Biomedical subjects

K D Murrell

Publications and source records attributed to K D Murrell.

At least 109 records · Page 6Linked to original sources

PubMed1984

Distribution of Trichinella spiralis larvae in selected muscles and organs of experimentally infected swine.

Thirty-two Hampshire-Yorkshire pigs (6 to 8 wk old) were inoculated with the Beltsville strain of Trichinella spiralis at a level of about 880 larvae/kg of body weight (about 15 kg). At about 100 kg, the pigs were slaughtered and 10-g samples of muscle and other tissues were digested in pepsin-HC1 and examined microscopically for T. spiralis larvae. The mean number of larvae recovered/gram was: tongue, 452; diaphragm, 391; obliquus abdominis internus, 130; serratus ventralis, 116; psoas major, 105; triceps brachii, 100; biceps femoris, 83; semitendinosus, 74; intercostal, 60; semimembranosus, 58 and longissimus dorsi, 37. The liver and spleen samples contained none. Larvae were found in one sample each of the blood, brain and kidney, in two samples of the heart, and in four samples of lymph tissue. Each of these samples was from a different pig except the positive samples of brain and heart, which were from the same pig. The larvae found in the blood, brain, kidney, heart and lymph were first stage larvae and, therefore, do not indicate migration of newborn larvae from the gut. The presence of these larvae in non-striated muscle tissue may have been due to contamination of the organs from infected skeletal muscle. These data confirmed previous reports of the distribution of the T. spiralis larvae among individual muscles of the carcass. Further, the data suggest that cross-contamination of organ tissue is possible during evisceration and, therefore, organ meat from infected swine cannot be assured to be free of T. spiralis larvae.

Animals↗

PubMed1984

Distribution, prevalence and intensity of Trichinella spiralis infection in furbearing mammals of Pennsylvania.

Tongues from 1,170 raccoons, 384 opossums, 201 muskrats, 168 foxes (red and grey), 51 skunks, and 17 mink from Pennsylvania were examined for Trichinella spiralis larvae by peptic digestion. The overall prevalence of T. spiralis infection was 3.2%, varying in the carnivores from 2.6% in raccoons to 15.1% in red foxes; no muskrats were infected. Prevalence varied regionally, being higher west of the Susquehanna River, where, in the Ridge and Valley Province, it reached 9%. The larval densities varied greatly as reflected by the overall geometric mean number of larvae per gram of muscle (LPG) of 18.5 and the comparable arithmetic mean LPG of 113.3. No geographic, sex, or species-related differences in the intensity of infection were demonstrated.

Animals↗

PubMed1984

Persistence of encysted Toxoplasma gondii in tissues of pigs fed oocysts.

Ten pigs were fed 100 to 10,000 Toxoplasma gondii oocysts. Two pigs died 7 and 11 days later, and 8 pigs were euthanatized at days 38, 38, 91, 126, 168, 169, 170, and 171. From the euthanatized pigs, portions of 15 organs digested in pepsin-HCl solution were inoculated into mice, as a bioassay for viable T gondii. Such organisms were isolated from the brain and heart of these 8 pigs, from the tongue of 7, from thigh muscles of 5, from the diaphragm of 4, from kidneys, liver, and small intestines of 2, and from salivary glands and eyes of 1 pig; but not from lungs, spleen, spinal cord, mesenteric and prescapular lymph nodes of any pig. Results indicate that T gondii can persist in edible tissues of living pigs for at least 171 days and that heart and brain may be the most suitable porcine tissues for epizootiologic surveys.

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PubMed1984

The intestinal mast cell response to Trichinella spiralis infection in mast cell-deficient w/wv mice.

