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PubMed1997

Surface modifications of titanium in calcium-ion-containing solutions.

The surface of titanium was modified in calcium-ion-containing solutions to improve bone conductivity. Three kinds of aqueous solutions for the modification were prepared using calcium nitrate, calcium chloride, and calcium oxide. The pH values of the solutions were 3.9, 7.4, and 12.6, respectively. At first, anatase powder was immersed in the solutions of 7 days to confirm the effect of the solutions on the modification. As a result, calcium titanate was formed on the anatase powder, indicating that the titanium surface was possibly modified by the solutions. Titanium plates were then immersed in the solutions at ambient temperature for 7 days, washed by deionized water, and dried. X-ray photo-electron spectroscopy of surface-modified titanium revealed that the surface-modified layer contained calcium hydroxide and/or calcium titanate. The surface-modified layer in which titanium was modified was thickest in this order: calcium oxide, calcium chloride, and calcium nitrate solutions. Apatite was formed on the surface-modified titanium in Hanks' solution while apatite was undetected on unmodified titanium. Therefore, the surface modification of titanium may improve bone conductivity. The amount of apatite corresponded to the thickness of the surface-modified layer and the amount of calcium in the layer.

Apatites↗

PubMed1996

Inhibition of ADP-induced platelet activation by 7-chloro-4-nitrobenz-2-oxa-1,3-diazole: covalent modification of aggregin, a putative ADP receptor.

ADP-induced platelet responses play an important role in the maintenance of hemostasis. There has been disagreement concerning the identity of an ADP receptor on the platelet surface. The chemical structure of 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD-CI) shows considerable resemblance to that of the adenine moiety of adenine-based nucleotides. The reagent has been previously used by other investigators as an affinity label for adenine nucleotide-requiring enzymes, such as mitochondrial ATPase and the catalytic subunit of cAMP-dependent protein kinase. Since ADP-induced platelet responses depend on the binding of ADP to its receptor, we investigated the effect on ADP-induced platelet responses and the nature of ADP-binding protein modified by NBD-CI. NBD-CI inhibited ADP-induced shape change and aggregation of platelets in platelet-rich plasma in a concentration- and time-dependent manner. NBD-CI also inhibited ADP-induced shape change, aggregation, exposure of fibrinogen binding sites, secretion, and calcium mobilization in washed platelets. NBD-CI did not act as an agonist for platelet shape change and aggregation. Covalent modification of platelets by NBD-CI blocked the ability of ADP to antagonize the increase in intracellular levels of cAMP mediated by iloprost (a stable analogue of prostaglandin I2). NBD-CI was quite specific in inhibiting platelet aggregation by those agonists, e.g., ADP, collagen, and U44619 (a thromboxane mimetic), that completely or partially depend on the binding of ADP to its receptor. Autoradiogram of the gel obtained by SDS-PAGE of solubilized platelets modified by [14C]-NBD-CI showed the presence of a predominant radiolabeled protein band at 100 kDa corresponding to aggregin, a putative ADP receptor. The intensity of this band was considerably decreased when platelets were either preincubated with ADP and ATP or covalently modified by a sulfhydryl group modifying reagent before modification by [14C]-NBD-CI. These results (1) indicate that covalent modification of aggregin by NBD-CI contributed to loss of the ADP-induced platelet responses, and (2) suggest that there is a sulfhydryl group in the ADP-binding domain of aggregin.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed1998

Drosophila acetylcholinesterase: effect of post-translational [correction of post-traductional] modifications on the production in the baculovirus system and substrate metabolization.

Acetylcholinesterase cDNAs from Drosophila melanogaster modified on its primary sequence were cloned into baculovirus and were expressed in Sf9 cells with the aim to identify a mutant form that produces the enzyme at a high level. Directed mutagenesis was used in order to independently knockout different sites of post-translational modifications: exchange of the C-terminal hydrophobic peptide for a glycolipid molecule, dimerization by disulfide bridge, N-linked glycosylation at the five accessible sites, and subunit formation by proteolytic cleavage of a hydrophilic peptide found in the precursor. Another mutation involved the elimination of a free cysteine in the mature protein. All mutations involving post-translational modifications resulted in lower recoveries, suggesting that they are useful for maintaining high amounts of protein in the synapse. By contrast, elimination of a free cysteine in the mature protein permitted an increase in the level of production of the enzyme. These mutations did not affect specific activity of the enzyme at substrate concentrations ranging from 3 microM to 200 mM, suggesting that activation and inhibition of the enzyme activity does not originate from a polymorphism in post-translational modifications.

Acetylcholine↗

PubMed1998

Physico-chemical modification of food proteins: food emulsions.

