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PubMed2026

Decoupled Synthesis Pathway via Precursor Functionalization Stabilizes High-Voltage Nickel-Based Cathodes.

Nickel-based layered cathodes are promising candidates for high-performance, high-energy lithium-ion batteries, yet their high-voltage application is jointly limited by synthesis-inherited structural defects and an unstable lattice oxygen framework. Here, we show that both limitations can be overcome by decoupled synthesis pathway (DSP) via La/Nb oxalate functionalization of the Ni0.6Co0.1Mn0.3(OH)2 precursor. Unlike the conventional coupled synthesis pathway (CSP) where precursor dehydration and Li2CO3 decomposition overlap in temperature, the DSP introduces a low‑temperature decomposition of La/Nb oxalates at 200°C, which effectively avoids localized contact between the precursor and Li2CO3 and shifts Li2CO3-related reactions to high temperatures. This allows sequential precursor dehydroxylation, rock‑salt (RS) intermediate formation, and layered‑phase transformation over a broad temperature window. The resulting LiNi0.6Co0.1Mn0.3O2 cathode with La/Nb functionalization (NCM-LN) features a uniform surface LaNiO3 perovskite heterostructure and a Nb‑doped layered bulk with suppressed RS and spinel defects. Consequently, under 4.5 V operation (vs. Li+/Li), NCM-LN exhibits homogeneous Li+ (de)intercalation, and a stabilized oxygen framework. In graphite||NCM-LN full cells, NCM-LN retains 80.1% of its capacity after 2000 cycles at 1C, substantially outperforming the pristine cathode. This decoupling strategy is broadly effective across various Ni‑based systems, providing a generalizable route toward high‑energy, long‑life cathode materials.

decoupled synthesis pathway↗
PubMed2005

Metabolic signatures associated with a NAD synthesis inhibitor-induced tumor apoptosis identified by 1H-decoupled-31P magnetic resonance spectroscopy.

PURPOSE: Attempts to selectively initiate tumor cell death through inducible apoptotic pathways are increasingly being exploited as a potential anticancer strategy. Inhibition of NAD+ synthesis by a novel agent FK866 has been recently reported to induce apoptosis in human leukemia, hepatocarcinoma cells in vitro, and various types of tumor xenografts in vivo. In the present study, we used 1H-decoupled phosphorus (31P) magnetic resonance spectroscopy (MRS) to examine the metabolic changes associated with FK866 induced tumor cell death in a mouse mammary carcinoma. EXPERIMENTAL DESIGN: Induction of apoptosis in FK866-treated tumors was confirmed by histology and cytofluorometric analysis. FK866-induced changes in mammary carcinoma tumor metabolism in vivo were investigated using 1H-decoupled 31P MRS. To discern further the changes in metabolic profiles of tumors observed in vivo, high-resolution in vitro 1H-decoupled 31P MRS studies were carried out with perchloric acid extracts of mammary carcinoma tumors excised after similar treatments. In addition, the effects of FK866 on mammary carcinoma tumor growth and radiation sensitivity were studied. RESULTS: Treatment with FK866 induced a tumor growth delay and enhanced radiation sensitivity in mammary carcinoma tumors that was associated with significant increases in the 31P MR signal in the phosphomonoester region and a decrease in NAD+ levels, pH, and bioenergetic status. The 31P MRS of perchloric acid extracts of treated tumors identified the large unresolved signal in the phosphomonoester region as the resultant of resonances originating from intermediates of tumor glycolysis and guanylate synthesis in addition to alterations in pyridine nucleotide pools and phospholipid metabolism. CONCLUSION: The present results suggest that FK866 interferes with multiple biochemical pathways that contribute to the increased cell death (apoptosis) and subsequent radiation sensitivity observed in the mammary carcinoma that could be serially monitored by 31P MRS.

Acrylamides↗
PubMed1998

Type I collagen synthesis in cultured human fibroblasts: regulation by cell spreading, platelet-derived growth factor and interactions with collagen fibers.

