Biomedical subjects

G B Craig

Publications and source records attributed to G B Craig.

At least 19 recordsLinked to original sources

PubMed1997

Decreased fat and nitrogen losses in patients with AIDS receiving medium-chain-triglyceride-enriched formula vs those receiving long-chain-triglyceride-containing formula.

OBJECTIVE: The purpose of this study was to compare two enteral formulas, differing only in fat source, for product acceptance, tolerance, and effect on fat malabsorption and nutritional status in subjects with acquired immune deficiency syndrome (AIDS). DESIGN: The double-blind, randomized 15-day trial was divided into a 3-day period in which solid food was consumed followed by a 12-day experimental period in which liquid formulas were consumed. SETTING/SUBJECTS: Twenty-three men and one woman with AIDS and fat malabsorption completed the study. The study was conducted in the General Clinical Research Center, University of Alabama Hospital, University of Alabama at Birmingham. Laboratory assays were performed in the Department of Nutrition Sciences. INTERVENTIONS: After 3 days of consuming a controlled, solid food diet containing 100 g fat per day from mixed sources to document fat malabsorption, subjects were randomly assigned to one of two groups. Each group received a liquid formula containing 35% of energy as fat for 12 days. One group received a formula containing 85% medium-chain triglycerides (MCTs) and the control group received a formula containing 100% long-chain triglycerides. MAIN OUTCOME MEASURES: Determinations included stool number, consistency, weight, and fat and nitrogen content; urine nitrogen and creatinine levels; and body weight. STATISTICAL ANALYSIS PERFORMED: Subject demographic and other baseline characteristics were compared using two-sample t tests; stool and urine assessments were compared between groups at the initial experimental period using two-sample t tests; changes from initial to final experimental periods were assessed by means of analysis of covariance; changes in pooled intake, body weight, and the number and consistency of bowel movements were also assessed using analysis of covariance. All statistical tests were two-tailed and considered significant at P < .05. RESULTS: Within-group comparisons indicated that subjects fed the MCT formula showed significantly decreased stool fat and stool nitrogen content (P = .01 and P = .03, respectively) and increased fat absorption (P = .03), whereas those fed the control formula did not. Differences in stool fat between the groups were not statistically significant. However, the difference in fat absorption from the initial to final formula period was significant (P = .04). Subjects consuming the MCT formula also tended to have a decreased number of bowel movements and abdominal symptoms, whereas subjects fed the control formula showed no improvement. All subjects maintained their body weights. APPLICATIONS: There may be advantages to using an MCT-based formula in the treatment of AIDS-associated malabsorption.

Acquired Immunodeficiency Syndrome↗

PubMed1995

Estimates of population size, dispersal, and longevity of domestic Aedes aegypti aegypti (Diptera: Culicidae) by mark-release-recapture in the village of Shauri Moyo in eastern Kenya.

Estimates of the absolute size of a domestic population of Aedes aegypti aegypti (L.) were made in the Rabai area of Kenya, based on a single release, followed by either single or repeated recaptures. From single recapture within 24 h of release, the size of the female Ae. a. aegypti population in the Shauri Moyo village was estimated by the Lincoln index to be 365. Using a single release and repeated recaptures, population size was estimated by Jackson's positive method to be 337. Depletion of the unmarked females by daily removal sampling provided us with two additional, direct estimates of the size of the village population (451 by Kano's method and [464 +/- 18.9 SEM] by the Moran-Zippin method). The longevity of marked females was at least 9 d. The day-to-day movement of marked mosquitoes revealed the dispersal pattern of Ae. a. aegypti among houses clustered within different distance zones. Marked mosquitoes reached all houses of the village within 24 h of release. After 5 d, the dispersion of both marked and unmarked mosquitoes among houses was similar.

Animal Identification Systems↗

PubMed1995

Aedes albopictus (Diptera: Culicidae) eggs: field survivorship during northern Indiana winters.

