C.J.H. Kelnar

Ovarian and uterine characteristics after total body irradiation in childhood and adolescence: response to sex steroid replacement

Objective To study the effect of total body irradiation (14.4 Gray) in childhood and adolescence on ovarian and uterine characteristics, and to investigate the response to physiological sex steroid serum concentrations.

Semen quality and spermatozoal DNA integrity in survivors of childhood cancer: a case-control study.

BACKGROUND Treatment of childhood cancer can result in impaired spermatogenesis. Intracytoplasmic sperm injection (ICSI), however, can enable men to achieve fatherhood, and has focused attention on gamete integrity in men with oligozoospermia. Our aim was to assess testicular function in survivors of childhood cancer. METHODS We assessed testicular function in 33 survivors of childhood cancer and 66 age-matched controls. The median age at diagnosis and at the start of the trial was 10.0 years (range 2.2-16.9) and 21.9 years (16.5-35.2), respectively. We assessed pubertal staging, measured plasma sex steroid hormone concentrations, and analysed semen quality, including spermatozoal DNA integrity. FINDINGS Ten (30%) individuals were azoospermic and six (18%) oligozoospermic (sperm concentration, 20 x 10(6)/mL). Sperm concentration was significantly lower in the non-azoospermic group than in controls (median 37.1 x 10(6)/mL, IQR 19.7 x 10(6) to 89.9 x 10(6), vs 90.7 x 10(6)/mL, 50.5 x 10(6) to 121.5 x 10(6); p=0.002). In the non-azoospermic cancer survivor group, inhibin B concentrations were lower than in controls (mean 153.3 ng/L, SEM 17.8, vs 223.7 ng/L, 8.8; p,0.001), and FSH concentrations were higher (6.6 U/L, 0.9, vs 3.2 U/L, 0.2; p,0.001). Only 11 (33%) survivors of childhood cancer had normal semen quality. There was no significant difference in sperm DNA integrity between the non-azoospermic and control groups (9%, 5-13, vs 11%, 7-16; p=0.06). INTERPRETATION Sperm concentration is reduced after treatment for cancer. However, the sperm produced seems to carry as much healthy DNA as those produced by the healthy population, suggesting that assisted conception can be considered as a treatment option for these men.

Inhibin B in boys from birth to adulthood: relationship with age, pubertal stage, FSH and testosterone.

objective Inhibin B in males is produced principally by Sertoli cells under the influence of FSH and is thought to have a role in feedback regulation of FSH. The aims of our study were to investigate how inhibin B changes from birth to late adolescence in boys, to derive reference data and to explore its relation with pubertal stage, FSH and testosterone.

Do Phthalates Affect Steroidogenesis by the Human Fetal Testis? Exposure of Human Fetal Testis Xenografts to Di-n-Butyl Phthalate

CONTEXT Phthalates are ubiquitous environmental chemicals. Fetal exposure to certain phthalates [e.g. di-n-butyl phthalate (DBP)] causes masculinization disorders in rats, raising concern for similar effects in humans. We investigated whether DBP exposure impairs steroidogenesis by the human fetal testis. OBJECTIVE The aim of the study was to determine effects of DBP exposure on testosterone production by normally growing human fetal testis xenografts. DESIGN Human fetal testes (14-20 wk gestation; n=12) were xenografted into castrate male nude mice that were treated for 4-21 d with vehicle, or 500 mg/kg·d DBP, or monobutyl phthalate (active metabolite of DBP); all mice were treated with human chorionic gonadotropin to mimic normal human pregnancy. Rat fetal testis xenografts were exposed for 4 d to DBP as a positive control. MAIN OUTCOME MEASURES Testosterone production was assessed by measuring host serum testosterone and seminal vesicle (SV) weights at termination, plus testis gene expression (rats). RESULTS Human fetal testis xenografts showed similar survival (∼80%) and total graft weight (8.6 vs. 10.1 mg) in vehicle and DBP-exposed hosts, respectively. Serum testosterone (0.56 vs. 0.64 ng/ml; P>0.05) and SV weight (67.2 vs. 81.9 mg; P>0.05) also did not differ. Exposure to monobutyl phthalate gave similar results. In contrast, exposure of rat fetal xenografts to DBP significantly reduced SV weight and testis Cyp11a1/StAR mRNA expression and lowered testosterone levels, confirming that DBP exposure can inhibit steroidogenesis in xenografts, further validating the negative findings on testosterone production in the human. CONCLUSIONS Exposure of human fetal testes to DBP is unlikely to impair testosterone production as it does in rats. This has important safety and regulatory implications.

