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Evidence of in vivo free radical generation by spin trapping with alpha-phenyl N-tert-butyl nitrone during ischemia/reperfusion in rabbit kidneys.

By using alpha-phenyl N-tert-butyl nitrone (PBN) as spin trap molecule and the electron paramagnetic resonance (EPR) technique, we obtained the first direct evidence of in vivo intervention of free radicals during an ischemia (50 minutes) reperfusion phenomenon in kidney of an intact rabbit. An EPR signal (triplet of doublets) characterized by coupling constants aN = 14.75-15 G and aH beta = 2.5-3 G was detected in blood samples. The signal was consistent with a nitroxyl-radical adduct resulting from the spin trapping by PBN of either oxygen-or carbon-centered radicals. Control experiments indicated that the EPR signal was not due to a toxic effect of the spin trap molecule.

Animals↗

Detection of cerebral {beta}-hydroxy butyrate, acetoacetate, and lactate on proton MR spectroscopy in children with diabetic ketoacidosis.

BACKGROUND AND PURPOSE: Ketone bodies provide important alternate fuel for brain metabolism, and their transport into the brain increases with prolonged fasting. During diabetic ketoacidosis (DKA), serum ketone concentrations markedly increase; however, little is known about whether ketone bodies accumulate in cerebral tissues during DKA. We used proton MR spectroscopy (MRS) to detect cerebral beta-hydroxy butyrate (betaOHB) and acetone/acetocaetate (AcAc) in children with DKA. METHODS: Twenty-five children underwent brain MRS: nine within 4 hours of the start of treatment for DKA; 11, at 4-8 hours; and five, at 8-12 hours. MRS was repeated after their recovery from the DKA episode at > or =72 hours after the start of treatment. MRS was evaluated for peaks corresponding to betaOHB (doublet centered on 1.20 ppm) and lactate (doublet centered on 1.33 ppm). Difference spectroscopy was used to identify the AcAc peak at 2.22-2.26 ppm. RESULTS: betaOHB was detected in 13 children (52%), more frequently within 4 hours (eight children, 89%) than after 4 hours (five children, 31%). AcAc was detected in 15 children (60%), more frequently at >4 hours after the start of treatment (12 patients, 75%) than in the first 4 hours (three patients, 33%). Lactate was detected in five children (18%), all within the first 8 hours of treatment. CONCLUSION: In children, betaOHB and AcAc accumulate in the brain during DKA, and they can be detected on MRS. Care should be taken in interpreting MRS results in patients with DKA to avoid erroneously attributing betaOHB peaks to lactate.

3-Hydroxybutyric Acid↗

Serological response of patients with leprosy to a 28- to 30-kilodalton protein doublet from early cultures of Mycobacterium bovis BCG.

Analysis by Western immunoblotting of Mycobacterium bovis BCG short-term culture filtrates with a pool of serum samples from lepromatous leprosy patients revealed an immunodominant protein doublet with apparent molecular masses of 28 and 30 kilodaltons (kDa). The humoral response to these antigens was also investigated by using individual serum samples from patients representative of the whole spectrum of leprosy and from tuberculosis patients, as well as from contacts of leprosy patients and control groups. The protein doublet was recognized by 92% of the sera from patients with lepromatous leprosy (51 of 56), whereas essentially negative results were obtained with sera from the other groups. Similar immunodominant bands were also detected by Western blotting analysis of sonic extracts of seven other slow- and fast-growing mycobacterial species, suggesting a broad distribution of these antigens within the genus. Analysis of the purified doublet by Western blotting after two-dimensional gel electrophoresis fractionation showed that the 28- and 30-kDa doublet consisted of at least five different components with pls from 5.2 to 5.7 and molecular masses from 28 to 31 kDa. These results indicate that the protein doublet could be used as a potential marker in the diagnosis of lepromatous leprosy.

Antibodies, Bacterial↗

Expression, characterization, processing and immunogenicity of an insulin-dependent diabetes mellitus autoantigen, IA-2, in Sf-9 cells.