Aedes albopictus (Skuse) is an Asian mosquito that recently has colonized North America via used tire transport. Temperate Ae. albopictus populations overwinter as diapausing eggs, but tropical populations cannot diapause. Eggs of tropical (SABAH) and temperate (INDY) Ae. albopictus were obtained in diapause-inducing conditions and placed inside a scrap tire to monitor overwintering survival in northern Indiana during the winters of 1989-1990 and 1990-1991. Diapause eggs of Ae. triseriatus (Say), a native North American mosquito, were included for comparison. Tropical Ae. albopictus from Malaysia did not survive either winter. Temperate Ae. albopictus from Indianapolis, IN, did not survive the winter of 1989-1990, but 78% survived the winter of 1990-1991. In contrast, 92 and 96% of Ae. triseriatus survived the winters of 1989-1990 and 1990-1991, respectively. Neither mean temperature nor absolute minimum temperature (a winter's lowest temperature) accurately predicted Ae. albopictus overwintering survivorship in the field. The possible effect of snow and other insulating materials on the overwintering survivorship of Ae. albopictus eggs is discussed.

Adaptation, Physiological↗

PubMed1995

Parasitism of Aedes aegypti and Ae. albopictus (Diptera: Culicidae) by Ascogregarina spp. (Apicomplexa: Lecudinidae) in Florida.

Aedes aegypti (L.) and Ae. albopictus (Skuse) from 40 sites in 17 counties of Florida were surveyed for gregarine parasites during the spring and autumn of 1993 and in July 1994. Larvae collected from containers (mainly tires) were dissected to determine the number of gregarine trophozoites present. Ascogregarina spp. were found at 70% of the sites and occurred as frequently in Ae. aegypti populations as in Ae. albopictus. Within sites, parasite distributions were highly variable and aggregated in host populations. Parasite loads ranged from 1 to 486 trophozoites per host. Mean parasite load was significantly higher in Ae. aegypti larvae (52.5 per host) than in Ae. albopictus (33.5 per host). Parasite prevalence was significantly higher in Ae. aegypti populations that were not sympatric with Ae. albopictus compared with allopatric Ae. albopictus or sympatric populations of either species. In sympatric populations, Ae. aegypti tended to have equal or higher parasite prevalence than the cohabiting Ae. albopictus. Ascogregarina taiwanensis (Lien & Levine) prevalence in Ae. albopictus was significantly higher in areas where these hosts have been present for at least 3 yr. These data contribute to the hypothesis that parasite-mediated competition may be a factor in the apparent displacement of Ae. aegypti by Ae. albopictus in Florida.

Aedes↗

PubMed1995

Relationship between cold hardiness and supercooling point in Aedes albopictus eggs.

For many insects, low temperatures are not lethal unless their tissues freeze. To determine whether freezing is the cause of low temperature mortality of Aedes albopictus eggs, we measured their lower lethal temperature, the temperature that causes 50% mortality in a population, and supercooling point, the temperature at which the tissues freeze. Tropical and temperate Ae. albopictus eggs were tested under different diapause and cold acclimation conditions. Temperate Ae. albopictus eggs had a lower lethal temperature than tropical Ae. albopictus eggs. Diapause and cold acclimation decreased the lower lethal temperatures of temperate eggs. However, neither diapause, cold acclimation, nor geographic origin affected Ae. albopictus egg supercooling points. All lower lethal temperatures were above -13 degrees C and all supercooling points were below -26 degrees C, indicating prefreeze mortality. Eggs of Aedes triseriatus and Aedes aegypti also died before they froze.

Acclimatization↗

PubMed1995

Comparative susceptibility of larvae of three Aedes species to malathion and permethrin.

Larvae of Aedes hendersoni, Ae. atropalpus, and 6 geographic strains of Ae. triseriatus were compared in terms of their susceptibility to malathion and permethrin. Aedes atropalpus was most tolerant to malathion, whereas Ae. triseriatus (Walton strain) was most tolerant to permethrin. Malathion LC50S for 6 geographic strains of Ae. triseriatus ranked from high to low were: Alabama (ALA) > Michigan (UNDERC) > Indiana (WAL) > Kentucky (UKEN) > Texas (SAL) > Florida (VB); similar ranking of permethrin LC50S resulted in: WAL > VB > SAL > UKEN > UNDERC > ALA. Differences in susceptibility were detected but were not considered large (i.e., over several orders of magnitude). As a result, no change in application rate of malathion or permethrin, from an operational viewpoint, would be warranted if used against these 3 mosquito species or the geographic strains of Ae. triseriatus investigated.

