PubMed Health⌕ Search

Biomedical subjects

R D Ward

Publications and source records attributed to R D Ward.

At least 19 recordsLinked to original sources
PubMed1997

Phlebotomine sandflies in a focus of visceral leishmaniasis in a border area of eastern Sudan.

A field study was carried out in eastern Sudan, near the Ethiopian border, to investigate the abundance, seasonality, man-biting behaviour and resting sites of sandflies in two areas where visceral leishmaniasis (kala-azar) is endemic: Umsalala village, Galabat Province; and the adjacent Dinder National Park (DNP), Dinder Province. Abundance of the different species was determined from collections made, using light and sticky-paper traps, in various habitats between November 1993 and February 1995. Man-biting sandflies were collected as they landed on human bait. The habitats investigated for day-resting sandflies were thatched huts, chicken coops, tree-holes, termite mounds and soil cracks. Animal burrows were not investigated. The species found were Phlebotomus (Larroussius) orientalis, P. (Phlebotomus) papatasi, P. (Paraphlebotomus) saevus, P. (Anaphlebotomus) rodhaini, Sergentomyia (Sintonius) clydei, S. (Sergentomyia) antennata, S. (Sergentomyia) sckwetzi, S. (Parrotomyia) africana and S. (Grassomyia) squamipleuris. Phlebotomus orientalis was the only man-biting sandfly species found in the DNP whereas P. papatasi, P. orientalis and P. saevus were all found in Umsalala. Abundance of each species varied with the habitat. In Umsalala and a camp for game wardens in the DNP, Sergentomyia spp. predominated over Phlebotomus. In the DNP, the most abundant sandfly in a thicket dominated by Acacia seyal trees was P. orientalis, followed by Sergentomyia spp. Significant habitat 'preferences' were observed for most sandfly species in the area. In attempts to find resting flies, P. orientalis was only found resting in the mounds made by the termite Macrotermes herus and P. papatasi was only found inside huts; no resting sites were detected for other Phlebotomus spp. but Sergentomyia spp. were observed in all the sites investigated. The P. orientalis in the DNP showed a clear seasonal variation in abundance, which was closely correlated with the mean monthly temperature and relative humidity of the area. A remarkable increase in the abundance of this vector occurred at the beginning of the rainy season.

Animals↗
PubMed1997

IMGs set goals for AMA section.

International medical graduates have become an important part of the American health care structure in recent decades, but too often they remain second-class citizens within the medical community. Increasingly, voices within medicine have called for formal recognition of the unique needs of IMG physicians.

American Medical Association↗
PubMed1996

Comparison of the sex-pheromone components of Lutzomyia longipalpis (Diptera:Psychodidae) from areas of visceral and atypical cutaneous leishmaniasis in Honduras and Cost Rica.

The terpene components of extracts prepared from male Lutzomyia longipalpis (Diptera: Psychodidae) collected from four sites in Honduras and one in Costa Rica were analysed by high-performance liquid chromatography, gas chromatography and coupled gas chromatography--mass spectrometry. The terpene components of Lu. longipalpis from other regions of South America have previously been shown to be sex pheromones. The flies from the four areas of Honduras, where Leishmania chagasi infection may lead to visceral or atypical cutaneous leishmaniasis, were found to be homogenous, all producing 9-methylgermacrene-B. Three types of terpene (9-methylgermacrene-B, a novel homosesquiterpene and a small amount of diterpene) were detected in pools of flies from Liberia, Costa Rica, where only atypical cutaneous leishmaniasis has been found. These results indicate that there are probably at least two and possibly three distinct populations of Lu. longipalpis in this region. The clinical manifestation of Leishmania chagasi infection does not appear to be dependent on which population of Lu. longipalpis transmitted the parasite.

Animals↗
PubMed1996

James P. Gallagher, MD. Scrappy former boxer fights to maintain physicians' voices.

It's been an adventurous life for James Gallagher, MD, from medical school in Ireland where he was a scrappy welterweight student boxer to one of the state's foremost cardiologists, and current president of the Wayne County Medical Society. Born in County Tyrone, Northern Ireland in 1932, the fifth in an ultimate full house of nine children, Doctor Gallagher attended medical school at the National University of Dublin.

