Biomedical subjects
Publications and source records attributed to B Yu.
Nine glycosides bearing the disaccharide of OSW-1, namely 2-O-(4-methoxybenzoyl)-beta-D-xylopyranosyl-(1-->3)-2-O-acetyl-alpha-L-arabinopyranosides, were synthesized, and their antitumor activities were tested.
Five analogues, including a 16-epi-isomer (6), and a 3-terephthalic acid linked dimer (8) of OSW-1 were synthesized. Their inhibitory activities on P388 and A-549 cells were detected.
Recent studies have indicated that the development of cyclin-dependent kinase (cdk)2 inhibitors that deregulate E2F are a plausible pharmacological strategy for novel antineoplastic agents. We show here that 3-[1-(3H-Imidazol-4-yl)-meth-(Z)-ylidene]-5-methoxy-1,3-dihydro-indol-2-one (SU9516), a novel 3-substituted indolinone compound, binds to and selectively inhibits the activity of cdk2. This inhibition results in a time-dependent decrease (4-64%) in the phosphorylation of the retinoblastoma protein pRb, an increase in caspase-3 activation (5-84%), and alterations in cell cycle resulting in either a G(0)-G(1) or a G(2)-M block. We also report here cell line differences in the cdk-dependent phosphorylation of pRb. These findings demonstrate that SU9516 is a selective cdk2 inhibitor and support the theory that compounds that inhibit cdk2 are viable resources in the development of new antineoplastic agents.
1,2-Migration and concurrent glycosidation of ethyl(phenyl) 2,3-orthoester-1-thio-alpha-D- and L-mannopyranosides under the action of TMSOTf readily afforded the corresponding 2-S-ethyl(phenyl)-2-thio-beta-glucopyranosides, ready precursors to 2-deoxy-arabino-hexopyranosides (2-deoxy-beta-glucopyranosides).
In this work, sorption of lead on sawdust (SD) has been studied by using batch techniques. Similar to the sorption of copper, the equilibrium sorption levels for lead is a function of the solution pH, contact time, sorbent and sorbate concentration. The equilibrium adsorption capacity of sawdust for lead was measured and extrapolated using linear Freundlich and Langmuir isotherms and compared with that for copper. Metal ions which are bounded to the sawdust could be stripped by acidic solution so that the sawdust can be recycled. Non-equilibrium experiments were done by using glass columns. The results indicate the potentially practical value of this method in industries and also provide strong evidence to support the adsorption mechanism proposed. Even though the focus of this work is on lead, some results from previous study for copper have been incorporated here for sake of comparison.
Trimolecular interactions between the T cell antigen receptor and MHC/peptide complexes, together with costimulatory molecules and cytokines, control the initial activation of naive T cells and determine whether the helper precursor cell differentiates into either T helper (TH)1 or TH2 effector cells. We now present evidence that regulatory CD8(+) T cells provide another level of control of TH phenotype during further evolution of immune responses. These regulatory CD8(+) T cells are induced by antigen-triggered CD4(+) TH1 cells during T cell vaccination and, in vitro, distinguish mature TH1 from TH2 cells in a T cell antigen receptor Vbeta-specific and Qa-1-restricted manner. In vivo, protection from experimental autoimmune encephalomyelitis (EAE) induced by T cell vaccination depends on CD8(+) T cells, and myelin basic protein-reactive TH1 Vbeta8(+) clones, but not TH2 Vbeta8(+) clones, used as vaccine T cells, protect animals from subsequent induction of EAE. Moreover, in vivo depletion of CD8(+) T cells during the first episode of EAE results in skewing of the TH phenotype toward TH1 upon secondary myelin basic protein stimulation. These data provide evidence that CD8(+) T cells control autoimmune responses, in part, by regulating the TH phenotype of self-reactive CD4(+) T cells.
