Difference in abdominal muscularity at the umbilicus level between young and middle-aged men

This study aimed to examine how the muscularity of the abdomen at the umbilicus level differs between sedentary middle-aged and young men. Magnetic resonance imaging was applied to determine the cross-sectional areas of skeletal muscle, subcutaneous fat, and interperitoneal tissue in 43 middle-aged (40 58yrs) and 38 young (21-29 yrs) men. The cross-sectional area of the skeletal muscle was analyzed as the sum of those of the rectus abdominis, abdominal oblique, lower back, and iliopsoas skeletal muscle groups. The middle-aged men showed greater waist circumference and whole abdominal cross-sectional area than the young men. In addition, the cross-sectional areas of subcutaneous fat and interperitoneal tissue were greater in the middle-aged men than in the young men. However, the total cross-sectional area of the skeletal muscle was similar between the two groups, although its percentage to the whole abdominal cross-sectional area was higher in the young men compared to the middle-aged men. Among the four skeletal muscle groups analyzed, the percentage of the cross-sectional areas in abdominal oblique muscles to that of total skeletal muscle was higher in the middle-aged men than in the young men and that of the lower back muscles was the reverse. These results were similar even when cross-sectional area data were analyzed using a subsample (33 middle-aged and 23 young men) matched for body height and mass. Thus, the present study indicated that the total muscularity of the abdomen at the umbilicus level was similar between the middle-aged and young men, but the relative distributions of lower back and abdominal oblique muscles varied between the two generations.     

The Death Effector Domain-containing DEDD Supports S6K1 Activity via Preventing Cdk1-dependent Inhibitory Phosphorylation

Cell cycle regulation and biochemical responses upon nutrients and growth factors are the major regulatory mechanisms for cell sizing in mammals. Recently, we identified that the death effector domain-containing DEDD impedes mitotic progression by inhibiting Cdk1 (cyclin-dependent kinase 1) and thus maintains an increase of cell size during the mitotic phase. Here we found that DEDD also associates with S6 kinase 1 (S6K1), downstream of phosphatidylinositol 3-kinase, and supports its activity by preventing inhibitory phosphorylation of S6K1 brought about by Cdk1 during the mitotic phase. DEDD^-/- cells showed reduced S6K1 activity, consistently demonstrating decreased levels in activating phosphorylation at the Thr-389 site. In addition, levels of Cdk1-dependent inhibitory phosphorylation at the C terminus of S6K1 were enhanced in DEDD^-/- cells and tissues. Consequently, as in S6K1^-/- mice, the insulin mass within pancreatic islets was reduced in DEDD^-/- mice, resulting in glucose intolerance. These findings suggest a novel cell sizing mechanism achieved by DEDD through the maintenance of S6K1 activity prior to cell division. Our results also suggest that DEDD may harbor important roles in glucose homeostasis and that its deficiency might be involved in the pathogenesis of type 2 diabetes mellitus.Cell size is closely related to specialized cell function and to the specific patterning of tissues in the body. Cell sizing is regulated mainly by two mechanisms: cell cycle control and the biochemical response to nutrients and/or growth factors (1–5). During cell cycle progression, both the G₁ (which is believed to be dominant) and the G₂ periods are important for cells to increase their volume (6–9). In addition, we recently provided evidence that the mitotic period (M phase) also influences cell size, through analysis of DEDD-deficient mice (10, 11). The DEDD molecule was initially described as a member of the death effector domain (DED)²-containing protein family (12). Although the absence of DEDD did not apparently influence progression of apoptosis (10), we found that during mitosis, DEDD is associated with Cdk1-cyclin B1 and that it decreases the kinase activity of Cdk1. This response impedes the Cdk1-dependent mitotic program to shut off synthesis of ribosomal RNA (rRNA) and protein and is consequently useful in gaining sufficient cell growth prior to cell division. Depletion of DEDD consistently results in a shortened mitotic duration and an overall reduction in the amount of cellular rRNA and protein and, furthermore, in cell and body size (10, 11).Of the biochemical responses responsible for cell sizing, the signaling cascade involving phosphatydilinositol 3-kinase (PI3K) and its downstream target of rapamycin (TOR) is most crucial (13–15). In mammals, upon stimulation by growth factors, including insulin, the mammalian TOR (mTOR) cooperates with PI3K-dependent effectors to activate S6K1, thereby phosphorylating the 40 S ribosomal protein S6, and subsequently enhances translation of the 5′-terminal oligopyrimidine sequences that encode components of the translational machinery. This reaction increases the number of ribosomes and the efficacy of protein synthesis, thus critically promoting cell growth (16–18). Therefore, mice deficient for S6K1 (S6K1^-/-) had reduced cell and body size (19–23). This effect also involves S6K1 in maintenance of glucose tolerance. S6K1 significantly supports the size of insulin-producing β cells within pancreatic Langerhans islets (24, 25). Thus, in S6K1^-/- mice, the insulin mass was diminished, which resulted in ineffective secretion of insulin upon glucose administration (21, 23).The activation of S6K1 proceeds through chronological phosphorylation at various residues, toward the crucial phosphorylation of Thr-389, present within the linker domain between the catalytic domain and the carboxyl tail, to obtain maximal enzymatic activity (26). Interestingly, phosphorylation at several Ser/Thr residues within the C-terminal autoinhibitory tail appears to either activate or inhibit S6K1, depending on the cell cycle phase. Shah et al. (27) demonstrated that phosphorylation of those residues (featured by the Thr-421/Ser-424 site) during mitosis pursued by Cdk1 inactivates S6K1 to terminate protein synthesis prior to cell division (28). A recent report by Schmidt et al. (29) demonstrating that phosphorylation of Thr-421/Ser-424 is specifically increased during the G₂/M phase may also support the finding, whereas during the G₁ phase, there is consensus that the phosphorylation at the autoinhibitory domain is requisite for S6K1 activation (26), as also recently demonstrated by Hou et al. (30), where the Cdk5 phosphorylates the Ser-411 site, leading to activation of S6K1. In contrast to such inhibitory regulation of S6K1 during mitosis, however, a recent report by Boyer et al. (31) sharply demonstrated that the activity of S6K1 peaks at mitosis, suggesting that S6K1 may also have some roles during the mitotic phase. If so, how its activity is supported against the inhibitory regulation caused by Cdk1 remains an open question.Hence, the two observations above that both DEDD^-/- and S6K1^-/- situations decrease the efficacy of ribosome and protein synthesis, resulting in smaller cell and body size, and that mitotic Cdk1 has a functional interaction with both S6K1 and DEDD led us here to assess a possible role of DEDD in the context of the functional regulation of S6K1.     