Autoantibodies to a 64-kD protein and a 40-kD tryptic fragment from pancreatic islets have been detected at high frequency in the sera of patients with insulin-dependent diabetes mellitus (IDDM). IA-2, a newly isolated transmembrane protein tyrosine phosphatase, is a major islet cell autoantigen in IDDM and the precursor of a 40-kD tryptic fragment. To express large quantities of recombinant IA-2 protein and analyse post-translational modifications we expressed full-length human IA-2 in baculovirus-infected Sf-9 cells. IA-2 expression was analysed by Western blot and by immunoprecipitation of 35S-methionine-radiolabelled proteins with rabbit antisera or IDDM sera. A 120-kD IA-2 protein was detected during the early, but not the late, phase of the infection. Pulse-chase experiments showed that the 120-kD protein was processed into fragments of 64 kD and smaller fragments of approximately 50 kD, 38 kD and 32 kD. The 64-kD fragment appeared as a doublet. Tunicamycin and PNGase F treatment down-shifted the 120-kD protein and the 64-kD doublet into lower molecular weight bands, suggesting that both were glycosylated. Trypsin treatment converted the 120-kD protein and the 64-kD doublet into a 40-kD fragment. Baculovirus-expressed IA-2 was as sensitive or slightly more sensitive than in vitro translated IA-2 in detecting autoantibodies to IA-2: 66% of sera from newly diagnosed IDDM patients reacted with baculovirus-expressed IA-2 compared with 59% of the same sera which reacted with in vitro translated IA-2. It is concluded that baculovirus-expressed IA-2 is a good source of autoantigen and that a number of lower molecular weight fragments with which IDDM autoantibodies react are derived from the 120-kD full-length IA-2 molecule.

Animals↗

Nitric oxide stimulates tyrosine phosphorylation of focal adhesion kinase, Src kinase, and mitogen-activated protein kinases in murine fibroblasts.

Nitric oxide (NO) can participate in cellular signaling. In this study, monoclonal antibodies against proteins from the growth factor-mediated signalling pathway were used to identify a set of 126-, 56-, 43-, and 40-kDa proteins phosphorylated on tyrosine at NO stimulation of murine fibroblasts overexpressing the human epidermal growth factor receptor. The band corresponding to the 126-kDa protein was FAK. The 56-kDa protein was Src kinase, and the doublet 43- and 40-kDa protein corresponded to the extracellular-regulated MAP kinases (ERK1/ERK2). The effects of NO on focal adhesion complexes were also investigated. FAK was constitutively associated with the adapter protein Grb2 in HER14 cells. Treatment of the cells with the NO donor, sodium nitroprusside, or with EGF did not change this association. We also detected a basal constitutive association of Src kinase with FAK in HER14 cells. In NO-treated cells, this association was stimulated. The doublet 43/40-kDa protein was identical to the ERK1/ERK2 MAP kinases. NO stimulated an increase in ERK1/ERK2 phosphorylation as assessed by a shift in its eletrophoretic mobility and by increased phosphotyrosine immunoreactivity. Furthermore, NO-dependent activation of ERK1/ERK2 depended on the intracellular redox status. Inhibition of glutathione synthesis was necessary to promote activation of the kinases.

Adaptor Proteins, Signal Transducing↗

[Hemorrhagic rectocolitis and carcinoma of the colon. Contribution of flow cytometry. Report of 3 cases].

Carcinoma complicating ulcerative colitis, although an uncommon event, is well known but follow-up of patients to detect high-grade dysplasia as a potential indicator for colectomy is very difficult. Retrospective morphological and cytometrical analysis of three resected colons harboring carcinoma coming from patients with ulcerative colitis were performed. It allowed to confirm the value of this technique. Histogram patterns varied between narrow unimodal in quiescent mucosa to broad unimodal with high IP (proliferation index) in regenerative mucosa and aneuploid in high dysplasic mucosa and carcinoma. In addition to histopathology and in spite of a patchy distribution of aneuploidy, different degrees of dysplasia in mucosa and technical sensibility DNA (desoxyribonucleic acid) analysis in long-standing ulcerative colitis seems to be helpful in the detection of potential malignancy.

Adult↗

Epizootiology, pathology, and ultrastructure of the myxosporean associated with parasitic encephalitis of farmed Atlantic salmon Salmo salar in Ireland.

