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Biomedical subjects

J E Foster

Publications and source records attributed to J E Foster.

At least 19 recordsLinked to original sources
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

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↗
PubMed1993

Surgical management of hyperparathyroidism at an Air Force medical center.

A critical determinant of successful neck exploration for primary hyperparathyroidism (HPT) is the experience of the surgeon. Results of 17 patients treated surgically for HPT were reviewed to compare results at our medical center with results of large series reported from established national centers. Preoperative laboratory evaluation of 15 patients with surgically proven HPT (solitary adenoma, 14; diffuse hyperplasia, 1) included: mean serum calcium (Ca) 10.9 mg/dl +/- 0.79 and mean serum chloride/phosphate ratio 39 mg/dl +/- 7.9. Serum parathyroid hormone (PTH) was elevated in all patients. Seven neck ultrasounds were performed with a positive predictive value of 42%. No significant operative complications occurred. Mean postoperative serum Ca was 8.34 mg/dl +/- 0.75. One patient had asymptomatic hypocalcemia (Ca = 6.5 mg/dl). Follow-up in 11 patients (65%) at a mean of 8.6 months revealed no evidence of recurrence in these patients. In our experience, proper patient selection and careful surgical technique within established principles for neck exploration and parathyroidectomy lead to excellent results despite the size of the medical center. Patient selection is based on serum Ca, PTH, and chloride/phosphate ratio. Preoperative imaging studies did not appear to be of benefit in the small study reported here.

Adult↗
PubMed1992

An investigation of the acute effect of gentamicin on the renal handling of electrolytes in the rat.

Standard renal clearance techniques were used to investigate the acute effects of gentamicin on renal electrolyte handling in anesthetized rats. Data were obtained before substantial changes in tubular integrity would be expected to occur, thus permitting a distinction between the actions of the drug per se and renal changes resulting from underlying tubular damage. Infusion of gentamicin over a 3-hr period resulted in an immediate and sustained calciuresis and magnesiuresis, with no significant change in the renal clearance of sodium or potassium. Within 60 min of the onset of drug infusion at 0.28 mg/kg/min, renal calcium clearance (ml/min) increased from 0.095 +/- 0.013 to 0.210 +/- 0.016 (P less than .001) and renal magnesium clearance (ml/min) increased from 0.538 +/- 0.059 to 0.662 +/- 0.053 (P less than .01). Because it was subsequently shown that infusion of gentamicin did not alter glomerular filtration rate, it is clear that both responses resulted from a reduced tubular reabsorption of the respective ions; they were rapidly reversible when gentamicin infusion ceased. A higher dose of gentamicin (0.56 mg/kg/min for 3 hr) also significantly decreased plasma magnesium concentrations (0.40 +/- 0.01 vs. 0.49 +/- 0.02 mmol/l, treated vs. control; P less than .01). Gentamicin-induced changes in the renal handling of calcium and magnesium, therefore, occur independently of and before the development of nephrotoxicity. They may be at least partially responsible for the alteration in electrolyte homeostasis seen in humans during aminoglycoside treatment (e.g., hypomagnesemia). It is interesting to speculate on the possibility that they may also in some way contribute to the subsequent cellular injury that is known to occur with prolonged use of gentamicin.

Animals↗
PubMed1987

Rotational artifact in phase imaging of cardiac scans: potential pitfalls in diagnosis.

In the past few years, we have occasionally observed linear bands in the phase images of gated cardiac blood-pool scans along the interventricular septum region among patients with normal septal motions. Our retrospective study investigated the cause of out-of-phase bands of 12 patients. We documented through review of cines, computer analysis of gated cardiac blood-pool scintigraphy data, and correlation with echocardiograms that this phenomenon was artifact introduced by rotational movements of the heart. It is important for nuclear physicians to recognize this rotational artifact on the phase analysis image in order to avoid the erroneous misdiagnosis of wall motion abnormalities of the septum.

Adult↗