Biomedical subjects

J E Foster

Publications and source records attributed to J E Foster.

At least 19 recordsLinked to original sources

PubMed2006

NT-proBNP can be used to detect right ventricular systolic dysfunction in pulmonary hypertension.

Right ventricular systolic dysfunction (RVSD) at baseline (pre-treatment) predicts early death in patients with pulmonary hypertension (PH). However, RVSD can only be detected reliably by prohibitively invasive or expensive techniques. N-terminal B-type natriuretic peptide concentration ([NT-proBNP]) correlates with RV function in PH; however, an [NT-proBNP] threshold that indicates RVSD in individual patients has not previously been determined. Twenty-five patients with PH (pulmonary arterial hypertension (n = 19) or chronic thromboembolic PH (n = 6)) underwent cardiovascular magnetic resonance (CMR) imaging and NT-proBNP measurement at baseline. [NT-proBNP] was correlated against RV dimensions and ejection fraction (RVEF) measured directly by CMR imaging. The ability of NT-proBNP to detect RVSD (defined as a CMR-derived RVEF >2 SDS below control values) was tested and predictors of [NT-proBNP] identified. [NT-proBNP] correlated negatively with RVEF. RVSD was present in nine out of 25 patients. An [NT-proBNP] threshold of 1,685 pg.mL(-1) was sensitive (100%) and specific (94%) in detecting RVSD. RVEF and RV mass index independently predicted [NT-proBNP]. In pulmonary hypertension, a baseline N-terminal B-type natriuretic peptide concentration of >1,685 ng.L(-1) suggests right ventricular systolic dysfunction, and thus an increased risk of early death. N-terminal B-type natriuretic peptide could prove useful as an objective, noninvasive means of identifying patients with pulmonary hypertension who have right ventricular systolic dysfunction at presentation.

Aged↗

PubMed2006

Vascular function in patients with end-stage renal disease and/or coronary artery disease: a cardiac magnetic resonance imaging study.

Decreased arterial compliance in end-stage renal disease (ESRD) is associated with increased cardiovascular risk. Our aim was to examine aortic compliance in patients with ESRD using cardiac magnetic resonance imaging (MRI) and to compare these with patients with advanced atherosclerotic disease who are known to be at high cardiovascular risk. We examined a total of 83 subjects matched for age: 24 had ESRD and were on dialysis therapy for 3+/-6 years, 24 had severe coronary artery disease (CAD), 11 had both ESRD and CAD (4+/-5 years on dialysis therapy), and 24 healthy subjects with no evidence of CAD. Vascular and cardiac function was assessed using cardiac MRI. Aortic compliance was significantly reduced in patients with CAD compared to control subjects (11.3+/-6.3 ml x 10(-3)/mm Hg vs 15.6+/-6.0 ml x 10(-3)/mm Hg, P=0.009). Patients with ESRD also exhibited significantly reduced aortic compliance compared to healthy controls (12.4+/-5.8 ml x 10(-3)/mm Hg vs 15.6+/-6.0 ml 10(-3)/mm Hg, P=0.012), whereas there was no significant difference in aortic compliance between patients with CAD and ESRD. Even in the absence of symptomatic CAD, patients with ESRD have significantly reduced aortic compliance compared to normal subjects. Patients with ESRD have equivalent aortic compliance to patients with advanced CAD. These findings suggest that a significantly reduced aortic compliance is one of many mechanisms promoting premature cardiovascular events in patients with ESRD compared to age-matched controls from the general population.

Aged↗

PubMed2006

Redefinition of uremic cardiomyopathy by contrast-enhanced cardiac magnetic resonance imaging.

