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G Murphy

Publications and source records attributed to G Murphy.

At least 307 records · Page 17Linked to original sources
PubMed1991

Tissue inhibitor of metalloproteinases-2 inhibits the activation of 72 kDa progelatinase by fibroblast membranes.

We report that monolayers of human fibroblasts stimulated with concanavalin A were able to activate 72 kDa progelatinase but not 95 kDa progelatinase. The activating capacity of fibroblasts appeared approx. 6 h after concanavalin A stimulation and was blocked by cycloheximide. The activation of 72 kDa progelatinase was readily inhibited by TIMP-2 but only poorly by TIMP-1. Plasma membranes isolated from the fibroblasts were capable of activating 72 kDa progelatinase. The cleavage products of the plasma membrane-mediated activation of 72 kDa progelatinase corresponded to those of organomercurial-induced self-cleavage. Only inhibitors of metalloproteinase self-cleavage inhibited the activating capacity of plasma membrane preparations, although the activating capacity was destroyed by trypsin and heat. As with the fibroblast monolayers, TIMP-2 was a potent inhibitor of the membrane-mediated activation whereas TIMP-1 was less so.

Binding Sites↗
PubMed1991

Cleavage of cartilage proteoglycan between G1 and G2 domains by stromelysins.

Normal and pathological turnover of proteoglycans in articular cartilage involves its cleavage close to the N-terminal G1 domain responsible for aggregation. A fragment containing G1 and G2 N-terminal domains of pig cartilage proteoglycans was therefore used as a substrate to investigate its degradation by the metalloproteinase stromelysin and related recombinant stromelysin enzymes. The stromelysins produced an apparent single cleavage yielding a G1 fragment of 56 kDa and a G2 fragment of 110 kDa. Rabbit bone stromelysin was much more active against the G1-G2 fragment and against proteoglycan aggregates than recombinant human stromelysin-1 and stromelysin-2. All metalloproteinase preparations were active against proteoglycan and the G1-G2 fragment at acid (pH 5.5) and neutral pH (7.4). N-terminal sequencing of the G2 fragment derived from the action of recombinant human stromelysin-1 revealed that cleavage between G1 and G2 occurred at the N-terminal end of the interglobular domain, close to the last cysteine in G1. The specific cleavage site was between an asparagine and a pair of phenylalanine residues, where the asparagine corresponds to residue 341 in human and rat mature core protein sequence.

Amino Acid Sequence↗
PubMed1991

The N-terminal domain of tissue inhibitor of metalloproteinases retains metalloproteinase inhibitory activity.

Recombinant tissue inhibitor of metalloproteinases (TIMP-1) and a truncated version containing only the three N-terminal loops, delta 127-184TIMP, have been expressed in myeloma cells and purified by affinity chromatography and gel filtration. delta 127-184TIMP was found to exist as two main glycosylation variants of molecular mass 24 kD and 19.5 kDa and an unglycosylated form of 13 kDa. All forms of the truncated inhibitor were able to inhibit and form complexes with active forms of the matrix metalloproteinases, indicating that the major structural features for specific interaction with these enzymes resides in these three loops. Stable binding of delta 127-184TIMP to pro 95-kDa gelatinase was not demonstrable under the conditions for binding of full-length TIMP-1.

Amino Acid Sequence↗
PubMed1991

The purification of tissue inhibitor of metalloproteinases-2 from its 72 kDa progelatinase complex. Demonstration of the biochemical similarities of tissue inhibitor of metalloproteinases-2 and tissue inhibitor of metalloproteinases-1.

