Delayed lupus nephritis.

OBJECTIVE: To describe and analyse the clinical and immunological characteristics of a large series of patients with delayed lupus nephritis (LN). METHODS: A cross-sectional study was carried out. Patients with systemic lupus erythematosus (SLE) who developed renal involvement >or=5 years after the first manifestation(s) of the disease (delayed LN, n = 48) were compared with patients with SLE in whom LN developed within 5 years or less after SLE appeared (early-onset LN, n = 187). A control group, the no LN (NLN) group, comprised patients with longstanding SLE (duration of disease >10 years) who had never shown signs of renal involvement (n = 164). RESULTS: The group with delayed LN was positively associated with Sjögren's syndrome, lung involvement and antiphospholipid syndrome as compared with early LN. However, its renal clinical expression and histopathological patterns were similar to those of early-onset LN. The frequency of anti-dsDNA, anti-Sm and anti-RNP antibodies was higher in patients with LN than in the NLN group, as was the frequency of low complement levels. Jaccoud's arthropathy was a protective factor for nephritis. CONCLUSIONS: Delayed LN is not uncommon in patients with SLE. The identified risk factors might aid in its diagnosis and enhance the ability to identify patients at risk for this complication of SLE.

Azospirillum brasilense produces the auxin-like phenylacetic acid by using the key enzyme for indole-3-acetic acid biosynthesis.

An antimicrobial compound was isolated from Azospirillum brasilense culture extracts by high-performance liquid chromatography and further identified by gas chromatography-mass spectrometry as the auxin-like molecule, phenylacetic acid (PAA). PAA synthesis was found to be mediated by the indole-3-pyruvate decarboxylase, previously identified as a key enzyme in indole-3-acetic acid (IAA) production in A. brasilense. In minimal growth medium, PAA biosynthesis by A. brasilense was only observed in the presence of phenylalanine (or precursors thereof). This observation suggests deamination of phenylalanine, decarboxylation of phenylpyruvate, and subsequent oxidation of phenylacetaldehyde as the most likely pathway for PAA synthesis. Expression analysis revealed that transcription of the ipdC gene is upregulated by PAA, as was previously described for IAA and synthetic auxins, indicating a positive feedback regulation. The synthesis of PAA by A. brasilense is discussed in relation to previously reported biocontrol properties of A. brasilense.

Cloning and characterisation of the Azospirillum brasilense glnD gene and analysis of a glnD mutant.

Nitrogen regulation in bacteria involves the capacity to sense the availability of fixed nitrogen and to translate a signal indicating nitrogen deficiency or nitrogen excess into a cellular response. One of the key enzymes in this complex regulation process, the uridylyltransferase/uridylyl-removing (UTase) enzyme, encoded by the glnD gene, was characterised in the diazotroph Azospirillum brasilense, which promotes plant growth. The glnD gene product is responsible for the uridylylation of both P(II)-like nitrogen regulatory proteins, P(II) and P(Z), depending on the nitrogen status of the cell. The nitrogen-regulated activity of the main ammonium-assimilating enzyme, glutamine synthetase, is not altered in a glnD-Tn 5-B30 insertion mutant. UTase influences processes that are regulated by the NtrB-NtrC two-component histidine protein kinase system, such as ammonium uptake and nitrate assimilation. Moreover, the glnD gene product is indispensable for the activation of nitrogen fixation. Transcription of glnD is up-regulated under nitrogen-fixing conditions. This regulation is only partially dependent on the global nitrogen regulation (Ntr) system.

Agentes fisicos y quimicos y riesgo carcinogenico. / Physical and chemical agents and carcinogenic risk

Los que se esfuerzan por identificar y reducir los riesgos ambientales tienen a su disposicion un arsenal de instrumentos cada vez mas abundante. En este articulo se examinan diversos problemas a los que se han aplicado esos instrumentos en Canada (como los riesgos carcinogenicos presentados por el cloroformo, la fluoracion del agua, la sacarina, el Tris y el radon) y se discuten las principales ventajas y deficiencias de los metodos empleados

Agentes físicos y químicos y riesgo carcinogénico / Physical and chemical agents and carcinogenic risk

Los que se esfuerzan por identificar y reducir los riesgos ambientales tienen a su disposición un arsenal de instrumentos cada vez más abundante. En este artículo se examinan diversos problemas a los que se han aplicado esos instrumentos en Canadá (como los riesgos carcinogénicos presentados por el cloroformo, la fluoración del agua, la sacarina, el Tris y el radón) y se discuten las principales ventajas y deficiencias de los métodos empleados (AU)