Patients with end stage renal failure (ESRF) have an increased risk of premature cardiovascular disease. Left ventricular (LV) abnormalities, so called 'uremic cardiomyopathy', are associated with poorer outcome. Cardiac magnetic resonance imaging (CMR) accurately defines LV dimensions and identifies underlying myocardial pathology. We studied the relationship between LV function and myocardial pathology in ESRF patients with CMR. A total of 134 patients with ESRF underwent CMR. LV function was assessed with further images acquired after gadolinium-diethylentriaminepentaacetic acid (DTPA). The presence of myocardial fibrosis was indicated by late gadolinium enhancement (LGE). Two main myocardial pathologies were identified. A total of 19 patients (14.2%) displayed 'subendocardial LGE' representing myocardial infarction, which was associated with conventional cardiovascular risk factors including a history of ischemic heart disease (IHD) (P < 0.001), hypercholesterolemia (P < 0.05), and diabetes (P < 0.01). Patients with subendocardial LGE had greater LV mass (P < 0.05), LV dilation (P < 0.01), and LV systolic dysfunction (P < 0.001) compared to patients with no evidence of LGE. The second pattern, 'diffuse LGE', seen in 19 patients (14.2%) appeared to represent regional areas of diffuse myocardial fibrosis. Diffuse LGE was associated with greater LV mass compared to patients without LGE (P < 0.01) but not systolic dysfunction. In total, 28.4% of all patients exhibited evidence of myocardial fibrosis demonstrated by LGE. In contrast to published literature describing three forms of uremic cardiomyopathy - left ventricular hypertrophy (LVH), dilation, and systolic dysfunction, we have shown that LVH is the predominant cardiomyopathy specific to uremia, while LV dilation and systolic dysfunction are due to underlying (possibly silent) ischemic heart disease.

Adult↗

PubMed2005

Susceptibility of biological stages of the horn fly, Haematobia irritans, to entomopathogenic fungi (Hyphomycetes).

The susceptibility of the egg, pupa, and adult of Haematobia irritans (L.) (Diptera: Muscidae) to isolates of the fungi Metarhizium anisopliae (Metsch.) Sor., Beauveria bassiana (Bals.) Vuill., and Paecilomyces fumosoroseus (Wize) Brown and Smith, was evaluated under laboratory conditions. Groups of 20 eggs than 4 h old, pupae less than 48h old and adults were sprayed with a conidial suspension of each isolate. Eggs, pupae and adults of horn fly were susceptible to these entomopathogenic fungi. For treated eggs, the isolates Ma3, Ma 15, Ma25, Pfr1, and Pfr8 reduced adult emergence to 3.8% to 6.3% in comparison with the control (72%). The mortality of pupae infected by the isolates Ma2, Ma25, and Pfr10 ranged between 50% and 71.3%. Mortality of adults after treatment with the isolates Ma6, Ma 10, Ma 14, Ma 15, Pfr 1, Pfr 9, Pfr 10, Pfr 11, and Pfr12 were higher than 90%. The isolate Ma6 produced the lowest LC(50) against adult horn flies (8.08 &times 10(2)conidia/ml). These findings supported the hypotheses that isolates of M. anisopliae, and P. fumosoroseus are pathogenic against the different biological stages of horn flies by reducing adult emergence when applied on groups of eggs and pupae, and producing mortality when applied to adults.

Animals↗

PubMed2002

Random amplified polymorphic DNA markers for discriminating Cochliomyia hominivorax from C. macellaria (Diptera: Calliphoridae).

The screwworm, Cochliomyia hominivorax (Coquerel), is one of the most important pests of livestock in the Western Hemisphere. During early immature stages it is morphologically very similar (first instars are virtually indistinguishable) to the secondary screwworm, C. macellaria (Fabricius). Here, the utility of the random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) was explored as a technique for developing molecular genetic markers for these two species. Of the 120 arbitrary primers screened, 21 primers produced markers that were further investigated. Seven of the 21 primers produced clear and reproducible markers that were tested with DNA of five individuals from four populations of each species; five of these primers showed 12 RAPD markers that differentiated the species in all populations. Analyses of data from these seven primers also suggested that intraspecific polymorphisms exist that could be useful in distinguishing populations of screwworms. Some population genetic tools, such as genetic distance, cluster analysis and bootstrapping, were used to statistically explore these polymorphisms. The resulting statistics showed 100% support for the ability of RAPD-PCR to discriminate between the two species. Bootstrapping with data from one of the genetic distance calculations produced a tree with all individual screwworms in the correct populations, indicating that RAPD-PCR has promise for displaying intraspecific genetic variation that could be used in establishing the general geographic origin of screwworm samples.

