic development of cochlear neurons by the release of neurotrophin-3 from the differentiating sensory epithelium of the cochlea.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9070744&dopt=Abstract
Lipids. 1997 Mar;32(3):293-302.
Incorporation of long-chain n-3 fatty acids in tissues and enhanced bone marrow cellularity with docosahexaenoic acid feeding in post-weanling Fischer 344 rats.
Atkinson TG, Barker HJ, Meckling-Gill KA.
Department of Human Biology and Nutritional Sciences, University of Guelph, Ontario, Canada.
We wanted to examine the effects of an oil rich in docosahexaenoic acid (DHA), without eicosapentaenoic acid, on the composition of membrane phospholipid in a variety of tissues. Our in vitro studies had previously shown that DHA could modify glucose and nucleoside transport in cells in culture and also increase selectivity of the nucleoside drug, arabinosylcytosine (araC) toward tumor cells. Here we wanted to examine what effect DHA supplementation would have in the whole animal in terms of the chemosensitivity of normal bone marrow, the dose-limiting tissue during chemotherapy, to araC. The purpose was to determine whether fatty acid supplementation might be useful as an adjuvant to chemotherapy. We fed diets containing 5% (w/w) low fat-corn oil (LF-CO group), 10% moderate fat-safflower oil (MF-SO group), or 10% DHASCO (MF-DHA group) to weanling Fischer 344 rats for 8-9 wk. Feed intake and growth were not different between the different diets. Similarly, treatment of animals with the chemotherapeutic drug araC did not differentially affect growth, feed intake, or tissue fatty acid composition for the different diet groups. Fatty acid compositions of bone marrow, liver, red blood cells, plasma phospholipid and triglyceride, as well as skeletal and cardiac muscle, were substantially different between the dietary groups. The DHASCO oil contained 46% DHA (22:6n-3) and resulted in profound incorporation of DHA in all tissues examined. The most dramatic response was seen in skeletal muscle of MF-DHA fed animals where DHA represented 46% of membrane phospholipid fatty acids. This is likely to have consequences to muscle function. Although DHASCO contains a similar level of saturated fatty acids (42%), few differences in saturates were noted between the various dietary groups for most of the tissues examined. Both LF-CO and MF-SO diets were hypercholesterolemic, and the LF-CO was also hypertriglyceridemic compared to the chow-fed animals. Animals fed the MF-DHA diet had the lowest triglyceride levels of any of the treatment groups and cholesterol levels comparable to chow-fed animals. MF-DHA had substantially higher numbers of colony-forming units-granulocyte macrophage (CFU-GM) as reflected in a twofold higher bone marrow cellularity than either chow or LF-CO animals, suggesting expansion of the bone marrow compartment with DHA feeding. Although higher than LF-SO, the number of CFU-GM in MF-SO animals was not significantly higher than animals fed chow. Bone marrow from LF-CO animals appeared to be more resistant to araC treatment than either MF group. Thus, DHA, fed as DHASCO, has advantages over low or moderate n-6 diets and chow as it is has both hypolipidemic- and bone marrow-enhancing properties in weanling Fischer 344 rats. This suggests that DHA supplementation may be useful in adjuvant chemotherapy.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9076666&dopt=Abstract
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