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Tissue plasminogen activator (tPA) is expressed by many types of neurons in the developing and adult rodent brain. We have now mapped tPA transcripts and protein in the human central nervous system using tissue arrays and find widespread expression, in particular in neocortical mantle, thalamus, amygdala, and hippocampal pyramidal neurons. The abundant presence of tPA protein in cellular vesicles implies that its acute release, e.g. upon ischaemic stroke or trauma, could play a role in neuronal damage. We also found in patients with multiple sclerosis (MS), and to a lesser extent patients with leukaemia and encephalitis, prominently elevated tPA activity in the cerebrospinal fluid and in MS in neurons in the proximity of areas of demyelination elevated tPA mRNA and antigen levels. In addition, we observed up-regulation of tPA expression in a mouse model of MS, experimental autoimmune encephalomyelitis. Accumulating evidence implies roles for tPA in normal neural function, as well as in neurodestructive processes in humans, such as occur in MS and brain tumours and warrant further studies on expression of tPA and its regulatory molecules in neurodegenerative diseases.

Aims-To evaluate the relation between Chlamydia trachomatis infection and stillbirth, placental tissue was studied for the presence of C trachomatis. Methods-Paraffin wax embedded placental tissue of a stillbirth fetus, born at the 36th week of gestation to a 21 year old mother with high serum antibody titres to C trachomatis immunotypes during pregnancy and who was culture positive to C trachomatis three years previously, was studied by in situ hybridisation, polymerase chain reaction, and immunohistochemistry for the presence of C trachomatis. Results-C trachomatis was detected in placental specimens by in situ hybridisation and alkaline phosphatase antialkaline phosphatase staining in several sections, whereas control tissues were uniformly negative, indicating the presence of C trachomatis nucleic acid and antigen in the placenta. Conclusion-This is the first reported case in which C trachomatis has been demonstrated in the human placenta. (7 Clin Pathol 1997;50:852-855)

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