bluuebunny/crossref_metadata_2025 huggingface dataset:
Stem cell research: immortality or a healthy old age?
Authors: Mummery C
Published: January 2005

Stem cell research holds the promise of treatments for many disorders resulting from disease or trauma where one or at most a few cell types have been lost or do not function. In combination with tissue engineering, stem cells may represent the greatest contribution to contemporary medicine of the present century. Progress is however being hampered by the debate on the origin of stem cells, which can be derived from human embryos and some adult tissues. Politics, religious beliefs and the media have determined society's current perception of their relative value while the ethical antipathy towards embryonic stem cells, which require destruction of a human embryo for their derivation, has in many countries biased research towards adult stem cells. Many scientists believe this bias may be premature and basic research on both cell types is still required. The media has created confusion about the purpose of stem cell research: treating chronic ailments or striving for immortality. Here, the scientific state of the art on adult and embryonic stem cells is reviewed as a basis for a debate on whether research on embryonic stem cells is ethically acceptable.
Role of thyroid hormone during early brain development
Authors: Morreale de Escobar G , Obregon MJ , Escobar del Rey F
Published: January 2005

The present comments are restricted to the role of maternal thyroid hormone on early brain development, and are based mostly on information presently available for the human fetal brain. It emphasizes that maternal hypothyroxinemia - defined as thyroxine (T4) concentrations that are low for the stage of pregnancy - is potentially damaging for neurodevelopment of the fetus throughout pregnancy, but especially so before midgestation, as the mother is then the only source of T4 for the developing brain.Despite a highly efficient uterine-placental 'barrier' to their transfer, very small amounts of T4 and triiodothyronine (T3) of maternal origin are present in the fetal compartment by 4 weeks after conception, with T4 increasing steadily thereafter. A major proportion of T4 in fetal fluids is not protein-bound: the 'free' T4 (FT4) available to fetal tissues is determined by the maternal serum T4, and reaches concentrations known to be of biological significance in adults. Despite very low T3 and 'free' T3 (FT3) in fetal fluids, the T3 generated locally from T4 in the cerebral cortex reaches adult concentrations by midgestation, and is partly bound to its nuclear receptor. Experimental results in the rat strongly support the conclusion that thyroid hormone is already required for normal corticogenesis very early in pregnancy.The first trimester surge of maternal FT4 is proposed as a biologically relevant event controlled by the conceptus to ensure its developing cerebral cortex is provided with the necessary amounts of substrate for the local generation of adequate amounts of T3 for binding to its nuclear receptor. Women unable to increase their production of T4 early in pregnancy would constitute a population at risk for neurological disabilities in their children. As mild-moderate iodine deficiency is still the most widespread cause of maternal hypothyroxinemia in Western societies, the birth of many children with learning disabilities may already be preventable by advising women to take iodine supplements as soon as pregnancy starts, or earlier if possible.
Molecular genetic defects in congenital hypothyroidism
Authors: Gruters A , Krude H , Biebermann H
Published: January 2005

Recently molecular genetic defects in some cases of congenital hypothyroidism (CH) as well as of rare cases of central hypothyroidism have been identified. These studies have led to the description of so far unexplained forms of these disorders. In some patients with CH early diagnosis by newborn screening and early treatment was not able to lead to a normal mental development. This could subsequently be explained by molecular defects of transcription factors (FOXE-1/FKHL15, NKX2.1) which are important not only for the embryonic development of the thyroid gland but also for other organs including the central nervous system (CNS). These findings will help in understanding the critical role of thyroid hormones in the pre-and postnatal CNS development. However, many questions regarding the molecular defects and their consequences in the majority of patients with CH still remain open and will be addressed in this article.
The sequelae of untreated maternal hypothyroidism
Authors: Mitchell ML , Klein RZ
Published: January 2005

The concept that gestational subclinical hypothyroidism could have deleterious effects on the intellectual outcome of progeny was championed more than three decades ago by Evelyn Man in a series of publications. Her studies lay fallow until the Spanish group directed by Morreale de Escobar and the Dutch group headed by Vulsma provided the rationale for her results. Although the findings of the Spanish and Dutch groups elucidated the pathophysiologic basis for Man's conclusions, questions remained regarding the reliability of her biochemical measurements and possible bias in patient selection. In view of the uncertainty surrounding the validity of Man's work, we decided to try to confirm her findings. Our initial goal was to obtain an estimate of the prevalence of subclinical hypothyroidism in an unselected population living in New England. We accomplished this with two separate prospective studies involving 12 000 pregnant women residing in Maine. We found that 2.3% had TSH concentrations of >6.0 mU/l and 0.3% had TSH values of >12 mU/l at 17 weeks' gestation. We next did a retrospective study, utilizing sera that had been stored at -20 degrees C for 8 years, obtained in week 17 of gestation from 25 000 women. We identified 62 women with subclinical hypothyroidism and 124 matched controls. Fourteen of the hypothyroid mothers had been diagnosed and treated before and during pregnancy on a dosage of thyroxine that was unchanged. WISC IQs of the offspring of the 124 control and 62 hypothyroid mothers were determined at 8+/-0.5 years. The mean and s.d. of IQs of the children of the 124 control and of the 14 treated hypothyroid mothers were significantly higher than those of the children of the 48 untreated hypothyroid women. More than twice as many children of the untreated mothers had IQs of >1 s.d. below the control mean, and four times as many of the children had IQs 2 s.d. below the control mean, as did the children of the controls. A comparison of the mean hormonal values of the treated and untreated mothers at 17 weeks showed no significant difference in any of the biochemical markers. We surmise that the circulating level of thyroxine was normal in the treated mothers at a critical time before 17 weeks' gestation, but by 17 weeks it was insufficient to meet the growing demands of pregnancy. Treatment should begin as early as possible in pregnancy with the goal of maintaining free thyroxine (FT(4)) in the upper half of the normal reference range and TSH in the lower half of the normal reference range. In view of these data, we believe that all pregnant women should be screened for hypothyroidism as early in pregnancy as possible (or even before conception). To be cost-effective, screening programs should be based on those designed for congenital hypothyroidism, in which filter-paper blood specimens are forwarded to regional laboratories for thyroid function determinations.
Prenatal glucocorticoids and long-term programming
Authors:   Seckl
Published: January 2005

