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PubMed1988

CEA-containing immune complexes in sera of patients with colorectal and breast cancer--analysis of complexed immunoglobulin classes.

A sandwich enzyme immunoassay was developed to detect circulating immune complexes containing carcinoembryonic antigen (CEA) and immunoglobulin (Ig) G, IgA, or IgM using a nitrocellulose-bound anti-CEA antibody as the solid phase reagent. Elevated levels of CEA-containing circulating immune complexes (CEA-IC) were found in 15.4% of 117 sera from patients with colorectal cancer in a postsurgery follow-up study. Also in 24.5% of 102 sera from patients with breast cancer in different states of disease CEA-IC were found. The predominant Ig determined in CEA-IC of colorectal cancer patients was IgA, followed by IgG and IgM, whereas IgG and IgM were the most frequent Igs in CEA-IC of breast cancer patients. Elevated CEA levels were found in 12.0% of the colorectal cancer patients and in 25.4% of sera from breast cancer patients. No significance for the coincidence of elevated CEA levels and CEA-IC was recorded in all patients sera tested. In sera of patients with disease recurrence, however, both parameters were shown to be elevated (CEA 80.7% and CEA-IC 42.3%). The data presented indicate the detection of CEA-IC as an additional parameter for the identification of patients at increased risk for disease recurrence.

Antigen-Antibody Complex↗

PubMed1992

Mapping of the SLA complex of miniature swine: mapping of the SLA gene complex by pulsed field gel electrophoresis.

The overall order of the regions of the swine major histocompatibility complex (MHC), the SLA complex, was determined by pulsed field gel electrophoresis (PFGE). It was found that the order of the regions is class II-class III-class I. A class I probe hybridized to a 420 kb Mlu I and a 420 kb Not I fragment as did a class III probe for C2. None of the class II probes hybridized to these fragments. Thus, linkage of class I to class III was shown. The class III C2, Bf, and C4 genes were found to residue in a 190 kb Not I fragment. Linkage of class III and class II genes was shown when both the class III C4 and the class II DR probes hybridized to the same 195 kb Sac II and 340 kb Not I fragments. The class I probe did not hybridize to these fragments. The order of the regions, class II-class III-class I, is similar to that of human MHC genes and may have been conserved in evolution so that coordinated expression of MHC genes could be achieved.

Animals↗

PubMedDate not supplied

Isolation and characterization of a multienzyme complex containing DNA replicative enzymes from mitochondria of S. cerevisiae. Multienzyme complex from yeast mitochondria.

A 40 S multienzyme complex containing mtDNA polymerase was isolated from mitochondria of S. cerevisiae by density gradient centrifugation and by gel filtration chromatography. Besides DNA polymerase, RNA polymerase, primase, 3'-->5' exonuclease and an ATPase activities were found to be associated with it. The presence of some of these enzymes were confirmed by Western blot. This high molecular weight multienzyme complex containing DNA has most of the attributes of a putative replisome.

Antibodies, Fungal↗

PubMed1979

Complexed rheumatoid factor measurements in sera, synovial fluids and in immune complex fractions.

Mild acidic treatment increases the rheumatoid factor titre of some sera and synovial fluids (SF) in rheumatoid arthritis (RA), juvenile RA (JRA) and most frequently in rheumatoid vasculitis. This unmasking of 'hidden' RF in serum and SF samples correlated with the RF-immune complexes (RF-IC) and complexed C4 present in the 3% polyethylene glycol (PEG) precipitates, indicating that by means of 'hidden' RF measurements RF-ICs are possibly detected. This method seems to provide a diagnostic tool for detecting RF-ICs in RA and other related diseases.

Antigen-Antibody Complex↗

PubMed2000

An answer to a complex problem: cloning the mouse t-complex responder.

The t-complex is maintained in wild mouse populations by its high transmission (up to 99%) from heterozygous males and provides an example of "meiotic drive". Its molecular basis has remained obscure despite long and intensive study. In a major advance, the t-complex responder gene, thought to be the key gene on which several distorters act, has now been cloned.

Animals↗

PubMed2006

Tubulointerstitial immune complex nephritis in a patient with systemic lupus erythematosus: role of peritubular capillaritis with immune complex deposits in the pathogenesis of the tubulointerstitial nephritis.

