Biomedical subjects

R C Axtell

Publications and source records attributed to R C Axtell.

At least 19 recordsLinked to original sources

PubMed2003

Blastomyces dermatitidis lysate antigens: antibody detection in serial serum specimens from dogs with blastomycosis.

Yeast phase lysate antigens prepared from different isolates of Blastomyces dermatitidis (T-58, dog-Tennessee; T-27, polar bear-Tennessee; ERC-2, dog-Wisconsin; ER-3, woodpile-Wisconsin) were compared with respect to the detection of antibodies (indirect enzyme-linked immunosorbent assay-ELISA, peroxidase system) in 126 serial serum specimens (pre-treatment, 30 and 60 days post-treatment with itraconazole) from 42 dogs with diagnosed blastomycosis. Mean absorbance values observed with the four lysate antigens at the three treatment intervals ranged from the most reactive to the least reactive as follows: T-58 (0.270, 0.210, 0.136); T-27 (0.209, 0.156, 0.096); ER-3 (0.189, 0.144, 0.089) and ERC-2 (0.158, 0.129, 0.080). Even though variations in reactivity were evidenced, the lysates prepared from isolates from various geographical regions and sources were all efficacious as antigens for the immunodiagnosis of canine blastomycosis.

Animals↗

PubMed2002

Serological differences in two Blastomyces dermatitidis isolates from different geographical regions of North America.

Yeast phase lysate antigens were prepared from two isolates (T-58 and ERC-2) from different geographic locations. Tennessee and Wisconsin. These lysate were evaluated with respect to their ability to detect antibody in dogs infected with blastomycosis and rabbits immunized with the lysates by an enzyme linked immunosorbent assay (ELISA). Both the dog sera and rabbit sera assays demonstrated that there were serological differences in these two isolates, which implied that there was antigenic variance in geographical populations of B. dermatitidis. These results correlated with a previous molecular study that indicated that there are genetic differences in different geographical populations of the organism.

Animals↗

PubMed2002

Comparison of seven Blastomyces dermatitidis antigens for the detection of antibodies in humans with occupationally acquired blastomycosis.

Yeast phase lysate antigens, prepared from seven isolates of Blastomyces dermatitidis (dogs, T-58, M-98; human, Le; soil, S; sea lion, SL; polar bear, PB; cat, C) were assayed by enzyme-linked immunosorbent assay (ELISA) to detect antibodies in human sera. The sera were from individuals potentially exposed to B. dermatitidis while working on a prairie dog relocation project in Colorado. All antigens exhibited greatest reactivity with three specimens in two separate assays. Absorbance values ranged from 0.370 (M-98) to 0.427 (LE) (Trial 1) and from 0.579 (M-98) to 0.714 (PB) (Trial 2) with serum 2; from 0.368 (C) to 0.453 (LE) (Trial 1) and from 0.565 (SL) to 0.694 (S) (Trial 2) with serum 3 and from 0.392 (M-98) to 0.506 (LE) (Trial 1) and from 0.557 (SL) to 0.758 (T-58) (Trial 2) with serum 6. The greatest reactivity was observed with sera from two persons (2 and 3 from the same individual and serum 6) who became ill with symptoms of pulmonary disease and sought medical care. Both patients were subsequently diagnosed with blastomycosis by microscopic and culture methods. The study indicated that all of the lysate antigens, regardless of source, could be used to reliably diagnose blastomycosis.

Animals↗

PubMed2002

Serological differences in three Blastomyces dermatitidis strains.

Yeast phase lysate antigens, prepared from three isolates of Blastomyces dermatitidis (T-58, Tennessee dog; 48089, Zaire human; ERC-2, Wisconsin dog) were assayed for their ability to detect antibodies in human sera, dog sera and sera from rabbits immunized with each of the lysate antigens. The dog sera were from animals diagnosed with blastomycosis from various endemic regions in North America. T-58 and ERC-2 lysate antigens exhibited a high reactivity with the serum from dogs infected with blastomycosis; however, 48089 lysate showed low reactivity with the same sera. With the immunized rabbit sera, 48089 lysate was the only lysate with a high reactivity with the 48089 serum and it exhibited little reactivity with the heterologous sera. The T-58 and ERC-2 lysate antigens reacted minimally with the 48089 serum but reacted highly with both the T-58 and ERC-2 sera. The human sera were from individuals potentially exposed to B. dermatitidis while working on a prairie dog relocation project in Colorado. Remarkably, all three lysate antigens could detect antibodies in the individuals diagnosed with blastomycosis. This study indicated that there were serological differences in the 48089 Zaire lysate compared with the other lysate antigens and it may be designated serotype 2.