Epidemiological evidence suggests that low birth weight is associated with an increased risk of cardiovascular, metabolic and neuroendocrine disorders in adult life. Glucocorticoid administration during pregnancy reduces offspring birth weight and alters the maturation of the lung and other organs. We hypothesised that prenatal exposure to excess glucocorticoids or stress might represent a mechanism linking foetal growth with adult pathophysiology. In rats, birth weight is reduced following prenatal exposure to the synthetic steroid dexamethasone, which readily crosses the placenta, or to carbenoxolone, which inhibits 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), the physiological feto-placental 'barrier' to maternal glucocorticoids. As adults, the offspring exhibit permanent hypertension, hyperglycaemic, increased hypothalamic-pituitary-adrenal (HPA) axis activity and behaviour reminiscent of anxiety. Physiological variations in placental 11beta-HSD2 activity correlate directly with foetal weight. In humans, 11beta-HSD2 gene mutations cause low birth weight. Moreover, low-birth-weight babies have higher plasma cortisol levels throughout adult life, indicating HPA axis programming. The molecular mechanisms may reflect permanent changes in the expression of specific transcription factors, key among which is the glucocorticoid receptor (GR) itself. The differential programming of the GR in different tissues reflects effects upon one or more of the multiple tissue-specific alternate first exons/promoters of the GR gene. Overall, the data suggest that both pharmacological and physiological exposure prenatally to excess glucocorticoids programmes cardiovascular, metabolic and neuroendocrine disorders in adult life.
Prenatal treatment of congenital adrenal hyperplasia
Authors: Lajic S , Nordenstrom A , Ritzen EM , Wedell A
Published: January 2005

In foetuses at risk of virilising congenital adrenal hyperplasia (CAH), prenatal treatment can be offered by administration of dexamethasone (DEX) via the mother, in order to suppress foetal adrenal androgen oversecretion and prevent genital malformations. The first treated cases were described 20 years ago, and several hundred pregnancies have been reported since. There is a consensus that the treatment effectively prevents or reduces virilisation, but opinions regarding its safety differ. Rare adverse events have been reported in treated children, but no harmful effect has been documented that can be clearly attributed to the treatment. However, few treated foetuses have been followed until adolescence. Animal studies and epidemiological data point to various adverse effects of excess glucocorticoids on the developing foetus. In order to prevent virilisation effectively in females affected with CAH, the prenatal treatment needs to be instituted in the early first trimester, before prenatal diagnosis is possible. Thus, a majority of treated foetuses will receive DEX unnecessarily.The PREDEX study was initiated in Stockholm in 1999 as an open, controlled, non-randomised, multicentre trial. Participating centres are Stockholm, Bergen, Kuopio, Warsaw, London, Lyon and Barcelona. The study has been approved by the ethics committees in each country. The purpose of PREDEX is to evaluate prospectively the prenatal treatment regarding efficacy in preventing virilisation as well as to study its safety for both mothers and treated children. Children are followed until 18 years of age and a wide range of physiological, metabolic and developmental parameters are considered. In Sweden, treatment is not offered outside the frames of the trial.
Classic congenital adrenal hyperplasia and puberty
Authors: Charmandari E , Brook CG , Hindmarsh PC
Published: January 2005

Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders resulting from deficiency of one of the five enzymes required for synthesis of cortisol in the adrenal cortex. The most common form of the disease is classic 21-hydroxylase deficiency, which is characterized by decreased synthesis of glucocorticoids and often mineralocorticoids, adrenal hyperandrogenism and impaired development and function of the adrenal medulla. The clinical management of classic 21-hydroxylase deficiency is often suboptimal, and patients are at risk of developing in tandem iatrogenic hypercortisolism and/or hyperandogenism. Limitations of current medical therapy include the inability to control hyperandrogenism without employing supraphysiologic doses of glucocorticoid, hyperresponsiveness of the hypertrophied adrenal glands to adrenocorticotropic hormone (ACTH) and difficulty in suppressing ACTH secretion from the anterior pituitary. Puberty imposes increased difficulty in attaining adrenocortical suppression despite optimal substitution therapy and adherence to medical treatment. Alterations in the endocrine milieu at puberty may influence cortisol pharmacokinetics and, consequently, the handling of hydrocortisone used as replacement therapy. Recent studies have demonstrated a significant increase in cortisol clearance at puberty and a shorter half-life of free cortisol in pubertal females compared with males. Furthermore, children with classic CAH have elevated fasting serum insulin concentrations and insulin resistance. The latter may further enhance adrenal and/or ovarian androgen secretion, decrease the therapeutic efficacy of glucocorticoids and contribute to later development of the metabolic syndrome and its complications.
New insights in the genetics of isolated hypogonadotropic hypogonadism
Authors: Iovane A , Aumas C , de Roux N
Published: January 2005

Isolated gonadotropic deficiency or isolated hypogonadotropic hypogonadism is defined as a low sexual hormone secretion by the gonads associated with low LH and FSH plasma levels. Kallmann syndrome is defined as a congenital isolated gonadotropic deficiency associated with anosmia whereas the phenotype of the idiopathic form is limited to the gonadotropic axis. For several years, it has been known that mutations of the KAL-1 gene or loss-of-function mutations of GnRH receptor did not explain all familial cases of isolated gonadotropic deficiency with or without anosmia. Thus the existence of other genes playing a major role in the physiology of the gonadotropic axis was highly suggested. In 2003, fibroblast growth factor receptor 1 (FGFR1) and GPR54 were shown to be two of these genes. FGFR1 loss-of-function mutations were reported in Kallmann syndrome whereas inactivating mutations of GPR54 were described in the idiopathic form of the gonadotropic deficiency. These genetic studies have opened up a new chapter in the physiology and the pharmacology of the gonadotropic axis.
Application of gonadotropin releasing hormone in hypogonadotropic hypogonadism--diagnostic and therapeutic aspects
Authors: Delemarre-van de Waal HA
Published: January 2005

BACKGROUND: Puberty is the result of reactivation of the gonadotropin releasing hormone (GnRH) pulse generator resulting in an increasing release of GnRH by the hypothalamus, which stimulates the gonadotropic cells of the pituitary to synthesize and secrete LH and FSH. Hypogonadotropic hypogonadism (HH) is often the result of GnRH deficiency. The clinical picture is characterized by the absence of pubertal development and infertility. It is difficult to differentiate HH from delayed puberty since low gonadotropin and low testosterone levels are found in both conditions. We hypothesized that long-term GnRH administration may differentiate between the two conditions by a difference in the increase of gonadotropins, the idea being that in normal delayed puberty the pituitary of the patient has been primed with GnRH during the fetal and early postnatal period. PATIENTS: Seventeen adolescents suspected of having hypogonadotropic hypogonadism were treated with pulsatile GnRH for 7 days. At the present time, the diagnosis of these patients is known and the results of the long-term GnRH stimulation have been evaluated according to the present diagnosis. RESULTS: The results show that the increase in gonadotropins following GnRH treatment is similar in both conditions. Therefore, at a prepubertal age a normal delayed puberty cannot be distinguished from hypogonadotropic hypogonadism using long-term GnRH stimulation. Long-term pulsatile GnRH treatment is a physiological therapy for the induction of puberty. Unlike testosterone it has the advantage of stimulation of testicular growth and fertility, as well as virilization, in males. We have treated 68 male patients with HH with pulsatile GnRH. The results show testicular growth and virilization in all the patients and spermatogenesis in 58 patients. Wearing a portable pump is cumbersome. However, the patients were very motivated and adapted very easily to this inconvenience. When spermatogenesis had developed, GnRH treatment was changed to human chorionic gonadotropin (hCG) administration 1-2 times per week intramuscularly or subcutaneously. During hCG therapy spermatogenesis was maintained or even improved. At least ten patients fathered children. CONCLUSION: Pulsatile GnRH cannot distinguish between a normal delayed puberty and a hypothalamic defect in still prepubertal patients. Pulsatile GnRH offers an appropriate way to initiate testicular growth including virilization and fertility in males with hypogonadotropic hypogonadism.
The regulation of GH secretion by sex steroids
Authors: Chowen JA , Frago LM , Argente J
Published: January 2005

Gonadal sex steroids modulate GH synthesis and secretion with effects on both the hypothalamus and anterior pituitary. In the post-pubertal animal, androgens and oestrogens modulate hypothalamic somatostatin (SS) and GHRH synthesis respectively. These effects may be direct as SS neurons express the androgen receptor and many GHRH neurons are oestrogen receptor positive. The neonatal steroid environment modulates the number of GHRH neurons in the adult hypothalamus, as well as their responsivity to post-pubertal steroids. Furthermore, both neonatal and post-pubertal steroids modulate hypothalamic synaptic organisation affecting the number of synaptic inputs and the morphology of glial cells. This in turn has important effects on the ability of the hypothalamus to drive the secretory pulsatility of anterior pituitary hormone release. At the level of the somatotroph, androgens and oestrogens have been reported to stimulate, inhibit or have no effect on GH synthesis. In primary cultures, we found no effect of either androgens or oestrogens on GH mRNA levels. However, the sex steroid environment significantly modified the response of somatotrophs to SS. Furthermore, males have more somatotrophs compared with female rats and this partially depends on the neonatal sex steroid environment. In conclusion, sex steroids have both organisational and activational effects on the GH axis. These effects range from modulating the number of hypothalamic neurons controlling GH secretion, their responsiveness to later steroids, and the synaptic connectivity and neuropeptide production, to modulation of somatotroph numbers in the anterior pituitary and their responsiveness to inputs controlling GH synthesis and secretion.
Can we increase adolescent growth?
Authors: Carel JC
Published: January 2005