Class IV-G (A/C) diffuse lupus nephritis and tubulointerstitial (TI) nephritis in a 31-year old woman was studied by light, immunofluorescence (IF), and electron microscopy (EM), to determine the pathogenesis of the TI lesions. The light microscopic findings showed peritubular capillaritis in the interstitium, with ruptures in the capillary structure, lysis of the surrounding tubular basement membrane (TBM), extravasated red blood cells (RBCs), the infiltration of neutrophils and mononuclear cells, and edema. The IF study revealed IgG, IgA, IgM, C1q, C3, and C4 depositions along the TBM, on the capillary walls, and in the interstitium proper. The EM study disclosed the deposition of immune complexes in the TBM, the capillary wall, and the interstitium proper. Based on these findings, the TI nephritis in this patient was considered to be due to peritubular capillaritis secondary to the immune complex depositions in the capillary wall of the interstitium.

Adult↗

PubMed1980

The isolation of immune complexes containing IgM rheumatoid factor and recovery of IgG rheumatoid factor from the complexes.

IgG with rheumatoid factor activity has been recovered from immune complexes containing IgM rheumatoid factor. This was done by passing serum from patients with rheumatoid arthritis through an immunoadsorbent column of the F(ab')2 fragment of rabbit anti-human mu chain. The recovered IgM was analysed by radioimmunoassays for IgM and IgG rheumatoid factors before and after sucrose density gradient centrifugation at neutral and acid pH. It is considered that the method may be generally applicable for the isolation of immune complexes containing IgM antibodies.

Animals↗

PubMed1980

Detection and quantitation of hepatitis B surface antigen immune complexes (HBsAg-ICs) by an antigen-specific method. II. Circulating immune complexes (CICs) in patients with hepatitis B and asymptomatic HBsAg carriers.

Using the PEG-trypsinisation assay, HBsAg-CICs were detected in 70% of patients with acute hepatitis B, in 5% of the asymptomatic HBsAg carriers and, in addition, in each of the 2 cases of chronic hepatitis B virus infection. In serial examinations, the complexed HBsAg levels in 77% of patients with acute hepatitis B decreased progressively in parallel with the free HBsAg levels, and persisted in the remaining 23%. In 19% of patients positive for HBsAg-CICs, the complexed HBsAg levels were higher than those of free HBsAg. No correlation was observed between results of PEG-trypsinisation and an anticomplementary assay. Artificial HBsAg-ICs in antigen excess were found to be poorly anticomplementary. C3 concentrations were normal or elevated in the majority (88%) of sera positive for HBsAg-CICs. These findings suggest that HBsAg-CICs in antigen excess are unlikely to be complement-activating. The method is useful for clinical investigation and for routine examination for HBsAg-CICs.

Adolescent↗

PubMed1987

Composition of IgA immune complexes precipitated with polyethylene glycol. A model for isolation and analysis of immune complexes.

Covalently cross-linked large and intermediate-sized IgA oligomers, prepared with IgA anti-dinitrophenyl (DNP) and bis-DNP-pimelic acid ester, were used to examine the ability of different concentrations (3.5%, 5% and 7%, w/v) of polyethylene glycol (PEG) to precipitate IgA immune complexes (IgA-IC). The size of the IgA-IC precipitated with PEG was determined by gradient polyacrylamide gel electrophoresis and quantitative autoradiography. The standard concentration of 3.5% PEG precipitated only a minor fraction (20%) of the IgA-IC. In contrast, 5% and 7% PEG precipitated 45% and 79% of the complexes, respectively. To test the influence of the antigen on the PEG assay. IgA-IC prepared with IgA anti-DNP and DNP conjugates of either bovine serum albumin or Ficoll were also used. Approximately 38% of these IgA-IC were precipitated with 3.5%, PEG. By comparison, the concentration of 5% and 7% PEG precipitated 60% and 76% of the IgA-IC, respectively. Distilled water rather than the standard borate-buffered saline was shown to be the optimal solvent for resolubilization of the PEG precipitates. Serum samples from 22 IgA nephropathy patients and 12 normal donors were tested with 3.5%, 5% and 7% PEG. Only the 7% PEG assay showed a significant difference between patients and controls (P less than 0.001) in the IgA levels of precipitates. Thus, the use of 7% PEG is recommended for the detection, isolation and analysis of large- and intermediate-sized IgA-IC.

