Time course of histomorphological changes in adipose tissue upon acute lipoatrophy.

BACKGROUND AND AIMS: Crown-like structures (CLS) are characteristic histopathology features of inflamed adipose tissues in obese mice and humans. In previous work, we suggested that these cells derived from macrophages primarily involved in the reabsorption of dead adipocytes. Here, we used a well-characterized transgenic mouse model in which the death of adipocytes in adult mice is inducible and highly synchronized. In this "FAT ATTAC" model, apoptosis is induced through forced dimerization of a caspase-8 fusion protein. METHODS AND RESULTS: 0, 0.5, 1, 2, 3 and 10 days post induction of adipocyte cell death, we analyzed mesenteric and epididymal adipose depots by histology, immunohistochemistry and electron microscopy. Upon induction of caspase-8 dimerization, numerous adipocytes lost immunoreactivity for perilipin, a marker for live adipocytes. In the same areas, we found adipocytes with hypertrophic mitochondria and signs of organelle degeneration. Neutrophils and lymphocytes were the main inflammatory cells present in the tissue, and the macrophages were predominantly Mac-2 negative. Over the course of ablation, Mac-2 positive macrophages substituted for Mac-2 negative macrophages, followed by CLS formation. All perilipin negative, dead adipocytes were surrounded by CLS structures. The time course of histopathology was similar in both fat pads studied, but occurred at earlier stages and was more gradual in mesenteric fat. CONCLUSION: Our data demonstrate that CLS formation results as a direct consequence of adipocyte death, and that infiltrating macrophages actively uptake remnant lipids of dead adipocytes. Upon induction of adipocyte apoptosis, inflammatory cells infiltrate adipose tissue initially consisting of neutrophils followed by macrophages that are involved in CLS formation.

Effects of joint effusion on proprioception in patients with knee osteoarthritis: a single-blind, randomized controlled clinical trial.

OBJECTIVE: To assess the effects of joint effusion on proprioceptive status in patients with knee osteoarthritis (OA). DESIGN: A single-blind, randomized, controlled clinical trial in 40 female subjects aged 50 years and over with painful knee OA. All subjects were randomly assigned to either the control or experimental group. A volume of 20 mL of normal saline was injected into the knee joint cavity of subjects in the experimental group under ultrasonographic guidance. Proprioceptive acuity was assessed by active repositioning of the lower limb using an electrogoniometer to measure knee joint position sense (JPS) under both non-weight-bearing (NWB) and weight-bearing (WB) conditions twice, with a 20-min rest interval. The experimental group performed the task twice (Test 1 and Test 2) before and within 5 min after joint infusion. The control group also performed Test 1 and Test 2 without joint infusion. The outcome of interest was the absolute angular error (AAE), ignoring the direction of the error, between the randomized target angle and the patient's reproduced angle of JPS values. RESULTS: Compared with the control group, JPS was significantly compromised in the experimental group in the NWB test after joint infusion (P=0.025). However, no significant differences in the angular error were observed between Test 1 and Test 2 in the control group for the NWB or WB test or in the experimental group for the WB test after infusion (P>0.05). CONCLUSIONS: This study showed that joint effusion impairs proprioceptive function in osteoarthritic knee joints.

Family history of diabetes and the risk of subclinical atherosclerosis.

AIM: This study investigated the influence of a family history of diabetes on the risk of subclinical coronary atherosclerosis according to coronary computed tomography angiography (CCTA) in asymptomatic individuals. METHODS: A total of 6434 consecutive asymptomatic individuals with no prior history of coronary artery disease voluntarily underwent CCTA evaluation as part of a general health examination. Coronary atherosclerotic plaque and significant coronary artery stenosis (degree of stenosis ≥50%) on CCTA were assessed. Logistic regression analysis was used to determine the association between a family history of diabetes and atherosclerotic plaque or significant coronary artery stenosis according to the degree of diabetes (normal, prediabetic and diabetic). RESULTS: Mean age of study participants was 53.7±7.6 years, and 4694 (73.0%) were male. A total of 1593 (24.8%) participants had a family history of diabetes in a first-degree relative. Among the study participants, 1115 (17.3%), 3122 (48.5%) and 2197 (34.1%) were categorized as diabetic, prediabetic and normal, respectively. In diabetic participants, after stepwise adjustments for clinical and laboratory variables, a family history of diabetes was significantly associated with non-calcified plaque (P<0.05 for all), but did not appear to be associated with either calcified or mixed plaques or with significant coronary artery stenosis (P>0.05 for all). In prediabetic and normal participants, a family history of diabetes was not associated with either atherosclerotic plaque or significant coronary artery stenosis (P>0.05 for all). CONCLUSION: In asymptomatic diabetic individuals, a family history of diabetes is consistently associated with non-calcified coronary plaque after adjusting for risk factors.

Cooperativity and anti-cooperativity between ligand binding and the dimerization of ristocetin A: asymmetry of a homodimer complex and implications for signal transduction.

BACKGROUND: Recent work has indicated that dimerization is important in the mode of action of the vancomycin group of glycopeptide antibiotics. NMR studies have shown that one member of this group, ristocetin A, forms an asymmetric dimer with two physically different binding sites for cell wall peptides. Ligand binding by ristocetin A and dimerization are slightly anti-cooperative. In contrast, for the other glycopeptide antibiotics of the vancomycin group that have been examined so far, binding of cell wall peptides and dimerization are cooperative. RESULTS: Here we show that the two halves of the asymmetric homodimer formed by ristocetin A have different affinities for ligand binding. One of these sites is preferentially filled before the other, and binding to this site is cooperative with dimerization. Ligand binding to the other, less favored half of the dimer, is anti-cooperative with dimerization. CONCLUSIONS: In dimer complexes, anti-cooperativity of dimerization upon ligand binding can be a result of asymmetry, in which two binding sites have different affinities for ligands. Such a system, in which one binding site is filled preferentially, may be a mechanism by which the cooperativity between ligand binding and dimerization is fine tuned and may thus have relevance to the control of signal transduction in biological systems.

eIF3m expression influences the regulation of tumorigenesis-related genes in human colon cancer.

