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At least 325 records · Page 18Linked to original sources
PubMed1983

Immune reactions to Wuchereria bancrofti infections in Tanzania. I. Serum-mediated adherence of leucocytes to microfilariae in vitro, using serum from different groups of patients.

Studies on serum-mediated adherence of leucocytes to microfilariae of Wuchereria bancrofti in vitro were carried out in an area of Tanzania endemic for filarial infections. Patients were divided into age-matched groups according to parasitological and clinical conditions. No adherence was seen with serum from microfilariae-positive patients (with or without clinical disease). A slightly, but not statistically significantly, higher prevalence of adherence-positive sera was found among hydrocele patients (27%) and lymphangitis/elephantiasis patients (33%) than among endemic control patients (20%). These three positive groups exhibited a marked difference in age distribution of prevalence of positivity, with very high prevalences found among young hydrocele patients (48%) and old lymphangitis/elephantiasis patients (63%). The hydrocele fluid from hydrocele patients with adherence-positive serum also mediated adherence.

Adolescent↗
PubMed1986

Efficiency of papain-treated microfilariae of Wuchereria bancrofti (var. pacifica) as antigen for serodiagnosis of bancroftian filariasis in French Polynesia.

Papain-treated microfilariae of Wuchereria bancrofti have been used as antigen for indirect fluorescent assay: 0% of non-endemic sera, 8% of healthy exposed Polynesians, 48% of clinical patients and 96% of microfilaraemic subjects were positive by this test. The geometric mean titres were 22, 41, 147 and 605 respectively. Untreated microfilariae were unsuitable for diagnostic purposes. Dirofilaria immitis adult sections showed low reactivity, giving poor discrimination between non-endemic and microfilaraemic sera. The geometric mean titres were 6 and 61 respectively.

Antigens, Helminth↗
PubMedDate not supplied

Serum-dependent interaction of granulocytes with Onchocerca volvulus microfilariae in generalized and chronic hyper-reactive onchocerciasis and its modulation by diethylcarbamazine.

The adherence and cytotoxicity of granulocytes to microfilariae of Onchocerca volvulus were examined in vitro. Reactivity and modulation by diethylcarbamazine of isolated eosinophilic and neutrophilic granulocytes from patients with generalized and chronic hyper-reactive onchocerciasis (sowda or localized form) from endemic foci in Liberia were evaluated under varying serum conditions. In the presence of pooled sera from patients with generalized onchocerciasis granulocytes from both polar groups of patients exhibited similar adherence rates, whereas immobilization rates were higher for eosinophils than for neutrophils. In localized onchocerciasis, the use of autologous serum resulted in a significant decrease in adherence and immobilization rates for both eosinophils and neutrophils. After preincubation of eosinophils, but not of microfilariae, with diethylcarbamazine autologous serum-mediated adherence and cytotoxicity were enhanced to rates similar to those found with pooled serum from individuals with generalized onchocerciasis. These results suggest that granulocytes from both forms of onchocerciasis did not differ with respect to their anti-parasitic reactivity and that antibodies as well as additional serum factors appear to contribute to the functional activity of these effector cells. The findings indicate that predominantly eosinophils, compared to neutrophils, damage the larvae of O. volvulus and support earlier observations which suggest that diethylcarbamazine influences the effector cells rather than the parasite itself.

Adolescent↗
PubMed1988

Antibodies to diethylcarbamazine cross-react with microfilariae of Wuchereria bancrofti.

Antibodies directed against the microfilarial sheath have been instrumental in the immune elimination of circulating microfilariae in human lymphatic filariasis. We report here that antibodies to diethylcarbamazine (DEC, the most commonly used anti-filarial drug) cross-react with the sheath of Wuchereria bancrofti microfilariae. Antibodies with reactivity to DEC were raised in rabbits by immunization with a conjugate of methylpiperazine carboxylic acid (MPCA, an acid hydrolysis product of DEC) coupled to bovine serum albumin. The reactivity of these antibodies with microfilarial sheath of W. bancrofti was demonstrated by indirect immunofluorescent assay and indirect immunoperoxidase assay. This reactivity could be effectively inhibited by pre-incubation of the antisera with different haptens such as DEC, MPCA or piperazine citrate.

