Changes in protein turnover, IGF-I and IGF binding proteins in children with cancer

Changes in insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding proteins (IGFBPs) were correlated with protein synthesis and breakdown using [1- ¹³C]leucine before chemotherapy and during subsequent febrile neutropenia (FN) in eight children with cancer, aged 6.3–17.5 y. IGF-I levels were similar to age-matched controls before chemotherapy (mean ±SEM: 250 ±28 and 228 ±22 μg l^-1, respectively). During FN, IGF-I fell to 156 ±22 /ng l ^-1(p= 0:02), and rose to 276 ±27 μ g l ^-1 with recovery at 6 months (p = 0:004). Similarly, IGFBP-3 decreased from 4.0 ±0.2mgl^-1 before chemotherapy to 3.0 ±0.3 mgl^-1 during FN (p= 0:01), and returned to 4.1 ±0.2mgl ^-1 at 6 months (p= 0:01). IGF-I correlated with IGFBP-3 (r=+0:7, p <0:001). Scanning densitometry showed a decrease in IGFBP-3 from 94 to 54% during FN, when the presence of IGFBP-3 protease activity was observed. Compared with normal human serum, IGFBP-2 was elevated throughout the study. IGFBP-1 increased from 14.6 ±3.5 to 30.6 ±2.8/ngl^-1 (p = 0:004), whereas serum insulin decreased from 26.5 ±6.8 to 7.8 ±0.8 mUl^-1 (p= 0:03) before and during FN, respectively. Whilst IGF-I and IGFBP-3 fell, daytime growth hormone increased from 3.3 ±0.6 to 6.7±0.8mUl ^-1 (p= 0:01), and cortisol from 197 ±48 to 594±98nmoll ^-1 (p = 0:005). Albumin decreased from 47 ±2 to 38 ±2gl^-1 (p= 0:004) and improved to 47 ±2gl^-1 with recovery (p= 0:003). Protein synthesis increased from 4.5 ±0.4 to 5.0 ±0.6gkg^-1 d^-1 before chemotherapy and during FN, while protein breakdown rose from 5.4 ±0.4 to 6.3 ±0.4kg^-1d^-1. Increasing protein breakdown was related to falling IGF-I and IGFBP-3 levels. Modification of IGFBP-3 by circulating proteolytic activity may alter IGF bioavailability, allowing protein synthesis to increase during periods of severe catabolic stress.     

Pretibial myxoedema associated with Hashimoto''s thyroiditis

Pretibial myxoedema is a cutaneous mucinosis typically associated with Graves' disease, although it may also develop in subjects with non-thyrotoxic thyroid pathologies. This report presents a rare case of pretibial myxoedema occurring in a 58-year-old woman with biopsy-proven Hashimoto's thyroiditis. The hypothetical pathogenetic link between the two disorders is discussed with particular attention to the role of thyroid stimulating hormone receptor antibodies.     

Inhibition of tissue factor/factor VIIa activity in plasma requires factor X and an additional plasma component

A study was carried out to explore requirements for the inhibition of tissue factor-factor VIIa enzymatic activity in plasma. Reaction mixtures contained plasma, 3H-factor IX or 3H-factor X, tissue factor (vol/vol 2.4% to 24%), and calcium. Tissue factor-factor VIIa activity was evaluated from progress curves of activation of factor IX or factor X, plotted from tritiated activation peptide release data. With normal plasma, progress curves exhibited initial limited activation followed by a plateau indicative of loss of tissue factor-factor VIIa activity. With hereditary factor X-deficient plasma treated with factor X antibodies, progress curves revealed full factor IX activation. Adding only 0.4 micrograms/mL factor X (final concentration) could restore inhibition. Inhibition was not observed in purified systems containing 6% to 24% tissue factor, factor VII, 0.5 micrograms/mL, factor IX, 13 micrograms/mL, and factor X up to 0.8 micrograms/mL, but could be induced by adding barium-absorbed plasma to the reaction mixture. Thus, both factor X and an additional material in plasma were required for inhibition. The amount of factor X needed appeared related to the concentration of tissue factor; adding more tissue factor at the plateau of a progress curve induced further activation. These results also indicate that inhibited reaction mixtures contained active free factor VII(a). Preliminary data suggest that inhibition may stem from loss of activity of the tissue factor component of the tissue factor- factor VII(a) complex.     

Event-Related Brain Potentials Reflecting Processing of Relevant and Irrelevant Stimuli During Selective Listening

Event-related brain potentials were recorded from the human scalp during selective listening to tone pips differing in location and/or pitch from irrelevant tones. The subjects' task was to discriminate infrequent deviant tones of lower intensity appearing among designated (relevant) tones. A large processing negativity was observed in the event-related potentials to relevant tones differing from the irrelevant tones in location even when both tones randomly varied in pitch. Similarly, a large processing negativity was elicited by the relevant tones differing from the irrelevant tones in pitch even when the location of both tones varied randomly. The results support the theory that the processing negativity to relevant stimuli reflects a match of these stimuli with an “attentional trace,' an actively maintained neuronal representation of the physical feature(s) of relevant stimuli that distinguish these stimuli from the irrelevant stimuli. Furthermore, the infrequent lower-intensity tones appearing among irrelevant tones elicited a mismatch negativity similar to the mismatch negativity elicited by target tones, equivalent lower-intensity tones appearing among relevant tones. This indicates that these infrequent stimulus changes were automatically discriminated by the generator mechanism associated with mismatch negativity.