Animals↗

PubMed2001

Identification of screwworms, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae), with a monoclonal antibody-based enzyme-linked immunosorbent assay (MAb-ELISA).

Myiasis caused by screwworms, Cochliomyia hominivorax (Coquerel), is devastating to warm-blooded animals and economically important to livestock producers. It is difficult to distinguish these pests, immature screwworms, from immatures of other non-pest fly species that often occur in animal wounds; it would be helpful to have tools available that do not rely on morphological characteristics. We developed two monoclonal antibodies (MAbs), highly specific for the screwworm, and used them in an enzyme-linked immunosorbent assay (MAb-ELISA), that differentiated screwworm eggs, larvae, pupae, and adults from those of the closely related secondary screwworm, C. macellaria (Fabricius) as well as Phormia regina (Meigen), Phaenicia sericata (Meigen), Calliphora vicina Robineau-Desvoidy, and Chrysomya rufifacies (Macquart). In a blind study, the microplate MAb-ELISA, which took about 4h to complete, displayed high specificity (99%), sensitivity (92%) and overall accuracy (97%) in distinguishing all life stages of the screwworm. Electrophoresis results suggested that the two monoclonal antibodies recognized identical conformational epitopes present in all screwworm life stages. The screwworm eradication program, successful in eradicating this pest from the US, Mexico, most of Central America and Libya (after an accidental introduction), could benefit in future eradication, surveillance, and exclusion efforts by developing a reliable field identification kit based on MAb-ELISA that accurately and quickly distinguished cases of screwworm myiasis.

Animals↗

PubMed2001

Corn pollen deposition on milkweeds in and near cornfields.

The density of corn pollen on leaves of milkweed plants inside and outside of cornfields was measured in several studies from different localities. The purpose was to obtain a representative picture of naturally occurring pollen densities to provide a perspective for laboratory and field studies of monarch larvae feeding on milkweed leaves with Bt corn pollen. Pollen density was highest (average 170.6 grains per cm(2)) inside the cornfield and was progressively lower from the field edge outward, falling to 14.2 grains per cm(2) at 2 m. Inside the cornfield, and for each distance from the field edge, a frequency distribution is presented showing the proportion of leaf samples with different pollen densities. Inside cornfields, 95% of leaf samples had pollen densities below 600 grains per cm(2) and the highest pollen density observed was 1400 grains per cm(2), which occurred in a study with a rainless anthesis period. All other studies had rainfall events during the anthesis period. A single rain event can remove 54-86% of the pollen on leaves. Leaves on the upper portion of milkweed plants, where young monarch larvae tend to feed, had only 30-50% of the pollen density levels of middle leaves.

Animals↗

PubMed2001

Allosteric binding of nucleoside triphosphates to RNA polymerase regulates transcription elongation.

The regulation of transcription elongation and termination appears to be governed by the ability of RNA polymerase elongation complexes to adopt multiple conformational states; however, the factors controlling the distribution between these states remain elusive. We used transient-state kinetics to investigate the incorporation of single nucleotides. We demonstrate that E. coli RNA polymerase contains an allosteric binding site in addition to the catalytic site. Binding of the templated nucleoside triphosphate (NTP), but not nontemplated NTPs, to this site increases the rate of nucleotide incorporation. The data suggest that RNA polymerase can exist in a state that catalyzes synthesis slowly (unactivated) and one that catalyzes synthesis rapidly (activated), with the transition from the slow to the fast state being induced by binding of the templated NTP to the allosteric site.

Adenosine Monophosphate↗

PubMed2001

Cross-resistance and resistance longevity as induced by bean leaf beetle, Cerotoma trifurcata and soybean looper, Pseudoplusia includens herbivory on soybean.

