Chains Research Articles

Effects of Short-Term Jump Squat Training With and Without Chains on Strength and Power in Recreational Lifters

Background: The use of chains in resistance training is a way to accommodate the muscular strength curve. Short-term training and jump squats have been shown to increase back squat strength, but not in conjunction with each other or with chains. Jump squats have also been used to increase jump height and power. Objectives: The purpose of this study was to investigate the effects of short-term jump squat training with and without chains on strength and power. Methods: Thirty-one resistance-trained men volunteered to participate (age = 23.87 ± 2.2 years, height=174.87 ± 6.94 cm, mass = 82.74 ± 14.95 kg) and were randomly assigned to one of three groups [control (C) = 10, no chains (NC) =10, or chains (CH) = 11]. Participants had their jump height (VJ) and back squat strength (BS) tested before and after a week of training. The NC and CH groups performed three training sessions consisting of five sets of three reps of jump squats at 30% 1RM with 30s rest between sets. The CH group had 20% of their load added by chains when standing erect. The C group did not train. Results: A 3 (group: CH, NC, C) x 2 (time: pre, post) mixed factor ANOVA revealed a significant ( p = 0.006) interaction for back squat 1RM. Both the CH (pre 142.56 ± 20.40 kg; post 145.66 ± 19.59 kg) and NC (pre 150.00 ± 15.23 kg; post 154.77 ± 15.09 kg) groups significantly increased while the C (pre 157.27 ± 25.35 kg; post 156.36 ± 24.85 kg) group showed no difference. There were no significant interactions ( p =0.32) or main effects for VJ (C = pre 50.59 ± 9.39cm; post 51.29 ± 9.68cm; NC = pre 55.29 ± 5.23cm; post 57.39 ± 5.22cm; CH = pre 46.19 ± 5.02; post 47.45 ± 4.62.) Conclusions: The CH group was able to increase strength while lifting less overall weight. Coaches may use short-term training with chains to yield a similar increase in back squat strength as without chains. Keywords : variable resistance, back squats, novel, vertical jump

Interaction Between 1-Dodecyl-3-Methylimidazolium Bromide and Sodium Carboxymethylcellulose in Aqueous Solution: Effect of Polymer Concentration

Effect of the concentration of water-soluble polyanion (sodium carboxymethylcellulose, NaCMC) on the interaction between a cationic surfactant (1-dodecyl-3-methylimidazolium bromide, C12mimBr) and NaCMC in aqueous solution has been studied by isothermal titration microcalorimetry (ITC), conductivity, surface tension, and rheological measurements. From the surfactant/polymer interacting enthalpy, it can be deduced that the electrostatic attraction between the cationic surfactant and anionic polyelectrolyte causes an endothermic process, and the C12mimBr monomers binding to the NaCMC chains to form micelle-like aggregates through hydrophobic interaction is an exothermic process. Increasing the NaCMC concentration causes the interaction between C12mimBr and NaCMC to decrease, and the characteristic surfactant concentrations, including the critical aggregation surfactant concentration (CAC), the surfactant concentration to form free micelles (Cm), and the saturation concentration of surfactant on the NaCMC chains (CS) to increase. Because of the strong electrostatic interaction between C12mimBr and NaCMC, the formation of C12mimBr/NaCMC complexes can lead to precipitation or redissolution depending on solution composition, so the critical precipitation concentration (CP) and the onset of a redissolution concentration (CR) has been determined by the electrical conductivity. The rheological results reveal a dramatic increase in solution viscosity around the CAC, attributed to interpolymer cross-linking through the formation of mixed micelles involving the carboxylic acid groups of NaCMC and the surfactant.