Physico-chemical protein modification involved in food processing is used for "engineering" the structure-property relationship of foods. The three main tools used for protein modification are food formulation, mechanical and thermal (heating/cooling) treatments. They correspond to the main stages of all food technologies. Food structural design is based upon incompatibility and complexing of food biopolymers as well as upon fundamental features of physico-chemical properties of biphasic aqueous systems. Some examples of functional biopolymer modification are considered in systems such as meat extenders, fat replacers, ice cream mixes and wheat flour doughs.

Chemical Phenomena↗

PubMed1983

Training community-based, Asian-American mental health personnel in behavior modification.

Sixteen Asian-American and Pacific Island mental health professionals received 10 weekly, 2-hour training sessions on behavior modification and its application, in particular, to Asian-American clients. A three-fold assessment of the training results revealed: a) a significant increase in knowledge of behavior modification principles, b) a significant increase in ability to accomplish a behavioral analysis and behavioral treatment plan, and c) a significant increase in one of three attitudes toward behavior modification: oriented activity. In general, the training was rated highly and, perhaps more importantly, was viewed as having relevance for this particular minority population which often under utilizes mental health services. The training model and needs for further consultation and supervision were discussed.

Asian↗

PubMed2001

Modification and inhibition of vancomycin group antibiotics by formaldehyde and acetaldehyde.

It is shown that several vancomycin group antibiotics (vancomycin, eremomycin, and avoparcin) undergo spontaneous chemical modifications when kept at room temperature at neutral pH in aqueous solutions containing traces of formaldehyde or acetaldehyde. This chemical modification predominantly results in a mass increase of 12 Da in the reaction with formaldehyde and 26 Da in the case of acetaldehyde. By using tandem mass spectrometry the modification can unambiguously be identified as originating from the formation of a ring-closed 4-imidazolidinone moiety at the N-terminus of the glycopeptide antibiotics, that is, near the receptor binding pocket of the glycopeptide antibiotics. Bioaffinity mass spectrometry shows that this ring-closure results in a dramatically decreased affinity for the peptidoglycan-mimicking D-alanyl-D-alanine receptor. Additionally, in vitro inhibition measurements on two different strains of bacteria have revealed that the modified antibiotics display reduced antibacterial activity. The ring-closure is also shown to have a dissociative effect on the dimerization of the vancomycin-analogue eremomycin. The spontaneous reaction of vancomycin with formaldehyde or acetaldehyde may have implications not only for the clinical use of this class of antibiotics, but also for the effectiveness of these antibiotics when they are used in chiral separation chromatography or capillary electrophoresis.

Acetaldehyde↗

PubMed2000

Changes in interfacial behaviour, emulsifying and foaming properties of faba bean legumin after modification with dimethylsuberimidate.

The effect of a rising rigidity and surface hydrophobicity of the 11S storage protein from faba beans--legumin--induced by chemical modification with dimethylsuberimidate (DMS) on some surface functional properties was studied. Short-time adsorption kinetics using a droplet-volume tensiometer, pressure transformation and desorption behaviour of monolayer using a film balance, and emulsifying and foaming properties were determined to characterize surface activity and interfacial film forming behaviour. Tensio-active properties at the air-water interface, i.e. decay in surface tension and pressure transformation in monolayer, were improved by modification. However, a decrease in emulsifying activity, foam capacity and foam expansion after modification of the legumin points to an overall deterioration of energy-induced film forming behaviour. The results support the view that surface activity is generally governed more by molecular flexibility than by surface hydrophobicity.

Dimethyl Suberimidate↗

PubMed2005

Chromatin modifications as targets for new anticancer drugs.

Chromatin proteins undergo diverse posttranslational modifications, esp. acetylation and methylation, that contribute to the control of transcriptional processes. The result of these modifications in its various states is called the histone code. This review presents an overview of those modifications of chromatin proteins that affect the side chains of lysines and arginines and define variations of the chromatin acetylome and methylome. The relevant enzymes are presented and the feasibility to influence their activity by inhibition or activation is discussed. The manipulation of these enzymes is an exciting strategy towards an increased understanding of their role in the functionality of a cell. Additionally, this may lead to new approaches for the treatment of diseases that are based on a dysregulation of transcription, especially cancer.

Acetylation↗

PubMed2005

Recent innovations in tissue-specific gene modifications in the mouse.

