Characterization of normal peripheral blood lymphocyte colony-forming cells: cell cycle status, surface markers, and cellular growth requirements

We performed a series of studies to further clarify the nature of lymphocyte colony-forming cells (CFC) from normal peripheral blood. Mononuclear cells were separated into E-rosette-enriched (E+) and E- rosette-depleted (E-) populations and cultured in methylcellulose with conditioned media and irradiated mononuclear cells. Linear plating relationships were obtained with plating efficiencies of 0.26% +/- .02% (mean +/- SE) for E+ CFC and 0.18% +/- .02% for E- CFC. Cells in E+ colonies were T lymphocytes and in E- colonies were B lymphocytes as determined by cell surface marker analysis. Using the thymidine suicide technique, approximately one-half of CFC were found to be in cycle at any moment, and plating efficiencies and cell cycle status of E+ CFC were not changed by preincubation with PHA in liquid culture for 48 hr. Using antibody complement-mediated cytotoxicity, E+ CFC were found to be T101+, OKT3+, and Ia-, while E- CFC were OKT3- and Ia+. Using monocyte-depleted populations obtained by sedimentation at unit gravity, lymphocyte colony growth was absent in monocyte-depleted fractions, and optimal growth occurred with 40% monocytes in culture. In contrast to some previous studies, we find that lymphocyte CFC originate from a small, cycling population of cells bearing mature T or B lymphocyte markers. Entry into cell division, however, does not confer colony-forming capacity on lymphocytes. Monocytes are critical to growth of E+ CFC, and cultures severely depleted of monocytes would not be expected to form colonies.     

Relation between aerobic fitness and brain structures in amnestic mild cognitive impairment elderly

Mild cognitive impairment (aMCI) is a clinical condition, with high risk to develop Alzheimer’s disease. Physical exercise may have positive effect on cognition and brain structure in older adults. However, it is still under research whether these influences are true on aMCI subjects with low Ab_42 and high total tau in cerebrospinal fluid (CSF), which is considered a biomarker for AD. Therefore, we aimed to investigate a possible relation between aerobic fitness (AF) and gray matter (GM) volume and AF and white matter (WM) integrity in aMCI with a CSF biomarker. Twenty-two participants with aMCI acquired the images on a 3.0-T MRI. AF was assessed by a graded exercise test on a treadmill. Voxel-based morphometry and tract-based spatial statistic methods were used to analyze the GM volume and WM microstructural integrity, respectively. We correlated AF and GM volume and WM integrity in aMCI (p < 0.05, FWE corrected, cluster with at least five voxels). There was a positive relation between AF and GM volume mostly in frontal superior cortex. In WM integrity, AF was positively correlated with fractional anisotropy and negatively correlated with mean diffusivity and radial diffusivity, all in the same tracts that interconnect frontal, temporal, parietal, and occipital areas (longitudinal fasciculus, fronto-occipital fasciculus, and corpus callosum). These results suggest that aerobic fitness may have a positive influence on protection of brain even in aMCI CSF biomarker, a high-risk population to convert to AD.     

Atrial fibrillation and venous thromboembolism: evidence of bidirectionality in the Atherosclerosis Risk in Communities Study

Essentials

• Atrial fibrillation (AF) may increase risk of venous thromboembolism (VTE), and vice versa.
• Bidirectionality was assessed prospectively via data from 15 129 black and white individuals.
• AF was associated with greater risk of developing VTE, and VTE with greater risk of AF.
• Associations were strongest among blacks and in the first 6 months after initial diagnosis.

Summary

Background

Atrial fibrillation (AF) and venous thromboembolism (VTE) frequently co‐occur. These conditions have shared risk factors and are accompanied by coagulation abnormalities. Furthermore, mechanistic pathways may directly link the disorders.

Objectives

To test the hypothesis that individuals with incident AF are at greater risk of developing VTE, and those with VTE are at elevated risk of AF. We also tested whether associations were stronger in the first 6 months after the initial diagnosis, and explored race differences.

Patients/Methods

A total of 15 129 ARIC study participants (45–64 years, 55% female, 26% Black) were followed from 1987 to 2011 for incident AF and VTE (median follow‐up 19.8 years). Multivariable‐adjusted Cox regression was used, with AF and VTE modeled as time‐dependent exposures.