Chondroitin sulfate prevents platelet derived growth factor‐mediated phosphorylation of PDGF‐Rβ in normal human fibroblasts severely impairing mitogenic responses

Platelet-derived growth factor (PDGF) is a major polypeptide mitogen for cells of mesenchymal origin such as fibroblasts. Chondroitin sulfate chains (CS), which are abundant in the extracellular matrix have been shown to physically interact with PDGF-BB modulating its biological function. The aim of the present study was to examine the involvement of CS on PDGF-BB induced proliferative responses and receptor activation in human lung fibroblasts. The addition of exogenous free CS chains caused a significant downregulation of the PDGF-BB mediated mitogenic and chemotactic responses. Similar results were obtained by the increase of endogenous CS biosynthesis after beta-D-xyloside treatment. Furthermore, removal of the membrane-bound CS chains by selective enzymatic treatment significantly increased the proliferative capacity of human fibroblasts. Analysis of PDGF-R phosphorylation in the presence of CS or beta-D-xyloside, revealed a reduction of PDGF-Rbeta phosphorylation in the tyrosine residue 1021. These results demonstrate, for the first time, that CS either soluble or surface bound downregulates the mitogenic responses of PDGF-BB in normal human lung fibroblasts through the reduction of PDGF-Rbeta phosphorylation.

Superconducting critical temperature, oxygen ordering and devil's staircase in YBa 2Cu 3O 6+ [formula omitted

Using the appropriate extension of the three-band Hubbard model to describe the basal CuO 2+ x subsystem of YBa 2Cu 3O 6+ x , for a certain region of parameters we obtain: a) the number of holes n H in the superconducting planes and T c as a function of x have a plateau, b) using a structural model to include the effect of interatomic OO repulsions, there is a transition from structures without first or second nearest-neighbor O atoms (HS) to order in chains (CS) at x ∼ 0.45 for increasing x . We also study the structural model for values of x for which the CS are stable.

Carbohydrate antigen type 2 chain N-acetyllactosamine (2NAcLc) as a histological marker of rat parietal cells

Lectin-staining suggested parietal cell-specific sugar antigens I-3" We reported here the rat parietal cell-specific expression of 2NAcLc. MATERIALS AND METHODS: Stomachs from five male Wistar rats (7weeks old) were fixed with 10% neutral buffered formalin for immunostaining. Mouse monoclonal antibody K214 (anti-INAcLc) and anti-My285 (anti-2NAcLc) were kindly donated by Prof. Lloyd (The Memorial Sloan-Kettering Cancer Center) and Prof. Civin (The Johns Hopkins University School of Medicine) respectively. Carbohydrate antigens were localized with an ABC method. RESULTS: Parietal cells expressed 2NAcLc in all cases(Fig. A). Parietal cells at the neck of the glands expressed 2NAcLc strongly and those among surface mucous cells weakly. Surface mucous cells and other cell types composing the oxyntic, cardiac and pyrolic glands did not express 2NAcLc. Only a small number of parietal cells at the base of the glands expressed INAcLc (Fig. B). DISCUSSION: Rat p a r i e t a l c e l l s express 2NAcLc, but do not or on ly r a r e l y i t s s t r u c t u r a l isomer iNAcLc. As no o t h e r c e l l s in r a t stomach exp re s s 2NAcLc, t h i s a n t i g e n may be u s e f u l as a h i s t o l o g i c a l marker of r a t p a r i e t a l c e l l s . As l e c t i n s and a n t i M y 2 8 s t a i n e d t h e a l m o s t same s t r u c t u r e s , s u g a r c h a i n s d e t e c t e d by l e c t i n s , a t l e a s t one o f them, may be 2NAcLc. I n t r a c e l l u l a r 2 N h c L c p o s i t i v e s t r u c t u r e s were r e c e n t l y shown to be s e c r e t a r y c a n a l i c u l i by i m m u n o e l e c t r o n m i c r o s c o p y ( S u z u k i K, Usumoto R, 0 k a d a Y, u n p u b l i s h e d o b s e r v a t i o n ) . The p r e s e n t r e s u l t and the p rev ious o b s e r v a t i o n t h a t l a c t o s e : H + c a r r i e r p a r t i c i p a t e s in p ro ton t r a n s p o r t in E. c o l t 6 sugges t p o s s i b l e i n v o l v e ment of sugar cha ins in ac id s e c r e t i o n . REFERENCESI)Kessimian N, et al: J Histochem Cytochem 1986,34:237. 2)Schulte BA: et al. j Histochem Cytochem 1983,31:19. 3)Fisher J: Histochemistry 1987,87:479. 4) Rettig WJ, et al: Cancer Re 1985,45:85. 5)Spitalnik SL, et al: Blood 1985,66:319. 6)Wright JK, e t a l : Ann NY Acad Sci 1985,456:326. INDEX WORDS: P a r i e t a l c e l l , Carbohydra te an t igen .

