Linkage of a gene causing malaria refractoriness to Diphenol oxidase-A2 on chromosome 3 of Anopheles gambiae.

An inbred line of the African malaria vector Anopheles gambiae is refractory to development of malaria parasites. It is homozygous for a 4.3-kb Sal I restriction fragment at the Dox-A2 locus, whereas the parent population is polymorphic at this locus, and a susceptible line is homozygous for an alternate 3.

A critical synopsis of the diagnostic and screening radiology outcomes literature.

In summary, the radiology outcomes research literature is both extensive and broad. The methodologic quality, however, is quite variable. Overall, this quality could be improved by intervention in two areas: methodologic dissemination and development.

Quantitative genetics of vector competence for dengue-2 virus in Aedes aegypti.

A quantitative genetic study of the ability of Aedes aegypti to propagate dengue-2 (DEN-2) virus in the midgut and in a disseminated infection in the head was conducted with a standard half-sib breeding design. Aedes aegypti aegypti and A. aegypti formosus differ markedly in oral susceptibility to DEN-2 virus.

Mitochondrial gene order is not conserved in arthropods: prostriate and metastriate tick mitochondrial genomes.

The entire mitochondrial genome was sequenced in a prostriate tick, Ixodes hexagonus, and a metastriate tick, Rhipicephalus sanguineus. Both genomes encode 22 tRNAs, 13 proteins, and two ribosomal RNAs. Prostriate ticks are basal members of Ixodidae and have the same gene order as Limulus polyphemus.

Molecular and genetic ecotoxicologic approaches to aquatic environmental bioreporting.

Molecular and population genetic ecotoxicologic approaches are being developed for the utilization of arthropods as bioreporters of heavy metal mixtures in the environment. The explosion of knowledge in molecular biology, molecular genetics, and biotechnology provides an unparalleled opportunity to use arthropods as bioreporter organisms. Interspecific differences in aquatic arthropod populations have been previously demonstrated in response to heavy metal insult in the Arkansas River (AR) California Gulch Superfund site (CGSS).

Breeding structure of three snow pool Aedes mosquito species in northern Colorado.

RAPD-PCR polymorphisms were used to examine breeding structure in three species of snow pool Aedes mosquitoes across three river drainages in northern Colorado. Larvae were collected from four snow pools for Aedes cataphylla Dyar, seven pools for A. hexodontus Dyar and six pools for A.

An estimate of phylogenetic relationships among culicine mosquitoes using a restriction map of the rDNA cistron.

Restriction maps of the rDNA cistron of twelve species of mosquitoes in six genera of the subfamily Culicinae were constructed using eight 6 bp recognition restriction enzymes. Anopheles albimanus was used as an outgroup. The size of the rDNA cistron ranged from 8.

Advances in radiology and the real versus apparent effects of early diagnosis.

Over the last two decades, technological advances in radiology have revolutionized the practice of medicine. Although the potential benefits of these advances are well recognized, the potential harms are not. This paper describes how early diagnosis can cause overestimations of disease prevalence and the effectiveness of intervention.

Taxonomic status of Ixodes neotomae and I. spinipalpis (Acari: Ixodidae) based on mitochondrial DNA evidence.

Ixodes spinipalpis Hadwen & Nuttall and I. neotomae Cooley are enzootic vectors of Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner in western North America. The taxa overlap in host preference, habitat, and morphology.

Linkage map for the Asian tiger mosquito [Aedes (Stegomyia) albopictus] based on SSCP analysis of RAPD markers.

A linkage map of the Asian tiger mosquito [Aedes (Stegomyia) albopictus (Skuse)] was constructed in an F1 intercross by monitoring the segregation of randomly amplified polymorphic DNA (RAPD) markers analyzed for single-strand conformation polymorphisms (SSCP). We hypothesized that SSCP analysis would reveal point mutations in RAPD fragments that would then segregate as codominant rather than dominant markers which are typically revealed through routine RAPD analysis. Markers were mapped to individual chromosomes by testing for cosegregation with Sex (chromosome I) or a polymorphism at the a-GPD allozyme locus (chromosome II).

The role of numeracy in understanding the benefit of screening mammography.

Background: Quantitative information about risks and benefits may be meaningful only to patients who have some facility with basic probability and numerical concepts, a construct called numeracy.

Objective: To assess the relation between numeracy and the ability to make use of typical risk reduction expressions about the benefit of screening mammography.

Design: Randomized, cross-sectional survey.

Using autopsy series to estimate the disease "reservoir" for ductal carcinoma in situ of the breast: how much more breast cancer can we find?

