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At least 163 records · Page 9Linked to original sources

PubMed1976

The populatin dynamics of Onchocerca volvulus microfilariae during treatment with suramin and diethylcarbamazine.

During treatment with suramin the numbers of O. volvulus microfilariae in the blood, urine, sputum, and anterior chambers of the eye fell before those in the skin. When diethylcarbamazine (DEC) was given after suramin, increased numbers of microfilariae appeared in the blood, urine, cerebrospinal fluid (CSF) and sputum, but the increase in the blood was less marked, and of shorter duration, than in similar patients receiving DEC without previous suramin. Microfilariae are thought to enter the urine, sputum and CSF directly from the blood by penetrating the capillary walls in the glomeruli, pulmonary alveoli, and choroid plexuses. Those in the aqueous humour do not appear to come directly from the bloodstream. The total numbers of microfilariae in the skin of some heavily infected onchocerciasis patients are estimated, as are the total numbers moving into the blood-stream under the influence of DEC and the proportion which escape into the urine, sputum and CSF. It is concluded that the majority of the microfilariae which appear in the blood during DEC therapy must be destroyed in the body, probably in the liver.

Anterior Chamber↗

PubMed2003

Incidental detection of microfilariae in aspirates from Ewing's sarcoma of bone.

Microfilariae have been reported as coincidental findings with various neoplasms. We present a case in which microfilariae were encountered in fine-needle aspiration (FNA) smears from a 10-yr-old boy who presented with a lytic lesion in the diaphysis of the right tibial bone. Stained aspirates from the swelling were composed of a dispersed population of small round cells with scanty to vacuolated cytoplasm. Two sheathed microfilariae with several nuclei and cephalic and caudal clearing were identified. A diagnosis of Ewing's sarcoma with presence of microfilariae of Wuchereria bancrofti was made. The diagnosis of Ewing's sarcoma was confirmed on histopathology.

Animals↗

PubMed1995

Brugia malayi: localisation and differential expression of extracellular and cytoplasmic CuZn superoxide dismutases in adults and microfilariae.

We have determined the levels of superoxide dismutase (SOD) in different stages of the lymphatic filarial nematode parasite of man, Brugia malayi. Adult male worm extracts showed the highest levels of enzyme activity at 34.5 U mg-1, and there was no significant difference in the overall levels of SOD in extracts of adult female worms and microfilariae (27.1 and 26.7 U mg-1, respectively). SOD activity was detected in the culture medium of parasites maintained in vitro, with particularly high levels of specific activity in media in which males and females were maintained (357 and 339 U mg-1, respectively), indicative of active secretion. In all cases, this was accounted for predominantly by CuZn SOD, assessed by potassium cyanide inhibition. Northern blots with cDNA probes specific for cytoplasmic and extracellular CuZn SODs indicated that levels of mRNA for the cytoplasmic form were similar between adults and microfilariae, whereas expression of the extracellular form was 10x higher in adult worms. Western blots with an antibody to recombinant CuZn SOD demonstrated that higher levels of the extracellular protein were present in adult male worms, whereas the cytoplasmic form was present in roughly equivalent amounts in males, females, and microfilaria. Iodination and immunoprecipitation experiments indicated that the extracellular enzyme was accessible to surface labeling of both male and female adult worms, but not microfilaria. Immuno-electron microscopy showed that CuZn SOD was localised predominantly in the hypodermis of adult parasites, with an asymmetric distribution in the intercordal regions suggestive of compartmentalisation into several distinct syncytia. No labeling was evident in the cuticle, and thus the accessibility of the extracellular enzyme to extrinsic iodination in adult worms remains unclear. No binding of antibody was demonstrable in the glandular region of the oesophagus or the uterus of females, presumed to be major sites of synthesis for secreted proteins. Dense labeling was observed in the seminal fluid surrounding spermatazoa in the vas deferens of male parasites. These data also suggest that, as observed in mammals, nematode spermatazoa are particularly susceptible to oxidative damage and are protected during storage by secreted anti-oxidant enzymes.

Animals↗

PubMed1990

Onchocerca raillieti: release from skin snips, maintenance in vitro and periodicity of microfilariae.

Several media were tested for the release of Onchocerca raillieti microfilariae from skin snips and for their subsequent in vitro maintenance. Tyrode's solution containing 20% equine serum and antibiotics was the best medium tested, followed by phosphate buffered saline. Tyrode's solution alone or distilled water were poor media. A temperature 7-12 degrees C lower than the host's body temperature favoured release of the microfilariae from skin snips. The microfilariae were best maintained at 4-10 degrees C, when they remained alive for up to 5 days. O. raillieti microfilariae had an evening periodicity which could be related to a possible vector's peak of feeding activity.

