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A Dubin

Publications and source records attributed to A Dubin.

At least 37 records · Page 2Linked to original sources
PubMed1996

The intracellular serpin family.

The serpins are widely distributed, structurally related family of proteins with diverse functions. Most of the known serpins are proteinase inhibitors, the majority being found as secreted species, however, there are a few that occur intracellularly and their physiological role remains unknown. Most of the intracellularly occurring serpins have been classified into the ovalbumin subfamily. The possible phytogenetic tree of 14 intracellular serpins is presented.

Phylogeny↗
PubMed1996

Evidence for the presence of different alpha-1-proteinase inhibitor genes products in mouse plasma.

The plasma alpha-1-proteinase inhibitor (API) of three mouse species Mus domesticus, M. caroli and M. pahori was isolated. Each of the species isoforms were then separated by chromatofocusing; however, no significant differences in association rate constants toward human neutrophil elastase and bovine chymotrypsin were observed. The amino-acid sequence of the P'1-P'15 C-terminal fragments of the API variants indicate that mouse plasma contains at least two different active API isoforms in the case of M. domesticus (five API genes) but only one active API isoform in M. pahori and M. caroli (one API gene).

Amino Acid Sequence↗
PubMed1996

Biosynthesis and distribution of leucocyte elastase inhibitor. Production of recombinant inhibitor.

The horse leucocyte elastase inhibitor (HLEI), present in neutrophils, monocytes and bone marrow cells, is apparently a cytoplasmic protein which is not released from cells even in response to stimulation with lipopolysaccharide, phorbol ester, tumour necrosis factor alpha, interleukin-1 or elastin degradation products. Although no expression of the inhibitor was detected in neutrophils, both monocytes and bone marrow cells were efficient in its synthesis. Using a new expression vector pREST5d, recombinant inhibitor was produced in a large quantity in a soluble form, with a yield of 88 mg per 10 litres of E. coli culture. A two-step purification procedure, consisting of ion-exchange chromatography and gel filtration, yielded 36 mg of the recombinant inhibitor of a purity higher than 95%, as judged by SDS/PAGE. The recombinant protein had physicochemical and kinetic properties indistinguishable from those of the natural one, including irreversible elastase inhibition with an association rate constant kass > 10(7) M-1s-1. Both proteins were eliminated from rat circulation at the same ratio, and within the first 20 min 70% of the protein was removed. Such a short half-life in the circulation suggests that local delivery of HLEI directly to lungs in the form of aerosol could be a more efficient therapeutic approach than its intravenous injection.

Animals↗
PubMed1994

Structural and functional characterization of elastases from horse neutrophils.

In order better to understand the pathophysiology of the equine form of emphysema, two elastinolytic enzymes from horse neutrophils, referred to as proteinases 2A and 2B, have been extensively characterized and compared with the human neutrophil proteinases, proteinase-3 and elastase. Specificity studies using both the oxidized insulin B-chain and synthetic peptides revealed that cleavage of peptide bonds with P1 alanine or valine residues was preferred. Further characterization of the two horse elastases by N-terminal sequence and reactive-site analyses indicated that proteinases 2A and 2B have considerable sequence similarity to each other, to proteinase-3 from human neutrophils (proteinase 2A), to human neutrophil elastase (proteinase 2B) and to a lesser extent to pig pancreatic elastase. Horse and human elastases differed somewhat in their interaction with some natural protein proteinase inhibitors. For example, in contrast with its action on human neutrophil elastase, aprotinin did not inhibit either of the horse proteinases. However, the Val15, alpha-aminobutyric acid-15 (Abu15), alpha-aminovaleric acid-15 (Nva15) and Ala15 reactive-site variants of aprotinin were good inhibitors of proteinase 2B (Ki < 10(-9) M) but only weak inhibitors of proteinase 2A (Ki > 10(-7) M). In summary, despite these differences, the horse neutrophil elastases were found to resemble closely their human counterparts, thus implicating them in the pathological degradation of connective tissue in chronic lung diseases in the equine species.

Amino Acid Sequence↗
PubMed1993

Molecular cloning and expression of an intracellular serpin: an elastase inhibitor from horse leucocytes.

