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This paper focuses on the active cell balancing of lithium-ion battery packs. An improved single-input, multioutput, bi-switch flyback converter was proposed to achieve effective balancing. The proposed topology simplifies the control logic by utilising a single MOSFET switch for energy transfer and two complementary pulses to control the cell-selecting switches. The proposed topology can decrease the number of switching devices as well as the size and cost of the system. The bi-switch flyback converter eliminates the need for a separate buffer circuit to minimise leakage and electromagnetic inductance. Losses and energy efficiency were analysed at each end of the proposed topology. The appropriate MATLAB simulations investigated the balancing characteristics of various state of charge (SOC) imbalances. A comparison is made between the balancing speed and energy transfer efficiency of the proposed topology and a conventional topology that employs a multi-input and multi-output flyback converter in a static mode. The results of the MATLAB simulation were validated by the OPAL-RT (OP5700) real-time simulator. The balancing data of the proposed topology were compared using MATLAB simulation and real-time simulation. This work may reduce the time required to assemble and commission the hardware for the proposed topology’s real-time implementation.

Li-ion batteries have increased dramatically in the automobile industry over the past few decades. Lithium-ion batteries are viewed more favourably due to their high energy density, specific energy, etc. Optimising the performance of lithium-ion batteries requires accurate modelling and estimation of the state of charge (SOC). This article introduces an efficient second-order resistor-capacitor (2RC) network battery model and an optimised extended Kalman-Bucy filter (EKBF) as the most effective way to model a battery and estimate its state of charge (SOC). The operating parameters of a lithium-ion battery are measured with the least-squares curve fitting method. At a temperature of 20 °C, the proposed method for estimating SOC has a mean absolute error (MAE) of 0.72 % and a root mean square error (RMSR) of 0.71 %. In addition, the operational characteristics of the proposed EKBF were validated by simulating its operation at temperatures ranging from 0 °C to 40 °C. Under all conditions, the proposed method maintained an average error rate of 0.40%. The output of the proposed topology was validated using OPAL-RT (OP5700) hardware-in-the-loop real-time simulator. Consequently, the proposed method is preferable for accurate and dependable SOC estimation in real-time battery management system (BMS) applications.

The pathogenesis of the amyloid deposition diseases is poorly understood. The CE/J mouse, which is naturally protected from amyloid A (AA) protein amyloidosis, has provided a tool to study mechanisms that may be implicated in amyloid deposition diseases by means of comparison of findings with those in an AA-susceptible mouse strain. We have compared proteoglycan/glycosaminoglycan accumulationin vivoin amyloid-protected CE/J mouse strain and in AA-susceptible CBA/J mouse strain in homeostasis and when injected with amyloid-inducing agents. Results indicate that there is an overall increase in[35S]proteoglycan/glycosaminoglycan accumulation in the spleens of both strains of mice, but with a specific increase in heparan sulfate in only CBA/J mouse spleens that are rich in amyloid. Further, we report the absence of heparan sulfate in the splenic perifollicular areas of amyloid-free CE/J mouse, whereas in the amyloid-laden CBA/J mouse there is co-localization of heparan sulfate with the AA deposits. We have also examined the glycosaminoglycan disaccharide products in both these strains of mice for their sulfation positions and found no differences in the disaccharide composition of chondroitin/dermatan sulfate and heparan sulfate isolated from the control CBA/J and control CE/J mice. There were no differences in chondroitin/dermatan sulfate in both strains after experimental induction. However, analysis of the heparan sulfate disaccharides by means of capillary high-performance liquid chromatography linked to microelectrospray ionization time-of-flight mass spectrometry indicated that the disaccharide composition of the splenic heparan sulfate obtained from the treated CBA/J mice that had developed amyloid was markedly different from that obtained from the control CBA/J mice and the treated amyloid-resistant CE/J mice. These findings suggest that unique heparan sulfates play a fundamental role in the pathogenesis of amyloid. [ABSTRACT FROM AUTHOR]