Animals↗
PubMed1994

Comparative study of hemolymph phenoloxidase activity in Aedes aegypti and Anopheles quadrimaculatus and its role in encapsulation of Brugia malayi microfilariae.

Hemolymph phenoloxidase activity of sugar-fed and blood-fed females of Anopheles quadrimaculatus and Aedes aegypti showed similar characteristics. Phenoloxidase was present as an inactive proenzyme in both mosquito species and was partially activated during collection of the hemolymph. In both mosquito species, phenoloxidase activity was modulated by different buffers and activated phenoloxidase did not need Ca2+. Enzymatic activity was higher in the hemocytes than in the plasma in both mosquito species. Trypsin, laminarin, and blood-feeding on uninfected and Brugia malayi-infected jirds enhanced hemolymph phenoloxidase activity in both mosquito species. The appearance of hemolymph phenoloxidase activity was inhibited by p-nitrophenyl p'-guanidinobenzoate HCl, soybean trypsin inhibitor, ethylenediaminetetraacetic acid, diethyldithiocarbamic acid, saturated 1-phenyl-2-thiourea and reduced glutathione, but not by benzamidine in A. quadrimaculatus. The appearance of hemolymph phenoloxidase activity was inhibited by benzamidine, diethyldithiocarbamic acid, saturated 1-phenyl-2-thiourea, reduced glutathione, p-nitrophenyl p'-guanidinobenzoate and soybean trypsin inhibitor, but not by ethylenediamine-tetraacetic acid in A. aegypti. It is suggested that in both mosquito species, blood-feeding and migration of sheathed microfilariae in the homocoel activated the prophenoloxidase in the hemolymph and caused the encapsulation and melanization of microfilarial sheaths and microfilariae of B. malayi.

Animals↗
PubMed1989

The acid phosphatase activity and morphological characteristics of Dipetalonema dracunculoides (Cobbold, 1870) microfilariae.

The acid phosphatase activity and some morphological characteristics of Dipetalonema dracunculoides microfilariae are described. Their morphological features are closely related to those of the pathogenic Dirofilaria immitis when Knott's technique is used for the microfilarial diagnosis. The acid phosphatase activity pattern found in Dip. dracunculoides microfilariae is clearly different from those previously described for D. immitis, D. repens and Dip. reconditum.

Acid Phosphatase↗
PubMed1989

Distribution of Onchocerca spp. microfilariae in the dermis of cattle.

A grid was drawn on a lateral half of 10 hides, from cattle infected with both Onchocerca gutturosa and Onchocerca lienalis, which were obtained from an abattoir in central Florida. Paired 7-mm diameter skin cores were taken from 24 grid sites on each hide and microfilariae (mff) extracted to determine their distribution. The only consistent pattern distribution was that mff were recovered from all 10 hides at four sample sites along the ventral midline near the umbilicus. Microfilariae were also frequently found in large numbers along the dorsal cervical midline and in the region of the tarsal and carpal-metacarpal joints.

Abattoirs↗
PubMed2001

Histochemical differentiation of Dirofilaria immitis, Dirofilaria repens and Acanthocheilonema dracunculoides microfilariae by staining with a commercial kit, Leucognost-SP.

The diagnosis of canine heartworm infection is based upon the presence of circulating Dirofilaria immitis microfilariae or on techniques for the detection of serum antibodies or antigens. In the first of these, discrimination between D. immitis, D. repens and Acanthocheilonema dracunculoides microfilariae is based upon the acid phosphatase histochemical stain. In this paper, we propose an alternative technique for histochemical staining using a commercial kit test of naphthol-AS-OL (Leucognost-SP). This offers the advantages of speed and simplicity as compared to the standard Barka procedure.

Acid Phosphatase↗
PubMed1983

Cryopreservation of Dirofilaria immitis microfilariae and third-stage larvae.

Microfilariae of Dirofilaria immitis retained their infectivity for susceptible mosquitoes after cooling to -196 degrees C in the presence of 5% dimethylsulphoxide (Me2SO) using a two-step cooling sequence. Motility and in vitro development of cryopreserved microfilariae also compared favourably with unfrozen controls. Third-stage larvae frozen by the same cooling sequence in the presence of either 5% Me2SO or 16% hydroxyethyl starch were motile upon thawing. Thawed larvae completed the third- to fourth-stage moult in vitro at a frequency approximately 5 to 10% of that seen in unfrozen controls.

