Prediction of long-term mortality in patients with rheumatoid arthritis according to simple questionnaire and joint count measures

This study examined changes in employment status and quality of work in 109 chronic pain patients who underwent a cognitive-behavioural pain management course; 68% of patients were female, mean age was 45 years, mean pain chronicity 10.7 years, 70% had spinal pain, and mean impairment on the Sickness Impact Profile was 26%. Twenty-six per cent of patients were employed at pre-treatment; the remaining 74% had been unemployed for 4.3 years on average. Measures of work status and quality, mood, pain, self-efficacy and walking performance were taken before admission, and at 1-, 6-, and 12-month follow-ups. Among employed patients quality of work scores improved by 35% from pre- to post-treatment (p < 0.01). Thirty per cent of previously unemployed patients returned to work during the 1-year follow-up, although employment status fluctuated greatly during this period. Non-workers were generally more impaired than workers on most measures, but the same measures did not differentiate between those who successfully returned to work and those who remained unemployed.     

A study of subunit interface residues of fructose-1,6-bisphosphatase by site-directed mutagenesis: effects on AMP and Mg2+ affinities

The structural transformation of fructose-1,6-bisphosphatase upon binding of the allosteric regulator AMP dramatically changes the interactions across the C1-C4 (C2-C3) subunit interface of the enzyme. Asn9, Met18, and Ser87 residues were modified by site-directed mutagenesis to probe the function of the interface residues in porcine liver fructose-1,6-bisphosphatase. The wild-type and mutant forms of the enzyme were purified to homogeneity and characterized by initial rate kinetics and circular dichroism (CD) spectrometry. No discernible alterations in structure were observed among the wild-type and Asn9Asp, Met18Ile, Met18Arg, and Ser87Ala mutant forms of the enzyme as measured by CD spectrometry. Kinetic analyses revealed 1.6- and 1.8-fold increases in kcat with Met18Arg and Asn9Asp, respectively. The K(m) for fructose 1,6-bisphosphate increased about 2-approximately 4-fold relative to that of the wild-type enzyme in the four mutants. A 50-fold lower Ka value for Mg2+ compared with that of the wild-type enzyme was obtained for Met18Ile with no alteration of the Ki for AMP. However, the replacement of Met18 with Arg caused a dramatic decrease in AMP affinity (20 000-fold) without a change in Mg2+ affinity. Increases of 6- and 2-fold in the Ki values for AMP were found with Asn9Asp and Ser87Ala, respectively. There was no difference in the cooperativity for AMP inhibition between the wild-type and the mutant forms of fructose-1,6-bisphosphatase. This study demonstrates that the mutation of residues in the C1-C4 (C2-C3) interface of fructose-1,6-bisphosphatase can significantly affect the affinity for Mg2+, which is presumably bound 30 A away. Moreover the mutations alternatively reduce AMP and Mg2+ affinities, and this finding may be associated with the destabilization of the corresponding allosteric states of the enzyme. The kinetics and structural modeling studies of the interface residues provide new insights into the conformational equilibrium of fructose-1,6-bisphosphatase.     

Changes in densities of hypothalamic mu opioid receptor during cupric acete-induced preovulatory lh surge in rabbit

Decrease in activity of hypothalamic beta-endorphin (beta-EP) is an important factor for inducing the preovulatory LH surge. To study whether hypothalamic mu opioid receptor is involved in this process, changes in densities of hypothalamic mu opioid receptors were observed in this study by autoradiography and image process during cupric acetate (CuAC)-induced preovulatory LH surge in rabbits. New Zealand female rabbits were injected 1% CuAC 0.9 ml or saline 0.9 ml and sacrificed at different times after the injection. The densities of mu opioid receptor in the medial basal hypothalamus (MBH) and the medial preoptic area (MPO) were measured. A transient increase in densities of MPO mu opioid receptor were observed 1 h after CuAC injection (P < 0.05). The densities of MPO mu opioid receptor decreased significantly before the onset of the LH surge (P < 0.05) and remained at a low level during the surge. The change in densities of mu opioid receptor in the MBH was similar to those in the MPO. No change was observed in the saline control group. There was a negative correlation between the changes in densities of MBH mu opioid receptor and serum LH levels in the process of LH surge. The results suggest that the decrease of hypothalamic mu opioid receptor may be involved in the preovulatory LH surge.