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Biomedical subjects

T R Klei

Publications and source records attributed to T R Klei.

At least 55 records · Page 3Linked to original sources
PubMed1997

Adoptive transfer of granulomatous inflammation to Brugia antigens in jirds.

Brugia pahangi infections of jirds (Meriones unguiculatus) produce a granulomatous inflammatory response within the lymphatic vessels. Granulomas that form around beads coated with soluble adult antigens embolized in the lungs have been used to measure this response. Similar lesions were observed in naive jirds receiving lymph node cells and splenocytes from animals with acute infections. This was not the case with cells from chronically infected jirds that were hyporesponsive to implanted antigen-coated beads. Passively transferred immune sera collected during the acute and chronic periods of infection did not transfer this response. Lymph node cells but not splenocytes obtained from chronically infected jirds induced a down regulation of this response in animals during the acute period. These results indicate that this inflammatory response in the jird is cell mediated and that adoptive transfer in jirds is feasible. The induction of the down-regulated state may also be mediated by cells, but not serum factors.

Acute Disease↗
PubMed1997

Effect of gamma radiation on Brugia L3 development in vivo and the kinetics of granulomatous inflammation induced by these parasites.

Previous studies have shown that the downregulation of parasite-specific cellular immune response in Brugia-infected jirds requires viable worms but is not dependent on microfilariae (MF) for either induction or maintenance of this phenomenon. To clarify further which life cycle stages induce filarial hyporesponsiveness, jirds were infected intraperitoneally with third stage larvae (L3) exposed to 0, 15, 25, 35, 45, or 90 krad of gamma radiation to differentially alter L3 development. Necropsies were performed at 7, 14, 28, and 118 days postinoculation (DPI). The degree of parasite development, intraperitoneal inflammation, and pulmonary granulomatous inflammation (PGRN) to parasite antigen-coated beads embolized in the lungs were monitored at the time of necropsy. Parasite survival and worm lengths were inversely related to the irradiation dose. Gamma radiation at 35, 45, or 90 krad prevented larval molt to the adult stage. Some parasites irradiated with 15 or 25 krad developed beyond fourth stage larvae (L4) to infertile adult females. The PGRN peaked at 14 DPI in all infected groups. Downregulation of the PGRN occurred after 14 DPI in groups that received nonirradiated L3 or L3 irradiated with 15 krad. No significant decrease of the PGRN occurred in groups that received parasites irradiated with more than 15 krad. Significant peritoneal inflammation as indicated by an increase in macrophages occurred only in jirds that received nonirradiated L3. These data demonstrate the importance of the adult stages in inducing downmodulation in the absence of MF and suggest that the L4 may also play a role in the induction of this phenomenon. An alternate conclusion is that parasite burden and not developmental stage is important in the induction of this hyporesponsive state.

Animals↗
PubMed1996

Identification and characterization of a pyrantel pamoate resistant cyathostome population.

Three fecal egg count reduction assays (FECR) and one critical trial were performed to determine the efficacy of pyrantel pamoate (PP) at 6.6 mg base kg-1 on a well managed stud farm in Louisiana where a loss of efficacy was suspected. Efficacy of PP based on FECR varied from 25% in mares to 83% in yearlings. Second treatments with PP 2 weeks following an initial treatment failed to reduce eggs per gram (EPG). A critical trial was performed to determine the cyathostome species resistant to PP. Three strongyle-naive ponies which acquired infections on the farm were used for this purpose. Following treatment with PP at the recommended dose, 11 species of cyathostomes remained in the intestine of the tracer ponies. Reduced efficacies (62%-88%) were noted for seven species. Resistance to oxibendazole (OBZ), which was > 90% effective on this farm in 1982, was also evaluated by FECR and found to exist. The results of one experiment indicate that dual resistance of parasites to PP and OBZ also exists.

Animals↗
PubMed1996

Cellular immune responses of jirds to extracts of life cycle stages and adult excretory secretory products during the early development of Brugia pahangi.

