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PubMed1988

Comparison of K-ABC performance between at-risk and normal preschool children.

This study examined differences in K-ABC performance between at-risk (n = 44) and normal (n = 49) preschool children. For the group at-risk, all of the mean global scores on the K-ABC clustered around a standard score of approximately 90. The normal group's mean scores were 15 to 21 standard-score points higher and clustered near 110. The results of t tests for independent samples indicated that the normal group's scores on both the global scales and K-ABC subtests were significantly higher than the at-risk group's scores in nearly every instance. Correlations among scores were consistent with previous findings for preschoolers on the K-ABC. For the normal group, correlations obtained among the global scales were nearly identical to those reported for the standardization sample. For the at-risk group, however, the correlation of .75 between Sequential processing and Achievement was higher than that (.58) between Simultaneous processing and Achievement.

Achievement↗

PubMed2001

ABC transporters and cholesterol metabolism.

ATP-binding cassette (ABC) proteins form a group of highly conserved cellular transmembrane transporters. Studies over the past year have implicated ABC transporters in cellular lipid trafficking processes. This notion has recently been confirmed and extended by the finding that the ABC transporter ABCA1 is a key regulator of high-density lipoprotein (HDL) metabolism and macrophage targeting to the RES or the vascular wall. Expression of a large number of ABC transporters in monocytes/macrophages and their regulation by cholesterol flux render these transporter molecules potentially critical players in chronic inflammatory diseases such as atherosclerosis.

ATP-Binding Cassette Transporters↗

PubMed1983

Application of dual pre-embedding stains for gonadotropins to pituitary cell monolayers with avidin-biotin (ABC) and peroxidase-antiperoxidase (PAP) complexes: light microscopic studies.

Double stains for gonadotropins and gonadotropin-releasing hormone were developed for fixed whole pituitary cells from cycling female rats. Monolayer cells were stimulated with [D-Lys6]GnRH, fixed in 2.5% glutaraldehyde, and then stained for luteinizing hormone (LH) (1:50,000-12 h) or follicle stimulating hormone (FSH) (1:60,000-12 h) and the avidin-biotin-peroxidase complex technique (ABC) with a jet-black substrate (nickel intensified diaminobenzidine-DAB). This was followed by a stain for the other gonadotropin with either ABC or peroxidase-antiperoxidase complex (PAP) techniques and amber (DAB) or red (3-amino-9-ethyl-carbazole) substrates. Additional monolayers were stimulated with biotinylated [D-Lys6]GnRH and stained with the ABC technique and the black (nickel-DAB) substrate. These monolayers were then stained immunocytochemically for LH or FSH with either ABC or PAP methods and orange or red substrates. The controls showed that the omission of the second primary antiserum abolished the stain indicating that the second staining solutions did not react with components in the first group. The addition of the second peroxidase substrate in sequence after the first stain indicated that no residual peroxidase activity remained from the first stain. Our tests also showed that saponin was not needed to aid reagent or antibody penetration. The dual stains demonstrated that 50-60% of the gonadotropes stored LH and FSH together, often in separate regions of the same cell. Some cells contained only one hormone (20-22%). The dual stains for GnRH and gonadotropins demonstrated that 80-90% of the GnRH bound cells are gonadotropes. These techniques allow a study of storage sites for multiple hormones in or on whole cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Applicability of ABC-ELISA and protein A-ELISA in serological diagnosis of cysticercosis.

Specific antibody test in serum and cerebrospinal fluid (CSF) is still the main mode of serological diagnosis of cysticercosis. Of different techniques of antibody test, enzyme-linked immunosorbent assay (micro-ELISA) has widely been applied. This study was undertaken to observe whether diagnostic capability can be improved by applying more sensitive techniques such as Protein A-ELISA and avidin biotin complex ELISA (ABC-ELISA). When evaluated using 115 sera of human cysticercosis, the antibody positive rates were not significantly improved in Protein A-ELISA (82.6%) and in ABC-ELISA (86.1%) than in micro-ELISA (81.7%). The specificities, evaluated in 165 sera from other diseases and normal controls, were significantly improved (88.5% by micro-ELISA, 93.3% by Protein A-ELISA and 93.8% by ABC-ELISA). Antibody levels (absorbance, abs.) in individual serum were correlated well (r = 0.83-0.86) each other. An actual benefit of Protein A-ELISA and ABC-ELISA was that they needed smaller amount of test sample.

Antibodies, Helminth↗

PubMed2001

The pleitropic drug ABC transporters from Saccharomyces cerevisiae.