Germ cell differentiation in the marmoset (Callithrix jacchus) during fetal and neonatal life closely parallels that in the human

BACKGROUND Testicular germ cell tumours (TGCT) are thought to originate from fetal germ cells that fail to differentiate normally, but no animal model for these events has been described. We evaluated the marmoset (Callithrix jacchus) as a model by comparing perinatal germ cell differentiation with that in humans. METHODS Immunohistochemical profiling was used to investigate germ cell differentiation (OCT4, NANOG, AP-2γ, MAGE-A4, VASA, NANOS-1) and proliferation (Ki67) in fetal and neonatal marmoset testes in comparison with the human and, to a lesser extent, the rat. RESULTS In marmosets and humans, differentiation of gonocytes into spermatogonia is associated with the gradual loss of pluripotency markers such as OCT4 and NANOG, and the expression of germ cell-specific proteins such as VASA. This differentiation occurs asynchronously within individual cords during fetal and early postnatal life. This contrasts with rapid and synchronous germ cell differentiation within and between cords in the rat. Similarly, germ cell proliferation in the marmoset and human occurs throughout perinatal life, in contrast to rats in which proliferation ceases during this period. CONCLUSIONS The marmoset provides a good model for normal human germ cell differentiation and proliferation. The perinatal marmoset may be a useful model in which to establish factors that lead to failure of normal germ cell differentiation and the origins of TGCT.

Changes in dimeric inhibin A and B during normal early puberty in boys and girls

OBJECTIVE Although recently developed specific and sensitive assays of bioactive dimeric inhibin A and B have given new insights into the pituitary‐gonadal axis in adult men and during the adult female menstrual cycle, there have been no reports on circulating inhibin A and B during normal human puberty. The aim of this study was to assess the relationship of dimeric inhibin A and B to pubertal stage, FSH and testosterone or oestradiol in late prepuberty and in early puberty.

Cardiovascular effects of physiological and standard sex steroid replacement regimens in premature ovarian failure

Current hormone replacement therapy may not optimize cardiovascular health in women with premature ovarian failure. We compared the effects of physiological and standard sex steroid replacement regimens on cardiovascular health in these women. In an open-label, randomized, controlled crossover trial, 34 women with premature ovarian failure were randomly assigned to 4-week cycles of physiological (transdermal estradiol and vaginal progesterone) and standard (oral ethinylestradiol and norethisterone) therapy for 12 months. Cardiovascular health was assessed by 24-hour ambulatory blood pressure, arterial stiffness, and renal and humoral factors. Eighteen women (19 to 39 years of age) completed the 28-month protocol. Both regimens caused similar suppression of luteinizing hormone and follicle-stimulating hormone and provided symptom relief. In comparison with the standard regimen, physiological sex steroid replacement caused lower mean 24-hour systolic and diastolic blood pressures throughout the 12-month treatment period (ANOVA; P≤0.0001 for both): systolic blood pressure was 7.3 mm Hg (95% CI: 2.5 to 12.0 mm Hg) and diastolic was 7.4 mm Hg (95% CI: 3.9 to 11.0 mm Hg) lower at 12 months. Although there were no differences in arterial stiffness, physiological sex steroid replacement reduced plasma angiotensin II (ANOVA; P=0.007) and serum creatinine (ANOVA; P=0.015) concentrations without altering plasma aldosterone concentrations. In comparison with a standard regimen, physiological sex steroid replacement in women with premature ovarian failure results in lower blood pressure, better renal function, and less activation of the renin-angiotensin system. These findings have major implications for the future cardiovascular health of young women who require long-term sex steroid replacement therapy.