The Brugia-jird model of lymphatic filariasis was used to examine the induction of cellular immune responses during the early premicrofilaremic phases of the infection. The intensity of the pulmonary granulomatous inflammatory response (PGRN) was determined by measuring granuloma areas around Sepharose beads coated with parasite extracts which were embolized in the lungs of jirds prior to necropsy. Necropsies were performed at 7, 14, 28, 56, and 150 days postinfection (DPI). These time points correspond to specific developmental changes in the life cycle. Lymphocyte blastogenesis assays were performed using cells from draining renal lymph nodes and splenocytes at 14 and 150 DPI. Soluble extracts of third stage larvae (L3), fourth stage larvae (L4), adult females, adult males, microfilariae (MF), and excretory secretory products (ES) of males and females were used in both measurements of cellular responsiveness. A marked granulomatous response to parasite extracts peaked at 7 DPI or 14 DPI followed by a gradual decrease to a hyporesponsive state at 120 DPI. The response of renal lymph node cells also was significantly elevated at 14 DPI and significantly decreased at > 150 DPI. The splenocyte responses were erratic and did not follow this pattern. Significant differences in PGRN responses to somatic extract preparations were not seen during the early stages of the infection (7, 14, 28 DPI), but those to MF and L3 were significantly less at 56 and 120 DPI. Although PGRN responses to ES followed a similar pattern, these were less than those to the somatic extract. The data indicated that a rapid, intense cell-mediated inflammatory response is induced early during a primary infection and that this response is rapidly downregulated. This downregulation begins prior to the maturation of adult parasites and microfilarial production. The early phase of the cellular response appears to be compartmentalized in that this response was consistently observed in the renal lymph nodes but not in the spleen. Soluble protein components of the parasites responsible for these responses are likely multiple and shared by all life cycle stages.

Animals↗
PubMed1996

Comparison of moxidectin oral gel and ivermectin oral paste against a spectrum of internal parasites of ponies with special attention to encysted cyathostome larvae.

Two dosages of moxidectin oral gel were evaluated and compared to a therapeutic dose of ivermectin oral paste in the control of a spectrum of gastrointestinal parasites of ponies naturally infected in southern Louisiana or Mississippi. Thirty-two mixed-breed ponies ranging in age from one to 21 years were used in this controlled test. Eight weeks prior to the experiment, ponies grazing on contaminated pasture were moved to a paddock and fed a pelleted ration, thus reducing or eliminating the potential for additional infection and ensuring the existence of a population of encysted larvae. Ponies were then allocated to replicates of four animals based on values of fecal strongyle egg counts and percent strongyle larvae composition determined from Baermann sedimentations of fecal cultures. Members of replicates were allocated to one of four treatment groups: moxidectin oral gel administered at 300 micrograms kg-1 body weight, moxidectin oral gel at 400 micrograms kg-1, the oral gel vehicle as negative control, and ivermectin oral paste at 200 micrograms kg-1. Prior to treatment, ponies were confined in pairs to covered concrete runs by treatment group. Two weeks following treatment, necropsy examinations of all animals were performed. Parasites were recovered from the lumen of the stomach, the intestinal tract, the cranial mesenteric artery and its major branches, the peritoneal body wall and from pepsin digests of mucosal scrapings taken from the cecum and large colon. Encysted cyathostome larval burdens were also compared using mural transillumination of segments of the large colon for visualization of the encysted forms. Control ponies were not uniformly infected with the spectrum of parasites; however, moxidectin, at either dosage, compared favorably with ivermectin in the control of the adults of Strongylus vulgaris, Strongylus edentatus, Triodontophorus spp., Oesophagodontus robustus, Trichostrongylus axei, Oxyuris equi, Parascaris equorum, Habronema muscae, as well as both the adult and larval Cyathostominae recovered from the lumen. Moxidectin also appears as efficacious as ivermectin against migrating large strongyle larvae at the two weeks post-treatment evaluation. Moxidectin demonstrated a trend towards greater efficacy against encysted cyathostome larvae than a therapeutic dosage of ivermectin, but this difference was not statistically significant. Moxidectin was less effective than ivermectin against Gasterophilus intestinalis and was equally ineffective as ivermectin against Anoplocephala perfoliata.

Administration, Oral↗
PubMed1995

Brugia pahangi: differential granulomatous reactivity of infected jirds (Meriones unguiculatus) to fractions of adult worm extract.

