Converging projections from the mediodorsal thalamic nucleus and mesencephalic dopaminergic neurons to the neocortex in three species.

Previous studies in the rat have shown that the neocortical dopaminergic afferents, originating in the mesencephalon, terminate in those areas of the frontal lobe which receive projections from the mediodorsal thalamic nucleus i.e., the prefrontal cortex. In order to clarify whether this overlap is accidental for the rat or a consistent feature of several species we have compared the projection areas of the ventral tegmental area and the mediodorsal thalamic nucleus in three species, rat, opossum and tree shrew, using HRP injections in combination with glyoxylic acid histofluorescence method. The results have shown, first, that the area innervated by the mediodorsal nucleus of the thalamus is localized in a different part of the frontal lobe in each species: dorsolateral in the opossum, anteromedial, polar and suprarhinal in the rat and frontopolar in the tree shrew. Secondly, this area alone in each species receives projections from the ventral tegmental area. Thirdly, this area alone receives a dense innervation in the deep cortical layers by fluorescent fibres probably containing dopamine. The neighbouring neocortical areas receive afferents neither from the mediodorsal nucleus of the thalamus nor from the ventral mesencephalic tegmentum; their catecholamine innervation is mainly confined to the superficial layers and appears to be of noradrenergic nature. Although the techniques used did not allow a precise determination of the borders of the two projection areas and, therefore, the exact degree of overlap, it appears that mesencephalic dopaminergic innervation is a characteristic feature of the prefrontal cortex in the mammalian brain

Frequency of the CFTR 2694T/G polymorphism and its association with CFTR-related monosymptomatic disorders

More than 100 sequence polymorphisms have been identified in the CFTR gene thus far. Routine molecular diagnostic methods are aimed at the detection of the most common mutations in the CFTR gene; these do not usually include polymorphisms. Consequently, there is little data about polymorphism frequency in European populations, and there is no data at all for the Yugoslav population. Therefore, the effects of CFTR polymorphisms are not known. Conclusions about their role can be drawn from genotype-phenotype studies. The aim of this study was to determine the frequency of the 2694T/G polymorphism in a healthy Yugoslav population (control group), patients with congenital bilateral absence of vas deferens (CBAVD) and patients with chronic pancreatitis (CP). Frequencies of 2694T and 2694G alleles obtained in the healthy group were 71 and 29%, respectively; these are the first data of CFTR polymorphism frequencies in Yugoslavia. Frequencies of the 2694G allele in CBAVD patients (25%) and CP patients (26%) were similar to the frequency obtained for the healthy population (29%), leading to the conclusion that the presence of this polymorphism is not associated with these CFTR-related monosymptomatic disorders