Animals↗

PubMed1999

Sensilla of the antennae and maxillary palps of Culicoides hollensis and C. melleus (Diptera: Ceratopogonidae).

The types and arrangement of the sensilla on the female antennae and maxillary palps of both sexes of 2 estuarine species of biting midges, Culicoides hollensis (Melander & Brues) and C. melleus (Coquillett), were studied by scanning electron microscopy. Five sensillum types are found on the antennae of both species. Both species have sharp-tipped sensilla trichodea and sensilla basiconica only on subsegments 9-13 and blunt-tipped sensilla trichodea on all subsegments. Sensilla coeloconica occur on subsegment 1 of both species and various other subsegments depending on the species. Sensilla chaetica are found on all subsegments of C. melleus, but only on subsegments 1-8 and 13 on C. hollensis. Both sexes of C. hollensis have either 1 or 2 pits on the 3rd segment of the maxillary palps, which contain 8-15 bulb-shaped sensilla in females compared with 5-6 in males. No pit is found on the maxillary palps of either sex of C. melleus, but rather the bulb-shaped sensilla are distributed individually on this segment, ranging from 13 to 29 on the female and 6-10 on the male palps. These data are compared with data obtained from previously published light and electron microscopical studies of biting midge sensory structures.

Animals↗

PubMed1996

Temperature-dependent development and survival of the lesser mealworm, Alphitobius diaperinus.

Development, growth and survival of the lesser mealworm, Alphitobius diaperinus (Panzer), were determined at six constant temperatures. No egg hatch or larval development occurred at 17 degrees C. At temperatures of 20, 25, 30, 35 and 38 degrees C the median development times (days), respectively, were for eggs (13.4, 6.0, 4.4, 2.6 and 2.6), larvae (133.0, 46.0, 26.2, 22.4 and 23.9), pupae (17.0, 8.0, 5.5, 4.0 and 4.1), and from oviposition to adult emergence (164.4, 60.2, 37.9, 29.0 and 30.8). The Sharpe & DeMichele (1977) model was used to describe the temperature-dependent development. The mean egg survival (hatching) ranged from 61% to 86%, with lowest hatch at 20 degrees C. Survival of the larvae and pupae ranged from 32% to 73% and from 85% to 95%, respectively, with lowest survival at 20 degrees C. Pupae had significantly lower weights at 35 degrees C and adults at 38 degrees C than at the other temperatures. Female pupae (20 mg) and female adults (16 mg) were significantly heavier than male pupae (17 mg) and male adults (13 mg). Adults (0.5-9 months old) laid 4-7 eggs per female per day at 25 degrees C.

Animals↗

PubMed1995

Feeding behavior and growth of broiler chicks fed larvae of the darkling beetle, Alphitobius diaperinus.

Experiments were conducted to determine the effects of feeding larvae of the darkling beetle (lesser mealworm), Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) to broiler chicks on chick growth. Chicks readily fed on the larvae and exhibited reduced growth in the absence of other feed. Chicks 3 to 8 d old restricted to a diet of only larvae consumed 1,552 +/- 172 (mean +/- SD) larvae per chick per day and their body weights were significantly less (mean = 84 g) at the end of the 6 d than for chicks on starter feed during the same time. After return to starter feed for 8 d after feeding on larvae for 6 d, the chicks did not compensate for the reduced weight and their body weights were significantly less (mean = 170 g) than for chicks on starter feed for the 14 d. Chicks from age 2 through 9 d were given a choice between broiler starter feed and darkling beetle larvae. The numbers (mean +/- SD) of larvae consumed per chick per day were: 389 +/- 18, 631 +/- 14, 496 +/- 20, and 287 +/- 33, for Days 2 to 3, 4 to 5, 6 to 7, and 8 to 9, respectively. The body weight of chicks feeding on starter feed and larvae was significantly greater than the weight of chicks consuming feed only. In the presence of larvae, the mean feed consumption per chick was less than for chicks provided with only starter feed. The beetle larvae were 68% crude protein and 21% fat (DM basis) and had higher amounts of 18 amino acids than the starter feed.

Animal Feed↗

PubMed1994

Comparisons of sampling methods and seasonal abundance of Drosophila repleta in caged-layer poultry houses.

