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Biomedical subjects

R E Oliver

Publications and source records attributed to R E Oliver.

At least 19 recordsLinked to original sources
PubMed2006

Molecular cytogenetic characterization of four partial wheat-Thinopyrum ponticum amphiploids and their reactions to Fusarium head blight, tan spot, and Stagonospora nodorum blotch.

Four wheat (Triticum aestivum L.)-Thinopyrum ponticum derivatives SS5 (PI604926), SS156 (PI604947), SS363 (PI604970), and SS660 (PI604879), were identified as resistant to Fusarium head blight (FHB), a serious fungal disease of wheat worldwide. Seedling reactions to tan spot and Stagonospora nodorum blotch (SNB), two important foliar diseases of wheat, suggest that these four derivatives are resistant to tan spot and two of them (SS5 and SS156) are resistant to SNB. Fluorescent genomic in situ hybridization (FGISH) patterns of mitotic chromosomes indicate that these four derivatives are partial wheat-Th. ponticum amphiploids, each with a total of 56 chromosomes, though with different amounts of Th. ponticum chromatin. These four amphiploids were hybridized with each other to determine homology between the Th. ponticum genomes in each of the amphiploids. Analysis of chromosome pairing in the F1 hybrids using FGISH suggests that each amphiploid carries a similar set of Th. ponticum chromosomes. These wheat-Th. ponticum amphiploids represent a potential novel source of resistance to FHB, tan spot, and SNB for wheat breeding.

Chromosomes, Plant↗
PubMed2001

A whole-body physiologically based pharmacokinetic model incorporating dispersion concepts: short and long time characteristics.

In whole-body physiologically based pharmacokinetic (PBPK) models, each tissue or organ is frequently portrayed as a single well-mixed compartment with distribution, perfusion rate limited. However, single-pass profiles from isolated organ studies are more adequately described by models which display an intermediate degree of mixing. One such model is the dispersion model, which successfully describes the outflow profiles from the liver and the perfused hindlimb of many compounds, under a variety of conditions. A salient parameter of this model is the dispersion number, a dimensionless term, which characterizes the relative axial spreading of compound on transit through the organ. We have developed a whole-body PBPK model wherein the distribution of drug on transit through each organ is described by the dispersion model with closed boundary conditions incorporated. The model equations were numerically solved using finite differencing methods, in particular, the method of lines. An integrating routine suitable for solving stiff sets of equations was used. Physiological parameters, blood flows, and tissue volumes, were taken from the literature, as were the tissue dispersion numbers, which characterize the mixing properties of each tissue; where none could be found, the value was set as that for liver. On solution, tissue, venous and arterial blood concentration-time profiles are generated. The profiles exhibited both short and long time characteristics. Oscillations were observed in the venous and arterial profiles over the first 10 min of simulation for the rat. On scale-up to human, the effects were seen over a 30 min period. Longer time effects of tissue distribution involve buildup of drug in the large tissues of distribution: skeletal muscle, skin, and adipose. The extent of distribution in the large tissues was somewhat dependent on the magnitude of the dispersion number, the lower the dispersion number, the greater the extent of distribution after an intravenous bolus dose. The model has a distinct advantage over the well-stirred organ whole-body PBPK model in its ability to describe both short and long time characteristics.

Animals↗
PubMed1998

What surface of the intestinal epithelium is effectively available to permeating drugs?

A mathematical model is presented which examines the extent to which the intestinal epithelium is accessed by drug molecules. Morphological information from the literature for the jejunum, ileum, and colon of the rat and for human jejunum was incorporated. Perturbation theory was used to derive the limiting cases for total access to the entire epithelial surface, for transport by diffusion and by diffusion with convection, respectively. A parameter gamma = square root of (Ph2)/(Db) was identified to provide a measure of the ability of drug molecules to access the entire epithelial surface down to the crypt wells, where P is the cell permeability, D the aqueous diffusion coefficient, h the channel depth between the villi, and b is half the width of the idealized intervillous channel. When gamma << 1, diffusion is not a limitation and the entire surface is fully utilized for absorption of drug. This condition arises with drugs of low permeability and is more likely to be met with colonic than small intestinal epithelium. When gamma >/= 1, diffusion becomes a limitation and then not all of the epithelial surface is functionally accessible to drug molecules, a condition most likely to prevail with drugs of high permeability traversing the jejunum. Furthermore, water flux per se is predicted to have relatively little influence on enhancing surface accessibility. This simple, but quantitative approach showed that the ranking order of permeability jejunum >ileum> colon for low permeable drugs can at least in part be explained by the differences in surface amplification between these different epithelial regions. The analysis also indicates that for highly permeable drugs extreme caution should be exercised in extrapolating permeability measurements in vitro across various preparations and to events in vivo.

