How does the brain control the process of puberty?

Summary Puberty is commonly thought to occur as a consequence of the decrease in sensitivity of certain hypothalamic neurons to the negative feedback effect exerted by gonadal steroid hormones. In view of the well-documented participation of adrenergic neurons in the central control of gonadotrophin secretion, it is proposed that the resetting of the hypothalamic gonadostat is caused by the growth and functional maturation of steroid-sensitive adrenergic systems. The ontogenetic development and certain plastic properties of hypothalamic adrenergic neurons are described. Their participation in the induction of experimental and clinical pubertas praecox and their possible mediation of nutritional effects are discussed.Work carried out in the author's laboratory has been supported by a Group Grant in Developmental Neurobiology from the Canadian Medical Research Council.     

The use of predatory soil mites in ecological soil classification and assessment concepts, with perspectives for oribatid mites

Gamasina are the main predators among the soil mesofauna and, therefore, have a crucial position in the soil food web and contribute significantly to energy and matter turnover. Ecological concepts including predatory mites in soil assessment have not yet been established, while standardized sampling, extraction, and conservation methods are available. There are reliable keys for Europe that cover most families. Few species in low dominance ranks correlate well with soil properties like soil texture and pH. Meaningful endpoints for soil assessment are community parameters that are based on the life history of the species (e.g., Maturity Index). It has been shown that the predatory mites, as well as the oribatids as a second common and widespread group of mites, fit well into a soil assessment concept comparable to RIVPACS, which was established for aquatic systems. Perspectives for future research are the development of a computer-aided identification key and the creation of a database with information on the ecology and biogeography of important species.     

Early and frequent histological recurrence of Crohn's disease in small intestinal allografts

BACKGROUND: Recurrence of Crohn's disease in small intestinal allografts, although rarely described, can cause serious morbidity and jeopardize graft survival among transplant recipients with Crohn's disease. However, systematic studies to determine the frequency, predictors, and clinical implications of recurrent Crohn's disease have not been reported METHODS: We analyzed our transplant program's experience with small intestinal allografts in patients with Crohn's disease based on retrospective review of clinical and pathological records and corresponding pathology slides. RESULTS: Of 67 patients undergoing 70 transplantations between 1998 and 2004, six adults (three males, three females; mean age 48.1 years) had Crohn's disease complicated by short gut syndrome and total parenteral nutrition failure. Four survivors surveyed endoscopically for a mean 29 (range, 20-40) months and underwent a mean 37 endoscopic examinations with biopsies (range, 31-44) while on maintenance immunosuppression. Despite absence of any endoscopic or clinical manifestations of Crohn's disease throughout this period, two patients had granulomatous enteritis characteristic of Crohn's disease in multiple biopsies, one patient in 8/44 examinations (18%) ranging from 34 days to 20 months postoperatively and the other in 6/32 examinations (19%) ranging from 20 days to 22 months postoperatively. No comparable changes occurred in 57 other patients without Crohn's disease followed endoscopically under the same protocol CONCLUSIONS: Histological recurrence of Crohn's disease may occur in small intestinal allografts despite the absence of endoscopic and clinical disease manifestations. Such recurrences are probably not rare, may occur as early as 3 weeks after transplantation, and do not necessarily portend early clinical recurrence or mandate aggressive therapy to prevent allograft loss.     

Value of image fusion using single photon emission computed tomography with integrated low dose computed tomography in comparison with a retrospective voxel-based method in neuroendocrine tumours

The objective was the evaluation of single photon emission computed tomography (SPECT) with integrated low dose computed tomography (CT) in comparison with a retrospective fusion of SPECT and high-resolution CT and a side-by-side analysis for lesion localisation in patients with neuroendocrine tumours. Twenty-seven patients were examined by multidetector CT. Additionally, as part of somatostatin receptor scintigraphy (SRS), an integrated SPECT–CT was performed. SPECT and CT data were fused using software with a registration algorithm based on normalised mutual information. The reliability of the topographic assignment of lesions in SPECT–CT, retrospective fusion and side-by-side analysis was evaluated by two blinded readers. Two patients were not enrolled in the final analysis because of misregistrations in the retrospective fusion. Eighty-seven foci were included in the analysis. For the anatomical assignment of foci, SPECT–CT and retrospective fusion revealed overall accuracies of 91 and 94% (side-by-side analysis 86%). The correct identification of foci as lymph node manifestations (n=25) was more accurate by retrospective fusion (88%) than from SPECT–CT images (76%) or by side-by-side analysis (60%). Both modalities of image fusion appear to be well suited for the localisation of SRS foci and are superior to side-by-side analysis of non-fused images especially concerning lymph node manifestations.     

Myocardial viability assessment in patients with highly impaired left ventricular function: comparison of delayed enhancement, dobutamine stress MRI, end-diastolic wall thickness, and TI201-SPECT with functional recovery after revascularization

This study compared different magnetic resonance imaging (MRI) methods with Tl²⁰¹ single photon emission computerized tomography (SPECT) and the gold standard for viability assessment, functional recovery after coronary artery bypass grafting (CABG). Twenty patients (64±7.3 years) with severely impaired left ventricular function (ejection fraction [EF] 28.6±8.7%) underwent MRI and SPECT before and 6 months after CABG. Wall-motion abnormalities were assessed by stress cine MRI using low-dose dobutamine. A segment with a nonreversible defect in Tl²⁰¹-SPECT and a delayed enhancement (DE) in an area >50% of the entire segment, as well as an end-diastolic wall thickness <6 mm, was defined as nonviable. The mean postoperative EF (n=20) improved slightly from 28.6±8.7% to 32.2±12.4% (not significant). Using the Tl²⁰¹-SPECT as the reference method, end-diastolic wall thickness, MRI-DE, and stress MRI showed high sensitivity of 94%, 93%, and 84%, respectively, but low specificities. Using the recovery of contractile function 6 months after CABG as the gold standard, MRI-DE showed an even higher sensitivity of 99%, end-diastolic wall thickness 96%, stress MRI 88%, and Tl²⁰¹-SPECT 86%. MRI-DE showed advantages compared with the widely used Tl²⁰¹-SPECT and all other MRI methods for predicting myocardial recovery after CABG.     

Association of ANKH gene polymorphisms with radiographic hand bone size and geometry in a Chuvasha population

We performed a family-based association study to test the hypothesis that genetic variation at the human orthologue of the mouse progressive ankylosis gene (ANKH) is involved in determining bone size (BS) and bone geometry (BG). The study population comprised 126 nuclear families with 574 adult Chuvashian individuals living in small villages in the Russian Federation. Quantitative bone traits were determined by analyzing plain hand radiographs. Familial correlations for all studied traits revealed a high degree of heritability in this ethnically homogeneous population. Three simple tandem repeat (STR) polymorphisms, one intragenic and two flanking markers, as well as six single nucleotide polymorphisms (SNPs) were tested. The SNPs were detected by re-sequencing experiments and covered ANKH exons with their flanking splice sites and the promoter region. We used three different transmission disequilibrium tests (TDTs) and obtained multiple significant association signals for all investigated bone traits. Alleles of several markers located at different positions of the ANKH locus, including the promoter, consistently revealed the association. The bone traits tested are closely related to bone fragility suggesting a role for ANKH in osteoporosis.