Adolescent growth represents 15-20% of adult height and has been the focus of several treatment interventions, aiming at increasing the amplitude of the adolescent spurt. Importantly, pre- and early puberty are times when patients and families seek medical help and when estimates of adult height are more accurate than in younger children. We review the current approaches aimed at increasing pubertal growth in short children and knowledge about their results and risks. GnRH agonists, when used outside the context of precocious puberty, induce a modest gain (4 cm) when they are used for more than 3 years. Their effects on bone mass, body composition and possibly on psychosocial parameters limit their use. Several trials have now shown that GH can increase adult height of short adolescents with idiopathic short stature or born small for gestational age. However, the amplitude of the effect is modest and of dubious clinical significance. Lastly, the association of both approaches is rather popular among pediatric endocrinologists but still lacks a definite demonstration of its efficacy. In conclusion, we have gained insight in the median effects of some of these treatments and overoptimistic initial expectations are now refocused. However, we still have a long way to go before we truly evaluate the factors affecting the variable individual responses to these treatments, their clinical significance and their cost-benefit balance.
Growth, growth factors and diabetes
Authors: Chiarelli F , Giannini C , Mohn A
Published: January 2005

Type 1 diabetes mellitus (T1DM) and other chronic diseases in children are well known to adversely affect linear growth and pubertal development. In the years immediately following the introduction of insulin therapy, short stature was consistently reported in children with T1DM. However, over the past 50 years significant improvement in the prognosis for growth and final height in children with diabetes has been achieved. Although pre-pubertal and post-pubertal growth are important phases in growth, puberty and its related hormonal changes represent a critical phase for growth gain and final height particularly in patients with T1DM. Growth impairment reported in diabetic patients is dependent on abnormalities in physiological bone growth and corresponds to abnormalities of the growth hormone-insulin-like growth-I (GH-IGF-I) axis. These alterations seem to be related to appropriate insulin levels and thereby to glycaemic control as judged by haemoglobin levels. Modern diabetes care, particularly intensified insulin regimens, might improve metabolic control in patients with T1DM, therefore preventing abnormalities of the GH-IGF-I axis and leading to normal growth and final height similar to that of their unaffected peers.
The Avon Longitudinal Study of Parents and Children (ALSPAC)--study design and collaborative opportunities
Authors: Golding J
Published: January 2005

The Avon Longitudinal Study of Parents and Children (ALSPAC) is a population-based study designed to understand the ways in which the physical and social environment interact, over time, with the genotype to affect health, behaviour and development. This information about causal interactions in common diseases and disorders will provide the basis on which future preventive interventions can be tested, especially in regard to people with specific genotypes. Whilst ALSPAC builds on data and hypotheses generated by earlier general population cohorts, its design offers special advantages, the most important being: enrolment in early pregnancy; banking of DNA from the children and parents (permitting genetic transmission tests and transgenerational imprinting studies); diverse physical, psychological and environmental measures; one geographical base (permitting medical record and school linkage; environmental measures in the home, and clinics for direct examination); annual hands-on examinations of the full cohort since age 7. The 14 541 enrolled pregnancies (expected date of delivery 1 April 1991 to 31 December 1992) represented about 85% of the eligible population. The 13 971 children who were still alive at age 12 months have been followed principally by questionnaires completed by a parent. Twelve years on, questionnaires are still being sent out to 11 300 families. The average questionnaire response rate from mothers is 79%. From age 7, annual examinations of both 'physical' and 'psychological' aspects have also been conducted on the children (approximately 8000 attend each 'clinic'). The quality of the data has proved high in validation studies and is maintained by collaboration with experts in each specialist field. The high participation rate ensures a viable study well into the future.
The Avon Longitudinal Study of Parents and Children (ALSPAC): a resource for genetic epidemiology
Authors: Pembrey M
Published: January 2005

The Avon Longitudinal Study of Parents and Children (ALSPAC) has collected detailed phenotypic and environmental information from pregnancy onwards on approximately 14 000 babies born in 1991-1992. A DNA bank on over 10 000 mothers and children has been established with generic consent for (undisclosed) genetic analysis, and cell lines on both children and parents are planned. As a multigenerational population cohort unselected by disease, trait or exposure, ALSPAC is uniquely placed to explore the genetic and environmental determinants of adverse developmental responses and common disease. Added value for genetic epidemiology generally is the ability to detect distortion of the expected Mendelian 50:50 transmission of alleles to study subjects (e.g. due to differential loss of embryos of one genotype) or to test for heterosis, i.e. whether heterozygotes have a greater or lesser effect than either homozygote. Finally, phenome scans (a fixed format analysis of the associations between a genotype of interest and thousands of outcome variables from the cohort database) could be used as a screening tool to test whether certain classes of genetic variation have more impact than others on human health and development.
The Avon Longitudinal Study of Parents and Children (ALSPAC)--a resource for the study of the environmental determinants of childhood obesity
Authors: Ness AR
Published: January 2005