Boxing↗
PubMed1995

A mutation in glyceraldehyde 3-phosphate dehydrogenase alters endocytosis in CHO cells.

The CHO cell mutant FD 1.3.25 exhibits both increased accumulation and altered distribution of endocytosed fluid phase tracers. Neither the rate of tracer internalization nor the kinetics of recycling from early endosomes was affected, but exocytosis from late endocytic compartments appeared to be decreased in the mutant. Endocytosed tracer moved more rapidly to the cell poles in FD1.3.25 than in wild type cells. An abundant 36-kD polypeptide was found associated with taxol-polymerized microtubules in preparations from wild type and mutant; in the former but not the latter this polypeptide could be dissociated by incubation of the microtubules in ATP or high salt. The 36-kD polypeptide co-electrophoresed in two dimensions with the monomer of the glycolytic enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Analysis of cDNA clones showed that the mutant is heterozygous for this enzyme, with approximately 25% of the GAPDH RNA containing a single nucleotide change resulting in substitution of Ser for Pro234, a residue that is conserved throughout evolution. Stable transfectants of wild type cells expressing the mutant monomer at approximately 15% of the total enzyme exhibited the various changes in endocytosis observed in FD1.3.25.

Animals↗
PubMed1995

Sugar meal sources for the phlebotomine sandfly Lutzomyia longipalpis in Ceará State, Brazil.

In the Brazilian village of Boqueirão do Renato Parente, Ceará State, where visceral leishmaniasis is endemic, significant variation in the abundance of phlebotomine sandflies between different types of vegetation was demonstrated by castor oil sticky trap collections. Population densities of Lutzomyia longipalpis (Lutz & Neiva) sandflies were higher in beans and maize crops than in the surrounding open and tree scrub. Significant relationships were detected between the abundances of sandflies and aphids, suggesting aphid honeydew as a potential food source. Sugar meal analysis, using high-performance anion exchange (HPAE) chromatography with pulsed amperometric detection (PAD) and the cold anthrone test, was used to demonstrate that significantly more sandflies fed on bean plants contaminated with aphids and honeydew than on uncontaminated beans. Furthermore, higher concentrations of sugars were detected in flies which fed on aphid/honeydew-contaminated beans, suggesting that sugar was more easily available and/or that honeydew/aphids act as phagostimulants for sandflies. Amongst wild sandflies collected from a bean field, significantly more female sandflies were 'sugar-positive' than males, though the sugar concentrations in positive sandflies were similar for both sexes. The concentrations of di- and trisaccharides in sandfly homogenates, honeydew extracts and phloem exudates were very low.

Animals↗
PubMed1995

Molecular techniques in the characterization of Leishmania isolates from Central America.

The public-health problems caused by leishmaniasis in most countries in Central America are becoming more severe. This is partly because of the increasing size of the human populations that are at risk and their migratory patterns. Annual incidence of the disease in Costa Rica, Honduras, Guatemala, Panama and Nicaragua is estimated to be as high as 20,000 cases. Regional changes in the epidemiology of the various Leishmania spp. present have emphasized the need for innovative, sensitive and accurate diagnostic tools. PCR and isoenzyme, monoclonal antibody, schizodeme, DNA-probe and random-amplified, polymorphic DNA analyses have been tested. Preliminary indications that Leishmania chagasi was present in Costa Rica and Honduras and that interspecific hybrids occurred in Nicaragua have been confirmed using these methods. The distribution of the mexicana complex was also found to be broader and more heterogeneous than initially expected. Overall, there was 87% concordance between the results produced using the different techniques.

Animals↗
PubMed1994

Development of Leishmania chagasi (Kinetoplastida: Trypanosomatidae) in the second blood-meal of its vector Lutzomyia longipalpis (Diptera: Psychodidae).

Light and electron microscopy investigations were carried out to compare the development of Leishmania chagasi in Lutzomyia longipalpis females that took a second blood-meal and others that took a single blood-meal. The establishment of the parasite in the foregut and the thoracic midgut of the vector was not severely affected by the intake of the second blood-meal. At 3 days after the intake of the second blood-meal, a rapid increase in the proportion of metacyclic promastigotes detected in the midgut and proboscis of the vector was noticed. No similar increase in the proportion of metacyclic promastigotes observed in the females that took a single blood-meal was noticeable. The results indicate a higher probability of transmission of the parasite to the vertebrate host at the third bite of the vector than at the second bite.