The intestinal mast cell response and lymphoblast activity, as measured by the incorporation of 3H-thymidine into mesenteric lymph node cells (MLN) of WBB6F1-w/wv(w/wv) mice, their normal congenic littermates (+/+) and C57BL/6J mice, were compared after infection with Trichinella spiralis. Marked and similar blast cell activity and an increase in number of cells were observed in the MLN of infected w/wv and C57BL/6J mice 7 and 15 days P.I. In contrast to C57BL/6J mice, primary T. spiralis intestinal infections were prolonged in w/wv mice and more muscle larvae were recovered from w/wv mice 29 days post-infection. In C57BL/6J mice mucosal mast cell (MMC) numbers increased on day 7 P.I. whereas in w/wv mice these cells did not increase significantly until day 15 post-infection, reaching a peak on day 22. In w/wv mice, the response to secondary infection as determined by an accelerated expulsion of adult worms did not occur until day 11 postchallenge whereas in +/+ and C57BL/6J mice worm expulsion was nearly complete at that time. In both primary and secondary infections, the MMC numbers in w/wv mice were significantly lower than in C57BL/6J or +/+ mice. The results suggest that prolongation of T. spiralis infection in w/wv mice is associated with delayed appearance of mast cells in the intestinal mucosa which may reflect slow generation of the intestinal inflammatory response.

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PubMed1983

Strongyloides ratti and Trichinella spiralis: net charge of epicuticle.

The intact epicuticles of Strongyloides ratti stage-3 larvae and Trichinella spiralis stage-1 larvae were found to have a surface net negative charge. Ultrastructural studies on S. ratti using cationized ferritin and ruthenium red showed the negative charge to be dense and uniformly distributed over the epicuticular surface. Staining with acetic acid-ferric oxide hydrosol occurred at pH 1.65 and suggests that amino acid carboxyl groups were not responsible for the negative charge property. Alcian blue staining occurred at pH 0.5 and at a critical electrolyte concentration (CEC) of 0.9 M MgCl2, a property similar to that of highly sulfated mucopolysaccharides such as the proteoglycan keratan sulfate. In contrast, T. spiralis larvae failed to stain with alcian blue below pH 5.0 or at a CEC of 0.1 M, suggesting its negative charge is associated with dissociated amino acid carboxyl groups. Attempts to remove the negative charge-bearing components in the epicuticle of S. ratti by detergents, organic solvents, denaturing agents, proteases, uronidases, neuraminidases, and lipases were unsuccessful. The presence of elastin in the S. ratti larval outer cortical layer was indicated by its vulnerability to elastase and its reaction to aldehyde fuchsin-alcian blue stain. These results show that the epicuticle of S. ratti is not a typical cell membrane, although it appears to have ultrastructural similarities. It is suggested that the association of highly sulfated mucopolysaccharides with the epicuticular surface of free-living nematodes such as S. ratti L3 may reflect a greater need to protect against surface desiccation. It is also postulated that the highly negatively charged surface may have anticomplementary and anticoagulation effects.

Animals↗

PubMed1983

Trichinella spiralis: effect of high temperature on infectivity in pork.

Twenty gram samples of homogenized Boston shoulder from swine experimentally infected with Trichinella spiralis were sealed in plastic pouches, pressed to a uniform thickness of 2 mm, and subjected to water bath temperatures of 49, 52, 55, 60, and 63 +/- 0.5 C for intervals of 2 min to 6 hr, especially within the interval of 0 to 15 min. These times included a period of about 1 min at the start and a period of about 1 min at the end for temperature equilibration. Treated samples were rapidly chilled to 25 C and then digested in a 1% pepsin-HCl solution at 37 C for 18 hr to recover T. spiralis larvae. The recovered larvae were suspended in 2 ml saline; 1 ml of this suspension was introduced into the stomach of each of two rats. The linear equation, log (time) = 17.3 -0.302 (temperature), was calculated from the time required at each temperature for the inactivation of T. spiralis larvae. The correlation coefficient for that relationship was r = -0.994. Larvae heated in the meat to 55 C for 4 min retained their infectivity, but were rendered noninfective after 6 min at 55 C. At 60 C, larvae were not infective after only 2 min (zero dwell time); whereas at 52 C, 47 min were required to render the larvae noninfective. Larvae in meat heated to 49 C were infective after 5 hr but not after 6 hr. These data demonstrate that the destruction of infectivity of T. spiralis is time-temperature related.

Animals↗

PubMed1983

Water contact behavior and schistosomiasis in an upper Egyptian village.

