Glyceraldehyde is present in rat lens and its level is increased in diabetes mellitus.

PURPOSE: OP-lysine, a glycation product of lysine residues of proteins, has been reported to be formed with glyceraldehyde and glycolaldehyde as precursors in the lens, and has been suggested to play a role in senile cataracts. However, there has been no reliable information regarding the content of glyceraldehyde in tissues. This study determined the glyceraldehyde levels in the lenses of normal and diabetic rats. METHODS: Glyceraldehyde was derivatized to a fluorescent compound, and the compound was then quantified by high-performance liquid chromatography. RESULTS: The lens glyceraldehyde levels in normal and diabetic rats were 0.75 +/- 0.06 and 1.26 +/- 0.21 nmol/g wet weight (means +/- standard deviations of 6 animals, p < 0.01), respectively. Isolated rat lenses accumulated a higher level of glyceraldehyde when cultured for 6 days in 25.5 mM glucose than when cultured in 5.5 mM glucose. CONCLUSIONS: Glyceraldehyde was found to be present in the lens and was increased in diabetes mellitus. OP-lysine is thus likely to be a potential risk factor for senile and diabetic cataracts.

Pyridoxal-aminoguanidine adduct is more effective than aminoguanidine in preventing neuropathy and cataract in diabetic rats.

We examined the ability of a pyridoxal-aminoguanidine adduct with both antiglycation and antioxidant activities in vitro to protect against neuropathy and cataract in streptozotocin-diabetic rats and compared the result with that of aminoguanidine. In vivo antiglycation and antioxidant activities were also compared between the adduct and aminoguanidine. Diabetic rats were given either of the compounds in their drinking water (9 mM) for 7 weeks. Neither compound affected body weight, blood glucose level or urine volume. The adduct, but not aminoguanidine, significantly improved motor nerve conduction velocity. The time to develop cataract was longer in adduct-treated rats than in untreated and aminoguanidine-treated rats. The increase in opacification of lenses in culture medium containing high glucose levels (55.5 mM) was more efficiently attenuated by the adduct than by aminoguanidine. Adduct and aminoguanidine similarly lowered glycated hemoglobin levels. The level of urinary 8-hydroxy-2'-deoxyguanosine, a marker of oxidative DNA damage, and the level of liver malondialdehyde plus 4-hydroxy-2-alkenals, a marker of tissue lipid peroxidation, both of which were elevated by diabetes, were significantly reduced by the adduct but not by aminoguanidine. These findings indicate that the pyridoxal-aminoguanidine adduct is superior to aminoguanidine in preventing diabetic neuropathy and cataracts, and we suggest that this may be at least partly due to the higher antioxidant activity of the former.

Semisuperfluidity of 3He in aerogel?

According to hydrodynamic, acoustic, and NMR studies the superfluid transition temperature of 3He in aerogel ( T(a)(c)) is significantly suppressed with respect to that of bulk 3He. We have found in the range of temperatures between T(c) and T(a)(c) a large and unexpected NMR satellite line attributable to the liquid inside the aerogel. We propose that this anomalous behavior of liquid 3He corresponds to a new type of superfluid ordering related to magnetic and possibly orbital coherence.

Collected studies on interfaces and interphases as related to the behaviour of fibre-reinforced aluminium alloy composites

This paper is an essentially practical treatment of interphases and interfaces and of their influence on the properties of a number of metal matrix composites (MMCs). The illustrations are drawn from the authors' experiences and have been chosen to underline the importance of detailed microstructural analysis for elucidating the fabrication behaviour and the mechanical performance of this group of materials. The work involves a series of MMCs based upon different combinations of aluminium alloy and ceramic/carbon fibre (both continuous and short) and made using the method of low-pressure liquid metal infiltration (LMI). Detailed analyses of the composite microstructures are given, with particular attention being paid to the interface regions. The data are used to categorize an interface according to the type of bond, that is a mechanical bond resulting from thermal mismatch between the fibre and metal matrix, or a chemical bond, with or without second phase, caused by chemical reaction. The information is then employed to account for aspects of composite fabrication, such as the cast microstructure produced by the LMI method and the effect of heat treatment, and to elucidate composite properties such as stiffness, yield stress and failure strength.