In 1995 at a sea-farm in Ireland, Atlantic salmon Salmo salar smolts were introduced in the spring and autumn into 2 marine rearing sites, one with and one without recent histories of neurologic disease and mass mortality believed to be due to parasitic encephalitis. In order to monitor disease, determine the onset and anatomic distribution of parasites and encephalitis, and determine the ultrastructure and identity of the parasite, randomly selected smolts were necropsied from both sites at intervals of 1 to 3 d for periods of 1 to 2 mo, and clinical signs and cumulative mortalities were monitored. The prevalences of parasites and encephalitis were assessed by light microscopy, and sections of brain were examined by transmission electron microscopy. No clinical signs of neurologic disease were observed, but parasites and encephalitis were detected in smolts from both sites, with prevalences of each that were significantly greater in smolts from the site with recent disease. Based on light microscopy, the parasite was first detected in smolts sampled at 26 d post-introduction. Parasites were detected with significantly greater frequency in the optic tectum of the mesencephalon than in the diencephalon, metencephalon, and myelencephalon, and were not detected in the telencephalon. Foci of non-suppurative encephalitis were detected with significantly greater frequency in the myelencephalon than in each of the other 4 anatomic subdivisions. In each anatomic subdivision the prevalence of encephalitis was significantly greater than that of parasitic infection. The ultrastructure of the parasite was consistent with that of a histozoic presporogonic multicellular developmental stage of a myxosporean, characterized by intercellular branching tubular structures containing generative cells arranged individually or in cell-in-cell doublets. Parasitic stages were located between bundles of axons, with compression of axons along segments of their plasmalemma. No mature spores were detected.

Animals↗

The human cationic antimicrobial protein (hCAP-18) is expressed in the epithelium of human epididymis, is present in seminal plasma at high concentrations, and is attached to spermatozoa.

Innate immunity is important for the integrity of the host against potentially invasive pathogenic microorganisms in the environment. Antibiotic peptides with broad antimicrobial activity are part of the innate immune system. We investigated the presence of the cathelicidin, human cationic antimicrobial protein (hCAP-18), in the male reproductive system. We found strong expression of the hCAP-18 gene by in situ hybridization and hCAP-18 protein, as detected by immunohistochemistry, in the epithelium of the epididymis, but not in the testis. The highest expression in the epididymis was in the caudal part. Western blotting showed a doublet band, the upper part corresponding to the size of hCAP-18 in plasma and neutrophils. Using a specific enzyme-linked immunosorbent assay (ELISA), levels of 86.5 +/- 37.8 microg/ml (mean +/- standard deviation; range, 41.8 to 142.8 microg/ml; n = 10) were detected in seminal plasma from healthy donors, which is 70-fold higher than the level in blood plasma. Flow cytometry and immunocytochemistry revealed the presence of hCAP-18 on spermatozoa. ELISA measurement showed levels of 196 ng/10(6) spermatozoa, corresponding to 6.6 x 10(6) molecules of hCAP-18 per spermatozoon. Our results suggest a key role for hCAP-18 in the antibacterial integrity of the male reproductive system. The attachment of hCAP-18 to spermatozoa may implicate a role for hCAP-18 in conception.

Anti-Bacterial Agents↗

Muscle connections between imaginal discs in Drosophila.

A comparison of the protein content of different imaginal discs of Drosophila revealed that among more than 600 protein species that can be detected, only three show differences in concentration among different types of discs. Two of them form a doublet that can be resolved only by using extended electrophoresis conditions. This doublet was also reported to have a nonhomogeneous distribution within some discs. Here we show that these two proteins are tropomyosin components, and that they are associated not with the discs themselves but with a new type of muscle that connects some of the discs together.

Antibodies, Monoclonal↗

Reactivity of haloketenes and halothioketenes with nucleobases: reactions in vitro with DNA.