Antigen-Antibody Complex↗

PubMed1983

Biochemical studies of immune complexes. II. Purification of immune complexes from sera of patients with malignant melanoma.

Circulating immune complexes (CICs) from serum samples of patients with malignant melanoma were isolated in high yield utilizing a bifunctional chromatography matrix that binds all normal serum proteins except IgG-containing immune complexes (ICs), IgG, and transferrin. Protein fractions were subsequently analyzed by polyacrylamide gel electrophoresis (PAGE) and characterized by molecular weight. By this method, one common and several unique component nonimmunoglobulin proteins of the ICs were identified. These proteins possess similar molecular weights to several previously described human melanoma antigens. This technique should permit biochemical and immunological characterization of the component antigens of CICs in melanoma and other malignancies.

Antigen-Antibody Complex↗

PubMed2003

Altered pattern of major histocompatibility complex expression in renal carcinoma: tumor-specific expression of the nonclassical human leukocyte antigen-G molecule is restricted to clear cell carcinoma while up-regulation of other major histocompatibility complex antigens is primarily distributed in all subtypes of renal carcinoma.

Renal epithelial cancers represent a heterogeneous group of neoplasms arising from the malignant transformation of presumed diverse cell lineages. We recently demonstrated that tumor-specific up-regulation of human leukocyte antigen (HLA)-G, a nonclassical HLA class Ib molecule that might be involved in immune evasion by tumor cells, frequently occurs in conventional (clear cell) renal carcinoma. We here examined whether HLA-G activation is a common process affecting all types of renal epithelial tumors. We analyzed a series of 38 paraffin-embedded tumors including clear cell, papillary, chromophobe, collecting duct carcinoma, and oncocytoma. Seven of 12 (58%) clear cell tumors were positive by immunohistochemistry, whereas all of the other subtypes of renal carcinoma were negative for HLA-G expression. Developing or adult normal renal tissue were devoid of HLA-G expression. We also observed that ectopic expression of HLA class II antigens occurs more frequently in clear cell renal carcinoma than in other subtypes of renal tumors. Moreover, in contrast to the common observation of a down-regulation of major histocompatibility complex class Ia antigens reported in various tumors, the concomitant study of the same biopsies for classical HLA class Ia antigen expression revealed a general increase of HLA class Ia expression, regardless of histological subtypes. These results provide evidence for the heterogeneity of major histocompatibility complex expression patterns in renal carcinoma and support the hypothesis that specific mechanisms underlying the malignant transformation into clear cell renal carcinoma up-regulate expression of HLA-G and to a lesser extent HLA class II molecule expression. Considering the immunotolerant role of HLA-G toward the immune response, these mechanisms may thus provide renal cell carcinoma tumor cells with additional means to escape immune surveillance.

Adenocarcinoma, Clear Cell↗

PubMed2003

Energy transfer pathways in the minor antenna complex CP29 of photosystem II: a femtosecond study of carotenoid to chlorophyll transfer on mutant and WT complexes.

The energy transfer processes between carotenoids and Chls have been studied by femtosecond transient absorption in the CP29-WT complex, which contains only two carotenoids per polypeptide located in the L1 and L2 sites, and in the CP29-E166V mutant in which only the L1 site is occupied. The comparison of these two samples allowed us to discriminate between the energy transfer pathways from the two carotenoid binding sites and thus to obtain detailed information on the Chl organization in CP29 and to assign the acceptor chlorophylls. For both samples, the main transfer occurs from the S(2) state of the carotenoid. In the case of the L1 site the energy acceptor is the Chl a 680 nm (A2), whereas the Chl a 675 nm (A4-A5) and the Chl b 652 nm (B6) are the acceptors from the xanthophyll in the L2 site. These transfers occur with lifetimes of 80-130 fs. Two additional transfers are observed with 700-fs and 8- to 20-ps lifetimes. Both these transfers originate from the carotenoid S(1) states. The faster lifetime is due to energy transfer from a vibrationally unrelaxed S(1) state, whereas the 8- to 20-ps component is due to a transfer from the S(1,0) state of violaxanthin and/or neoxanthin located in site L2. A comparison between the carotenoid to Chl energy transfer pathways in CP29 and LHCII is presented and differences in the structural organization in the two complexes are discussed.

