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Biomedical subjects

M H Dresden

Publications and source records attributed to M H Dresden.

13 recordsLinked to original sources
PubMed1992

Cysteine proteinases from Schistosoma haematobium adult worms.

To identify and characterize cysteine proteinases from Schistosoma haematobium, lyophilized adult worms were homogenized, and enzymes were isolated and purified. From extracts prepared in acidic buffer, 3 putative cysteine proteinases were identified either directly or indirectly. The first proteinase (ShCP1) was identified by labeling with a radioiodinated inhibitor, Z-Tyr-Ala-CHN2, as a 35-kDa protein. However, it could not be detected by silver staining, amino acid sequencing, or by a monoclonal antibody specific for a similar molecule from Schistosoma mansoni. A second cysteine proteinase, ShCP2, was purified by gel filtration and dialysis. This 32-kDa molecule was thiol-dependent and was labeled with Z-Tyr-Ala-CHN2. The amino terminal amino acid sequence of ShCP2 showed remarkable similarity (up to 77%) to that of S. mansoni cathepsin B (SmCP2) as well as to mammalian cysteine proteinases. Both ShCP1 and ShCP2 reacted with polyclonal antibodies against S. mansoni, suggesting the existence of shared antigenic epitopes. A third activity, ShCP3, was identified as possibly a distinct proteinase based on its similarities to a 28-kDa cysteine proteinase from S. mansoni. This preliminary investigation demonstrates that the overall profile of cysteine proteinases in S. haematobium is very similar to that of S. mansoni.

Amino Acid Sequence↗
PubMed1979

Selection of a chemically defined medium for culturing adult newt forelimb regenerates.

Three commercially available tissue-culture media were evaluated for their ability to support continued growth and differentiation of 14-day regenerates of adult newt forelimbs. Serums, embryo extracts, egg ultrafiltrates, and antimicrobial agents were avoided in this analysis. The hormones insulin and L-thyroxine were added to these chemically defined media to enhance continued cellular metabolism and growth. The optimum conditions appeared to be cultivated at 25 degrees C (pH 7.2 to 7.4) in media osmotically adjusted to conditions approximating amphibian blood values (i.e. 225 m0SM for 199, 244 m0SM for CMRL-1066, and 262 m0SM FOR L-15).

Animals↗
PubMed1979

Acidic thiol proteinase activity of Schistosoma mansoni egg extracts.

Extracts of the eggs of the human blood fluke, Schistosoma mansoni, exhibit proteolytic activity which requires the presence of added thiol reagents or cyanide. The pH optimum for hydrolysis of Azocoll and cartilage proteoglycan is 4.8--5.2 and the molecular weight of the major component is 25--26,000. The effects of inhibitors suggest this activity belongs to the acidic thiol proteinase class, with a similarity to Cathepsin B. These proteinases may be involved in nutrition of the egg or sporocyst, in penetration of eggs or miracidia through host tissues, or in the immunopathology of schistosomiasis.

Animals↗
PubMed1977

Schistosoma mansoni: inhibition of cercarial "penetration" proteases by components of mammalian blood.

1. Normal human sera and plasma were fractionated in order to identify inhibitors of the "penetration" proteases of Schistosoma mansoni cercariae. 2. The main inhibitor, accounting for 90% of the total activity of serum, appears to be alpha 1-antitrypsin (alpha 1-AT) as identified by separation on DEAE-cellulose and Sephadex, by immunoelectrophoresis and by anticercarial protease activity of purified alpha 1-AT preparations. 3. The inhibition profiles of purified preparations of the 6 known serum antiproteases suggest that the parasite protease is similar to vertebrate chymotrypsin. 4. On a molar basis, the order of inhibitory activity against the cercarial protease is: alpha 1-AT = alpha 2-macroglobulin; C'-1-inactivator; alpha 1-antichymotrypsin. No inhibition was obtained with inter-alpha-inhibitor or antithrombin III.

Animals↗
PubMed1977

Schistosoma mansoni: effects of zinc on cercarial and schistosomule viability.

The effects of ZnCl2 on the viability and morphology of cercariae and schistosomules of Schistosoma mansoni were examined. The longevity of cercariae was inversely proportional to the zinc concentration from 0.05 to 5 micronM. Zinc caused body-tail separation and crenation of bodies but not of tails of cercariae, as well as alteration of the staining of cercariae in the indirect immunofluorescence test. Zinc was also effective in reducing penetration of cercariae into mice in a brief (10 min) exposure period. Although the effects on schistosomule morphology were not as conspicuous as with cercariae, 5mM ZnCl2 also affected this stage of the parasite.

Animals↗
PubMed1976

Regenerative abnormalities in Notophthalmus viridescens induced by repeated amputations.

The fidelity of the regenerative response in the adult newt, Notophthalmus viridescens, was examined following repeated amputations at the level of the distal one-third of humerus. Three to four months following amputation, all regenerates were scored for gross morphology, reamputated, and stained with methylene blue for skeletal elements. The occurrence of abnormal regeneration with respect both to gross morphology and to skeletal structure was found to increase directly with the number of times the limb stumps were required to initiate dedifferentiation and repair. The initial amputation-regeneration process produced structurally normal replacement limbs in 91% of the cases examined. Reamputations of 4-digit regenerates (3--4 months after the previous transection) resulted in structurally abnormal regenerates in 28% of the cases following two amputations; 50% of the cases following three amputations; 65% of the cases following four amputations; and 81% of the cases following five amputations. The relationships between repeated dedifferentiation, proliferation, and redifferentiation and normal limb development are discussed.

Amputation, Surgical↗
PubMed1975

Disruption of normal forelimb regeneration in adult Notophthalmus viridescens by sublethal concentrations of trypan blue.

The effects of the vital dye trypan blue (TpB) on the regeneration of amputated newt forelimbs were examined. Administration of the dye (10 mug/g body weight) via IP injection during the early wound healing and dedifferentiation phases of regeneration inhibited the normal regenerative response. The accumulation phases of regeneration are similarly halted but only by greater concentrations of TpB (50 mug/g body weight) while redifferentiation and morphogenesis are only affected by still greater concentrations of the dye (100 mug/g body weight). In addition to abolishing the regenerative response, low levels of TpB were also capable of inducing skeletal abnormalities in the regenerates as might be expected from previous reports on the teratogenicity of the dye. The in vitro action of newt hyaluronidase (as well as purified testicular hyaluronidase) on hyaluronate was diminished by TpB, with virtually complete inhibition observed at initial reaction mixture concentrations of 100 mug/ml. The results of this study suggest that TpB acts to disrupt the normal regenerative response by preventing dedifferentiation and remodeling, perhaps by inhibition of various necessary lytic enzyme functions or by interference with normal intercellular communications.

Animals↗