Non-tuberculous Mycobacteria isolated from lymph nodes and faecal samples of healthy slaughtered cattle and the abattoir environment.

Infections caused by non-tuberculous mycobacteria (NTM) are reported as emerging disease in many countries worldwide. The occurrence of NTM in different hosts and their implication as obligate or opportunistic pathogen remain largely unclear. Lymph nodes and faecal samples of clinically healthy Swiss cattle at slaughter were analysed for the presence of NTM. Based on the examined lymph nodes, NTM were detected in 20% of 108 cattle originating from different premises. The 22 isolates belonged to five different species of Mycobacteria (M. avium subsp. hominissuis, M. kansasii, M. persicum, "M. lymphaticum" and M. europaeum). M. avium subsp. hominissuis (63%) and M. kansasii (18%) thereby predominated and were found in lymph nodes with and without macroscopic changes. Moreover, M. persicum found in two cattle has recently been described as a human pathogen and is closely related to M. kansasii. Amongst cattle with lymph nodes positive for mycobacteria, viable NTM were occasionally also detected in bovine faeces. However, the isolated NTM species from lymph nodes and respective faecal samples (M. hassiacum, M. phlei and M. vaccae) did not coincide. Moreover, NTM species identified amongst isolates from the slaughterhouse environment clearly differed from those from lymph nodes and faecal samples, excluding cross-contamination of the tissue specimens through the environment or laboratory processing. Assuming that some NTM interfere with the detection of bovine tuberculosis (bTB), the present findings in healthy animals emphasize the need of more specific diagnostic tools for bTB eradication programs.

The sodium-calcium exchanger of bovine rod photoreceptors: K(+)-dependence of the purified and reconstituted protein.

The K(+)-dependence of the rod photoreceptor sodium-calcium exchanger was investigated using the Ca2(+)-sensitive dye arsenazo III after reconstitution of the purified protein into proteoliposomes. The uptake of Ca2+ by Na(+)-loaded liposomes was found to be greatly enhanced by the presence of external K+ (EC50 approximately 1 mM) in a Michaelis-Menten manner, suggesting that one K+ ion is involved in the transport of one Ca2+ ion. We also found a minimal degree of Ca2+ uptake in the total absence of K+. Other alkali cations, notably Rb+ and, to a lesser extent, Cs+, were also able to stimulate Na(+)-Ca2+ exchange. We also investigated the K(+)-dependence of the photoreceptor Na(+)-Ca2+ exchanger by determining the effects of electrochemical K+ gradients on the Na(+)-activated Ca2+ efflux from proteoliposomes. We found that, under conditions of membrane voltage clamp with FCCP, inwardly directed electrochemical K+ gradients (i.e., K0+ greater than Ki+) inhibited, whereas an outwardly directed electrochemical K+ gradient (i.e., Ki+ greater than K0+) enhanced, Na(+)-dependent Ca2+ efflux, consistent with the notion that K+ is cotransported in the same direction as Ca2+. The investigation of the reconstituted exchanger at physiological (i.e. Ki+ = 110 mM, K0+ = 2.5 mM) potassium concentrations revealed that the Na(+)-dependence of Ca2(+)-efflux was highly cooperative (n = 3.01 from Hill plots), indicating that at least three, but possibly four, Na+ ions are exchanged for one Ca2+ ion. Under these conditions the reconstituted exchanger showed a Km for Na+ of 26.1 mM, and a turnover number of 115 Ca2+.s-1 per exchanger molecule. Our results with the purified and reconstituted sodium-calcium exchanger from rod photoreceptors are therefore consistent with previous reports (Cervetto, L., Lagnado, L., Perry, R.J., Robinson, D.W. and McNaughton, P.A. (1989) Nature 337, 740-743; Schnetkamp, P.P.M., Basu, D.K. and Szerencsei, R.T. (1989) Am. J. Physiol. 257, C153-C157) that the sodium-calcium exchanger of rod photoreceptors cotransports K+ under physiological conditions with a stoichiometry of 4 Na+:1 Ca2+, 1K+.

[Early childhood brain damage and epilepsy. Results of a clinical and electroencephalographic cross-sectional study]. / Frühkindliche Hirnschäden und Epilepsie. Ergebnisse einer klinischen und elektroenzephalographischen Querschnittsuntersuchung.

Among 593 children treated as inpatients because of epilepsy, 191 (32.2%) showed indications of a pre- and/or perinatal brain damage. Under partial consideration of another six children (7.8%) with postnatal brain damage, the relations of various clinical and encephalographic parameters between the time of the brain damage and the occurrence of epilepsy were studied. The risk to fall ill with epilepsy after an infantile brain damage is independent of the time the brain damage took place. Children with a perinatal brain damage, however, show the prognostically more unfavourable form of epilepsy with a higher frequency of attacks and greater difficulties of influencing the disease with drugs. Children below the age of six years predominantly showed an occipital localisation of the foci spread over several brain regions and associated with a tendency to attacks while in older children temporally localised foci occurred more frequently.

Primary structure and functional expression of the Na/Ca,K-exchanger from bovine rod photoreceptors.

Complementary DNA encoding the Na/Ca,K-exchanger was isolated from bovine retina cDNA libraries. The complete full-length cDNA is approximately 4 kb long and contains an open reading frame of 3597 bp. The deduced amino acid sequence corresponds to a protein of 1199 amino acids with a calculated molecular weight of approximately 130 kDa. Hydrophobicity analysis revealed the presence of two alternating sets of hydrophobic and hydrophilic domains. There also exists a hydrophobic region at the N-terminus which may be part of a cleavable signal peptide. The protein shares limited sequence homology with the Na/Ca-exchanger from cardiac sarcolemma. Northern blot analysis indicates that the approximately 6 kb transcript is highly specific for retinal tissue. Insect cells infected with recombinant baculovirus bearing the full-length cDNA express a functional Na/Ca,K-exchanger with an apparent relative molecular weight of approximately 210 kDa, as determined by Western blotting.

Identification of the sodium-calcium exchanger as the major ricin-binding glycoprotein of bovine rod outer segments and its localization to the plasma membrane.

After neuraminidase treatment the Na+/Ca2+ exchanger of bovine rod outer segments was found to specifically bind Ricinus communis agglutinin. SDS gel electrophoresis and Western blotting of ricin-binding proteins purified from rod outer segment membranes by lectin affinity chromatography revealed the existence of two major polypeptides of Mr 215K and 103K, the former of which was found to specifically react with PMe 1B3, a monoclonal antibody specific for the 230-kDa non-neuraminidase-treated Na+/Ca2+ exchanger. Reconstitution of the ricin affinity-purified exchanger into calcium-containing liposomes revealed that neuraminidase treatment had no significant effect on the kinetics of Na+/Ca2+ exchange activation by sodium. We further investigated the density of the Na+/Ca2+ exchanger in disk and plasma membrane preparations using Western blotting, radioimmunoassays, immunoelectron microscopy, and reconstitution procedures. The results indicate that the Na+/Ca2+ exchanger is localized in the rod photoreceptor plasma membrane and is absent or present in extremely low concentrations in disk membranes, as we have previously shown to be the case for the cGMP-gated cation channel. Previous reports describing the existence of Na+/Ca2+ exchange activity in rod outer segment disk membrane preparations may be due to the fusion of plasma membrane components and/or the presence of contaminating plasma membrane vesicles.