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H Zahner

Publications and source records attributed to H Zahner.

At least 19 recordsLinked to original sources
PubMed1997

Expression of the microfilarial sheath protein 2 (shp2) of the filarial parasites Litomosoides sigmodontis and Brugia malayi.

The microfilarial sheaths of the filarial parasites Brugia malayi, Brugia pahangi, and Litomosoides sigmodontis consist of several parasite proteins, probably ranging between 7 and 10. The gene encoding sheath protein 2 (shp2), which is the object of this study, is transcribed in embryos and in the uterine epithelium; at least in B. malayi, it is translated in both tissues. Apparently, shp2 is synthesized as a monomer, exported by the respective cells, and integrated into the microfilarial sheath. In the sheath, it exists as a highly polymerized molecule cross-linked by cysteine formation and other covalent bonds, presumably epsilon-(gamma-glutamyl)-lysine links.

Animals↗
PubMed1997

Ivermectin-induced killing of microfilariae in vitro by neutrophils mediated by NO.

Rat neutrophil granulocytes isolated after intraperitoneal casein injection of the donors exhibit high cytotoxic efficacy in vitro against microfilariae of Litomosoides carinii in the presence of ivermectin. Optimum effects of 80-90% killing of microfilariae were obtained with 100 ng ivermectin per milliliter and a microfilariae: cell ratio of 1:100. Spleen cells killed approximately 30% of the microfilariae under these conditions. Cytotoxic effects were independent of any adherence of the cell to the larvae. In contrast to the effects of spleen cells, cytotoxicity of neutrophils completely abrogated when cells and targets were separated by a membrane impermeable for the cells, suggesting a very short-living mediator in the latter case. Correspondingly, cytotoxic effects of neutrophils were completely inhibited by the addition of the arginine analogues NG-monomethyl-L-arginine and L-canavanine, indicating the involvement of reactive nitrogen intermediates. The nitric oxide scavenger hemoglobin also protected the microfilariae. Several compounds which are known to interfere with reactive oxygen intermediates were ineffective. An excess of ferrous ions in the medium in the presence of a reducing agent significantly reduced the cytotoxic efficacy of neutrophils.

Animals↗
PubMed1997

Renal disease in lymphatic filariasis: evidence for tubular and glomerular disorders at various stages of the infection.

Brugia malayi-infected patients, endemic normals with high levels of specific antibodies and European controls were investigated for kidney disorders by noninvasive techniques. Groups of patients with filarial infections included asymptomatic, microfilaraemic cases (group 1), patients with filarial fever (group 2) and with obstructive filariasis (group 3). Several patients underwent a treatment course with diethylcarbamazine (DEC) when blood and urine samples were collected. Urine samples were investigated for proteinuria and analysed by SDS-PAGE to discriminate between proteinurias caused by tubular and glomerular disorders. In addition, urine levels of alpha-1 microglobulin, of the brush border antigen gp400 and of N-acetyl-beta-glucosaminidase (NAG) activity were determined as indicators of tubular disorders, the albumin content of the urines served as indicator of glomerular alterations. IgG rheuma factors were also determined in the serum as possible reasons for glomerulonephritis. Neither in the endemic normals nor in the European controls there was evidence for kidney disorders. Infected patients had significantly increased proteinuria compared to controls. There were no significant differences between the 3 groups of infected persons, although the mean protein levels were highest in cases with chronic disease and lowest in asymptomatic patients. Quantitative urine analyses and results of accompanying tests suggest predominantly tubular but generally relatively weak disorders in asymptomatic infections; abundant involvement of the kidney which involves both compartments of the organ in the course of filarial fever; and partly severe and probably chronically progredient kidney alterations, which predominantly affect the glomerula in symptomatic cases. IgG rheuma factors do not seem to play a role in filarial infection associated renal disease. DEC-treatment indeed did not significantly alter degree and character of the proteinuria, but relatively high albumin levels in the urine of treated persons yet suggest increased glomerular disorders in these cases. In conclusion, renal disease appears to be a common event in Brugia filariasis; involving both the tubular and glomerular compartment of the organ its pathogenesis is obviously complex and not only immune complex-mediated.

Acetylglucosaminidase↗
PubMed1997

Infection of BALB/c mice with the filarial nematode Litomosoides sigmodontis: role of CD4+ T cells in controlling larval development.

