title: Prolactin signalling in murine hair growth

authors: Craven, A.J.

abstract: Although prolactin has been shown to entrain hair growth cycles in seasonally responsive mammals, no comparable role has been identified in the age-dependent pelage replacement of rodents. Prolactin binds to dimerised membrane-associated prolactin receptors (PRLR) on target organs and initiates signalling via a number of intracellular pathways including the JAK-Stat5b pathway. The role of this pathway in murine hair growth was investigated by (i) PRLR gene disrupted mice, (ii) altered circulating prolactin profiles and (iii) impaired PRLR signal transduction with Stat5b gene-disrupted mice. 
The long (PRLR-L), and two short (PRLR-S2 and PRLR-S3) forms of the prolactin receptor were shown by RT-PCR to be expressed in the skin. These receptors were immunolocalised to the outer root sheath of the follicle as well as the epidermis and sebaceous gland. The first hair replacement cycle in PRLR gene-disrupted mice was advanced by 4 days in males and 2 weeks in females compared to wild type controls. Similarly, bromocriptine suppression of prolactin secretion advanced hair replacement by four days, which could be reversed by administration of exogenous prolactin at 18-22 days of age. In contrast, hair replacement in Stat5b-disrupted mice was delayed by two weeks. The duration of anagen, measured as the period of fibre elongation, did not differ between treated and control groups in any of these experiments. Pelage structure, fibre length and fibre diameter was not substantially altered. Pelage renewal across the body was slower during pregnancy and pseudopregnancy, and halted completely during lactation. Only after weaning was follicle reactivation resumed. As a key gestational and lactation hormone, prolactin is a likely candidate as a modulator of hair cycling at this time. An inverse relationship between PRLR-L mRNA and prolactin mRNA demonstrates the high level of prolactin signal regulation in the skin during reproduction. 
Hence, both reduced circulating prolactin levels and PRLR-deficiency results in a shorter telogen and hair renewal at a younger age. In contrast, when the signalling protein Stat5b is absent, follicle growth was retarded and new hair growth occurred later than in wild type mice. This could be explained by the altered pituitary feedback regulation of lactotrophs resulting in hyperprolactinemia in Stat5b-deficient mice. These results provide strong evidence that prolactin inhibits the activation of murine hair follicle growth.

text: Prolactin signalling in murine hair growth Although prolactin has been shown to entrain hair growth cycles in seasonally responsive mammals, no comparable role has been identified in the age-dependent pelage replacement of rodents. Prolactin binds to dimerised membrane-associated prolactin receptors (PRLR) on target organs and initiates signalling via a number of intracellular pathways including the JAK-Stat5b pathway. The role of this pathway in murine hair growth was investigated by (i) PRLR gene disrupted mice, (ii) altered circulating prolactin profiles and (iii) impaired PRLR signal transduction with Stat5b gene-disrupted mice. 
The long (PRLR-L), and two short (PRLR-S2 and PRLR-S3) forms of the prolactin receptor were shown by RT-PCR to be expressed in the skin. These receptors were immunolocalised to the outer root sheath of the follicle as well as the epidermis and sebaceous gland. The first hair replacement cycle in PRLR gene-disrupted mice was advanced by 4 days in males and 2 weeks in females compared to wild type controls. Similarly, bromocriptine suppression of prolactin secretion advanced hair replacement by four days, which could be reversed by administration of exogenous prolactin at 18-22 days of age. In contrast, hair replacement in Stat5b-disrupted mice was delayed by two weeks. The duration of anagen, measured as the period of fibre elongation, did not differ between treated and control groups in any of these experiments. Pelage structure, fibre length and fibre diameter was not substantially altered. Pelage renewal across the body was slower during pregnancy and pseudopregnancy, and halted completely during lactation. Only after weaning was follicle reactivation resumed. As a key gestational and lactation hormone, prolactin is a likely candidate as a modulator of hair cycling at this time. An inverse relationship between PRLR-L mRNA and prolactin mRNA demonstrates the high level of prolactin signal regulation in the skin during reproduction. 
Hence, both reduced circulating prolactin levels and PRLR-deficiency results in a shorter telogen and hair renewal at a younger age. In contrast, when the signalling protein Stat5b is absent, follicle growth was retarded and new hair growth occurred later than in wild type mice. This could be explained by the altered pituitary feedback regulation of lactotrophs resulting in hyperprolactinemia in Stat5b-deficient mice. These results provide strong evidence that prolactin inhibits the activation of murine hair follicle growth.

