Ascorbic acid glycation: the reactions of L-threose in lens tissue.

L-Threose is a significant degradation product of ascorbic acid at pH 7.0 in the presence of oxygen. When compared to several other ascorbate-derived degradation products, it had the greatest ability to glycate and crosslink lens proteins in vitro. To determine whether L-threose was formed in the lens, the sugars in a TCA-soluble extract from human lenses were reduced to polyols with NaBH4, acetylated and analysed by gas-liquid chromatography. The threitol levels measured were 3.4 +/- 0.8 micrograms per lens (n = 4). GC-MS measurements made after reduction with NaBD4 indicated that threitol, but little or no threose, was originally present in the human lens. Rat lenses were incubated with [1-13C]D-threose for 24 hr, and considerable D-threitol formation was seen by NMR spectroscopy. Analysis of the lenses after medium removal showed that only [1-13C]threitol was present within the lenses indicating a rapid reduction of threose within the lens, presumably by aldose reductase. Assays with human recombinant aldose reductase and with human lens cortical and nuclear extracts all exhibited sorbinil-inhibitable aldose reductase activity with L-threose as substrate. This was confirmed by incubating a preparation of [1-14C]L-tetrose (a mixture of 40% L-threose and 45% L-erythrose) with both the pure aldose reductase and crude lens extracts followed by the subsequent identification of the [1-14C]L-threitol formed by thin layer chromatography. L-Threose degrades very slowly in 0.1 M phosphate buffer at pH 7.0, but the addition of a four-fold excess of N alpha-acetyl-L-lysine accelerated the rate of disappearance of threose 30-fold, indicating a rapid glycation reaction. When [1-14C]L-tetrose was incubated with a complete bovine lens homogenate, a linear incorporation into protein was observed over a 24 hr period. Increasing levels of lens extract exhibited increasing incorporation into protein. These data confirm a rapid reactivity of L-threose with lens protein and argue that glycation would occur in vivo in spite of the presence of aldose reductase.

Body size estimation and locus of control in obese adolescent boys undergoing weight reduction.

Body size estimation (BSE) and locus of control (LOC) were studied in 18 obese adolescent boys undergoing weight reduction. The subjects attended a seven-week summer camp which offered both increased activity and a 1200 kcal (5023 kJ)/d diet, resulting in an average weight loss of 29.2 +/- 6.3 lb (13.3 +/- 2.9 kg) and a decrease in body fat from 39.0 percent +/- 0.6 percent to 27.5 percent +/- 4.3 percent. Fatness was correlated with poor physical performance [1.5 mile (2.4 km) runs]. Weight reduction and decreased body fat resulted in an improved running time. BSE was assessed using self photographs distorted by an anamorphic lens. While subjects could correctly estimate their body size prior to weight reduction, after weight reduction they significantly underestimated body size. This finding contrasts with adults with juvenile-onset obesity who overestimate body size after weight reduction. LOC (measured by Nowicki-Strickland LOC Inventory) changed in the direction of internality after weight reduction. The use of exercise with the weight loss program may thus improve feelings of control and prevent overestimation of body size.

Incidence of plant poisonings in Philadelphia noted as poison information calls.

During a one year period, plant calls were 5.3% of the total number of poison information calls. Of all confirmed plant exposures, 6.8% developed symptoms. Of all suspected plant exposures, 3.2% developed symptoms. Most (75%) of plant exposures occurred in children 3 years old and under. There was no difference between the sexes in exposures or symptoms.