Litomosoides sigmodontis is the only filaria which develops from infective larvae into adults in immunocompetent laboratory mice. Depletion of CD4+ T cells from infected BALB/c mice resulted in worm and microfilarial burdens significantly higher than those of infected controls. Th2 cytokines, eosinophilia, and immunoglobulin E, which were strongly induced in infected controls, were diminished in CD4-depleted mice.

Animals↗
PubMed1995

Brugia spp. and Litomosoides carinii: identification of a covalently cross-linked microfilarial sheath matrix protein (shp2).

A microfilarial sheath protein gene (shp2) coding for the major constituent of the insoluble, cross-linked sheath remnant (SR) from Brugia malayi, Brugia pahangi and Litomosoides carinii has been cloned and sequenced, based on peptide partial amino-acid sequences. All three closely related single-copy shp2 genes in the two genera carry a single intron in identical position; shp2 mRNAs are post-transcriptionally modified by both cis-splicing and trans-splicing. In accordance with their extracellular destinations the encoded proteins include signal peptide sequences; molecular masses of approx. 23 kDa are hence predicted for the mature secreted polypeptides. In their structures sheath matrix proteins shp2 may be regarded as extreme cases of a modular constitution, since these proteins largely consist of two different segments of multiple sequence repetitions, PAA and QYPQAP (or QYPQ), separated by elements of unique sequence. Extreme insolubility and cross-linking are likely to originate from these repetitive sequences within shp2, and to constitute the basic properties of a microfilarial matrix largely consisting of an shp2 network.

Amino Acid Sequence↗
PubMed1995

Induction and prevention of shock-like lethal side effects after microfilaricidal treatment in filariae infected rodents.

In contrast to human carriers of microfilariae, filariae infected rodents generally tolerate an effective microfilaricidal treatment without obvious signs of adverse reactions. The study shows, however, that also the filariae (Litomosoides carinii, Brugia malayi) infected rodent Mastomys coucha can be rendered sensitive to side effects of the treatment by the administration of D-galactosamine (D-Gal), due to reduction of liver UTP levels. Independent of the drug (diethylcarbamazine, ivermectin, CGP 20376) and the parasite species, D-Gal-primed infected animals died within 4 days after a microfilaricidal treatment. Lethal effects did also occur in naive animals to which microfilariae had been transfused 18 h prior to the challenge with D-Gal and a microfilaricidal, provided the animals had received at least approximately 10(3) larvae/g body weight. Both infected animals and naive recipients of microfilariae could be protected from death by cyclosporin A, polyclonal antibodies to mouse TNF or suitable amounts of NG-monomethyl-L-arginine. Pentoxifylline was less protective. The results suggest that components play a role in adverse reactions after microfilaricidal treatment, which are released by dying/dead microfilariae and may interact with T lymphocytes independent of a specific state of immunity. In a sequela, TNF released by T cells seems to induce an excess synthesis of N-oxides which appear to be the final morbific agent.

Animals↗
PubMed1995

In vitro cultivation of third-stage larvae of Brugia malayi to the young adult stage.

The in vitro cultivation of the filarial nematode Brugia malayi from the infective stage to the fourth and the young adult stage is described. Different culture conditions including cell-free systems and co-culture with different human lymphatic cell lines were compared. Cell-free systems reported by others to promote the in vitro development of the parasites to the adult stage failed to work, i.e. the parasite development stopped at the L4 stage and the larvae died after approximately 3 weeks. Cocultivation with each of the cell lines used enhanced the survival of the parasites. The best results were obtained employing the human T cell leukemia line Jurkat and human dermal fibroblasts as feeder cells in RPMI 1640 supplemented with 10% heat-inactivated human serum. This culture system allowed the cultivation of B. malayi for more than 7 weeks with an average growth of the larvae by factor 6.4 (0.77 +/- 0.035 cm) and a maximum growth by factor 10 (1.2 cm). 69% of the initially cultivated larvae (which corresponded to 100% larvae alive at that time) reached the fourth larval stage after 14 days, and 2.6% of the initially cultivated larvae (which corresponded to 17% of the parasites alive at that day) had reached the young adult stage by day 37 of culture. Parasites remained alive up to 52 days. During the first four weeks of culture, both the length and the periods of moulting of the in vitro cultivated filariae closely resembled those observed with B. malayi in vivo in rodent hosts.

Aedes↗
PubMed1994

Litomosoides carinii microfilarial sheaths: partial amino acid sequences of several major polypeptide constituents.