Horse blood leucocytes contain an elastase inhibitor (HLEI) belonging to the serpin family. Poly(A)+RNA isolated from these cells was used to construct a cDNA library in lambda gt10, which was first screened with a synthetic degenerate oligonucleotide probe corresponding to the amino acid sequence of the reactive centre of the inhibitor. Three clones were obtained covering the entire coding region of the protein. Sequencing of these clones showed identity with the amino acid sequence obtained from Edman degradation of the elastase inhibitor. The coding sequence of the HLEI cDNA was cloned into the bacterial expression vector pKK233-2 and expressed in Escherichia coli cells. Transformed bacteria expressed significant amounts of the protein, which was immunoprecipitated with a specific anti-HLEI antiserum. Furthermore, HLEI expressed in bacteria inhibited the activity of elastase but not trypsin.

Amino Acid Sequence↗
PubMed1992

Equine leukocyte elastase inhibitor. Primary structure and identification as a thymosin-binding protein.

The primary structure of an elastase inhibitor located in the cytoplasm of leukocytes obtained from the equine species has been determined. By sequence comparison, the protein was found to be a member of the serpin family with strong identity to plasminogen activator inhibitor-2. In contrast to other serpins this protein contained no carbohydrate and had a blocked amino terminus. Preliminary evidence indicates that the inhibitor has the additional feature of being a thymosin beta 4-binding protein, since this polypeptide was always located in purified preparations of the protein. This suggests a physiological role for cytoplasmic elastase inhibitors in the thymosin beta 4-regulated rearrangement of the cytoskeleton of leukocytes.

Amino Acid Sequence↗
PubMed1992

Gastric intramucosal pH as a therapeutic index of tissue oxygenation in critically ill patients.

Falls in gastric intramucosal pH (pHi) are associated with morbidity and mortality in patients admitted to intensive-care units (ICU). We tested the hypothesis that ICU outcome can be improved by therapy guided by changes in pHi and aimed at improving systemic oxygen availability. We studied 260 patients admitted to ICUs with APACHE II scores of 15-25. After insertion of a gastric tonometer, each patient was randomly assigned to a control or protocol group within the admission pHi category (normal = 7.35 or higher; low = below 7.35). The control groups were treated according to standard ICU practices. The protocol groups received, in addition, treatment to increase systemic oxygen transport or to reduce oxygen demand, whenever the pHi fell below 7.35 or by more than 0.10 units from the previous measurement. The protocol was used, because pHi fell, in 67 (85%) of the protocol group with normal pHi on admission. There were no significant differences between protocol and control groups in demographic characteristics, admission blood gases or haemoglobin concentration, number or type of organ system failures, or the intensity of ICU care. For patients admitted with low pHi, survival was similar in the protocol and control groups (37% vs 36%), whereas for those admitted with normal pHi, survival was significantly greater in the protocol than in the control group (58% vs 42%; p less than 0.01). Therapy guided by pHi measurements improved survival in patients whose pHi on admission to ICU was normal. pHi-guided resuscitation may help improve outcome in such patients by preventing splanchnic organ hypoxia and the development of a systemic oxygen deficit.

Aged↗
PubMed1992

Coordinate loss of growth regulatory factors following castration of rats carrying the Dunning R3327 G prostatic tumor.

Hormonal manipulation of prostate cancer is an effective therapy for metastatic disease. Unfortunately, following an initial response tumors reestablish themselves as hormone independent variants and progress. This study was designed to assess the interrelationship of cytokeratin P (Cyto P), vimentin, epidermal growth factor receptor (rEGF) and tissue testosterone following androgen deprivation therapy. Animals bearing the hormone dependent Dunning R3327 G subline prostatic adenocarcinoma were surgically castrated and progressing tumors from both hormone intact and castrated groups were quantitatively assayed for immunohistologic reactivity against the described markers. The results demonstrate a significant (p < 0.05) decrease in cytokeratin (Cyto P), rEGF and testosterone levels following castration. When the expression of both rEGF and Cyto P are related to the tissue testosterone content, it is observed that the ratio between rEGF and testosterone remains essentially unchanged (0.65 +/- 0.21 to 0.65 +/- 0.41), suggesting that in the Dunning R3327 G subline, rEGF expression is coordinately under androgen control. At least some cytokeratin expression also appears to be particularly sensitive to androgen levels, since the ratio between Cyto P and testosterone decreased from 0.92 +/- 0.39 to 0.35 +/- 0.41 following castration. In contrast, following castration, the expression of vimentin was unaffected.