Binding Sites↗

PubMed1999

Hydrogen peroxide generation by higher plant mitochondria oxidizing complex I or complex II substrates.

The generation of H2O2 by isolated pea stem mitochondria, oxidizing either malate plus glutamate or succinate, was examined. The level of H2O2 was almost one order of magnitude higher when mitochondria were energized by succinate. The succinate-dependent H2O2 formation was abolished by malonate, but unaffected by rotenone. The lack of effect of the latter suggests that pea mitochondria were working with a proton motive force below the threshold value required for reverse electron transfer. The activation by pyruvate of the alternative oxidase was reflected in an inhibition of H2O2 formation. This effect was stronger when pea mitochondria oxidized malate plus glutamate. Succinate-dependent H2O2 formation was ca. four times lower in Arum sp. mitochondria (known to have a high alternative oxidase) than in pea mitochondria. An uncoupler (FCCP) completely prevented succinate-dependent H2O2 generation, while it only partially (40-50%) inhibited that linked to malate plus glutamate. ADP plus inorganic phosphate (transition from state 4 to state 3) also inhibited the succinate-dependent H2O2 formation. Conversely, that dependent on malate plus glutamate oxidation was unaffected by low and stimulated by high concentrations of ADP. These results show that the main bulk of H2O2 is formed during substrate oxidation at the level of complex II and that this generation may be prevented by either dissipation of the electrochemical proton gradient (uncoupling and transition state 4-state 3), or preventing its formation (alternative oxidase). Conversely, H2O2 production, dependent on oxidation of complex I substrate, is mainly lowered by the activation of the alternative oxidase.

Hydrogen Peroxide↗

PubMed1999

Respiratory chain complex III [correction of complex] in deficiency with pruritus: a novel vitamin responsive clinical feature.

We report a child with an isolated complex III respiratory chain deficiency and global developmental delay who had severe pruritus with elevated plasma bile acid levels. A liver biopsy showed micronodular cirrhosis, and enzymologic evaluation demonstrated an isolated complex III deficiency in both liver and muscle. His pruritus improved and serum bile acid levels decreased after treatment with menadione and vitamin C.

Anemia, Iron-Deficiency↗

PubMed2000

Use of a photoactivated ruthenium dimer complex to measure electron transfer between the Rieske iron-sulfur protein and cytochrome c(1) in the cytochrome bc(1) complex.

Electron transfer between the Rieske iron-sulfur protein (Fe(2)S(2)) and cytochrome c(1) was studied using the ruthenium dimer, Ru(2)D, to either photoreduce or photooxidize cytochrome c(1) within 1 micros. Ru(2)D has a charge of +4, which allows it to bind with high affinity to the cytochrome bc(1) complex. Flash photolysis of a solution containing beef cytochrome bc(1), Ru(2)D, and a sacrificial donor resulted in reduction of cytochrome c(1) within 1 micros, followed by electron transfer from cytochrome c(1) to Fe(2)S(2) with a rate constant of 90,000 s(-1). Flash photolysis of reduced beef bc(1), Ru(2)D, and a sacrificial acceptor resulted in oxidation of cytochrome c(1) within 1 micros, followed by electron transfer from Fe(2)S(2) to cytochrome c(1) with a rate constant of 16,000 s(-1). Oxidant-induced reduction of cytochrome b(H) was observed with a rate constant of 250 s(-1) in the presence of antimycin A. Electron transfer from Fe(2)S(2) to cytochrome c(1) within the Rhodobacter sphaeroides cyt bc(1) complex was found to have a rate constant of 60,000 s(-1) at 25 degrees C, while reduction of cytochrome b(H) occurred with a rate constant of 1000 s(-1). Double mutation of Ala-46 and Ala-48 in the neck region of the Rieske protein to prolines resulted in a decrease in the rate constants for both cyt c(1) and cyt b(H) reduction to 25 s(-1), indicating that a conformational change in the Rieske protein has become rate-limiting.