Human gingival fibroblasts in culture were shown to secrete a 72 kDa progelatinase, of which a proportion in the medium was found to be complexed with tissue inhibitor of metalloproteinases-2 (TIMP-2). A purification procedure was devised to purify free enzyme and inhibitor. We also describe the purification of both 95 kDa progelatinase bound to TIMP-1 and free 95 kDa progelatinase from the medium of U937 cells. A polyclonal antiserum to TIMP-2 was prepared and it was shown that TIMP-1 and TIMP-2 are antigenically distinct. The ability to form stable complexes and the relative inhibitory activities of TIMP-1 and TIMP-2 towards 95 kDa and 72 kDa gelatinases, collagenase, stromelysins 1 and 2 and punctuated metalloproteinase were determined; only minor differences were found. Complex-formation between TIMP-2 and 72 kDa progelatinase was demonstrated not to reduce the metalloproteinase-inhibitory activity of TIMP-2, a finding that led to the characterization of high-molecular-mass TIMP activity. Competition experiments between progelatinases and active gelatinases for TIMPs indicated that the affinity of TIMPs for progelatinases is weaker than that for active gelatinases. In a study of the effects of TIMP-1 and TIMP-2 on progelatinase self-cleavage we found that both TIMP-1 and TIMP-2 inhibit the conversion of 95 kDa and 72 kDa progelatinases and prostromelysin into lower-molecular-mass forms. TIMP capable of complexing with progelatinase was shown to be no more efficient an inhibitor of gelatinase self-cleavage than TIMP not able to complex with progelatinase.

Amino Acid Sequence↗
PubMed1991

Isolation and characterisation of a chicken gelatinase (type IV collagenase).

The proform of chick gelatinase (type IV collagenase) was isolated and purified to a high specific activity of 12,071 U/mg from cultured embryonic skin fibroblasts stimulated with cytochalasin-B. The enzyme was activated in the presence of 4-aminophenylmercuric acetate with a fall in molecular weight from 66,000-58,000 on non-reducing polyacrylamide gel electrophoresis and was active over the pH range of 6.0-8.9 against a number of substrates. Further biochemical characterisation showed that the organomercurial activated form of the enzyme behaved like a typical mammalian gelatinase, actively degrading gelatin, soluble type I collagen, collagenase generated type I fragments, type IV collagen (producing 3/4 and 1/4 fragments) and type V collagen, whilst having little effect on laminin. The enzyme was inhibited by metal chelators such as EDTA and 1,10-phenanthroline, but not by inhibitors is suggested that this may be TIMP-2. An antiserum was raised to the proenzyme and was found to localise intra- and extra-cellularly in both tissue sections and cell cultures.

Animals↗
PubMed1991

Matrix metalloproteinase degradation of elastin, type IV collagen and proteoglycan. A quantitative comparison of the activities of 95 kDa and 72 kDa gelatinases, stromelysins-1 and -2 and punctuated metalloproteinase (PUMP).

The abilities of the matrix metalloproteinases 95 kDa and 72 kDa gelatinases (type IV collagenases), stromelysins-1 and -2 and punctuated metalloproteinase (PUMP) to degrade insoluble elastin, type IV collagen films and proteoglycan have been compared. The gelatinases and PUMP were markedly more active in the degradation of elastin than were the stromelysins. PUMP and the stromelysins were more potent proteoglycan-degrading enzymes. All of the enzymes studied degraded soluble native type IV collagen, but the gelatinases were more effective at higher temperatures. These quantitative data allow an analysis of the potential relative roles of these metalloproteinases in the breakdown of the key components of connective tissue matrices.

Cell Line↗
PubMed1991

Purification of recombinant human prostromelysin. Studies on heat activation to give high-Mr and low-Mr active forms, and a comparison of recombinant with natural stromelysin activities.

Recombinant human prostromelysin was purified in a single step using Procion Red-Sepharose chromatography. The purified prostromelysin was self-activated to high-Mr (45,000) and low-Mr (28,000) forms by incubation at 55 degrees C without the addition of extraneous activators. The two forms of stromelysin were subsequently separated, again using Procion Red-Sepharose. Both of the heat-activated recombinant forms demonstrated similar specific activities (for the macromolecular substrates casein, gelatin, elastin, proteoglycan and type IV collagen) when compared with either heat- or trypsin-activated natural stromelysin. The heat-activated recombinant stromelysins both showed similar abilities to potentiate activation of human procollagenase when compared with trypsin-activated natural stromelysin.

Amino Acid Sequence↗
PubMed1991

Immunization with haptenized, autologous tumor cells induces inflammation of human melanoma metastases.