year: 2003

title: Reinforced Sintered Cancellous Bovine Bone as a Potential Bone Replacement Material

authors: Laird, Dougal Frazer

abstract: This research was undertaken in order to investigate the possibilities of transforming a widely available waste bone resource into a viable human bone replacement biomaterial. Large quantities of bovine bone are available as a resource in New Zealand due to the presence of an extensive meat industry. Cancellous bone was harvested from within the condyle regions of bovine femoral bone by cutting with either band saw or lapidary saw. Portions of cut cancellous bovine bone were significantly defatted and partially deproteinated through repeated autoclaving. The material was then sintered at 1000°C for 3 hours to give a pristine white sintered cancellous bovine bone (SCBB) material, that although weakened in comparison to its original form, retained the porous trabecular architecture of the original cancellous bone. This material was characterised by means of Fourier transform infrared (FT-IR) spectroscopy and powder X-ray diffraction (XRD), while also being subjected to a washing experiment in distilled water with pH monitoring to show that the material was hydroxyapatite (HAp) (Ca10(PO4)6(OH)2) with small quantities of CaO. Scanning Electron Microscopy (SEM) showed that the SCBB material had retained its macroporous architecture, with higher magnification micrographs revealing a microporosity with channels through crystallites of the HAp of approximately 500 – 700 nm in diameter. Organic infiltrating solutions were prepared by dissolving chitosan in hydrochloric acid in addition to calcium phosphate, such as HAp or CaHPO4, to act as a mineral reinforcing material. Due to the limited solubility of HAp, the maximum concentration that could be achieved involving a 50 : 50 w/w combination of chitosan and HAp was 6 g L-1 for both materials in ~ 0.1 mol L-1 HCl. ε Polycaprolactone (PCL) dissolved in tetrahydrofuran (THF) was also trialled as an infiltrating solution, with concentrations up to 14 % w / v dissolved in the THF. Solutions were infiltrated into the porous SCBB material by means of vacuum, vacuum and pressure or a pressure only method. The extent of penetration of the infiltrate into the SCBB was followed by labelling the chitosan molecule with the fluorophore, Fluorescein Isothiocyanate (FITC) and then examining the infiltrated SCBB by fluorescence microscopy. After infiltration into the SCBB material, chitosan and mineral reinforcing were precipitated by an increase in pH. Several methods for increasing solution pH were trialled, including; the addition of urea into the infiltrating solution with subsequent thermal hydrolysis, the catalysis of urea by urease, and treatment with ammonia gas. By products and excess ammonia were shown to be able to be removed from the infiltrated SCBB by repeated washing in water and buffer solution. Mechanical testing on the infiltrated SCBB material was carried out by compression testing on an Instron materials testing instrument. Due to the inherent variability in the density and strength of the starting SCBB material, a statistical approach was required. Multiple samples were used and values for ultimate stress, modulus and a modified toughness measurement obtained from the mechanical testing for non-infiltrated SCBB samples were compared against infiltrated samples. SCBB samples infiltrated with a chitosan / CaHPO4 infiltrate displayed an improvement in ultimate stress, while samples infiltrated with PCL showed an overall increase in modulus. Finally, biocompatibility of the SCBB samples infiltrated with chitosan based infiltrates was tested using L929 fibroblast cell culture testing and a Hen’s Egg Test - Chorioallantoic Membrane (HET-CAM) test. Materials with low cytotoxic response were produced when sufficient washing and buffer treatment was employed after infiltration. This research proved that SCBB could be successfully infiltrated with an organic / mineral composite matrix, which was capable of modifying the mechanical properties of the SCBB, while displaying positive biocompatibility potential.

