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Biomedical subjects

M Philipp

Publications and source records attributed to M Philipp.

At least 127 records · Page 7Linked to original sources
PubMed1984

Identification of an antigen of Onchocerca volvulus of possible diagnostic use.

Adult Onchocerca volvulus worms obtained by enzyme digestion from nodules of infected Mexicans were radio-isotope labelled by the chloramine-T or Bolton-Hunter methods. No antigenic determinants were detected in extracts of worms labelled by the chloramine-T method but 3 antigens were detected in extracts of the Bolton-Hunter labelled worms. Two were present in such small amounts that it was impractical to investigate them further, but a major component of mol. wt 20 kDa was purified by gel filtration and used in a serological survey of inhabitants of villages in Southern Mexico. Using the 20 kDa antigen, which is superficially located on both sexes of O. volvulus, sera from both non-endemic and endemic regions were analysed by radio-immunoprecipitation of this antigen. In Southern Mexico, the average sensitivity of the test was 92%, and the specificity 98%. Whilst the 20 kDa antigen did not detect antibodies in the sera of Trinidadians infected with Wuncheria bancrofti or Mansonella ozzardi, this antigen detected high levels of antibodies in Indians exposed to W. bancrofti.

Animals↗
PubMed1984

Surface proteins of a filarial nematode: a major soluble antigen and a host component on the cuticle of Litomosoides carinii.

The surface composition of three stages in the life cycle of Litomosoides carinii, a filarial parasite of rodents, has been studied using radio-iodination techniques. Confirmation that radiolabelled components were confined to the parasite surface was achieved using light and electron microscope autoradiography. Biochemical analysis of extracts of radiolabelled parasites by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) revealed that one major component (mol. wt. 55 000) could be solubilized with the aid of detergents. This component, which was present on male and female adult worms and on post-parasitic third stage larvae, accounted for about one-third of the total proteins available for surface iodination, and was antigenic in infected hosts. The remaining surface components could be solubilized only with urea and SDS under reducing conditions. The 55 000 mol. wt. surface antigens of male and female adult worms exhibited identical two-dimensional tryptic maps, but the similar 55 000 mol. wt. antigen of post-parasitic third stage larvae was different. There was, however, some sharing of antigenic determinants between adult and larval surface components. The principal protein present in detergent extracts of surface-radio-labelled blood microfilariae was host serum albumin.

Animals↗
PubMed1983

Kinetics of subtilisin and thiolsubtilisin.

Subtilisin is a bacterial serine protease with a broad specificity in the S1 subsite. It has been very extensively studied using a variety of kinetic and physical techniques. A chemical derivative, thiolsubtilisin, has been subjected to similar studies in order to analyze the effects of the OH to SH conversion on enzyme activity. The native structure of thiolsubtilisin is indicated by a variety of physical techniques. Oligopeptides bind nearly equally well to both enzymes, and a peptide chloromethylketone is much more reactive to thiolsubtilisin than to subtilisin. Both enzymes have a similar level of activity towards activated nonspecific amides and esters. However, thiolsubtilisin is inactive towards highly specific peptide amides and esters. Thiolsubtilisin also does not show good binding to boronic and arsonic acids. The observation that these transition state analog inhibitors bind poorly to thiolsubtilisin while other compounds bind nearly equally well to both enzymes suggests that thiolsubtilisin may not be able to stabilize the transition state during acylation by specific substrates.

Acylation↗
PubMed1983

[3-year catamneses of psychosomatically treated chronic headache syndromes].

Follow-up examination was carried out on 25 patients having suffered from severest head-ache syndromes for an average of 21.8 years. Three years after a six-week in-patient psychosomatic treatment these patients showed stable rates of improvement with regard to frequency and intensity of persistent head-ache, frequency and intensity of paroxysmal head-ache, use of analgetics, and neurotic complaints like phobic anxiety, depressive symptoms, and inhibition of aggression. These findings established the effectiveness of the therapeutic concept which we had developed in this context. This concept does not concern attempts at intervening in the pathogenetic backgrounds of isolated attacks of pain. The approach starts out with the psychosomatic conditions for the disposition to suffer pain.

Adult↗
PubMed1982

Non-covalent interactions result in aggregation of surface antigens of the parasitic nematode Trichinella spiralis.

Surface antigens of three stages of the nematode worm Trichinella spiralis has been labelled with iodine and examined by sodium dodecyl sulphate (SDS)/polyacrylamide-gel electrophoresis under reducing and non-reducing conditions. A variety of interactions were defined: the infective larva surface antigens formed a spectrum of aggregates from 50kDa to greater than 1000kDa from subunits of 47kDa and 90kDa; in the adult worms of 60kDa complex arose fron interaction between two dissimilar molecules of 40kDa and 20kDa; the new-born larvae components formed homologous dimers from a 58kDa molecule. Aggregating molecules were adherent to lentil lectin-Sepharose and are therefore glycoproteins. The interactions observed were completely abolished by boiling in SDS/mercaptoethanol, but only partially destroyed by boiling in SDS/iodoacetamide. Based upon this, the associations can be characterized as non-covalent, but disulphide-bond-dependent. It is suggested, but not proved, that the aggregates arise from strong non-covalent hydrophobic interaction sites which are stabilized by intrachain disulphide bonds in the molecules concerned.

Animals↗
PubMed1981

Immune response to stage-specific surface antigens of the parasitic nematode Trichinella spiralis.

