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Biomedical subjects

B R Miller

Publications and source records attributed to B R Miller.

At least 37 records · Page 2Linked to original sources
PubMed1999

Mosquito feeding modulates Th1 and Th2 cytokines in flavivirus susceptible mice: an effect mimicked by injection of sialokinins, but not demonstrated in flavivirus resistant mice.

Culex pipiens and Aedes aegypti mosquitoes were fed on C3H/HeJ mice and systemic cytokine production was quantified from stimulated lymphocytes harvested four to ten days after feeding. Mosquito feeding on C3H/HeJ mice significantly down regulated IFN gamma production seven to ten days post feeding by Cx. pipiens and seven days after Ae aegypti feeding. Th2 cytokines, IL-4 and IL-10, were significantly up regulated 4-7 days after Cx. pipiens and Ae. aegypti feeding. The immunosuppressive effect of Cx. pipiens feeding on systemic cytokine production was not evident in congenic flavivirus resistant (C3H/RV) mice, as systemic IFN gamma and IL-2 were significantly up regulated at days 7 and 10, correlating with a significant decrease in IL-4 10 days after feeding by Cx. pipiens mosquitoes. Inoculation of 5-1000 ng of sialokinin-I into C3H/HeJ mice mimicked the effect of Ae. aegypti feeding by down regulating Th1 cytokines and significantly up regulating Th2 cytokines four days post inoculation. Injections of sialokinin-II resulted in only moderate effects on IFN gamma and IL-4 production seven and ten days after injection. Thus natural feeding by two arbovirus vectors had a profound T cell modulatory effect in vivo in virus susceptible animals which was not demonstrated in the flavivirus resistant host. Moreover, sialokinin-I and sialokinin-II mimicked the effect of mosquito feeding by modulating the host T cell response. These results may lend new insight into specific aspects of the role of the mosquito vector in potentiating virus transmission in the mammalian host.

Aedes↗
PubMed1999

Isolation of thogoto virus (Orthomyxoviridae) from the banded mongoose, Mongos mungo (Herpestidae), in Uganda.

Small wild vertebrates were trapped during an investigation into possible vertebrate reservoirs of o'nyong-nyong (ONN) fever virus in Uganda in 1997. Antibody neutralization test results and virus isolation attempts were negative for ONN virus, confirming the work of earlier investigators, who also failed to find evidence for a nonhuman ONN virus reservoir. In the course of these ONN virus studies, Thogoto virus was isolated from one of eight banded mongooses (Mongos mungo). This is the first isolation of Thogoto virus from a wild vertebrate. Neutralizing antibodies to Thogoto virus were also found in two of the other mongooses.

Animals↗
PubMed1999

Epidemic O'Nyong-Nyong fever in southcentral Uganda, 1996-1997: entomologic studies in Bbaale village, Rakai District.

Entomologic studies were conducted between January 27 and February 2, 1997, in Bbaale village in southcentral Uganda during an o'nyong-nyong (ONN) virus epidemic, which began in mid 1996 and continued into 1997. The objectives were to confirm the role of anophelines in ONN virus transmission and to examine other mosquito species as epidemic vectors of ONN virus. Of 10,050 mosquitoes collected using light traps and pyrethrum knockdown sprays, Anopheles (Cellia) funestus Giles was presumed to be the principal vector because it was the most abundant mosquito species from which a strain of ONN virus was isolated. This virus was isolated for the first time from a culicine species, Mansonia (Mansonioides) uniformis Theobald. Bwamba virus and Nyando virus were also isolated from An. funestus.

Alphavirus↗
PubMed1998

Emergence of epidemic O'nyong-nyong fever in Uganda after a 35-year absence: genetic characterization of the virus.

O'nyong-nyong (ONN) virus is an alphavirus (family Togaviridae, genus Alphavirus) classified in the Semliki Forest virus (SFV) antigenic complex. ONN was initially isolated in northern Uganda in 1959 during the early stages of an explosive arbovirus epidemic in which > 2 million cases were reported. No additional epidemics or human isolations of ONN were reported until 1996, when it was isolated from an epidemic in southern Uganda. We report the complete nucleotide and deduced amino acid sequence of one of these 1996-1997 ONN isolates (SG650) and that of the related alphavirus Igbo Ora virus. The data indicate that the recent ONN virus isolate is closely related to the previously published ONN strain isolated in 1959. In addition, phylogenetic analysis of the sequence data reveals that Igbo Ora virus, previously thought to be a separate virus closely related to ONN and Chikungunya (CHIK), clearly is a strain of ONN. The sequence data also reveal that unlike the published ONN (1959) sequence, all ONN strains from the 1996-1997 epidemic possess a stop codon at the nsp3-nsp4 junction.