Childhood obesity is a major public health problem because the prevalence is increasing and because childhood obesity is associated with short- and long-term adverse consequences. By contributing to our understanding of the causes of childhood obesity epidemiological studies can help to inform preventive strategies. Prospective studies with all-of-life measures of exposures, objective measures of physical activity and more accurate measures of diet and body composition will be better able to identify modifiable environmental exposures that act cumulatively or at critical time periods across the lifecourse. The Avon Longitudinal Study of Parents and Children (ALSPAC) recruited around 14 000 pregnant women with estimated dates of delivery between 1991 and 1992. The children have been followed-up in detail ever since and now constitute probably the most intensively studied cohort of children ever recruited. Recent analyses have identified important modifiable risk factors and further analyses based on more accurate measures of diet, activity and body composition should provide further insights.
Sex 'n' drugs 'n' rock 'n' roll: the meaning and social consequences of pubertal timing
Authors: Waylen A , Wolke D
Published: January 2005

This is a brief review of the normal changes in adolescent behaviour and the interplay between biology and social factors that occur at and around puberty, in an attempt to explain when this transition may become problematic The onset of puberty is a biological marker for an individual's transition from a non-reproductive to a reproductive state. Adolescence is a normal developmental transition associated with clearly visible physical changes, reorganization and pruning of neuronal circuits in the brain and the occurrence of new behaviours and interests. It is a time when new life tasks (orientation towards peers of the other sex, romantic and sexual involvement and mastering an educational career) need to be mastered. Parent-child conflict increases and becomes more intense as the adolescent struggles for more independence while still requiring support. These normal changes can become problematic if biological and social expectations diverge e.g. entering puberty very early or very late. While early pubertal onset in boys is likely to have beneficial effects, in girls precocious pubertal timing may have a negative impact on body-image, affect (or emotional well-being) and sex-role expectations. Other individual biological predispositions and genetic endowment may interact with social factors (e.g. peers, parenting style, neighbourhood) making adolescence either an adaptive or a challenging transition. There is a lack of sufficiently large longitudinal studies that have been able to study this interaction between genetics, biology and social environment on adolescent development. The Avon Longitudinal Study of Parents and Children (ALSPAC) cohort provides a unique opportunity to investigate the impact of pubertal timing on social behaviour. Planned assessments and concepts are outlined.
Genetic control of growth
Authors: Mullis Primus E
Published: January 2005

The application of the powerful tool molecular biology has made it possible to ask questions not only about hormone production and action but also to characterize many of the receptor molecules that initiate responses to the hormones. We are beginning to understand how cells may regulate the expression of genes and how hormones intervene in regulatory processes to adjust the expression of individual genes. In addition, great strides have been made in understanding how individual cells talk to each other through locally released factors to coordinate growth, differentiation, secretion, and other responses within a tissue. In this review I (1) focus on developmental aspects of the pituitary gland, (2) focus on the different components of the growth hormone axis and (3) examine the different altered genes and their related growth factors and/or regulatory systems that play an important physiological and pathophysiological role in growth. Further, as we have already entered the ‘post-genomic’ area, in which not only a defect at the molecular level becomes important but also its functional impact at the cellular level, I concentrate in the last part on some of the most important aspects of cell biology and secretion.
Subclinical hyperthyroidism: clinical features and treatment options
Authors: Biondi Bernadette , Palmieri Emiliano Antonio , Klain Michele , Schlumberger Martin , Filetti Sebastiano , Lombardi Gaetano
Published: January 2005

Subclinical hyperthyroidism appears to be a common disorder. It may be caused by exogenous or endogenous factors: excessive TSH suppressive therapy withl-thyroxine (l-T4) for benign thyroid nodular disease, differentiated thyroid cancer, or hormone over-replacement in patients with hypothyroidism are the most frequent causes. Consistent evidence indicates that ‘subclinical’ hyperthyroidism reduces the quality of life, affecting both the psycho and somatic components of well-being, and produces relevant signs and symptoms of excessive thyroid hormone action, often mimicking adrenergic overactivity. Subclinical hyperthyroidism exerts many significant effects on the cardiovascular system; it is usually associated with a higher heart rate and a higher risk of supra-ventricular arrhythmias, and with an increased left ventricular mass, often accompanied by an impaired diastolic function and sometimes by a reduced systolic performance on effort and decreased exercise tolerance. It is well known that these abnormalities usually precede the onset of a more severe cardiovascular disease, thus potentially contributing to the increased cardiovascular morbidity and mortality observed in these patients. In addition, it is becoming increasingly apparent that subclinical hyperthyroidism may accelerate the development of osteoporosis and hence increased bone vulnerability to trauma, particularly in postmenopausal women with a pre-existing predisposition. Subclinical hyperthyroidism and its related clinical manifestations are reversible and may be prevented by timely treatment.
Mechanism of inhibition of cytochrome P450 C21 enzyme activity by autoantibodies from patients with Addison’s disease
Authors: Nikfarjam L , Kominami S , Yamazaki T , Chen S , Hewer R , Dal Pra C , Nakamatsu T , Betterle C , Zanchetta R , Rees Smith B , Furmaniak J
Published: January 2005

Objective: To study possible mechanisms for the inhibition of cytochrome P450 C21 (steroid 21-hydroxylase) enzyme activity by P450 C21 autoantibodies (Abs)in vitro.

