For those readers interested in researching the theory of HPLC and the associated instrumentation a brief bibliography is listed below in addition to the references cited. The reader is also referred to the many good quality International Journals which are dedicated to the techniques of HPLC.
The enzyme defects of steroidogenesis appear to be monogenic disorders. The clinical heterogeneity of these disorders suggests allelic variations at the loci for these disorders, as has been reported for other gentic inborn errors. When the genes for these enzymes are cloned and sequenced, the final proof of allelism will be obtained. Prenatal diagnosis of one of the enzyme defects is possible by biochemical and HLA studies of the amniotic fluid. In the others, DNA restriction fragment polymorphism may provide a tool in the future for prenatal diagnosis. Since all these disorders are compatible with normal intelligence and a productive life, the more frequent ones at least are worthy of screening for early diagnosis and treatment.
A large number of endocrinological studies of testicular function in men of different ages suggest that primary testicular failure becomes common and more severe with aging. There is an increasing frequency of impotence, reduced secondary sex hair and testicular atrophy. Serum LH and FSH levels rise, androgen production rates and levels fall and oestrogen levels rise. The clearance of oestradiol falls but the production rate is maintained, in part, through increased peripheral conversion of testosterone to oestradiol. The levels of SHBG rise and free testosterone levels are reduced. Leydig cell responsiveness to hCG is probably reduced but gonadotrope responsiveness to GnRH reasonably maintained in the elderly. There are histological changes in the seminiferous epithelium of old men but these are non-specific. Senescent testicular failure is mainly a primary gonadal disorder but its cause and significance are only poorly understood.
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