Animals↗
PubMed1997

Ki-67 antigen staining as an adjunct to identifying cervical intraepithelial neoplasia.

The purpose of the work was to determine the feasibility and predictive value of Ki-67 immunostaining of cervical cytology and the detection of cervical dysplasia. Air-dried cervical smears were stained with MIB-1 antibody to identify the Ki-67 antigen. Nuclear decoration in abnormal squamous nuclei determined immunoreactivity. One hundred twenty-four nonpregnant patients underwent colposcopy and directed biopsies for abnormal cytology. Sensitivity (0.89), specificity (0.65), positive predictive value (0.60), and negative predictive value (0.91) were found for Ki-67 immunostaining in detection of high-grade cervical intraepithelial neoplasia (CIN) in 124 patients and positive Ki-67 staining was a significant predictor of high-grade CIN in both univariate (odds ratio 15.5 (95% CI 5.5-43.8) and multivariable (odds ratio 21.5 (95% CI 5.0-92.0) analysis. In 101 patients with ASCUS and LGSIL, Ki-67 immunostaining demonstrated the following in detection of high-grade CIN: sensitivity (0.96), specificity (0.67), positive predictive value (0.49), and negative predictive value (0.98). Ki-67 immunostaining of cervical cytology is a predictor of significant cervical pathology with high sensitivity and negative predictive value. Ki-67 immunostaining of cervical cytology may represent a new and cost-effective triage tool for patients with minor abnormalities on cytology.

Adolescent↗
PubMed1997

A physiologically based pharmacokinetic model incorporating dispersion principles to describe solute distribution in the perfused rat hindlimb preparation.

A physiologically based pharmacokinetic model incorporating dispersion principles has been developed to describe outflow data from the isolated perfused rat hindlimb preparation, for the three reference markers 14C-sucrose, 14C-urea, and 3H-water and three 14C-labeled 5-n-alkyl-5-ethyl barbiturates; the methyl, butyl, and nonyl homologues. Also 51Cr-RBC and 125I-albumin were studied. The model consists of four parallel components representing each of the tissues comprising the hindlimb: skeletal muscle, skin, bone, and adipose. Attempts to simplify the model by using the principle of tissue lumping were made by examining the tissue equilibration rate constant k tau for each of respective tissues for each compound. It was found that simplification was only possible in the case of 3H-water data. The model took into account a possible shunting component in the skin tissue and incomplete mass but not volumetric recovery from the system. The dispersion model characterizes the relative spreading of solute on transit through a tissue bed by a dimension-less parameter DN. The estimated dispersion numbers (DN) obtained were in the region of 2.7-4.72, 8.39-15.54, 0.61-2.74, and 6.02-14.0 for skeletal muscle, skin, bone, and adipose, respectively, and were independent of the compound studied. These values are much larger than the range reported in the literature for hepatic outflow data, DN = 0.2-0.5, and suggest a greater heterogeneity of vascular flow in the different component tissues of the rat hindlimb.

Albumins↗
PubMed1996

Protocol for immunocytochemical detection of SIL in cervical smears using MIB-1 antibody to Ki-67 [corrected].

