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D Stengel

Publications and source records attributed to D Stengel.

65 records · Page 4Linked to original sources
PubMed1977

Proteolytic activation of rat liver adenylate cyclase by a contaminant of crude collagenase from Clostridium histolyticum.

Treatment of rat liver plasma membranes with various commercial preparations of crude collagenase from Clostridium histolyticum at concentrations as low as 1 mug/ml, resulted in activation of the adenylate cyclase system. Maximal activation occurred at 50 to 100 mug/ml of collagenase, and promoted a 2- to 3-fold increase in the basal activity as well as in the activities stimulated by catecholamines, glucagon, fluoride, or GTP. This was due to an increase in the maximal velocity of the cyclizing reaction without any increase in the affinity of the enzyme for its substrate. Treatment of plasma membranes with crude collagenase did not induce gross structural modifications as judged by electron microscopic examination. 5'-Nucleotidase activity was slightly inhibited and ATPase activity remained unaffected. The stimulatory substance was nondialyzable, thermolabile, and inhibited by both EDTA and -SH reagents, thus appearing to be a protein. The following observations suggest the effects observed were due to other protease(s) present in crude collagenase: (a) only crude collagenase was active on liver adenylate cyclase: treatment with purified collagenase from C. histolyticum or from Achromobacter iophagus gave no stimulation; (b) the stimulatory activity was irreversible since washing of the membranes after treatment was without effect; (c) crude collagenase contained no lecithinase or sphingomyelinase activity under our conditions of adenylate cyclase assay; (d) after chromatography on Sephadex G-100, the activator appeared as a peak in the 30,000-dalton region and was clearly separated from the collagenase and clostripain peaks, but coincident with elastolytic and caseinolytic activities; (e) the effect of crude collagenase could be prevented by addition of elastin in vitro and was mimicked by purified elastase from hog pancreas. It remains to be seen whether the effects observed result from an increase in the catalytic constant of adenylate cyclase, or an unmasking of new catalytic sites.

Adenosine Triphosphate↗
PubMedDate not supplied

Different chromosomal localization of two adenylyl cyclase genes expressed in human brain.

Recently, we characterized a cDNA clone that encodes a human brain adenylyl cyclase (HBAC1). In the present study, we identified a second population of mRNA suspected to encode a new brain adenylyl cyclase (HBA C2). The amino acid sequence of HBA C2 displays significant homology with HBA C1 in the highly conserved adenylyl cyclase domain (250 aminio acids), found in the 3' cytoplasmic domain of all mammalian adenylyl cyclases. However, outside this domain, the homology is extremely low, suggesting that the corresponding mRNA originates from a different gene. We report here the first chromosomal localization of the adenylyl cyclase genes determined by in situ hybridization of human metaphase chromosomal spreads using human brain cDNA probes specific for each mRNA. The probe corresponding to HBA C1 exhibited a strong specific signal on chromosome 8q24, with a major peak in the band q24.2. In contrast, the HBA C2 probe hybridized to chromosome 5p15, with a major peak in the band p15.3. The two cDNAs hybridized at the two loci without any cross reactivity. Thus, in human brain, a heterogeneous population of adenylyl cyclase mRNAs is expressed, and the corresponding genes might be under the control of independent regulatory mechanisms.

Adenylyl Cyclases↗
PubMedDate not supplied

Forskolin requires more than the catalytic unit to activate adenylate cyclase.

Forskolin, a natural diterpene, is a novel, potent activator of a variety of adenylate cyclase systems; its mechanism and site of action are still disputed. We report here that, while forskolin activates liver adenylate cyclase up to 15-fold, it does not activate cyclase of ram sperm which comprises a pure catalytic subunit. However, forskolin activation of sperm adenylate cyclase activity could be observed after reconstitution with the regulatory component-enriched membrane from human erythrocytes. The diterpene weakly (3-5-fold) activated the cytosolic, soluble cyclase found in rat and ram tests, but this effect was lost when the cyclase was purified by gel chromatography. Our data are not compatible with the hypothesis that forskolin acts directly on the catalytic subunit, but rather suggest that it acts via another regulatory component, part of, or different from, the GTP-binding regulatory complex.

Adenylyl Cyclases↗
PubMedDate not supplied

[Osteomyelitis of the carpus and metacarpus].

AIM: Because of the low prevalence, there is poor evidence on the effective management of bone and joint infections of the carpus and metacarpus. We therefore studied the outcomes of patients undergoing surgical treatment at our department. METHOD: We conducted a retrospective study on all patients operated on because of osteomyelitis of the carpus and metacarpus between January 1998 and June 2004. Main study endpoint were the infection control rate at end of treatment and at time of follow-up. RESULTS: Of eleven subjects (nine men, two women) with a median age of 43 years (range, 19 to 79 years) serial débridement with temporary wound closure and surgical fixation proved successful in ten cases. We identified causative pathogens in ten cases (S. aureus: n = 3, P. aeruginosa: n = 3, mixed: n = 4) by intraoperative biopsy. Eight subjects received local or free tissue flaps. A 73 year old man died in hospital. Follow-up information was available for eight patients after a median of 19.5 months (range: 3 to 61 months). Seven of them did not show signs of recurrent infection. CONCLUSION: Adhering to accepted standards of treating osteomyelitis, satisfactory control rates in carpal and metacarpal infection can be achieved while salvaging the hand.

Adult↗