Amino Acid Substitution↗

PubMed1994

Reconstitution of a functional photosynthetic receptor complex with isolated subunits of core light-harvesting complex and reaction centers.

The B820 subunit form of the core light-harvesting complex LHI, isolated from the photosynthetic bacterium Rhodospirillum rubrum, was combined in a reassociation assay with the reaction center (RC) isolated from the same or related bacteria. This reassociation produced a photoreceptor complex (PRC) which appeared, by absorption spectroscopy, circular dichroism measurements, and kinetic absorption spectroscopy measuring transient photochanges, as analogous to the PRC in the intact bacteria. Energy transfer between the LHI and reaction center progressed with almost 100% efficiency and indicated a cooperative pattern of transfer. Treatment of the RC with proteinase K resulted in peptide cleavages of all three polypeptides of the RC but did not alter the light-induced charge separation in the RC or prevent the reassociation of the LHI and modified RC. Energy transfer efficiency from LHI to RC still approached 100% but the cooperative behavior seen in reconstitutions with the intact RC was not observed. Initial experiments using interspecies reassociations (LHI from Rhodobacter sphaeroides and RC from Rs. rubrum) showed a low efficiency of energy transfer from LHI to RC. Possible association domains for the LHI-RC interaction based on considerations of the comparative amino acid sequences of the RC of each bacteria and the most feasible remaining residues in the proteinase K treated RC are considered.

Amino Acid Sequence↗

PubMed2002

Decay of the transient Cu(B)-CO complex is accompanied by formation of the heme Fe-CO complex of cytochrome cbb(3)-CO at ambient temperature: evidence from time-resolved Fourier transform infrared spectroscopy.

Time-resolved step-scan Fourier infrared spectroscopy has been used to study the CO-bound cbb(3)-type cytochrome c oxidase from Pseudomonas stutzeri at room temperature. We observe a single band in the FTIR spectrum at 1956 cm(-1) (beta-form). The time-resolved data indicate that upon photolysis, CO is transferred from heme b(3) (nu(CO) = 1956 cm(-1)) to CuB (nu(CO) = 2064 cm(-1)). The decay of the 2065 cm(-1) peak (t(1/2) = 120 +/- 16 ms) and the development of the 1956 cm(-1) peak (t(1/2) = 144 +/- 8 ms ) suggest that formation of the Fe-CO complex is concurrent with the decay of the CuB-CO complex. The intensity ratio of the Fe-CO/CuB-CO (2.15) remains constant for all data points, and thus we conclude that no fraction of CO escapes the binuclear center at 293 K.

Carbon Monoxide↗

PubMed2002

Reduction of expression of tuberin, the tuberous-sclerosis-complex-gene-2 product in tuberous sclerosis complex associated connective tissue nevi and sporadic squamous and basal cell carcinomas.

BACKGROUND: Patients affected with tuberous sclerosis complex (TSC) are prone to the development of multiple benign tumors of the skin and other organs. Tuberin, the protein product of the tuberous-sclerosis-complex-2 tumor suppressor gene (TSC2) has been shown to inhibit cell proliferation. In TSC associated kidney tumors and sporadic brain tumors the loss/reduction of tuberin has been shown. METHODS: Specimens of nine squamous cell carcinomas (SCC) and five basal cell carcinomas (BCC) from patients without TSC and six biopsies of connective tissue nevi (CTN) of patients with TSC were obtained. Specimens were analyzed by immunoblotting for the expression of tuberin. RESULTS: Absent or reduced levels of tuberin were detected in the dermal parts of three of six shagreen patches, two of five BCC, and four of nine SCC. CONCLUSIONS: In tumors/hamartomas of patients with TSC the complete loss of TSC2 and tuberin is a mechanism which could be shown for CTN, thereby excluding the possibility of haploinsufficiency of TSC2. In a substantial number of cutaneous BCC and SCC the loss or downregulation of tuberin seems to be epigenetic, as alterations of TSC2 are not known in these tumors. The absence or reduction of tuberin might contribute to their proliferation.

Basal Cell Carcinoma↗