Since tropical spastic paraparesis in 1985 was found to be associated with HTLV-I infection, it has been suggested that a retrovirus might be involved in multiple sclerosis (MS). Our group has studied long-term cultures of cerebrospinal fluid cells and peripheral blood mononuclear cells from MS patients and controls with the purpose of elucidating the possible involvement of a retrovirus in MS. For an extended period electron microscopical analysis (EM) of T-cell lines, derived from MS patients and controls and cultured for 4 weeks was performed. In two cultures obtained 8 months apart from a patient with progressive MS, retrovirus-like particles were observed in 1-2% of the cells examined. Recently a B-lymphoblastoid cell line (LCL) producing retrovirus-like particles and EBV was established from a 30-year-old male patient with a chronic progressive myelopathy, clinically resembling multiple sclerosis. Similar cell lines have now been established from two MS patients. The retrovirus-like particles produced by the LCL have been purified by gradient ultracentrifugation. In the purified material reverse transcriptase assays are clearly positive in the gradients where EM shows retrovirus-like particles. Antigen characterization, nucleic acid sequence analysis and antibody studies are now being performed. The retrovirus found is definitively different from other known human retroviruses. It has previously been found that 100% of patients with MS have antibodies against EBV, in contrast to controls where only 86-95% have antibodies against this virus. Previous epidemiological studies have pointed toward a post-pubertal primary EBV infection as an important event in the induction of MS disease. These studies have now been substantiated by our group. Though it is still unknown whether EBV infection is a prerequisite for development of MS or whether the 100% EBV seropositivity is a consequence of the MS disease, we have put forward the hypothesis that the etiological agent for development of MS and MS-like diseases is a new hitherto uncharacterized retrovirus, whereas development of neurologic disease is related to or even dependent on a delayed infection with a virus from the herpes group, most likely EBV. This dual infection hypothesis has been analyzed and was found to be in accordance with the most consistent epidemiological characteristics of MS. We have previously, also from epidemiological data, negated retroviruses, behaving as the known human retroviruses, as an independent cause of MS.

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To elucidate the mechanism of action of interferon-alpha (IFN-alpha), the effect on cell proliferation and protein synthesis in the human hairy cell leukemia line JOK-1 and the Burkitt's lymphoma cell line Daudi were investigated. While Daudi cells were inhibited in proliferation and in total protein synthesis, no effect was seen on JOK-1 cells. However, high-resolution two-dimensional gel electrophoresis showed that four polypeptides were induced in JOK-1 cells after IFN-alpha incubation, while an additional 11 were induced and two down-regulated in Daudi cells. Kinetic studies revealed that the changes in JOK-1 cells were only temporary (within 8-16 h) and small to moderate in magnitude (less than four-fold). In Daudi cells, the changes for two of these polypeptides were early (within 2 h), for most of them prolonged (at least 24 h), and for three of them of great magnitude (between 6- and 30-fold). Quantitative analytical assessments indicated that four IFN-alpha-inducible polypeptides, present in low amounts of untreated cells, were highly expressed only in sensitive Daudi cells upon IFN-alpha treatment. This observation might indicate a role for these polypeptides in the inhibition of cell proliferation in Daudi cells. Furthermore, six of the other IFN-alpha-modulated polypeptides were synthesized constitutively in JOK-1 cells at levels comparable to those achieved in IFN-alpha-treated Daudi cells.(ABSTRACT TRUNCATED AT 250 WORDS)

The potential nitrogen sources for the primary production in the intertidal area are nitrogen compounds obtained from mineralization in the sediment and the water column, nitrogen fixation, outflow from rivers and groundwater seeping from the mainland.The available inorganic nitrogen in the adjacent coastal waters decreases from 50-80 #mol NO 3 / 1 and 6-15 #mol NH+/1 in early spring to ca one tenth during the growing season. In the sediment of the tidal flats available ammonia and nitrate vary between 50 and 100 ~tmol/1 pw. In the salt marsh available ammonia increases from 200-300 nmol N H + / g fwt to approximately double the amount, and the available nitrate varies from 100-300 nmol NO3/g fwt (250-750 ~tmol NO~/1 pw) to ca one third during the growing season.The exchange of NH +, NO 2 and NO 3-across the sediment water interface has been estimated during tidal cycles under light and dark conditions on the tidal flats. The flux of nitrogen was dependent on the flora and fauna as well as the time of the year.The tidal activity, frequency and length of inundation are considered the driving force in a two-way process between salt marshes and adjacent coastal waters. The role of marsh sediment, tidal water and sediments of the tidal fiats as sites of accumulation, consumption and remineralization of organic matter is emphasized. The possible exchange of ammonia and nitrate between the salt marsh and the different compartments of the tidal water is discussed.

In a series of 100 acute myeloid leukemia (AML) patients defined by cytochemistry and immunophenotyping, 20 expressed T-lymphocyte associated antigens on the surface of their blasts. While 15 expressed two or more T-cell antigens, five were found to express only CD7. All patients belonged to the French-American-British type M4, and four were under the age of 40. Despite intensive chemotherapy, four never obtained a complete remission and the fifth died of relapse after an allogenic bone marrow transplantation. While 12 randomly selected T- cell antigen negative AML patients showed only few rearrangements in Ig- or T-cell receptor (TCR) genes, such genetic alterations were demonstrated in four of five patients for the TCR delta gene and in all patients for the TCR beta gene. Interestingly, DNA fragments of similar size were demonstrated in three of five patients for both the beta and delta genes. These data suggest that the solitary presence of CD7 among T-cell antigens in otherwise clearcut AML cases identifies a group of patients with similarities in antigen receptor gene configuration as well as outcome.