Reproducibility of glucose, fatty acid and VLDL kinetics and multi-organ insulin sensitivity in obese subjects with non-alcoholic fatty liver disease

OBJECTIVE

Non-alcoholic fatty liver disease (NAFLD) is associated with abnormalities in basal glucose and free fatty acid (FFA) metabolism, multi-organ insulin resistance and alterations in lipoprotein kinetics. These metabolic outcomes can be evaluated in vivo by using stable isotopically labeled tracer methods. An understanding of the reproducibility of these measures is necessary to ensure adequate statistical power in studies designed to evaluate metabolic function in subjects with NAFLD.

METHODS

We determined the degree of intra-individual variability of skeletal muscle, adipose tissue, and hepatic insulin sensitivity and basal plasma glucose, FFA, and very-low-density lipoprotein triglyceride and apolipoprotein B-100 (apoB-100) kinetics in eight obese subjects with NAFLD (age: 44 ± 3 years; body mass index: 38.2 ± 1.7 kg m(-2); intrahepatic triglyceride content: 24.5 ± 3.9%), by using the hyperinsulinemic-euglycemic clamp technique and stable isotope-labeled tracer methods and mathematical modeling on two separate occasions ∼2 months apart.

RESULTS

The intra-individual variability (coefficient of variation) ranged from 6% for basal glucose production to 21% for insulin-stimulated glucose disposal (percentage increase from basal). We estimated that a 25% difference in any outcome measure can be detected with a sample size of ≤ 8 subjects for paired studies and ≤ 15 subjects per group for unpaired studies, assuming an α value of 0.05 and a β value of 0.20 (that is, 80% power).

CONCLUSION

These results demonstrate that only a small number of subjects are needed to detect clinically relevant effects in insulin sensitivity and hepatic lipoprotein metabolism in obese subjects with NAFLD, and will be useful to determine appropriate sample size for future metabolic studies.

Additional pregnane glycoside from Baseonema acuminatum

The isolation of baseonemoside C (1), a new pregnane glycoside from the aerial parts of Baseonema acuminatum is reported.

Cinchonicine-derived alkaloids from the bark of the Peruvian Ladenbergia oblongifolia

The isolation of cinchonicine-derived alkaloids epicinchonicinol (1), cinchonidicinol (2) and a mixture of dihydrocinchonicinol and dihydrocinchonidicinol (3) from the dried bark of Ladenbergia oblongifolia, is reported along with (1)H and (13)C-NMR data.

Pregnane glycosides from Baseonema acuminatum

Two new pregnane glycosides, baseonemoside A and B, were isolated from the aerial parts of Baseonema acuminatum. Their structures were established as pregn-5-ene-3beta,16alpha,20(S)-triol 3-O-beta-D-cymaropyranosyl-(1-->4)-beta-D-digitoxopyranoside 20-O-beta-D-glucopyranosyl-(1-->2)-beta-D-digitalopyranoside 1 and pregn-5-ene-3beta,16alpha,20(S)-triol 3-O-beta-D-cymaropyranosyl-(1-->4)-beta-D-cymaropyranosyl-(1-->4)-beta-D-digitoxopyranoside 20-O-beta-D-glucopyranosyl-(1-->2)-beta-D-digitalopyranoside 2, respectively, on the basis of spectral evidence and chemical transformation.

Azaanthraquinone: an antimicrobial alkaloid from Mitracarpus scaber

An ethanolic extract of the aerial parts of Mitracarpus scaber demonstrated good antimicrobial activity. Bioassay directed fractionation of this extract led to the isolation of benz[g]isoquinoline-5,10-dione (1) as an active component. Compound 1 showed significant in vitro inhibitory activity against the AIDS-related pathogens.

Antimicrobial properties of Honduran medicinal plants

Ninety-two plants used in the traditional pharmacopoeia of the Pech and neighboring Mestizo peoples of central Honduras are reported. The results of in vitro antimicrobial screens showed that 19 of the extracts from medicinal plants revealed signs of antifungal activity while 22 demonstrated a measurable inhibitory effect on one or more bacterial cultures. Bioassay-guided fractionation of extracts from Mikania micrantha, Neurolaena lobata and Piper aduncum produced weak to moderately active isolates. The broad spectrum of activity of the extracts helps to explain the widespread use of these plants for wound healing and other applications.

Antimicrobial properties of alkaloids from Xanthorhiza simplicissima

The organic extract of the whole plant Xanthorhiza simplicissima was found to exhibit good activity against the AIDS-related opportunistic pathogens Candida albicans, Cryptococcus neoformans, and Mycobacterium intracellularae. Bioassay-directed fractionation of the extract led to the isolation of the known alkaloid berberine as the major active component. A second alkaloid of the isohomoprotoberberine family, puntarenine, was isolated from this plant family for the first time. Puntarenine also showed marginal activity against the dermatophytic fungus Trichophyton mentagrophytes and the yeast Saccharomyces cerevisiae.

Antimicrobial compounds from Petalostemum purpureum

EtOH extracts of Petalostemum purpureum demonstrated antimicrobial activity against bacteria and fungi. Bioassay-directed fractionation led to the isolation of petalostemumol [1] as the active constituent. Its structure was determined by a single crystal X-ray diffraction analysis. A minor component designated petalostemumol G [3] is believed to be an artifact of the isolation procedure. Its structure was confirmed by a single crystal X-ray analysis of its pentamethylether 2. A number of derivatives of 1 and 3, including the Me- and benzylethers and acetates, were prepared.