Ketenes are important and highly reactive intermediates. Thioketenes are formed by cysteine conjugate beta-lyase-dependent biotransformation of 1-halovinylcysteine S-conjugates which are metabolites of several halogenated olefins. Nucleic acid constituents react with haloketenes and halothioketenes in vitro. Thioketenes induce DNA strand breaks in incubations of 1,2-dichlorovinyl 2-nitrophenyl disulfide, a thioketene precursor, with pBr 322 plasmid DNA. After treatment of single-stranded or native calf thymus DNA with chlorothioketene generated by the hydrolysis of 1,2-dichlorovinyl 2-nitrophenyl disulfide, the formation of 3,N4-thioacetylcytosine could be demonstrated. N6-(Dichloroacetyl)adenine and N4-(dichloroacetyl)cytosine, however, adducts formed by dichloroketene in vitro, are labile to hydrolysis. Therefore, the binding of this compound to DNA constituents in intact DNA is difficult to demonstrate. Substitution of one chlorine atom by fluorine allowed us to use 19F NMR as a tool to demonstrate the formation of adducts by dihaloketenes in intact DNA. N6-(Chlorofluoroacetyl)adenine and N4-(chlorofluoroacetyl)cytosine were synthesized (yields 77%, 15%, respectively) as references and characterized by LC/MS, 1H, 13C, and 19F NMR, FT-IR, and elemental analysis. To demonstrate the ability of dihaloketenes to bind to DNA, poly-dA (1 mg) and calf thymus DNA (10 mg) were suspended in DMF and treated with different concentrations of chlorofluoroketene (50-200 micromol). Analysis of the polymeric DNA by 19F NMR showed one doublet at -137.2 ppm downfield from the reference (CFCl3). A doublet at -146.9 ppm, characteristic for chlorofluoroacetic acid, an expected product of DNA adduct hydrolysis, was not detected. These results demonstrate the formation of a stable adenine adduct by dihaloketenes in intact calf thymus DNA.

Animals↗

Regulation of an ERG K+ current by Src tyrosine kinase.

The human "ether-a-go-go"-related gene (HERG) K(+) channel, and its homologues are present in heart, neuronal tissue, some cancer cells, and the MLS-9 rat microglia cell line (Zhou, W., Cayabyab, F. S., Pennefather, P. S., Schlichter, L. C., and DeCoursey, T. E. (1998) J. Gen. Physiol. 111, 781-794). Despite its importance, there are few studies of ERG modulation. In this first report of regulation by tyrosine phosphorylation we show that MLS-9 cells express transcripts for r-erg1 (rat homologue of HERG) and r-erg2, and an immunoreactive doublet was identified using an anti-HERG antibody. The constitutive tyrosine phosphorylation of the ERG1 protein, detected by co-immunoprecipitation, was reduced by the protein-tyrosine kinase inhibitors, lavendustin A, herbimycin A, or genistein (but not daidzein). The whole cell ERG current was reduced by protein-tyrosine kinase inhibitors or the Src-selective inhibitory peptide, src40-58, but not by a scrambled peptide. Conversely, the current was increased by the Src-activating peptide, srcpY, but not by an inactive analogue. Activating endogenous Src or transfecting constitutively active v-Src altered the voltage dependence and deactivation kinetics to produce more current at negative potentials. Co-immunoprecipitation identified an association between the channel protein and Src. Thus, r-ERG1 and Src tyrosine kinase appear to exist in a signaling complex that is well positioned to modulate this K(+) channel and affect its contribution to cellular functions.

Adenosine Triphosphate↗

A cytotoxic monoclonal anti-leukemia antibody binds to histone H1.

Monoclonal antibody (MAb) AP64 is a mouse IgM MAb raised against human acute non-lymphocytic leukemia (ANLL) cells. It has been shown to bind to a wide variety of cell lines and is capable of initiating complement (C) dependent cytotoxicity. Other studies indicated that MAb AP64 can effect long term cure in a leukemia minimal residual disease model. By using various techniques we have determined the identity of a protein which is bound by this MAb. Immunofluorescent studies have shown that MAb AP64 stains the nuclei of fixed cells as well as metaphase chromosomes, indicating that this MAb binds to a component of chromatin. Biochemical characterization revealed that MAb AP64 western blots a 31 and 32 kilodalton doublet from NP-40 extracts from both rat and human leukemia cells. The mobility of this doublet is identical under reducing and non-reducing conditions. Further studies have shown that the bands detected by western blot analysis using MAb AP64 as a probe have a similar migration to those of bovine histone H1. Also, 1 nanogram of bovine histone H1 can be detected by MAb AP64 when spotted onto nitrocellulose. These data demonstrate that MAb AP64 binds to a conserved epitope present on molecules coded for by the histone H1 gene family.