Preliminary findings of a study of the role of microspatial behavior and local ecological circumstances in the persistence of Schistosoma haematobium infection in El Ayaisha village, Upper Egypt, are presented. Twelve types of water contact activities were studied in three cohorts of 274,324 and 392 male students aged 5-16 during a 2-year period. Swimming and playing resulted in more frequent and intensive contact with potentially infective water and in more pollution of snail habitats with schistosome eggs than any other type of activity. Irrigation was probably not a major cause of S. haematobium infection in schoolboys and drinking water and fishing carried the smallest risk for this age group. Mapping and discriminate analysis of infection and transmission indicators revealed spatial associations between water contact, schistosome transmission and infection among the various age groups. The highest egg excretion rates in individuals and the highest prevalence rates were noted in the neighborhoods nearest to the canals. Water contact and contamination of water by the heavily infected school age boys is seasonally concentrated during the summer, when intermediate host snails and infective cercariae are also most common in the water. Frequency, type and duration of water contact change with age together with types of water bodies used, causing corresponding changes in exposure risk. Nevertheless, other factors, including acquired immunity, preexisting infections, chemotherapy and the effect of the study on the normal water contact behavior of the study population must also be evaluated. Contact with the Nile and the canals by the general nonschool population of El Ayaisha was studied to verify the observations among the schoolboys and to study socially linked activities and the transmission potential of the various transmission sites. Results are evaluated in regard to the feasibility of various schistosomiasis control measures in El Ayaisha.

Adolescent↗

PubMed1983

Diagnosis of swine trichinosis by enzyme-linked immunosorbent assay (ELISA) using an excretory--secretory antigen.

An excretory--secretory (ES) antigen was used in a serodiagnostic enzyme-linke immunosorbent assay (ELISA) for swine trichinosis. ELISA procedures included a double-antibody test, using either an anti-swine IgG or a protein A enzyme conjugate, and a triple-antibody test using a pig IgG heavy-chain specific second antibody with a conjugated third antibody. The ES antigen was effective in eliminating all false-positive reactivity in sera from farm-raised hogs. The triple-antibody procedure was more sensitive and demonstrated a greater efficiency in detecting positive animals and early seroconversions. Naturally-infected pigs with worm burdens as low as 0.01 larvae per gram (LPG) of diaphragm were seropositive using these procedures. Seroconversion in experimentally-infected animals receiving low doses of muscle larvae (500) occurred considerably later than in animals receiving high doses (10000). This might account for false-negative reactions in naturally-infected animals with very low (less than 0.1 LPG) worm burdens.

Animals↗

PubMed1983

Immunization of mice with ultraviolet-irradiated Schistosoma mansoni cercariae: a re-evaluation.

Mice immunized by percutaneous exposure to ultraviolet-irradiated Schistosoma mansoni cercariae developed levels of resistance to subsequent S. mansoni infection comparable to those induced by gamma-irradiated cercariae (50-70% reduction in adult worm burden). Cercariae treated with ultraviolet doses ranging from one to three times the minimum dose required to prevent long-term survival induced the highest levels of resistance.

Animals↗

PubMed1983

Shedding of antibody complexes by Strongyloides ratti (Nematoda) larvae.

Antigens on the epicuticular surface of Strongyloides ratti infective third-stage larvae (L3) could be demonstrated by an indirect fluorescent antibody technique under certain conditions. Infective L3 shed anti-antibody complexes at room temperature, but not at 4 C or in the presence of sodium azide or colchicine. Shedding of antibody did not appear to involve epicuticular antigens, and only occurred when anti-rat IgG was complexed to rat anti-larval antibody. However, parasitic L3 removed from rats did not exhibit this shedding reaction, suggesting that an important developmental change in cuticle physiology occurs during the transition from a free-living existence to a parasitic mode. The ability to shed foreign objects from the epicuticle of free-living infective L3 may be a defensive or protective response to soil microorganisms.

Animals↗

PubMed1983

Comparison of three subspecies of Trichinella spiralis by scanning electron microscopy.