The Saccharomyces cerevisiae genome contains 16 genes encoding full-size ABC transporters. Each comprises two nucleotide binding folds (NBF) alternating with transmembrane domains (TM). We have studied in detail three plasma membrane multidrug exporters: Pdr5p (TC3.A.1.205.1) and Snq2p (TC3.A.1.205.2) which share NBF-TM-NBF-TM topology as well as Yor1p (TC3.A.1.208.3) which exhibits the reciprocal TM-NBF-TM-NBF topology. The substrate specificity of Pdr5p, Snq2p and Yor1p are largely, but not totally, overlapping as shown by screening the growth inhibition by 349 toxic compounds of combinatorial deletants of these three ABC genes. Multiple deletion of 7 ABC genes (YOR1, SNQ2, PDR5, YCF1, PDR10, PDR11 and PDR15) and of two transcription activation factors (PDR1 and PDR3) renders the cell from 2 to 200 times more sensitive to numerous toxic coumpounds including antifungals used in agriculture or medicine. The use of the pdr1-3 activating mutation and when necessary of the PDR5 promoter in appropriate multideleted hosts allow high levels of expression of Pdr5p, Snq2p or Yor1 p. These overexpressed proteins exhibit ATPase activity in vitro and confer considerable multiple drug resistance in vivo. The latter property can be used for screening specific inhibitors of fungal and other ABC transporters.

ATP-Binding Cassette Transporters↗

PubMed2002

[Functional activity of ABC transporters (markers of multidrug resistance) in human colon adenocarcinoma and normal colonic mucosa].

Functional activity of multidrug resistance (MDR) markers (total activity of ABC-transporters, P-glycoprotein (Pgp) and multidrug resistance-associated protein (MRP) activities) in human colon adenocarcinoma and normal mucosa was examined. Functional activity of ABC-transporters was revealed in all colon tumors and in 70% of normal mucosa samples investigated. Expression of Pgp and MRP functional activity was determined in about 50% and 70% of colon tumors respectively. Pgp+MRP+ phenotype was determined in 36% of normal mucosa and adenocarcinoma samples. Expression of Pgp+MRP- phenotype was practically the same in normal mucosa and tumors (in 10 and 18% of samples respectively). Pgp-MRP+ phenotype was revealed two times more often in tumors than in mucosa--in 36 and 18% respectively. On the contrary, Pgp-MRP- phenotype was detected more rarely in tumors than in mucosa (in 10 and 36% of samples respectively). Transporters different from Pgp and MRP were also determined in some tumors and normal mucosa. At the patients with expression of Pgp function in normal mucosa the activity of the transporter was revealed in 25% of tumor samples only. On the contrary, at the patients with expression of MRP function in normal mucosa the activity of the transporter was revealed in 70% of tumor samples. At the patients with no expression of Pgp or MRP activity in normal mucosa the function of the transporters in tumors was determined in 60% and 70% of samples respectively. It is concluded that functional activity of various ABC-transporters (Pgp, MRP and other different from Pgp and MRP) is expressed in human colon adenocarcinoma; expression of ABC-transporters functional activity in normal mucosa does not predict MDR phenotype of the tumor.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2003

[Inhibition of ABC-transporter(s)' function in non-small cell lung cancer cells by platinum drugs].

With an account of the literature data that platinum drugs react with many cellular targets, including ATP and proteins, the authors suggested that disturbance of the function of energy-dependent ABC-transporters (markers of multidrug resistance, MDR) under the effect of platinum drugs could be a cause of increased efficacy of MDR agents (agents, MDR to which is developed by the classical mechanism) when used in combination with platinum drugs even in the treatment of multidrug resistant lung cancer. The cisplatin and carboplatin effect on accumulation of MDR doxorubicin in cells of non-small cell cancer was studied by flow cytometry with the use of biopsy specimens. The MDR phenotype of the tumors was determined by a change in doxorubicin intracellular accumulation under the action of the ABC-transporter(s)' inhibitors: verapamil and genistein (specific inhibitors of Pgp and MRP respectively) and sodium azide (an inhibitor of all energy-dependent ABC-transporters). The MDR phenotypes, i.e. Pgp-MRP+ or Pgp+MRP+, were detected in all the tumors investigated. Two types of changes in doxorubicin intracellular accumulation under the action of the inhibitors and the platinum drugs were shown: (a) an increase in doxorubicin cytoplasmic accumulation and (b) a change in subcellular distribution of the anthracycline (increased accumulation of doxorubicin in the cell nucleus and its higher binding to DNA). Cisplatin and carboplatin had an inhibitory effect on ABC-transporter(s) in all the tumors investigated but the effect of carboplatin was less pronounced. It was concluded that cisplatin and carboplatin stimulation of doxorubicin intracellular accumulation, as well as a change in subcellular distribution of the anthracycline under the action of the platinum drugs (increased doxorubicin accumulation in the cell nucleus) in multidrug resistant lung tumors could be at least partly explained by inhibition of the MDR transporter(s)' function. The results could provide a basis for the use of the sequential combination cisplatin (or carboplatin)-->doxorubicin in the treatment of multidrug resistant lung cancer.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2005

[Transcriptional repression of pltZ on pyoluteorin ABC transporter of Pseudomonas sp. M18].

