Deficient insulin-like growth factor I in chronic heart failure predicts altered body composition, anabolic deficiency, cytokine and neurohormonal activation

BACKGROUND: Recent studies of growth hormone supplementation in chronic heart failure have been associated with variable results. Acquired abnormalities of biochemical parameters of the growth hormone insulin-like growth factor I axis have been associated with severe chronic heart failure. There are suggestions of an acquired growth hormone resistance with deficient insulin-like growth factor I in some patients. OBJECTIVES: Therefore, we set out to investigate the clinical and functional status and the degree of cytokine and neurohormonal alteration of chronic heart failure patients with deficient insulin-like growth factor I responses. METHODS: Patients with chronic heart failure were divided into two groups according to their insulin-like growth factor I levels (classified according to the manufacturer's assay range in normal controls): low insulin-like growth factor I <104 (n = 20; 89 +/- 9.6 ng/ml), and normal/high >104 ng/ml (n = 32; 169 +/- 52 ng/ml). Between groups there was no difference in age (low versus high: 65.3 +/- 12.1 versus 61.6 +/- 9.1 years, p = 0.21), body mass index, aerobic capacity (peak oxygen consumption: low versus high: 15.5 +/- 5.2 versus 17.3 +/- 6.3 mL/kg/min, p = 0.23), left ventricular ejection fraction, New York Heart Association classification. RESULTS: During quadriceps strength testing, patients with low insulin-like growth factor I had reduced absolute strength (-24%), and strength per unit area muscle (- 14%) than patients with normal/high insulin-like growth factor I. Leg muscle cross-sectional area was lower in the low insulin-like growth factor I group (-12% and -13% for right and left legs, respectively). These alterations were accompanied by increased levels of growth hormone (+145%), tumor necrosis factor-alpha (+46%), cortisol/ dehydroepiandrosterone ratio (+60%), noradrenaline (+49%) and adrenaline (+136%) (all at least p < 0.05). CONCLUSIONS: Patients with low insulin-like growth factor I levels show signs of altered body composition, cytokine and neuroendocrine activation, to a greater extent than patients with normal/high levels.     

Thrombin induced inhibition of neurite outgrowth from dorsal root ganglion neurons

Adrenalectomy (ADX) is known to block the acquisition of intravenous cocaine self-administration. A previous study therefore examined whether ADX decreases sensitivity of the 'brain reward system' in general, or its response to cocaine in particular, by measuring thresholds for intracranial self-stimulation with and without concurrent cocaine administration. ADX had no effect on thresholds for lateral hypothalamic self-stimulation (LHSS) and did not alter the cocaine dose-response curve for lowering the LHSS threshold. This result suggested that ADX does not affect sensitivity of the brain reward system. However, medial prefrontal cortex (MPFC) appears to be an important site in the mediation of cocaine reinforcing effects, and MPFC self-stimulation (MPFCSS) is mediated by a neural substrate that is largely independent of that which mediates LHSS. The present study therefore assessed whether ADX diminishes cocaine facilitation of MPFCSS. It was found that the threshold-lowering effect of cocaine (5.0, 10.0 and 20.0 mg/kg, i.p. ) did not differ between ADX rats maintained on 0.7% saline, ADX rats maintained on corticosterone (50 microg/ml) in 0.7% saline, and sham-operated controls. However, there was a trend toward desensitization of MPFCSS, itself, following ADX in the group that did not receive corticosterone supplementation. Based on this observation, and the similar responses of MPFCSS and cocaine self-administration to noncontingent priming stimulation, stress, and NMDA receptor antagonism, it is speculated that acquisition of MPFCSS and cocaine self-administration may be dependent upon a common sensitization process that is regulated by corticosterone.     