Purpose: To determine how many cases of breast cancer might be found if women not known to have the disease were thoroughly examined (the disease "reservoir").

Data Sources: MEDLINE search from 1966 to the present.

Study Selection: Hospital-based and forensic autopsy series examining women not known to have had breast cancer during life.

Rapid characterization of genetic diversity among twelve dengue-2 virus isolates by single-strand conformation polymorphism analysis.

Single-strand conformation polymorphism (SSCP) analysis was used to characterize genetic polymorphisms among 12 isolates of dengue-2 virus, which were previously genetically characterized by RNase T1 oligonucleotide mapping and by sequencing the viral envelope (E) gene. Specific cDNA fragments from the dengue-2 isolates were amplified by the reverse transcriptase-polymerase chain reaction. The viral E, premembrane (prM), and nonstructural 5 (NS5) gene cDNAs of 291 basepairs (bp), 291 bp, and 201 bp, respectively, were denatured, rapidly chilled to promote intrastrand reassociation, electrophoretically separated on nondenaturing polyacrylamide gels, and SSCP patterns were observed by silver staining.

Phylogeny of the grassland leafhopper genus Flexamia (Homoptera: Cicadellidae) based on mitochondrial DNA sequences.

Leafhoppers (Cicadellidae) are a highly diverse group of sap-sucking insects, many species of which specialize on grasses. Past attempts to examine the roles of host transfer or host plant coevolution in the diversification of leafhopper species using cladistic methods have been hindered by a paucity of discrete, phylogenetically informative morphological characters. To demonstrate the utility of DNA sequence data for species-level phylogenetic studies of Cicadellidae, we estimated phylogenetic relationships among species in the North American grassland leafhopper genus Flexamia DeLong using partial nucleotide sequences of mitochondrial 16S rDNA and NADH dehydrogenase 1, totaling 1496 base pairs and 810 potentially informative characters.

Culturing selects for specific genotypes of Borrelia burgdorferi in an enzootic cycle in Colorado.

In Colorado, Borrelia burgdorferi sensu stricto, the etiologic agent of Lyme disease, is maintained in an enzootic cycle between Ixodes spinipalpis ticks and Neotoma mexicana rats (27). The frequencies of flagellin (fla), 66-kDa protein (p66), and outer surface protein A (ospA) alleles were examined in 71 B. burgdorferi isolates from samples from Colorado.

Regional molecular genetic key of thirteen snow pool Aedes species (Diptera:Culicidae) in northern Colorado.

Snow pool Aedes mosquitoes are identified easily and accurately by microscopic examination of 4th instars or male genitalia. Early instars and females cannot be identified accurately. We demonstrate that restriction fragment-length polymorphisms (RFLP) in the internal transcribed spacer (ITS) of the nuclear ribosomal DNA cistron are specific to each of 13 snow pool Aedes species found in northern Colorado.

Accuracy of prenatal sonography for detecting circumvallate placenta.

Objective: We determined the accuracy of prenatal sonography for detecting placental circumvallation, a placental abnormality associated with increased fetal morbidity and mortality.

Materials And Methods: We analyzed 62 healthy pregnant (range, 18-36 weeks) patients with focused placental sonography for detection of morphologic abnormality using the published criteria for circumvallate placenta (irregular edge, uplifted margin, or placental sheet or shelf). Placental marginal sonograms were taken at 30 degrees intervals around the entire placental margin.

Phylogenetic relationships among tick subfamilies (Ixodida: Ixodidae: Argasidae) based on the 18S nuclear rDNA gene.

Phylogenetic relationships among tick subfamilies have been estimated using morphological and molecular characters. However, the phylogeny based on a portion of the 16S mitochondrial rDNA gene differed from the morphologically based phylogeny in a number of important respects. The entire 18S rDNA gene was examined in 18 taxa from all tick subfamilies to test the 16S rDNA based phylogeny.

Determining transition probabilities from mortality rates and autopsy findings.

The Markov process is a useful tool for modeling the natural history of disease, which is becoming increasingly important as new diagnostic tests increase the detectability of early-stage disease. The accuracy of a Markov model, however, depends on the accuracy of the estimates for the transition probabilities between different stages of disease. Because these estimates are usually based on "expert opinion" or small cohort studies, they are subject to imprecision and bias.

Screening for disease.

Screening for disease has become a major activity over the last few decades, and the potential for future growth is almost boundless. However, the necessity for and effectiveness of screening has often been overstated with misused survival statistics. Nevertheless, screening with certain radiologic tests may provide modest benefits at acceptable costs under certain conditions.