A pltZ gene involved in negatively regulating pyoluteorin (Plt) biosynthesis, and an ABC (ATP-binding cassette) transporter involved in pyoluteorin secretion and itself resistance, were identified downstream of Plt biosynthesis gene cluster in Pseudomonas sp. M18. The ABC transporter gene pltH'-lacZ translational and transcriptional fusion expression plasmids, pHZLF and pHZCF, were constructed using promoter probe vector pME6015 and pME6522 respectively, and then were introduced into the wild-type strain of Pseudomonas sp. M18 and the pltZ mutant strain M18Z. The chromosomal pltZ disruption mutant gave rise to 3.7-8.4-fold enhancement of translational pltH'-'lacZ fusion expression and 2.8-7.4-fold enhancement of transcriptional pltH'-'lacZ fusion expression compared with those in the wild-type strain M18. These results suggested that pltZ can repress transcription of Plt ABC transporter, and it can indirectly regulate Plt biosynthesis negatively through the Plt ABC transporter system.

ATP-Binding Cassette Transporters↗

PubMed1988

Use of avidin-biotin-peroxidase complex (ABC) in postembedding immunoelectron microscopy: detection of immunoglobulins in myeloma cells.

For the purpose of detecting immunoglobulins at the electron microscopic level, the avidin-biotin-peroxidase complex (ABC) technique was applied to ultrathin sections of the bone marrow obtained from patients with multiple myeloma. In this study, a low temperature embedding medium (Lowicryl K4M) was applied to avoid the loss of antigenicity. This electron microscopic ABC (EM-ABC) technique allowed the detection of cytoplasmic immunoglobulins in myeloma cells and provided fairly satisfactory ultrastructural preservation. However, nonspecific reaction product was seen in eosinophil granules possibly due to the close affinity of biotinylated antibodies for eosinophil granules. The EM-ABC staining is of definite value for detecting various antigens as well as immunoglobulins in biological specimens.

Endoplasmic Reticulum↗

PubMed1986

Construction of DNA substrates modified with psoralen at a unique site and study of the action mechanism of ABC excinuclease on these uniformly modified substrates.

Psoralens bind to DNA noncovalently and upon exposure to near UV (320-400 nm) light produce covalent adducts. Thymidine residues in DNA, especially those at 5'-TpA-3' sequences, are most susceptible to the photochemical reaction. This property of the reaction and the recent advances in oligonucleotide synthesis and separation has enabled us to construct DNA fragments containing psoralen adducts at a specific site. The octanucleotide 5'-TCGTAGCT-3' was photoreacted (in the presence of the complementary strand) with the synthetic psoralen 4'-hydroxymethyl-4,5',8-trimethylpsoralen to obtain oligonucleotides adducted via the furan or pyrone ring at the internal thymine. These modified octanucleotides were ligated to nonmodified oligonucleotides to obtain a 40-base pair DNA fragment containing a psoralen adduct at a central location. The modified fragment having the thymine-furan side 4'-hydroxymethyl-4,5',8-trimethylpsoralen adduct was irradiated with 360 nm of light to produce an interstrand cross-link, and this cross-linked DNA was purified to homogeneity. These uniquely modified DNAs were used as substrates for Escherichia coli ABC excinuclease to determine its incision mechanism unambiguously and to determine the contact sites of the enzyme. ABC excinuclease mediates the cleavage of the 8th and 5th phosphodiester bonds 5' and 3', respectively, to psoralen monoadducts, and the 9th (5') and 3rd (3') phosphodiester bonds to the furan-side thymine of the cross-link. Preliminary DNaseI footprinting studies show that ABC excinuclease protects the whole 40-base pair fragment from DNaseI, and binding of the A and B subunits to the furan side-monoadducted substrate produces two hypersensitive phosphodiester bonds in the vicinity of the 5' incision site of ABC excinuclease.

Base Sequence↗

PubMed1984

[Modulation of the lymphocyte membrane with anti-HLA ABC in psoriasis].