Soluble extracts of adult Brugia pahangi (SSE) were fractionated by lectin affinity chromatography, followed by reversed phase HPLC. The immunologic and in vivo inflammatory reactivity of the resulting fractions were compared in jirds with acute and chronic infections of B. pahangi. When separated by SDS-PAGE, all fractions possessed bands which were recognized in Western blots by antibodies from jirds with both acute and chronic infections. Fractions were coupled to sized Sepharose beads that were subsequently embolized into the lungs of infected and uninfected control jirds. Granulomas were induced by SSE, the lectin column eluate, and HPLC fractions E, F, and G in acutely infected jirds. These reactions were significantly reduced in chronically infected jirds. HPLC fractions B, C, and D did not elicit an in vivo inflammatory response. A perivascular infiltrate of eosinophils and mononuclear cells was also observed in lungs of acutely infected jirds which received granuloma-inducing coated beads but not in lungs of similar jirds which received beads that did not induce this inflammatory response. Proliferative responses of splenocytes stimulated with SSE or the lectin eluate and lymph node cells and splenocytes stimulated with HPLC fractions B, C, or D corresponded to the in vivo granulomatous response to homologously coated beads. Correlations between in vivo inflammatory responses and in vitro proliferative responses were not seen using other fractions in these assays. These data indicate that varying degrees of granulomatous inflammation are induced by different filarial proteins mixtures and that the in vivo granuloma induction by antigen-coated beads will be useful in the identification of specific proteins involved in the induction, maintenance, and regulation of filariae-elicited inflammatory reactions. Although the size of these granulomas corresponds to severity of granulomatous inflammatory responses visualized within the jird lymphatics during the course of infection, the reaction does not correlate in all instances to lymphoproliferative responses of cells from peripheral lymph nodes or the spleen. Distinct differences between antibody and granulomatous reactivity to some fractions were noted.

Animals↗
PubMed1995

Dose titration of moxidectin oral gel against gastrointestinal parasites of ponies.

Moxidectin was tested as an oral gel formulation during a controlled test performed to evaluate dosages against equine gastrointestinal parasites. Four groups of ten ponies were used. Ponies ranged from 1 to 20 years of age and were naturally infected in southern Louisiana or Mississippi. Fecal exams and fecal cultures were performed on all ponies to determine the strongyle egg counts and the percent distributions of large and small strongyles. Following these determinations, ponies were allocated to replicates of four ponies to provide an even distribution of strongyle infection, age, weight and gender. Members of each replicate were then randomly assigned to one of four treatment groups. The doses tested were 300, 400 and 500 micrograms kg-1 body weight. The oral gel vehicle alone served as control. Treatments were administered behind the tongue and the ponies were observed continuously for 4 h for any adverse reactions; thereafter, ponies were observed at least twice daily. Necropsy examinations were performed 14 days post-treatment for the recovery and identification of any parasites present. Moxidectin, at all doses tested, was 100% efficacious against adults of Strongylus vulgaris, Strongylus edentatus, Triodontophorus spp. and 22 species of small strongyles. Moxidectin was also 100% efficacious against larvae of Strongylus edentatus and Oxyuris equi, greater than 94% efficacious against Strongylus vulgaris larvae and Oxyuris equi adults at 14 days post-treatment. Moxidectin proved highly efficacious against luminal small strongyle larvae (> 99.9% against L4 and > 92% against L3) and moxidectin demonstrated some efficacy against encysted small strongyle larvae as well.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1995

Dose titration of moxidectin oral gel against migrating Strongylus vulgaris and Parascaris equorum larvae in pony foals.