Elevations in urinary hyaluronan have been used as the principal laboratory indicator for diagnosis of Hutchinson-Gilford Progeria Syndrome (HGPS). Previous reports have provided evidence suggesting that children with HGPS have altered hyaluronan metabolism as indicated by a mean 17-fold increase in urinary hyaluronan over normal values. In addition, adults with Werner's syndrome have elevated urinary hyaluronan and even more prominent elevations in serum hyaluronan over age-matched controls. It is not known whether serum hyaluronan is elevated or whether serum hyaluronan levels correlate with urinary hyaluronan levels in children with HGPS. In a large cohort of 19 HGPS patients, we sought to confirm elevations in urinary hyaluronan concentration, to establish whether serum hyaluronan is elevated, to measure the size of urinary hyaluronan, and to determine whether serum or urine hyaluronidase levels are altered. We have analyzed urinary and serum hyaluronan levels in patients with HGPS and control patients (1) by using an enzyme-linked immunosorbent assay (ELISA)-like method in which sample hyaluronan in solution and hyaluronan in solid phase compete for a solution of biotinylated hyaluronan-binding protein, and (2) by fluorophore-assisted carbohydrate electrophoresis. The size of urinary hyaluronan was measured by using Sepharose CL-6B size exclusion chromatography. Serum and urinary hyaluronidases were evaluated quantitatively, by using ELISA, and qualitatively, by using a gel detection method. HGPS patients did not show a significant elevation in either urinary or serum hyaluronan. We detected no difference in the size of urinary hyaluronan between HGPS children and age-matched controls. Serum and urinary hyaluronidase levels were not significantly different in normal and HGPS patients. These studies indicate that neither serum nor urinary hyaluronan concentration is a reliable diagnostic or prognostic marker for HGPS and underscore a difference between adult and childhood progerias.

The objective of this study was to determine the characteristics of proteoglycans synthesized by canine annulus fibrosus cells expanded in number in monolayer culture through passage 4 and subsequently grown in a type I collagen-glycosaminoglycan matrix to be employed for tissue engineering. Newly synthesized [35S]sulfate-labeled proteoglycans were analyzed by gel chromatography, including sequential digestion with enzymes and nitrous acid. After 1 week in culture, the percentage of cell-associated, aggregated proteoglycans synthesized in type I collagen-glycosaminoglycan matrices was 52% compared with 38% by the cells in monolayer. The percentage of aggregated proteoglycan in each group increased only slightly with the addition of exogenous hyaluronic acid, but remained significantly different from each other. There were at least three different hydrodynamic sizes of proteoglycans both in the collagen-glycosaminoglycan matrix and in monolayer; the average size was larger in the collagen matrices and the glycosaminoglycan chains were longer. The proteoglycans contained chondroitin sulfate, dermatan sulfate, heparan sulfate, and keratan sulfate. The results provide a foundation for future investigations of collagen-glycosaminoglycan matrices for intervertebral disc tissue engineering.

Chondroitin sulfate and dermatan sulfate are synthesized as galactosaminoglycan polymers containing N-acetylgalactosmine alternating with glucuronic acid. The sugar residues are sulfated to varying degrees and positions depending upon the tissue sources and varying conditions of formation. Epimerization of any of the glucuronic acid residues to iduronic acid at the polymer level constitutes the formation of dermatan sulfate. Chondroitin/dermatan glycosaminoglycans are covalently attached by a common tetrasaccharide sequence to the serine residues of core proteins while they are adherent to the inner surface of endoplasmic reticulum/Golgi vesicles. Addition of the first sugar residue, xylose, to core proteins begins in the endoplasmic reticulum, followed by the addition of two galactose residues by two distinct glycosyl transferases in the early cis/medial regions of the Golgi. The linkage tetrasaccharide is completed in the medial/trans Golgi by the addition of the first glucuronic acid residue, followed by transfer of N-acetylgalactosamine to initiate the formation of a galactosaminoglycan rather than a glucosaminoglycan. This specific N-acetylgalactosaminyl transferase is different from the chondroitin synthase involved in generation of the repeating disaccharide units to form the chondroitin polymer. Sulfation of the chondroitin polymer by specific sulfotransferases occurs as the polymer is being formed. All the enzymes in the pathway for synthesis have been cloned, with the exception of the glucuronyl to iduronyl epimerase involved in the formation of dermatan residues.

Cultured peritoneal macrophages obtained from azocasein-injected mice were found to produce several fold more cell-associated and medium proteoglycans than peritoneal macrophages from untreated mice. Since serum amyloid A (an acute-phase protein) is also upregulated following injections of azocasein, we questioned whether its production was the immediate agent stimulating proteoglycan formation. Cultured peritoneal macrophages from untreated mice were then incubated with varying concentrations of SAA, resulting in a similar dose-dependent several fold increase in proteoglycan production. Of particular note was a disproportionate increase in cell-associated heparan sulfate proteoglycans in both experimental groups and of dermatan sulfate and chondroitin sulfate proteoglycans when cells were incubated in the presence of SAA in the culture medium. These results indicate a potentially important function of SAA in directing specific modifications in inflammatory conditions where increase in macrophage proteoglycans may play direct roles., (Copyright 1999 Academic Press.)