Aedes↗

PubMed1994

Cold acclimation, diapause, and geographic origin affect cold hardiness in eggs of Aedes albopictus (Diptera: Culicidae).

Eggs of five strains of Aedes albopictus (Skuse) were obtained in both diapause and nondiapause conditions and exposed to various cold acclimation regimes in the laboratory, after which they were subjected to diverse chilling treatments. Larvae that survived chilling as eggs survived to the pupal stage. Eggs of Aedes aegypti (L.) and Aedes triseriatus (Say) were included as control species. Eggs of temperate Ae. albopictus were more cold-hardy than eggs of Ae. aegypti but less cold-hardy than the eggs of Ae. triseriatus. Cold acclimation and diapause enhanced cold hardiness of only temperate Ae. albopictus. Cold acclimation had a greater influence on cold hardiness than did diapause. Both the temperature and the duration of cold acclimation modulated cold hardiness. Cold hardiness induced in the laboratory was similar to cold hardiness induced in the field in northern Indiana. The cold hardiness of Ae. albopictus from central Florida was intermediate in comparison with temperate and tropical strains. Tropical Brazilian Ae. albopictus and tropical Asian Ae. albopictus were similar in cold hardiness.

Acclimatization↗

PubMed1994

Aedes albopictus (Diptera: Culicidae): a statistical model of the role of temperature, photoperiod, and geography in the induction of egg diapause.

Aedes albopictus (Skuse) lays eggs refractory to hatching in response to several environmental cues. The goal of this statistical treatment was to quantify the role and interaction of latitude and country of origin (Japan and the United States), photoperiod, rearing/holding temperature, and a newly identified element, elevation of the site of origin, with critical photoperiod (Cpp). We also describe the development of an equation relating the incidence of diapause to daylength, rearing/holding temperature, and latitude and elevation of the site of origin, an equation useful in the development of a simulation model of the population dynamics and distribution of Ae. albopictus in North America. The analysis indicated that elevation from 0 to 300 m is significantly correlated with Cpp. The results also corroborate earlier conclusions that, on the basis of a shallower geographical cline in photoperiodic response in the United States, North American strains of Ae. albopictus have a temperate origin in Asia and indicate that the rapid spread of this mosquito within the United States via the distribution of used tires resulted in founder populations that were only partially adapted in diapause response to local conditions.

Aedes↗

PubMed1994

Morphology of long- and short-day eggs of Aedes atropalpus and A. epactius (Diptera: Culicidae).

Scanning electron micrographs are used to document differences in the shape and fine structure of long-day (16:8 [L:D] h) and short-day (8:16 [L:D] h) eggs of Aedes atropalpus (Coquillett) and Aedes epactius Dyar & Knab from Illinois. Both shape and structural detail differed much more in A. atropalpus than in A. epactius. Long-day eggs of A. atropalpus were significantly longer and narrower; their outer chorionic cells on both the ventral (upper) and lateral surfaces were significantly smaller in area, with fewer small tubercles, and the detailed structure, shown in a comprehensive series of micrographs, was distinctly different than those of the short-day eggs. Dimensional differences of the whole egg were much less apparent in A. epactius; only width was significantly greater in short-day eggs. However, the ventral and lateral chorionic cells in the 2-d length groups showed the same highly significant differences in area and numbers of small tubercles as in A. atropalpus. Fine structural differences also were much less apparent in the eggs of A. epactius.

Aedes↗

PubMed1994

Dispersal and survival of Aedes albopictus at a scrap tire yard in Missouri.