Moxidectin was tested for efficacy in ponies against experimental infections of 56 day Strongylus vulgaris larvae and 11 day Parascaris equorum larvae. Three dosages of moxidectin were tested: 300 micrograms per kg live body weight, 400 micrograms per kg, and 500 micrograms per kg, and the vehicle served as control. Ponies were first infected with 600 S. vulgaris third-stage larvae (L3) on Experiment Day 0 and then with 3000 embryonated P. equorum eggs on Day 45. Moxidectin treatments were administered on Day 56 and necropsy examinations were performed on Day 91. Strongylus vulgaris fourth-stage (L4) and fifth-stage (L5) larvae were recovered at necropsy from the control ponies, in dissections of the cranial mesenteric artery and its branches (L4 and L5), and recovered from nodules in the wall of the cecum and ventral colon (L5). Parascaris equorum larvae were recovered from the small intestine of control ponies. Moxidectin was highly efficacious against S. vulgaris L4 and L5 at all three doses tested (99.6-100%), and appeared to be equally efficacious against P. equorum larvae (100%); however, control ponies had low levels of P. equorum infections compared to previous experimental infections performed using identical methods. This suggests that the prior S. vulgaris infection on Day 0 may have influenced the subsequent experimental P. equorum infection on Day 45 and contributed to the lower recovery.

Administration, Topical↗
PubMed1995

Impact of microfilaremia on maintenance of a hyporesponsive cellular immune response in Brugia-infected gerbils (Meriones unguiculatus).

The purpose of these experiments was to define the significance of the microfilarial stage to the hyporesponsive condition seen in lymphatic filariasis. Two types of experiments were conducted with Brugia pahangi-infected gerbils. In one, in vitro lymphocyte blastogenesis and in vivo granuloma formation in response to parasite antigen were correlated to microfilaremia in chronically infected individuals. In a second set of experiments, the level of in vivo granuloma formation was assessed following chemotherapeutic removal of microfilariae with ivermectin. The results indicated that the microfilarial stage alone is not responsible for the maintenance of the low cellular responses seen during chronic infections in this model. Furthermore, the data suggest that the degree of downregulation of these responses may be related to parasite burden.

Acute Disease↗
PubMed1995

Absence of protective resistance to homologous challenge infections in jirds with chronic, amicrofilaremic infections of Brugia pahangi.

Most jirds (Meriones unguiculatus) with chronic Brugia pahangi infections remain microfilaremic, develop a hyporesponsive state, and are susceptible to reinfection. Although few, some jirds become amicrofilaremic or fail to develop a microfilaremia. The hypothesis that chronically infected, amicrofilaremic jirds may be resistant to reinfection was tested. Twenty-four chronically infected amicrofilaremic jirds, with or without circulating antigen, were inoculated subcutaneously with 75 B. pahangi third-stage larvae (L3). Necropsies were performed 25 days postinoculation, and challenge populations were separated from existing worms by size. Similar inoculations and necropsies were performed on groups of chronically infected microfilaremic jirds and uninfected jirds. Based on worm recoveries, jirds with occult infections were not resistant to reinfection. An anamnestic antibody response to extracts of L3 or microfilariae (mf) was not seen, nor were antibodies to the surface of L3 or mf. The data indicate that a susceptible state is maintained in this model of lymphatic filariasis in the absence of circulating mf.

Animals↗
PubMed1995

Efficacy of moxidectin oral gel against Onchocerca cervicalis microfilariae.

During a series of dose-titration experiments designed to evaluate the efficacy of moxidectin oral gel against equine gastrointestinal parasites, infection with Onchocerca cervicalis was diagnosed in 25 of 82 ponies prior to treatment. Microfilariae were identified in full-thickness skin biopsies taken from the ventral midline. Treatment with moxidectin in single doses of 300, 400, or 500 micrograms/kg of body weight was 100% effective in eliminating microfilariae from 20 skin biopsies taken 14 days posttreatment, whereas 5 microfilaria-positive ponies in 2 control groups remained positive following placebo treatment. No adverse reaction was seen in any pony following treatment with moxidectin or the vehicle control.

Administration, Oral↗
PubMed1994

Cross-species PCR cloning of gerbil (Meriones unguiculatus) interleukin-2 cDNA and its expression in COS-7 cells.