Ki-67 nuclear antigen is expressed in upper epithelial levels of intraepithelial neoplasia of the cervix and vulva, variably in condyloma, and in basal and parabasal cells of normal squamous mucosa in histologic preparations. The application of antibodies to Ki-67 as a marker of squamous intraepithelial lesions in cervical smears was explored using either air-dried, acetone-fixed cervical smears obtained from 106 consenting patients or a single slide from archival two-slide cases of squamous intraepithelial lesions MIB-1 monoclonal antibody to Ki-67 was tested using two immunocytochemical techniques. In one set of smears, avidin-biotin peroxidase was used for detection and diaminobenzidine with H2O2 as the chromogen. Some specimens were incubated with 0.3% H2O2 and phosphate buffered saline for blockade of endogenous peroxidase. Alternatively, other air-dried smears were stained using alkaline phosphatase antialkaline phosphatase for detection and new fuchsin as the chromogen. Nuclear staining in squamous intraepithelial lesions was identified in air-dried smears using all of the above methods. Slides stained with avidin-biotin peroxidase and blocked with 0.3% H2O2 and phosphate buffered saline showed less background staining from neutrophils and erythrocytes compared with those without blocking. Slides stained using alkaline phosphatase antialkaline phosphatase showed excessive cytoplasmic staining of endocervical cells, making intraepithelial difficult. No nuclear staining of squamous intraepithelial lesions was observed in destained archival smears. Air-dried smears blocked with 0.3% H2O2 and phosphate buffered saline, incubated with MIB-1, and stained using avidin-biotin peroxidase gave the best results for identification of Ki-67 expression in squamous intraepithelial lesions.

Antibodies, Monoclonal↗
PubMed1995

Characterization of zinc uptake and its regulation by arachidonic acid in fetal type II pneumocytes.

In freshly isolated fetal guinea pig type II pneumocytes, zinc uptake is time and temperature dependent. Two pathways of uptake exist, resulting in a rapid phase that reaches a steady state within 30 s and a slower linear phase that does not attain a steady state within 60 min. Both processes exhibit saturation kinetics. The rapid phase has a maximal zinc uptake of 60.7 +/- 9.3 pmol.10(6) cells-1.30 s-1 and an apparent affinity (Kt) of 13.7 +/- 5.4 microM. The maximum velocity of uptake (Vmax) of the slower phase is 24.6 +/- 1.9 pmol.10(6) cells-1.min-1 with a Kt of 22.0 +/- 3.6 microM. Epinephrine, terbutaline, dibutyryl adenosine 3',5'-cyclic monophosphate, and dexamethasone have no significant effect on zinc uptake, while arachidonic acid (AA) stimulates. Dose-response data of AA-stimulated zinc uptake gives an apparent K0.5 of 0.42 +/- 0.01 microM and a Hill coefficient of 1. The maximal uptake in the rapid phase is significantly increased to 146.8 +/- 12.4 pmol.10(6) cells-1.30 s-1 and in the slow phase, the Vmax for zinc uptake is also significantly increased to 33.0 +/- 1.8 pmol.10(6) cells-1.min-1 by 10 microM AA. However, the Kt values in both processes remain unchanged after AA stimulation. The effect is not mediated by either leukotrienes or prostaglandins but can be mimicked by other unsaturated fatty acids.

Animals↗
PubMed1988

Detection of foot-and-mouth disease antigen in bovine epithelial samples: comparison of sites of sample collection by an enzyme linked immunosorbent assay (ELISA) and complement fixation test.

Serially collected epithelial samples from lesions in the mouth and on the feet of calves experimentally infected with foot-and-mouth disease (FMD) type O1 BFS 1860 were assayed for the presence of FMD viral antigen using a double antibody sandwich enzyme-linked immunosorbent assay (ELISA) and a complement fixation (CF) test. The amount of infectious virus in each sample was also determined. FMD viral antigen was detected by ELISA in 70 per cent of the mouth samples and 92 per cent of samples from the feet. The CF test was less sensitive; it detected antigen in 44 per cent of mouth and 85 per cent of foot samples. In mouth samples the amount of antigen decreased rapidly becoming undetectable by the fourth day of sampling whereas in foot samples the quantity of antigen declined more slowly, and could be detected until the seventh day of sampling. Therefore it was concluded that the age of lesion and the site from which epithelial samples are collected are both important determinants in the laboratory diagnosis of FMD. In cattle, foot lesions are more likely than mouth lesions to yield antigen and to remain positive for a longer period.

Animals↗
PubMed1988

Immunogenicity, pathogenicity, and transmissibility of a recombinant vaccinia virus in calves.