Type I collagen protein and pro-alpha 1(I) collagen mRNA levels were investigated in human dermal fibroblasts cultured on substrates which induced distinct morphologies. Induction of type I collagen protein synthesis required cell spreading in monolayer cultures; mere attachment to dishes coated with 2-hydroxyethyl methacrylate (poly(HEMA)) did not suffice. Spread cells or round cells cultured on poly(HEMA) differed in collagen type I production, but pro-alpha 1(I) collagen mRNA levels were similar. Recombinant human platelet-derived growth factor (PDGF)-BB could replace cell spreading as a stimulus for collagen synthesis in cells cultured on poly(HEMA). At later time points, pro-alpha 1(I) collagen mRNA levels were down-regulated, although relatively less than type I collagen synthesis. Type I collagen synthesis by fibroblasts cultured in three-dimensional collagen gels was strongly down-regulated at both the protein and RNA levels. In addition to its capacity to stimulate collagen synthesis, PDGF-BB induced elongation and the formation of long processes by fibroblasts cultured in collagen gels. The stimulatory effect by cell spreading and PDGF-BB on collagen synthesis was inhibited by the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002. However, inhibition of PI3K only inhibited induction of collagen synthesis by actively spreading cells or by PDGF-BB and did not induce a down-regulation of collagen synthesis in cells which had already spread. These data demonstrate that type I collagen protein synthesis is partly independent of pro-alpha 1(I) collagen mRNA levels but highly regulated by cell shape, although this could be decoupled by PDGF-BB. Both cell shape- and PDGF-BB-induced stimulation of collagen type I synthesis depends on a signalling pathway involving PI3K. Furthermore, levels of pro-alpha 1(I) collagen mRNA in fibroblasts are partly cell shape independent but are down-regulated by fibroblast interactions with native collagen fibers.

Adult↗
PubMed2005

Synthesis and structure of the organometallic MFe2(mu3-S)2 clusters (M = Mo or Fe).

New organometallic clusters with the MFe2(mu3-S)2 core (M = Mo or Fe) have been synthesized from inorganic [MoFe3S4] or [Fe4S4] clusters under high pressure CO. The reaction of (Cl4-cat)2Mo2Fe6S8(PR3)6[R = Et, (n)Pr] with high pressure CO produced the crystalline [MoFe2S2]4+ clusters, (Cl4-cat)Mo(O)Fe2S2(CO)(n)(PR3)6-n[n= 4, Et =I, (n)Pr =II; n = 5, Et =III] after flash column chromatography. The similar [MoFe2S2]4+ cluster, (Cl4-cat)2MoFe2S2(CO)2(depe)(2)(IV), also has been achieved by the reactions of (Cl4-cat)MoFe3S3(CO)6(PEt3)2 with depe by reductive decoupling of the cluster. For the [Fe3(mu3-S)2]4+ cluster, [Fe4S4(PcHex3)4](BPh4) was reacted with high pressure CO to produce a new Fe3S2(CO)7(PcHex)(2)(V) compound. These reactions generalized the preparation of organometallic compounds from inorganic clusters. All the compounds have been characterized by single crystal X-ray crystallography. A possible reaction pathway for the synthesis of the MFe2(mu3-S) clusters (M = Mo or Fe) has also been suggested.

Crystallography, X-Ray↗
PubMed2001

Tissue shear deformation stimulates proteoglycan and protein biosynthesis in bovine cartilage explants.

Chondrocytes are known to sense and respond to mechanical and physicochemical stimuli by multiple regulatory pathways, including upstream signaling, transcription, translation, posttranslational modifications, and vesicular transport. Due to the complexity of identifying the biophysical phenomena that occur during cartilage loading in vivo, the regulatory mechanisms that govern chondrocyte mechanotransduction are not fully understood. Recent studies have shown that fluid flow during dynamic compression of cartilage explants can stimulate proteoglycan and protein synthesis. In this study, we examined the effect of deformations of cell and extracellular matrix on chondrocyte biosynthesis. We used tissue shear loading, since tissue shear causes little volumetric deformation and can thereby decouple fluid flow from cell and matrix deformation. Shear loading was applied over a wide range of frequencies, 0.01-1.0 Hz, using 1-3% sinusoidal shear strain amplitudes, and the resulting proteoglycan and protein syntheses were measured using radiolabel incorporation. In addition, quantitative autoradiography was used to investigate spatial variations in matrix biosynthesis and to correlate these variations with the spatial profiles of biophysical stimuli. Our data show that tissue shear loading at 1-3% strain amplitude stimulated the synthesis of protein by approximately 50% and proteoglycans by approximately 25% at frequencies between 0.01 and 1.0 Hz. The relatively uniform patterns of biosynthesis in the radial and vertical directions within cylindrical explants revealed by autoradiography suggest that the stimulatory effect was associated with the relatively uniform deformation caused by simple shear loading. These results suggest that chondrocytes can respond to tissue shear stress-initiated pathways for the production of collagen and proteoglycan, which include deformation of cells and pericellular matrix, even in the absence of macroscopic tissue-level fluid flow.