Impacts of global environmental change on future health and health care in tropical countries

The most common strategy in the development of HIV-1 protease inhibitors has been the design of high affinity transition state analogs that effectively compete with natural substrates for the active site. A second approach has been the development of compounds that inactivate the protease by destabilizing its quaternary or tertiary structure. A successful optimization of these strategies requires an accurate knowledge of the energetics of structural stabilization and binding, and the identification of those regions in the protease molecule that are critical to stability and function. Here the energetics of stabilization of the HIV-1 protease has been measured for the first time by high sensitivity differential scanning calorimetry. These studies have permitted the evaluation of the different components of the Gibbs energy of stabilization (the enthalpy, entropy and heat capacity changes). The stability of the protease is pH-dependent and due to its dimeric nature is also concentration-dependent. At pH 3.4 the Gibbs energy of stabilization is close to 10 kcal/mol at 25 degreesC, consistent with a dissociation constant of 5x10(-8) M. The stability of the protease increases at higher pH values. At pH 5, the Gibbs energy of stabilization is 14.5 kcal/mol at 25 degreesC, consistent with a dissociation constant of 2.3x10(-11) M. The pH dependence of the Gibbs energy of stabilization indicates that between pH 3.4 and pH 5 an average of 3-4 ionizable groups per dimer become protonated upon unfolding. A structure-based thermodynamic analysis of the protease molecule indicates that most of the Gibbs energy of stabilization is provided by the dimerization interface and that the isolated subunits are intrinsically unstable. The Gibbs energy, however, is not uniformly distributed along the dimerization interface. The dimer interface is characterized by the presence of clusters of residues (hot spots) that contribute significantly and other regions that contribute very little to subunit association. At the dimerization interface, residues located at the carboxy and amino termini contribute close to 75% of the total Gibbs energy (Cys95, Thr96, Leu97, Asn98 and Phe99 and Pro1, Ile3, Leu5). Residues Thr26, Gly27 and Asp29 located at the base of the active site are also important, and to a lesser extent Gly49, Ile50, Gly51 located at the tip of the flap region. The structure-based thermodynamic analysis also predicts the existence of regions of the protease with only marginal stability and a high propensity to undergo independent local unfolding. In particular, the flap region occupies a very shallow energy minimum and its conformation can easily be affected by relatively small perturbations. This property of the protease can be related to the ability of some mutations to elicit resistance towards certain inhibitors.     

Paradoxic decreases in atherosclerotic plaque mass in insulin-treated diabetic patients

This study assessed the impact of diabetes mellitus on atherosclerotic lesion formation. Seventy insulin-treated diabetics, 150 non-insulin-treated diabetics, and 607 nondiabetics with chronic anginal syndromes and de novo native coronary stenoses were studied using (1) angiography, and (2) intravascular ultrasound (reference and lesion arterial, lumen, and plaque areas; area stenosis [reference-lesion/reference lumen area]; remodeling index [reference-lesion lumen area/lesion-reference plaque area]; and slope of the regression line relating lumen area to plaque burden [plaque/arterial area]). Despite being diabetic for longer and having similar lumen compromise, insulin-treated patients had (1) less reference plaque (8.3 +/- 3.4 vs 10.5 +/- 4.5 mm2, p = 0.0015), (2) less stenosis plaque (13.0 +/- 4.9 vs 16.9 mm2, p <0.0001), (3) smaller reference arterial areas (17.1 +/- 5.4 vs 19.7 +/- 6.2 mm2, p = 0.0063), and (4) smaller stenosis arterial areas (15.3 +/- 4.9 vs 19.5 +/- 6.5 mm2, p <0.0001) than non-insulin-treated diabetics. With use of multivariate linear regression analysis, insulin use was an independent (and negative) predictor of reference plaque and arterial areas (p = 0.0308 and p = 0.0179) and stenosis plaque and arterial areas (p = 0.0117 and p = 0.0066). This was also true when normalized for body surface area. The remodeling index showed that insulin treatment resulted in an exaggerated impact of plaque accumulation on lumen compromise. This was confirmed by the slope of the regression line relating lumen area to plaque burden. Patients with a longer duration of diabetes who were treated with insulin for > or = 1 year had (paradoxically) less reference segment and stenosis plaque accumulation. Possible explanations include impaired adaptive remodeling and/or arterial (and plaque) shrinkage.     