Polyphyllin D, namely diosgenyl alpha-L-rhamnopyranosyl-(1 --> 2)- [(alpha-L-arabinofuranosyl)-(1 --> 4)]-[beta-D-glucopyranoside, was synthesized from diosgenyl-beta-D-glucopyranoside in four steps and in 30% overall yield, taking advantage of regioselective pivaloylation and alpha-L-rhamnopyranosylation reactions.
Aromatase (estrogen synthetase) is expressed in breast cancer tissue, and in situ expression of the enzyme stimulates breast cancer growth. Promoter I.3 is one of the major promoters that control the expression of aromatase in breast cancer tissue. Using the yeast one-hybrid approach to screen a human breast tissue hybrid cDNA expression library, we found that the zinc-finger transcriptional factor Snail (SnaH) interacted with a regulatory region near promoter I.3 of the human aromatase gene. DNA mobility shift assays and mutation analyses using recombinant SnaH protein expressed in Escherichia coli have revealed that this protein interacts with a segment, 5'-CTGATGAAGT-3', which is between 66 and 76 bp upstream from the transcriptional start site of promoter I.3. Using mammalian cell transfection experiments, SnaH was found to act as a repressor of promoter I.3 activity. Site-directed mutagenesis experiments have revealed that the NH2-terminal SNAG domain is important for the repressor activity of SnaH. To demonstrate the inhibitory activity against aromatase expression, a stable SnaH-expressing MDA-MB-231 breast cancer cell line was generated, and the aromatase RNA messages in the SnaH-transfected cell line were found to be 30% of those in the vector-transfected cell line. Reverse transcription-PCR analysis on RNAs isolated from 12 cell lines has confirmed that SnaH is expressed at a higher level in normal breast epithelial cell and stromal fibroblast cell lines than in breast cancer cell lines. In addition, SnaH mRNA was detected in only 16 of 55 breast cancer specimens. On the other hand, aromatase mRNA was detected in 54 of the 55 specimens. Our results indicate that SnaH acts as a repressor that down-regulates the expression of aromatase in normal breast tissue by suppressing the function of promoter I.3. A reduction of the expression of SnaH in breast cancer tissue further suggests a cancer-protective role for this protein in normal breast tissue.
[figure: see text] 1,2-Migration and concurrent glycosidation of phenyl 2,3-O-thionocarbonyl-1-thlo-alpha-L-rhamnopyranosides under the action of methyl trifluoromethanesulfonate (MeOTf) afforded in high yields the 3-O-(methylthio)carbonyl-2-S-phenyl-2,6-dideoxy-beta-L-glucopyranosides, ready precursors to the corresponding 2-deoxy-beta-glycosides.
Although the functional roles of interleukin (IL-)13 in haematopoietic cells are well investigated, those in non-haematopoietic cells remain to be addressed. IL-13 exerts its actions by binding to the IL-13 receptor (IL-13R) on target cells, which is composed of IL-13Ralpha1 and the IL-4 receptor alpha chain (IL-4Ralpha). However, there has been no study of localization of IL-13R in each tissue. To address this question, we generated monoclonal anti-IL-13Ralpha1 antibody, and performed immunohistochemistry using this antibody and anti-IL-4Ralpha antibody. Distribution of these two components was the same in all examined tissues. Staining was positive in keratinocytes, hair follicles, and sebaceous and sweat glands in skin; in ciliated respiratory epithelial cells in nasal tissue; in heart muscle cells; in foveola cells, gastric glands, and the smooth muscle layer in stomach; and in hepatocytes in liver. However, staining was undetectable in brain and bone marrow. Fibroblasts and endothelial cells were stained in some tissues. These results provide clues to elucidate the known pathological roles of IL-13 in atopic dermatitis and allergic rhinitis, as well as its unknown physiological roles.