A cDNA clone of the gerbil interleukin-2 (IL-2) gene was isolated by cross-species PCR cloning, and demonstrated to produce a functional gerbil IL-2 protein when inserted in the eucaryotic expression vector pSV-SPORT1 and transfected into COS-7 monkey cells. The open reading frame codes for a polypeptide of 155 amino acid residues with a molecular weight (MW) of 17,601 which includes a putative signal peptide. The mature gerbil IL-2 is deduced to contain 135 amino acid residues and has a calculated MW of 15,496. Culture supernatant of COS-7 cells transfected with pSV-SPORT1-GIL-2, but not pSV-SPORT1 stimulates the proliferation of the IL-2 dependent murine CTLL-2 cells. Molecular characteristics of gerbil IL-2 have been compared with IL-2 of mouse, rat, human, bovine, ovine and porcine origin. The mature form of gerbil IL-2 is similar in molecular weight to all species except the mouse. A N-glycosylation site present in bovine, ovine and porcine IL-2 respectively, is absent in gerbil. Three Cys residues are conserved in all compared mature IL-2 molecules. In these comparisons, gerbil IL-2 has highest identity with rat IL-2 for both nucleotide and amino acid sequence.

Amino Acid Sequence↗
PubMed1994

Production and characterization of monospecific adult worm infections of Strongylus vulgaris and Strongylus edentatus in ponies.

Since 1978, 20 surgical implantations of either Strongylus vulgaris or Strongylus edentatus have been performed in our laboratory for the purpose of obtaining single species cultures of these parasites. Following surgical implantation peak EPG values of 13-327 (S. vulgaris) and 363-1284 (S. edentatus) generally occurred during the first 3 weeks post-implantation. Duration of infections was as long as 5 years. Successful outcome of such surgeries appears to be related to the total number of parasites used (> or = 38) and the ratio of female to male worms implanted (1:1 or 2:1).

Animals↗
PubMed1994

Experimental immunization of ponies with Strongylus vulgaris radiation-attenuated larvae or crude soluble somatic extracts from larval or adult stages.

Protection from Strongylus vulgaris infection through immunization with radiation-attenuated third-stage larvae (L3) or crude soluble homogenates from larval or adult stages was examined. Yearling ponies raised parasite-free were divided into 3 immunization groups: radiation-attenuated L3; soluble adult somatic extracts; larval somatic extracts with excretory/secretory products (E/S) from in vitro culture; and 1 medium control group. Ponies were immunized twice; attenuated larvae were administered orally and somatic extracts or controls injected intramuscularly with adjuvant. Approximately 6 wk following the second immunization, all ponies were challenged. Necrospy examinations were performed 6 wk following challenge. Irradiated larvae recipients had the fewest postchallenge clinical signs and lesions and were 91% protected from infection determined by larval recoveries from arterial dissections. Soluble antigen recipients and controls had similar larval recoveries and thus equal susceptibility to challenge. Soluble antigen recipients had more severe clinical signs and lesions than controls, suggesting that parenteral immunization exacerbated postchallenge inflammatory responses. Protection by immunization with irradiated larvae was associated with an anamnestic eosinophilia and postimmunization antibody recognition of S. vulgaris L3 surface antigens. Histologic staining of eosinophils within tissues of this group suggested that this immunization induced a cytophilic antibody response that facilitated degranulation.

Analysis of Variance↗
PubMed1994

In vitro culture of equine strongylidae to the fourth larval stage in a cell-free medium.

An efficient and reliable method is described for the culture of equine strongyles from the third (L3) to the fourth (L4) larval stage. Medium consists of 50% fetal calf serum and 50% NCTC with additions of L-glutamine, NaHCO3, yeast extract, bactopeptone, and dextrose. The gas phase used is of prime importance; it is a mixture of 10% CO2, 5% O2, and 85% N2. Strongylus vulgaris, Strongylus edentatus, Strongylus equinus, Triodontophorus brevicauda, Triodontophorus serratus, Triodontophorus tenuicollis, Oesophagodontus robustus, Cylicocyclus insigne, and mixed species of cyathostomes were cultured to the L4 stage. Oesophagodontus robustus was cultured to the fifth larval stage. Depending on species, 44-95% of Strongylinae L3 inoculated into this system molted to L4. Although some development of the Cyathostominae L3 occurred, only a small portion (1%) completed ecdysis to L4. Viability in cultures of all species remained high (> 60-70% larvae surviving) for at least 4 wk (cyathostomes) and as long as 6 mo (S. edentatus). The addition of equine hemin to cultures of S. vulgaris and O. robustus L4 enhanced development and prolonged viability of these larvae. Hemin had no effect on cultures of S. edentatus or S. equinus, and it was not tested in cultures of other species.

Animals↗