A Model System that Demonstrates Interactions Among Extracellular Matrix Macromolecules

Binding interactions among fibronectin (FN), glycosaminoglycan chains (GAG) and hyaluronate binding proteins (HABP) have been examined using a bead aggregation assay. 3H-FN binds to Dowex beads coated with chondroitin sulfate GAG chains (CS) but not to beads coated with hyaluronic acid (HA). Assays of bead agglutination indicate that FN has multiple binding sites for CS. Binding of 3H-FN to HA-beads is slightly promoted by exogenous divalent cations but this interaction does not aggregate Dowex-HA. The interaction between FN and CS reduces the previously reported ability of Dowex-CS to associate with HA-beads (Turley, E.A. and Roth, S. 1980, Nature Vol. 283, 268-271). HABP bind to HA and to a lesser extent CS. These proteins both stabilize the interaction between HA- and CS-beads in a manner reminiscent of the stabilization of HA-proteoglycan interactions by link protein and permit aggregation of Dowex-CS-FN with Dowex-HA. This simple bead aggregation assay allows rapid characterization of properties that may help to clarify how macromolecular constituents spontaneously assemble into an interstitial matrix.

Altered proteoglycan synthesis by epiphyseal cartilages in culture at low SO4(2-) concentration.

Proteoglycan Type H formed by incubation of chick embryo epiphyseal cartilages with [14C]glucosamine altered its buoyant density as the concentration of SO4(2-) in medium was lowered from 300 to 0 microM. At the highest SO4(2-) concentration, the labeled product was essentially identical with unlabeled proteoglycan Type H (i.e. the molecules already preformed in ovo) with respect to the buoyant density and hyaluronic acid-binding activity. With decreasing the SO4(2-) concentration in medium, the products showed a gradual decrease in the buoyant density with no apparent change in the hyaluronic acid-binding activity. This change of buoyant density was directly related to a decrease in average sulfation degree of the chondroitin sulfate moiety, which in turn reflected an increase in the ratio of low sulfated chondroitin chains (Chn) to high sulfated chondroitin sulfate chains (CS) per proteoglycan molecule. At intermediate SO4(2-) concentrations, 50 and 100 microM, the labeled products were of hybrid type containing both Chn and CS chains. Treatment of such hybrids with trypsin yielded, in each case, a mixture of CS- and Chn-carrying peptide fragments with an average buoyant density slightly lower than that of the parent proteoglycan. In no case were these fragments separated into two discrete groups corresponding to Chn-rich peptides and CS-rich peptides, respectively, suggesting that the two types of polysaccharide chain are rather evenly distributed along the core protein.

The Influence of Morphology on the Electric Strength of Polymer Insulation

This paper describes the effect of morphological structure on the electric strength and some physico-chemical properties of polymers with flexible chains (HDPE, LDPE, PP) and polymers with rigid chains (CA). It is shown that a polymer body has a discrete structure consisting of elements of different densities. The most regular structure with high density is characteristic of spherulites. Their size may be modified by different methods: heat treatment, plasticization, addition of nucleating agent, modification of molecular weight, etc. The inter-spherulitic boundary regions are shown to determine the electrical properties of the specimen as a whole. As the spherulite size decreases, the density of the polymer within the boundary regions increases, improving the electric strength.

