References: Hair growth and hair loss
J Med Entomol. 1997 Jul;34(4):485-8.
Effect of juvenile hormone and juvenile hormone mimics on sperm transfer from the testes of the male cat flea (Siphonaptera:Pulicidae).
Dean SR, Meola RW.
Department of Entomology, Texas A&M University, College Station 77843, USA.
Sperm transfer into the epididymis was completed without a blood meal, when newly emerged male cat fleas. Ctenocephalides felis (Bouche), were exposed to filter papers treated with juvenile hormone III or the juvenile hormone mimics fenoxycarb, methoprene, or pyriproxyfen. As the concentration of juvenile hormone or the time of flea exposure to juvenile hormone or the juvenile hormone mimics increased, the percentage of fleas that transferred sperm also increased. The percentage of pyriproxyfen-treated males that transferred sperm reached 100% after 3 d: whereas, 7 d exposure to juvenile hormone, fenoxycarb and methoprene was required for 100% of the males to transfer sperm. Although sperm were present in the epididymis of treated fleas, insemination of females did not take place off the host either on juvenile hormone-treated filter paper or on juvenile hormone-treated dog hair.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9220683&dopt=Abstract
Exp Cell Res. 1997 Jul 10;234(1):37-46.
Induction of apoptosis through the PKC pathway in cultured dermal papilla fibroblasts.
Ferraris C, Cooklis M, Polakowska RR, Haake AR.
Department of Dermatology, University of Rochester School of Medicine and Dentistry, New York 14642, USA.
The dermal papilla (DP) consists of a discrete population of specialized fibroblasts that are important in the morphogenesis of the hair follicle in the embryo and in the control of the hair growth cycle in the adult. This mitotically quiescent and long-lived cell population expresses gene products that promote cell survival such as Bcl-2, and thus normally might be protected from apoptosis. We investigated whether cultured DP fibroblasts are able to undergo apoptosis by treatment with the protein kinase inhibitor staurosporine. Involvement of the PKC signaling pathway in DP fibroblast survival/death was investigated by inhibition (staurosporine and Bisindolylmaleimide (Bis) treatment) or activation (TPA; 12-O-tetradecanoylphorbol-13-acetate treatment) of PKC and characterization of DP-expressed PKC isoforms by RT-PCR. We determined that cultured DP fibroblasts undergo apoptosis, in a dose-related manner, when treated with staurosporine but not when treated with Bis, an inhibitor with narrow PKC isoform specificity. TPA confers partial and transient resistance to staurosporine-induced DP apoptosis. Staurosporine and Bis each induced G1 arrest, whereas TPA treatment of cultured DP resulted in increased entry into S-phase. The differential responses to individual inhibitors and activators of PKC may be related to the multiple PKC isoforms that DP fibroblasts express. Flow cytometric analysis indicates that the mechanism of staurosporine-induced apoptosis may be through decrease of Bcl-2 in treated DP cells or through modulation of cell cycle regulators. Correlation between sensitivity to induction of apoptosis and proliferation suggests that dermal papilla cells may normally be protected from apoptosis in vivo by their mitotically quiescent state.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9223368&dopt=Abstract
Acta Anat (Basel). 1996;157(3):169-82.
Changing patterns of cell adhesion molecules during mouse pelage hair follicle development. 1. Follicle morphogenesis in wild-type mice.
Hardy MH, Vielkind U.
Department of Biomedical Sciences, University of Guelph, Ont., Canada.
The morphogenesis of hairs is initiated and maintained by reciprocal interactions between groups of epithelial and mesenchymal cells. To examine whether cell adhesion molecules play a role in this process, prenatal distribution patterns of various cell adhesion molecules were studied during hair follicle morphogenesis in the dorsal skin of C57BL mouse embryos, using monoclonal antibodies. E-cadherin was present on all epithelial cells of the skin when the ectoderm gave rise to periderm and epidermis. E-cadherin was reduced in the follicle placodes and hair plugs, then disappeared from the presumptive hair matrix of elongating follicles. P-cadherin was initially present on all cells of periderm and epidermis and was later retained at a reduced level in the basal epidermal layer. P-cadherin was prominent in all follicle placodes and hair plugs and in the presumptive hair matrix of elongating follicles. N-CAM was present on all mesenchymal cells of the presumptive dermis at the prefollicle stage, then temporarily restricted to a few cells just below the dermal-epithelial junction. Later, N-CAM reappeared in the interfollicular mesenchyme and was prominent in the mesenchymal sheath and dermal papilla of elongating follicles. In addition, N-CAM was expressed in the hair plugs, then became progressively restricted to the upper caudal part of the elongating follicles. The results suggest that the main role of cell adhesion molecules is to mould the follicle by relaxing or reinforcing cell contacts in areas of increased morphogenetic activity.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9226036&dopt=Abstract
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