Combined use of bFGF and GDF-5 enhances the healing of medial collateral ligament injury

Basic fibroblast growth factor (bFGF) and growth and differentiation factor (GDF)-5 stimulate the healing of medial collateral ligament (MCL) injury. However, the effect of isolated and combined use of bFGF/GDF-5 remains still unclear. We investigated cellular proliferation and migration responding to bFGF/GDF-5 using rabbit MCL fibroblasts. Rabbit MCL injury was treated by bFGF and/or GDF-5 with peptide hydrogels. Gene expression and deposition of collagens in healing tissues were evaluated. bFGF/GDF-5 treatment additively enhanced cell proliferation and migration. bFGF/GDF-5 hydrogels stimulated Col1a1 expression without increasing Col3a1 expression. Combined use of bFGF/GDF-5 stimulated type I collagen deposition and the reorganization of fiber alignment, and induced better morphology of fibroblasts in healing MCLs. Our study indicates that combined use of bFGF/GDF-5 might enhance MCL healing by increasing proliferation and migration of MCL fibroblasts, and by regulating collagen synthesis and connective fiber alignment.     

Combined use of bFGF and GDF-5 enhances the healing of medial collateral ligament injury

The anti-CD20 monoclonal antibody (Ab) rituximab is accepted to be an effective therapeutic Ab for malignant B-cell lymphoma; however, discovery of other cell surface antigens is required for the option of antibody medicine. Considering that many tumor-associated antigens are glycans, we have searched glycoconjugates for the candidate antigens that therapeutic Abs target. To this end, we first focused on the difference in the glycogenes expression in terms of Epstein-Barr virus (EBV) infection of a Burkitt’s lymphoma cell line, Akata. Using DNA array, flow cytometry and Western blotting, we found that Thy1 was highly expressed in EBV-positive Akata cells. Subsequently, Thy1 was found to be expressed in other B-cell lymphoma cell lines: BJAB, MutuI, and MutuIII, irrespective of EBV infection. Treatment of these cells with an anti-Thy1 monoclonal antibody inhibited proliferation more strongly than the therapeutic Ab rituximab. The B-cell lymphoma cell lines were classified based on the extent of the proliferation inhibition, which was not correlated with the expression level of Thy1. It is suggested that stable residence of receptor tyrosine kinases in lipid rafts sustains cell growth in B-cell lymphoma cells.     