Antibodies, Monoclonal↗

Monoclonal antibodies to factor VIII: their application in immunoblotting for the visualization of factor VIII in therapeutic concentrates and plasma.

Two monoclonal antibodies (McAb) termed 12A4 and 19C1 have been raised against human factor VIII. In immunoassays 12A4 bound to factor VIII antigen (VIII:Ag) in plasma but not serum whilst 19C1 bound to VIII:Ag in both plasma and serum. Both McAb were shown by immunoblotting to react with the carboxy (C) terminal polypeptide of factor VIII which appeared as a doublet with a molecular weight (Mr) of 77,000/75,000. The C terminal factor VIII polypeptide was detectable by immunoblotting in each of 12 therapeutic factor VIII concentrates, from six different manufacturers, although its level was variable. Factor VIII was visualized in plasma by immunoblotting following its immunoadsorption and elution from agarose-bound monoclonal antibodies. No Mr 77,000/75,000 bands were detectable in plasma obtained from 13 unrelated CRM- haemophiliacs whilst 11 CRM+ haemophilic plasmas from seven kindred were shown to have a C terminal factor VIII polypeptide of normal molecular size.

Antibodies, Monoclonal↗

The distribution of genes on human chromosomes as studied by in situ nick translation.

We have studied the distribution of potentially active genes on human chromosomes, using two methods: DNAse I hypersensitivity and restriction enzyme--nick translation with enzymes sensitive to methylation of CpG doublets. DNAse hypersensitivity is known to be associated with potentially active genes, and, when the reaction is detected by "in situ" nick translation, produces an R-banding pattern. Digestion of chromosomes with HpaII or CfoI, both of which should preferentially cut unmethylated sequences in the CpG islands associated with the majority of genes, also produces R-banding patterns. Deviations are attributable to overdigestion of the chromosomes, leading to extraction of DNA and loss of the specific sites that were to be detected. Contrary to the results of a number of previous workers, we have failed to demonstrate any differences between the DNAse I hypersensitivity or the degree of methylation of the active and inactive X chromosomes in metaphases from females.

Chromosome Mapping↗

The disposition of the synthetic prostaglandin analogue cloprostenol ('Estrumate') in the rat and marmoset.

1. Following subcutaneous administration of the synthetic prostaglandin analogue [14C]cloprostenol to the rat (200 micrograms/kg), the dose was quantitatively recovered from the excreta: 52% of the dose was present in the urine and 43% in faeces. After intravaginal administration (200 micrograms/kg) 42% of the dose was recovered from the excreta, equally divided between urine and faeces, and 40% (range 25--66%) of the dose was recovered from the site of application. The radiolabelled compounds present in faeces were eliminated initially via the bile. 2. The max. observed plasma concn. of total 14C in the rat was 84 ng equiv./ml at 30 min after subcutaneous administration of cloprostenol (200 micrograms/kg). A component which co-chromatographed with cloprostenol on t.l.c. was rapidly cleared from plasma with a half-life of 54 min. After intravaginal administration of cloprostenol (200 micrograms/kg), low and persistent plasma concn. of 14C were detected. 3. The metabolic fate of cloprostenol in the rat and marmoset has been studied with radiolabelled and non-labelled drug mixed such that fragments detected by mass spectrometry exhibited characteristic 12C:14C isotope clusters. Metabolites derived from cloprostenol contained these characteristic doublets. 4. In the rat cloprostenol is metabolized by beta-oxidation to tetranor-cloprostenol. Unchanged cloprostenol and a conjugate of tetranor-cloprostenol were minor urinary metabolites. In the rat biotransformation of cloprostenol in the cyclopentane ring occurred; the tetranor acid of 9-keto-cloprostenol was identified in urine. In the marmoset unchanged cloprostenol and dinor-cloprostenol were major urinary components.

Animals↗

Phosphorylation of the rat hepatic polymeric IgA receptor.