Adenocarcinoma↗
PubMed1991

Proteolytic inactivation of alpha-1-anti-chymotrypsin. Sites of cleavage and generation of chemotactic activity.

The effect of several microbial and mammalian proteinases on the inhibitory activity of human plasma alpha-1-anti-chymotrypsin (alpha-1-Achy) has been tested. Most of these enzymes caused rapid inactivation of the inhibitor by cleavage at single sites within the reactive-site loop between P5 Lys and P3' Leu, with additional cleavages also being detected in some cases near the NH2 terminus of the native protein. In contrast, two of the enzymes tested failed to inactivate alpha-1-Achy, although they could cause removal of peptides near the NH2 terminus. Studies of neutrophil chemotaxis revealed that native or NH2-terminally truncated alpha-1-Achy was not stimulatory. However, testing of two enzymatically inactivated forms of the inhibitor (alpha-1-Achy), cleaved at widely different positions within the reactive-site loop, indicated that they had become potent chemoattractants at concentrations within the nanomolar range. Competition studies using proteolytically inactivated alpha-1-proteinase inhibitor suggested that the chemotactic activity of the two inactivated serpins was probably mediated by the same mechanism. The physiological relevance of this chemotactic activity is underscored by the results of plasma elimination studies which indicate that alpha-1-Achy is eliminated at approximately the same rate as native alpha-1-Achy, thus prolonging chemotactic stimuli within the tissues.

Amino Acid Sequence↗
PubMed1991

GM-CSF restoration of a differentiated (growth factor-regulated) phenotype in an anaplastic tumor.

GM-CSF (granulocyte-macrophage-derived colony-stimulating factor) is a differentiation agent that stimulates bone marrow activity in patients receiving chemotherapy. GM-CSF (1 microgram/ml daily for 10 days), administered intralesionally, was evaluated to determine whether it would restore a more differentiated phenotype to an anaplastic, rapidly growing, hormone-independent variant (R3327 MAT-LyLu) of the Dunning prostatic adenocarcinoma. Immunohistology was used to quantitate the expression of epithelial growth factor receptors (rEGF) and the tissue testosterone content. GM-CSF therapy significantly (P less than 0.05) restored rEGF expression and tissue testosterone to levels associated with better differentiated, slower growing, androgen-dependent Dunning variants (R3327 H and G). GM-CSF may have a role in treatment of prostatic cancers by promoting androgen and epithelial growth factor regulation.

Adenocarcinoma↗
PubMed1991

Purification and biochemical characterization of xanthopterin from patients with chronic renal failure. I. Isolation, purification and preliminary characterization.

We describe the purification and initial characterization of a hitherto unrecognized fluorescence (excitation/emission maxima at 380/440 nm and 400/460 nm) reported from this laboratory in patients with chronic renal failure (Clin Chem 31: 1988, 1985). Purification was achieved using Sephadex G-10 gel chromatography combined with reverse phase and ion exchange high-performance liquid chromatography (HPLC). Purity of the "blue-green" fluorescent compound was determined to be greater than 99% by HPLC, and two-dimensional thin layer chromatography using an acidic and basic solvent system. The excitation/emission maxima were shown to be 390 nm/456 nm, and ultraviolet scans, at pH 1.0, 7.0, and 13.0, gave absorbance optima at 261 nm/356 nm, 278 nm/390 nm, and 255 nm/394 nm, respectively. The isoelectric point of 4.05 in conjunction with the fluorescent and ultraviolet spectra suggests that the fluorophore belongs to the class of compounds known as pteridines.

Chromatography, High Pressure Liquid↗
PubMed1991

Purification and biochemical characterization of xanthopterin from patients with chronic renal failure. II. Biochemical elucidation and structural analysis.