Annotating the functions of individual genes in in vivo contexts has become the primary task of mouse genetics in the post-genome era. In addition to conventional approaches using transgenic technologies and gene targeting, the recent development of conditional gene modification techniques has opened novel opportunities for elucidating gene function at the level of the whole mouse to individual tissues or cell types. Tissue-specific gene modifications in the mouse have been made possible using site-specific DNA recombinases and conditional alleles. Recent innovations in this basic technology have facilitated new types of experiments, revealing novel insights into mammalian embryology. In this review, we focus on these recent innovations and new technical issues that impact the success of these conditional gene modification approaches.

Animals↗

PubMed2002

Protein modification during anti-viral heat-treatment bioprocessing of factor VIII concentrates, factor IX concentrates, and model proteins in the presence of sucrose.

To ensure the optimal safety of plasma derived and new generation recombinant proteins, heat treatment is customarily applied in the manufacturing of such biopharmaceuticals as a means of viral inactivation. In subjecting proteins to anti-viral heat-treatment it is necessary to use high concentrations of thermostabilizing excipients to prevent protein damage, and it is therefore imperative that the correct balance between bioprocessing conditions, maintenance of protein integrity and virus kill is found. In this study we have utilized model proteins (lysozyme, fetuin, and human serum albumin) and plasma-derived therapeutic proteins (factor VIII and factor IX) to investigate the protein modifications that occur during anti-viral heat treatment. Specifically, we investigated the relationship between bioprocessing conditions and the type and extent of protein modification under a variety of industrially relevant wet and lyophilized heat treatments using sucrose as a thermostabilizing agent. Heat treatment led to the formation of disulfide crosslinks and aggregates in proteins containing free cysteine residues. Terminal oligosaccharide sialic acid residues were hydrolyzed from the glycan moieties of glycoproteins during anti-viral heat treatment. Heat treatment promoted sucrose hydrolysis to yield glucose and fructose, leading, in turn, to the glycation of lysine amino groups in those proteins containing di-lysine motifs. During extended hear treatments, 1,2-dicarbonyl type advanced glycation end-products were also formed. Glycation-type modifications were more prevalent in wet heat-treated protein formulations.

Disinfection↗

PubMed2004

Increased single-nucleotide discrimination of PCR by primer probes bearing hydrophobic 4'C modifications.

We report on significantly increased selectivity of real-time PCR through employment of primer probes that bear hydrophobic 4'C modifications at the 3'-terminal nucleotide. The primer probes were designed to bind the target sequences in such a way that the 3'-terminal nucleotide defines whether a matched or a single mismatched basepair is present depending on the respective target sequence. Several commercially available thermostable DNA polymerases belonging to different DNA polymerase families were tested for their efficacy in discriminating between PCR amplification of matched substrates and duplexes that contain a single mismatch. It turned out that, depending on the 4'C modification and the employed DNA polymerase, significantly increased differentiation between single matches and mismatches could be observed with real-time PCR. The degrees of the observed effects varied with the employed 4'C modification and the sequence context studied. The system is robust enough to work faithfully under several buffer conditions. Our approach should be useful for the direct diagnosis of single nucleotide variations within genes, like single nucleotide polymorphisms or mutations, by PCR without the need for further time- and cost-intensive post-PCR analysis.

DNA Primers↗

PubMed2006

A second metalloid Ga18 cluster and its topological similarity to the high-pressure Ga-II modification.

The topology of many modifications of elemental gallium is reflected in the large variety of metalloid Ga clusters that have been isolated as intermediates on the way from the metastable molecular GaX species (X=Cl, Br, I) by means of disproportionation to the bulk metal. Herein, we report the synthesis and characterization of the first metalloid cluster anion [Ga(18)(PtBu(2))(10)](3-) with the singular core topology that resembles the gallium high-pressure modification Ga-II. The stabilization of the cluster anion through ion-pair contacts with a chainlike "Li(4)Br(2) backbone" is discussed. Furthermore, the compound is discussed in context of the other metalloid clusters Ga(18)R(8) and Ga(22)R(8) (R=SitBu(3)) and their structural relation to the elemental modifications Ga-III and beta-Ga, respectively.

Journal Article↗

PubMed2026

Timing matters: Impact of covalent BTK inhibitor dose modifications on outcomes in chronic lymphocytic leukemia/small lymphocytic leukemia-A 7-year real-world study.