Adolescent↗
PubMed1997

Development of a polymerase chain reaction assay for differentiation between Culex pipiens pipiens and Cx. p. quinquefasciatus (Diptera: Culicidae) in North America based on genomic differences identified by subtractive hybridization.

Culex pipiens is a complex of mosquitoes that are involved in the transmission of pathogens, including St. Louis encephalitis virus in North America. The 2 major taxa in the complex, Cx. p. pipiens and Cx. p. quinquefasciatus, are nearly identical morphologically, making identification of field-collected specimens difficult, and attempts at differentiation based on biochemical and molecular techniques have been unsuccessful. We report here the use of genomic subtractive hybridization to identify a region of nucleic acid heterology between the genomes of Cx. p. pipiens and Cx. p. quinquefasciatus and the development of a polymerase chain reaction (PCR) assay to discriminate between them. PCR primers based on the nucleic acid sequence of a Cx. p. pipiens-unique DNA fragment were used to differentiate Cx. p. pipiens and Cx. p. pipiens/quinquefasciatus hybrids from Cx. p. quinquefasciatus by using extracted individual mosquito genomic DNA, crude DNA preparations from a mosquito head or legs, and DNA from triturated mosquito pools.

Animals↗
PubMed1997

Phylogenetic relationships of the Culicomorpha inferred from 18S and 5.8S ribosomal DNA sequences. (Diptera:Nematocera).

We investigated the evolutionary origins of the mosquito family Culicidae by examination of 18S and 5.8S ribosomal gene sequence divergence. Phylogenetic analyses demonstrated that within the infraorder Culicomorpha, taxa in the families Corethrellidae, Chaoboridae and Culicidae formed a monophyletic group; there was support for a sister relationship between this lineage and a representative of the Chironomidae. A chaoborid midge was the closest relative of the mosquitoes. Taxa from four genera of mosquitoes formed a monophyletic group; lack of a spacer in the 5.8S gene was unique to members of the Culicidae. A member of the genus Anopheles formed the most basal lineage among the mosquitoes analysed. Phylogenetic relationships were unresolved for representatives in the families Dixidae, Simuliidae and Ceratopogonidae.

Animals↗
PubMed1996

Population genetics with RAPD-PCR markers: the breeding structure of Aedes aegypti in Puerto Rico.

RAPD-PCR polymorphisms at 57 presumptive loci were used to examine the breeding structure of the mosquito Aedes aegypti in Puerto Rico. Mosquitoes were sampled from 16 locations in six cities and samples were located in a nested spatial design to examine local patterns of gene flow. Allele frequencies were estimated assuming (1) that genomic regions amplified by RAPD-PCR segregate as dominant alleles, (2) that genotypes at RAPD loci are in Hardy-Weinberg proportions, (3) identity in state (iis) among dominant amplified alleles and (4) iis among null alleles. The average genic heterozygosity was 0.354, more than twice the level detected in earlier allozyme surveys. Nested analysis of variance indicated extensive genetic differentiation among locations within cities. Effective migration rates (Nm) among cities were estimated from FST assuming an island model of migration. Estimates of Nm ranged from 9.7 to 12.2 indicating a high dispersal rate. The large number of polymorphisms revealed by RAPD-PCR allowed the distribution of FST and linkage disequilibrium to be examined among loci and demonstrated that small samples inflate FST and linkage disequilibrium. No linkage disequilibrium maintained through epistasis was detected among alleles at the 57 loci.

Aedes↗
PubMed1996

Phylogeny of fourteen Culex mosquito species, including the Culex pipiens complex, inferred from the internal transcribed spacers of ribosomal DNA.

Ribosomal DNA sequence divergence in the internal transcribed spacer regions (ITS-1 and ITS-2) was examined for fourteen species and four subgenera (sixty-two clones) in the mosquito genus Culex (Diptera: Culicidae). A neighbour-joining tree produced with Kimura 2-parameter distances showed that each of the four subgenera was monophyletic at confidence probabilities of 70-99%. Culex (Lutzia) formed the sister group of Cx. (Culex). Two major clades, a Cx. pipiens complex-Cx. torrentium assemblage and a Cx. restuans-Cx. salinarius-Cx. erythrothorax assemblage, formed monophyletic groups. Cx. torrentium was closely related to members of the Cx. pipiens complex. Phylogenetic analysis of ITS-1 and ITS-2 sequences from members of the Cx. pipiens complex separated populations from northern latitudes and southern latitudes, but did not support the traditional taxa as monophyletic units.

Animals↗
PubMed1995

Mitochondrial import of subunit Va of cytochrome c oxidase characterized with yeast mutants.