Analysis of Variance↗
PubMed2004

An improved method for the synthesis of [closo-B12(OH)12]-2.

The dicesium salt of the icosahedral borane anion dodecahydroxy-closo-dodecaborate(2-), closo-Cs(2)B(12)(OH)(12), Cs(2)4, was prepared using an improved synthetic pathway. Heating cesium dodecahydro-closo-dodecaborate, closo-Cs(2)B(12)H(12), Cs(2)1, with 30% hydrogen peroxide added in successive increments at 105-110 degrees C provided Cs(2)4 in 95% yield. Reaction progress was monitored using (1)H-decoupled (11)B NMR while (17)O NMR provides the most reliable way to detect the presence of peroxides in the reaction solution. The reaction may be safely increased in scale to afford Cs(2)4 in multigram quantities.

Journal Article↗
PubMed1992

Carbon 13 NMR study of glycogen metabolism in the baboon liver in vivo.

In vivo glycogen metabolism was investigated at 2 Tesla by 13C NMR in the baboon liver. Two concentric surface coils were used for 13C observation and proton decoupling, respectively. Spectra were acquired in 2 to 10 minutes with a 60 ms repetition time. After 3 hours of glucose infusion in the 48 hr fasted animal, 3 g of 99%-enriched [1-13C]glucose were injected. The distribution of the label on C-1 and also C-2, C-5 and C-6 of glycogen indicated 65% and 35% contributions of the direct and indirect pathways to glycogen synthesis from glucose, respectively. The results show that hepatic metabolic pathways and rates can be followed in vivo in large animals by 13C NMR at 2 Tesla.

Animals↗
PubMedDate not supplied

In vivo 1H, 31P-[1H] and 13C-[1H] magnetic resonance spectroscopy of malignant histiocytoma and skeletal muscle tissue in man.

Human tumor and skeletal muscle tissue was studied by means of in vivo 1H, 31P, and 13C MRS. The examinations were performed with a 1.5 T whole-body MR scanner equipped with a second RF system. Localized 1H and broadband proton-decoupled 31P and 13C MR spectra were obtained in measurement times of 5, 10 and 33 min, respectively, from a malignant fibrous histiocytoma in a patient and from gastrocnemius muscle tissue in healthy volunteers. Proton decoupling enhanced the sensitivity (via the nuclear Overhauser effect) and the information available from in vivo 31P and 13C MR spectra significantly. The most information was obtained from 1H-decoupled 31P spectra. Observation of more than one spin species allows peak assignments to be verified mutually. The spectral data of the histiocytoma differ largely from that of muscle tissue and show a tumor with elevated pH value, normal level of nucleoside 5'-triphosphates, and high level of compounds involved in phospholipid turnover. The multinuclear in vivo MRS experiment may allow the non-invasive observation of almost the complete pathway of phospholipid synthesis and degradation in intact human tissue.

Histiocytoma, Benign Fibrous↗
PubMed1998

Catalytic mechanism of Kdo8P synthase: transient kinetic studies and evaluation of a putative reaction intermediate.