Myelomonocytic Leukemia in an Orangutan

Myelomonocytic Leukemia in an Orangutan

Immunochemical studies of the a allotypes of rabbit heavy chain variable regions—II: Immunological properties of peptides from variable regions of heavy chains of limited heterogeneity and a3 allotype

Immunological properties of peptides from two different heavy chains of a3 allotype and restricted heterogeneity were studied using radioimmunoassays that involved inhibition by these peptides of a reaction between 125I labeled anti-a3 antibodies and Sepharose-bound a3 IgG. A purified fraction of a2-anti-a3 which cross reacts with at IgG was used for the assays of peptides from one of the heavy chains (AH80-5). The picomoles of various inhibitors required for 50% inhibition of the a3-anti-a3 reactions were determined and the corresponding Δ G 0 values were calculated. Citraconylation of the lysine side chains (CH) markedly affected the inhibitory activity of one of the two heavy chains (AH80-5) and had a lesser effect [Δ(Δ G 0) 1.4 kcal/mole] on the other. In both instances when the lysines of the tryptic peptides were deblocked by exposure to low pH, we observed gains in activity (1.3–1.7 kcal/mole). Although some of the primary structure which contributes to some a3-antigenic determinants may have been removed by tryptic digestion, the immunopeptides which we recovered inhibited at least 60% of the maximal binding of purified, labeled a 2 anti-a3 antibodies to a3 IgG. Thus major antigenic determmant(s) recognized by these particular anti-a3 antibodies, were retained on the portions of V H region recovered from the tryptic digests. It is probable that losses in conformation contributed to the changes in Δ G 0

Chronic suppression of immunoglobulin allotype production in adult congenic mice.

MOUSE allotypes refer to the inheritance of antigenic differences on the constant region of immunoglobulin (Ig) heavy chains (CH). As such, allotypes are used as genetic markers to distinguish allelic CH genes, the expression of which is codominant in heterozygous mice1,2. The expression of a paternal CH gene, however, can be suppressed in heterozygote offspring if the mother has previously been made immune to the allotype encoded by the paternal gene3. Neonatally induced suppression of this sort is known to lead to (or result in) the generation of allotype-specific suppressor T lymphocytes which directly or indirectly prevent allotype production by B lymphocytes4–6. In contrast to this we have shown that allotype suppression can also be initiated in adult mice, that is in BALB/c mice that are congenic for the C57BL allotype (C.B-17 mice)1. When X-irradiated C.B-17 mice (550 r.) are injected with thymocytes from BALB/c donors immune to the C57BL allotype, IgG2a allotype production in the C.B-17 recipients becomes chronically suppressed7. We now report that allotype suppression in C.B-17 mice is mediated by T cells; that production of only the IgG2a class allotype (G2) is suppressed, presumably as a result of direct interaction between specific T and B cells, and that the capacity of spleen cells to suppress host allotype production can be transferred serially from one C.B-17 mouse to another and as yet without obvious limit.

Genetic control of variable and constant regions of immunoglobulin heavy chains.

IMMUNOGLOBULIN polypeptide chains consist of two well defined regions designated the “variable region” and the “constant region”. Whereas great diversity exists in amino-acid sequences of variable regions, the constant regions of a given subclass of heavy chains (CH)* are essentially invariant in sequence1, 2. Exceptions are the allelic forms, such as the rabbit allotypes A14 and A153, 4, where a threonine-alanine interchange occurs in the constant region of γ chains (Appella, Chersi, R. G. M. and Dubiski, in preparation). The markers unique to a chains (for example, A14-A15) are closely linked to allotypic markers at the a locus (a1, a2, a3)3, 4 which seem to be present on four different Ig heavy chain classes (α, γ, e, µ)5–7. These puzzling observations can be explained if the a locus determinants are variable region markers which reflect genetically controlled differences in some relatively constant residues within the VH region sequences7.