Importance of macroprolactinemia in hyperprolactinemia.

Macroprolactin is an antigen-antibody complex of higher molecular mass than prolactin (>150kDa), consisting of monomeric prolactin and immunoglobulin G. The term 'macroprolactinemia' is used when the concentration of macroprolactin exceeds 60% of the total serum prolactin concentration determined by polyethylene glycol precipitation. The gold standard technique for the diagnosis of macroprolactinemia is gel filtration chromatography. The prevalence of macroprolactinemia in hyperprolactinemic populations varies between 15% and 35%. Although the pathogenesis of these antibodies is not clear, it is possible that changes in the pituitary prolactin molecule represent increased antigenicity to the immune system, leading to the production of anti-prolactin antibodies. Mild hyperprolactinemia usually occurs because macroprolactin is not cleared readily from the circulation due to its higher molecular weight. Moreover, the hypothalamic negative feedback mechanism for autoantibody-bound prolactin is inactive because macroprolactin cannot access the hypothalamus, resulting in hyperprolactinemia. Reduced in-vivo bioactivity of macroprolactin may be the reason for the lack of hyperprolactinemic symptoms. It also seems that anti-prolactin autoantibodies may compete with prolactin molecules for receptor binding, resulting in low bioactivity. Additionally, the large molecular size of macroprolactin confined in the intravascular compartment prevents its passage through the capillary endothelium to the target cells, which may be the reason for the lack of symptoms. Macroprolactinemia is considered to be a benign clinical condition in patients with normal concentrations of bioactive monomeric prolactin, with a lack, or low incidence, of hyperprolactinemic symptoms and negative pituitary imaging. In such cases with resistance to anti-prolactinaemic drugs, no pharmacological treatment, diagnostic investigations or prolonged follow-up are required. However, macroprolactinemia may also occur in patients with conventional symptoms of hyperprolactinemia who cannot be differentiated from patients with true hyperprolactinemia. These symptoms are mainly attributed to excess levels of monomeric prolactin, and this is of concern. The diagnosis of macroprolactinemia is misleading and inappropriate. A multitude of physiological, pharmacological and pathological causes, including stress, prolactinomas, hypothyroidism, renal and hepatic failure, intercostal nerve stimulation and polycystic ovary disease, can contribute to increased levels of monomeric prolactin. It is important for patients with elevated monomeric prolactin levels to undergo routine evaluation to identify the exact pathological state and introduce adequate treatment, regardless of the presence of macroprolactin. In addition, macroprolactinemia occasionally occurs due to macroprolactin associated with pituitary adenomas, with biological activity of macroprolactin comparable with that of monomeric prolactin. In cases when excess macroprolactin occurs with clinical manifestations of hyperprolactinemia, macroprolactinemia should be regarded as a pathological biochemical variant of hyperprolactinemia. An individualized approach to the management of such patients with macroprolactinemia may be necessary, and pituitary imaging, dopamine treatment and prolonged follow-up should be applied.

Ikaros family transcription factors expression in rat thymus: detection of impaired development.

The expression of Ikaros family transcription factors and consequently their signalling pathway is limiting for hematopoietic and lymphocyte development in mice and human. Due to their importance, these transcription factors are highly homologous between species. As an initial approach to examining the possible involvement of Ikaros transcription factors in pathogenesis of rat lymphoid development, we analyzed the expression of all known Ikaros family members, Ikaros, Aiolos, Helios, Eos and Pegasus in the rat thymus. We established a semi-quantitative RT-PCR to detect mRNA of each transcription factor. For the first time we give evidence of the expression of Ikaros family transcription factors in the rat thymus. Further, we evaluated whether their mRNA expression was succumbed to changes when the rats were exposed to ethanol, as a known debilitating agent during development. Therefore we analyzed the thymus of adult rats whose mothers were forced to drink ethanol during gestation, to detect possible changes in thymus mRNA expression levels of Ikaros, Aiolos, Helios, Eos and Pegasus. We found that rats prenatally exposed to ethanol show a slightly higher expression of Ikaros family transcription factors in the adult thymus when compared to control rats, but these differences were not statistically significant. We further studied the distribution of the major lymphocyte subpopulations in the rat thymus according to CD3, CD4 and CD8 expression by four color flow cytometry. We found a higher incidence of CD3 positive cells in the double positive, CD4+CD8+ thymic subpopulation of rats prenatally exposed to ethanol when compared to non-exposed animals. Our findings indicate that ethanol exposure of pregnant rats might influence the development of CD3 positive cells in the thymus of the offspring but this result should be further tackled at the level of transcription factor expression.

Local estrogen treatment in patients with urogenital symptoms.

OBJECTIVES: Determination of the efficacy and safety of vaginally administered low dose (25 microg) micronized 17beta-estradiol in the management of patients with urogenital symptoms. METHODS: A total of 1612 patients with urogenital complaints were randomized to receive 25 microg of micronized 17beta-estradiol (n=828) or placebo (n=784) in a multicenter double-blind placebo-controlled study running for 12 months. Female patients were treated once a day over a period of 2 weeks, and then twice a week for the remaining of the 12 months with an active or placebo tablet. The assessment included full history-questionnaire, micturition diary, gynecologic and cystometric examination, transvaginal ultrasound, and serum 17beta-estradiol level determination. It was carried out at the beginning, and after 4 and 12 months of treatment. RESULTS: The overall success rate of micronized 17beta-estradiol and placebo on subjective and objective symptoms of postmenopausal women with vaginal atrophy was 85.5%, and 41.4%, respectively. A significant improvement of urinary atrophy symptoms was determined in vaginal ERT group as compared with the beginning of the study (51.9% vs. 15.5%, P=0.001). The maximal cystometric capacity (290 ml vs. 200 ml, P=0.023), the volume of the urinary bladder at which patients first felt urgency (180 vs. 140, P=0.048), and strong desire to void (170 ml vs. 130 ml, P=0.045) were significantly increased subsequent to the micronized 17beta-estradiol treatment. The number of patients with uninhibited bladder contractions significantly decreased following micronized 17beta-estradiol as compared with pretreatment values (17/30, P=0.013). Side effects were observed in 61 (7.8%) patients treated with low dose micronized 17beta-estradiol. Therapy with 25 microg of micronized 17beta-estradiol did not raise serum estrogen level nor stimulated endometrial growth. CONCLUSIONS: Local administration of 25 microg of micronized 17beta-estradiol is an effective and a safe treatment option in the management of women with urogenital complaints.