Animals↗

PubMed1985

[Suppression of the parasitemia in rodent filariasis (Litomosoides carinii) by immunization with BCG and microfilaria. II. Intravenous BCG application].

By intravenous (i.v.) inoculation of living tuberculosis bacteria (BCG) non-specific resistance to microfilariae of Litomosoides carinii (Filarioidea) is induced in cotton rats. This is only possible using the preparation "Immune-BCG Pasteur F" (suspended germs), but not with "Vaccin-BCG pour scarifications" (lyophilized tuberculosis bacteria). After inoculation of Immune-BCG, followed by a challenge infection by 60 infective larvae 6 weeks later, a patent infection develops. However, the level of microfilaraemia is constantly lower than in the control. After challenge infection 12 weeks later, this effect has disappeared. Immune-BCG has no influence on the worm load or the output of microfilariae by the adult worms. If i.v. inoculation of Immune-BCG is combined with a subcutaneous injection of specific antigen--living embryos from the uteri of adult worms--the BCG-activated immune system undergoes specific sensitization. Upon challenge infection 6 weeks later, the microfilaraemia is completely suppressed, but the worm load and production of microfilariae by the adult female worms are normal. If Immune-BCG is injected i.v. 3 days before intraperitoneal injection of freeze-killed microfilariae, there is still constantly reduced microfilaraemia when challenge infection follows 12 weeks later. Obviously, the effect of this relatively weak antigen may be increased by BCG stimulation.

Animals↗

PubMed1982

[Experiments in vitro with Litomosoides carinii (Nematoda: Filarioidea) II. Influence of different sera on the release of microfilariae and experiments on the readiness for copulation of the worms (author's transl)].

When fetal calf serum or human serum is added to the culture medium Tc 199, adult females of Litomosoides carinii release the same amount of microfilariae in vitro as after addition of cotton rat serum. In contrast, in media with serum of Meriones unguiculatus or Mastomys natalensis only a few microfilariae are released; moreover, addition of Mastomys serum immobilizes them. When males and females are kept together, the same amount of microfilariae is released as compared with single females. Worms 4 weeks of age (i.e., about 2 weeks before copulation) maintained in medium Tc 199 with 33% cotton rat serum do not mate (no insemination of the females). However, the females live 18 days (harmonic mean) in vitro and grow on average 5 mm in length (28%) and the males roll up their tails in characteristic manner. Worms 5 or 6 weeks of age kept in pairs for 45 to 6 days in vitro were implanted into cotton rats. In vivo they grew to normal length, copulated and delivered microfilariae into the circulating blood. Females implanted solely into the recipient grew as well but remained sterile; this means that no insemination took place in vitro.

Animals↗

PubMed1988

Comparisons of glucose and amino acid use in adults and microfilariae of Brugia pahangi.

With [U-14C]glucose we confirmed that essentially all of the glucose carbon used aerobically by intact Brugia pahangi adults was accounted for in the recovered lactate, in spite of the presence of cristate mitochondria in these parasites. Approximately 0.2% of the glucose carbon that disappeared was recovered in CO2. However, aerobiosis was required for the incorporation of alanine, proline, and glutamate into both respiratory CO2 and protein, but the glucose was used on the order of 1000 times faster than the amino acids. Homogenate fractions were examined for amino acid use, and all except the 100,000 g soluble fraction showed activity. However, all of the active fractions also contained living microfilariae and other developmental stages that arise from the adult uterus, since the females give birth to living larvae. Sonicates of the microfilariae formed CO2 from proline 30 times more rapidly than crude homogenates of the adult. Similarly, CO2 was formed from glucose 14 times more rapidly by intact microfilariae than by intact adults. The possibility arises that the low rates of CO2 formation from both the amino acids and glucose by intact adults may arise from the metabolism of the aerobic microfilariae and other developmental stages present in utero.

Aerobiosis↗

PubMed2004

The effects of diethylcarbamazine on the ultrastructure of microfilariae of Wuchereria bancrofti in vivo and in vitro.