Results

Incident AF was associated with greater risk of subsequent incident VTE (hazard ratio [95% CI], 1.71 [1.32–2.22]); the association was stronger in Black people (2.30 [1.48–3.58]) and during the first 6 months after AF diagnosis (5.08 [3.08–8.38]). Similarly, incident VTE was associated with increased risk of incident AF (1.73 [1.34–2.24]), especially in Black people (2.40 [1.55–3.74]) and in the first 6 months after VTE diagnosis (4.50 [2.61–7.77]).

Conclusions

The occurrence of AF was associated with increased risk of incident VTE, and occurrence of VTE was associated with greater risk of incident AF. Associations were particularly strong among Black people and during the first 6 months after the initial diagnosis, although they remained elevated even after 6 months. These findings highlight patient populations that may be at increased risk of AF and VTE, and perhaps should be targeted with preventive strategies.

     

Increases in nitrogen uptake rather than nitrogen-use efficiency support higher rates of temperate forest productivity under elevated CO2

Forest ecosystems are important sinks for rising concentrations of atmospheric CO(2). In previous research, we showed that net primary production (NPP) increased by 23 +/- 2% when four experimental forests were grown under atmospheric concentrations of CO(2) predicted for the latter half of this century. Because nitrogen (N) availability commonly limits forest productivity, some combination of increased N uptake from the soil and more efficient use of the N already assimilated by trees is necessary to sustain the high rates of forest NPP under free-air CO(2) enrichment (FACE). In this study, experimental evidence demonstrates that the uptake of N increased under elevated CO(2) at the Rhinelander, Duke, and Oak Ridge National Laboratory FACE sites, yet fertilization studies at the Duke and Oak Ridge National Laboratory FACE sites showed that tree growth and forest NPP were strongly limited by N availability. By contrast, nitrogen-use efficiency increased under elevated CO(2) at the POP-EUROFACE site, where fertilization studies showed that N was not limiting to tree growth. Some combination of increasing fine root production, increased rates of soil organic matter decomposition, and increased allocation of carbon (C) to mycorrhizal fungi is likely to account for greater N uptake under elevated CO(2). Regardless of the specific mechanism, this analysis shows that the larger quantities of C entering the below-ground system under elevated CO(2) result in greater N uptake, even in N-limited ecosystems. Biogeochemical models must be reformulated to allow C transfers below ground that result in additional N uptake under elevated CO(2).     

Involvement of PKCα and G-protein-coupled receptor kinase 2 in agonist-selective desensitization of μ-opioid receptors in mature brain neurons

Background and purpose:

The ability of an agonist to induce desensitization of the µ-opioid receptor (MOR) depends upon the agonist used. Furthermore, previous data suggest that the intracellular mechanisms underlying desensitization may be agonist-specific. We investigated the mechanisms underlying MOR desensitization, in adult mammalian neurons, caused by morphine (a partial agonist in this system) and DAMGO (a high-efficacy agonist).

Experimental approach:

MOR function was measured in locus coeruleus neurons, by using whole-cell patch-clamp electrophysiology, in rat and mouse brain slices (both wild-type and protein kinase C (PKC)α knockout mice). Specific isoforms of PKC were inhibited by using inhibitors of the receptors for activated C-kinase (RACK), and in vivo viral-mediated gene-transfer was used to transfect neurons with dominant negative mutants (DNMs) of specific G-protein-coupled receptor kinases (GRKs).

Key results:

Morphine-induced desensitization was attenuated by using RACK inhibitors that inhibit PKCα, but not by other isoform-specific inhibitors. Further, the PKC component of morphine-induced desensitization was absent in locus coeruleus neurons from PKCα knockout mice. The PKC-enhanced morphine-induced desensitization was not affected by over-expression of a GRK2 dominant negative mutant (GRK2 DNM). In contrast, DAMGO-induced MOR desensitization was independent of PKC activity but was reduced by over-expression of the GRK2 DNM but not by that of a GRK6 DNM.

Conclusions and implications:

In mature mammalian neurons, different MOR agonists can induce MOR desensitization by different mechanisms, morphine by a PKCα-mediated, heterologous mechanism and DAMGO by a GRK-mediated, homologous mechanism. These data represent functional selectivity at the level of receptor desensitization.     