The mechanistic pathway for the reaction catalyzed by Kdo8P synthase has been investigated, and the cyclic bisphosphate 2 has been examined as a putative reaction intermediate. Two parallel approaches were used: (1) chemical synthesis of 2 and evaluation as an alternate substrate for the enzyme and (2) transient kinetic studies using rapid chemical quench methodology to provide direct observation and characterization of putative intermediate(s) during enzyme catalysis. The putative cyclic bisphosphate intermediate 2, possessing the stereochemistry of the beta-pyranose form, was synthesized and evaluated as a substrate and as an inhibitor of Kdo8P synthase. The substrate activity was examined by monitoring the release of anomeric phosphate over time using proton-decoupled 31P NMR spectroscopy. A very similar time course for the formation of inorganic phosphate was found in each experiment and the corresponding control experiment; i.e., no enzyme-catalyzed acceleration in the anomeric phosphate hydrolysis was detected. It was found however that 2 binds to the enzyme and is a competitive inhibitor with respect to phosphoenolpyruvate binding, having a Ki value of 35 microM. In a parallel study, we have performed single-turnover rapid chemical quench experiments to examine both the forward and reverse directions to identify a putative enzyme intermediate(s). Our results clearly demonstrate that the cyclic bisphosphate intermediate 2 does not accumulate under single-enzyme turnover conditions. This observation, coupled with the results obtained through the evaluation of synthetic 2 as a substrate, strongly suggests that the Kdo8P synthase catalytic pathway does not involve the formation of 2 as a reaction intermediate. Taken together, these combined results support the original hypothesis [Hedstrom, L., and Abeles, R. H. (1988) Biochem. Biophys. Res. Commun. 157, 816-820], which suggests a reaction pathway involving an acyclic bisphosphate intermediate 1.

Aldehyde-Lyases↗
PubMed2026

Integrative multi-omics analysis reveals lipid/metabolite dysregulation and temporal decoupling in disease progression.

Our study presents and applies a metabolomics-driven multi-omics integration strategy to elucidate dynamic pathway interactions during disease progression. We analyzed longitudinal metabolomics datasets from a Duchenne muscular dystrophy (DMD) mouse model (6-30 weeks) and an acute Bothrops asper envenomation model (1-24 h) to contrast chronic versus acute inflammation. In the DMD model, we predicted phased cross-talk between sphingolipid metabolism and neurotrophin signaling: an early proteomic surge followed by lipid-mediated amplification and a late convergence at the protein level. Arginine and proline metabolism exhibited early metabolite accumulation preceding delayed inferred protein changes, consistent with impaired nitric oxide synthesis and argininemia-like effect. We also predicted late-stage activation of the AGE-RAGE pathway in DMD, likely triggered by ceramide buildup, and an autophagy-related lipid metabolic shift at mid-stage. In the envenomation model, tryptophan-kynurenine and nicotinamide pathways for NAD⁺ biosynthesis were rapidly perturbed at the metabolite level (1-3 h) but induced corresponding predicted enzymes only by 24 h. Thyroid hormone signaling showed an early coupling of substrate availability (tyrosine surge at 1 h) with predicted stress-response proteins and a second, delayed wave of inferred transcriptional regulators at 24 h. Acute envenomation also triggered immediate glycine/serine utilization possibly for antioxidant defense and glycerophospholipid breakdown (via phospholipase A₂), whereas chronic DMD showed sustained glycine/serine engagement and inferred, unresolved phospholipid perturbation without protein-level compensation, which may result from chronic oxidative stress. Overall, our integrative analysis revealed time-specific, multi-layer molecular perturbations distinguishing acute toxin injury from chronic muscle degeneration. Key metabolic control points (ceramide accumulation, arginine flux diversion, autophagy-lipid cross-talk, NAD⁺ salvage timing) were identified, highlighting potential targets for stage-specific therapeutic or nutritional interventions.

Animals↗
PubMed2002

Identification of novel hemes generated by heme A synthase: evidence for two successive monooxygenase reactions.