Aedes↗
PubMed1983

Onchocerca raillieti: adult location and skin distribution of the microfilaria in Sudanese donkeys.

Onchocerca raillieti is the only Onchocerca species infecting Sudanese donkeys; it occurs only in the ligamentum nuchae, especially in the lamellar part of the ligament. The morphological features of both uterine and skin microfilariae were determined. Skin microfilariae are shorter than uterine ones and tend to accumulate in the regions of Linea alba and withers of infected donkeys. The possible identity of the vector of this worm in the Sudan is discussed.

Animals↗
PubMed1985

Immunity to Onchocerca lienalis microfilariae in mice. II. Effects of sensitization with a range of heterologous species.

The model of Onchocerca lienalis microfilariae (mff) injected into CBA and T.O. strains of mice has been used to examine immunity to skin-dwelling microfilariae following exposure to a range of species of helminths. Mice which had received a primary infection with O. cervicalis mff were significantly resistant to challenge with O. lienalis mff (58% reduction relative to challenge controls). Immunization with the uterine contents (eggs and mff) of O. lienalis, O. gutturosa or O. volvulus conferred equivalent levels of protection against challenge with O. lienalis mff (66 to 75%). Similar results were obtained with immunizations in mice that employed either fresh or freeze-killed eggs of O. gutturosa. Significant reductions in the recoveries of O. lienalis mff were also demonstrated following the intraperitoneal implantation of adult male worms of O. gutturosa (30 to 52%), the adults of either sex of Dipetalonema viteae (60%), or after infection with Trichinella spiralis (27 to 81%). Infections with the trematode, Schistosoma mansoni, had a negligible effect on mff recoveries. It is concluded that partial resistance in mice to Onchocerca mff may be stimulated by factors, yet to be determined, that are neither stage nor species-specific.

Animals↗
PubMed1976

Studies with Brugia pahangi. 14. Intrauterine development of the microfilaria and a comparison with other filarial species.

The intrauterine development of Brugia pahangi embryos was followed from after fertilization to birth, using light and electron microscopy. The origin and development of the sheath of the microfilaria and its possible role in the nutrition of the developing embryo were particularly investigated. Comparisons were drawn with the intrauterine development of other filarial species. The egg shell of the B. pahangi embryo is distinct from the oolemma and forms the sheath of the microfilaria. It is suggested that the electron dense material released by cells of the uterine wall and passing along the channels between the egg shells of adjacent embryos is nutritive. The death of large numbers of developing embryos in the central uterine lumen is probably caused by overcrowding as their size rapidly increases, leading to nutritional deficiency.

Animals↗
PubMed1984

Activation in vitro of some biological systems by extracts of adult worms and microfilariae of Dirofilaria immitis.

Extracts of Dirofilaria immitis adults and microfilariae cause the degranulation of mast cells in rat mesentery when applied in vitro and also cause increased vascular permeability in guinea-pigs and rabbits. Adult worms but not microfilariae are able to activate complement in vitro and both stages contain a plasminogen activator. No proteolytic activity or haemolysins could be detected in either stage. The possibility that these factors may be important in the pathogenesis of dirofilariasis and in the adverse drug reactions that may follow treatment of microfilaraemic animals with diethylcarbamazine is discussed.

Animals↗
PubMed1984

Separation of viable microfilariae free of blood cells on Percoll gradients.

A consistent and reproducible method is described for isolating pure populations of microfilariae of Litomosoides carinii, Brugia pahangi, B. malayi and Dipetalonema viteae, free of cells, from blood, by density gradient centrifugation on Percoll in 0.25 M sucrose. The recovery of the microfilariae was 85 to 97%.

Animals↗
PubMed1981

Dipetalonema viteae: ultrastructural study on the in vitro interaction between rat macrophages and microfilariae in the presence of IgE antibody.