Isolated sheaths from Litomosoides carinii microfilariae were disintegrated by reduction with dithiothreitol and were 14C-carboxymethylated. Five major sheath proteins thus solubilized were purified by size exclusion chromatography and reversed-phase HPLC (rpHPLC). Proteolytic fragments of complete sheaths and of the single sheath proteins were isolated by rpHPLC and were N-terminally sequenced. A library of 27 partial sheath polypeptide sequences was thus established, 21 of which could be assigned to three L. carinii sheath structural genes (shp1,2, and 3/3a) isolated on the basis of this and of previous amino acid sequence information. The remaining peptides document the presence of at least one additional major sheath constituent.

Amino Acid Sequence↗
PubMed1994

Surface antigens of Litomosoides carinii microfilariae: agglutinating antibodies react with sheath components of 40 and 120 kilo Dalton molecular mass.

This study was conducted to identify surface antigens of the microfilarial sheath of Litomosoides carinii which are accessible to antibodies. Rabbit antisera were raised against the soluble and insoluble fractions of purified sheaths by extracting them with a buffer containing 2-mercaptoethanol and sodium dodecylsulphate. These sera and rabbit hyperimmune sera directed against homogenates of total microfilariae, mature (i.e. microfilariae liberating) female parasites and excretory-secretory products of adult females were able to agglutinate live and formaldehyde-fixed microfilariae. When the antisera directed against sheath constituents were administered to patently infected Mastomys coucha, the microfilaraemia of these animals was rapidly reduced and remained low for a period of 2-3 weeks. Antibodies specifically binding to the microfilarial surface were immunoaffinity-purified on formaldehyde-fixed microfilariae. The antibodies react with sheath antigens of 40 and 120 kDa molecular mass which are produced by the epithelium of the distal uterus of the mature female, secreted and attached to the surface of the sheaths. A 120 kDa antigen recognized by anti-sheath surface antibodies was also detected in the excretory-secretory products of in vitro-cultured immature female L. carinii from day 30 post-infection onwards. In the excretory-secretory products of mature adult female parasites recovered on day 130 post-infection, this 120 kDa molecule was absent. However, material reacting with the antibody was detected in the stacking gel of SDS-polyacrylamide gels. This finding may indicate that the basic units forming the 120 kDa antigen of immature adults or microfilarial sheath surface antigens occur in a highly polymerized form in the excretory-secretory products of mature female parasites.

Agglutination Tests↗
PubMed1994

Litomosoides carinii: macrofilariae-derived glycolipids--chromatography, serology and potential in the evaluation of anthelminthic efficacy.

A preliminary characterization of the glycolipids of Litomosoides carinii macrofilariae, resolved according to their chromatographic, chemical and serological properties, has been performed. Emphasis has been placed on the neutral fraction glycolipids. These are separable on thinlayer chromatography into two groups of fast and slow migrating band components, that differ in their migration, differential chemical staining and serological traits, respectively. Serological analyses have been accomplished by thin-layer chromatography immunostaining and ELISA. Only components of the slow migrating band group react with infection serum from Litomosoides carinii-infected Mastomys coucha. Cross-reactivity experiments with homologous and heterologous infection sera of various helminthiases indicate that, epitopes bound to the neutral glycolipid fraction show structural similarity within the Nematoda, but not to the Cestoda or Trematoda. The dynamic development of specific Ig-, IgG- and IgM-anti-neutral glycolipid fraction antibody levels were correlated with the different progression of L. carinii and Brugia malayi infections in the multimammate rat, Mastomys coucha. The reduction in the dynamics of IgG- and IgM-antibody levels on chemotherapeutic treatment with the filaricides flubendazole and CGP 20376 has been related to their macrofilaricide-activity.

Animals↗
PubMed1994

Ivermectin-induced cell-dependent lethal effects on litomosoides carinii microfilariae in vitro.

Ivermectin affected the motility of Litomosoides carinii microfilariae in vitro in a dose dependent manner but did not completely immobilize the larvae and had no lethal effects when tested up to a concentration of 1000 ng/ml. However, killing of microfilariae was induced by ivermectin in vitro in the presence of spleen cells of Mastomys coucha or rats within 14 h. Optimum effects occurred at drug levels of 10-100 ng ivermectin/ml. Addition of infection serum led to increased cytotoxicity when compared with normal serum. Pretreatment in vitro of L. carinii microfilariae with ivermectin in cell-free medium and subsequent exposure to spleen cells caused also cytotoxic effects which appeared to be accelerated in comparison with simultaneous exposure of microfilariae to ivermectin and cells. Pretreated microfilariae, injected intravenously into naive M. coucha were rapidly eliminated from the blood of the recipients. These results suggest that the microfilariae become altered by the drug and thus susceptible to cell-mediated cytotoxic effects. Cytotoxicity did not depend on the attachment of cells to L. carinii microfilariae and was also induced when targets and effector cells were separated by membranes impermeable for cells. Thus ivermectin-induced cellular cytotoxicity to L. carinii microfilariae is at least partly mediated by soluble factors released by effective cells.