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BACKGROUND: Women have higher non-contact anterior cruciate ligament injury rate than men do in sport activities. Non-contact anterior cruciate ligament injuries frequently occur in sports requiring cutting tasks. Alternated motor control strategies have identified as a potential risk factor for the non-contact anterior cruciate ligament injuries. The purpose of this study was to compare the patterns of knee kinematics and electromyographic activities in running, side-cutting, and cross-cutting between men and women recreational athletes. METHODS: Three-dimensional kinematic data of the knee and electromyographic data of selected muscles across the knee joint were collected for 11 men and 9 women recreational athletes in running, side-cutting, and cross-cutting. Regression analyses with dummy variables for comparison of knee motion patterns between men and women. RESULTS: Women tend to have less knee flexion angles, more knee valgus angles, greater quadriceps activation, and lower hamstring activation in comparison to men during the stance phase of each of the three athletic tasks. Literatures suggest these alternated knee motion patterns of women tend to increase the load on the anterior cruciate ligament. CONCLUSION: Women on average may have certain motor control strategies that may alter their knee motion patterns. Women's altered knee motion patterns may tend to increase the load on the anterior cruciate ligament in the selected athletic tasks, which may contribute to the increased anterior cruciate ligament injury rate among women. RELEVANCE: Non-contact anterior cruciate ligament injuries frequently occur in sports. Altered motor control strategies and lower extremity motion patterns are likely to play an important role in non-contact anterior cruciate ligament injuries. Non-contact anterior cruciate ligament injuries may be prevented by correcting altered motor control strategies and associated lower extremity motion patterns through certain training programs.
In a novel application of two-photon scanning fluorescence microscopy, three-dimensional spatial distributions of the hydrophilic and hydrophobic fluorescent probes, sulforhodamine B and rhodamine B hexyl ester, in excised full-thickness human cadaver skin were visualized and quantified. Both sulforhodamine B and rhodamine B hexyl ester were observed to lie primarily in the lipid multilamellae region surrounding the corneocytes within the stratum corneum. From the two-photon scanning fluorescence microscopy scans, the changes in the concentration gradient and the vehicle to skin partition coefficient of each probe induced by the oleic acid enhancer action were calculated relative to the control sample (not exposed to oleic acid), and subsequently applied to theoretically derived mathematical expressions of transdermal transport to quantitatively characterize the oleic acid-induced relative changes in the skin diffusion coefficient and the skin barrier diffusion length of the permeant. For the hydrophobic probe rhodamine B hexyl ester, the permeability enhancement was primarily driven by an increase in the vehicle to skin partition coefficient, leading to an increase in the steepness of the concentration gradient across the skin. The primary oleic acid-induced changes in the transport properties of the hydrophilic probe sulforhodamine B included increases in the vehicle to skin partition coefficient and the skin diffusion coefficient. These findings utilizing the two-photon scanning fluorescence microscopy methodology and data analysis described here demonstrate that, in addition to providing three-dimensional images that clearly delineate probe distributions in the direction of increasing skin depth, the subsequent quantification of these images provides additional important insight into the mechanistic changes in transdermal transport underlying the visualized changes in probe distributions across the skin.
OBJECTIVE: To determine whether a lumbar support improves trunk repositioning error (RE), an aspect of proprioception. DESIGN: RE was measured with and without a lumbar support. SETTING: Outpatient clinic. PARTICIPANTS: Twenty subjects with chronic low back pain (LBP) and 20 control subjects. INTERVENTIONS: Subjects wore the lumbar support for 2 hours and then testing was repeated. MAIN OUTCOME MEASURES: Standing with legs and pelvis immobilized, subjects moved to a predetermined target position and then attempted to replicate the position. The 3-dimensional position of the trunk was measured with a 3Space Tracker. RE was calculated as the absolute difference between the actual target position and the subject-perceived target position. Testing was performed with and without a lumbar support both before and after wearing the support for 2 hours. RESULTS: In subjects with LBP, RE was significantly lower with a support in flexion, extension, and right lateral bending. In control subjects, RE was significantly lower when wearing the support in left bending only, and RE was significantly higher in control subjects after wearing the support for 2 hours. CONCLUSION: A lumbar support improves trunk RE. In subjects with LBP, this result was significant in the sagittal plane and in right lateral bending, whereas in control subjects, it was significant only in left lateral bending.