Thiopurine methyltransferase genotype predicts therapy-limiting severe toxicity from azathioprine

BACKGROUND: Substantial hematologic toxicity limits the use of azathioprine. OBJECTIVE: To evaluate 1) polymorphic inactivation of azathioprine by thiopurine methyltransferase and 2) clinical toxicity. DESIGN: Prospective cohort study. SETTING: Two rheumatology units. PATIENTS: 67 patients for whom azathioprine was prescribed as second-line therapy for rheumatic disease. MEASUREMENTS: Polymerase chain reaction-based assays were used to detect mutations in thiopurine methyltransferase. The primary end point was discontinuation of azathioprine therapy because of toxicity. RESULTS: Six of 67 patients (9%) were heterozygous for mutant thiopurine methyltransferase alleles. Five of the 6 patients discontinued therapy within 1 month of starting treatment because of low leukocyte counts. The sixth patient did not adhere to treatment. Patients with wild-type thiopurine methyltransferase alleles received therapy longer than did patients with mutant alleles (median duration of therapy, 39 weeks [range, 6 to 180 weeks] and 2 weeks [range, 2 to 4 weeks], respectively; P = 0.018). CONCLUSION: Analysis of thiopurine methyltransferase genotype is a quick way to identify patients at risk for acute toxicity from azathioprine.     

Modulation of whole body protein metabolism, during and after exercise, by variation of dietary protein

The aim of this study was to investigate dietary protein-induced changes in whole body leucine turnover and oxidation and in skeletal muscle branched chain 2-oxo acid dehydrogenase (BCOADH) activity, at rest and during exercise. Postabsorptive subjects received a primed constant infusion of L-[1-13C,15N]leucine for 6 h, after previous consumption of a high- (HP; 1.8 g . kg-1 . day-1, n = 8) or a low-protein diet (LP; 0.7 g . kg-1 . day-1, n = 8) for 7 days. The subjects were studied at rest for 2 h, during 2-h exercise at 60% maximum oxygen consumption, then again for 2 h at rest. Exercise induced a doubling of both leucine oxidation from 20 micromol . kg-1 . h-1 and BCOADH percent activation from 7% in all subjects. Leucine oxidation was greater before (+46%) and during (+40%, P < 0.05) the first hour of exercise in subjects consuming the HP rather than the LP diet, but there was no additional change in muscle BCOADH activity. The results suggest that leucine oxidation was increased by previous ingestion of an HP diet, attributable to an increase in leucine availability rather than to a stimulation of the skeletal muscle BCOADH activity.     

A carboxyl-terminal Cys2/His2-type zinc-finger motif in DNA primase influences DNA content in Synechococcus PCC 7942

The DNA primase gene, dnaG, has been isolated from the cyanobacterium Synechococcus PCC 7942. It is not part of a macromolecular synthesis operon but is co-transcribed with pheT and located adjacent to the metallothionein divergon, smt. At the carboxyl terminus of this DnaG is a Cys2/His2 zinc-finger motif. The carboxyl-terminal 91 residues bound 65Zn and 0.95 g atom of Zn2+ mol-1 were detected with 4-(2-pyridylazo)resorcinol. Following exposure to Cd2+, 0.95 g atom of Cd2+ was displaced by 2 equivalents of p-(hydroxymercuri) phenylsulfonate mol-1, while only 0.03 g atom of Cd2+ was displaced mol-1 polypeptide missing the carboxyl-terminal (residue 592 onward) zinc-finger motif. Zn2+ caused an increase in intensity, and a reduction in wavelength, of Trp fluorescence at the tip of the predicted zinc-finger, while EDTA caused the converse. Cells containing a single chromosomal codon substitution (C597S), altering the zinc-finger, were generated by exploiting Zn2+-sensitive smt mutants and the proximity of dnaG to smt. Cells in which smt and dnaG(C597S) had integrated into the chromosome were selected via restored Zn2+ tolerance. Synechococcus PCC 7942 and its dnaG(C597S) mutant grew at equivalent rates, but the latter had a reduced number of chromosomes.     

Effects of short-term treatment of hyperlipidemia on coronary vasodilator function and myocardial perfusion in regions having substantial impairment of baseline dilator reverse