Cross-resistance, and longevity of resistance, induced by the bean leaf beetle, Cerotoma trifurcata, was studied IN the soybean PI 227687 that exhibited induced response in earlier studies. Bean leaf beetle adults and soybean looper, Pseudoplusia includens, larvae were used to induce resistance and to determine beetle feeding preference. Beetles were collected from soybean fields 2 to 5 days prior to the feeding preference test. The level of cross-resistance induced by soybean looper herbivory to subsequent bean leaf beetle feeding was higher when compared to cross-resistance induced by bean leaf beetle herbivory against subsequent feeding by soybean looper. Further, herbivory by the bean leaf beetle also induced resistance against soybean looper feeding. In the longevity study, leaflets from treated plants were collected 5, 10, 12, 14, 16, 20 and 25 days after initiation of feeding. Pairwise comparisons of leaflets from plants treated by bean leaf beetle herbivory with untreated plants revealed that induced responses were highest 14 and lowest 25 days after initiation of feeding. On other sampling days, levels of induced response varied with the sampling day.

Animals↗

PubMed2001

Molecular phylogeny of Diabrotica beetles (Coleoptera: Chrysomelidae) inferred from analysis of combined mitochondrial and nuclear DNA sequences.

The phylogenetic relationships of thirteen Diabrotica (representing virgifera and fucata species groups) and two outgroup Acalymma beetle species (Coleoptera: Chrysomelidae) were inferred from the phylogenetic analysis of a combined data set of 1323 bp of mitochondrial DNA (mtDNA) cytochrome oxidase subunit 1 (COI) and the entire second internal transcribed spacer region (ITS-2) of nuclear ribosomal DNA of 362 characters. Species investigated were D. adelpha, D. balteata, D. barberi, D. cristata, D. lemniscata, D. longicornis, D. porracea, D. speciosa, D. undecimpunctata howardi, D. u. undecimpunctata, D. virgifera virgifera, D. v. zeae, D. viridula, and outgroup A. blandulum and A. vittatum. Maximum parsimony (MP), minimum evolution (ME), and maximum likelihood (ML) analyses of combined COI and ITS-2 sequences clearly place species into their traditional morphological species groups with MP and ME analyses resulting in identical topologies. Results generally confer with a prior work based on allozyme data, but within the virgifera species group, D. barberi and D. longicornis strongly resolve as sister taxa as well as monophyletic with the neotropical species, D. viridula, D. cristata and D. lemniscata also resolve as sister taxa. Both relationships are not in congruence with the prior allozyme-based hypothesis. Within the fucata species group, D. speciosa and D. balteata resolve as sister taxa. Results also strongly supported the D. virgifera and D. undecimpunctata subspecies complexes. Our proposed phylogeny provides some insight into current hypotheses regarding distribution status and evolution of various life history traits for Diabrotica.

Animals↗

PubMed2001

PCR-RFLP of the mitochondrial cytochrome oxidase (subunit I) gene provides diagnostic markers for selected Diabrotica species (Coleoptera: Chrysomelidae).

Adult and larval identification of Diabrotica can be difficult. Some adult identifications require considerable taxonomic experience while larvae of many Diabrotica species are morphologically indistinguishable. This study was conducted to determine whether 12 pest and non-pest Diabrotica species could be separated using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). A 1308 bp portion of the mitochondrial cytochrome oxidase subunit I gene (COI) was amplified using PCR and digested using several restriction endonucleases. Double digests of COI amplicons with AluI and MspI resolved on polyacrylamide gels revealed several diagnostic inter- and intraspecific polymorphisms. A key to the 12 species was constructed using the PCR-RFLP patterns.

Animals↗

PubMed2000

Diurnal variation in the femoral articular cartilage of the knee in young adult humans.

Our objective was to test the hypothesis that diurnal changes occur in thickness or volume of the femoral articular cartilage of the knee in asymptomatic young adults. Fat-suppressed three-dimensional (3D) spoiled gradient-echo magnetic resonance imaging (MRI) was employed. Six volunteers each were scanned early in the morning and at the end of a working day spent mainly standing. This protocol was repeated on 3 successive weeks. Femoral cartilage volumes were obtained via semiautomatic segmentation that employed a seeding algorithm. These segmentations then were regridded onto a 500-pixel template, and differences in the resulting thickness maps were assessed. Analysis of variance showed no significant diurnal variation in overall volume or thickness. The reproducibility for volume (test-retest coefficient of variation) was 1.6%. There were, however, statistically-significant diurnal changes in the thickness maps. Cartilage thickness decreased by up to 0.6 mm during the day in each of the following three specific locations: the patellofemoral compartment, the lateral tibiofemoral compartment, and the medial tibiofemoral compartment. Elsewhere, cartilage thickness was unchanged or increased by up to 0.5 mm. We conclude that, in asymptomatic young adults, cartilage volume does not change during the day; however, the cartilage does become thinner in locations that encounter the greatest biomechanical force.