Short stature in Noonan syndrome: response to growth hormone therapy

BACKGROUND Growth hormone (GH) has been used to promote growth in both the short and long term in a number of dysmorphic syndromes, including Turner syndrome. As this condition shares many clinical features with Noonan syndrome, it would seem logical to treat the latter group with GH. AIMS To assess the short and long term response to GH therapy in patients with Noonan syndrome. METHODS Analysis of patients with Noonan syndrome in the Pharmacia & Upjohn International Growth Study (this post-marketing database contains data on the majority of patients currently treated with GH in the UK). A questionnaire was also sent to participating clinicians. RESULTS Data on 66 patients (54 males) were available for study. At the start of GH therapy children were short, compared with both normal and Noonan children. During the first year of GH therapy height velocity increased from a mean of 4.9 to 7.2 cm per year. For patients treated long term with GH, mean height SDS increased from −2.9 pretreatment to −2.6 after one year and −2.3 after five years. Of the 10 patients at near final height, only one had a height above the 3rd centile for normal adults and above the mean for untreated Noonan patients. The mean increment in final height was 3.1 cm (range −1.1 to 6.5 cm). CONCLUSIONS GH therapy in patients with Noonan syndrome will improve height velocity in the short term. Longer-term therapy results in a waning of effect; initial indications are that final height is not improved substantially in most patients.

GNAS1 mutational analysis in pseudohypoparathyroidism

Mutations of the GNAS1 gene, which is located on chromosome 20q13.11 and encodes the α‐subunit of the stimulatory GTP‐binding protein, have been identified in patients with pseudohypoparathyroidism type Ia (PHPIa) and pseudopseudohypoparathyroidism (PPHP). We have undertaken studies to determine the prevalence of GNAS1 mutations and to explore methods for their more rapid detection.

Bone Turnover and Growth During and After Continuing Chemotherapy in Children with Acute Lymphoblastic Leukemia

Children treated for acute lymphoblastic leukemia may develop reduced bone mineral density during treatment, but there is little information on the mechanisms involved. In a prospective, longitudinal study on 15 children with ALL, we undertook serial measurements of markers of bone and collagen turnover, insulin-like growth factor (IGF)-I and its binding proteins (IGFBPs)-3 and -2 during the second year of continuing chemotherapy. In eight patients we also measured lower leg length by knemometry. Height SD scores, lower leg length velocity, IGF-I, and markers of bone collagen turnover did not differ significantly from healthy children. However, bone alkaline phosphatase, a marker of the differentiated osteoblast, was lower (mean SD score, −0.64;p < 0.0001), whereas procollagen type III N-terminal propeptide (P3NP, a marker of soft tissue collagen turnover; mean SD score, +0.93, p < 0.05), IGFBP-3 (mean SD score, +0.76;p < 0.01), and IGFBP-2 (mean SD score, +1.24, p = 0.01) were all higher than in healthy children. IGFBP-3 decreased during episodes of afebrile neutropenia (p < 0.05). Within 3 mo after completion of treatment, bone ALP increased in all eight patients, but collagen markers showed little change. IGFBP-2 returned to normal posttreatment, but P3NP and IGFBP-3 remained significantly elevated compared with healthy children (mean SD scores, +1.51 and +1.36, respectively;p < 0.01). We conclude that continuing chemotherapy was associated with normal growth and bone collagen turnover but enhanced soft tissue collagen turnover. Bone bone alkaline phosphatase was low throughout treatment, which suggests impaired osteoblast differentiation resulting from a direct effect of chemotherapy on bone. Although the effect was reversible, the long-term implications for bone health in survivors remain uncertain.