Antibodies against lymphocyte surface antigens are able to rearrange the topographic of the cell membrana. This is the first event of immune cell functions for motility and cell adherence. Take in account: the high incidence of some HLA antigens in psoriasis and that the HLA system is involved in the genetic control of immune responses, we studied the reaction of anti HLA antibodies against lymphocytes from 16 patients with active psoriasis and from six healty controls. For this: lymphocytes T or B are sensitized with optimal amounts of anti HLA ABC antibodies. They are washed and resuspended in a nutrient medium and incubated at 37 degrees C. At 0, 3, 4, 5 and 6 hours samples are taken and observed for microlymphocytoxicity after addition of complement. Controls for viability and for antigenic sites are made. The addition of complement shows a decrease in the cytotoxic reaction. This is due to the loss from the cell surface of the antigen-antibodies complexes. The observed phenomenon is paralleled to the rearrangement of membrane proteins and is developed in a similar period to the normal antigen turnover time. Our results demonstrate a significative decrease in the turnover for HLA ABC molecules at the cell surface of T lymphocytes from psoriasic patients, that we assimilate to an altered rearrangement of HLA ABC molecules. No significative differences was observed for the turnover of HLA ABC molecules at cell surface of B lymphocytes. The altered T lymphocyte membrane demonstrate an immunobiologic defect and it may the explanation for the impairment for the T cell function in psoriasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1984

Isolation and sequencing of a cDNA clone for a human HLA-ABC antigen.

A cDNA clone, pHLA-A, containing sequences specific for a human class I HLA antigen heavy chain, was isolated from a bank of clones made from partially purified HLA-ABC heavy chain mRNA from the human lymphoblastoid cell line Bristol 8 (HLA-A1, A2, B8, B16). The clone corresponded to sequence for the -COOH-terminal 117 amino acids of an HLA-ABC alpha-chain. It differed in at least 15 positions from the published HLA-B7 amino acid sequence but in only two residues when compared to the partial HLA-A2 protein sequence, and was identical to the HLA-A3 protein sequence derived from the nucleotide sequence of the gene. It also differed from some published human HLA-ABC sequences by the addition of three extra -COOH-terminal amino acids: cysteine-lysine-valine. The clone may correspond to either the HLA-A1 allele, for which independent sequence information is not available, or to HLA-A2, in which case there are possible explanations for the discrepancies. Comparison of the pHLA-A sequence with genomic HLA sequences suggests variations in splicing at the end of the protein coding region in some HLA-ABC heavy chain genes, and the use of alternative poly(A) addition sites.

Amino Acid Sequence↗

PubMed1981

A comparison of the ABC orthogonal system with the standard 12-lead electrocardiogram.

Fifteen cases were taken at random from 200 cardiac patients on whom standard, Frank and ABC, ECG leads were taken synchronously. The ABC tracings were analysed without clinical or laboratory information being made available. Evidence is presented that ABC leads are superior to the 12-lead standard ECG system and show more significant changes than the Frank leads. It is suggested the ABC system should replace these 12-lead and Frank systems in clinical medicine owing to the much more sensitive analysis of the former and the ease of reading these leads.

Adolescent↗

PubMed1995

Chondroitinase ABC affects the activity of intracellular enzymes in rabbit articular cartilage chondrocytes.

OBJECTIVE: To determine the response of intrachondrocytic enzymes to specific matrix proteoglycan depletion induced by nonproteolytic enzyme, i.e., chondroitinase ABC. METHODS: The activity of uridine diphosphoglucose dehydrogenase, glucose-6-phosphate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase, and succinate dehydrogenase in the patellar cartilage chondrocytes of postpubertal rabbit was measured cytochemically following a single intraarticular injection of chondroitinase ABC. RESULTS: Dose dependent depression of dehydrogenase activity of duration up to 14 weeks was detected in chondrocytes of all cartilage zones. CONCLUSION: Chondroitinase ABC induced marked proteoglycan depletion, which was not associated with light microscopy structural damage. The mechanism(s) by which chondroitinase ABC produces intracellular effects are unknown.

Animals↗

PubMed1996

Protein secretion in gram-negative bacteria: assembly of the three components of ABC protein-mediated exporters is ordered and promoted by substrate binding.

