Investigation of a potential electrogenic transport-system for myo-inositol in the small intestine of laying hens

1. Myo-inositol (MI) is an essential metabolite for cell function in animals and humans. The aim of this study was to characterise the transport mechanism of MI in the small intestine of laying hens as there is a lack of knowledge about the MI uptake mechanisms. The hypothesised secondary active, cation coupled transport of MI was assessed by electrophysiological measurements with Ussing chambers, and was compared to the electrophysiology of glucose transport.2. Twenty-six laying hens were used. The potential ion-dependent transport was tested in tissue of the small intestine. Barrier function of the tissue was shown by determining the transepithelial resistance. During the experiments, mucosal and serosal buffers were sampled to measure time-dependent changes in MI concentrations. Samples from eight hens were further used for Western blot analyses of the jejunal apical membranes.3. Active MI transport, indicated by changes in the short circuit current after MI addition, could not be demonstrated in the Ussing chambers experiments. MI was further not detectable in the serosal buffer, nor in the lysates of mucosal tissue cytoplasm nor lipids. Thus, there was no evidence for a MI transport or absorption. However, Western blot analyses of the jejunal apical membrane revealed signals indicated the expression of the MI transport proteins SMIT-1 and SMIT-2.4. In conclusion, the MI transport process in the chicken intestine is more complex than it was presumed and is probably influenced by still unknown regulations or metabolic processes.

Comparison of the effects of gelatin and a modern hydroxyethyl starch solution on renal function and inflammatory response in elderly cardiac surgery patients

BACKGROUND

The effects of hydroxyethylstarch (HES) 130/0.4 6% and gelatin 4% on inflammation, endothelial integrity, and renal function after cardiac surgery were compared.

METHODS

Sixty patients aged >80 yr undergoing cardiac surgery were randomized to receive gelatin (n=30) or HES 130/0.4 (n=30). The colloid was used in the priming of the cardiopulmonary bypass circuit (500 ml) and for volume replacement until the second postoperative day (POD). Serum creatinine, creatinine clearance, IL-6, IL-10, intercellular adhesion molecule-1 (sICAM-1), urinary glutathione transferase-alpha, and neutrophil gelatinase-associated lipocalin (NGAL) were measured perioperatively. Serum creatinine was also reported approximately 60 days after discharge.

RESULTS

The mean(sd) volume of gelatin infused was 4180(440) ml, which was greater than the volume of HES infused 2910(330) ml (P=0.002). The mean(sd) volume of serum creatinine on the first POD was 151(24) micromol litre(-1) in the gelatin group and 126(13) micromol litre(-1) in the HES group (P=0.004). Values for the second POD were 161(0.26) and 133(16) micromol litre(-1), respectively (P=0.004). Creatinine clearance was lower in the gelatin group on the first POD [37(7) vs 46(8) ml min(-1) 1.73 m2 (P=0.004)] and the second POD [32(8) vs 45(10) ml min(-1) 1.73 m2 (P=0.002)]. Kidney function approximately 60 days after discharge did not differ between the groups. IL-6, IL-10, and sICAM-1 were significantly lower in the HES group than in the gelatin group on the first and second PODs. Urinary alpha-GST increased in both groups to a comparable extent. Urinary NGAL concentrations were higher in the gelatin than in the HES patients 5 h after surgery and on the first and second PODs.

CONCLUSIONS

In cardiac surgery patients aged >80 years, volume therapy with HES 130/0.4 6% was associated with less marked changes in kidney function and a less marked endothelial inflammatory response than gelatin 4%.

Expression and biotinylation of a mutant of the transcarboxylase carrier protein from Propioni shermanii

A deletion mutant (residues 10 to 48 cut) of the biotinyl subunit (tcc) from the enzyme transcarboxylase (EC 2.1.3.1) of Propioni shermanii was overexpressed in Escherichia coli. Complete biotinylation of the protein was achieved by addition of exogenous biotin and coexpression of the biotin holoenzyme synthetase (EC 6.3. 4.15.) from E. coli. The transcription of both genes was put under control of different operators/promoters, thus achieving independent control of expression levels and optimized yields of the holo-tcc. Bacteria were grown in a biotin-supplemented minimal medium (M9) that contained [(13)C]glucose as the carbon source and [(15)N]NH(4)Cl as the sole nitrogen source. The target protein could be purified to homogeneity by ion-exchange chromatography and concentrated to NMR-suitable concentrations (2 mM) without aggregation.