Rats were infected with the nematode Trichinella spiralis and the primary serum antibody response to antigenic surface proteins of infective larvae, intestinal worms, and newborn larvae was studies. 1 wk after infection, the sera contained antibodies to surface antigens of both infective larvae and intestinal worms. These early sera, however, failed to react with newborn larvae surface antigens. In addition, adsorption of sera with living intestinal worms or infective larvae removed antibodies to surface antigens of the homologous stage only. Finally, the time-course of appearance of antibodies that mediate eosinophil adherence to the surface of each stage of the parasite. We concluded that in a primary infection in rats, the surface proteins of T. spiralis used in this study are antigenically stage specific. Furthermore, they could be targets for the stage-specific, antibody-dependent eosinophil-mediated destruction of this parasite, known to occur in vitro.

Animals↗
PubMed1981

Characterization of surface antigens of Trichinella spiralis infective larvae.

Infective larvae of trichinella spiralis were surface-labelled with radioactive iodine, and the products were characterized biochemically and immunochemically. The labelled material was restricted to two basic subunits: a lentil lectin-adherent glycoprotein (GP), mol. wt 47K, and a lentil lectin-nonadherent protein fraction (P), mol. wt 55K. Both of these form homologous dimers through as yet unspecified covalent bonds to yield GP90 and P105. GP is further polymerized into higher molecular weight forms by disulphide bond-dependent associations. suggesting a highly cross-linked arrangement in the cuticle. To what extent this structure contributes to the overall organization of the cuticle remains to be established. The two labelled surface molecules are immunogenic in the infected host, and do not react with a panel of sera taken from animals chronically infected with other nematode species. The approach therefore offers immediate possibilities for immunodiagnosis in nematode infections, and for a comparative immunochemical study of the surface cuticle of different stages of the same and different nematode species and for studies of the function of the nematode cuticle.

Animals↗
PubMed1980

Changing proteins on the surface of a parasitic nematode.

Most of the organisms of the phylum Nematoda are free living, but some are animal or plant parasites of major importance to man. During their life cycle all nematodes undergo a series of moults in which they shed an external cuticle, consisting of an outermost membrane-like layer of unknown composition and a series of fibrillar layers similar to collagens. Because of this structure, the cuticle has been viewed as an acellular exoskeleton with rather inert molecular components. However, observations have shown that it contains enzymes and sometimes haemoglobin, and that nutrients are absorbed through it in the infective larvae and adut stages of Brugia pahangi. It is bound by complement and antibody, resulting in the adherence of leukocytes, and antibody-dependent cell-mediated reactions damage the cuticle of newborn larvae of Trichinella spiralis and the microfilariae of Dipetalonema viteae and Litomosoides carinii. We report here that the surface of the cuticle of the parasitic nematode Trichinella spiralis expresses protein molecules which change qualitatively following the moulting process, and quantitatively during growth of the worms within one stage. Also, surface proteins are released in vitro at a rate which depends on the conditions of culture of the worms.

Animals↗
PubMed1980

Preparation of immobilized phosphodiesterase from calf spleen and its use in oligonucleotide analysis.

The phosphodiesterase from calf spleen (EC 3.1.4.18) was immobilized on several supports. Some properties of the most suitable enzyme support system--calf spleen phosphodiesterase bound to agarose-Concanavalin A--were investigated, e.g., pH dependence, influence of ionic strength of the buffer medium, and Zn2+-ion inhibition. The immobilized spleen phosphodiesterase showed about 60% of the activity of the free enzyme; the activity toward several oligonucleotide test substrates was unchanged for two months.

Animals↗
PubMed1980

Non-stepwise methods in the preparation of building blocks for polynucleotide synthesis.

Oligonucleotide fragments of the general sequence ABn, BnC and ABnC as building units for polynucleotide synthesis can be obtained by three types of reactions, namely the sequence-specific co-condensation of nucleic acid constituents, the sequence-specific degradation of copolymers and the limited addition of nucleotides to primers. Examples for these reactions are described and the scope and application of the approach discussed.

Base Sequence↗
PubMed1979

Comparison of the kinetic specificity of subtilisin and thiolsubtilisin toward n-alkyl p-nitrophenyl esters.

The p-nitrophenyl esters of straight-chain fatty acids were used as substrates of the enzyme subtilisin Novo (EC 3.4.4.16) and its chemically produced artificial enzyme thiolsubtilisin. Subtilisin and thiolsubtilisin pH--activity profiles were determined, and kinetic effects of the active site O-S substitution were observed. Among the substrates tested, both enzymes show highest specificity with p-nitrophenyl butyrate. It was also found that subtilisin is more sensitive to changes in substrate chain length than is thiolsubtilisin. Second-order acylation rate constants (k2/Ks) are remarkably similar for both enzymes. However, thiolsubtilisin deacylation rate constants and Km values are lower than analogous subtilisin constants. While thiolsubtilisin deacylation rate constants give a pH profile identical with that of subtilisin, the pH profile of thiolsubtilisin acylation rate constants shows an active site pK value lowered from the subtilisin pK of 7.15 and exhibits an inflection point at pH 8.45, which is absent in subtilisin.

Binding Sites↗
PubMed1979

[Endocrinological prediction of the responsiveness of depressive patients to lofepramine (author's transl)].

In a pilot study of 15 depressive patients of the neurotic and endogenous type we could show that some neuroendocrinological parameters are apt to predict the thymoleptic efficacy of lofepramine. These parameters, which were measured with a simple global stimulation test (insulin hypoglycaemia combined with injection of TRH and LHRH), were as follows: high basal blood glucose; high hypoglycaemic blood glucose; high decrease of blood glucose in comparison to the basal level; low basal TSH; low increase of HGH and low increase of cortisol after hypoglycemia. A synopsis of these parameters allowed a correct classification of 14 out of 15 patients according to therapy response and therapy resistance.

Adult↗