Experiments concerned with the immunogenicity, pathogenicity, and transmissibility of a recombinant vaccinia:Sindbis virus were conducted. The WR strain of the recombinant vaccinia:Sindis virus was found to be infective for calves and mildly pathogenic, resulting in local tissue reaction. It was not transmissible to other calves. Also, it was found to be immunogenic when inoculated intradermally into calves, and antibody was produced against the parent vector virus (vaccinia) and the Sindbis antigen. Recombinant virus given IV to calves induced no detectable clinical signs, nor did the calves develop neutralizing antibodies. Furthermore, second-passage lesion material containing up to 10(7) tissue culture infective doses of the recombinant virus failed to induce development of lesions or illness in intradermally inoculated calves, and virus could not be recovered from the inoculation sites. In this series of experiments, this vaccinia recombinant given intradermally was immunogenic, mildly pathogenic at the local injection site only, and was not transmissible to contact animals, thus demonstrating the potential efficacy and safety of the WR strain of vaccinia virus when used as a live vector system in cattle.

Animals↗
PubMed1987

A successful attempt to raise goat kids free of infection with caprine arthritis encephalitis virus in an endemically infected goat herd.

Goat kids from a herd endemically infected with caprine arthritis encephalitis (CAE) virus were raised according to 3 methods. One group of ten goat kids was removed from infected does at birth before suckling or licking by the doe could occur (snatch birth technique). Kids were fed on goat colostrum, which had been heated to 57 degrees C for ten minutes and then held in a thermos flask for one hour. Subsequently the kids were fed reconstituted spray dried cows' milk powder. They were raised apart from infected goats with separation maintained by a wire fence. Contact occurred across-the-fence. Passively acquired serum antibody to CAE virus was detected in some kids at two to three months of age. Nine of the ten goats were negative for serum antibody to CAE virus when tested at 5-6, 9 and 12 months of age. One goat was positive at three and nine months of age but was negative when tested at 12 months of age. A second group of four kids was removed at birth and fed heat-treated goat colostrum, followed by milk from CAE virus-infected does. All four kids became infected with CAE virus; they developed serum antibody to CAE virus between 5-6 and 9 months of age. A third group of two kids was not removed from their infected dams. Both kids were infected at 5-6 and 9 months of age.

Journal Article↗
PubMed1987

A vesiculo-bullous disease in pigs resembling foot and mouth disease. I. Field cases.

Eleven incidents of bullae and vesicles on the snouts and less frequently the feet of white-skinned pigs on seven farms are described. Bullous and vesicular lesions up to 5 cm in diameter and containing clotted gelatinous fluid were located on the dorsal aspect of the snout, behind the flange. Lesions ruptured, became ulcerated, developed scabs and healed within three weeks. There was no transmission to other pigs or ruminants. The condition was associated with contact with green vegetable material containing parsnips (Pastinaca sativa) or celery (Apium graveolens), followed by exposure to periods of extended sunshine. Parsnips and celery are known to contain furocoumarins, potent phototoxic compounds. It is suggested that absorption of furocoumarins on the skin of the snout and feet after contact with parsnips and celery and exposure to ultraviolet light caused the lesions in the cases reported. It is postulated that a similar condition may have been responsible for national foot and mouth disease scares in pigs at Warkworth and Temuka in New Zealand and at Legana in Tasmania.

Journal Article↗
PubMed1987

A vesiculo-bullous disease in pigs resembling foot and mouth disease. II. Experimental reproduction of the lesion.

Vesiculo-bullous dermatitis of pigs characterised by presence of vesicles and bullae on the snout and feet of white skinned pigs was reproduced experimentally. Leaves of parsnips (Pastinaca sativa), or celery (Apium graveolens) infected with the fungus Sclerotinia sclerotiorum were fed or rubbed on the snouts and feet of white skinned pigs. Pigs were then exposed to sunlight or to UV light of intensity approximately 212 m W/M2 at a wavelength 340-360 nm for eight hours per day until vesicles developed. All treated pigs developed lesions on the snouts, and less frequently on the feet. Lesions were characterised by the appearance of erythema at 24 hours after treatment. Vesicles developed at 48 hours and became maximal by 72 hours. Pigs treated with plant material without exposure to UV light or exposed to UV light without contact with plant material did not develop lesions. The experimental lesions closely resemble those observed in several field cases in 1984 and 1985 in New Zealand and to lesions present in three well publicized foot and mouth disease scares at Warkworth, and Temuka in New Zealand and Legana in Tasmania.

Journal Article↗