Four sampling methods were compared to determine their practicality and suitability for detecting population fluctuations of adult Drosophila repleta, a pest in caged-layer poultry houses. Five caged-layer poultry houses with gutter-flush manure removal systems in Franklin County, North Carolina, U.S.A., were sampled once every 2 weeks over 15 months, from June 1991 to August 1992. The flies were most abundant during the spring and early summer. Visual counts of adult flies resting on the feed troughs in front of cages in the aisles and counts of flies caught on a sticky ribbon lowered into the gutter used for manure removal by flushing were more satisfactory sampling methods than using counts of flies caught on sticky ribbons carried along the aisles or aspirator collections from the gutters. For the visual count method, the effects of location in the house, within each aisle, and feed trough height were determined; two counts on feed troughs in each of two inside rows of cages were sufficient to measure population changes. For routine monitoring of D. repleta populations, visual counts of flies resting on the feed troughs in the front area of two aisles and catching flies on sticky ribbons inserted into the rear gutter area are recommended.

Animals↗

PubMed1994

Feeding behavior and growth of turkey poults fed larvae of the darkling beetle, Alphitobius diaperinus.

Experiments were conducted to determine the effects of feeding larvae of the darkling beetle (lesser mealworm), Alphitobius diaperinus (Panzer) [Coleoptera:Tenebrionidae], to turkey poults on poult growth and of beak trimming on poult feeding on the larvae. Young turkey poults readily fed on the larvae and exhibited reduced growth in the absence of other feed. Poults 3 to 5 d old restricted to a diet of only larvae consumed 259 +/- 99 (+/- SD) larvae per poult per day and their body weights were significantly lower (mean = 30 g) at the end of the 3 d than for poults on starter feed during the same time. After return to starter feed for 16 d after feeding on larvae for 3 d, the poults did not compensate for the weight loss although weight gains were normal. Poults from 2 through 10 d of age were given a choice between starter turkey feed and darkling beetle larvae. The numbers of larvae consumed per poult per day were: 174 +/- 8 for Days 2 to 4, 221 +/- 3 for Days 5 to 7, and 189 +/- 80 for Days 8 to 10. There was no significant difference between the body weight of poults feeding on larvae and starter feed compared with that of poults consuming feed only. In the presence of larvae, the mean feed consumption per poult was lower than for poults provided with only starter feed. The beetle larvae were 68% crude protein and 21% fat (DM basis) and had higher amounts of 18 amino acids than the starter feed. Poults that were beak trimmed consumed only about one-third as many larvae as poults with intact beaks. Poults (1 to 3 d old) with intact beaks consumed 169 +/- 20 larvae per poult per day; poults with trimmed beaks consumed 58 +/- 23 larvae per poult per day.

Animal Feed↗

PubMed1993

Susceptibility of the bedbug, Cimex lectularius, to selected insecticides and various treated surfaces.

Adult bedbugs, Cimex lectularius, were exposed for 24 h (25 degrees C) to filter paper treated with various dilutions of the technical grade of nine insecticides dissolved in acetone to determine the concentration-response relationships. The order of toxicity, from most to least based on the LC50's was: dichlorvos, pirimiphos methyl, lambda-cyhalothrin, bendiocarb, permethrin, malathion, carbaryl, tetrachlorvinphos, and fenvalerate. The residual toxicities of commercial formulations of six of the chemicals diluted with water and applied to wood, cardboard, cloth and galvanized metal, were determined by exposing adult bedbugs at 3, 7 and 12 weeks after treatment. The formulation of bendiocarb (FICAM 76% W) had little residual activity on all surfaces at 12 weeks after treatment. The formulation of carbaryl (SEVIN 21.5% L) was toxic to bedbugs on all surfaces at 12 weeks after treatment, but required high concentrations on wood, cardboard, and cloth. The formulation of pirimiphos methyl (ACTELLIC 57% EC) had no residual activity on any of the surfaces at 12 weeks after treatment. The formulation of tetrachlorovinphos (RABON 50% W) had residual activity for 12 weeks on all surfaces except metal. The formulation of permethrin (ATROBAN 11% EC) had residual activity on only metal and wood while the formulation of lambda-cyhalothrin (KARATE 13.1% EC) had residual activity 12 weeks on all surfaces.