A potent adjuvant monophosphoryl lipid A triggers various immune responses, but not secretion of IL-1beta or activation of caspase-1

Lipid A, the membrane anchor portion of LPS, is responsible for the endotoxin activity of LPS and induces many inflammatory responses in macrophages. Monophosphoryl lipid A (MPL), a lipid A derivative lacking a phosphate residue, induces potent immune responses with low toxicity. To elucidate the mechanism underlying the low toxicity of MPL, we examined the effects of MPL on the secretion of proinflammatory cytokines by mouse peritoneal macrophages, a murine macrophage-like cell line (RAW 264.7), and a human macrophage-like cell line (THP-1). MPL enhanced the secretion of TNF-alpha, but not that of IL-1beta, whereas Escherichia coli-type lipid A (natural source-derived and chemically synthesized lipid A) enhanced the secretion of both cytokines. Although MPL enhanced the levels of IL-1beta mRNA and IL-1beta precursor protein to levels similar to those induced by lipid A, IL-1beta precursor processing in MPL-treated cells was much lower than that in E. coli-type lipid A-treated ones. Moreover, MPL, unlike E. coli-type lipid A, failed to induce activation of caspase-1, which catalyzes IL-1beta precursor processing. These results suggest that an immune response without activation of caspase-1 or secretion of IL-1beta results in the low toxicity of this adjuvant.     

Sesquiterpenes from Artemisia princeps

Copaene, cyperene, caryophyllene, β-farnesene, α-himachalene, γ-humulene and farnesyl acetate were isolated from the root of Artemisia princeps. As a result of isomerization studies on γ-humulene, the main constituent, a preferred conformation was proposed.     

2'-Deoxy-2'-azidoadenosine triphosphate and 2'-deoxy-2'-fluoroadenosine triphosphate as substrates and inhibitors for Escherichia coli DNA-dependent RNA polymerase

The effects of 2'-substitutions of ATP on the substrate and inhibitor properties for RNA synthesis were studied in the poly(dAT)-dependent reaction of Escherichia coli RNA polymerase. In the presence of UTP, 2'-deoxy-2'-azidoadenosine 5'-triphosphate (AZTP) was incorporated into an acid-insoluble fraction at one-tenth of the rate of ATP incorporation; it thus acts as a competitive inhibitor for poly(AU) synthesis. On the other hand, another ATP analog, 2'-deoxy-2'-fluoroadenosine 5'-triphosphate (AfTP), was co-polymerized with UTP into acid-insoluble materials at a rate less than 1% of that of ATP incorporation; in addition, it exerted a strong but mixed-type inhibition on poly(AU) synthesis. Different modes of action of the two ATP analogs are discussed in connection with the specificity of substrate recognition by RNA polymerase.     

Effects of uniconazole and GA3 on cold-induced stem elongation and flowering of Raphanus sativus L.

The effects of gibberellin (GA) on cold-induced stem elongation and flowering of Japanese radish (Raphanus sativus L.) were investigated using application of GA3 and a GA-biosynthesis inhibitor, uniconazole (UCZ). UCZ very strongly inhibited stem elongation and delayed flowering, and the inhibition and delay were completely reversed by GA3 application. These results suggest that GA is necessary not only in the stem elongation but also in the flowering. When cold treatment (CT) was conducted on the plants whose GA level was lowered by UCZ, GA3 applied after CT completely reversed the delay of flowering. Thus low GA level probably did not retard cold induction. Microscopic observation of apical meristem showed that UCZ delayed flowering by delaying the shift from vegetative to dome-shaped meristem. This result suggested that low GA level delayed floral evocation. Consequently it was suggested that low GA level retarded physiological process involved in long day induction or in floral evocation, resulting in delay of floral evocation.