Animals↗
PubMed1994

Antifilarial activity of macrocyclic lactones: comparative studies with ivermectin, doramectin, milbemycin A4 oxime, and moxidectin in Litomosoides carinii, Acanthocheilonema viteae, Brugia malayi, and B. pahangi infection of Mastomys coucha.

The avermectins ivermectin and doramectin and the milbemycins milbemycin A4 oxime and moxidectin were tested for filaricidal activity in Mastomys coucha infected with Litomosoides carinii, Acanthocheilonema viteae, Brugia malayi, and B. pahangi. Single subcutaneous doses of 0.005-5 mg/kg (L. carinii), 0.0005-0.5 mg/kg (A. viteae), 0.5 and 5 mg/kg (B. malayi), and 5 mg/kg (B. pahangi) were injected. Necropsies were performed 42 days after treatment. The avermectins caused a strong and rapid reduction of microfilaraemia in L. carinii and A. viteae infections within a few hours after treatment but showed only moderate efficacies on microfilariae of Brugia spp. The effects of the milbemycin derivatives on L. carinii and A. viteae microfilariae were generally weaker than those of the avermectins. However, moxidectin was comparatively active against microfilariae of Brugia spp. Subsequently the parasitaemia levels of L. carinii and A. viteae infected animals remained either almost completely depressed or tended to reincrease in a dose dependent manner whereas there was generally a continuous decrease of microfilaraemia levels in Brugia spp. infected animals. Adulticidal effects were limited to A. viteae although with neither dose of neither drug > 95% reductions of adult worm counts were reached. However, pathogenic influences of the drugs were observed on intrauterine embryonic stages of the parasites.

Animals↗
PubMed1994

IgG subclasses of the multimammate rat, Mastomys coucha: isolation and characterization of IgG1 and IgG2.

The objective of the study was to characterize the IgG-system of Mastomys coucha and to provide antibodies specific for IgG subclasses of this animal species. Serum proteins binding to protein A at pH 8.0 could be eluted in two distinct peaks at pH 7.5 - 6.2 and pH 5.0 - 3.9. The fractions were analysed by SDS-PAGE and immunoelectrophoresis. Both tests suggested an IgG character of the fractions. Based on their migration behavior in the electric field they were classified as IgG1 (anodic position) and IgG2 (cathodic position). After cleavage of IgG1 and IgG2 with papain, the Fc fragments were isolated by their binding to protein A and used to raise antisera in rabbits. The specificity of these antisera to IgG1 and IgG2 was improved by mutual affinity purification. Subsequently these specific reagents were used for further characterization of IgG1 and IgG2. Thus, affinity chromatography of IgG to protein G allowed a differentiation of IgG1 into two subtypes which either bound to protein G at pH 8.0 or not. In combination with isoelectric focussing and 2-dimensional immunoelectrophoresis the results suggest the occurrence of two and three subtypes of IgG1 (IgG 1a-b) and IgG2 (IgG 2a-c) respectively. A synoptical table of available information on the immunoglobulins of M. coucha including IgM, IgA, IgE and a homocytotropic IgG3 is presented. In addition, serum levels of IgG1 and IgG2 are determined in male and female M. coucha of different ages.

Animals↗
PubMed1993

Experimental chemotherapy of filariasis: comparative evaluation of the efficacy of filaricidal compounds in Mastomys coucha infected with Litomosoides carinii, Acanthocheilonema viteae, Brugia malayi and B. pahangi.