Design: Two possible mechanisms for the inhibition of P450 C21 enzyme activity by P450 C21 Abs were studied: (a) conformational changes in the P450 C21 molecule induced by Ab binding and (b) the effects of Ab binding to P450 C21 on the electron transfer from the nicotinamide adenine dinucleotide phosphate reduced (NADPH) cytochrome P450 reductase (CPR) to P450 C21.

Methods: The effect of P450 C21 Ab binding on the conformation of recombinant P450 C21 in yeast microsomes was studied using an analysis of the dithionite-reduced CO difference spectra. The effect of P450 C21 Abs on electron transfer was assessed by analysis of reduction of P450 C21 in the microsomes in the presence of CO after addition of NADPH.

Results: Our studies confirmed the inhibiting effect of P450 C21 Abs on P450 C21 enzyme activity. Binding of the Abs did not induce significant change in the P450 C21 peak at 450 nm (native form) and did not produce a detectable peak at 420 nm (denatured form) in the dithionite-reduced CO difference spectra. This indicated that conformation of P450 C21 around the heme was not altered compared with the native structure. However, incubation of the P450 C21 in yeast microsomes with P450 C21 Ab inhibited the fast phase electron transfer from the CPR to P450 C21.

Conclusions: Our observations suggested that the mechanism by which P450 C21 Abs inhibit P450 C21 enzyme activity most likely involves inhibition of the interaction between the CPR and P450 C21.
Defective lymphocyte caspase-3 expression in type 1 diabetes mellitus
Authors: Vendrame Francesco , Santangelo Carmela , Misasi Roberta , Dionisi Sabrina , Gizzi Chiara , Realacci Massimo , Grassetti Daniele , Di Mario Umberto , Dotta Francesco
Published: January 2005

Objective: Activation-induced cell death (AICD) is a major mechanism in the regulation of peripheral tolerance and its impairment can determine the development of autoimmunity. In the present study, in order to evaluate the role of caspase-3 in type 1 diabetes mellitus (T1DM) AICD, caspase-3 expression was analyzed in peripheral blood lymphocytes from 37 new onset T1DM patients and from 36 normal control subjects (NC) in resting conditions and after anti-Fas-triggered apoptosis.

Methods: Caspase-3 expression was determined by semiquantitative RT-PCR and Western blot. Apoptosis was induced in activated lymphocytes by anti-Fas monoclonal antibody and quantified by flow cytometry and morphological analysis.

Results: Caspase-3 mRNA expression was reduced in resting lymphocytes in 18/37 T1DM patients and in 1/36 NC (P < 0.01). Patients studied for both Fas-mediated AICD and caspase-3 mRNA expression revealed that a reduced caspase-3 mRNA expression in resting lymphocytes occurred in all patients showing resistance to Fas-mediated apoptosis (T1DM vs NC, P < 0.02) with the exception of 3 patients who exhibited normal caspase-3 expression levels. Caspase-3 protein analysis confirmed mRNA data and showed an impaired expression of caspase-3 active form in T1DM subjects compared with NC.

Conclusions: Our data show that defective expression and function of caspase-3 in peripheral lymphocytes of T1DM patients may contribute to the development of AICD resistance in type 1 diabetes.
Regulation of H2O2 generation in thyroid cells does not involve Rac1 activation
Authors: Fortemaison N , Miot F , Dumont J E , Dremier S
Published: January 2005

Objectives: The H2O2generating system of the thyrocyte and the O2−generating system of macrophages and leukocytes present numerous functional analogies. The main constituent enzymes belong to the NADPH oxidase (NOX) family (Duox/ThOX for the thyroid and NOX2/gp91phoxfor the leukocytes and macrophages), and in both cell types, H2O2generation is activated by the intra-cellular generation of Ca2+and diacylglycerol signals. Nevertheless, although the controls involved in these two systems are similar, their mechanisms are different. The main factors controlling O2−production by NOX2 are the cytosolic proteins p67phoxand p47phox, and Rac, a small GTP-binding protein. We have previously reported that there is no expression of p67phoxand p47phoxin thyrocytes. Here, we investigated whether Rac1 is an actor in the thyroid H2O2-generating system.

Design and methods: Ionomycin- and carbamylcholine-stimulated H2O2generation was measured in dog thyroid cells pretreated with theClostridium difficiletoxin B, which inhibits Rac proteins. Activation of Rac1 was measured in response to agents stimulating H2O2production, using the CRIB domain of PAK1 as a probe in a glutathione S-transferase (GST) pull-down assay.

