Differential activities of the RET tyrosine kinase receptor isoforms during mammalian embryogenesis

The RET receptor tyrosine kinase has a critical role in kidney organogenesis and the development of the enteric nervous system. Two major isoforms, RET9 and RET51, differ in the amino acid sequence of the C-terminal tail as a result of alternative splicing. To determine the roles of these isoforms in vivo, we used targeted mutagenesis to generate mice that express either RET9 or RET51. Monoisoformic RET9 mice, which lack RET51, are viable and appear normal. In contrast, monoisoformic RET51 animals, which lack RET9, have kidney hypodysplasia and lack enteric ganglia from the colon. To study the differential activities of the two RET isoforms further, we generated transgenic mice expressing ligand-dependent and constitutively active forms of RET9 or RET51 under the control of the Hoxb7 regulatory sequences. Such RET9 transgenes are capable of rescuing the kidney agenesis in RET-deficient mice or causing kidney hypodysplasia in wild-type animals. In contrast, similar RET51 transgenes fail to rescue the kidney agenesis or cause hypodysplasia. Our findings show that RET9 and RET51 have different signaling properties in vivo and define specific temporal and spatial requirements of c-Ret function during renal development and histogenesis of the enteric nervous system.     

Neonatal hypothyroidism induces striatal dopaminergic dysfunction

Oral administration of the antithyroid drug methimazole (50 mg/kg per day) to rats during the last six days of pregnancy, and subsequent daily s.c. injection of methimazole (20-30 mg/kg) to their pups from birth to postnatal day 30 provoked hormonal and somatic alterations resembling (with all caution to any association between rodent and human data) those of congenital hypothyroidism. The steady-state concentrations of striatal dopamine were similar in hypothyroid and euthyroid, 32-day-old rats, while the levels of the dopamine metabolites 3,4-dihydroxyphenylacetic and homovanillic acids were markedly decreased in hypothyroidism. The results of this and our earlier study [Vaccari A. and Gessa G. L. (1989) Neurochem. Res. 14, 949-955] show that the maximal synaptosomal uptake of [3H]dopamine, an index for the density of nigrostriatal dopaminergic terminals, and the maximum number of membrane [3H]tyramine binding sites, reflecting the concentration of the vesicular transporter for dopamine, were decreased in the hypothyroid striatum. There was also a loss of those D1-type dopaminergic receptors claimed to be located on neurons intrinsic to the striatum, and, consequently, dopamine-stimulated, D1-regulated adenylate cyclase activity was depressed. It is suggested that individual dopaminergic nerve endings in the neonatal hypothyroid striatum must contain more dopamine, owing to some loss of pertinent innervation and, therefore, to the presence of less vesicular transport sites for dopamine. Hypothyroidism-related decreases in the maximum number of striatal D1- and, reportedly, D2-receptors, plus the impairment of D1-coupled second messenger activity, may play a role in the derangement of those neurobehavioural patterns where a dopaminergic regulation is putatively implied.     

Paraganglioma (chemodectoma) of the larynx. Presentation of 2 cases

Two rare cases of laryngeal paraganglioma are reported. The first patient was a 14-year-old girl, that had a new laterocervical paraganglioma, 4 years after the excision of a laryngeal tumor. The other patient was a 33-year-old man. In both the cases, the diagnosis was made on histopathological ground and the tumors displayed the typical histological pattern of paragangliomas: epithelioid tumor cell arranged in nests (Zell-ballen) in a vascular stroma. Neoplastic cells were found to contain argyrophil granules and chromogranin. Laryngeal paragangliomas reported in the literature are 73, they generally are supraglottic, show no sex predilection and prefer the V-VII decades of age.     

Magnetic resonance imaging of the brain stem

Magnetic resonance imaging of 30 normal volonteers' posterior fossae was performed on a CGR Magniscan machine with a magnetic field strength of 0.5 Tesla. We chose the inversion recovery signal with a Tr of 2,000 ms, a TE of 21 ms and an inverse time of 500 ms. This sequence gives a better definition of the grey matter, the white matter and the CSF. To study the brain stem we suggest 8 horizontal and 3 sagittal sections.     

Analysis of human prenatal and postnatal thymocytes with the anti-Tac monoclonal antibody and recombinant interleukin-2

The expression of the interleukin-2 (Il-2) receptor on the cell surface membrane of human prenatal and postnatal thymocytes has been studied by flow cytometry. The in vitro responsiveness of these thymocytes to human recombinant Il-2 (rIl-2) was also studied. Prenatal and postnatal thymocytes contained very few Tac positive cells. The different T cell antigens T6, T3, T4, T8, T9, T10, 3A1 and T11 were expressed by the first trimester of fetal development. Recombinant Il-2 alone was able to induce proliferation of human prenatal and postnatal thymocytes. From this study and data in the literature we conclude that hither-to a thymic precursor cell carrying the interleukin-2 receptor as is the case for the murine thymus has not been found in man.     