BACKGROUND: We tested the hypothesis that correction of hyperlipidemia improves coronary vasodilator response and maximal perfusion in myocardial regions having substantial impairment of pretreatment vasodilator capacity. METHODS AND RESULTS: Measurements of myocardial blood flow were made with PET [13N]ammonia in 12 patients with ischemic heart disease (11 men; age, 65+/-8 years [mean+/-SD]) at rest and during adenosine at 70 and then 140 microg . kg-1 . min-1 for 5 minutes each before and approximately 4 months after simvastatin treatment (40 mg daily). Simvastatin reduced LDL (171+/-13 before versus 99+/-18 mg/dL after simvastatin, P<0.001) and increased HDL (39+/-8 versus 45+/-9 mg/dL, P<0.05). Myocardial segments were classified on the basis of pretreatment blood flow response to 140 microg . kg-1 . min-1 adenosine as normal (flow >/=2 mL . min-1 . g-1) or abnormal (flow <2 mL . min-1 . g-1). In normal segments, baseline myocardial blood flow (0.95+/-0.32) increased (P<0.001) at both low- (1.62+/-0.81) and high- (2.63+/-0.41) dose adenosine and was unchanged both at rest and with adenosine after simvastatin. In abnormal segments, myocardial blood flow at rest (0. 73+/-0.19) increased at low- (1.06+/-0.59, P<0.02) and high- (1. 29+/-0.33, P<0.01) dose adenosine. After simvastatin, myocardial blood flow increased more compared with pretreatment at both low- (1. 37+/-0.66, P<0.05 versus pretreatment) and high- (1.89+/-0.79, P<0. 01 versus pretreatment) dose adenosine. CONCLUSIONS: Short-term lipid-lowering therapy increases stenotic segment maximal myocardial blood flow by approximately 45%. The mechanism involves enhanced, flow-mediated dilation of stenotic epicardial conduit vessels and may account at least in part for the efficacy of lipid lowering in secondary prevention trials and in reducing ischemic episodes in ambulatory patients.     

Patient-reported short-term and long-term physical and psychologic symptoms: results of the continuous hyperfractionated accelerated [correction of acclerated] radiotherapy (CHART) randomized trial in non-small-cell lung cancer. CHART Steering Committee

PURPOSE: The randomized multicenter trial of continuous hyperfractionated accelerated radiotherapy (CHART) versus conventional radiotherapy for patients with non-small-cell lung cancer (NSCLC) showed a significant survival benefit to CHART (29% v 20% at 2 years, P=.004). However, an assessment of the effect on physical and psychologic symptoms is vital to balance the costs and benefits of the two treatments. METHODS: A total of 356 patients in the United Kingdom completed the Rotterdam Symptom Checklist (RSCL) and the Hospital Anxiety and Depression Scale (HADS) at 10 time points. The principal aim of the analyses was to keep the methods simple, so as to allow the presentation and interpretation of the results to be as clear as possible. This was achieved by (1) considering individual symptoms rather than symptom subscales or domains, (2) assessing short-term effects (up to 3 months) and long-term effects (at 1 and 2 years) separately, and (3) for the short-term analyses, (a) splitting the data randomly into an exploratory data set and a confirmatory data set, and (b) using two different methods of analysis: a subject-specific approach, which used the area under the curve (AUC) as a summary measure, and a group-based method, which plotted the percent of patients with moderate or severe symptoms over time. RESULTS: The results indicate that apart from CHART causing transient pain on swallowing and heartburn, there was little difference between the regimens in the short or long-term. CONCLUSION: Combining the results of the patient-assessed symptom comparisons with the clinical results indicates that CHART confers a major benefit without serious morbidity.     

Anergic T cells actively suppress T cell responses via the antigen-presenting cell

We here show that anergic T cells are active mediators of T cell suppression. In co-culture experiments, we found that anergic T cells, derived from established rat T cell clones and rendered anergic via T cell presentation of the specific antigen (Ag), were active inhibitors of T cell responses. Anergic T cells inhibited not only the responses of T cells with the same Ag specificity as the anergic T cells, but were also capable of efficiently inhibiting polyclonal T cell responses directed to other epitopes. This suppression required close cell-cell contact between antigen-presenting cells (APC), anergic T cells and responder T cells, and only occurred when the epitope recognized by the anergic T cell was present. The suppression was not caused by passive competition for ligands on the APC surface, IL-2 consumption, or cytolysis, and was not mediated by soluble factors derived from anergic T cells that were stimulated with their specific Ag. When responder T cells were added 24 h after co-culturing anergic cells in the presence of Ag and APC, T cell responses were still suppressed, indicating that the suppressive effect was persistently present. However, anergic T cells were not able to suppress responder T cells that had already received a full activation signal. We propose that suppression by anergic T cells is mediated via the APC, either through modulation of the T cell-activating capacity of the APC (APC/T cell interaction), or by inhibition of T cells recognizing their ligand in close proximity on the same APC (T/T cell interaction).