Adult↗

PubMed2000

Diet high in monounsaturated fat does not have a different effect on arterial elasticity than a low-fat, high-carbohydrate diet.

OBJECTIVE: To compare the effects of a modified-fat diet high in monounsaturated fat, and a low-fat/high-carbohydrate diet on arterial elasticity. DESIGN: Randomized crossover design; each diet period was 1 month and a 2-week wash out period occurred in between. SUBJECTS/SETTING: Thirty healthy, free-living, nonsmoking men and women were recruited from the Melbourne, Australia, metropolitan region of Australia. Men were aged 35 to 55 years and postmenopausal women were aged 50 to 60 years and were not taking hormone replacement therapy. Twenty-eight subjects completed the study. INTERVENTION: Two diets of equal energy value: a modified-fat diet and a low-fat/high-carbohydrate diet; the modified-fat diet had 3 times more energy from monounsaturated fat. MAIN OUTCOME MEASURES: Arterial elasticity and serum lipoprotein concentrations. STATISTICAL ANALYSIS: The general linear model was used to investigate overall effect and any carryover or order effects. Paired t test and the general linear model were used to compare the results from the 2 diet periods. RESULTS: High-density lipoprotein cholesterol concentration was significantly higher on the modified-fat diet than on the low-fat/low-carbohydrate diet. Arterial elasticity and concentrations of total cholesterol, low-density lipoprotein cholesterol, and triglycerides were not significantly different on the 2 diets. APPLICATIONS/CONCLUSIONS: There is no evidence to favor a diet high in monounsaturated fat over a low-fat/high-carbohydrate diet because of an effect on arterial elasticity. Other changes in diet may be needed to cause a beneficial effect on arterial elasticity.

Adult↗

PubMed2000

Identification and quantification of hydroxamic acids in maize seedling root tissue and impact on western corn rootworm (Coleoptera: Chrysomelidae) larval development.

Hydroxamic acid content was analyzed in the root tissue of four maize, Zea mays L., lines using high-performance liquid chromatography (HPLC) and related to western corn rootworm, Diabrotica virgifera virgifera LeConte, larval development and survivorship. Maize lines evaluated included Mp710 (PI 596627), MpSWCB-4, (PI 550498), Sc213 (PI 548792), and Dk580 (DeKalb commercial hybrid). Maize plants from each line were grown in test tubes containing a transparent agarose gel medium in a growth chamber. After 8 d of growth, root tissue of each line was harvested and hydroxamic acid content analyzed using HPLC. Three hydroxamic acids, 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), 6-methoxybenzoxazolinone (MBOA), and 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA), were identified in the maize roots tested. DIMBOA concentration was quantified and ranged from 246.37 +/- 70.53 micrograms to 91.84 +/- 49.82 micrograms DIMBOA per gram of root tissue. No significant difference was found among lines in D. v. virgifera larval development and survivorship.

Animals↗

PubMed1999

Synthesis, characterization and anticonvulsant activity of enaminones. Part 6: Synthesis of substituted vinylic benzamides as potential anticonvulsants.

A comparison of enaminones from various unsubstituted and p-substituted benzamides to the analogous benzylamines has been undertaken with the aim of elucidating the essential structural parameters necessary for anticonvulsant activity. Initial studies on methyl 4-N-(benzylamino)-6-methyl-2-oxocyclohex-3-en-1-oate, 3a, 3-N-(benzylamino)cyclohex-2-en-1-one, 3p, and 5,5-dimethyl-3-N-(benzylamino)-cyclohex-2-en-1-one, 3r indicated that benzylamines possessed significant anti-maximal electroshock seizure (MES) activity. Evaluation of the analogous benzamides revealed significant differences in anticonvulsant activity, these differences were most probably related to the differences in their three-dimensional structures.