Animals↗

PubMed1991

Susceptibilities of northern fowl mite, Ornithonyssus sylviarum (Acarina: Macronyssidae), and chicken mite, Dermanyssus gallinae (Acarina: Dermanyssidae), to selected acaricides.

The relative toxicities of ten acaricides to northern fowl mite, Ornithonyssus sylviarum (Canestrini and Fanzago), and the chicken mite, Dermanyssus gallinae (De Geer), were determined simultaneously by holding the mites inside disposable glass Pasteur pipettes previously immersed in acetone solutions of various concentrations (w/v) of technical grade acaricides. The LC90s (parts per million) of the acaricides after 24 h exposure for the northern fowl mite and the chicken mite, respectively, were: bendiocarb (13.1, 0.18), tetrachlorvinphos (14.5, 4.07), carbaryl (15.0, 0.83), pirimiphos methyl (18.3, 2.03), permethrin (23.1, 8.46), lambda cyhalothrin (80.7, 11.4), dichlorvos (252.8, 3.75), malathion (238.4, 6.59), amitraz (6741, 9430) and fenvalerate (greater than 10,000, 60.2). After 48 h exposure there were only slight increases in mortalities of both species except for increased mortalities for the northern fowl mite with lambda cyhalothrin, amitraz and fenvalerate, and for the chicken mite with amitraz.

Animals↗

PubMed1991

Temperature-dependent development of the fungal pathogen Lagenidium giganteum (Oomycetes: Lagenidiales) in larvae of Culex quinquefasciatus (Diptera: Culicidae).

The rates of development of Lagenidium giganteum were determined in the four larval instars of Culex quinquefasciatus Say held at 15, 20, 25, 27, 30, and 34 degrees C. The fastest development was in second instars held at 34 degrees; vesicles and oospores occurred in 50% of the larvae (the median development time) 19.7 and 25.0 h, respectively, after infection. The greatest median time to the formation of vesicles was in third instars at 15 degrees C (185.6 h) and for oospores was in second instars at 15 degrees C (152.3 h). The fungus did not form oospores in fourth instars at 15 degrees C. The median developmental rates of vesicles and oospores in each instar were fit to the Sharpe & DeMichele model, which may be used to predict the effects of different temperatures on the in-vivo developmental rate of the fungus.

Animals↗

PubMed1991

Retention of larvicidal activity after feeding cyromazine (Larvadex) for the initial 20 weeks of life of single comb White Leghorn layers.

Single Comb White Leghorn pullets were fed cyromazine (Larvadex) continuously at levels of 0, 25, 250, and 1,000 mg/kg diet (ppm) from hatch to 20 wk of age. Fresh manure was bioassayed for toxicity to housefly, Musca domestica, larvae beginning at the 6th wk after removal of cyromazine from the feed, and at weekly intervals thereafter. At 6 wk after removal of the feed additive there was 51.6% fly mortality at 25 ppm, 75.7% at 250 ppm, and 86.5% at 1,000 ppm relative to the 0-ppm control. Fly mortality decreased to less than 10.7% mortality at 13 and 15 wk postremoval for hens grown on 25 ppm and 250 ppm cyromazine, respectively. Hens grown on 1,000 ppm cyromazine produced manure that was still exhibiting more than 50% fly mortality 20 wk after removal of the feed additive. These data demonstrate retention of cyromazine in laying hens for up to 20 wk after feeding the chemical to the birds at 5 to 200 times greater than the maximum recommended rate for the initial 20 wk of life.

Administration, Oral↗

PubMed1991

Compatibility of Bacillus thuringiensis var. Israelensis and Bacillus sphaericus with the fungal pathogen Lagenidium giganteum (Oomycetes: Lagenidiales).

Larvae of Culex quinquefasciatus were exposed to infection by Lagenidium giganteum and various concentrations of B.t.i. or B. sphaericus. The resulting larval mortalities, percentages of infected dead larvae and percentages of larval body regions containing the fungus were compared. Overall, the effectiveness of Lagenidum giganteum against the larvae was not significantly affected by the presence of B.t.i. or B. sphaericus, and the fungal and bacterial agents were compatible. In experiments using 3-day-old larvae, the extent of growth of the fungus in the infected larvae and the percentage of the larvae infected were related to the concentration of B.t.i. in the range of 0.057-0.456 ITU/ml tested but were not related to the concentration of B. sphaericus in the range of 0.6-4.8 x 10(4) spores/ml. With larvae of various ages treated with a low concentration of B.t.i. (0.114 ITU/ml), exposure to the fungus increased the mortality rate in early but not late instars. After single and multiple applications of B.t.i. and B. sphaericus in the presence of the fungus, followed by drying and reflooding, the fungus persisted and reinfected larvae while the B. sphaericus persisted but the B.t.i. did not.