The surface morphology of three subspecies of Trichinella spiralis was examined by SEM in an attempt to find characteristics useful for distinguishing the subspecies. The subspecies studied were T. spiralis spiralis, which had been maintained in swine and laboratory animals for about 50 yr; T. spiralis nativa collected from Ursus maritimus at 58 degrees N latitude and 95 degrees W longitude in 1976; and, T. spiralis pseudospiralis, which was derived from the original isolation of this subspecies from Procyon lotor at 43 degrees N latitude and 47 degrees 30'E longitude in 1972. All three subspecies were passed in CFW mice and adult worms were collected from the small intestine at 4, 5, 6, 7, 8, and 11 days PI. Characteristics examined included labial and cephalic papillae, cuticular ridges and folds, hypodermal gland cell pores, pseudobursal lobes, genital papillae, cloacal aperture, copulatory bell and vulval morphology. Previous reports of subspecies differences within Trichinella spiralis in the number and distribution of hypodermal gland cell pores, position of genital papillae, shape of the cloacal aperture and shape of pseudobursal lobes were not confirmed and are believed to have been in error resulting from artifacts of fixation and a lack of knowledge of variations within the subspecies caused by low numbers of samples. Differences in surface morphology were not found among the three subspecies. The available names of the recognized biological populations of Trichinella were used at the subspecies level rather than species level because this more clearly represents the state of our knowledge of the nematodes. The question of whether the epidemiology of trichinosis is complicated by the presence of more than one species has not been answered, and it is important that our nomenclature reflect this.

Animals↗

PubMed1983

Induction of immunity by transcolostrally-passed Strongyloides ransomi larvae in neonatal pigs.

Earlier studies had suggested that neonatal pigs that acquire infections of Strongyloides ransomi via the sow's milk fail to expel intestinal worms normally. Adult worm recoveries were compared from the intestines of normal and transcolostrally-infected neonatal pigs after a subcutaneous challenge inoculation of third-stage larve (L3) to determine whether a direct intestinal infection (via sow's colostrum) might affect resistance. Additionally, transcolostrally-infected pigs that had received an additional subcutaneous inoculation of L3 were reinoculated with L3, and the adult worm recoveries were compared to those of pigs immunized with only one subcutaneous inoculation of L3 to determine the effect of initial transcolostral infection on the development of protective immunity by this established procedure. The results showed that intestinal worms obtained transcolostrally can induce high resistance in pigs to reinfection by S. ransomi, and they do not affect the enhancement of protective immunity by a subcutaneous inoculation of L3. However, peripheral blood lymphocytes obtained from transcolostrally-infected pigs did not respond to larval antigens in vitro until after a subsequent subcutaneous inoculation of L3.

Animals↗

PubMed1982

Solubilization studies on the epicuticular antigens of Strongyloides ratti.

Antigens on the epicuticular surface of Strongyloides ratti infective third-stage larvae (L3) were demonstrated by both ferritin-conjugated antibody and indirect fluorescent antibody techniques. The rat antibodies from immune serum that bind to these antigens were chiefly of the IgG2a subclass. Solubilization of these antigens by extraction with detergents, hypertonic salt, organic solvents and by freezing and thawing was limited as measured by the reduction in antibody binding to the epicuticle. The epicuticular antigens were resistant in situ to degradation by a variety of proteases, carbohydrases and lipase. Infectivity of the L3 in the rat was not reduced by prior sensitization with rat antibody. The epicuticular antigens are not completely species-specific since antibody from S. ransomi-infected pigs cross-reacted well with S. ratti L3 antibody. However, high levels of resistance to S. ratti could be induced in rats only by multiple inoculations of heat-killed S. ratti L3.

Animals↗

PubMed1982

Some problems associated with radiolabeling surface antigens on helminth parasites: a brief review.

Recent developments in technology have facilitated substantial advances in the characterization of surface antigens from a wide variety of both normal and neoplastic cells. However, the immunochemistry of parasites has lagged behind. Efforts to apply conventional radiolabeling methods to helminths have not always been successful. Experimental work with Schistosoma mansoni is reviewed to illustrate common problems encountered in surface labeling studies. These findings should provide insight for the future investigation of other helminth species.

Animals↗

PubMed1982

Evaluation of three immunodiagnostic procedures for porcine strongyloidiasis.

