Termination of cell-type specification gene programs by miR-183 cluster determines the population sizes of low threshold mechanosensitive neurons

Touch and mechanical sensations require the development of several different kinds of sensory neurons dedicated to respond to certain types of mechanical stimuli. The transcription factor Shox2 (short stature homeobox 2) is involved in the generation of TRKB+ low-threshold mechanoreceptors (LTMRs), but mechanisms terminating this program and allowing for alternative fates are unknown. Here, we show that the conditional loss of miR-183-96-182 cluster leads to a failure of extinction of Shox2 during development and an increase in the proportion of Aδ LTMRs (TRKB+/NECAB2+) neurons at the expense of Aβ slowly adapting (SA)-LTMRs (TRKC+/Runx3−) neurons. Conversely, overexpression of miR-183 cluster that represses Shox2 expression, or loss of Shox2, both increases the Aβ SA-LTMRs population at expense of Aδ LTMRs. Our results suggest that the miR-183 cluster determines the timing of Shox2 expression by direct targeting during development, and through this determines the population sizes of Aδ LTMRs and Aβ SA-LTMRs.

Visceral motor neuron diversity delineates a cellular basis for nipple- and pilo-erection muscle control

Despite the variety of physiological and target-related functions, little is known regarding the cellular complexity in the sympathetic ganglion. We explored the heterogeneity of mouse stellate and thoracic ganglia and found an unexpected variety of cell types. We identified specialized populations of nipple- and pilo-erector muscle neurons. These neurons extended axonal projections and were born among other neurons during embryogenesis, but remained unspecialized until target organogenesis occurred postnatally. Target innervation and cell-type specification was coordinated by an intricate acquisition of unique combinations of growth factor receptors and the initiation of expression of concomitant ligands by the nascent erector muscles. Overall, our results provide compelling evidence for a highly sophisticated organization of the sympathetic nervous system into discrete outflow channels that project to well-defined target tissues and offer mechanistic insight into how diversity and connectivity are established during development.

Sox2 and Mitf cross-regulatory interactions consolidate progenitor and melanocyte lineages in the cranial neural crest

The cellular origin and molecular mechanisms regulating pigmentation of head and neck are largely unknown. Melanocyte specification is controlled by the transcriptional activity of Mitf, but no general logic has emerged to explain how Mitf and progenitor transcriptional activities consolidate melanocyte and progenitor cell fates. We show that cranial melanocytes arise from at least two different cellular sources: initially from nerve-associated Schwann cell precursors (SCPs) and later from a cellular source that is independent of nerves. Unlike the midbrain-hindbrain cluster from which melanoblasts arise independently of nerves, a large center of melanocytes in and around cranial nerves IX-X is derived from SCPs, as shown by genetic cell-lineage tracing and analysis of ErbB3-null mutant mice. Conditional gain- and loss-of-function experiments show genetically that cell fates in the neural crest involve both the SRY transcription factor Sox2 and Mitf, which consolidate an SCP progenitor or melanocyte fate by cross-regulatory interactions. A gradual downregulation of Sox2 in progenitors during development permits the differentiation of both neural crest- and SCP-derived progenitors into melanocytes, and an initial small pool of nerve-associated melanoblasts expands in number and disperses under the control of endothelin receptor B (Ednrb) and Wnt5a signaling.

[Association of low 50 g glucose screening test in pregnancy and fetal retardation]

BACKGROUND

The connection between elevated blood sugar and macrosomia is sufficiently well known and studied. The following study, however, examines whether patients with lower blood sugar values--based on the result of the 50 g-glucose screening test--delivered smaller children than patients with normal blood sugar based on the current criteria of blood sugar levels. PATIENTS RESPECTIVELY AND METHODS: In this study, all patients were included who visited our Prenatal Counseling Center between September 21, 1994 and July 31, 1996. Not included were patients with one-hour values greater or equal to 140 mg/dl. For assessing the 50 g-screening tests, percentiles were used. Based on the tables of Voigt, children below the 10th percentile were considered to be growth retarded. The student's t-test and chi-square test were employed as statistical tests.

RESULTS

Of the 1416 participating patients in the study, 868 fulfilled the aforementioned criteria. A significant statistical correlation was shown between the development of fetal retardation and nicotine consumption, weight gain, and maternal height. It was also shown that patients with a lower (< 93 mg/dl) 50 g-screening test more often delivered a retarded child than patients with a normal value (23% vs. 12%, p = 0.034). No significant connection was found between the screening test groups and the described influencing factors. The clinical outcome, measured by the Apgar-scores and the transferal rate, was statistically significantly worse with the retarded children.

CONCLUSIONS

The maternal glucose metabolism influences the fetal growth not only with respect to macrosomia but also growth retardation. The growth curves that have been used until now wrongly do not take into consideration the maternal anthropometric data. In light of this, the former ought to be re-evaluated. The data of this study emphasize the necessity of need-adapted nutrition. Maybe also pregnant women with a growth retarded child need a dietary consultation.

Internal jugular vein thrombosis caused by resistance to activated protein C as a complication of ovarian hyperstimulation after in-vitro fertilization

We present a case of a 24 year old woman who became pregnant (twins) after human menopausal gonadotrophin (HMG)-induced ovarian stimulation, in-vitro fertilization (IVF) and subsequent embryo transfer. She developed a right internal jugular vein thrombosis as a complication of severe ovarian hyperstimulation syndrome (OHSS) 28 days after embryo transfer. The thrombosis developed in spite of anticoagulation with low-dose heparin. Later a resistance to activated protein C (APC) or Dahlbäck disease was diagnosed. Due to a new test procedure (accelerin inactivation test), the diagnosis was possible even under anticoagulation treatment. The coincidence of hyperstimulation and internal jugular vein thrombosis with the concurrent diagnosis of resistance to APC has not been published previously. The benefit of general screening for resistance to APC before admission to the IVF programme should be weighed. Targeted selection of a group of high-risk women would therefore be made possible.

Recurrent benign Müllerian papilloma of the vagina. Immunohistological findings and histogenesis

Vaginal papillomata are rare, particularly in children. The macroscopic appearance is suggestive of a botryoid rhabdomyosarcoma, which is more common in this age group. The histogenesis of these tumors is still controversial, the choices being mesonephric or Müllerian origin. In our case cytokeratins and intermediate filaments were looked for immunohistochemically. Squamous epithelium as well as the cylindrical epithelium expresses type I cytokeratins, an acidic polypeptide typical of cylindrical epithelium. A strong expression of EMA in both epithelial types and CEA staining of the cylindrical epithelium support the hypothesis that these papillomata derive from Müllerian epithelium. Recurrence as observed in our case has not been described before. Treatment involves the simple removal of the papilloma.

Die Wirkung verschiedener Gifte auf die Entstehung von Wasserstoff bei Belichtung anaerob inkubierter Chlorella pyrenoidosa

Mit Hilfe einer elektrochemischen H2-Meßmethode wurde ein vorübergehendes Auftreten von molekularem Wasserstoff bei Belichtung anaerob inkubierter Zellen beobachtet. Die H2-Menge lag in der Größenordnung von 1 · 10-5 Mol/l und war von der Inkubationszeit abhängig. Es wurde die Wirkung verschiedener Gifte auf diesen Effekt untersucht