An ultrastructural study of microfilariae of Wuchereria bancrofti was performed after treatment in vitro and in vivo with diethylcarbamazine citrate (DEC). The morphological alterations produced by treatment in vitro with 5 micro g/ml of DEC were the loss of microfilarial sheaths and lysis of the cytoplasm, with the destruction of all organelles and the formation of several vacuoles, the contents of which presented various degrees of electron-density, or showed an empty appearance. Some of these vacuoles seemed to be extruding from the cytoplasm as apoptotic bodies and others presented organelles inside. Similar alterations were observed after in vivo treatment. At 40 min after treatment of a microfilaremic individual with DEC, almost all microfilariae observed had lost their sheaths; and, in some of them, remains of the microfilarial sheath on the larval surface could be detected. Numerous vacuoles were observed, mainly in the hypodermis and somatic cells, showing organelles inside or an empty appearance. Condensed chromatin was also observed in some somatic cells. At 1 h after treatment of a microfilemic individual with DEC, microfilariae presented drastic morphological alterations, with large vacuoles within somatic cell cytoplasm and complete lysis of all cellular organelles. Therefore, both treatments with DEC in vitro and in vivo had a direct mechanism of action on the microfilariae of W. bancrofti, including organelle damage and apoptosis.

Animals↗

PubMed2001

Immunocytochemical localization of antigens recognized by asymptomatic microfilaremic patient's antisera in microfilariae of Wuchereria bancrofti.

Ultrathin sections of microfilariae of Wuchereria bancrofti embedded in hydrophilic resin were incubated with sera from patients, using antisera from asymptomatic microfilaremic patients with different microfilarial densities [1-100 microfilariae (mf)/ml, 101-500 mf/ml, > 1,000 mf/ml]. All groups studied showed reactivity against relevant epitopes in all tissues of microfilariae of W. bancrofti, instead of being localized in a specific nematode region, although the number of colloidal per square micron was inversely proportional to the microfilaremia. Such results confirm data obtained by other authors and indicate a possible role for the humoral response in the mechanism for the destruction of circulating microfilariae.

Animals↗

PubMed2001

Fine structure, freeze-fracture and deep-etch views of the sheath and cuticle of microfilariae of Litomosoides chagasfilhoi (Nematoda: Filarioidea).

The fine structure of the sheath and the cuticle of microfilariae of the filariid Litomosoides chagasfilhoi is described based on observations made using transmission electron microscopy (TEM) and especially on deep-etched replicas of fully developed intrauterine microfilariae and mature stretched microfilariae released by adult females through cultivation in vitro. TEM showed that the sheath was trilaminated. In contrast, in deep-etching replicas the sheath presented two layers: an inner layer composed of tightly arranged globular material, and an outer layer whose external surface was relatively smooth. Both in thin sections and in classical freeze-fracture and deep-etched replicas, the cuticle presented two distinct regions: an external one, corresponding to the trilaminated epicuticle, and an inner one, corresponding to the inner cuticle. Deep-etching replicas revealed that the epicuticle presented several structures on the annulations of the microfilariae and that the inner region was composed by two parallel rows of globular structures.

Animals↗

PubMed1981

Combination of techniques for concentration and identification of microfilariae from peripheral blood.

Human blood containing a known number of Dirofilaria immitis or Brugia malayi microfilariae was incubated with Giemsa-stain or methylene blue solution and then subjected to density gradient centrifugation in Percoll-solution at a density of 1.090 g/ml. This resulted in complete separation of microfilariae from cellular components. Subsequently the microfilaria-containing layer was altered through a polycarbonate membrane. The stained parasites are then easily recognized and identified on the completely transparent membrane. The average recovery was 80%. This technique proved useful as a preparatory method and as a diagnostic tool for the detection of microfilariae in patients with low microfilaraemia.

Animals↗

PubMed1983

Immune reactions to Wuchereria bancrofti infections in Tanzania. II. Characterization of the serum-mediated adherence reaction of leucocytes to microfilariae in vitro.

Investigations to characterize the in vitro reaction of serum-mediated leucocyte-adherence to microfilariae of Wuchereria bancrofti were carried out in Tanzania. The adherence reaction took place within one hour and at least two serum factors were involved: a heat-labile factor, present also in normal serum (probably complement), and a more heat-stable factor, present in positive serum only (probably an antibody). Neutrophils and eosinophils were involved in the reaction proportionately to Their numbers in the cell solutions used; the reaction killed significantly more microfilariae, than did adherence-negative tests. Microfilariae could be used for at least one week after their isolation from the donor, but a significant decrease in the percentage of reactive microfilariae occurred within 16 hours of isolation. A high degree of species specificity was observed when positive sera were tested against other nematodes. The involvement of complement and the speed with which the reaction took place is in contrast to the results of similar studies from India, and may indicate a difference in the parasite in the two continents.

Adolescent↗

PubMed1985

Loa loa: a simple method for isolation of microfilariae from blood with production of antigen in extraction medium.