One of the strategies used by Gram-negative bacteria to secrete proteins across the two membranes which delimit the cells, is sec independent and dedicated to proteins lacking an N-terminal signal peptide. It depends on ABC protein-mediated exporters, which consist of three cell envelope proteins, two inner membrane proteins, an ATPase (the ABC protein), a membrane fusion protein (MFP) and an outer membrane polypeptide. Erwinia chrysanthemi metalloproteases B and C and Serratia marcescens hemoprotein HasA are secreted by such homologous pathways and interact with the ABC protein. Using as protein substrates HasA and GST-PrtC, a chimeric protein which has a glutathione S-transferase moiety fused to a large C-terminal domain of protease C, we developed a simple system to identify proteins bound to the substrate based on substrate affinity-chromatography using heme- or glutathione-agarose. We show an ordered association between the protein substrates and the three exporter components: the substrate recognizes the ABC protein which interacts with the MFP which in turn binds the outer membrane component. Substrate binding is required for assembly of the three components.

ATP-Binding Cassette Transporters↗

PubMed1997

[Multidrug resistance of cancer cells mediated by ABC superfamily transporters].

ATP-binding cassette(ABC) superfamily transporters, including P-glycoprotein and MRP, actively transport various structurally dissimilar chemotherapeutic compounds out of cancer cells and confer multidrug resistance. Members of ABC superfamily which may extrude anti-cancer drugs are still expanding, thus the importance of these proteins are further increasing for cancer chemotherapy. Multidrug resistance will be acquired either by the induction of expression of ABC superfamily transporters or by mutations of ABC superfamily genes which cause amino acids substitutions. We recently found that amino acid substitutions in the first predicted transmembrane domain of P-glycoprotein increase the ability to confer resistance to important anti-cancer drugs adriamycin and VP-16. The mechanisms for drug recognition and transport of human P-glycoprotein and MRP are discussed.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1998

A model for the nucleotide-binding domains of ABC transporters based on the large domain of aspartate aminotransferase.

ABC transporters are a large superfamily of integral membrane proteins involved inATP-dependent transport across biological membranes. Members of this superfamily play roles in a number of phenomena of biomedical interest, including cystic fibrosis (CFTR) and multidrug resistance (P-glycoprotein, MRP). Most ABC transporters are predicted to consist of four domains, two membrane-spanning domains and two cytoplasmic domains. The latter contain conserved nucleotide-binding motifs. Attempts to determine the structure of ABC transporters and of their separate domains are in progress but have not yet been successful. To aid structure determination and possibly learn more about the domain boundaries, we set out to model nucleotide-binding domains (NBDs) of ABC transporters based on a known structure. Previous attempts to predict the 3D structure of NBDs were based solely on sequence similarity with known nucleotide-binding folds. We have analyzed the sequences of a number of nucleotide-binding domains with the algorithm THREADER, developed by D.T. Jones, and a possible fold was found in the structure of aspartate aminotransferase. We present a model for the N-terminal NBD of CFTR, based on the large domain of the A chain of aspartate aminotransferase. The model is refined using multiple sequence alignment, secondary structure prediction, and 3D-1D profiles. Our model seems to be in good agreement with known properties of nucleotide-binding domains and has some appealing characteristics compared with the previous models.

ATP-Binding Cassette Transporters↗

PubMed2007

Mechanisms of cartilage growth: modulation of balance between proteoglycan and collagen in vitro using chondroitinase ABC.

OBJECTIVE: To examine the cartilage growth-associated effects of a disruption in the balance between the swelling pressure of glycosaminoglycans (GAGs) and the restraining function of the collagen network, by diminishing GAG content prior to culture using enzymatic treatment with chondroitinase ABC. METHODS: Immature bovine articular cartilage explants from the superficial and middle layers were analyzed immediately or after incubation in serum-supplemented medium for 13 days. Other explants were treated with chondroitinase ABC to deplete tissue GAG and also either analyzed immediately or after incubation in serum-supplemented medium for 13 days. Treatment- and incubation-associated variations in tissue volume, contents of proteoglycan and collagen network components, and tensile mechanical properties were assessed. RESULTS: Incubation in serum-supplemented medium resulted in expansive growth with a marked increase in tissue volume that was associated with a diminution of tensile integrity. In contrast, chondroitinase ABC treatment on day 0 led to a marked reduction of GAG content and enhancement of tensile integrity, and subsequent incubation led to maturational growth with minimal changes in tissue volume and maintenance of tensile integrity at the enhanced levels. CONCLUSION: The data demonstrate that a manipulation of GAG content in articular cartilage explants can distinctly alter the growth phenotype of cartilage. This may have practical utility for tissue engineering and cartilage repair. For example, the expansive growth phenotype may be useful to fill cartilage defects, while the maturational growth phenotype may be useful to induce matrix stabilization after filling defect spaces.

Animals↗