An indirect fluorescent antibody test (IFAT), an indirect radioimmune antibody test (IRAT), and an enzyme-linked immunosorbent antibody assay (ELISA) were compared for their efficacies in detecting antibody to Strongyloides ransomi in pigs. The greatest sensitivity was exhibited by the ELISA, using a soluble, whole larval extract. The 2 indirect antibody assays, IFAT and IRAT, using intact 3rd-stage larvae (L3) were comparable in sensitivities. The use of live L3 in the IFAT and IRAT presented technical problems, because the larvae shed antibody complexes at ambient room temperature. This could be inhibited by the addition of 20 mM of sodium azide to all working solutions or by doing the tests at 4 C. Fixation of the L3 by either formalin or heat also eliminated the shedding problem. The specificities of the ELISA and IFAT were supported by the negative results obtained with serum from pigs infected with Ascaris suum, Stephanurus dentatus, and Trichinella spiralis.

Animals↗

PubMed1981

A longitudinal study of Schistosoma haematobium infection in Qena governorate, Upper Egypt. 1. Initial epidemiological findings.

An epidemiological study was conducted as an initial phase of a longitudinal study on the immunology of Schistosoma haematobium in Upper Egypt. The study area was confined to three villages in Qena governorate, a region endemic solely for S. haematobium. In a cross-sectional survey in two of these villages, the overall prevalence of infection was 28.7% (29.9% at Khozam and 26.9% at El Ayaisha) based on urine examination of the family members in every third household. S. haematobium infection was found in all age groups including infants below 1 year of age. The age distribution of those infected showed the classical rise in the percent infected, reaching a peak of 57-63% in the 11- to 15-year age group followed by a rapid decline and stable low prevalence below 28% in adult years. Males consistently had higher prevalence rates than females at all ages with the profiles of the age prevalence curves strikingly similar. In the two villages, significantly (P less than 0.05) higher infection rates were found in farmers compared to those in other occupations. The overall prevalence of infection in school children (5-16 years old) in the three villages was 61.1% based on the examination of one urine sample. Almost 10% greater prevalence was found when four consecutive daily urines were examined compared to one in the same study group sampled 1 month apart. There was a rapid increase in prevalence with age, reaching a maximum at age 10 with relatively little fluctuation to age 16 years. When comparing the age prevalence data with the intensity of infection expressed as either mean or median age excretion per milliliter urine, it was found that both were parallel and rose sharply from age 5-10 years, but the latter significantly declined several years prior to any perceptible diminution in prevalence.

Adolescent↗

PubMed1981

Induction of protective immunity to Strongyloides ransomi in pigs.

Pigs inoculated once or twice with infective Strongyloides ransomi larvae (L3) developed a strong protective immunity to challenge exposure. Intestinal expulsion of adult worms resulting from initial infection occurred 3 to 4 weeks after inoculation; worm loss reached 68% by 52 days after inoculation. Necropsy of pigs at various times after challenge exposure with infective L3 revealed that the majority of migrating L3 were eliminated before reaching the intestine; based on parasitic recoveries from the lung, the reduction was manifested as early as 48 hours after challenge exposure, Evidence for enhanced migration of L3 to the fat tissue in immune pigs could not be detected. Data indicate that infective L3 possess functional antigens capable of inducing protective immunity. Treatment of infected pigs with ivermectin was effective in removing arrested L3 in the subventral fat; 85% of these larvae were eliminated in 3 weeks. The role of milk-transmitted arrested L3 in the immunology of porcine strongyloidiasis is discussed.

Animals↗

PubMed1981

Protective role of immunoglobulin G in immunity to Strongyloides ratti.

Serum transfer from hyperimmune rats provided a significant degree of protection against Strongyloides ratti in mature, recipient rats. Eight immune serum pools tested were effective; however, the level of protection, as measured by challenge worm recoveries, ranged from 32 to 91%. Protection did not increase consistently with increasing volumes of immune serum, although as little as 5.0 ml/100 g of body weight afforded consistent protection against challenge infection. The protective effect was exerted against the early migrating tissue stages of the larvae; immune serum given 24 hr after challenge or later had no effect. The specificity of the immune serum's protection was suggested by the removal of this activity by absorption with heat-killed larvae, which have been shown to induce protection by immunization. Fractionation of immune serum showed that a heat-stable 7S component was responsible for protection; no protective activity could be detected in the 19S fraction. Further resolution of the 7S fraction by DEAE ion-exchange chromatography confirmed that the serum's protective activity was in the IgG component. The greatest protection was obtained with the fraction containing predominantly IgG1. In vitro sensitization of infective larvae with rat antibody failed to alter in vivo viability.

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