Eleven types/classes of compound with antifilarial activity were comparatively evaluated in Mastomys coucha infected with Litomosoides carinii, Acanthocheilonema viteae, Brugia malayi or B. pahangi. The paper deals with the efficacy of (i) predominantly microfilaricidal compounds [diethylcarbamazine, levamisole, avermectins (ivermectin, milbemycin), nitrofurans (nitrofurantoin, hydroxymethylnitrofurantoin, nifurtimox, furazolidone, furapyrimidone), organophosphorals (metrifonate, haloxon), and aminophenyl-amidines], (ii) predominantly macrofilaricidal compounds [suramin, benzimidazoles (flubendazole, mebendazole, oxfendazole, ciclobendazole, albendazole, cambendazole, fenbendazole), and arsenicals (thiacetarsamide, Mel PH, R7/45)], and (iii) micro- and macrofilaricidal compounds [benzazole derivatives (CGP 20376 and other benzothiazoles) and nitrophenylamines (amoscanate, CGP 6140)]. Minimum effective doses against microfilariae and minimum curative doses against adult filariae as well as detailed data on dose-efficacy relationships are reported for the various drugs. The results obtained in M. coucha are compared with those published for other experimental in vivo filarial systems, thus attempting to describe a general status of in vivo antifilarial activity of the compounds.

Animals↗
PubMed1993

The gene coding for the major sheath protein of Litomosoides carinii microfilariae, gp22, is transcribed in oocytes and embryonic cells.

The transcription and translation of the gene encoding gp22, a major constituent of the microfilarial sheath of the filarial parasite Litomosoides carinii were studied by in situ hybridisation and immunohistology. Transcription of the gp22 gene is confined to oocytes and embryos in the reproductive organs of adult female worms. It starts in oocytes in the rhachis zone, is maximal in multicellular embryos and decreases slowly as the microfilariae develop. Blood microfilariae lack the gp22 transcript. The gp22 gene product is first detectable in parasites recovered on day 32 post infection. Expression of gp22 begins in multicellular embryos in the uteri of mature female worms and can be detected in all further developed intrauterine stages. The gp22 gene product appears to be exported by the embryonic cells and becomes integrated into the sheath where it may contribute to the flexibility of the latter structure.

Amino Acid Sequence↗
PubMed1992

Trans-splicing of an early embryo mRNA in Litomosoides carinii, coding for the major microfilarial sheath protein gp22.

Both genomic and cDNA clones have been isolated encoding the major sheath glycoprotein, gp22, of Litomosoides carinii microfilariae. The mature gp22 mRNA is shown to result from both trans-splicing of a 22-nucleotide 5'-leader sequence to an acceptor site at position 313 of the pre-mRNA, immediately upstream from the start codon, and from cis-splicing of a 117-nt intron located within the coding sequence. Cis-splicing precedes the trans-splicing reaction. The gp22 reading frame of 148 codons has the inferred structure of a prepro-protein and includes a leader peptide and a pro-segment ahead of the known N terminus of the mature, extracellular protein of 105 amino acids. The N-terminal part of that protein contains five repeats of an elastin-related pentapeptide sequence, which, together with a proline-threonine segment between two Cys clusters in the center and at its C terminus, may cause an elongated conformation with an apparent molecular size of 22 kDa in contrast to the calculated M(r) of 11,200.

Amino Acid Sequence↗
PubMed1992

Litomosoides carinii: extraction of the microfilarial sheath components and antigenicity of the sheath fractions.

Microfilarial sheaths of Litomosoides carinii were isolated and extracted with 2% sodium dodecyl sulfate (SDS) and 5% 2-mercaptoethanol (2ME). Extraction with SDS alone did not alter the ultrastructure of the sheaths and yielded five polypeptides (27-67 kDa) that were not recognized by antibodies of infected hosts but reacted with antibodies to host-serum proteins. 2ME treatment caused partial solubilization of the sheaths (45% as determined by amino acid analysis), which could be further improved by combining 2ME with SDS. The remainder showed filamentous/threadlike structures on electron microscopic examination. As compared with whole sheaths, the insoluble proportion was markedly enriched in alanine and cysteine but contained less galactosamine, serine, and threonine. SDS-polyacrylamide gel electrophoresis (SDS-PAGE) of 2ME/SDS-extractable components showed 12-16 bands of 14- greater than 120 kDa. A predominant component had an apparent molecular mass of 22 kDa. Two bands (42 and 120 kDa) could be stained with Coomassie blue but showed "negative" staining when gels were stained with silver. Several components (but not the 22-kDa polypeptide) bore phosphocholine epitopes. Apart from the negatively staining bands, most of the 2ME-soluble sheath components were recognized by antibodies of L. carinii-infected Mastomys coucha. Except for several polypeptides that had been unspecifically recognized by IgM, the antibody response to sheath components started at the end of the prepatent period.

Amino Acids↗