Field-reared Aedes albopictus were marked with fluorescent pigment upon release and recaptured with a vacuum aspirator at a scrap tire yard and in surrounding vegetation in Potosi, MO, during 1989-90. In 8 dispersal trials, 8.1% (1,100/13,513) of the Ae. albopictus were recaptured with 84.4% (928/1,100) collected in the forest edge ecotone between 10 and 600 m from the release point. The maximum dispersal distance recorded was 525 m and 11.1% (122/1,100) dispersed further than 100 m. In 3 survival trials, 4.8% (2,660/55,284) of the mosquitoes were recaptured. Adult Ae. albopictus females survived an average of 8.2 days (probability of daily survival [PDS] = 0.89, range = 0-24) and males an average of 3.9 days (PDS = 0.77, range = 0-12). The dispersal and survival capacity of Ae. albopictus adults may contribute to the spread and potential health threat of this mosquito in the USA.

Aedes↗

PubMed1994

Blood hosts of Aedes albopictus in the United States.

Bloodfed Aedes albopictus were collected during 1989-91 by vacuum aspirator from rural and urban study sites in Missouri, Florida, Indiana, Illinois, and Louisiana. Blood hosts identified by ELISA and precipitin tests were rabbit (n = 91), Rattus sp. (n = 69), dog (n = 14), unidentified mammal (n = 14), cow (n = 13), human (n = 10), deer (n = 10), sciurid (n = 7), turtle (n = 5), murid other than Rattus sp. (n = 4), raccoon (n = 3), passeriform bird (n = 3), and cat (n = 2). As an opportunistic bloodfeeder, Ae. albopictus may be a potential vector of domestic arboviruses and a nuisance pest where infestations occur.

Aedes↗

PubMed1993

Host-feeding patterns of Aedes albopictus (Diptera: Culicidae) at a temperate North American site.

Precipitin tests and ELISA were used to investigate host-feeding patterns of 172 blood-fed Aedes albopictus (Skuse) collected at Potosi, MO, during the summers of 1989 and 1990. One hundred ten (64.0%) mosquitoes had fed on mammals, 29 (16.9%) on birds, and none on turtles or snakes. Thirty-three (19.2%) mosquitoes failed to react in all tests. Eighty-six (78.2%) of the 110 mammalian feeds were positive for lower taxa as follows: rabbit, 24.5%; deer, 14.5%; dog, 13.6%; human, 8.2%; squirrel, 7.3%; opossum, 4.5%; myomorph rodents other than Rattus, 3.6%; raccoon, 0.9%; and bovine, 0.9%. Positive feeds were not detected for the following mammals: cat (n = 99); horse (n = 95); Rattus (n = 84); and swine (n = 84). Fourteen (48.3%) of the 29 avian feeds were positive for lower taxa as follows: Passeriformes, 24.1%; Columbiformes, 17.2%; Ciconiiformes, 3.4%; and quail, 3.4%. These data, the first on host-feeding patterns for Ae. albopictus populations in the New World, indicate that Ae. albopictus is an opportunistic feeder that utilizes a wide variety of hosts and, therefore, has the potential to become involved in the transmission cycles of indigenous arboviruses.

Aedes↗

PubMed1993

Records of mosquito-parasitic mermithid nematodes in the northcentral United States.

Mermithid parasites (Nematoda: Mermithidae) were observed in 11 mosquito species in 22 counties of Indiana, Michigan, Minnesota, Ohio and Wisconsin. Natural hosts included adult Aedes vexans, Ae. canadensis, Ae. cinereus, Ae. diantaeus, Ae. punctor, Anopheles punctipennis and Coquillettidia perturbans and larvae of Ae. abserratus, Ae. canadensis, Ae. cinereus, Ae. communis, Ae. diantaeus, Ae. provocans, Ae. punctor, Ae. stimulans and Cq. perturbans. These are the first records of such parasites in Indiana, Minnesota, Ohio and Wisconsin.

Aedes↗

PubMed1993

Reducing the overwintering ability of Aedes albopictus by male release.