We have investigated the unusual import pathway of cytochrome c oxidase subunit Va (COXVa) into the yeast mitochondrial inner membrane by use of mutants that lack import receptors or are defective in matrix hsp70. (i) Mitochondria lacking the receptor MOM72 are not impaired in import of COXVa. Mitochondria lacking the main receptor MOM19 are moderately reduced in import of COXVa; this, however, is caused by a reduction of the inner membrane potential and not by a lack of specific receptor functions. (ii) Mitochondria defective in the unfoldase function of matrix hsp70 efficiently import COXVa, whereas mitochondria defective in the translocase function of the hsp70 are blocked in import of COXVA. A COXVa construct where the internal hydrophobic sorting signal is placed close to the presequence does not require either hsp70 function. These results demonstrate that import of COXVa does not require MOM19 or MOM72, but they unexpectedly reveal a strong dependence on the translocase function of matrix hsp70. Two important implications about the characterization of mitochondrial protein import in general are obtained. First, the interpretation of import results with mutants lacking MOM19 have to consider effects on the membrane potential. Second, the distance between a matrix targeting sequence and a hydrophobic sorting sequence within a precursor appears to determine if the inner membrane sorting machinery can substitute for the translocase function of hsp70 or not.

Biological Transport↗
PubMed1995

Nuclear pore complex assembly studied with a biochemical assay for annulate lamellae formation.

Formation of the nuclear pore is an intricate process involving membrane fusion and the ordered assembly of up to 1,000 pore proteins. As such, the study of pore assembly is not a simple one. Interestingly, annulate lamellae, a cytoplasmic organelle consisting of stacks of flattened membrane cisternae perforated by numerous pore complexes, have been found to form spontaneously in a reconstitution system derived from Xenopus egg extracts, as determined by electron microscopy (Dabauvalle et al., 1991). In this work, a biochemical assay for annulate lamellae (AL) formation was developed and used to study the mechanism of AL assembly in general and the assembly of individual nucleoporins into pore complexes in particular. Upon incubation of Xenopus egg cytosol and membrane vesicles, the nucleoporins nup58, nup60, nup97, nup153, and nup200 initially present in a disassembled form in the cytosol became associated with membranes and were pelletable. The association was time and temperature dependent and could be measured by immunoblotting. Thin-section electron microscopy as well as negative staining confirmed that annulate lamellae were forming coincident with the incorporation of pore proteins into membranes. Homogenization and subsequent flotation of the membrane fraction allowed us to separate a population of dense membranes, containing the integral membrane pore protein gp210 and all other nucleoporins tested, from the bulk of cellular membranes. Electron microscopy indicated that annulate lamellae were enriched in this dense, pore protein-containing fraction. GTP gamma S prevented incorporation of the soluble pore proteins into membranes. To address whether AL form in the absence of N-acetylglucosaminylated pore proteins, AL assembly was carried out in WGA-sepharose-depleted cytosol. Under these conditions, annulate lamellae formed but were altered in appearance. When the membrane fraction containing this altered AL was homogenized and subjected to flotation, the pore protein-containing membranes still sedimented in a distinct peak but were less dense than control annulate lamellae.

Animals↗
PubMed1995

Development of a species-diagnostic polymerase chain reaction assay for the identification of Culex vectors of St. Louis encephalitis virus based on interspecies sequence variation in ribosomal DNA spacers.

Culex pipiens complex mosquitoes (Cx. p. pipiens and Cx. p. quinquefasciatus) are among the principal vectors of St. Louis encephalitis (SLE) virus in the eastern United States; Cx. restuans and Cx. salinarius play secondary roles in the transmission and maintenance of the virus cycle. Accurate identification of these three species in field collections is required for epidemiologic studies of SLE virus transmission. We have developed a polymerase chain reaction (PCR) assay for this purpose. Species-specific PCR primers were designed based on interspecies nucleic acid sequence variation in the first and second internal transcribed spacers (ITS1 and ITS2) of the nuclear ribosomal DNA gene array; however, insufficient variation was detected to differentiate between subspecies of the Cx. pipiens complex. The primers were used together in a single amplification reaction to correctly identify specimens to species using genomic DNA extracted from whole individual mosquitoes, DNA from triturated mosquito pools, or crude DNA from mosquito heads or legs.

Animals↗
PubMed1995

Subgingival bacteria--comparison of culture results in dogs and cats with gingivitis.

Aerobic and anaerobic subgingival bacteria were cultured and identified from 49 dogs and 40 cats with spontaneous gingivitis. The most common organisms were gram-negative anaerobes (37% of canine isolates and 39% of feline isolates) and gram-positive aerobes (36% of canine isolates and 29% of feline isolates). No major differences were found between the subgingival floras of dogs and cats with gingivitis.