Microsomal membranes from chick embryo epiphyseal cartilage were fractionated by equilibrium sucrose-density-gradient centrifugation and assayed for GlcA (glucuronic acid) transferase I (the enzyme that transfers GlcA from UDP-GlcA to Gal-Gal-Xyl of proteochondroitin linkage region), for comparison with GlcA transferase II (the GlcA transferase of chondroitin polymerization). Gal(beta1-3)Galbeta1-methyl (disaccharide) and GalNAc(beta1-4)GlcA(beta1-3)GalNAc(beta1-4) GlcA(beta1-3)GalNAc(pentasaccharide) were used respectively as acceptors of [14C]GlcA from UDP-[14C]GlcA. Distributions of the two GlcA transferase activities in the sucrose-density-gradient fractions were compared with each other and with the previously reported distribution of the activities of Gal transferases (UDP-Gal to ovalbumin, and to xylose of the proteochondroitin linkage region) and GalNAc (N-acetylgalactosamine) transferase II of chondroitin polymerization. The linkage-region GlcA transferase I had a dual Golgi distribution similar to that of chondroitin-polymerizing GlcA transferase II and distinctly different from the distribution of linkage-region Gal transferases I and II, which were found exclusively in the heavier fractions. Solubilized GlcA transferase I was partly purified by sequential use of Q-Sepharose, heparin-Sepharose and wheatgerm agglutinin-agarose and was accompanied at each step by some of the GlcA transferase II activity. Both GlcA transferase I and II bound to the Q-Sepharose as though they were highly anionic. However, treatment with chondroitin ABC lyase eliminated the binding while markedly decreasing enzyme stability. The enzyme activities could not be reconstituted by adding chondroitin or chondroitin pentasaccharide to the chondroitin ABC lyase-treated enzymes. Incubation of the partly purified enzymes with both UDP-GlcA and UDP-GalNAc resulted in a 40-fold greater incorporation than with just one sugar nucleotide, indicating the presence of bound, nascent proteochondroitin serving as the acceptor for chondroitin polymerization. These results, together with the membrane co-localization, indicate that GlcA transferase I and GlcA transferase II occur closely together with nascent proteochondroitin at the site of synthesis and that this complex with the nascent proteochondroitin stabilizes both enzymes during purification.

Hs 198.St cells (a line derived from normal human gastric tissue), Hs 746T cells (a line derived from human gastric adenocarcinoma), and HeLa cells were used together with 3H-labelled Helicobacter pylori, strain NCTC 11637 to determine if cell surface glycosaminoglycans could act as initial receptors for adherence of the bacteria. Although as much as 40% of the 3H-labelled bacteria adhered to monolayers of the cultured cells, removal of glycosaminoglycans by prior treatment of the cells with heparitinase, heparinase, or chondroitin ABC lyase had no effect in modifying the adherence. Prior addition of heparan sulfate, heparin, or chondroitin/dermatan sulfate to bacteria had no effect on adherence, nor were bacteria released when these same glycosaminoglycans or these same enzymes were added to cultures already containing adherent bacteria. These results indicated that neither heparan sulfate nor chondroitin/dermatan sulfate are involved as receptors in the initial adherence step of H. pylori to these cultured cells.