Effect of fluvastatin on cardiac outcomes in kidney transplant patients with systemic lupus erythematosus: A randomized placebo‐controlled study

Objective

Patients with systemic lupus erythematosus (SLE), with or without end‐stage renal failure, are at increased risk of premature cardiovascular disease. Although statin therapy has been found to reduce cardiovascular risk in the general population, its effectiveness in kidney transplant recipients with SLE has not been examined. This study was undertaken to investigate the effect of fluvastatin on cardiac end points in a randomized controlled trial of renal transplant patients with SLE.

Methods

Patients with SLE were identified from among participants in the Assessment of Lescol in Renal Transplantation trial, a randomized, double‐blind, placebo‐controlled study of the effect of fluvastatin (40–80 mg/day) on cardiovascular outcomes in renal transplant recipients. Patients were randomized to either a group receiving fluvastatin or a placebo group for the duration of the 5–6‐year trial, and then invited to continue in a 2‐year open‐label extension during which all participants, regardless of original group, received fluvastatin. Patients were followed up for a total of 7–8 years for assessment of the primary end point of major cardiac events, comprising nonfatal myocardial infarction, cardiac death, and coronary intervention procedures.

Results

Fluvastatin reduced low‐density lipoprotein cholesterol levels by 29.2% (95% confidence interval [95% CI] 18.3–40%), from a mean ± SD of 4.0 ± 0.9 mmoles/liter to 2.8 ± 1.1 mmoles/liter, and total cholesterol by 19.6% (95% CI 11.7–27.5%), from 6.4 ± 0.9 mmoles/liter to 5.1 ± 1.1 mmoles/liter. Compared with placebo‐treated patients, patients randomized to receive fluvastatin exhibited a 73.4% reduction in the risk of major cardiac events (relative risk 26.6 [95% CI 5.9–119.4], P = 0.064).

Conclusion

Our results indicate that the effect of fluvastatin on cardiac events in renal transplant recipients with SLE is similar to that observed with statin therapy in the renal transplant population as a whole.

     

Differences in gut microbial metabolism are responsible for reduced hippurate synthesis in Crohn's disease

Background  

Certain urinary metabolites are the product of gut microbial or mammalian metabolism; others, such as hippurate, are mammalian-microbial 'co-metabolites'. It has previously been observed that Crohn's disease (CD) patients excrete significantly less hippurate than controls. There are two stages in the biosynthesis of this metabolite: 1) gut microbial metabolism of dietary aromatic compounds to benzoate, and 2) subsequent hepatorenal conjugation of benzoate with glycine, forming hippurate. Differences in such urinary co-metabolites may therefore reflect systemic consequences of altered gut microbial metabolism, though altered host metabolic pathways may also be involved.     

恶性黑色素瘤和非皮肤型恶性肿瘤的相关性

背景：黑色素瘤患者继发恶性肿瘤的发病率增减的报道不一：为了解恶性黑色素瘤与非皮肤型恶性肿瘤是否有关联，作者调查了印第安纳大学肿瘤中心的数据库。目的：作者搜寻黑色素瘤患者发生非皮肤型恶性肿瘤的证据。方法：分析1987年1月至2001年3月间病检确诊的恶性黑色素瘤患者。在这些患者中调查被诊断为黑色素瘤前后发生非皮肤型恶性肿瘤的数据。用实际继发恶性肿瘤人数和预期继发恶性肿瘤的比率作标准化发病率（SIR）的计算，从累积泊松分布估计SIR的95％CI。结果：14年间共955例黑色素瘤患者（其中男498例，女457例）记录在案。59例（6．2％）黑色素瘤患者（男39例，女20例）证实有69个非皮肤型恶性肿瘤。在男性，非霍奇金淋巴瘤（SIR=1．91，95％C10．88～3．62）和肾细胞癌（SIR=2．41，95％C10．97～4．97）有较高的危险度。但在女性患者中，未见非皮肤型恶性肿瘤的较高危险度。结论：本研究未显示黑色素瘤患者有发生前列腺癌、胃肠癌、白血病、子宫内膜癌或神经和神经内分泌系统肿瘤的较高危险度。女性患者无发生非皮肤型肿瘤的较高危险度。