A simple method for isolating Loa loa microfilariae from the blood of patients is described. This involves sedimentation on Ficoll followed by migration of the microfilariae into an extraction medium. During migration the microfilariae release antigen-rich excretory or secretory products. The procedure thus yields two products: pure microfilariae and large amounts of antigen in the extraction medium.

Antigens, Helminth↗

PubMed1986

Expression of cross-reactive surface antigens by microfilariae and adult worms of Brugia pahangi during infections in cats.

Microfilariae of Brugia pahangi were labelled with 125-Iodine using the reagent IODOGEN. Electron microscope autoradiographs of sections of iodinated microfilariae showed that the label was strictly confined to their sheath. Adult worms were also iodinated by the same procedure. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of detergent extracts of radio-labelled parasites revealed components of molecular weights 113, 81-71, 46 and 33 kDa in microfilariae, and of molecular weights 29, 20 and 16 kDa in adult worms. All but the 33 kDa component of microfilariae were immunoprecipitable with sera of infected cats and therefore antigenic. Antibodies to the 81-71 kDa and the 46 kDa microfilarial antigens were detected by immunoprecipitation before patency. Similarly, the 29 kDa antigen of adult worms was immunoprecipitable before the fourth moult. Therefore, during infection in cats, these antigens cross-react with epitopes present on earlier developmental stages.

Animals↗

PubMed1988

An egg surface antigen of Setaria digitata (filariae) shed on development to microfilariae.

Egg surface antigens of Setaria digitata were investigated by an immunoperoxidase staining technique. Certain antigens on the egg surface were shed when the eggs developed to microfilariae. Rabbit antisera to S. digitata eggs and to the soluble egg antigen reacted (as detected by immunoperoxidase staining) with the surface antigens of S. digitata eggs and immature microfilariae, and with mature microfilariae of Wuchereria bancrofti and Dirofilaria repens, but not with the surface antigens of mature microfilariae of S. digitata.

Animals↗

PubMed1988

Ingestion of microfilariae from different sources by Culicoides nubeculosus (Diptera: Ceratopogonidae) through an artificial membrane.

Laboratory-hatched Culicoides nubeculosus midges were membrane-fed on cattle blood containing various Onchocerca microfilariae which had been isolated from the hides of red deer (Cervus elaphus) and from Australian and native German cattle. All microfilariae were ingested through the membrane except those of O. tarsicola, which were too large. Onchocerca gibsoni and O. lienalis reached the thoracic musculature, but no further development occurred. Microfilariae of O. flexuosa developed to the "sausage" stage. Microfilariae of O. gutturosa developed to the infective larval stage within 9 days at a temperature of 25 degrees C.

Animals↗

PubMed1990

Prevalence of microfilariae in cattle at slaughter in Zaria, Nigeria.

Skin snips and blood taken from 372 randomly selected slaughtered cattle in Zaria, Nigeria were examined for microfilariae. A total of 293 (78.8%) skin snips and 218 (58.6%) blood samples were positive for microfilariae. Two types of microfilariae, identified as Onchocerca armillata, with a percentage prevalence of 64%, and O. gutturosa with a prevalence of 40% were isolated from the skin. The blood microfilariae were identified as those of Setaria labiatopapillosa.

Animals↗

PubMed2005

Discrimination between six species of canine microfilariae by a single polymerase chain reaction.

Canine dirofilariasis caused by Dirofilaria immitis is usually diagnosed by specific antigen testing and/or identification of microfilariae. However, D. immitis and at least six other filariae can produce canine microfilaremias with negative heartworm antigen tests. Discriminating these can be of clinical importance. To resolve discordant diagnoses by two diagnostic laboratories in an antigen-negative, microfilaremic dog recently imported into the US from Europe we developed a simple molecular method of identifying different microfilariae, and subsequently validated our method against six different filariae known to infect dogs by amplifying ribosomal DNA spacer sequences by polymerase chain reaction using common and species-specific primers, and sequencing the products to confirm the genotype of the filariae. We identified the filaria in this dog as D. repens. This is the first case of D. repens infection in the United States. Additionally, we examined microfilariae from five additional antigen-negative, microfilaremic dogs and successfully identified the infecting parasite in each case. Our diagnoses differed from the initial morphological diagnosis in three of these cases, demonstrating the inaccuracy of morphological diagnosis. In each case, microfilariae identified morphologically as A. reconditum were identified as D. immitis by molecular methods. Finally, we demonstrated that our PCR method should amplify DNA from at least two additional filariae (Onchocerca and Mansonella), suggesting that this method may be suitable for genotyping all members of the family Onchocercidae.

Animals↗