Heme A, an obligatory cofactor in eukaryotic cytochrome c oxidase, is produced from heme B (protoheme) via two enzymatic reactions catalyzed by heme O synthase and heme A synthase. Heme O synthase is responsible for the addition of a farnesyl moiety, while heme A synthase catalyzes the oxidation of a methyl substituent to an aldehyde. We have cloned the heme O synthase and heme A synthase genes from Bacillus subtilis (ctaB and ctaA) and overexpressed them in Escherichia coli to probe the oxidative mechanism of heme A synthase. Because E. coli does not naturally produce or utilize heme A, this strategy effectively decoupled heme A biosynthesis from the native electron transfer pathway and heme A transport, allowing us to observe two previously unidentified hemes. We utilized HPLC, UV/visible spectroscopy, and tandem mass spectrometry to identify these novel hemes as derivatives of heme O containing an alcohol or a carboxylate moiety at position C8 on pyrrole ring D. We interpret these derivatives to be the putative alcohol intermediate and an overoxidized byproduct of heme A synthase. Because we have shown that all hemes produced by heme A synthase require O(2) for their synthesis, we propose that heme A synthase catalyzes the oxidation of the C8 methyl to an aldehyde group via two discrete monooxygenase reactions.

Alkyl and Aryl Transferases↗
PubMed2026

Mitochondrial dysfunction in muscle cells induced by snoring vibrations.

Snoring-related vibrations have been proposed as a pathogenic factor contributing to upper airway muscle dysfunction in patients with obstructive sleep apnea (OSA). To investigate whether exposure to snoring vibration is linked to muscle weakness, we used an in vitro vibration model to examine its effects on mitochondrial homeostasis in L6 muscle cells at 8, 12, 24, and 48 h. The findings were then compared with mitochondrial alterations in the upper airway muscles from snorers and patients with OSA. Proteomic analysis of L6 myoblasts revealed extensive remodeling of the mitochondrial proteome at 8 h, affecting pathways involved in oxidative phosphorylation, protein import, ribosome biogenesis, and RNA processing. Respiratory chain remodeling was subunit-specific, with increased abundance of selected components of Complexes I, IV, and V, including NDUFS4, COX5A, and ATP5PD. However, reductions in spliceosome-associated factors, such as SRSF2 and DDX46, along with alterations in mitochondrial ribosomal proteins, indicated impaired RNA processing and protein synthesis. Furthermore, both proteomic and transcriptomic analyses revealed activation of a mechanosensing-mechanotransduction axis, with early upregulation of integrin subunits and mechanosensitive ion channels, followed by transient activation of focal adhesion signaling. Despite transcriptional upregulation of selected Complex IV subunits Cox5a and Cox6a2, this response was accompanied by accumulation of unspliced pre-mRNA, indicating impaired RNA processing efficiency and a decoupling between transcript and protein levels. Real-time Seahorse assay revealed a collapse of mitochondrial respiration and glycolytic reserve at 8 h. Although mitochondrial oxygen consumption recovered after 48 h, the ability to dynamically upregulate glycolysis remained impaired. In patients, muscle capillarization was impaired, COX activity was reduced, and mitochondrial organization was disrupted. Moreover, transcription of Complex IV subunits COX5A and COX6A2 was, as in vibrated L6 cells, upregulated, suggesting a mismatch between transcript levels and protein expression. We conclude that snoring-induced vibrations are an unrecognized stressor that disrupts mitochondrial homeostasis in muscle by impairing RNA processing, protein synthesis, and mechanotransduction-driven mitochondrial remodeling, leading to transcript-protein uncoupling and likely muscle dysfunction.

Humans↗
PubMed2004

Observation of calcium-dependent unidirectional rotational motion in recombinant photosynthetic F1-ATPase molecules.

ATP hydrolysis and synthesis by the F(0)F(1)-ATP synthase are coupled to proton translocation across the membrane in the presence of magnesium. Calcium is known, however, to disrupt this coupling in the photosynthetic enzyme in a unique way: it does not support ATP synthesis, and CaATP hydrolysis is decoupled from any proton translocation, but the membrane does not become leaky to protons. Understanding the molecular basis of these calcium-dependent effects can shed light on the as yet unclear mechanism of coupling between proton transport and rotational catalysis. We show here, using an actin filament gamma-rotation assay, that CaATP is capable of sustaining rotational motion in a highly active hybrid photosynthetic F(1)-ATPase consisting of alpha and beta subunits from Rhodospirillum rubrum and gamma subunit from spinach chloroplasts (alpha(R)(3)beta(R)(3)gamma(C)). The rotation was found to be similar to that induced by MgATP in Escherichia coli F(1)-ATPase molecules. Our results suggest a possible long range pathway that enables the bound CaATP to induce full rotational motion of gamma but might block transmission of this rotational motion into proton translocation by the F(0) part of the ATP synthase.