text: Reinforced Sintered Cancellous Bovine Bone as a Potential Bone Replacement Material This research was undertaken in order to investigate the possibilities of transforming a widely available waste bone resource into a viable human bone replacement biomaterial. Large quantities of bovine bone are available as a resource in New Zealand due to the presence of an extensive meat industry. Cancellous bone was harvested from within the condyle regions of bovine femoral bone by cutting with either band saw or lapidary saw. Portions of cut cancellous bovine bone were significantly defatted and partially deproteinated through repeated autoclaving. The material was then sintered at 1000°C for 3 hours to give a pristine white sintered cancellous bovine bone (SCBB) material, that although weakened in comparison to its original form, retained the porous trabecular architecture of the original cancellous bone. This material was characterised by means of Fourier transform infrared (FT-IR) spectroscopy and powder X-ray diffraction (XRD), while also being subjected to a washing experiment in distilled water with pH monitoring to show that the material was hydroxyapatite (HAp) (Ca10(PO4)6(OH)2) with small quantities of CaO. Scanning Electron Microscopy (SEM) showed that the SCBB material had retained its macroporous architecture, with higher magnification micrographs revealing a microporosity with channels through crystallites of the HAp of approximately 500 – 700 nm in diameter. Organic infiltrating solutions were prepared by dissolving chitosan in hydrochloric acid in addition to calcium phosphate, such as HAp or CaHPO4, to act as a mineral reinforcing material. Due to the limited solubility of HAp, the maximum concentration that could be achieved involving a 50 : 50 w/w combination of chitosan and HAp was 6 g L-1 for both materials in ~ 0.1 mol L-1 HCl. ε Polycaprolactone (PCL) dissolved in tetrahydrofuran (THF) was also trialled as an infiltrating solution, with concentrations up to 14 % w / v dissolved in the THF. Solutions were infiltrated into the porous SCBB material by means of vacuum, vacuum and pressure or a pressure only method. The extent of penetration of the infiltrate into the SCBB was followed by labelling the chitosan molecule with the fluorophore, Fluorescein Isothiocyanate (FITC) and then examining the infiltrated SCBB by fluorescence microscopy. After infiltration into the SCBB material, chitosan and mineral reinforcing were precipitated by an increase in pH. Several methods for increasing solution pH were trialled, including; the addition of urea into the infiltrating solution with subsequent thermal hydrolysis, the catalysis of urea by urease, and treatment with ammonia gas. By products and excess ammonia were shown to be able to be removed from the infiltrated SCBB by repeated washing in water and buffer solution. Mechanical testing on the infiltrated SCBB material was carried out by compression testing on an Instron materials testing instrument. Due to the inherent variability in the density and strength of the starting SCBB material, a statistical approach was required. Multiple samples were used and values for ultimate stress, modulus and a modified toughness measurement obtained from the mechanical testing for non-infiltrated SCBB samples were compared against infiltrated samples. SCBB samples infiltrated with a chitosan / CaHPO4 infiltrate displayed an improvement in ultimate stress, while samples infiltrated with PCL showed an overall increase in modulus. Finally, biocompatibility of the SCBB samples infiltrated with chitosan based infiltrates was tested using L929 fibroblast cell culture testing and a Hen’s Egg Test - Chorioallantoic Membrane (HET-CAM) test. Materials with low cytotoxic response were produced when sufficient washing and buffer treatment was employed after infiltration. This research proved that SCBB could be successfully infiltrated with an organic / mineral composite matrix, which was capable of modifying the mechanical properties of the SCBB, while displaying positive biocompatibility potential.

year: 2010

title: Composition Portfolio

authors: Ulenberg, Phillippa

subjects: composition portfolio

abstract: The music written for this portfolio offers creative answers to some of the challenges facing contemporary New Zealand composition, including multiculturalism.This has involved in-depth research using a variety of methods. Engagement was undertaken with linguists and musicians from Malaysia and Korea, who not only assisted with texts, but also spoke knowledgeably about their cultural traditions and past and present musical genres. The inclusion of Chinese gu-zheng in several of the works was made possible with the assistance given by Chen Xi Yao, an excellent performer who comes from a long lineage of musicians. Attending concerts given by performers of the instruments that have been used in the portfolio was essential to understanding the sounds and uses of the instruments. In addition, on-line sources include many examples of the sounds. Attendance at workshops on Māori taonga pūoro also brought the additional honour, benefits and experience of making and playing the instruments, and the opportunities to meet and work with leading makers and performers of these musical treasures. Sources of Western classical music that have been particularly influential during the writing of the portfolio are orchestral works by Igor Stravinsky, Samuel Barber and Param Vir, and the song cycles of Alban Berg and Benjamin Britten. Luciano Berio’s virtuosic piece for solo bassoon was also instructive. Experiences of composition, reflection and scholarly research underpin the portfolio and have have informed the composition of each work.

text: Composition Portfolio The music written for this portfolio offers creative answers to some of the challenges facing contemporary New Zealand composition, including multiculturalism.This has involved in-depth research using a variety of methods. Engagement was undertaken with linguists and musicians from Malaysia and Korea, who not only assisted with texts, but also spoke knowledgeably about their cultural traditions and past and present musical genres. The inclusion of Chinese gu-zheng in several of the works was made possible with the assistance given by Chen Xi Yao, an excellent performer who comes from a long lineage of musicians. Attending concerts given by performers of the instruments that have been used in the portfolio was essential to understanding the sounds and uses of the instruments. In addition, on-line sources include many examples of the sounds. Attendance at workshops on Māori taonga pūoro also brought the additional honour, benefits and experience of making and playing the instruments, and the opportunities to meet and work with leading makers and performers of these musical treasures. Sources of Western classical music that have been particularly influential during the writing of the portfolio are orchestral works by Igor Stravinsky, Samuel Barber and Param Vir, and the song cycles of Alban Berg and Benjamin Britten. Luciano Berio’s virtuosic piece for solo bassoon was also instructive. Experiences of composition, reflection and scholarly research underpin the portfolio and have have informed the composition of each work.

year: 2011