Twenty-four patients with metastatic melanoma were treated with a novel form of active immunotherapy, autologous tumor cell vaccine conjugated to the hapten, dinitrophenyl. This approach is based on the idea, well established in animal systems, that presentation of tumor antigens in the context of a strongly immunogenic hapten augments the development of immunity to those antigens. After being sensitized to dinitrophenyl, patients were given injections of dinitrophenyl-vaccine every 28 days following pretreatment with low dose cyclophosphamide. The vaccine induced a striking inflammatory response in superficial metastases in 14 of 24 patients, consisting of erythema, swelling, warmth, and tenderness over tumor masses. Immunohistochemistry and flow cytometric analysis of biopsy specimens showed marked infiltration with lymphocytes, the majority of which were CD8+, HLA-DR+ T-cells. These observations suggest that a T-cell-mediated immune response against melanoma-associated antigens was facilitated by the "helper" effect of the anti-hapten response.

Antibodies, Monoclonal↗
PubMed1991

Proteolytic inactivation of human alpha 1 antitrypsin by human stromelysin.

alpha 1 Antitrypsin (alpha 1AT) is the main physiological inhibitor of neutrophil elastase, a serine protease which has been implicated in tissue degradation at inflammatory sites. We report here that the connective tissue metalloproteinase, stromelysin, cleaved alpha 1AT (54 kDa), producing fragments of approximately 50 kDa and 4 kDa, as shown by gel electrophoresis. The cleavage of alpha 1AT was accompanied by inactivation of its elastase inhibitory capacity. Isolation of the 4 kDa fragment by reversed-phase HPLC, followed by N-terminal amino acid sequencing, demonstrated that the cleavage of alpha 1AT occurred at the Pro357-Met358 (P2-P1) peptide bond, one peptide bond to the N-terminal side of the inhibitory site. We suggest that stromelysin may potentiate the activity of neutrophil elastase by proteolytically inactivating alpha 1AT.

Amino Acid Sequence↗
PubMed1991

Fatal pulmonary venoocclusive disease secondary to a generalized venulopathy: a new syndrome presenting with facial swelling and pericardial tamponade.

We describe a patient who developed fatal pulmonary artery hypertension secondary to diffuse venulitis. This otherwise healthy young woman first presented with generalized venulopathy, with chemosis, facial swelling, pleural effusions, and pericardial tamponade. The symptoms partially responded to steroid therapy, but over a 2-year course, a rapidly progressive and fatal venoocclusive disease developed. No other primary condition was diagnosed, and at autopsy, the patient had striking venulitis throughout, including the pulmonary bed. We believe that this is a unique case of pulmonary hypertension resulting from a generalized venulopathy.

Adult↗
PubMed1991

Intelligence, motor skills and behaviour at 5 years in early-treated congenital hypothyroidism.

The cognitive functioning, motor skills and behaviour of 5-year-old children with early-treated congenital hypothyroidism was assessed. The study group was 57 children with congenital hypothyroidism (CH) diagnosed by neonatal screening in N.E. and N.W. Thames regions between 1978 and 1981 along with 51 non-affected controls matched for age, sex, social class and language background. Small differences in I.Q. and behaviour between the patients and the controls were not statistically significant. However, children with CH showed significant deficits in motor skills (M 79.9 SE 3.7) compared to the controls (M 99.8 SE 4.0) (P = 0.0003). Deficits were particularly marked for balance. In addition, children with more severe hypothyroidism at diagnosis (Plasma thyroxine less than 20 nmol/l) did significantly less well in respect to I.Q. and motor skills than those with less severe hypothyroidism (plasma thyroxine greater than 60 nmol/l). These findings provide further evidence for the importance of the severity of hypothyroidism in determining the outcome for intelligence and motor skills in children with early-treated congenital hypothyroidism. Deficits in motor skills, particularly in relation to balance, suggest that early impairment of the vestibular system may occur despite early treatment.

Child Behavior↗
PubMed1991

Treatment of dermatomyositis with intravenous gammaglobulin.

PURPOSE: The mainstay of pharmacologic therapy in patients with dermatomyositis is corticosteroids. However, because patients sometimes become refractory to these drugs and because these drugs have potential short- and long-term toxicities, alternate therapy is highly desirable. Therefore, a pilot study was initiated using high-dose intravenous gammaglobulin (IVGG) in the treatment of dermatomyositis. PATIENTS AND METHODS: IVGG was administered to five patients with juvenile dermatomyositis. Prior to IVGG treatment, all patients had persistent muscle weakness despite daily corticosteroids and three patients had developed unacceptable steroid toxicity. Two of the patients had previously developed toxicity while receiving immunosuppressive therapy. RESULTS: IVGG therapy resulted in improved muscle strength and ameliorated skin rash in all patients. The percentage increase in muscle strength as measured by sphygmomanometry following the 9-month course of IVGG ranged from 56% to 606% in the proximal lower extremities and from 30% to 186% in the proximal upper extremities. Following IVGG therapy, prednisone could be discontinued or the dose reduced in all patients. CONCLUSION: This study suggests that IVGG may allow steroid sparing in dermatomyositis and may provide a safe alternative to cytotoxic therapy.

