Larch arabinogalactan for hepatic drug delivery: isolation and characterization of a 9 kDa arabinogalactan fragment.

Purified arabinogalactan [AG(37 kDa)] from Larix occidentalis is composed of repeating units of similar molecular weight and composition. A 9 kDa arabinogalactan [AG(9 kDa)] has been obtained in high yield from AG(37 kDa) either by autoclaving at 121 degrees C or by exposure to alkaline solution in the presence of sodium borohydride. The weight average molecular weight of AG(37 (kDa) was determined to be 37 and 38 kDa by intensity light scattering and sedimentation equilibrium, respectively. The weight average molecular weight of AG(9 kDa) was determined to be 9.1 and 9.5 kDa by intensity light scattering and sedimentation equilibrium, respectively. MALDI-TOF mass spectrometry yielded a molecular weight at the peak of the distribution of 8.3 kDa for AG(9 kDa). Both AG(37 kDa) and AG(9 kDa) exhibited narrow molecular-weight distributions (Mw/Mn approximately 1.2). AG(37 kDa) and AG(9 kDa) exhibit nearly identical 13C-NMR spectra, monosaccharide composition, and sugar linkages. It is proposed that AG(37 kDa) is composed of covalently bound subunits of AG(9 kDa). AG(37 kDa) and AG(9 kDa) bind isolated hepatocyte asialoglycoprotein receptor equally well. As a result AG(9 kDa) is a candidate for use in hepatocyte directed drug delivery and may be more desirable for such use than is AG(37 kDa).

Cognitive function in diabetes mellitus: the effects of duration of illness and glycaemic control.

Post-mortem studies suggest that chronic, poorly controlled diabetes mellitus might be associated with degenerative changes in the central nervous system. However, the evidence that these changes are reflected in any impairment of cognitive performance is equivocal. The study reported here evaluated the effects of duration of illness and glycaemic control upon memory function in 40 cases of insulin-dependent diabetes mellitus (IDDM). Duration of illness was inversely related to performance, but degree of glycaemic control had no effect at all. This suggests that any impairment of cognitive function associated with IDDM is more likely to be attributable to the impact of suffering from a life-threatening disease rather than to organic neurological damage. The effect of chronicity was somewhat more pronounced in the case of concrete material than in the case of abstract material, and it is suggested that chronic IDDM might be associated with a specific impairment in elaborative encoding.

Mass mortality of harbor seals: pneumonia associated with influenza A virus.

More than 400 harbor seals, most of them immature, died along the New England coast between December 1979 and October 1980 of acute pneumonia associated with influenza virus, A/Seal/Mass/1/180 (H7N7). The virus has avian characteristics, replicates principally in mammals, and causes mild respiratory disease in experimentally infected seals. Concurrent infection with a previously undescribed mycoplasma or adverse environmental conditions may have triggered the epizootic. The similarities between this epizootic and other seal mortalities in the past suggest that these events may be linked by common biological and environmental factors.

Some problems in assessing the physiological and economic significance of hypocupraemia in beef suckler herds.

Factors influencing the incidence of hypocupraemia and responses to copper therapy were investigated in three beef suckler herds calving in spring and early summer. On farm A hypocupraemia was most severe (plasma copper less than 0.4 mg per litre) in March for the cows and in October/November for their calves. On farm B plasma copper levels were 30 per cent lower in five to eight-year-old cows than in two-year-old cows in late November. Administration of copper (100 mg) in late pregnancy significantly increased plasma copper in the suckled calves on farm A but not in their dams after parturition. Growth of the calves was not increased. The alleviation of severe hypocupraemia on a third farm (C) by injecting the calf with copper did not improve growth rate. It is concluded that in some areas a severe seasonal hypocupraemia may be tolerated without loss of productivity.