Animals↗

PubMed1999

Structural periodicity in human articular cartilage: comparison between magnetic resonance imaging and histological findings.

OBJECTIVE: To relate the vertical striations visualized in the deeper layers of articular cartilage by Magnetic Resonance Imaging (MRI) to histological features. METHODS: Two knee joints recovered at post-mortem from males in their seventies with no history or visual evidence of joint disease were examined. MR images were obtained in a 4.7 T 400 mm-bore magnet, after which the knees were fixed, sectioned, and examined histologically. RESULTS: High resolution MR showed vertical high/low signal striations with a two to three-fold variation in signal intensity and a periodicity of 0.56 (+/-0.16 mm), most prominent in weight bearing areas. Histological sections revealed alternating light and dark staining areas with a periodicity of 1.01+/-0.54 mm in the lower zones of the cartilage, some, but not all of which clearly represented folding. Given that MR will only visualize vertical structures in cartilage aligned at 90 degrees, whereas histology will cut them at varying angles, it is likely that the vertical structures seen by each modality correspond, and that they represent structural heterogeneity in cartilage; perhaps the presence of plates of high collagen and proteoglycan content. CONCLUSION: The vertical striations seen routinely in the deep zones of hyaline articular cartilage on histological sections are not artefactual; they are likely to represent structural heterogeneity due to the presence of areas of high collagen and high proteoglycan content that exist in weight-bearing areas. This structural heterogeneity may be of great importance to the integrity and function of the cartilage.

Aged↗

PubMed1997

Psychiatric symptoms in offspring of within vs. across racial/ethnic marriages.

A large number of adolescents of interracial ancestry (parents comprising various combinations of African-American, American Indian/Alaska Native, European-American, Chinese, Filipino, Hispanic, Japanese, Korean, Puerto Rican, Samoan, and Tongan ancestry) were contrasted with a monoracial European-American sample in the degree to which they reported symptoms of depression, anxiety, conduct disorder/aggression, and substance abuse. The adolescents of interracial ancestry were subdivided into three groups in terms of parental ancestry: both parents of interracial ancestry, one parent of interracial and the other of monoracial ancestry, and both parents of monoracial but different ancestries. The interracial ancestry groups did not differ significantly from one another or from the European American sample in terms of symptom scores.

Adaptation, Psychological↗

PubMed1996

Magnetic resonance imaging reveals micro-haemorrhage in the feet of diabetic patients with a history of ulceration.

Soft tissue haemorrhage in the foot is a possible precursor of ulceration in patients with diabetic peripheral neuropathy. High resolution 'targetted' magnetic resonance imaging was used to scan the forefoot. Neuropathic patients with and without previous ulceration were matched for degree of neuropathy, mean vibration perception threshold 33.5 +/- 4.2 V (previous ulcer) vs 31.0 +/- 6.9 V (no ulcer), age, sex, and duration of diabetes against non-neuropathic controls. There were nine patients in each category. Paramagnetic materials, e.g. iron compounds, cause a signal void ('drop-out') on gradient-echo images which disappear on spin-echo images. Evidence of haemorrhage was seen in 6 patients with previous ulceration, and none in the other groups (p = 0.009, chi square test). Autologous injection of 20 microliters of blood into the foot of a healthy volunteer produced similar images, a 'drop-out' 1 cm across being visible on magnetic resonance scanning 3 days later. Peak vertical forefoot pressures were not significantly different in the neuropathic groups 0.67 +/- 0.20 vs 0.60 +/- 0.13 Pa but were lower in the non-neuropathic group, 0.43 +/- 0.11 Pa (p = 0.0004, Mann-Whitney), and do not explain the appearance of these haemorrhages. Magnetic resonance imaging provides a sensitive way of detecting micro-haemorrhage and its presence may predict an increased risk of foot ulceration.

Blood Pressure↗