Animals↗
PubMed1995

Antimicrobial susceptibility of subgingival bacterial flora in dogs with gingivitis.

The aerobic and anaerobic flora from gingival pockets of 49 dogs with severe gingivitis and periodontitis were cultured. The susceptibility of each isolate to four antimicrobial agents currently approved for veterinary use in the USA (amoxicillin-clavulanic acid; clindamycin; cefadroxil; and enrofloxacin) was determined. Amoxicillin-clavulanic acid (Clavamox Pfizer Animal Health) had the highest in-vitro susceptibility against all isolates (96%), all aerobes (94%) and all anaerobes (100%) tested. For gram-negative aerobes, enrofloxacin (Baytril, Bayer Corp.) had the highest in-vitro susceptibility activity. For bacteria associated with treatment of gingivitis, which typically are mixed aerobic/anaerobic and gram-positive/gram-negative organisms, the antimicrobial of choice for clinical use based on these susceptibility tests is amoxicillin-clavulanic acid.

Amoxicillin-Potassium Clavulanate Combination↗
PubMed1995

Antimicrobial susceptibility of subgingival bacterial flora in cats with gingivitis.

The aerobic and anaerobic flora from gingival pockets of 40 cats with established gingivitis were cultured. The susceptibility of each isolate to four antimicrobial agents currently approved for use in cats (amoxicillin-clavulanic acid; clindamycin; cefadroxil; enrofloxacin) was determined. Amoxicillin-clavulanic acid (Clavamox) had the highest in-vitro susceptibility against all isolates (92%) and all anaerobes (99% [co-equal with clindamycin]) tested; enrofloxacin (Baytril) had the highest in-vitro susceptibility against all aerobes (90%) tested.

Amoxicillin-Potassium Clavulanate Combination↗
PubMed1994

Analysis of a yellow fever virus isolated from a fatal case of vaccine-associated human encephalitis.

The virulence of a yellow fever (YF) virus (P-16065) isolated from a fatal case of vaccine-associated viral encephalitis was investigated. P-16065 appeared identical to its parent vaccine virus (17D-204 USA, lot 6145) when examined with monoclonal antibodies except that YF wild type-specific MAb S24 recognized P-16065 but not 17D-204 USA 6145. Thus, a mutation of at least one epitope on the envelope (E) protein had occurred. Unlike 17D-204 USA 6145 and other 17D vaccine viruses, P-16065 was neuroinvasive and virulent for mice after intranasal inoculation, and neurovirulent for monkeys after intracerebral inoculation. The E protein of P-16065 differed from 17D-204 USA by two amino acids at positions 155 and 303. Changes at amino acid position 155 are found in other YF vaccine viruses that are not neurovirulent, and it is therefore postulated that the change at position 303 is involved in the alteration of the phenotype of P-16065 and may be important for virulence of YF virus.

Aedes↗
PubMed1994

Use of randomly amplified polymorphic DNA amplified by polymerase chain reaction markers to estimate the number of Aedes aegypti families at oviposition sites in San Juan, Puerto Rico.

We report the application of a molecular genetic technique to estimate the number of full-sibling families of Aedes aegypti contained in oviposition traps. Randomly amplified polymorphic DNA amplified by the polymerase chain reaction markers were used to estimate the numbers and sizes of families in traps at field locations in San Juan, Puerto Rico. Forty-nine presumptive loci were amplified with five primers in a total of 813 individuals from 26 sites. The average family size was 10.95, but the size distribution was skewed with an excess of small families containing 1-2 individuals. The number of families increased with the number of eggs in traps; however, the average family size decreased as the number of eggs increased. This suggests that females oviposited only a few eggs in traps that were recently placed in the field and lacked mosquito eggs or fewer eggs were oviposited as traps became crowded.

Aedes↗
PubMed1994

Effectiveness of SofScale Calculus Scaling Gel as an aid during dental scaling of teeth of dogs.

The effect of pre-scaling application of SofScale Calculus Scaling Gel was studied on teeth of cadaver dogs, comparing scaling time and effort among pre-treated and untreated pairs of teeth. Teeth with light, moderate and heavy calculus were studied, treated by either hand-scaling only or hand and ultrasonic scaling. No significant difference was found in overall mean time required, comparing SofScale treated and untreated teeth. Scaling time was faster for SofScale treated teeth with light calculus, and slower for SofScale treated teeth with heavy calculus. There were no differences observed in the effort required for scaling, comparing SofScale treated and untreated teeth.

Analysis of Variance↗