Results: Among the various agents inducing H2O2generation in dog thyrocytes, carbamylcholine is the only one which activates Rac1, whereas phorbol ester and calcium increase alone have no effect, and cAMP inactivates it. Moreover, whereas toxin B inhibits the stimulation of O2generation by phorbol ester in leukocytes, it does not inhibit H2O2generation induced by carbamylcholine and ionomycin in dog thyrocytes.

Conclusions: Unlike in leukocytes, Rac proteins do not play a role in H2O2generation in thyroid cells. A different regulatory cascade for the control of H2O2generation remains to be defined.
Serum parathyroid hormone (PTH) levels in smokers and non-smokers. The fifth Tromsø study
Authors: Jorde R , Saleh F , Figenschau Y , Kamycheva E , Haug E , Sundsfjord J
Published: January 2005

Objective: Smoking is associated with reduced bone density and calcium absorption, and reduced serum levels of vitamin D. A compensatory increase in serum parathyroid hormone (PTH) would therefore be expected as a result of an altered calcium balance. However, reports on PTH levels in smokers are conflicting. As serum PTH levels give important information on the calcium balance, the PTH levels in smokers are of interest.

Subjects and methods: In the fifth Tromsø study, smoking status was recorded and serum PTH measured in 7896 subjects. Intakes of calcium and vitamin D were evaluated with a food-frequency questionnaire. In a follow-up study on 205 subjects, serum 25-hydroxyvitamin D, calcium absorption, and renal excretion of calcium were measured in addition.

Results: The serum PTH levels were significantly lower in smokers than non-smokers (3.1±1.4 vs 3.6±1.9 pmol/l in males; 3.1±1.5 vs 3.6±1.8 pmol/l in females (P< 0.001) after correcting for confounding variables, linear regression). In the smokers, there was no association between number of cigarettes smoked and serum PTH. One year after quitting smoking, serum PTH levels were similar to those of people who had never smoked. The smokers had significantly lower intake of vitamin D, lower serum levels of 25-hydroxyvitamin D and lower calcium absorption. The intake of calcium and the renal excretion of calcium were similar to that in non-smokers.

Conclusions: Smokers have lower serum PTH levels than non-smokers. This cannot be explained by the predictors of serum PTH measured in our study.
Influencing the between-feeding and endocrine responses of plasma ghrelin in healthy dogs
Authors: Yokoyama Masayuki , Nakahara Keiko , Kojima Masayasu , Hosoda Hiroshi , Kangawa Kenji , Murakami Noboru
Published: January 2005

Objectives: Ghrelin has recently been isolated from rat and human stomach as an endogenous ligand for the growth hormone (GH) secretagog receptor. Using beagle dogs, we investigated the distribution of ghrelin in the stomach and its possible role.

Methods: We examined: (i) GH release in response to ghrelin injection (0.5 or 5 μg/kg, i.v.), (ii) gastric localization of ghrelin-immunostained cells, (iii) changes in daily food consumption after ghrelin injection (3, 10, and 20 μg/kg, i.v.), (iv) plasma ghrelin levels under regular, but restricted feeding conditions, and (v) variations in plasma ghrelin levels in relatively lean, normal and obese dogs.

Results: Administration of ghrelin to dogs promptly increased circulating GH concentrations, although this effect was transitory and was maintained for only 20 min. Ghrelin was localized in the stomach fundus and body, but none was detected in either the pylorus or cardia. Administration of ghrelin at a dose of 20 μg/kg increased the daily food intake of beagle dogs. Plasma ghrelin levels peaked just before meal times, and then returned to basal levels. Obese dogs had higher plasma ghrelin levels than did normal and lean dogs.

Conclusions: These results indicate that ghrelin is a potent GH secretagog in dogs. The distribution of ghrelin-immunoreactive cells in the canine stomach resembles that of both the murine and human stomach. Ghrelin participates in the control of feeding behavior and energy homeostasis in dogs and may, therefore, be involved in the development of obesity.
Prognostic significance of successful ablation with radioiodine of differentiated thyroid cancer patients
Authors: Verburg Frederik A , de Keizer Bart , Lips Cornelis J M , Zelissen Pierre M J , de Klerk John M H
Published: January 2005

Objectives: Currently, little is known about the prognostic significance of achieving successful ablation with the first dosage of I-131 in patients with differentiated thyroid cancer. This study aimed to assess the following: (i) whether successful or unsuccessful ablation at post-ablation follow-up has prognostic consequences; (ii) possible factors predicting success of ablation in a patient.

Methods: In order to do this, we retrospectively studied 180 patients with a median follow-up of 55 months. Ablation was considered to be successful if 1 year after the initial dosage of I-131 patients fulfilled all of the following criteria: not dead from thyroid cancer, no additional therapy needed for any kind for thyroid cancer within the first year, undetectable thyroglobulin (Tg) levels under TSH stimulation, and negative I-131 scintigraphy. Tg levels at the time of ablation (P < .001), lymph node metastasis (P = 0.04) and distant metastasis (P < .001) have a significant influence on the success of ablation. P values were calculated by Mann–Whitney U test and Chi-square test, respectively.