Cytotoxic T lymphocytes generated across and I-Ab mutant difference are directed against a molecule bearing Ia antigens

The recently discovered B6.C-H-2bm12 (bm12) histocompatibility mutant bears a mutation of the I-A subregion of the H-2b haplotype. We have studied cytotoxic T lymphocytes (CTL) generated in secondary mixed lymphocyte culture (MLC) between the bm12 mutant and the strain of origin C57BL/6 (B6). In both directions, strong CTL responses were generated against lipopolysaccharide-stimulated, but not against concanavalin A-stimulated target cells. Studies of the specificity of the bm12 anti-B6 CTL response, using target cells from a panel of H-2 recombinants, showed that the CTL were directed against specificities of the I-Ab subregion. This conclusion was confirmed by the observation that the bm12 anti-B6 CTL could be specifically blocked by anti-Iab, but not by anti-Kb antisera. EL4 tumor cells, which express Kb and Db but not Iab antigens, were not lysed by the CTL. The combined data confirm that bm12 is an I-A subregion mutant and indicate that the I-A subregion antigens, recognized by antibody and those recognized by CTL, are probably present on the same molecules. The CTL effector cells generated in secondary MLC across the I-Ab mutant difference had the surface phenotype Lyt 1- 2+.     

Increased HLA-DR homozygosity associated with pre-eclampsia

It is generally accepted that maternal recognition of paternally derived fetal antigens occurs during normal pregnancy and may be beneficial for implantation and maintenance of gestation. Thus, we have investigated the human leukocyte class II DR antigens (HLA-DR), whose role in self and non-self recognition is well known, in women with pre-eclampsia, their partners and in control couples. The HLA-DR antigens were tested in 70 pre-eclamptic primigravidae women and their partners and 70 healthy control couples using the serological Terasaki technique. Our results did not show any particular HLA-DR antigen to be correlated with pre-eclampsia, but a statistically significant increase of only one identifiable HLA-DR antigen, which was presumed to express homozygosity at the HLA-DR locus, in the pre-eclamptic women and their partners: 67.1 versus 7. 9% in the control couples (P < 0.000001). The analysis of HLA-DR compatibility between pre-eclamptic women and their partners showed a statistically highly significant increase of the female-to-male compatibility (P = 0.0003) and a lower but significant male-to-female compatibility in comparison with controls (P = 0.014). From our results, it emerges that HLA-DR homozygosity and reduced antigenic disparity seem to be associated to a major risk for pre-eclampsia, which consequently appears to be a 'couple's disease'.     

Inflammation, depressive symptomtology, and coronary artery disease

OBJECTIVE: Many patients feel exhausted or depressed before the onset of an acute coronary event, but little is known about the origin of these feelings. We tested the hypothesis that the depressive symptomatology is associated with a reactivation of latent viruses and inflammation of a coronary vessel. METHODS: A blood sample was drawn and a biopsy sample was obtained from the coronary lesion of 15 exhausted and 15 nonexhausted patients treated with directional coronary angioplasty because of severe angina. Blood samples were analyzed to measure antibody titers against Chlamydia pneumoniae, cytomegalovirus, and the cytokines interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha. The biopsy sample was analyzed for the presence of IL-1beta and TNF-alpha. RESULTS: Exhausted/depressed patients had higher antibody titers against cytomegalovirus, higher levels of C. pneumoniae immunoglobulin G, and higher levels of IL-1beta and TNF-alpha. No associations between the mental state of a patient and cytokine mRNA in the biopsy sample were found. CONCLUSIONS: The findings indicate that the mental state of angioplasty patients is positively associated with serological markers of inflammation. It remains to be seen whether the inflammation causes feelings of exhaustion, whether exhaustion and depression set the stage for inflammation, or whether existing feelings of exhaustion are amplified by the inflammation.     

Clonal heterogeneity of HLA-B27 cellular allorecognition. Delineation of immunodominant sites

The fine specificity of nine cytolytic T lymphocyte (CTL) clones obtained after stimulation of HLA-B27- responder lymphocytes with B27.1+ lymphoblastoid cell lines has been analyzed. These clones defined three different reaction patterns when tested against a panel of target cells including those expressing all known HLA-B27 subtypes: (a) specific recognition of HLA-B27.1, B27.2 and B27d, (b) selective reactivity with B27.1, B27d and HLA-B40 and (c) selective recognition of B27.1, B27.2, B27d, B27f and B40. Representative clones within each group were analyzed in detail. Differences in lytic ability of the various susceptible targets within each group were established by cold target inhibition analyses and by blocking experiments with anti-CD3 and anti-CD8 monoclonal antibodies. When correlated with the known structure of the HLA-B27 subtypes, these results demonstrate the critical relevance of amino acid changes within residues 77-81 and at position 152 in modulating allospecific CTL recognition of HLA-B27.1 and suggest that these residues could be involved in the structure of immunodominant regions of this antigen. The observed cross-reactions with HLA-B40, differing from B27.1 in 16 amino acid residues, suggest that the simultaneous occurrence of multiple amino acid changes could have mutually compensatory effects, so that a cross-reactive epitope might result from various combinations of polymorphic residues.