The in vitro interaction between rat peritoneal macrophages and Dipetalonema viteae microfilariae in the presence of amicrofilaraemic rat immune serum was studied by transmission electron microscopy. The probable sequence of events leading to the killing of D. viteae microfilaria by macrophages is as follows. (a) Rat peritoneal macrophages in the presence of amicrofilaraemic rat immune serum adhere to the parasite surface, (b) the macrophages extend their pseudopodia around the parasite, (c) the 'lysosome-like' granules discharge their contents on to the parasite surface, (d) the lytic activity of these products begins at the parasite surface and (e) subsequent breaking of the microfilarial cuticle occurs, exposing the parasite intracellular material.

Animals↗
PubMedDate not supplied

Platelets mediate the action of diethylcarbamazine on microfilariae.

More than 400 million people in the world are infected by filarial parasites leading to a wide range of pathologies. Although introduced in 1947, the mainstay of the therapy and control of the filariases is diethylcarbamazine (N,N-diethyl-4-methyl-1-piperazine carboxamide; DEC), the mode of action of which still remains unknown despite widespread use and intensive laboratory investigations. The marked contrast between an extremely rapid action in vivo and the absence of any significant activity on microfilariae in vitro is unique among chemotherapeutic agents. DEC has been thought to modify the surface layer of the microfilariae and expose them to immunological cell-mediated lysis. This report provides the first evidence that the effect of DEC is mediated by blood platelets with the additional triggering of a filarial excretory antigen (FEA). The killing mechanism is antibody-independent and involves the participation of free radicals.

Animals↗
PubMed1994

Activity of albendazole-ivermectin combination and other filaricidal drugs against infective larvae, preadult, microfilariae and adult worms of Molinema dessetae in the rodent Proechimys oris.

The efficacy of albendazole-ivermectin combination was tested an adult and developing stages of Molinema dessetae in the rodent Proechimys oris. Albendazole and ivermectin, both given alone, suramin and diethylcarbamazine were used as reference compounds. The drug combination (albendazole at 10 mg/kg/ day x 5 days and Ivermectin at 0.04 mg/kg/day x 5 days) was effective against infective larvae and preadult worms, and substantially reduced the number of live adult worms. The known filaricidal agents, diethylcarbamazine (400 mg/kg twice daily x 5 days), ivermectin (0.2 mg/kg/day x 5 days), and suramin (40 mg/kg/day x 5 days), as well as albendazole (50 mg/kg/day x 5 days) were active on infective larvae, preadult worms, microfilariae and adult worms. All drugs had the same level of efficacity on infective larvae. Albendazole had the highest efficacy against adult and preadult worms and diethylcarbamazine was the most active on microfilariae. Although the drug combination was not as effective against preadult and adult worms as albendazole alone, the results indicate that albendazole-ivermectin combination at a low dose had prophylactic effect and suggest a possible macrofilaricidal activity.

Administration, Oral↗
PubMed1984

Peritrophic membrane formation in three temperate simuliids, Simulium ornatum, S. equinum and S. lineatum, with respect to the migration of onchocercal microfilariae.

Engorged females of three temperate simuliid species, Simulium ornatum, S. lineatum and S. equinum, were collected immediately after their bloodfeeds from a cow host. Midguts were dissected out at selected time intervals thereafter, from two minutes to 24 hours post engorgement (p.e.) and peritrophic membrane formation observed. There was an initial rapid secretion of peritrophic membrane (PM) material from the midgut epithelium. The peritrophic membrane produced is Type 1, being formed by delamination from the entire midgut epithelium. This secretory phase continued for approximately two hours p.e. in all three species and was followed by a period of organization within the membrane. At between 12 and 24 hours p.e., the PM appeared more organized and was associated with the formation of several distinct laminae in both S. ornatum and S. lineatum, although in S. equinum it consisted of only a single homogenous layer. Both the rate of secretion and the resulting morphological appearance of the PM appeared species-specific and there was great variation in its thickness in all three species at all time intervals examined. It is suggested that microfilariae penetrate the PM during the initial period of its secretion before it has condensed to form a distinct structure. Furthermore, the migration of microfilariae may be restricted to, or enhanced by, the presence of very thin areas within the membrane where erythrocytes lie almost adjacent to the midgut epithelium.

Animals↗