Biomedical subjects

S Hallin

Publications and source records attributed to S Hallin.

3 recordsLinked to original sources

PubMed2005

Community survey of ammonia-oxidizing bacteria in full-scale activated sludge processes with different solids retention time.

AIMS: To study the effects of different solids retention time (SRT) on the nitrification activity and community composition of ammonia-oxidizing bacteria (AOB) in two full-scale activated sludge processes during a 5-month period. METHODS AND RESULTS: The AOB community composition was analysed using fluorescence in situ hybridization (FISH) and denaturing gradient gel electrophoresis (DGGE), and the identified populations were enumerated by quantitative FISH. Potential nitrification rates were determined in batch tests and the in situ rates were calculated from mass balances of nitrogen in the plants. Increased SRT reduced the nitrification activity, but neither the number per mixed liquor suspended solids nor community composition of AOB were affected. Two dominant AOB populations related to Nitrosomonas europaea and Nitrosomonas oligotropha were identified by FISH, whereas only the latter could be detected by DGGE. CONCLUSIONS: The effect of a longer SRT on the activity was probably because of physiological changes in the AOB community rather than a change in community composition. SIGNIFICANCE AND IMPACT OF THE STUDY: Physiological alterations of a stable AOB community are possible and may stabilize activated sludge processes. The commonly used FISH probes designed to target all beta-proteobacterial AOB does not detect certain Nitrosomonas oligotropha populations, leading to an underestimation of AOB if a wider set of probes is not used.

Ammonia↗

PubMed1999

PCR detection of genes encoding nitrite reductase in denitrifying bacteria.

Using consensus regions in gene sequences encoding the two forms of nitrite reductase (Nir), a key enzyme in the denitrification pathway, we designed two sets of PCR primers to amplify cd1- and Cu-nir. The primers were evaluated by screening defined denitrifying strains, denitrifying isolates from wastewater treatment plants, and extracts from activated sludge. Sequence relationships of nir genes were also established. The cd1 primers were designed to amplify a 778 to 799-bp region of cd1-nir in the six published sequences. Likewise, the Cu primers amplified a 473-bp region in seven of the eight published Cu-nir sequences. Together, the two sets of PCR primers amplified nir genes in nine species within four genera, as well as in four of the seven sludge isolates. The primers did not amplify genes of nondenitrifying strains. The Cu primers amplified the expected fragment in all 13 sludge samples, but cd1-nir fragments were only obtained in five samples. PCR products of the expected sizes were verified as nir genes after hybridization to DNA probes, except in one case. The sequenced nir fragments were related to other nir sequences, demonstrating that the primers amplified the correct gene. The selected primer sites for Cu-nir were conserved, while broad-range primers targeting conserved regions of cd1-nir seem to be difficult to find. We also report on the existence of Cu-nir in Paracoccus denitrificans Pd1222.

Alcaligenes↗

PubMed1986

Myotonic dystrophy treated with selenium and vitamin E.

We have previously reported the successful treatment of a patient with myotonic dystrophy with selenium and vitamin E. This paper deals with the treatment of a further five patients with myotonic dystrophy in different stages. All five patients improved subjectively and objectively in two or more respects. All improved their grip strength according to vigorimeter measurements (Martin), two normalized their gait, another two can now sit down on their heels and stand up, one patient can now walk on his toes, one can now get up from lying on the floor without using a chair and two patients have improved their physical capacity. Patients in early stages of the disease improved faster and more markedly than those in late stages. Electromyographical measurements also showed improvements, in that the myotonic discharges had diminished. The daily dose was 4 mg of Na2SeO3 and 600 mg of vitamin E. Serum concentration of selenium increased in all patients at the beginning of the treatment, but stabilized at a level slightly above the normal. No side-effects were observed.

Adult↗