BACKGROUND: Covalent BTK inhibitors (cBTKis) are the cornerstone of chronic lymphocytic leukemia (CLL)/small lymphocytic leukemia (SLL) therapy, yet real-world data on dose modifications and their differential impact on long-term outcomes remain incompletely defined. This study investigated the incidence, timing, and the effectiveness of drug switching in a real-world CLL cohort. METHODS: In this 7-year retrospective real-world study, 324 CLL/SLL patients treated at a specialized Shanghai outpatient clinic (April 2018-April 2025; median follow-up, 42 months) were analyzed. Dose modifications were classified as dose interruption (DI) or dose reduction (DR). Their prognostic impact on progression-free (PFS) and overall survival (OS) was assessed by Kaplan-Meier analysis and multivariate Cox regression. RESULTS: The 42-month PFS rate was 70.2%. Of 324 patients, 229 (70.7%) experienced dose reductions or interruptions; infections were the predominant cause (61.9%). The full-dose (FD) group (n = 90) demonstrated superior 4-year PFS (93% vs. 58%, p < .001) and OS (98% vs. 76%, p = .007). Early modifications (0-3 months) were independent predictors of inferior PFS (hazard ratio [HR], 3.93, p = .008) and OS (HR, 3.29, p = .014). Prolonged DI (>14 days) was associated with inferior PFS (HR, 2.64) and OS (HR, 2.15), whereas DR and short DI (≤14 days) had negligible impact. Early (0-3 months) prolonged DI was devastating (3-year PFS, 41.2%; HR, 3.84, p < .001). cBTKi switching (n = 82; 100% nonprogression-driven) shortened DI (median, 6 vs. 14 days) and was independently associated with superior OS (HR, 0.34, p = .018) and PFS (HR, 0.36, p = .022). CONCLUSIONS: Early prolonged DI is the dominant adverse prognostic factor in cBTKi-treated CLL/SLL. Proactive switching minimizes treatment gaps and improves survival, supporting a timing-aware, DI- versus DR-informed approach to dose management.

Humans↗

PubMed1983

Modifications in the laminar organization of peptide-like immunoreactivity in the anuran optic tectum following retinal deafferentation.

Substance P (SP)-, leucine-enkephalin (LENK)-, cholecystokinin octapeptide (CCK8)-, bombesin (BOM)-, and avian pancreatic polypeptide (APP)-like immunoreactivities were analyzed in the optic tectum of Rana pipiens 5-99 days after unilateral eye enucleation, or optic nerve ligation, by means of the peroxidase-antiperoxidase and indirect fluorescence single and double labeling methods. The normal pattern (Kuljis and Karten, '81, '82c) of peptide-like immunoreactivity was observed ipsilaterally to the operation. Contralateral deafferented tectae displayed conspicuous modifications in the normal pattern of peptide-like immunoreactivity unique to each of the substances studied. The modifications of peptide-like immunoreactivity observed varied depending both on the survival time and on the particular peptide analyzed, with either increment or diminution or disappearance--or combinations thereof--in the staining intensity of some of the peptide-positive bands in the superficial one-third (superficial neuropil) of the tectum. The onset of these changes is detectable immunocytochemically between the sixth and tenth day following deafferentation. By 2-4 weeks full expression of the long-term changes is reached with no apparent further modification up to the 99th postoperative day. The rapid onset of these phenomena suggests the existence of a previously unrecognized retinal ganglion cell terminal peptidergic contribution to the tectum and/or rapid transsynaptic effects. The former possibility is suggested by recent observations demonstrating peptide-like immunoreactivity for SP, LENK, CCK8 and BOM in the retinal stump of ligated optic nerves (Kuljis and Karten, '82b). The fact that no vertebrate retinal ganglion cells have been shown to contain any of these peptides (Brecha et al., '79; Famiglietti et al., '80; Eldred and Karten, '81; Karten et al., '82), however, argues against the possibility of a retinal terminal contribution to peptide-like immunoreactivity in the tectum and suggests that transsynaptic phenomena are involved.

Animals↗

PubMed1988

Modification of tumor cells by a low dose of Newcastle disease virus. Augmentation of the tumor-specific T cell response in the absence of an anti-viral response.

The present study elucidates the mechanism whereby viral xenogenization of highly metastatic ESb lymphoid tumor cells increases tumor immunogenicity and syngeneic tumor-specific T cell responses in comparison to nonmodified tumor cells. It was found that the frequency of cytotoxic T lymphocytes specific for the Esb tumor-associated transplantation antigen (TATA) and the cytotoxic anti-tumor activity in bulk cultures of immune spleen cells were significantly increased (by factor 3 and 25, respectively) when using virus-modified tumor cells. An amplified response was observed both in vivo and in vitro which might explain the demonstrated effectiveness of this approach for postoperative immunotherapy of ESb metastases. For the stimulation of tumor-specific cytolytic T lymphocytes (CTL) the ESb tumor cells which are highly metastatic were infected with an avirulent strain of the paramyxovirus Newcastle Disease Virus (NDV). Infection of ESb cells with low amounts of NDV was sufficient to lead to an increase in cytolytic activity of tumor-specific CTL after sensitization in vivo and restimulation in vitro. In a sensitive limiting dilution mixed leukocyte-tumor cell microculture system the direct effect of viral modification on the frequency and specificity of CTL was investigated. The number of ESb-specific CTL per spleen could be raised from about 3300 (without modification) to 9100 by both in vivo and in vitro application of ESb-NDV. One application of ESb-NDV (in vivo or in vitro) increased the number of CTL to 4900 and 4600, respectively. In split-type experiments it could be shown at the clonal level that viral modification did not alter the specificity of ESb-specific CTL.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Fetal thymocyte potential for T cell receptor V gamma 3-J gamma 1 junctional modification.