Eggs of temperate Aedes albopictus populations are cold hardy and can diapause, but tropical populations are not cold hardy and cannot diapause. Heterozygotes possess intermediate diapause and cold hardiness. Males of a tropical strain from Malaysia with a distinctive genetic marker were released into an existing temperate population in East St. Louis, Illinois. Subsequent egg samples from the release site had genetic marker frequency of up to 24%. Reduced cold hardiness and decreased diapause incidence were also observed in the release site population. No such changes occurred at a nearby control site. The rank order of overwintering survival of eggs at the release site was: Aedes triseriatus > temperate Ae. albopictus > hybrid temperate/tropical Ae. albopictus > tropical Ae. albopictus. Eggs collected from the release population the next summer showed total absence of the genetic marker; presumably carriers were removed by the winter.

Aedes↗

PubMed1992

Isolation of eastern equine encephalitis virus from Aedes albopictus in Florida.

Fourteen strains of eastern equine encephalitis (EEE) virus were isolated from Aedes albopictus mosquitoes collected in Polk County, Florida. These are the first isolations of an arbovirus of proven public health and veterinary importance from naturally infected Ae. albopictus in the United States since established populations of this introduced mosquito were first discovered in 1985. The widespread distribution of Ae. albopictus in Florida and in other areas of the United States where EEE is endemic raises concern that this species may become an epizootic and epidemic vector of EEE virus.

Aedes↗

PubMed1992

Differential oviposition by Aedes hendersoni and Aedes triseriatus (Diptera: Culicidae) in response to chemical cues associated with treehole water.

The oviposition behavior of Aedes hendersoni Cockerell and Aedes triseriatus (Say) was examined in the laboratory by offering gravid females oviposition sites containing water from different treehole types and by varying the physical characteristics of oviposition sites. Ae. hendersoni females oviposited more frequently in containers with water from treeholes in which they are found commonly in nature (maple "deep rotholes") than in containers with water from holes in which they are found rarely (beech "pans"). In contrast, Ae. triseriatus eggs were distributed uniformly in containers holding the two types of treehole water. There were no differences between species in response to oviposition container height or orientation of the entrance hole (vertical or horizontal). Females of both species laid nearly all their eggs in containers with horizontal openings, and most were deposited at the higher of two levels. We suggest that the adaptive value of the oviposition behavior of Ae. hendersoni is to maximize fitness by reducing interspecific contact with Ae. triseriatus.

Aedes↗

PubMed1992

Vector competence of Aedes hendersoni (Diptera: Culicidae) for La Crosse virus: lack of impaired function in virus-infected salivary glands and enhanced virus transmission by sporozoite-infected mosquitoes.

Previous research has shown Aedes hendersoni Cockerell to be an incompetent vector of La Crosse (LAC) virus because of a salivary gland escape (SGE) barrier; that is, the salivary glands are infected but the mosquito fails to transmit the virus orally. Intradermal probing behavior and ability to locate blood were studied in infected mosquitoes as indicators of salivary gland impairment to determine if the SGE barrier was due to virus-induced pathology of the salivary glands. No evidence of salivary gland impairment as a result of virus infection was detected in infected Ae. hendersoni. This was also true for Aedes triseriatus (Say), a competent vector of LAC virus, which was used as a control. However, coinfection of Ae. hendersoni with Plasmodium gallinaceum and LAC virus dramatically increased virus transmission (72 versus 8%), whereas transmission by coinfected Ae. triseriatus was not significantly affected. Possible causes for the SGE barrier in Ae. hendersoni are discussed.

Aedes↗

PubMed1992

Influence of temperature and larval nutrition on the diapause inducing photoperiod of Aedes albopictus.

Photoperiod induced dormancy for 14 North American strains of Aedes albopictus were determined at 21, 26 and 29 degrees C. Strains tested at 21 degrees C and intermediate temperatures of 25-27 degrees C demonstrated clear photoperiodic responses whereas temperatures of 29 degrees C and above, greatly reduced or negated diapause incidence. A suboptimal larval diet increased the percentage diapause in eggs laid by resulting adults. This larval diet was also associated with a slight increase in critical photoperiod.

Aedes↗