Results: Patients with successful ablation had a better prognosis than those with unsuccessful ablation: disease-free survival was 87% versus 49% after 10 years; additionally, thyroid-cancer related survival was 93% versus 78%.

Conclusion: We conclude that the extent of the remaining normal or neoplastic thyroid tissue influences the outcome of ablation, and that successful ablation leads to a better prognosis. It seems that it is very important to achieve complete ablation as soon as possible in order to ensure the best possible prognosis for a patient.
Long-term maintenance of the anabolic effects of GH on the skeleton in successfully treated patients with acromegaly
Authors: Biermasz Nienke R , Hamdy Neveen A T , Pereira Alberto M , Romijn Johannes A , Roelfsema Ferdinand
Published: January 2005

Introduction: The anabolic actions of growth hormone (GH) are well documented. In acromegaly, the skeletal effects of chronic GH excess have been mainly addressed by evaluating bone mineral density (BMD). Most data were obtained in patients with active acromegaly, and apparently high or normal BMD was observed in the absence of hypogonadism. Data on BMD are not available after successful treatment of acromegaly. Whether the positive effect of GH excess on bone mass is maintained in the long term after clinical and biochemical cure of acromegaly remains to be established.

Patients and methods: In a cross-sectional study design, lumbar spine and femoral neck BMD was measured in 79 acromegalic patients cured or well controlled on octreotide treatment (45 male and 34 female patients; mean age 57±1 years). Successful treatment (by surgery, radiotherapy and/or use of octreotide) was defined as normal age-adjusted IGF-I. Mean time after biochemical remission was 10.2±7 years.

Results: Normal or increased BMD was observed at the femoral neck and lumbar spine in both men and women in remission after treatment for acromegaly. Similar results were obtained in patients in remission for 5 years or longer. Osteoporosis was present in 15% of the patients, with similar prevalence in men and women. There was no relationship between BMD and duration or severity of GH excess before treatment, gonadal status and presence of pituitary hormone deficiencies. Pituitary irradiation was a strong negative predictor of bone mass at the femoral neck. Long-term bone loss was observed only at the femoral neck.

Conclusion: Our data suggest that the anabolic effect of GH on trabecular and cortical bone remains demonstrable after remission of acromegaly, although it may not be maintained at cortical sites in the long term. In the present study, the lack of effect of gonadal status on BMD may be explained by the presence of only mild hypogonadism and by our policy of prompt hormonal replacement therapy for severe hypogonadism. The negative effect of pituitary irradiation on femoral neck BMD remains intriguing, although it is probably related to some degree of the diminished GH secretion frequently observed after this form of treatment.
Disease activity in acromegaly may be assessed 6 weeks after discontinuation of pegvisomant
Authors: Drake W M , Loureiro R A , Parkinson C , Monson J P , Besser G M , Trainer P J
Published: January 2005

Objective: Pegvisomant, a modified growth hormone (GH) molecule, is a novel medical therapy for acromegaly that functions as a GH receptor antagonist. Serum GH cannot be used as a marker of disease activity in patients taking this form of therapy, partly because GH levels rise on pegvisomant and partly because the drug cross-reacts with many routine GH assays. The purpose of this study was to assess the time for which it is necessary to discontinue pegvisomant prior to biochemical reassessment of acromegaly.

Design and methods: This was a retrospective study of 13 patients (seven male, median age 61 years, range 43–77) enrolled in two separate, open-label studies of the efficacy and tolerability of pegvisomant in the treatment of acromegaly. All had been taking a stable dose of pegvisomant (median dose 15 mg daily, range 10–30) as monotherapy for at least 3 months before discontinuing the drug. After discontinuation of pegvisomant, serum IGF-I was measured at 0, 2, 4, 6 and 8 weeks in all patients. Serum GH (single sample) was measured in nine patients at 2, 4, 6 and 8 weeks, but not at baseline on account of the cross-reactivity of pegvisomant with the GH assay.

Results: Mean serum IGF-I rose from 210±105 ng/ml (s.d.) at baseline to 392±175 ng/ml at 2 weeks after discontinuation of pegvisomant (P < 0.0001). Although there was no statistically significant change in mean serum IGF-I beyond 2 weeks (412±181, 392±152 and 399±150 ng/ml at 4, 6 and 8 weeks respectively; P = 0.13 (2 vs 4 weeks), 0.31 (4 vs 6 weeks) and 0.46 (6 vs 8 weeks), serum IGF-I rose by more than twice the interassay coefficient of variation (CV) in two of the 13 patients between weeks 2 and 4. The standard deviation of the difference in serum IGF-I between time points was calculated. The values declined from 118% (weeks 0–2) 17%, 19.7% and 10% (weeks 2–4, 4–6 and 6–8 respectively). The expected measure if there was no systematic change in base would be 15% (1.4 ×interassay CV). Mean serum GH was virtually unchanged at 2–8 weeks after cessation of pegvisomant therapy.

Conclusions: These results suggest that the activity of acromegaly may be assessed by serum IGF-I levels 6 weeks after the discontinuation of pegvisomant.