The effects of ruscogenin 1-O-[beta-D-glucopyranosyl(1 --> 2)] [beta-D-xylopyranosyl(1 --> 3)]-beta-D-fucopyranoside (Lm-3) and its aglycone, ruscogenin, on liver injury induced in mice by delayed-type hypersensitivity to picryl chloride have been investigated. Lm-3 and ruscogenin significantly decreased liver injury when given during the effector phase of the delayed-type hypersensitivity reaction. The pretreatment of nonparenchymal cells, but not hepatocytes, with Lm-3 or ruscogenin in-vitro caused a concentration- and time-dependent inhibition against the damage. Lm-3 showed a stronger inhibition against the damage than ruscogenin (IC50: Lm-3 6.3 x 10(-10) M, ruscogenin 3.9 x 10(-7) M). However, neither Lm-3 nor ruscogenin blocked the hepatotoxic potential of CCl4, when used to pretreat hepatocytes. Moreover, Lm-3 and ruscogenin inhibited concanavalin A-induced lymphocyte proliferation only at high concentrations. These results suggested that Lm-3 and ruscogenin improved the immunological liver injury by selectively causing dysfunction of the liver-infiltrating cells rather than by protecting hepatocyte membranes. Such characteristics would be significant for treating immunologically related liver diseases as well as for developing new drugs.
STUDY DESIGN: A mixed design for kinetic comparison of 2 types of one-handed backhand strokes and 2 skill levels in tennis. OBJECTIVES: To develop and evaluate a model to estimate the impact force on the racquet during tennis stroke, and to compare the peak impact force between one-handed backhand stroke with a long backswing and one-handed backhand stroke with a short backswing and between the beginning and advanced players. BACKGROUND: A one-handed backhand stroke is commonly used in tennis and may be associated with many upper extremity over-use injuries. An understanding of kinetics of the backhand stroke is essential for understanding injury mechanisms and prevention. METHODS AND MEASURES: Five male advanced tennis players and 4 male and 1 female beginning tennis players participated. Mean age was 32.2 +/- 7.0 years. Each subject was instructed to use the 2 types of one-handed backhand strokes to hit balls from a tennis ball machine. Three-dimensional coordinates of critical body and racquet landmarks were obtained. A mathematical model was developed to estimate the contact duration and the peak impact force during a stroke. RESULTS: The estimated peak impact forces were reproducible and comparable to those reported in the literature from direct measurements. A one-handed backhand stroke with a short backswing had a significantly shorter contact duration (0.008 +/- 0.003 seconds) and a greater peak resultant impact force (330.0 +/- 140.7) than that with a long backswing (0.016 +/- 0.004 seconds and 180.8 +/- 49.1 N). Skill level did not significantly affect the peak resultant impact force. CONCLUSION: A long backswing in a one-handed backhand stroke may reduce the load on the upper extremity and may assist in reducing the risks of tennis-related upper extremity over-use injuries.
Locally available sawdust, a byproduct of the world industry, was found to be a low cost and promising adsorbent for the removal of copper(II) from wastewater. In this work, adsorption of copper on sawdust has been studied by using batch techniques. The equilibrium adsorption level was determined to be a function of the solution pH, contact time, and sorbate concentration. The equilibrium adsorption capacity of sawdust for copper was obtained by using linear Freundlich and Langmuir isotherms. Ion exchange is probably one of the major adsorption mechanisms for binding divalent metal ions to the maple sawdust. The results provide strong evidence to support the hypothesis of adsorption mechanism. It also supplies significant sawdust operation capacity data for engineering design.
The identification of cross-over products in the rearrangement of two structurally similar sugar 1,2-orthoesters to glycosidic products is reported.