Morphologie

Ohne Zusammenfassung     

Developmental and stage-specific expression of Smad2 and Smad3 in rat testis

Members of the transforming growth factor beta type (TGFbeta) superfamily and their receptors are expressed in the testis, and are believed to play important paracrine and autocrine roles during testicular development and spermatogenesis. The Smad proteins are downstream mediators for the family of TGFbeta growth factors. Smad2 and Smad3 are associated with both TGFbeta and activin signaling. However, very little is known about the expression and regulation of the Smad signaling proteins in the testis. In the present study, we have determined that Smad2 and Smad3 proteins are expressed in the postnatal testes of rats from 5 days to 60 days of age. Expression levels for both proteins are higher in young rats than in sexually mature rats. Smad2 and Smad3 messenger RNA levels parallel protein expression. Smad2 and Smad3 proteins are mainly localized in the cytoplasm of meiotic germ cells, Sertoli cells, and Leydig cells. Smad3 protein is localized to the nucleus of preleptotene to zygotene primary spermatocytes in young rats. Both proteins are expressed throughout all stages of the cycle of seminiferous tubules but are expressed at their lowest levels at stages VII-VIII in the seminiferous epithelium of adult rats. The presence of these downstream mediators in these cell types supports a role for TGFbeta and activin during spermatogenesis. The difference between the expression of Smad2 and Smad3 suggests that they may have different functions within the testis.     

Internalization and signal transduction of PrP106−126 in neuronal cells

Invasion of the nervous system and neuronal spread of infection are critical, but poorly understood steps in the pathogenesis of prion diseases. We have thus analyzed the internalization and signal transduction of the neurotoxic fragment of the prion protein PrP_106–126 in the rat neuroblastoma cell line B104 by fluorescence microscopy and quantification by ELISA and in primary neuronal cells from mice. Phospholipase D (PLD) is known to be an enzyme involved in the regulation of secretion, endocytosis and receptor signalling. We determined the PLD activity using a transphosphatidylation assay and could show that PLD is involved in PrP_106–126 internalization. The determination of receptor activity via quantification of ERK1/2 phosphorylation and cAMP level measurement verified the PrP_106–126-induced signal transduction in B104 cells and primary neuronal cells. PrP_106−126-induced a decrease in cAMP level in neuronal cells. These studies indicate the involvement of PLD in PrP_106–126-endocytosis and mediated cellular signalling by an unidentified inhibitory G-protein-coupled receptor and may allow the development of therapeutic agents interfering with prion uptake and/or PLD function using PLD as a possible pharmaceutical target.     

Differences in the perception of seven behaviour‐modifying techniques in paediatric dentistry by undergraduate students using lecturing and video sequences for teaching

Whilst preparing undergraduate students for a clinical course in paediatric dentistry, four consecutive classes (n = 107) were divided into two groups. Seven behaviour‐modifying techniques were introduced: systematic desensitization, operant conditioning, modelling, Tell, Show, Do‐principle, substitution, change of roles and the active involvement of the patient. The behaviour‐modifying techniques that had been taught to group one (n = 57) through lecturing were taught to group two (n = 50) through video sequences and vice versa in the following semester. Immediately after the presentations, students were asked by means of a questionnaire about their perceptions of ease of using the different techniques and their intention for clinical application of each technique. After completion of the clinical course, they were asked about which behaviour‐modifying techniques they had actually used when dealing with patients. Concerning the perception of ease of using the different techniques, there were considerable differences for six of the seven techniques (P < 0.05). Whilst some techniques seemed more difficult to apply clinically after lecturing, others seemed more difficult after video‐based teaching. Concerning the intention for clinical application and the actual clinical application, there were higher percentages for all techniques taught after video‐based teaching. However, the differences were significant only for two techniques in each case (P < 0.05). It is concluded that the use of video based teaching enhances the intention for application and the actual clinical application only for a limited number of behaviour‐modifying techniques.     

Immunohistochemical Diagnosis of Disseminated Intravascular Coagulation in Newborns

Disseminated intravascular coagulation (DIC) and other clotting abnormalities are common in sick newborn infants who have a variety of conditions. To document evidence of DIC at autopsy, immunoperoxidase staining of fibrin-related antigens (FRA) was used to detect intravascular microthrombi in liver, kidney, and lung from 127 newborns. Patients were selected from seven major disease groups: hyaline membrane disease/bronchopulmonary dysplasia, infection, meconium aspiration, necrotizing enterocolitis, congenital heart disease, other congenital anomalies, and extreme prematurity. Staining for FRA in intravascular microthrombi was seen in 40% of cases studied. The liver showed the highest frequency of intravascular microthombri, located predominantly in the sinusoids. Unlike the adult kidney, the newborn kidney seldom had evidence of intravascular coagulation. Extravascular staining of FRA was observed in the renal distal tubular epithelium in 48 cases, many of which also had evidence of intravascular FRA staining. No significant differences in FRA staining patterns were seen among the disease groups except for cases of extreme prematurity in which all tissues showed minimal staining. Control tissues from SIDS patients also showed minimal FRA staining. Hepatic sinusoidal staining was the only tissue finding that correlated with thrombocytopenia, a clinical indicator of DIC. Despite the use of this immunohistochemical staining method, discrepancies between the clinical and autopsy diagnosis of DIC remain.     

Immune response to caprine arthritis-encephalitis virus surface protein induced by coimmunization with recombinant vaccinia viruses expressing the caprine arthritis-encephalitis virus envelope gene and caprine interleukin-12

The objective of this study was to determine if interleukin (IL)-12 can focus an antigen specific type 1 immune response characterized by activation of Th1 lymphocytes and production of IgG2 antibodies in vivo. Saanen goats co-immunized with recombinant vaccinia viruses expressing caprine IL-12 (rRB-IL12) and the caprine arthritis-encephalitis virus (CAEV) envelope (env) gene (rWR-63) were evaluated for development of immune responses to the CAEV env encoded surface glycoprotein (SU). Immune responses were defined by: (i) SU antibody titers; (ii) the ratio of SU IgG1 and IgG2 antibodies; (iii) interferon gamma (IFNgamma) and IL-4 gene expression and proliferative response of SU stimulated lymph node mononuclear cells (LNMC). Apart from enhancement of IFNgamma and IL-4 gene expression in SU stimulated LNMC, rRB-IL12 did not affect the immune response to rWR-63 encoded SU. Thus, localized production of exogenous species specific IL-12 at the site of immunization did not focus initial priming of antigen reactive Th lymphocytes. These results are in contrast to previous studies using inbred mice and raise questions regarding the use of cytokine adjuvants to focus immune responses in outbred animals.