Adrenal Cortex Hormones↗
PubMed1991

Nonuniform variation in band pattern with luminol/horseradish peroxidase western blotting.

When optimized, the peroxidase-catalyzed oxidation of luminol can provide a useful, sensitive detection system for Western blotting. However, while the luminescence from intense bands appears rapidly, faint bands require at least 30 min after removal of the membrane from reaction buffer for maximum luminescence to develop. This can result in the detection of a variant band pattern if films are exposed to the blotted membrane too soon after reaction, while exposure later after reaction can result in the preferential detection of faint bands. As a consequence, in order to detect a range of bands similar to that seen using autoradiographic or chromogenic systems, it is necessary to determine the correct time after the initiation of the luminol reaction for film exposure. These effects are due to enhancement of luminescence as a result of the peroxidase-immunoglobulin conjugate binding to a solid phase.

Autoradiography↗
PubMed1991

Uremic tumoral calcinosis: preliminary observations suggesting an association with aberrant vitamin D homeostasis.

Periarticular tumoral calcification is a unique form of soft tissue calcification that occurs infrequently in patients with end-stage renal disease. The mechanism underlying such massive periarticular calcifications is unknown. The radiographic similarity between uremic tumoral calcifications and those found in hereditary tumoral calcinosis, a disorder of calcitriol and phosphorus homeostasis, caused us to examine whether abnormalities in vitamin D metabolism were associated with uremic calcinosis as well. We examined two uremic subjects with massive periarticular tumoral calcifications and found that they had inappropriately high serum calcitriol levels for the degree of renal function, hyperparathyroidism, and hyperphosphatemia. The source of calcitriol could not be identified in one subject, but likely was derived from granulomatous tissue in the other. In the subject with marrow granulomas, we found that calcitonin administration further stimulated calcitriol production. Although epidemiological studies are needed to confirm this preliminary association between calcitriol and uremic tumoral calcinosis, our observations suggest that normal serum calcitriol levels in association with hyperphosphatemia may be a contributing factor in the development of this rare disorder.

Adult↗
PubMed1991

A clonal CD4-positive T-cell line established from the blood of a patient with Sézary syndrome.

The reported inability to establish long-term T-cell lines from the blood of cutaneous T-cell lymphoma patients with circulating neoplastic T cells has hindered the development of an in vitro system to investigate Sézary syndrome. We have established a rapidly proliferating T-cell line from the peripheral blood of a patient with Sézary syndrome, which expresses a mature helper T-cell phenotype and contains cytogenetic abnormalities and T-cell receptor gene rearrangements identical to those in the patient's blood. The method of establishment and characteristics of this line are described.

Aged↗
PubMed1991

Molecular differences between human and experimental pancreaticobiliary diversion-induced rat pancreatic neoplasia.

A series of molecular changes are now known to be seen in human pancreatic neoplasia, including the very frequent mutational activation of Kirsten ras oncogene at codon 12, overexpression of the epidermal growth factor receptor, and abnormalities of c-erbB-2 expression. In order to determine whether similar changes can be seen in animal models of pancreatic cancer a molecular analysis of tumours induced in rats by pancreaticobiliary diversion was performed. The polymerase chain reaction was used to amplify portions of the rat Kirsten ras gene and sequence specific oligonucleotide hybridisation was used to define whether sequences were wild type or mutant. No evidence of mutation was found in the Kirsten ras gene at codons 12 or 61, where activating mutations are known to occur. In addition immunohistochemical methods were used to investigate expression of c-erB-2 and the epidermal growth factor receptor but no evidence of abnormal expression was found. We conclude that there are major molecular differences between human and experimental rat pancreatic cancer.

Amino Acid Sequence↗