Animals↗

PubMed1991

Comparison of floating and sinking encapsulated formulations of the fungus Lagenidium giganteum (Oomycetes: Lagenidiales) for control of Anopheles larvae.

Floating calcium alginate capsules containing Lagenidium giganteum and 1% ground cork gave higher levels of control of Anopheles quadrimaculatus larvae in a 100-cm column of water than sinking capsules containing no cork. There was no significant difference between the cork capsules and the sinking capsules in the infection of larvae by the encapsulated fungus after storage (15 degrees C) for 57 days, although infectivity declined during that time from an initial infection rate of 100% to 35% and 40% for the cork and sinking capsules, respectively. Floating capsules containing glass bubbles were less effective than the cork capsules in the 100-cm column of water and had a shorter storage life than either sinking capsules or cork capsules.

Animals↗

PubMed1990

Temperature-dependent development and survival rates of Culex quinquefasciatus and Aedes aegypti (Diptera: Culicidae).

Development, growth, and survival of Culex quinquefasciatus Say and Aedes aegypti (L.) were determined at six constant temperatures (15, 20, 25, 27, 30, 34 degrees C). The Sharpe & DeMichele four-parameter model with high-temperature inhibition described the temperature-dependent median developmental rates of both mosquito species. In both species, body size generally decreased as temperature increased. Head capsule widths in all instars in both species were significantly greater at 15 than at 30-34 degrees C. Except for the third instar of Ae. aegypti, the larval body lengths in both species were significantly greater at 15 than at 34 degrees C. All instars and pupae of both species and the adults in Cx. quinquefasciatus were significantly heavier at 15 than at 27-34 degrees C. In Cx. quinquefasciatus, survival from eclosion to adult emergence was highest in the range from 20 to 30 degrees C (85-90%) and dropped drastically at 15 (38%) and 34 degrees C (42%). In Ae. aegypti, survival to adult stage was high at 20 (92%) and 27 degrees C (90%) and lowest at 15 degrees C (3%).

Aedes↗

PubMed1990

Longevity and fecundity of Musca domestica (Diptera: Muscidae) as a function of temperature.

Longevity and fecundity of adult house flies were determined at constant temperatures of 20, 25, 30, and 35 degrees C. At the four temperatures, respectively, the median mortality rates (1/days to 50% mortality) for females were 0.023, 0.041, 0.060, and 0.099 and for males were 0.029, 0.047, 0.066, and 0.085. The numbers of days for 50% of the eggs to be deposited for each temperature were 34.5, 21.3, 10.2 and 7.1, respectively. The total numbers of eggs deposited per female for each temperature were 184, 729, 709, and 506, respectively. Models were developed for longevity and fecundity and their distributions as functions of temperature.

Animals↗

PubMed1990

Parasitism of house fly (Musca domestica) pupae by four species of Pteromalidae (Hymenoptera): effects of host--parasitoid densities and host distribution.

Parasitoid-induced mortality of house fly, Musca domestica L., pupae and parasitoid progeny emergence by four species of pteromalid parasitoids, Muscidifurax raptor Girault & Sanders, M.zaraptor Kogan & Legner, Spalangia cameroni Perkins and S.endius Walker, were determined for a 24 h exposure period using parasitoid: host ratios ranging from 1:2 to 1:50. When the number of parasitoids was held constant (n = 5) and the numbers of hosts varied, and when the number of hosts was held constant (n = 100) and the number of parasitoids varied, both the number of pupae killed per parasitoid and the number of parasitoid progeny per parasitoid increased with increasing parasitoid:host ratios to reach an upper limit asymptotically. Maximum values were, respectively: M.raptor (14.7, 11.1), M.zaraptor (12.3, 9.3), S.cameroni (16.9, 5.5), S.endius (14.8, 9.7) with no consistent effects attributed to parasitoid interference. For M.raptor and S.cameroni at parasitoid:host ratios of 1:10, the pupal mortality and progeny emergence were determined for a 24 h exposure period when hosts were distributed in poultry manure at four levels of aggregation ranging from clumped to uniform. Pupal mortality was least in clumped distributions, while parasitoid progeny emergence was not significantly different.

Animals↗