We have identified the primary endogenous fluorescent substance, which has characteristic excitation/emission maxima at 380/440 nm and 400/460 nm, found in the sera of patients with chronic renal failure (Clin Chem 32: 1276, 1988). Preliminary studies, using thin layer chromatography (with cellulose) in conjunction with pteridine standards, indicated that the compound is an unconjugated pteridine. Characterization by gas chromatography-mass spectrometry (electron impact), direct probe-mass spectrometry (electron impact/chemical ionization), and Fourier Transform Infrared analysis showed this compound to be xanthopterin (2-amino 4,6 pteridinedione), an unconjugated pteridine known to be present in man in trace quantities. An authentic sample of this compound had a retention time with high-performance liquid chromatography (HPLC) identical to that of the purified fluorophore. The physiological role of xanthopterin in the pathogenesis of uremia has yet to be elucidated.

Chromatography, Thin Layer↗
PubMed1991

Elastase inhibitor from mammalian neutrophil cytosol.

Bovine, pig and horse leukocyte elastase inhibitors represent the first example of functionally active intracellular serpin. Sequence analysis yields data indicating that the reactive site encompasses P1-P'1 Ala-Met sequence. Oxidation of swine (as well as equine) inhibitor reduced its association rate constants kon with the tested enzymes (by at least 1 order of magnitude). However in case of bovine inhibitor, only a slight reduction has been observed for human neutrophil elastase but not for chymotrypsin or pancreatic elastase.

Amino Acid Sequence↗
PubMed1991

Alpha-1-antitrypsin and alpha-1-antitrypsin-neutrophil elastase complex in bronchoalveolar lavage fluid of patients with pulmonary diseases (pilot study).

A simple method based on rocket and crossed immunoelectrophoresis was adapted for detection of alpha 1 AT-HNE complexes in BALF: Agarose gel with anti-alpha 1 AT combined with intermediate gel containing anti-HNE was used for detection and evaluation of the ratio of complexes with HNE to the free form of alpha 1 AT. BALF samples from 31 patients divided into 5 groups suffering from various respiratory tract diseases were tested. It was found that 3 out of 8 patients with inflammatory pulmonary diseases showed the presence of both forms of alpha 1 AT, 7 out of 13 patients suffering from cancer showed both forms, whereas the complexed form was not detected in any of 8 patients with asthma bronchiale. It is suggested that the presence of alpha 1 AT-HNE complex may reflect, to some extent, the proteolytic status of pulmonary tissue.

Adult↗
PubMed1990

Comparative properties of human alpha-1-proteinase inhibitor glycosylation variants.

Variant forms of human alpha-1-proteinase inhibitor (alpha-1-PI), obtained by the treatment of human Hep G2 cells with specific inhibitors of glycosylation were tested for both inhibitory activity and heat stability. All were found to have the same second-order association rate with human neutrophil elastase, indicating a lack of importance of the carbohydrate moiety. In contrast, incompletely glycosylated forms of alpha-1-PI were found to be heat sensitive relative to the mature protein, suggesting a role for carbohydrate in protein stabilization.

1-Deoxynojirimycin↗
PubMed1990

Septic encephalopathy. Evidence for altered phenylalanine metabolism and comparison with hepatic encephalopathy.

We elected to test the hypothesis that the metabolic encephalopathy associated with systemic sepsis may have a pathogenesis that is similar to hepatic encepathology, ie, as the consequence of hepatic dysfunction that induces alterations in synthesis of catecholic and noncatecholic neurotransmitters. Eleven patients with septic encephalopathy were compared with nine patients with septic encephalopathy and nine normal controls with respect to blood and cerebrospinal fluid (CSF) amino acid profile, phenylethylamine and its metabolite phenylacetic acid, and blood ammonia. Blood and CSF levels of phenylacetic acid increased markedly in septic and hepatic encephalopathy while CSF phenylethylamine levels were not increased in either condition, presumably due to rapid turnover. The CSF concentrations of all the aromatic amino acids were increased in hepatic encephalopathy, whereas in the patients with sepsis, only phenylalanine levels were increased. Evidence of stimulated neutral amino acid transport into brain was demonstrated in hepatic not septic encephalopathy and appeared to correlate with the CSF glutamine concentration. Blood ammonia levels were increased in hepatic but not in septic encephalopathy. Our data support the hypothesis that metabolites of phenylethylamine contribute to encephalopathy in systemic sepsis and hepatic failure; however, the entities differ in other respects.

Ammonia↗