Update on detection, morphology and fragility in pili annulati in three kindreds.

BACKGROUND: Pili annulati is an inherited hair shaft abnormality with a wide range of clinical expression. OBJECTIVE: We have examined closely three kindreds to reveal levels and character of expression of the phenotype and supplement current literature on the threshold for detection and aspects of hair shaft fragility. PATIENTS AND METHODS: Eleven cases of pili annulati from three families were included in a clinical and morphological study. All cases were assessed clinically and by light and scanning electron microscopy (SEM) of hair shafts. In addition, transmission electron microscopy (TEM) (four patients) and amino acid analysis (three patients) were undertaken on clinically overt cases. Results Examination by light microscopy with a fluid mountant was more sensitive than clinical examination, increasing the detection rate by 120%. Microscopic examination revealed that the characteristic periodic bands become less frequent distally in the hair shaft. Microscopic features of weathering were found in two cases, adding pili annulati to the list of structural hair shaft dystrophies that may weaken hair and dispose to weathering. Amino acid analysis of the hair of three patients with pili annulati showed elevated lysine and decreased cystine content compared to 12 normal controls, consistent with the reduced threshold for weathering. CONCLUSION: Careful light microscopy with fluid-mounted hair is needed to detect subjects mildly affected by pili annulati. Expression of the phenotype varies widely between individuals, between hairs and within hairs of the same individual, where ageing of the hair diminishes detectable features.

Control of growth and differentiation in vitro of human keratinocytes cultured in serum-free medium.

Normal human proliferative keratinocytes can be serially cultured in serum-free medium. The medium and culture conditions that have been developed support the growth of these cells in the absence of a feeder layer and in the absence of contaminating fibroblasts. Using this system, the nutritional and hormonal factors that affect the growth and differentiation of these cells have been studied in the absence of undefined supplements. The data suggest that the control of proliferation and differentiation in keratinocytes may take place by unique mechanisms. The defined serum-free conditions that have been developed provide an excellent system for the study of nutritional disorders that affect human epidermal cells. In addition, the culture system can be used to propagate large numbers of cells for use in autografts for cases of severe burns.

Integrated control of growth and differentiation of normal human prokeratinocytes cultured in serum-free medium: clonal analyses, growth kinetics, and cell cycle studies.

The effects of growth factors, hormones, and calcium on the growth and differentiation of secondary cultures of normal human prokeratinocytes, i.e., proliferative keratinocytes, derived from adult or neonatal skin were determined by culture in serum-free basal medium, MCDB 153. Clonal growth was achieved when MCDB 153 was supplemented with either epidermal growth factor (EGF) or bovine pituitary extract (BPE), provided insulin was present. In the absence of insulin, however, both EGF and BPE were required for clonal growth. Using this assay, it was established that colony-forming efficiency is independent of calcium concentrations above 0.03 mM and averages 56%; colony size, however, was influenced by calcium and EGF concentrations. Optimal clonal growth occurred in medium containing 10 ng/ml EGF and 0.3 mM calcium. By contrast, differentiation was enhanced by the combination of low EGF (0.1 ng/ml) and high calcium (2 mM). This suggests that an inverse relationship exists between the growth response (extent of clonal growth) and the differentiation response (extent of differentiation). These results suggest that proliferation and differentiation are regulated in an integrated manner. Detailed kinetic studies and cytofluorimetric and autoradiographic analyses also showed that exponentially growing secondary cultures of adult and neonatal prokeratinocytes have a 24-hour cell generation time with G1, S, G2, and M phases of 12, 8, 3, and 1 hours, respectively. In addition, the data show that such cells can be growth arrested in medium that does not induce differentiation and that such a procedure significantly limits the cell's subsequent proliferative potential. Furthermore, prolonged culture of adult (greater than 30 population doublings) and neonatal prokeratinocytes (greater than 50 population doublings) is associated with senescence and the G1 arrest of noncycling cells.