Mouse mastocytoma cells were cultured in medium containing [3H]GlcN and concentrations of [35S]sulphate varying from 0.01 to 0.5 mM. Intracellular [35S]sulphate incorporation increased severalfold from the lowest concentrations, reaching a maximum at 0.1-0.2 mM, whereas incorporation of [3H]hexosamine remained constant at all sulphate concentrations. Proteo[3H]-chondroitin [35S]sulphate was isolated and incubated with chondroitin ABC lyase, yielding 35S-labelled and/or 3H-labelled delta Di-0S and delta Di-4S disaccharide products. The increasing percentage of delta Di-4S was consistent with the increasing sulphate incorporation at each higher [35S]sulphate concentration. Examination of proteochondroitin [35S]sulphate size by Sepharose CL-6B chromatography indicated a range consistent with various numbers of glycosaminoglycan chains on the protease-resistant serglycin core protein. Alkali-cleaved chondroitin [35S]sulphate products indicated similar size distributions at all sulphate concentrations with no indication of preferential sulphation being related to smaller or larger size. DEAE-cellulose chromatography of [3H]chondroitin [35S]sulphate glycosaminoglycans indicated a random undersulphation as [35S]sulphate concentration was lowered. Addition of 4-methylumbelliferyl beta-D-xyloside to the cultures resulted in a 2-2.5-fold stimulation of [3H]chondroitin [35S]sulphate synthesis with formation of beta-xyloside-[3H]chondroitin [35S]sulphate which was much smaller, as estimated by Sepharose CL-6B chromatography, than the decreased amount of [3H]chondroitin [35S]sulphate derived from proteo[3H]chondroitin [35S]sulphate. Much higher concentrations of sulphate were necessary to produce sulphation of the beta-xyloside-[3H]chondroitin comparable with that of proteo[3H]-chondroitin, as indicated by chondroitin ABC lyase products and DEAE-cellulose chromatography. The specific radioactivities of the [3H]GalN in the proteo[3H]chondroitin [35S]sulphate and beta-xyloside-[3H]chondroitin [35S]sulphate were calculated from the 3H and 35S c.p.m. of isolated dual-labelled delta Di-4S from each, and indicated that the presence of the beta-xyloside resulted in a dilution of the [3H]GlcN by endogenous GlcN that was 4 times higher than that of cultures lacking the beta-xyloside. The higher sulphate concentrations needed for sulphation of beta-xyloside-chondroitin suggests that the membrane-bound nature of the proteochondroitin acceptor in juxtaposition to a chondroitin sulphate-synthesizing enzyme complex effectively reduces the apparent Km for adenosine 3'-phosphate 5'-phosphosulphate.

Mouse mastocytoma cells were cultured with brefeldin A in medium containing [35S]sulfate and [3H]glucosamine in order to determine the effects of this fungal metabolite on the formation of chondroitin 4-sulfate by these cells. There was a marked reduction in the incorporation of [35S]sulfate into the glycosaminoglycan which was approximately equal to the reduction in the incorporation of [3H]hexosamine into the same molecule. The chondroitin 4-sulfate chain size was greatly diminished, while the number of chains appeared to remain relatively constant, indicating that the brefeldin A partially disrupted the polymerizing system, but had little effect upon movement of the nascent proteochondroitin to the site for chondroitin polymerization and sulfation.

Chondrocytes derived from normal human adult articular cartilage were established and maintained for over 5 months in a completely defined medium without the addition of serum or any other growth factors. At the end of 5 months, these cells were still metabolically active. The cells incorporated [3H] thymidine into DNA, incorporated [35S] sulfate into proteoglycans, and exhibited lysosomal enzyme activities. The 35S-labeled proteoglycans isolated from the culture medium had elution profiles on high pressure liquid chromatography (HPLC) similar to those observed for proteoglycans from other mammalian sources. This self-contained growth competence may reflect a need produced by the unusual avascular and alymphatic character of articular cartilage.

Formation of two species of [14C]proteochondroitin sulfate has previously been demonstrated with UDP-D-[14C]glucuronic acid and UDP-N-acetylgalactosamine as substrates with a microsomal preparation from chick-embryo epiphyseal cartilage. A large species of [14C]proteoglycan that appeared at an earlier stage of synthesis was excluded on Sepharose CL-2B, indicating that it was larger than proteoglycans found in cartilage matrix. Another newly synthesized, smaller [14C]proteoglycan species also formed was retarded on Sepharose CL-2B, and appeared to be at a later stage of synthesis. A 6-h pulse-chase experiment using UDP-[14C]GlcA and UDP-GalNAc followed by cold UDP-GlcA demonstrates that there was no conversion of the large [14C]proteoglycan to the small [14C]proteoglycan. Sulfation of the newly formed large and small [14C]proteoglycans with adenylyl sulfate 3'-phosphate also did not alter their chromatographic patterns, indicating that sulfation did not trigger any post-synthetic size modification. Synthesis with lower concentrations of the sugar nucleotides resulted in a disproportionate diminution in formation of the large proteoglycan. The apparent Km values for UDP-GlcA for the formation of large and small proteoglycans were 0.055 and 0.015 mM, respectively. Concentration requirements for UDP-GalNAc also showed a similar 4-fold difference. These results indicate that, even though the large proteoglycan was at an earlier stage of synthesis, it was not a precursor to the small proteoglycan, and that these proteoglycans represent two separately synthesized species.