Abnormal regulation of gene expression is essential for tumorigenesis. Recent studies indicate that regulation of oncogene expression and neoplastic transformation are controlled by subunits of eukaryotic translation initiation factors (eIFs). Here we focused on eIF3 performing a pivotal role in protein synthesis and the differential expression of its subunits in cancer. The most uncharacterized non-core subunit eIF3m was confirmed to be highly expressed in human cancer cell lines and colon cancer patient tissues. By expression silencing with eIF3m-specific small interfering RNA (siRNA), we confirmed that eIF3m influences cell proliferation, cell cycle progression and cell death in human colon cancer cell line HCT-116. Using a ribonomics approach, we identified a subset of elF3m-influenced genes and showed that the expression of two highly represented tumorigenesis-related genes, MIF and MT2, were affected by eIF3m at the mRNA level. We also confirmed eIF3m-dependent regulation of MT2A downstream molecule CDC25A, which is necessary for cell cycle progression in HCT-116 cells. These results suggest that eIF3m mediates regulation of tumorigenesis-related genes in human colon cancer. Further investigations on tumorigenesis-related genes and their regulation by eIFs will provide clues for designing targeted therapy for cancer.

Study of the effect of nano-sized precipitates on the mechanical properties of boron-added low-carbon steels by neutron scattering techniques.

Small-angle neutron scattering (SANS) and neutron powder diffraction (ND) techniques were used to study quantitatively the effect of nano-sized precipitates and boron addition on the mechanical properties of low-carbon steels. SANS was used to evaluate nano-sized precipitates, smaller than about 600 A in diameter, and ND was used to determine the weight fraction of the cementite precipitates. Fine core-shell structured spherical precipitates with an average radius of ~50 A, such as MnS and/or CuS, surrounded by BN layers were observed in the boron-added (BA) low-carbon steels; fine spherical precipitates with an average radius of ~48 A were mainly observed in the boron-free (BF) low-carbon steels. In the BA steels, the number of boron precipitates, such as BN, Fe(3)(C,B) and MnS, surrounded by BN layers increased drastically at higher hot-rolling temperatures. The volume fraction of the fine precipitates of the BA steels was higher than that of the BF steels; this difference is related to the rapid growth of the BN layers on the MnS and CuS precipitates. Boron addition to low-carbon steels resulted in a reduction in strength and an improvement in elongation; this behaviour is related to the reduction of the solute carbon and the nitrogen contents in the ferrite matrix caused by the precipitation of BN, as well by the increase in the volume fraction of the cementites.

Neuropeptide Y promotes beta-cell replication via extracellular signal-regulated kinase activation.

AIMS/HYPOTHESIS: Previous studies have shown that neuropeptide Y (NPY) gene expression and release are increased in hyperphagic ob/ob mice and diabetic rats. Therefore, we hypothesized that orexigenic agent, NPY, has the effect on the obesity and diabetes. To elucidate the relationship, we have studied the regulatory role of NPY on islet cells. METHODS: Isolated islets were incubated with NPY or NPY Y1 receptor specific antagonist, BIBP3226. Proliferation, apoptosis, and Y1 receptor expression were identified by immunohistochemistry. We studied that ERK1/2 mediates the NPY pathway with PD98059 (MAP kinase inhibitor), wortmannin (phosphatidylinositol 3-kinase inhibitor), and BIM-1 (protein kinase C inhibitor). After NPY-treated islets were exposed to high glucose, insulin levels were detected. RESULTS: beta-Cell replication was enhanced in a dose-dependent manner, but without any changes on the other cells in islet. NPY Y1 receptors were expressed on islet and NPY induced phosphorylation of ERK1/2 rapidly and transiently. PD98059 (MAPK kinase inhibitor) and BIM-1 (protein kinase C inhibitor) inhibited activation of ERK1/2 by NPY, but wortmannin (phosphatidylinositol 3-kinase inhibitor) did not. Exposure of NPY-treated islets to high glucose showed the decreasing trend of insulin secretion. CONCLUSION/INTERPRETATION: Our data suggest that NPY promotes beta-cell replication via extracellular signal-regulated kinase activation and inhibits glucose-stimulated insulin secretion.

Induction of asymmetry into homodimers.

The self-regulation of biological signalling receptors via homodimerization is discussed in relation to the symmetry changes occurring when these receptors bind their target ligand. The idea of positive and negative cooperativity between dimerization and ligand binding, mediated by changes in the symmetry of the system as a source of signalling control is considered; an analogy made with the homodimerization of a glycopeptide antibiotic, ristocetin A, which displays negative cooperativity. Finally, the regulation of the bacterial aspartate receptor and the human growth hormone receptor is discussed as a function of ligand-induced asymmetry.

Sleep-wake behavior of shift workers using wrist actigraph.

The sleep-wake behavior and the effects of aging on the tolerance of night shift were investigated using wrist actigraph for 12 Korean male workers of a continuous full-day three-team three-shift system. The wrist actigraph data were obtained for about 21 days (1 shift cycle) for each subject. During night duty, total sleep time decreased, the number of naps and nap length during on-duty or off-duty periods increased, and the level of activity decreased with increasing age. These results suggest that the tolerance to night shift becomes weaker with increasing age.