Junctional modifications of T cell receptor (TcR) and immunoglobulin (Ig) gene joining regions provide great diversity to respective protein repertoires. The addition of non-germ-line-encoded nucleotides (N-regions) in the V-J gamma junction is one such modification which is developmentally regulated, rarely evident in the fetal animal, but common in the adult. A question has recently arisen as to whether developmentally patterned N-region additions in V-J gamma joins are a reflection of T cell progenitors which are committed to particular types of rearrangement prior to the event, or of changing environmental influences on uncommitted cell populations. To address this question with regard to the V gamma 3-J gamma 1 join, T cells were examined in the fetal thymic organ culture (FTOC), a system with which the environment of early progenitor cells could be deliberately altered. At various times following FTOC initiation, cells were isolated for examination by the polymerase chain reaction, cloning and sequencing. V gamma 3-J gamma 1 sequences within genomic DNA as well as cDNA were evaluated. Data from these studies revealed frequent N-region additions within V-J gamma joins among day 14 fetal thymocyte populations, a situation dissimilar from that in vivo. Also dissimilar from the in vivo situation was the degree of exonuclease activity evident in FTOC. The canonical V gamma 3-J gamma 1 join (a frequent junction lacking N-region addition) was recognized in all experiments, but was least common among DNA versus cDNA sequences. Results illustrate that early progenitor cell populations are not programmed to exclude junctional modifications from V gamma 3-J gamma 1 joins.

Animals↗

PubMed2005

On the surface modification of microchannels for microcapillary electrophoresis chips.

This paper presents systematic investigation of the microchannel surface properties in microCE chips. Three popular materials for microCE chips, polydimethylsiloxane (PDMS), quartz, and glass, are used. The zeta potentials of these microchannels are calculated by measuring the EOF velocity to evaluate the surface properties after surface modification. The hydrophobic PDMS is usually plasma-treated for microCE applications. In this study, a new method using a high-throughput atmospheric plasma generator is adopted to treat the PDMS surface under atmospheric conditions. In this approach, the cost and time for surface treatment can be significantly reduced compared with the conventional vacuum plasma generator method. Experimental results indicate that new functional groups could be formed on the PDMS surface after treatment, resulting in a change in the surface property. The time-dependent surface property of the plasma-treated PDMS is then measured in terms of the zeta potential. Results show that the surface property will reach a stable condition after 1 h of plasma treatment. For glass CE chips, two new methods for changing the microchannel surface properties are developed. Instead of using complicated and time-consuming chemical silanization procedures for CE channel surface modification, two simple and reliable methods utilizing organic-based spin-on-glass and water-soluble acrylic resin are reported. The proposed method provides a fast batch process for controlling the surface properties of glass-based CE channels. The proposed methods are evaluated using PhiX-174 DNA maker separation. The experimental data show that the surface property is modified and separation efficiency greatly improved. In addition, the long-term stability of both coatings is verified in this study. The methods proposed in this study show potential as an excellent solution for glass-based microCE chip surface modification.

Bacteriophage phi X 174↗

PubMed2006

Permanent surface modification of polymeric capillary electrophoresis microchips for protein and peptide analysis.

Because of their surface heterogeneity, proteins readily adsorb on polymeric substrates via various interactions, which adversely affects the performance of polymeric microfluidic devices in electrophoresis-based protein/peptide analysis. Therefore, it is necessary to use surface modification techniques such as dynamic coating or more complicated permanent surface modification, which has broader application and better performance, to render the polymeric microchannels protein-resistant. This manuscript is a review of the surface chemistry of microfluidic devices used for electrophoretic separations of proteins and peptides. The structural complexity of proteins as it relates to adsorption is described, followed by a review of the mechanisms and structural characteristics of protein-resistant surfaces. Permanent surface modification techniques used in grafting protein-resistant materials onto the surfaces of electrophoresis microchannels fabricated from polymer substrates are summarized and successful examples are presented.

Electrophoresis, Capillary↗