Actins↗
PubMed2001

Bordetella pertussis autoregulates pertussis toxin production through the metabolism of cysteine.

Pertussis toxin (Ptx) expression and secretion in Bordetella pertussis are regulated by a two-component signal transduction system encoded by the bvg regulatory locus. However, it is not known whether the metabolic pathways and growth state of the bacterium influence synthesis and secretion of Ptx and other virulence factors. We have observed a reduction in the concentration of Ptx per optical density unit midway in fermentation. Studies were conducted to identify possible factors causing this reduction and to develop culture conditions that optimize Ptx expression. Medium reconstitution experiments demonstrated that spent medium and a fraction of this medium containing components with a molecular weight of <3,000 inhibited the production of Ptx. A complete flux analysis of the intermediate metabolism of B. pertussis revealed that the sulfur-containing amino acids methionine and cysteine and the organic acid pyruvate accumulated in the media. In fermentation, a large amount of internal sulfate (SO4(2-)) was observed in early stage growth, followed by a rapid decrease as the cells entered into logarithmic growth. This loss was later followed by the accumulation of large quantities of SO4(2-) into the media in late-stage fermentation. Release of SO4(2-) into the media by the cells signaled the decoupling of cell growth and Ptx production. Under conditions that limited cysteine, a fivefold increase in Ptx production was observed. Addition of barium chloride (BaCl2) to the culture further increased Ptx yield. Our results suggest that B. pertussis is capable of autoregulating the activity of the bvg regulon through its metabolism of cysteine. Reduction of the amount of cysteine in the media results in prolonged vir expression due to the absence of the negative inhibitor SO4(2-). Therefore, the combined presence and metabolism of cysteine may be an important mechanism in the pathogenesis of B. pertussis.

Adenylate Cyclase Toxin↗
PubMed2005

Template-aluminosilicate structures at the early stages of zeolite ZSM-5 formation. A combined preparative, solid-state NMR, and computational study.

Species at three stages in the self-assembly of zeolite ZSM-5 have been studied with one- and two-dimensional magic-angle-spinning 13C, 27Al, 29Si, and 1H NMR spectroscopy and compared with the earlier proposed structures: (1) precursor species containing 33-36 T sites around a tetrapropylammonium (TPA) cation, (2) nanoslabs consisting of a flat 4 x 3 array of such precursors, and (3) the final TPA-ZSM-5 zeolite. Synthesis was carried out in D2O to suppress the water and silanol protons. Under such conditions, the effective Si-H and Al-H distances measured with 29Si-{1H} and 27Al-{1H} rotational echo double resonance (REDOR) reflect the interactions between TPA cations and the surrounding aluminosilica. The 29Si-{1H} REDOR curves for Q4-type silicon atoms at the three mentioned stages are closely similar, as well as the observed 27Al-1H REDOR curve for the precursor species compared to that for the TPA-ZSM-5. This indicates that in addition to externally attached TPA, there is also internal TPA already incorporated at an early stage into the aluminosilicate in a similar way as in the final zeolite, in accordance with the earlier proposed MFI self-assembly pathway (Kirschhock et al. Angew. Chem. Int. Ed. 2001, 40, 2637). However, the effective distances extracted from the initial REDOR curvatures are significantly (10-15%) larger than those computed for the model. Since there is no temperature effect, we tentatively assign this difference to a reduction of the 29Si-1H and 27Al-1H interactions by multispin decoherence effects or self-decoupling caused by proton spin diffusion. By assuming the computed model distances and fitting Anderson-Weiss curves to the observed REDOR data, we obtain similar "decoherence times" in the order of 0.1 ms. The observed 29Si-{1H} REDOR dephasing for the Q3 sites in the precursors is significantly faster than that for the Q4 sites. This is tentatively ascribed to a partial deuteron-proton back exchange at the silanol positions.

Journal Article↗