In vivo labeling with [35S]cysteine has identified three transmembrane forms of the rat hepatic polymeric IgA receptor: (i) a 105-kDa core glycosylated precursor; (ii) a terminally glycosylated 116-kDa intermediate; and (iii) a mature 120-kDa form. In the current study we show that the 120-kDa form is phosphorylated. After in vivo labeling with [32P]orthophosphate, all receptor forms were immunoprecipitated from hepatic total microsomes (TM) (with an antireceptor antiserum), separated by NaDodSO4/PAGE, and detected by autoradiography. The 120-kDa form was selectively phosphorylated, whereas the 116- and 105-kDa forms incorporated no detectable 32P. To determine the topology of the phosphorylation sites, hepatic TM isolated from rats labeled in vivo with either [35S]cysteine or [32P]orthophosphate were treated with trypsin. TM were solubilized and receptors were immunoprecipitated from lysates. With increasing trypsin concentrations, the [35S]cysteine-labeled receptor triplet was degraded to a trypsin-resistant doublet of approximately 95 and 85 kDa, indicating that approximately 20 kDa was removed from the receptor endodomain by trypsin. The same treatment removed all detectable 32P from labeled receptors. Furthermore, no 32P was detected in the 80-kDa biliary form of the receptor. Serine was identified as the only phosphorylated residue in acid hydrolysates of 32P-labeled immunoprecipitated receptor. These findings indicate that (i) the 120-kDa form is the only phosphorylated species of the receptor; and (ii) the phosphorylated residues are serine(s) located in the endodomain of the protein.

Animals↗

Steady-state levels of G-proteins and beta-adrenergic receptors in rat fat cells. Permissive effects of thyroid hormones.

Thyroid hormones exert a permissive influence on the ability of cells to respond to other hormones. In hypothyroidism, stimulation of adenylate cyclase by beta-adrenergic agonists is impaired in rat fat cells, whereas inhibition by adenosine is potentiated. The effects of thyroid status on steady-state levels of the G-protein subunits alpha-Go, alpha-Gi, and beta-G35/36 were investigated using specific antibodies and quantitative immunoblotting of rat fat cell membranes. The amount of alpha-Go (Mr 39,000, alpha-G39) detected in fat cell membranes of euthyroid rats was 44 +/- 5 pmol/mg of membrane protein (n = 5). In the hypothyroid state, the amount of the alpha-subunits of Gi (Mr 41,000, alpha-G41) and Go were found to be markedly increased in comparison to the control. The steady-state level of alpha-G41 and alpha-G39 increased more than 50 and 70%, respectively, in the hypothyroid state. The beta-subunit of G-proteins of rat fat cells appears as a doublet of proteins with Mr = 35,000/36,000 on sodium dodecyl sulfate-polyacrylamide gels. The amount of beta-G35/36 detected in fat cell membranes of euthyroid rats was 0.20 +/- 0.03 nmol/mg of protein (n = 5) and was found to increase by about 60% in the hypothyroid state. Administration of triiodothyronine in vivo (short term hyperthyroidism) resulted in a decrease in the amounts of alpha-G41 and alpha-G39 subunits (25 and 20%, respectively). In contrast to these effects of thyroid hormones on Go and Gi, the steady-state level of beta-adrenergic receptors was not significantly altered by changes in thyroid status. Thus, thyroid status in vivo can modulate the steady-state levels of specific G-proteins.

Adipose Tissue↗

Two-dimensional gel analyses of the 24-kDa cap binding protein from poliovirus-infected and uninfected HeLa cells.

The 24-kDa cap binding protein (CBP) from uninfected, mock-infected and poliovirus-infected HeLa cell extracts was isolated by m7GTP affinity chromatography and examined by isoelectric focusing followed by SDS-PAGE. Two major species (pI 6.7 and 7.1) and two minor species (pI 6.5 and 6.8) were found in all cases. Preparations from postribosomal supernate (S200) and the supernate from 0.5 M KCl washed ribosomes (RSW) also demonstrated these same four species. We conclude that there are no detectable differences between ribosome-associated and soluble 24-kDa CBP and that the 24-kDa CBP is not detectably altered by poliovirus infection. We also report the presence of a previously undescribed 16-kDa polypeptide(s) doublet that copurifies with the 24-kDa CBP from uninfected, mock-infected and poliovirus-infected HeLa cells.

Carrier Proteins↗