Animals↗
PubMed1994

A unique expression pattern for a sperm membrane protein during sea urchin spermatogenesis.

Specific mRNAs coding for a 63 kDa sperm membrane protein (63-SMP) were localised in Strongylocentrotus purpuratus testis sections using in situ hybridisation techniques. 35S-labelled antisense RNA probes transcribed from a 766 base pair fragment of the gene coding for the 63-SMP hybridised to all spermatogenic cells in the basal germinal epithelia of testicular acini, except the most peripherally located (least differentiated) spermatogonia. No hybridisation to the luminally located mature spermatozoa or somatic cells of the testis was observed. Using monoclonal antibody J17/30 and indirect immunofluorescence techniques, the 63-SMP was localised to the same subset of spermatogenic cells that contain the 63-SMP mRNA, suggesting that expression of this gene is transcriptionally controlled. In combination with previous studies on the expression of sperm histones and sperm binding, these results show that multiple, perhaps sequential, classes of gene activity contribute to the differentiation of sea urchin sperm.

Animals↗
PubMed1994

Chemical analysis of a putative sex pheromone from Lutzomyia pessoai (Diptera: Psychodidae).

Lutzomyia pessoai has been named as a probable vector of Leishmania braziliensis in southern Brazil. Males of this species have recently been shown to have pheromone-disseminating structures on their abdomen. Chemical analysis of extracts from the glands associated with these structures has revealed the presence of a possible sex pheromone. Although this compound has been partially characterized as a monocyclic diterpene with the same molecular weight as the Lu. longipalpis diterpene sex pheromone, mass spectral evidence indicates that it is different compound. This, the first evidence for a possible sex pheromone in any phlebotomine species other than Lu. longipalpis, indicates that such semiochemicals may be widely distributed in this group.

Animals↗
PubMed1994

Response of adult sandflies, Lutzomyia longipalpis (Diptera: Psychodidae), to sticky traps baited with host odour and tested in the laboratory.

The responses of adult Lutzomyia longipalpis Lutz and Neiva to sticky traps baited with entrained volatiles from a hamster were assessed in the laboratory. In a two-choice test, significantly more females and males were caught on odour-baited sticky traps than on control traps, and only a few adults remained alive and untrapped at the end of the experiments. In contrast, significantly fewer flies of both sexes were caught in a series of tests where both traps were unbaited. Twice as many males as females were caught in the control traps in the tests with odour, an observation in accordance with known male lekking behaviour around hosts. The results show that sandflies of both sexes are attracted to traps by host odour alone, in the absence of any other host cues or pheromones from the male flies.

Animals↗
PubMed1994

A study of phlebotomine sandflies (Diptera:Psychodidae) in Yunnan Province. V. Phlebotomus (Larroussius) lengi sp. nov.

A new species of the subgenus Larroussius Nitzulescu 1931, named Phlebotomus lengi in honour of the Chinese sandfly taxonomist Professor Yan Jia Leng, was found amongst the phlebotomine sandflies collected in Yunnan Province, China, in 1989. A full description of the male and female of this species is provided. The ascoid formula of P. lengi distinguishes it from all previously described members of the subgenus Larroussius.

Animals↗
PubMed1994

Isolation of oviposition pheromone from the eggs of the sandfly Lutzomyia longipalpis.

Semiochemical components of eggs of the sandfly Lutzomyia longipalpis (Diptera: Psychodidae) were separated by high performance liquid chromatography. HPLC fractions were examined quantitatively and qualitatively by gas chromatography (GC). A bioassay was used to determine the oviposition attraction of gravid L. longipalpis to each of the fractions separately and a peak responsible for the semiochemical activity was identified. Gravid flies were placed in individual oviposition tubes to determine if the peak of interest was an oviposition stimulant. The active semiochemical fraction attracted gravid flies for oviposition. Furthermore, egg laying was enhanced: gravid flies exposed to the pheromone oviposited earlier and laid more eggs than control flies. GC analysis indicated that 1200 eggs (2 days old) gave a yield of 12.75 micrograms of active pheromone. This fraction had similar HPLC and GC retention times to caryophyllene oxide, suggesting comparable polarity and molecular weight.

Animals↗